Science.gov

Sample records for gravitational microlensing events

  1. Gravitational Microlensing Events as a Target for the SETI project

    NASA Astrophysics Data System (ADS)

    Rahvar, Sohrab

    2016-09-01

    The detection of signals from a possible extrasolar technological civilization is one of the most challenging efforts of science. In this work, we propose using natural telescopes made of single or binary gravitational lensing systems to magnify leakage of electromagnetic signals from a remote planet that harbors Extraterrestrial Intelligent (ETI) technology. Currently, gravitational microlensing surveys are monitoring a large area of the Galactic bulge to search for microlensing events, finding more than 2000 events per year. These lenses are capable of playing the role of natural telescopes, and, in some instances, they can magnify radio band signals from planets orbiting around the source stars in gravitational microlensing systems. Assuming that the frequency of electromagnetic waves used for telecommunication in ETIs is similar to ours, we propose follow-up observation of microlensing events with radio telescopes such as the Square Kilometre Array (SKA), the Low Frequency Demonstrators, and the Mileura Wide-Field Array. Amplifying signals from the leakage of broadcasting by an Earth-like civilization will allow us to detect them as far as the center of the Milky Way galaxy. Our analysis shows that in binary microlensing systems, the probability of amplification of signals from ETIs is more than that in single microlensing events. Finally, we propose the use of the target of opportunity mode for follow-up observations of binary microlensing events with SKA as a new observational program for searching ETIs. Using optimistic values for the factors of the Drake equation provides detection of about one event per year.

  2. Photometric, astrometric and polarimetric observations of gravitational microlensing events

    NASA Astrophysics Data System (ADS)

    Sajadian, Sedighe; Rahvar, Sohrab

    2015-09-01

    Gravitational microlensing can be used as a unique astrophysical tool to study the atmospheres of stars thousands of parsec away from us. This capability results from the bending of light rays in the gravitational field of a lens that can magnify the light of a background source star during the lensing. Moreover, one of the consequences of this light bending is that the circular symmetry of the source is broken because distorted images are produced at either side of the lens position. This property makes it possible to observe polarization, and also the light centroid shift of images. Assigning vectors for these two parameters, they are perpendicular to each other in simple and binary microlensing events, except in fold singularities. In this work, we investigate the advantages of polarimetric and astrometric observations during microlensing events (i) for studying the surface of the source star and spots on it and (ii) for obtaining extra information to determine the trajectory of source stars with respect to the lens. Finally, we analyse the largest sample of microlensing events from the Optical Gravitational Lensing Experiment (OGLE) catalogue and show that, for almost ˜4.3 per cent of events in the direction of the Galactic bulge, the polarization signals would be observable with large telescopes.

  3. Detectability of GW150914-like events by gravitational microlensing

    NASA Astrophysics Data System (ADS)

    Eilbott, Daniel; Riley, Alexander; Cohn, Jonathan; Kesden, Michael H.; King, Lindsay J.

    2017-01-01

    The recent discovery of gravitational waves from stellar-mass binary black holes (BBHs) provided direct evidence of the existence of these systems. These BBHs would have gravitational microlensing signatures that are, due to their large masses and small separations, distinct from single-lens signals. We apply Bayesian statistics to examine the distinguishability of BBH microlensing events from single-lens events under ideal observing conditions, using modern photometric and astrometric capabilities. Given one year of ideal observations, a source star at the Galactic center, a GW150914-like BBH lens (total mass 65 M⊙, mass ratio 0.8) at half that distance, and an impact parameter of 0.4 Einstein radii, we find that BBH separations down to 0.00634 Einstein radii are detectable, which is < 0.00716 Einstein radii, the limit at which the BBH would merge within the age of the universe. We encourage analyses of LSST data to search for similar modulation in all long-duration events, providing a new channel for the discovery of short-period BBHs in our Galaxy.

  4. Candidate gravitational microlensing events for future direct lens imaging

    SciTech Connect

    Henderson, C. B.; Gould, A.; Gaudi, B. S.; Park, H.; Han, C.; Sumi, T.; Koshimoto, N.; Udalski, A.; Tsapras, Y.; Bozza, V.; Abe, F.; Fukunaga, D.; Itow, Y.; Masuda, K.; Bennett, D. P.; Bond, I. A.; Ling, C. H.; Botzler, C. S.; Freeman, M.; Fukui, A.; Collaboration: MOA Collaboration; OGLE Collaboration; μFUN Collaboration; RoboNet Collaboration; and others

    2014-10-10

    The mass of the lenses giving rise to Galactic microlensing events can be constrained by measuring the relative lens-source proper motion and lens flux. The flux of the lens can be separated from that of the source, companions to the source, and unrelated nearby stars with high-resolution images taken when the lens and source are spatially resolved. For typical ground-based adaptive optics (AO) or space-based observations, this requires either inordinately long time baselines or high relative proper motions. We provide a list of microlensing events toward the Galactic bulge with high relative lens-source proper motion that are therefore good candidates for constraining the lens mass with future high-resolution imaging. We investigate all events from 2004 to 2013 that display detectable finite-source effects, a feature that allows us to measure the proper motion. In total, we present 20 events with μ ≳ 8 mas yr{sup –1}. Of these, 14 were culled from previous analyses while 6 are new, including OGLE-2004-BLG-368, MOA-2005-BLG-36, OGLE-2012-BLG-0211, OGLE-2012-BLG-0456, MOA-2012-BLG-532, and MOA-2013-BLG-029. In ≲12 yr from the time of each event the lens and source of each event will be sufficiently separated for ground-based telescopes with AO systems or space telescopes to resolve each component and further characterize the lens system. Furthermore, for the most recent events, comparison of the lens flux estimates from images taken immediately to those estimated from images taken when the lens and source are resolved can be used to empirically check the robustness of the single-epoch method currently being used to estimate lens masses for many events.

  5. Candidate Gravitational Microlensing Events for Future Direct Lens Imaging

    NASA Astrophysics Data System (ADS)

    Henderson, C. B.; Park, H.; Sumi, T.; Udalski, A.; Gould, A.; Tsapras, Y.; Han, C.; Gaudi, B. S.; Bozza, V.; Abe, F.; Bennett, D. P.; Bond, I. A.; Botzler, C. S.; Freeman, M.; Fukui, A.; Fukunaga, D.; Itow, Y.; Koshimoto, N.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Namba, S.; Ohnishi, K.; Rattenbury, N. J.; Saito, To; Sullivan, D. J.; Suzuki, D.; Sweatman, W. L.; Tristram, P. J.; Tsurumi, N.; Wada, K.; Yamai, N.; Yock, P. C. M.; Yonehara, A.; MOA Collaboration; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Skowron, J.; Kozłowski, S.; Poleski, R.; Ulaczyk, K.; Wyrzykowski, Ł.; Pietrukowicz, P.; OGLE Collaboration; Almeida, L. A.; Bos, M.; Choi, J.-Y.; Christie, G. W.; Depoy, D. L.; Dong, S.; Friedmann, M.; Hwang, K.-H.; Jablonski, F.; Jung, Y. K.; Kaspi, S.; Lee, C.-U.; Maoz, D.; McCormick, J.; Moorhouse, D.; Natusch, T.; Ngan, H.; Pogge, R. W.; Shin, I.-G.; Shvartzvald, Y.; Tan, T.-G.; Thornley, G.; Yee, J. C.; μFUN Collaboration; Allan, A.; Bramich, D. M.; Browne, P.; Dominik, M.; Horne, K.; Hundertmark, M.; Figuera Jaimes, R.; Kains, N.; Snodgrass, C.; Steele, I. A.; Street, R. A.; RoboNet Collaboration

    2014-10-01

    The mass of the lenses giving rise to Galactic microlensing events can be constrained by measuring the relative lens-source proper motion and lens flux. The flux of the lens can be separated from that of the source, companions to the source, and unrelated nearby stars with high-resolution images taken when the lens and source are spatially resolved. For typical ground-based adaptive optics (AO) or space-based observations, this requires either inordinately long time baselines or high relative proper motions. We provide a list of microlensing events toward the Galactic bulge with high relative lens-source proper motion that are therefore good candidates for constraining the lens mass with future high-resolution imaging. We investigate all events from 2004 to 2013 that display detectable finite-source effects, a feature that allows us to measure the proper motion. In total, we present 20 events with μ >~ 8 mas yr-1. Of these, 14 were culled from previous analyses while 6 are new, including OGLE-2004-BLG-368, MOA-2005-BLG-36, OGLE-2012-BLG-0211, OGLE-2012-BLG-0456, MOA-2012-BLG-532, and MOA-2013-BLG-029. In lsim12 yr from the time of each event the lens and source of each event will be sufficiently separated for ground-based telescopes with AO systems or space telescopes to resolve each component and further characterize the lens system. Furthermore, for the most recent events, comparison of the lens flux estimates from images taken immediately to those estimated from images taken when the lens and source are resolved can be used to empirically check the robustness of the single-epoch method currently being used to estimate lens masses for many events.

  6. Detecting binarity of GW150914-like lenses in gravitational microlensing events

    NASA Astrophysics Data System (ADS)

    Kesden, Michael; Eilbott, Daniel; Riley, Alexander; Cohn, Jonathan; King, Lindsay

    2017-01-01

    The recent discovery of gravitational waves from stellar-mass binary black holes (BBHs) provided direct evidence of the existence of these systems. These BBHs would have gravitational microlensing signatures that are, due to their large masses and small separations, distinct from single-lens signals. We apply Bayesian statistics to examine the distinguishability of BBH microlensing events from single-lens events under ideal observing conditions, using modern photometric and astrometric capabilities. Given one year of ideal observations, a source star at the Galactic center, a GW150914-like BBH lens (total mass 65 solar masses, mass ratio 0.8) at half that distance, and an impact parameter of 0.4 Einstein radii, we find that BBHs with separations down to 0.00634 Einstein radii are detectable, marginally below the separation at which such systems would merge due to gravitational radiation with the age of the Universe. Supported by Alfred P Sloan Foundation Grant No. RG- 2015-65299 and NSF Grant No. PHY-1607031.

  7. Data analysis of MOA for Gravitational Microlensing events with durations Less than 2 days by using brown dwarf population

    NASA Astrophysics Data System (ADS)

    Hassani, Sh.

    2016-12-01

    Gravitational Microlensing is one of the most powerful methods of detecting very low mass objects like Exoplanets and Brown dwarfs. The most important parameter that we can extract from a microlensing event is the Einstein radius crossing time tE. In this work, by performing Monte-Carlo simulation, we obtain tE distribution for brown dwarf population. Then we show that this population can be a good candidate for very short microlensing events with tE<2 days. The data set used in this analysis was taken in 2006 and 2007 seasons by the MOA-II survey, using the 1.8-m MOA-II telescope located at the Mt. John University Observatory, New Zealand.

  8. Study by MOA of extrasolar planets in gravitational microlensing events of high magnification

    NASA Astrophysics Data System (ADS)

    Bond, I. A.; Rattenbury, N. J.; Skuljan, J.; Abe, F.; Dodd, R. J.; Hearnshaw, J. B.; Honda, M.; Jugaku, J.; Kilmartin, P. M.; Marles, A.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Nakamura, T.; Nankivell, G.; Noda, S.; Noguchi, C.; Ohnishi, K.; Reid, M.; Saito, To.; Sato, H.; Sekiguchi, M.; Sullivan, D. J.; Sumi, T.; Takeuti, M.; Watase, Y.; Wilkinson, S.; Yamada, R.; Yanagisawa, T.; Yock, P. C. M.

    2002-06-01

    A search for extrasolar planets was carried out in three gravitational microlensing events of high magnification, MACHO 98-BLG-35, MACHO 99-LMC-2 and OGLE 00-BUL-12. Photometry was derived from observational images by the MOA and OGLE groups using an image subtraction technique. For MACHO 98-BLG-35, additional photometry derived from the MPS and PLANET groups was included. Planetary modelling of the three events was carried out in a supercluster computing environment. The estimated probability for explaining the data on MACHO 98-BLG-35 without a planet is <1 per cent. The best planetary model has a planet of mass ~(0.4-1.5)×MEarth at a projected radius of either ~1.5 or ~2.3au. We show how multiplanet models can be applied to the data. We calculate exclusion regions for the three events and find that Jupiter-mass planets can be excluded with projected radii from as wide as about 30au to as close as around 0.5au for MACHO 98-BLG-35 and OGLE 00-BUL-12. For MACHO 99-LMC-2, the exclusion region extends out to around 10au and constitutes the first limit placed on a planetary companion to an extragalactic star. We derive a particularly high peak magnification of ~160 for OGLE 00-BUL-12. We discuss the detectability of planets with masses as low as Mercury in this and similar events.

  9. Confirmation of the Planetary Origin of the Gravitational Microlensing Event OGLE-2006-BLG-0169

    NASA Astrophysics Data System (ADS)

    Barry, Richard K.; Bennett, David P.; Bhattacharya, Aparna; Anderson, Jay; Bond, Ian; Anderson, Nyki; Batista, Virgini; Beaulieu, Jean-philippe; Depoy, Darren L.; Dong, Subo; Gaudi, B. Scott; Gould, Andrew; Gilbert, Emily; Pfeifle, Ryan; Pogge, Richard W.; Terry, Sean; Udalski, Andrzej

    2016-01-01

    We present Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) observations of the source and lens stars for planetary microlensing event OGLE-2005-BLG-169, which confirm the relative proper motion prediction due to the planetary light curve signal observed for this event. This (and the companion Keck result) provide the first confirmation of a planetary microlensing signal, for which the deviation was only 2%. The follow-up observations determine the flux of the planetary host star in multiple passbands and remove light curve model ambiguity caused by sparse sampling of part of the light curve. This leads to a precise determination of the properties of the OGLE-2005-BLG-169Lb planetary system.

  10. Exoplanet searches with gravitational microlensing

    NASA Astrophysics Data System (ADS)

    Zakharov, Alexander

    2012-07-01

    Depending on gravitational lens masses, people are speaking about different regimes of gravitational lensing or more precisely, different regimes correspond to different angular distances, assuming that lenses and sources are located at cosmological distances. If a gravitational lens has a stellar mass, the regime is called microlensing. Since a distance between images depends on a square root of a lens mass, a regime for a lens with a planet mass (10^{-6} M_{⊙}) is called nanolensing. Therefore, searches for light exoplanets with gravitational lensing may be called nanolensing. There are different techniques to find exoplanets such as Doppler shift measurements, transits, pulsar timing, astrometrical measurements. It was noted that gravitational microlensing is the most promising technique to find exoplanets near the habitable zone with a temperature at exoplanet surface in the range 1 - 100° C (or in the temperature range for temperature of liquid water).

  11. Interpretation of a short-term anomaly in the gravitational microlensing event MOA-2012-BLG-486

    SciTech Connect

    Hwang, K.-H.; Choi, J.-Y.; Han, C.; Bond, I. A.; Sumi, T.; Koshimoto, N.; Gaudi, B. S.; Gould, A.; Bozza, V.; Beaulieu, J.-P.; Tsapras, Y.; Abe, F.; Fukunaga, D.; Itow, Y.; Bennett, D. P.; Botzler, C. S.; Freeman, M.; Chote, P.; Harris, P.; Fukui, A.; Collaboration: MOA Collaboration; μFUN Collaboration; PLANET Collaboration; RoboNet Collaboration; and others

    2013-11-20

    A planetary microlensing signal is generally characterized by a short-term perturbation to the standard single lensing light curve. A subset of binary-source events can produce perturbations that mimic planetary signals, thereby introducing an ambiguity between the planetary and binary-source interpretations. In this paper, we present the analysis of the microlensing event MOA-2012-BLG-486, for which the light curve exhibits a short-lived perturbation. Routine modeling not considering data taken in different passbands yields a best-fit planetary model that is slightly preferred over the best-fit binary-source model. However, when allowed for a change in the color during the perturbation, we find that the binary-source model yields a significantly better fit and thus the degeneracy is clearly resolved. This event not only signifies the importance of considering various interpretations of short-term anomalies, but also demonstrates the importance of multi-band data for checking the possibility of false-positive planetary signals.

  12. Real Time Gravitational Microlensing in OGLE experiment

    NASA Astrophysics Data System (ADS)

    Udalski, Andrzej; Szymanski, Michal

    1998-05-01

    The Early Warning System (EWS) designed for detection of microlensing events in progress has been implemented for the second phase of the Optical Gravitational Lensing Experiment - OGLE-2. Information about detected events in progress is available on WWW page and Anonymous FTP. Astronomers interested in e-mail notification, are requested to send an e-mail to ogle-ews@sirius.astrouw.edu.pl.

  13. Constraint on Additional Planets in Planetary Systems Discovered Through the Channel of High-magnification Gravitational Microlensing Events

    NASA Astrophysics Data System (ADS)

    Shin, I.-G.; Han, C.; Choi, J.-Y.; Hwang, K.-H.; Jung, Y.-K.; Park, H.

    2015-04-01

    High-magnification gravitational microlensing events provide an important channel of detecting planetary systems with multiple giants located at their birth places. In order to investigate the potential existence of additional planets, we reanalyze the light curves of the eight high-magnification microlensing events, for each of which a single planet was previously detected. The analyzed events include OGLE-2005-BLG-071, OGLE-2005-BLG-169, MOA-2007-BLG-400, MOA-2008-BLG-310, MOA-2009-BLG-319, MOA-2009-BLG-387, MOA-2010-BLG-477, and MOA-2011-BLG-293. We find that including an additional planet improves fits with {Δ }{{χ }2}\\lt 80 for seven out of eight analyzed events. For MOA-2009-BLG-319, the improvement is relatively big with {Δ }{{χ }2}∼ 143. From inspection of the fits, we find that the improvement of the fits is attributed to systematics in data. Although no clear evidence of additional planets is found, it is still possible to constrain the existence of additional planets in the parameter space. For this purpose, we construct exclusion diagrams showing the confidence levels excluding the existence of an additional planet as a function of its separation and mass ratio. We also present the exclusion ranges of additional planets with 90% confidence level for Jupiter-, Saturn-, and Uranus-mass planets.

  14. Measuring polarization in microlensing events

    NASA Astrophysics Data System (ADS)

    Ingrosso, G.; Calchi Novati, S.; De Paolis, F.; Jetzer, Ph.; Nucita, A. A.; Strafella, F.

    2015-01-01

    We reconsider the polarization of the star light that may arise during microlensing events due to the high gradient of magnification across the atmosphere of the source star, by exploring the full range of microlensing and stellar physical parameters. Since it is already known that only cool evolved giant stars give rise to the highest polarization signals, we follow the model by Simmons et al. to compute the polarization as due to the photon scattering on dust grains in the stellar wind. Motivated by the possibility to perform a polarization measurement during an ongoing microlensing event, we consider the recently reported event catalogue by the Optical Gravitational Lensing Experiment (OGLE) collaboration covering the 2001-2009 campaigns (OGLE-III events), that makes available the largest and more comprehensive set of single-lens microlensing events towards the Galactic bulge. The study of these events, integrated by a Monte Carlo analysis, allows us to estimate the expected polarization profiles and to predict for which source stars and at which time is most convenient to perform a polarization measurement in an ongoing event. We find that about two dozens of OGLE-III events (about 1 per cent of the total) have maximum polarization degree in the range 0.1 < Pmax < 1 per cent, corresponding to source stars with apparent magnitude I ≲ 14.5, being very cool red giants. This signal is measurable by using the FOcal Reducer and low dispersion Spectrograph (FORS2) polarimeter at Very Large Telescope (VLT) telescope with about 1 h integration time.

  15. Dark Matter Detection with Gravitational Microlensing

    NASA Astrophysics Data System (ADS)

    Pratt, Mark Robin

    There is overwhelming evidence that the majority of the mass in ordinary galaxies like our own is undetected by its absorption or emission of light. If this mass is in the form of massive compact halo objects (Machos) it can be detected through its gravitational microlensing of background stars. The MACHO Project is searching for this Galactic dark matter by monitoring millions of stars in the Magellanic Clouds and Galactic bulge in an attempt to detect rare microlensing events caused by otherwise invisible Machos. Analysis of two years of photometry on 8.5 million stars in the Large Magellanic Cloud (LMC) reveals 8 candidate microlensing events. Detailed calibrations including characterization of our confusion limited photometry allow us to calculate a mass for the entire lensing population and to compare the observed event rate with both that expected from known stars and that expected for the dark matter. We find that only ~1 event should be expected from lensing by stars in known galactic populations. From these eight events we estimate the optical depth towards the LMC from events with duration 2Event time scales yield a most probable Macho mass of 0.5-0.2+0.3Msolar, although this value is quite model dependent. The absence of short timescale microlensing events allows us to exclude Machos in the mass range ~10-4-0.03Msolar as significant contributors to the Galactic dark matter.

  16. Microlensing Event Caustic Crossing

    NASA Astrophysics Data System (ADS)

    MACHO/GMAN Collaboration

    1998-06-01

    The MACHO/GMAN Collaboration (cf. IAUC 6845) plus affiliate S.Rhie report that further observations of microlensing event MACHO-98-SMC-1 (R.A. = 0h45m35s.2, Decl. = -72o52'34" J2000) confirm the binary lens interpretation and yield a prediction for the time of the 2nd caustic crossing: June 19.2 +/- 1.5 UT. The confirming observations were obtained with the MSO 1.3m MACHO survey telescope and the CTIO 0.9-m telescope.

  17. REANALYSES OF ANOMALOUS GRAVITATIONAL MICROLENSING EVENTS IN THE OGLE-III EARLY WARNING SYSTEM DATABASE WITH COMBINED DATA

    SciTech Connect

    Jeong, J.; Park, H.; Han, C.; Gould, A.; Poleski, R.; Udalski, A.; Szymański, M. K.; Pietrzyński, G.; Soszyński, I.; Ulaczyk, K.; Wyrzykowski, Ł.; Abe, F.; Fukunaga, D.; Itow, Y.; Bennett, D. P.; Bond, I. A.; Botzler, C. S.; Freeman, M.; Fukui, A.; Koshimoto, N.; Collaboration:; and others

    2015-05-01

    We reanalyze microlensing events in the published list of anomalous events that were observed from the Optical Gravitational Lensing Experiment (OGLE) lensing survey conducted during the 2004–2008 period. In order to check the existence of possible degenerate solutions and extract extra information, we conduct analyses based on combined data from other survey and follow-up observation and consider higher-order effects. Among the analyzed events, we present analyses of eight events for which either new solutions are identified or additional information is obtained. We find that the previous binary-source interpretations of five events are better interpreted by binary-lens models. These events include OGLE-2006-BLG-238, OGLE-2007-BLG-159, OGLE-2007-BLG-491, OGLE-2008-BLG-143, and OGLE-2008-BLG-210. With additional data covering caustic crossings, we detect finite-source effects for six events including OGLE-2006-BLG-215, OGLE-2006-BLG-238, OGLE-2006-BLG-450, OGLE-2008-BLG-143, OGLE-2008-BLG-210, and OGLE-2008-BLG-513. Among them, we are able to measure the Einstein radii of three events for which multi-band data are available. These events are OGLE-2006-BLG-238, OGLE-2008-BLG-210, and OGLE-2008-BLG-513. For OGLE-2008-BLG-143, we detect higher-order effects induced by the changes of the observer’s position caused by the orbital motion of the Earth around the Sun. In addition, we present degenerate solutions resulting from the known close/wide or ecliptic degeneracy. Finally, we note that the masses of the binary companions of the lenses of OGLE-2006-BLG-450 and OGLE-2008-BLG-210 are in the brown-dwarf regime.

  18. Reanalyses of Anomalous Gravitational Microlensing Events in the OGLE-III Early Warning System Database with Combined Data

    NASA Astrophysics Data System (ADS)

    Jeong, J.; Park, H.; Han, C.; Gould, A.; Udalski, A.; Szymański, M. K.; Pietrzyński, G.; Soszyński, I.; Poleski, R.; Ulaczyk, K.; Wyrzykowski, Ł.; OGLE Collaboration; Abe, F.; Bennett, D. P.; Bond, I. A.; Botzler, C. S.; Freeman, M.; Fukui, A.; Fukunaga, D.; Itow, Y.; Koshimoto, N.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Namba, S.; Ohnishi, K.; Rattenbury, N. J.; Saito, To.; Sullivan, D. J.; Sweatman, W. L.; Sumi, T.; Suzuki, D.; Tristram, P. J.; Tsurumi, N.; Wada, K.; Yamai, N.; Yock, P. C. M.; Yonehara, A.; MOA Collaboration; Albrow, M. D.; Batista, V.; Beaulieu, J.-P.; Caldwell, J. A. R.; Cassan, A.; Cole, A.; Coutures, C.; Dieters, S.; Dominik, M.; Dominis Prester, D.; Donatowicz, J.; Fouqué, P.; Greenhill, J.; Hoffman, M.; Huber, M.; Jørgensen, U. G.; Kane, S. R.; Kubas, D.; Martin, R.; Marquette, J.-B.; Menzies, J.; Pitrou, C.; Pollard, K.; Sahu, K. C.; Vinter, C.; Wambsganss, J.; Williams, A.; PLANET Collaboration; Allen, W.; Bolt, G.; Choi, J.-Y.; Christie, G. W.; DePoy, D. L.; Drummond, J.; Gaudi, B. S.; Hwang, K.-H.; Jung, Y. K.; Lee, C.-U.; Mallia, F.; Maoz, D.; Maury, A.; McCormick, J.; Monard, L. A. G.; Moorhouse, D.; Natusch, T.; Ofek, E. O.; Park, B.-G.; Pogge, R. W.; Santallo, R.; Shin, I.-G.; Thornley, G.; Yee, J. C.; μFUN Collaboration; Bramich, D. M.; Burgdorf, M.; Horne, K.; Hundertmark, M.; Kains, N.; Snodgrass, C.; Steele, I.; Street, R.; Tsapras, Y.; RoboNet Collaboration

    2015-05-01

    We reanalyze microlensing events in the published list of anomalous events that were observed from the Optical Gravitational Lensing Experiment (OGLE) lensing survey conducted during the 2004-2008 period. In order to check the existence of possible degenerate solutions and extract extra information, we conduct analyses based on combined data from other survey and follow-up observation and consider higher-order effects. Among the analyzed events, we present analyses of eight events for which either new solutions are identified or additional information is obtained. We find that the previous binary-source interpretations of five events are better interpreted by binary-lens models. These events include OGLE-2006-BLG-238, OGLE-2007-BLG-159, OGLE-2007-BLG-491, OGLE-2008-BLG-143, and OGLE-2008-BLG-210. With additional data covering caustic crossings, we detect finite-source effects for six events including OGLE-2006-BLG-215, OGLE-2006-BLG-238, OGLE-2006-BLG-450, OGLE-2008-BLG-143, OGLE-2008-BLG-210, and OGLE-2008-BLG-513. Among them, we are able to measure the Einstein radii of three events for which multi-band data are available. These events are OGLE-2006-BLG-238, OGLE-2008-BLG-210, and OGLE-2008-BLG-513. For OGLE-2008-BLG-143, we detect higher-order effects induced by the changes of the observer’s position caused by the orbital motion of the Earth around the Sun. In addition, we present degenerate solutions resulting from the known close/wide or ecliptic degeneracy. Finally, we note that the masses of the binary companions of the lenses of OGLE-2006-BLG-450 and OGLE-2008-BLG-210 are in the brown-dwarf regime.

  19. Possibly high amplification microlensing event

    NASA Astrophysics Data System (ADS)

    Szymanski, Michal; Udalski, Andrzej

    1998-06-01

    The OGLE team informs about a microlensing event in progress - OGLE-1998-BUL-18 (17:54:21.79, -29:53:24.0, J2000) which is presently about 2 days before maximum. It is relatively bright star (I0=15.5), rising rapidly. Preliminary microlensing fit to the light curve predicts large maximum magnification to be reached on JD=2450971.831 (1998-06-07.33 UT) Follow-up observations, both photometric and spectroscopic, are strongly encouraged.

  20. Sharpening the tools of gravitational microlensing

    NASA Astrophysics Data System (ADS)

    Poindexter, Shawn D.

    We attempt to identify all microlensing parallax events for which the parallax fit improves Deltachi2 > 100 relative to a standard microlensing model. We outline a procedure to identify three types of discrete degeneracies (including a new one that we dub the "ecliptic degeneracy") and find many new degenerate solutions in 16 previously published and 6 unpublished events. Only four events have one unique solution and the other 18 events have a total of 44 solutions. Our sample includes three previously identified black-hole (BH) candidates. We consider the newly discovered degenerate solutions and determine the relative likelihood that each of these is a BH. We find the lens of event MACHO-99-BLG-22 is a strong BH candidate (78%), event MACHO-96-BLG-5 is a marginal BH candidate (37%), and MACHO-98-BLG-6 is a weak BH candidate (2.2%). The lens of event OGLE-2003-BLG-84 may be a Jupiter-mass free-floating planet candidate based on a weak 3sigma detection of finite-source effects. We find that event MACHO-179-A is a brown dwarf candidate within ˜100 pc of the Sun, mostly due to its very small projected Einstein radius, r˜E = 0.23 +/- 0.05 AU. As expected, these microlensing parallax events are biased toward lenses that are heavier and closer than average. These events were examined for xallarap (or binary-source motion), which can mimic parallax. We find that 23% of these events are strongly affected by xallarap. The mid-IR flux ratios FA/F B = 2.84 +/- 0.06 of the two images of the gravitationally lensed quasar HE 1104--1805 show no wavelength dependence to within 3% across 3.6--8.0 mum, no time dependence over 6 months and agree with the broad emission line flux ratios. This indicates that the mid-IR emission likely comes from scales large enough to be little affected by microlensing and that there is little differential extinction between the images. We measure a revised time-delay between these two images of 152.2+2.8-3.0 (1sigma) days from R and V-band data

  1. Gravitational microlensing searches and results

    SciTech Connect

    Alcock, C.

    1997-05-08

    Baryonic matter, in the form of Machos (MAssive Compact Halo Objects), might be a significant constituent of the dark matter that dominates the Milky Way. This article describes how surveys for Machos exploit the gravitational microlens magnification of extragalactic stars. The experimental searches for this effect monitor millions of stars, in some cases every night, looking for magnification events. The early results of these surveys indicate that Machos make up a significant fraction of the dark matter in the Milky Way, and that these objects have stellar masses. Truly substellar objects do not contribute much to the total. Additionally, the relatively high event rate towards the Galactic bulge seems to require that the bulge be elongated, and massive.

  2. Possible high magnification microlensing event

    NASA Astrophysics Data System (ADS)

    Udalski, Andrzej; Szymanski, Michal

    1998-05-01

    The OGLE team informs about a microlensing event in progress - OGLE-1998-BUL-15 (18:07:20.83, -27:34:10.8, J2000) which is presently about 4 days before maximum and is rising rapidly (already more than 2 mag above the normal level). Preliminary fit to the light curve predicts possible maximum magnification as large as 10 mag and maximum on JD=2450945.2. Follow up observations, both photometric and spectroscopic, are strongly encouraged.

  3. GRAVITATIONAL MICROLENSING BY THE ELLIS WORMHOLE

    SciTech Connect

    Abe, F.

    2010-12-10

    A method to calculate light curves of the gravitational microlensing of the Ellis wormhole is derived in the weak-field limit. In this limit, lensing by the wormhole produces one image outside the Einstein ring and another image inside. The weak-field hypothesis is a good approximation in Galactic lensing if the throat radius is less than 10{sup 11} km. The light curves calculated have gutters of approximately 4% immediately outside the Einstein ring crossing times. The magnification of the Ellis wormhole lensing is generally less than that of Schwarzschild lensing. The optical depths and event rates are calculated for the Galactic bulge and Large Magellanic Cloud fields according to bound and unbound hypotheses. If the wormholes have throat radii between 100 and 10{sup 7} km, are bound to the galaxy, and have a number density that is approximately that of ordinary stars, detection can be achieved by reanalyzing past data. If the wormholes are unbound, detection using past data is impossible.

  4. Short duration microlensing events: Searching for rogue planets

    NASA Astrophysics Data System (ADS)

    St. Laurent, Kathryn E.; Di Stefano, Rosanne; Primini, Francis A.; Lew, Wei Peng; Gau, Lai Su; Benson, Sophie

    2015-01-01

    Einstein described gravitational microlensing in 1936, at the same time suggesting it to be an unobservable phenomenon. He did not foresee technological advancements that would lead to microlensing becoming a productive tool for astronomy. Of particular interest may be the role it has begun to play in the discovery of rogue planets - exoplanets that are not bound to a star or stars. Rogue planets may be formed independently, or they may be formed in the confines of a stellar system and then ejected by gravitational interactions. Currently fewer than a dozen rogue planets are known but estimates of their abundance conservatively start at double the number of stars in our galaxy.The Optical Gravitational Lensing Experiment (OGLE) and Microlensing Observations in Astrophysics (MOA) teams have collectively detected approximately 2500 events this year alone. A significant portion of these events are of short duration, with an Einstein crossing time of less than 10 days. Microlensing events generally occur on a timescale of weeks to months, so short duration events are an interesting class for study, particularly with regard to searches for rogue planets. We have undertaken a systematic study and categorization of the short duration microlensing events from recent OGLE and MOA alerts, with a special eye to identifying exoplanet candidates.

  5. PERIODIC SIGNALS IN BINARY MICROLENSING EVENTS

    SciTech Connect

    Guo, Xinyi; Stefano, Rosanne Di; Esin, Ann; Taylor, Jeffrey

    2015-08-20

    Gravitational microlensing events are powerful tools for the study of stellar populations. In particular, they can be used to discover and study a variety of binary systems. A large number of binary lenses have already been found through microlensing surveys and a few of these systems show strong evidence of orbital motion on the timescale of the lensing event. We expect that more binary lenses of this kind will be detected in the future. For binaries whose orbital period is comparable to the event duration, the orbital motion can cause the lensing signal to deviate drastically from that of a static binary lens. The most striking property of such light curves is the presence of quasi-periodic features, which are produced as the source traverses the same regions in the rotating lens plane. These repeating features contain information about the orbital period of the lens. If this period can be extracted, then much can be learned about the lensing system even without performing time-consuming, detailed light-curve modeling. However, the relative transverse motion between the source and the lens significantly complicates the problem of period extraction. To resolve this difficulty, we present a modification of the standard Lomb–Scargle periodogram analysis. We test our method for four representative binary lens systems and demonstrate its efficiency in correctly extracting binary orbital periods.

  6. A POSSIBLE BINARY SYSTEM OF A STELLAR REMNANT IN THE HIGH-MAGNIFICATION GRAVITATIONAL MICROLENSING EVENT OGLE-2007-BLG-514

    SciTech Connect

    Miyake, N.; Abe, F.; Furusawa, K.; Itow, Y.; Udalski, A.; Kubiak, M.; Szymanski, M. K.; Pietrzynski, G.; Soszynski, I.; Ulaczyk, K.; Wyrzykowski, L.; Sumi, T.; Bennett, D. P.; Dong, S.; Gould, A.; Street, R. A.; Greenhill, J.; Bond, I. A.; Fukui, A.; Holderness, S.; Collaboration: OGLE Collaboration; MOA Collaboration; muFUN Collaboration; RoboNet Collaboration; PLANET Collaboration; and others

    2012-06-20

    We report the extremely high-magnification (A > 1000) binary microlensing event OGLE-2007-BLG-514. We obtained good coverage around the double peak structure in the light curve via follow-up observations from different observatories. The binary lens model that includes the effects of parallax (known orbital motion of the Earth) and orbital motion of the lens yields a binary lens mass ratio of q = 0.321 {+-} 0.007 and a projected separation of s = 0.072 {+-} 0.001 in units of the Einstein radius. The parallax parameters allow us to determine the lens distance D{sub L} = 3.11 {+-} 0.39 kpc and total mass M{sub L} = 1.40 {+-} 0.18 M{sub Sun }; this leads to the primary and secondary components having masses of M{sub 1} = 1.06 {+-} 0.13 M{sub Sun} and M{sub 2} = 0.34 {+-} 0.04 M{sub Sun }, respectively. The parallax model indicates that the binary lens system is likely constructed by the main-sequence stars. On the other hand, we used a Bayesian analysis to estimate probability distributions by the model that includes the effects of xallarap (possible orbital motion of the source around a companion) and parallax (q = 0.270 {+-} 0.005, s = 0.083 {+-} 0.001). The primary component of the binary lens is relatively massive, with M{sub 1} = 0.9{sup +4.6}{sub -0.3} M{sub Sun} and it is at a distance of D{sub L} = 2.6{sup +3.8}{sub -0.9} kpc. Given the secure mass ratio measurement, the companion mass is therefore M{sub 2} = 0.2{sup +1.2}{sub -0.1} M{sub Sun }. The xallarap model implies that the primary lens is likely a stellar remnant, such as a white dwarf, a neutron star, or a black hole.

  7. Gravitational Microlensing by Ellis Wormhole: Second Order Effects

    NASA Astrophysics Data System (ADS)

    Lukmanova, Regina; Kulbakova, Aliya; Izmailov, Ramil; Potapov, Alexander A.

    2016-11-01

    Gravitational lensing is the effect of light bending in a gravitational field. It can be used as a possible observational method to detect or exclude the existence of wormholes. In this work, we extend the work by Abe on gravitational microlensing by Ellis wormhole by including the second order deflection term. Using the lens equation and definition of Einstein radius, we find the angular locations of the physical image inside and outside Einstein ring. The work contains a comparative analysis of light curves between the Schwarzschild black hole and the Ellis wormhole that can be used to distinguish such objects though such distinctions are too minute to be observable even in the near future. We also tabulate the optical depth and event rate for lensing by bulge and Large Magellanic Cloud (LMC) stars.

  8. Characterizing Lenses and Lensed Stars of High-magnification Single-lens Gravitational Microlensing Events with Lenses Passing over Source Stars

    NASA Astrophysics Data System (ADS)

    Choi, J.-Y.; Shin, I.-G.; Park, S.-Y.; Han, C.; Gould, A.; Sumi, T.; Udalski, A.; Beaulieu, J.-P.; Street, R.; Dominik, M.; Allen, W.; Almeida, L. A.; Bos, M.; Christie, G. W.; Depoy, D. L.; Dong, S.; Drummond, J.; Gal-Yam, A.; Gaudi, B. S.; Henderson, C. B.; Hung, L.-W.; Jablonski, F.; Janczak, J.; Lee, C.-U.; Mallia, F.; Maury, A.; McCormick, J.; McGregor, D.; Monard, L. A. G.; Moorhouse, D.; Muñoz, J. A.; Natusch, T.; Nelson, C.; Park, B.-G.; Pogge, R. W.; "TG" Tan, T.-G.; Thornley, G.; Yee, J. C.; μFUN Collaboration; Abe, F.; Barnard, E.; Baudry, J.; Bennett, D. P.; Bond, I. A.; Botzler, C. S.; Freeman, M.; Fukui, A.; Furusawa, K.; Hayashi, F.; Hearnshaw, J. B.; Hosaka, S.; Itow, Y.; Kamiya, K.; Kilmartin, P. M.; Kobara, S.; Korpela, A.; Lin, W.; Ling, C. H.; Makita, S.; Masuda, K.; Matsubara, Y.; Miyake, N.; Muraki, Y.; Nagaya, M.; Nishimoto, K.; Ohnishi, K.; Okumura, T.; Omori, K.; Perrott, Y. C.; Rattenbury, N.; Saito, To.; Skuljan, L.; Sullivan, D. J.; Suzuki, D.; Suzuki, K.; Sweatman, W. L.; Takino, S.; Tristram, P. J.; Wada, K.; Yock, P. C. M.; MOA Collaboration; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Poleski, R.; Ulaczyk, K.; Wyrzykowski, Ł.; Kozłowski, S.; Pietrukowicz, P.; OGLE Collaboration; Albrow, M. D.; Bachelet, E.; Batista, V.; Bennett, C. S.; Bowens-Rubin, R.; Brillant, S.; Cassan, A.; Cole, A.; Corrales, E.; Coutures, Ch.; Dieters, S.; Dominis Prester, D.; Donatowicz, J.; Fouqué, P.; Greenhill, J.; Kane, S. R.; Menzies, J.; Sahu, K. C.; Wambsganss, J.; Williams, A.; Zub, M.; PLANET Collaboration; Allan, A.; Bramich, D. M.; Browne, P.; Clay, N.; Fraser, S.; Horne, K.; Kains, N.; Mottram, C.; Snodgrass, C.; Steele, I.; Tsapras, Y.; RoboNet Collaboration; Alsubai, K. A.; Bozza, V.; Burgdorf, M. J.; Calchi Novati, S.; Dodds, P.; Dreizler, S.; Finet, F.; Gerner, T.; Glitrup, M.; Grundahl, F.; Hardis, S.; Harpsøe, K.; Hinse, T. C.; Hundertmark, M.; Jørgensen, U. G.; Kerins, E.; Liebig, C.; Maier, G.; Mancini, L.; Mathiasen, M.; Penny, M. T.; Proft, S.; Rahvar, S.; Ricci, D.; Scarpetta, G.; Schäfer, S.; Schönebeck, F.; Skottfelt, J.; Surdej, J.; Southworth, J.; Zimmer, F.; MiNDSTEp Consortium

    2012-05-01

    We present the analysis of the light curves of nine high-magnification single-lens gravitational microlensing events with lenses passing over source stars, including OGLE-2004-BLG-254, MOA-2007-BLG-176, MOA-2007-BLG-233/OGLE-2007-BLG-302, MOA-2009-BLG-174, MOA-2010-BLG-436, MOA-2011-BLG-093, MOA-2011-BLG-274, OGLE-2011-BLG-0990/MOA-2011-BLG-300, and OGLE-2011-BLG-1101/MOA-2011-BLG-325. For all of the events, we measure the linear limb-darkening coefficients of the surface brightness profile of source stars by measuring the deviation of the light curves near the peak affected by the finite-source effect. For seven events, we measure the Einstein radii and the lens-source relative proper motions. Among them, five events are found to have Einstein radii of less than 0.2 mas, making the lenses very low mass star or brown dwarf candidates. For MOA-2011-BLG-274, especially, the small Einstein radius of θE ~ 0.08 mas combined with the short timescale of t E ~ 2.7 days suggests the possibility that the lens is a free-floating planet. For MOA-2009-BLG-174, we measure the lens parallax and thus uniquely determine the physical parameters of the lens. We also find that the measured lens mass of ~0.84 M ⊙ is consistent with that of a star blended with the source, suggesting that the blend is likely to be the lens. Although we did not find planetary signals for any of the events, we provide exclusion diagrams showing the confidence levels excluding the existence of a planet as a function of the separation and mass ratio.

  9. CHARACTERIZING LENSES AND LENSED STARS OF HIGH-MAGNIFICATION SINGLE-LENS GRAVITATIONAL MICROLENSING EVENTS WITH LENSES PASSING OVER SOURCE STARS

    SciTech Connect

    Choi, J.-Y.; Shin, I.-G.; Park, S.-Y.; Han, C.; Gould, A.; Gaudi, B. S.; Henderson, C. B.; Sumi, T.; Udalski, A.; Beaulieu, J.-P.; Street, R.; Dominik, M.; Allen, W.; Almeida, L. A.; Christie, G. W.; Depoy, D. L.; Dong, S.; Drummond, J.; Gal-Yam, A.; Collaboration: muFUN Collaboration; MOA Collaboration; OGLE Collaboration; PLANET Collaboration; RoboNet Collaboration; MiNDSTEp Consortium; and others

    2012-05-20

    We present the analysis of the light curves of nine high-magnification single-lens gravitational microlensing events with lenses passing over source stars, including OGLE-2004-BLG-254, MOA-2007-BLG-176, MOA-2007-BLG-233/OGLE-2007-BLG-302, MOA-2009-BLG-174, MOA-2010-BLG-436, MOA-2011-BLG-093, MOA-2011-BLG-274, OGLE-2011-BLG-0990/MOA-2011-BLG-300, and OGLE-2011-BLG-1101/MOA-2011-BLG-325. For all of the events, we measure the linear limb-darkening coefficients of the surface brightness profile of source stars by measuring the deviation of the light curves near the peak affected by the finite-source effect. For seven events, we measure the Einstein radii and the lens-source relative proper motions. Among them, five events are found to have Einstein radii of less than 0.2 mas, making the lenses very low mass star or brown dwarf candidates. For MOA-2011-BLG-274, especially, the small Einstein radius of {theta}{sub E} {approx} 0.08 mas combined with the short timescale of t{sub E} {approx} 2.7 days suggests the possibility that the lens is a free-floating planet. For MOA-2009-BLG-174, we measure the lens parallax and thus uniquely determine the physical parameters of the lens. We also find that the measured lens mass of {approx}0.84 M{sub Sun} is consistent with that of a star blended with the source, suggesting that the blend is likely to be the lens. Although we did not find planetary signals for any of the events, we provide exclusion diagrams showing the confidence levels excluding the existence of a planet as a function of the separation and mass ratio.

  10. Exoplanets and brown dwarfs detections through gravitational microlensing. Study of interferometric observations.

    NASA Astrophysics Data System (ADS)

    Ranc, Clément

    2015-09-01

    Gravitational microlensing effect has become a unique tool to detect and characterise exoplanets. A microlensing effect occurs when a foreground star (the microlens) and a background star (the source) are aligned with the Earth on the same line of sight. The light from the furthest star, usually in the Galactic bulge, is deflected by the microlens located on the disk. During this phenomenon, multiple images of the source are created by the lens, bigger than the source that consequently seems amplified. When one of these images are located in the vicinity of an exoplanet, a short amplification jump occurs revealing its presence. After a quick overview of the exoplanets field of research, I highlight the specificities of microlensing comparing to the other planets detection techniques. Then, I describe in details the modelling of microlensing effects, from a theoretical to a numerical point of view. In a third part, I describe the detection of the first brown dwarf orbiting a solar-type star using microlensing, strengthening the recent idea that microlensing will lead to a better understanding of the mechanisms involved in the brown dwarfs formation, still not fully understood. Finally, I investigate the potential of interferometric observations of microlensing events that will give, in the future, new original constraints on the microlens physical properties. First, we introduce a new formalism that closely combines interferometric and microlensing observable quantities. Secondly, we determine an average number of events that are at reach of long baseline interferometers every year.

  11. Random scattering approach to gravitational microlensing

    NASA Technical Reports Server (NTRS)

    Katz, N.; Balbus, S.; Paczynski, B.

    1986-01-01

    Small random deflections of a narrow beam of radiation due to gravitational scattering by stars randomly distributed within the deflector plane are considered. Using a Fouriere transform method, the probability of scattering is obtained as a function of scattering angle for an arbitrary number of stars with an arbitrary distribution of masses. The probability density, expressed in proper units, depends on one parameter only: the effective number of stars. At small scattering angles the density is a Gaussian, and at large angles it falls off as the scattering angle to the minus fourth power. The probability distribution for scatterings is simply related to the angular distribution of the surface brightness of a macroimage, averaged over many microimages. The isophotes are ellipses, with the ratio of the major axis to the minor axis, determined by the dimensionless surface mass density and the shear of the lensing system. The number of stars that has to be included in the modeling of microlensing is proportional to the amplification due to the macrolens, and to the square of the dimensionless surface mass density.

  12. Gravitational microlensing by a single star plus external shear

    NASA Technical Reports Server (NTRS)

    Mao, Shude

    1992-01-01

    Gravitational microlensing by a single star plus external shear is considered. It is shown that for a general cusp the magnification probability distribution follows pc(A)dA of about (A exp -7/2)dA for sufficiently large magnifications. An adaptive grid technique is developed to calculate the magnification probability distributions. The results could be useful for cases of microlensing where the surface-mass density is low.

  13. Application of Compressive Sensing to Gravitational Microlensing Experiments

    NASA Technical Reports Server (NTRS)

    Korde-Patel, Asmita; Barry, Richard K.; Mohsenin, Tinoosh

    2016-01-01

    Compressive Sensing is an emerging technology for data compression and simultaneous data acquisition. This is an enabling technique for significant reduction in data bandwidth, and transmission power and hence, can greatly benefit spaceflight instruments. We apply this process to detect exoplanets via gravitational microlensing. We experiment with various impact parameters that describe microlensing curves to determine the effectiveness and uncertainty caused by Compressive Sensing. Finally, we describe implications for spaceflight missions.

  14. Probing the gravitational Faraday rotation using quasar X-ray microlensing.

    PubMed

    Chen, Bin

    2015-11-17

    The effect of gravitational Faraday rotation was predicted in the 1950s, but there is currently no practical method for measuring this effect. Measuring this effect is important because it will provide new evidence for correctness of general relativity, in particular, in the strong field limit. We predict that the observed degree and angle of the X-ray polarization of a cosmologically distant quasar microlensed by the random star field in a foreground galaxy or cluster lens vary rapidly and concurrently with flux during caustic-crossing events using the first simulation of quasar X-ray microlensing polarization light curves. Therefore, it is possible to detect gravitational Faraday rotation by monitoring the X-ray polarization of gravitationally microlensed quasars. Detecting this effect will also confirm the strong gravity nature of quasar X-ray emission.

  15. Probing the gravitational Faraday rotation using quasar X-ray microlensing

    PubMed Central

    Chen, Bin

    2015-01-01

    The effect of gravitational Faraday rotation was predicted in the 1950s, but there is currently no practical method for measuring this effect. Measuring this effect is important because it will provide new evidence for correctness of general relativity, in particular, in the strong field limit. We predict that the observed degree and angle of the X-ray polarization of a cosmologically distant quasar microlensed by the random star field in a foreground galaxy or cluster lens vary rapidly and concurrently with flux during caustic-crossing events using the first simulation of quasar X-ray microlensing polarization light curves. Therefore, it is possible to detect gravitational Faraday rotation by monitoring the X-ray polarization of gravitationally microlensed quasars. Detecting this effect will also confirm the strong gravity nature of quasar X-ray emission. PMID:26574051

  16. Extrasolar planets detections and statistics through gravitational microlensing

    NASA Astrophysics Data System (ADS)

    Cassan, A.

    2014-10-01

    Gravitational microlensing was proposed thirty years ago as a promising method to probe the existence and properties of compact objects in the Galaxy and its surroundings. The particularity and strength of the technique is based on the fact that the detection does not rely on the detection of the photon emission of the object itself, but on the way its mass affects the path of light of a background, almost aligned source. Detections thus include not only bright, but also dark objects. Today, the many successes of gravitational microlensing have largely exceeded the original promises. Microlensing contributed important results and breakthroughs in several astrophysical fields as it was used as a powerful tool to probe the Galactic structure (proper motions, extinction maps), to search for dark and compact massive objects in the halo and disk of the Milky Way, to probe the atmospheres of bulge red giant stars, to search for low-mass stars and brown dwarfs and to hunt for extrasolar planets. As an extrasolar planet detection method, microlensing nowadays stands in the top five of the successful observational techniques. Compared to other (complementary) detection methods, microlensing provides unique information on the population of exoplanets, because it allows the detection of very low-mass planets (down to the mass of the Earth) at large orbital distances from their star (0.5 to 10 AU). It is also the only technique that allows the discovery of planets at distances from Earth greater than a few kiloparsecs, up to the bulge of the Galaxy. Microlensing discoveries include the first ever detection of a cool super-Earth around an M-dwarf star, the detection of several cool Neptunes, Jupiters and super-Jupiters, as well as multi-planetary systems and brown dwarfs. So far, the least massive planet detected by microlensing has only three times the mass of the Earth and orbits a very low mass star at the edge of the brown dwarf regime. Several free-floating planetary

  17. Fitting Photometry of Blended Microlensing Events

    NASA Astrophysics Data System (ADS)

    Thomas, Christian L.; Griest, Kim

    2006-03-01

    We reexamine the usefulness of fitting blended light-curve models to microlensing photometric data. We find agreement with previous workers (e.g., Woźniak & Paczyński) that this is a difficult proposition because of the degeneracy of blend fraction with other fit parameters. We show that follow-up observations at specific point along the light curve (peak region and wings) of high-magnification events are the most helpful in removing degeneracies. We also show that very small errors in the baseline magnitude can result in problems in measuring the blend fraction and study the importance of non-Gaussian errors in the fit results. The biases and skewness in the distribution of the recovered blend fraction is discussed. We also find a new approximation formula relating the blend fraction and the unblended fit parameters to the underlying event duration needed to estimate microlensing optical depth.

  18. Resolving Microlensing Events with Triggered VLBI

    NASA Astrophysics Data System (ADS)

    Karami, Mansour; Broderick, Avery E.; Rahvar, Sohrab; Reid, Mark

    2016-12-01

    Microlensing events provide a unique capacity to study the stellar remnant population of the Galaxy. Optical microlensing suffers from a near-complete degeneracy between mass, velocity, and distance. However, a subpopulation of lensed stars, Mira variable stars, are also radio-bright, exhibiting strong SiO masers. These are sufficiently bright and compact to permit direct imaging using existing very long baseline interferometers such as the Very Long Baseline Array (VLBA). We show that these events are relatively common, occurring at a rate of ≈ 2 {{yr}}-1 of which 0.1 {{yr}}-1 are associated with Galactic black holes. Features in the associated images, e.g., the Einstein ring, are sufficiently well resolved to fully reconstruct the lens properties, enabling the measurement of mass, distance, and tangential velocity of the lensing object to a precision better than 15%. Future radio microlensing surveys conducted with upcoming radio telescopes combined with modest improvements in the VLBA could increase the rate of Galactic black hole events to roughly 10 {{yr}}-1, sufficient to double the number of known stellar mass black holes in a couple of years, and permitting the construction of distribution functions of stellar mass black hole properties.

  19. Discovery of a Jupiter/Saturn Analog with Gravitational Microlensing

    SciTech Connect

    Gaudi, B; Bennett, D; Udalski, A; Gould, A; Christie, G; Maoz, D; Dong, S; McCormick, J; Szymanski, M; Tristram, P; Nikolaev, S; Paczynski, B; Kubiak, M; Pietrzynski, G; Soszynski, I; Szewczyk, O; Ulaczyk, K; Wyrzykowski, L; DePoy, D; Han, C; Kaspi, S; Lee, C; Mallia, F; Natusch, T; Pogge, R; Park, B; Abe, F; Bond, I; Botzler, C; Fukui, A; Hearnshaw, J; Itow, Y; Kamiya, K; Korpela, A; Kilmartin, P; Lin, W; Masuda, K; Matsubara, Y; Motomura, M; Muraki, Y; Nakamura, S; Okumura, T; Ohnishi, K; Rattenbury, N; Sako, T; Saito, T; Sato, S; Skuljan, L; Sullivan, D; Sumi, T; Sweatman, W; Yock, P; Albrow, M; Beaulieu, J; Burgdorf, M; Cook, K; Coutures, C; Dominik, M; Dieters, S; Fouque, P; Greenhill, J; Horne, K; Steele, I; Tsapras, Y; Chaboyer, B; Crocker, A; Frank, S; Macintosh, B

    2007-11-08

    Searches for extrasolar planets have uncovered an astonishing diversity of planetary systems, yet the frequency of solar system analogs remains unknown. The gravitational microlensing planet search method is potentially sensitive to multiple-planet systems containing analogs of all the solar system planets except Mercury. We report the first detection of a multiple-planet system with microlensing. We identify two planets with masses of {approx} 0.71 and {approx} 0.27 times the mass of Jupiter and orbital separations of {approx} 2.3 and {approx} 4.6 astronomical units orbiting a primary of mass {approx} 0.50 solar masses. This system resembles a scaled version of our solar system in that the mass ratio, separation ratio, and equilibrium temperatures of the planets are similar to those of Jupiter and Saturn. These planets could not have been detected with other techniques; their discovery from only 6 confirmed microlensing planet detections suggests that solar system analogs may be common.

  20. Microlensing Events in Gaia and other Astrometric Surveys

    NASA Astrophysics Data System (ADS)

    Baker, Claire; Di Stefano, Rosanne; Lepine, Sebastien

    2017-01-01

    The region within a kiloparsec of the Sun is a vast and mysterious place filled with uncharted planets, stars and compact objects, whose masses and properties are unknown. The Gaia space mission provides a unique opportunity to study of this region by measuring parallax distances and proper motions to millions of nearby stars, significantly advancing data available from previous astrometric surveys.We are putting this new astrometric information from the first Gaia data release to a novel use, by searching for matches between the positions of known microlensing events and the positions of stars observed by both the Gaia and the Tycho-2 missions, as listed in the Tycho-Gaia Astrometric Solution (TGAS) Catalogue.The existence of a gravitational microlensing event near a TGAS-listed star may provide information about the nature of either the source star lensed in the event, or the lens itself. For example, the source star lensed in the ‘TAGO’ event lies nearby, and is listed in the TGAS Catalogue. Other events may also have been caused by nearby TGAS-listed stars, or by their dim companions. In such cases, we can determine the lens mass and acquire information about any compact objects or planets which may exist around the lens.We report on the process of matching the positions of over 20,000 candidate microlensing events discovered by either OGLE and/or MOA, with the positions of 2 million stars from the TGAS Catalogue and stars from a range of other surveys, including Lepine's SUPERBLINK survey, and discuss the implications of the matches obtained.

  1. Gravitational Microlensing in Modified Gravity Theories - Inverse-Square Theorem

    NASA Astrophysics Data System (ADS)

    Asada, H.

    2011-02-01

    Microlensing studies are usually based on the lens equation that is valid only to the first order in the gravitational constant G and lens mass M. We consider corrections to the conventional lens equation in terms of differentiable functions, so that they can express not only the second-order effects of GM in general relativity but also modified gravity theories. As a generalization of Ebina et al. (Prog. Theor. Phys. 104 (2000), 1317), we show that, provided that the spacetime is static, spherically symmetric and asymptotically flat, the total amplification by microlensing remains unchanged at the linear order of the correction to the deflection angle, if and only if the correction takes a particular form as the inverse square of the impact parameter, whereas the magnification factor for each image is corrected. It is concluded that the light curve shape by microlensing is inevitably changed and will thus allow us to probe modified gravity, unless a modificati on to the deflection angle takes the particular form. No systematic deviation in microlensing observations has been reported. For instance, therefore, the Yukawa-type correction is constrained as the characteristic length > 10^{14} m.

  2. Discovery of a Jupiter/Saturn analog with gravitational microlensing.

    PubMed

    Gaudi, B S; Bennett, D P; Udalski, A; Gould, A; Christie, G W; Maoz, D; Dong, S; McCormick, J; Szymanski, M K; Tristram, P J; Nikolaev, S; Paczynski, B; Kubiak, M; Pietrzynski, G; Soszynski, I; Szewczyk, O; Ulaczyk, K; Wyrzykowski, L; Depoy, D L; Han, C; Kaspi, S; Lee, C-U; Mallia, F; Natusch, T; Pogge, R W; Park, B-G; Abe, F; Bond, I A; Botzler, C S; Fukui, A; Hearnshaw, J B; Itow, Y; Kamiya, K; Korpela, A V; Kilmartin, P M; Lin, W; Masuda, K; Matsubara, Y; Motomura, M; Muraki, Y; Nakamura, S; Okumura, T; Ohnishi, K; Rattenbury, N J; Sako, T; Saito, To; Sato, S; Skuljan, L; Sullivan, D J; Sumi, T; Sweatman, W L; Yock, P C M; Albrow, M D; Allan, A; Beaulieu, J-P; Burgdorf, M J; Cook, K H; Coutures, C; Dominik, M; Dieters, S; Fouqué, P; Greenhill, J; Horne, K; Steele, I; Tsapras, Y; Chaboyer, B; Crocker, A; Frank, S; Macintosh, B

    2008-02-15

    Searches for extrasolar planets have uncovered an astonishing diversity of planetary systems, yet the frequency of solar system analogs remains unknown. The gravitational microlensing planet search method is potentially sensitive to multiple-planet systems containing analogs of all the solar system planets except Mercury. We report the detection of a multiple-planet system with microlensing. We identify two planets with masses of approximately 0.71 and approximately 0.27 times the mass of Jupiter and orbital separations of approximately 2.3 and approximately 4.6 astronomical units orbiting a primary star of mass approximately 0.50 solar mass at a distance of approximately 1.5 kiloparsecs. This system resembles a scaled version of our solar system in that the mass ratio, separation ratio, and equilibrium temperatures of the planets are similar to those of Jupiter and Saturn. These planets could not have been detected with other techniques; their discovery from only six confirmed microlensing planet detections suggests that solar system analogs may be common.

  3. Gravitational microlensing by double stars and planetary systems

    NASA Technical Reports Server (NTRS)

    Mao, Shunde; Paczynski, Bohdan

    1991-01-01

    Almost all stars are in binary systems. When the separation between the two components is comparable to the Einstein ring radius corresponding to the combined mass of the binary acting as a gravitational lens, then an extra pair of images can be created, and the light curve of a lensed source becomes complicated. It is estimated that about 10 percent of all lensing episodes of the Galactic bulge stars will strongly display the binary nature of the lens. The effect is strong even if the companion is a planet. A massive search for microlensing of the Galactic bulge stars may lead to a discovery of the first extrasolar planetary systems.

  4. Resolving the Nature of the LMC Microlensing Event LMC-5

    SciTech Connect

    Drake, A J; Cook, K H; Keller, S C

    2004-04-22

    The authors present the results from an analysis of Hubble Space Telescope High Resolution Camera data for the Large Magellanic Cloud microlensing event MACHO-LMC-5. By determining the parallax and proper motion of this object they find that the lens is an M dwarf star at a distance of 578{sub -53}{sup +65}pc with a proper motion of 21.39 {+-} 0.04 mas/yr. Based on the kinematics and location of this star is it more likely to be part of the Galactic thick disk than thin disk population. They confirm that the microlensing event LMC-5 is a jerk-parallax microlensing event.

  5. Gravitational microlensing by low-mass objects in the globular cluster M22.

    PubMed

    Sahu, K C; Casertano, S; Livio, M; Gilliland, R L; Panagia, N; Albrow, M D; Potter, M

    2001-06-28

    Gravitational microlensing offers a means of determining directly the masses of objects ranging from planets to stars, provided that the distances and motions of the lenses and sources can be determined. A globular cluster observed against the dense stellar field of the Galactic bulge presents ideal conditions for such observations because the probability of lensing is high and the distances and kinematics of the lenses and sources are well constrained. The abundance of low-mass objects in a globular cluster is of particular interest, because it may be representative of the very early stages of star formation in the Universe, and therefore indicative of the amount of dark baryonic matter in such clusters. Here we report a microlensing event associated with the globular cluster M22. We determine the mass of the lens to be 0.13(+0.03)(-0.02) solar masses. We have also detected six events that are unresolved in time. If these are also microlensing events, they imply that a non-negligible fraction of the cluster mass resides in the form of free-floating planetary-mass objects.

  6. Exoplanets mass measurement using gravitational microlensing

    NASA Astrophysics Data System (ADS)

    Ranc, Clement; Cassan, Arnaud

    2015-07-01

    Thousands of extrasolar planets have been discovered so far, and after the pioneer era, when the discovery of a single planet was a notable event, the interest is moving to the more complex work of planet and planetary system taxonomy, trying to put some order and eventually understand why they are so different from each others. The characterization of planets is tied to the knowledge of their host stars. Nearly all planets known so far however belong to isolated field stars, and their mass and radius are affected by large errors that transfer directly onto the precision of the planet parameters. On the contrary, distances, ages, mass and overall characteristics of stars in Open Clusters are much better measured than for field stars. OC stars are chemically homogeneous, so we can effectively investigate the effect of the presence of a planetary systems on the host star chemistry, e.g. if the observed trend of chemical elements with respect to their condensation temperature is effectively related to the presence planets. Curiously, at the present time, only less than ten planets have been confirmed or validated around Main Sequence stars in OCs. In this proposed talk I will give a short historical review on previous searches for exoplanets in OCs, then I will introduce our on-going survey aimed at detecting Neptune-mass planets around close, intermediate-age OC stars with HARPS (8 night/year) and HARPS-N (5 nights/semester, within the GAPS program). I will discuss our observational strategy and how we are dealing with activity, the main limiting factor in this kind of research, and the impact of the forth-coming K2 observations on our search. I will finally present our latest discoveries, including the first planetary multiple system around a OC star.

  7. Gravitational lens system SDSS J1339+1310: microlensing factory and time delay

    NASA Astrophysics Data System (ADS)

    Goicoechea, L. J.; Shalyapin, V. N.

    2016-12-01

    We spectroscopically re-observed the gravitational lens system SDSS J1339+1310 using OSIRIS on the GTC. We also monitored the r-band variability of the two quasar images (A and B) with the LT over 143 epochs in the period 2009-2016. These new data in both the wavelength and time domains have confirmed that the system is an unusual microlensing factory. The C iv emission line is remarkably microlensed, since the microlensing magnification of B relative to that for A, μBA, reaches a value of 1.4 ( 0.4 mag) for its core. Moreover, the B image shows a red wing enhancement of C iv flux (relative to A), and μBA = 2 (0.75 mag) for the C iv broad-line emission. Regarding the nuclear continuum, we find a chromatic behaviour of μBA, which roughly varies from 5 (1.75 mag) at 7000 Å to 6 (1.95 mag) at 4000 Å. We also detect significant microlensing variability in the r band, and this includes a number of microlensing events on timescales of 50-100 d. Fortunately, the presence of an intrinsic 0.7 mag dip in the light curves of A and B, permitted us to measure the time delay between both quasar images. This delay is ΔtAB = 47 d (1σ confidence interval; A is leading), in good agreement with predictions of lens models. Tables 1-3 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/596/A77

  8. High Probabilities of Planet Detection during Microlensing Events.

    NASA Astrophysics Data System (ADS)

    Peale, S. J.

    2000-10-01

    The averaged probability of detecting a planetary companion of a lensing star during a gravitational microlensing event toward the Galactic center when the planet-lens mass ratio is 0.001 is shown to have a maximum exceeding 20% for a distribution of source-lens impact parameters that is determined by the efficiency of event detection, and a maximum exceeding 10% for a uniform distribution of impact parameters. The probability varies as the square root of the planet-lens mass ratio. A planet is assumed detectable if the perturbation of the light curve exceeds 2/(S/N) for a significant number of data points, where S/N is the signal-to noise ratio for the photometry of the source. The probability peaks at a planetary semimajor axis a that is close to the mean Einstein ring radius of the lenses of about 2 AU along the line of sight, and remains significant for 0.6<= a<= 10 AU. The low value of the mean Einstein ring radius results from the dominance of M stars in the mass function of the lenses. The probability is averaged over the distribution of the projected position of the planet onto the lens plane, over the lens mass function, over the distribution of impact parameters, over the distribution of lens along the line of sight to the source star, over the I band luminosity function of the sources adjusted for the source distance, and over the source distribution along the line of sight. If two or more parameters of the lensing event are known, such as the I magnitude of the source and the impact parameter, the averages over these parameters can be omitted and the probability of detection determined for a particular event. The calculated probabilities behave as expected with variations in the line of sight, the mass function of the lenses, the extinction and distance to and magnitude of the source, and with a more demanding detection criterion. The relatively high values of the probabilities are robust to plausible variations in the assumptions. The high

  9. Quasar Structure from Microlensing in Gravitationally Lensed Quasars

    NASA Astrophysics Data System (ADS)

    Morgan, Christopher W.

    2007-12-01

    I investigate microlensing in gravitationally lensed quasars and discuss the use of its signal to probe quasar structure on small angular scales. I describe our lensed quasar optical monitoring program and RETROCAM, the optical camera I built for the 2.4m Hiltner telescope to monitor lensed quasars. I use the microlensing variability observed in 11 gravitationally lensed quasars to show that the accretion disk size at 2500Å is related to the black hole mass by log(R2500/cm) = (15.70±0.16) + (0.64±0.18)log(MBH/109M⊙). This scaling is consistent with the expectation from thin disk theory (R ∝ MBH2/3), but it implies that black holes radiate with relatively low efficiency, log(η) = -1.54±0.36 + log(L/LE) where η=L/(Mdotc2). With one exception, these sizes are larger by a factor of 4 than the size needed to produce the observed 0.8µm quasar flux by thermal radiation from a thin disk with the same T ∝ R-3/4 temperature profile. More sophisticated disk models are clearly required, particularly as our continuing observations improve the precision of the measurements and yield estimates of the scaling with wavelength and accretion rate. This research made extensive use of a Beowulf computer cluster obtained through the Cluster Ohio program of the Ohio Supercomputer Center. Support for program HST-GO-9744 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS-5-26666.

  10. A PUZZLE INVOLVING GALACTIC BULGE MICROLENSING EVENTS

    SciTech Connect

    Cohen, Judith G.; Gould, Andrew; Johnson, Jennifer A.; Thompson, Ian B.; Feltzing, Sofia; Bensby, Thomas; Huang Wenjin; Melendez, Jorge; Lucatello, Sara; Asplund, Martin E-mail: gould@astronomy.ohio-state.edu E-mail: ian@obs.carnegiescience.edu E-mail: tbensby@eso.org E-mail: jorge@astro.up.pt E-mail: asplund@MPA-Garching.MPG.DE

    2010-03-01

    We study a sample of 16 microlensed Galactic bulge main-sequence turnoff region stars for which high-dispersion spectra have been obtained with detailed abundance analyses. We demonstrate that there is a very strong and highly statistically significant correlation between the maximum magnification of the microlensed bulge star and the value of the [Fe/H] deduced from the high resolution spectrum of each object. Physics demands that this correlation, assuming it to be real, be the result of some sample bias. We suggest several possible explanations, but are forced to reject them all, and are left puzzled. To obtain a reliable metallicity distribution in the Galactic bulge based on microlensed dwarf stars, it will be necessary to resolve this issue through the course of additional observations.

  11. Quasar structure from microlensing in gravitationally lensed quasars

    NASA Astrophysics Data System (ADS)

    Morgan, Christopher Warren

    2008-02-01

    I analyze microlensing in gravitationally lensed quasars to yield measurements of the structure of their continuum emission regions. I first describe our lensed quasar monitoring program and RETROCAM, the auxiliary port camera I built for the 2.4m Hiltner telescope to monitor lensed quasars. I describe the application of our Monte Carlo microlensing analysis technique to SDSS 0924+0219, a system with a highly anomalous optical flux ratio. For an inclination angle i, I find an optical scale radius log[( r s /cm)[Special characters omitted.] ] = [Special characters omitted.] . I extrapolate the best-fitting light curves into the future to find a roughly 45% probability that the anomalous image (D) will brighten by at least an order of magnitude during the next decade. I expand our method to make simultaneous estimates of the time delays and structure of HE1104-1805 and QJ0158-4325, two doubly-imaged quasars with microlensing and intrinsic variability on comparable time scales. For HE1104- 1805 I find a time delay of D t AB = t A - t B = [Special characters omitted.] days and estimate a scale radius of log[( r s /cm)[Special characters omitted.] ] = [Special characters omitted.] at 0.2mm in the rest frame. I am unable to measure a time delay for QJ0158-4325, but the scale radius is log[( r s /cm) [Special characters omitted.] ] = 14.9 ±1 0.3 at 0.3mm in the rest frame. I then apply our Monte Carlo microlensing analysis technique to the optical light curves of 11 lensed quasar systems to show that quasar accretion disk sizes at 2500Å are related to black hole mass ( M BH ) by log( R 2500 /cm) = (15.7 ± 0.16) + (0.64± 0.18) log( M BH /10 9 [Special characters omitted.] ). This scaling is consistent with the expectation from thin disk theory (R 0( [Special characters omitted.] ), but it implies that black holes radiate with relatively low efficiency, log(e) = -1.54 ± 0.36 + log( L/L E ) where e=3D L / ( M c 2 ). These sizes are also larger, by a factor of ~ 3, than

  12. Exotic gravitational microlensing effects as a probe of stellar and galactic structure

    NASA Astrophysics Data System (ADS)

    Becker, Andrew Cameron

    The nature of the "dark matter" which comprises the majority of the mass of our Universe is one of the most elusive, yet fundamental, cosmological properties. Its presence has been inferred on a variety of scales by indirect observational measurements. It remains to be seen whether or not this dark matter is composed of discrete units (Machos---Massive Compact Halo Objects) or is a sea of fundamental particles (WIMPS---Weakly Interacting Massive Particles). The MACHO project was founded to test for Machos orbiting in the halo of our Milky Way Galaxy. The experiment makes use of the one property we know about dark matter---it exerts a gravitational force on its surroundings. Einstein's theory of general relativity implies the region of influence sensitive to dark matter includes the fundamental fabric of space-time itself. A bizarre consequence of this is that matter may warp space, splitting the light from a background source into multiple images on the sky, hence acting as a gravitational lens. Millions of source stars in the Large and Small Magellanic Clouds have been observed for signatures of intervening, lensing dark matter. Approximately 20 events have been discovered. Several hundred additional events have been seen towards our Galactic bulge. Given the dearth of lensing events, the focus of the gravitational microlensing field has evolved from passive surveys to an aggressive pursuit of lightcurve fine structure. Embedded in each microlensing lightcurve are clues to the nature of the lensing system. Recognizing these features in real-time requires frequent sampling and high precision measurements. This dissertation includes the development and maintenance of the MACHO Alert System, which recognized these rare events in real-time. This Alert System required daily vigilance between its inception in 1995 and the completion of the MACHO Survey in 1999. However, the focus of this dissertation was the Global Microlensing Alert Network (GMAN). This system

  13. OGLE-III MICROLENSING EVENTS AND THE STRUCTURE OF THE GALACTIC BULGE

    SciTech Connect

    Wyrzykowski, Łukasz; Rynkiewicz, Alicja E.; Skowron, Jan; Kozłowski, Szymon; Udalski, Andrzej; Szymański, Michał K.; Kubiak, Marcin; Soszyński, Igor; Pietrzyński, Grzegorz; Poleski, Radosław; Pietrukowicz, Paweł; Pawlak, Michał

    2015-01-01

    We present and study the largest and most comprehensive catalog of microlensing events ever constructed. The sample of standard microlensing events comprises 3718 unique events from 2001-2009 with 1409 events that had not been detected before in real-time by the Early Warning System of the Optical Gravitational Lensing Experiment. The search pipeline uses machine learning algorithms to help find rare phenomena among 150 million objects and to derive the detection efficiency. Applications of the catalog can be numerous, from analyzing individual events to large statistical studies of the Galactic mass, kinematics distributions, and planetary abundances. We derive maps of the mean Einstein ring crossing time of events spanning 31 deg{sup 2} toward the Galactic center and compare the observed distributions with the most recent models. We find good agreement within the observed region and we see the signature of the tilt of the bar in the microlensing data. However, the asymmetry of the mean timescales seems to rise more steeply than predicted, indicating either a somewhat different orientation of the bar or a larger bar width. The map of events with sources in the Galactic bulge shows a dependence of the mean timescale on the Galactic latitude, signaling an increasing contribution from disk lenses closer to the plane relative to the height of the disk. Our data present a perfect set for comparing and enhancing new models of the central parts of the Milky Way and creating a three-dimensional picture of the Galaxy.

  14. Limits on Planetary Companions in Microlensing Event OGLE-BUL-98-14

    NASA Astrophysics Data System (ADS)

    Gaudi, B. S.; Albrow, M. D.; Beaulieu, J. P.; Caldwell, J. A. R.; Depoy, D. L.; Dominik, M.; Gould, A.; Greenhill, J.; Hill, K.; Kane, S.; Martin, R.; Menzies, J.; Naber, R. M.; Pogge, R. W.; Pollard, K.; Sackett, P. D.; Sahu, K. C.; Vermaak, P.; Watson, R.; Williams, A.

    1998-12-01

    As part of an ongoing effort to detect second order effects in gravitational microlensing events, the Probing Lensing Anomalies NETwork (PLANET) collaboration has obtained nearly continuous photometry of the microlensing event OGLE-BUL-98-14 with four telescopes located in Tasmania, Perth, South Africa and Chile. The complete data set consists of over 500 points in I and 200 in V taken over a period of ~ 120 days, making this one of the most well sampled microlensing events to date. The scatter in I is ~ 2% (1 sigma). OGLE-BUL-98-14 was a high magnification event (maximum magnification > 10) with a timescale of ~ 40 days. These facts, combined with the high sampling rate and good photometry, make this an extremely promising event for detection of second order effects. We find that the observed lightcurve is completely consistent with a point-source point-lens model. We can rule out the presence of a companion with mass ratio >10(-3) over a substantial range of projected separations. Furthermore, the lack of detected finite-source or parallax effects allows us to put a lower limit on the mass of the lens, Mlens > 0.1 Msun.

  15. Search for low-mass exoplanets by gravitational microlensing at high magnification.

    PubMed

    Abe, F; Bennett, D P; Bond, I A; Eguchi, S; Furuta, Y; Hearnshaw, J B; Kamiya, K; Kilmartin, P M; Kurata, Y; Masuda, K; Matsubara, Y; Muraki, Y; Noda, S; Okajima, K; Rakich, A; Rattenbury, N J; Sako, T; Sekiguchi, T; Sullivan, D J; Sumi, T; Tristram, P J; Yanagisawa, T; Yock, P C M; Gal-Yam, A; Lipkin, Y; Maoz, D; Ofek, E O; Udalski, A; Szewczyk, O; Zebrun, K; Soszynski, I; Szymanski, M K; Kubiak, M; Pietrzynski, G; Wyrzykowski, L

    2004-08-27

    Observations of the gravitational microlensing event MOA 2003-BLG-32/OGLE 2003-BLG-219 are presented, for which the peak magnification was over 500, the highest yet reported. Continuous observations around the peak enabled a sensitive search for planets orbiting the lens star. No planets were detected. Planets 1.3 times heavier than Earth were excluded from more than 50% of the projected annular region from approximately 2.3 to 3.6 astronomical units surrounding the lens star, Uranus-mass planets were excluded from 0.9 to 8.7 astronomical units, and planets 1.3 times heavier than Saturn were excluded from 0.2 to 60 astronomical units. These are the largest regions of sensitivity yet achieved in searches for extrasolar planets orbiting any star.

  16. The first radial velocity measurements of a microlensing event: no evidence for the predicted binary⋆

    NASA Astrophysics Data System (ADS)

    Boisse, I.; Santerne, A.; Beaulieu, J.-P.; Fakhardji, W.; Santos, N. C.; Figueira, P.; Sousa, S. G.; Ranc, C.

    2015-10-01

    The gravitational microlensing technique allows the discovery of exoplanets around stars distributed in the disk of the galaxy towards the bulge. The alignment of two stars that led to the discovery is unique over the timescale of a human life, however, and cannot be re-observed. Moreover, the target host is often very faint and located in a crowded region. These difficulties hamper and often make impossible the follow up of the target and study of its possible companions. A radial-velocity curve was predicted for the binary system, OGLE-2011-BLG-0417, discovered and characterised from a microlensing event. We used the UVES spectrograph mounted at the VLT, ESO to derive precise radial-velocity measurements of OGLE-2011-BLG-0417. To gather high-precision radial velocities on faint targets of microlensing events, we proposed to use the source star as a reference to measure the lens radial velocities. We obtained ten radial velocities on the putative V = 18 lens with a dispersion of ~100 m s-1, spread over one year. Our measurements do not confirm the microlensing prediction for this binary system. The most likely scenario is that the putative V = 18 mag lens is actually a blend and not the primary lens which is 2 mag fainter. Further observations and analyses are needed to understand the microlensing observation and infer on the nature and characteristics of the lens itself. Based on observations made with ESO Telescope at the Paranal Observatory under program ID 092.C-0763(A) and 093.C-0532(A).Appendix A is available in electronic form at http://www.aanda.org

  17. Predictions for microlensing planetary events from core accretion theory

    SciTech Connect

    Zhu, Wei; Mao, Shude; Penny, Matthew; Gould, Andrew; Gendron, Rieul

    2014-06-10

    We conduct the first microlensing simulation in the context of a planet formation model. The planet population is taken from the Ida and Lin core accretion model for 0.3 M {sub ☉} stars. With 6690 microlensing events, we find that for a simplified Korea Microlensing Telescopes Network (KMTNet), the fraction of planetary events is 2.9%, out of which 5.5% show multiple-planet signatures. The numbers of super-Earths, super-Neptunes, and super-Jupiters detected are expected to be almost equal. Our simulation shows that high-magnification events and massive planets are favored by planet detections, which is consistent with previous expectation. However, we notice that extremely high-magnification events are less sensitive to planets, which is possibly because the 10 minute sampling of KMTNet is not intensive enough to capture the subtle anomalies that occur near the peak. This suggests that while KMTNet observations can be systematically analyzed without reference to any follow-up data, follow-up observations will be essential in extracting the full science potential of very high magnification events. The uniformly high-cadence observations expected for KMTNet also result in ∼55% of all detected planets not being caustic crossing, and more low-mass planets even down to Mars mass being detected via planetary caustics. We also find that the distributions of orbital inclinations and planet mass ratios in multiple-planet events agree with the intrinsic distributions.

  18. Predictions for Microlensing Planetary Events from Core Accretion Theory

    NASA Astrophysics Data System (ADS)

    Zhu, Wei; Penny, Matthew; Mao, Shude; Gould, Andrew; Gendron, Rieul

    2014-06-01

    We conduct the first microlensing simulation in the context of a planet formation model. The planet population is taken from the Ida & Lin core accretion model for 0.3 M ⊙ stars. With 6690 microlensing events, we find that for a simplified Korea Microlensing Telescopes Network (KMTNet), the fraction of planetary events is 2.9%, out of which 5.5% show multiple-planet signatures. The numbers of super-Earths, super-Neptunes, and super-Jupiters detected are expected to be almost equal. Our simulation shows that high-magnification events and massive planets are favored by planet detections, which is consistent with previous expectation. However, we notice that extremely high-magnification events are less sensitive to planets, which is possibly because the 10 minute sampling of KMTNet is not intensive enough to capture the subtle anomalies that occur near the peak. This suggests that while KMTNet observations can be systematically analyzed without reference to any follow-up data, follow-up observations will be essential in extracting the full science potential of very high magnification events. The uniformly high-cadence observations expected for KMTNet also result in ~55% of all detected planets not being caustic crossing, and more low-mass planets even down to Mars mass being detected via planetary caustics. We also find that the distributions of orbital inclinations and planet mass ratios in multiple-planet events agree with the intrinsic distributions.

  19. Galactic Bulge Microlensing Events from the MACHO Collaboration

    SciTech Connect

    Thomas, C L; Griest, K; Popowski, P; Cook, K H; Drake, A J; Minniti, D; Myer, D G; Alcock, C; Allsman, R A; Alves, D R; Axelrod, T S; Becker, A C; Bennett, D P; Freeman, K C; Geha, M; Lehner, M J; Marshall, S L; Nelson, C A; Peterson, B A; Quinn, P J; Stubbs, C W; Sutherland, W; Vandehei, T; Welch, D L

    2005-06-16

    The authors present a catalog of 450 relatively high signal-to-noise microlensing events observed by the MACHO collaboration between 1993 and 1999. The events are distributed throughout the fields and, as expected, they show clear concentration toward the Galactic center. No optical depth is given for this sample since no blending efficiency calculation has been performed, and they find evidence for substantial blending. In a companion paper they give optical depths for the sub-sample of events on clump giant source stars, where blending is a less significant effect. Several events with sources that may belong to the Sagittarius dwarf galaxy are identified. For these events even relatively low dispersion spectra could suffice to classify these events as either consistent with Sagittarius membership or as non-Sagittarius sources. Several unusual events, such as microlensing of periodic variable source stars, binary lens events, and an event showing extended source effects are identified. They also identify a number of contaminating background events as cataclysmic variable stars.

  20. Limits on the Mass and Abundance of Primordial Black Holes from Quasar Gravitational Microlensing

    NASA Astrophysics Data System (ADS)

    Mediavilla, E.; Jiménez-Vicente, J.; Muñoz, J. A.; Vives-Arias, H.; Calderón-Infante, J.

    2017-02-01

    The idea that dark matter can be made of intermediate-mass primordial black holes (PBHs) in the 10 M ⊙ ≲ M ≲ 200 M ⊙ range has recently been reconsidered, particularly in the light of the detection of gravitational waves by the LIGO experiment. The existence of even a small fraction of dark matter in black holes should nevertheless result in noticeable quasar gravitational microlensing. Quasar microlensing is sensitive to any type of compact objects in the lens galaxy, to their abundance, and to their mass. We have analyzed optical and X-ray microlensing data from 24 gravitationally lensed quasars to estimate the abundance of compact objects in a very wide range of masses. We conclude that the fraction of mass in black holes or any type of compact objects is negligible outside of the 0.05 M ⊙ ≲ M ≲ 0.45 M ⊙ mass range and that it amounts to 20% ± 5% of the total matter, in agreement with the expected masses and abundances of the stellar component. Consequently, the existence of a significant population of intermediate-mass PBHs appears to be inconsistent with current microlensing observations. Therefore, primordial massive black holes are a very unlikely source of the gravitational radiation detected by LIGO.

  1. Can gravitational microlensing be used to probe geometry of a massive black-hole?

    NASA Astrophysics Data System (ADS)

    Popović, Luka Č.; Jovanović, Predrag

    2007-04-01

    Astronomical Observatory, Belgrade, Yugoslavia (Serbia and Montenegro) Here we discuss the possibility to use gravitational microlensing in order to probe the geometry around a massive black hole. Taking into account that lensed quasars are emitting X-rays which come from the heart of these objects (around a massive black hole), we investigated the influence of microlensing on the shape of the X-ray continuum/Fe K-alpha line variability due to microlensing by stars from a foreground galaxy [1,2]. We considered an X-ray accretion disk in Schwarzschild and Kerr metrics that is microlensed by a straight-fold caustic and a magnification pattern [2]. We found that the changes in the shape of the X-ray continuum as well as Fe K-alpha line due to microlensing depend on assumed metrics. This shows that microlensing can be used to investigate an unresolved X-ray emitting region geometry around massive black holes. [1] Popović, L.Č., Mediavilla, E.G.; Jovanović, P., Muñoz, J.A. 2003 A& A...398..975P [2] Popović, L. Č., Jovanović, P., Mediavilla, E.; Zakharov, A. F.; Abajas, C.; Muñoz, J. A.; Chartas, G. 2005, ApJ (to be published in February 2006; astro-ph /0510271).

  2. Long-term monitoring, time delay, and microlensing in the gravitational lens system Q0142-100

    SciTech Connect

    Oscoz, A.; Serra-Ricart, M.; Mediavilla, E.

    2013-12-20

    We present 12 yr of monitoring of the gravitational lens Q0142-100 from the Teide Observatory. The data, taken from 1999 to 2010, comprise 105 observing nights with the IAC80 Telescope. The application of the δ{sup 2} method to the dataset leads to a value for the time delay between both components of the system of 72 ± 22 days (68% confidence level), consistent within uncertainties with the most recent results. With this value in mind a possible microlensing event is detected in Q0142-100.

  3. Microlensing in the Q0957 + 561 gravitational mirage

    SciTech Connect

    Schild, R.E.; Smith, R.C. )

    1991-03-01

    Analysis of the 10 yr record from monitoring the continuum brightness of Q0957 + 561 A, B shows a systematic increase of the B relative to the A component. The B brightness has leveled off in the last 2 yr at a value 32 percent higher than would be predicted from the ratio of Mg II 2798 A emission line strengths. This is taken to be the signature of microlensing by a star or stars in the lens galaxy. 11 refs.

  4. Detecting Earth-Mass Planets with Gravitational Microlensing

    NASA Astrophysics Data System (ADS)

    Bennett, David P.; Rhie, Sun Hong

    1996-11-01

    We show that Earth-mass planets orbiting stars in the Galactic disk and bulge can be detected by monitoring microlensed stars in the Galactic bulge. The star and its planet act as a binary lens which generates a light curve that can differ substantially from the light curve due only to the star itself. We show that the planetary signal remains detectable for planetary masses as small as an Earth mass when realistic source star sizes are included in the light curve calculation. These planets are detectable if they reside in the "lensing zone," which is centered between 1 and 4 AU from the lensing star and spans about a factor of 2 in distance. If we require a minimum deviation of 4% from the standard point-lens microlensing light curve, then we find that more than 2% of all M⊕ planets and 10% of all 10 M⊕ in the lensing zone can be detected. If a third of all lenses have no planets, a third have 1 M⊕ planets, and the remaining third have 10 M⊕ planets then we estimate that an aggressive ground-based microlensing planet search program could find one Earth-mass planet and half a dozen 10 M⊕ planets per year.

  5. "Rare" Microlensing Events: how frequent are they? what can they teach us?

    NASA Astrophysics Data System (ADS)

    Di Stefano, Rosanne; Bryk, William; Ginsburg, Idan; Greiner, Jochen; Lepine, Sebastien; Oprescu, Antonia; Primini, Francis A.; Tunbridge, Ben

    2014-06-01

    Today's microlensing teams discover roughly 2000 candidate microlensing events per year. Many of these exhibit the standard point-source/point-lens form, and are caused by distant lenses we cannot detect. In our poster we report on the preliminary results of a long term program of analysis designed to identify and study "rare" gravitational lensing events. We have focused on those rare events with light curve profiles that differ from the point-source/point-lens form. These unusual light curves provide additional information about the lens or source. We devote special effort to the study of a small set of events that appear to have been caused by nearby lenses. Nearby lenses are interesting, whatever the form of the light curve they generate. We show that some unusual events are common enough that their systematic study can be scientifically fruitful, allowing lensing programs to identify nearby (closer than a kiloparsec) compact objects and measure their masses, and to also identify and measure masses in nearby planetary systems. We have developed methods that should prove useful in a wide range of ground-based and space-based lensing studies.

  6. Empirical study of simulated two-planet microlensing events

    SciTech Connect

    Zhu, Wei; Gould, Andrew; Penny, Matthew; Mao, Shude; Gendron, Rieul

    2014-10-10

    We undertake the first study of two-planet microlensing models recovered from simulations of microlensing events generated by realistic multiplanet systems in which 292 planetary events, including 16 two-planet events, were detected from 6690 simulated light curves. We find that when two planets are recovered, their parameters are usually close to those of the two planets in the system most responsible for the perturbations. However, in 1 of the 16 examples, the apparent mass of both detected planets was more than doubled by the unmodeled influence of a third, massive planet. This fraction is larger than but statistically consistent with the roughly 1.5% rate of serious mass errors due to unmodeled planetary companions for the 274 cases from the same simulation in which a single planet is recovered. We conjecture that an analogous effect due to unmodeled stellar companions may occur more frequently. For 7 out of 23 cases in which two planets in the system would have been detected separately, only one planet was recovered because the perturbations due to the two planets had similar forms. This is a small fraction (7/274) of all recovered single-planet models, but almost a third of all events that might plausibly have led to two-planet models. Still, in these cases, the recovered planet tends to have parameters similar to one of the two real planets most responsible for the anomaly.

  7. Gravitational microlensing - Powerful combination of ray-shooting and parametric representation of caustics

    NASA Technical Reports Server (NTRS)

    Wambsganss, J.; Witt, H. J.; Schneider, P.

    1992-01-01

    We present a combination of two very different methods for numerically calculating the effects of gravitational microlensing: the backward-ray-tracing that results in two-dimensional magnification patterns, and the parametric representation of caustic lines; they are in a way complementary to each other. The combination of these methods is much more powerful than the sum of its parts. It allows to determine the total magnification and the number of microimages as a function of source position. The mean number of microimages is calculated analytically and compared to the numerical results. The peaks in the lightcurves, as obtained from one-dimensional tracks through the magnification pattern, can now be divided into two groups: those which correspond to a source crossing a caustic, and those which are due to sources passing outside cusps. We determine the frequencies of those two types of events as a function of the surface mass density, and the probability distributions of their magnitudes. We find that for low surface mass density as many as 40 percent of all events in a lightcurve are not due to caustic crossings, but rather due to passings outside cusps.

  8. VizieR Online Data Catalog: OGLE microlensing events in Galactic Bulge (Udalski+, 2000)

    NASA Astrophysics Data System (ADS)

    Udalski, A.; Zebrun, K.; Szymanski, M.; Kubiak, M.; Pietrzynski, G.; Soszynski, I.; Wozniak, P.

    2006-09-01

    We present the Catalog of microlensing events detected toward the Galactic bulge in three observing seasons, 1997-1999, during the OGLE-II microlensing survey. The search for microlensing events was performed using a database of about 4x109 photometric measurements of about 20.5 million stars from the Galactic bulge. The Catalog comprises 214 microlensing events found in the fields covering about 11 square degrees on the sky and distributed in different parts of the Galactic bulge. The sample includes 20 binary microlensing events, 14 of them are caustic crossing. In one case a double star is likely lensed. We present distribution of the basic parameters of microlensing events and show preliminary rate of microlensing in different regions of the Galactic bulge. The latter reveals clear dependence on the Galactic coordinates. The dependence on l indicates that the majority of lenses toward the Galactic bulge are located in the Galactic bar. Models of the Galactic bar seem to reasonably predict the observed spatial distribution of microlensing events in the Galactic bulge. All data presented in the Catalog and photometry of all events are available from the OGLE Internet archive. (3 data files).

  9. Gravitational microlensing - The effect of random motion of individual stars in the lensing galaxy

    NASA Technical Reports Server (NTRS)

    Kundic, Tomislav; Wambsganss, Joachim

    1993-01-01

    We investigate the influence of random motion of individual stars in the lensing galaxy on the light curve of a gravitationally lensed background quasar. We compare this with the effects of the transverse motion of the galaxy. We find that three-dimensional random motion of stars with a velocity dispersion sigma in each dimension is more effective in producing 'peaks' in a microlensed light curve by a factor a about 1.3 than motion of the galaxy with a transverse velocity v(t) = sigma. This effectiveness parameter a seems to depend only weakly on the surface mass density. With an assumed transverse velocity of v(t) = 600 km/s of the galaxy lensing the QSO 2237+0305 and a measured velocity dispersion of sigma = 215 km/s, the expected rate of maxima in the light curves calculated for bulk motion alone has to be increased by about 10 percent due to the random motion of stars. As a consequence, the average time interval Delta t between two high-magnification events is smaller than the time interval Delta(t) bulk, calculated for bulk motion alone, Delta t about 0.9 Delta(t) bulk.

  10. Galactic Distribution of Planets From High-Magnification Microlensing Events

    NASA Astrophysics Data System (ADS)

    Gould, Andrew; Yee, Jennifer; Carey, Sean

    2015-10-01

    We will use Spitzer to measure microlens parallaxes for ~14 microlensing events that are high-magnification (as seen from Earth), in order to determine the Galactic distribution of planets. Simultaneous observations from Spitzer and Earth yield parallaxes because they are separated by ~1 AU, which is of order the size of the Einstein radius projected on the observer plane. Hence, Earth and Spitzer see substantially different lightcurves for the same event. These Spitzer parallaxes enable measurements of the distances to the lenses (and their masses), which is a crucial element for measuring the Galactic distribution of planets. High-mag events are exceptionally sensitive to planets: Gould+ (2010) detected 6 planets from 13 high-mag events. However, previously it was believed impossible to measure their parallaxes using Spitzer: scheduling constraints imply a 3-10 day delay from event recognition to first observation, while high-mag events are typically recognized only 1-2 days before peak. By combining aggressive observing protocols, a completely new photometry pipeline, and new mathematical techniques, we successfully measured parallaxes for 7 events with peak magnification A>100 and another ~7 with 50events. From this sample, we expect to detect ~4 planets (the number is smaller than Gould+ 2010 because our Spitzer sample will have lower mean magnification). These ~4 planets represent significant progress toward the ~12 necessary to measure the Galactic distribution. All lightcurves will be reduced using our customized software and then made public (unrestricted use), within 2 months of the completion of observations (as we did for our 2015 observations).

  11. Planets, Moons, and Multiple Stars - Gravitational Microlensing by Three-Body Systems

    NASA Astrophysics Data System (ADS)

    Heyrovsky, David; Danek, Kamil

    2017-01-01

    Gravitational microlensing has proved to be a useful tool for detecting exoplanets, particularly those separated a few AU from the lens star. Of the 43 microlensing-detected planets published so far, four are members of two-planet systems, and a further three are associated with binary stars (two circumprimary and one circumbinary). While the lensing by a single star with a single planet is well understood, systematic insight into the substantially more diverse lensing by three-body systems is still lacking. We introduce efficient methods for studying and visualizing the different regimes of lensing by a triple lens with a given combination of masses. For illustration, we present here full analyses of critical-curve regimes of the following lenses in arbitrary spatial configuration: an equal-mass triple, an equal-mass binary with a planet, and a hierarchical star-planet-moon system. Such studies can facilitate the interpretation and analysis of observed microlensing light curves due to triple lenses.

  12. Application of Compressive Sensing to Gravitational Microlensing Data and Implications for Miniaturized Space Observatories

    NASA Technical Reports Server (NTRS)

    Korde-Patel, Asmita (Inventor); Barry, Richard K.; Mohsenin, Tinoosh

    2016-01-01

    Compressive Sensing is a technique for simultaneous acquisition and compression of data that is sparse or can be made sparse in some domain. It is currently under intense development and has been profitably employed for industrial and medical applications. We here describe the use of this technique for the processing of astronomical data. We outline the procedure as applied to exoplanet gravitational microlensing and analyze measurement results and uncertainty values. We describe implications for on-spacecraft data processing for space observatories. Our findings suggest that application of these techniques may yield significant, enabling benefits especially for power and volume-limited space applications such as miniaturized or micro-constellation satellites.

  13. Quasar microlensing

    NASA Astrophysics Data System (ADS)

    Schmidt, R. W.; Wambsganss, J.

    2010-09-01

    Quasar microlensing deals with the effect of compact objects along the line of sight on the apparent brightness of the background quasars. Due to the relative motion between quasar, lenses and observer, the microlensing magnification changes with time which results in uncorrelated brightness variations in the various images of multiple quasar systems. The amplitudes of the signal can be more than a magnitude with time scales of weeks to months to years. The effect is due to the “granular” nature of the gravitational microlenses—stars or other compact objects in the stellar mass range. Quasar microlensing allows to study the quasar accretion disk with a resolution of tens of microarcseconds, hence quasar microlensing can be used to explore an astrophysical field that is hardly accessible by any other means. Quasar microlensing can also be used to study the lensing objects in a statistical sense, their nature (compact or smoothly distributed, normal stars or dark matter) as well as transverse velocities. Quasar microlensing light curves are now being obtained from monitoring programs across the electromagnetic spectrum from the radio through the infrared and optical range to the X-ray regime. Recently, spectroscopic microlensing was successfully applied, it provides quantitative comparisons with quasar/accretion disk models. There are now more than a handful of systems with several-year long light curves and significant microlensing signal, lending to detailed analysis. This review summarizes the current state of the art of quasar microlensing and shows that at this point in time, observational monitoring programs and complementary intense simulations provide a scenario where some of the early promises of quasar microlensing can be quantitatively applied. It has been shown, e.g., that smaller sources display more violent microlensing variability, first quantitative comparison with accretion disk models has been achieved, and quasar microlensing has been used to

  14. Polarimetric microlensing of circumstellar discs

    NASA Astrophysics Data System (ADS)

    Sajadian, Sedighe; Rahvar, Sohrab

    2015-12-01

    We study the benefits of polarimetry observations of microlensing events to detect and characterize circumstellar discs around the microlensed stars located at the Galactic bulge. These discs which are unresolvable from their host stars make a net polarization effect due to their projected elliptical shapes. Gravitational microlensing can magnify these signals and make them be resolved. The main aim of this work is to determine what extra information about these discs can be extracted from polarimetry observations of microlensing events in addition to those given by photometry ones. Hot discs which are closer to their host stars are more likely to be detected by microlensing, owing to more contributions in the total flux. By considering this kind of discs, we show that although the polarimetric efficiency for detecting discs is similar to the photometric observation, but polarimetry observations can help to constraint the disc geometrical parameters e.g. the disc inner radius and the lens trajectory with respect to the disc semimajor axis. On the other hand, the time-scale of polarimetric curves of these microlensing events generally increases while their photometric time-scale does not change. By performing a Monte Carlo simulation, we show that almost four optically thin discs around the Galactic bulge sources are detected (or even characterized) through photometry (or polarimetry) observations of high-magnification microlensing events during 10-yr monitoring of 150 million objects.

  15. Central engine of a gamma-ray blazar resolved through the magnifying glass of gravitational microlensing

    NASA Astrophysics Data System (ADS)

    Neronov, Andrii; Vovk, Ievgen; Malyshev, Denys

    2015-08-01

    Gamma-ray emission from blazars is known to originate from jets emitted by supermassive black holes. However, the exact location and size of the γ-ray emitting part of the jets is uncertain. The main difficulty is the very small angular size of these sources, beyond the angular resolution of γ-ray telescopes. Here, we report a measurement of the projected size of the γ-ray jet, revealed by the detection of microlensing in the gravitationally lensed blazar PKS 1830-211. This measurement is consistent with a constraint from the intrinsic variability timescale of the blazar. Our measurement shows that the γ-ray emission originates from the vicinity of the central supermassive black hole. Combining the X-ray and γ-ray data, we use the microlensing effect to constrain the size of the X-ray source. We show that the effect of pair production of γ-rays on X-ray photons does not make the source opaque, owing to the large size of the X-ray emission region.

  16. Predicting the 4th caustic crossing in Gaia16aye binary microlensing event

    NASA Astrophysics Data System (ADS)

    Mroz, P.; Wyrzykowski, L.; Rybicki, K.; Altavilla, G.; Bakis, V.; Bendjoya, P.; Birenbaum, G.; Blagorodnova, N.; Blanco-Cuaresma, S.; Bonanos, A.; Bozza, V.; Britavskiy, N.; Burgaz, U.; Butterley, T.; Capuozzo, P.; Carrasco, J. M.; Chruslinska, M.; Damljanovic, G.; Dennefeld, M.; Dhillon, V. S.; Dominik, M.; Esenoglu, H.; Fossey, S.; Gomboc, A.; Hallokoun, N.; Hamanowicz, A.; Hardy, L. K.; Hudec, R.; Khamitov, I.; Klencki, J.; Kolaczkowski, Z.; Kolb, U.; Leonini, S.; Leto, G.; Lewis, F.; Liakos, A.; Littlefair, S. P.; Maoz, D.; Maund, J. R.; Mikolajczyk, P.; Palaversa, L.; Pawlak, M.; Penny, M.; Piascik, A.; Reig, P.; Rhodes, L.; Russell, D.; Sanchez, R. Z.; Shappee, B.; Shvartzvald, Y.; Sitek, M.; Sniegowska, M.; Sokolovsky, K.; Steele, I.; Street, R.; Tomasella, L.; Trascinelli, L.; Wiersema, K.; Wilson, R. W.; Zharkov, I.; Zola, S.; Zubareva, A.

    2016-11-01

    Gaia16aye, nicknamed Ayers Rock (19:40:01.13 +30:07:53.4, J2000) is a spectacular binary microlensing event in the Northern Galactic Plane. The event has been observed by Gaia, ASAS-SN survey and a network of follow-up telescopes, coordinated by the Time Domain WP of the EC's OPTICON grant.

  17. The different origins of high- and low-ionization broad emission lines revealed by gravitational microlensing in the Einstein cross

    NASA Astrophysics Data System (ADS)

    Braibant, L.; Hutsemékers, D.; Sluse, D.; Anguita, T.

    2016-07-01

    We investigate the kinematics and ionization structure of the broad emission line region of the gravitationally lensed quasar QSO2237+0305 (the Einstein cross) using differential microlensing in the high- and low-ionization broad emission lines. We combine visible and near-infrared spectra of the four images of the lensed quasar and detect a large-amplitude microlensing effect distorting the high-ionization CIV and low-ionization Hα line profiles in image A. While microlensing only magnifies the red wing of the Balmer line, it symmetrically magnifies the wings of the CIV emission line. Given that the same microlensing pattern magnifies both the high- and low-ionization broad emission line regions, these dissimilar distortions of the line profiles suggest that the high- and low-ionization regions are governed by different kinematics. Since this quasar is likely viewed at intermediate inclination, we argue that the differential magnification of the blue and red wings of Hα favors a flattened, virialized, low-ionization region whereas the symmetric microlensing effect measured in CIV can be reproduced by an emission line formed in a polar wind, without the need of fine-tuned caustic configurations. Based on observations made with the ESO-VLT, Paranal, Chile; Proposals 076.B-0197 and 076.B-0607 (PI: Courbin).

  18. Microlensing Planets

    NASA Astrophysics Data System (ADS)

    Gould, Andrew

    The theory and practice of microlensing planet searches is developed in a systematic way, from an elementary treatment of the deflection of light by a massive body to a thorough discussion of the most recent results. The main concepts of planetary microlensing, including microlensing events, finite-source effects, and microlens parallax, are first introduced within the simpler context of point-lens events. These ideas are then applied to binary (and hence planetary) lenses and are integrated with concepts specific to binaries, including caustic topologies, orbital motion, and degeneracies, with an emphasis on analytic understanding. The most important results from microlensing planet searches are then reviewed, with emphasis both on understanding the historical process of discovery and the means by which scientific conclusions were drawn from light-curve analysis. Finally, the future prospects of microlensing planets searches are critically evaluated. Citations to original works provide the reader with multiple entry points into the literature.

  19. Using graphical and pictorial representations to teach introductory astronomy students about the detection of extrasolar planets via gravitational microlensing

    NASA Astrophysics Data System (ADS)

    Wallace, Colin S.; Chambers, Timothy G.; Prather, Edward E.; Brissenden, Gina

    2016-05-01

    The detection and study of extrasolar planets is an exciting and thriving field in modern astrophysics and an increasingly popular topic in introductory astronomy courses. One detection method relies on searching for stars whose light has been gravitationally microlensed by an extrasolar planet. In order to facilitate instructors' abilities to bring this interesting mix of general relativity and extrasolar planet detection into the introductory astronomy classroom, we have developed a new Lecture-Tutorial called "Detecting Exoplanets with Gravitational Microlensing." In this paper, we describe how this new Lecture-Tutorial's representations of astrophysical phenomena, which we selected and created based on theoretically motivated considerations of their pedagogical affordances, are used to help introductory astronomy students develop more expert-like reasoning abilities.

  20. BINARY ASTROMETRIC MICROLENSING WITH GAIA

    SciTech Connect

    Sajadian, Sedighe

    2015-04-15

    We investigate whether or not Gaia can specify the binary fractions of massive stellar populations in the Galactic disk through astrometric microlensing. Furthermore, we study whether or not some information about their mass distributions can be inferred via this method. In this regard, we simulate the binary astrometric microlensing events due to massive stellar populations according to the Gaia observing strategy by considering (i) stellar-mass black holes, (ii) neutron stars, (iii) white dwarfs, and (iv) main-sequence stars as microlenses. The Gaia efficiency for detecting the binary signatures in binary astrometric microlensing events is ∼10%–20%. By calculating the optical depth due to the mentioned stellar populations, the numbers of the binary astrometric microlensing events being observed with Gaia with detectable binary signatures, for the binary fraction of about 0.1, are estimated to be 6, 11, 77, and 1316, respectively. Consequently, Gaia can potentially specify the binary fractions of these massive stellar populations. However, the binary fraction of black holes measured with this method has a large uncertainty owing to a low number of the estimated events. Knowing the binary fractions in massive stellar populations helps with studying the gravitational waves. Moreover, we investigate the number of massive microlenses for which Gaia specifies masses through astrometric microlensing of single lenses toward the Galactic bulge. The resulting efficiencies of measuring the mass of mentioned populations are 9.8%, 2.9%, 1.2%, and 0.8%, respectively. The numbers of their astrometric microlensing events being observed in the Gaia era in which the lens mass can be inferred with the relative error less than 0.5 toward the Galactic bulge are estimated as 45, 34, 76, and 786, respectively. Hence, Gaia potentially gives us some information about the mass distribution of these massive stellar populations.

  1. A NEW MICROLENSING EVENT IN THE DOUBLY IMAGED QUASAR Q 0957+561

    SciTech Connect

    Hainline, Laura J.; Morgan, Christopher W.; Beach, Joseph N.; Le, Truong X.; Kochanek, C. S.; Harris, Hugh C.; Tilleman, Trudy; Fadely, Ross; Falco, Emilio E. E-mail: cmorgan@usna.edu E-mail: m113678@usna.edu E-mail: hch@nofs.navy.mil E-mail: rfadely@haverford.edu

    2012-01-10

    We present evidence for ultraviolet/optical microlensing in the gravitationally lensed quasar Q 0957+561. We combine new measurements from our optical monitoring campaign at the United States Naval Observatory, Flagstaff, with measurements from the literature and find that the time-delay-corrected r-band flux ratio m{sub A} - m{sub B} has increased by {approx}0.1 mag over a period of five years beginning in the fall of 2005. We apply our Monte Carlo microlensing analysis procedure to the composite light curves, obtaining a measurement of the optical accretion disk size, log ((r{sub s} /cm)[cos (i)/0.5]{sup 1/2}) = 16.2 {+-} 0.5, that is consistent with the quasar accretion disk size-black hole mass relation.

  2. UKIRT Microlensing Surveys as a Pathfinder for WFIRST: The Detection of Five Highly Extinguished Low-∣b∣ Events

    NASA Astrophysics Data System (ADS)

    Shvartzvald, Y.; Bryden, G.; Gould, A.; Henderson, C. B.; Howell, S. B.; Beichman, C.

    2017-02-01

    Optical microlensing surveys are restricted from detecting events near the Galactic plane and center, where the event rate is thought to be the highest due to the high optical extinction of these fields. In the near-infrared (NIR), however, the lower extinction leads to a corresponding increase in event detections and is a primary driver for the wavelength coverage of the WFIRST microlensing survey. During the 2015 and 2016 bulge observing seasons, we conducted NIR microlensing surveys with UKIRT in conjunction with and in support of the Spitzer and Kepler microlensing campaigns. Here, we report on five highly extinguished ({A}H=0.81{--}1.97), low-Galactic latitude (-0.98≤slant b≤slant -0.36) microlensing events discovered from our 2016 survey. Four of them were monitored with an hourly cadence by optical surveys but were not reported as discoveries, likely due to the high extinction. Our UKIRT surveys and suggested future NIR surveys enable the first measurement of the microlensing event rate in the NIR. This wavelength regime overlaps with the bandpass of the filter in which the WFIRST microlensing survey will conduct its highest-cadence observations, making this event rate derivation critically important for optimizing its yield.

  3. Spectroscopic characterisation of microlensing events. Towards a new interpretation of OGLE-2011-BLG-0417

    NASA Astrophysics Data System (ADS)

    Santerne, A.; Beaulieu, J.-P.; Rojas Ayala, B.; Boisse, I.; Schlawin, E.; Almenara, J.-M.; Batista, V.; Bennett, D.; Díaz, R. F.; Figueira, P.; James, D. J.; Herter, T.; Lillo-Box, J.; Marquette, J. B.; Ranc, C.; Santos, N. C.; Sousa, S. G.

    2016-11-01

    The microlensing event OGLE-2011-BLG-0417 is an exceptionally bright lens binary that was predicted to present radial velocity variation at the level of several km s-1. Pioneer radial velocity follow-up observations with the UVES spectrograph at the ESO-VLT of this system clearly ruled out the large radial velocity variation, leaving a discrepancy between the observation and the prediction. In this paper, we further characterise the microlensing system by analysing its spectral energy distribution (SED) derived using the UVES spectrum and new observations with the ARCoIRIS (CTIO) near-infrared spectrograph and the Keck adaptive optics instrument NIRC2 in the J, H, and Ks-bands. We determine the mass and distance of the stars independently from the microlensing modelling. We find that the SED is compatible with a giant star in the Galactic bulge and a foreground star with a mass of 0.94 ± 0.09 M⊙ at a distance of 1.07 ± 0.24 kpc. We find that this foreground star is likely the lens. Its parameters are not compatible with the ones previously reported in the literature (0.52 ± 0.04 M⊙ at 0.95 ± 0.06 kpc), based on the microlensing light curve. A thoughtful re-analysis of the microlensing event is mandatory to fully understand the reason of this new discrepancy. More importantly, this paper demonstrates that spectroscopic follow-up observations of microlensing events are possible and provide independent constraints on the parameters of the lens and source stars, hence breaking some degeneracies in the analysis. UV-to-NIR low-resolution spectrographs like X-shooter (ESO-VLT) could substantially contribute to this follow-up efforts, with magnitude limits above all microlensing events detected so far. Based on observations made with ESO Telescope at the Paranal Observatory under program ID 092.C-0763(A) and 093.C-0532(A).Based on observations at Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, which is operated by the Association of

  4. Beyond the Wobbles: Teaching Students About Detecting Planets with the Transit and Gravitational Microlensing Methods

    NASA Astrophysics Data System (ADS)

    Prather, Edward E.; Wallace, Colin Scott; Chambers, Timothy G.; Brissenden, Gina; Traub, Wesley A.; Greene, W. M.; Biferno, Anya A.; Rodriguez, Joshua

    2015-01-01

    Members of the Center for Astronomy Education (CAE) at the University of Arizona's Steward Observatory in collaboration with JPL scientists, visualization experts, and education and public outreach professionals with the Exoplanet Exploration Program (ExEP) have recently completed classroom field-testing of a new suite of educational materials to help learners better understand how extrasolar planets are detected using the transit and gravitational microlensing techniques. This collaboration has created a set of evidence-based Think-Pair-Share questions, Lecture-Tutorials, animations, presentation slides, and instrucotrs guide that can be used together or separately to actively engage learners in reasoning about the data and scientific representations associated with these exciting new extrasolar planet detection methods. In this talk we present several of the conceptually challenging collaborative learning tasks that students encounter with this new suite of educational materials and some of the assessment questions we are using to assess the efficacy of their use in general education, college-level astronomy courses.

  5. Red Noise Versus Planetary Interpretations in the Microlensing Event Ogle-2013-BLG-446

    NASA Astrophysics Data System (ADS)

    Bachelet, E.; Bramich, D. M.; Han, C.; Greenhill, J.; Street, R. A.; Gould, A.; D'Ago, G.; AlSubai, K.; Dominik, M.; Figuera Jaimes, R.; Horne, K.; Hundertmark, M.; Kains, N.; Snodgrass, C.; Steele, I. A.; Tsapras, Y.; RoboNet Collaboration; Albrow, M. D.; Batista, V.; Beaulieu, J.-P.; Bennett, D. P.; Brillant, S.; Caldwell, J. A. R.; Cassan, A.; Cole, A.; Coutures, C.; Dieters, S.; Dominis Prester, D.; Donatowicz, J.; Fouqué, P.; Hill, K.; Marquette, J.-B.; Menzies, J.; Pere, C.; Ranc, C.; Wambsganss, J.; Warren, D.; PLANET Collaboration; de Almeida, L. Andrade; Choi, J.-Y.; DePoy, D. L.; Dong, S.; Hung, L.-W.; Hwang, K.-H.; Jablonski, F.; Jung, Y. K.; Kaspi, S.; Klein, N.; Lee, C.-U.; Maoz, D.; Muñoz, J. A.; Nataf, D.; Park, H.; Pogge, R. W.; Polishook, D.; Shin, I.-G.; Shporer, A.; Yee, J. C.; μFUN Collaboration; Abe, F.; Bhattacharya, A.; Bond, I. A.; Botzler, C. S.; Freeman, M.; Fukui, A.; Itow, Y.; Koshimoto, N.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Ohnishi, K.; Philpott, L. C.; Rattenbury, N.; Saito, To.; Sullivan, D. J.; Sumi, T.; Suzuki, D.; Tristram, P. J.; Yonehara, A.; MOA Collaboration; Bozza, V.; Calchi Novati, S.; Ciceri, S.; Galianni, P.; Gu, S.-H.; Harpsøe, K.; Hinse, T. C.; Jørgensen, U. G.; Juncher, D.; Korhonen, H.; Mancini, L.; Melchiorre, C.; Popovas, A.; Postiglione, A.; Rabus, M.; Rahvar, S.; Schmidt, R. W.; Scarpetta, G.; Skottfelt, J.; Southworth, John; Stabile, An.; Surdej, J.; Wang, X.-B.; Wertz, O.; MiNDSTEp Collaboration

    2015-10-01

    For all exoplanet candidates, the reliability of a claimed detection needs to be assessed through a careful study of systematic errors in the data to minimize the false positives rate. We present a method to investigate such systematics in microlensing data sets using the microlensing event OGLE-2013-BLG-0446 as a case study. The event was observed from multiple sites around the world and its high magnification (Amax ˜ 3000) allowed us to investigate the effects of terrestrial and annual parallax. Real-time modeling of the event while it was still ongoing suggested the presence of an extremely low-mass companion (˜3M⊕) to the lensing star, leading to substantial follow-up coverage of the light curve. We test and compare different models for the light curve and conclude that the data do not favor the planetary interpretation when systematic errors are taken into account.

  6. RED NOISE VERSUS PLANETARY INTERPRETATIONS IN THE MICROLENSING EVENT OGLE-2013-BLG-446

    SciTech Connect

    Bachelet, E.; Bramich, D. M.; AlSubai, K.; Han, C.; Greenhill, J.; Street, R. A.; Tsapras, Y.; Gould, A.; Batista, V.; D’Ago, G.; Dominik, M.; Jaimes, R. Figuera; Horne, K.; Hundertmark, M.; Kains, N.; Snodgrass, C.; Steele, I. A.; Albrow, M. D.; Beaulieu, J.-P.; Bennett, D. P. E-mail: p.yock@auckland.ac.nz E-mail: abe@stelab.nagoya-u.ac.jp E-mail: itow@stelab.nagoya-u.ac.jp; Collaboration: RoboNet collaboration; PLANET collaboration; μFUN collaboration; MOA collaboration; MiNDSTEp collaboration; and others

    2015-10-20

    For all exoplanet candidates, the reliability of a claimed detection needs to be assessed through a careful study of systematic errors in the data to minimize the false positives rate. We present a method to investigate such systematics in microlensing data sets using the microlensing event OGLE-2013-BLG-0446 as a case study. The event was observed from multiple sites around the world and its high magnification (A{sub max} ∼ 3000) allowed us to investigate the effects of terrestrial and annual parallax. Real-time modeling of the event while it was still ongoing suggested the presence of an extremely low-mass companion (∼3M{sub ⨁}) to the lensing star, leading to substantial follow-up coverage of the light curve. We test and compare different models for the light curve and conclude that the data do not favor the planetary interpretation when systematic errors are taken into account.

  7. The OGLE view of microlensing towards the Magellanic Clouds - I. A trickle of events in the OGLE-II LMC data

    NASA Astrophysics Data System (ADS)

    Wyrzykowski, Ł.; Kozłowski, S.; Skowron, J.; Belokurov, V.; Smith, M. C.; Udalski, A.; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Szewczyk, O.; Żebruń, K.

    2009-08-01

    We present the results from the Optical Gravitational Lensing Experiment II (OGLE-II) survey (1996-2000) towards the Large Magellanic Cloud (LMC), which has the aim of detecting the microlensing phenomena caused by dark matter compact objects in the Galactic halo [massive compact halo objects (MACHOs)]. We use high-resolution Hubble Space Telescope images of the OGLE fields and derive the correction for the number of monitored stars in each field. This also yields blending distributions which we use in `catalogue-level' Monte Carlo simulations of the microlensing events in order to calculate the detection efficiency of the events. We detect two candidates for microlensing events in the All Stars Sample, which translates into an optical depth of 0.43 +/- 0.33 × 10-7. If both events were due to MACHO, the fraction of mass of compact dark matter objects in the Galactic halo would be 8 +/- 6 per cent. This optical depth, however, along with the characteristics of the events seems to be consistent with the self-lensing scenario, i.e. self-lensing alone is sufficient to explain the observed microlensing signal. Our results indicate the non-detection of MACHOs lensing towards the LMC with an upper limit on their abundance in the Galactic halo of 19 per cent for M = 0.4Msolar and 10 per cent for masses between 0.01 and 0.2Msolar. Based on observations obtained with the 1.3-m Warsaw Telescope at the Las Campanas Observatory of the Carnegie Institution of Washington. E-mail: wyrzykow@ast.cam.ac.uk ‡ Name pronunciation: Woocash Vizhikovsky.

  8. Microlensing events from the 11-year Observations of the Wendelstein Calar Alto Pixellensing Project

    NASA Astrophysics Data System (ADS)

    Lee, C.-H.; Riffeser, A.; Seitz, S.; Bender, R.; Koppenhoefer, J.

    2015-06-01

    We present the results of the decade-long M31 observation from the Wendelstein Calar Alto Pixellensing Project (WeCAPP). WeCAPP has monitored M31 from 1997 until 2008 in both R- and I-filters, and thus provides the longest baseline of all M31 microlensing surveys. The data are analyzed with difference imaging analysis, which is most suitable for studying variability in crowded stellar fields. We extracted light curves based on each pixel, and devised selection criteria that are optimized to identify microlensing events. This leads to 10 new events, and adds up to a total of 12 microlensing events from WeCAPP, for which we derive their timescales, flux excesses, and colors from their light curves. The colors of the lensed stars fall in the range (R - I) = 0.56 to 1.36, with a median of 1.0 mag, in agreement with our expectation that the sources are most likely bright, red stars at the post-main-sequence stage. The event FWHM timescales range from 0.5 to 14 days, with a median of 3 days, in good agreement with predictions based on the model of Riffeser et al.

  9. The POINT-AGAPE survey: comparing automated searches of microlensing events towards M31

    NASA Astrophysics Data System (ADS)

    Tsapras, Y.; Carr, B. J.; Weston, M. J.; Kerins, E.; Baillon, P.; Gould, A.; Paulin-Henriksson, S.

    2010-05-01

    Searching for microlensing in M31 using automated superpixel surveys raises a number of difficulties which are not present in more conventional techniques. Here we focus on the problem that the list of microlensing candidates is sensitive to the selection criteria or `cuts' imposed, and some subjectivity is involved in this. Weakening the cuts will generate a longer list of microlensing candidates but with a greater fraction of spurious ones; strengthening the cuts will produce a shorter list but may exclude some genuine events. We illustrate this by comparing three analyses of the same data set obtained from a 3 yr observing run on the Isaac Newton Telescope in La Palma. The results of two of these analyses have been already reported: Belokurov et al. obtained between three and 22 candidates, depending on the strength of their cuts, while Calchi Novati et al. obtained six candidates. The third analysis is presented here for the first time and reports 10 microlensing candidates, seven of which are new. Only two of the candidates are common to all three analyses. In order to understand why these analyses produce different candidate lists, a comparison is made of the cuts used by the three groups. Particularly crucial are the method employed to distinguish between a microlensing event and a variable star, and the extent to which one encodes theoretical prejudices into the cuts. Another factor is that the superpixel technique requires the masking of resolved stars and bad pixels. Belokurov et al. and the present analysis use the same input catalogue and the same masks but Calchi Novati et al. use different ones and a somewhat less automated procedure. Because of these considerations, one expects the lists of candidates to vary and it is not possible to pronounce a candidate a definite microlensing event. Indeed we accept that several of our new candidates, especially the long time-scale ones, may not be genuine. This uncertainty also impinges on one of the most

  10. Resolving the Innermost Region of the Accretion Disk of the Lensed Quasar Q2237+0305 through Gravitational Microlensing

    NASA Astrophysics Data System (ADS)

    Mediavilla, E.; Jiménez-vicente, J.; Muñoz, J. A.; Mediavilla, T.

    2015-12-01

    We study three high magnification microlensing events, generally recognized as probable caustic crossings, in the optical light curves of the multiply imaged quasar Q2237+0305. We model the light curve of each event as the convolution of a standard thin disk luminosity profile with a straight fold caustic. We also allow for a linear gradient that can account for an additional varying background effect of microlensing. This model not only matches noticeably well the global shape of each of the three independent microlensing events but also gives remarkably similar estimates for the disk size parameter. The measured average half-light radius, {R}1/2=(3.0+/- 1.5)\\sqrt{M/0.3M⊙ } light-days, agrees with previous estimates. In the three events, the core of the magnification profile exhibits “fine structure” related to the innermost region of the accretion disk (located at a radial distance of 2.7 ± 1.4 Schwarzschild radii according to our measurement). Relativistic beaming at the internal rim of the accretion disk can explain the shape and size of the fine structure, although alternative explanations are also possible. This is the first direct measurement of the size of a structure, likely the innermost stable circular orbit, at ˜3 Schwarzschild radii in a quasar accretion disk. The monitoring of thousands of lensed quasars with future telescopes will allow the study of the event horizon environment of black holes in hundreds of quasars in a wide range of redshifts (0.5 < z < 5).

  11. New method to measure proper motions of microlensed sources: Application to candidate free-floating-planet event MOA-2011-BLG-262

    SciTech Connect

    Skowron, Jan; Udalski, Andrzej; Szymański, Michał K. E-mail: udalski@astrouw.edu.pl; and others

    2014-04-20

    We develop a new method to measure source proper motions in microlensing events, which can partially overcome problems due to blending. It takes advantage of the fact that the source position is known precisely from the microlensing event itself. We apply this method to the event MOA-2011-BLG-262, which has a short timescale t {sub E} = 3.8 day, a companion mass ratio q = 4.7 × 10{sup –3}, and a very high or high lens-source relative proper motion μ{sub rel} = 20 mas yr{sup –1} or 12 mas yr{sup –1} (for two possible models). These three characteristics imply that the lens could be a brown dwarf or a massive planet with a roughly Earth-mass 'moon'. The probability of such an interpretation would be greatly increased if it could be shown that the high lens-source relative proper motion was primarily due to the lens rather than the source. Based on the long-term monitoring data of the Galactic bulge from the Optical Gravitational Lensing Experiment, we measure the source proper motion that is small, μ{sub s}=(−2.3,−0.9)±(2.8,2.6) mas yr{sup −1} in a (north, east) Galactic coordinate frame. These values are then important input into a Bayesian analysis of the event presented in a companion paper by Bennett et al.

  12. AN EFFICIENT METHOD FOR MODELING HIGH-MAGNIFICATION PLANETARY MICROLENSING EVENTS

    SciTech Connect

    Bennett, David P.

    2010-06-20

    I present a previously unpublished method for calculating and modeling multiple lens microlensing events that is based on the image centered ray-shooting approach of Bennett and Rhie. It has been used to model a wide variety of binary and triple lens systems, but it is designed to efficiently model high-magnification planetary microlensing events, because these high-magnification events are, by far, the most challenging events to model. It is designed to be efficient enough to handle complicated microlensing events, which include more than two lens masses and lens orbital motion. This method uses a polar coordinate integration grid with a smaller grid spacing in the radial direction than in the angular direction, and it employs an integration scheme specifically designed to handle limb-darkened sources. I present tests that show that these features achieve second-order accuracy for the light curves of a number of high-magnification planetary events. They improve the precision of the calculations by a factor of >100 compared to first-order integration schemes with the same grid spacing in both directions (for a fixed number of grid points). This method also includes a {chi}{sup 2} minimization method, based on the Metropolis algorithm, that allows the jump function to vary in a way that allows quick convergence to {chi}{sup 2} minima. Finally, I introduce a global parameter space search strategy that allows a blind search of parameter space for light curve models without requiring {chi}{sup 2} minimization over a large grid of fixed parameters. Instead, the parameter space is explored on a grid of initial conditions for a set of {chi}{sup 2} minimizations using the full parameter space. While this method may be somewhat faster than methods that find the {chi}{sup 2} minima over a large grid of parameters, I argue that the main strength of this method is for events with the signals of multiple planets, where a much higher dimensional parameter space must be explored

  13. Binary Source Microlensing Event OGLE-2016-BLG-0733: Interpretation of a Long-term Asymmetric Perturbation

    NASA Astrophysics Data System (ADS)

    Jung, Y. K.; Udalski, A.; Yee, J. C.; Sumi, T.; Gould, A.; Han, C.; Albrow, M. D.; Lee, C.-U.; Kim, S.-L.; Chung, S.-J.; Hwang, K.-H.; Ryu, Y.-H.; Shin, I.-G.; Zhu, W.; Cha, S.-M.; Kim, D.-J.; Lee, Y.; Park, B.-G.; Pogge, R. W.; KMTNet Collaboration; Pietrukowicz, P.; Kozłowski, S.; Poleski, R.; Skowron, J.; Mróz, P.; Szymański, M. K.; Soszyński, I.; Pawlak, M.; Ulaczyk, K.; OGLE Collaboration; Abe, F.; Bennett, D. P.; Barry, R.; Bond, I. A.; Asakura, Y.; Bhattacharya, A.; Donachie, M.; Freeman, M.; Fukui, A.; Hirao, Y.; Itow, Y.; Koshimoto, N.; Li, M. C. A.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Nagakane, M.; Oyokawa, H.; Rattenbury, N. J.; Sharan, A.; Sullivan, D. J.; Suzuki, D.; Tristram, P. J.; Yamada, T.; Yamada, T.; Yonehara, A.; MOA Collaboration

    2017-03-01

    In the process of analyzing an observed light curve, one often confronts various scenarios that can mimic the planetary signals causing difficulties in the accurate interpretation of the lens system. In this paper, we present the analysis of the microlensing event OGLE-2016-BLG-0733. The light curve of the event shows a long-term asymmetric perturbation that would appear to be due to a planet. From the detailed modeling of the lensing light curve, however, we find that the perturbation originates from the binarity of the source rather than the lens. This result demonstrates that binary sources with roughly equal-luminosity components can mimic long-term perturbations induced by planets with projected separations near the Einstein ring. The result also represents the importance of the consideration of various interpretations in planet-like perturbations and of high-cadence observations for ensuring the unambiguous detection of the planet.

  14. MiNDSTEp differential photometry of the gravitationally lensed quasars WFI 2033-4723 and HE 0047-1756: microlensing and a new time delay

    NASA Astrophysics Data System (ADS)

    Giannini, E.; Schmidt, R. W.; Wambsganss, J.; Alsubai, K.; Andersen, J. M.; Anguita, T.; Bozza, V.; Bramich, D. M.; Browne, P.; Calchi Novati, S.; Damerdji, Y.; Diehl, C.; Dodds, P.; Dominik, M.; Elyiv, A.; Fang, X.; Figuera Jaimes, R.; Finet, F.; Gerner, T.; Gu, S.; Hardis, S.; Harpsøe, K.; Hinse, T. C.; Hornstrup, A.; Hundertmark, M.; Jessen-Hansen, J.; Jørgensen, U. G.; Juncher, D.; Kains, N.; Kerins, E.; Korhonen, H.; Liebig, C.; Lund, M. N.; Lundkvist, M. S.; Maier, G.; Mancini, L.; Masi, G.; Mathiasen, M.; Penny, M.; Proft, S.; Rabus, M.; Rahvar, S.; Ricci, D.; Scarpetta, G.; Sahu, K.; Schäfer, S.; Schönebeck, F.; Skottfelt, J.; Snodgrass, C.; Southworth, J.; Surdej, J.; Tregloan-Reed, J.; Vilela, C.; Wertz, O.; Zimmer, F.

    2017-01-01

    Aims: We present V and R photometry of the gravitationally lensed quasars WFI 2033-4723 and HE 0047-1756. The data were taken by the MiNDSTEp collaboration with the 1.54 m Danish telescope at the ESO La Silla observatory from 2008 to 2012. Methods: Differential photometry has been carried out using the image subtraction method as implemented in the HOTPAnTS package, additionally using GALFIT for quasar photometry. Results: The quasar WFI 2033-4723 showed brightness variations of order 0.5 mag in V and R during the campaign. The two lensed components of quasar HE 0047-1756 varied by 0.2-0.3 mag within five years. We provide, for the first time, an estimate of the time delay of component B with respect to A of Δt = (7.6 ± 1.8) days for this object. We also find evidence for a secular evolution of the magnitude difference between components A and B in both filters, which we explain as due to a long-duration microlensing event. Finally we find that both quasars WFI 2033-4723 and HE 0047-1756 become bluer when brighter, which is consistent with previous studies. Based on data collected by MiNDSTEp with the Danish 1.54 m telescope at the ESO La Silla observatory.

  15. A PLANETARY LENSING FEATURE IN CAUSTIC-CROSSING HIGH-MAGNIFICATION MICROLENSING EVENTS

    SciTech Connect

    Chung, Sun-Ju; Hwang, Kyu-Ha; Ryu, Yoon-Hyun; Lee, Chung-Uk E-mail: kyuha@kasi.re.kr E-mail: leecu@kasi.re.kr

    2012-05-20

    Current microlensing follow-up observations focus on high-magnification events because of the high efficiency of planet detection. However, central perturbations of high-magnification events caused by a planet can also be produced by a very close or a very wide binary companion, and the two kinds of central perturbations are not generally distinguished without time consuming detailed modeling (a planet-binary degeneracy). Hence, it is important to resolve the planet-binary degeneracy that occurs in high-magnification events. In this paper, we investigate caustic-crossing high-magnification events caused by a planet and a wide binary companion. From this investigation, we find that because of the different magnification excess patterns inside the central caustics induced by the planet and the binary companion, the light curves of the caustic-crossing planetary-lensing events exhibit a feature that is discriminated from those of the caustic-crossing binary-lensing events, and the feature can be used to immediately distinguish between the planetary and binary companions. The planetary-lensing feature appears in the interpeak region between the two peaks of the caustic-crossings. The structure of the interpeak region for the planetary-lensing events is smooth and convex or boxy, whereas the structure for the binary-lensing events is smooth and concave. We also investigate the effect of a finite background source star on the planetary-lensing feature in the caustic-crossing high-magnification events. From this, we find that the convex-shaped interpeak structure appears in a certain range that changes with the mass ratio of the planet to the planet-hosting star.

  16. A New Nonplanetary Interpretation of the Microlensing Event OGLE-2013-BLG-0723

    NASA Astrophysics Data System (ADS)

    Han, Cheongho; Bennett, David P.; Udalski, Andrzej; Jung, Youn Kil

    2016-07-01

    Recently, the discovery of a Venus-mass planet orbiting a brown-dwarf host in a binary system was reported from the analysis of the microlensing event OGLE-2013-BLG-0723. We reanalyze the event considering the possibility of other interpretations. From this, we find a new solution where the lens is composed of two bodies, in contrast to the three-body solution of the previous analysis. The new solution better explains the observed light curve than the previous solution with Δχ 2 ˜ 202, suggesting that the new solution is a correct model for the event. From the estimation of the physical parameters based on the new interpretation, we find that the lens system is composed of two low-mass stars with ˜0.2 M ⊙ and ˜0.1 M ⊙ and located at a distance of ˜3 kpc. The fact that the physical parameters correspond to those of the most common lens population located at a distance with a large lensing probability further supports the likelihood of the new interpretation. Considering that two dramatically different solutions can approximately explain the observed light curve, the event suggests the need for carefully testing all possible lens-system geometries.

  17. Properties of Microlensing Events by Wide-separation Planets with a Moon

    NASA Astrophysics Data System (ADS)

    Chung, Sun-Ju; Ryu, Yoon-Hyun

    2016-07-01

    We investigate the properties of microlensing events caused by planetary systems where planets with a moon are widely separated from their host stars. From this investigation, we find that the moon feature generally appears as a very short-duration perturbation on the smooth asymmetric light curve of the lensing event induced by the wide-separation planet; thus it can be easily discriminated from the planet feature responsible for the overall asymmetric light curve. For typical Galactic lensing events with an Einstein radius of ˜2 au, the asymmetry of the light curves due to bound planets can be noticed up to ˜20 au. We also find that the perturbations of wide planetary systems become dominated by the moon as the projected star-planet separation increases, and eventually the light curves of events produced by such systems appear as the single lensing light curve of the planet itself with a very short-duration perturbation induced by the moon, which is a representative light curve of the event induced by a star and a planet, except on the Einstein timescale of the planet. We also study the effect of a finite source star on the moon feature in wide planetary lensing events. From this study, we find that when the lunar caustic is sufficiently separated from the planetary caustic, the lower limit on the ratio of the size of the lunar caustic to the source radius causing a ≥5% lunar deviation depends mostly on the projected planet-moon separation regardless of the moon/star mass ratio, and it decreases as the planet-moon separation becomes smaller or larger than the planetary Einstein radius.

  18. Observational limits on Omega in stars, brown dwarfs, and stellar remnants from gravitational microlensing

    NASA Technical Reports Server (NTRS)

    Dalcanton, Julianne J.; Canizares, Claude R.; Granados, Arno; Steidel, Charles C.; Stocke, John T.

    1994-01-01

    Microlensing by compact objects with masses between approximately 0.001 solar masses and approximately 300 solar masses will amplify the continuum emission of a quasar, without significantly changing its line emission. Thus, compact objects with masses associated with stars, subdwarfs, and stellar remnants will reduce the apparent equivalent widths of quasar emission lines. It is possible to detect this population of lenses by searching for an increase in the number of small equivalent width quasars with redshift. This increase was looked for, but not found, in quasar samples taken from the Einstein Medium Sensitivity Survey and the Steidel & Sargent absorption-line studies. Thus, Omega(sub c), the cosmological density of compact objects relative to the critical density, is less than or approximately equal to 0.1 in the mass range 0.01 solar masses-20 solar masses (for Omega less than 0.6). For any value of Omega, Omega(sub c) less than or approximately equal to 0.2 in the larger mass range 0.001 solar masses-60 solar masses, and Omega(sub c) less than 1 for 0.001 solar masses-300 solar masses. Subdwarfs, stellar objects, or their remnants (e.g., MACHOS) cannot close the universe.

  19. Statistical searches for microlensing events in large, non-uniformly sampled time-domain surveys: A test using palomar transient factory data

    SciTech Connect

    Price-Whelan, Adrian M.; Agüeros, Marcel A.; Fournier, Amanda P.; Street, Rachel; Ofek, Eran O.; Covey, Kevin R.; Levitan, David; Sesar, Branimir; Laher, Russ R.; Surace, Jason

    2014-01-20

    Many photometric time-domain surveys are driven by specific goals, such as searches for supernovae or transiting exoplanets, which set the cadence with which fields are re-imaged. In the case of the Palomar Transient Factory (PTF), several sub-surveys are conducted in parallel, leading to non-uniform sampling over its ∼20,000 deg{sup 2} footprint. While the median 7.26 deg{sup 2} PTF field has been imaged ∼40 times in the R band, ∼2300 deg{sup 2} have been observed >100 times. We use PTF data to study the trade off between searching for microlensing events in a survey whose footprint is much larger than that of typical microlensing searches, but with far-from-optimal time sampling. To examine the probability that microlensing events can be recovered in these data, we test statistics used on uniformly sampled data to identify variables and transients. We find that the von Neumann ratio performs best for identifying simulated microlensing events in our data. We develop a selection method using this statistic and apply it to data from fields with >10 R-band observations, 1.1 × 10{sup 9} light curves, uncovering three candidate microlensing events. We lack simultaneous, multi-color photometry to confirm these as microlensing events. However, their number is consistent with predictions for the event rate in the PTF footprint over the survey's three years of operations, as estimated from near-field microlensing models. This work can help constrain all-sky event rate predictions and tests microlensing signal recovery in large data sets, which will be useful to future time-domain surveys, such as that planned with the Large Synoptic Survey Telescope.

  20. Confirmation of the Planetary Microlensing Signal and Star and Planet Mass Determinations for Event OGLE-2005-BLG-169

    NASA Astrophysics Data System (ADS)

    Bennett, D. P.; Bhattacharya, A.; Anderson, J.; Bond, I. A.; Anderson, N.; Barry, R.; Batista, V.; Beaulieu, J.-P.; DePoy, D. L.; Dong, Subo; Gaudi, B. S.; Gilbert, E.; Gould, A.; Pfeifle, R.; Pogge, R. W.; Suzuki, D.; Terry, S.; Udalski, A.

    2015-08-01

    We present Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) observations of the source and lens stars for planetary microlensing event OGLE-2005-BLG-169, which confirm the relative proper motion prediction due to the planetary light curve signal observed for this event. This (and the companion Keck result) provide the first confirmation of a planetary microlensing signal, for which the deviation was only 2%. The follow-up observations determine the flux of the planetary host star in multiple passbands and remove light curve model ambiguity caused by sparse sampling of part of the light curve. This leads to a precise determination of the properties of the OGLE-2005-BLG-169Lb planetary system. Combining the constraints from the microlensing light curve with the photometry and astrometry of the HST/WFC3 data, we find star and planet masses of {M}*=0.69+/- 0.02{M}⊙ and {m}{{p}}=14.1+/- 0.9{M}\\oplus . The planetary microlens system is located toward the Galactic bulge at a distance of {D}L=4.1+/- 0.4 kpc and the projected star-planet separation is {a}\\perp =3.5+/- 0.3 AU, corresponding to a semimajor axis of a={4.0}-0.6+2.2 AU.

  1. Discovery of a Gas Giant Planet in Microlensing Event Ogle-2014-BLG-1760

    NASA Technical Reports Server (NTRS)

    Bhattacharya, A.; Bennett, D. P.; Bond, I. A.; Sumi, T.; Udalski, A.; Street, R.; Tsapras, Y.; Abe, F.; Freeman, M.; Fukui, A.

    2016-01-01

    We present the analysis of the planetary microlensing event OGLE-2014-BLG-1760, which shows a strong light-curve signal due to the presence of a Jupiter mass ratio planet. One unusual feature of this event is that the source star is quite blue, with V-I = 1.48 +/- 0.08. This is marginally consistent with a source star in the Galactic bulge, but it could possibly indicate a young source star on the far side of the disk. Assuming a bulge source, we perform a Bayesian analysis assuming a standard Galactic model, and this indicates that the planetary system resides in or near the Galactic bulge at D(sub L) = 6.9 +/- 1.1 kpc. It also indicates a host-star mass of M(sub *) = 0.51(sup + 0.44/sub -0.28) M(sub theta), a planet mass of m(sub p ) = 0.56(sup +0.34/sub -0.26) M(sub J), and a projected star-planet separation of a(perpendicular) = 1.75(sup +0.33/sub -0.34) au. The lens-source relative proper motion is micro(sub rel) = 6.5 +/- 1.1mas per yr. The lens (and stellar host star) is estimated to be very faint compared to the source star, so it is most likely that it can be detected only when the lens and source stars start to separate. Due to the relatively high relative proper motion, the lens and source will be resolved to about approximately 46 mas in 6-8 yr after the peak magnification. So, by 2020-2022, we can hope to detect the lens star with deep, high-resolution images.

  2. Discovery of a Gas Giant Planet in Microlensing Event OGLE-2014-BLG-1760

    NASA Astrophysics Data System (ADS)

    Bhattacharya, A.; Bennett, D. P.; Bond, I. A.; Sumi, T.; Udalski, A.; Street, R.; Tsapras, Y.; Abe, F.; Freeman, M.; Fukui, A.; Hirao, Y.; Itow, Y.; Koshimoto, N.; Li, M. C. A.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Nagakane, M.; Ohnishi, K.; Rattenbury, N.; Saito, T.; Sharan, A.; Sullivan, D. J.; Suzuki, D.; Tristram, P. J.; MOA Collaboration; Skowron, J.; Szymański, M. K.; Soszyński, I.; Poleski, R.; Mróz, P.; Kozlowski, S.; Pietrukowicz, P.; Ulaczyk, K.; Wyrzykowski, L.; OGLE Collaboration; Bachelet, E.; Bramich, D. M.; D'Ago, G.; Dominik, M.; Figuera Jaimes, R.; Horne, K.; Hundertmark, M.; Kains, N.; Menzies, J.; Schmidt, R.; Snodgrass, C.; Steele, I. A.; Wambsganss, J.; ROBONET Collaboration

    2016-11-01

    We present the analysis of the planetary microlensing event OGLE-2014-BLG-1760, which shows a strong light-curve signal due to the presence of a Jupiter mass ratio planet. One unusual feature of this event is that the source star is quite blue, with V-I=1.48+/- 0.08. This is marginally consistent with a source star in the Galactic bulge, but it could possibly indicate a young source star on the far side of the disk. Assuming a bulge source, we perform a Bayesian analysis assuming a standard Galactic model, and this indicates that the planetary system resides in or near the Galactic bulge at {D}L=6.9+/- 1.1 {kpc}. It also indicates a host-star mass of {M}* ={0.51}-0.28+0.44{M}⊙ , a planet mass of {m}{{p}}={0.56}-0.26+0.34{M}J, and a projected star-planet separation of {a}\\perp ={1.75}-0.33+0.34 au. The lens-source relative proper motion is {μ }{rel}=6.5+/- 1.1 mas yr-1. The lens (and stellar host star) is estimated to be very faint compared to the source star, so it is most likely that it can be detected only when the lens and source stars start to separate. Due to the relatively high relative proper motion, the lens and source will be resolved to about ˜46 mas in 6-8 yr after the peak magnification. So, by 2020-2022, we can hope to detect the lens star with deep, high-resolution images.

  3. Free-floating planets from core accretion theory: microlensing predictions

    NASA Astrophysics Data System (ADS)

    Ma, Sizheng; Mao, Shude; Ida, Shigeru; Zhu, Wei; Lin, Douglas N. C.

    2016-09-01

    We calculate the microlensing event rate and typical time-scales for the free-floating planet (FFP) population that is predicted by the core accretion theory of planet formation. The event rate is found to be ˜1.8 × 10-3 of that for the stellar population. While the stellar microlensing event time-scale peaks at around 20 d, the median time-scale for FFP events (˜0.1 d) is much shorter. Our values for the event rate and the median time-scale are significantly smaller than those required to explain the Sumi et al. result, by factors of ˜13 and ˜16, respectively. The inclusion of planets at wide separations does not change the results significantly. This discrepancy may be too significant for standard versions of both the core accretion theory and the gravitational instability model to explain satisfactorily. Therefore, either a modification to the planet formation theory is required or other explanations to the excess of short-time-scale microlensing events are needed. Our predictions can be tested by ongoing microlensing experiment such as Korean Microlensing Telescope Network, and by future satellite missions such as WFIRST and Euclid.

  4. PLANETESIMAL DISK MICROLENSING

    SciTech Connect

    Heng, Kevin; Keeton, Charles R. E-mail: keeton@physics.rutgers.ed

    2009-12-10

    Motivated by debris disk studies, we investigate the gravitational microlensing of background starlight by a planetesimal disk around a foreground star. We use dynamical survival models to construct a plausible example of a planetesimal disk and study its microlensing properties using established ideas of microlensing by small bodies. When a solar-type source star passes behind a planetesimal disk, the microlensing light curve may exhibit short-term, low-amplitude residuals caused by planetesimals several orders of magnitude below Earth mass. The minimum planetesimal mass probed depends on the photometric sensitivity and the size of the source star, and is lower when the planetesimal lens is located closer to us. Planetesimal lenses may be found more nearby than stellar lenses because the steepness of the planetesimal mass distribution changes how the microlensing signal depends on the lens/source distance ratio. Microlensing searches for planetesimals require essentially continuous monitoring programs that are already feasible and can potentially set constraints on models of debris disks, the progeny of the supposed extrasolar analogues of Kuiper Belts.

  5. The First Simultaneous Microlensing Observations by Two Space Telescopes: Spitzer and Swift Reveal a Brown Dwarf in Event OGLE-2015-BLG-1319

    NASA Astrophysics Data System (ADS)

    Shvartzvald, Y.; Li, Z.; Udalski, A.; Gould, A.; Sumi, T.; Street, R. A.; Calchi Novati, S.; Hundertmark, M.; Bozza, V.; Beichman, C.; Bryden, G.; Carey, S.; Drummond, J.; Fausnaugh, M.; Gaudi, B. S.; Henderson, C. B.; Tan, T. G.; Wibking, B.; Pogge, R. W.; Yee, J. C.; Zhu, W.; (Spitzer Team; Tsapras, Y.; Bachelet, E.; Dominik, M.; Bramich, D. M.; Cassan, A.; Figuera Jaimes, R.; Horne, K.; Ranc, C.; Schmidt, R.; Snodgrass, C.; Wambsganss, J.; Steele, I. A.; Menzies, J.; Mao, S.; (RoboNet; Poleski, R.; Pawlak, M.; Szymański, M. K.; Skowron, J.; Mróz, P.; Kozłowski, S.; Wyrzykowski, Ł.; Pietrukowicz, P.; Soszyński, I.; Ulaczyk, K.; (OGLE Group; Abe, F.; Asakura, Y.; Barry, R. K.; Bennett, D. P.; Bhattacharya, A.; Bond, I. A.; Freeman, M.; Hirao, Y.; Itow, Y.; Koshimoto, N.; Li, M. C. A.; Ling, C. H.; Masuda, K.; Fukui, A.; Matsubara, Y.; Muraki, Y.; Nagakane, M.; Nishioka, T.; Ohnishi, K.; Oyokawa, H.; Rattenbury, N. J.; Saito, To.; Sharan, A.; Sullivan, D. J.; Suzuki, D.; Tristram, P. J.; Yonehara, A.; (MOA Group; Jørgensen, U. G.; Burgdorf, M. J.; Ciceri, S.; D'Ago, G.; Evans, D. F.; Hinse, T. C.; Kains, N.; Kerins, E.; Korhonen, H.; Mancini, L.; Popovas, A.; Rabus, M.; Rahvar, S.; Scarpetta, G.; Skottfelt, J.; Southworth, J.; Peixinho, N.; Verma, P.; (MiNDSTEp; Sbarufatti, B.; Kennea, J. A.; Gehrels, N.; (Swift

    2016-11-01

    Simultaneous observations of microlensing events from multiple locations allow for the breaking of degeneracies between the physical properties of the lensing system, specifically by exploring different regions of the lens plane and by directly measuring the “microlens parallax.” We report the discovery of a 30-65M J brown dwarf orbiting a K dwarf in the microlensing event OGLE-2015-BLG-1319. The system is located at a distance of ˜5 kpc toward the Galactic Bulge. The event was observed by several ground-based groups as well as by Spitzer and Swift, allowing a measurement of the physical properties. However, the event is still subject to an eight-fold degeneracy, in particular the well-known close-wide degeneracy, and thus the projected separation between the two lens components is either ˜0.25 au or ˜45 au. This is the first microlensing event observed by Swift, with the UVOT camera. We study the region of microlensing parameter space to which Swift is sensitive, finding that though Swift could not measure the microlens parallax with respect to ground-based observations for this event, it can be important for other events. Specifically, it is important for detecting nearby brown dwarfs and free-floating planets in high magnification events.

  6. Simulation of Gravitational Microlensing

    NASA Video Gallery

    This simulation shows the 22-year journey of a star moving through space and passing directly in front of a more distant background star. All stars drift through space. Occasionally, a star lines u...

  7. Microlensing search towards M 31

    NASA Astrophysics Data System (ADS)

    Calchi Novati, S.; Iovane, G.; Marino, A. A.; Aurière, M.; Baillon, P.; Bouquet, A.; Bozza, V.; Capaccioli, M.; Capozziello, S.; Cardone, V.; Covone, G.; De Paolis, F.; de Ritis, R.; Giraud-Héraud, Y.; Gould, A.; Ingrosso, G.; Jetzer, Ph.; Kaplan, J.; Lambiase, G.; Le Du, Y.; Mancini, L.; Piedipalumbo, E.; Re, V.; Roncadelli, M.; Rubano, C.; Scarpetta, G.; Scudellaro, P.; Sereno, M.; Strafella, F.

    2002-01-01

    We present the first results of the analysis of data collected during the 1998-99 observational campaign at the 1.3 meter McGraw-Hill Telescope, towards the Andromeda galaxy (M 31), aimed to detect gravitational microlensing effects as a probe for the presence of dark matter in our Galaxy and in the M 31 halo. The analysis is performed using the pixel lensing technique, which consists of the study of flux variations of unresolved sources and has been proposed and implemented by the AGAPE collaboration. We carry out a shape analysis by demanding that the detected flux variations be achromatic and compatible with a Paczyński light curve. We apply the Durbin-Watson hypothesis test to the residuals. Furthermore, we consider the background of variables sources. Finally five candidate microlensing events emerge from our selection. Comparing with the predictions of a Monte Carlo simulation, assuming a standard spherical model for the M 31 and Galactic haloes, and typical values for the MACHO mass, we find that our events are only marginally consistent with the distribution of observable parameters predicted by the simulation.

  8. Structure of Quasar Continuum Emission Regions and Cosmology from Optical and X-Ray Microlensing in Gravitationally Lensed Quasars

    DTIC Science & Technology

    2008-05-02

    available. The flux of each component of the multiply-imaged quasars was measured in many seasons of ground-based optical imagery. Lightcurves were...constructed from the flux measurements, and Monte Carlo methods were used to analyze the microlensing variability in the lightcurves . The results of...available. The flux of each component of the multiply-imaged quasars was measured in many seasons of ground-based optical imagery. Lightcurves were

  9. Detections of Planets in Binaries Through the Channel of Chang–Refsdal Gravitational Lensing Events

    NASA Astrophysics Data System (ADS)

    Han, Cheongho; Shin, In-Gu; Jung, Youn Kil

    2017-02-01

    Chang–Refsdal (C–R) lensing, which refers to the gravitational lensing of a point mass perturbed by a constant external shear, provides a good approximation in describing lensing behaviors of either a very wide or a very close binary lens. C–R lensing events, which are identified by short-term anomalies near the peak of high-magnification lensing light curves, are routinely detected from lensing surveys, but not much attention is paid to them. In this paper, we point out that C–R lensing events provide an important channel to detect planets in binaries, both in close and wide binary systems. Detecting planets through the C–R lensing event channel is possible because the planet-induced perturbation occurs in the same region of the C–R lensing-induced anomaly and thus the existence of the planet can be identified by the additional deviation in the central perturbation. By presenting the analysis of the actually observed C–R lensing event OGLE-2015-BLG-1319, we demonstrate that dense and high-precision coverage of a C–R lensing-induced perturbation can provide a strong constraint on the existence of a planet in a wide range of planet parameters. The sample of an increased number of microlensing planets in binary systems will provide important observational constraints in giving shape to the details of planet formation, which have been restricted to the case of single stars to date.

  10. Microlensing for extrasolar planets : improving the photometry

    NASA Astrophysics Data System (ADS)

    Bajek, David J.

    2013-08-01

    Gravitational Microlensing, as a technique for detecting Extrasolar Planets, is recognised for its potential in discovering small-mass planets similar to Earth, at a distance of a few Astronomical Units from their host stars. However, analysing the data from microlensing events (which statistically rarely reveal planets) is complex and requires continued and intensive use of various networks of telescopes working together in order to observe the phenomenon. As such the techniques are constantly being developed and refined; this project outlines some steps of the careful analysis required to model an event and ensure the best quality data is used in the fitting. A quantitative investigation into increasing the quality of the original photometric data available from any microlensing event demonstrates that 'lucky imaging' can lead to a marked improvement in the signal to noise ratio of images over standard imaging techniques, which could result in more accurate models and thus the calculation of more accurate planetary parameters. In addition, a simulation illustrating the effects of atmospheric turbulence on exposures was created, and expanded upon to give an approximation of the lucky imaging technique. This further demonstrated the advantages of lucky images which are shown to potentially approach the quality of those expected from diffraction limited photometry. The simulation may be further developed for potential future use as a 'theoretical lucky imager' in our research group, capable of producing and analysing synthetic exposures through customisable conditions.

  11. The Manchester Microlensing Conference: The 12th International Conference and ANGLES Microlensing Workshop

    NASA Astrophysics Data System (ADS)

    Kerins, E.; Mao, S.; Rattenbury, N.; Wyrzykowski, L.

    The Manchester Microlensing Conference (M2C) was held at the Jodrell Bank Centre for Astrophysics at Manchester University in the UK from 21st-25th January 2008. M2C comprised two elements: the ANGLES Microlensing Workshop and the 12th International Conference on gravitational microlensing. M2C began with the two-day Workshop, providing interactive Master Classes to around 60 researchers on selected hot topics in microlensing. The Master Classes were delivered by world-leading experts on each of the topics. The topics reflected the diverse techniques and applications of microlensing, such as crowded-field photometry, modelling of extra-solar planetary systems, and the use of microlensing in cosmology. The 12th International Conference on microlensing followed immediately after the Workshop and was attended by around 90 researchers. The Conference covered all aspects of current research in microlensing, including: Microlensing towards the Magellanic Clouds; Cosmological Microlensing; Stellar and Galactic Microlensing; Galactic Microlensing Surveys; Follow-up Programmes and Planetary Microlensing; M31 Microlensing; and Future Directions. The M2C Proceedings serve three functions. Through the expert master classes the M2C Proceedings provide a great starting point for those who wish to enter the field or who just wish to learn more about microlensing at a depth beyond that usually covered by a single review article. The M2C proceedings also provide a snapshot of the state-of-the art in microlensing observations and theory as of January 2008, in what is a rapidly developing field. Lastly, the M2C meeting and its Proceedings are dedicated to the memory of the late Bohdan Paczynski, a towering figure and founding father of modern day microlensing research.

  12. The Optical Gravitational Lensing Experiment

    NASA Technical Reports Server (NTRS)

    Udalski, A.; Szymanski, M.; Kaluzny, J.; Kubiak, M.; Mateo, Mario

    1992-01-01

    The technical features are described of the Optical Gravitational Lensing Experiment, which aims to detect a statistically significant number of microlensing events toward the Galactic bulge. Clusters of galaxies observed during the 1992 season are listed and discussed and the reduction methods are described. Future plans are addressed.

  13. Detection of planets in extremely weak central perturbation microlensing events via next-generation ground-based surveys

    SciTech Connect

    Chung, Sun-Ju; Lee, Chung-Uk; Koo, Jae-Rim E-mail: leecu@kasi.re.kr

    2014-04-20

    Even though the recently discovered high-magnification event MOA-2010-BLG-311 had complete coverage over its peak, confident planet detection did not happen due to extremely weak central perturbations (EWCPs, fractional deviations of ≲ 2%). For confident detection of planets in EWCP events, it is necessary to have both high cadence monitoring and high photometric accuracy better than those of current follow-up observation systems. The next-generation ground-based observation project, Korea Microlensing Telescope Network (KMTNet), satisfies these conditions. We estimate the probability of occurrence of EWCP events with fractional deviations of ≤2% in high-magnification events and the efficiency of detecting planets in the EWCP events using the KMTNet. From this study, we find that the EWCP events occur with a frequency of >50% in the case of ≲ 100 M {sub E} planets with separations of 0.2 AU ≲ d ≲ 20 AU. We find that for main-sequence and sub-giant source stars, ≳ 1 M {sub E} planets in EWCP events with deviations ≤2% can be detected with frequency >50% in a certain range that changes with the planet mass. However, it is difficult to detect planets in EWCP events of bright stars like giant stars because it is easy for KMTNet to be saturated around the peak of the events because of its constant exposure time. EWCP events are caused by close, intermediate, and wide planetary systems with low-mass planets and close and wide planetary systems with massive planets. Therefore, we expect that a much greater variety of planetary systems than those already detected, which are mostly intermediate planetary systems, regardless of the planet mass, will be significantly detected in the near future.

  14. Microlensing Parallax for Observers in Heliocentric Motion

    NASA Astrophysics Data System (ADS)

    Calchi Novati, S.; Scarpetta, G.

    2016-06-01

    Motivated by the ongoing Spitzer observational campaign, and the forthcoming K2 one, we revisit, working in an heliocentric reference frame, the geometrical foundation for the analysis of the microlensing parallax, as measured with the simultaneous observation of the same microlensing event from two observers with relative distance of order au. For the case of observers at rest, we discuss the well-known fourfold microlensing parallax degeneracy and determine an equation for the degenerate directions of the lens trajectory. For the case of observers in motion, we write down an extension of the Gould relationship between the microlensing parallax and the observable quantities and, at the same time, highlight the functional dependence of these same quantities from the timescale of the underlying microlensing event. Furthermore, through a series of examples, we show the importance of taking into account themotion of the observers to correctly recover the parameters of the underlying microlensing event. In particular, we discuss the cases of the amplitude of the microlensing parallax and that of the difference of the timescales between the observed microlensing events, which are key to understand the breaking of the microlensing parallax degeneracy. Finally, we consider the case of the simultaneous observation of the same microlensing event from the ground and two satellites, a case relevant for the expected joint K2 and Spitzer observational programs in 2016.

  15. A super-jupiter orbiting a late-type star: A refined analysis of microlensing event OGLE-2012-BLG-0406

    SciTech Connect

    Tsapras, Y.; Street, R. A.; Choi, J.-Y.; Han, C.; Bozza, V.; Gould, A.; Dominik, M.; Browne, P.; Horne, K.; Hundertmark, M.; Beaulieu, J.-P.; Udalski, A.; Jørgensen, U. G.; Sumi, T.; Bramich, D. M.; Kains, N.; Ipatov, S.; Alsubai, K. A.; Snodgrass, C.; Steele, I. A.; Collaboration: RoboNet Collaboration; MiNDSTEp Collaboration; OGLE Collaboration; PLANET Collaboration; μFUN Collaboration; MOA Collaboration; and others

    2014-02-10

    We present a detailed analysis of survey and follow-up observations of microlensing event OGLE-2012-BLG-0406 based on data obtained from 10 different observatories. Intensive coverage of the light curve, especially the perturbation part, allowed us to accurately measure the parallax effect and lens orbital motion. Combining our measurement of the lens parallax with the angular Einstein radius determined from finite-source effects, we estimate the physical parameters of the lens system. We find that the event was caused by a 2.73 ± 0.43 M {sub J} planet orbiting a 0.44 ± 0.07 M {sub ☉} early M-type star. The distance to the lens is 4.97 ± 0.29 kpc and the projected separation between the host star and its planet at the time of the event is 3.45 ± 0.26 AU. We find that the additional coverage provided by follow-up observations, especially during the planetary perturbation, leads to a more accurate determination of the physical parameters of the lens.

  16. New limits on primordial black hole dark matter from an analysis of Kepler source microlensing data.

    PubMed

    Griest, Kim; Cieplak, Agnieszka M; Lehner, Matthew J

    2013-11-01

    We present new limits on the allowed masses of a dark matter (DM) halo consisting of primordial black holes (PBH) (or any other massive compact halo object). We analyze two years of data from the Kepler satellite, searching for short-duration bumps caused by gravitational microlensing. After removing background events consisting of variable stars, flare events, and comets or asteroids moving through the Kepler field, we find no microlensing candidates. We measure the efficiency of our selection criteria by adding millions of simulated microlensing lensing events into the Kepler light curves. We find that PBH DM with masses in the range 2 × 10(-9) M[Symbol: see text] to 10(-7)M[Symbol: see text] cannot make up the entirety of the DM in the Milky Way. At the low-mass end, this decreases the allowed mass range by more than an order of magnititude.

  17. Microlensing of Kepler stars as a method of detecting primordial black hole dark matter.

    PubMed

    Griest, Kim; Lehner, Matthew J; Cieplak, Agnieszka M; Jain, Bhuvnesh

    2011-12-02

    If the dark matter consists of primordial black holes (PBHs), we show that gravitational lensing of stars being monitored by NASA's Kepler search for extrasolar planets can cause significant numbers of detectable microlensing events. A search through the roughly 150,000 light curves would result in large numbers of detectable events for PBHs in the mass range 5×10(-10) M(⊙) to 10(-4) M(⊙). Nondetection of these events would close almost 2 orders of magnitude of the mass window for PBH dark matter. The microlensing rate is higher than previously noticed due to a combination of the exceptional photometric precision of the Kepler mission and the increase in cross section due to the large angular sizes of the relatively nearby Kepler field stars. We also present a new formalism for calculating optical depth and microlensing rates in the presence of large finite-source effects.

  18. OGLE-2016-BLG-0596Lb: A High-mass Planet from a High-magnification Pure-survey Microlensing Event

    NASA Astrophysics Data System (ADS)

    Mróz, P.; Han, C.; and; Udalski, A.; Poleski, R.; Skowron, J.; Szymański, M. K.; Soszyński, I.; Pietrukowicz, P.; Kozłowski, S.; Ulaczyk, K.; Wyrzykowski, Ł.; Pawlak, M.; OGLE group; Albrow, M. D.; Cha, S.-M.; Chung, S.-J.; Jung, Y. K.; Kim, D.-J.; Kim, S.-L.; Lee, C.-U.; Lee, Y.; Park, B.-G.; Pogge, R. W.; Ryu, Y.-H.; Shin, I.-G.; Yee, J. C.; Zhu, W.; Gould, A.; (KMTNet group

    2017-04-01

    We report the discovery of a high mass ratio planet, q = 0.012, i.e., 13 times higher than the Jupiter/Sun ratio. The host mass has not yet been measured but can be determined or strongly constrained from adaptive optics imaging. The planet was discovered in a small archival study of high-magnification events in pure-survey microlensing data, which was unbiased by the presence of anomalies. The fact that it was previously unnoticed may indicate that more such planets lie in archival data and could be discovered by a similar systematic study. In order to understand the transition from predominantly survey+followup to predominately survey-only planet detections, we conduct the first analysis of these detections in the observational (s, q) plane. Here s is the projected separation in units of the Einstein radius. We find some evidence that survey+followup is relatively more sensitive to planets near the Einstein ring, but that there is no statistical difference in sensitivity by mass ratio.

  19. Rapid Radio Followups of LIGO Gravitational Wave Events

    NASA Astrophysics Data System (ADS)

    Jenet, Rick; Stevens, Jamie; Wieringa, Mark; Creighton, Teviet

    2010-10-01

    We propose real time follow-up observations with the ATCA to search for radio counterparts to candidate gravitational-wave events detected by the LIGO and Virgo detectors. Electromagnetic and gravitational radiation provide complementary views of the Universe: the former being generated by the microphysical processes of charged particles, the latter by coherent bulk motion of masses. A complete picture of the most violent events in nature, such as supernovae and mergers of stellar remnants, will require both types of observation: Gravitational waves (GWs) to uncover the mechanics of the underlying (gravitational) energy source, and electromagnetic waves to reveal how that energy is then dissipated in matter. The search for GWs is entering an exciting phase with kilometer-scale interferometric detectors LIGO and Virgo achieving sensitivities for which detection of GWs is plausible. Since the sensitivity of these instruments improves incrementally, it is likely that the first verifiable detections of GWs will have signal-to-noise ratios that are just barely statistically significant. Observations in the electromagnetic spectrum will help confirm the first GW detections.

  20. The Arithmetic of events and a new theory of Gravitation

    NASA Astrophysics Data System (ADS)

    Abbasi, Malek

    2012-04-01

    Of fundamental importance in physics is the concept of event. This study tries; first, to provide a mathematical background showing how must deal with these events and based on what laws the watches, another important concept used frequently in this research, record them. Armed, then, with this mathematical background, the Gravitational Clouds Theory, a novel theory of gravitation concerning the role of the matter and energy in the universe, is proposed. This completely new theory leads to miscellanies results some of which are: the second Einstein's postulate; the well known identity E = mc2; the time-dilation phenomenon and Fitzgerald-Lorentz contraction. This theory will also explain why indeed we never feel the speed of the Earth, what is the origin of Dark matter-energy and many other extraordinary results associated with cosmology.

  1. The Arithmetic of Events and a New Theory of Gravitation

    NASA Astrophysics Data System (ADS)

    Abbasi, Malek

    2012-10-01

    Of fundamental importance in physics is the concept of event. This study tries, first, to provide a mathematical background showing how must deal with these events and based on what laws the watches, another important concept used frequently in this research, record them. Armed, then, with this mathematical background, the Gravitational Clouds Theory, a novel theory of gravitation concerning the role of the matter and energy in the universe, is proposed. This completely new theory leads to miscellanies results some of which are: the second Einstein's postulate; the well known identity E = mc2; the time-dilation phenomenon and Fitzgerald-Lorentz contraction. This theory will also explain why indeed we never feel the speed of the Earth, what is the origin of Dark matter-energy and many other extraordinary results associated with cosmology.

  2. Revisiting the Microlensing Event OGLE 2012-BLG-0026: A Solar Mass Star with Two Cold Giant Planets

    NASA Technical Reports Server (NTRS)

    Beaulieu, J.-P.; Bennett, D. P.; Batista, V.; Fukui, A.; Marquette, J.-B.; Brillant, S.; Cole, A. A.; Rogers, L. A.; Sumi, T.; Abe, F.

    2016-01-01

    Two cold gas giant planets orbiting a G-type main-sequence star in the galactic disk were previously discovered in the high-magnification microlensing event OGLE-2012-BLG-0026. Here, we present revised host star flux measurements and a refined model for the two-planet system using additional light curve data. We performed high angular resolution adaptive optics imaging with the Keck and Subaru telescopes at two epochs while the source star was still amplified. We detected the lens flux, H = 16.39 +/- 0.08. The lens, a disk star, is brighter than predicted from the modeling in the original study. We revisited the light curve modeling using additional photometric data from the B and C telescope in New Zealand and CTIO 1.3 m H-band light curve. We then include the Keck and Subaru adaptive optic observation constraints. The system is composed of an approximately 4-9 Gyr lens star of M(sub lens) = 1.06 +/- 0.05 solar mass at a distance of D(sub lens) = 4.0 +/- 0.3 kpc, orbited by two giant planets of 0.145 +/- 0.008 M(sub Jup) and 0.86 +/- 0.06 M(sub Jup), with projected separations of 4.0 +/- 0.5 au and 4.8 +/- 0.7 au, respectively. Because the lens is brighter than the source star by 16 +/- 8% in H, with no other blend within one arcsec, it will be possible to estimate its metallicity using subsequent IR spectroscopy with 8-10 m class telescopes. By adding a constraint on the metallicity it will be possible to refine the age of the system.

  3. Revisiting the Microlensing Event OGLE 2012-BLG-0026: A Solar Mass Star with Two Cold Giant Planets

    NASA Astrophysics Data System (ADS)

    Beaulieu, J.-P.; Bennett, D. P.; Batista, V.; Fukui, A.; Marquette, J.-B.; Brillant, S.; Cole, A. A.; Rogers, L. A.; Sumi, T.; Abe, F.; Bhattacharya, A.; Koshimoto, N.; Suzuki, D.; Tristram, P. J.; Han, C.; Gould, A.; Pogge, R.; Yee, J.

    2016-06-01

    Two cold gas giant planets orbiting a G-type main-sequence star in the galactic disk were previously discovered in the high-magnification microlensing event OGLE-2012-BLG-0026. Here, we present revised host star flux measurements and a refined model for the two-planet system using additional light curve data. We performed high angular resolution adaptive optics imaging with the Keck and Subaru telescopes at two epochs while the source star was still amplified. We detected the lens flux, H = 16.39 ± 0.08. The lens, a disk star, is brighter than predicted from the modeling in the original study. We revisited the light curve modeling using additional photometric data from the B&C telescope in New Zealand and CTIO 1.3 m H-band light curve. We then include the Keck and Subaru adaptive optic observation constraints. The system is composed of a ˜4-9 Gyr lens star of M lens = 1.06 ± 0.05 M ⊙ at a distance of D lens = 4.0 ± 0.3 kpc, orbited by two giant planets of 0.145 ± 0.008 M Jup and 0.86 ± 0.06 M Jup, with projected separations of 4.0 ± 0.5 au and 4.8 ± 0.7 au, respectively. Because the lens is brighter than the source star by 16 ± 8% in H, with no other blend within one arcsec, it will be possible to estimate its metallicity using subsequent IR spectroscopy with 8-10 m class telescopes. By adding a constraint on the metallicity it will be possible to refine the age of the system.

  4. Probing the Broad-Line Region and the Accretion Disk in the Lensed Quasars HE 0435-1223, WFI 2033-4723, and HE 2149-2745 Using Gravitational Microlensing

    NASA Astrophysics Data System (ADS)

    Motta, V.; Mediavilla, E.; Rojas, K.; Falco, E. E.; Jiménez-Vicente, J.; Muñoz, J. A.

    2017-02-01

    We use single-epoch spectroscopy of three gravitationally lensed quasars, HE 0435-1223, WFI 2033-4723, and HE 2149-2745, to study their inner structure (broad-line region [BLR] and continuum source). We detect microlensing-induced magnification in the wings of the broad emission lines of two of the systems (HE 0435-1223 and WFI 2033-4723). In the case of WFI 2033-4723, microlensing affects two “bumps” in the spectra that are almost symmetrically arranged on the blue (coincident with an Al iii emission line) and red wings of C iii]. These match the typical double-peaked profile that follows from disk kinematics. The presence of microlensing in the wings of the emission lines indicates the existence of two different regions in the BLR: a relatively small one with kinematics possibly related to an accretion disk, and another one that is substantially more extended and insensitive to microlensing. There is good agreement between the estimated size of the region affected by microlensing in the emission lines, {r}s={10}-7+15\\sqrt{M/{M}ȯ } lt-day (red wing of C iv in HE 0435-1223) and {r}s={11}-7+28\\sqrt{M/{M}ȯ } lt-day (C iii] bumps in WFI 2033-4723), and the sizes inferred from the continuum emission, {r}s={13}-4+5\\sqrt{M/{M}ȯ } lt-day (HE 0435-1223) and {r}s={10}-2+3\\sqrt{M/{M}ȯ } lt-day (WFI 2033-4723). For HE 2149-2745 we measure an accretion disk size {r}s={8}-5+11\\sqrt{M/{M}ȯ } lt-day. The estimates of p, the exponent of the size versus wavelength ({r}s\\propto {λ }p), are 1.2 ± 0.6, 0.8 ± 0.2, and 0.4 ± 0.3 for HE 0435-1223, WFI 2033-4723, and HE 2149-2745, respectively. In conclusion, the continuum microlensing amplitude in the three quasars and chromaticity in WFI 2033-4723 and HE 2149-2745 are below expectations for the thin-disk model. The disks are larger and their temperature gradients are flatter than predicted by this model.

  5. Faint detection of exoplanets in microlensing surveys

    SciTech Connect

    Brown, Robert A.

    2014-06-20

    We propose a new approach to discovering faint microlensing signals below traditional thresholds, and for estimating the binary-lens mass ratio and the apparent separation from such signals. The events found will be helpful in accurately estimating the true distribution of planetary semimajor axes, which is an important goal of space microlensing surveys.

  6. Faint-source-star planetary microlensing: the discovery of the cold gas-giant planet OGLE-2014-BLG-0676Lb

    NASA Astrophysics Data System (ADS)

    Rattenbury, N. J.; Bennett, D. P.; Sumi, T.; Koshimoto, N.; Bond, I. A.; Udalski, A.; Shvartzvald, Y.; Maoz, D.; Jørgensen, U. G.; Dominik, M.; Street, R. A.; Tsapras, Y.; Abe, F.; Asakura, Y.; Barry, R.; Bhattacharya, A.; Donachie, M.; Evans, P.; Freeman, M.; Fukui, A.; Hirao, Y.; Itow, Y.; Li, M. C. A.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Nagakane, M.; Ohnishi, K.; Oyokawa, H.; Saito, To.; Sharan, A.; Sullivan, D. J.; Suzuki, D.; Tristram, P. J.; Yonehara, A.; Poleski, R.; Skowron, J.; Mróz, P.; Szymański, M. K.; Soszyński, I.; Pietrukowicz, P.; Kozłowski, S.; Ulaczyk, K.; Wyrzykowski, Ł.; Friedmann, M.; Kaspi, S.; Alsubai, K.; Browne, P.; Andersen, J. M.; Bozza, V.; Calchi Novati, S.; Damerdji, Y.; Diehl, C.; Dreizler, S.; Elyiv, A.; Giannini, E.; Hardis, S.; Harpsøe, K.; Hinse, T. C.; Liebig, C.; Hundertmark, M.; Juncher, D.; Kains, N.; Kerins, E.; Korhonen, H.; Mancini, L.; Martin, R.; Mathiasen, M.; Rabus, M.; Rahvar, S.; Scarpetta, G.; Skottfelt, J.; Snodgrass, C.; Surdej, J.; Taylor, J.; Tregloan-Reed, J.; Vilela, C.; Wambsganss, J.; Williams, A.; D'Ago, G.; Bachelet, E.; Bramich, D. M.; Figuera Jaimes, R.; Horne, K.; Menzies, J.; Schmidt, R.; Steele, I. A.

    2017-04-01

    We report the discovery of a planet - OGLE-2014-BLG-0676Lb- via gravitational microlensing. Observations for the lensing event were made by the following groups: Microlensing Observations in Astrophysics; Optical Gravitational Lensing Experiment; Wise Observatory; RoboNET/Las Cumbres Observatory Global Telescope; Microlensing Network for the Detection of Small Terrestrial Exoplanets; and μ-FUN. All analyses of the light-curve data favour a lens system comprising a planetary mass orbiting a host star. The most-favoured binary lens model has a mass ratio between the two lens masses of (4.78 ± 0.13) × 10-3. Subject to some important assumptions, a Bayesian probability density analysis suggests the lens system comprises a 3.09_{-1.12}^{+1.02} MJ planet orbiting a 0.62_{-0.22}^{+0.20} M⊙ host star at a deprojected orbital separation of 4.40_{-1.46}^{+2.16} au. The distance to the lens system is 2.22_{-0.83}^{+0.96} kpc. Planet OGLE-2014-BLG-0676Lb provides additional data to the growing number of cool planets discovered using gravitational microlensing against which planetary formation theories may be tested. Most of the light in the baseline of this event is expected to come from the lens and thus high-resolution imaging observations could confirm our planetary model interpretation.

  7. The Korean Microlensing Telescope Network: Expectations for a Cold Exoplanet Census through a Global Microlensing Survey

    NASA Astrophysics Data System (ADS)

    Henderson, Calen Barnett

    The Korean Microlensing Telescope Network (KMTNet) consists of three 1.6m telescopes each with a 4 deg2 field of view (FoV) and is dedicated to monitoring the Galactic bulge to detect exoplanets via gravitational microlensing. KMTNet's combination of aperture size, FoV, cadence, and longitudinal coverage will provide a unique opportunity to probe exoplanet demographics in an unbiased way. My dissertation focuses on the results of simulations I have written and analyses I have performed that together provide estimates of and facilitate intuition about the number and variety of systmes KMTNet will detect and how best to maximize their scientific yield. First I present my simulations that optimize the observing strategy for, and predict the planetary yields of, KMTNet. I estimate the planet detection rates for planets with mass and separation across the ranges 0.1 ≤Mp/M⊕ ≤1000 and 0.4 ≤ a/AU ≤ 16, respectively, and also for free-floating planets. I furthermore investigate the dependence of these detection rates on the number of observatories, the photometric precision limit, and optimistic assumptions regarding seeing, throughput, and flux measurement uncertainties. Next I explore several possible avenues for constraining the flux of the lens for these predicted KMTNet detections. I examine the potential to obtain lens flux measurements by 1) imaging the lens once it is spatially resolved from the source, 2) measuring the elongation of the point spread function of the microlensing target (lens+source) when the lens and source are still unresolved, and 3) taking prompt follow-up photometry. In each case I simulate observing programs for a representative example of current ground-based adaptive optics (AO) facilities, future ground-based AO facilities, and future space telescopes. Lastly, I provide a list of microlensing events toward the Galactic bulge with high relative lens-source proper motion that are therefore good candidates for constraining the lens

  8. Polarimetry Microlensing of Close-in Planetary Systems

    NASA Astrophysics Data System (ADS)

    Sajadian, Sedighe; Hundertmark, Markus

    2017-04-01

    A close-in giant planetary (CGP) system has a net polarization signal whose value varies depending on the orbital phase of the planet. This polarization signal is either caused by the stellar occultation or by reflected starlight from the surface of the orbiting planet. When the CGP system is located in the Galactic bulge, its polarization signal becomes too weak to be measured directly. One method for detecting and characterizing these weak polarization signatures due to distant CGP systems is gravitational microlensing. In this work, we focus on potential polarimetric observations of highly magnified microlensing events of CGP systems. When the lens is passing directly in front of the source star with its planetary companion, the polarimetric signature caused by the transiting planet is magnified. As a result, some distinct features in the polarimetry and light curves are produced. In the same way, microlensing amplifies the reflection-induced polarization signal. While the planet-induced perturbations are magnified whenever these polarimetric or photometric deviations vanish for a moment, the corresponding magnification factor of the polarization component(s) is related to the planet itself. Finding these exact times in the planet-induced perturbations helps us to characterize the planet. In order to evaluate the observability of such systems through polarimetric or photometric observations of high-magnification microlensing events, we simulate these events by considering confirmed CGP systems as their source stars and conclude that the efficiency for detecting the planet-induced signal with the state-of-the-art polarimetric instrument (FORS2/VLT) is less than 0.1%. Consequently, these planet-induced polarimetry perturbations can likely be detected under favorable conditions by the high-resolution and short-cadence polarimeters of the next generation.

  9. The Next Generation Microlensing Search: SuperMacho

    SciTech Connect

    Drake, A; Cook, K; Hiriart, R; Keller, S; Miknaitis, G; Nilolaev, S; Olsen, K; Prochter, G; Rest, A; Schmidt, B; Smith, C; Stubbs, C; Suntzeff, N; Welch, D; Becker, A; Clocchiati, A; Covarrubias, R

    2003-10-27

    Past microlensing experiments such as the MACHO project have discovered the presence of a larger than expected number of microlensing events toward the Large Magellanic Cloud (LMC). These events could represent a large fraction of the dark matter in the halo of our Galaxy, if they are indeed due to halo lenses. However the locations of most of the lenses are poorly defined. The SuperMacho project will detect and follow up {approx}60 microlensing events exhibiting special properties due to binarity, etc., will allow us to better determine the location and nature of the lenses causing the LMC microlensing events.

  10. Gravitational black hole hair from event horizon supertranslations

    NASA Astrophysics Data System (ADS)

    Averin, Artem; Dvali, Gia; Gomez, Cesar; Lüst, Dieter

    2016-06-01

    We discuss BMS supertranslations both at null-infinity BMS- and on the horizon {BMS}^{mathscr{H}} for the case of the Schwarzschild black hole. We show that both kinds of supertranslations lead to infinetly many gapless physical excitations. On this basis we construct a quotient algebra mathcal{A}equiv {BMS}^{mathscr{H}}/{BMS}- using suited superpositions of both kinds of transformations which cannot be compensated by an ordinary BMS-supertranslation and therefore are intrinsically due to the presence of an event horizon. We show that transformations in mathcal{A} are physical and generate gapless excitations on the horizon that can account for the gravitational hair as well as for the black hole entropy. We identify the physics of these modes as associated with Bogolioubov-Goldstone modes due to quantum criticality. Classically the number of these gapless modes is infinite. However, we show that due to quantum criticality the actual amount of information-carriers becomes finite and consistent with Bekenstein entropy. Although we only consider the case of Schwarzschild geometry, the arguments are extendable to arbitrary space-times containing event horizons.

  11. Extracting Binary Orbital Periods Using Timing Analysis of Microlensing Lightcurves

    NASA Astrophysics Data System (ADS)

    Guo, Xinyi; Esin, A.; Di Stefano, R.

    2012-01-01

    Gravitational microlensing events provide unique opportunities to discover and study binaries. A large number of binary lenses have already been found by the microlensing surveys. For the majority of these systems, the binary orbital period is much longer than the duration of the lensing event, so orbital motion can be safely ignored. However, a few lenses have already been discovered that show strong evidence of orbital motion on the timescale of the lensing event. We expect that more such systems will be seen in the future. For binaries whose orbital period is comparable to the event duration, the orbital motion can cause the lensing signal to deviate drastically from that of a static binary lens. The most striking property of such lightcurves is the presence of quasi-periodic features, produced as the source traverses the same regions in the rotating lens plane. Those repeated features contain information about the orbital period of the lens. If this period can be extracted, we immediately learn a lot about the lensing system even without performing the detailed lightcurve modeling. However, the relative transverse motion between the source and the lens significantly complicates the problem of period extraction. To resolve this difficulty, we present a modification to the standard Lomb-Scargle periodogram analysis. We test our method for 6 representative binary lens systems and demonstrate its efficiency in correctly extracting binary orbital periods.

  12. Microlensing detection of extrasolar planets.

    PubMed

    Giannini, Emanuela; Lunine, Jonathan I

    2013-05-01

    We review the method of exoplanetary microlensing with a focus on two-body planetary lensing systems. The physical properties of planetary systems can be successfully measured by means of a deep analysis of lightcurves and high-resolution imaging of planetary systems, countering the concern that microlensing cannot determine planetary masses and orbital radii. Ground-based observers have had success in diagnosing properties of multi-planet systems from a few events, but space-based observations will be much more powerful and statistically more complete. Since microlensing is most sensitive to exoplanets beyond the snow line, whose statistics, in turn, allow for testing current planetary formation and evolution theories, we investigate the retrieval of semi-major axis density by a microlensing space-based survey with realistic parameters. Making use of a published statistical method for projected exoplanets quantities (Brown 2011), we find that one year of such a survey might distinguish between simple power-law semi-major axis densities. We conclude by briefly reviewing ground-based results hinting at a high abundance of free-floating planets and describing the potential contribution of space-based missions to understanding the frequency and mass distribution of these intriguing objects, which could help unveil the formation processes of planetary systems.

  13. VizieR Online Data Catalog: Microlensing optical depth & event rates from MOA-II (Sumi+, 2016)

    NASA Astrophysics Data System (ADS)

    Sumi, T.; Penny, M. T.

    2016-11-01

    We use the same data set as Sumi+ (2013, J/ApJ/778/150), which used the data taken in the 2006 and 2007 seasons by the MOA-II survey, with the 1.8m MOA-II telescope located at the Mt. John University Observatory, New Zealand. The centers of the 22 Galactic bulge (GB) fields of the MOA-II survey are listed in Table 1. The images were taken using the custom MOA-Red wide-band filter, which is equivalent to the sum of the standard Kron/Cousins R and I bands. Each field is divided into 80 subfields and each subfield is individually calibrated using the red clump giant (RCG) feature in each subfield CMD more precisely. The number of subfields used in the final analysis is 1536 in total and also given in Table 1 for each field. The coordinates and other properties of the subfields are listed in Table 4. The OGLE (Udalski 2003AcA....53..291U) also conducts a microlensing survey toward the GB with the 1.3m Warsaw telescope at the Las Campanas Observatory in Chile. The median seeing is about 1.3 arcsec. Most observations are taken in the standard Kron-Cousin I band with occasional observations in the Johnson V band. (1 data file).

  14. Progresses of Search for Gravitational Wave Events Using TAMA300 Data

    NASA Astrophysics Data System (ADS)

    Kanda, N.; Ando, M.; Nakano, H.; Soida, K.; Tagoshi, H.; Takahashi, H.; Tatsumi, D.; Tsunesada, Y.; TAMA Collaboration

    2003-07-01

    We implemented and evaluated the Gravitational wave event search in TAMA 300 data analysis. Our searches are for the inspiral gravitational wave from coalescing compact binary, Black Hole (BH) quasi-normal ringing, supernova bursts, and continuous wave from SN1987a remnant. Using TAMA's over 2000 hours of observation data, we have progresses of the searches and improved the upper limits.

  15. Finding Free-Floating Black Holes using Astrometric Microlensing

    NASA Astrophysics Data System (ADS)

    Lu, Jessica R.; Ofek, Eran Oded; Sinukoff, Evan; Udalski, Andrzej; Kozlowski, Szymon

    2017-01-01

    Our Galaxy most likely hosts 10-100 million stellar mass black holes. The exact number and mass function of these black holes contains important information regarding our Galaxy's star formation history, stellar mass function, and the fate of very massive stars. However, isolated stellar black holes have yet to be detected. To date, stellar mass black holes have only been definitively detected in binary systems with accreting companions or merging to produce gravitational waves. In principle, the presence of isolated black holes can be inferred from astrometric and photometric signatures produced when they lens light from a background star. We attempt to detect the astrometric lensing signatures of several photometrically identified microlensing events, toward the Galactic Bulge. Long-duration events (t_Einstein > 100 days) were selected as the most likely black hole candidates and were observed using several years of laser-guided adaptive optics observations from the W. M. Keck telescopes. We present results from this search.

  16. Stellar Rotation Effects in Polarimetric Microlensing

    NASA Astrophysics Data System (ADS)

    Sajadian, Sedighe

    2016-07-01

    It is well known that the polarization signal in microlensing events of hot stars is larger than that of main-sequence stars. Most hot stars rotate rapidly around their stellar axes. The stellar rotation creates ellipticity and gravity-darkening effects that break the spherical symmetry of the source's shape and the circular symmetry of the source's surface brightness respectively. Hence, it causes a net polarization signal for the source star. This polarization signal should be considered in polarimetric microlensing of fast rotating stars. For moderately rotating stars, lensing can magnify or even characterize small polarization signals due to the stellar rotation through polarimetric observations. The gravity-darkening effect due to a rotating source star creates asymmetric perturbations in polarimetric and photometric microlensing curves whose maximum occurs when the lens trajectory crosses the projected position of the rotation pole on the sky plane. The stellar ellipticity creates a time shift (i) in the position of the second peak of the polarimetric curves in transit microlensing events and (ii) in the peak position of the polarimetric curves with respect to the photometric peak position in bypass microlensing events. By measuring this time shift via polarimetric observations of microlensing events, we can evaluate the ellipticity of the projected source surface on the sky plane. Given the characterizations of the FOcal Reducer and low dispersion Spectrograph (FORS2) polarimeter at the Very Large Telescope, the probability of observing this time shift is very small. The more accurate polarimeters of the next generation may well measure these time shifts and evaluate the ellipticity of microlensing source stars.

  17. OGLE-2012-BLG-0455/MOA-2012-BLG-206: Microlensing event with ambiguity in planetary interpretations caused by incomplete coverage of planetary signal

    SciTech Connect

    Park, H.; Han, C.; Choi, J.-Y.; Hwang, K.-H.; Jung, Y. K.; Shin, I.-G.; Gould, A.; Gaudi, B. S.; Kavka, A.; Pogge, R. W.; Udalski, A.; Sumi, T.; Fouqué, P.; Christie, G.; Natusch, T.; Ngan, H.; Depoy, D. L.; Dong, Subo; Lee, C.-U.; Monard, L. A. G.; Collaboration: μFUN Collaboration; OGLE Collaboration; MOA Collaboration; and others

    2014-05-20

    Characterizing a microlensing planet is done by modeling an observed lensing light curve. In this process, it is often confronted that solutions of different lensing parameters result in similar light curves, causing difficulties in uniquely interpreting the lens system, and thus understanding the causes of different types of degeneracy is important. In this work, we show that incomplete coverage of a planetary perturbation can result in degenerate solutions even for events where the planetary signal is detected with a high level of statistical significance. We demonstrate the degeneracy for an actually observed event OGLE-2012-BLG-0455/MOA-2012-BLG-206. The peak of this high-magnification event (A {sub max} ∼ 400) exhibits very strong deviation from a point-lens model with Δχ{sup 2} ≳ 4000 for data sets with a total of 6963 measurements. From detailed modeling of the light curve, we find that the deviation can be explained by four distinct solutions, i.e., two very different sets of solutions, each with a twofold degeneracy. While the twofold (so-called close/wide) degeneracy is well understood, the degeneracy between the radically different solutions is not previously known. The model light curves of this degeneracy differ substantially in the parts that were not covered by observation, indicating that the degeneracy is caused by the incomplete coverage of the perturbation. It is expected that the frequency of the degeneracy introduced in this work will be greatly reduced with the improvement of the current lensing survey and follow-up experiments and the advent of new surveys.

  18. Stochastic Microlensing: Mathematical Theory and Applications

    NASA Astrophysics Data System (ADS)

    Teguia, Alberto Mokak

    expected number of minimum images in the limit of an infinite number of stars. This global expectation is bounded, while the global expected number of images and the global expected number of saddle images diverge as the order of the number of stars. Finally, we outline a framework for the study of stochastic microlensing in the neighbourhood of lensed images. This framework is related to the study of the local geometry of a random surface. In our case, the surface is non-Gaussian, and therefore standard literature on the subject does not apply. We explore the case of a random gravitational field caused by a random star.

  19. FREQUENCY OF SOLAR-LIKE SYSTEMS AND OF ICE AND GAS GIANTS BEYOND THE SNOW LINE FROM HIGH-MAGNIFICATION MICROLENSING EVENTS IN 2005-2008

    SciTech Connect

    Gould, A.; Dong, Subo; Gaudi, B. S.; Han, C. E-mail: gaudi@astronomy.ohio-state.ed

    2010-09-10

    We present the first measurement of the planet frequency beyond the 'snow line', for the planet-to-star mass-ratio interval -4.5 < log q < -2, corresponding to the range of ice giants to gas giants. We find (d{sup 2}N{sub pl})/(d log q d log s) = (0.36{+-}0.15) dex{sup -2} at the mean mass ratio q = 5 x 10{sup -4} with no discernible deviation from a flat (Oepik's law) distribution in log-projected separation s. The determination is based on a sample of six planets detected from intensive follow-up observations of high-magnification (A>200) microlensing events during 2005-2008. The sampled host stars have a typical mass M{sub host} {approx} 0.5 M {sub sun}, and detection is sensitive to planets over a range of planet-star-projected separations (s {sup -1}{sub max} R {sub E}, s{sub max} R {sub E}), where R {sub E} {approx} 3.5 AU(M{sub host}/M{sub sun}){sup 1/2} is the Einstein radius and s {sub max} {approx} (q/10{sup -4.3}){sup 1/3}. This corresponds to deprojected separations roughly three times the 'snow line'. We show that the observations of these events have the properties of a 'controlled experiment', which is what permits measurement of absolute planet frequency. High-magnification events are rare, but the survey-plus-follow-up high-magnification channel is very efficient: half of all high-mag events were successfully monitored and half of these yielded planet detections. The extremely high sensitivity of high-mag events leads to a policy of monitoring them as intensively as possible, independent of whether they show evidence of planets. This is what allows us to construct an unbiased sample. The planet frequency derived from microlensing is a factor 8 larger than the one derived from Doppler studies at factor {approx}25 smaller star-planet separations (i.e., periods 2-2000 days). However, this difference is basically consistent with the gradient derived from Doppler studies (when extrapolated well beyond the separations from which it is measured). This

  20. Astrometric microlensing with the GAIA satellite

    NASA Astrophysics Data System (ADS)

    Belokurov, V. A.; Evans, N. W.

    2002-04-01

    GAIA is the `super-Hipparcos ' survey satellite selected as a Cornerstone 6 mission by the European Space Agency. GAIA can measure microlensing by the brightening of source stars. For the broad G -band photometer, the all-sky source-averaged photometric optical depth is ~10-7 . There are ~1300 photometric microlensing events for which GAIA will measure at least one data point on the amplified light curve. GAIA can also measure microlensing by the small excursions of the light centroid that occur during events. The all-sky source-averaged astrometric microlensing optical depth is ~2.5×10-5 . Some ~25000 sources will have a significant variation of the centroid shift, together with a closest approach, during the lifetime of the mission. This is not the actual number of events that can be extracted from the GAIA data set, as the false detection rate has not been assessed. A covariance analysis is used to study the propagation of errors and the estimation of parameters from realistic sampling of the GAIA data stream of transits in the along-scan direction during microlensing events. The mass of the lens can be calculated to good accuracy if the lens is nearby so that the angular Einstein radius θ E is large; if the Einstein radius projected on to the observer plane r~ E is approximately an astronomical unit; or if the duration of the astrometric event is long (>~1yr) or the source star is bright . Monte Carlo simulations are used to study the ~2500 events for which the mass can be recovered with an error of <50 per cent. These high-quality events are dominated by disc lenses within a few tens of parsecs and source stars within a few hundred parsecs. We show that the local mass function can be recovered from the high-quality sample to good accuracy. GAIA is the first instrument with the capability of measuring the mass locally in very faint objects such as black holes and very cool white and brown dwarfs. For only ~5 per cent of all astrometric events will GAIA record

  1. Stellar, Remnant, Planetary, and Dark-Object Masses from Astrometric Microlensing

    NASA Technical Reports Server (NTRS)

    Gould, Andrew P.; Bennett, David P.; Boden, Andrew; Depoy, Darren L.; Gaudi, Scott B.; Griest, Kim; Han, Cheongho; Paczynski, Bohdan; Reid, I. Neill

    2004-01-01

    The primary goal of our project is to make a complete census of the stellar population of the Galaxy. We are broadening the term stellar here to include both ordinary stars and dark stars. Ordinary stars, burning their nuclear fuel and shining, can perhaps best be studied with traditional astronomical techniques, but dark stars, by which we include old brown dwarfs, black holes, old white dwarfs, neutron stars, and perhaps exotic objects such as mirror matter stars or primordial black holes, can only be studied by their gravitational effects. Traditionally, these objects have been probed in binaries, and thus selected in a way that may or may not be representative of their respective field populations. The only way to examine the field population of these stars is through microlensing, the deflection of light from a visible star in the background by an object (dark or not) in the foreground. When lensed, there are two images of the background star. Although these images cannot be resolved when the lens has a stellar mass, the lensing effect can be detected in two ways: photometrically, i.e. by measuring the magnification of the source by the lens, and astrometrically, i.e. by measuring the shift in the centroid of the two images. Photometric microlensing experiments have detected hundreds of microlensing events over the past decade. Despite its successes, photometric microlensing has so far been somewhat frustrating because these events are difficult to interpret. Almost nothing is known about the masses of individual lenses and very little is known about the statistical properties of the lenses treated as a whole, such as their average mass. Although probably over 100 of the lenses are in fact dark objects, we can't determine which they are, let alone investigate finer details such as what their masses are, and where they are in the Galaxy. With SIM, we will break the microlensing degeneracy, and allow detailed interpretation of individual microlensing events. We

  2. Detecting extrasolar asteroid belts through their microlensing signatures

    NASA Astrophysics Data System (ADS)

    Lake, Ethan; Zheng, Zheng; Dong, Subo

    2017-02-01

    We propose that extrasolar asteroid belts can be detected through their gravitational microlensing signatures. Asteroid belt + star lens systems create so-called 'pseudo-caustics', regions in the source plane where the magnification exhibits a finite but discontinuous jump. These features allow such systems to generate distinctive signatures in the microlensing light curves for a wide range of belt configurations, with source trajectories as far as tenths of the Einstein ring radius from the centre of the lens. Sample light curves for a range of asteroid belt parameters are presented. In the near future, space-based microlensing surveys like WFIRST, which will have the power of detecting per cent-level changes in microlensing light curves even with subminute exposure times, may be able to discover extrasolar asteroid belts with masses of the order of an earth mass.

  3. MACHO project 2nd year LMC microlensing results and dark matter implications

    SciTech Connect

    Alcock, C.; Allsman, R.A.; Alves, D.

    1996-02-01

    The MACHO Project is searching for galactic dark matter in the form of massive compact halo objects (Machos). Millions of stars in the Large Magellanic Cloud (LMC), Small Magellanic Cloud (SMC), and Galactic bulge are photometrically monitored in an attempt to detect rare gravitational microlensing events caused by otherwise invisible Machos. Analysis of two years of photometry on 8.5 million stars in the LMC reveals 8 candidate microlensing events, far more than the one event expected from lensing by low-mass stars in known galactic populations. Five these eight events we estimate the optical depth towards the LMC from events with 2 < i < 200 days to be r2 280 about 2.9+1 4/-0.8 X 10-7. This exceeds the optical depth of 0.5 x 10-7 expected for known stars and is to be compared with an optical depth of 4.7 X 10-7 predicted for a `standard` halo composed entirely of Machos. The total mass in this lensing population is 2 +1.2/-0.7 x 10+11 Mo (within 50 kpc from the Galactic center). Event timescales yield a most probable Macho Mass of 0.5 +0.3/-0.2 Mo, although this value is quite model dependent. -0.2

  4. Studies on the high-energy follow-up of gravitational wave transient events

    NASA Astrophysics Data System (ADS)

    Razzano, Massimiliano; Patricelli, Barbara; Cella, Giancarlo; Fidecaro, Francesco; Pian, Elena; Stamerra, Antonio; Branchesi, Marica

    2016-05-01

    Second-generation gravitational wave interferometers, such as Advanced LIGO and Advanced Virgo, will soon reach sensitivities sufficient to first detect gravitational waves and open a new era in the multi-messenger investigations of the cosmos. The most violent and energetic astrophysical phenomena, including the mergers of compact objects or the core collapse of massive stars, are promising sources of gravitational waves, and are thought to be connected with transient phenomena such as Gamma Ray Bursts and supernovae. Combined observations of gravitational and electromagnetic signals from these events will thus provide a unique opportunity to unveil their progenitors and study the physics of compact objects. In particular, gamma-ray ground-based and space observatories such as Fermi or the Air Cherenkov Telescopes will be crucial to observe the high-energy electromagnetic counterparts of transient gravitational wave signals and provide a robust identification based on a precise sky localization. We will report on our studies of possible joint observation strategies carried on by gravitational interferometers and gamma-ray telescopes, with particular attention to the high-energy follow-up of Gamma Ray Bursts.

  5. Microlensing of quasar ultraviolet iron emission

    SciTech Connect

    Guerras, E.; Mediavilla, E.; Kochanek, C. S.; Muñoz, J. A.; Falco, E.; Motta, V.; Rojas, K.

    2013-12-01

    We measure the differential microlensing of the UV Fe II and Fe III emission line blends between 14 quasar image pairs in 13 gravitational lenses. We find that the UV iron emission is strongly microlensed in four cases with amplitudes comparable to that of the continuum. Statistically modeling the magnifications, we infer a typical size of r{sub s}∼4√(M/M{sub ⊙}) light-days for the Fe line-emitting regions, which is comparable to the size of the region generating the UV continuum (∼3-7 light-days). This may indicate that a significant part of the UV Fe II and Fe III emission originates in the quasar accretion disk.

  6. The MACHO project: Microlensing and variable stars

    SciTech Connect

    Alcock, C.; Alves, D. R.; Axelrod, T. S.; Bennett, D. P.; Marshall, S. L.; Minniti, D.

    1996-10-01

    The MACHO Project monitors millions of stars in the Large Magellanic Cloud, the Small Magellanic Cloud and the bulge of the Milky Way searching for the gravitational microlensing signature of baryonic dark matter. This Project has yielded surprising results. An analysis of two years of data monitoring the Large Magellanic Cloud points to {approximately} 50% of the mass of the Milky Way`s halo in compact objects of {approximately} 0.5 solar mass. An analysis of one year of monitoring the bulge has yielded more microlensing than predicted without invocation of a massive bar or significant disk dark matter. The huge database of light curves created by this search is yielding information on extremely rare types of astrophysical variability as well as providing temporal detail for the study of well known variable astrophysical phenomena. The variable star catalog created from this database is previewed and example light curves are presented. 31 refs., 7 figs., 1 tab.

  7. THE MICROLENSING PROPERTIES OF A SAMPLE OF 87 LENSED QUASARS

    SciTech Connect

    Mosquera, A. M.; Kochanek, C. S.

    2011-09-01

    Gravitational microlensing is a powerful tool for probing the physical properties of quasar accretion disks and properties of the lens galaxy such as its dark matter fraction and mean stellar mass. Unfortunately, the number of lensed quasars ({approx}90) exceeds our monitoring capabilities. Thus, estimating their microlensing properties is important for identifying good microlensing candidates as well as for the expectations of future surveys. In this work, we estimate the microlensing properties of a sample of 87 lensed quasars. While the median Einstein radius crossing timescale is 20.6 years, the median source crossing timescale is 7.3 months. Broadly speaking, this means that on {approx}10 year timescales roughly half the lenses will be quiescent, with the source in a broad demagnified valley, and roughly half will be active with the source lying in the caustic ridges. We also found that the location of the lens system relative to the cosmic microwave background dipole has a modest effect on microlensing timescales, and in theory microlensing could be used to confirm the kinematic origin of the dipole. As a corollary of our study we analyzed the accretion rate parameters in a sub-sample of 32 lensed quasars. At fixed black hole mass, it is possible to sample a broad range of luminosities (i.e., Eddington factors) if it becomes feasible to monitor fainter lenses.

  8. REVEALING THE STRUCTURE OF AN ACCRETION DISK THROUGH ENERGY-DEPENDENT X-RAY MICROLENSING

    SciTech Connect

    Chartas, G.; Moore, D.; Kochanek, C. S.; Mosquera, A. M.; Blackburne, J. A.; Dai, X.

    2012-10-01

    We present results from monitoring observations of the gravitationally lensed quasar RX J1131-1231 performed with the Chandra X-Ray Observatory. The X-ray observations were planned with relatively long exposures that allowed a search for energy-dependent microlensing in the soft (0.2-2 keV) and hard (2-10 keV) light curves of the images of RX J1131-1231. We detect significant microlensing in the X-ray light curves of images A and D, and energy-dependent microlensing of image D. The magnification of the soft band appears to be larger than that in the hard band by a factor of {approx}1.3 when image D becomes more magnified. This can be explained by the difference between a compact, softer-spectrum corona that is producing a more extended, harder spectrum reflection component off the disk. This is supported by the evolution of the fluorescent iron line in image D over three consecutive time-averaged phases of the light curve. In the first period, an Fe line at E = 6.35{sup +0.14}{sub -0.14} keV is detected (at >99% confidence). In the second period, two Fe lines are detected, one at E = 5.50{sup +0.03}{sub -0.08} keV (detected at >99% confidence) and another at E = 6.04{sup +0.10}{sub -0.07} keV (marginally detected at >90% confidence), and in the third period, a broadened Fe line at 6.42{sup +0.16}{sub -0.14} keV is detected (at >99% confidence). This evolution of the Fe line profile during the microlensing event is consistent with the line distortion expected when a caustic passes over the inner disk where the shape of the fluorescent Fe line is distorted by general relativistic and Doppler effects.

  9. Determination of Microlensing Selection Criteria for the SuperMACHO Survey

    SciTech Connect

    Garg, A

    2008-10-10

    The SuperMACHO project is a 5 year survey to determine the nature of the lens population responsible for the excess microlensing rate toward the Large Magellanic Cloud observed by the MACHO project [1]. The survey probes deeper than earlier surveys unveiling many more extragalactic contaminants, particularly type Ia supernovae and active galactic nuclei. Using {approx}10{sup 7} simulated light curves of both microlensing events and type Ia supernovae we determine selection criteria optimized to maximize the microlensing detection efficiency while minimizing the contamination rate from non-microlensing events. We discuss these simulations and the selection criteria.

  10. Theory of dispersive microlenses

    NASA Technical Reports Server (NTRS)

    Herman, B.; Gal, George

    1993-01-01

    A dispersive microlens is a miniature optical element which simultaneously focuses and disperses light. Arrays of dispersive mircolenses have potential applications in multicolor focal planes. They have a 100 percent optical fill factor and can focus light down to detectors of diffraction spot size, freeing up areas on the focal plane for on-chip analog signal processing. Use of dispersive microlenses allows inband color separation within a pixel and perfect scene registration. A dual-color separation has the potential for temperature discrimination. We discuss the design of dispersive microlenses and present sample results for efficient designs.

  11. High-energy neutrino follow-up search of gravitational wave event GW150914 with ANTARES and IceCube

    NASA Astrophysics Data System (ADS)

    Adrián-Martínez, S.; Albert, A.; André, M.; Anghinolfi, M.; Anton, G.; Ardid, M.; Aubert, J.-J.; Avgitas, T.; Baret, B.; Barrios-Martí, J.; Basa, S.; Bertin, V.; Biagi, S.; Bormuth, R.; Bouwhuis, M. C.; Bruijn, R.; Brunner, J.; Busto, J.; Capone, A.; Caramete, L.; Carr, J.; Celli, S.; Chiarusi, T.; Circella, M.; Coleiro, A.; Coniglione, R.; Costantini, H.; Coyle, P.; Creusot, A.; Deschamps, A.; De Bonis, G.; Distefano, C.; Donzaud, C.; Dornic, D.; Drouhin, D.; Eberl, T.; El Bojaddaini, I.; Elsässer, D.; Enzenhöfer, A.; Fehn, K.; Felis, I.; Fusco, L. A.; Galatà, S.; Gay, P.; Geißelsöder, S.; Geyer, K.; Giordano, V.; Gleixner, A.; Glotin, H.; Gracia-Ruiz, R.; Graf, K.; Hallmann, S.; van Haren, H.; Heijboer, A. J.; Hello, Y.; Hernández-Rey, J. J.; Hößl, J.; Hofestädt, J.; Hugon, C.; Illuminati, G.; James, C. W.; de Jong, M.; Jongen, M.; Kadler, M.; Kalekin, O.; Katz, U.; Kießling, D.; Kouchner, A.; Kreter, M.; Kreykenbohm, I.; Kulikovskiy, V.; Lachaud, C.; Lahmann, R.; Lefèvre, D.; Leonora, E.; Loucatos, S.; Marcelin, M.; Margiotta, A.; Marinelli, A.; Martínez-Mora, J. A.; Mathieu, A.; Melis, K.; Michael, T.; Migliozzi, P.; Moussa, A.; Mueller, C.; Nezri, E.; Pǎvǎlaş, G. E.; Pellegrino, C.; Perrina, C.; Piattelli, P.; Popa, V.; Pradier, T.; Racca, C.; Riccobene, G.; Roensch, K.; Saldaña, M.; Samtleben, D. F. E.; Sánchez-Losa, A.; Sanguineti, M.; Sapienza, P.; Schnabel, J.; Schüssler, F.; Seitz, T.; Sieger, C.; Spurio, M.; Stolarczyk, Th.; Taiuti, M.; Trovato, A.; Tselengidou, M.; Turpin, D.; Tönnis, C.; Vallage, B.; Vallée, C.; Van Elewyck, V.; Vivolo, D.; Wagner, S.; Wilms, J.; Zornoza, J. D.; Zúñiga, J.; Aartsen, M. G.; Abraham, K.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Ahrens, M.; Altmann, D.; Anderson, T.; Ansseau, I.; Anton, G.; Archinger, M.; Arguelles, C.; Arlen, T. C.; Auffenberg, J.; Bai, X.; Barwick, S. W.; Baum, V.; Bay, R.; Beatty, J. J.; Becker Tjus, J.; Becker, K.-H.; Beiser, E.; BenZvi, S.; Berghaus, P.; Berley, D.; Bernardini, E.; Bernhard, A.; Besson, D. Z.; Binder, G.; Bindig, D.; Bissok, M.; Blaufuss, E.; Blumenthal, J.; Boersma, D. J.; Bohm, C.; Börner, M.; Bos, F.; Bose, D.; Böser, S.; Botner, O.; Braun, J.; Brayeur, L.; Bretz, H.-P.; Buzinsky, N.; Casey, J.; Casier, M.; Cheung, E.; Chirkin, D.; Christov, A.; Clark, K.; Classen, L.; Coenders, S.; Collin, G. H.; Conrad, J. M.; Cowen, D. F.; Cruz Silva, A. H.; Daughhetee, J.; Davis, J. C.; Day, M.; de André, J. P. A. M.; De Clercq, C.; del Pino Rosendo, E.; Dembinski, H.; De Ridder, S.; Desiati, P.; de Vries, K. D.; de Wasseige, G.; de With, M.; DeYoung, T.; Díaz-Vélez, J. C.; di Lorenzo, V.; Dujmovic, H.; Dumm, J. P.; Dunkman, M.; Eberhardt, B.; Ehrhardt, T.; Eichmann, B.; Euler, S.; Evenson, P. A.; Fahey, S.; Fazely, A. R.; Feintzeig, J.; Felde, J.; Filimonov, K.; Finley, C.; Flis, S.; Fösig, C.-C.; Fuchs, T.; Gaisser, T. K.; Gaior, R.; Gallagher, J.; Gerhardt, L.; Ghorbani, K.; Gier, D.; Gladstone, L.; Glagla, M.; Glüsenkamp, T.; Goldschmidt, A.; Golup, G.; Gonzalez, J. G.; Góra, D.; Grant, D.; Griffith, Z.; Ha, C.; Haack, C.; Haj Ismail, A.; Hallgren, A.; Halzen, F.; Hansen, E.; Hansmann, B.; Hansmann, T.; Hanson, K.; Hebecker, D.; Heereman, D.; Helbing, K.; Hellauer, R.; Hickford, S.; Hignight, J.; Hill, G. C.; Hoffman, K. D.; Hoffmann, R.; Holzapfel, K.; Homeier, A.; Hoshina, K.; Huang, F.; Huber, M.; Huelsnitz, W.; Hulth, P. O.; Hultqvist, K.; In, S.; Ishihara, A.; Jacobi, E.; Japaridze, G. S.; Jeong, M.; Jero, K.; Jones, B. J. P.; Jurkovic, M.; Kappes, A.; Karg, T.; Karle, A.; Katz, U.; Kauer, M.; Keivani, A.; Kelley, J. L.; Kemp, J.; Kheirandish, A.; Kim, M.; Kintscher, T.; Kiryluk, J.; Klein, S. R.; Kohnen, G.; Koirala, R.; Kolanoski, H.; Konietz, R.; Köpke, L.; Kopper, C.; Kopper, S.; Koskinen, D. J.; Kowalski, M.; Krings, K.; Kroll, G.; Kroll, M.; Krückl, G.; Kunnen, J.; Kunwar, S.; Kurahashi, N.; Kuwabara, T.; Labare, M.; Lanfranchi, J. L.; Larson, M. J.; Lennarz, D.; Lesiak-Bzdak, M.; Leuermann, M.; Leuner, J.; Lu, L.; Lünemann, J.; Madsen, J.; Maggi, G.; Mahn, K. B. M.; Mandelartz, M.; Maruyama, R.; Mase, K.; Matis, H. S.; Maunu, R.; McNally, F.; Meagher, K.; Medici, M.; Meier, M.; Meli, A.; Menne, T.; Merino, G.; Meures, T.; Miarecki, S.; Middell, E.; Mohrmann, L.; Montaruli, T.; Morse, R.; Nahnhauer, R.; Naumann, U.; Neer, G.; Niederhausen, H.; Nowicki, S. C.; Nygren, D. R.; Obertacke Pollmann, A.; Olivas, A.; Omairat, A.; O'Murchadha, A.; Palczewski, T.; Pandya, H.; Pankova, D. V.; Paul, L.; Pepper, J. A.; Pérez de los Heros, C.; Pfendner, C.; Pieloth, D.; Pinat, E.; Posselt, J.; Price, P. B.; Przybylski, G. T.; Quinnan, M.; Raab, C.; Rädel, L.; Rameez, M.; Rawlins, K.; Reimann, R.; Relich, M.; Resconi, E.; Rhode, W.; Richman, M.; Richter, S.; Riedel, B.; Robertson, S.; Rongen, M.; Rott, C.; Ruhe, T.; Ryckbosch, D.; Sabbatini, L.; Sander, H.-G.; Sandrock, A.; Sandroos, J.; Sarkar, S.; Schatto, K.; Schimp, M.; Schlunder, P.; Schmidt, T.; Schoenen, S.; Schöneberg, S.; Schönwald, A.; Schumacher, L.; Seckel, D.; Seunarine, S.; Soldin, D.; Song, M.; Spiczak, G. M.; Spiering, C.; Stahlberg, M.; Stamatikos, M.; Stanev, T.; Stasik, A.; Steuer, A.; Stezelberger, T.; Stokstad, R. G.; Stößl, A.; Ström, R.; Strotjohann, N. L.; Sullivan, G. W.; Sutherland, M.; Taavola, H.; Taboada, I.; Tatar, J.; Ter-Antonyan, S.; Terliuk, A.; Tešić, G.; Tilav, S.; Toale, P. A.; Tobin, M. N.; Toscano, S.; Tosi, D.; Tselengidou, M.; Turcati, A.; Unger, E.; Usner, M.; Vallecorsa, S.; Vandenbroucke, J.; van Eijndhoven, N.; Vanheule, S.; van Santen, J.; Veenkamp, J.; Vehring, M.; Voge, M.; Vraeghe, M.; Walck, C.; Wallace, A.; Wallraff, M.; Wandkowsky, N.; Weaver, Ch.; Wendt, C.; Westerhoff, S.; Whelan, B. J.; Wiebe, K.; Wiebusch, C. H.; Wille, L.; Williams, D. R.; Wills, L.; Wissing, H.; Wolf, M.; Wood, T. R.; Woschnagg, K.; Xu, D. L.; Xu, X. W.; Xu, Y.; Yanez, J. P.; Yodh, G.; Yoshida, S.; Zoll, M.; Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M. R.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V. B.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Aiello, L.; Ain, A.; Ajith, P.; Allen, B.; Allocca, A.; Altin, P. A.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C. C.; Areeda, J. S.; Arnaud, N.; Arun, K. G.; Ascenzi, S.; Ashton, G.; Ast, M.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Babak, S.; Bacon, P.; Bader, M. K. M.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barclay, S. E.; Barish, B. C.; Barker, D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barta, D.; Bartlett, J.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Baune, C.; Bavigadda, V.; Bazzan, M.; Behnke, B.; Bejger, M.; Belczynski, C.; Bell, A. S.; Bell, C. J.; Berger, B. K.; Bergman, J.; Bergmann, G.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Birney, R.; Biscans, S.; Bisht, A.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blair, C. D.; Blair, D. G.; Blair, R. M.; Bloemen, S.; Bock, O.; Bodiya, T. P.; Boer, M.; Bogaert, G.; Bogan, C.; Bohe, A.; Bojtos, P.; Bond, C.; Bondu, F.; Bonnand, R.; Boom, B. A.; Bork, R.; Boschi, V.; Bose, S.; Bouffanais, Y.; Bozzi, A.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Briant, T.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brockill, P.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brown, N. M.; Buchanan, C. C.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Cahillane, C.; Calderón Bustillo, J.; Callister, T.; Calloni, E.; Camp, J. B.; Cannon, K. C.; Cao, J.; Capano, C. D.; Capocasa, E.; Carbognani, F.; Caride, S.; Casanueva Diaz, J.; Casentini, C.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C. B.; Cerboni Baiardi, L.; Cerretani, G.; Cesarini, E.; Chakraborty, R.; Chalermsongsak, T.; Chamberlin, S. J.; Chan, M.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Chen, H. Y.; Chen, Y.; Cheng, C.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, S.; Chung, S.; Ciani, G.; Clara, F.; Clark, J. A.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Collette, C. G.; Cominsky, L.; Constancio, M.; Conte, A.; Conti, L.; Cook, D.; Corbitt, T. R.; Cornish, N.; Corsi, A.; Cortese, S.; Costa, C. A.; Coughlin, M. W.; Coughlin, S. B.; Coulon, J.-P.; Countryman, S. T.; Couvares, P.; Cowan, E. E.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Craig, K.; Creighton, J. D. E.; Cripe, J.; Crowder, S. G.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dal Canton, T.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Darman, N. S.; Dattilo, V.; Dave, I.; Daveloza, H. P.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; DeBra, D.; Debreczeni, G.; Degallaix, J.; De Laurentis, M.; Deléglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dereli, H.; Dergachev, V.; DeRosa, R. T.; De Rosa, R.; DeSalvo, R.; Dhurandhar, S.; Díaz, M. C.; Di Fiore, L.; Di Giovanni, M.; Di Lieto, A.; Di Pace, S.; Di Palma, I.; Di Virgilio, A.; Dojcinoski, G.; Dolique, V.; Donovan, F.; Dooley, K. L.; Doravari, S.; Douglas, R.; Downes, T. P.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dwyer, S. E.; Edo, T. B.; Edwards, M. C.; Effler, A.; Eggenstein, H.-B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Engels, W.; Essick, R. C.; Etzel, T.; Evans, M.; Evans, T. M.; Everett, R.; Factourovich, M.; Fafone, V.; Fair, H.; Fairhurst, S.; Fan, X.; Fang, Q.; Farinon, S.; Farr, B.; Farr, W. M.; Favata, M.; Fays, M.; Fehrmann, H.; Fejer, M. M.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Fiori, I.; Fiorucci, D.; Fisher, R. P.; Flaminio, R.; Fletcher, M.; Fournier, J.-D.; Franco, S.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Frey, V.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gabbard, H. A. G.; Gair, J. R.; Gammaitoni, L.; Gaonkar, S. G.; Garufi, F.; Gatto, A.; Gaur, G.; Gehrels, N.; Gemme, G.; Gendre, B.; Genin, E.; Gennai, A.; George, J.; Gergely, L.; Germain, V.; Ghosh, Archisman; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gill, K.; Glaefke, A.; Goetz, E.; Goetz, R.; Gondan, L.; González, G.; Gonzalez Castro, J. M.; Gopakumar, A.; Gordon, N. A.; Gorodetsky, M. L.; Gossan, S. E.; Gosselin, M.; Gouaty, R.; Graef, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greco, G.; Green, A. C.; Groot, P.; Grote, H.; Grunewald, S.; Guidi, G. M.; Guo, X.; Gupta, A.; Gupta, M. K.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Hacker, J. J.; Hall, B. R.; Hall, E. D.; Hammond, G.; Haney, M.; Hanke, M. M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hanson, J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M. J.; Hartman, M. T.; Haster, C.-J.; Haughian, K.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Hennig, J.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Hofman, D.; Hollitt, S. E.; Holt, K.; Holz, D. E.; Hopkins, P.; Hosken, D. J.; Hough, J.; Houston, E. A.; Howell, E. J.; Hu, Y. M.; Huang, S.; Huerta, E. A.; Huet, D.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Idrisy, A.; Indik, N.; Ingram, D. R.; Inta, R.; Isa, H. N.; Isac, J.-M.; Isi, M.; Islas, G.; Isogai, T.; Iyer, B. R.; Izumi, K.; Jacqmin, T.; Jang, H.; Jani, K.; Jaranowski, P.; Jawahar, S.; Jiménez-Forteza, F.; Johnson, W. W.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; Haris, K.; Kalaghatgi, C. V.; Kalogera, V.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Karki, S.; Kasprzack, M.; Katsavounidis, E.; Katzman, W.; Kaufer, S.; Kaur, T.; Kawabe, K.; Kawazoe, F.; Kéfélian, F.; Kehl, M. S.; Keitel, D.; Kelley, D. B.; Kells, W.; Kennedy, R.; Key, J. S.; Khalaidovski, A.; Khalili, F. Y.; Khan, I.; Khan, S.; Khan, Z.; Khazanov, E. A.; Kijbunchoo, N.; Kim, C.; Kim, J.; Kim, K.; Kim, Nam-Gyu; Kim, Namjun; Kim, Y.-M.; King, E. J.; King, P. J.; Kinzel, D. L.; Kissel, J. S.; Kleybolte, L.; Klimenko, S.; Koehlenbeck, S. M.; Kokeyama, K.; Koley, S.; Kondrashov, V.; Kontos, A.; Korobko, M.; Korth, W. Z.; Kowalska, I.; Kozak, D. B.; Kringel, V.; Krishnan, B.; Królak, A.; Krueger, C.; Kuehn, G.; Kumar, P.; Kuo, L.; Kutynia, A.; Lackey, B. D.; Landry, M.; Lange, J.; Lantz, B.; Lasky, P. D.; Lazzarini, A.; Lazzaro, C.; Leaci, P.; Leavey, S.; Lebigot, E. O.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Lee, K.; Lenon, A.; Leonardi, M.; Leong, J. R.; Leroy, N.; Letendre, N.; Levin, Y.; Levine, B. M.; Li, T. G. F.; Libson, A.; Littenberg, T. B.; Lockerbie, N. A.; Logue, J.; Lombardi, A. L.; Lord, J. E.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J. D.; Lück, H.; Lundgren, A. P.; Luo, J.; Lynch, R.; Ma, Y.; MacDonald, T.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magaña-Sandoval, F.; Magee, R. M.; Mageswaran, M.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man, N.; Mandel, I.; Mandic, V.; Mangano, V.; Mansell, G. L.; Manske, M.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markosyan, A. S.; Maros, E.; Martelli, F.; Martellini, L.; Martin, I. W.; Martin, R. M.; Martynov, D. V.; Marx, J. N.; Mason, K.; Masserot, A.; Massinger, T. J.; Masso-Reid, M.; Matichard, F.; Matone, L.; Mavalvala, N.; Mazumder, N.; Mazzolo, G.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McGuire, S. C.; McIntyre, G.; McIver, J.; McManus, D. J.; McWilliams, S. T.; Meacher, D.; Meadors, G. D.; Meidam, J.; Melatos, A.; Mendell, G.; Mendoza-Gandara, D.; Mercer, R. A.; Merilh, E.; Merzougui, M.; Meshkov, S.; Messenger, C.; Messick, C.; Meyers, P. M.; Mezzani, F.; Miao, H.; Michel, C.; Middleton, H.; Mikhailov, E. E.; Milano, L.; Miller, J.; Millhouse, M.; Minenkov, Y.; Ming, J.; Mirshekari, S.; Mishra, C.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moggi, A.; Mohan, M.; Mohapatra, S. R. P.; Montani, M.; Moore, B. C.; Moore, C. J.; Moraru, D.; Moreno, G.; Morriss, S. R.; Mossavi, K.; Mours, B.; Mow-Lowry, C. M.; Mueller, C. L.; Mueller, G.; Muir, A. W.; Mukherjee, Arunava; Mukherjee, D.; Mukherjee, S.; Mukund, N.; Mullavey, A.; Munch, J.; Murphy, D. J.; Murray, P. G.; Mytidis, A.; Nardecchia, I.; Naticchioni, L.; Nayak, R. K.; Necula, V.; Nedkova, K.; Nelemans, G.; Neri, M.; Neunzert, A.; Newton, G.; Nguyen, T. T.; Nielsen, A. B.; Nissanke, S.; Nitz, A.; Nocera, F.; Nolting, D.; Normandin, M. E. N.; Nuttall, L. K.; Oberling, J.; Ochsner, E.; O'Dell, J.; Oelker, E.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Oliver, M.; Oppermann, P.; Oram, Richard J.; O'Reilly, B.; O'Shaughnessy, R.; Ott, C. D.; Ottaway, D. J.; Ottens, R. S.; Overmier, H.; Owen, B. J.; Pai, A.; Pai, S. A.; Palamos, J. R.; Palashov, O.; Palomba, C.; Pal-Singh, A.; Pan, H.; Pankow, C.; Pannarale, F.; Pant, B. C.; Paoletti, F.; Paoli, A.; Papa, M. A.; Paris, H. R.; Parker, W.; Pascucci, D.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patricelli, B.; Patrick, Z.; Pearlstone, B. L.; Pedraza, M.; Pedurand, R.; Pekowsky, L.; Pele, A.; Penn, S.; Perreca, A.; Phelps, M.; Piccinni, O.; Pichot, M.; Piergiovanni, F.; Pierro, V.; Pillant, G.; Pinard, L.; Pinto, I. M.; Pitkin, M.; Poggiani, R.; Popolizio, P.; Post, A.; Powell, J.; Prasad, J.; Predoi, V.; Premachandra, S. S.; Prestegard, T.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prix, R.; Prodi, G. A.; Prokhorov, L.; Puncken, O.; Punturo, M.; Puppo, P.; Pürrer, M.; Qi, H.; Qin, J.; Quetschke, V.; Quintero, E. A.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Radkins, H.; Raffai, P.; Raja, S.; Rakhmanov, M.; Rapagnani, P.; Raymond, V.; Razzano, M.; Re, V.; Read, J.; Reed, C. M.; Regimbau, T.; Rei, L.; Reid, S.; Reitze, D. H.; Rew, H.; Reyes, S. D.; Ricci, F.; Riles, K.; Robertson, N. A.; Robie, R.; Robinet, F.; Rocchi, A.; Rolland, L.; Rollins, J. G.; Roma, V. J.; Romano, J. D.; Romano, R.; Romanov, G.; Romie, J. H.; Rosińska, D.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Ryan, K.; Sachdev, S.; Sadecki, T.; Sadeghian, L.; Salconi, L.; Saleem, M.; Salemi, F.; Samajdar, A.; Sammut, L.; Sanchez, E. J.; Sandberg, V.; Sandeen, B.; Sanders, J. R.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Sauter, O.; Savage, R. L.; Sawadsky, A.; Schale, P.; Schilling, R.; Schmidt, J.; Schmidt, P.; Schnabel, R.; Schofield, R. M. S.; Schönbeck, A.; Schreiber, E.; Schuette, D.; Schutz, B. F.; Scott, J.; Scott, S. M.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sequino, V.; Sergeev, A.; Serna, G.; Setyawati, Y.; Sevigny, A.; Shaddock, D. A.; Shah, S.; Shahriar, M. S.; Shaltev, M.; Shao, Z.; Shapiro, B.; Shawhan, P.; Sheperd, A.; Shoemaker, D. H.; Shoemaker, D. M.; Siellez, K.; Siemens, X.; Sigg, D.; Silva, A. D.; Simakov, D.; Singer, A.; Singer, L. P.; Singh, A.; Singh, R.; Singhal, A.; Sintes, A. M.; Slagmolen, B. J. J.; Smith, J. R.; Smith, N. D.; Smith, R. J. E.; Son, E. J.; Sorazu, B.; Sorrentino, F.; Souradeep, T.; Srivastava, A. K.; Staley, A.; Steinke, M.; Steinlechner, J.; Steinlechner, S.; Steinmeyer, D.; Stephens, B. C.; Stone, R.; Strain, K. A.; Straniero, N.; Stratta, G.; Strauss, N. A.; Strigin, S.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sun, L.; Sutton, P. J.; Swinkels, B. L.; Szczepańczyk, M. J.; Tacca, M.; Talukder, D.; Tanner, D. B.; Tápai, M.; Tarabrin, S. P.; Taracchini, A.; Taylor, R.; Theeg, T.; Thirugnanasambandam, M. P.; Thomas, E. G.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Tiwari, S.; Tiwari, V.; Tokmakov, K. V.; Tomlinson, C.; Tonelli, M.; Torres, C. V.; Torrie, C. I.; Töyrä, D.; Travasso, F.; Traylor, G.; Trifirò, D.; Tringali, M. C.; Trozzo, L.; Tse, M.; Turconi, M.; Tuyenbayev, D.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Usman, S. A.; Vahlbruch, H.; Vajente, G.; Valdes, G.; van Bakel, N.; van Beuzekom, M.; van den Brand, J. F. J.; Van Den Broeck, C.; Vander-Hyde, D. C.; van der Schaaf, L.; van Heijningen, J. V.; van Veggel, A. A.; Vardaro, M.; Vass, S.; Vasúth, M.; Vaulin, R.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Verkindt, D.; Vetrano, F.; Viceré, A.; Vinciguerra, S.; Vine, D. J.; Vinet, J.-Y.; Vitale, S.; Vo, T.; Vocca, H.; Vorvick, C.; Voss, D.; Vousden, W. D.; Vyatchanin, S. P.; Wade, A. R.; Wade, L. E.; Wade, M.; Walker, M.; Wallace, L.; Walsh, S.; Wang, G.; Wang, H.; Wang, M.; Wang, X.; Wang, Y.; Ward, R. L.; Warner, J.; Was, M.; Weaver, B.; Wei, L.-W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Welborn, T.; Wen, L.; Weßels, P.; Westphal, T.; Wette, K.; Whelan, J. T.; Whitcomb, S. E.; White, D. J.; Whiting, B. F.; Williams, R. D.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M. H.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Worden, J.; Wright, J. L.; Wu, G.; Yablon, J.; Yam, W.; Yamamoto, H.; Yancey, C. C.; Yap, M. J.; Yu, H.; Yvert, M.; ZadroŻny, A.; Zangrando, L.; Zanolin, M.; Zendri, J.-P.; Zevin, M.; Zhang, F.; Zhang, L.; Zhang, M.; Zhang, Y.; Zhao, C.; Zhou, M.; Zhou, Z.; Zhu, X. J.; Zucker, M. E.; Zuraw, S. E.; Zweizig, J.; Antares Collaboration

    2016-06-01

    We present the high-energy-neutrino follow-up observations of the first gravitational wave transient GW150914 observed by the Advanced LIGO detectors on September 14, 2015. We search for coincident neutrino candidates within the data recorded by the IceCube and Antares neutrino detectors. A possible joint detection could be used in targeted electromagnetic follow-up observations, given the significantly better angular resolution of neutrino events compared to gravitational waves. We find no neutrino candidates in both temporal and spatial coincidence with the gravitational wave event. Within ±500 s of the gravitational wave event, the number of neutrino candidates detected by IceCube and Antares were three and zero, respectively. This is consistent with the expected atmospheric background, and none of the neutrino candidates were directionally coincident with GW150914. We use this nondetection to constrain neutrino emission from the gravitational-wave event.

  12. Microlenses of smectic flowers

    NASA Astrophysics Data System (ADS)

    Serra, Francesca; Gharbi, Mohamed-Amine; Liu, Iris B.; Luo, Yimin; Bade, Nathan D.; Kamien, Randall D.; Yang, Shu; Stebe, Kathleen J.

    2015-03-01

    The search for new and tunable optical components finds suitable candidates in liquid crystals, which have both reconfigurability and unique optical properties. Here we discuss smectic liquid crystals arranged in focal conic domains (FCDs), which can work as gradient-refractive index microlenses. We exploit this property to create an assembly of microlenses that resembles an insect compound eye. The system consists of a thin layer of smectics on a substrate patterned with microposts. The smectic film is pinned at the microposts, creating a curved interface that induces a hierarchical assembly of FCDs called the ''flower pattern'': each FCD resembles the petal of a flower around the micropost. The arrangement of FCDs, with the largest FCDs pinned at the top of the microposts and the smallest FCDs in the low-curvature regions far from the post, is mirrored into a hierarchy of focal lengths of the microlenses. This structure is reconfigurable by melting and cooling and it allows visualizing objects placed at different distances, hence it can be exploited for 3D image reconstruction. Similarly to the insect eyes, the flower pattern is sensitive to light polarization: the large FCDs, with the largest eccentricity, only work as microlenses for one direction of light polarization. We thank the MRSEC NSF Grant DMR11-20901.

  13. Microlensing on extended structures having a spherically-symmetric mass distribution

    NASA Astrophysics Data System (ADS)

    Zhdanov, V.; Alexandrov, A.; Stashko, O.

    2016-06-01

    Different dark matter (DM) models predict various clustering properties, i.e. the possibility of DM to form massive objects on different scales. The lower mass limit of these objects according to [1, 2]. may be of the order of planetary masses. The gravitational microlensing can be used to confirm or to reject the existence of such structures and therefore to argue in favor or against concrete DM theories. There are observational programs (OGLE, EROS etc) yielding the light curves of a remote objects in high amplification events (HAE) due to microlensing on foreground masses of the Galaxy. In case when the foreground mass is an extended one, then the light curve in HAE must differ from the light curve due to ordinary microlensing on a point mass. However the question is: what is the value of this difference and is it possible to register this difference with modern observational facilities. This question has been studied elsewhere [3–5] by means of special model lens mappings. In this paper we study this problem starting directly from mass distribution of the extended structure. Namely, we consider microlensing on an extended DM clump with the cored spherically-symmetric mass profile (without a singularity in the center). We present examples of the amplification curves in both cases. Then we generate the amplification curves in case of the extended clump model for different values R, γ when the clump moves uniformly with respect to the line of sight with some impact parameter p and velocity V. These curves are then fitted with the point microlens model (with free parameters p and V) and we estimate the difference between the curves. The general outcome is that the amplification curves in case of the extended clumps are very similar to those in case of the point microlens (with appropriately chosen parameters p and V that cannot be derived from observations independently), and it would be difficult to distinguish them on the basis of observations if we deal with

  14. A new parameter space study of cosmological microlensing

    NASA Astrophysics Data System (ADS)

    Vernardos, G.; Fluke, C. J.

    2013-09-01

    Cosmological gravitational microlensing is a useful technique for understanding the structure of the inner parts of a quasar, especially the accretion disc and the central supermassive black hole. So far, most of the cosmological microlensing studies have focused on single objects from ˜90 currently known lensed quasars. However, present and planned all-sky surveys are expected to discover thousands of new lensed systems. Using a graphics processing unit (GPU) accelerated ray-shooting code, we have generated 2550 magnification maps uniformly across the convergence (κ) and shear (γ) parameter space of interest to microlensing. We examine the effect of random realizations of the microlens positions on map properties such as the magnification probability distribution (MPD). It is shown that for most of the parameter space a single map is representative of an average behaviour. All of the simulations have been carried out on the GPU Supercomputer for Theoretical Astrophysics Research.

  15. INTEGRAL upper limits on gamma-ray emission associated with the gravitational wave event GW150914

    NASA Astrophysics Data System (ADS)

    Savchenko, V.; Ferrigno, C.; Mereghetti, S.; Natalucci, L.; Kuulkers, E.

    2016-06-01

    Using observations of the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL), we put tight upper limits on the gamma-ray and hard X-ray prompt emission associated with the gravitational wave event GW150914, discovered by the LIGO/Virgo collaboration. The omni-directional view of the INTEGRAL/SPI-ACS has allowed us to constrain the fraction of energy emitted in the hard X-ray electromagnetic component for the full high-probability sky region of LIGO/Virgo trigger. Our upper limits on the hard X-ray fluence at the time of the event range from F_{γ}=2 × 10^{-8} erg cm^{-2} to F_{γ}=10^{-6} erg cm^{-2} in the 75 keV - 2 MeV energy range for typical spectral models. Our results constrain the ratio of the energy promptly released in gamma-rays in the direction of the observer to the gravitational wave energy E_γ/E_{GW}<10^{-6}. We discuss the implication of gamma-ray limits on the characteristics of the gravitational wave source, based on the available predictions for prompt electromagnetic emission. This work has been possible thanks to a Memorandum of Understanding with the LIGO-Virgo scientific collaboration and is presented on behalf of a larger collaboration.

  16. First Searches for Optical Counterparts to Gravitational-Wave Candidate Events

    NASA Technical Reports Server (NTRS)

    Aasi, J.; Abadie, J.; Abbott, B. P.; Abbott, R.; Abbott, T.; Abernathy, M. R.; Accadia, T.; Acernese, F.; Adams, C.; Adams, T.; Adhikari, R. X.; Affeldt, C.; Agathos, M.; Aggarwal, N.; Aguiar, O. D.; Ajith, P.; Allen, B.; Allocca, A.; Amador Ceron, E.; Blackburn, L.; Camp, J. B.; Gehrels, N.; Graff, P. B.; Kanner, J. B.; Cenko, S. B.

    2014-01-01

    During the Laser Interferometer Gravitational-wave Observatory and Virgo joint science runs in 2009-2010, gravitational wave (GW) data from three interferometer detectors were analyzed within minutes to select GW candidate events and infer their apparent sky positions. Target coordinates were transmitted to several telescopes for follow-up observations aimed at the detection of an associated optical transient. Images were obtained for eight such GW candidates. We present the methods used to analyze the image data as well as the transient search results. No optical transient was identified with a convincing association with any of these candidates, and none of the GW triggers showed strong evidence for being astrophysical in nature. We compare the sensitivities of these observations to several model light curves from possible sources of interest, and discuss prospects for future joint GW-optical observations of this type.

  17. First Searches for Optical Counterparts to Gravitational-wave Candidate Events

    NASA Astrophysics Data System (ADS)

    Aasi, J.; Abadie, J.; Abbott, B. P.; Abbott, R.; Abbott, T.; Abernathy, M. R.; Accadia, T.; Acernese, F.; Adams, C.; Adams, T.; Adhikari, R. X.; Affeldt, C.; Agathos, M.; Aggarwal, N.; Aguiar, O. D.; Ajith, P.; Allen, B.; Allocca, A.; Amador Ceron, E.; Amariutei, D.; Anderson, R. A.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C.; Areeda, J.; Ast, S.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Austin, L.; Aylott, B. E.; Babak, S.; Baker, P. T.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barker, D.; Barnum, S. H.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barton, M. A.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J.; Bauchrowitz, J.; Bauer, Th. S.; Bebronne, M.; Behnke, B.; Bejger, M.; Beker, M. G.; Bell, A. S.; Bell, C.; Belopolski, I.; Bergmann, G.; Berliner, J. M.; Bertolini, A.; Bessis, D.; Betzwieser, J.; Beyersdorf, P. T.; Bhadbhade, T.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Bitossi, M.; Bizouard, M. A.; Black, E.; Blackburn, J. K.; Blackburn, L.; Blair, D.; Blom, M.; Bock, O.; Bodiya, T. P.; Boer, M.; Bogan, C.; Bond, C.; Bondu, F.; Bonelli, L.; Bonnand, R.; Bork, R.; Born, M.; Bose, S.; Bosi, L.; Bowers, J.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brannen, C. A.; Brau, J. E.; Breyer, J.; Briant, T.; Bridges, D. O.; Brillet, A.; Brinkmann, M.; Brisson, V.; Britzger, M.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brückner, F.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Calderón Bustillo, J.; Calloni, E.; Camp, J. B.; Campsie, P.; Cannon, K. C.; Canuel, B.; Cao, J.; Capano, C. D.; Carbognani, F.; Carbone, L.; Caride, S.; Castiglia, A.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C.; Cesarini, E.; Chakraborty, R.; Chalermsongsak, T.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Chen, X.; Chen, Y.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Chow, J.; Christensen, N.; Chu, Q.; Chua, S. S. Y.; Chung, S.; Ciani, G.; Clara, F.; Clark, D. E.; Clark, J. A.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Colombini, M.; Constancio, M., Jr.; Conte, A.; Conte, R.; Cook, D.; Corbitt, T. R.; Cordier, M.; Cornish, N.; Corsi, A.; Costa, C. A.; Coughlin, M. W.; Coulon, J.-P.; Countryman, S.; Couvares, P.; Coward, D. M.; Cowart, M.; Coyne, D. C.; Craig, K.; Creighton, J. D. E.; Creighton, T. D.; Crowder, S. G.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dahl, K.; Dal Canton, T.; Damjanic, M.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dattilo, V.; Daudert, B.; Daveloza, H.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; Dayanga, T.; De Rosa, R.; Debreczeni, G.; Degallaix, J.; Del Pozzo, W.; Deleeuw, E.; Deléglise, S.; Denker, T.; Dereli, H.; Dergachev, V.; DeRosa, R.; DeSalvo, R.; Dhurandhar, S.; Di Fiore, L.; Di Lieto, A.; Di Palma, I.; Di Virgilio, A.; Díaz, M.; Dietz, A.; Dmitry, K.; Donovan, F.; Dooley, K. L.; Doravari, S.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Dumas, J.-C.; Dwyer, S.; Eberle, T.; Edwards, M.; Effler, A.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Endrőczi, G.; Essick, R.; Etzel, T.; Evans, K.; Evans, M.; Evans, T.; Factourovich, M.; Fafone, V.; Fairhurst, S.; Fang, Q.; Farr, B.; Farr, W.; Favata, M.; Fazi, D.; Fehrmann, H.; Feldbaum, D.; Ferrante, I.; Ferrini, F.; Fidecaro, F.; Finn, L. S.; Fiori, I.; Fisher, R.; Flaminio, R.; Foley, E.; Foley, S.; Forsi, E.; Forte, L. A.; Fotopoulos, N.; Fournier, J.-D.; Franco, S.; Frasca, S.; Frasconi, F.; Frede, M.; Frei, M.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fujimoto, M.-K.; Fulda, P.; Fyffe, M.; Gair, J.; Gammaitoni, L.; Garcia, J.; Garufi, F.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; Gergely, L.; Ghosh, S.; Giaime, J. A.; Giampanis, S.; Giardina, K. D.; Giazotto, A.; Gil-Casanova, S.; Gill, C.; Gleason, J.; Goetz, E.; Goetz, R.; Gondan, L.; González, G.; Gordon, N.; Gorodetsky, M. L.; Gossan, S.; Goßler, S.; Gouaty, R.; Graef, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Griffo, C.; Grote, H.; Grover, K.; Grunewald, S.; Guidi, G. M.; Guido, C.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Hall, B.; Hall, E.; Hammer, D.; Hammond, G.; Hanke, M.; Hanks, J.; Hanna, C.; Hanson, J.; Harms, J.; Harry, G. M.; Harry, I. W.; Harstad, E. D.; Hartman, M. T.; Haughian, K.; Hayama, K.; Heefner, J.; Heidmann, A.; Heintze, M.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Holt, K.; Holtrop, M.; Hong, T.; Hooper, S.; Horrom, T.; Hosken, D. J.; Hough, J.; Howell, E. J.; Hu, Y.; Hua, Z.; Huang, V.; Huerta, E. A.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh, M.; Huynh-Dinh, T.; Iafrate, J.; Ingram, D. R.; Inta, R.; Isogai, T.; Ivanov, A.; Iyer, B. R.; Izumi, K.; Jacobson, M.; James, E.; Jang, H.; Jang, Y. J.; Jaranowski, P.; Jiménez-Forteza, F.; Johnson, W. W.; Jones, D.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; K, Haris; Kalmus, P.; Kalogera, V.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Kasprzack, M.; Kasturi, R.; Katsavounidis, E.; Katzman, W.; Kaufer, H.; Kaufman, K.; Kawabe, K.; Kawamura, S.; Kawazoe, F.; Kéfélian, F.; Keitel, D.; Kelley, D. B.; Kells, W.; Keppel, D. G.; Khalaidovski, A.; Khalili, F. Y.; Khazanov, E. A.; Kim, B. K.; Kim, C.; Kim, K.; Kim, N.; Kim, W.; Kim, Y.-M.; King, E. J.; King, P. J.; Kinzel, D. L.; Kissel, J. S.; Klimenko, S.; Kline, J.; Koehlenbeck, S.; Kokeyama, K.; Kondrashov, V.; Koranda, S.; Korth, W. Z.; Kowalska, I.; Kozak, D.; Kremin, A.; Kringel, V.; Krishnan, B.; Królak, A.; Kucharczyk, C.; Kudla, S.; Kuehn, G.; Kumar, A.; Kumar, P.; Kumar, R.; Kurdyumov, R.; Kwee, P.; Landry, M.; Lantz, B.; Larson, S.; Lasky, P. D.; Lawrie, C.; Lazzarini, A.; Le Roux, A.; Leaci, P.; Lebigot, E. O.; Lee, C.-H.; Lee, H. K.; Lee, H. M.; Lee, J.; Lee, J.; Leonardi, M.; Leong, J. R.; Leroy, N.; Letendre, N.; Levine, B.; Lewis, J. B.; Lhuillier, V.; Li, T. G. F.; Lin, A. C.; Littenberg, T. B.; Litvine, V.; Liu, F.; Liu, H.; Liu, Y.; Liu, Z.; Lloyd, D.; Lockerbie, N. A.; Lockett, V.; Lodhia, D.; Loew, K.; Logue, J.; Lombardi, A. L.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J.; Luan, J.; Lubinski, M. J.; Lück, H.; Lundgren, A. P.; Macarthur, J.; Macdonald, E.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magana-Sandoval, F.; Mageswaran, M.; Mailand, K.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man, N.; Manca, G. M.; Mandel, I.; Mandic, V.; Mangano, V.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markosyan, A.; Maros, E.; Marque, J.; Martelli, F.; Martin, I. W.; Martin, R. M.; Martinelli, L.; Martynov, D.; Marx, J. N.; Mason, K.; Masserot, A.; Massinger, T. J.; Matichard, F.; Matone, L.; Matzner, R. A.; Mavalvala, N.; May, G.; Mazumder, N.; Mazzolo, G.; McCarthy, R.; McClelland, D. E.; McGuire, S. C.; McIntyre, G.; McIver, J.; Meacher, D.; Meadors, G. D.; Mehmet, M.; Meidam, J.; Meier, T.; Melatos, A.; Mendell, G.; Mercer, R. A.; Meshkov, S.; Messenger, C.; Meyer, M. S.; Miao, H.; Michel, C.; Mikhailov, E. E.; Milano, L.; Miller, J.; Minenkov, Y.; Mingarelli, C. M. F.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moe, B.; Mohan, M.; Mohapatra, S. R. P.; Mokler, F.; Moraru, D.; Moreno, G.; Morgado, N.; Mori, T.; Morriss, S. R.; Mossavi, K.; Mours, B.; Mow-Lowry, C. M.; Mueller, C. L.; Mueller, G.; Mukherjee, S.; Mullavey, A.; Munch, J.; Murphy, D.; Murray, P. G.; Mytidis, A.; Nagy, M. F.; Nanda Kumar, D.; Nardecchia, I.; Nash, T.; Naticchioni, L.; Nayak, R.; Necula, V.; Neri, I.; Newton, G.; Nguyen, T.; Nishida, E.; Nishizawa, A.; Nitz, A.; Nocera, F.; Nolting, D.; Normandin, M. E.; Nuttall, L. K.; Ochsner, E.; O'Dell, J.; Oelker, E.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Oppermann, P.; O'Reilly, B.; Ortega Larcher, W.; O'Shaughnessy, R.; Osthelder, C.; Ottaway, D. J.; Ottens, R. S.; Ou, J.; Overmier, H.; Owen, B. J.; Padilla, C.; Pai, A.; Palomba, C.; Pan, Y.; Pankow, C.; Paoletti, F.; Paoletti, R.; Papa, M. A.; Paris, H.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Pedraza, M.; Peiris, P.; Penn, S.; Perreca, A.; Phelps, M.; Pichot, M.; Pickenpack, M.; Piergiovanni, F.; Pierro, V.; Pinard, L.; Pindor, B.; Pinto, I. M.; Pitkin, M.; Poeld, J.; Poggiani, R.; Poole, V.; Poux, C.; Predoi, V.; Prestegard, T.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prix, R.; Prodi, G. A.; Prokhorov, L.; Puncken, O.; Punturo, M.; Puppo, P.; Quetschke, V.; Quintero, E.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Rácz, I.; Radkins, H.; Raffai, P.; Raja, S.; Rajalakshmi, G.; Rakhmanov, M.; Ramet, C.; Rapagnani, P.; Raymond, V.; Re, V.; Reed, C. M.; Reed, T.; Regimbau, T.; Reid, S.; Reitze, D. H.; Ricci, F.; Riesen, R.; Riles, K.; Robertson, N. A.; Robinet, F.; Rocchi, A.; Roddy, S.; Rodriguez, C.; Rodruck, M.; Roever, C.; Rolland, L.; Rollins, J. G.; Romano, J. D.; Romano, R.; Romanov, G.; Romie, J. H.; Rosińska, D.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Ryan, K.; Salemi, F.; Sammut, L.; Sandberg, V.; Sanders, J.; Sannibale, V.; Santiago-Prieto, I.; Saracco, E.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Savage, R.; Schilling, R.; Schnabel, R.; Schofield, R. M. S.; Schreiber, E.; Schuette, D.; Schulz, B.; Schutz, B. F.; Schwinberg, P.; Scott, J.; Scott, S. M.; Seifert, F.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sergeev, A.; Shaddock, D.; Shah, S.; Shahriar, M. S.; Shaltev, M.; Shapiro, B.; Shawhan, P.; Shoemaker, D. H.; Sidery, T. L.; Siellez, K.; Siemens, X.; Sigg, D.; Simakov, D.; Singer, A.; Singer, L.; Sintes, A. M.; Skelton, G. R.; Slagmolen, B. J. J.; Slutsky, J.; Smith, J. R.; Smith, M. R.; Smith, R. J. E.; Smith-Lefebvre, N. D.; Soden, K.; Son, E. J.; Sorazu, B.; Souradeep, T.; Sperandio, L.; Staley, A.; Steinert, E.; Steinlechner, J.; Steinlechner, S.; Steplewski, S.; Stevens, D.; Stochino, A.; Stone, R.; Strain, K. A.; Strigin, S.; Stroeer, A. S.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Susmithan, S.; Sutton, P. J.; Swinkels, B.; Szeifert, G.; Tacca, M.; Talukder, D.; Tang, L.; Tanner, D. B.; Tarabrin, S. P.; Taylor, R.; ter Braack, A. P. M.; Thirugnanasambandam, M. P.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Tiwari, V.; Tokmakov, K. V.; Tomlinson, C.; Toncelli, A.; Tonelli, M.; Torre, O.; Torres, C. V.; Torrie, C. I.; Travasso, F.; Traylor, G.; Tse, M.; Ugolini, D.; Unnikrishnan, C. S.; Vahlbruch, H.; Vajente, G.; Vallisneri, M.; van den Brand, J. F. J.; Van Den Broeck, C.; van der Putten, S.; van der Sluys, M. V.; van Heijningen, J.; van Veggel, A. A.; Vass, S.; Vasúth, M.; Vaulin, R.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Verkindt, D.; Verma, S.; Vetrano, F.; Viceré, A.; Vincent-Finley, R.; Vinet, J.-Y.; Vitale, S.; Vlcek, B.; Vo, T.; Vocca, H.; Vorvick, C.; Vousden, W. D.; Vrinceanu, D.; Vyachanin, S. P.; Wade, A.; Wade, L.; Wade, M.; Waldman, S. J.; Walker, M.; Wallace, L.; Wan, Y.; Wang, J.; Wang, M.; Wang, X.; Wanner, A.; Ward, R. L.; Was, M.; Weaver, B.; Wei, L.-W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Welborn, T.; Wen, L.; Wessels, P.; West, M.; Westphal, T.; Wette, K.; Whelan, J. T.; Whitcomb, S. E.; White, D. J.; Whiting, B. F.; Wibowo, S.; Wiesner, K.; Wilkinson, C.; Williams, L.; Williams, R.; Williams, T.; Willis, J. L.; Willke, B.; Wimmer, M.; Winkelmann, L.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Worden, J.; Yablon, J.; Yakushin, I.; Yamamoto, H.; Yancey, C. C.; Yang, H.; Yeaton-Massey, D.; Yoshida, S.; Yum, H.; Yvert, M.; Zadrożny, A.; Zanolin, M.; Zendri, J.-P.; Zhang, F.; Zhang, L.; Zhao, C.; Zhu, H.; Zhu, X. J.; Zotov, N.; Zucker, M. E.; Zweizig, J.; LIGO Scientific Collaboration; Virgo Collaboration; Akerlof, C.; Baltay, C.; Bloom, J. S.; Cao, Y.; Cenko, S. B.; Ćwiek, A.; Ćwiok, M.; Dhillon, V.; Fox, D. B.; Gal-Yam, A.; Kasliwal, M. M.; Klotz, A.; Laas-Bourez, M.; Laher, R. R.; Law, N. M.; Majcher, A.; Małek, K.; Mankiewicz, L.; Nawrocki, K.; Nissanke, S.; Nugent, P. E.; Ofek, E. O.; Opiela, R.; Piotrowski, L.; Poznanski, D.; Rabinowitz, D.; Rapoport, S.; Richards, J. W.; Schmidt, B.; Siudek, M.; Sokołowski, M.; Steele, I. A.; Sullivan, M.; Żarnecki, A. F.; Zheng, W.

    2014-03-01

    During the Laser Interferometer Gravitational-wave Observatory and Virgo joint science runs in 2009-2010, gravitational wave (GW) data from three interferometer detectors were analyzed within minutes to select GW candidate events and infer their apparent sky positions. Target coordinates were transmitted to several telescopes for follow-up observations aimed at the detection of an associated optical transient. Images were obtained for eight such GW candidates. We present the methods used to analyze the image data as well as the transient search results. No optical transient was identified with a convincing association with any of these candidates, and none of the GW triggers showed strong evidence for being astrophysical in nature. We compare the sensitivities of these observations to several model light curves from possible sources of interest, and discuss prospects for future joint GW-optical observations of this type.

  18. Observation of the microlensing toward the Andromeda galaxy

    NASA Astrophysics Data System (ADS)

    Shulga, V. V.; Sazhin, M. V.; Gorbatko, N. P.

    Observation of the Andromeda galaxy (M31) stars microlensed by dark bodies in the halo of our Galaxy is considered. Observations toward the Andromeda galaxy significantly increase the probability to reveal microlensing effects in comparison with MACHO and EROS procedures for observations of LMC and SMC. This is due to: greater amount of background stars (stars from M31) for which it is possible to observe the microlensing effect; greater distance to M31 (690 kps). This fact allows us to consider ALL the dark bodies in our Galaxy whereas LMC and SMC are actually situated INSIDE (55 kps) the halo of the Galaxy. The probability of microlensing effects, their characteristic times and the maximum factor of M31 star brightness amplification are estimated for different models. If the mass of a dark body in the halo of our Galaxy is of the order of 1M, it is possible to detect 5-6 microlensing events in one year. When the maximum factor of brightness amplification is 10, the characteristic time of the event is 7-10 days. If masses of dark bodies is of the order of 10-3 M it is possible detect 175-200 events per year and duration of these events is 0.2-0.3 days provided that the maximum amplification factor is 10. Procedures of real astronomical observations to search for the microlensing effect are discussed in detail. Information about observational series obtained is given. This series was obtained with the telescope AFR-1 in observatory at Mount Majdanak in 1990-1992 (total duration of the series is about 1.5 years). Processing of long observational series is being performed for the purpose of revealing microlensing effect. Preliminary results of the processing are presented.

  19. Search for Neutrinos in Super-Kamiokande Associated with Gravitational-wave Events GW150914 and GW151226

    NASA Astrophysics Data System (ADS)

    Abe, K.; Haga, K.; Hayato, Y.; Ikeda, M.; Iyogi, K.; Kameda, J.; Kishimoto, Y.; Miura, M.; Moriyama, S.; Nakahata, M.; Nakajima, T.; Nakano, Y.; Nakayama, S.; Orii, A.; Sekiya, H.; Shiozawa, M.; Takeda, A.; Tanaka, H.; Tasaka, S.; Tomura, T.; Akutsu, R.; Kajita, T.; Kaneyuki, K.; Nishimura, Y.; Richard, E.; Okumura, K.; Labarga, L.; Fernandez, P.; Blaszczyk, F. d. M.; Gustafson, J.; Kachulis, C.; Kearns, E.; Raaf, J. L.; Stone, J. L.; Sulak, L. R.; Berkman, S.; Nantais, C. M.; Tobayama, S.; Goldhaber, M.; Kropp, W. R.; Mine, S.; Weatherly, P.; Smy, M. B.; Sobel, H. W.; Takhistov, V.; Ganezer, K. S.; Hartfiel, B. L.; Hill, J.; Hong, N.; Kim, J. Y.; Lim, I. T.; Park, R. G.; Himmel, A.; Li, Z.; O'Sullivan, E.; Scholberg, K.; Walter, C. W.; Ishizuka, T.; Nakamura, T.; Jang, J. S.; Choi, K.; Learned, J. G.; Matsuno, S.; Smith, S. N.; Friend, M.; Hasegawa, T.; Ishida, T.; Ishii, T.; Kobayashi, T.; Nakadaira, T.; Nakamura, K.; Oyama, Y.; Sakashita, K.; Sekiguchi, T.; Tsukamoto, T.; Suzuki, A. T.; Takeuchi, Y.; Yano, T.; Cao, S. V.; Hiraki, T.; Hirota, S.; Huang, K.; Jiang, M.; Minamino, A.; Nakaya, T.; Patel, N. D.; Wendell, R. A.; Suzuki, K.; Fukuda, Y.; Itow, Y.; Suzuki, T.; Mijakowski, P.; Frankiewicz, K.; Hignight, J.; Imber, J.; Jung, C. K.; Li, X.; Palomino, J. L.; Santucci, G.; Wilking, M. J.; Yanagisawa, C.; Fukuda, D.; Ishino, H.; Kayano, T.; Kibayashi, A.; Koshio, Y.; Mori, T.; Sakuda, M.; Xu, C.; Kuno, Y.; Tacik, R.; Kim, S. B.; Okazawa, H.; Choi, Y.; Nishijima, K.; Koshiba, M.; Totsuka, Y.; Suda, Y.; Yokoyama, M.; Bronner, C.; Calland, R. G.; Hartz, M.; Martens, K.; Marti, Ll.; Suzuki, Y.; Vagins, M. R.; Martin, J. F.; Tanaka, H. A.; Konaka, A.; Chen, S.; Wan, L.; Zhang, Y.; Wilkes, R. J.; Super-Kamiokande Collaboration

    2016-10-01

    We report the results from a search in Super-Kamiokande for neutrino signals coincident with the first detected gravitational-wave events, GW150914 and GW151226, as well as LVT151012, using a neutrino energy range from 3.5 MeV to 100 PeV. We searched for coincident neutrino events within a time window of ±500 s around the gravitational-wave detection time. Four neutrino candidates are found for GW150914, and no candidates are found for GW151226. The remaining neutrino candidates are consistent with the expected background events. We calculated the 90% confidence level upper limits on the combined neutrino fluence for both gravitational-wave events, which depends on event energy and topologies. Considering the upward-going muon data set (1.6 GeV-100 PeV), the neutrino fluence limit for each gravitational-wave event is 14-37 (19-50) cm-2 for muon neutrinos (muon antineutrinos), depending on the zenith angle of the event. In the other data sets, the combined fluence limits for both gravitational-wave events range from 2.4 × 104 to 7.0 × 109 cm-2.

  20. The Spitzer Microlensing Program as a Probe for Globular Cluster Planets: Analysis of OGLE-2015-BLG-0448

    NASA Astrophysics Data System (ADS)

    Poleski, Radosław; Zhu, Wei; Christie, Grant W.; Udalski, Andrzej; Gould, Andrew; Bachelet, Etienne; Skottfelt, Jesper; Calchi Novati, Sebastiano; Szymański, M. K.; Soszyński, I.; Pietrzyński, G.; Wyrzykowski, Ł.; Ulaczyk, K.; Pietrukowicz, P.; Kozłowski, Szymon; Skowron, J.; Mróz, P.; Pawlak, M.; OGLE Group; Beichman, C.; Bryden, G.; Carey, S.; Fausnaugh, M.; Gaudi, B. S.; Henderson, C. B.; Pogge, R. W.; Shvartzvald, Y.; Wibking, B.; Yee, J. C.; Spitzer Team; Beatty, T. G.; Eastman, J. D.; Drummond, J.; Friedmann, M.; Henderson, M.; Johnson, J. A.; Kaspi, S.; Maoz, D.; McCormick, J.; McCrady, N.; Natusch, T.; Ngan, H.; Porritt, I.; Relles, H. M.; Sliski, D. H.; Tan, T.-G.; Wittenmyer, R. A.; Wright, J. T.; μFUN Group; Street, R. A.; Tsapras, Y.; Bramich, D. M.; Horne, K.; Snodgrass, C.; Steele, I. A.; Menzies, J.; Figuera Jaimes, R.; Wambsganss, J.; Schmidt, R.; Cassan, A.; Ranc, C.; Mao, S.; project, RoboNet; Bozza, V.; Dominik, M.; Hundertmark, M. P. G.; Jørgensen, U. G.; Andersen, M. I.; Burgdorf, M. J.; Ciceri, S.; D'Ago, G.; Evans, D. F.; Gu, S.-H.; Hinse, T. C.; Kains, N.; Kerins, E.; Korhonen, H.; Kuffmeier, M.; Mancini, L.; Popovas, A.; Rabus, M.; Rahvar, S.; Rasmussen, R. T.; Scarpetta, G.; Southworth, J.; Surdej, J.; Unda-Sanzana, E.; Verma, P.; von Essen, C.; Wang, Y.-B.; Wertz, O.; MiNDSTEp Group

    2016-05-01

    The microlensing event OGLE-2015-BLG-0448 was observed by Spitzer and lay within the tidal radius of the globular cluster NGC 6558. The event had moderate magnification and was intensively observed, hence it had the potential to probe the distribution of planets in globular clusters. We measure the proper motion of NGC 6558 ({{\\boldsymbol{μ }}}{cl}(N,E)=(+0.36+/- 0.10,+1.42+/- 0.10) {{mas}} {{{yr}}}-1) as well as the source and show that the lens is not a cluster member. Even though this particular event does not probe the distribution of planets in globular clusters, other potential cluster lens events can be verified using our methodology. Additionally, we find that microlens parallax measured using Optical Gravitational Lens Experiment (OGLE) photometry is consistent with the value found based on the light curve displacement between the Earth and Spitzer.

  1. MEASURING MICROLENSING USING SPECTRA OF MULTIPLY LENSED QUASARS

    SciTech Connect

    Motta, V.; Mediavilla, E.; Munoz, J. A. E-mail: emg@iac.es E-mail: jmunoz@uv.es

    2012-08-10

    We report on a program of spectroscopic observations of gravitationally lensed QSOs with multiple images. We seek to establish whether microlensing is occurring in each QSO image using only single-epoch observations. We calculate flux ratios for the cores of emission lines in image pairs to set a baseline for no microlensing. The offset of the continuum flux ratios relative to this baseline yields the microlensing magnification free from extinction, as extinction affects the continuum and the lines equally. When we find chromatic microlensing, we attempt to constrain the size of the QSO accretion disk. SDSSJ1004+4112 and HE1104-1805 show chromatic microlensing with amplitudes 0.2 < |{Delta}m| < 0.6 and 0.2 < |{Delta}m| < 0.4 mag, respectively. Modeling the accretion disk with a Gaussian source (I{proportional_to}exp (- R{sup 2}/2r{sup 2}{sub s})) of size r{sub s} {proportional_to}{lambda}{sup p} and using magnification maps to simulate microlensing, we find r{sub s} ({lambda}3363) = 7 {+-} 3 lt-day(18.1 {+-} 7.8 Multiplication-Sign 10{sup 15} cm) and p = 1.1 {+-} 0.4 for SDSS1004+4112, and r{sub s} ({lambda}3363) = 6 {+-} 2 lt-day(15.5 {+-} 5.2 Multiplication-Sign 10{sup 15} cm) and p = 0.7 {+-} 0.1 for HE1104-1805. For SDSSJ1029+2623, we find strong chromaticity of {approx}0.4 mag in the continuum flux ratio, which probably arises from microlensing, although not all the available data fit within this explanation. For Q0957+561, we measure B - A magnitude differences of 0.4 mag, much greater than the {approx}0.05 mag amplitude usually inferred from light-curve variability. It may substantially modify the current interpretations of microlensing in this system, likely favoring the hypothesis of smaller sources and/or larger microdeflectors. For HS0818+1227, our data yield possible evidence of microlensing.

  2. Astrophysical applications of quasar microlensing

    NASA Astrophysics Data System (ADS)

    Mediavilla, E.; Jiménez-Vicente, J.; Muñoz, J. A.

    2017-03-01

    We present a quick overview of several examples that illustrate the application of quasar microlensing to various problems of great interest in Astrophysics and Cosmology. We start introducing the main tool for simulating quasar microlensing, the magnification map. Then, the flux magnification statistics obtained from the magnification maps is used to study the quasar accretion disk size and temperature profile with results that challenge the thin disk model. The microlensing flux magnification statistics is also useful to determine the radial slope of the dark matter distribution in lens galaxies. The extremely high microlensing magnification at caustics allows to scan with horizon scale accuracy the quasar accretion disk, spiraling around the central super massive black hole, resolving the innermost stable circular orbit. Finally, transverse peculiar velocities of the lens galaxies, of great interest in cosmology, can be inferred either counting peaks in the microlensing light curves or directly from astrometric measurements of the highly magnified relative motions between lensed quasar images.

  3. Exoplanet Demographics with Microlensing Surveys

    NASA Astrophysics Data System (ADS)

    Gaudi, B.

    2014-04-01

    Because of its unique sensitivity to low-mass, long-period, and free-floating planets, microlensing is an essential complement to our arsenal of planet detection methods. I motivate microlensing surveys for exoplanets, and in particular describe how they can be used to test models for planet formation, as well as inform our understanding of the frequency and potential habitability of low-mass planets located in the habitable zones of their host stars. I review results from current microlensing surveys, and then discuss expectations for next-generation experiments. I explain why a space-based mission is necessary to realize the full potential of microlensing. When combined with the results from complementary surveys such as Kepler, a space-based microlensing survey will yield a nearly complete picture of the demographics of planetary systems throughout the Galaxy.

  4. Event Rate for LISA Gravitational Wave Signals from Black Hole-Massive Black Hole Coalescences

    NASA Technical Reports Server (NTRS)

    Bender, Peter L.

    2002-01-01

    Earlier work under a previous grant had been mainly on investigating the event rate for coalescences of white dwarfs or neutron stars with massive black holes (MBHs) in galactic nuclei. Under the new grant, two studies were undertaken. One was an approximate extension of the earlier study to stellar mass black holes as the lighter object, with masses in the range of roughly 3 to 20 solar mass rather than about 1 solar mass. The other was an improved estimate of the confusion noise due to galactic binaries against which the signals from BH-MBH coalescences would have to be detected. In the earlier work, the mass of the white dwarfs (WDs) and neutron stars (NSs) was assumed to be about the same as that of the evolved stars in the density cusp around the galactic center MBH. However, with the BH mass being substantially larger, the sinking down of pHs toward the center (mass segregation) became important, and was included in the model. A single representative mass of 7 solar mass was used. The other main difference involved what happened after the compact object got scattered in close enough to the MBH to start losing appreciable energy and angular momentum by gravitational radiation. For WDs or NSs, it had been found in most cases that the object would be perturbed considerably by other stars in the cusp before much energy had been lost. Thus the angular momentum would either increase enough so that gravitational radiation would be cut off, or would decrease enough so that the WD or NS would plunge into the MBH in just a few revolutions. The latter event would mean that the signal-to noise ratio would not have time to build up, and the event would not be detectable. The ratio of gradual energy loss events to plunges was found to be roughly one to a few percent, and thus substantially decreased the expected rate of detectable events.

  5. Effect of Binary Source Companions on the Microlensing Optical Depth Determination toward the Galactic Bulge Field

    NASA Astrophysics Data System (ADS)

    Han, Cheongho

    2005-11-01

    Currently, gravitational microlensing survey experiments toward the Galactic bulge field use two different methods of minimizing the blending effect for the accurate determination of the optical depth τ. One is measuring τ based on clump giant (CG) source stars, and the other is using ``difference image analysis'' (DIA) photometry to measure the unblended source flux variation. Despite the expectation that the two estimates should be the same assuming that blending is properly considered, the estimates based on CG stars systematically fall below the DIA results based on all events with source stars down to the detection limit. Prompted by the gap, we investigate the previously unconsidered effect of companion-associated events on τ determination. Although the image of a companion is blended with that of its primary star and thus not resolved, the event associated with the companion can be detected if the companion flux is highly magnified. Therefore, companions work effectively as source stars to microlensing, and thus the neglect of them in the source star count could result in a wrong τ estimation. By carrying out simulations based on the assumption that companions follow the same luminosity function as primary stars, we estimate that the contribution of the companion-associated events to the total event rate is ~5fbi% for current surveys and can reach up to ~6fbi% for future surveys monitoring fainter stars, where fbi is the binary frequency. Therefore, we conclude that the companion-associated events comprise a nonnegligible fraction of all events. However, their contribution to the optical depth is not large enough to explain the systematic difference between the optical depth estimates based on the two different methods.

  6. Primordial Black Hole Scenario for the Gravitational-Wave Event GW150914.

    PubMed

    Sasaki, Misao; Suyama, Teruaki; Tanaka, Takahiro; Yokoyama, Shuichiro

    2016-08-05

    We point out that the gravitational-wave event GW150914 observed by the LIGO detectors can be explained by the coalescence of primordial black holes (PBHs). It is found that the expected PBH merger rate would exceed the rate estimated by the LIGO Scientific Collaboration and the Virgo Collaboration if PBHs were the dominant component of dark matter, while it can be made compatible if PBHs constitute a fraction of dark matter. Intriguingly, the abundance of PBHs required to explain the suggested lower bound on the event rate, >2  events  Gpc^{-3} yr^{-1}, roughly coincides with the existing upper limit set by the nondetection of the cosmic microwave background spectral distortion. This implies that the proposed PBH scenario may be tested in the not-too-distant future.

  7. Optimal survey strategies and predicted planet yields for the Korean microlensing telescope network

    SciTech Connect

    Henderson, Calen B.; Gaudi, B. Scott; Skowron, Jan; Penny, Matthew T.; Gould, Andrew P.; Han, Cheongho; Nataf, David

    2014-10-10

    The Korean Microlensing Telescope Network (KMTNet) will consist of three 1.6 m telescopes each with a 4 deg{sup 2} field of view (FoV) and will be dedicated to monitoring the Galactic Bulge to detect exoplanets via gravitational microlensing. KMTNet's combination of aperture size, FoV, cadence, and longitudinal coverage will provide a unique opportunity to probe exoplanet demographics in an unbiased way. Here we present simulations that optimize the observing strategy for and predict the planetary yields of KMTNet. We find preferences for four target fields located in the central Bulge and an exposure time of t {sub exp} = 120 s, leading to the detection of ∼2200 microlensing events per year. We estimate the planet detection rates for planets with mass and separation across the ranges 0.1 ≤ M{sub p} /M {sub ⊕} ≤ 1000 and 0.4 ≤ a/AU ≤ 16, respectively. Normalizing these rates to the cool-planet mass function of Cassan et al., we predict KMTNet will be approximately uniformly sensitive to planets with mass 5 ≤ M{sub p} /M {sub ⊕} ≤ 1000 and will detect ∼20 planets per year per dex in mass across that range. For lower-mass planets with mass 0.1 ≤ M{sub p} /M {sub ⊕} < 5, we predict KMTNet will detect ∼10 planets per year. We also compute the yields KMTNet will obtain for free-floating planets (FFPs) and predict KMTNet will detect ∼1 Earth-mass FFP per year, assuming an underlying population of one such planet per star in the Galaxy. Lastly, we investigate the dependence of these detection rates on the number of observatories, the photometric precision limit, and optimistic assumptions regarding seeing, throughput, and flux measurement uncertainties.

  8. Astrometric microlensing and rotation of extragalactic reference frame

    NASA Astrophysics Data System (ADS)

    Zhdanov, V. I.; Alexandrov, A. N.; Fedorova, E. V.

    Gravitational field of foreground stars of the Galaxy causes additional motion of images of extragalactic sources. We estimate characteristics of stochastic and average motions of these images. The probability distribution for the image motions and their changes is obtained for general spatial density of microlenses. We show that collective motion of stars induces small nonzero dragging velocity of the reference frame. The results obtained are compared to the other relativistic effects in optical satellite-oriented reference frame.

  9. Creep events and creep noise in gravitational-wave interferometers: Basic formalism and stationary limit

    NASA Astrophysics Data System (ADS)

    Levin, Yuri

    2012-12-01

    In gravitational-wave interferometers, test masses are suspended on thin fibers which experience considerable tension stress. Sudden microscopic stress release in a suspension fiber, which I call a “creep event,” would excite motion of the test mass that would be coupled to the interferometer’s readout. The random test-mass motion due to a time sequence of creep events is referred to as “creep noise.” In this paper I present an elastodynamic calculation for the test-mass motion due to a creep event. I show that within a simple suspension model, the main coupling to the optical readout occurs via a combination of a “dc” horizontal displacement of the test mass and excitation of the violin and pendulum modes, and not, as was thought previously, via lengthening of the fiber. When the creep events occur sufficiently frequently and their statistics is time independent, the creep noise can be well approximated by a stationary Gaussian random process. I derive the functional form of the creep noise spectral density in this limit, with the restrictive assumption that the creep events are statistically independent from each other.

  10. Testing LMC Microlensing Scenarios: The Discrimination Power of the SuperMACHO Microlensing Survey

    SciTech Connect

    Rest, A; Stubbs, C; Becker, A C; Miknaitis, G A; Miceli, A; Covarrubias, R; Hawley, S L; Smith, C; Suntzeff, N B; Olsen, K; Prieto, J; Hiriart, R; Welch, D L; Cook, K; Nikolaev, S; Proctor, G; Clocchiatti, A; Minniti, D; Garg, A; Challis, P; Keller, S C; Scmidt, B P

    2004-05-27

    Characterizing the nature and spatial distribution of the lensing objects that produce the observed microlensing optical depth toward the Large Magellanic Cloud (LMC) remains an open problem. They present an appraisal of the ability of the SuperMACHO Project, a next-generation microlensing survey pointed toward the LMC, to discriminate between various proposed lensing populations. they consider two scenarios: lensing by a uniform foreground screen of objects and self-lensing of LMC stars. The optical depth for ''screen-lensing'' is essentially constant across the face of the LMC; whereas, the optical depth for self-lensing shows a strong spatial dependence. they have carried out extensive simulations, based upon actual data obtained during the first year of the project, to assess the SuperMACHO survey's ability to discriminate between these two scenarios. In the simulations they predict the expected number of observed microlensing events for each of their fields by adding artificial stars to the images and estimating the spatial and temporal efficiency of detecting microlensing events using Monte-Carlo methods. They find that the event rate itself shows significant sensitivity to the choice of the LMC luminosity function shape and other parameters, limiting the conclusions which can be drawn from the absolute rate. By instead determining the differential event rate across the LMC, they can decrease the impact of these systematic uncertainties rendering the conclusions more robust. With this approach the SuperMACHO Project should be able to distinguish between the two categories of lens populations and provide important constraints on the nature of the lensing objects.

  11. A DECam Search for an Optical Counterpart to the LIGO Gravitational-wave Event GW151226

    NASA Astrophysics Data System (ADS)

    Cowperthwaite, P. S.; Berger, E.; Soares-Santos, M.; Annis, J.; Brout, D.; Brown, D. A.; Buckley-Geer, E.; Cenko, S. B.; Chen, H. Y.; Chornock, R.; Diehl, H. T.; Doctor, Z.; Drlica-Wagner, A.; Drout, M. R.; Farr, B.; Finley, D. A.; Foley, R. J.; Fong, W.; Fox, D. B.; Frieman, J.; Garcia-Bellido, J.; Gill, M. S. S.; Gruendl, R. A.; Herner, K.; Holz, D. E.; Kasen, D.; Kessler, R.; Lin, H.; Margutti, R.; Marriner, J.; Matheson, T.; Metzger, B. D.; Neilsen, E. H., Jr.; Quataert, E.; Rest, A.; Sako, M.; Scolnic, D.; Smith, N.; Sobreira, F.; Strampelli, G. M.; Villar, V. A.; Walker, A. R.; Wester, W.; Williams, P. K. G.; Yanny, B.; Abbott, T. M. C.; Abdalla, F. B.; Allam, S.; Armstrong, R.; Bechtol, K.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Burke, D. L.; Carnero Rosell, A.; Carrasco Kind, M.; Carretero, J.; Castander, F. J.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; Desai, S.; Dietrich, J. P.; Evrard, A. E.; Fausti Neto, A.; Fosalba, P.; Gerdes, D. W.; Giannantonio, T.; Goldstein, D. A.; Gruen, D.; Gutierrez, G.; Honscheid, K.; James, D. J.; Johnson, M. W. G.; Johnson, M. D.; Krause, E.; Kuehn, K.; Kuropatkin, N.; Lima, M.; Maia, M. A. G.; Marshall, J. L.; Menanteau, F.; Miquel, R.; Mohr, J. J.; Nichol, R. C.; Nord, B.; Ogando, R.; Plazas, A. A.; Reil, K.; Romer, A. K.; Sanchez, E.; Scarpine, V.; Sevilla-Noarbe, I.; Smith, R. C.; Suchyta, E.; Tarle, G.; Thomas, D.; Thomas, R. C.; Tucker, D. L.; Weller, J.; DES Collaboration

    2016-08-01

    We report the results of a Dark Energy Camera optical follow-up of the gravitational-wave (GW) event GW151226, discovered by the Advanced Laser Interferometer Gravitational-wave Observatory detectors. Our observations cover 28.8 deg2 of the localization region in the i and z bands (containing 3% of the BAYESTAR localization probability), starting 10 hr after the event was announced and spanning four epochs at 2-24 days after the GW detection. We achieve 5σ point-source limiting magnitudes of i≈ 21.7 and z≈ 21.5, with a scatter of 0.4 mag, in our difference images. Given the two-day delay, we search this area for a rapidly declining optical counterpart with ≳ 3σ significance steady decline between the first and final observations. We recover four sources that pass our selection criteria, of which three are cataloged active galactic nuclei. The fourth source is offset by 5.8 arcsec from the center of a galaxy at a distance of 187 Mpc, exhibits a rapid decline by 0.5 mag over 4 days, and has a red color of i-z≈ 0.3 mag. These properties could satisfy a set of cuts designed to identify kilonovae. However, this source was detected several times, starting 94 days prior to GW151226, in the Pan-STARRS Survey for Transients (dubbed as PS15cdi) and is therefore unrelated to the GW event. Given its long-term behavior, PS15cdi is likely a Type IIP supernova that transitioned out of its plateau phase during our observations, mimicking a kilonova-like behavior. We comment on the implications of this detection for contamination in future optical follow-up observations.

  12. A DECam Search for an Optical Counterpart to the LIGO Gravitational Wave Event GW151226

    DOE PAGES

    Cowperthwaite, P.S.; et al.

    2016-07-29

    We report the results of a Dark Energy Camera optical follow-up of the gravitational-wave (GW) event GW151226, discovered by the Advanced Laser Interferometer Gravitational-wave Observatory detectors. Our observations cover 28.8 deg(2) of the localization region in the i and z bands (containing 3% of the BAYESTAR localization probability), starting 10 hr after the event was announced and spanning four epochs at 2–24 days after the GW detection. We achievemore » $$5\\sigma $$ point-source limiting magnitudes of $$i\\approx 21.7$$ and $$z\\approx 21.5$$, with a scatter of 0.4 mag, in our difference images. Given the two-day delay, we search this area for a rapidly declining optical counterpart with $$\\gtrsim 3\\sigma $$ significance steady decline between the first and final observations. We recover four sources that pass our selection criteria, of which three are cataloged active galactic nuclei. The fourth source is offset by 5.8 arcsec from the center of a galaxy at a distance of 187 Mpc, exhibits a rapid decline by 0.5 mag over 4 days, and has a red color of $$i-z\\approx 0.3$$ mag. These properties could satisfy a set of cuts designed to identify kilonovae. However, this source was detected several times, starting 94 days prior to GW151226, in the Pan-STARRS Survey for Transients (dubbed as PS15cdi) and is therefore unrelated to the GW event. Given its long-term behavior, PS15cdi is likely a Type IIP supernova that transitioned out of its plateau phase during our observations, mimicking a kilonova-like behavior. We comment on the implications of this detection for contamination in future optical follow-up observations.« less

  13. A DECam Search for an Optical Counterpart to the LIGO Gravitational Wave Event GW151226

    SciTech Connect

    Cowperthwaite, P.S.; et al.

    2016-07-29

    We report the results of a Dark Energy Camera optical follow-up of the gravitational-wave (GW) event GW151226, discovered by the Advanced Laser Interferometer Gravitational-wave Observatory detectors. Our observations cover 28.8 deg(2) of the localization region in the i and z bands (containing 3% of the BAYESTAR localization probability), starting 10 hr after the event was announced and spanning four epochs at 2–24 days after the GW detection. We achieve $5\\sigma $ point-source limiting magnitudes of $i\\approx 21.7$ and $z\\approx 21.5$, with a scatter of 0.4 mag, in our difference images. Given the two-day delay, we search this area for a rapidly declining optical counterpart with $\\gtrsim 3\\sigma $ significance steady decline between the first and final observations. We recover four sources that pass our selection criteria, of which three are cataloged active galactic nuclei. The fourth source is offset by 5.8 arcsec from the center of a galaxy at a distance of 187 Mpc, exhibits a rapid decline by 0.5 mag over 4 days, and has a red color of $i-z\\approx 0.3$ mag. These properties could satisfy a set of cuts designed to identify kilonovae. However, this source was detected several times, starting 94 days prior to GW151226, in the Pan-STARRS Survey for Transients (dubbed as PS15cdi) and is therefore unrelated to the GW event. Given its long-term behavior, PS15cdi is likely a Type IIP supernova that transitioned out of its plateau phase during our observations, mimicking a kilonova-like behavior. We comment on the implications of this detection for contamination in future optical follow-up observations.

  14. Gravitational lensing of gravitational wave

    NASA Astrophysics Data System (ADS)

    Kei Wong, Wang; Ng, Kwan Yeung

    2017-01-01

    Gravitational lensing phenomena are widespread in electromagnetic astrophysics, and in principle may also be uncovered with gravitational waves. We examine gravitational wave events lensed by elliptical galaxies in the limit of geometric optics, where we expect to see multiple signals from the same event with different arrival times and amplitudes. By using mass functions for compact binaries from population-synthesis simulations and a lensing probability calculated from Planck data, we estimate the rate of lensed signals for future gravitational wave missions.

  15. Event Trigger Generator for Gravitational-Wave Data based on Hilbert-Huang Transform

    NASA Astrophysics Data System (ADS)

    Son, Edwin J.; Chu, Hyoungseok; Kim, Young-Min; Blackburn, Lindy; Hayama, Kazuhiro; Kim, Hwansun; Oh, John J.; Oh, Sang Hoon; Robinet, Florent

    2015-08-01

    The Hilbert-Huang Transform (HHT) is composed of the Empirical Mode Decomposition (EMD) and the Hilbert Spectral Analysis (HSA). The EMD decomposes any time series data into a small number of components called the Intrinsic Mode Functions (IMFs), compared to the Discrete Fourier Transform which decomposes a data into a large number of harmonic functions. Each IMF has varying amplitude and frequency with respect to time, which can be obtained by HSA. The time resolution of the modes in HHT is the same as that of the given time series, while in the Wavelet Transform, Constant Q Transform and Short-Time Fourier Transform, there is a tradeoff between the resolutions in frequency and time. Based on the time-dependent amplitudes of IMFs, we develop an Event Trigger Generator and demonstrate its efficiency by applying it to gravitational-wave mock data.

  16. Electromagnetic counterparts to Gravitational Wave events with the Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Vianello, Giacomo; Omodei, Nicola; Racusin, Judith L.; McEnery, Julie E.; Chiang, James; Buson, Sara; Fermi LAT Collaboration

    2017-01-01

    At least a fraction of Gravitational Wave (GW) progenitors is expected to emit an electromagnetic (EM) signal in the form of a short gamma-ray burst (sGRB). The discovery of such a transient EM counterpart is challenging because the LIGO/VIRGO localization region is much larger (several hundreds of square degrees) than the field of view of X-ray, optical and radio telescopes. The Fermi Large Area Telescope (LAT) has a wide field of view (~ 2.4 sr), and detects ~2-3 sGRBs per year above 100 MeV. It can detect them not only during the short prompt phase but also during their long-lasting high-energy afterglow phase. If other wide-field high-energy instruments such as Fermi-GBM, Swift-BAT or INTEGRAL-ISGRI cannot detect or localize with enough precision an EM counterpart during the prompt phase, the LAT can potentially pinpoint it with < 10 arcmin accuracy during the afterglow phase. This routinely happens in the case of gamma-ray bursts. Moreover, the LAT covers the entire localization region within hours of any GW triggers during normal operations, allowing upper bounds to be evaluated. This has been demonstrated in the case of the three known GW events (GW150914, LVT151012, and GW151226). Over the coming years, as LIGO and Virgo approach design sensitivity and will soon be able to detect these mergers, LAT will continue to provide a unique capability to potentially localize and characterize gravitational wave events.

  17. Swift Follow-up Observations of Candidate Gravitational-wave Transient Events

    NASA Astrophysics Data System (ADS)

    Evans, P. A.; Fridriksson, J. K.; Gehrels, N.; Homan, J.; Osborne, J. P.; Siegel, M.; Beardmore, A.; Handbauer, P.; Gelbord, J.; Kennea, J. A.; Smith, M.; Zhu, Q.; LIGO Scientific Collaboration; Virgo Collaboration; Aasi, J.; Abadie, J.; Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M.; Accadia, T.; Acernese, F.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Ajith, P.; Allen, B.; Allocca, A.; Amador Ceron, E.; Amariutei, D.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Ast, S.; Aston, S. M.; Astone, P.; Atkinson, D.; Aufmuth, P.; Aulbert, C.; Aylott, B. E.; Babak, S.; Baker, P.; Ballardin, G.; Ballmer, S.; Bao, Y.; Barayoga, J. C. B.; Barker, D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barton, M. A.; Bartos, I.; Bassiri, R.; Bastarrika, M.; Basti, A.; Batch, J.; Bauchrowitz, J.; Bauer, Th. S.; Bebronne, M.; Beck, D.; Behnke, B.; Bejger, M.; Beker, M. G.; Bell, A. S.; Bell, C.; Belopolski, I.; Benacquista, M.; Berliner, J. M.; Bertolini, A.; Betzwieser, J.; Beveridge, N.; Beyersdorf, P. T.; Bhadbade, T.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Biswas, R.; Bitossi, M.; Bizouard, M. A.; Black, E.; Blackburn, J. K.; Blackburn, L.; Blair, D.; Bland, B.; Blom, M.; Bock, O.; Bodiya, T. P.; Bogan, C.; Bond, C.; Bondarescu, R.; Bondu, F.; Bonelli, L.; Bonnand, R.; Bork, R.; Born, M.; Boschi, V.; Bose, S.; Bosi, L.; Bouhou, B.; Braccini, S.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Breyer, J.; Briant, T.; Bridges, D. O.; Brillet, A.; Brinkmann, M.; Brisson, V.; Britzger, M.; Brooks, A. F.; Brown, D. A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Burguet-Castell, J.; Buskulic, D.; Buy, C.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Calloni, E.; Camp, J. B.; Campsie, P.; Cannon, K.; Canuel, B.; Cao, J.; Capano, C. D.; Carbognani, F.; Carbone, L.; Caride, S.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C.; Cesarini, E.; Chalermsongsak, T.; Charlton, P.; Chassande-Mottin, E.; Chen, W.; Chen, X.; Chen, Y.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Chow, J.; Christensen, N.; Chua, S. S. Y.; Chung, C. T. Y.; Chung, S.; Ciani, G.; Clara, F.; Clark, D. E.; Clark, J. A.; Clayton, J. H.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colacino, C. N.; Colla, A.; Colombini, M.; Conte, A.; Conte, R.; Cook, D.; Corbitt, T. R.; Cordier, M.; Cornish, N.; Corsi, A.; Costa, C. A.; Coughlin, M.; Coulon, J.-P.; Couvares, P.; Coward, D. M.; Cowart, M.; Coyne, D. C.; Creighton, J. D. E.; Creighton, T. D.; Cruise, A. M.; Cumming, A.; Cunningham, L.; Cuoco, E.; Cutler, R. M.; Dahl, K.; Damjanic, M.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dattilo, V.; Daudert, B.; Daveloza, H.; Davier, M.; Daw, E. J.; Day, R.; Dayanga, T.; De Rosa, R.; DeBra, D.; Debreczeni, G.; Degallaix, J.; Del Pozzo, W.; Dent, T.; Dergachev, V.; DeRosa, R.; Dhurandhar, S.; Di Fiore, L.; Di Lieto, A.; Di Palma, I.; Emilio, M. Di Paolo; Di Virgilio, A.; Díaz, M.; Dietz, A.; Donovan, F.; Dooley, K. L.; Doravari, S.; Dorsher, S.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Dumas, J.-C.; Dwyer, S.; Eberle, T.; Edgar, M.; Edwards, M.; Effler, A.; Ehrens, P.; Eikenberry, S.; Endrőczi, G.; Engel, R.; Etzel, T.; Evans, K.; Evans, M.; Evans, T.; Factourovich, M.; Fafone, V.; Fairhurst, S.; Farr, B. F.; Favata, M.; Fazi, D.; Fehrmann, H.; Feldbaum, D.; Ferrante, I.; Ferrini, F.; Fidecaro, F.; Finn, L. S.; Fiori, I.; Fisher, R. P.; Flaminio, R.; Foley, S.; Forsi, E.; Forte, L. A.; Fotopoulos, N.; Fournier, J.-D.; Franc, J.; Franco, S.; Frasca, S.; Frasconi, F.; Frede, M.; Frei, M. A.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T. T.; Friedrich, D.; Fritschel, P.; Frolov, V. V.; Fujimoto, M.-K.; Fulda, P. J.; Fyffe, M.; Gair, J.; Galimberti, M.; Gammaitoni, L.; Garcia, J.; Garufi, F.; Gáspár, M. E.; Gelencser, G.; Gemme, G.; Genin, E.; Gennai, A.; Gergely, L. Á.; Ghosh, S.; Giaime, J. A.; Giampanis, S.; Giardina, K. D.; Giazotto, A.; Gil-Casanova, S.; Gill, C.; Gleason, J.; Goetz, E.; González, G.; Gorodetsky, M. L.; Goßler, S.; Gouaty, R.; Graef, C.; Graff, P. B.; Granata, M.; Grant, A.; Gray, C.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Griffo, C.; Grote, H.; Grover, K.; Grunewald, S.; Guidi, G. M.; Guido, C.; Gupta, R.; Gustafson, E. K.; Gustafson, R.; Hallam, J. M.; Hammer, D.; Hammond, G.; Hanks, J.; Hanna, C.; Hanson, J.; Harms, J.; Harry, G. M.; Harry, I. W.; Harstad, E. D.; Hartman, M. T.; Haughian, K.; Hayama, K.; Hayau, J.-F.; Heefner, J.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M. A.; Heng, I. S.; Heptonstall, A. W.; Herrera, V.; Heurs, M.; Hewitson, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Holt, K.; Holtrop, M.; Hong, T.; Hooper, S.; Hough, J.; Howell, E. J.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Ingram, D. R.; Inta, R.; Isogai, T.; Ivanov, A.; Izumi, K.; Jacobson, M.; James, E.; Jang, Y. J.; Jaranowski, P.; Jesse, E.; Johnson, W. W.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; Kalmus, P.; Kalogera, V.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Kasprzack, M.; Kasturi, R.; Katsavounidis, E.; Katzman, W.; Kaufer, H.; Kaufman, K.; Kawabe, K.; Kawamura, S.; Kawazoe, F.; Keitel, D.; Kelley, D.; Kells, W.; Keppel, D. G.; Keresztes, Z.; Khalaidovski, A.; Khalili, F. Y.; Khazanov, E. A.; Kim, B. K.; Kim, C.; Kim, H.; Kim, K.; Kim, N.; Kim, Y. M.; King, P. J.; Kinzel, D. L.; Kissel, J. S.; Klimenko, S.; Kline, J.; Kokeyama, K.; Kondrashov, V.; Koranda, S.; Korth, W. Z.; Kowalska, I.; Kozak, D.; Kringel, V.; Krishnan, B.; Królak, A.; Kuehn, G.; Kumar, P.; Kumar, R.; Kurdyumov, R.; Kwee, P.; Lam, P. K.; Landry, M.; Langley, A.; Lantz, B.; Lastzka, N.; Lawrie, C.; Lazzarini, A.; Le Roux, A.; Leaci, P.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Leong, J. R.; Leonor, I.; Leroy, N.; Letendre, N.; Lhuillier, V.; Li, J.; Li, T. G. F.; Lindquist, P. E.; Litvine, V.; Liu, Y.; Liu, Z.; Lockerbie, N. A.; Lodhia, D.; Logue, J.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J.; Lubinski, M.; Lück, H.; Lundgren, A. P.; Macarthur, J.; Macdonald, E.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Mageswaran, M.; Mailand, K.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man, N.; Mandel, I.; Mandic, V.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markosyan, A.; Maros, E.; Marque, J.; Martelli, F.; Martin, I. W.; Martin, R. M.; Marx, J. N.; Mason, K.; Masserot, A.; Matichard, F.; Matone, L.; Matzner, R. A.; Mavalvala, N.; Mazzolo, G.; McCarthy, R.; McClelland, D. E.; McDaniel, P.; McGuire, S. C.; McIntyre, G.; McIver, J.; Meadors, G. D.; Mehmet, M.; Meier, T.; Melatos, A.; Melissinos, A. C.; Mendell, G.; Menéndez, D. F.; Mercer, R. A.; Meshkov, S.; Messenger, C.; Meyer, M. S.; Miao, H.; Michel, C.; Milano, L.; Miller, J.; Minenkov, Y.; Mingarelli, C. M. F.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moe, B.; Mohan, M.; Mohapatra, S. R. P.; Moraru, D.; Moreno, G.; Morgado, N.; Morgia, A.; Mori, T.; Morriss, S. R.; Mosca, S.; Mossavi, K.; Mours, B.; Mow-Lowry, C. M.; Mueller, C. L.; Mueller, G.; Mukherjee, S.; Mullavey, A.; Müller-Ebhardt, H.; Munch, J.; Murphy, D.; Murray, P. G.; Mytidis, A.; Nash, T.; Naticchioni, L.; Necula, V.; Nelson, J.; Neri, I.; Newton, G.; Nguyen, T.; Nishizawa, A.; Nitz, A.; Nocera, F.; Nolting, D.; Normandin, M. E.; Nuttall, L.; Ochsner, E.; O'Dell, J.; Oelker, E.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Oldenberg, R. G.; O'Reilly, B.; O'Shaughnessy, R.; Osthelder, C.; Ott, C. D.; Ottaway, D. J.; Ottens, R. S.; Overmier, H.; Owen, B. J.; Page, A.; Palladino, L.; Palomba, C.; Pan, Y.; Pankow, C.; Paoletti, F.; Paoletti, R.; Papa, M. A.; Parisi, M.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Pedraza, M.; Penn, S.; Perreca, A.; Persichetti, G.; Phelps, M.; Pichot, M.; Pickenpack, M.; Piergiovanni, F.; Pierro, V.; Pihlaja, M.; Pinard, L.; Pinto, I. M.; Pitkin, M.; Pletsch, H. J.; Plissi, M. V.; Poggiani, R.; Pöld, J.; Postiglione, F.; Poux, C.; Prato, M.; Predoi, V.; Prestegard, T.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prix, R.; Prodi, G. A.; Prokhorov, L. G.; Puncken, O.; Punturo, M.; Puppo, P.; Quetschke, V.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Rácz, I.; Radkins, H.; Raffai, P.; Rakhmanov, M.; Ramet, C.; Rankins, B.; Rapagnani, P.; Raymond, V.; Re, V.; Reed, C. M.; Reed, T.; Regimbau, T.; Reid, S.; Reitze, D. H.; Ricci, F.; Riesen, R.; Riles, K.; Roberts, M.; Robertson, N. A.; Robinet, F.; Robinson, C.; Robinson, E. L.; Rocchi, A.; Roddy, S.; Rodriguez, C.; Rodruck, M.; Rolland, L.; Rollins, J. G.; Romano, J. D.; Romano, R.; Romie, J. H.; Rosińska, D.; Röver, C.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Ryan, K.; Salemi, F.; Sammut, L.; Sandberg, V.; Sankar, S.; Sannibale, V.; Santamaría, L.; Santiago-Prieto, I.; Santostasi, G.; Saracco, E.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Savage, R. L.; Schilling, R.; Schnabel, R.; Schofield, R. M. S.; Schulz, B.; Schutz, B. F.; Schwinberg, P.; Scott, J.; Scott, S. M.; Seifert, F.; Sellers, D.; Sentenac, D.; Sergeev, A.; Shaddock, D. A.; Shaltev, M.; Shapiro, B.; Shawhan, P.; Shoemaker, D. H.; Sidery, T. L.; Siemens, X.; Sigg, D.; Simakov, D.; Singer, A.; Singer, L.; Sintes, A. M.; Skelton, G. R.; Slagmolen, B. J. J.; Slutsky, J.; Smith, J. R.; Smith, M. R.; Smith, R. J. E.; Smith-Lefebvre, N. D.; Somiya, K.; Sorazu, B.; Speirits, F. C.; Sperandio, L.; Stefszky, M.; Steinert, E.; Steinlechner, J.; Steinlechner, S.; Steplewski, S.; Stochino, A.; Stone, R.; Strain, K. A.; Strigin, S. E.; Stroeer, A. S.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sung, M.; Susmithan, S.; Sutton, P. J.; Swinkels, B.; Szeifert, G.; Tacca, M.; Taffarello, L.; Talukder, D.; Tanner, D. B.; Tarabrin, S. P.; Taylor, R.; ter Braack, A. P. M.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Thüring, A.; Titsler, C.; Tokmakov, K. V.; Tomlinson, C.; Toncelli, A.; Tonelli, M.; Torre, O.; Torres, C. V.; Torrie, C. I.; Tournefier, E.; Travasso, F.; Traylor, G.; Tse, M.; Ugolini, D.; Vahlbruch, H.; Vajente, G.; van den Brand, J. F. J.; Van Den Broeck, C.; van der Putten, S.; van Veggel, A. A.; Vass, S.; Vasuth, M.; Vaulin, R.; Vavoulidis, M.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Verkindt, D.; Vetrano, F.; Viceré, A.; Villar, A. E.; Vinet, J.-Y.; Vitale, S.; Vocca, H.; Vorvick, C.; Vyatchanin, S. P.; Wade, A.; Wade, L.; Wade, M.; Waldman, S. J.; Wallace, L.; Wan, Y.; Wang, M.; Wang, X.; Wanner, A.; Ward, R. L.; Was, M.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Welborn, T.; Wen, L.; Wessels, P.; West, M.; Westphal, T.; Wette, K.; Whelan, J. T.; Whitcomb, S. E.; White, D. J.; Whiting, B. F.; Wiesner, K.; Wilkinson, C.; Willems, P. A.; Williams, L.; Williams, R.; Willke, B.; Wimmer, M.; Winkelmann, L.; Winkler, W.; Wipf, C. C.; Wiseman, A. G.; Wittel, H.; Woan, G.; Wooley, R.; Worden, J.; Yablon, J.; Yakushin, I.; Yamamoto, H.; Yamamoto, K.; Yancey, C. C.; Yang, H.; Yeaton-Massey, D.; Yoshida, S.; Yvert, M.; Zadrożny, A.; Zanolin, M.; Zendri, J.-P.; Zhang, F.; Zhang, L.; Zhao, C.; Zotov, N.; Zucker, M. E.; Zweizig, J.

    2012-12-01

    We present the first multi-wavelength follow-up observations of two candidate gravitational-wave (GW) transient events recorded by LIGO and Virgo in their 2009-2010 science run. The events were selected with low latency by the network of GW detectors (within less than 10 minutes) and their candidate sky locations were observed by the Swift observatory (within 12 hr). Image transient detection was used to analyze the collected electromagnetic data, which were found to be consistent with background. Off-line analysis of the GW data alone has also established that the selected GW events show no evidence of an astrophysical origin; one of them is consistent with background and the other one was a test, part of a "blind injection challenge." With this work we demonstrate the feasibility of rapid follow-ups of GW transients and establish the sensitivity improvement joint electromagnetic and GW observations could bring. This is a first step toward an electromagnetic follow-up program in the regime of routine detections with the advanced GW instruments expected within this decade. In that regime, multi-wavelength observations will play a significant role in completing the astrophysical identification of GW sources. We present the methods and results from this first combined analysis and discuss its implications in terms of sensitivity for the present and future instruments.

  18. Swift Follow-Up Observations of Candidate Gravitational-Wave Transient Events

    NASA Technical Reports Server (NTRS)

    Evans, P. A.; Fridriksson, J. K.; Gehrels, N.; Homan, J.; Osborne, J. P.; Siegel, M.; Beardmore, A.; Handbauer, P.; Gelbord, J.; Kennea, J. A.; Smith, M.; Zhu, Q.; Aasi, J.; Abadie, J.; Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M.; Accadia, T.; Acernese, F.; Adams, C.; Adams, T.; Blackburn, J. K.; Camp, J. B.; Kanner, J. B.

    2012-01-01

    We present the first multi-wavelength follow-up observations of two candidate gravitational-wave (GW) transient events recorded by LIGO and Virgo in their 2009-2010 science run. The events were selected with low latency by the network of GW detectors (within less than 10 minutes) and their candidate sky locations were observed by the Swift observatory (within 12 hr). Image transient detection was used to analyze the collected electromagnetic data, which were found to be consistent with background. Off-line analysis of the GW data alone has also established that the selected GW events show no evidence of an astrophysical origin; one of them is consistent with background and the other one was a test, part of a "blind injection challenge." With this work we demonstrate the feasibility of rapid follow-ups of GW transients and establish the sensitivity improvement joint electromagnetic and GW observations could bring. This is a first step toward an electromagnetic follow-up program in the regime of routine detections with the advanced GW instruments expected within this decade. In that regime, multi-wavelength observations will play a significant role in completing the astrophysical identification of GW sources. We present the methods and results from this first combined analysis and discuss its implications in terms of sensitivity for the present and future instruments.

  19. Combining Gravitational Wave Events with their Electromagnetic Counterparts: A Realistic Joint False-Alarm Rate

    NASA Astrophysics Data System (ADS)

    Ackley, Kendall; Eikenberry, Stephen; Klimenko, Sergey; LIGO Team

    2017-01-01

    We present a false-alarm rate for a joint detection of gravitational wave (GW) events and associated electromagnetic (EM) counterparts for Advanced LIGO and Virgo (LV) observations during the first years of operation. Using simulated GW events and their recostructed probability skymaps, we tile over the error regions using sets of archival wide-field telescope survey images and recover the number of astrophysical transients to be expected during LV-EM followup. With the known GW event injection coordinates we inject artificial electromagnetic (EM) sources at that site based on theoretical and observational models on a one-to-one basis. We calculate the EM false-alarm probability using an unsupervised machine learning algorithm based on shapelet analysis which has shown to be a strong discriminator between astrophysical transients and image artifacts while reducing the set of transients to be manually vetted by five orders of magnitude. We also show the performance of our method in context with other machine-learned transient classification and reduction algorithms, showing comparability without the need for a large set of training data opening the possibility for next-generation telescopes to take advantage of this pipeline for LV-EM followup missions.

  20. Microlensing Effects on Emission Lines from Homologously Expanding Winds

    NASA Astrophysics Data System (ADS)

    Ignace, R.; Bryce, H. M.; Hendry, M. A.

    2004-12-01

    We have been investigating the influence of microlensing on a variety of spectroscopic signatures relevant to circumstellar flows. Here we report on recent results for line profiles that form in spherically symmetric winds during a microlensing event. As a convenient test case, we have adopted a homologous velocity law (v ∝ r, from r=Rphot to rmax). Results are discussed for resonance scattering P Cygni lines and recombination emission lines. Somewhat surprisingly, the rectified line profiles show rather mild variations in response to microlensing. The reason is that both the line emission from the extended wind and the stellar photosphere are lensed, so that the strong magnification effects of lensing seen in either component are partially supressed when showing the continuum normalized spectrum (which is the common form of display for such data). Still, significant and observable variations in the line equivalent width do result. This research has been supported in part by NSF grant AST-0354261.

  1. Topics in gravitation - numerical simulations of event horizons and parameter estimation for LISA

    NASA Astrophysics Data System (ADS)

    Cohen, Michael Isaac

    2011-08-01

    In Part I, we consider numerical simulations of event horizons. Event horizons are the defining physical features of black hole spacetimes, and are of considerable interest in studying black hole dynamics. Here, we reconsider three techniques to find event horizons in numerical spacetimes, and find that straightforward integration of geodesics backward in time is most robust. We apply this method to various systems, from a highly spinning Kerr hole through to an asymmetric binary black hole inspiral. We find that the exponential rate at which outgoing null geodesics diverge from the event horizon of a Kerr black hole is the surface gravity of the hole. In head-on mergers we are able to track quasi-normal ringing of the merged black hole through seven oscillations, covering a dynamic range of about 10^5. In the head-on "kick" merger, we find that computing the Landau-Lifshitz velocity of the event horizon is very useful for an improved understanding of the kick behaviour. Finally, in the inspiral simulations, we find that the topological structure of the black holes does not produce an intermediate toroidal phase, though the structure is consistent with a potential re-slicing of the spacetime in order to introduce such a phase. We further discuss the topological structure of non-axisymmetric collisions. In Part II, we consider parameter estimation of cosmic string burst gravitational waves in Mock LISA data. A network of observable, macroscopic cosmic (super-)strings may well have formed in the early Universe. If so, the cusps that generically develop on cosmic-string loops emit bursts of gravitational radiation that could be detectable by gravitational-wave interferometers, such as the ground-based LIGO/Virgo detectors and the planned, space-based LISA detector. We develop two versions of a LISA-oriented string-burst search pipeline within the context of the Mock LISA Data Challenges, which rely on the publicly available MultiNest and PyMC software packages

  2. Detecting Extrasolar Asteroid Belts Through Their Microlensing Signatures

    NASA Astrophysics Data System (ADS)

    Lake, Ethan; Zheng, Zheng; Dong, Subo

    2016-03-01

    We propose that extrasolar asteroid belts can be detected through their gravitational microlensing signatures and present a simple theoretical understanding of how asteroid belts behave as gravitational lenses. Asteroid belt + star lens systems create so-called ``pseudo-caustics'', which are regions in the source plane where the magnification of the source exhibits a discontinuous jump. Such a magnification change can be associated with either a change in image multiplicity or with a sudden change in the size of an image. The existence of pseudo-caustics and the complex interplay between them and the formal caustics (which possess formally infinite magnification) lead to several interesting consequences, such as the presence of open caustics and the violation of Burke's theorem. These features allow such systems to generate very distinctive microlensing light curves across a wide region of asteroid belt parameter space and possess remarkably large lensing cross-sections. By constructing simulated light curves for a range of asteroid belt parameters, we demonstrate that upcoming space-based microlensing surveys like WFIRST are well-poised to discover extrasolar asteroid belts with masses on the order of 0 . 1M⊕ .

  3. MICROLENSING BINARIES WITH CANDIDATE BROWN DWARF COMPANIONS

    SciTech Connect

    Shin, I.-G.; Han, C.; Gould, A.; Skowron, J.; Udalski, A.; Szymanski, M. K.; Kubiak, M.; Soszynski, I.; Pietrzynski, G.; Poleski, R.; Ulaczyk, K.; Pietrukowicz, P.; Kozlowski, S.; Wyrzykowski, L.; Sumi, T.; Dominik, M.; Beaulieu, J.-P.; Tsapras, Y.; Bozza, V.; Abe, F.; Collaboration: OGLE Collaboration; MOA Collaboration; muFUN Collaboration; and others

    2012-12-01

    Brown dwarfs are important objects because they may provide a missing link between stars and planets, two populations that have dramatically different formation histories. In this paper, we present the candidate binaries with brown dwarf companions that are found by analyzing binary microlensing events discovered during the 2004-2011 observation seasons. Based on the low mass ratio criterion of q < 0.2, we found seven candidate events: OGLE-2004-BLG-035, OGLE-2004-BLG-039, OGLE-2007-BLG-006, OGLE-2007-BLG-399/MOA-2007-BLG-334, MOA-2011-BLG-104/OGLE-2011-BLG-0172, MOA-2011-BLG-149, and MOA-201-BLG-278/OGLE-2011-BLG-012N. Among them, we are able to confirm that the companions of the lenses of MOA-2011-BLG-104/OGLE-2011-BLG-0172 and MOA-2011-BLG-149 are brown dwarfs by determining the mass of the lens based on the simultaneous measurement of the Einstein radius and the lens parallax. The measured masses of the brown dwarf companions are 0.02 {+-} 0.01 M {sub Sun} and 0.019 {+-} 0.002 M {sub Sun} for MOA-2011-BLG-104/OGLE-2011-BLG-0172 and MOA-2011-BLG-149, respectively, and both companions are orbiting low-mass M dwarf host stars. More microlensing brown dwarfs are expected to be detected as the number of lensing events with well-covered light curves increases with new-generation searches.

  4. A search for electron antineutrinos associated with gravitational-wave events GW150914 and GW151226 using KamLAND

    SciTech Connect

    Gando, A.; Gando, Y.; Hachiya, T.; Hayashi, A.; Hayashida, S.; Ikeda, H.; Inoue, K.; Ishidoshiro, K.; Karino, Y.; Koga, M.; Matsuda, S.; Mitsui, T.; Nakamura, K.; Obara, S.; Oura, T.; Ozaki, H.; Shimizu, I.; Shirahata, Y.; Shirai, J.; Suzuki, A.; Takai, T.; Tamae, K.; Teraoka, Y.; Ueshima, K.; Watanabe, H.; Kozlov, A.; Takemoto, Y.; Yoshida, S.; Fushimi, K.; Piepke, A.; Banks, T. I.; Berger, B. E.; Fujikawa, B. K.; O’Donnell, T.; Learned, J. G.; Maricic, J.; Sakai, M.; Winslow, L. A.; Krupczak, E.; Ouellet, J.; Efremenko, Y.; Karwowski, H. J.; Markoff, D. M.; Tornow, W.; Detwiler, J. A.; Enomoto, S.; Decowski, M. P.

    2016-09-30

    Here, we present a search, using KamLAND, a kiloton-scale anti-neutrino detector, for low-energy anti-neutrino events that were coincident with the gravitational-wave (GW) events GW150914 and GW151226, and the candidate event LVT151012. We find no inverse beta-decay neutrino events within ±500 s of either GW signal. This non-detection is used to constrain the electron anti-neutrino fluence and the total integrated luminosity of the astrophysical sources.

  5. A DECam search for an optical counterpart to the LIGO gravitational-wave event GW151226

    SciTech Connect

    Cowperthwaite, P. S.; Berger, E.; Soares-Santos, M.; Annis, J.; Brout, D.; Brown, D. A.; Buckley-Geer, E.; Cenko, S. B.; Chen, H. Y.; Chornock, R.; Diehl, H. T.; Doctor, Z.; Drlica-Wagner, A.; Drout, M. R.; Farr, B.; Finley, D. A.; Foley, R. J.; Fong, W.; Fox, D. B.; Frieman, J.; Garcia-Bellido, J.; Gill, M. S. S.; Gruendl, R. A.; Herner, K.; Holz, D. E.; Kasen, D.; Kessler, R.; Lin, H.; Margutti, R.; Marriner, J.; Matheson, T.; Metzger, B. D.; Neilsen Jr., E. H.; Quataert, E.; Rest, A.; Sako, M.; Scolnic, D.; Smith, N.; Sobreira, F.; Strampelli, G. M.; Villar, V. A.; Walker, A. R.; Wester, W.; Williams, P. K. G.; Yanny, B.; Abbott, T. M. C.; Abdalla, F. B.; Allam, S.; Armstrong, R.; Bechtol, K.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Burke, D. L.; Rosell, A. Carnero; Kind, M. Carrasco; Carretero, J.; Castander, F. J.; Cunha, C. E.; D’Andrea, C. B.; Costa, L. N. da; Desai, S.; Dietrich, J. P.; Evrard, A. E.; Neto, A. Fausti; Fosalba, P.; Gerdes, D. W.; Giannantonio, T.; Goldstein, D. A.; Gruen, D.; Gutierrez, G.; Honscheid, K.; James, D. J.; Johnson, M. W. G.; Johnson, M. D.; Krause, E.; Kuehn, K.; Kuropatkin, N.; Lima, M.; Maia, M. A. G.; Marshall, J. L.; Menanteau, F.; Miquel, R.; Mohr, J. J.; Nichol, R. C.; Nord, B.; Ogando, R.; Plazas, A. A.; Reil, K.; Romer, A. K.; Sanchez, E.; Scarpine, V.; Sevilla-Noarbe, I.; Smith, R. C.; Suchyta, E.; Tarle, G.; Thomas, D.; Thomas, R. C.; Tucker, D. L.; Weller, J.

    2016-07-29

    We report the results of a Dark Energy Camera (DECam) optical follow-up of the gravitational wave (GW) event GW151226, discovered by the Advanced LIGO detectors. Our observations cover 28.8 deg2 of the localization region in the i and z bands (containing 3% of the BAYESTAR localization probability), starting 10 hours after the event was announced and spanning four epochs at 2–24 days after the GW detection. We achieve 5σ point-source limiting magnitudes of i ≈ 21.7 and z ≈ 21.5 , with a scatter of 0.4 mag, in our difference images. Given the two day delay, we search this area for a rapidly declining optical counterpart with ≳3σ significance steady decline between the first and final observations. We recover four sources that pass our selection criteria, of which three are cataloged AGN. The fourth source is offset by 5.8 arcsec from the center of a galaxy at a distance of 187 Mpc, exhibits a rapid decline by 0.5 mag over 4 days, and has a red color of i–z ≈ 0.3 mag. These properties roughly match the expectations for a kilonova. However, this source was detected several times, starting 94 days prior to GW151226, in the Pan-STARRS Survey for Transients (dubbed as PS15cdi) and is therefore unrelated to the GW event. Given its long-term behavior, PS15cdi is likely a Type IIP supernova that transitioned out of its plateau phase during our observations, mimicking a kilonova-like behavior. As a result, we comment on the implications of this detection for contamination in future optical follow-up observations.

  6. A DECam search for an optical counterpart to the LIGO gravitational-wave event GW151226

    DOE PAGES

    Cowperthwaite, P. S.; Berger, E.; Soares-Santos, M.; ...

    2016-07-29

    We report the results of a Dark Energy Camera (DECam) optical follow-up of the gravitational wave (GW) event GW151226, discovered by the Advanced LIGO detectors. Our observations cover 28.8 deg2 of the localization region in the i and z bands (containing 3% of the BAYESTAR localization probability), starting 10 hours after the event was announced and spanning four epochs at 2–24 days after the GW detection. We achieve 5σ point-source limiting magnitudes of i ≈ 21.7 and z ≈ 21.5 , with a scatter of 0.4 mag, in our difference images. Given the two day delay, we search this areamore » for a rapidly declining optical counterpart with ≳3σ significance steady decline between the first and final observations. We recover four sources that pass our selection criteria, of which three are cataloged AGN. The fourth source is offset by 5.8 arcsec from the center of a galaxy at a distance of 187 Mpc, exhibits a rapid decline by 0.5 mag over 4 days, and has a red color of i–z ≈ 0.3 mag. These properties roughly match the expectations for a kilonova. However, this source was detected several times, starting 94 days prior to GW151226, in the Pan-STARRS Survey for Transients (dubbed as PS15cdi) and is therefore unrelated to the GW event. Given its long-term behavior, PS15cdi is likely a Type IIP supernova that transitioned out of its plateau phase during our observations, mimicking a kilonova-like behavior. As a result, we comment on the implications of this detection for contamination in future optical follow-up observations.« less

  7. Effects of Kerr strong gravity on quasar x-ray microlensing

    SciTech Connect

    Chen, Bin; Dai, Xinyu; Baron, E.; Kantowski, R.

    2013-06-01

    Recent quasar microlensing observations have constrained the sizes of X-ray emission regions to be within about 10 gravitational radii of the central supermassive black hole. Therefore, the X-ray emission from lensed quasars is first strongly lensed by the black hole before it is lensed by the foreground galaxy and star fields. We present a scheme that combines the initial strong lensing of a Kerr black hole with standard linearized microlensing by intervening stars. We find that X-ray microlensed light curves incorporating Kerr strong gravity can differ significantly from standard curves. The amplitude of the fluctuations in the light curves can increase or decrease by ∼0.65-0.75 mag by including Kerr strong gravity. Larger inclination angles give larger amplitude fluctuations in the microlensing light curves. Consequently, current X-ray microlensing observations can under or overestimate the sizes of the X-ray emission regions. We estimate this bias using a simple metric based on the amplitude of magnitude fluctuations. The half-light radius of the X-ray emission region can be underestimated by up to ∼50% or overestimated by up to ∼20% depending on the spin of the black hole, the emission profile, and the inclination angle of the observer. Underestimates were found in most situations we investigated. The only exception was for a disk with large spin and a radially flat emission profile, observed nearly face-on. We thus conclude that more accurate microlensing size constraints should be obtainable by including Kerr lensing. We also find that the caustic crossing time can differ by months when Kerr strong gravity is included. A simultaneous monitoring of gravitational lensed quasars in both X-ray and optical bands with densely sampled X-ray light curves should reveal this feature. We conclude that it should be possible to constrain important parameters such as inclination angles and black hole spins from combined Kerr and microlensing effects.

  8. The effect of macromodel uncertainties on microlensing modelling of lensed quasars

    NASA Astrophysics Data System (ADS)

    Vernardos, G.; Fluke, C. J.

    2014-12-01

    Cosmological gravitational microlensing has been proven to be a powerful tool to constrain the structure of multiply imaged quasars, especially the accretion disc and central supermassive black hole system. However, the derived constraints on models may be affected by large systematic errors introduced in the various stages of modelling, namely, the macromodels, the microlensing magnification maps, and the convolution with realistic disc profiles. In particular, it has been known that different macromodels of the galaxy lens that fit the observations equally well, can lead to different values of convergence, κ, and shear, γ, required to generate magnification maps. So far, ˜25 microlensed quasars have been studied using microlensing techniques, where each system has been modelled and analysed individually, or in small samples. This is about to change due to the upcoming synoptic all-sky surveys, which are expected to discover thousands of quasars suitable for microlensing studies. In this study, we investigate the connection between macromodels of the galaxy lens and microlensing magnification maps throughout the parameter space in preparation for future studies of large statistical samples of systems displaying microlensing. In particular, we use 55 900 maps produced by the GERLUMPH parameter survey (available online at http://gerlumph.swin.edu.au) and identify regions of parameter space where macromodel uncertainties (Δκ, Δγ) lead to statistically different magnification maps. Strategies for mitigating the effect of Δκ, Δγ uncertainties are discussed in order to understand and control this potential source of systematic errors in accretion disc constraints derived from microlensing.

  9. Microlensing of circumstellar envelopes. III. Line profiles from stellar winds in homologous expansion

    NASA Astrophysics Data System (ADS)

    Hendry, M. A.; Ignace, R.; Bryce, H. M.

    2006-05-01

    This paper examines line profile evolution due to the linear expansion of circumstellar material obsverved during a microlensing event. This work extends our previous papers on emission line profile evolution from radial and azimuthal flow during point mass lens events and fold caustic crossings. Both "flavours" of microlensing were shown to provide effective diagnostics of bulk motion in circumstellar envelopes. In this work a different genre of flow is studied, namely linear homologous expansion, for both point mass lenses and fold caustic crossings. Linear expansion is of particular relevance to the effects of microlensing on supernovae at cosmological distances. We derive line profiles and equivalent widths for the illustrative cases of pure resonance and pure recombination lines, modelled under the Sobolev approximation. The efficacy of microlensing as a diagnostic probe of the stellar environs is demonstrated and discussed.

  10. Liquid Tunable Microlenses based on MEMS techniques

    PubMed Central

    Zeng, Xuefeng; Jiang, Hongrui

    2013-01-01

    The recent rapid development in microlens technology has provided many opportunities for miniaturized optical systems, and has found a wide range of applications. Of these microlenses, tunable-focus microlenses are of special interest as their focal lengths can be tuned using micro-scale actuators integrated with the lens structure. Realization of such tunable microlens generally relies on the microelectromechanical system (MEMS) technologies. Here, we review the recent progress in tunable liquid microlenses. The underlying physics relevant to these microlenses are first discussed, followed by description of three main categories of tunable microlenses involving MEMS techniques, mechanically driven, electrically driven, and those integrated within microfluidic systems. PMID:24163480

  11. Discovering Exoplanets with Microlensing: Transition to the Next Generation

    NASA Astrophysics Data System (ADS)

    Gould, Andrew

    We propose to continue our successful program of planet discovery using the gravitaional microlensing technique. Our work will specifically focus on so-called "high- magnification events", which are exceptionally sensitive to planets, and which allow us to extract exceptionally detailed information about each planetary system. These results will be of high scientific interest in their own right, but will also play a key role in the transition to "next-generation" surveys that will discover many times more planets in "low-magnification events". We will continue to operate and build our network of approximately 30 amateur+professional astronomers (about half each) on 6 continents plus Oceania, which enables the 24 hour coverage that is crucial to extracting planetary science from microlensing events. In particular, by engaging the amateurs at a high scientific level, we will both improve the quantity and quality of amateur data and utilize their role as a "transmission belt" to the broader public. Over the past few years, high-mag events have enabled the first detection of a Jupiter- Saturn analog system, the first census of ice and gas giants beyond the snow line, the recognition that "cold Neptunes" are extremely common, and the detection of 3 very massive, super-Jupiter planets orbiting M dwarfs (which may challenge the standard "core-accretion" paradigm). Analysis of these events has also led to key theoretical insights, including the fact that planet orbital motion can be detected in microlensing events and that careful effort is required to disentangle this from "parallax effects" (due to the Earth's own orbital motion). The direct impact of our proposed work will be to increase the still small statistics of high-mag planet detections (due to the intrinsic rarity of high-mag events) and to exploit the sensitivity of these events to higher-order effects (including parallax, planet orbital motion, and multiple planets) to gain deeper knowledge of detected systems

  12. A Search for an Optical Counterpart to the Gravitational-wave Event GW151226

    NASA Astrophysics Data System (ADS)

    Smartt, S. J.; Chambers, K. C.; Smith, K. W.; Huber, M. E.; Young, D. R.; Chen, T.-W.; Inserra, C.; Wright, D. E.; Coughlin, M.; Denneau, L.; Flewelling, H.; Heinze, A.; Jerkstrand, A.; Magnier, E. A.; Maguire, K.; Mueller, B.; Rest, A.; Sherstyuk, A.; Stalder, B.; Schultz, A. S. B.; Stubbs, C. W.; Tonry, J.; Waters, C.; Wainscoat, R. J.; Della Valle, M.; Dennefeld, M.; Dimitriadis, G.; Firth, R. E.; Fraser, M.; Frohmaier, C.; Gal-Yam, A.; Harmanen, J.; Kankare, E.; Kotak, R.; Kromer, M.; Mandel, I.; Sollerman, J.; Gibson, B.; Primak, N.; Willman, M.

    2016-08-01

    We present a search for an electromagnetic counterpart of the gravitational-wave source GW151226. Using the Pan-STARRS1 telescope we mapped out 290 square degrees in the optical i P1 filter, starting 11.5 hr after the LIGO information release and lasting for an additional 28 days. The first observations started 49.5 hr after the time of the GW151226 detection. We typically reached sensitivity limits of i P1 = 20.3-20.8 and covered 26.5% of the LIGO probability skymap. We supplemented this with ATLAS survey data, reaching 31% of the probability region to shallower depths of m ≃ 19. We found 49 extragalactic transients (that are not obviously active galactic nuclei), including a faint transient in a galaxy at 7 Mpc (a luminous blue variable outburst) plus a rapidly decaying M-dwarf flare. Spectral classification of 20 other transient events showed them all to be supernovae. We found an unusual transient, PS15dpn, with an explosion date temporally coincident with GW151226, that evolved into a type Ibn supernova. The redshift of the transient is secure at z = 0.1747 ± 0.0001 and we find it unlikely to be linked, since the luminosity distance has a negligible probability of being consistent with that of GW151226. In the 290 square degrees surveyed we therefore do not find a likely counterpart. However we show that our survey strategy would be sensitive to NS-NS mergers producing kilonovae at D L ≲ 100 Mpc, which is promising for future LIGO/Virgo searches.

  13. On extreme transient events from rotating black holes and their gravitational wave emission

    NASA Astrophysics Data System (ADS)

    van Putten, Maurice H. P. M.; Della Valle, Massimo

    2017-01-01

    The super-luminous object ASASSN-15lh (SN2015L) is an extreme event with a total energy Erad ≃ 1.1 × 1052 erg in blackbody radiation on par with its kinetic energy Ek in ejecta and a late time plateau in the UV, which defies a nuclear origin. It likely presents a new explosion mechanism for hydrogen-deprived supernovae. With no radio emission and no H-rich environment, we propose to identify Erad with dissipation of a baryon-poor outflow in the optically thick remnant stellar envelope produced by a central engine. By negligible time-scales of light crossing and radiative cooling of the envelope, SN2015L's light curve closely tracks the evolution of this engine. We here model its light curve by the evolution of black hole spin during angular momentum loss in Alvén waves to matter at the Inner Most Stable Circular Orbit (ISCO). The duration is determined by σ = MT/M of the torus mass MT around the black hole of mass M: σ ˜ 10-7 and σ ˜ 10-2 for SN2015L and, respectively, a long GRB. The observed electromagnetic radiation herein represents a minor output of the rotational energy Erot of the black hole, while most is radiated unseen in gravitational radiation. This model explains the high-mass slow-spin binary progenitor of GWB150914, as the remnant of two CC-SNe in an intra-day binary of two massive stars. This model rigorously predicts a change in magnitude Δm ≃ 1.15 in the light curve post-peak, in agreement with the light curve of SN2015L with no fine-tuning.

  14. The gravitational bending of light by stars: a continuing story of curiosity, scepticism, surprise, and fascination

    NASA Astrophysics Data System (ADS)

    Dominik, Martin

    2011-04-01

    Driven entirely by human curiosity, the effect of the gravitational bending of light has evolved on unforeseen paths, in an interplay between shifts in prevailing paradigms and advance of technology, into the most unusual way to study planet populations. The confirmation of the bending angle predicted by Einstein with the Solar Eclipse measurements from 1919 marked the breakthrough of the theory of General Relativity, but it was not before the detection of the double image of the quasar 0957+561 that `gravitational lensing' really entered the observational era. The observation of a characteristic transient brightening of a star caused by the gravitational deflection of its light by an intervening foreground star, constituting a `microlensing event', required even further advance in technology before it could first emerge in 1993. While it required more patience in waiting before `Einstein's blip' for the first time revealed the presence of a planet orbiting a star other than the Sun, such detections can now be monitored live, and gravitational microlensing is not only sensitive to masses as low as that of the Moon, but can even reveal planets around stars in galaxies other than the Milky Way.

  15. Microlensing by Kuiper, Oort, and Free-Floating Planets

    NASA Astrophysics Data System (ADS)

    Gould, Andrew

    2016-08-01

    Microlensing is generally thought to probe planetary systems only out to a few Einstein radii. Microlensing events generated by bound planets beyond about 10 Einstein radii generally do not yield any trace of their hosts, and so would be classified as free floating planets (FFPs). I show that it is already possible, using adaptive optics (AO), to constrain the presence of potential hosts to FFP candidates at separations comparable to the Oort Cloud. With next-generation telescopes, planets at Kuiper-Belt separations can be probed. Next generation telescopes will also permit routine vetting for all FFP candidates, simply by obtaining second epochs 4-8 years after the event.At present, the search for such hosts is restricted to within the ``confusion limit'' of θ_\\confus ˜ 0.25'' but future WFIRST (Wide Field Infrared Survey Telescope) observations will allow one to probe beyond this confusion limit as well.

  16. Mass Measurements of Isolated Objects from Space-based Microlensing

    NASA Astrophysics Data System (ADS)

    Zhu, Wei; Calchi Novati, S.; Gould, A.; Udalski, A.; Han, C.; Shvartzvald, Y.; Ranc, C.; Jørgensen, U. G.; Poleski, R.; Bozza, V.; Beichman, C.; Bryden, G.; Carey, S.; Gaudi, B. S.; Henderson, C. B.; Pogge, R. W.; Porritt, I.; Wibking, B.; Yee, J. C.; SPITZER Team; Pawlak, M.; Szymański, M. K.; Skowron, J.; Mróz, P.; Kozłowski, S.; Wyrzykowski, Ł.; Pietrukowicz, P.; Pietrzyński, G.; Soszyński, I.; Ulaczyk, K.; OGLE Group; Choi, J.-Y.; Park, H.; Jung, Y. K.; Shin, I.-G.; Albrow, M. D.; Park, B.-G.; Kim, S.-L.; Lee, C.-U.; Cha, S.-M.; Kim, D.-J.; Lee, Y.; KMTNET Group; Friedmann, M.; Kaspi, S.; Maoz, D.; WISE Group; Hundertmark, M.; Street, R. A.; Tsapras, Y.; Bramich, D. M.; Cassan, A.; Dominik, M.; Bachelet, E.; Dong, Subo; Figuera Jaimes, R.; Horne, K.; Mao, S.; Menzies, J.; Schmidt, R.; Snodgrass, C.; Steele, I. A.; Wambsganss, J.; RoboNeT Team; Skottfelt, J.; Andersen, M. I.; Burgdorf, M. J.; Ciceri, S.; D'Ago, G.; Evans, D. F.; Gu, S.-H.; Hinse, T. C.; Kerins, E.; Korhonen, H.; Kuffmeier, M.; Mancini, L.; Peixinho, N.; Popovas, A.; Rabus, M.; Rahvar, S.; Tronsgaard, R.; Scarpetta, G.; Southworth, J.; Surdej, J.; von Essen, C.; Wang, Y.-B.; Wertz, O.; MiNDSTEP Group

    2016-07-01

    We report on the mass and distance measurements of two single-lens events from the 2015 Spitzer microlensing campaign. With both finite-source effect and microlens parallax measurements, we find that the lens of OGLE-2015-BLG-1268 is very likely a brown dwarf (BD). Assuming that the source star lies behind the same amount of dust as the Bulge red clump, we find the lens is a 45 ± 7 {M}{{J}} BD at 5.9 ± 1.0 kpc. The lens of of the second event, OGLE-2015-BLG-0763, is a 0.50 ± 0.04 {M}⊙ star at 6.9 ± 1.0 kpc. We show that the probability to definitively measure the mass of isolated microlenses is dramatically increased once simultaneous ground- and space-based observations are conducted.

  17. Microlensing of the Broad Line Region in the Most Anomalous Lensed Quasar

    NASA Astrophysics Data System (ADS)

    Keeton, Charles

    2009-07-01

    The gravitationally lensed quasar SDSS J0924+0219 has highly anomalous flux ratios: image D is more than a factor of 10 fainter than expected if the lens galaxy has a smooth mass distribution. From previous HST spectra {Keeton et al. 2006} and photometric variability {Morgan et al. 2006} we know the anomalous continuum flux ratios are caused by microlensing by stars in the lens galaxy. However, with existing data we do not know whether the anomalous emission line flux ratios are caused by microlensing by stars or millilensing by dark matter clumps. With just four orbits we can measure spectra at two more epochs and determine unambiguously whether the quasar's broad line region {BLR} is microlensed. If the emission line flux ratios vary, that would prove the BLR is microlensed and make SDSS0924 only the second known quasar with microlensing of an optical broad emission line. In this case we would be able to constrain the BLR size and and relative densities of stars and dark matter in the lens galaxy. Conversely, if the emission line flux ratios do not vary, that would prove the BLR is millilensed rather than microlensed, and make SDSS0924 the first lens known to have both microlensing {of the continuum} and millilensing {of the BLR}. This would usher in a new and rich field of multiscale lensing. The conclusions about small-scale structure in galaxies and quasars will be exciting in either case. This experiment is infeasible with ground-based telescopes, but with HST it is easy and fast to make this powerful test of small-scale structure in SDSS0924.

  18. Understanding possible electromagnetic counterparts to loud gravitational wave events: Binary black hole effects on electromagnetic fields

    SciTech Connect

    Palenzuela, Carlos; Lehner, Luis; Yoshida, Shin

    2010-04-15

    In addition to producing loud gravitational waves, the dynamics of a binary black hole system could induce emission of electromagnetic radiation by affecting the behavior of plasmas and electromagnetic fields in their vicinity. We study how the electromagnetic fields are affected by a pair of orbiting black holes through the merger. In particular, we show how the binary's dynamics induce a variability in possible electromagnetically induced emissions as well as an enhancement of electromagnetic fields during the late-merge and merger epochs. These time dependent features will likely leave their imprint in processes generating detectable emissions and can be exploited in the detection of electromagnetic counterparts of gravitational waves.

  19. Techniques for Targeted Fermi-GBM Follow-Up of Gravitational-Wave Events

    NASA Technical Reports Server (NTRS)

    Blackburn, L.; Camp, J.; Briggs, M. S.; Connaughton, V.; Jenke, P.; Christensen, N.; Veitch, J.

    2012-01-01

    The Advanced LIGO and Advanced Virgo ground-based gravitational-wave (GW) detectors are projected to come online 2015 2016, reaching a final sensitivity sufficient to observe dozens of binary neutron star mergers per year by 2018. We present a fully-automated, targeted search strategy for prompt gamma-ray counterparts in offline Fermi-GBM data. The multi-detector method makes use of a detailed model response of the instrument, and benefits from time and sky location information derived from the gravitational-wave signal.

  20. GERLUMPH Data Release 2: 2.5 Billion Simulated Microlensing Light Curves

    NASA Astrophysics Data System (ADS)

    Vernardos, G.; Fluke, C. J.; Bate, N. F.; Croton, D.; Vohl, D.

    2015-04-01

    In the upcoming synoptic all-sky survey era of astronomy, thousands of new multiply imaged quasars are expected to be discovered and monitored regularly. Light curves from the images of gravitationally lensed quasars are further affected by superimposed variability due to microlensing. In order to disentangle the microlensing from the intrinsic variability of the light curves, the time delays between the multiple images have to be accurately measured. The resulting microlensing light curves can then be analyzed to reveal information about the background source, such as the size of the quasar accretion disk. In this paper we present the most extensive and coherent collection of simulated microlensing light curves; we have generated \\gt 2.5 billion light curves using the GERLUMPH high resolution microlensing magnification maps. Our simulations can be used to train algorithms to measure lensed quasar time delays, plan future monitoring campaigns, and study light curve properties throughout parameter space. Our data are openly available to the community and are complemented by online eResearch tools, located at http://gerlumph.swin.edu.au.

  1. DISCOVERY OF ENERGY-DEPENDENT X-RAY MICROLENSING IN Q2237+0305

    SciTech Connect

    Chen Bin; Dai Xinyu; Kochanek, C. S.; Blackburne, Jeffrey A.; Chartas, George; Kozlowski, Szymon

    2011-10-20

    We present our long-term Chandra X-ray monitoring data for the gravitationally lensed quasar Q2237+0305 with 20 epochs spanning 10 years. We easily detect microlensing variability between the images in the full (0.2-8 keV), soft (0.2-2 keV), and hard (2-8 keV) bands at very high confidence. We also detect, for the first time, chromatic microlensing differences between the soft and hard X-ray bands. The hard X-ray band is more strongly microlensed than the soft band, suggesting that the corona above the accretion disk thought to generate the X-rays has a non-uniform electron distribution, in which the hotter and more energetic electrons occupy more compact regions surrounding the black holes. Both the hard and soft X-ray bands are more strongly microlensed than the optical (rest-frame UV) emission, indicating that the X-ray emission is more compact than the optical, confirming the microlensing results from other lenses.

  2. The OGLE view of microlensing towards the Magellanic Clouds - III. Ruling out subsolar MACHOs with the OGLE-III LMC data

    NASA Astrophysics Data System (ADS)

    Wyrzykowski, Ł.; Kozłowski, S.; Skowron, J.; Udalski, A.; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Szewczyk, O.; Ulaczyk, K.; Poleski, R.

    2011-05-01

    In the third part of the series presenting the Optical Gravitational Lensing Experiment (OGLE) microlensing studies of the dark matter halo compact objects (MACHOs), we describe results of the OGLE-III monitoring of the Large Magellanic Cloud (LMC). This unprecedented data set contains almost continuous photometric coverage over 8 years of about 35 million objects spread over 40 deg2. We report a detection of two candidate microlensing events found with the automated pipeline and an additional two, less probable, candidate events found manually. The optical depth derived for the two main candidates was calculated following a detailed blending examination and detection efficiency determination and was found to be τ= (0.16 ± 0.12) × 10-7. If the microlensing signal we observe originates from MACHOs, then it means their masses are around 0.2 M⊙ and they comprise only f= 3 ± 2 per cent of the mass of the Galactic halo. However, the more likely explanation of our detections does not involve dark matter compact objects at all and relies on the natural effect of self-lensing of LMC stars by LMC lenses. In such a scenario, we can almost completely rule out MACHOs in the subsolar mass range with an upper limit at f < 7 per cent reaching its minimum of f < 4 per cent at M= 0.1 M⊙. For masses around M= 10 M⊙, the constraints on the MACHOs are more lenient with f˜ 20 per cent. Owing to limitations of the survey, there is no reasonable limit found for heavier masses, leaving only a tiny window of mass spectrum still available for dark matter compact objects. Based on observations obtained with the 1.3-m Warsaw telescope at the Las Campanas Observatory of the Carnegie Institution of Washington.

  3. Planet Sensitivity from Combined Ground- and Space-based Microlensing Observations

    NASA Astrophysics Data System (ADS)

    Zhu, Wei; Gould, Andrew; Beichman, Charles; Calchi Novati, Sebastiano; Carey, Sean; Gaudi, B. Scott; Henderson, Calen B.; Penny, Matthew; Shvartzvald, Yossi; Yee, Jennifer C.; Udalski, A.; Poleski, R.; Skowron, J.; Kozłowski, S.; Mróz, P.; Pietrukowicz, P.; Pietrzyński, G.; Szymański, M. K.; Soszyński, I.; Ulaczyk, K.; Wyrzykowski, Ł.; OGLE Collaboration; Abe, F.; Barry, R. K.; Bennett, D. P.; Bhattacharya, A.; Bond, I. A.; Freeman, M.; Fukui, A.; Hirao, Y.; Itow, Y.; Koshimoto, N.; Ling, H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Nagakane, M.; Ohnishi, K.; Saito, To.; Sullivan, D. J.; Sumi, T.; Suzuki, D.; Tristram, P. J.; Rattenbury, N.; Wakiyama, Y.; Yonehara, A.; MOA Collaboration; Maoz, D.; Kaspi, S.; Friedmann, M.; The Wise Group

    2015-12-01

    To move one step forward toward a Galactic distribution of planets, we present the first planet sensitivity analysis for microlensing events with simultaneous observations from space and the ground. We present this analysis for two such events, OGLE-2014-BLG-0939 and OGLE-2014-BLG-0124, which both show substantial planet sensitivity even though neither of them reached high magnification. This suggests that an ensemble of low to moderate magnification events can also yield significant planet sensitivity, and therefore probability, for detecting planets. The implications of our results to the ongoing and future space-based microlensing experiments to measure the Galactic distribution of planets are discussed.

  4. Gravitational Waves from Merging Intermediate-mass Black Holes. II. Event Rates at Ground-based Detectors

    NASA Astrophysics Data System (ADS)

    Shinkai, Hisa-aki; Kanda, Nobuyuki; Ebisuzaki, Toshikazu

    2017-02-01

    Based on a dynamical formation model of a supermassive black hole (SMBH), we estimate the expected observational profile of gravitational waves at ground-based detectors, such as KAGRA or advanced LIGO/VIRGO. Noting that the second generation of detectors have enough sensitivity from 10 Hz and up (especially with KAGRA owing to its location at less seismic noise), we are able to detect the ring-down gravitational wave of a BH with mass M< 2× {10}3{M}ȯ . This enables us to check the sequence of BH mergers to SMBHs via intermediate-mass BHs. We estimate the number density of galaxies from the halo formation model and estimate the number of BH mergers from the giant molecular cloud model assuming hierarchical growth of merged cores. At the designed KAGRA (and/or advanced LIGO/VIRGO), we find that the BH merger of its total mass M∼ 60{M}ȯ is at the peak of the expected mass distribution. With its signal-to-noise ratio ρ =10 (30), we estimate the event rate R∼ 200 (20) per year in the most optimistic case, and we also find that BH mergers in the range M< 150{M}ȯ are R> 1 per year for ρ =10. Thus, if we observe a BH with more than 100{M}ȯ in future gravitational-wave observations, our model naturally explains its source.

  5. Maximizing the probability of detecting an electromagnetic counterpart of gravitational-wave events

    NASA Astrophysics Data System (ADS)

    Coughlin, Michael; Stubbs, Christopher

    2016-10-01

    Compact binary coalescences are a promising source of gravitational waves for second-generation interferometric gravitational-wave detectors such as advanced LIGO and advanced Virgo. These are among the most promising sources for joint detection of electromagnetic (EM) and gravitational-wave (GW) emission. To maximize the science performed with these objects, it is essential to undertake a followup observing strategy that maximizes the likelihood of detecting the EM counterpart. We present a follow-up strategy that maximizes the counterpart detection probability, given a fixed investment of telescope time. We show how the prior assumption on the luminosity function of the electro-magnetic counterpart impacts the optimized followup strategy. Our results suggest that if the goal is to detect an EM counterpart from among a succession of GW triggers, the optimal strategy is to perform long integrations in the highest likelihood regions. For certain assumptions about source luminosity and mass distributions, we find that an optimal time investment that is proportional to the 2/3 power of the surface density of the GW location probability on the sky. In the future, this analysis framework will benefit significantly from the 3-dimensional localization probability.

  6. Gravitational wave signatures of the absence of an event horizon: Nonradial oscillations of a thin-shell gravastar

    SciTech Connect

    Pani, Paolo; Berti, Emanuele; Cardoso, Vitor; Chen Yanbei; Norte, Richard

    2009-12-15

    Gravitational waves from compact objects provide information about their structure, probing deep into strong-gravity regions. Here we illustrate how the presence or absence of an event horizon can produce qualitative differences in the gravitational waves emitted by ultracompact objects. In order to set up a straw-man ultracompact object with no event horizon, but which is otherwise almost identical to a black hole, we consider a nonrotating thin-shell model inspired by Mazur and Mottola's gravastar, which has a Schwarzschild exterior, a de Sitter interior and an infinitely thin shell with finite tension separating the two regions. As viewed from the external space-time, the shell can be located arbitrarily close to the Schwarzschild radius, so a gravastar might seem indistinguishable from a black hole when tests are only performed on its external metric. We study the linearized dynamics of the system, and, in particular, the junction conditions connecting internal and external gravitational perturbations. As a first application of the formalism we compute polar and axial oscillation modes of a thin-shell gravastar. We show that the quasinormal mode spectrum is completely different from that of a black hole, even in the limit when the surface redshift becomes infinite. Polar quasinormal modes depend on the equation of state of matter on the shell and can be used to distinguish between different gravastar models. Our calculations suggest that low-compactness gravastars could be unstable when the sound speed on the shell v{sub s}/c > or approx. 0.92.

  7. OGLE-2013-BLG-0578L: A Microlensing Binary Composed of a Brown Dwarf and an M Dwarf

    NASA Astrophysics Data System (ADS)

    Park, H.; Udalski, A.; Han, C.; Poleski, R.; Skowron, J.; Kozłowski, S.; Wyrzykowski, Ł.; Szymański, M. K.; Pietrukowicz, P.; Pietrzyński, G.; Soszyński, I.; Ulaczyk, K.; OGLE Collaboration

    2015-06-01

    Determining the physical parameters of binary microlenses is hampered by the lack of information about the angular Einstein radius due to the difficulty involved in resolving caustic crossings. In this paper, we present an analysis of the binary microlensing event OGLE-2013-BLG-0578, for which the caustic exit was precisely predicted in advance from real-time analysis, enabling us to densely resolve the caustic crossing and to measure the Einstein radius. From the mass measurement of the lens system based on the Einstein radius, combined with additional information about the lens parallax, we determine that the lens is a binary composed of a late-type M dwarf primary and a substellar brown dwarf companion. This event demonstrates the capability of current real-time microlensing modeling and the usefulness of microlensing for detecting and characterizing faint or dark objects in the Galaxy.

  8. Geographic and Annual Influences on Optical Follow-up of Gravitational Wave Events

    NASA Astrophysics Data System (ADS)

    Srivastava, Varun; Bhalerao, Varun; Ravi, Aravind P.; Ghosh, Archisman; Bose, Sukanta

    2017-03-01

    We investigate the effects of observatory location on the probability of discovering optical/infrared (OIR) counterparts of gravitational wave sources. We show that, for the LIGO–Virgo network, the odds of discovering OIR counterparts show some latitude dependence. A stronger effect is seen to arise from the timing of LIGO–Virgo observing runs during the year, with northern OIR observatories having a better chance of finding the counterparts in northern winters. Assuming identical technical capabilities, the tentative mid-2017 three-detector network observing run favors southern OIR observatories for the discovery of electromagnetic counterparts.

  9. Size of the Accretion Disk in the Graviationally Lensed Quasar SDSS J1004+4112 from the Statistics of Microlensing Magnifications

    NASA Astrophysics Data System (ADS)

    Fian, C.; Mediavilla, E.; Hanslmeier, A.; Oscoz, A.; Serra-Ricart, M.; Muñoz, J. A.; Jiménez-Vicente, J.

    2016-10-01

    We present eight monitoring seasons of the four brightest images of the gravitational lens SDSS J1004+4112 observed between 2003 December and 2010 October. Using measured time delays for the images A, B, and C and the model predicted time delay for image D we have removed the intrinsic quasar variability, finding microlensing events of about 0.5 and 0.7 mag of amplitude in the images C and D. From the statistics of microlensing amplitudes in images A, C, and D, we have inferred the half-light radius (at {λ }{rest}=2407 \\mathringA ) for the accretion disk using two different methods, {R}1/2={8.7}-5.5+18.5\\sqrt{M/0.3{M}⊙ } (histogram product) and {R}1/2={4.2}-2.2+3.2\\sqrt{M/0.3{M}⊙ } lt-days ({χ }2). The results are in agreement within uncertainties with the size predicted from the black hole mass in SDSS J1004+4112 using thin disk theory.

  10. High-Energy Electromagnetic Offline Follow-Up of Ligo-Virgo Gravitational-Wave Binary Coalescence Candidate Events

    NASA Technical Reports Server (NTRS)

    Blackburn, L.; Briggs, M. S.; Camp, J.; Christensen, N.; Connaughton, V.; Jenke, P.; Remillard, R. A.; Veitch, J.

    2015-01-01

    We present two different search methods for electromagnetic counterparts to gravitational-wave (GW) events from ground-based detectors using archival NASA high-energy data from the Fermi Gamma-ray Burst Monitor (GBM) and RXTE All-sky Monitor (ASM) instruments. To demonstrate the methods, we use a limited number of representative GW background noise events produced by a search for binary neutron star coalescence over the last two months of the LIGO-Virgo S6/VSR3 joint science run. Time and sky location provided by the GW data trigger a targeted search in the high-energy photon data. We use two custom pipelines: one to search for prompt gamma-ray counterparts in GBM, and the other to search for a variety of X-ray afterglow model signals in ASM. We measure the efficiency of the joint pipelines to weak gamma-ray burst counterparts, and a family of model X-ray afterglows. By requiring a detectable signal in either electromagnetic instrument coincident with a GW event, we are able to reject a large majority of GW candidates. This reduces the signal-to-noise ratio of the loudest surviving GW background event by around 15-20 percent.

  11. HIGH-ENERGY ELECTROMAGNETIC OFFLINE FOLLOW-UP OF LIGO-VIRGO GRAVITATIONAL-WAVE BINARY COALESCENCE CANDIDATE EVENTS

    SciTech Connect

    Blackburn, L.; Camp, J.; Christensen, N.; Remillard, R. A.; Veitch, J.

    2015-03-15

    We present two different search methods for electromagnetic counterparts to gravitational-wave (GW) events from ground-based detectors using archival NASA high-energy data from the Fermi Gamma-ray Burst Monitor (GBM) and RXTE All-sky Monitor (ASM) instruments. To demonstrate the methods, we use a limited number of representative GW background noise events produced by a search for binary neutron star coalescence over the last two months of the LIGO-Virgo S6/VSR3 joint science run. Time and sky location provided by the GW data trigger a targeted search in the high-energy photon data. We use two custom pipelines: one to search for prompt gamma-ray counterparts in GBM, and the other to search for a variety of X-ray afterglow model signals in ASM. We measure the efficiency of the joint pipelines to weak gamma-ray burst counterparts, and a family of model X-ray afterglows. By requiring a detectable signal in either electromagnetic instrument coincident with a GW event, we are able to reject a large majority of GW candidates. This reduces the signal-to-noise ratio of the loudest surviving GW background event by around 15–20%.

  12. A Dark Energy Camera Search for an Optical Counterpart to the First Advanced LIGO Gravitational Wave Event GW150914

    DOE PAGES

    Soares-Santos, M.

    2016-05-27

    We report initial results of a deep search for an optical counterpart to the gravitational wave event GW150914, the first trigger from the Advanced LIGO gravitational wave detectors. We used the Dark Energy Camera (DECam) to image a 102 degmore » $^2$ area, corresponding to 38% of the initial trigger high-probability sky region and to 11% of the revised high-probability region. We observed in i and z bands at 4-5, 7, and 24 days after the trigger. The median $$5\\sigma$$ point-source limiting magnitudes of our search images are i=22.5 and z=21.8 mag. We processed the images through a difference-imaging pipeline using templates from pre-existing Dark Energy Survey data and publicly available DECam data. Due to missing template observations and other losses, our effective search area subtends 40 deg$$^{2}$$, corresponding to 12% total probability in the initial map and 3% of the final map. In this area, we search for objects that decline significantly between days 4-5 and day 7, and are undetectable by day 24, finding none to typical magnitude limits of i= 21.5,21.1,20.1 for object colors (i-z)=1,0,-1, respectively. Our search demonstrates the feasibility of a dedicated search program with DECam and bodes well for future research in this emerging field.« less

  13. A Dark Energy Camera Search for an Optical Counterpart to the First Advanced LIGO Gravitational Wave Event GW150914

    SciTech Connect

    Soares-Santos, M.

    2016-05-27

    We report initial results of a deep search for an optical counterpart to the gravitational wave event GW150914, the first trigger from the Advanced LIGO gravitational wave detectors. We used the Dark Energy Camera (DECam) to image a 102 deg$^2$ area, corresponding to 38% of the initial trigger high-probability sky region and to 11% of the revised high-probability region. We observed in i and z bands at 4-5, 7, and 24 days after the trigger. The median $5\\sigma$ point-source limiting magnitudes of our search images are i=22.5 and z=21.8 mag. We processed the images through a difference-imaging pipeline using templates from pre-existing Dark Energy Survey data and publicly available DECam data. Due to missing template observations and other losses, our effective search area subtends 40 deg$^{2}$, corresponding to 12% total probability in the initial map and 3% of the final map. In this area, we search for objects that decline significantly between days 4-5 and day 7, and are undetectable by day 24, finding none to typical magnitude limits of i= 21.5,21.1,20.1 for object colors (i-z)=1,0,-1, respectively. Our search demonstrates the feasibility of a dedicated search program with DECam and bodes well for future research in this emerging field.

  14. New Methods for Identifying Nearby Gravitational Lenses in All-Sky Surveys

    NASA Astrophysics Data System (ADS)

    McCandlish, Samuel; Di Stefano, R.

    2011-01-01

    All-sky catalogs provide a wealth of information about gravitational lensing events that has not yet been utilized. We present a method for matching lensing events to catalogs and finding the probability that the association is genuine. Given a likely candidate for the lens object associated with an event, it is possible to break the inherent degeneracy in microlensing and estimate the mass of the lens, depending on its distance. Eight percent of microlensing events have matches in the 2MASS catalog, and there are many more matches in catalogs that cover other wave bands. In addition to detecting the associated lens or source, it is possible that the cataloged object is a companion or host to the actual lens. This opens up the possibility of finding dark nearby lenses, such as stellar remnants or planets that are associated with cataloged objects. We propose various methods for determining which events are most likely to be caused by nearby lenses, and apply them to our matches. We present some interesting matched objects and the results of observations of those objects. This work is supported in part by the NSF REU and DOD ASSURE programs under NSF grant no. 0754568 and by the Smithsonian Institution.

  15. The Exoplanet Microlensing Survey by the Proposed WFIRST Observatory

    NASA Technical Reports Server (NTRS)

    Barry, Richard; Kruk, Jeffrey; Anderson, Jay; Beaulieu, Jean-Philippe; Bennett, David P.; Catanzarite, Joseph; Cheng, Ed; Gaudi, Scott; Gehrels, Neil; Kane, Stephen; Lunine, Jonathan; Sumi, Takahiro; Tanner, Angelle; Traub, Wesley

    2012-01-01

    The New Worlds, New Horizons report released by the Astronomy and Astrophysics Decadal Survey Board in 2010 listed the Wide Field Infrared Survey Telescope (WFIRST) as the highest-priority large space mission for the . coming decade. This observatory will provide wide-field imaging and slitless spectroscopy at near infrared wavelengths. The scientific goals are to obtain a statistical census of exoplanets using gravitational microlensing. measure the expansion history of and the growth of structure in the Universe by multiple methods, and perform other astronomical surveys to be selected through a guest observer program. A Science Definition Team has been established to assist NASA in the development of a Design Reference Mission that accomplishes this diverse array of science programs with a single observatory. In this paper we present the current WFIRST payload concept and the expected capabilities for planet detection. The observatory. with science goals that are complimentary to the Kepler exoplanet transit mission, is designed to complete the statistical census of planetary systems in the Galaxy, from habitable Earth-mass planets to free floating planets, including analogs to all of the planets in our Solar System except Mercury. The exoplanet microlensing survey will observe for 500 days spanning 5 years. This long temporal baseline will enable the determination of the masses for most detected exoplanets down to 0.1 Earth masses.

  16. Using HST to Detect Isolated Black Holes and Neutron Stars through Astrometric Microlensing

    NASA Astrophysics Data System (ADS)

    Sahu, Kailash C.; Albrow, M.; Anderson, J.; Bond, H. E.; Bond, I.; Brown, T. M.; Casertano, S.; Dominik, M.; Ferguson, H. C.; Fryer, C.; Livio, M.; Mao, S.; Perrott, Y.; Udalski, A.; Yock, P.

    2012-05-01

    To date, Black Hole (BH) and Neutron Star (NS) masses have been directly measured only in binaries; no isolated stellar-mass BH has been detected unambiguously within our Galaxy. We have underway a large, 3-year HST program (192 orbits) designed to detect microlensing events caused by non-luminous isolated BHs and NSs in the direction of the Galactic bulge. Our program consists of monitoring of 12 fields in the Sagittarius window of the Galactic bulge, containing a total of 1.5 million stars down to V=28. Our observations have a typical cadence of one observation every two weeks, and are primarily targeted towards detecting microlensing events caused by non-luminous isolated BHs and NSs in the Galactic disk and bulge. The unique capability of HST imaging for microlensing observations is the addition of high-precision astrometry, allowing detection of the astrometric shift of the source during the event. Combined with the lens parallax, which can be determined from the light curve as measured by HST (and supplemented by GEMINI) observations, the astrometric shift provides a direct measurement of the lens mass. Our program is optimized to detect long-duration events, which are more likely to be caused by massive lenses. We expect to detect a few dozen long-duration microlensing events, of which 45% will show astrometric deflections, leading to direct determinations of the lens masses.

  17. CAN THE MASSES OF ISOLATED PLANETARY-MASS GRAVITATIONAL LENSES BE MEASURED BY TERRESTRIAL PARALLAX?

    SciTech Connect

    Freeman, M.; Botzler, C. S.; Bray, J. C.; Cherrie, J. M.; Rattenbury, N. J.; Philpott, L. C.; Abe, F.; Muraki, Y.; Albrow, M. D.; Bennett, D. P.; Bond, I. A.; Christie, G. W.; Natusch, T.; Dionnet, Z.; Gould, A.; Han, C.; Heyrovský, D.; McCormick, J. M.; Skowron, J.; and others

    2015-02-01

    Recently Sumi et al. reported evidence for a large population of planetary-mass objects (PMOs) that are either unbound or orbit host stars in orbits ≥10 AU. Their result was deduced from the statistical distribution of durations of gravitational microlensing events observed by the MOA collaboration during 2006 and 2007. Here we study the feasibility of measuring the mass of an individual PMO through microlensing by examining a particular event, MOA-2011-BLG-274. This event was unusual as the duration was short, the magnification high, the source-size effect large, and the angular Einstein radius small. Also, it was intensively monitored from widely separated locations under clear skies at low air masses. Choi et al. concluded that the lens of the event may have been a PMO but they did not attempt a measurement of its mass. We report here a re-analysis of the event using re-reduced data. We confirm the results of Choi et al. and attempt a measurement of the mass and distance of the lens using the terrestrial parallax effect. Evidence for terrestrial parallax is found at a 3σ level of confidence. The best fit to the data yields the mass and distance of the lens as 0.80 ± 0.30 M {sub J} and 0.80 ± 0.25 kpc respectively. We exclude a host star to the lens out to a separation ∼40 AU. Drawing on our analysis of MOA-2011-BLG-274 we propose observational strategies for future microlensing surveys to yield sharper results on PMOs including those down to super-Earth mass.

  18. Stochastic Template Bank for Gravitational Wave Searches for Precessing Neutron Star-Black Hole Coalescence Events

    NASA Technical Reports Server (NTRS)

    Indik, Nathaniel; Haris, K.; Dal Canton, Tito; Fehrmann, Henning; Krishnan, Badri; Lundgren, Andrew; Nielsen, Alex B.; Pai, Archana

    2017-01-01

    Gravitational wave searches to date have largely focused on non-precessing systems. Including precession effects greatly increases the number of templates to be searched over. This leads to a corresponding increase in the computational cost and can increase the false alarm rate of a realistic search. On the other hand, there might be astrophysical systems that are entirely missed by non-precessing searches. In this paper we consider the problem of constructing a template bank using stochastic methods for neutron star-black hole binaries allowing for precession, but with the restrictions that the total angular momentum of the binary is pointing toward the detector and that the neutron star spin is negligible relative to that of the black hole. We quantify the number of templates required for the search, and we explicitly construct the template bank. We show that despite the large number of templates, stochastic methods can be adapted to solve the problem. We quantify the parameter space region over which the non-precessing search might miss signals.

  19. Wide-field X-ray afterglow searches for gravitational wave events

    NASA Astrophysics Data System (ADS)

    Shawhan, Peter; Tervala, Justin

    2015-04-01

    The Advanced LIGO and Virgo gravitational wave (GW) detectors are on track to begin collecting science data soon and to reach full sensitivity by 2019. Low-latency analysis of the GW data will provide triggers for astronomers to seek electromagnetic transient counterparts. Many instruments will contribute to that effort, but instruments with very large fields of view will have a natural advantage for following up the typically large GW error regions. In particular, we consider ISS-Lobster, a proposed NASA mission to be deployed on the International Space Station, which features a focusing imager for soft X-rays with a field of view of over 800 square degrees. Our study using binary neutron star coalescence simulations from Singer et al. shows that a single ISS-Lobster pointing will, on average, cover over 95% of a LIGO-Virgo 3-detector sky map, while even a 2-detector sky map can be over 85% covered (on average) by a sequence of four pointings. We gratefully acknowledge the support of NSF Grants PHY-1068549 and PHY-1404121.

  20. Microlenses and their applications in endoscopes

    NASA Astrophysics Data System (ADS)

    Zeng, Xuefeng

    Microlenses have been developed in the past and play an important role in many fields, including optical communication, photolithography, imaging systems and lab on chips. Microlenses with fixed focal length and tunable focus have their individual applications. Several methods and mechanisms have been reported to realize microlenses; however, they have their advantages and disadvantages. In this work, two kinds of microlenses are studied: microlens arrays with fixed focal length and liquid tunable-focus microlenses actuated by stimuli-responsive hydrogels. The design, fabrication, testing and applications of these microlenses are explored. The gist of these microlenses is to utilize surface tension of liquid-air and/or immiscible liquid-liquid interfaces because surface tension dominates over gravity at the micro-scale. Microlens arrays with fixed focal length, made of polydimethylsiloxane (PDMS), are fabricated through liquid-phase photopolymerization and molding. Liquid menisci of photopolymerizable solutions at liquid-air interfaces are first formed and cured under ultraviolet (UV) radiance to obtain the mold. The resultant polymerized mold is then transferred to PDMS utilizing two molding steps to form a microlens array. The liquid tunable-focus microlens is formed by a water-oil interface that is pinned at a hydrophobic-hydrophilic boundary at the top edge of an aperture. Multiple hydrogel microstructures, whose volume is responsive to a certain stimuli, are formed around the lens aperture under UV radiance and regulate the pressure across the meniscus of the water-oil interface, varying the focal length of the microlens. The liquid tunable-focus microlenses responsive to infrared (IR) light are integrated at the end of fiber endoscopes and can scan the areas of interest with minimal back-and-forth movements of the scopes themselves. The operation of the microlens and the image acquisition are realized through light transmitted via optical fibers. Benefitting

  1. Possible microlensing in the Galactic Disk

    NASA Astrophysics Data System (ADS)

    Udalski, Andrzej; Szymanski, Michal

    1999-02-01

    The OGLE Early Warning System triggered a microlensing candidate located in the Galactic disk field in Carina. The I=18.0 mag (V=19.6) star designated CAR_SC2 24589 (RA2000=11:07:26.72, DEC2000=-61:22:30.6, l=290.8,b=-1.0) is currently brightening with the light curve consistent with microlensing rise of brightness.

  2. RTT-150 detected the new brightening of the Gaia16aye binary microlensing system

    NASA Astrophysics Data System (ADS)

    Khamitov, I.; Bikmaev, I.; Burenin, R.; Grebenev, S.; Tkachenko, A.; Irtuganov, E.; Melnikov, S.; Sakhibullin, N.; Pavlinsky, M.; Sunyaev, R.; Esenoglu, H.; Koseoglu, D.; Bakis, V.; Sipahi, E.

    2016-11-01

    The 1.5-m Russian-Turkish optical telescope RTT-150 (Antalya, Turkey) monitored the Galactic transient Gaia16aye, suspected to be the first binary microlensing event ever discovered towards the Galactic Plane (ATel #9376, #9507), since Sep. 25, 2016.

  3. GW150914: First Search for the Electromagnetic Counterpart of a Gravitational-wave Event by the TOROS Collaboration

    NASA Astrophysics Data System (ADS)

    Díaz, Mario C.; Beroiz, Martín; Peñuela, Tania; Macri, Lucas M.; Oelkers, Ryan J.; Yuan, Wenlong; García Lambas, Diego; Cabral, Juan; Colazo, Carlos; Domínguez, Mariano; Sánchez, Bruno; Gurovich, Sebastián; Lares, Marcelo; Schneiter, Matías; Graña, Darío; Renzi, Víctor; Rodriguez, Horacio; Starck, Manuel; Vrech, Rubén; Artola, Rodolfo; Chiavassa Ferreyra, Antonio; Girardini, Carla; Quiñones, Cecilia; Tapia, Luis; Tornatore, Marina; Marshall, Jennifer L.; DePoy, Darren L.; Branchesi, Marica; Brocato, Enzo; Padilla, Nelson; Pereyra, Nicolas A.; Mukherjee, Soma; Benacquista, Matthew; Key, Joey

    2016-09-01

    We present the results of the optical follow-up conducted by the TOROS collaboration of the first gravitational-wave event GW150914. We conducted unfiltered CCD observations (0.35-1 μm) with the 1.5 m telescope at Bosque Alegre starting ˜2.5 days after the alarm. Given our limited field of view (˜100 arcmin2), we targeted 14 nearby galaxies that were observable from the site and were located within the area of higher localization probability. We analyzed the observations using two independent implementations of difference-imaging algorithms, followed by a Random-Forest-based algorithm to discriminate between real and bogus transients. We did not find any bona fide transient event in the surveyed area down to a 5σ limiting magnitude of r = 21.7 mag (AB). Our result is consistent with the LIGO detection of a binary black hole merger, for which no electromagnetic counterparts are expected, and with the expected rates of other astrophysical transients.

  4. Halo Microlensing and Dark Baryons

    NASA Astrophysics Data System (ADS)

    Crotts, A. P. S.

    1993-12-01

    (While Pierce lectures review past accomplishments, customarily, this talk concerns efforts which we have pursued for some years and which are now reaching fruition. We present elsewhere at this meeting results from research cited for the Prize.) Dark matter exists in the halos of spiral galaxies, and the least radical alternative for its identity is normal matter produced by primordial nucleosynthesis. This matter could easily be hidden in large, condensed objects. Paczynski pointed out in 1986 that if condensations of Galactic halo matter are sufficiently massive, they will produce detectable amplification of background starlight by gravitational lensing. Several groups recently reported possible detections of this effect after surveying large numbers of stars in the Galactic Bulge and LMC. The connection between these events and massive, dark halos is unclear and likely to remain so for some time, given the rate at which they are detected. Following Paczynski's realization, we stressed that a much higher event rate, a statistical control sample, sensitivity to a much broader mass range, and modulation of the predicted lensing rate with galactocentric distance can all be realized by a different experiment: observing the halo of M31 (and the Galaxy) using stars in M31. In some ways, M31 is a more difficult target than the LMC or the Bulge, given the faintness of its stars, but our observations in 1991 and 1993 indicate that these problems have been surmounted. We can detect stellar variability even under extremely crowded conditions like those in M31's inner disk, and can monitor a sufficient number of stars to study halo lensing. We present results from our initial survey which indicates that the required sensitivity can be reached to confirm or reject the hypothesis that sub-solar masses like those detected in our Galaxy make up the missing spiral galaxy mass. It is possible that we may use the data already obtained (and still being analyzed) to place

  5. Is the Gravitational-Wave Ringdown a Probe of the Event Horizon?

    PubMed

    Cardoso, Vitor; Franzin, Edgardo; Pani, Paolo

    2016-04-29

    It is commonly believed that the ringdown signal from a binary coalescence provides a conclusive proof for the formation of an event horizon after the merger. This expectation is based on the assumption that the ringdown waveform at intermediate times is dominated by the quasinormal modes of the final object. We point out that this assumption should be taken with great care, and that very compact objects with a light ring will display a similar ringdown stage, even when their quasinormal-mode spectrum is completely different from that of a black hole. In other words, universal ringdown waveforms indicate the presence of light rings, rather than of horizons. Only precision observations of the late-time ringdown signal, where the differences in the quasinormal-mode spectrum eventually show up, can be used to rule out exotic alternatives to black holes and to test quantum effects at the horizon scale.

  6. MOA-2011-BLG-322Lb: a `second generation survey' microlensing planet

    NASA Astrophysics Data System (ADS)

    Shvartzvald, Y.; Maoz, D.; Kaspi, S.; Sumi, T.; Udalski, A.; Gould, A.; Bennett, D. P.; Han, C.; Abe, F.; Bond, I. A.; Botzler, C. S.; Freeman, M.; Fukui, A.; Fukunaga, D.; Itow, Y.; Koshimoto, N.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Namba, S.; Ohnishi, K.; Rattenbury, N. J.; Saito, To.; Sullivan, D. J.; Sweatman, W. L.; Suzuki, D.; Tristram, P. J.; Wada, K.; Yock, P. C. M.; Skowron, J.; Kozłowski, S.; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Ulaczyk, K.; Wyrzykowski, Ł.; Poleski, R.; Pietrukowicz, P.

    2014-03-01

    Global `second-generation' microlensing surveys aim to discover and characterize extrasolar planets and their frequency, by means of round-the-clock high-cadence monitoring of a large area of the Galactic bulge, in a controlled experiment. We report the discovery of a giant planet in microlensing event MOA-2011-BLG-322. This moderate-magnification event, which displays a clear anomaly induced by a second lensing mass, was inside the footprint of our second-generation microlensing survey, involving MOA, OGLE and the Wise Observatory. The event was observed by the survey groups, without prompting alerts that could have led to dedicated follow-up observations. Fitting a microlensing model to the data, we find that the time-scale of the event was tE = 23.2 ± 0.8 d, and the mass ratio between the lens star and its companion is q = 0.028 ± 0.001. Finite-source effects are marginally detected, and upper limits on them help break some of the degeneracy in the system parameters. Using a Bayesian analysis that incorporates a Galactic structure model, we estimate the mass of the lens at 0.39^{+0.45}_{-0.19} M_{⊙}, at a distance of 7.56 ± 0.91 kpc. Thus, the companion is likely a planet of mass 11.6^{+13.4}_{-5.6} M_J, at a projected separation of 4.3^{+1.5}_{-1.2} AU, rather far beyond the snow line. This is the first pure-survey planet reported from a second-generation microlensing survey, and shows that survey data alone can be sufficient to characterize a planetary model. With the detection of additional survey-only planets, we will be able to constrain the frequency of extrasolar planets near their systems' snow lines.

  7. Event Rate for LISA Gravitational Wave Signals from Black Hole-Massive Black Hole Coalescences

    NASA Technical Reports Server (NTRS)

    Bender, Peter L.; Salamon, Michael H. (Technical Monitor)

    2002-01-01

    Earlier work under a previous grant had been mainly on investigating the event rate for coalescences of white dwarfs or neutron stars with massive black holes (MBHs) in galactic nuclei. Under the new grant, two studies were undertaken. One was an approximate extension of the earlier study to stellar mass black holes as the lighter object, with masses in the range of roughly 3 to 20 M_sun, rather than about 1 M_sun. The other was an improved estimate of the confusion noise due to galactic binaries against which the signals from BH-MDH coalescences would have to be detected. In the earlier work, the mass of the white dwarfs (WDs) and neutron stars (NSs) was assumed to be about the same as that of the unevolved stars in the density cusp around the galactic center MBH. However, with the BH mass being substantially larger, the sinking down of BHs toward the center (mass segregation) became important and was included in the model. A single representative mass of 7 M_sun was used.

  8. Caustic Structures and Detectability of Circumbinary Planets in Microlensing

    NASA Astrophysics Data System (ADS)

    Luhn, Jacob K.; Penny, Matthew T.; Gaudi, B. Scott

    2016-08-01

    Recent discoveries of circumbinary planets in Kepler data show that there is a viable channel of planet formation around binary main-sequence stars. Motivated by these discoveries, we have investigated the caustic structures and detectability of circumbinary planets in microlensing events. We have produced a suite of animations of caustics as a function of the projected separation and angle of the binary host to efficiently explore caustic structures over the entire circumbinary parameter space. Aided by these animations, we have derived a semi-empirical analytic expression for the location of planetary caustics, which are displaced in circumbinary lenses relative to those of planets with a single host. We have used this expression to show that the dominant source of caustic motion will be due to the planet’s orbital motion and not that of the binary star. Finally, we estimate the fraction of circumbinary microlensing events that are recognizable as such to be significant (5%-50%) for binary projected separations in the range 0.1-0.5 in units of Einstein radii.

  9. Microlensing planet detection via geosynchronous and low Earth orbit satellites

    NASA Astrophysics Data System (ADS)

    Mogavero, F.; Beaulieu, J. P.

    2016-01-01

    Planet detection through microlensing is usually limited by a well-known degeneracy in the Einstein timescale tE, which prevents mass and distance of the lens to be univocally determined. It has been shown that a satellite in geosynchronous orbit could provide masses and distances for most standard planetary events (tE ≈ 20 days) via a microlens parallax measurement. This paper extends the analysis to shorter Einstein timescales, tE ≈ 1 day, when dealing with the case of Jupiter-mass lenses. We then study the capabilities of a low Earth orbit satellite on even shorter timescales, tE ≈ 0.1 days. A Fisher matrix analysis is employed to predict how the 1-σ error on parallax depends on tE and the peak magnification of the microlensing event. It is shown that a geosynchronous satellite could detect parallaxes for Jupiter-mass free floaters and discover planetary systems around very low-mass brown dwarfs. Moreover, a low Earth orbit satellite could lead to the discovery of Earth-mass free-floating planets. Limitations to these results can be the strong requirements on the photometry, the effects of blending, and in the case of the low orbit, the Earth's umbra.

  10. A Dark Energy Camera Search for an Optical Counterpart to the First Advanced LIGO Gravitational Wave Event GW150914

    NASA Astrophysics Data System (ADS)

    Soares-Santos, M.; Kessler, R.; Berger, E.; Annis, J.; Brout, D.; Buckley-Geer, E.; Chen, H.; Cowperthwaite, P. S.; Diehl, H. T.; Doctor, Z.; Drlica-Wagner, A.; Farr, B.; Finley, D. A.; Flaugher, B.; Foley, R. J.; Frieman, J.; Gruendl, R. A.; Herner, K.; Holz, D.; Lin, H.; Marriner, J.; Neilsen, E.; Rest, A.; Sako, M.; Scolnic, D.; Sobreira, F.; Walker, A. R.; Wester, W.; Yanny, B.; Abbott, T. M. C.; Abdalla, F. B.; Allam, S.; Armstrong, R.; Banerji, M.; Benoit-Lévy, A.; Bernstein, R. A.; Bertin, E.; Brown, D. A.; Burke, D. L.; Capozzi, D.; Carnero Rosell, A.; Carrasco Kind, M.; Carretero, J.; Castander, F. J.; Cenko, S. B.; Chornock, R.; Crocce, M.; D'Andrea, C. B.; da Costa, L. N.; Desai, S.; Dietrich, J. P.; Drout, M. R.; Eifler, T. F.; Estrada, J.; Evrard, A. E.; Fairhurst, S.; Fernandez, E.; Fischer, J.; Fong, W.; Fosalba, P.; Fox, D. B.; Fryer, C. L.; Garcia-Bellido, J.; Gaztanaga, E.; Gerdes, D. W.; Goldstein, D. A.; Gruen, D.; Gutierrez, G.; Honscheid, K.; James, D. J.; Karliner, I.; Kasen, D.; Kent, S.; Kuropatkin, N.; Kuehn, K.; Lahav, O.; Li, T. S.; Lima, M.; Maia, M. A. G.; Margutti, R.; Martini, P.; Matheson, T.; McMahon, R. G.; Metzger, B. D.; Miller, C. J.; Miquel, R.; Mohr, J. J.; Nichol, R. C.; Nord, B.; Ogando, R.; Peoples, J.; Plazas, A. A.; Quataert, E.; Romer, A. K.; Roodman, A.; Rykoff, E. S.; Sanchez, E.; Scarpine, V.; Schindler, R.; Schubnell, M.; Sevilla-Noarbe, I.; Sheldon, E.; Smith, M.; Smith, N.; Smith, R. C.; Stebbins, A.; Sutton, P. J.; Swanson, M. E. C.; Tarle, G.; Thaler, J.; Thomas, R. C.; Tucker, D. L.; Vikram, V.; Wechsler, R. H.; Weller, J.; DES Collaboration

    2016-06-01

    We report the results of a deep search for an optical counterpart to the gravitational wave (GW) event GW150914, the first trigger from the Advanced LIGO GW detectors. We used the Dark Energy Camera (DECam) to image a 102 deg2 area, corresponding to 38% of the initial trigger high-probability sky region and to 11% of the revised high-probability region. We observed in the i and z bands at 4-5, 7, and 24 days after the trigger. The median 5σ point-source limiting magnitudes of our search images are i = 22.5 and z = 21.8 mag. We processed the images through a difference-imaging pipeline using templates from pre-existing Dark Energy Survey data and publicly available DECam data. Due to missing template observations and other losses, our effective search area subtends 40 deg2, corresponding to a 12% total probability in the initial map and 3% in the final map. In this area, we search for objects that decline significantly between days 4-5 and day 7, and are undetectable by day 24, finding none to typical magnitude limits of i = 21.5, 21.1, 20.1 for object colors (i - z) = 1, 0, -1, respectively. Our search demonstrates the feasibility of a dedicated search program with DECam and bodes well for future research in this emerging field.

  11. The Angstrom Project: a new microlensing candidate

    NASA Astrophysics Data System (ADS)

    Kerins, E.; Darnley, M. J.; Newsam, A. M.; Duke, J. P.; Gould, A.; Street, C. Han B.-G. Park R. A.

    2008-12-01

    We report the discovery of a new microlensing candidate in M31 by the Angstrom Project M31 bulge microlensing survey using the Liverpool Telescope (La Palma). The candidate was discovered using difference imaging techniques by the Angstrom Project Alert System (APAS) in a series of Sloan i'-band images of the bulge of M31.

  12. Direct Laser Printing of Tailored Polymeric Microlenses.

    PubMed

    Florian, Camilo; Piazza, Simonluca; Diaspro, Alberto; Serra, Pere; Duocastella, Martí

    2016-07-13

    We report a laser-based approach for the fast fabrication of high-optical-quality polymeric microlenses and microlens arrays with controllable geometry and size. Our strategy consists of the direct laser printing of microdroplets of a highly viscous UV prepolymer at targeted positions, followed by photocuring. We study the morphological characteristics and imaging performance of the microlenses as a function of the substrate and laser parameters and investigate optimal printing conditions and printing mechanisms. We show that the microlens size and focusing properties can be easily tuned by the laser pulse energy, with minimum volumes below 20 fL and focal lengths ranging from 7 to 50 μm.

  13. Augmenting WFIRST Microlensing with a Ground-Based Telescope Network

    NASA Astrophysics Data System (ADS)

    Zhu, Wei; Gould, Andrew

    2016-06-01

    Augmenting the Wide Field Infrared Survey Telescope (WFIRST) microlensing campaigns with intensive observations from a ground-based network of wide-field survey telescopes would have several major advantages. First, it would enable full two-dimensional (2-D) vector microlens parallax measurements for a substantial fraction of low-mass lenses as well as planetary and binary events that show caustic crossing features. For a significant fraction of the free-floating planet (FFP) events and all caustic-crossing planetary/binary events, these 2-D parallax measurements directly lead to complete solutions (mass, distance, transverse velocity) of the lens object (or lens system). For even more events, the complementary ground-based observations will yield 1-D parallax measurements. Together with the 1-D parallaxes from WFIRST alone, they can probe the entire mass range M > M_Earth. For luminous lenses, such 1-D parallax measurements can be promoted to complete solutions (mass, distance, transverse velocity) by high-resolution imaging. This would provide crucial information not only about the hosts of planets and other lenses, but also enable a much more precise Galactic model. Other benefits of such a survey include improved understanding of binaries (particularly with low mass primaries), and sensitivity to distant ice-giant and gas-giant companions of WFIRST lenses that cannot be detected by WFIRST itself due to its restricted observing windows. Existing ground-based microlensing surveys can be employed if WFIRST is pointed at lower-extinction fields than is currently envisaged. This would come at some cost to the event rate. Therefore the benefits of improved characterization of lenses must be weighed against these costs.

  14. Two Stars Two Ways: Confirming a Microlensing Binary Lens Solution with a Spectroscopic Measurement of the Orbit

    NASA Astrophysics Data System (ADS)

    Yee, Jennifer C.; Johnson, John Asher; Skowron, Jan; Gould, Andrew; Pineda, J. Sebastian; Eastman, Jason; Vanderburg, Andrew; Howard, Andrew

    2016-04-01

    Light curves of microlensing events involving stellar binaries and planetary systems can provide information about the orbital elements of the system due to orbital modulations of the caustic structure. Accurately measuring the orbit in either the stellar or planetary case requires detailed modeling of subtle deviations in the light curve. At the same time, the natural, Cartesian parameterization of a microlensing binary is partially degenerate with the microlens parallax. Hence, it is desirable to perform independent tests of the predictions of microlens orbit models using radial velocity (RV) time series of the lens binary system. To this end, we present 3.5 years of RV monitoring of the binary lens system OGLE-2009-BLG-020 L, for which Skowron et al. constrained all internal parameters of the 200-700 day orbit. Our RV measurements reveal an orbit that is consistent with the predictions of the microlens light curve analysis, thereby providing the first confirmation of orbital elements inferred from microlensing events.

  15. The NuSTAR spectrum of Mrk 335: extreme relativistic effects within two gravitational radii of the event horizon?

    NASA Astrophysics Data System (ADS)

    Parker, M. L.; Wilkins, D. R.; Fabian, A. C.; Grupe, D.; Dauser, T.; Matt, G.; Harrison, F. A.; Brenneman, L.; Boggs, S. E.; Christensen, F. E.; Craig, W. W.; Gallo, L. C.; Hailey, C. J.; Kara, E.; Komossa, S.; Marinucci, A.; Miller, J. M.; Risaliti, G.; Stern, D.; Walton, D. J.; Zhang, W. W.

    2014-09-01

    We present 3-50 keV NuSTAR observations of the active galactic nuclei Mrk 335 in a very low flux state. The spectrum is dominated by very strong features at the energies of the iron line at 5-7 keV and Compton hump from 10-30 keV. The source is variable during the observation, with the variability concentrated at low energies, which suggesting either a relativistic reflection or a variable absorption scenario. In this work, we focus on the reflection interpretation, making use of new relativistic reflection models that self consistently calculate the reflection fraction, relativistic blurring and angle-dependent reflection spectrum for different coronal heights to model the spectra. We find that the spectra can be well fitted with relativistic reflection, and that the lowest flux state spectrum is described by reflection alone, suggesting the effects of extreme light-bending occurring within ˜2 gravitational radii (RG) of the event horizon. The reflection fraction decreases sharply with increasing flux, consistent with a point source moving up to above 10 RG as the source brightens. We constrain the spin parameter to greater than 0.9 at the 3σ confidence level. By adding a spin-dependent upper limit on the reflection fraction to our models, we demonstrate that this can be a powerful way of constraining the spin parameter, particularly in reflection dominated states. We also calculate a detailed emissivity profile for the iron line, and find that it closely matches theoretical predictions for a compact source within a few RG of the black hole.

  16. Chalcogenide glass microlenses by inkjet printing

    SciTech Connect

    Sanchez, Eric A.; Waldmann, Maike; Arnold, Craig B.

    2011-05-10

    We demonstrate micrometer scale mid-IR lenses for integrated optics, using solution-based inkjet printing techniques and subsequent processing. Arsenic sulfide spherical microlenses with diameters of 10-350 {mu}m and focal lengths of 10-700 {mu}m have been fabricated. The baking conditions can be used to tune the precise focal length.

  17. THE EFFECT OF A TIME-VARYING ACCRETION DISK SIZE ON QUASAR MICROLENSING LIGHT CURVES

    SciTech Connect

    Blackburne, Jeffrey A.; Kochanek, Christopher S. E-mail: ckochanek@astronomy.ohio-state.ed

    2010-08-01

    Microlensing perturbations to the magnification of gravitationally lensed quasar images are dependent on the angular size of the quasar. If quasar variability at visible wavelengths is caused by a change in the area of the accretion disk, it will affect the microlensing magnification. We derive the expected signal, assuming that the luminosity scales with some power of the disk area, and estimate its amplitude using simulations. We discuss the prospects for detecting the effect in real-world data and for using it to estimate the logarithmic slope of the luminosity's dependence on disk area. Such an estimate would provide a direct test of the standard thin accretion disk model. We tried fitting six seasons of the light curves of the lensed quasar HE 0435-1223 including this effect as a modification to the Kochanek et al. approach to estimating time delays. We find a dramatic improvement in the goodness of fit and relatively plausible parameters, but a robust estimate will require a full numerical calculation in order to correctly model the strong correlations between the structure of the microlensing magnification patterns and the magnitude of the effect. We also comment briefly on the effect of this phenomenon for the stability of time-delay estimates.

  18. One or more bound planets per Milky Way star from microlensing observations.

    PubMed

    Cassan, A; Kubas, D; Beaulieu, J-P; Dominik, M; Horne, K; Greenhill, J; Wambsganss, J; Menzies, J; Williams, A; Jørgensen, U G; Udalski, A; Bennett, D P; Albrow, M D; Batista, V; Brillant, S; Caldwell, J A R; Cole, A; Coutures, Ch; Cook, K H; Dieters, S; Prester, D Dominis; Donatowicz, J; Fouqué, P; Hill, K; Kains, N; Kane, S; Marquette, J-B; Martin, R; Pollard, K R; Sahu, K C; Vinter, C; Warren, D; Watson, B; Zub, M; Sumi, T; Szymański, M K; Kubiak, M; Poleski, R; Soszynski, I; Ulaczyk, K; Pietrzyński, G; Wyrzykowski, L

    2012-01-11

    Most known extrasolar planets (exoplanets) have been discovered using the radial velocity or transit methods. Both are biased towards planets that are relatively close to their parent stars, and studies find that around 17-30% (refs 4, 5) of solar-like stars host a planet. Gravitational microlensing, on the other hand, probes planets that are further away from their stars. Recently, a population of planets that are unbound or very far from their stars was discovered by microlensing. These planets are at least as numerous as the stars in the Milky Way. Here we report a statistical analysis of microlensing data (gathered in 2002-07) that reveals the fraction of bound planets 0.5-10 AU (Sun-Earth distance) from their stars. We find that 17(+6)(-9)% of stars host Jupiter-mass planets (0.3-10 M(J), where M(J) = 318 M(⊕) and M(⊕) is Earth's mass). Cool Neptunes (10-30 M(⊕)) and super-Earths (5-10 M(⊕)) are even more common: their respective abundances per star are 52(+22)(-29)% and 62(+35)(-37)%. We conclude that stars are orbited by planets as a rule, rather than the exception.

  19. Accurate Mass Determination of the Ancient White Dwarf ER 8 Through Astrometric Microlensing

    NASA Astrophysics Data System (ADS)

    Sahu, Kailash

    2005-07-01

    We propose to determine the mass of the very cool white dwarf ER 8 through astrometric microlensing. We have predicted that ER 8 will pass very close to a 15th-mag background star in January 2006, with an impact parameter of less than 0.05 arcsec. As it passes in front, it will cause a deflection of the background star's image by >8 milliarcsec, an amount easily detectable with HST/FGS. The gravitational deflection angle depends only on the distances and relative positions of the stars, and on the mass of the white dwarf. Since the distances and positions can be determined precisely before the event, the astrometric measurement offers a unique and direct method to measure the mass of the white dwarf to high accuracy {<5%}. Unlike all other stellar mass determinations, this technique works for single stars {but only if they are nearby and of sufficient mass}. The mass of ER 8 is of special interest because it is a member of the Galactic halo, and appears to be the oldest known field white dwarf. This object can thus set a lower limit on the age of the Galactic halo, but since white-dwarf cooling rates depend on their masses, the mass is a necessary ingredient in the age determination. As a byproduct, we will obtain an accurate parallax for ER 8, and thus its luminosity and {from its effective temperature} its radius. Such quantities are at present rather poorly known for the coolest white dwarfs, and will provide strong constraints on white-dwarf physics.

  20. Accurate Mass Determination of the Ancient White Dwarf ER 8 Through Astrometric Microlensing

    NASA Astrophysics Data System (ADS)

    Sahu, Kailash

    2004-07-01

    We propose to determine the mass of the very cool white dwarf ER 8 through astrometric microlensing. We have predicted that ER 8 will pass very close to a 15th-mag background star in January 2006, with an impact parameter of less than 0.05 arcsec. As it passes in front, it will cause a deflection of the background star's image by >8 milliarcsec, an amount easily detectable with HST/FGS. The gravitational deflection angle depends only on the distances and relative positions of the stars, and on the mass of the white dwarf. Since the distances and positions can be determined precisely before the event, the astrometric measurement offers a unique and direct method to measure the mass of the white dwarf to high accuracy {<5%}. Unlike all other stellar mass determinations, this technique works for single stars {but only if they are nearby and of sufficient mass}. The mass of ER 8 is of special interest because it is a member of the Galactic halo, and appears to be the oldest known field white dwarf. This object can thus set a lower limit on the age of the Galactic halo, but since white-dwarf cooling rates depend on their masses, the mass is a necessary ingredient in the age determination. As a byproduct, we will obtain an accurate parallax for ER 8, and thus its luminosity and {from its effective temperature} its radius. Such quantities are at present rather poorly known for the coolest white dwarfs, and will provide strong constraints on white-dwarf physics.

  1. Detecting and Measuring the Masses of Isolated Black Holes and Neutron Stars through Astrometric Microlensing

    NASA Astrophysics Data System (ADS)

    Sahu, Kailash

    2011-10-01

    We propose a 3-year program of monitoring of 12 fields in the Galactic bulge, containing a total of 1.5 million stars down to V=28. Our primary aim is to detect microlensing events caused by non-luminous isolated black holes {BHs} and neutron stars {NSs} in the Galactic disk and bulge.The unique capability of HST imaging for microlensing observations is the addition of high-precision astrometry, allowing detection of the astrometric shift of the source during the event. Combined with the lens parallax, provided by the HST event light curve, the astrometric shift provides a direct measurement of the lens mass. We will detect 120 microlensing events, of which 45% will show astrometric deflections, leading to direct determinations of the lens masses. Of these, about 18 lenses are expected to be BHs and 14 of them NSs, along with about 22 events due to main-sequence stars.To date, BH and NS masses have been directly measured only in binaries; no isolated BH has been detected unambiguously within our Galaxy. A survey of the scope proposed here is the only means available at present for measuring the mass function of isolated BHs and NSs, and moreover one that is normalized to that of luminous stars. The results will provide a quantitative estimate of the mass content in the form of stellar remnants in the young Galactic disk and old bulge, and important constraints on SN/GRB explosion mechanisms that produce NSs and BHs.Our data will also be useful for other investigations, including a more accurate determination of the microlensing optical depth, faint variable stars, bulge proper motions and kinematics, and a deep luminosity function of the disk and bulge stars.

  2. Detecting and Measuring the Masses of Isolated Black Holes and Neutron Stars through Astrometric Microlensing

    NASA Astrophysics Data System (ADS)

    Sahu, Kailash

    2012-10-01

    We propose a 3-year program of monitoring of 12 fields in the Galactic bulge, containing a total of 1.5 million stars down to V=28. Our primary aim is to detect microlensing events caused by non-luminous isolated black holes {BHs} and neutron stars {NSs} in the Galactic disk and bulge.The unique capability of HST imaging for microlensing observations is the addition of high-precision astrometry, allowing detection of the astrometric shift of the source during the event. Combined with the lens parallax, provided by the HST event light curve, the astrometric shift provides a direct measurement of the lens mass. We will detect 120 microlensing events, of which 45% will show astrometric deflections, leading to direct determinations of the lens masses. Of these, about 18 lenses are expected to be BHs and 14 of them NSs, along with about 22 events due to main-sequence stars.To date, BH and NS masses have been directly measured only in binaries; no isolated BH has been detected unambiguously within our Galaxy. A survey of the scope proposed here is the only means available at present for measuring the mass function of isolated BHs and NSs, and moreover one that is normalized to that of luminous stars. The results will provide a quantitative estimate of the mass content in the form of stellar remnants in the young Galactic disk and old bulge, and important constraints on SN/GRB explosion mechanisms that produce NSs and BHs.Our data will also be useful for other investigations, including a more accurate determination of the microlensing optical depth, faint variable stars, bulge proper motions and kinematics, and a deep luminosity function of the disk and bulge stars.

  3. Detecting and Measuring the Masses of Isolated Black Holes and Neutron Stars through Astrometric Microlensing

    NASA Astrophysics Data System (ADS)

    Sahu, Kailash

    2013-10-01

    We propose a 3-year program of monitoring of 12 fields in the Galactic bulge, containing a total of 1.5 million stars down to V=28. Our primary aim is to detect microlensing events caused by non-luminous isolated black holes {BHs} and neutron stars {NSs} in the Galactic disk and bulge.The unique capability of HST imaging for microlensing observations is the addition of high-precision astrometry, allowing detection of the astrometric shift of the source during the event. Combined with the lens parallax, provided by the HST event light curve, the astrometric shift provides a direct measurement of the lens mass. We will detect 120 microlensing events, of which 45% will show astrometric deflections, leading to direct determinations of the lens masses. Of these, about 18 lenses are expected to be BHs and 14 of them NSs, along with about 22 events due to main-sequence stars.To date, BH and NS masses have been directly measured only in binaries; no isolated BH has been detected unambiguously within our Galaxy. A survey of the scope proposed here is the only means available at present for measuring the mass function of isolated BHs and NSs, and moreover one that is normalized to that of luminous stars. The results will provide a quantitative estimate of the mass content in the form of stellar remnants in the young Galactic disk and old bulge, and important constraints on SN/GRB explosion mechanisms that produce NSs and BHs.Our data will also be useful for other investigations, including a more accurate determination of the microlensing optical depth, faint variable stars, bulge proper motions and kinematics, and a deep luminosity function of the disk and bulge stars.

  4. Adventures in the microlensing cloud: Large datasets, eResearch tools, and GPUs

    NASA Astrophysics Data System (ADS)

    Vernardos, G.; Fluke, C. J.

    2014-10-01

    As astronomy enters the petascale data era, astronomers are faced with new challenges relating to storage, access and management of data. A shift from the traditional approach of combining data and analysis at the desktop to the use of remote services, pushing the computation to the data, is now underway. In the field of cosmological gravitational microlensing, future synoptic all-sky surveys are expected to bring the number of multiply imaged quasars from the few tens that are currently known to a few thousands. This inflow of observational data, together with computationally demanding theoretical modeling via the production of microlensing magnification maps, requires a new approach. We present our technical solutions to supporting the GPU-Enabled, High Resolution cosmological MicroLensing parameter survey (GERLUMPH). This extensive dataset for cosmological microlensing modeling comprises over 70 000 individual magnification maps and ˜106 related results. We describe our approaches to hosting, organizing, and serving ˜ 30 TB of data and metadata products. We present a set of online analysis tools developed with PHP, JavaScript and WebGL to support access and analysis of GELRUMPH data in a Web browser. We discuss our use of graphics processing units (GPUs) to accelerate data production, and we release the core of the GPU-D direct inverse ray-shooting code (Thompson et al., 2010, 2014) used to generate the magnification maps. All of the GERLUMPH data and tools are available online from http://gerlumph.swin.edu.au. This project made use of gSTAR, the GPU Supercomputer for Theoretical Astrophysical Research.

  5. OGLE-2013-BLG-0102LA,B: MICROLENSING BINARY WITH COMPONENTS AT STAR/BROWN DWARF AND BROWN DWARF/PLANET BOUNDARIES

    SciTech Connect

    Jung, Y. K.; Han, C.; Udalski, A.; Skowron, J.; Kozłowski, S.; Poleski, R.; Wyrzykowski, Ł.; Szymański, M. K.; Pietrzyński, G.; Soszyński, I.; Ulaczyk, K.; Pietrukowicz, P.; Mróz, P.; Kubiak, M.; Sumi, T.; Gould, A.; Abe, F.; Bennett, D. P.; Bond, I. A.; Botzler, C. S.; Collaboration: OGLE Collaboration; MOA Collaboration; μFUN Collaboration; and others

    2015-01-10

    We present an analysis of the gravitational microlensing event OGLE-2013-BLG-0102. The light curve of the event is characterized by a strong short-term anomaly superposed on a smoothly varying lensing curve with a moderate magnification A {sub max} ∼ 1.5. It is found that the event was produced by a binary lens with a mass ratio between the components of q = 0.13 and the anomaly was caused by the passage of the source trajectory over a caustic located away from the barycenter of the binary. Based on the analysis of the effects on the light curve due to the finite size of the source and the parallactic motion of the Earth, we determine the physical parameters of the lens system. The measured masses of the lens components are M {sub 1} = 0.096 ± 0.013 M {sub ☉} and M {sub 2} = 0.012 ± 0.002 M {sub ☉}, which correspond to near the hydrogen-burning and deuterium-burning mass limits, respectively. The distance to the lens is 3.04 ± 0.31 kpc and the projected separation between the lens components is 0.80 ± 0.08 AU.

  6. Gravitational Waves: The Evidence Mounts

    ERIC Educational Resources Information Center

    Wick, Gerald L.

    1970-01-01

    Reviews the work of Weber and his colleagues in their attempts at detecting extraterrestial gravitational waves. Coincidence events recorded by special detectors provide the evidence for the existence of gravitational waves. Bibliography. (LC)

  7. Black hole, neutron star and white dwarf candidates from microlensing with OGLE-III

    NASA Astrophysics Data System (ADS)

    Wyrzykowski, Ł.; Kostrzewa-Rutkowska, Z.; Skowron, J.; Rybicki, K. A.; Mróz, P.; Kozłowski, S.; Udalski, A.; Szymański, M. K.; Pietrzyński, G.; Soszyński, I.; Ulaczyk, K.; Pietrukowicz, P.; Poleski, R.; Pawlak, M.; Iłkiewicz, K.; Rattenbury, N. J.

    2016-05-01

    Most stellar remnants so far have been found in binary systems, where they interact with matter from their companions. Isolated neutron stars and black holes are difficult to find as they are dark, yet they are predicted to exist in our Galaxy in vast numbers. We explored the OGLE-III data base of 150 million objects observed in years 2001-2009 and found 59 microlensing events exhibiting a parallax effect due to the Earth's motion around the Sun. Combining parallax and brightness measurements from microlensing light curves with expected proper motions in the Milky Way, we identified 13 microlensing events which are consistent with having a white dwarf, neutron star or a black hole lens and we estimated their masses and distances. The most massive of our black hole candidates has 9.3 M⊙ and is at a distance of 2.4 kpc. The distribution of masses of our candidates indicates a continuum in mass distribution with no mass gap between neutron stars and black holes. We also present predictions on how such events will be observed by the astrometric Gaia mission.

  8. Halo cold dark matter and microlensing

    SciTech Connect

    Gates, Evalyn; Turner, Michael S.

    1993-12-01

    There is good evidence that most of the baryons in the Universe are dark and some evidence that most of the matter in the Universe is nonbaryonic with cold dark matter (cdm) being a promising possibility. We discuss expectations for the abundance of baryons and cdm in the halo of our galaxy and locally. We show that in plausible cdm models the local density of cdm is at least $10^{-25}\\gcmm3$. We also discuss what one can learn about the the local cdm density from microlensing of stars in the LMC by dark stars in the halo and, based upon a suite of reasonable two-component halo models, conclude that microlensing is not a sensitive probe of the local cdm density.

  9. The chemically homogeneous evolutionary channel for binary black hole mergers: rates and properties of gravitational-wave events detectable by advanced LIGO

    NASA Astrophysics Data System (ADS)

    de Mink, S. E.; Mandel, I.

    2016-08-01

    We explore the predictions for detectable gravitational-wave signals from merging binary black holes formed through chemically homogeneous evolution in massive short-period stellar binaries. We find that ˜500 events per year could be detected with advanced ground-based detectors operating at full sensitivity. We analyse the distribution of detectable events, and conclude that there is a very strong preference for detecting events with nearly equal components (mass ratio >0.66 at 90 per cent confidence in our default model) and high masses (total source-frame mass between 57 and 103 M⊙ at 90 per cent confidence). We consider multiple alternative variations to analyse the sensitivity to uncertainties in the evolutionary physics and cosmological parameters, and conclude that while the rates are sensitive to assumed variations, the mass distributions are robust predictions. Finally, we consider the recently reported results of the analysis of the first 16 double-coincident days of the O1 LIGO (Laser Interferometer Gravitational-wave Observatory) observing run, and find that this formation channel is fully consistent with the inferred parameters of the GW150914 binary black hole detection and the inferred merger rate.

  10. Microlensing Signature of Binary Black Holes

    NASA Technical Reports Server (NTRS)

    Schnittman, Jeremy; Sahu, Kailash; Littenberg, Tyson

    2012-01-01

    We calculate the light curves of galactic bulge stars magnified via microlensing by stellar-mass binary black holes along the line-of-sight. We show the sensitivity to measuring various lens parameters for a range of survey cadences and photometric precision. Using public data from the OGLE collaboration, we identify two candidates for massive binary systems, and discuss implications for theories of star formation and binary evolution.

  11. Planetary Caustic Perturbations of a Close-separation Planet on Microlensing

    NASA Astrophysics Data System (ADS)

    Ryu, Yoon-Hyun; Kim, Han-Seek; Chung, Sun-Ju; Kim, Dong-Jin

    2016-09-01

    Most planetary events discovered up to date by the planetary caustic of close-separation planets have low-mass ratios. In next-generation microlensing experiments with a wider field of view and a higher cadence, it is possible to obtain densely covered planetary signals induced by the planetary caustic of close-separation planets without missing events. Therefore, the planetary caustic perturbation of close-separation planets would be the more important channel to detect low-mass exoplanets in the next generation of microlensing surveys. In this paper, we investigate the theoretical properties and detection conditions for the planetary caustic perturbation of close-separation planets. To find the properties of the planetary caustic perturbation, we construct deviation maps by subtracting the single-lensing magnification of the lens star from the planetary lensing magnification for various lensing parameters. We find that each deviation area of the positive and negative perturbations disappears at the same normalized source radius according to a given deviation threshold regardless of mass ratio but disappears at a different normalized source radius according to the separation. We also estimate the upper limit of the normalized source radius to detect the planetary caustic perturbation. We find simple relations between the upper limit of the normalized source radius and the lensing parameters. From the relations, we obtain an analytic condition for the theoretical detection limit of the planet, which shows that we can sufficiently discover a planet with a sub-Earth-mass for typical microlensing events. Therefore, we conclude that our planet-detection condition of can be used as an important criteria for maximal planet detections, considering the source type and the photometric accuracy and expect that a number of low-mass planets will be added from the next-generation microlensing experiments.

  12. The WFIRST Microlensing Survey: Expectations and Unexpectations

    NASA Astrophysics Data System (ADS)

    Gaudi, B. Scott; Penny, Matthew

    2016-01-01

    The WFIRST microlensing survey will provide the definitive determination of the demographics of cool planets with semimajor axes > 1 AU and masses greater than that of the Earth, including free-floating planets. Together with the results from Kepler, TESS, and PLATO, WFIRST will complete the statistical census of planets in the Galaxy. These expectations are based on the most basic and conservative assumptions about the data quality, and assumes that the analysis methodologies will be similar to that used for current ground-based microlensing. Yet, in fact, the data quality will be dramatically better, and information content substantially richer, for the WFIRST microlensing survey as compared to current ground-based surveys. Thus WFIRST should allow for orders of magnitude improvement in both sensitivity and science yield. We will review some of these expected improvements and opportunities (the "known unknowns"), and provide a "to do list" of what tasks will need to be completed in order to take advantage of these opportunities. We will then speculate on the opportunities that we may not be aware of yet (the "unknown unknowns"), how we might go about determining what those opportunities are, and how we might figure out what we will need to do to take advantage of them.This work was partially supported by NASA grant NNX14AF63G.

  13. MICROLENSING BINARIES DISCOVERED THROUGH HIGH-MAGNIFICATION CHANNEL

    SciTech Connect

    Shin, I.-G.; Choi, J.-Y.; Park, S.-Y.; Han, C.; Gould, A.; Gaudi, B. S.; Sumi, T.; Udalski, A.; Beaulieu, J.-P.; Dominik, M.; Allen, W.; Bos, M.; Christie, G. W.; Depoy, D. L.; Dong, S.; Drummond, J.; Gal-Yam, A.; Hung, L.-W.; Janczak, J.; Kaspi, S.; Collaboration: muFUN Collaboration; MOA Collaboration; OGLE Collaboration; PLANET Collaboration; RoboNet Collaboration; MiNDSTEp Consortium; and others

    2012-02-20

    Microlensing can provide a useful tool to probe binary distributions down to low-mass limits of binary companions. In this paper, we analyze the light curves of eight binary-lensing events detected through the channel of high-magnification events during the seasons from 2007 to 2010. The perturbations, which are confined near the peak of the light curves, can be easily distinguished from the central perturbations caused by planets. However, the degeneracy between close and wide binary solutions cannot be resolved with a 3{sigma} confidence level for three events, implying that the degeneracy would be an important obstacle in studying binary distributions. The dependence of the degeneracy on the lensing parameters is consistent with a theoretical prediction that the degeneracy becomes severe as the binary separation and the mass ratio deviate from the values of resonant caustics. The measured mass ratio of the event OGLE-2008-BLG-510/MOA-2008-BLG-369 is q {approx} 0.1, making the companion of the lens a strong brown dwarf candidate.

  14. Gravitational wave signatures of the absence of an event horizon. II. Extreme mass ratio inspirals in the spacetime of a thin-shell gravastar

    SciTech Connect

    Pani, Paolo; Berti, Emanuele; Cardoso, Vitor; Chen Yanbei; Norte, Richard

    2010-04-15

    We study gravitational wave emission from the quasicircular, extreme mass ratio inspiral of compact objects of mass m{sub 0} into massive objects of mass M>>m{sub 0} whose external metric is identical to the Schwarzschild metric, except for the absence of an event horizon. To be specific we consider one of the simplest realizations of such an object: a nonrotating thin-shell gravastar. The power radiated in gravitational waves during the inspiral shows distinctive peaks corresponding to the excitation of the polar oscillation modes of the gravastar. For ultracompact gravastars the frequency of these peaks depends mildly on the gravastar compactness. For masses M{approx}10{sup 6}M{sub {center_dot}}the peaks typically lie within the optimal sensitivity bandwidth of the Laser Interferometer Space Antenna, potentially providing a unique signature of the horizonless nature of the central object. For relatively modest values of the gravastar compactness the radiated power has even more peculiar features, carrying the signature of the microscopic properties of the physical surface replacing the event horizon.

  15. The background rate of false positives: Combining simulations of gravitational wave events with an unsupervised algorithm for transient identification in crowded image-subtracted data

    NASA Astrophysics Data System (ADS)

    Ackley, Kendall; Eikenberry, Stephen; Klimenko, Sergey; LIGO Collaboration

    2016-03-01

    We are now entering the era of multimessenger gravitational wave (GW) astronomy with the completion of the first observing run of Advanced LIGO. Multiwavelength electromagnetic (EM) emission is expected to accompany gravitational radiation from compact object binary mergers, such as those between neutron stars and stellar-mass black holes, where Advanced LIGO is most sensitive to their detection. Attempting to perform EM follow-up over the 10-100s deg2 error regions will be faced with many challenges, including the identification and removal of O (105) false positive transients that appear as a commotion of background events and as image artifacts in crowded image-subtracted fields. We present an update to our automated unsupervised algorithm including how our pipeline uses the existing coherent WaveBurst pipeline in an attempt to develop optimized EM follow-up schema. Our end-to-end pipeline combines simulated GW events with actual observational data from a number of ground-based optical observatories, including PTF, ROTSE, and DECam. Our performance is reported both in terms of the number of coincident false positives as well as the efficiency of recovery.

  16. Predictions on the detection of the free-floating planet population with K2 and spitzer microlensing campaigns

    NASA Astrophysics Data System (ADS)

    Hamolli, L.; De Paolis, F.; Hafizi, M.; Nucita, A. A.

    2017-01-01

    The K2's Campaign 9 (K2C9) by the Kepler satellite for microlensing observations towards the Galactic bulge started on April 7, 2016, and is going to last for about three months. It offers the first chance to measure the masses of members of the large population of the isolated dark low-mass objects further away in our Galaxy, free-floating planets (FFPs). Intentionally, this observational period of K2 will overlap with that of the 2016 Spitzer follow-up microlensing project expected to start in June, 2016. Therefore, for the first time it is going to be possible to observe simultaneously the same microlensing events from a ground-based telescope and two satellites. This will help in removing the two-fold degeneracy of the impact parameter and in estimating the FFP mass, provided that the angular Einstein ring radius ΘE is measured. In this paper we calculate the probability that a microlensing event is detectable by two or more telescopes and study how it depends on the mass function index of FFPs and the position of the observers on the orbit.

  17. CHARACTERIZATION OF MICROLENSING PLANETS WITH MODERATELY WIDE SEPARATIONS

    SciTech Connect

    Han, Cheongho

    2009-08-01

    In future high-cadence microlensing surveys, planets can be detected through a new channel of an independent event produced by the planet itself. The two populations of planets to be detected through this channel are wide-separation planets and free-floating planets. Although they appear as similar short timescale events, the two populations of planets are widely different in nature and thus distinguishing them is important. In this paper, we investigate the lensing properties of events produced by planets with moderately wide separations from host stars. We find that the lensing behavior of these events is well described by the Chang-Refsdal lensing, and the shear caused by the primary not only produces a caustic but also makes the magnification contour elongated along the primary-planet axis. The elongated magnification contour implies that the light curves of these planetary events are generally asymmetric, and thus the asymmetry can be used to distinguish the events from those produced by free-floating planets. The asymmetry can be noticed from the overall shape of the light curve and thus can hardly be missed unlike the very short duration central perturbation caused by the caustic. In addition, the asymmetry occurs regardless of the event magnification, and thus the bound nature of the planet can be identified for majority of these events. The close approximation of the lensing light curve to that of the Chang-Refsdal lensing implies that the analysis of the light curve yields only the information about the projected separation between the host star and the planet.

  18. Gravitational lenses

    SciTech Connect

    Turner, E.L.

    1988-07-01

    For several years astronomers have devoted considerable effort to finding and studying a class of celestial phenomena whose very existence depends on rare cosmic accidents. These are gravitational-lens events, which occur when two or more objects at different distances from the earth happen to lie along the same line of sight and so coincide in the sky. The radiation from the more distant object, typically a quasar, is bent by the gravitational field of the foreground object. The bending creates a cosmic mirage: distorted or multiple images of the background object. Such phenomena may reveal many otherwise undetectable features of the image source, of the foreground object and of the space lying between them. Such observations could help to resolve several fundamental questions in cosmology. In the past decade theoretical and observational research on gravitational lenses has grown rapidly and steadily. At this writing at least 17 candidate lens systems have been discussed in the literature. Of the 17 lens candidates reported so far in professional literature, only five are considered to have been reliably established by subsequent observations. Another three are generally regarded as weak or speculative cases with less than 50 percent chance of actually being lens systems. In the remaining nine cases the evidence is mixed or is sparse enough so that the final judgment could swing either way. As might be concluded, little of the scientific promise of gravitational lenses has yet been realized. The work has not yielded a clear value for the proportionality constant or any of the other fundamental cosmological parameter. 7 figs.

  19. A dark energy camera search for missing supergiants in the LMC after the advanced LIGO gravitational-wave event GW150914

    DOE PAGES

    Annis, J.

    2016-05-27

    The collapse of a stellar core is expected to produce gravitational waves (GWs), neutrinos, and in most cases a luminous supernova. Sometimes, however, the optical event could be significantly less luminous than a supernova and a direct collapse to a black hole, where the star just disappears, is possible. The GW event GW150914 was detected by the LIGO Virgo Collaboration via a burst analysis that gave localization contours enclosing the Large Magellanic Cloud (LMC). Shortly thereafter, we used DECam to observe 102 deg2 of the localization area, including 38 deg2 on the LMC for a missing supergiant search. We constructmore » a complete catalog of LMC luminous red supergiants, the best candidates to undergo invisible core collapse, and collected catalogs of other candidates: less luminous red supergiants, yellow supergiants, blue supergiants, luminous blue variable stars, and Wolf–Rayet stars. Of the objects in the imaging region, all are recovered in the images. The timescale for stellar disappearance is set by the free-fall time, which is a function of the stellar radius. Our observations at 4 and 13 days after the event result in a search sensitive to objects of up to about 200 solar radii. We conclude that it is unlikely that GW150914 was caused by the core collapse of a relatively compact supergiant in the LMC, consistent with the LIGO Collaboration analyses of the gravitational waveform as best interpreted as a high mass binary black hole merger. Lastly, we discuss how to generalize this search for future very nearby core-collapse candidates.« less

  20. A dark energy camera search for missing supergiants in the LMC after the advanced LIGO gravitational-wave event GW150914

    SciTech Connect

    Annis, J.

    2016-05-27

    The collapse of a stellar core is expected to produce gravitational waves (GWs), neutrinos, and in most cases a luminous supernova. Sometimes, however, the optical event could be significantly less luminous than a supernova and a direct collapse to a black hole, where the star just disappears, is possible. The GW event GW150914 was detected by the LIGO Virgo Collaboration via a burst analysis that gave localization contours enclosing the Large Magellanic Cloud (LMC). Shortly thereafter, we used DECam to observe 102 deg2 of the localization area, including 38 deg2 on the LMC for a missing supergiant search. We construct a complete catalog of LMC luminous red supergiants, the best candidates to undergo invisible core collapse, and collected catalogs of other candidates: less luminous red supergiants, yellow supergiants, blue supergiants, luminous blue variable stars, and Wolf–Rayet stars. Of the objects in the imaging region, all are recovered in the images. The timescale for stellar disappearance is set by the free-fall time, which is a function of the stellar radius. Our observations at 4 and 13 days after the event result in a search sensitive to objects of up to about 200 solar radii. We conclude that it is unlikely that GW150914 was caused by the core collapse of a relatively compact supergiant in the LMC, consistent with the LIGO Collaboration analyses of the gravitational waveform as best interpreted as a high mass binary black hole merger. Lastly, we discuss how to generalize this search for future very nearby core-collapse candidates.

  1. A Dark Energy Camera Search for Missing Supergiants in the LMC after the Advanced LIGO Gravitational-wave Event GW150914

    NASA Astrophysics Data System (ADS)

    Annis, J.; Soares-Santos, M.; Berger, E.; Brout, D.; Chen, H.; Chornock, R.; Cowperthwaite, P. S.; Diehl, H. T.; Doctor, Z.; Drlica-Wagner, A.; Drout, M. R.; Farr, B.; Finley, D. A.; Flaugher, B.; Foley, R. J.; Frieman, J.; Gruendl, R. A.; Herner, K.; Holz, D.; Kessler, R.; Lin, H.; Marriner, J.; Neilsen, E.; Rest, A.; Sako, M.; Smith, M.; Smith, N.; Sobreira, F.; Walker, A. R.; Yanny, B.; Abbott, T. M. C.; Abdalla, F. B.; Allam, S.; Benoit-Lévy, A.; Bernstein, R. A.; Bertin, E.; Buckley-Geer, E.; Burke, D. L.; Capozzi, D.; Carnero Rosell, A.; Carrasco Kind, M.; Carretero, J.; Castander, F. J.; Cenko, S. B.; Crocce, M.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; Desai, S.; Dietrich, J. P.; Eifler, T. F.; Evrard, A. E.; Fernandez, E.; Fischer, J.; Fong, W.; Fosalba, P.; Fox, D. B.; Fryer, C. L.; Garcia-Bellido, J.; Gaztanaga, E.; Gerdes, D. W.; Goldstein, D. A.; Gruen, D.; Gutierrez, G.; Honscheid, K.; James, D. J.; Karliner, I.; Kasen, D.; Kent, S.; Kuehn, K.; Kuropatkin, N.; Lahav, O.; Li, T. S.; Lima, M.; Maia, M. A. G.; Martini, P.; Metzger, B. D.; Miller, C. J.; Miquel, R.; Mohr, J. J.; Nichol, R. C.; Nord, B.; Ogando, R.; Peoples, J.; Petravic, D.; Plazas, A. A.; Quataert, E.; Romer, A. K.; Roodman, A.; Rykoff, E. S.; Sanchez, E.; Santiago, B.; Scarpine, V.; Schindler, R.; Schubnell, M.; Sevilla-Noarbe, I.; Sheldon, E.; Smith, R. C.; Stebbins, A.; Swanson, M. E. C.; Tarle, G.; Thaler, J.; Thomas, R. C.; Tucker, D. L.; Vikram, V.; Wechsler, R. H.; Weller, J.; Wester, W.; DES Collaboration

    2016-06-01

    The collapse of a stellar core is expected to produce gravitational waves (GWs), neutrinos, and in most cases a luminous supernova. Sometimes, however, the optical event could be significantly less luminous than a supernova and a direct collapse to a black hole, where the star just disappears, is possible. The GW event GW150914 was detected by the LIGO Virgo Collaboration via a burst analysis that gave localization contours enclosing the Large Magellanic Cloud (LMC). Shortly thereafter, we used DECam to observe 102 deg2 of the localization area, including 38 deg2 on the LMC for a missing supergiant search. We construct a complete catalog of LMC luminous red supergiants, the best candidates to undergo invisible core collapse, and collected catalogs of other candidates: less luminous red supergiants, yellow supergiants, blue supergiants, luminous blue variable stars, and Wolf-Rayet stars. Of the objects in the imaging region, all are recovered in the images. The timescale for stellar disappearance is set by the free-fall time, which is a function of the stellar radius. Our observations at 4 and 13 days after the event result in a search sensitive to objects of up to about 200 solar radii. We conclude that it is unlikely that GW150914 was caused by the core collapse of a relatively compact supergiant in the LMC, consistent with the LIGO Collaboration analyses of the gravitational waveform as best interpreted as a high mass binary black hole merger. We discuss how to generalize this search for future very nearby core-collapse candidates.

  2. IMPROVED THEORETICAL PREDICTIONS OF MICROLENSING RATES FOR THE DETECTION OF PRIMORDIAL BLACK HOLE DARK MATTER

    SciTech Connect

    Cieplak, Agnieszka M.; Griest, Kim

    2013-04-20

    Primordial black holes (PBHs) remain a dark matter (DM) candidate of the Standard Model of Particle Physics. Previously, we proposed a new method of constraining the remaining PBH DM mass range using microlensing of stars monitored by NASA's Kepler mission. We improve this analysis using a more accurate treatment of the population of the Kepler source stars, their variability, and limb darkening. We extend the theoretically detectable PBH DM mass range down to 2 Multiplication-Sign 10{sup -10} M{sub Sun }, two orders of magnitude below current limits and one-third order of magnitude below our previous estimate. We address how to extract the DM properties, such as mass and spatial distribution, if PBH microlensing events were detected. We correct an error in a well-known finite-source limb-darkening microlensing formula and also examine the effects of varying the light curve cadence on PBH DM detectability. We also introduce an approximation for estimating the predicted rate of detection per star as a function of the star's properties, thus allowing for selection of source stars in future missions, and extend our analysis to planned surveys, such as the Wide-Field Infrared Survey Telescope.

  3. Ultrahigh-energy neutrino follow-up of gravitational wave events GW150914 and GW151226 with the Pierre Auger Observatory

    SciTech Connect

    Aab, A.; Abreu, P.; Aglietta, M.; Al Samarai, I.; Albuquerque, I. F. M.; Allekotte, I.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muñiz, J.; Ambrosio, M.; Anastasi, G. A.; Anchordoqui, L.; Andrada, B.; Andringa, S.; Aramo, C.; Arqueros, F.; Arsene, N.; Asorey, H.; Assis, P.; Aublin, J.; Avila, G.; Badescu, A. M.; Balaceanu, A.; Barreira Luz, R. J.; Baus, C.; Beatty, J. J.; Becker, K. H.; Bellido, J. A.; Berat, C.; Bertaina, M. E.; Bertou, X.; Biermann, P. L.; Billoir, P.; Biteau, J.; Blaess, S. G.; Blanco, A.; Blazek, J.; Bleve, C.; Boháčová, M.; Boncioli, D.; Bonifazi, C.; Borodai, N.; Botti, A. M.; Brack, J.; Brancus, I.; Bretz, T.; Bridgeman, A.; Briechle, F. L.; Buchholz, P.; Bueno, A.; Buitink, S.; Buscemi, M.; Caballero-Mora, K. S.; Caccianiga, L.; Cancio, A.; Canfora, F.; Caramete, L.; Caruso, R.; Castellina, A.; Cataldi, G.; Cazon, L.; Cester, R.; Chavez, A. G.; Chinellato, J. A.; Chudoba, J.; Clay, R. W.; Colalillo, R.; Coleman, A.; Collica, L.; Coluccia, M. R.; Conceição, R.; Contreras, F.; Cooper, M. J.; Coutu, S.; Covault, C. E.; Cronin, J.; D’Amico, S.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; de Jong, S. J.; De Mauro, G.; de Mello Neto, J. R. T.; De Mitri, I.; de Oliveira, J.; de Souza, V.; Debatin, J.; Deligny, O.; Di Giulio, C.; Di Matteo, A.; Díaz Castro, M. L.; Diogo, F.; Dobrigkeit, C.; D’Olivo, J. C.; Dorofeev, A.; dos Anjos, R. C.; Dova, M. T.; Dundovic, A.; Ebr, J.; Engel, R.; Erdmann, M.; Erfani, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Falcke, H.; Fang, K.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Fick, B.; Figueira, J. M.; Filipčič, A.; Fratu, O.; Freire, M. M.; Fujii, T.; Fuster, A.; Gaior, R.; García, B.; Garcia-Pinto, D.; Gaté, F.; Gemmeke, H.; Gherghel-Lascu, A.; Ghia, P. L.; Giaccari, U.; Giammarchi, M.; Giller, M.; Głas, D.; Glaser, C.; Glass, H.; Golup, G.; Gómez Berisso, M.; Gómez Vitale, P. F.; González, N.; Gookin, B.; Gorgi, A.; Gorham, P.; Gouffon, P.; Grillo, A. F.; Grubb, T. D.; Guarino, F.; Guedes, G. P.; Hampel, M. R.; Hansen, P.; Harari, D.; Harrison, T. A.; Harton, J. L.; Hasankiadeh, Q.; Haungs, A.; Hebbeker, T.; Heck, D.; Heimann, P.; Herve, A. E.; Hill, G. C.; Hojvat, C.; Holt, E.; Homola, P.; Hörandel, J. R.; Horvath, P.; Hrabovský, M.; Huege, T.; Hulsman, J.; Insolia, A.; Isar, P. G.; Jandt, I.; Jansen, S.; Johnsen, J. A.; Josebachuili, M.; Kääpä, A.; Kambeitz, O.; Kampert, K. H.; Kasper, P.; Katkov, I.; Keilhauer, B.; Kemp, E.; Kemp, J.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Krause, R.; Krohm, N.; Kuempel, D.; Kukec Mezek, G.; Kunka, N.; Kuotb Awad, A.; LaHurd, D.; Lauscher, M.; Lebrun, P.; Legumina, R.; Leigui de Oliveira, M. A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; Lopes, L.; López, R.; López Casado, A.; Luce, Q.; Lucero, A.; Malacari, M.; Mallamaci, M.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Mariş, I. C.; Marsella, G.; Martello, D.; Martinez, H.; Martínez Bravo, O.; Masías Meza, J. J.; Mathes, H. J.; Mathys, S.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Mayotte, E.; Mazur, P. O.; Medina, C.; Medina-Tanco, G.; Melo, D.; Menshikov, A.; Messina, S.; Micheletti, M. I.; Middendorf, L.; Minaya, I. A.; Miramonti, L.; Mitrica, B.; Mockler, D.; Molina-Bueno, L.; Mollerach, S.; Montanet, F.; Morello, C.; Mostafá, M.; Müller, G.; Muller, M. A.; Müller, S.; Naranjo, I.; Nellen, L.; Neuser, J.; Nguyen, P. H.; Niculescu-Oglinzanu, M.; Niechciol, M.; Niemietz, L.; Niggemann, T.; Nitz, D.; Nosek, D.; Novotny, V.; Nožka, H.; Núñez, L. A.; Ochilo, L.; Oikonomou, F.; Olinto, A.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Papenbreer, P.; Parente, G.; Parra, A.; Paul, T.; Pech, M.; Pedreira, F.; Pękala, J.; Pelayo, R.; Peña-Rodriguez, J.; Pereira, L. A. S.; Perrone, L.; Peters, C.; Petrera, S.; Phuntsok, J.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Porowski, C.; Prado, R. R.; Privitera, P.; Prouza, M.; Quel, E. J.; Querchfeld, S.; Quinn, S.; Ramos-Pollan, R.; Rautenberg, J.; Ravignani, D.; Reinert, D.; Revenu, B.; Ridky, J.; Risse, M.; Ristori, P.; Rizi, V.; Rodrigues de Carvalho, W.; Rodriguez Fernandez, G.; Rodriguez Rojo, J.; Rogozin, D.; Roth, M.; Roulet, E.; Rovero, A. C.; Saffi, S. J.; Saftoiu, A.; Salazar, H.; Saleh, A.; Salesa Greus, F.; Salina, G.; Sanabria Gomez, J. D.; Sánchez, F.; Sanchez-Lucas, P.; Santos, E. M.; Santos, E.; Sarazin, F.; Sarkar, B.; Sarmento, R.; Sarmiento, C. A.; Sato, R.; Schauer, M.; Scherini, V.; Schieler, H.; Schimp, M.; Schmidt, D.; Scholten, O.; Schovánek, P.; Schröder, F. G.; Schulz, A.; Schulz, J.; Schumacher, J.; Sciutto, S. J.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sigl, G.; Silli, G.; Sima, O.; Śmiałkowski, A.; Šmída, R.; Snow, G. R.; Sommers, P.; Sonntag, S.; Sorokin, J.; Squartini, R.; Stanca, D.; Stanič, S.; Stasielak, J.; Stassi, P.; Strafella, F.; Suarez, F.; Suarez Durán, M.; Sudholz, T.; Suomijärvi, T.; Supanitsky, A. D.; Swain, J.; Szadkowski, Z.; Taboada, A.; Taborda, O. A.; Tapia, A.; Theodoro, V. M.; Timmermans, C.; Todero Peixoto, C. J.; Tomankova, L.; Tomé, B.; Torralba Elipe, G.; Torres Machado, D.; Torri, M.; Travnicek, P.; Trini, M.; Ulrich, R.; Unger, M.; Urban, M.; Valdés Galicia, J. F.; Valiño, I.; Valore, L.; van Aar, G.; van Bodegom, P.; van den Berg, A. M.; van Vliet, A.; Varela, E.; Vargas Cárdenas, B.; Varner, G.; Vázquez, J. R.; Vázquez, R. A.; Veberič, D.; Vergara Quispe, I. D.; Verzi, V.; Vicha, J.; Villaseñor, L.; Vorobiov, S.; Wahlberg, H.; Wainberg, O.; Walz, D.; Watson, A. A.; Weber, M.; Weindl, A.; Wiencke, L.; Wilczyński, H.; Winchen, T.; Wittkowski, D.; Wundheiler, B.; Wykes, S.; Yang, L.; Yelos, D.; Yushkov, A.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zepeda, A.; Zimmermann, B.; Ziolkowski, M.; Zong, Z.; Zuccarello, F.

    2016-12-30

    On September 14, 2015 the Advanced LIGO detectors observed their first gravitational wave (GW) transient GW150914. This was followed by a second GW event observed on December 26, 2015. Both events were inferred to have arisen from the merger of black holes in binary systems. Such a system may emit neutrinos if there are magnetic fields and disk debris remaining from the formation of the two black holes. With the surface detector array of the Pierre Auger Observatory we can search for neutrinos with energy Eν above 100 PeV from point like sources across the sky with equatorial declination from about -65° to +60°, and, in particular, from a fraction of the 90% confidence-level inferred positions in the sky of GW150914 and GW151226. A targeted search for highly inclined extensive air showers, produced either by interactions of downward-going neutrinos of all flavors in the atmosphere or by the decays of tau leptons originating from tau-neutrino interactions in the Earth’s crust (Earth-skimming neutrinos), yielded no candidates in the Auger data collected within ±500 s around or 1 day after the coordinated universal time (UTC) of GW150914 and GW151226, as well as in the same search periods relative to the UTC time of the GW candidate event LVT151012. As a result, from the non-observation we constrain the amount of energy radiated in ultrahigh-energy neutrinos from such remarkable events.

  4. Ultrahigh-energy neutrino follow-up of gravitational wave events GW150914 and GW151226 with the Pierre Auger Observatory

    NASA Astrophysics Data System (ADS)

    Aab, A.; Abreu, P.; Aglietta, M.; Al Samarai, I.; Albuquerque, I. F. M.; Allekotte, I.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muñiz, J.; Ambrosio, M.; Anastasi, G. A.; Anchordoqui, L.; Andrada, B.; Andringa, S.; Aramo, C.; Arqueros, F.; Arsene, N.; Asorey, H.; Assis, P.; Aublin, J.; Avila, G.; Badescu, A. M.; Balaceanu, A.; Barreira Luz, R. J.; Baus, C.; Beatty, J. J.; Becker, K. H.; Bellido, J. A.; Berat, C.; Bertaina, M. E.; Bertou, X.; Biermann, P. L.; Billoir, P.; Biteau, J.; Blaess, S. G.; Blanco, A.; Blazek, J.; Bleve, C.; Boháčová, M.; Boncioli, D.; Bonifazi, C.; Borodai, N.; Botti, A. M.; Brack, J.; Brancus, I.; Bretz, T.; Bridgeman, A.; Briechle, F. L.; Buchholz, P.; Bueno, A.; Buitink, S.; Buscemi, M.; Caballero-Mora, K. S.; Caccianiga, L.; Cancio, A.; Canfora, F.; Caramete, L.; Caruso, R.; Castellina, A.; Cataldi, G.; Cazon, L.; Cester, R.; Chavez, A. G.; Chinellato, J. A.; Chudoba, J.; Clay, R. W.; Colalillo, R.; Coleman, A.; Collica, L.; Coluccia, M. R.; Conceição, R.; Contreras, F.; Cooper, M. J.; Coutu, S.; Covault, C. E.; Cronin, J.; D'Amico, S.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; de Jong, S. J.; De Mauro, G.; de Mello Neto, J. R. T.; De Mitri, I.; de Oliveira, J.; de Souza, V.; Debatin, J.; Deligny, O.; Di Giulio, C.; Di Matteo, A.; Díaz Castro, M. L.; Diogo, F.; Dobrigkeit, C.; D'Olivo, J. C.; Dorofeev, A.; dos Anjos, R. C.; Dova, M. T.; Dundovic, A.; Ebr, J.; Engel, R.; Erdmann, M.; Erfani, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Falcke, H.; Fang, K.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Fick, B.; Figueira, J. M.; Filipčič, A.; Fratu, O.; Freire, M. M.; Fujii, T.; Fuster, A.; Gaior, R.; García, B.; Garcia-Pinto, D.; Gaté, F.; Gemmeke, H.; Gherghel-Lascu, A.; Ghia, P. L.; Giaccari, U.; Giammarchi, M.; Giller, M.; Głas, D.; Glaser, C.; Glass, H.; Golup, G.; Gómez Berisso, M.; Gómez Vitale, P. F.; González, N.; Gookin, B.; Gorgi, A.; Gorham, P.; Gouffon, P.; Grillo, A. F.; Grubb, T. D.; Guarino, F.; Guedes, G. P.; Hampel, M. R.; Hansen, P.; Harari, D.; Harrison, T. A.; Harton, J. L.; Hasankiadeh, Q.; Haungs, A.; Hebbeker, T.; Heck, D.; Heimann, P.; Herve, A. E.; Hill, G. C.; Hojvat, C.; Holt, E.; Homola, P.; Hörandel, J. R.; Horvath, P.; Hrabovský, M.; Huege, T.; Hulsman, J.; Insolia, A.; Isar, P. G.; Jandt, I.; Jansen, S.; Johnsen, J. A.; Josebachuili, M.; Kääpä, A.; Kambeitz, O.; Kampert, K. H.; Kasper, P.; Katkov, I.; Keilhauer, B.; Kemp, E.; Kemp, J.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Krause, R.; Krohm, N.; Kuempel, D.; Kukec Mezek, G.; Kunka, N.; Kuotb Awad, A.; LaHurd, D.; Lauscher, M.; Lebrun, P.; Legumina, R.; Leigui de Oliveira, M. A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; Lopes, L.; López, R.; López Casado, A.; Luce, Q.; Lucero, A.; Malacari, M.; Mallamaci, M.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Mariş, I. C.; Marsella, G.; Martello, D.; Martinez, H.; Martínez Bravo, O.; Masías Meza, J. J.; Mathes, H. J.; Mathys, S.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Mayotte, E.; Mazur, P. O.; Medina, C.; Medina-Tanco, G.; Melo, D.; Menshikov, A.; Messina, S.; Micheletti, M. I.; Middendorf, L.; Minaya, I. A.; Miramonti, L.; Mitrica, B.; Mockler, D.; Molina-Bueno, L.; Mollerach, S.; Montanet, F.; Morello, C.; Mostafá, M.; Müller, G.; Muller, M. A.; Müller, S.; Naranjo, I.; Nellen, L.; Neuser, J.; Nguyen, P. H.; Niculescu-Oglinzanu, M.; Niechciol, M.; Niemietz, L.; Niggemann, T.; Nitz, D.; Nosek, D.; Novotny, V.; Nožka, H.; Núñez, L. A.; Ochilo, L.; Oikonomou, F.; Olinto, A.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Papenbreer, P.; Parente, G.; Parra, A.; Paul, T.; Pech, M.; Pedreira, F.; Pekala, J.; Pelayo, R.; Peña-Rodriguez, J.; Pereira, L. A. S.; Perrone, L.; Peters, C.; Petrera, S.; Phuntsok, J.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Porowski, C.; Prado, R. R.; Privitera, P.; Prouza, M.; Quel, E. J.; Querchfeld, S.; Quinn, S.; Ramos-Pollan, R.; Rautenberg, J.; Ravignani, D.; Reinert, D.; Revenu, B.; Ridky, J.; Risse, M.; Ristori, P.; Rizi, V.; Rodrigues de Carvalho, W.; Rodriguez Fernandez, G.; Rodriguez Rojo, J.; Rogozin, D.; Roth, M.; Roulet, E.; Rovero, A. C.; Saffi, S. J.; Saftoiu, A.; Salazar, H.; Saleh, A.; Salesa Greus, F.; Salina, G.; Sanabria Gomez, J. D.; Sánchez, F.; Sanchez-Lucas, P.; Santos, E. M.; Santos, E.; Sarazin, F.; Sarkar, B.; Sarmento, R.; Sarmiento, C. A.; Sato, R.; Schauer, M.; Scherini, V.; Schieler, H.; Schimp, M.; Schmidt, D.; Scholten, O.; Schovánek, P.; Schröder, F. G.; Schulz, A.; Schulz, J.; Schumacher, J.; Sciutto, S. J.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sigl, G.; Silli, G.; Sima, O.; Śmiałkowski, A.; Šmída, R.; Snow, G. R.; Sommers, P.; Sonntag, S.; Sorokin, J.; Squartini, R.; Stanca, D.; Stanič, S.; Stasielak, J.; Stassi, P.; Strafella, F.; Suarez, F.; Suarez Durán, M.; Sudholz, T.; Suomijärvi, T.; Supanitsky, A. D.; Swain, J.; Szadkowski, Z.; Taboada, A.; Taborda, O. A.; Tapia, A.; Theodoro, V. M.; Timmermans, C.; Todero Peixoto, C. J.; Tomankova, L.; Tomé, B.; Torralba Elipe, G.; Torres Machado, D.; Torri, M.; Travnicek, P.; Trini, M.; Ulrich, R.; Unger, M.; Urban, M.; Valdés Galicia, J. F.; Valiño, I.; Valore, L.; van Aar, G.; van Bodegom, P.; van den Berg, A. M.; van Vliet, A.; Varela, E.; Vargas Cárdenas, B.; Varner, G.; Vázquez, J. R.; Vázquez, R. A.; Veberič, D.; Vergara Quispe, I. D.; Verzi, V.; Vicha, J.; Villaseñor, L.; Vorobiov, S.; Wahlberg, H.; Wainberg, O.; Walz, D.; Watson, A. A.; Weber, M.; Weindl, A.; Wiencke, L.; Wilczyński, H.; Winchen, T.; Wittkowski, D.; Wundheiler, B.; Wykes, S.; Yang, L.; Yelos, D.; Yushkov, A.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zepeda, A.; Zimmermann, B.; Ziolkowski, M.; Zong, Z.; Zuccarello, F.; Pierre Auger Collaboration

    2016-12-01

    On September 14, 2015 the Advanced LIGO detectors observed their first gravitational wave (GW) transient GW150914. This was followed by a second GW event observed on December 26, 2015. Both events were inferred to have arisen from the merger of black holes in binary systems. Such a system may emit neutrinos if there are magnetic fields and disk debris remaining from the formation of the two black holes. With the surface detector array of the Pierre Auger Observatory we can search for neutrinos with energy Eν above 100 PeV from pointlike sources across the sky with equatorial declination from about -6 5 ° to +6 0 ° , and, in particular, from a fraction of the 90% confidence-level inferred positions in the sky of GW150914 and GW151226. A targeted search for highly inclined extensive air showers, produced either by interactions of downward-going neutrinos of all flavors in the atmosphere or by the decays of tau leptons originating from tau-neutrino interactions in the Earth's crust (Earth-skimming neutrinos), yielded no candidates in the Auger data collected within ±500 s around or 1 day after the coordinated universal time (UTC) of GW150914 and GW151226, as well as in the same search periods relative to the UTC time of the GW candidate event LVT151012. From the nonobservation we constrain the amount of energy radiated in ultrahigh-energy neutrinos from such remarkable events.

  5. Refractive microlenses for ultraflat photolithographic projection systems

    NASA Astrophysics Data System (ADS)

    Voelkel, Reinhard; Eisner, Martin; Ossmann, Christian; Weible, Kenneth J.

    2000-08-01

    We report on the fabrication of high quality microlens arrays on 4', 6' and 8'-fused silica wafers. Refractive, plano-convex microlenses are fabricated by using photolithography; a reflow or melting resist technique and reactive ion etching. A diffraction-limited optical performance (p-v wave aberrations of < (lambda) /8, Strehl ratio GTR 0.97) is achieved. Aspherical lens profiles are obtained by varying the etch parameters during the reactive ion etching transfer. The microlens arrays are used for Microlens Projection Lithography (MPL) and within UV-light illumination systems. Microlens Projection Lithography is an innovative technique using KARL SUSS Mask Aligners equipped with an ultra-flat microlens-based projection system. The projection system consists of 500.000 identical micro-objectives side- by-side. Each micro-objective consists of 3 to 4 microlenses. A fully symmetrical optical design eliminates coma, distortion and lateral color. The lens system is frontal- and backside telecentric to provide a unit magnification (+1) over the whole depth of focus. Each micro- objective images a small part of the photomask pattern onto the wafer. The partial images from different channels overlap consistently and form a complete aerial image of the photomask. Microlens Projection Lithography provides an increased depth of focus (GTR 50 microns) at a larger working distance ($GTR 1 mm)than standard proximity printing. Microlens Projection Lithography allows photolithography on curved on non-planar substrates, in V-grooves, holes, etc. using a KARL SUSS Mask Aligner.

  6. pyLIMA : an open source microlensing software

    NASA Astrophysics Data System (ADS)

    Bachelet, Etienne

    2017-01-01

    Planetary microlensing is a unique tool to detect cold planets around low-mass stars which is approaching a watershed in discoveries as near-future missions incorporate dedicated surveys. NASA and ESA have decided to complement WFIRST-AFTA and Euclid with microlensing programs to enrich our statistics about this planetary population. Of the nany challenges in- herent in these missions, the data analysis is of primary importance, yet is often perceived as time consuming, complex and daunting barrier to participation in the field. We present the first open source modeling software to conduct a microlensing analysis. This software is written in Python and use as much as possible existing packages.

  7. Interpreting the Strongly Lensed Supernova iPTF16geu: Time Delay Predictions, Microlensing, and Lensing Rates

    NASA Astrophysics Data System (ADS)

    More, Anupreeta; Suyu, Sherry H.; Oguri, Masamune; More, Surhud; Lee, Chien-Hsiu

    2017-02-01

    We present predictions for time delays between multiple images of the gravitationally lensed supernova, iPTF16geu, which was recently discovered from the intermediate Palomar Transient Factory (iPTF). As the supernova is of Type Ia where the intrinsic luminosity is usually well known, accurately measured time delays of the multiple images could provide tight constraints on the Hubble constant. According to our lens mass models constrained by the Hubble Space Telescope F814W image, we expect the maximum relative time delay to be less than a day, which is consistent with the maximum of 100 hr reported by Goobar et al. but places a stringent upper limit. Furthermore, the fluxes of most of the supernova images depart from expected values suggesting that they are affected by microlensing. The microlensing timescales are small enough that they may pose significant problems to measure the time delays reliably. Our lensing rate calculation indicates that the occurrence of a lensed SN in iPTF is likely. However, the observed total magnification of iPTF16geu is larger than expected, given its redshift. This may be a further indication of ongoing microlensing in this system.

  8. Discovery of the distant cool sub-Neptune mass planet OGLE 2005-BLG-390Lb by microlensing

    SciTech Connect

    Beaulieu, J P; Bennett, D P; Fouque, P; Williams, A; Dominik, M; Jorgensen, U G; Kubas, D; Cassan, A; Coutures, C; Greenhill, J; Hill, K; Menzies, J; Sackett, P D; Albrow, M; Brillant, S; Caldwell, J R; Calitz, J J; Cook, K H; Corrales, E; Desort, M; Dieters, S; Dominis, D; Donatowicz, J; Hoffman, M; Kane, S; Marquette, J B; Martin, R; Meintjes, P; Pollard, K; Sahu, K; Vinter, C; Wambsganss, J; Woller, K; Horne, K; Steele, I; Bramich, D M; Burgdorf, M; Snodgrass, C; Bode, M; Udalski, A; Szymanski, M K; Kubiak, M; Wieckowski, T; Pietrzynski, G; Soszynski, I; Szewczyk, O; Wyrzykowski, L; Paczynski, B; Abe, F; Bond, I A; Britton, T R; Gilmore, A C; Hearnshaw, J B; Itow, Y; Kamiya, K; Kilmartin, P M; Korpela, A V; Masuda, K; Matsubara, Y; Motomura, M; Muraki, Y; Nakamura, S; Okada, C; Ohnishi, K; Rattenbury, N J; Sako, T; Sato, S; Sasaki, M; Sekiguchi, T; Sullivan, D J; Tristram, P J; Yock, P M; Yoskioka, T

    2005-11-07

    The favoured theoretical explanation for planetary systems formation is the core-accretion model in which solid planetesimals accumulate to build up planetary cores, which then accrete nebular gas if they are sufficiently massive. Around M-dwarf stars, the most common stars of our Galaxy, this model favours the formation of Earth- to Neptune-mass planets in a few million years with orbital sizes of 1 to 10 AU, which is consistent with the small number of detections of giant planets with M-dwarf host stars. More than 170 extrasolar planets have been discovered so far with a wide range of masses and orbital periods, but planets of Neptune's mass or less have not previously been detected at separations of more than 0.15 AU from normal stars. Here we report the discovery of a 5.5{sub -2.7}{sup +5.5} Earthmass planetary companion at a separation of 2.6{sub -0.6}{sup +1.5}AU from a 0.22{sub -0.11}{sup +0.21} M{sub e} M-dwarf star, which is the lens star for gravitational microlensing event OGLE 2005-BLG-390. This is the lowest mass ever reported for an extrasolar planet orbiting a main sequence star, although the error bars overlap those for the mass of GJ876d. Our detection suggests that such cool, sub-Neptune mass planets may be common than gas giant planets, as predicted by the core accretion theory.

  9. A simple method to determine time delays in the presence of microlensing: application to HE 0435-1112 and PG 1115+080

    NASA Astrophysics Data System (ADS)

    Tsvetkova, V. S.; Shulga, V. M.; Berdina, L. A.

    2016-10-01

    A method for determining the time delays in gravitationally lensed quasars is proposed. This method offers a simple and transparent procedure to mitigate the effects of microlensing. It is based on the fundamental properties of representation of quadratically integrable functions by their expansions in orthogonal polynomials series. The method was tested on the artificial light curves simulated for the Time Delay Challenge campaign (TDC0). The new estimates of the time delays in the gravitationally lensed quasars HE 0435-1223 and PG 1115+080 are obtained and compared with the results reported earlier by other authors.

  10. The Pan-STARRS, Mauna Kea, and PESSTO search for optical counterparts to aLIGO gravitational wave events

    NASA Astrophysics Data System (ADS)

    Chambers, Kenneth C.; Pan-STARRS Collaboration

    2016-06-01

    We have searched for an optical counterpart to the first gravitational wave source discovered by the Advanced LIGO experiment, GW150914, using the Pan-STARRS wide-field telescope and associated data processing to identify transient objects. Interesting candidates are then followed up using the UH88, Gemini, and PESSTO for the spectroscopic characterization. We mapped out 442 square degrees of the northern sky region of the initial LIGO map. We discovered 56 astrophysical transients over a period of 41 days from the discovery of the source. Of these, 19 were spectroscopically classied and a further 13 have host galaxy redshifts. All transients appear to be fairly normal supernovae and AGN variability and none are obviously linked with GW150914. We find one high energey type II supernova with an estimated explosion date consistent with that of GW150914, but no causal link can be inferred. We discuss our results as demonstration of the survey capability of Pan-STARRS, and the spectroscopic capabilities of PESSTO and Mauna Kea.

  11. Variability of GeV gamma-ray emission in QSO B0218+357 due to microlensing on intermediate size structures

    NASA Astrophysics Data System (ADS)

    Sitarek, J.; Bednarek, W.

    2016-06-01

    Strong gravitational lensing leads to an occurrence of multiple images, with different magnifications, of a lensed source. Those magnifications can in turn be modified by microlensing on smaller mass scales within the lens. Recently, measurements of the changes in the magnification ratio of the individual images have been proposed as a powerful tool for estimation of the size and velocity of the emission region in the lensed source. The changes of the magnification ratios in blazars PKS1830-211 and QSO B0218+357, if interpreted as caused by a microlensing on individual stars, put strong constraints on those two variables. These constraints are difficult to accommodate with the current models of gamma-ray emission in blazars. In this paper we study if similar changes in the magnification ratio can be caused by microlensing on intermediate size structures in the lensing galaxy. We investigate in details three classes of possible lenses: globular clusters (GCs), open clusters (OCs) and giant molecular clouds (GMCs). We apply this scenario to the case of QSO B0218+357. Our numerical simulations show that changes in magnifications with similar time-scales can be obtained for relativistically moving emission regions with sizes up to 0.01 pc in the case of microlensing on the cores of GCs or clumps in GMCs. From the density of such structures in spiral galaxies we estimate however that lensing in GMCs would be more common.

  12. Dynamics and Origin of Extra-solar Planetary Systems and Microlensing Detection of Extra-solar Planets

    NASA Technical Reports Server (NTRS)

    Peale, S. J.

    2003-01-01

    We compare a space-based microlensing search for planets, with a ground based microlensing search originally proposed by D. Tytler (Beichman, et al. 1996). Perturbations of microlensing light curves when the lens star has a planetary companion are sought by one wide angle survey telescope and an array of three or four followup narrow angle telescopes distributed in longitude that follow events with high precision, high time resolution photometry. Alternative ground based programs are considered briefly. With the four 2 meter telescopes distributed in longitude in the southern hemisphere in the Tytler proposal, observational constraints on a ground-based search for planets during microlensing events toward the center of the galaxy are severe. Probably less than 100 events could be monitored per year with high precision, high time resolution photometry with only about 42% coverage on the average regardless of how many events were discovered by the survey telescope. Statistics for the occurrence and properties for Jupiter-mass planets would be meaningful but relatively meager four years after the program was started, and meaningful statistics for Earth-mass planets would be non existent. In contrast, the 14,500 events in a proposed 4 year space based program (GEST = Galactic Exoplanet Survey Telescope) would yield very sound statistics on the occurrence, masses and separations of Jupiter-mass planets, and significant constraints on similar properties for Earth-mass planets. The significance of the Jupiter statistics would be to establish the frequency of planetary systems like our own, where terrestrial planets could exist inside the orbits of the giants.

  13. High-throughput plastic microlenses fabricated using microinjection molding techniques

    NASA Astrophysics Data System (ADS)

    Appasamy, Sreeram; Li, Weizhuo; Lee, Se Hwan; Boyd, Joseph T.; Ahn, Chong H.

    2005-12-01

    A novel fabrication scheme to develop high-throughput plastic microlenses using injection-molding techniques is realized. The initial microlens mold is fabricated using the well-known reflow technique. The reflow process is optimized to obtain reliable and repeatable microlens patterns. The master mold insert for the injection-molding process is fabricated using metal electroforming. The electroplating process is optimized for obtaining a low stress electroform. Two new plastic materials, cyclo olefin copolymer (COC) and Poly IR 2 are introduced in this work for fabricating microlenses. The plastic microlenses have been characterized for their focal lengths that range from 200 µm to 1.9 mm. This technique enables high-volume production of plastic microlenses with cycle times for a single chip being of the order of 60 s.

  14. GRB 130427A AND SN 2013cq: A MULTI-WAVELENGTH ANALYSIS OF AN INDUCED GRAVITATIONAL COLLAPSE EVENT

    SciTech Connect

    Ruffini, R.; Wang, Y.; Enderli, M.; Muccino, M.; Kovacevic, M.; Bianco, C. L.; Pisani, G. B.; Rueda, J. A.; Penacchioni, A. V.

    2015-01-01

    We performed a data analysis of the observations by the Swift, NuStar, and Fermi satellites in order to probe the induced gravitational collapse (IGC) paradigm for gamma-ray bursts (GRBs) associated with supernovae (SNe) in the terra incognita of GRB 130427A. We compare our data analysis with those in the literature. We have verified that GRB 130427A conforms to the IGC paradigm by examining the power law behavior of the luminosity in the early 10{sup 4} s of the XRT observations. This has led to the identification of the four different episodes of the binary driven hypernovae (BdHNe) and to the prediction, on 2013 May 2, of the occurrence of SN 2013cq, which was also observed in the optical band on 2013 May 13. The exceptional quality of the data has allowed the identification of novel features in Episode 3 including: (1) the confirmation and the extension of the existence of the recently discovered nested structure in the late X-ray luminosity in GRB 130427A, as well as the identification of a spiky structure at 10{sup 2} s in the cosmological rest-frame of the source; (2) a power law emission of the GeV luminosity light curve and its onset at the end of Episode 2; and (3) different Lorentz Γ factors for the emitting regions of the X-ray and GeV emissions in this Episode 3. These results make it possible to test the details of the physical and astrophysical regimes at work in the BdHNe: (1) a newly born neutron star and the supernova ejecta, originating in Episode 1; (2) a newly formed black hole originating in Episode 2; and (3) the possible interaction among these components, observable in the standard features of Episode 3.

  15. GRB 130427A and SN 2013cq: A Multi-wavelength Analysis of An Induced Gravitational Collapse Event

    NASA Astrophysics Data System (ADS)

    Ruffini, R.; Wang, Y.; Enderli, M.; Muccino, M.; Kovacevic, M.; Bianco, C. L.; Penacchioni, A. V.; Pisani, G. B.; Rueda, J. A.

    2015-01-01

    We performed a data analysis of the observations by the Swift, NuStar, and Fermi satellites in order to probe the induced gravitational collapse (IGC) paradigm for gamma-ray bursts (GRBs) associated with supernovae (SNe) in the terra incognita of GRB 130427A. We compare our data analysis with those in the literature. We have verified that GRB 130427A conforms to the IGC paradigm by examining the power law behavior of the luminosity in the early 104 s of the XRT observations. This has led to the identification of the four different episodes of the binary driven hypernovae (BdHNe) and to the prediction, on 2013 May 2, of the occurrence of SN 2013cq, which was also observed in the optical band on 2013 May 13. The exceptional quality of the data has allowed the identification of novel features in Episode 3 including: (1) the confirmation and the extension of the existence of the recently discovered nested structure in the late X-ray luminosity in GRB 130427A, as well as the identification of a spiky structure at 102 s in the cosmological rest-frame of the source; (2) a power law emission of the GeV luminosity light curve and its onset at the end of Episode 2; and (3) different Lorentz Γ factors for the emitting regions of the X-ray and GeV emissions in this Episode 3. These results make it possible to test the details of the physical and astrophysical regimes at work in the BdHNe: (1) a newly born neutron star and the supernova ejecta, originating in Episode 1; (2) a newly formed black hole originating in Episode 2; and (3) the possible interaction among these components, observable in the standard features of Episode 3.

  16. Ultrahigh-energy neutrino follow-up of gravitational wave events GW150914 and GW151226 with the Pierre Auger Observatory

    DOE PAGES

    Aab, A.; Abreu, P.; Aglietta, M.; ...

    2016-12-30

    On September 14, 2015 the Advanced LIGO detectors observed their first gravitational wave (GW) transient GW150914. This was followed by a second GW event observed on December 26, 2015. Both events were inferred to have arisen from the merger of black holes in binary systems. Such a system may emit neutrinos if there are magnetic fields and disk debris remaining from the formation of the two black holes. With the surface detector array of the Pierre Auger Observatory we can search for neutrinos with energy Eν above 100 PeV from point like sources across the sky with equatorial declination from aboutmore » -65° to +60°, and, in particular, from a fraction of the 90% confidence-level inferred positions in the sky of GW150914 and GW151226. A targeted search for highly inclined extensive air showers, produced either by interactions of downward-going neutrinos of all flavors in the atmosphere or by the decays of tau leptons originating from tau-neutrino interactions in the Earth’s crust (Earth-skimming neutrinos), yielded no candidates in the Auger data collected within ±500 s around or 1 day after the coordinated universal time (UTC) of GW150914 and GW151226, as well as in the same search periods relative to the UTC time of the GW candidate event LVT151012. As a result, from the non-observation we constrain the amount of energy radiated in ultrahigh-energy neutrinos from such remarkable events.« less

  17. The OGLE view of microlensing towards the Magellanic Clouds - II. OGLE-II Small Magellanic Cloud data

    NASA Astrophysics Data System (ADS)

    Wyrzykowski, Ł.; Kozłowski, S.; Skowron, J.; Belokurov, V.; Smith, M. C.; Udalski, A.; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Szewczyk, O.

    2010-09-01

    The primary goal of this paper is to provide evidence that can prove true or false the hypothesis that dark matter in the Galactic halo can clump into stellar-mass compact objects. If such objects exist, they would act as lenses to external sources in the Magellanic Clouds, giving rise to an observable effect of microlensing. We present the results of our search for such events, based on data from the second phase of the OGLE survey (1996-2000) towards the Small Magellanic Cloud (SMC). The data set we used comprises 2.1 million monitored sources distributed over an area of 2.4deg2. We found only one microlensing event candidate, however its poor-quality light curve limited our discussion of the exact distance to the lensing object. Given a single event, taking blending (crowding of stars) into account for the detection-efficiency simulations and deriving the Hubble Space Telescope (HST)-corrected number of monitored stars, the microlensing optical depth is τ = (1.55 +/- 1.55) × 10-7. This result is consistent with the expected SMC self-lensing signal, with no need to introduce dark matter microlenses. Rejecting the unconvincing event leads to an upper limit on the fraction of dark matter in the form of massive compact halo objects (MACHOs) of f < 20 per cent for deflector masses around 0.4Msolar and f < 11 per cent for masses between 0.003 and 0.2Msolar (95 per cent confidence limit). Our result indicates that the Milky Way's dark matter is unlikely to be clumpy and to form compact objects in the subsolar-mass range. Based on observations obtained with the 1.3-m Warsaw Telescope at the Las Campanas Observatory of the Carnegie Institution of Washington. E-mail: wyrzykow@ast.cam.ac.uk ‡ Name pronunciation: Woocash Vizhikovsky

  18. Is the Large Magellanic Cloud Microlensing Due to an Intervening Dwarf Galaxy?

    NASA Astrophysics Data System (ADS)

    Alcock, C.; Allsman, R. A.; Alves, D. R.; Axelrod, T. S.; Becker, A. C.; Bennett, D. P.; Cook, K. H.; Freeman, K. C.; Griest, K.; Lehner, M. J.; Marshall, S. L.; Minniti, D.; Peterson, B. A.; Pratt, M. R.; Quinn, P. J.; Rodgers, A. W.; Rorabeck, A.; Stubbs, C. W.; Sutherland, W.; Tomaney, A. B.; Vandehei, T.; Welch, D. L.

    1997-11-01

    The recent suggestion that the microlensing events observed toward the Large Magellanic Cloud are due to an intervening Sgr-like dwarf galaxy is examined. A search for foreground RR Lyrae in the MACHO photometry database yields 20 stars whose distance distribution follow the expected halo density profile. Cepheid and red giant branch clump stars in the MACHO database are consistent with membership in the LMC. There is also no evidence in the literature for a distinct kinematic population, for intervening gas, or for the turnoff of such a hypothetical galaxy. We conclude that if the lenses are in a foreground galaxy, it must be a particularly dark galaxy.

  19. MOA-2011-BLG-028Lb: A Neptune-mass Microlensing Planet in the Galactic Bulge

    NASA Astrophysics Data System (ADS)

    Skowron, J.; Udalski, A.; Poleski, R.; Kozłowski, S.; Szymański, M. K.; Wyrzykowski, Ł.; Ulaczyk, K.; Pietrukowicz, P.; Pietrzyński, G.; Soszyński, I.; OGLE Collaboration; Abe, F.; Bennett, D. P.; Bhattacharya, A.; Bond, I. A.; Freeman, M.; Fukui, A.; Hirao, Y.; Itow, Y.; Koshimoto, N.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Nagakane, M.; Ohnishi, K.; Rattenbury, N.; Saito, To.; Sullivan, D. J.; Sumi, T.; Suzuki, D.; Tristram, P. J.; Yonehara, A.; MOA Collaboration; Dominik, M.; Jørgensen, U. G.; Bozza, V.; Harpsøe, K.; Hundertmark, M.; Skottfelt, J.; MiNDSTEp Collaboration

    2016-03-01

    We present the discovery of a Neptune-mass planet orbiting a 0.8+/- 0.3{M}⊙ star in the Galactic bulge. The planet manifested itself during the microlensing event MOA-2011-BLG-028/OGLE-2011-BLG-0203 as a low-mass companion to the lens star. The analysis of the light curve provides the measurement of the mass ratio (1.2+/- 0.2)× {10}-4, which indicates that the mass of the planet is 12-60 Earth masses. The lensing system is located at 7.3 ± 0.7 kpc away from the Earth near the direction of Baade’s Window. The projected separation of the planet at the time of the microlensing event was 3.1-5.2 au. Although the microlens parallax effect is not detected in the light curve of this event, preventing the actual mass measurement, the uncertainties of mass and distance estimation are narrowed by the measurement of the source star proper motion on the OGLE-III images spanning eight years, and by the low amount of blended light seen, proving that the host star cannot be too bright and massive. We also discuss the inclusion of undetected parallax and orbital motion effects into the models and their influence onto the final physical parameters estimates. Based on observations obtained with the 1.3 m Warsaw telescope at the Las Campanas Observatory operated by the Carnegie Institution of Washington.

  20. Reevaluating the feasibility of ground-based Earth-mass microlensing planet detections

    SciTech Connect

    Jung, Youn Kil; Park, Hyuk; Han, Cheongho; Hwang, Kyu-Ha; Shin, In-Gu; Choi, Joon-Young

    2014-05-10

    An important strength of the microlensing method to detect extrasolar planets is its high sensitivity to low-mass planets. However, many believe that microlensing detections of Earth-mass planets from ground-based observation would be difficult because of limits set by finite-source effects. This view comes from the previous estimation of planet detection probability based on the fractional deviation of planetary signals; however, a proper probability estimation is required when considering the source brightness, which is directly related to the photometric precision. In this paper, we reevaluate the feasibility of low-mass planet detections by considering photometric precision for different populations of source stars. From this, we find that the contribution of improved photometric precision to the planetary signal of a giant-source event is large enough to compensate for the decrease in magnification excess caused by finite-source effects. As a result, we conclude that giant-source events are suitable targets for Earth-mass planet detections with significantly higher detection probability than events involved with source stars of smaller radii, and we predict that Earth-mass planets could be detected by prospective high-cadence surveys.

  1. Imaging transient events at high angular resolution

    NASA Astrophysics Data System (ADS)

    Schaefer, Gail H.

    2016-08-01

    Resolving the spatial structure of transient events provides insights into their physical nature and origin. Recent observations using long baseline optical/infrared interferometry have revealed the size, shape, and angular expansion of bright novae within a few days after their outbursts. This has implications for understanding the timescale for the development of asymmetric features in novae ejecta. Additionally, combining spectroscopic measurements of the expansion velocity with the angular expansion rate provides a way to measure a geometric distance to the nova. In this paper, I provide a review of interferometric observations of novae, with a focus on recent results on the expansion and spatial structure of nova V339 Del in 2013. I also discuss other promising applications of interferometry to transient sources, such as measuring the image size and centroid displacements to measure planetary masses in gravitational microlensing events. Given the timescales of transient events, it is critical for interferometric arrays to respond rapidly to targets of opportunity in order to optimize the instrumental sensitivity and baselines required to resolve the source while its brightness and size change over time.

  2. Microlensing Optical Depth towards the Galactic Bulge Using Clump Giants from the MACHO Survey

    SciTech Connect

    Popowski, P; Griest, K; Thomas, C L; Cook, K H; Bennett, D P; Becker, A C; Alves, D R; Minniti, D; Drake, A J; Alcock, C; Allsman, R A; Axelrod, T S; Freeman, K C; Geha, M; Lehner, M J; Marshall, S L; Nelson, C A; Peterson, B A; Quinn, P J; Stubbs, C W; Sutherland, W; Vandehei, T; Welch, D

    2005-07-14

    Using 7 years of MACHO survey data, we present a new determination of the optical depth to microlensing towards the Galactic bulge. We select the sample of 62 microlensing events (60 unique) on clump giant sources and perform a detailed efficiency analysis. We use only the clump giant sources because these are bright bulge stars and are not as strongly affected by blending as other events. Using a subsample of 42 clump events concentrated in an area of 4.5 deg{sup 2} with 739000 clump giant stars, we find {tau} = 2.17{sub -0.38}{sup +0.47} x 10{sup -6} at (l,b) = (1{sup o}.50, -2{sup o}.68), somewhat smaller than found in most previous MACHO studies, but in excellent agreement with recent theoretical predictions. We also present the optical depth in each of the 19 fields in which we detected events, and find limits on optical depth for fields with no events. The errors in optical depth in individual fields are dominated by Poisson noise. We measure optical depth gradients of (1.06 {+-} 0.71) x 10{sup -6}deg{sup -1} and (0.29 {+-} 0.43) x 10{sup -6}deg{sup -1} in the galactic latitude b and longitude l directions, respectively. Finally, we discuss the possibility of anomalous duration distribution of events in the field 104 centered on (l,b) = (3{sup o}.11, -3{sup o}.01) as well as investigate spatial clustering of events in all fields.

  3. Preparing for the WFIRST Microlensing Survey: Simulations, Requirements, Survey Strategies, and Precursor Observations

    NASA Astrophysics Data System (ADS)

    Gaudi, Bernard

    As one of the four primary investigations of the Wide Field Infrared Survey Telescope (WFIRST) mission, the microlensing survey will monitor several square degrees of the Galactic bulge for a total of roughly one year. Its primary science goal is to "Complete the statistical census of planetary systems in the Galaxy, from the outer habitable zone to free floating planets, including analogs of all of the planets in our Solar System with the mass of Mars or greater.'' WFIRST will therefore (a) measure the mass function of cold bound planets with masses greater than that of roughly twice the mass of the moon, including providing an estimate of the frequency of sub-Mars-mass embryos, (b) determine the frequency of free-floating planets with masses down to the Earth and below, (c) inform the frequency and habitability of potentially habitable worlds, and (d) revolutionize our understanding of the demographics of cold planets with its exquisite sensitivity to, and large expected yield of, planets in a broad and unexplored region of parameter space. In order for the microlensing survey to be successful, we must develop a plan to go from actual survey observations obtained by the WFIRST telescope and hardware to the final science products. This plan will involve many steps, the development of software, data reduction, and analysis tools at each step, and a list of requirements for each of these components. The overarching goal of this proposal is thus to develop a complete flowdown from the science goals of the microlensing survey to the mission design and hardware components. We have assembled a team of scientists with the breadth of expertise to achieve this primary goal. Our specific subgoals are as follows. Goal 1: We will refine the input Galactic models in order to provide improved microlensing event rates in the WFIRST fields. Goal 2: We will use the improved event rate estimates, along with improvements in our simulation methodology, to provide higher

  4. Reconfigurable and responsive droplet-based compound micro-lenses

    NASA Astrophysics Data System (ADS)

    Nagelberg, Sara; Zarzar, Lauren D.; Nicolas, Natalie; Subramanian, Kaushikaram; Kalow, Julia A.; Sresht, Vishnu; Blankschtein, Daniel; Barbastathis, George; Kreysing, Moritz; Swager, Timothy M.; Kolle, Mathias

    2017-03-01

    Micro-scale optical components play a crucial role in imaging and display technology, biosensing, beam shaping, optical switching, wavefront-analysis, and device miniaturization. Herein, we demonstrate liquid compound micro-lenses with dynamically tunable focal lengths. We employ bi-phase emulsion droplets fabricated from immiscible hydrocarbon and fluorocarbon liquids to form responsive micro-lenses that can be reconfigured to focus or scatter light, form real or virtual images, and display variable focal lengths. Experimental demonstrations of dynamic refractive control are complemented by theoretical analysis and wave-optical modelling. Additionally, we provide evidence of the micro-lenses' functionality for two potential applications--integral micro-scale imaging devices and light field display technology--thereby demonstrating both the fundamental characteristics and the promising opportunities for fluid-based dynamic refractive micro-scale compound lenses.

  5. Reconfigurable and responsive droplet-based compound micro-lenses

    PubMed Central

    Nagelberg, Sara; Zarzar, Lauren D.; Nicolas, Natalie; Subramanian, Kaushikaram; Kalow, Julia A.; Sresht, Vishnu; Blankschtein, Daniel; Barbastathis, George; Kreysing, Moritz; Swager, Timothy M.; Kolle, Mathias

    2017-01-01

    Micro-scale optical components play a crucial role in imaging and display technology, biosensing, beam shaping, optical switching, wavefront-analysis, and device miniaturization. Herein, we demonstrate liquid compound micro-lenses with dynamically tunable focal lengths. We employ bi-phase emulsion droplets fabricated from immiscible hydrocarbon and fluorocarbon liquids to form responsive micro-lenses that can be reconfigured to focus or scatter light, form real or virtual images, and display variable focal lengths. Experimental demonstrations of dynamic refractive control are complemented by theoretical analysis and wave-optical modelling. Additionally, we provide evidence of the micro-lenses' functionality for two potential applications—integral micro-scale imaging devices and light field display technology—thereby demonstrating both the fundamental characteristics and the promising opportunities for fluid-based dynamic refractive micro-scale compound lenses. PMID:28266505

  6. Liquid crystal bubbles forming a tunable micro-lenses array

    NASA Astrophysics Data System (ADS)

    Hamdi, R.; Petriashvili, G.; Lombardo, G.; De Santo, M. P.; Barberi, R.

    2011-10-01

    Cholesteric liquid crystals with long pitch confined in homeotropic cells can be used to generate stable but distorted and localized liquid crystal structures exhibiting spherulitic textures, known as "bubbles." As these bubbles can be induced by an external electric field with a narrow range following the confinement ratio C=d/p ≈1 (d representing cell thickness and p representing cholesteric pitch), it is possible to obtain electrically controlled micro-lenses. Here we investigated the optical and electro-optical properties of such liquid crystal bubbles for creating an array of micro-lenses with electrically tunable focal length.

  7. A MICROLENSING MEASUREMENT OF DARK MATTER FRACTIONS IN THREE LENSING GALAXIES

    SciTech Connect

    Bate, N. F.; Webster, R. L.; Wyithe, J. S. B.; Floyd, D. J. E.

    2011-04-10

    Direct measurements of dark matter distributions in galaxies are currently only possible through the use of gravitational lensing observations. Combinations of lens modeling and stellar velocity dispersion measurements provide the best constraints on dark matter distributions in individual galaxies, however they can be quite complex. In this paper, we use observations and simulations of gravitational microlensing to measure the smooth (dark) matter mass fraction at the position of lensed images in three lens galaxies: MG 0414+0534, SDSS J0924+0219, and Q2237+0305. The first two systems consist of early-type lens galaxies, and both display a flux ratio anomaly in their close image pair. Anomalies such as these suggest that a high smooth matter percentage is likely, and indeed we prefer {approx}50% smooth matter in MG 0414+0534 and {approx}80% in SDSS J0924+0219 at the projected locations of the lensed images. Q2237+0305 differs somewhat in that its lensed images lie in the central kiloparsec of the barred spiral lens galaxy, where we expect stars to dominate the mass distribution. In this system, we find a smooth matter percentage that is consistent with zero.

  8. Gravitation research

    NASA Technical Reports Server (NTRS)

    Weiss, R.; Muehlner, D. J.; Benford, R. L.; Owens, D. K.; Pierre, N. A.; Rosenbluh, M.

    1972-01-01

    Balloon measurements were made of the far infrared background radiation. The radiometer used and its calibration are discussed. An electromagnetically coupled broadband gravitational antenna is also considered. The proposed antenna design and noise sources in the antenna are reviewed. A comparison is made between interferometric broadband and resonant bar antennas for the detection of gravitational wave pulses.

  9. Microlensing Constraints on Broad Absorption and Emission Line Flows in the Quasar H1413+117

    NASA Astrophysics Data System (ADS)

    O'Dowd, Matthew J.; Bate, Nicholas F.; Webster, Rachel L.; Labrie, Kathleen; Rogers, Joshua

    2015-11-01

    We present new integral field spectroscopy of the gravitationally lensed broad absorption line (BAL) quasar H1413+117, covering the ultraviolet restframe spectral range. We observe strong microlensing signatures in lensed image D, and we use this microlensing to simultaneously constrain both the broad emission and broad absorption line gas. The wavelength independence of image D magnifications across the broad emission lines (BELs) indicates a lower limit on the broad emission line region (BELR) size equal to the Einstein radius (ER) of the system: ≳11 {(< M> /{M}⊙ )}0.5 lt-day for a lens redshift of 1.4 and ≳15 {(< M> /{M}⊙ )}0.5 lt-day for zL = 0.94. Lensing simulations verify that the observed wavelength independence is very unlikely for BELRs with significant velocity stratification at size scales below an ER. We perform spectral decomposition to derive the intrinsic BEL and continuum spectrum, subject to BAL absorption. We reconstruct the intrinsic BAL absorption profile, whose features allow us to constrain outflow kinematics in the context of a disk-wind model. We find a very sharp, blueshifted onset of absorption of 1500 km s-1 in both C iv and N v, which may correspond to an inner edge of a disk-wind’s radial outflow. The lower ionization Si iv and Al iii have higher-velocity absorption onsets, consistent with a decreasing ionization parameter with radius in an accelerating outflow. There is evidence of strong absorption in the BEL component, which indicates a high covering factor for absorption over two orders of magnitude in outflow radius.

  10. Gravitational vacuum

    NASA Astrophysics Data System (ADS)

    Grigoryan, L. S.; Saakyan, G. S.

    1984-09-01

    The existence of a special gravitational vacuum is considered in this paper. A phenomenological method differing from the traditional Einsteinian formalization is utilized. Vacuum, metric and matter form a complex determined by field equations and at great distances from gravitational masses vacuum effects are small but could be large in powerful fields. Singularities and black holes justify the approach as well as the Ambartsmyan theory concerning the existence of supermassive and superdense prestallar bodies that then disintegrate. A theory for these superdense bodies is developed involving gravitational field equations that describe the vacuum by an energy momentum tensor and define the field and mass distribution. Computations based on the theory for gravitational radii with incompressible liquid models adequately reflecting real conditions indicate that a gravitational vacuum could have considerable effects on superdense stars and could have radical effects for very large masses.

  11. OGLE-2014-BLG-0257L: A Microlensing Brown Dwarf Orbiting a Low-mass M Dwarf

    NASA Astrophysics Data System (ADS)

    Han, C.; Jung, Y. K.; Udalski, A.; Gould, A.; Bozza, V.; Szymański, M. K.; Soszyński, I.; Poleski, R.; Kozłowski, S.; Pietrukowicz, P.; Skowron, J.; Ulaczyk, K.; Wyrzykowski, Ł.; OGLE Collaboration

    2016-05-01

    In this paper, we report the discovery of a binary composed of a brown dwarf (BD) and a low-mass M dwarf from observation of the microlensing event OGLE-2014-BLG-0257. The resolution of the very brief caustic crossing combined with the detection of subtle continuous deviation in the lensing light curve induced by the Earth’s orbital motion enable us to precisely measure both the Einstein radius {θ }{{E}} and the lens parallax {π }{{E}}, which are the two quantities needed to unambiguously determine the mass and distance to the lens. It is found that the companion is a substellar BD with a mass of 0.036+/- 0.005 {M}⊙ (37.7+/- 5.2 {M}{{J}}) and it is orbiting an M dwarf with a mass of 0.19+/- 0.02 {M}⊙ . The binary is located at a distance of 1.25 ± 0.13 kpc toward the Galactic bulge and the projected separation between the binary components is 0.61 ± 0.07 au. The separation scaled by the mass of the host is 3.2 {{au}}/{M}⊙ . Based on the assumption that separations scale with masses, the discovered BD is located in the BD desert. With the growing sample of BDs in various environments, microlensing will provide a powerful probe of BDs in the Galaxy.

  12. The complete catalogue of light curves in equal-mass binary microlensing

    NASA Astrophysics Data System (ADS)

    Liebig, Christine; D'Ago, Giuseppe; Bozza, Valerio; Dominik, Martin

    2015-06-01

    The light curves observed in microlensing events due to binary lenses span an extremely wide variety of forms, characterized by U-shaped caustic crossings and/or additional smoother peaks. However, all peaks of the binary-lens light curve can be traced back to features of caustics of the lens system. Moreover, all peaks can be categorized as one of only four types (cusp-grazing, cusp-crossing, fold-crossing or fold-grazing). This enables us to present the first complete map of the parameter space of the equal-mass case by identifying regions in which light curves feature the same number and nature of peaks. We find that the total number of morphologies that can be obtained is 73 out of 232 different regions. The partition of the parameter space so-obtained provides a new key to optimize modelling of observed events through a clever choice of initial conditions for fitting algorithms.

  13. OGLE-2015-BLG-0196: Ground-based Gravitational Microlens Parallax Confirmed by Space-based Observation

    NASA Astrophysics Data System (ADS)

    Han, C.; Udalski, A.; Gould, A.; Zhu, Wei; and; Szymański, M. K.; Soszyński, I.; Skowron, J.; Mróz, P.; Poleski, R.; Pietrukowicz, P.; Kozłowski, S.; Ulaczyk, K.; Pawlak, M.; The OGLE Collaboration; Yee, J. C.; Beichman, C.; Calchi Novati, S.; Carey, S.; Bryden, C.; Fausnaugh, M.; Gaudi, B. S.; Henderson, Calen B.; Shvartzvald, Y.; Wibking, B.; The Spitzer Microlensing Team

    2017-01-01

    In this paper, we present an analysis of the binary gravitational microlensing event OGLE-2015-BLG-0196. The event lasted for almost a year, and the light curve exhibited significant deviations from the lensing model based on the rectilinear lens-source relative motion, enabling us to measure the microlens parallax. The ground-based microlens parallax is confirmed by the data obtained from space-based microlens observations using the Spitzer telescope. By additionally measuring the angular Einstein radius from the analysis of the resolved caustic crossing, the physical parameters of the lens are determined up to the twofold degeneracy, u0 < 0 and u0 > 0, solutions caused by the well-known “ecliptic” degeneracy. It is found that the binary lens is composed of two M dwarf stars with similar masses, M1 = 0.38 ± 0.04 M⊙ (0.50 ± 0.05 M⊙) and M2 = 0.38 ± 0.04 M⊙ (0.55 ± 0.06 M⊙), and the distance to the lens is DL = 2.77 ± 0.23 kpc (3.30 ± 0.29 kpc). Here the physical parameters outside and inside the parentheses are for the u0 < 0 and u0 > 0 solutions, respectively.

  14. Exoplanet Demographics with a Space-Based Microlensing Survey

    NASA Astrophysics Data System (ADS)

    Gaudi, B. Scott

    2012-05-01

    Measurements of the frequency of exoplanets over a broad range of planet and host star properties provide fundamental empirical constraints on theories of planet formation and evolution. Because of its unique sensitivity to low-mass, long-period, and free-floating planets, microlensing is an essential complement to our arsenal of planet detection methods. I motivate microlensing surveys for exoplanets, and in particular describe how they can be used to test the currently-favored paradigm for planet formation, as well as inform our understanding of the frequency and potential habitability of low-mass planets located in the habitable zones of their host stars. I explain why a space-based mission is necessary to realize the full potential of microlensing, and outline the expected returns of such surveys. When combined with the results from complementary surveys such as Kepler, a space-based microlensing survey will yield a nearly complete picture of the demographics of planetary systems throughout the Galaxy.

  15. Microlenses with tuned focal characteristics for optical wireless imaging

    NASA Astrophysics Data System (ADS)

    Jin, Xian; Guerrero, Daniel; Klukas, Richard; Holzman, Jonathan F.

    2014-07-01

    Microlenses are fabricated and investigated for integrated imaging applications. The microlenses are fabricated by an in situ polymer electro-dispensing technique that enables user-controlled microlens sizes and shapes, by direct-dispensing and voltage-tuning with a metal micro-needle tip in a filler solution. Theoretical and experimental analyses are carried out for three limiting-cases of electro-dispensed microlenses: an acute-angle microlens with a 30° contact angle, a right-angle microlens with a 90° contact angle, and an obtuse-angle microlens with a 120° contact angle. It is found that the right-angle microlens, with a 500 μm diameter, yields an especially short focal length (700 μm) and exceedingly large numerical aperture (0.533). These characteristics can meet the needs of emerging applications, such as optical wireless devices, which demand compact device integration and broad field-of-view imaging. The microlenses are tested in optical wireless imaging receivers, for signal-to-noise ratio performance, and it is found that the right-angle microlens can offer significant (10 dB) performance enhancements.

  16. Gravitating Hopfions

    SciTech Connect

    Shnir, Ya. M.

    2015-12-15

    We construct solutions of the 3 + 1 dimensional Faddeev–Skyrme model coupled to Einstein gravity. The solutions are static and asymptotically flat. They are characterized by a topological Hopf number. We investigate the dependence of the ADM masses of gravitating Hopfions on the gravitational coupling. When gravity is coupled to flat space solutions, a branch of gravitating Hopfion solutions arises and merges at a maximal value of the coupling constant with a second branch of solutions. This upper branch has no flat space limit. Instead, in the limit of a vanishing coupling constant, it connects to either the Bartnik–McKinnon or a generalized Bartnik–McKinnon solution. We further find that in the strong-coupling limit, there is no difference between the gravitating solitons of the Skyrme model and the Faddeev–Skyrme model.

  17. Gravitational induction

    NASA Astrophysics Data System (ADS)

    Bini, Donato; Cherubini, Christian; Chicone, Carmen; Mashhoon, Bahram

    2008-11-01

    We study the linear post-Newtonian approximation to general relativity known as gravitoelectromagnetism (GEM); in particular, we examine the similarities and differences between GEM and electrodynamics. Notwithstanding some significant differences between them, we find that a special nonstationary metric in GEM can be employed to show explicitly that it is possible to introduce gravitational induction within GEM in close analogy with Faraday's law of induction and Lenz's law in electrodynamics. Some of the physical implications of gravitational induction are briefly discussed.

  18. PROSPECTS FOR CHARACTERIZING HOST STARS OF THE PLANETARY SYSTEM DETECTIONS PREDICTED FOR THE KOREAN MICROLENSING TELESCOPE NETWORK

    SciTech Connect

    Henderson, Calen B.

    2015-02-10

    I investigate the possibility of constraining the flux of the lens (i.e., host star) for the types of planetary systems the Korean Microlensing Telescope Network is predicted to find. I examine the potential to obtain lens flux measurements by (1) imaging the lens once it is spatially resolved from the source, (2) measuring the elongation of the point-spread function of the microlensing target (lens+source) when the lens and source are still unresolved, and (3) taking prompt follow-up photometry. In each case I simulate the observing programs for a representative example of current ground-based adaptive optics (AO) facilities (specifically NACO on the Very Large Telescope), future ground-based AO facilities (GMTIFS on the Giant Magellan Telescope, GMT), and future space telescopes (NIRCAM on the James Webb Space Telescope, JWST). Given the predicted distribution of relative lens-source proper motions, I find that the lens flux could be measured to a precision of σ{sub H{sub ℓ}}≤0.1 for ≳60% of planet detections ≥5 yr after each microlensing event for a simulated observing program using GMT, which images resolved lenses. NIRCAM on JWST would be able to carry out equivalently high-precision measurements for ∼28% of events Δt = 10 yr after each event by imaging resolved lenses. I also explore the effects various blend components would have on the mass derived from prompt follow-up photometry, including companions to the lens, companions to the source, and unassociated interloping stars. I find that undetected blend stars would cause catastrophic failures (i.e., >50% fractional uncertainty in the inferred lens mass) for ≲ (16 · f {sub bin})% of planet detections, where f {sub bin} is the binary fraction, with the majority of these failures occurring for host stars with mass ≲0.3 M {sub ☉}.

  19. Gravitational Waves from Gravitational Collapse.

    PubMed

    Fryer, Chris L; New, Kimberly C B

    2003-01-01

    Gravitational wave emission from stellar collapse has been studied for more than three decades. Current state-of-the-art numerical investigations of collapse include those that use progenitors with more realistic angular momentum profiles, properly treat microphysics issues, account for general relativity, and examine non-axisymmetric effects in three dimensions. Such simulations predict that gravitational waves from various phenomena associated with gravitational collapse could be detectable with ground-based and space-based interferometric observatories. This review covers the entire range of stellar collapse sources of gravitational waves: from the accretion induced collapse of a white dwarf through the collapse down to neutron stars or black holes of massive stars to the collapse of supermassive stars.

  20. Gravitational Waves from Gravitational Collapse.

    PubMed

    Fryer, Chris L; New, Kimberly C B

    2011-01-01

    Gravitational-wave emission from stellar collapse has been studied for nearly four decades. Current state-of-the-art numerical investigations of collapse include those that use progenitors with more realistic angular momentum profiles, properly treat microphysics issues, account for general relativity, and examine non-axisymmetric effects in three dimensions. Such simulations predict that gravitational waves from various phenomena associated with gravitational collapse could be detectable with ground-based and space-based interferometric observatories. This review covers the entire range of stellar collapse sources of gravitational waves: from the accretion-induced collapse of a white dwarf through the collapse down to neutron stars or black holes of massive stars to the collapse of supermassive stars.

  1. Gravitational waves from gravitational collapse

    SciTech Connect

    Fryer, Christopher L; New, Kimberly C

    2008-01-01

    Gravitational wave emission from stellar collapse has been studied for nearly four decades. Current state-of-the-art numerical investigations of collapse include those that use progenitors with more realistic angular momentum profiles, properly treat microphysics issues, account for general relativity, and examine non-axisymmetric effects in three dimensions. Such simulations predict that gravitational waves from various phenomena associated with gravitational collapse could be detectable with ground-based and space-based interferometric observatories. This review covers the entire range of stellar collapse sources of gravitational waves: from the accretion induced collapse of a white dwarf through the collapse down to neutron stars or black holes of massive stars to the collapse of supermassive stars.

  2. The Theory of Multiscale Gravitational Lensing

    NASA Astrophysics Data System (ADS)

    Keeton, Charles

    2005-07-01

    Strong gravitational lensing probes the mass distributions of distant galaxies on scales from tens of kiloparsecs {dark matter halos and "macrolensing"} through parsecs {dark matter substructure and "millilensing"} all the way down to individual stars {"microlensing"}. Wonderful data are now available, thanks in large part to HST. However, the theoretical understanding of lensing on different scales is much less mature, which has complicated efforts to interpret the data. We have begun a comprehensive theoretical study of multiscale lensing, to develop a formalism that will enable us both to interpret existing data and to inspire and guide new observations. In this proposal, we specifically seek to develop the first code that simultaneously includes macro-, milli-, and microlensing. We will then use it to: {1} Find clear observational signatures that reveal the scale{s} being probed in data, and then resolve the debate about whether millilensing truly reveals Cold Dark Matter substructure. {2} Show how observations at different scales can constrain the mass function of stars in lens galaxies, and apply the method to existing HST data for seven distant galaxies. {3} Examine non-linearities that link micro-, milli-, and macrolensing, and use the combined analysis to open a new window on dark matter studies with strong lensing. We will also make the code available to the community as part of PI Keeton's public lensing software.

  3. Constraining the Frequency of Free-floating Planets from a Synthesis of Microlensing, Radial Velocity, and Direct Imaging Survey Results

    NASA Astrophysics Data System (ADS)

    Clanton, Christian; Gaudi, B. Scott

    2017-01-01

    A microlensing survey by Sumi et al. exhibits an overabundance of short-timescale events (STEs; tE < 2 days) relative to what is expected from known stellar populations and a smooth power-law extrapolation down to the brown dwarf regime. This excess has been interpreted as a population of approximately Jupiter-mass objects that outnumber main-sequence stars nearly twofold; however the microlensing data alone cannot distinguish between events due to wide-separation (a ≳ 10 au) and free-floating planets. Assuming these STEs are indeed due to planetary-mass objects, we aim to constrain the fraction of these events that can be explained by bound but wide-separation planets. We fit the observed timescale distribution with a lens mass function comprised of brown dwarfs, main-sequence stars, and stellar remnants, finding and thus corroborating the initial identification of an excess of STEs. We then include a population of bound planets that are expected not to show signatures of the primary lens (host) in their microlensing light curves and that are also consistent with results from representative microlensing, radial velocity, and direct imaging surveys. We find that bound planets alone cannot explain the entire STE excess without violating the constraints from the surveys we consider and thus some fraction of these events must be due to free-floating planets, if our model for bound planets holds. We estimate a median fraction of STEs due to free-floating planets to be f = 0.67 (0.23 ≤ f ≤ 0.85 at 95% confidence) when assuming “hot-start” planet evolutionary models and f = 0.58 (0.14 ≤ f ≤ 0.83 at 95% confidence) for “cold-start” models. Assuming a delta-function distribution of free-floating planets of mass {m}p=2 {M}{Jup} yields a number of free-floating planets per main-sequence star of N = 1.4 (0.48 ≤ N ≤ 1.8 at 95% confidence) in the “hot-start” case and N = 1.2 (0.29 ≤ N ≤ 1.8 at 95% confidence) in the “cold-start” case.

  4. Reflection aspherical microlenses for planar optics fabricated by electron-beam lithography.

    PubMed

    Shiono, T; Ogawa, H

    1992-04-15

    Reflection aspherical microlenses are proposed for planar optics. These microlenses have the structure of a nonconcentric elliptical concave mirror. Broadband light can be used for these microlenses because these microlenses have no chromatic aberration. The microlens fabricated by electron-beam lithography and Ag deposition was found to have a smooth surface as designed. The focal length of the microlens was constant independent of the wavelength. The measured spot sizes agreed with diffraction-limited values at two different wavelengths. By using the array of this microlens, multiple images with excellent contrast were obtained under incoherent white-light illumination.

  5. Astrophysical Applications of Gravitational Lensing

    NASA Astrophysics Data System (ADS)

    Mediavilla, Evencio; Muñoz, Jose A.; Garzón, Francisco; Mahoney, Terence J.

    2016-10-01

    Contributors; Participants; Preface; Acknowledgements; 1. Lensing basics Sherry H. Suyu; 2. Exoplanet microlensing Andrew Gould; 3. Case studies of microlensing Veronica Motta and Emilio Falco; 4. Microlensing of quasars and AGN Joachim Wambsganss; 5. DM in clusters and large-scale structure Peter Schneider; 6. The future of strong lensing Chris Fassnacht; 7. Methods for strong lens modelling Charles Keeton; 8. Tutorial on inverse ray shooting Jorge Jimenez-Vicente.

  6. The First Circumbinary Planet Found by Microlensing: OGLE-2007-BLG-349L(AB)c

    NASA Technical Reports Server (NTRS)

    Bennett, D. P.; Rhie, S. H.; Udalski, A.; Gould, A.; Tsapras, Y.; Kubas, D.; Bond, I. A.; Greenhill, J.; Cassan, A.; Rattenbury, N. J.; Boyajian, T. S.; Luhn, J.; Penny, M. T.; Anderson, J.; Abe, F.; Bhattacharya, A.; Botzler, C. S.; Donachie, M.; Freeman, M.; Fukui, A.; Hirao, Y.; Itow, Y.; Koshimoto, N.; Li, M. C. A.; Suzuki, Daisuke

    2016-01-01

    We present the analysis of the first circumbinary planet microlensing event, OGLE-2007-BLG-349. This event has a strong planetary signal that is best fit with a mass ratio of q approx. = 3.4×10(exp -4), but there is an additional signal due to an additional lens mass, either another planet or another star. We find acceptable light-curve fits with two classes of models: two-planet models (with a single host star) and circumbinary planet models. The light curve also reveals a significant microlensing parallax effect, which constrains the mass of the lens system to be M(sub L) approx. = 0.7 Stellar Mass. Hubble Space Telescope (HST) images resolve the lens and source stars from their neighbors and indicate excess flux due to the star(s) in the lens system. This is consistent with the predicted flux from the circumbinary models, where the lens mass is shared between two stars, but there is not enough flux to be consistent with the two-planet, one-star models. So, only the circumbinary models are consistent with the HST data. They indicate a planet of mass m(sub c) = 80 +/- 13 Stellar Mass, orbiting a pair of M dwarfs with masses of M(sub A) = 0.41+/- 0.07 and M(sub B) = 0.30 +/- 0.07, which makes this the lowest-mass circumbinary planet system known. The ratio of the separation between the planet and the center of mass to the separation of the two stars is approx.40, so unlike most of the circumbinary planets found by Kepler, the planet does not orbit near the stability limit.

  7. The First Circumbinary Planet Found by Microlensing: OGLE-2007-BLG-349L(AB)c

    NASA Astrophysics Data System (ADS)

    Bennett, D. P.; Rhie, S. H.; Udalski, A.; Gould, A.; Tsapras, Y.; Kubas, D.; Bond, I. A.; Greenhill, J.; Cassan, A.; Rattenbury, N. J.; Boyajian, T. S.; Luhn, J.; Penny, M. T.; Anderson, J.; Abe, F.; Bhattacharya, A.; Botzler, C. S.; Donachie, M.; Freeman, M.; Fukui, A.; Hirao, Y.; Itow, Y.; Koshimoto, N.; Li, M. C. A.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Nagakane, M.; Ohnishi, K.; Oyokawa, H.; Perrott, Y. C.; Saito, To.; Sharan, A.; Sullivan, D. J.; Sumi, T.; Suzuki, D.; Tristram, P. J.; Yonehara, A.; Yock, P. C. M.; MOA Collaboration; Szymański, M. K.; Soszyński, I.; Ulaczyk, K.; Wyrzykowski, Ł.; OGLE Collaboration; Allen, W.; DePoy, D.; Gal-Yam, A.; Gaudi, B. S.; Han, C.; Monard, I. A. G.; Ofek, E.; Pogge, R. W.; μFUN Collaboration; Street, R. A.; Bramich, D. M.; Dominik, M.; Horne, K.; Snodgrass, C.; Steele, I. A.; Robonet Collaboration; Albrow, M. D.; Bachelet, E.; Batista, V.; Beaulieu, J.-P.; Brillant, S.; Caldwell, J. A. R.; Cole, A.; Coutures, C.; Dieters, S.; Dominis Prester, D.; Donatowicz, J.; Fouqué, P.; Hundertmark, M.; Jørgensen, U. G.; Kains, N.; Kane, S. R.; Marquette, J.-B.; Menzies, J.; Pollard, K. R.; Ranc, C.; Sahu, K. C.; Wambsganss, J.; Williams, A.; Zub, M.; PLANET Collaboration

    2016-11-01

    We present the analysis of the first circumbinary planet microlensing event, OGLE-2007-BLG-349. This event has a strong planetary signal that is best fit with a mass ratio of q ≈ 3.4 × 10-4, but there is an additional signal due to an additional lens mass, either another planet or another star. We find acceptable light-curve fits with two classes of models: two-planet models (with a single host star) and circumbinary planet models. The light curve also reveals a significant microlensing parallax effect, which constrains the mass of the lens system to be M L ≈ 0.7 {M}⊙ . Hubble Space Telescope (HST) images resolve the lens and source stars from their neighbors and indicate excess flux due to the star(s) in the lens system. This is consistent with the predicted flux from the circumbinary models, where the lens mass is shared between two stars, but there is not enough flux to be consistent with the two-planet, one-star models. So, only the circumbinary models are consistent with the HST data. They indicate a planet of mass m c = 80 ± 13 {M}\\oplus , orbiting a pair of M dwarfs with masses of M A = 0.41 ± 0.07 and M B = 0.30 ± 0.07, which makes this the lowest-mass circumbinary planet system known. The ratio of the separation between the planet and the center of mass to the separation of the two stars is ˜40, so unlike most of the circumbinary planets found by Kepler, the planet does not orbit near the stability limit.

  8. OGLE-2011-BLG-0265Lb: A Jovian Microlensing Planet Orbiting an M Dwarf

    NASA Astrophysics Data System (ADS)

    Skowron, J.; Shin, I.-G.; Udalski, A.; Han, C.; Sumi, T.; Shvartzvald, Y.; Gould, A.; Dominis Prester, D.; Street, R. A.; Jørgensen, U. G.; Bennett, D. P.; Bozza, V.; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Poleski, R.; Kozłowski, S.; Pietrukowicz, P.; Ulaczyk, K.; Wyrzykowski, Ł.; OGLE Collaboration; Abe, F.; Bhattacharya, A.; Bond, I. A.; Botzler, C. S.; Freeman, M.; Fukui, A.; Fukunaga, D.; Itow, Y.; Ling, C. H.; Koshimoto, N.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Namba, S.; Ohnishi, K.; Philpott, L. C.; Rattenbury, N.; Saito, T.; Sullivan, D. J.; Suzuki, D.; Tristram, P. J.; Yock, P. C. M.; MOA Collaboration; Maoz, D.; Kaspi, S.; Friedmann, M.; Wise Group; Almeida, L. A.; Batista, V.; Christie, G.; Choi, J.-Y.; DePoy, D. L.; Gaudi, B. S.; Henderson, C.; Hwang, K.-H.; Jablonski, F.; Jung, Y. K.; Lee, C.-U.; McCormick, J.; Natusch, T.; Ngan, H.; Park, H.; Pogge, R. W.; Yee, J. C.; μFUN Collaboration; Albrow, M. D.; Bachelet, E.; Beaulieu, J.-P.; Brillant, S.; Caldwell, J. A. R.; Cassan, A.; Cole, A.; Corrales, E.; Coutures, Ch.; Dieters, S.; Donatowicz, J.; Fouqué, P.; Greenhill, J.; Kains, N.; Kane, S. R.; Kubas, D.; Marquette, J.-B.; Martin, R.; Menzies, J.; Pollard, K. R.; Ranc, C.; Sahu, K. C.; Wambsganss, J.; Williams, A.; Wouters, D.; PLANET Collaboration; Tsapras, Y.; Bramich, D. M.; Horne, K.; Hundertmark, M.; Snodgrass, C.; Steele, I. A.; RoboNet Collaboration; Alsubai, K. A.; Browne, P.; Burgdorf, M. J.; Calchi Novati, S.; Dodds, P.; Dominik, M.; Dreizler, S.; Fang, X.-S.; Gu, C.-H.; Hardis; Harpsøe, K.; Hessman, F. V.; Hinse, T. C.; Hornstrup, A.; Jessen-Hansen, J.; Kerins, E.; Liebig, C.; Lund, M.; Lundkvist, M.; Mancini, L.; Mathiasen, M.; Penny, M. T.; Rahvar, S.; Ricci, D.; Scarpetta, G.; Skottfelt, J.; Southworth, J.; Surdej, J.; Tregloan-Reed, J.; Wertz, O.; MiNDSTEp Consortium

    2015-05-01

    We report the discovery of a Jupiter-mass planet orbiting an M-dwarf star that gave rise to the microlensing event OGLE-2011-BLG-0265. Such a system is very rare among known planetary systems and thus the discovery is important for theoretical studies of planetary formation and evolution. High-cadence temporal coverage of the planetary signal, combined with extended observations throughout the event, allows us to accurately model the observed light curve. However, the final microlensing solution remains degenerate, yielding two possible configurations of the planet and the host star. In the case of the preferred solution, the mass of the planet is {{M}p}=0.9+/- 0.3 {{M}J}, and the planet is orbiting a star with a mass M=0.22+/- 0.06 {{M}⊙ }. The second possible configuration (2σ away) consists of a planet with {{M}p}=0.6+/- 0.3 {{M}J} and host star with M=0.14+/- 0.06 {{M}⊙ }. The system is located in the Galactic disk 3-4 kpc toward the Galactic bulge. In both cases, with an orbit size of 1.5-2.0 AU, the planet is a “cold Jupiter”—located well beyond the “snow line” of the host star. Currently available data make the secure selection of the correct solution difficult, but there are prospects for lifting the degeneracy with additional follow-up observations in the future, when the lens and source star separate.

  9. On the gravitational redshift

    NASA Astrophysics Data System (ADS)

    Wilhelm, Klaus; Dwivedi, Bhola N.

    2014-08-01

    The study of the gravitational redshift-a relative wavelength increase of ≈2×10-6 was predicted for solar radiation by Einstein in 1908-is still an important subject in modern physics. In a dispute whether or not atom interferometry experiments can be employed for gravitational redshift measurements, two research teams have recently disagreed on the physical cause of the shift. Regardless of any discussion on the interferometer aspect-we find that both groups of authors miss the important point that the ratio of gravitational to the electrostatic forces is generally very small. For instance, the ratio of the gravitational force acting on an electron in a hydrogen atom situated in the Sun’s photosphere to the electrostatic force between the proton and the electron in such an atom is approximately 3×10-21. A comparison of this ratio with the predicted and observed solar redshift indicates a discrepancy of many orders of magnitude. With Einstein’s early assumption that the frequencies of spectral lines depend only on the generating ions themselves as starting point, we show that a solution can be formulated based on a two-step process in analogy with Fermi’s treatment of the Doppler effect. It provides a sequence of physical processes in line with the conservation of energy and momentum resulting in the observed shift and does not employ a geometric description. The gravitational field affects the release of the photon and not the atomic transition. The control parameter is the speed of light. The atomic emission is then contrasted with the gravitational redshift of matter-antimatter annihilation events.

  10. Completing the Exoplanet Census with the WFIRST Microlensing Survey

    NASA Astrophysics Data System (ADS)

    Bennett, David P.; WFIRST Science Definition Team

    2011-09-01

    The WFIRST mission is the top rated large space mission from last year's decadal survey. It has three major science programs, a microlensing planet search program, a dark energy program, and a general observer program. WFIRST's microlensing planet search program will provide a statistical census of exoplanets with masses greater than one tenth of an Earth mass and orbital separations ranging from 0.5AU to infinity. This includes analogs to all the Solar System’s planets except for Mercury, as well as most types of planets predicted by planet formation theories. In combination with Kepler's census of planets in shorter period orbits, WFIRST's planet search program will provide a complete statistical census of the planets that populate our Galaxy. The current status of the WFIRST mission design will be presented.

  11. The Microlensing Planet Search Program of the WFIRST Mission

    NASA Astrophysics Data System (ADS)

    Bennett, David P.

    2011-01-01

    The recently Decadal Survey report, "New Worlds, New Horizons in Astronomy and Astrophysics" recommends a new mission called WFIRST as its top ranked large space mission for the next decade. The WFIRST mission is to have two major science programs that will drive the design requirements: a dark energy program and a microlensing planet search program. WFIRST's microlensing planet search program will provide a statistical census of exoplanets with masses greater than one tenth of an Earth mass and orbital separations ranging from 0.5AU to infinity. This includes analogs to all the Solar System's planets except for Mercury, as well as most types of planets predicted by planet formation theories. In combination with Kepler's census of planets in shorter period orbits, WFIRST's planet search program will provide a complete statistical census of the planets that populate our Galaxy.

  12. The Microlensing Planet Search Program of the WFIRST Mission

    NASA Astrophysics Data System (ADS)

    Bennett, David P.

    2010-10-01

    The recently Decadal Survey report, "New Worlds, New Horizons in Astronomy and Astrophysics" recommends a new mission called WFIRST as its top ranked large space mission for the next decade. The WFIRST mission is to have two major science programs that will drive the design requirements: a dark energy program and a microlensing planet search program. WFIRST's microlensing planet search program will provide a statistical census of exoplanets with masses greater than one tenth of an Earth mass and orbital separations ranging from 0.5AU to infinity. This includes analogs to all the Solar System's planets except for Mercury, as well as most types of planets predicted by planet formation theories. In combination with Kepler's census of planets in shorter period orbits, WFIRST's planet search program will provide a complete statistical census of the planets that populate our Galaxy.

  13. Broadband Plasmonic Microlenses based on Patches of Nanoholes

    PubMed Central

    Gao, Hanwei; Hyun, Jerome K.; Lee, Min Hyung; Yang, Jiun-Chan; Lauhon, Lincoln J.; Odom, Teri W.

    2010-01-01

    This paper reports a new type of diffractive microlens based on finite-areas of 2D arrays of circular nanoholes (patches). The plasmonic microlenses can focus single wavelengths of light across the entire visible spectrum as well as broadband white light with little divergence. The focal length is determined primarily by the overall size of the patch and is tolerant to significant changes in patch substructure, including lattice geometry and local order of the circular nanoholes. The optical throughput, however, depends sensitively on the patch substructure and is determined by the wavelengths of surface plasmon resonances. This simple diffractive lens design enables millions of broadband plasmonic microlenses to be fabricated in parallel using soft nanolithographic techniques. PMID:20839781

  14. A method for the microlensed flux variance of QSOs

    NASA Astrophysics Data System (ADS)

    Goodman, Jeremy; Sun, Ai-Lei

    2014-06-01

    A fast and practical method is described for calculating the microlensed flux variance of an arbitrary source by uncorrelated stars. The required inputs are the mean convergence and shear due to the smoothed potential of the lensing galaxy, the stellar mass function, and the absolute square of the Fourier transform of the surface brightness in the source plane. The mathematical approach follows previous authors but has been generalized, streamlined, and implemented in publicly available code. Examples of its application are given for Dexter and Agol's inhomogeneous-disc models as well as the usual Gaussian sources. Since the quantity calculated is a second moment of the magnification, it is only logarithmically sensitive to the sizes of very compact sources. However, for the inferred sizes of actual quasi-stellar objects (QSOs), it has some discriminatory power and may lend itself to simple statistical tests. At the very least, it should be useful for testing the convergence of microlensing simulations.

  15. Extended X-Ray Monitoring of Gravitational Lenses with Chandra and Joint Constraints on X-Ray Emission Regions

    NASA Astrophysics Data System (ADS)

    Guerras, Eduardo; Dai, Xinyu; Steele, Shaun; Liu, Ang; Kochanek, Christopher S.; Chartas, George; Morgan, Christopher W.; Chen, Bin

    2017-02-01

    We present an X-ray photometric analysis of six gravitationally lensed quasars, with observation campaigns spanning from 5 to 14 years, measuring the total (0.83–21.8 keV restframe), soft- (0.83–3.6 keV), and hard- (3.6–21.8 keV) band image flux ratios for each epoch. Using the ratios of the model-predicted macro-magnifications as baselines, we build differential microlensing light curves and obtain joint likelihood functions for the average X-ray emission region sizes. Our analysis yields a probability distribution function for the average half-light radius of the X-ray emission region in the sample that peaks slightly above 1 gravitational radius and with nearly indistinguishable 68 % confidence (one-sided) upper limits of 17.8 and 18.9 gravitational radii for the soft and hard X-ray emitting regions, assuming a mean stellar mass of 0.3 M ⊙. We see hints of energy dependent microlensing between the soft and hard bands in two of the objects. In a separate analysis on the root-mean-square (rms) of the microlensing variability, we find significant differences between the soft and hard bands, but the sign of the difference is not consistent across the sample. This suggests the existence of some kind of spatial structure to the X-ray emission in an otherwise extremely compact source. We also discover a correlation between the rms microlensing variability and the average microlensing amplitude.

  16. Methodological Gravitism

    ERIC Educational Resources Information Center

    Zaman, Muhammad

    2011-01-01

    In this paper the author presents the case of the exchange marriage system to delineate a model of methodological gravitism. Such a model is not a deviation from or alteration to the existing qualitative research approaches. I have adopted culturally specific methodology to investigate spouse selection in line with the Grounded Theory Method. This…

  17. Campaign 9 of the K2 Mission: Observational Parameters, Scientific Drivers, and Community Involvement for a Simultaneous Space- and Ground-based Microlensing Survey

    NASA Astrophysics Data System (ADS)

    Henderson, Calen B.; Poleski, Radosław; Penny, Matthew; Street, Rachel A.; Bennett, David P.; Hogg, David W.; Gaudi, B. Scott; K2 Campaign 9 Microlensing Science Team; Zhu, W.; Barclay, T.; Barentsen, G.; Howell, S. B.; Mullally, F.; Udalski, A.; Szymański, M. K.; Skowron, J.; Mróz, P.; Kozłowski, S.; Wyrzykowski, Ł.; Pietrukowicz, P.; Soszyński, I.; Ulaczyk, K.; Pawlak, M.; OGLE Project, The; Sumi, T.; Abe, F.; Asakura, Y.; Barry, R. K.; Bhattacharya, A.; Bond, I. A.; Donachie, M.; Freeman, M.; Fukui, A.; Hirao, Y.; Itow, Y.; Koshimoto, N.; Li, M. C. A.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Nagakane, M.; Ohnishi, K.; Oyokawa, H.; Rattenbury, N.; Saito, To.; Sharan, A.; Sullivan, D. J.; Tristram, P. J.; Yonehara, A.; MOA Collaboration; Bachelet, E.; Bramich, D. M.; Cassan, A.; Dominik, M.; Figuera Jaimes, R.; Horne, K.; Hundertmark, M.; Mao, S.; Ranc, C.; Schmidt, R.; Snodgrass, C.; Steele, I. A.; Tsapras, Y.; Wambsganss, J.; RoboNet Project, The; Bozza, V.; Burgdorf, M. J.; Jørgensen, U. G.; Calchi Novati, S.; Ciceri, S.; D'Ago, G.; Evans, D. F.; Hessman, F. V.; Hinse, T. C.; Husser, T.-O.; Mancini, L.; Popovas, A.; Rabus, M.; Rahvar, S.; Scarpetta, G.; Skottfelt, J.; Southworth, J.; Unda-Sanzana, E.; The MiNDSTEp Team; Bryson, S. T.; Caldwell, D. A.; Haas, M. R.; Larson, K.; McCalmont, K.; Packard, M.; Peterson, C.; Putnam, D.; Reedy, L.; Ross, S.; Van Cleve, J. E.; K2C9 Engineering Team; Akeson, R.; Batista, V.; Beaulieu, J.-P.; Beichman, C. A.; Bryden, G.; Ciardi, D.; Cole, A.; Coutures, C.; Foreman-Mackey, D.; Fouqué, P.; Friedmann, M.; Gelino, C.; Kaspi, S.; Kerins, E.; Korhonen, H.; Lang, D.; Lee, C.-H.; Lineweaver, C. H.; Maoz, D.; Marquette, J.-B.; Mogavero, F.; Morales, J. C.; Nataf, D.; Pogge, R. W.; Santerne, A.; Shvartzvald, Y.; Suzuki, D.; Tamura, M.; Tisserand, P.; Wang, D.

    2016-12-01

    K2's Campaign 9 (K2C9) will conduct a ˜3.7 deg2 survey toward the Galactic bulge from 2016 April 22 through July 2 that will leverage the spatial separation between K2 and the Earth to facilitate measurement of the microlens parallax {π }{{E}} for ≳ 170 microlensing events. These will include several that are planetary in nature as well as many short-timescale microlensing events, which are potentially indicative of free-floating planets (FFPs). These satellite parallax measurements will in turn allow for the direct measurement of the masses of and distances to the lensing systems. In this article we provide an overview of the K2C9 space- and ground-based microlensing survey. Specifically, we detail the demographic questions that can be addressed by this program, including the frequency of FFPs and the Galactic distribution of exoplanets, the observational parameters of K2C9, and the array of resources dedicated to concurrent observations. Finally, we outline the avenues through which the larger community can become involved, and generally encourage participation in K2C9, which constitutes an important pathfinding mission and community exercise in anticipation of WFIRST.

  18. Campaign 9 of the K2 Mission: Observational Parameters, Scientific Drivers, and Community Involvement for a Simultaneous Space- and Ground-based Microlensing Survey

    NASA Technical Reports Server (NTRS)

    Henderson, Calen B.; Poleski, Radoslaw; Penny, Matthew; Street, Rachel A.; Bennett, David P.; Hogg, David W.; Gaudi, B. Scott; Zhu, W.; Barclay, T.; Barentsen, G.; Howell, S. B.; Mullally, F.; Barry, R. K.; Bryson, S. T.; Caldwell, D. A.; Haas, M. R.; Beichman, C. A.; Bryden, G.; Van Cleve, J. E.

    2016-01-01

    K2's Campaign 9 (K2C9) will conduct a approximately 3.7 sq. deg survey toward the Galactic bulge from 2016 April 22 through July 2 that will leverage the spatial separation between K2 and the Earth to facilitate measurement of the microlens parallax Pi(sub E) for approximately greater than 170 microlensing events. These will include several that are planetary in nature as well as many short-timescale microlensing events, which are potentially indicative of free-floating planets (FFPs). These satellite parallax measurements will in turn allow for the direct measurement of the masses of and distances to the lensing systems. In this article we provide an overview of the K2C9 space- and ground-based microlensing survey. Specifically, we detail the demographic questions that can be addressed by this program, including the frequency of FFPs and the Galactic distribution of exoplanets, the observational parameters of K2C9, and the array of resources dedicated to concurrent observations. Finally, we outline the avenues through which the larger community can become involved, and generally encourage participation in K2C9, which constitutes an important pathfinding mission and community exercise in anticipation of WFIRST.

  19. OGLE-2015-BLG-0051/KMT-2015-BLG-0048Lb: A Giant Planet Orbiting a Low-mass Bulge Star Discovered by High-cadence Microlensing Surveys

    NASA Astrophysics Data System (ADS)

    Han, C.; Udalski, A.; Gould, A.; Bozza, V.; Jung, Y. K.; Albrow, M. D.; Kim, S.-L.; Lee, C.-U.; Cha, S.-M.; Kim, D.-J.; Lee, Y.; Park, B.-G.; Shin, I.-G.; KMTNet Collaboration; Szymański, M. K.; Soszyński, I.; Skowron, J.; Mróz, P.; Poleski, R.; Pietrukowicz, P.; Kozłowski, S.; Ulaczyk, K.; Wyrzykowski, Ł.; Pawlak, M.; OGLE Collaboration

    2016-10-01

    We report the discovery of an extrasolar planet detected from the combined data of a microlensing event OGLE-2015-BLG-0051/KMT-2015-BLG-0048 acquired by two microlensing surveys. Despite the fact that the short planetary signal occurred in the very early Bulge season during which the lensing event could be seen for just about an hour, the signal was continuously and densely covered. From the Bayesian analysis using models of the mass function, and matter and velocity distributions, combined with information on the angular Einstein radius, it is found that the host of the planet is located in the Galactic bulge. The planet has a mass {0.72}-0.07+0.65 {M}{{J}} and it is orbiting a low-mass M-dwarf host with a projected separation {d}\\perp =0.73+/- 0.08 {{au}}. The discovery of the planet demonstrates the capability of the current high-cadence microlensing lensing surveys in detecting and characterizing planets.

  20. MOA-2011-BLG-293LB: First microlensing planet possibly in the habitable zone

    SciTech Connect

    Batista, V.; Gould, A.; Yee, J. C.; Gaudi, B. S.; Beaulieu, J.-P.; Bennett, D. P.; Fukui, A.; Sumi, T.; Udalski, A. E-mail: gould@astronomy.ohio-state.edu E-mail: beaulieu@iap.fr E-mail: afukui@oao.nao.ac.jp E-mail: udalski@astrouw.edu.pl

    2014-01-01

    We used Keck adaptive optics observations to identify the first planet discovered by microlensing to lie in or near the habitable zone, i.e., at projected separation r = 1.1 ± 0.1 AU from its M{sub L} = 0.86 ± 0.06 M {sub ☉} host, being the highest microlensing mass definitely identified. The planet has a mass m{sub p} = 4.8 ± 0.3 M {sub Jup}, and could in principle have habitable moons. This is also the first planet to be identified as being in the Galactic bulge with good confidence: D{sub L} = 7.72 ± 0.44 kpc. The planet/host masses and distance were previously not known, but only estimated using Bayesian priors based on a Galactic model. These estimates had suggested that the planet might be a super-Jupiter orbiting an M dwarf, a very rare class of planets. We obtained high-resolution JHK images using Keck adaptive optics to detect the lens and so test this hypothesis. We clearly detect light from a G dwarf at the position of the event, and exclude all interpretations other than that this is the lens with high confidence (95%), using a new astrometric technique. The calibrated magnitude of the planet host star is H{sub L} = 19.16 ± 0.13. We infer the following probabilities for the three possible orbital configurations of the gas giant planet: 53% to be in the habitable zone, 35% to be near the habitable zone, and 12% to be beyond the snow line, depending on the atmospherical conditions and the uncertainties on the semimajor axis.

  1. Adaptive PSF fitting - a highly performing photometric method and light curves of the GLS H1413+117: time delays and micro-lensing effects

    NASA Astrophysics Data System (ADS)

    Akhunov, T. A.; Wertz, O.; Elyiv, A.; Gaisin, R.; Artamonov, B. P.; Dudinov, V. N.; Nuritdinov, S. N.; Delvaux, C.; Sergeyev, A. V.; Gusev, A. S.; Bruevich, V. V.; Burkhonov, O.; Zheleznyak, A. P.; Ezhkova, O.; Surdej, J.

    2017-03-01

    We present new photometric observations of H1413+117 acquired during seasons between 2001 and 2008 in order to estimate the time delays between the lensed quasar images and to characterize at best the on-going micro-lensing events. We propose a highly performing photometric method called the adaptive point spread function fitting and have successfully tested this method on a large number of simulated frames. This has enabled us to estimate the photometric error bars affecting our observational results. We analysed the V- and R-band light curves and V-R colour variations of the A-D components which show short- and long-term brightness variations correlated with colour variations. Using the χ2 and dispersion methods, we estimated the time delays on the basis of the R-band light curves over the seasons between 2003 and 2006. We have derived the new values: ΔtAB = -17.4 ± 2.1, ΔtAC = -18.9 ± 2.8 and ΔtAD = 28.8 ± 0.7 d using the χ2 method (B and C are leading, D is trailing) with 1σ confidence intervals. We also used available observational constraints (resp. the lensed image positions, the flux ratios in mid-IR and two sets of time delays derived in the present work) to update the lens redshift estimation. We obtained z_l = 1.95^{+0.06}_{-0.10} which is in good agreement with previous estimations. We propose to characterize two kinds of micro-lensing events: micro-lensing for the A, B, C components corresponds to typical variations of ∼10-4 mag d-1 during all the seasons, while the D component shows an unusually strong micro-lensing effect with variations of up to ∼10-3 mag d-1 during 2004 and 2005.

  2. Electromagnetic Counterparts of Gravitational Wave Transients

    NASA Astrophysics Data System (ADS)

    Branchesi, Marica

    2015-03-01

    In the near future the ground-based gravitational wave detectors will reach sensitivities that should make it possible for the first time to directly observe gravitational waves. The simultaneous availability of gravitational wave detectors observing together with space and ground-based electromagnetic telescopes will offer a great opportunity to explore the Universe in a new multi-messenger perspective. Promising sources of gravitational waves are the most energetic astrophysical events such as the merger of neutron stars and/or stellar-mass black holes and the core collapse of massive stars. These events are believed to produce electromagnetic transients in the sky, like gamma-ray bursts and supernovae. An overview of the expected electromagnetic counterparts of the gravitational wave sources is presented, focusing on the challenges, opportunities and strategies for starting transient gravitational wave astronomy.

  3. Gravitational Lensing

    SciTech Connect

    Lincoln, Don

    2015-06-24

    In a long line of intellectual triumphs, Einstein’s theory of general relativity was his greatest and most imaginative. It tells us that what we experience as gravity can be most accurately described as the bending of space itself. This idea leads to consequences, including gravitational lensing, which is caused by light traveling in this curved space. This is works in a way analogous to a lens (and hence the name). In this video, Fermilab’s Dr. Don Lincoln explains a little general relativity, a little gravitational lensing, and tells us how this phenomenon allows us to map out the matter of the entire universe, including the otherwise-invisible dark matter.

  4. Gravitational Lensing

    ScienceCinema

    Lincoln, Don

    2016-07-12

    In a long line of intellectual triumphs, Einstein’s theory of general relativity was his greatest and most imaginative. It tells us that what we experience as gravity can be most accurately described as the bending of space itself. This idea leads to consequences, including gravitational lensing, which is caused by light traveling in this curved space. This is works in a way analogous to a lens (and hence the name). In this video, Fermilab’s Dr. Don Lincoln explains a little general relativity, a little gravitational lensing, and tells us how this phenomenon allows us to map out the matter of the entire universe, including the otherwise-invisible dark matter.

  5. Experimental gravitation

    NASA Astrophysics Data System (ADS)

    Lämmerzahl, Claus; di Virgilio, Angela

    2016-06-01

    100 years after the invention of General Relativity (GR) and 110 years after the development of Special Relativity (SR) we have to state that until now no single experiment or observation allows any doubt about the validity of these theories within the accuracy of the available data. Tests of GR can be divided into three categories: (i) test of the foundations of GR, (ii) tests of the consequences of GR, and (iii) test of the interplay between GR and quantum mechanics. In the first category, we have tests of the Einstein Equivalence Principle and the structure of the Newton axioms, in the second category we have effects like the gravitational redshift, light defection, gravitational time delay, the perihelion shift, the gravitomagnetic effects as the Lense-Thirring and Schiff effect, and gravitational waves. Tests of the effects of gravity on quantum systems are a first step towards experiments searching for a quantum gravity theory. In this paper, we also highlight practical applications in positioning, geodesy, and the International Atomic Time. After 100 years, GR can now definitely be regarded also as practical and applied science.

  6. Gravitational vacuum condensate stars

    PubMed Central

    Mazur, Pawel O.; Mottola, Emil

    2004-01-01

    A new final state of gravitational collapse is proposed. By extending the concept of Bose–Einstein condensation to gravitational systems, a cold, dark, compact object with an interior de Sitter condensate pv = -ρv and an exterior Schwarzschild geometry of arbitrary total mass M is constructed. These regions are separated by a shell with a small but finite proper thickness ℓ of fluid with equation of state p = +ρ, replacing both the Schwarzschild and de Sitter classical horizons. The new solution has no singularities, no event horizons, and a global time. Its entropy is maximized under small fluctuations and is given by the standard hydrodynamic entropy of the thin shell, which is of the order kBℓMc/, instead of the Bekenstein–Hawking entropy formula, SBH = 4πkBGM2/c. Hence, unlike black holes, the new solution is thermodynamically stable and has no information paradox. PMID:15210982

  7. The MACHO Project HST Follow-Up: The Large Magellanic Cloud Microlensing Source Stars

    SciTech Connect

    Nelson, C.A.; Drake, A.J.; Cook, K.H.; Bennett, D.P.; Popowski, P.; Dalal, N.; Nikolaev, S.; Alcock, C.; Axelrod, T.S.; Becker, A.C. Freeman, K.C.; Geha, M.; Griest, K.; Keller, S.C.; Lehner, M.J.; Marshall, S.L.; Minniti, D.; Pratt, M.R.; Quinn, P.J.; Stubbs, C.W.; Sutherland, W.; /Oxford U. /Oran, Sci. Tech. U. /Garching, Max Planck Inst. /McMaster U.

    2009-06-25

    We present Hubble Space Telescope (HST) WFPC2 photometry of 13 microlensed source stars from the 5.7 year Large Magellanic Cloud (LMC) survey conducted by the MACHO Project. The microlensing source stars are identified by deriving accurate centroids in the ground-based MACHO images using difference image analysis (DIA) and then transforming the DIA coordinates to the HST frame. None of these sources is coincident with a background galaxy, which rules out the possibility that the MACHO LMC microlensing sample is contaminated with misidentified supernovae or AGN in galaxies behind the LMC. This supports the conclusion that the MACHO LMC microlensing sample has only a small amount of contamination due to non-microlensing forms of variability. We compare the WFPC2 source star magnitudes with the lensed flux predictions derived from microlensing fits to the light curve data. In most cases the source star brightness is accurately predicted. Finally, we develop a statistic which constrains the location of the Large Magellanic Cloud (LMC) microlensing source stars with respect to the distributions of stars and dust in the LMC and compare this to the predictions of various models of LMC microlensing. This test excludes at {approx}> 90% confidence level models where more than 80% of the source stars lie behind the LMC. Exotic models that attempt to explain the excess LMC microlensing optical depth seen by MACHO with a population of background sources are disfavored or excluded by this test. Models in which most of the lenses reside in a halo or spheroid distribution associated with either the Milky Way or the LMC are consistent which these data, but LMC halo or spheroid models are favored by the combined MACHO and EROS microlensing results.

  8. Testing Gravitational Physics with Space-based Gravitational-wave Observations

    NASA Technical Reports Server (NTRS)

    Baker, John G.

    2011-01-01

    Gravitational wave observations provide exceptional and unique opportunities for precision tests of gravitational physics, as predicted by general relativity (GR). Space-based gravitational wave measurements, with high signal-to-noise ratios and large numbers of observed events may provide the best-suited gravitational-wave observations for testing GR with unprecedented precision. These observations will be especially useful in testing the properties of gravitational waves and strong-field aspects of the theory which are less relevant in other observations. We review the proposed GR test based on observations of massive black hole mergers, extreme mass ratio inspirals, and galactic binary systems.

  9. Observational determination of the time delays in gravitational lens system Q2237+0305

    NASA Astrophysics Data System (ADS)

    Vakulik, V.; Schild, R.; Dudinov, V.; Nuritdinov, S.; Tsvetkova, V.; Burkhonov, O.; Akhunov, T.

    2006-03-01

    We present new brightness monitoring observations of the 4 components of gravitationally lensed system Q2237+0305, which show detection of an intrinsic quasar brightness fluctuation at a time of subdued microlensing activity, between June 27 and October 12, 2003. These data were used to determine the time delays between the arrivals of the four images. The measured delays are τ_BA≈-6, τ_CA≈35, and τ_DA≈2 h, so they confirm that the long history of brightness monitoring has produced significant detection of microlensing. However the error bars associated with the delays, of order 2 days, are too large to discriminate between competing macro-imaging models. Moreover, our simulations show that for the amplitude of this intrinsic fluctuation and for photometric errors intrinsic to optical monitoring from our 1.5-m telescope or from the OGLE monitoring, a daily sampled brightness record cannot produce reliable lags for model discrimination. We use our simulations to devise a strategy for future delay determination with optical data. Nevertheless, we regard these first estimates to be significant, since they are the first direct measurements of time delays made for this system from ground-based observations in the visual wavelengths. The detected highly correlated fluctuations of the four quasar images provide an extra confirmation of the gravitational-lens nature of Q2237+0305, and give observational justification to the extensive literature which attributes the quasar's previously observed brightness fluctuations to microlensing.

  10. The Angstrom Project: two new microlensing/nova transients

    NASA Astrophysics Data System (ADS)

    Kerins, Eamonn

    2008-11-01

    We report the discovery of two new optical transients in M31 by the Angstrom Project M31 bulge microlensing survey using the Liverpool Telescope (La Palma). These transients were discovered using difference imaging techniques by the Angstrom Project Alert System (APAS) in a series of Sloan i'-band images of the bulge of M31.

  11. TIME DELAY AND ACCRETION DISK SIZE MEASUREMENTS IN THE LENSED QUASAR SBS 0909+532 FROM MULTIWAVELENGTH MICROLENSING ANALYSIS

    SciTech Connect

    Hainline, Laura J.; Morgan, Christopher W.; MacLeod, Chelsea L.; Landaal, Zachary D.; Kochanek, C. S.; Harris, Hugh C.; Tilleman, Trudy; Goicoechea, L. J.; Shalyapin, V. N.

    2013-09-01

    We present three complete seasons and two half-seasons of Sloan Digital Sky Survey (SDSS) r-band photometry of the gravitationally lensed quasar SBS 0909+532 from the U.S. Naval Observatory, as well as two seasons each of SDSS g-band and r-band monitoring from the Liverpool Robotic Telescope. Using Monte Carlo simulations to simultaneously measure the system's time delay and model the r-band microlensing variability, we confirm and significantly refine the precision of the system's time delay to {Delta}t{sub AB} = 50{sub -4}{sup +2} days, where the stated uncertainties represent the bounds of the formal 1{sigma} confidence interval. There may be a conflict between the time delay measurement and a lens consisting of a single galaxy. While models based on the Hubble Space Telescope astrometry and a relatively compact stellar distribution can reproduce the observed delay, the models have somewhat less dark matter than we would typically expect. We also carry out a joint analysis of the microlensing variability in the r and g bands to constrain the size of the quasar's continuum source at these wavelengths, obtaining log {l_brace}(r{sub s,r}/cm)[cos i/0.5]{sup 1/2}{r_brace} = 15.3 {+-} 0.3 and log {l_brace}(r{sub s,g}/cm)[cos i/0.5]{sup 1/2}{r_brace} = 14.8 {+-} 0.9, respectively. Our current results do not formally constrain the temperature profile of the accretion disk but are consistent with the expectations of standard thin disk theory.

  12. Time Delay and Accretion Disk Size Measurements in the Lensed Quasar SBS 0909+532 from Multiwavelength Microlensing Analysis

    NASA Astrophysics Data System (ADS)

    Hainline, Laura J.; Morgan, Christopher W.; MacLeod, Chelsea L.; Landaal, Zachary D.; Kochanek, C. S.; Harris, Hugh C.; Tilleman, Trudy; Goicoechea, L. J.; Shalyapin, V. N.; Falco, Emilio E.

    2013-09-01

    We present three complete seasons and two half-seasons of Sloan Digital Sky Survey (SDSS) r-band photometry of the gravitationally lensed quasar SBS 0909+532 from the U.S. Naval Observatory, as well as two seasons each of SDSS g-band and r-band monitoring from the Liverpool Robotic Telescope. Using Monte Carlo simulations to simultaneously measure the system's time delay and model the r-band microlensing variability, we confirm and significantly refine the precision of the system's time delay to \\Delta t_{AB} = 50^{+2}_{-4}\\,{days}, where the stated uncertainties represent the bounds of the formal 1σ confidence interval. There may be a conflict between the time delay measurement and a lens consisting of a single galaxy. While models based on the Hubble Space Telescope astrometry and a relatively compact stellar distribution can reproduce the observed delay, the models have somewhat less dark matter than we would typically expect. We also carry out a joint analysis of the microlensing variability in the r and g bands to constrain the size of the quasar's continuum source at these wavelengths, obtaining log {(r s, r /cm)[cos i/0.5]1/2} = 15.3 ± 0.3 and log {(r s, g /cm)[cos i/0.5]1/2} = 14.8 ± 0.9, respectively. Our current results do not formally constrain the temperature profile of the accretion disk but are consistent with the expectations of standard thin disk theory.

  13. The Effect of Micro-lensing in Eclipsing Binary-star Systems

    NASA Astrophysics Data System (ADS)

    Hoffman, Kelsey L.; Rowe, J.; Hansen, B.

    2013-04-01

    Using photometric observations from the Kepler Space Telescope of eclipsing binary star systems where one component is a white dwarf we have investigated the strength of the micro-lensing effect. We have examined the stellar binary KOI-81 from the Kepler mission. KOI-81 is composed of a white dwarf and a A-type main-sequence star in a 24 day circular orbit and have found that micro-lensing is detectable. We use our lightcurve models to measure the strength of the micro-lensing signal and refine the radius of the eclipsing white dwarf.

  14. MOA-2011-BLG-293Lb: A TEST OF PURE SURVEY MICROLENSING PLANET DETECTIONS

    SciTech Connect

    Yee, J. C.; Gould, A.; Skowron, J.; Collaboration: MOA Collaboration; OGLE Collaboration; muFUN Collaboration; and others

    2012-08-20

    Because of the development of large-format, wide-field cameras, microlensing surveys are now able to monitor millions of stars with sufficient cadence to detect planets. These new discoveries will span the full range of significance levels including planetary signals too small to be distinguished from the noise. At present, we do not understand where the threshold is for detecting planets. MOA-2011-BLG-293Lb is the first planet to be published from the new surveys, and it also has substantial follow-up observations. This planet is robustly detected in survey+follow-up data ({Delta}{chi}{sup 2} {approx} 5400). The planet/host mass ratio is q = (5.3 {+-} 0.2) Multiplication-Sign 10{sup -3}. The best-fit projected separation is s = 0.548 {+-} 0.005 Einstein radii. However, due to the s{r_reversible}s{sup -1} degeneracy, projected separations of s{sup -1} are only marginally disfavored at {Delta}{chi}{sup 2} = 3. A Bayesian estimate of the host mass gives M{sub L} = 0.43{sup +0.27}{sub -0.17} M{sub Sun }, with a sharp upper limit of M{sub L} < 1.2 M{sub Sun} from upper limits on the lens flux. Hence, the planet mass is m{sub p} = 2.4{sup +1.5}{sub -0.9} M{sub Jup}, and the physical projected separation is either r {approx_equal} 1.0 AU or r {approx_equal} 3.4 AU. We show that survey data alone predict this solution and are able to characterize the planet, but the {Delta}{chi}{sup 2} is much smaller ({Delta}{chi}{sup 2} {approx} 500) than with the follow-up data. The {Delta}{chi}{sup 2} for the survey data alone is smaller than for any other securely detected planet. This event suggests a means to probe the detection threshold, by analyzing a large sample of events like MOA-2011-BLG-293, which have both follow-up data and high-cadence survey data, to provide a guide for the interpretation of pure survey microlensing data.

  15. The particle production at the event horizon of a black hole as gravitational Fowler-Nordheim emission in uniformly accelerated frame, in the non-relativistic scenario

    NASA Astrophysics Data System (ADS)

    De, Sanchari; Ghosh, Sutapa; Chakrabarty, Somenath

    2015-11-01

    In the conventional scenario, the Hawking radiation is believed to be a tunneling process at the event horizon of the black hole. In the quantum field theoretic approach the Schwinger's mechanism is generally used to give an explanation of this tunneling process. It is the decay of quantum vacuum into particle anti-particle pairs near the black hole surface. However, in a reference frame undergoing a uniform accelerated motion in an otherwise flat Minkowski space-time geometry, in the non-relativistic approximation, the particle production near the event horizon of a black hole may be treated as a kind of Fowler-Nordheim field emission, which is the typical electron emission process from a metal surface under the action of an external electrostatic field. This type of emission from metal surface is allowed even at extremely low temperature. It has been noticed that in one-dimensional scenario, the Schrödinger equation satisfied by the created particle (anti-particle) near the event horizon, can be reduced to a differential form which is exactly identical with that obeyed by an electron immediately after the emission from the metal surface under the action of a strong electrostatic field. The mechanism of particle production near the event horizon of a black hole is therefore identified with Schwinger process in relativistic quantum field theory, whereas in the non-relativistic scenario it may be interpreted as Fowler-Nordheim emission process, when observed from a uniformly accelerated frame.

  16. On the Feasibility of Characterizing Free-floating Planets with Current and Future Space-based Microlensing Surveys

    NASA Astrophysics Data System (ADS)

    Henderson, Calen B.; Shvartzvald, Yossi

    2016-10-01

    Simultaneous space- and ground-based microlensing surveys, such as K2's Campaign 9 (K2C9) and WFIRST, facilitate measuring the masses and distances of free-floating planet (FFP) candidates, which are identified as single-lens events with timescales that are of the order of 1 day. Measuring the mass and distance of an FFP lens requires determining the size of the source star ρ, measuring the microlens parallax {π }{{E}}, and using high-resolution imaging to search for the lens flux {F}{\\ell } from a possible host star. Here we investigate the accessible parameter space for each of these components considering different satellites for a range of FFP masses, Galactic distances, and source star properties. We find that at the beginning of K2C9, when its projected separation {D}\\perp from the Earth is ≲0.2 au, it will be able to measure {π }{{E}} for Jupiter-mass FFP candidates at distances larger than ∼2 kpc and to Earth-mass lenses at ∼8 kpc. At the end of K2C9, when {D}\\perp = 0.81 au, it is sensitive to planetary-mass lenses for distances ≳3.5 kpc, and even then only to those with mass ≳M Jup. From lens flux constraints we find that it will be possible to exclude hosts down to the deuterium-burning limit for events within ∼2 kpc. This indicates that the ability to characterize FFPs detected during K2C9 is optimized for events occurring toward the beginning of the campaign. WFIRST, on the other hand, will be able to detect and characterize FFP masses down to or below super-Earths throughout the Galaxy during its entire microlensing survey.

  17. Short gamma-ray burst formation rate from BATSE data using E{sub p} -L{sub p} correlation and the minimum gravitational-wave event rate of a coalescing compact binary

    SciTech Connect

    Yonetoku, Daisuke; Sawano, Tatsuya; Toyanago, Asuka; Nakamura, Takashi; Takahashi, Keitaro E-mail: takashi@tap.scphys.kyoto-u.ac.jp

    2014-07-01

    Using 72 short gamma-ray bursts (SGRBs) with well determined spectral data observed by BATSE, we determine their redshift and luminosity by applying the E{sub p} -L{sub p} correlation for SGRBs found by Tsutsui et al. For 53 SGRBs with an observed flux brighter than 4 × 10{sup –6} erg cm{sup –2} s{sup –1}, the cumulative redshift distribution up to z = 1 agrees well with that of 22 Swift SGRBs. This suggests that the redshift determination by the E{sub p} -L{sub p} correlation for SGRBs works well. The minimum event rate at z = 0 is estimated as R{sub on−axis}{sup min}=6.3{sub −3.9}{sup +3.1}× 10{sup −10} events Mpc{sup −3} yr{sup −1}, so that the minimum beaming angle is 0.°6-7.°8 assuming a merging rate of 10{sup –7}- 4 × 10{sup –6} events Mpc{sup –3} yr{sup –1} suggested from the binary pulsar data. Interestingly, this angle is consistent with that for SGRB 130603B of ∼4°-8°. On the other hand, if we assume a beaming angle of ∼6° suggested from four SGRBs with the observed beaming angle value, then the minimum event rate including off-axis SGRBs is estimated as R{sub all}{sup min}=1.15{sub −0.66}{sup +0.56} × 10{sup −7} events Mpc{sup −3} yr{sup −1}. If SGRBs are induced by the coalescence of binary neutron stars (NSs) and/or black holes (BHs), then this event rate leads to a minimum gravitational-wave detection rate of 3.8{sub −2.2}{sup +1.8} (146{sub −83}{sup +71}) events yr{sup −1} for an NS-NS (NS-BH) binary, respectively, by a worldwide network with KAGRA, advanced-LIGO, advanced-VIRGO, and GEO.

  18. Gravitational waves and multimessenger astronomy

    NASA Astrophysics Data System (ADS)

    Ricci, Fulvio

    2016-07-01

    It is widely expected that in the coming quinquennium the first gravitational wave signal will be directly detected. The ground-based advanced LIGO and Virgo detectors are being upgraded to a sensitivity level such that we expect to be measure a significant binary merger rate. Gravitational waves events are likely to be accompanied by electromagnetic counterparts and neutrino emission carrying complementary information to those associated to the gravitational signals. If it becomes possible to measure all these forms of radiation in concert, we will end up an impressive increase in the comprehension of the whole phenomenon. In the following we summarize the scientific outcome of the interferometric detectors in the past configuration. Then we focus on some of the potentialities of the advanced detectors once used in the new context of the multimessenger astronomy.

  19. X-Ray Counterpart of Gravitational Waves Due to Binary Neutron Star Mergers: Light Curves, Luminosity Function, and Event Rate Density

    NASA Astrophysics Data System (ADS)

    Sun, Hui; Zhang, Bing; Gao, He

    2017-01-01

    Zhang proposed a type of GRB-less X-ray transient associated with double neutron star (NS–NS) mergers under the conjecture of a rapidly spinning magnetar merger product with the line of sight off the short gamma-ray burst (GRB) jet. We investigate possible light curves of these transients by considering different observers’ viewing angles. We perform Monte Carlo simulations to calculate the peak luminosity function (LF) and event rate density of these X-ray transients. By considering that a fraction of massive neutron stars may be supra-massive and later collapse into black holes after spinning down, we investigate how the predicted LF depends on the equation of state (EoS) of the central object and the geometry of the system. In general, the LF can be fit by two log-normal distributions peaking around {10}46.4 and {10}49.6 {erg} {{{s}}}-1, corresponding to the trapped and free zones, respectively. For the majority of the EoS models, the current non-detection is consistent with having a free zone solid angle, at most a few times the solid angle of the short GRB jet. The event rate density of these X-ray transients is around a few tens of {{Gpc}}-3 {{yr}}-1 for luminosity above 1045 {erg} {{{s}}}-1. We predict that future X-ray telescopes (such as Einstein Probe) with sensitivity ∼ {10}-11 {erg} {{{s}}}-1 {{cm}}-2 would detect as many as several tens of such transients per year per steradian. Within 200 Mpc, the aLIGO average range for NS–NS mergers, the estimated event rate of these transients is about 1 transient per year all sky.

  20. Liquid microlenses and waveguides from bulk nematic birefringent profiles.

    PubMed

    Čančula, Miha; Ravnik, Miha; Muševič, Igor; Žumer, Slobodan

    2016-09-19

    We demonstrate polarization-selective microlensing and waveguiding of laser beams by birefringent profiles in bulk nematic fluids using numerical modelling. Specifically, we show that radial escaped nematic director profiles with negative birefringence focus and guide light with radial polarization, whereas the opposite - azimuthal - polarization passes through unaffected. A converging lens is realized in a nematic with negative birefringence, and a diverging lens in a positive birefringence material. Tuning of such single-liquid lenses by an external low-frequency electric field and by adjusting the profile and intensity of the beam itself is demonstrated, combining external control with intrinsic self-adaptive focusing. Escaped radial profiles of birefringence are shown to act as single-liquid waveguides with a single distinct eigenmode and low attenuation. Finally, this work is an approach towards creating liquid photonic elements for all-soft matter photonics.

  1. Chromatic aberration control for tunable all-silicone membrane microlenses.

    PubMed

    Waibel, Philipp; Mader, Daniel; Liebetraut, Peter; Zappe, Hans; Seifert, Andreas

    2011-09-12

    Tunable multi-chamber microfluidic membrane microlenses with achromaticity over a given focal length range are demonstrated. In analogy to a fixed-focus achromatic doublet lens, the multi-lens system is based on a stack of microfluidic cavities filled with optically optimized liquids with precisely defined refractive index and Abbe number, and these are independently pneumatically actuated. The membranes separating the cavities form the refractive optical surfaces, and the curvatures as a function of pressure are calculated using a mechanical model for deformation of flexible plates. The results are combined with optical ray tracing simulations of the multi-lens system to yield chromatic aberration behavior, which is verified experimentally. A focal length tuning range of 5-40 mm and reduction in chromatic aberration of over 30% is demonstrated, limited by the availability of optical fluids.

  2. Adaptive liquid microlenses activated by stimuli-responsive hydrogels

    NASA Astrophysics Data System (ADS)

    Dong, Liang; Agarwal, Abhishek K.; Beebe, David J.; Jiang, Hongrui

    2006-08-01

    Despite its compactness, the human eye can easily focus on different distances by adjusting the shape of its lens with the help of ciliary muscles. In contrast, traditional man-made optical systems achieve focusing by physical displacement of the lenses used. But in recent years, advances in miniaturization technology have led to optical systems that no longer require complicated mechanical systems to tune and adjust optical performance. These systems have found wide use in photonics, displays and biomedical systems. They are either based on arrays of microlenses with fixed focal lengths, or use external control to adjust the microlens focal length. An intriguing example is the tunable liquid lens, where electrowetting or external pressure manipulates the shape of a liquid droplet and thereby adjusts its optical properties. Here we demonstrate a liquid lens system that allows for autonomous focusing. The central component is a stimuli-responsive hydrogel integrated into a microfluidic system and serving as the container for a liquid droplet, with the hydrogel simultaneously sensing the presence of stimuli and actuating adjustments to the shape-and hence focal length-of the droplet. By working at the micrometre scale where ionic diffusion and surface tension scale favourably, we can use pinned liquid-liquid interfaces to obtain stable devices and realize response times of ten to a few tens of seconds. The microlenses, which can have a focal length ranging from -∞ to +∞ (divergent and convergent), are also readily integrated into arrays that may find use in applications such as sensing, medical diagnostics and lab-on-a-chip technologies.

  3. EDITORIAL: Focus on Gravitational Lensing

    NASA Astrophysics Data System (ADS)

    Jain, Bhuvnesh

    2007-11-01

    Gravitational lensing emerged as an observational field following the 1979 discovery of a doubly imaged quasar lensed by a foreground galaxy. In the 1980s and '90s dozens of other multiply imaged systems were observed, as well as time delay measurements, weak and strong lensing by galaxies and galaxy clusters, and the discovery of microlensing in our galaxy. The rapid pace of advances has continued into the new century. Lensing is currently one of best techniques for finding and mapping dark matter over a wide range of scales, and also addresses broader cosmological questions such as understanding the nature of dark energy. This focus issue of New Journal of Physics presents a snapshot of current research in some of the exciting areas of lensing. It provides an occasion to look back at the advances of the last decade and ahead to the potential of the coming years. Just about a decade ago, microlensing was discovered through the magnification of stars in our galaxy by invisible objects with masses between that of Jupiter and a tenth the mass of the Sun. Thus a new component of the mass of our galaxy, dubbed MACHOs, was established (though a diffuse, cold dark matter-like component is still needed to make up most of the galaxy mass). More recently, microlensing led to another exciting discovery—of extra-solar planets with masses ranging from about five times that of Earth to that of Neptune. We can expect many more planets to be discovered through ongoing surveys. Microlensing is the best technique for finding Earth mass planets, though it is not as productive overall as other methods and does not allow for follow up observations. Beyond planet hunting, microlensing has enabled us to observe previously inaccessible systems, ranging from the surfaces of other stars to the accretion disks around the black holes powering distant quasars. Galaxies and galaxy clusters at cosmological distances can produce dramatic lensing effects: multiple images of background galaxies

  4. Microlensing discovery of a tight, low-mass-ratio planetary-mass object around an old field brown dwarf

    SciTech Connect

    Han, C.; Jung, Y. K.; Udalski, A.; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Skowron, J.; Kozłowski, S.; Poleski, R.; Ulaczyk, K.; Wyrzykowski, Ł.; Pietrukowicz, P.; Sumi, T.; Gaudi, B. S.; Gould, A.; Bennett, D. P.; Tsapras, Y.; Abe, F.; Bond, I. A.; Collaboration: OGLE Collaboration; MOA Collaboration; μFUN Collaboration; RoboNet Collaboration; and others

    2013-11-20

    Observations of accretion disks around young brown dwarfs (BDs) have led to the speculation that they may form planetary systems similar to normal stars. While there have been several detections of planetary-mass objects around BDs (2MASS 1207-3932 and 2MASS 0441-2301), these companions have relatively large mass ratios and projected separations, suggesting that they formed in a manner analogous to stellar binaries. We present the discovery of a planetary-mass object orbiting a field BD via gravitational microlensing, OGLE-2012-BLG-0358Lb. The system is a low secondary/primary mass ratio (0.080 ± 0.001), relatively tightly separated (∼0.87 AU) binary composed of a planetary-mass object with 1.9 ± 0.2 Jupiter masses orbiting a BD with a mass 0.022 M {sub ☉}. The relatively small mass ratio and separation suggest that the companion may have formed in a protoplanetary disk around the BD host in a manner analogous to planets.

  5. Opto-mechanical analysis of nonlinear elastomer membrane deformation under hydraulic pressure for variable-focus liquid-filled microlenses.

    PubMed

    Choi, Seung Tae; Son, Byeong Soo; Seo, Gye Won; Park, Si-Young; Lee, Kyung-Sick

    2014-03-10

    Nonlinear large deformation of a transparent elastomer membrane under hydraulic pressure was analyzed to investigate its optical performance for a variable-focus liquid-filled membrane microlens. In most membrane microlenses, actuators control the hydraulic pressure of optical fluid so that the elastomer membrane together with the internal optical fluid changes its shape, which alters the light path of the microlens to adapt its optical power. A fluid-structure interaction simulation was performed to estimate the transient behavior of the microlens under the operation of electroactive polymer actuators, demonstrating that the viscosity of the optical fluid successfully stabilizes the fluctuations within a fairly short period of time during dynamic operations. Axisymmetric nonlinear plate theory was used to calculate the deformation profile of the membrane under hydrostatic pressure, with which optical characteristics of the membrane microlens were estimated. The effects of gravitation and viscoelastic behavior of the elastomer membrane on the optical performance of the membrane microlens were also evaluated with finite element analysis.

  6. Spitzer Observations of a Gravitationally Lensed Quasar, QSO 2237+0305

    NASA Astrophysics Data System (ADS)

    Agol, Eric; Gogarten, Stephanie M.; Gorjian, Varoujan; Kimball, Amy

    2009-06-01

    The four-image gravitationally lensed quasar QSO 2237+0305 is microlensed by stars in the lens galaxy. The amplitude of microlensing variability can be used to infer the relative size of the quasar as a function of wavelength; this provides a test of quasar models. Toward this end, we present Spitzer Space Telescope Infrared Spectrograph and Infrared Array Camera (IRAC) observations of QSO 2237+0305, finding the following. (1) The infrared (IR) spectral energy distribution (SED) is similar to that of other bright radio-quiet quasars, contrary to an earlier claim. (2) A dusty torus model with a small opening angle fits the overall shape of the IR SED well, but the quantitative agreement is poor due to an offset in wavelength of the silicate feature. (3) The flux ratios of the four lensed images can be derived from the IRAC data despite being unresolved. We find that the near-IR fluxes are increasingly affected by microlensing toward shorter wavelengths. (4) The wavelength dependence of the IRAC flux ratios is consistent with the standard quasar model in which an accretion disk and a dusty torus both contribute near 1 μm in the rest frame. This is also consistent with recent IR spectropolarimetry of nearby quasars.

  7. Microlensing results toward the galactic bulge, theory of fitting blended light curves, and discussion of weak lensing corrections

    NASA Astrophysics Data System (ADS)

    Thomas, Christian L.

    2006-06-01

    Analysis and results (Chapters 2-5) of the full 7 year Macho Project dataset toward the Galactic bulge are presented. A total of 450 high quality, relatively large signal-to-noise ratio, events are found, including several events exhibiting exotic effects, and lensing events on possible Sagittarius dwarf galaxy stars. We examine the problem of blending in our sample and conclude that the subset of red clump giants are minimally blended. Using 42 red clump giant events near the Galactic center we calculate the optical depth toward the Galactic bulge to be t = [Special characters omitted.] × 10 -6 at ( l, b ) = ([Special characters omitted.] ) with a gradient of (1.06 ± 0.71) × 10 -6 deg -1 in latitude, and (0.29±0.43) × 10 -6 deg -1 in longitude, bringing measurements into consistency with the models for the first time. In Chapter 6 we reexamine the usefulness of fitting blended light-curve models to microlensing photometric data. We find agreement with previous workers (e.g. Wozniak & Paczynski) that this is a difficult proposition because of the degeneracy of blend fraction with other fit parameters. We show that follow-up observations at specific points along the light curve (peak region and wings) of high magnification events are the most helpful in removing degeneracies. We also show that very small errors in the baseline magnitude can result in problems in measuring the blend fraction, and study the importance of non- Gaussian errors in the fit results. The biases and skewness in the distribution of the recovered blend fraction is discussed. We also find a new approximation formula relating the blend fraction and the unblended fit parameters to the underlying event duration needed to estimate microlensing optical depth. In Chapter 7 we present work-in-progress on the possibility of correcting standard candle luminosities for the magnification due to weak lensing. We consider the importance of lenses in different mass ranges and look at the contribution

  8. A Search For Stellar-mass Black Holes Via Astrometric Microlensing

    NASA Astrophysics Data System (ADS)

    Lu, J. R.; Sinukoff, E.; Ofek, E. O.; Udalski, A.; Kozlowski, S.

    2016-10-01

    While dozens of stellar-mass black holes (BHs) have been discovered in binary systems, isolated BHs have eluded detection. Their presence can be inferred when they lens light from a background star. We attempt to detect the astrometric lensing signatures of three photometrically identified microlensing events, OGLE-2011-BLG-0022, OGLE-2011-BLG-0125, and OGLE-2012-BLG-0169 (OB110022, OB110125, and OB120169), located toward the Galactic Bulge. These events were selected because of their long durations, which statistically favors more massive lenses. Astrometric measurements were made over one to two years using laser-guided adaptive optics observations from the W. M. Keck Observatory. Lens model parameters were first constrained by the photometric light curves. The OB120169 light curve is well fit by a single-lens model, while both OB110022 and OB110125 light curves favor binary lens models. Using the photometric fits as prior information, no significant astrometric lensing signal was detected and all targets were consistent with linear motion. The significant lack of astrometric signal constrains the lens mass of OB110022 to 0.05-1.79 M ⊙ in a 99.7% confidence interval, which disfavors a BH lens. Fits to OB110125 yielded a reduced Einstein crossing time and insufficient observations during the peak, so no mass limits were obtained. Two degenerate solutions exist for OB120169, which have a lens mass between 0.2-38.8 M ⊙ and 0.4-39.8 M ⊙ for a 99.7% confidence interval. Follow-up observations of OB120169 will further constrain the lens mass. Based on our experience, we use simulations to design optimal astrometric observing strategies and show that with more typical observing conditions the detection of BHs is feasible.

  9. TOPICAL REVIEW Gravitational lensing

    NASA Astrophysics Data System (ADS)

    Bartelmann, Matthias

    2010-12-01

    Gravitational lensing has developed into one of the most powerful tools for the analysis of the dark universe. This review summarizes the theory of gravitational lensing, its main current applications and representative results achieved so far. It has two parts. In the first, starting from the equation of geodesic deviation, the equations of thin and extended gravitational lensing are derived. In the second, gravitational lensing by stars and planets, galaxies, galaxy clusters and large-scale structures is discussed and summarized.

  10. Gravitation in Material Media

    ERIC Educational Resources Information Center

    Ridgely, Charles T.

    2011-01-01

    When two gravitating bodies reside in a material medium, Newton's law of universal gravitation must be modified to account for the presence of the medium. A modified expression of Newton's law is known in the literature, but lacks a clear connection with existing gravitational theory. Newton's law in the presence of a homogeneous material medium…

  11. Gravitational lensing by ring-like structures

    NASA Astrophysics Data System (ADS)

    Lake, Ethan; Zheng, Zheng

    2017-02-01

    We study a class of gravitational lensing systems consisting of an inclined ring/belt, with and without an added point mass at the centre. We show that a common feature of such systems are so-called pseudo-caustics, across which the magnification of a point source changes discontinuously and yet remains finite. Such a magnification change can be associated with either a change in image multiplicity or a sudden change in the size of a lensed image. The existence of pseudo-caustics and the complex interplay between them and the formal caustics (which correspond to points of infinite magnification) can lead to interesting consequences, such as truncated or open caustics and a non-conservation of total image parity. The origin of the pseudo-caustics is found to be the non-differentiability of the solutions to the lens equation across the ring/belt boundaries, with the pseudo-caustics corresponding to ring/belt boundaries mapped into the source plane. We provide a few illustrative examples to understand the pseudo-caustic features, and in a separate paper consider a specific astronomical application of our results to study microlensing by extrasolar asteroid belts.

  12. OGLE-2015-BLG-0479LA,B: Binary Gravitational Microlens Characterized by Simultaneous Ground-based and Space-based Observations

    NASA Astrophysics Data System (ADS)

    Han, C.; Udalski, A.; Gould, A.; Zhu, Wei; Street, R. A.; Yee, J. C.; Beichman, C.; Bryden, C.; Calchi Novati, S.; Carey, S.; Fausnaugh, M.; Gaudi, B. S.; Henderson, Calen B.; Shvartzvald, Y.; Wibking, B.; Spitzer Microlensing Team; Szymański, M. K.; Soszyński, I.; Skowron, J.; Mróz, P.; Poleski, R.; Pietrukowicz, P.; Kozłowski, S.; Ulaczyk, K.; Wyrzykowski, Ł.; Pawlak, M.; OGLE Collaboration; Tsapras, Y.; Hundertmark, M.; Bachelet, E.; Dominik, M.; Bramich, D. M.; Cassan, A.; Figuera Jaimes, R.; Horne, K.; Ranc, C.; Schmidt, R.; Snodgrass, C.; Wambsganss, J.; Steele, I. A.; Menzies, J.; Mao, S.; RoboNet Collaboration; Bozza, V.; Jørgensen, U. G.; Alsubai, K. A.; Ciceri, S.; D'Ago, G.; Haugbølle, T.; Hessman, F. V.; Hinse, T. C.; Juncher, D.; Korhonen, H.; Mancini, L.; Popovas, A.; Rabus, M.; Rahvar, S.; Scarpetta, G.; Skottfelt, J.; Southworth, J.; Starkey, D.; Surdej, J.; Wertz, O.; Zarucki, M.; MiNDSTEp Consortium; Pogge, R. W.; DePoy, D. L.; μFUN Collaboration

    2016-09-01

    We present a combined analysis of the observations of the gravitational microlensing event OGLE-2015-BLG-0479 taken both from the ground and by the Spitzer Space Telescope. The light curves seen from the ground and from space exhibit a time offset of ˜13 days between the caustic spikes, indicating that the relative lens-source positions seen from the two places are displaced by parallax effects. From modeling the light curves, we measure the space-based microlens parallax. Combined with the angular Einstein radius measured by analyzing the caustic crossings, we determine the mass and distance of the lens. We find that the lens is a binary composed of two G-type stars with masses of ˜1.0 M ⊙ and ˜0.9 M ⊙ located at a distance of ˜3 kpc. In addition, we are able to constrain the complete orbital parameters of the lens thanks to the precise measurement of the microlens parallax derived from the joint analysis. In contrast to the binary event OGLE-2014-BLG-1050, which was also observed by Spitzer, we find that the interpretation of OGLE-2015-BLG-0479 does not suffer from the degeneracy between (±, ±) and (±, ∓) solutions, confirming that the four-fold parallax degeneracy in single-lens events collapses into the two-fold degeneracy for the general case of binary-lens events. The location of the blend in the color-magnitude diagram is consistent with the lens properties, suggesting that the blend is the lens itself. The blend is bright enough for spectroscopy and thus this possibility can be checked from future follow-up observations.

  13. The Bright Future of Gravitational Wave Astronomy

    NASA Astrophysics Data System (ADS)

    Gonzalez, Gabriela

    2008-04-01

    These are exciting times in the search for gravitational waves. Gravitational waves are expected from many different astrophysical sources: brief transients from violent events like supernova explosions and collisions of neutron stars and black holes, coalescence of compact binary systems, continuous waves from rotating systems, and stochastic signals from cosmological origin or unresolved transients. The LIGO gravitational wave detectors have achieved unprecedented sensitivity to gravitational waves, and other detectors around the world are expected to reach similar sensitivities. The LIGO Scientific Collaboration (LSC) has recently completed their most sensitive observation run to date with LIGO and GEO detectors, including several months of joint observations with the European VIRGO detector. The LIGO Laboratory and the LSC, as well as the Virgo Collaboration, are actively preparing for operating enhanced detectors in the very near future. The next decade will see the construction and commissioning of Advanced LIGO and VIRGO, and quite possibly the launch of the space-based LISA mission, starting for sure then, if not earlier, a new era for gravitational wave astronomy. Plans for a world-wide network of ground based detectors involving more detectors in Europe, Japan and Australia are becoming more concrete. The future of gravitational wave astronomy is bright indeed! In this talk, will briefly describe the present status of the ground and space based detector projects and discuss the science we may expect to do with the detectors (and detections!) we will have in the upcoming era of gravitational wave astronomy.

  14. The Angstrom Project: M31 microlensing alert ANG-08B-M31-07

    NASA Astrophysics Data System (ADS)

    Darnley, M. J.; Kerins, E.; Newsam, A. M.; Duke, J. P.; Gould, A.; Street, C. Han B.-G. Park R. A.

    2008-12-01

    We report an ongoing microlensing candidate in M31 by the Angstrom Project M31 bulge microlensing survey using the Liverpool Telescope (La Palma). The candidate was detected from difference imaging photometry generated by the Angstrom Project Alert System (APAS) in a series of Sloan i'-band images of the bulge of M31.

  15. Gravitational waves from compact objects

    NASA Astrophysics Data System (ADS)

    de Freitas Pacheco, José Antonio

    2010-11-01

    Large ground-based laser beam interferometers are presently in operation both in the USA (LIGO) and in Europe (VIRGO) and potential sources that might be detected by these instruments are revisited. The present generation of detectors does not have a sensitivity high enough to probe a significant volume of the universe and, consequently, predicted event rates are very low. The planned advanced generation of interferometers will probably be able to detect, for the first time, a gravitational signal. Advanced LIGO and EGO instruments are expected to detect few (some): binary coalescences consisting of either two neutron stars, two black holes or a neutron star and a black hole. In space, the sensitivity of the planned LISA spacecraft constellation will allow the detection of the gravitational signals, even within a “pessimistic" range of possible signals, produced during the capture of compact objects by supermassive black holes, at a rate of a few tens per year.

  16. Extragalactic sources of gravitational waves

    NASA Astrophysics Data System (ADS)

    Rees, M. J.

    The prospects of detecting gravitational waves from galactic nuclei are shown to be bleak: although some 'scenarios', such as those involving black hole coalescence, would emit a pulse with about 0.1 efficiency, the predicted event rate is discouragingly low. If most of the 'unseen' mass in the universe were in the remnants of massive 'Population III' stars, then the overlapping bursts from the collapse of such objects in early epochs would yield a stochastic background that could amount to about 0.001 (or even more) of the critical cosmological density. Such a background may be above the detectability threshold for future experiments, and can be probed by studying the timing noise of pulsars, and the secular behavior of the binary pulsar. General constraints on stochastic backgrounds, including 'primordial' gravitational radiation, are summarized.

  17. Gravitational wave science from space

    NASA Astrophysics Data System (ADS)

    Gair, Jonathan R.

    2016-05-01

    The rich millihertz gravitational wave band can only be accessed with a space- based detector. The technology for such a detector will be demonstrated by the LISA Pathfinder satellite that is due to launch this year and ESA has selected gravitational wave detection from space as the science theme to be addressed by the L3 large mission to be launched around 2034. In this article we will discuss the sources that such an instrument will observe, and how the numbers of events and precision of parameter determination are affected by modifications to the, as yet not finalised, mission design. We will also describe some of the exciting scientific applications of these observations, to astrophysics, fundamental physics and cosmology.

  18. Gravitational waves from inflation

    NASA Astrophysics Data System (ADS)

    Guzzetti, M. C.; Bartolo, N.; Liguori, M.; Matarrese, S.

    2016-09-01

    The production of a stochastic background of gravitational waves is a fundamental prediction of any cosmological inflationary model. The features of such a signal encode unique information about the physics of the Early Universe and beyond, thus representing an exciting, powerful window on the origin and evolution of the Universe. We review the main mechanisms of gravitational-wave production, ranging from quantum fluctuations of the gravitational field to other mechanisms that can take place during or after inflation. These include e.g. gravitational waves generated as a consequence of extra particle production during inflation, or during the (p)reheating phase. Gravitational waves produced in inflation scenarios based on modified gravity theories and second-order gravitational waves are also considered. For each analyzed case, the expected power spectrum is given. We discuss the discriminating power among different models, associated with the validity/violation of the standard consistency relation between tensor-to-scalar ratio r and tensor spectral index nT. In light of the prospects for (directly/indirectly) detecting primordial gravitational waves, we give the expected present-day gravitational radiation spectral energy-density, highlighting the main characteristics imprinted by the cosmic thermal history, and we outline the signatures left by gravitational waves on the Cosmic Microwave Background and some imprints in the Large-Scale Structure of the Universe. Finally, current bounds and prospects of detection for inflationary gravitational waves are summarized.

  19. The Origin of Gravitation

    NASA Astrophysics Data System (ADS)

    Zheng, Sheng Ming

    2012-10-01

    In the natural world, people have discovered four kinds of forces: electromagnetic force, gravitation, weak force, and strong force. Although the gravitation has been discovered more than three hundred years, its mechanism of origin is unclear until today. While investigating the origin of gravitation, I do some experiments discover the moving photons produce gravitation. This discovery shows the origin of gravitation. Meanwhile I do some experiments discover the light interference fringes are produced by the gravitation: my discovery demonstrate light is a particle, but is not a wave-particle duality. Furthermore, applications of this discovery to other moving particles show a similar effect. In a word: the micro particle moving produce gravitation and electromagnetic force. Then I do quantity experiment get a general formula: Reveal the essence of gravitational mass and the essence of electric charge; reveal the origin of gravitation and the essence of matter wave. Along this way, I unify the gravitation and electromagnetic force. Namely I find a natural law that from atomic world to star world play in moving track. See website: https://www.lap-publishing.com/catalog/details/store/gb/book/978-3-8473-2658-8/mechanism-of-interaction-in-moving-matter

  20. Quantum Gravitational Spectroscopy

    SciTech Connect

    Nesvizhevsky, Valery V.; Antoniadis, Ignatios; Baessler, Stefan; Pignol, Guillaume

    2015-01-01

    We report that one of the main goals for improving the accuracy of quantum gravitational spectroscopy with neutrons is searches for extra short-range fundamental forces. We discuss also any progress in all competing nonneutron methods as well as constraints at other characteristic distances. Among major methodical developments related to the phenomenon of gravitational quantum states are the detailed theoretical analysis and the planning experiments on observation of gravitational quantum states of antihydrogen atoms.

  1. Gravitation in material media

    NASA Astrophysics Data System (ADS)

    Ridgely, Charles T.

    2011-03-01

    When two gravitating bodies reside in a material medium, Newton's law of universal gravitation must be modified to account for the presence of the medium. A modified expression of Newton's law is known in the literature, but lacks a clear connection with existing gravitational theory. Newton's law in the presence of a homogeneous material medium is herein derived on the basis of classical, Newtonian gravitational theory and by a general relativistic use of Archimedes' principle. It is envisioned that the techniques presented herein will be most useful to graduate students and those undergraduate students having prior experience with vector analysis and potential theory.

  2. Digital holographic characterization of liquid microlenses array fabricated in electrode-less configuration

    NASA Astrophysics Data System (ADS)

    Miccio, L.; Vespini, V.; Grilli, S.; Paturzo, M.; Finizio, A.; De Nicola, S.; Ferraro, P.

    2009-06-01

    We show how thin liquid film on polar dielectric substrate can form an array of liquid micro-lenses. The effect is driven by the pyroelectric effect leading to a new concept in electro-wetting (EW). EW is a viable method for actuation of liquids in microfluidic systems and requires the design and fabrication of complex electrodes for suitable actuation of liquids. When compared to conventional electrowetting devices, the pyroelectric effect allowed to have an electrode-less and circuitless configuration. In our case the surface electric charge induced by the thermal stimulus is able to pattern selectively the surface wettability according to geometry of the ferroelectric domains micro-engineered into the lithium niobate crystal. We show that different geometries of liquid microlenses can be obtained showing also a tuneability of the focal lenses down to 1.6 mm. Thousand of liquid microlenses, each with 100 μm diameter, can be formed and actuated. Also different geometries such as hemi-cylindrical and toroidal liquid structures can be easily obtained. By means of a digital holography method, an accurate characterization of the micro-lenses curvature is performed and presented. The preliminary results concerning the imaging capability of the micro-lens array are also reported. Microlens array can find application in medical stereo-endoscopy, imaging, telecommunication and optical data storage too.

  3. Gradient-index microlenses: numerical investigation of different spherical index profiles with the wave propagation method.

    PubMed

    Singer, W; Testorf, M; Brenner, K H

    1995-05-01

    Ion-exchange microlenses are available with different gradient-index profiles. We investigate the dependence of the imaging properties on the steepness of the index profiles. Therefore we model the index distribution by the Fermi function as radial distribution with spherical symmetry. The results are compared to index profiles according to the Doremus model.

  4. Omnidirectional Gravitational Radiation Observatory: Proceedings of the First International Workshop

    NASA Astrophysics Data System (ADS)

    Velloso, W. F.; Aguiar, O. D.; Magalhães, N. S.

    1997-08-01

    neutron star coalescence, bar-mode instability and core colapse events by spherical antennas * Interaction of high energy muons and hadrons with a large aluminum spherical resonant detector * Optimal detection of pulsed GW signals correlated with cosmic gamma-bursts * Preliminary results of searching of joint gravity-neutrinos-gamma events * Next Generation Resonant-Mass Antennas * A 100 TON 10mK spherical gravitational wave detector * Experimental study of spherical resonators at very low temperatures * Thermal convective cooling of gravitational radiation antennas * Very low temperature measurements of quality factors of copper alloys for resonant gravitational wave antennae * Real life TIGA measurements: results from the LSU prototype * Simulation of a spherical resonant-mass gravitational wave antenna * DEFOSP: the gravitational wave detector for a space laboratory * The resonator problem in a spherical GW antenna * On the use of the Finite Elements Method to design the structures of mechanical isolation to resonant mass antennas * Transducers and Amplification Techniques * Low-loss sapphire transducers for resonant-mass Gravitational Wave detectors and quantum non-demolition readouts * Improvement of an inductive tripode transducer electrical Q * Tests of a resonant capacitive transducer with integrated readout on the cryogenic gravitational wave antenna ALTAIR * Development of an optical transducer * Noise measurements on two-squid gravitational wave transducer systems * Resonant/Free Mass Omnidirectional Network * The present status of VIRGO Project * The supernova cosmological background of gravitational waves * LIGO: status and prospects * The ring interferometer in the field of a weak gravitational wave * List of Participants

  5. General-relativistic astrophysics. [gravitational wave astronomy

    NASA Technical Reports Server (NTRS)

    Thorne, K. S.

    1978-01-01

    The overall relevance of general relativity to astrophysics is considered, and some of the knowledge about the ways in which general relativity should influence astrophysical systems is reviewed. Attention is focused primarily on finite-sized astrophysical systems, such as stars, globular clusters, galactic nuclei, and primordial black holes. Stages in the evolution of such systems and tools for studying the effects of relativistic gravity in these systems are examined. Gravitational-wave astronomy is discussed in detail, with emphasis placed on estimates of the strongest gravitational waves that bathe earth, present obstacles and future prospects for detection of the predicted waves, the theory of small perturbations of relativistic stars and black holes, and the gravitational waves such objects generate. Characteristics of waves produced by black-hole events in general, pregalactic black-hole events, black-hole events in galactic nuclei and quasars, black-hole events in globular clusters, the collapse of normal stars to form black holes or neutron stars, and corequakes in neutron stars are analyzed. The state of the art in gravitational-wave detection and characteristics of various types of detector are described.

  6. Testing the Speed of Gravitational Waves over Cosmological Distances with Strong Gravitational Lensing

    NASA Astrophysics Data System (ADS)

    Collett, Thomas E.; Bacon, David

    2017-03-01

    Probing the relative speeds of gravitational waves and light acts as an important test of general relativity and alternative theories of gravity. Measuring the arrival time of gravitational waves (GWs) and electromagnetic (EM) counterparts can be used to measure the relative speeds, but only if the intrinsic time lag between emission of the photons and gravitational waves is well understood. Here we suggest a method that does not make such an assumption, using future strongly lensed GW events and EM counterparts; Biesiada et al. [J. Cosmol. Astropart. Phys.10 (2014) 080, 10.1088/1475-7516/2014/10/080] forecast that 50-100 strongly lensed GW events will be observed each year with the Einstein Telescope. A single strongly lensed GW event would produce robust constraints on cGW/cγ at the 10-7 level, if a high-energy EM counterpart is observed within the field of view of an observing γ -ray burst monitor.

  7. Those Elusive Gravitational Waves

    ERIC Educational Resources Information Center

    MOSAIC, 1976

    1976-01-01

    The presence of gravitational waves was predicted by Einstein in his theory of General Relativity. Since then, scientists have been attempting to develop a detector sensitive enough to measure these cosmic signals. Once the presence of gravitational waves is confirmed, scientists can directly study star interiors, galaxy cores, or quasars. (MA)

  8. Advanced Gravitational Wave Detectors

    NASA Astrophysics Data System (ADS)

    Blair, D. G.; Howell, E. J.; Ju, L.; Zhao, C.

    2012-02-01

    Part I. An Introduction to Gravitational Wave Astronomy and Detectors: 1. Gravitational waves D. G. Blair, L. Ju, C. Zhao and E. J. Howell; 2. Sources of gravitational waves D. G. Blair and E. J. Howell; 3. Gravitational wave detectors D. G. Blair, L. Ju, C. Zhao, H. Miao, E. J. Howell, and P. Barriga; 4. Gravitational wave data analysis B. S. Sathyaprakash and B. F. Schutz; 5. Network analysis L. Wen and B. F. Schutz; Part II. Current Laser Interferometer Detectors: Three Case Studies: 6. The Laser Interferometer Gravitational-Wave Observatory P. Fritschel; 7. The VIRGO detector S. Braccini; 8. GEO 600 H. Lück and H. Grote; Part III. Technology for Advanced Gravitational Wave Detectors: 9. Lasers for high optical power interferometers B. Willke and M. Frede; 10. Thermal noise, suspensions and test masses L. Ju, G. Harry and B. Lee; 11. Vibration isolation: Part 1. Seismic isolation for advanced LIGO B. Lantz; Part 2. Passive isolation J-C. Dumas; 12. Interferometer sensing and control P. Barriga; 13. Stabilizing interferometers against high optical power effects C. Zhao, L. Ju, S. Gras and D. G. Blair; Part IV. Technology for Third Generation Gravitational Wave Detectors: 14. Cryogenic interferometers J. Degallaix; 15. Quantum theory of laser-interferometer GW detectors H. Miao and Y. Chen; 16. ET. A third generation observatory M. Punturo and H. Lück; Index.

  9. Gravitationally coupled electroweak monopole

    NASA Astrophysics Data System (ADS)

    Cho, Y. M.; Kimm, Kyoungtae; Yoon, J. H.

    2016-10-01

    We present a family of gravitationally coupled electroweak monopole solutions in Einstein-Weinberg-Salam theory. Our result confirms the existence of globally regular gravitating electroweak monopole which changes to the magnetically charged black hole as the Higgs vacuum value approaches to the Planck scale. Moreover, our solutions could provide a more accurate description of the monopole stars and magnetically charged black holes.

  10. Search for Gravitational Waves

    NASA Astrophysics Data System (ADS)

    Tsubono, K.

    The current status of the experimental search for gravitational waves is reviewed here. The emphasis is on the Japanese TAMA project. We started operation of the TAMA300 laser interferometric detector in 1999, and are now collecting and analyzing observational data to search for gravitational wave signals.

  11. Optimizing Vetoes for Gravitational-wave Transient Searches

    NASA Technical Reports Server (NTRS)

    Essick, R.; Blackburn, Lindy L.; Katsavounidis, E.

    2014-01-01

    Interferometric gravitational-wave detectors like LIGO, GEO600 and Virgo record a surplus of information above and beyond possible gravitational-wave events. These auxiliary channels capture information about the state of the detector and its surroundings which can be used to infer potential terrestrial noise sources of some gravitational-wave-like events. We present an algorithm addressing the ordering (or equivalently optimizing) of such information from auxiliary systems in gravitational-wave detectors to establish veto conditions in searches for gravitational-wave transients. The procedure was used to identify vetoes for searches for unmodelled transients by the LIGO and Virgo collaborations during their science runs from 2005 through 2007. In this work we present the details of the algorithm; we also use a limited amount of data from LIGO's past runs in order to examine the method, compare it with other methods, and identify its potential to characterize the instruments themselves. We examine the dependence of Receiver Operating Characteristic curves on the various parameters of the veto method and the implementation on real data. We find that the method robustly determines important auxiliary channels, ordering them by the apparent strength of their correlations to the gravitational-wave channel. This list can substantially reduce the background of noise events in the gravitational-wave data. In this way it can identify the source of glitches in the detector as well as assist in establishing confidence in the detection of gravitational-wave transients.

  12. Are some BL Lacs artefacts of gravitational lensing?

    PubMed

    Ostriker, J P; Vietri, M

    1990-03-01

    WE suggested in 1985 that a significant fraction of BL Lacertae objects, a kind of lineless quasar, seen in nearby galaxies are in fact images, gravitationally lensed and substantially amplified by stars in the nearby galaxy, of background objects, optically violent variable (OVV) quasars at redshifts z > 1 (ref. 1). This hypothesis was made on the basis of certain general similarities between BL Lacs and O Ws, but for two recently observed BL Lacs(2,3) a strong case can be made that the accompanying elliptical galaxy is a foreground object. In addition, we argue that the distribution of BL Lac redshifts is hard to understand without gravitational lensing, unless we happen to be at a very local maximum of the spatial cosmic distribution of BL Lacs. Our analysis also indicates that the galaxies whose stars are likely to act as microlenses will be found in two peaks, one nearby, with redshift 0.05-0.10, and the other near the distant quasar.

  13. Creating images by adding masses to gravitational point lenses

    NASA Astrophysics Data System (ADS)

    Sète, Olivier; Luce, Robert; Liesen, Jörg

    2015-04-01

    A well-studied maximal gravitational point lens construction of S. H. Rhie produces images of a light source using deflector masses. The construction arises from a circular, symmetric deflector configuration on masses (producing only images) by adding a tiny mass in the center of the other mass positions (and reducing all the other masses a little bit). In a recent paper we studied this "image creating effect" from a purely mathematical point of view (Sète, Luce & Liesen, Comput. Methods Funct. Theory 15(1), 2014). Here we discuss a few consequences of our findings for gravitational microlensing models. We present a complete characterization of the effect of adding small masses to these point lens models, with respect to the number of images. In particular, we give several examples of maximal lensing models that are different from Rhie's construction and that do not share its highly symmetric appearance. We give generally applicable conditions that allow the construction of maximal point lenses on masses from maximal lenses on masses.

  14. Self-aligned process for forming microlenses at the tips of vertical silicon nanowires by atomic layer deposition

    SciTech Connect

    Dan, Yaping Chen, Kaixiang; Crozier, Kenneth B.

    2015-01-01

    The microlens is a key enabling technology in optoelectronics, permitting light to be efficiently coupled to and from devices such as image sensors and light-emitting diodes. Their ubiquitous nature motivates the development of new fabrication techniques, since existing methods face challenges as microlenses are scaled to smaller dimensions. Here, the authors demonstrate the formation of microlenses at the tips of vertically oriented silicon nanowires via a rapid atomic layer deposition process. The nature of the process is such that the microlenses are centered on the nanowires, and there is a self-limiting effect on the final sizes of the microlenses arising from the nanowire spacing. Finite difference time domain electromagnetic simulations are performed of microlens focusing properties, including showing their ability to enhance visible-wavelength absorption in silicon nanowires.

  15. Discovering Habitable Earths, Hot Jupiters, and Other Close Planets with Microlensing

    NASA Astrophysics Data System (ADS)

    Di Stefano, R.

    2012-06-01

    Searches for planets via gravitational lensing have focused on cases in which the projected separation, a, between planet and star is comparable to the Einstein radius, RE . This paper considers smaller orbital separations and demonstrates that evidence of close-orbit planets can be found in the low-magnification portion of the light curves generated by the central star. We develop a protocol for discovering hot Jupiters as well as Neptune-mass and Earth-mass planets in the stellar habitable zone. When planets are not discovered, our method can be used to quantify the probability that the lens star does not have planets within specified ranges of the orbital separation and mass ratio. Nearby close-orbit planets discovered by lensing can be subject to follow-up observations to study the newly discovered planets or to discover other planets orbiting the same star. Careful study of the low-magnification portions of lensing light curves should produce, in addition to the discoveries of close-orbit planets, definite detections of wide-orbit planets through the discovery of "repeating" lensing events. We show that events exhibiting extremely high magnification can effectively be probed for planets in close, intermediate, and wide distance regimes simply by adding several-time-per-night monitoring in the low-magnification wings, possibly leading to gravitational lensing discoveries of multiple planets occupying a broad range of orbits, from close to wide, in a single planetary system.

  16. DISCOVERING HABITABLE EARTHS, HOT JUPITERS, AND OTHER CLOSE PLANETS WITH MICROLENSING

    SciTech Connect

    Di Stefano, R.

    2012-06-20

    Searches for planets via gravitational lensing have focused on cases in which the projected separation, a, between planet and star is comparable to the Einstein radius, R{sub E} . This paper considers smaller orbital separations and demonstrates that evidence of close-orbit planets can be found in the low-magnification portion of the light curves generated by the central star. We develop a protocol for discovering hot Jupiters as well as Neptune-mass and Earth-mass planets in the stellar habitable zone. When planets are not discovered, our method can be used to quantify the probability that the lens star does not have planets within specified ranges of the orbital separation and mass ratio. Nearby close-orbit planets discovered by lensing can be subject to follow-up observations to study the newly discovered planets or to discover other planets orbiting the same star. Careful study of the low-magnification portions of lensing light curves should produce, in addition to the discoveries of close-orbit planets, definite detections of wide-orbit planets through the discovery of 'repeating' lensing events. We show that events exhibiting extremely high magnification can effectively be probed for planets in close, intermediate, and wide distance regimes simply by adding several-time-per-night monitoring in the low-magnification wings, possibly leading to gravitational lensing discoveries of multiple planets occupying a broad range of orbits, from close to wide, in a single planetary system.

  17. The gravitational wave decade

    NASA Astrophysics Data System (ADS)

    Conklin, John

    2016-03-01

    With the expected direct detection of gravitational waves by Advanced LIGO and pulsar timing arrays in the near future, and with the recent launch of LISA Pathfinder this can arguably be called the decade of gravitational waves. Low frequency gravitational waves in the mHz range, which can only be observed from space, provide the richest science and complement high frequency observatories on the ground. A space-based observatory will improve our understanding of the formation and growth of massive black holes, create a census of compact binary systems in the Milky Way, test general relativity in extreme conditions, and enable searches for new physics. LISA, by far the most mature concept for detecting gravitational waves from space, has consistently ranked among the nation's top priority large science missions. In 2013, ESA selected the science theme ``The Gravitational Universe'' for its third large mission, L3, under the Cosmic Visions Program, with a planned launch date of 2034. NASA has decided to join with ESA on the L3 mission as a junior partner and has recently assembled a study team to provide advice on how NASA might contribute to the European-led mission. This talk will describe these efforts and the activities of the Gravitational Wave Science Interest Group and the L3 Study Team, which will lead to the first space-based gravitational wave observatory.

  18. Fitting gravitational lenses: truth or delusion

    NASA Astrophysics Data System (ADS)

    Evans, N. Wyn; Witt, Hans J.

    2003-11-01

    The observables in a strong gravitational lens are usually just the image positions and sometimes the flux ratios. We develop a new and simple algorithm which allows a set of models to be fitted exactly to the observations. Taking our cue from the strong body of evidence that early-type galaxies are close to isothermal, we assume that the lens is scale-free with a flat rotation curve. External shear can be easily included. Our algorithm allows full flexibility regarding the angular structure of the lensing potential. Importantly, all the free parameters enter linearly into the model and so the lens and flux ratio equations can always be solved by straightforward matrix inversion. The models are only restricted by the fact that the surface mass density must be positive. We use this new algorithm to examine some of the claims made for anomalous flux ratios. It has been argued that such anomalies betray the presence of substantial amounts of substructure in the lensing galaxy. We demonstrate by explicit construction that some of the lens systems for which substructure has been claimed can be well fitted by smooth lens models. This is especially the case when the systematic errors in the flux ratios (caused by microlensing or differential extinction) are taken into account. However, there is certainly one system (B1422+231) for which the existing smooth models are definitely inadequate and for which substructure may be implicated. Within a few tens of kpc of the lensing galaxy centre, dynamical friction and tidal disruption are known to be very efficient at dissolving any substructure. Very little substructure is projected within the Einstein radius. The numbers of strong lenses for which substructure is currently being claimed may be so large that this contradicts rather than supports cold dark matter theories.

  19. Towards Gravitational Wave Astronomy

    NASA Astrophysics Data System (ADS)

    Losurdo, Giovanni

    This chapter is meant to introduce the reader to the forthcoming network of second-generation interferometric detectors of gravitational waves, at a time when their construction is close to completion and there is the ambition to detect gravitational waves for the first time in the next few years and open the way to gravitational wave astronomy. The legacy of first-generation detectors is discussed before giving an overview of the technology challenges that have been faced to make advanced detectors possible. The various aspects outlined here are then discussed in more detail in the subsequent chapters of the book.

  20. Exploring Gravitational Waves in the Classroom

    NASA Astrophysics Data System (ADS)

    Cominsky, Lynn R.; McLin, Kevin M.; Peruta, Carolyn; Simonnet, Aurore

    2016-04-01

    On September 14, 2015, the Laser Interferometer Gravitational-wave Observatory (LIGO) received the first confirmed gravitational wave signals. Now known as GW150914 (for the date on which the signals were received), the event represents the coalescence of two black holes that were previously in mutual orbit. LIGO’s exciting discovery provides direct evidence of what is arguably the last major unconfirmed prediction of Einstein’s General Theory of Relativity. The Education and Public Outreach group at Sonoma State University has created an educator's guide that provides a brief introduction to LIGO and to gravitational waves, along with two simple demonstration activities that can be done in the classroom to engage students in understanding LIGO’s discovery. Additional resources have also been provided to extend student explorations of Einstein’s Universe.

  1. Gravitational Lensing Illustration

    NASA Video Gallery

    Simulation of a gravitational lens moving against a background field of galaxy. The gravity of the mass of the foreground object warps space. This bends the light of background galaxies making them...

  2. Preparation of plastic spherical microlenses by use of a fluoropolymer stencil and oil-bath heating.

    PubMed

    Tamura, Hiromoto; Kojima, Ryousuke; Usui, Hiroaki

    2003-07-01

    A new method for fabricating plastic spherical microlenses was developed, which allowed self-alignment of lenses and self-organized formation of a spherical shape. First a low-surface-energy fluoropolymer thin film was deposited and patterned as a stencil. Then photosensitive phenol resin was patterned on it as the lens material. Finally the resin was annealed in an oil bath to form a sphere. The molten phenol resin spontaneously formed a sphere and positioned itself in the center of the fluoropolymer ring pattern as a result of the difference of surface free energy and the equivalently zero-gravity condition in the oil bath. When a light-emitting-diode printer head was loaded with spherical microlenses, its optical output increased by 1 order of magnitude.

  3. Characteristics of stand-alone microlenses in fiber-based fluorescence imaging applications.

    PubMed

    Mirkhalaf, M; Murukeshan, V M; Tor, Shu Beng; Shinoj, V K; Sathiyamoorthy, K

    2011-04-01

    Microlens-ended fibers, which have found tremendous interest in the recent past, find potential biomedical applications, in particular, in endoscopic imaging. The work presented in this paper focuses on the stand-alone microlenses along with custom-fabricated specialty optical fiber, such as imaging fiber, for probe imaging applications. Stand-alone self-aligned microlenses have been fabricated employing microcompression molding and then attached at the end facet of imaging fiber. A detailed characterization of the fabricated microlens is carried and it demonstrates appropriate focusing ability, high fluorescence collection efficiency and imaging ability for biomedical applications. The surface roughness of the microlens is found to be 25 nm with a minimum spot size of 38 μm. The probe imaging system is found to be able to image the fluorescence microspheres of 10 μm size. The collection efficiency of the fiber probe with lens found to be enhanced by three times approximately.

  4. An efficient method to compute microlensed light curves for point sources

    NASA Technical Reports Server (NTRS)

    Witt, Hans J.

    1993-01-01

    We present a method to compute microlensed light curves for point sources. This method has the general advantage that all microimages contributing to the light curve are found. While a source moves along a straight line, all micro images are located either on the primary image track or on the secondary image tracks (loops). The primary image track extends from - infinity to + infinity and is made of many sequents which are continuously connected. All the secondary image tracks (loops) begin and end on the lensing point masses. The method can be applied to any microlensing situation with point masses in the deflector plane, even for the overcritical case and surface densities close to the critical. Furthermore, we present general rules to evaluate the light curve for a straight track arbitrary placed in the caustic network of a sample of many point masses.

  5. Precision compression molding of glass microlenses and microlens arrays--an experimental study.

    PubMed

    Firestone, G C; Yi, A Y

    2005-10-10

    An innovative manufacturing process utilizing high-temperature compression molding to fabricate aspherical microlenses by using optical glasses, such as BK7, K-PG325, and soda-lime glass, is investigated. In a departure from conventional approaches, a unique hollow contactless mold design is adopted. Polished glass substrates and the mold assembly are heated above the glass transition temperature first, followed by initial forming, then annealing. The forming rate is controlled in real time to ensure mold position accuracy. Mold materials used include tungsten carbides, 316 stainless steel, 715 copper nickel, and aluminum alloys. The geometric control of the microlenses or microlens arrays can be precisely controlled by the forming temperature, forming speed, mold design, and annealing time.

  6. A simple focal-length measurement technique for adaptive microlenses using z-scan

    NASA Astrophysics Data System (ADS)

    Abdelaziez, Yasser; Banerjee, Partha P.

    2004-10-01

    A simple technique for focal length measurements of adaptive micro-lenses using z-scan is reported. Focal length is one of the most important parameters of any lens. The effective focal length is measured with reference to the principal points that are not easy to find especially for micro-lenses. In addition, variable focal length microlenses pose a different challenge that makes the process of determining their exact focal length a tedious and difficult process. Classical methods such as nodal slide and magnification have been used for focal length determination. Also, advanced Interference techniques such as Talbot, Moire, Digital Speckle, Zygo and Joint Fourier Transform were used for focal length measurements. These techniques require more elaborate setups and difficult to implement, especially for microlenses. Recently a power meter was used to find the focal length of an unknown lens. Most of the techniques mentioned above proof to be not simple for microlens characterization. The z-scan technique has been implemented, for quite sometimes, to characterize the third-order effects of a nonlinear optical material. The z-scan provides information on both the sign and magnitude of the non-linear refractive index and offer advantage of simplicity. We have used a regular lens to collimate and focus light unto the lens under test. By scanning the lens under test and measuring the on-axis intensity, one can find the focal length. This is because the on-axis intensity is proportional to the phase of the lens and therefore the focal length. In the case of an adaptive lens with its focal length is a function of the applied voltage, the scanning occurs for each voltage value that will correspond to the on-axis refractive index change and therefore the far field on-axis intensity. This described technique above is easy to implement and can achieve good accuracy due to the inherent sensitivity of the z-scan.

  7. Detection of the 4th caustic crossing in the Gaia16aye binary microlensing system

    NASA Astrophysics Data System (ADS)

    Khamitov, I.; Bikmaev, I.; Burenin, R.; Grebenev, S.; Tanriver, M.; Avci, A.; Kaynar, S.; Gumus, D.; Kocak, M.; Ãzisik, T.; Dindar, M.; Esenoglu, H.; Kirbiyik, H.; Okuyan, O.; Saygac, T.; Semena, A.; Tkachenko, A.; Irtuganov, E.; Melnikov, S.; Pavlinsky, M.; Sakhibullin, N.; Sunyaev, R.

    2016-11-01

    Following the brightening recently detected in the direction of the Gaia16aye binary microlensing system (ATel #9753) and the subsequent prediction for it of the close caustic crossing (ATel #9770) we organized regular observations of the system with the RTT-150 and T-100 telescopes (Antalya, Turkey) and detected the caustic crossing on Nov. 21, 2016, at 17:54 UTC (JD 2457714.246).

  8. Limits on MACHOs from microlensing in the double quasar Q0957+561

    NASA Astrophysics Data System (ADS)

    Schmidt, Robert; Wambsganss, Joachim

    1998-07-01

    The light curves of the two images of the double quasar Q0957+561 as obtained by Kundicet al. (1997) are almost identical, except for an overall time delay and scaling factor. This allows us to put limits on the amount of microlensing that took place during the time interval corresponding to the monitoring observations. We perform numerical simulations in which we model the microlensing behaviour of the (halo of the) lensing galaxy in the system. We test ``MACHO-masses'' ranging from 10(-8) to 10(-1) Msun and quasar sizes from 10(14) to 3x 10(15) cm. Statistically comparing the expected microlensing-induced changes from 100 000 simulated light curves over a period of 160 days with the (lack of) observed fluctuations, we can constrain regions in the parameter space of MACHO mass and quasar size with various degrees of confidence. In particular, a halo consisting of objects at the low end of our mass scale can be ruled out with high confidence for a small quasar size. A halo consisting of objects with 10(-2) or 10(-1) Msun cannot be ruled out yet, but it should produce MACHO induced fluctuations in future observations. We also test halos with only 50% or 25% of the mass in compact objects; constraints here are a bit less stringent.

  9. ADAPTIVE OPTICS OBSERVATIONS OF B0128+437: A LOW-MASS, HIGH-REDSHIFT GRAVITATIONAL LENS

    SciTech Connect

    Lagattuta, David J.; Fassnacht, Christopher D.; Auger, Matthew W.

    2010-06-20

    We use high-resolution adaptive optics (AO) imaging on the Keck II telescope to study the gravitational lens B0128+437 in unprecedented detail, allowing us to resolve individual lensed quasar components and, for the first time, detect and measure properties of the lensing galaxy. B0128+437 is a small-separation lens with known flux-ratio and astrometric anomalies. We discuss possible causes for these anomalies, including the presence of substructure in the lensing galaxy, propagation effects due to dust and a turbulent interstellar medium, and gravitational microlensing. This work demonstrates that AO will be an essential tool for studying the many new small-separation lenses expected from future surveys.

  10. Gravitational-wave detection using multivariate analysis

    NASA Astrophysics Data System (ADS)

    Adams, Thomas S.; Meacher, Duncan; Clark, James; Sutton, Patrick J.; Jones, Gareth; Minot, Ariana

    2013-09-01

    Searches for gravitational-wave bursts (transient signals, typically of unknown waveform) require identification of weak signals in background detector noise. The sensitivity of such searches is often critically limited by non-Gaussian noise fluctuations that are difficult to distinguish from real signals, posing a key problem for transient gravitational-wave astronomy. Current noise rejection tests are based on the analysis of a relatively small number of measured properties of the candidate signal, typically correlations between detectors. Multivariate analysis (MVA) techniques probe the full space of measured properties of events in an attempt to maximize the power to accurately classify events as signal or background. This is done by taking samples of known background events and (simulated) signal events to train the MVA classifier, which can then be applied to classify events of unknown type. We apply the boosted decision tree (BDT) MVA technique to the problem of detecting gravitational-wave bursts associated with gamma-ray bursts. We find that BDTs are able to increase the sensitive distance reach of the search by as much as 50%, corresponding to a factor of ˜3 increase in sensitive volume. This improvement is robust against trigger sky position, large sky localization error, poor data quality, and the simulated signal waveforms that are used. Critically, we find that the BDT analysis is able to detect signals that have different morphologies from those used in the classifier training and that this improvement extends to false alarm probabilities beyond the 3σ significance level. These findings indicate that MVA techniques may be used for the robust detection of gravitational-wave bursts with a priori unknown waveform.

  11. The microlensing rate and distribution of free-floating planets towards the Galactic bulge

    NASA Astrophysics Data System (ADS)

    Ban, M.; Kerins, E.; Robin, A. C.

    2016-10-01

    Context. Ground-based optical microlensing surveys have provided tantalising, if inconclusive, evidence for a significant population of free-floating planets (FFPs). Both ground- and space-based facilities are being used and developed which will be able to probe the distrubution of FFPs with much better sensitivity. It is also vital to develop a high-precision microlensing simulation framework to evaluate the completeness of such surveys. Aims: We present the first signal-to-noise limited calculations of the FFP microlensing rate using the Besançon Galactic model. The microlensing distribution towards the Galactic centre is simulated for wide-area ground-based optical surveys (I-band) such as OGLE or MOA, a wide-area ground-based near-infrared survey (K-band), and a targeted space-based near-infrared survey (H-band) which could be undertaken with Euclid or WFIRST. Methods: We present a calculation framework for the computation of the optical and near-infrared microlensing rate and optical depth for simulated stellar catalogues which are signal-to-noise limited, and take account of extinction, unresolved stellar background light, and finite source size effects, which can be significant for FFPs. Results: We find that the global ground-based I-band yield over a central 200 deg2 region covering the Galactic centre ranges from 20 Earth-mass FFPs yr-1 up to 3500 yr-1 for Jupiter FFPs in the limit of 100% detection efficiency, and almost an order of magnitude larger for a K-band survey. For ground-based surveys we find that the inclusion of finite source and the unresolved background reveals a mass-dependent variation in the spatial distribution of FFPs. For a targeted space-based H-band covering 2 deg2, the yield depends on the target field but maximises close to the Galactic centre with around 76 Earth to 1700 Jupiter FFPs per year. For near-IR space-based surveys like Euclid or WFIRST the spatial distribution of FFPs is found to be largely insensitive to the FFP mass

  12. Black holes as gravitational atoms

    NASA Astrophysics Data System (ADS)

    Vaz, Cenalo

    2014-06-01

    Recently, it was argued [A. Almheiri et al., arXiv: 1207.3123, A. Almheiri et al., arXiv: 1304.6483], via a delicate thought experiment, that it is not consistent to simultaneously require that (a) Hawking radiation is pure, (b) effective field theory is valid outside a stretched horizon and (c) infalling observers encounter nothing unusual as they cross the horizon. These are the three fundamental assumptions underlying Black Hole Complementarity and the authors proposed that the most conservative resolution of the paradox is that (c) is false and the infalling observer burns up at the horizon (the horizon acts as a "firewall"). However, the firewall violates the equivalence principle and breaks the CPT invariance of quantum gravity. This led Hawking to propose recently that gravitational collapse may not end up producing event horizons, although he did not give a mechanism for how this may happen. Here we will support Hawking's conclusion in a quantum gravitational model of dust collapse. We will show that continued collapse to a singularity can only be achieved by combining two independent and entire solutions of the Wheeler-DeWitt equation. We interpret the paradox as simply forbidding such a combination. This leads naturally to a picture in which matter condenses on the apparent horizon during quantum collapse.

  13. Gravitation, photons, clocks.

    NASA Astrophysics Data System (ADS)

    Okun, L. B.; Selivanov, K. G.; Telegdi, V.

    1999-10-01

    This paper is concerned with the classical phenomenon of gravitational red shift, the decrease in the measured frequency of a photon moving away from a gravitating body (e.g., the Earth) of the two current interpretations, one is that at higher altitudes the frequency-measuring clocks (atoms or atomic nuclei) run faster, i.e., their characteristic frequencies are higher, while the photon frequency in a static gravitational field is independent of the altitude and so the photon only reddens relative to the clocks. The other approach is that the photon reddens because it loses the energy when overcoming the attraction of the gravitational field. This view, which is especially widespread in popular science literature, ascribes such notions as a "gravitational mass" and "potential energy" to the photon. Unfortunately, also scientific papers and serious books on the general theory of relativity often employ the second interpretation as a "graphic" illustration of mathematically immaculate results. The authors show that this approach is misleading and only serves to create confusion in a simple subject.

  14. Strong gravitational lensing of gravitational waves from double compact binaries—perspectives for the Einstein Telescope

    SciTech Connect

    Biesiada, Marek; Ding, Xuheng; Zhu, Zong-Hong; Piórkowska, Aleksandra E-mail: dingxuheng@mail.bnu.edu.cn E-mail: zhuzh@bnu.edu.cn

    2014-10-01

    Gravitational wave (GW) experiments are entering their advanced stage which should soon open a new observational window on the Universe. Looking into this future, the Einstein Telescope (ET) was designed to have a fantastic sensitivity improving significantly over the advanced GW detectors. One of the most important astrophysical GW sources supposed to be detected by the ET in large numbers are double compact objects (DCO) and some of such events should be gravitationally lensed by intervening galaxies. We explore the prospects of observing gravitationally lensed inspiral DCO events in the ET. This analysis is a significant extension of our previous paper [1]. We are using the intrinsic merger rates of the whole class of DCO (NS-NS,BH-NS,BH-BH) located at different redshifts as calculated by [2] by using StarTrack population synthesis evolutionary code. We discuss in details predictions from each evolutionary scenario. Our general conclusion is that ET would register about 50–100 strongly lensed inspiral events per year. Only the scenario in which nascent BHs receive strong kick gives the predictions of a few events per year. Such lensed events would be dominated by the BH-BH merging binary systems. Our results suggest that during a few years of successful operation ET will provide a considerable catalog of strongly lensed events.

  15. THE SECOND MULTIPLE-PLANET SYSTEM DISCOVERED BY MICROLENSING: OGLE-2012-BLG-0026Lb, c-A PAIR OF JOVIAN PLANETS BEYOND THE SNOW LINE

    SciTech Connect

    Han, C.; Choi, J.-Y.; Udalski, A.; Szymanski, M. K.; Kubiak, M.; Soszynski, I.; Pietrzynski, G.; Poleski, R.; Ulaczyk, K.; Pietrukowicz, P.; Kozlowski, S.; Wyrzykowski, L.; Yee, J. C.; Gould, A.; Skowron, J.; Batista, V.; Christie, G.; Tan, T.-G.; Almeida, L. A.; Depoy, D. L.; Collaboration: OGLE Collaboration; muFUN Collaboration; and others

    2013-01-10

    We report the discovery of a planetary system from observation of the high-magnification microlensing event OGLE-2012-BLG-0026. The lensing light curve exhibits a complex central perturbation with multiple features. We find that the perturbation was produced by two planets located near the Einstein ring of the planet host star. We identify four possible solutions resulting from the well-known close/wide degeneracy. By measuring both the lens parallax and the Einstein radius, we estimate the physical parameters of the planetary system. According to the best-fit model, the two planet masses are {approx}0.11 M{sub J} and 0.68 M{sub J} and they are orbiting a G-type main-sequence star with a mass {approx}0.82 M{sub Sun }. The projected separations of the individual planets are beyond the snow line in all four solutions, being {approx}3.8 AU and 4.6 AU in the best-fit solution. The deprojected separations are both individually larger and possibly reversed in order. This is the second multi-planet system with both planets beyond the snow line discovered by microlensing. This is the only such system (other than the solar system) with measured planet masses without sin i degeneracy. The planetary system is located at a distance 4.1 kpc from the Earth toward the Galactic center. It is very likely that extra light from stars other than the lensed star comes from the lens itself. If this is correct, it will be possible to obtain detailed information about the planet host star from follow-up observation.

  16. Nuclear Quantum Gravitation - Forces Unification

    NASA Astrophysics Data System (ADS)

    Kotas, Ronald

    2017-01-01

    With Nuclear Quantum Gravitation, the Forces are plainly and coherently unified. This most certainly is the missing link in Newtonian Gravitation explaining clearly the internal workings based in the Atomic Nucleus. The gravitational force between two gravitating masses is because of alternating electromagnetic functions in nuclei in matter. The Cavendish Experiment - Demonstration clearly shows the Gravitational attraction between two masses, which is a force proportional to the Newtonian Mechanics. General Relativity fails this real, physical test. Nuclear Quantum Gravitation has 10 logical proofs and 21 more indications. It is Scientifically logical and is compatible with Quantum Mechanics and Newtonian Mechanics.

  17. Gravitational potential as a source of earthquake energy

    USGS Publications Warehouse

    Barrows, L.; Langer, C.J.

    1981-01-01

    Some degree of tectonic stress within the earth originates from gravity acting upon density structures. The work performed by this "gravitational tectonics stress" must have formerly existed as gravitational potential energy contained in the stress-causing density structure. According to the elastic rebound theory (Reid, 1910), the energy of earthquakes comes from an elastic strain field built up by fairly continuous elastic deformation in the period between events. For earthquakes resulting from gravitational tectonic stress, the elastic rebound theory requires the transfer of energy from the gravitational potential of the density structures into an elastic strain field prior to the event. An alternate theory involves partial gravitational collapse of the stress-causing density structures. The earthquake energy comes directly from a net decrease in gravitational potential energy. The gravitational potential energy released at the time of the earthquake is split between the energy released by the earthquake, including work done in the fault zone and an increase in stored elastic strain energy. The stress associated with this elastic strain field should oppose further fault slip. ?? 1981.

  18. Breeding gravitational lenses

    NASA Astrophysics Data System (ADS)

    Liesenborgs, J.; de Rijcke, S.; Dejonghe, H.; Bekaert, P.

    2011-03-01

    Gravitational lenses are a spectacular astrophysical phenomenon, a cosmic mirage caused by the gravitational deflection of light in which multiple images of a same background object can be seen. Their beauty is only exceeded by their usefulness, as the gravitational lens effect is a direct probe of the total mass of the deflecting object. Furthermore, since the image configuration arising from the gravitational lens effect depends on the exact gravitational potential of the deflector, it even holds the promise of learning about the distribution of the mass. In this presentation, a method for extracting the information encoded in the images and reconstructing the mass distribution is presented. Being a non-parametric method, it avoids making a priori assumptions about the shape of the mass distribution. At the core of the procedure lies a genetic algorithm, an optimization strategy inspired by Darwin's principle of ``survival of the fittest''. One only needs to specify a criterion to decide if one particular trial solution is deemed better than another, and the genetic algorithm will ``breed'' appropriate solutions to the problem. In a similar way, one can create a multi-objective genetic algorithm, capable of optimizing several fitness criteria at the same time. This provides a very flexible way to incorporate all the available information in the gravitational lens system: not only the positions and shapes of the multiple images are used, but also the so-called ``null space'', i.e. the area in which no such images can be seen. The effectiveness of this approach is illustrated using simulated data, which allows one to compare the reconstruction to the true mass distribution.

  19. Gravitational lensing by black holes: The case of Sgr A*

    SciTech Connect

    Bozza, V.

    2014-01-14

    The strong gravitational fields created by black holes dramatically affect the propagation of photons by bending their trajectories. Gravitational lensing thus stands as the main source of information on the space-time structure in such extreme regimes. We will review the theory and phenomenology of gravitational lensing by black holes, with the generation of higher order images and giant caustics by rotating black holes. We will then focus on Sgr A*, the black hole at the center of the Milky Way, for which next-to-come technology will be able to reach resolutions of the order of the Schwarzschild radius and ultimately test the existence of an event horizon.

  20. Gravitational-Wave Astronomy

    NASA Technical Reports Server (NTRS)

    Kelly, Bernard J.

    2010-01-01

    Einstein's General Theory of Relativity is our best classical description of gravity, and informs modern astronomy and astrophysics at all scales: stellar, galactic, and cosmological. Among its surprising predictions is the existence of gravitational waves -- ripples in space-time that carry energy and momentum away from strongly interacting gravitating sources. In my talk, I will give an overview of the properties of this radiation, recent breakthroughs in computational physics allowing us to calculate the waveforms from galactic mergers, and the prospect of direct observation with interferometric detectors such as LIGO and LISA.

  1. New gravitational memories

    NASA Astrophysics Data System (ADS)

    Pasterski, Sabrina; Strominger, Andrew; Zhiboedov, Alexander

    2016-12-01

    The conventional gravitational memory effect is a relative displacement in the position of two detectors induced by radiative energy flux. We find a new type of gravitational `spin memory' in which beams on clockwise and counterclockwise orbits acquire a relative delay induced by radiative angular momentum flux. It has recently been shown that the displacement memory formula is a Fourier transform in time of Weinberg's soft graviton theorem. Here we see that the spin memory formula is a Fourier transform in time of the recently-discovered subleading soft graviton theorem.

  2. Three-dimensional profilometry of microlenses by phase shifting interferometery using nematic liquid crystal material filled cell as a phase modulator.

    PubMed

    Inam, M; Srivastava, V; Mehta, D S

    2015-02-10

    In this paper, we report the use of a nematic liquid crystal material filled cell in transmission mode as a voltage controlled phase modulator for the characterization of microlenses. In one arm of the Mach-Zehnder interferometer, a nematic liquid crystal filled cell with DC voltage connection was placed, and in another arm of the interferometer microlenses with a 4-F imaging system were placed. Interference takes place between the light beams coming from the two arms of the Mach-Zehnder interferometer, one after passing through the nematic liquid crystal cell and another after passing through microlenses. Interference patterns were recorded by a CCD camera. By applying DC voltage to the nematic liquid crystal filled cell, various phase shifted interferograms were recorded, and from phase shifted interferograms, the shape and size of microlenses were determined. The results of the reconstructed profile of the microlenses are compared with white-light profilometry.

  3. Gravitational-Wave Detection (ii). Current Gravitational Wave Detector Results

    NASA Astrophysics Data System (ADS)

    Kanda, Nobuyuki

    2005-11-01

    The workshop session C1ii was focused on the results of recent operating detectors. 10 speakers presented the latest results of each experiments: ALLEGRO, GEO, LIGO, TAMA and VIRGO experiments. There were reports about searches for gravitational waves in analysis of observation data. The results are of no detection of gravitational waves, but observational upper-limits of gravitational waves are improved.

  4. Probing gravitational dark matter

    SciTech Connect

    Ren, Jing; He, Hong-Jian

    2015-03-27

    So far all evidences of dark matter (DM) come from astrophysical and cosmological observations, due to the gravitational interactions of DM. It is possible that the true DM particle in the universe joins gravitational interactions only, but nothing else. Such a Gravitational DM (GDM) may act as a weakly interacting massive particle (WIMP), which is conceptually simple and attractive. In this work, we explore this direction by constructing the simplest scalar GDM particle χ{sub s}. It is a ℤ{sub 2} odd singlet under the standard model (SM) gauge group, and naturally joins the unique dimension-4 interaction with Ricci curvature, ξ{sub s}χ{sub s}{sup 2}R, where ξ{sub s} is the dimensionless nonminimal coupling. We demonstrate that this gravitational interaction ξ{sub s}χ{sub s}{sup 2}R, together with Higgs-curvature nonminimal coupling term ξ{sub h}H{sup †}HR, induces effective couplings between χ{sub s}{sup 2} and SM fields, and can account for the observed DM thermal relic abundance. We analyze the annihilation cross sections of GDM particles and derive the viable parameter space for realizing the DM thermal relic density. We further study the direct/indirect detections and the collider signatures of such a scalar GDM. These turn out to be highly predictive and testable.

  5. Gravitational waves from technicolor

    SciTech Connect

    Jaervinen, Matti; Sannino, Francesco; Kouvaris, Chris

    2010-03-15

    We investigate the production and possible detection of gravitational waves stemming from the electroweak phase transition in the early universe in models of minimal walking technicolor. In particular we discuss the two possible scenarios in which one has only one electroweak phase transition and the case in which the technicolor dynamics allows for multiple phase transitions.

  6. Research on gravitational physiology

    NASA Technical Reports Server (NTRS)

    Brown, A. H.; Dahl, A. O.

    1974-01-01

    The topic of gravitational plant physiology was studied through aspects of plant development (in ARABIDOPSIS) and of behavior (in HELIANTHUS) as these were affected by altered g experience. The effect of increased g levels on stem polarity (in COLEUS) was also examined.

  7. Locating gravitational potential energy

    NASA Astrophysics Data System (ADS)

    Keeports, David

    2017-01-01

    Where does gravitational potential energy reside when a ball is in the air? The perfectly correct answer is that it is located in the ball-Earth system. Still, mechanical energy conservation problems are routinely solved by assigning a potential energy to the ball alone. Provided here is a proof that such an assignment introduces only an entirely undetectable error.

  8. Weak Gravitational Lensing

    NASA Astrophysics Data System (ADS)

    Pires, Sandrine; Starck, Jean-Luc; Leonard, Adrienne; Réfrégier, Alexandre

    2012-03-01

    This chapter reviews the data mining methods recently developed to solve standard data problems in weak gravitational lensing. We detail the different steps of the weak lensing data analysis along with the different techniques dedicated to these applications. An overview of the different techniques currently used will be given along with future prospects. Until about 30 years ago, astronomers thought that the Universe was composed almost entirely of ordinary matter: protons, neutrons, electrons, and atoms. The field of weak lensing has been motivated by the observations made in the last decades showing that visible matter represents only about 4-5% of the Universe (see Figure 14.1). Currently, the majority of the Universe is thought to be dark, that is, does not emit electromagnetic radiation. The Universe is thought to be mostly composed of an invisible, pressure less matter - potentially relic from higher energy theories - called "dark matter" (20-21%) and by an even more mysterious term, described in Einstein equations as a vacuum energy density, called "dark energy" (70%). This "dark" Universe is not well described or even understood; its presence is inferred indirectly from its gravitational effects, both on the motions of astronomical objects and on light propagation. So this point could be the next breakthrough in cosmology. Today's cosmology is based on a cosmological model that contains various parameters that need to be determined precisely, such as the matter density parameter Omega_m or the dark energy density parameter Omega_lambda. Weak gravitational lensing is believed to be the most promising tool to understand the nature of dark matter and to constrain the cosmological parameters used to describe the Universe because it provides a method to directly map the distribution of dark matter (see [1,6,60,63,70]). From this dark matter distribution, the nature of dark matter can be better understood and better constraints can be placed on dark energy

  9. MOA-2008-BLG-379Lb: A massive planet from a high magnification event with a faint source

    SciTech Connect

    Suzuki, D.; Sumi, T.; Fukagawa, M.; Shibai, H.; Udalski, A.; Bennett, D. P.; Bond, I. A.; Ling, C. H.; Abe, F.; Furusawa, K.; Itow, Y.; Masuda, K.; Matsubara, Y.; Botzler, C. S.; Freeman, M.; Rattenbury, N.; Fukui, A.; Muraki, Y.; Ohnishi, K.; Saito, To.; Collaboration: MOA Collaboration; OGLE Collaboration; and others

    2014-01-10

    We report on the analysis of the high microlensing event MOA-2008-BLG-379, which has a strong microlensing anomaly at its peak due to a massive planet with a mass ratio of q = 6.9 × 10{sup –3}. Because the faint source star crosses the large resonant caustic, the planetary signal dominates the light curve. This is unusual for planetary microlensing events, and as a result, the planetary nature of this light curve was not immediately noticed. The planetary nature of the event was found when the Microlensing Observations in Astrophysics (MOA) Collaboration conducted a systematic study of binary microlensing events previously identified by the MOA alert system. We have conducted a Bayesian analysis based on a standard Galactic model to estimate the physical parameters of the lens system. This yields a host star mass of M{sub L}=3.3{sub −1.2}{sup +1.7} M{sub ⊙} orbited by a planet of mass m{sub P}=0.56{sub −0.27}{sup +0.24} M{sub Jup} at an orbital separation of a=3.3{sub −1.2}{sup +1.3} AU at a distance of D{sub L}=4.1{sub −1.9}{sup +1.7} kpc. The faint source magnitude of I {sub S} = 21.30 and relatively high lens-source relative proper motion of μ{sub rel} = 7.6 ± 1.6 mas yr{sup –1} imply that high angular resolution adaptive optics or Hubble Space Telescope observations are likely to be able to detect the source star, which would determine the masses and distance of the planet and its host star.

  10. VizieR Online Data Catalog: Microlensing maps for a cusp configuration (Sluse+, 2013)

    NASA Astrophysics Data System (ADS)

    Sluse, D.; Kishimoto, M.; Anguita, T.; Wucknitz, O.; Wambsganss, J.

    2013-03-01

    The microlensing maps (see maps.dat) are generated with the inverse ray-shooting code developped by Prof. J. Wambsganss (Wambsganss 1990, PhD thesis). They are computed for a saddle-point image with (kappa,gamma)=(0.47,0.57) and for a minimum image with (kappa,gamma)=(0.42,0.50). Those values match those found for images A & B of the lensed AGN J1131-1231 (assuming a Singular Isothermal Ellipsoid+shear lens model). Each map has been computed for 3 different fraction of kappa_star (i.e. convergence in form of compact objects): 0.07, 0.30, 1.0. For each case, there is a high resolution map of 100eta0x100eta0 (eta0 = microlensing Einstein radius =3*10+16cm) and a low resolution map of 250eta0x250eta0. Source profiles (sources.dat) are calculated for the same two resolution (i.e. low/high). Three source brightness profiles are provided: a uniform disc, a ring-like uniform compact torus, a ring-like extended torus. The torus characteristics are described in Table 1 of the main paper. The source profile is calculated for 3 different luminosities (10+44.2, 10+45, 10+46erg/s/cm2) and rest-frame wavelengths (1.0, 2.2, 4.4um) as described in sources.dat. Source profiles which are larger that the microlensing maps are not calculated and are listed in nosources.dat. (4 data files).

  11. VizieR Online Data Catalog: Abundances of microlensed Bulge dwarf stars. V. (Bensby+, 2013)

    NASA Astrophysics Data System (ADS)

    Bensby, T.; Yee, J. C.; Feltzing, S.; Johnson, J. A.; Gould, A.; Cohen, J. G.; Asplund, M.; Melendez, J.; Lucatello, S.; Han, C.; Thompson, I.; Gal-Yam, A.; Udalski, A.; Benett, D. P.; Bond, I. A.; Kohei, W.; Sumi, T.; Suzuki, D.; Suzuki, K.; Takino, S.; Tristram, P.; Yamai, N.; Yonehara, A.

    2012-11-01

    For each spectral line we give the lower excitation potential, measured equivalent widths, and derived absolute abundances. We also give median abundances for each star, normalised to the Sun, and errors in the median abundances. These tables contain data for all so far 58 microlensed dwarf stars, and superseeds the tables in Bensby+ (2009, Cat. J/A+A/499/737), Bensby+ (2010, Cat. J/A+A/512/A41), and Bensby+ (2011, Cat. J/A+A/533/A134). (4 data files).

  12. Strong chromatic microlensing in HE0047–1756 and SDSS1155+6346

    SciTech Connect

    Rojas, K.; Motta, V.; Mediavilla, E.; Jiménez-Vicente, J.; Muñoz, J. A. E-mail: veronica.motta@uv.cl E-mail: falco@cfa.harvard.edu E-mail: jmunoz@uv.es

    2014-12-10

    We use spectra of the double-lensed quasars HE0047–1756 and SDSS1155+6346 to study their unresolved structure through the impact of microlensing. There is no significant evidence of microlensing in the emission line profiles except for the Lyα line of SDSS1155+6346, which shows strong differences in the shapes for images A and B. However, the continuum of the B image spectrum in SDSS1155+6346 is strongly contaminated by the lens galaxy, and these differences should be considered with caution. Using the flux ratios of the emission lines for image pairs as a baseline to remove macro-magnification and extinction, we have detected strong chromatic microlensing in the continuum measured by CASTLES (www.cfa.harvard.edu/castles/) in both lens systems, with amplitudes 0.09(λ16000) ≲ |Δm| ≲ 0.8(λ5439) for HE0047–1756, and 0.2(λ16000) ≲ |Δm| ≲ 0.8(λ5439) for SDSS1155+6346. Using magnification maps to simulate microlensing and modeling the accretion disk as a Gaussian source (I ∝ exp(–R {sup 2}/2r {sub s}{sup 2})) of size r {sub s} ∝ λ {sup p}, we find r {sub s} = 2.5{sub −1.4}{sup +3.0} √(M/0.3M{sub ⊙}) lt-day and p = 2.3 ± 0.8 at the rest frame for λ = 2045 for HE0047–1756 (log prior) and r {sub s} = 5.5{sub −3.3}{sup +8.2} √(M/0.3M{sub ⊙}) lt-day and p = 1.5 ± 0.6 at the rest frame of λ = 1398 for SDSS1155+6346 (log prior). Contrary to other studied lens systems, the chromaticity detected in HE0047–1756 and SDSS1155+6346 is large enough to fulfill the thin disk prediction. The inferred sizes, however, are very large compared to the predictions of this model, especially in the case of SDSS1155+6346.

  13. Design of binary diffractive microlenses with subwavelength structures using the genetic algorithm.

    PubMed

    Shirakawa, Tatsuya; Ishikawa, Kenichi L; Suzuki, Shuichi; Yamada, Yasufumi; Takahashi, Hiroyuki

    2010-04-12

    We present a method to design binary diffractive microlenses with subwavelength structures, based on the finite-difference time-domain method and the genetic algorithm, also accounting for limitations on feature size and aspect ratio imposed by fabrication. The focusing efficiency of the microlens designed by this method is close to that of the convex lens and much higher than that of the binary Fresnel lens designed by a previous method. Although the optimized structure appears to be a binary Fresnel lens qualitatively, it is hard to quantitatively derive directly from the convex Fresnel lens. The design of a microlens with reduced chromatic aberration is also presented.

  14. ALGORITHMS AND PROGRAMS FOR STRONG GRAVITATIONAL LENSING IN KERR SPACE-TIME INCLUDING POLARIZATION

    SciTech Connect

    Chen, Bin; Maddumage, Prasad; Kantowski, Ronald; Dai, Xinyu; Baron, Eddie

    2015-05-15

    Active galactic nuclei (AGNs) and quasars are important astrophysical objects to understand. Recently, microlensing observations have constrained the size of the quasar X-ray emission region to be of the order of 10 gravitational radii of the central supermassive black hole. For distances within a few gravitational radii, light paths are strongly bent by the strong gravity field of the central black hole. If the central black hole has nonzero angular momentum (spin), then a photon’s polarization plane will be rotated by the gravitational Faraday effect. The observed X-ray flux and polarization will then be influenced significantly by the strong gravity field near the source. Consequently, linear gravitational lensing theory is inadequate for such extreme circumstances. We present simple algorithms computing the strong lensing effects of Kerr black holes, including the effects on polarization. Our algorithms are realized in a program “KERTAP” in two versions: MATLAB and Python. The key ingredients of KERTAP are a graphic user interface, a backward ray-tracing algorithm, a polarization propagator dealing with gravitational Faraday rotation, and algorithms computing observables such as flux magnification and polarization angles. Our algorithms can be easily realized in other programming languages such as FORTRAN, C, and C++. The MATLAB version of KERTAP is parallelized using the MATLAB Parallel Computing Toolbox and the Distributed Computing Server. The Python code was sped up using Cython and supports full implementation of MPI using the “mpi4py” package. As an example, we investigate the inclination angle dependence of the observed polarization and the strong lensing magnification of AGN X-ray emission. We conclude that it is possible to perform complex numerical-relativity related computations using interpreted languages such as MATLAB and Python.

  15. Algorithms and Programs for Strong Gravitational Lensing In Kerr Space-time Including Polarization

    NASA Astrophysics Data System (ADS)

    Chen, Bin; Kantowski, Ronald; Dai, Xinyu; Baron, Eddie; Maddumage, Prasad

    2015-05-01

    Active galactic nuclei (AGNs) and quasars are important astrophysical objects to understand. Recently, microlensing observations have constrained the size of the quasar X-ray emission region to be of the order of 10 gravitational radii of the central supermassive black hole. For distances within a few gravitational radii, light paths are strongly bent by the strong gravity field of the central black hole. If the central black hole has nonzero angular momentum (spin), then a photon’s polarization plane will be rotated by the gravitational Faraday effect. The observed X-ray flux and polarization will then be influenced significantly by the strong gravity field near the source. Consequently, linear gravitational lensing theory is inadequate for such extreme circumstances. We present simple algorithms computing the strong lensing effects of Kerr black holes, including the effects on polarization. Our algorithms are realized in a program “KERTAP” in two versions: MATLAB and Python. The key ingredients of KERTAP are a graphic user interface, a backward ray-tracing algorithm, a polarization propagator dealing with gravitational Faraday rotation, and algorithms computing observables such as flux magnification and polarization angles. Our algorithms can be easily realized in other programming languages such as FORTRAN, C, and C++. The MATLAB version of KERTAP is parallelized using the MATLAB Parallel Computing Toolbox and the Distributed Computing Server. The Python code was sped up using Cython and supports full implementation of MPI using the “mpi4py” package. As an example, we investigate the inclination angle dependence of the observed polarization and the strong lensing magnification of AGN X-ray emission. We conclude that it is possible to perform complex numerical-relativity related computations using interpreted languages such as MATLAB and Python.

  16. Methodological studies on the search for Gravitational Waves and Neutrinos from Type II Supernovae

    NASA Astrophysics Data System (ADS)

    Casentini, Claudio

    2016-02-01

    Type II SNe, also called Core-collapse SuperNovae have a neutrino (v) emission, as confirmed by SN 1987A, and are also potential sources of gravitational waves. Neutrinos and gravitational waves from these sources reach Earth almost contemporaneously and without relevant interaction with stellar matter and interstellar medium. The upcoming advanced gravitational interferometers would be sensitive enough to detect gravitational waves signals from close galactic Core-collapse SuperNovae events. Nevertheless, significant uncertainties on theoretical models of emission remain. A joint search of coincident low energy neutrinos and gravitational waves events from these sources would bring valuable information from the inner core of the collapsing star and would enhance the detection of the so-called Silent SuperNovae. Recently a project for a joint search involving gravitational wave interferometers and neutrino detectors has started. We discuss the benefits of a joint search and the status of the search project.

  17. Spacetime Symphony: APOD and Gravitational Waves

    NASA Astrophysics Data System (ADS)

    Cominsky, Lynn R.; Simonnet, Aurore; LIGO-Virgo Scientific Collaboration

    2017-01-01

    In 1915, Albert Einstein published his General Theory of Relativity. In this theory, gravity is not a force, but a property of space and time in the presence of massive objects. A century later, on September 14, 2015, the Laser Interferometer Gravitational-wave Observatory (LIGO) received the first confirmed gravitational wave signals. Now known as GW150914, the event represents the coalescence of two distant black holes that were previously in mutual orbit. The LIGO-Virgo Scientific Collaboration planned a detailed social media strategy to publicize the February 11, 2016 press conference that announced this discovery. Astronomy Picture of the Day (APOD) was a major factor in disseminating the now iconic imagery that was developed, and the LVC worked closely with APOD to ensure that the secrecy would be maintained throughout the press embargo period. Due to the success of our efforts, we repeated the process for the AAS press conference that announced GW151226, the second confirmed gravitational wave event. We have also repurposed the APOD imagery for an online course for community college instructors, as well as in a poster that will be available through CPEPphysics.org (Contemporary Physics Education Project).

  18. Breaking a dark degeneracy with gravitational waves

    SciTech Connect

    Lombriser, Lucas; Taylor, Andy E-mail: ant@roe.ac.uk

    2016-03-01

    We identify a scalar-tensor model embedded in the Horndeski action whose cosmological background and linear scalar fluctuations are degenerate with the concordance cosmology. The model admits a self-accelerated background expansion at late times that is stable against perturbations with a sound speed attributed to the new field that is equal to the speed of light. While degenerate in scalar fluctuations, self-acceleration of the model implies a present cosmological tensor mode propagation at ∼<95 % of the speed of light with a damping of the wave amplitude that is ∼>5 % less efficient than in general relativity. We show that these discrepancies are endemic to self-accelerated Horndeski theories with degenerate large-scale structure and are tested with measurements of gravitational waves emitted by events at cosmological distances. Hence, gravitational-wave cosmology breaks the dark degeneracy in observations of the large-scale structure between two fundamentally different explanations of cosmic acceleration—a cosmological constant and a scalar-tensor modification of gravity. The gravitational wave event GW150914 recently detected with the aLIGO instruments and its potential association with a weak short gamma-ray burst observed with the Fermi GBM experiment may have provided this crucial measurement.

  19. Modeling Gravitational Radiation Waveforms from Black Hole Mergers

    NASA Technical Reports Server (NTRS)

    Baker, J. G.; Centrelia, J. M.; Choi, D.; Koppitz, M.; VanMeter, J.

    2006-01-01

    Gravitational radiation from merging binary black hole systems is anticipated as a key source for gravitational wave observations. Ground-based instruments, such as the Laser Interferometer Gravitational-wave Observatory (LIGO) may observe mergers of stellar-scale black holes, while the space-based Laser Interferometer Space Antenna (LISA) observatory will be sensitive to mergers of massive galactic-center black holes over a broad range of mass scales. These cataclysmic events may emit an enormous amount of energy in a brief time. Gravitational waves from comparable mass mergers carry away a few percent of the system's mass-energy in just a few wave cycles, with peak gravitational wave luminosities on the order of 10^23 L_Sun. Optimal analysis and interpretation of merger observation data will depend on developing a detailed understanding, based on general relativistic modeling, of the radiation waveforms. We discuss recent progress in modeling radiation from equal mass mergers using numerical simulations of Einstein's gravitational field equations, known as numerical relativity. Our simulations utilize Adaptive Mesh Refinement (AMR) to allow high-resolution near the black holes while simultaneously keeping the outer boundary of the computational domain far from the black holes, and making it possible to read out gravitational radiation waveforms in the weak-field wave zone. We discuss the results from simulations beginning with the black holes orbiting near the system's innermost stable orbit, comparing the recent simulations with earlier "Lazarus" waveform estimates based on an approximate hybrid numerical/perturbative technique.

  20. Gravitational wave astronomy.

    NASA Astrophysics Data System (ADS)

    Finn, L. S.

    Astronomers rely on a multiplicity of observational perspectives in order to infer the nature of the Universe. Progress in astronomy has historically been associated with new or improved observational perspectives. Gravitational wave detectors now under construction will provide us with a perspective on the Universe fundamentally different from any we have come to know. With this new perspective comes the hope of new insights and understanding, not just of exotic astrophysical processes, but of "bread-and-butter" astrophysics: e.g., stars and stellar evolution, galaxy formation and evolution, neutron star structure, and cosmology. In this report the author discusses briefly a small subset of the areas of conventional, "bread-and-butter" astrophysics where we can reasonably hope that gravitational wave observations will provide us with valuable new insights and understandings.

  1. Self-gravitating skyrmions

    NASA Astrophysics Data System (ADS)

    Ayón-Beato, Eloy; Canfora, Fabrizio; Zanelli, Jorge

    2016-05-01

    A self-gravitating Skyrmion is an analytic and globally regular solution of the Einstein-Skyrme system with nonvanishing topological charge. The spacetime is the direct product R × S3 and the Skyrmion is the self-gravitating generalization of the static hedgehog solution of Manton and Ruback. This solution can be promoted to a dynamical one in which the spacetime is a cosmology of the Bianchi type-IX and, through an analytic continuation, it can also be turned into a transversable asymptotically AdS Lorentzian wormhole. The stress-energy of this wormhole satisfies physically realistic energy conditions and the only “exotic matter” required by it is a negative cosmological constant.

  2. Gravitational properties of antimatter

    SciTech Connect

    Goldman, T.; Nieto, M.M.

    1985-01-01

    Quantum gravity is at the forefront of modern particle physics, yet there are no direct tests, for antimatter, of even the principle of equivalence. We note that modern descriptions of gravity, such as fibre bundles and higher dimensional spacetimes, allow violations of the commonly stated form of the principle of equivalence, and of CPT. We review both indirect arguments and experimental tests of the expected gravitational properties of CPT-conjugate states. We conclude that a direct experimental test of the gravitational properties of antimatter, at the 1% (or better) level, would be of great value. We identify some experimental reasons which make the antiproton a prime candidate for this test, and we strongly urge that such an experiment be done at LEAR. 21 references.

  3. A gravitational puzzle.

    PubMed

    Caldwell, Robert R

    2011-12-28

    The challenge to understand the physical origin of the cosmic acceleration is framed as a problem of gravitation. Specifically, does the relationship between stress-energy and space-time curvature differ on large scales from the predictions of general relativity. In this article, we describe efforts to model and test a generalized relationship between the matter and the metric using cosmological observations. Late-time tracers of large-scale structure, including the cosmic microwave background, weak gravitational lensing, and clustering are shown to provide good tests of the proposed solution. Current data are very close to proving a critical test, leaving only a small window in parameter space in the case that the generalized relationship is scale free above galactic scales.

  4. Gravitationally induced quantum transitions

    NASA Astrophysics Data System (ADS)

    Landry, A.; Paranjape, M. B.

    2016-06-01

    In this paper, we calculate the probability for resonantly inducing transitions in quantum states due to time-dependent gravitational perturbations. Contrary to common wisdom, the probability of inducing transitions is not infinitesimally small. We consider a system of ultracold neutrons, which are organized according to the energy levels of the Schrödinger equation in the presence of the Earth's gravitational field. Transitions between energy levels are induced by an oscillating driving force of frequency ω . The driving force is created by oscillating a macroscopic mass in the neighborhood of the system of neutrons. The neutron lifetime is approximately 880 sec while the probability of transitions increases as t2. Hence, the optimal strategy is to drive the system for two lifetimes. The transition amplitude then is of the order of 1.06 ×10-5, and hence with a million ultracold neutrons, one should be able to observe transitions.

  5. The gravitational wave experiment

    NASA Technical Reports Server (NTRS)

    Bertotti, B.; Ambrosini, R.; Asmar, S. W.; Brenkle, J. P.; Comoretto, G.; Giampieri, G.; Less, L.; Messeri, A.; Wahlquist, H. D.

    1992-01-01

    Since the optimum size of a gravitational wave detector is the wave length, interplanetary dimensions are needed for the mHz band of interest. Doppler tracking of Ulysses will provide the most sensitive attempt to date at the detection of gravitational waves in the low frequency band. The driving noise source is the fluctuations in the refractive index of interplanetary plasma. This dictates the timing of the experiment to be near solar opposition and sets the target accuracy for the fractional frequency change at 3.0 x 10 exp -14 for integration times of the order of 1000 sec. The instrumentation utilized by the experiment is distributed between the radio systems on the spacecraft and the seven participating ground stations of the Deep Space Network and Medicina. Preliminary analysis is available of the measurements taken during the Ulysses first opposition test.

  6. Undulator Gravitational Deflection

    SciTech Connect

    Bowden, G.

    2005-01-31

    This note estimates distortions imposed by gravity on LCLS undulator strong-backs. Because of the strongback's asymmetric cross section, gravitational forces cause both torsion as well as simple bending. The superposition of these two effects yields a 4.4 {micro}m maximum deflection and a 0.16 milli radian rotation of the undulator axis. The choice of titanium is compared to aluminum.

  7. Gravitational Repulsion of Photons

    NASA Astrophysics Data System (ADS)

    Brynjolfsson, Ari

    2012-03-01

    Plasma redshift explains the cosmological redshift, the redshift of stars and galaxies, the cosmic microwave background, the cosmic X-ray background, the observed redshift relation for magnitude and surface-brightness for supernovae, the solar redshift, the transition zone for the solar corona, the high temperatures of the solar corona. Plasma redshift makes it clear that the optical solar lines are not gravitationally redshifted when observed on Earth. Instead their gravitational redshifts in the Sun are reversed, as the photons travel from the Sun to the Earth. This means that the photons are repelled and not attracted by the gravitational field. There is, therefore, no need for Einstein's Lambda for explaining the static Universe. When the matter concentrates and falls towards the center of galaxies, it becomes so hot that it disintegrates matter to reform primordial like matter. In this way the universe can renew itself forever. This is all based on conventional physics, using only more accurate physics and calculations than those usually used. There is no need for Dark Energy, Dark Matter, Accelerated Expansion, nor Black Holes for explaining the everlasting Universe.

  8. Retarded gravitation theory

    NASA Astrophysics Data System (ADS)

    Raju, C. K.

    2012-10-01

    We propose a Lorentz-covariant theory of gravity, and explain its theoretical origins in the problem of time in Newtonian physics. In this retarded gravitation theory (RGT), the gravitational force depends upon both retarded position and velocity, and the equations of motion are time-asymmetric retarded functional differential equations. We explicitly solve these equations, under simplifying assumptions, for various NASA spacecraft. This shows that the differences from Newtonian gravity, though tiny within the solar system, are just appropriate to explain the flyby anomaly as a ν/c effect due to earth's rotation. The differences can, however, be large in the case of a spiral galaxy, and we show that the combined velocity drag from a large number of co-rotating stars enormously speeds up a test particle. Thus, the non-Newtonian behaviour of rotation curves in a spiral galaxy may be explained as being due to velocity drag rather than dark matter. RGT can also be tested in the laboratory. It necessitates a reappraisal of current laboratory methods of determining the Newtonian gravitational constant G. Since RGT makes no speculative assumptions, its refutation would have serious implications across physics.

  9. Fermions and gravitational gyrotropy

    NASA Astrophysics Data System (ADS)

    Helfer, Adam D.

    2016-12-01

    In conventional general relativity without torsion, high-frequency gravitational waves couple to the chiral number density of spin one-half quanta: the polarization of the waves is rotated by 2 π N5ℓPl2, where N5 is the chiral column density and ℓPl is the Planck length. This means that if a primordial distribution of gravitational waves with E-E or B-B correlations passed through a chiral density of fermions in the very early Universe, an E-B correlation will be generated. This in turn will give rise to E-B and T-B correlations in the cosmic microwave background (CMB). Less obviously but more primitively, the condition Albrecht called "cosmic coherence" would be violated, changing the restrictions on the class of admissible cosmological gravitational waves. This altered class of waves would, generally speaking, probe earlier physics than do the conventional waves; their effects on the CMB would be most pronounced for low (≲100 ) multipoles. Rough estimates indicate that if the tensor-to-scalar ratio is less than about 10-2, it will be hard to constrain a spatially homogeneous primordial N5 by present data.

  10. Some problems of the theory of gravitation

    NASA Astrophysics Data System (ADS)

    Verozub, Leonid

    Leonid Verozub, lverozub@gmail.com Kharkov National University, Kharkov, Ukraine The contemporary observations pose serious challenges to the fundamental physics and astro-physics. We proceed from the equations of gravitation, based on an examination of foundations of the theory. (Ann. Phys. (Leipzig) 17, No. 1, 28 -51 (2008)). Namely, these equations are based on going back to Poincare's ideas about the relativity of geometry of space and time to the properties of measuring instruments, and on the consideration of the geodesic invariance as gauge invariance in the theory of gravitation. These equations do not contradict the observa-tional data, however, lead to two unexpected consequences, which allow you to test the theory: 1. They predict the existence of super-massive compact objects without event horizons, which are an alternative to black holes in the centers of galaxies. 2. They provide a simple and natural explanation for the accelerating expansion of the universe.

  11. Multimessenger time delays from lensed gravitational waves

    NASA Astrophysics Data System (ADS)

    Baker, Tessa; Trodden, Mark

    2017-03-01

    We investigate the potential of high-energy astrophysical events, from which both massless and massive signals are detected, to probe fundamental physics. In particular, we consider how strong gravitational lensing can induce time delays in multimessenger signals from the same source. Obvious messenger examples are massless photons and gravitational waves, and massive neutrinos, although more exotic applications can also be imagined, such as to massive gravitons or axions. The different propagation times of the massive and massless particles can, in principle, place bounds on the total neutrino mass and probe cosmological parameters. Whilst measuring such an effect may pose a significant experimental challenge, we believe that the "massive time delay" represents an unexplored fundamental physics phenomenon.

  12. The potential for very high-frequency gravitational wave detection

    NASA Astrophysics Data System (ADS)

    Cruise, A. M.

    2012-05-01

    The science case for observing gravitational waves at frequencies in the millihertz-kilohertz range using LIGO, VIRGO, GEO600 or LISA is very strong and the first results are expected at these frequencies. However, as gravitational wave astronomy progresses beyond the first detections, other frequency bands may be worth exploring. Early predictions of gravitational wave emission from discrete sources at very much higher frequencies (megahertz and above) have been published and more recent studies of cosmological signals from inflation, Kaluza-Klein modes from gravitational interactions in brane worlds and plasma instabilities surrounding violent astrophysical events, are all possible sources. This communication examines current observational possibilities and the detector technology required to make meaningful observations at these frequencies.

  13. Gravitational-Wave Detectors: First, Second, and Third Generation

    SciTech Connect

    Mandic, Vuk

    2011-11-02

    Gravitational waves are predicted by the general theory of relativity to be produced by accelerating mass systems with quadrupole (or higher) moment. The amplitude of gravitational waves is expected to be very small, so the best chance of their direct detection lies with some of the most energetic events in the universe, such as mergers of two neutron stars or black holes, supernova explosions, or the Big Bang itself. Over the past decade several detectors have been built to search for such gravitational-wave sources. This talk will review the current status of these detectors, as well as some of their most recent results, and will cover plans and expectations for the future generations of gravitational wave detectors.

  14. Speeding up low-mass planetary microlensing simulations and modeling: The caustic region of influence

    SciTech Connect

    Penny, Matthew T.

    2014-08-01

    Extensive simulations of planetary microlensing are necessary both before and after a survey is conducted: before to design and optimize the survey and after to understand its detection efficiency. The major bottleneck in such computations is the computation of light curves. However, for low-mass planets, most of these computations are wasteful, as most light curves do not contain detectable planetary signatures. In this paper, I develop a parameterization of the binary microlens that is conducive to avoiding light curve computations. I empirically find analytic expressions describing the limits of the parameter space that contain the vast majority of low-mass planet detections. Through a large-scale simulation, I measure the (in)completeness of the parameterization and the speed-up it is possible to achieve. For Earth-mass planets in a wide range of orbits, it is possible to speed up simulations by a factor of ∼30-125 (depending on the survey's annual duty-cycle) at the cost of missing ∼1% of detections (which is actually a smaller loss than for the arbitrary parameter limits typically applied in microlensing simulations). The benefits of the parameterization probably outweigh the costs for planets below 100 M{sub ⊕}. For planets at the sensitivity limit of AFTA-WFIRST, simulation speed-ups of a factor ∼1000 or more are possible.

  15. Study of dynamical formation and shape of microlenses formed by the reflow method

    NASA Astrophysics Data System (ADS)

    Audran, S.; Faure, B.; Mortini, B.; Aumont, C.; Tiron, R.; Zinck, C.; Sanchez, Y.; Fellous, C.; Regolini, J.; Reynard, J. P.; Schlatter, G.; Hadziioannou, G.

    2006-03-01

    Microlenses arrays are commonly used in CMOS images sensors to focus the incident light onto the photosensitive area of the pixel. These microlenses are fabricated using a thermal reflow method. Currently, due to the fast evolution of CMOS Imager technology, the understanding of the mechanisms involved in microlens formation becomes essential to better control what occurs during the process. We have seen in a previous study that the complexity of the reflow method comes from the competition between two phenomena occurring during the melt bake step: on one hand the surface tension tends to push the resist patterns into a spherical shape, on the other hand the resist crosslinking reaction drastically increases the resist viscosity hindering the microlens formation. In this paper the influence of resist crosslinking, resist volume and resist/substrate interface on the final shape of the microlens has been investigated. It appears that the contact angle between microlens and substrate varies depending on substrate wettability but is the same whatever the resist volume for a given substrate/resist combination. The microlens shape depends also significantly on bake temperature and crosslinking kinetics. In fact the right tuning of process conditions seems to be the key parameter in the control of the final microlens shape because it enables to adjust the kinetics of each mechanism and thus favour the microlens formation with regards to resist crosslinking.

  16. Capillary-assisted fabrication of biconcave polymeric microlenses from microfluidic ternary emulsion droplets.

    PubMed

    Nisisako, Takasi; Ando, Takuya; Hatsuzawa, Takeshi

    2014-12-29

    In this study, a simple capillary-based approach for producing biconcave polymeric microlenses with uniform size and shape from ternary emulsion droplets is presented. Monodisperse ternary emulsion droplets (0.6-4.0 nL) are produced which contain a photocurable segment of an acrylate monomer and two non-curable segments of silicone oil (SO) by using a microfluidic sheath-flowing droplet generator on a glass chip. The curvature radius of the interfaces separating the droplet segments, as well as the droplet size, and production rate can be flexibly varied by changing the flow conditions of the organic and aqueous phases. Subsequently, off-chip suspension photopolymerization yields non-spherical polymeric microparticles with two spherical concave surfaces templated by two SO segments at random positions. By ultraviolet light irradiation of ternary droplets with two SO segments trapped by the interior wall of a cylindrical microcapillary (internal diameter: 130 μm), biconcave microlenses can be produced with two spherical concave surfaces with a common lens axis. The produced lenses are suitable for use as optical diverging lenses.

  17. Microlensed dual-fiber probe for depth-resolved fluorescence measurements

    NASA Astrophysics Data System (ADS)

    Choi, Hae Young; Ryu, Seon Young; Kim, Jae Young; Kim, Geon Hee; Park, Seong Jun; Lee, Byeong Ha; Chang, Ki Soo

    2011-07-01

    We propose and demonstrate a compact microlensed dual-fiber probe that has a good collection efficiency and a high depth-resolution ability for fluorescence measurements. The probe is formed with a conventional fusion splicer creating a common focusing lens on two fibers placed side by side. The collection efficiency of the fabricated probe was evaluated by measuring the fluorescence signal of a fresh ginkgo leaf. It was shown experimentally that the proposed probe could effectively collect the fluorescence signal with a six-fold increase compared to that of a general flat-tipped probe. The beam propagation method was used to design a probe with an optimized working distance and an improved resolving depth. It was found that the working distance depends mainly on the radius of curvature of the lens, whereas the resolving depth is determined by the core diameters of the illumination and collection fibers. The depth-resolved ability of probes with working distances of ~100 μm and 300 μm was validated by using a two-layer tissue phantom. The experimental results demonstrate that the microlensed dual-fiber probe has the potential to facilitate depth-resolved fluorescence detection of epithelial tissue.

  18. Highly indistinguishable photons from deterministic quantum-dot microlenses utilizing three-dimensional in situ electron-beam lithography

    PubMed Central

    Gschrey, M.; Thoma, A.; Schnauber, P.; Seifried, M.; Schmidt, R.; Wohlfeil, B.; Krüger, L.; Schulze, J. -H.; Heindel, T.; Burger, S.; Schmidt, F.; Strittmatter, A.; Rodt, S.; Reitzenstein, S.

    2015-01-01

    The success of advanced quantum communication relies crucially on non-classical light sources emitting single indistinguishable photons at high flux rates and purity. We report on deterministically fabricated microlenses with single quantum dots inside which fulfil these requirements in a flexible and robust quantum device approach. In our concept we combine cathodoluminescence spectroscopy with advanced in situ three-dimensional electron-beam lithography at cryogenic temperatures to pattern monolithic microlenses precisely aligned to pre-selected single quantum dots above a distributed Bragg reflector. We demonstrate that the resulting deterministic quantum-dot microlenses enhance the photon-extraction efficiency to (23±3)%. Furthermore we prove that such microlenses assure close to pure emission of triggered single photons with a high degree of photon indistinguishability up to (80±7)% at saturation. As a unique feature, both single-photon purity and photon indistinguishability are preserved at high excitation power and pulsed excitation, even above saturation of the quantum emitter. PMID:26179766

  19. Speed of Gravitational Waves from Strongly Lensed Gravitational Waves and Electromagnetic Signals.

    PubMed

    Fan, Xi-Long; Liao, Kai; Biesiada, Marek; Piórkowska-Kurpas, Aleksandra; Zhu, Zong-Hong

    2017-03-03

    We propose a new model-independent measurement strategy for the propagation speed of gravitational waves (GWs) based on strongly lensed GWs and their electromagnetic (EM) counterparts. This can be done in two ways: by comparing arrival times of GWs and their EM counterparts and by comparing the time delays between images seen in GWs and their EM counterparts. The lensed GW-EM event is perhaps the best way to identify an EM counterpart. Conceptually, this method does not rely on any specific theory of massive gravitons or modified gravity. Its differential setting (i.e., measuring the difference between time delays in GW and EM domains) makes it robust against lens modeling details (photons and GWs travel in the same lensing potential) and against internal time delays between GW and EM emission acts. It requires, however, that the theory of gravity is metric and predicts gravitational lensing similar to general relativity. We expect that such a test will become possible in the era of third-generation gravitational-wave detectors, when about 10 lensed GW events would be observed each year. The power of this method is mainly limited by the timing accuracy of the EM counterpart, which for kilonovae is around 10^{4}  s. This uncertainty can be suppressed by a factor of ∼10^{10}, if strongly lensed transients of much shorter duration associated with the GW event can be identified. Candidates for such short transients include short γ-ray bursts and fast radio bursts.

  20. Testing the Speed of Gravitational Waves over Cosmological Distances with Strong Gravitational Lensing.

    PubMed

    Collett, Thomas E; Bacon, David

    2017-03-03

    Probing the relative speeds of gravitational waves and light acts as an important test of general relativity and alternative theories of gravity. Measuring the arrival time of gravitational waves (GWs) and electromagnetic (EM) counterparts can be used to measure the relative speeds, but only if the intrinsic time lag between emission of the photons and gravitational waves is well understood. Here we suggest a method that does not make such an assumption, using future strongly lensed GW events and EM counterparts; Biesiada et al. [J. Cosmol. Astropart. Phys.10 (2014) 080JCAPBP1475-751610.1088/1475-7516/2014/10/080] forecast that 50-100 strongly lensed GW events will be observed each year with the Einstein Telescope. A single strongly lensed GW event would produce robust constraints on c_{GW}/c_{γ} at the 10^{-7} level, if a high-energy EM counterpart is observed within the field of view of an observing γ-ray burst monitor.

  1. Speed of Gravitational Waves from Strongly Lensed Gravitational Waves and Electromagnetic Signals

    NASA Astrophysics Data System (ADS)

    Fan, Xi-Long; Liao, Kai; Biesiada, Marek; Piórkowska-Kurpas, Aleksandra; Zhu, Zong-Hong

    2017-03-01

    We propose a new model-independent measurement strategy for the propagation speed of gravitational waves (GWs) based on strongly lensed GWs and their electromagnetic (EM) counterparts. This can be done in two ways: by comparing arrival times of GWs and their EM counterparts and by comparing the time delays between images seen in GWs and their EM counterparts. The lensed GW-EM event is perhaps the best way to identify an EM counterpart. Conceptually, this method does not rely on any specific theory of massive gravitons or modified gravity. Its differential setting (i.e., measuring the difference between time delays in GW and EM domains) makes it robust against lens modeling details (photons and GWs travel in the same lensing potential) and against internal time delays between GW and EM emission acts. It requires, however, that the theory of gravity is metric and predicts gravitational lensing similar to general relativity. We expect that such a test will become possible in the era of third-generation gravitational-wave detectors, when about 10 lensed GW events would be observed each year. The power of this method is mainly limited by the timing accuracy of the EM counterpart, which for kilonovae is around 1 04 s . This uncertainty can be suppressed by a factor of ˜1 010, if strongly lensed transients of much shorter duration associated with the GW event can be identified. Candidates for such short transients include short γ -ray bursts and fast radio bursts.

  2. Quantum Emulation of Gravitational Waves

    PubMed Central

    Fernandez-Corbaton, Ivan; Cirio, Mauro; Büse, Alexander; Lamata, Lucas; Solano, Enrique; Molina-Terriza, Gabriel

    2015-01-01

    Gravitational waves, as predicted by Einstein’s general relativity theory, appear as ripples in the fabric of spacetime traveling at the speed of light. We prove that the propagation of small amplitude gravitational waves in a curved spacetime is equivalent to the propagation of a subspace of electromagnetic states. We use this result to propose the use of entangled photons to emulate the evolution of gravitational waves in curved spacetimes by means of experimental electromagnetic setups featuring metamaterials. PMID:26169801

  3. Mars gravitational field estimation error

    NASA Technical Reports Server (NTRS)

    Compton, H. R.; Daniels, E. F.

    1972-01-01

    The error covariance matrices associated with a weighted least-squares differential correction process have been analyzed for accuracy in determining the gravitational coefficients through degree and order five in the Mars gravitational potential junction. The results are presented in terms of standard deviations for the assumed estimated parameters. The covariance matrices were calculated by assuming Doppler tracking data from a Mars orbiter, a priori statistics for the estimated parameters, and model error uncertainties for tracking-station locations, the Mars ephemeris, the astronomical unit, the Mars gravitational constant (G sub M), and the gravitational coefficients of degrees six and seven. Model errors were treated by using the concept of consider parameters.

  4. Gravitational Physics Research

    NASA Technical Reports Server (NTRS)

    Wu, S. T.

    2000-01-01

    Gravitational physics research at ISPAE is connected with NASA's Relativity Mission (Gravity Probe B (GP-B)) which will perform a test of Einstein's General Relativity Theory. GP-B will measure the geodetic and motional effect predicted by General Relativity Theory with extremely stable and sensitive gyroscopes in an earth orbiting satellite. Both effects cause a very small precession of the gyroscope spin axis. The goal of the GP-B experiment is the measurement of the gyroscope precession with very high precision. GP-B is being developed by a team at Stanford University and is scheduled for launch in the year 2001. The related UAH research is a collaboration with Stanford University and MSFC. This research is focussed primarily on the error analysis and data reduction methods of the experiment but includes other topics concerned with experiment systems and their performance affecting the science measurements. The hydrogen maser is the most accurate and stable clock available. It will be used in future gravitational physics missions to measure relativistic effects such as the second order Doppler effect. The HMC experiment, currently under development at the Smithsonian Astrophysical Observatory (SAO), will test the performance and capability of the hydrogen maser clock for gravitational physics measurements. UAH in collaboration with the SAO science team will study methods to evaluate the behavior and performance of the HMC. The GP-B data analysis developed by the Stanford group involves complicated mathematical operations. This situation led to the idea to investigate alternate and possibly simpler mathematical procedures to extract the GP-B measurements form the data stream. Comparison of different methods would increase the confidence in the selected scheme.

  5. General Relativity and Gravitation

    NASA Astrophysics Data System (ADS)

    Ashtekar, Abhay; Berger, Beverly; Isenberg, James; MacCallum, Malcolm

    2015-07-01

    Part I. Einstein's Triumph: 1. 100 years of general relativity George F. R. Ellis; 2. Was Einstein right? Clifford M. Will; 3. Cosmology David Wands, Misao Sasaki, Eiichiro Komatsu, Roy Maartens and Malcolm A. H. MacCallum; 4. Relativistic astrophysics Peter Schneider, Ramesh Narayan, Jeffrey E. McClintock, Peter Mészáros and Martin J. Rees; Part II. New Window on the Universe: 5. Receiving gravitational waves Beverly K. Berger, Karsten Danzmann, Gabriela Gonzalez, Andrea Lommen, Guido Mueller, Albrecht Rüdiger and William Joseph Weber; 6. Sources of gravitational waves. Theory and observations Alessandra Buonanno and B. S. Sathyaprakash; Part III. Gravity is Geometry, After All: 7. Probing strong field gravity through numerical simulations Frans Pretorius, Matthew W. Choptuik and Luis Lehner; 8. The initial value problem of general relativity and its implications Gregory J. Galloway, Pengzi Miao and Richard Schoen; 9. Global behavior of solutions to Einstein's equations Stefanos Aretakis, James Isenberg, Vincent Moncrief and Igor Rodnianski; Part IV. Beyond Einstein: 10. Quantum fields in curved space-times Stefan Hollands and Robert M. Wald; 11. From general relativity to quantum gravity Abhay Ashtekar, Martin Reuter and Carlo Rovelli; 12. Quantum gravity via unification Henriette Elvang and Gary T. Horowitz.

  6. Gravitating lepton bag model

    SciTech Connect

    Burinskii, A.

    2015-08-15

    The Kerr–Newman (KN) black hole (BH) solution exhibits the external gravitational and electromagnetic field corresponding to that of the Dirac electron. For the large spin/mass ratio, a ≫ m, the BH loses horizons and acquires a naked singular ring creating two-sheeted topology. This space is regularized by the Higgs mechanism of symmetry breaking, leading to an extended particle that has a regular spinning core compatible with the external KN solution. We show that this core has much in common with the known MIT and SLAC bag models, but has the important advantage of being in accordance with the external gravitational and electromagnetic fields of the KN solution. A peculiar two-sheeted structure of Kerr’s gravity provides a framework for the implementation of the Higgs mechanism of symmetry breaking in configuration space in accordance with the concept of the electroweak sector of the Standard Model. Similar to other bag models, the KN bag is flexible and pliant to deformations. For parameters of a spinning electron, the bag takes the shape of a thin rotating disk of the Compton radius, with a ring–string structure and a quark-like singular pole formed at the sharp edge of this disk, indicating that the considered lepton bag forms a single bag–string–quark system.

  7. (abstract) OMEGA: A Gravitational Wave MIDEX Mission

    NASA Technical Reports Server (NTRS)

    Hellings, Ronald W.

    1996-01-01

    Among the low frequency (LF) gravitational wave sources that are of astronomical interest are white dwarf binaries, neutron star binaries, massive black hole binaries, and compact stars spiralling into massive black holes. A mission to detect these sources has been proposed to NASA as a possible member of its low-cost, near-term MIDEX mission series. This mission utilizes six tiny miniprobes in high Earth orbit to produce a sensitive Michelson interferometer with million kilometer arms, yielding a strain sensitivity below 10^{-21} at periods longer than a hundred seconds. At this sensitivity, known binary stars will be seen and plausible unknown massive black hole events will be searched for.

  8. Gravitational Wave Observations can Constrain Gamma-Ray Busrt Models: The Case of GW 150914 - GBM

    NASA Astrophysics Data System (ADS)

    Veres, P.; Preece, R. D.; Goldstein, A.; Meszaros, P.; Burns, E.; Connaughton, V.

    2016-10-01

    Assuming a common origin for the GW150914 gravitational wave and the GW150914-GBM event, we present the implications of joint observations on leading gamma-ray burst models (photospheric, internal- and external shocks).

  9. Gravitational gradient changes following the 2004 December 26 Sumatra-Andaman Earthquake inferred from GRACE

    NASA Astrophysics Data System (ADS)

    Wang, Lei; Shum, C. K.; Jekeli, Christopher

    2012-12-01

    It has been demonstrated that the Gravity Recovery And Climate Experiment (GRACE) spaceborne gravimetry data are capable of observing coseismic gravity changes resulting from great earthquakes, such as the 2004 December 26 Sumatra-Andaman event (Mw 9.1-9.3). Here, we show for the first time that refined deformation signals from the 2004 December 26 Sumatra-Andaman Earthquake (Mw 9.1-9.3) together with the 2005 March 28 Nias earthquake (Mw 8.6) can be revealed by deriving the full gravitational gradient tensor from GRACE monthly gravitational field. The GRACE-inferred coseismic gravitational gradient changes agree well with coseismic slip model predictions. Since the high-frequency contents in gravitational field variation can be amplified by deriving the gravitational gradients, the GRACE-derived coseismic gravitational gradient changes clearly delineate the fault lines, locate significant slips, and better define the extent of the coseismic deformation.

  10. Gravitational Casimir-Polder effect

    NASA Astrophysics Data System (ADS)

    Hu, Jiawei; Yu, Hongwei

    2017-04-01

    The interaction due to quantum gravitational vacuum fluctuations between a gravitationally polarizable object modelled as a two-level system and a gravitational boundary is investigated. This quantum gravitational interaction is found to be position-dependent, which induces a force in close analogy to the Casimir-Polder force in the electromagnetic case. For a Dirichlet boundary, the quantum gravitational potential for the polarizable object in its ground-state is shown to behave like z-5 in the near zone, and z-6 in the far zone, where z is the distance to the boundary. For a concrete example, where a Bose-Einstein condensate is taken as a gravitationally polarizable object, the relative correction to the radius of the BEC caused by fluctuating quantum gravitational waves in vacuum is found to be of order 10-21. Although the correction is far too small to observe in comparison with its electromagnetic counterpart, it is nevertheless of the order of the gravitational strain caused by a recently detected black hole merger on the arms of the LIGO.

  11. The gravitational properties of antimatter

    SciTech Connect

    Goldman, T.; Hughes, R.J.; Nieto, M.M.

    1986-09-01

    It is argued that a determination of the gravitational acceleration of antimatter towards the earth is capable of imposing powerful constraints on modern quantum gravity theories. Theoretical reasons to expect non-Newtonian non-Einsteinian effects of gravitational strength and experimental suggestions of such effects are reviewed. 41 refs. (LEW)

  12. Enhanced light extraction from UV LEDs using spin-on glass microlenses

    NASA Astrophysics Data System (ADS)

    Liu, Chi-Min; Su, Guo-Dung J.

    2016-05-01

    In this paper, we present a cost-effective method for fabricating spin-on glass (SOG) microlens arrays (MLAs) on ultra-violet light-emitting diodes. The SOG MLA is formed using thermal reflow molds and multiple replication processes, which can reduce the cost of the solution process. In this paper, we fabricate SOG MLA of different sizes, where the diameter of each microlens is approximately 50, 100, 150, and 200 μm. In each case, the light extraction efficiency is improved by 21.86%, 14.01%, 10.35%, and 7.31%, respectively. We also discuss the effects of different-shaped SOG microlenses, namely circular, square, and hexagonal. The light extraction efficiency is improved by 7.31%, 9.60%, and 13.80% for the circular, square, and hexagonal SOG MLAs, respectively. By applying an optimized lens pattern, an increase in light extraction efficiency of 21.86% is achieved.

  13. Gravitational Repulsion and Dirac Antimatter

    NASA Astrophysics Data System (ADS)

    Kowitt, Mark E.

    1996-03-01

    Based on an analogy with electron and hole dynamics in semiconductors, Dirac's relativistic electron equation is generalized to include a gravitational interaction using an electromagnetic-type approximation of the gravitational potential. With gravitational and inertial masses decoupled, the equation serves to extend Dirac's deduction of antimatter parameters to include the possibility of gravitational repulsion between matter and antimatter. Consequences for general relativity and related “antigravity” issues are considered, including the nature and gravitational behavior of virtual photons, virtual pairs, and negative-energy particles. Basic cosmological implications of antigravity are explored—in particular, potential contributions to inflation, expansion, and the general absence of detectable antimatter. Experimental and observational tests are noted, and new ones suggested.

  14. Gravitational correction to vacuum polarization

    NASA Astrophysics Data System (ADS)

    Jentschura, U. D.

    2015-02-01

    We consider the gravitational correction to (electronic) vacuum polarization in the presence of a gravitational background field. The Dirac propagators for the virtual fermions are modified to include the leading gravitational correction (potential term) which corresponds to a coordinate-dependent fermion mass. The mass term is assumed to be uniform over a length scale commensurate with the virtual electron-positron pair. The on-mass shell renormalization condition ensures that the gravitational correction vanishes on the mass shell of the photon, i.e., the speed of light is unaffected by the quantum field theoretical loop correction, in full agreement with the equivalence principle. Nontrivial corrections are obtained for off-shell, virtual photons. We compare our findings to other works on generalized Lorentz transformations and combined quantum-electrodynamic gravitational corrections to the speed of light which have recently appeared in the literature.

  15. A NEW CHANNEL FOR DETECTING DARK MATTER SUBSTRUCTURE IN GALAXIES: GRAVITATIONAL LENS TIME DELAYS

    SciTech Connect

    Keeton, Charles R.; Moustakas, Leonidas A.

    2009-07-10

    We show that dark matter substructure in galaxy-scale halos perturbs the time delays between images in strong gravitational lens systems. The variance of the effect depends on the subhalo mass function, scaling as the product of the substructure mass fraction, and a characteristic mass of subhalos (namely (m {sup 2})/(m)). Time delay perturbations therefore complement gravitational lens flux ratio anomalies and astrometric perturbations by measuring a different moment of the subhalo mass function. Unlike flux ratio anomalies, 'time delay millilensing' is unaffected by dust extinction or stellar microlensing in the lens galaxy. Furthermore, we show that time delay ratios are immune to the radial profile degeneracy that usually plagues lens modeling. We lay out a mathematical theory of time delay perturbations and find it to be tractable and attractive. We predict that in 'cusp' lenses with close triplets of images, substructure may change the arrival-time order of the images (compared with smooth models). We discuss the possibility that this effect has already been observed in RX J1131-1231.

  16. Numerical simulation of gravitational lenses

    NASA Astrophysics Data System (ADS)

    Cherniak, Yakov

    Gravitational lens is a massive body or system of bodies with gravitational field that bends directions of light rays propagating nearby. This may cause an observer to see multiple images of a light source, e.g. a star, if there is a gravitational lens between the star and the observer. Light rays that form each individual image may have different distances to travel, which creates time delays between them. In complex gravitational fields generated by the system of stars, analytical calculation of trajectories and light intensities is virtually impossible. Gravitational lens of two massive bodies, one behind another, are able to create four images of a light source. Furthermore, the interaction between the four light beams can form a complicated interference pattern. This article provides a brief theory of light behavior in a gravitational field and describes the algorithm for constructing the trajectories of light rays in a gravitational field, calculating wave fronts and interference pattern of light. If you set gravitational field by any number of transparent and non- transparent objects (stars) and set emitters of radio wave beams, it is possible to calculate the interference pattern in any region of space. The proposed method of calculation can be applied even in the case of the lack of continuity between the position of the emitting stars and position of the resulting image. In this paper we propose methods of optimization, as well as solutions for some problems arising in modeling of gravitational lenses. The simulation of light rays in the sun's gravitational field is taken as an example. Also caustic is constructed for objects with uniform mass distribution.

  17. An Android application for receiving notifications of astrophysical transient events

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Bond, I. A.; Sweatman, W. L.

    2014-10-01

    We describe an application written for the Android platform for receiving real-time notifications of astrophysical transient events. The key feature of our application is the use of message oriented middleware as a message broker, with the messages in VOEvent format. We describe the design features and implementation details of our application. In particular, it was necessary to implement support for the Simple Text Oriented Messaging Protocol (STOMP) to allow communication with the broker. Our application is designed around VOEvent alerts from the Microlensing Observations in Astrophysics (MOA) project, but could easily be adapted for other surveys that issue VOEvent notices of astrophysical transients.

  18. Probing small-scale structure in galaxies with strong gravitational lensing

    NASA Astrophysics Data System (ADS)

    Congdon, Arthur Benjamin

    We use gravitational lensing to study the small-scale distribution of matter in galaxies. First, we examine galaxies and their dark matter halos. Roughly half of all observed four-image quasar lenses have image flux ratios that differ from the values predicted by simple lens potentials. We show that smooth departures from elliptical symmetry fail to explain anomalous radio fluxes, strengthening the case for dark matter substructure. Our results have important implications for the "missing satellites'' problem. We then consider how time delays between lensed images can be used to identify lens galaxies containing small-scale structure. We derive an analytic relation for the time delay between the close pair of images in a "fold'' lens, and perform Monte Carlo simulations to investigate the utility of time delays for probing small- scale structure in realistic lens populations. We compare our numerical predictions with systems that have measured time delays and discover two anomalous lenses. Next, we consider microlensing, where stars in the lens galaxy perturb image magnifications. This is relevant at optical wavelengths, where the size of the lensed source is comparable to the Einstein radius of a typical star. Our simulations of negative-parity images show that raising the fraction of dark matter relative to stars increases image flux variability for small sources, and decreases it for large sources. This suggests that quasar accretion disks and broad-emission-line regions may respond differently to microlensing. We also consider extended sources with a range of ellipticities, which has relevance to a population of inclined accretion disks. Depending on their orientation, more elongated sources lead to more rapid variability, which may complicate the interpretation of microlensing light curves. Finally, we consider prospects for observing strong lensing by the supermassive black hole at the center of the Milky Way, Sgr A*. Assuming a black hole on the million

  19. Bubble collision with gravitation

    SciTech Connect

    Hwang, Dong-il; Lee, Bum-Hoon; Lee, Wonwoo; Yeom, Dong-han E-mail: bhl@sogang.ac.kr E-mail: innocent.yeom@gmail.com

    2012-07-01

    In this paper, we study vacuum bubble collisions with various potentials including gravitation, assuming spherical, planar, and hyperbolic symmetry. We use numerical calculations from double-null formalism. Spherical symmetry can mimic the formation of a black hole via multiple bubble collisions. Planar and especially hyperbolic symmetry describes two bubble collisions. We study both cases, when two true vacuum regions have the same field value or different field values, by varying tensions. For the latter case, we also test symmetric and asymmetric bubble collisions, and see details of causal structures. If the colliding energy is sufficient, then the vacuum can be destabilized, and it is also demonstrated. This double-null formalism can be a complementary approach in the context of bubble collisions.

  20. Gravitational adaptation of animals

    NASA Technical Reports Server (NTRS)

    Smith, A. H.; Burton, R. R.

    1982-01-01

    The effect of gravitational adaptation is studied in a group of five Leghorn cocks which had become physiologically adapted to 2 G after 162 days of centrifugation. After this period of adaptation, they are periodically exposed to a 2 G field, accompanied by five previously unexposed hatch-mates, and the degree of retained acceleration adaptation is estimated from the decrease in lymphocyte frequency after 24 hr at 2 G. Results show that the previously adapted birds exhibit an 84% greater lymphopenia than the unexposed birds, and that the lymphocyte frequency does not decrease to a level below that found at the end of 162 days at 2 G. In addition, the capacity for adaptation to chronic acceleration is found to be highly heritable. An acceleration tolerant strain of birds shows lesser mortality during chronic acceleration, particularly in intermediate fields, although the result of acceleration selection is largely quantitative (a greater number of survivors) rather than qualitative (behavioral or physiological changes).

  1. Atomic and gravitational clocks

    NASA Technical Reports Server (NTRS)

    Canuto, V. M.; Goldman, I.

    1982-01-01

    Atomic and gravitational clocks are governed by the laws of electrodynamics and gravity, respectively. While the strong equivalence principle (SEP) assumes that the two clocks have been synchronous at all times, recent planetary data seem to suggest a possible violation of the SEP. Past analysis of the implications of an SEP violation on different physical phenomena revealed no disagreement. However, these studies assumed that the two different clocks can be consistently constructed within the framework. The concept of scale invariance, and the physical meaning of different systems of units, are now reviewed and the construction of two clocks that do not remain synchronous - whose rates are related by a non-constant function beta sub a - is demonstrated. The cosmological character of beta sub a is also discussed.

  2. Earth Gravitational Model 2020

    NASA Astrophysics Data System (ADS)

    Barnes, D.; Factor, J. K.; Holmes, S. A.; Ingalls, S.; Presicci, M. R.; Beale, J.; Fecher, T.

    2015-12-01

    The National Geospatial-Intelligence Agency [NGA], in conjunction with its U.S. and international partners, has begun preliminary work on its next Earth Gravitational Model, to replace EGM2008. The new 'Earth Gravitational Model 2020' [EGM2020] has an expected public release date of 2020, and will likely retain the same harmonic basis and resolution as EGM2008. As such, EGM2020 will be essentially an ellipsoidal harmonic model up to degree (n) and order (m) 2159, but will be released as a spherical harmonic model to degree 2190 and order 2159. EGM2020 will benefit from new data sources and procedures. Updated satellite gravity information from the GOCE and GRACE mission, will better support the lower harmonics, globally. Multiple new acquisitions (terrestrial, airborne and shipborne) of gravimetric data over specific geographical areas, will provide improved global coverage and resolution over the land, as well as for coastal and some ocean areas. Ongoing accumulation of satellite altimetry data as well as improvements in the treatment of this data, will better define the marine gravity field, most notably in polar and near-coastal regions. NGA and partners are evaluating different approaches for optimally combining the new GOCE/GRACE satellite gravity models with the terrestrial data. These include the latest methods employing a full covariance adjustment. NGA is also working to assess systematically the quality of its entire gravimetry database, towards correcting biases and other egregious errors where possible, and generating improved error models that will inform the final combination with the latest satellite gravity models. Outdated data gridding procedures have been replaced with improved approaches. For EGM2020, NGA intends to extract maximum value from the proprietary data that overlaps geographically with unrestricted data, whilst also making sure to respect and honor its proprietary agreements with its data-sharing partners.

  3. GRB as a counterpart for Gravitational Wave detection in LCGT

    NASA Astrophysics Data System (ADS)

    Kanda, Nobuyuki

    2010-10-01

    Short Gamma-ray burst (GRB) progenitors are considered as merger of compact star binaries which consist of neutron stars or blackholes. These compact star binaries will radiate a strong gravitational wave in their coalescence, and gravitational wave detectors aim to detect them. We studied the chance probability of coincidence between GRB and GW detection in LCGT detector. Due to omni-directional acceptance of GW detectors, about 75% of GRB events which closer than cosmological redshift z<0.1 are expected to confirm by GW detection.

  4. Measurement and modeling of microlenses fabricated on single-photon avalanche diode arrays for fill factor recovery.

    PubMed

    Pavia, Juan Mata; Wolf, Martin; Charbon, Edoardo

    2014-02-24

    Single-photon avalanche diode (SPAD) imagers typically have a relatively low fill factor, i.e. a low proportion of the pixel's surface is light sensitive, due to in-pixel circuitry. We present a microlens array fabricated on a 128×128 single-photon avalanche diode (SPAD) imager to enhance its sensitivity. The benefits and limitations of these light concentrators are studied for low light imaging applications. We present a new simulation software that can be used to simulate microlenses' performance under different conditions and a new non-destructive contact-less method to estimate the height of the microlenses. Results of experiments and simulations are in good agreement, indicating that a gain >10 can be achieved for this particular sensor.

  5. Weight, gravitation, inertia, and tides

    NASA Astrophysics Data System (ADS)

    Pujol, Olivier; Lagoute, Christophe; Pérez, José-Philippe

    2015-11-01

    This paper deals with the factors that influence the weight of an object near the Earth's surface. They are: (1) the Earth's gravitational force, (2) the centrifugal force due to the Earth's diurnal rotation, and (3) tidal forces due to the gravitational field of the Moon and Sun, and other solar system bodies to a lesser extent. Each of these three contributions is discussed and expressions are derived. The relationship between weight and gravitation is thus established in a direct and pedagogical manner readily understandable by undergraduate students. The analysis applies to the Newtonian limit of gravitation. The derivation is based on an experimental (or operational) definition of weight, and it is shown that it coincides with the Earth’s gravitational force modified by diurnal rotation around a polar axis and non-uniformity of external gravitational bodies (tidal term). Two examples illustrate and quantify these modifications, respectively the Eötvös effect and the oceanic tides; tidal forces due to differential gravitation on a spacecraft and an asteroid are also proposed as examples. Considerations about inertia are also given and some comments are made about a widespread, yet confusing, explanation of tides based on a centrifugal force. Finally, the expression of the potential energy of the tide-generating force is established rigorously in the appendix.

  6. Elastomeric inverse moulding and vacuum casting process characterization for the fabrication of arrays of concave refractive microlenses

    NASA Astrophysics Data System (ADS)

    Desmet, L.; Van Overmeire, S.; Van Erps, J.; Ottevaere, H.; Debaes, C.; Thienpont, H.

    2007-01-01

    We present a complete and precise quantitative characterization of the different process steps used in an elastomeric inverse moulding and vacuum casting technique. We use the latter replication technique to fabricate concave replicas from an array of convex thermal reflow microlenses. During the inverse elastomeric moulding we obtain a secondary silicone mould of the original silicone mould in which the master component is embedded. Using vacuum casting, we are then able to cast out of the second mould several optical transparent poly-urethane arrays of concave refractive microlenses. We select ten particular representative microlenses on the original, the silicone moulds and replica sample and quantitatively characterize and statistically compare them during the various fabrication steps. For this purpose, we use several state-of-the-art and ultra-precise characterization tools such as a stereo microscope, a stylus surface profilometer, a non-contact optical profilometer, a Mach-Zehnder interferometer, a Twyman-Green interferometer and an atomic force microscope to compare various microlens parameters such as the lens height, the diameter, the paraxial focal length, the radius of curvature, the Strehl ratio, the peak-to-valley and the root-mean-square wave aberrations and the surface roughness. When appropriate, the microlens parameter under test is measured with several different measuring tools to check for consistency in the measurement data. Although none of the lens samples shows diffraction-limited performance, we prove that the obtained replicated arrays of concave microlenses exhibit sufficiently low surface roughness and sufficiently high lens quality for various imaging applications.

  7. An overview of gravitational physiology

    NASA Technical Reports Server (NTRS)

    Miquel, Jaime; Souza, Kenneth A.

    1991-01-01

    The focus of this review is on the response of humans and animals to the effects of the near weightless condition occurring aboard orbiting spacecraft. Gravity is an omnipresent force that has been a constant part of our lives and of the evolution of all living species. Emphasis is placed on the general mechanisms of adaptation to altered gravitational fields and vectors, i.e., both hypo- and hypergravity. A broad literature review of gravitational biology was conducted and the general state of our knowledge in this area is discussed. The review is specifically targeted at newcomers to the exciting and relatively new area of space and gravitational biology.

  8. Gravitation. [Book on general relativity

    NASA Technical Reports Server (NTRS)

    Misner, C. W.; Thorne, K. S.; Wheeler, J. A.

    1973-01-01

    This textbook on gravitation physics (Einstein's general relativity or geometrodynamics) is designed for a rigorous full-year course at the graduate level. The material is presented in two parallel tracks in an attempt to divide key physical ideas from more complex enrichment material to be selected at the discretion of the reader or teacher. The full book is intended to provide competence relative to the laws of physics in flat space-time, Einstein's geometric framework for physics, applications with pulsars and neutron stars, cosmology, the Schwarzschild geometry and gravitational collapse, gravitational waves, experimental tests of Einstein's theory, and mathematical concepts of differential geometry.

  9. A new AF gravitational instanton

    NASA Astrophysics Data System (ADS)

    Chen, Yu; Teo, Edward

    2011-09-01

    It has long been conjectured that the Euclidean Schwarzschild and Euclidean Kerr instantons are the only non-trivial asymptotically flat (AF) gravitational instantons. In this Letter, we show that this conjecture is false by explicitly constructing a new two-parameter AF gravitational instanton with a U (1) × U (1) isometry group, using the inverse-scattering method. It has Euler number χ = 3 and Hirzebruch signature τ = 1, and its global topology is CP2 with a circle S1 removed appropriately. Various other properties of this gravitational instanton are also discussed.

  10. Short-duration Lensing Events. II. Expectations and Protocols

    NASA Astrophysics Data System (ADS)

    Di Stefano, Rosanne

    2012-08-01

    Ongoing microlensing observations by OGLE and MOA regularly identify lensing events with Einstein diameter crossing time, τ E , of 16 or fewer days. Events with estimated values of τ E of one to two days have been detected. Short-duration events tend to be generated by low-mass lenses or by lenses with high transverse velocities. We compute the expected rates, demonstrate the expected ranges of parameters for lenses of different mass, and develop a protocol for observing and modeling short-duration events. Relatively minor additions to the procedures presently used will increase the rate of planet discovery, and also discover or place limits on the population of high-speed dim stars and stellar remnants in the vicinity of the Sun.

  11. Gravitational Stokes parameters. [for electromagnetic and gravitational radiation in relativity

    NASA Technical Reports Server (NTRS)

    Anile, A. M.; Breuer, R. A.

    1974-01-01

    The electromagnetic and gravitational Stokes parameters are defined in the general theory of relativity. The general-relativistic equation of radiative transfer for polarized radiation is then derived in terms of the Stokes parameters for both high-frequency electromagnetic and gravitational waves. The concept of Stokes parameters is generalized for the most general class of metric theories of gravity, where six (instead of two) independent states of polarization are present.

  12. Grayscale lithography process study applied to zero-gap microlenses for sub-2μm CMOS image sensors

    NASA Astrophysics Data System (ADS)

    Audran, S.; Vaillant, J.; Farys, V.; Hirigoyen, F.; Huss, E.; Mortini, B.; Cowache, C.; Berthier, L.; Mortini, E.; Fantuz, J.; Arnaud, O.; Depoyan, L.; Sundermann, F.; Baron, C.; Reynard, J.-P.

    2010-04-01

    Microlens arrays are used on CMOS image sensors to focus incident light onto the appropriate photodiode and thus improve the device quantum efficiency. As the pixel size shrinks, the fill factor of the sensor (i.e. ratio of the photosensitive area to the total pixel area) decreases and one way to compensate this loss of sensibility is to improve the microlens photon collection efficiency. This can be achieved by developing zero-gap microlens processes. One elegant solution to pattern zero-gap microlenses is to use a grayscale reticle with varying optical densities which locally modulate the UV light intensity, allowing the creation of continuous relief structure in the resist layer after development. Contrary to conventional lithography for which high resist contrast is appreciated to achieve straight resist pattern profiles, grayscale lithography requires smooth resist contrast curve. In this study we demonstrate the efficiency of grayscale lithography to generate sub-2μm diameter microlens with a positive-tone photoresist. We also show that this technique is resist and process (film thickness, development normality and exposure conditions) dependent. Under the best conditions, spherical zero-gap microlenses as well as aspherical and off-axis microlenses, which are impossible to obtain with the conventional reflow method, were obtained with satisfying process latitude.

  13. Strong lensing of gravitational waves as seen by LISA.

    PubMed

    Sereno, M; Sesana, A; Bleuler, A; Jetzer, Ph; Volonteri, M; Begelman, M C

    2010-12-17

    We discuss strong gravitational lensing of gravitational waves from the merging of massive black hole binaries in the context of the LISA mission. Detection of multiple events would provide invaluable information on competing theories of gravity, evolution and formation of structures and, possibly, constraints on H0 and other cosmological parameters. Most of the optical depth for lensing is provided by intervening massive galactic halos, for which wave optics effects are negligible. Probabilities to observe multiple events are sizable for a broad range of formation histories. For the most optimistic models, up to ≲ 4 multiple events with a signal to noise ratio ≳ 8 are expected in a 5-year mission. Chances are significant even for conservative models with either light (≲ 60%) or heavy (≲ 40%) seeds. Because of lensing amplification, some intrinsically too faint signals are brought over threshold (≲ 2 per year).

  14. Gravitational Waves From Supermassive Black Holes

    NASA Astrophysics Data System (ADS)

    di Girolamo, Tristano

    2016-10-01

    In this talk, I will present the first direct detections of gravitational waves from binary stellar-mass black hole mergers during the first observing run of the two detectors of the Advanced Laser Interferometer Gravitational-wave Observatory, which opened the field of gravitational-wave astronomy, and then discuss prospects for observing gravitational waves from supermassive black holes with future detectors.

  15. Gravitation toward Walls among Human Subjects

    ERIC Educational Resources Information Center

    Dabbs, James M., Jr.; Wheeler, Patricia A.

    1976-01-01

    In two studies, college students (N=34) in a classroom corridor who walked near the wall ("gravitators") were contrasted with those who walked near the center ("non-gravitators"). Gravitators were lower than non-gravitators on Autonomy and Defendence and appeared to be less responsive to other persons. (Author)

  16. Resonant mode for gravitational wave detectors based on atom interferometry

    NASA Astrophysics Data System (ADS)

    Graham, Peter W.; Hogan, Jason M.; Kasevich, Mark A.; Rajendran, Surjeet

    2016-11-01

    We describe an atom interferometric gravitational wave detector design that can operate in a resonant mode for increased sensitivity. By oscillating the positions of the atomic wave packets, this resonant detection mode allows for coherently enhanced, narrow-band sensitivity at target frequencies. The proposed detector is flexible and can be rapidly switched between broadband and narrow-band detection modes. For instance, a binary discovered in broadband mode can subsequently be studied further as the inspiral evolves by using a tailored narrow-band detector response. In addition to functioning like a lock-in amplifier for astrophysical events, the enhanced sensitivity of the resonant approach also opens up the possibility of searching for important cosmological signals, including the stochastic gravitational wave background produced by inflation. We give an example of detector parameters which would allow detection of inflationary gravitational waves down to ΩGW˜10-14 for a two-satellite space-based detector.

  17. Gravitational energy sources in Jupiter

    NASA Technical Reports Server (NTRS)

    Flasar, F. M.

    1973-01-01

    Gravitational sources of the intrinsic luminosity of Jupiter are examined in the context of current hydrogen-helium models. When no gravitational separation of matter occurs, the amount of heat which can be released over the remaining lifetime of the planet is necessarily limited by the size of its existing reservoir of thermal energy. This conclusion rests only on the assumption that its interior is relatively cold and degenerate. If gravitational unmixing occurs, the size of the thermal reservoir does not necessarily limit the heat output. If core formation occurs, for example, then the size of the core formed will be a limiting factor. The energy released with the formation of a helium core is computed for Jupiter. A core growth rate, averaged over several billion years, of 20 trillionths of Jupiter's mass per year is required if gravitational separation is to play a significant role in the thermal evolution.

  18. Gravitational scattering of electromagnetic radiation

    NASA Technical Reports Server (NTRS)

    Brooker, J. T.; Janis, A. I.

    1980-01-01

    The scattering of electromagnetic radiation by linearized gravitational fields is studied to second order in a perturbation expansion. The incoming electromagnetic radiation can be of arbitrary multipole structure, and the gravitational fields are also taken to be advanced fields of arbitrary multipole structure. All electromagnetic multipole radiation is found to be scattered by gravitational monopole and time-varying dipole fields. No case has been found, however, in which any electromagnetic multipole radiation is scattered by gravitational fields of quadrupole or higher-order multipole structure. This lack of scattering is established for infinite classes of special cases, and is conjectured to hold in general. The results of the scattering analysis are applied to the case of electromagnetic radiation scattered by a moving mass. It is shown how the mass and velocity may be determined by a knowledge of the incident and scattered radiation.

  19. Relativistic Gravitational Experiments in Space

    NASA Technical Reports Server (NTRS)

    Hellings, Ronald W. (Editor)

    1989-01-01

    The results are summarized of a workshop on future gravitational physics space missions. The purpose of the workshop was to define generic technological requirements for such missions. NASA will use the results to direct its program of advanced technology development.

  20. Gravitational Many-Body Problem

    SciTech Connect

    Makino, J.

    2008-04-29

    In this paper, we briefly review some aspects of the gravitational many-body problem, which is one of the oldest problems in the modern mathematical science. Then we review our GRAPE project to design computers specialized to this problem.

  1. Gravitational Many-Body Problem

    NASA Astrophysics Data System (ADS)

    Makino, J.

    2008-04-01

    In this paper, we briefly review some aspects of the gravitational many-body problem, which is one of the oldest problems in the modern mathematical science. Then we revi