Science.gov

Sample records for gravitational radiation observatory

  1. 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

    The Table of Contents for the full book PDF is as follows: * Foreword * Introduction: The OMNI-1 Workshop and the beginning of the International Gravitational Radiation Observatory * Opening Talks * Gravitational radiation sources for Acoustic Detectors * The scientific and technological benefits of gravitational wave research * Operating Second and Third Generation Resonant-Mass Antennas * Performance of the ALLEGRO detector -- and what our experience tells us about spherical detectors * The Perth Niobium resonant mass antenna with microwave parametric transducer * The gravitational wave detectors EXPLORER and NAUTILUS * Gravitational Waves and Astrophysical Sources for the Next Generation Observatory * What is the velocity of gravitational waves? * Superstring Theory: how it change our ideas about the nature of Gravitation * Statistical approach to the G.W. emission from radio pulsars * Gravitational waves from precessing millisecond pulsars * The production rate of compact binary G.W. sources in elliptical galaxies * On the possibility to detect Gravitational Waves from precessing galactic neutron stars * Gravitational wave output of the head-on collision of two black holes * SN as a powerfull source of gravitational radiation * Long thick cosmic strings radiating gravitational waves and particles * Non-Parallel Electric and Magnetic Fields in a gravitational background, stationary G.W. and gravitons * Exact solutions of gravitational waves * Factorization method for linearized quantum gravity at tree-level. Graviton, photon, electron processes * Signal Detection with Resonant-Mass Antennas * Study of coalescing binaries with spherical gravitational waves detectors * Influence of transducer asymmetries on the isotropic response of a spherical gravitational wave antenna * Performances and preliminary results of the cosmic-ray detector associated with NAUTILUS * Possible transducer configurations for a spherical gravitational wave antenna * Detectability of

  2. Building a Galactic Scale Gravitational Wave Observatory

    NASA Astrophysics Data System (ADS)

    McLaughlin, Maura

    2016-03-01

    Pulsars are rapidly rotating neutron stars with phenomenal rotational stability that can be used as celestial clocks in a variety of fundamental physics experiences. One of these experiments involves using a pulsar timing array of precisely timed millisecond pulsars to detect perturbations due to gravitational waves. The low frequency gravitational waves detectable through pulsar timing will most likely result from an ensemble of supermassive black hole binaries. I will introduce the efforts of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav), a collaboration that monitors over 50 millisecond pulsars with the Green Bank Telescope and the Arecibo Observatory, with a focus on our observation and data analysis methods. I will also describe how NANOGrav has joined international partners through the International Pulsar Timing Array to form a low-frequency gravitational wave detector of unprecedented sensitivity.

  3. Report from the Gravitational Observatory Advisory Team

    NASA Astrophysics Data System (ADS)

    Mueller, Guido; Gravitational Observatory Advisory Team

    2016-03-01

    As a response to the selection of the Gravitational Universe as the science theme for ESA's L3 mission, ESA formed the Gravitational-Wave Observatory Advisory Team (GOAT) to advise ESA on the scientific and technological approach for a gravitational wave observatory. NASA is participating with three US scientists and one NASA observer; JAXA was also invited and participates with one observer. The GOAT looked at a range of mission technologies and designs, discussed their technical readiness with respect to the ESA schedule, recommended technology development activities for selected technologies, and worked with the wider gravitational-wave community to analyze the impact on the science of the various mission designs. The final report is expected to be submitted to ESA early March and I plan to summarize its content.

  4. Space Based Gravitational Wave Observatories (SGOs)

    NASA Technical Reports Server (NTRS)

    Livas, Jeff

    2014-01-01

    Space-based Gravitational-wave Observatories (SGOs) will enable the systematic study of the frequency band from 0.0001 - 1 Hz of gravitational waves, where a rich array of astrophysical sources is expected. ESA has selected The Gravitational Universe as the science theme for the L3 mission opportunity with a nominal launch date in 2034. This will be at a minimum 15 years after ground-based detectors and pulsar timing arrays announce their first detections and at least 18 years after the LISA Pathfinder Mission will have demonstrated key technologies in a dedicated space mission. It is therefore important to develop mission concepts that can take advantage of the momentum in the field and the investment in both technology development and a precision measurement community on a more near-term timescale than the L3 opportunity. This talk will discuss a mission concept based on the LISA baseline that resulted from a recent mission architecture study.

  5. Linked Gravitational Radiation

    NASA Astrophysics Data System (ADS)

    Thompson, Amy; Swearngin, Joseph; Wickes, Alexander; Willem Dalhuisen, Jan; Bouwmeester, Dirk

    2013-04-01

    The electromagnetic knot is a topologically nontrivial solution to the vacuum Maxwell equations with the property that any two field lines belonging to either the electric, magnetic, or Poynting vector fields are closed and linked exactly once [1]. The relationship between the vacuum Maxwell and linearized Einstein equations, as expressed in the form of the spin-N massless field equations, suggests that gravitational radiation possesses analogous topologically nontrivial field configurations. Using twistor methods we find the analogous spin-2 solutions of Petrov types N, D, and III. Aided by the concept of tendex and vortex lines as recently developed for the physical interpretation of solutions in general relativity [2], we investigate the physical properties of these knotted gravitational fields by characterizing the topology of their associated tendex and vortex lines.[4pt] [1] Ranada, A. F. and Trueba, J. L., Mod. Nonlinear Opt. III, 119, 197 (2002).[2] Nichols, D. A., et al., Phys. Rev. D, 84 (2011).

  6. The Science of Gravitational Waves with Space Observatories

    NASA Technical Reports Server (NTRS)

    Thorpe, James Ira

    2013-01-01

    After decades of effort, direct detection of gravitational waves from astrophysical sources is on the horizon. Aside from teaching us about gravity itself, gravitational waves hold immense promise as a tool for general astrophysics. In this talk I will provide an overview of the science enabled by a space-based gravitational wave observatory sensitive in the milli-Hertz frequency band including the nature and evolution of massive black holes and their host galaxies, the demographics of stellar remnant compact objects in the Milky Way, and the behavior of gravity in the strong-field regime. I will also summarize the current status of efforts in the US and Europe to implement a space-based gravitational wave observatory.

  7. The LIGO Gravitational Wave Observatories:. Recent Results and Future Plans

    NASA Astrophysics Data System (ADS)

    Harry, G. M.; Adhikari, R.; Ballmer, S.; Bayer, K.; Betzwieser, J.; Bochner, B.; Burgess, R.; Cadonati, L.; Chatterji, S.; Corbitt, T.; Csatorday, P.; Fritschel, P.; Goda, K.; Hefetz, Y.; Katsavounidis, E.; Lawrence, R.; Macinnis, M.; Marin, A.; Mason, K.; Mavalvala, N.; Mittleman, R.; Ottaway, D. J.; Pratt, M.; Regimbau, T.; Richman, S.; Rollins, J.; Shoemaker, D. H.; Smith, M.; van Putten, M.; Weiss, R.; Aulbert, C.; Berukoff, S. J.; Cutler, C.; Grunewald, S.; Itoh, Y.; Krishnan, B.; Machenschalk, B.; Mohanty, S.; Mukherjee, S.; Naundorf, H.; Papa, M. A.; Schutz, B. F.; Sintes, A. M.; Williams, P. R.; Colacino, C.; Danzmann, K.; Freise, A.; Grote, H.; Heinzel, G.; Kawabe, K.; Kloevekorn, P.; Lück, H.; Mossavi, K.; Nagano, S.; Rüdiger, A.; Schilling, R.; Smith, J. R.; Weidner, A.; Willke, B.; Winkler, W.; Cusack, B. J.; McClelland, D. E.; Scott, S. M.; Searle, A. C.; Drever, R. W. P.; Tinto, M.; Williams, R.; Buonanno, A.; Chen, Y.; Thorne, K. S.; Vallisneri, M.; Abbott, B.; Anderson, S. B.; Araya, M.; Armandula, H.; Asiri, F.; Barish, B. C.; Barnes, M.; Barton, M. A.; Bhawal, B.; Billingsley, G.; Black, E.; Blackburn, K.; Bogue, L.; Bork, R.; Busby, D.; Cardenas, L.; Chandler, A.; Chapsky, J.; Charlton, P.; Coyne, D.; Creighton, T. D.; D'Ambrosio, E.; Desalvo, R.; Ding, H.; Edlund, J.; Ehrens, P.; Etzel, T.; Evans, M.; Farnham, D.; Fine, M.; Gillespie, A.; Grimmett, D.; Hartunian, A.; Heefner, J.; Hoang, P.; Hrynevych, M.; Ivanov, A.; Jones, L.; Jungwirth, D.; Kells, W.; King, C.; King, P.; Kozak, D.; Lazzarini, A.; Lei, M.; Libbrecht, K.; Lindquist, P.; Liu, S.; Logan, J.; Lyons, T. T.; Mageswaran, M.; Mailand, K.; Majid, W.; Mann, F.; Márka, S.; Maros, E.; Mason, J.; Meshkov, S.; Miyakawa, O.; Miyoki, S.; Mours, B.; Nocera, F.; Ouimette, D.; Pedraza, M.; Rao, S. R.; Redding, D.; Regehr, M. W.; Reilly, K. T.; Reithmaier, K.; Robison, L.; Romie, J.; Rose, D.; Russell, P.; Salzman, I.; Sanders, G. H.; Sannibale, V.; Schmidt, V.; Sears, B.; Seel, S.; Shawhan, P.; Sievers, L.; Smith, M. R.; Spero, R.; Sumner, M. C.; Sylvestre, J.; Takamori, A.; Tariq, H.; Taylor, R.; Tilav, S.; Torrie, C.; Tyler, W.; Vass, S.; Wallace, L.; Ware, B.; Webber, D.; Weinstein, A.; Wen, L.; Whitcomb, S. E.; Willems, P. A.; Wilson, A.; Yamamoto, H.; Zhang, L.; Zweizig, J.; Ganezer, K. S.; Babak, S.; Balasubramanian, R.; Churches, D.; Davies, R.; Sathyaprakash, B.; Taylor, I.; Christensen, N.; Ebeling, C.; Flanagan, É.; Nash, T.; Penn, S.; Dhurandar, S.; Nayak, R.; Sengupta, A. S.; Barker, D.; Barker-Patton, C.; Bland-Weaver, B.; Cook, D.; Gray, C.; Guenther, M.; Hindman, N.; Landry, M.; Lubiński, M.; Matherny, O.; Matone, L.; McCarthy, R.; Mendell, G.; Moreno, G.; Myers, J.; Parameswariah, V.; Raab, F.; Radkins, H.; Ryan, K.; Savage, R.; Schwinberg, P.; Sigg, D.; Vorvick, C.; Worden, J.; Abbott, R.; Carter, K.; Coles, M.; Evans, T.; Frolov, V.; Fyffe, M.; Gretarsson, A. M.; Hammond, M.; Hanson, J.; Kern, J.; Khan, A.; Kovalik, J.; Langdale, J.; Lormand, M.; O'Reilly, B.; Overmier, H.; Parameswariah, C.; Riesen, R.; Rizzi, A.; Roddy, S.; Sibley, A.; Stapfer, G.; Traylor, G.; Watts, K.; Wooley, R.; Yakushin, I.; Zucker, M.; Chickarmane, V.; Daw, E.; Giaime, J. A.; González, G.; Hamilton, W. O.; Johnson, W. W.; Wen, S.; Zotov, N.; McHugh, M.; Whelan, J. T.; Walther, H.; Ageev, A.; Bilenko, I. A.; Braginsky, V. B.; Mitrofanov, V. P.; Tokmakov, K. V.; Vyachanin, S. P.; Camp, J. B.; Kawamura, S.; Belczynski, K.; Grandclément, P.; Kalogera, V.; Kim, C.; Nutzman, P.; Olson, T.; Yoshida, S.; Beausoleil, R.; Bullington, A.; Byer, R. L.; Debra, D.; Fejer, M. M.; Gustafson, E.; Hardham, C.; Hennessy, M.; Hua, W.; Lantz, B.; Robertson, N. A.; Saulson, P. R.; Finn, L. S.; Hepler, N.; Owen, B. J.; Rotthoff, E.; Schlaufman, K.; Shapiro, C. A.; Stuver, A.; Summerscales, T.; Sutton, P. J.; Tibbits, M.; Winjum, B. J.; Anderson, W. G.; Díaz, M.; Johnston, W.; Romano, J. D.; Torres, C.; Ugolini, D.; Aufmuth, P.; Brozek, S.; Fallnich, C.; Goßler, S.; Heng, I. S.; Heurs, M.; Kötter, K.; Leonhardt, V.; Malec, M.; Quetschke, V.; Schrempel, M.; Traeger, S.; Weiland, U.; Welling, H.; Zawischa, I.; Ingley, R.; Messenger, C.; Vecchio, A.; Amin, R.; Castiglione, J.; Coldwell, R.; Delker, T.; Klimenko, S.; Mitselmakher, G.; Mueller, G.; Rakhmanov, M.; Reitze, D. H.; Rong, H.; Sazonov, A.; Shu, Q. Z.; Tanner, D. B.; Whiting, B. F.; Wise, S.; Barr, B.; Bennett, R.; Cagnoli, G.; Cantley, C. A.; Casey, M. M.; Crooks, D. R. M.; Dupuis, R. J.; Elliffe, E. J.; Grant, A.; Heptonstall, A.; Hewitson, M.; Hough, J.; Jennrich, O.; Killbourn, S.; Killow, C. J.; McNamara, P.; Newton, G.; Pitkin, M.; Plissi, M.; Robertson, D. I.; Rowan, S.; Skeldon, K.; Sneddon, P.; Strain, K. A.; Ward, H.; Woan, G.; Chin, D.; Gustafson, R.; Riles, K.; Brau, J. E.; Frey, R.; Ito, M.; Leonor, I.

    2006-02-01

    The LIGO interferometers are operating as gravitational wave observatories, with a noise level near an order of magnitude of the goal and the first scientific data recently taken. This data has been analyzed for four different categories of gravitational wave sources; millisecond bursts, inspiralling binary neutron stars, periodic waves from a known pulsar, and stochastic background. Research and development is also underway for the next generation LIGO detector, Advanced LIGO.

  8. 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.

  9. Toward a Space based Gravitational Wave Observatory

    NASA Technical Reports Server (NTRS)

    Stebbins, Robin T.

    2015-01-01

    A space-based GW observatory will produce spectacular science. The LISA mission concept: (a) Long history, (b) Very well-studied, including de-scopes, (c) NASAs Astrophysics Strategic Plan calls for a minority role in ESAs L3 mission opportunity. To that end, NASA is Participating in LPF and ST7 Developing appropriate technology for a LISA-like mission Preparing to seek an endorsement for L3 participation from the 2020 decadal review.

  10. Tidal radiation. [relativistic gravitational effects

    NASA Technical Reports Server (NTRS)

    Mashhoon, B.

    1977-01-01

    The general theory of tides is developed within the framework of Einstein's theory of gravitation. It is based on the concept of Fermi frame and the associated notion of tidal frame along an open curve in spacetime. Following the previous work of the author an approximate scheme for the evaluation of tidal gravitational radiation is presented which is valid for weak gravitational fields. The emission of gravitational radiation from a body in the field of a black hole is discussed, and for some cases of astrophysical interest estimates are given for the contributions of radiation due to center-of-mass motion, purely tidal deformation, and the interference between the center of mass and tidal motions.

  11. LIGO - The Laser Interferometer Gravitational-Wave Observatory

    NASA Technical Reports Server (NTRS)

    Abramovici, Alex; Althouse, William E.; Drever, Ronald W. P.; Gursel, Yekta; Kawamura, Seiji; Raab, Frederick J.; Shoemaker, David; Sievers, Lisa; Spero, Robert E.; Thorne, Kip S.

    1992-01-01

    The goal of the Laser Interferometer Gravitational-Wave Observatory (LIGO) Project is to detect and study astrophysical gravitational waves and use data from them for research in physics and astronomy. LIGO will support studies concerning the nature and nonlinear dynamics for gravity, the structures of black holes, and the equation of state of nuclear matter. It will also measure the masses, birth rates, collisions, and distributions of black holes and neutron stars in the universe and probe the cores of supernovae and the very early universe. The technology for LIGO has been developed during the past 20 years. Construction will begin in 1992, and under the present schedule, LIGO's gravitational-wave searches will begin in 1998.

  12. Gravitating toward Science: Parent-Child Interactions at a Gravitational-Wave Observatory

    ERIC Educational Resources Information Center

    Szechter, Lisa E.; Carey, Elizabeth J.

    2009-01-01

    This research examined the nature of parent-child conversations at an informal science education center housed in an active gravitational-wave observatory. Each of 20 parent-child dyads explored an interactive exhibit hall privately, without the distraction of other visitors. Parents employed a variety of strategies to support their children's…

  13. Possible Space-Based Gravitational-Wave Observatory Mission Concept

    NASA Technical Reports Server (NTRS)

    Livas, Jeffrey C.

    2015-01-01

    The existence of gravitational waves was established by the discovery of the Binary Pulsar PSR 1913+16 by Hulse and Taylor in 1974, for which they were awarded the 1983 Nobel Prize. However, it is the exploitation of these gravitational waves for the extraction of the astrophysical parameters of the sources that will open the first new astronomical window since the development of gamma ray telescopes in the 1970's and enable a new era of discovery and understanding of the Universe. Direct detection is expected in at least two frequency bands from the ground before the end of the decade with Advanced LIGO and Pulsar Timing Arrays. However, many of the most exciting sources will be continuously observable in the band from 0.1-100 mHz, accessible only from space due to seismic noise and gravity gradients in that band that disturb ground-based observatories. This poster will discuss a possible mission concept, Space-based Gravitational-wave Observatory (SGO-Mid) developed from the original Laser Interferometer Space Antenna (LISA) reference mission but updated to reduce risk and cost.

  14. 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.

  15. Charge management for gravitational-wave observatories using UV LEDs

    SciTech Connect

    Pollack, S. E.; Turner, M. D.; Schlamminger, S.; Hagedorn, C. A.; Gundlach, J. H.

    2010-01-15

    Accumulation of electrical charge on the end mirrors of gravitational-wave observatories can become a source of noise limiting the sensitivity of such detectors through electronic couplings to nearby surfaces. Torsion balances provide an ideal means for testing gravitational-wave technologies due to their high sensitivity to small forces. Our torsion pendulum apparatus consists of a movable plate brought near a plate pendulum suspended from a nonconducting quartz fiber. A UV LED located near the pendulum photoejects electrons from the surface, and a UV LED driven electron gun directs photoelectrons towards the pendulum surface. We have demonstrated both charging and discharging of the pendulum with equivalent charging rates of {approx}10{sup 5}e/s, as well as spectral measurements of the pendulum charge resulting in a white noise level equivalent to 3x10{sup 5}e/{radical}(Hz).

  16. Possible Space-Based Gravitational-Wave Observatory Mission Concept

    NASA Astrophysics Data System (ADS)

    Livas, Jeffrey C.

    2015-08-01

    The existence of gravitational waves was established by the discovery of the Binary Pulsar PSR 1913+16 by Hulse and Taylor in 1974, for which they were awarded the 1983 Nobel Prize. However, it is the exploitation of these gravitational waves for the extraction of the astrophysical parameters of the sources that will open the first new astronomical window since the development of gamma ray telescopes in the 1970’s and enable a new era of discovery and understanding of the Universe. Direct detection is expected in at least two frequency bands from the ground before the end of the decade with Advanced LIGO and Pulsar Timing Arrays. However, many of the most exciting sources will be continuously observable in the band from 0.1-100 mHz, accessible only from space due to seismic noise and gravity gradients in that band that disturb ground-based observatories. This talk will discuss a possible mission concept developed from the original Laser Interferometer Space Antenna (LISA) reference mission but updated to reduce risk and cost.

  17. Possible Space-Based Gravitational-Wave Observatory Mission Concept

    NASA Technical Reports Server (NTRS)

    Livas, Jeffrey C.

    2015-01-01

    The existence of gravitational waves was established by the discovery of the Binary Pulsar PSR 1913+16 by Hulse and Taylor in 1974, for which they were awarded the 1983 Nobel Prize. However, it is the exploitation of these gravitational waves for the extraction of the astrophysical parameters of the sources that will open the first new astronomical window since the development of gamma ray telescopes in the 1970's and enable a new era of discovery and understanding of the Universe. Direct detection is expected in at least two frequency bands from the ground before the end of the decade with Advanced LIGO and Pulsar Timing Arrays. However, many of the most exciting sources will be continuously observable in the band from 0.1-100 mHz, accessible only from space due to seismic noise and gravity gradients in that band that disturb groundbased observatories. This talk will discuss a possible mission concept developed from the original Laser Interferometer Space Antenna (LISA) reference mission but updated to reduce risk and cost.

  18. Architectures for a Space-based Gravitational-Wave Observatory

    NASA Astrophysics Data System (ADS)

    Stebbins, Robin

    2015-04-01

    The European Space Agency (ESA) selected the science theme, the ``Gravitational Universe,'' for the third large mission opportunity, known as L3, under its Cosmic Vision Programme. The planned launch date is 2034. ESA is considering a 20% participation by an international partner, and NASA's Astrophysics Division has begun negotiating a NASA role. We have studied the design consequences of a NASA contribution, evaluated the science benefits and identified the technology requirements for hardware that could be delivered by NASA. The European community proposed a strawman mission concept, called eLISA, having two measurement arms, derived from the well studied LISA (Laser Interferometer Space Antenna) concept. The US community is promoting a mission concept known as SGO Mid (Space-based Gravitational-wave Observatory Mid-sized), a three arm LISA-like concept. If NASA were to partner with ESA, the eLISA concept could be transformed to SGO Mid by the addition of a third arm, thereby augmenting science, reducing risk and reducing non-recurring engineering costs. The characteristics of the mission concepts and the relative science performance of eLISA, SGO Mid and LISA are described.

  19. 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.

  20. Constraints on Lorentz violation from gravitational Čerenkov radiation

    NASA Astrophysics Data System (ADS)

    Kostelecký, V. Alan; Tasson, Jay D.

    2015-10-01

    Limits on gravitational Čerenkov radiation by cosmic rays are obtained and used to constrain coefficients for Lorentz violation in the gravity sector associated with operators of even mass dimensions, including orientation-dependent effects. We use existing data from cosmic-ray telescopes to obtain conservative two-sided constraints on 80 distinct Lorentz-violating operators of dimensions four, six, and eight, along with conservative one-sided constraints on three others. Existing limits on the nine minimal operators at dimension four are improved by factors of up to a billion, while 74 of our explicit limits represent stringent first constraints on nonminimal operators. Prospects are discussed for future analyses incorporating effects of Lorentz violation in the matter sector, the role of gravitational Čerenkov radiation by high-energy photons, data from gravitational-wave observatories, the tired-light effect, and electromagnetic Čerenkov radiation by gravitons.

  1. Dipole gravitational radiation in the nonsymmetric gravitational theory of Moffat

    NASA Astrophysics Data System (ADS)

    Krisher, Timothy P.

    1985-07-01

    The generation of gravitational radiation in the nonsymmetric gravitational theory (NGT) of Moffat is analyzed. It is shown that the theory predicts the emission of dipole gravitational radiation from a binary system. The source of the dipole radiation is a vector density S postulated to be proportional to the number density of fermion particles in the components of the system. This radiation is shown to result in a secular decrease in the orbital period of a binary system in addition to that predicted by general relativity. The size of the effect is proportional to the reduced mass of the system and to the square of the difference in l2/[mass] between the two components of the system, where l is a parameter having units of [length] that is related to the number of fermion particles in each component. As part of the analysis, the stress-energy pseudotensor of the NGT, expanded to quadratic order in the gravitational fields, and the NGT gravitational-wave luminosity formula are derived for the first time. With a perfect-fluid model of matter, results are also given for the post-Newtonian expansions of the source densities of the gravitational fields. The results of this analysis are then applied to the binary pulsar system PSR 1913+16 which contains a pulsar orbiting an unobserved companion. With gravitational radiation attributed as the cause of the observed secular decrease in the orbital period, this system provides a test of the prediction by the NGT of dipole gravitational radiation. It is shown that the NGT can only fit the observations of this system provided the l parameter of the unseen companion is <~350 km.

  2. The Observatory for Multi-Epoch Gravitational Lens Astrophysics (OMEGA)

    NASA Astrophysics Data System (ADS)

    Moustakas, Leonidas A.; Bolton, Adam J.; Booth, Jeffrey T.; Bullock, James S.; Cheng, Edward; Coe, Dan; Fassnacht, Christopher D.; Gorjian, Varoujan; Heneghan, Cate; Keeton, Charles R.; Kochanek, Christopher S.; Lawrence, Charles R.; Marshall, Philip J.; Metcalf, R. Benton; Natarajan, Priyamvada; Nikzad, Shouleh; Peterson, Bradley M.; Wambsganss, Joachim

    2008-07-01

    Dark matter in a universe dominated by a cosmological constant seeds the formation of structure and is the scaffolding for galaxy formation. The nature of dark matter remains one of the fundamental unsolved problems in astrophysics and physics even though it represents 85% of the mass in the universe, and nearly one quarter of its total mass-energy budget. The mass function of dark matter "substructure" on sub-galactic scales may be enormously sensitive to the mass and properties of the dark matter particle. On astrophysical scales, especially at cosmological distances, dark matter substructure may only be detected through its gravitational influence on light from distant varying sources. Specifically, these are largely active galactic nuclei (AGN), which are accreting super-massive black holes in the centers of galaxies, some of the most extreme objects ever found. With enough measurements of the flux from AGN at different wavelengths, and their variability over time, the detailed structure around AGN, and even the mass of the super-massive black hole can be measured. The Observatory for Multi-Epoch Gravitational Lens Astrophysics (OMEGA) is a mission concept for a 1.5-m near-UV through near-IR space observatory that will be dedicated to frequent imaging and spectroscopic monitoring of ~100 multiply-imaged active galactic nuclei over the whole sky. Using wavelength-tailored dichroics with extremely high transmittance, efficient imaging in six channels will be done simultaneously during each visit to each target. The separate spectroscopic mode, engaged through a flip-in mirror, uses an image slicer spectrograph. After a period of many visits to all targets, the resulting multidimensional movies can then be analyzed to a) measure the mass function of dark matter substructure; b) measure precise masses of the accreting black holes as well as the structure of their accretion disks and their environments over several decades of physical scale; and c) measure a

  3. LIMITS ON THE STOCHASTIC GRAVITATIONAL WAVE BACKGROUND FROM THE NORTH AMERICAN NANOHERTZ OBSERVATORY FOR GRAVITATIONAL WAVES

    SciTech Connect

    Demorest, P. B.; Ransom, S.; Ferdman, R. D.; Kaspi, V. M.; Gonzalez, M. E.; Stairs, I. H.; Nice, D.; Arzoumanian, Z.; Brazier, A.; Cordes, J. M.; Burke-Spolaor, S.; Lazio, J.; Chamberlin, S. J.; Ellis, J.; Giampanis, S.; Finn, L. S.; Freire, P.; Jenet, F.; Lommen, A. N.; McLaughlin, M.; and others

    2013-01-10

    We present an analysis of high-precision pulsar timing data taken as part of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) project. We have observed 17 pulsars for a span of roughly five years using the Green Bank and Arecibo radio telescopes. We analyze these data using standard pulsar timing models, with the addition of time-variable dispersion measure and frequency-variable pulse shape terms. Sub-microsecond timing residuals are obtained in nearly all cases, and the best rms timing residuals in this set are {approx}30-50 ns. We present methods for analyzing post-fit timing residuals for the presence of a gravitational wave signal with a specified spectral shape. These optimally take into account the timing fluctuation power removed by the model fit, and can be applied to either data from a single pulsar, or to a set of pulsars to detect a correlated signal. We apply these methods to our data set to set an upper limit on the strength of the nHz-frequency stochastic supermassive black hole gravitational wave background of h{sub c} (1 yr{sup -1}) < 7 Multiplication-Sign 10{sup -15} (95%). This result is dominated by the timing of the two best pulsars in the set, PSRs J1713+0747 and J1909-3744.

  4. Gravitational radiation quadrupole formula is valid for gravitationally interacting systems

    NASA Technical Reports Server (NTRS)

    Walker, M.; Will, C. M.

    1980-01-01

    An argument is presented for the validity of the quadrupole formula for gravitational radiation energy loss in the far field of nearly Newtonian (e.g., binary stellar) systems. This argument differs from earlier ones in that it determines beforehand the formal accuracy of approximation required to describe gravitationally self-interacting systems, uses the corresponding approximate equation of motion explicitly, and evaluates the appropriate asymptotic quantities by matching along the correct space-time light cones.

  5. Vision for a Virtual Radiation Belt Observatory

    NASA Astrophysics Data System (ADS)

    Green, J. C.; Baker, D. N.; Kroehl, H. W.; Kihn, E. A.; Fennell, J. F.; Blake, J. B.; Reeves, G. D.; Friedel, R. H.; McGuire, R. E.; Fung, S. F.; Kanekal, S. G.; Mason, G. M.; Rigler, E. J.; Weigel, R. S.; Elkington, , S. R.

    2004-05-01

    Satellite engineers, operators, and scientists now share a common desire to understand the structure and variability of the earth's radiation belts. Continuing upsets to space operations demonstrate a need for improved scientific understanding of the radiation belts, more accurate models, and better transfer of scientific understanding to space technology and operations. Currently, the resources necessary for such advancements are beyond the scope of an individual researcher. Thus, we discuss plans to advance our understanding of the radiation belts and mitigate the hazards they pose to society by creating a Virtual Radiation Belt Observatory (ViRBO). The observatory will be an open access near real time and long term archive of observed and simulated radiation belt model data. It will enable scientists to test theoretical mechanisms proposed to explain how particles are accelerated and removed from the radiation belts and it will provide improved tools for engineers designing satellites and operators assessing satellite malfunctions. The observatory will capitalize on radiation belt modeling efforts currently underway at institutions throughout the country and support the goals of the electronic Geophysical Year (eGY) endorsed by the world wide community.

  6. A low temperature gravitational radiation detector

    NASA Technical Reports Server (NTRS)

    Hamilton, W. O.

    1971-01-01

    The beginning design of an experiment is discussed for studying gravitational radiation by using massive detectors which are cooled to ultralow temperatures in order to improve the signal to noise ratios and the effective range and stability of the detectors. The gravitational detector, a low detection system, a cooled detector, magnetic support, superconducting shielding, and superconducting accelerometer detector are described.

  7. Approximation methods in gravitational-radiation theory

    NASA Technical Reports Server (NTRS)

    Will, C. M.

    1986-01-01

    The observation of gravitational-radiation damping in the binary pulsar PSR 1913 + 16 and the ongoing experimental search for gravitational waves of extraterrestrial origin have made the theory of gravitational radiation an active branch of classical general relativity. In calculations of gravitational radiation, approximation methods play a crucial role. Recent developments are summarized in two areas in which approximations are important: (a) the quadrupole approxiamtion, which determines the energy flux and the radiation reaction forces in weak-field, slow-motion, source-within-the-near-zone systems such as the binary pulsar; and (b) the normal modes of oscillation of black holes, where the Wentzel-Kramers-Brillouin approximation gives accurate estimates of the complex frequencies of the modes.

  8. Compact dark matter objects, asteroseismology, and gravitational waves radiated by sun

    SciTech Connect

    Pokrovsky, Yu. E.

    2015-12-15

    The solar surface oscillations observed by Crimean Astrophysical Observatory and Solar Helioseismic Observatory are considered to be excited by a small fraction of Dark Matter in form of Compact Dark Matter Objects (CDMO) in the solar structure. Gravitational Waves (GW) radiated by these CDMO are predicted to be the strongest at the Earth and are easily detectable by European Laser Interferometer Space Antenna or by Gravitational-Wave Observatory “Dulkyn” which can solve two the most challenging tasks in the modern physics: direct detection of GW and DM.

  9. Gravitational radiation as a test of relativistic gravity

    NASA Technical Reports Server (NTRS)

    Will, Clifford M.

    1989-01-01

    Gravitational radiation can be used to test theories of gravitation. When the waves are ultimately detected directly, their speed and polarization properties can be measured and compared with predictions of alternative theories. The multipole nature of gravitational radiation was already tested in the binary pulsar, where observations of the decay of the orbit verify the quadrupole formula for gravitational radiation damping of general relativity and put strong constraints on dipole gravitational radiation predicted by many alternative theories.

  10. Inhomogeneous cosmology: Gravitational radiation in Bianchi backgrounds

    SciTech Connect

    Adams, P.J.; Hellings, R.W.; Zimmerman, R.L.; Farhoosh, H.; Levine, D.I.; Zeldich, S.

    1982-02-01

    An exact formalism is developed for describing cosmological models with strong, long wavelength gravitational waves of general polarization propagating over backgrounds corresponding to Bianchi types I through VII. We introduce and discuss a new metric which exhibits the appropriate symmetries of two equivalent independent polarizations of gravitational waves. The formalism is applied to an empty type I cosmology, and it is shown how the original z-dependent chaotic singularity structure transforms itself into gravitational radiation propagating along the z-axis in a Bianchi I background.

  11. Inhomogeneous cosmology - Gravitational radiation in Bianchi backgrounds

    NASA Technical Reports Server (NTRS)

    Adams, P. J.; Hellings, R. W.; Zimmerman, R. L.; Farhoosh, H.; Levine, D. I.; Zeldich, S.

    1982-01-01

    An exact formalism is developed for describing cosmological models with strong, long wavelength gravitational waves of general polarization, propagating over backgrounds corresponding to Bianchi types I through VII. A new metric which exhibits the appropriate symmetries of two equivalent independent polarizations of gravitational waves is introduced and discussed. The formalism is applied to an empty type I cosmology, and it is shown how the original z-dependent chaotic singularity structure transforms itself into gravitational radiation propagating along the z-axis in a Bianchi I background.

  12. Gravitational radiation observations on the moon

    SciTech Connect

    Stebbins, R.T. ); Armstrong, J.W. ); Bender, P.L. Quantum Physics Division, National Institute of Standards and Technology ); Drever, R.W.P. ); Hellings, R.W. ); Saulson, P.R. )

    1990-07-05

    A Laser-Interferometer Gravitational-Wave Observatory (LIGO) is planned for operation in the United States, with two antennas separated by several thousand kilometers. Each antenna would incorporate laser interferometers with 4 km arm lengths, operating in vacuum. The frequency range covered initially would be from a few tens of Hz to a few kHz, with possible extension to lower frequencies later. Similar systems are likely to be constructed in Europe, and there is a possibility of at least one system in Asia or Australia. It will be possible to determine the direction to a gravitational wave source by measuring the difference in the arrival times at the various antennas for burst signals or the phase difference for short duration nearly periodic signals. The addition of an antenna on the Moon, operating in support of the Earth-based antennas, would improve the angular resolution for burst signals by about a factor 50 in the plane containing the source, the Moon, and the Earth. This would be of major importance in studies of gravitational wave sources. There is also a possibility of somewhat lower noise at frequencies near 1 Hz for a lunar gravitational wave antenna, because of lower gravity gradient noise and microseismic noise on the Moon. However, for frequencies near 0.1 Hz and below, a 10{sup 7} km laser gravitational wave antenna in solar orbit would be much more sensitive.

  13. The Laser Interferometer Gravitational-Wave Observatory: Lasers at the Frontiers of Astrophysics

    NASA Astrophysics Data System (ADS)

    Reitze, David

    2005-04-01

    The Laser Interferometric Gravitational-Wave Observatory (LIGO) is poised to open a new window on the universe - the detection of gravitational waves from distant large-scale astrophysical sources. Gravitational waves were predicted by Einstein almost 90 years ago but never been observed directly despite a number of experiments over the last 40 years. While there exists strong indirect evidence for gravitational waves, it is only with the construction of large-scale high precision interferometers that direct detection of gravitational waves is possible. Gravitational waves are miniscule dynamic strains applied to space-time by motion of massive astrophysical objects. A passing gravitational wave will expand and contract the distance between two mirrors (`test masses') in the arms of an interferometer. Direct observation of gravitational waves presents a formidable challenge, because the magnitude of the dynamic strain is expected to be infinitesimal, less than one part in 10-22. The astrophysical motivation for detecting gravitational waves is compelling. Unlike the visible sky, the gravitational wave `sky' is completely unexplored. The LIGO detectors and its partner GEO600 in Europe have the sensitivity to observe gravitational waves not only in our own galaxy, but in neighboring galaxies, thus opening an absolutely unique window into these phenomena. In the first part of the presentation, we will give an overview of gravitational waves - what they are and where they come from -- and describe in general terms the techniques that gravitational wave astrophysicists use to hunt for them. In the second part of the presentation, we describe the LIGO interferometers emphasizing the critical role that lasers and optics play in its operation.

  14. Emission of gravitational radiation from ultrarelativistic sources

    NASA Astrophysics Data System (ADS)

    Segalis, Ehud B.; Ori, Amos

    2001-09-01

    Recent observations suggest that blobs of matter are ejected with ultrarelativistic speeds in various astrophysical phenomena such as supernova explosions, quasars, and microquasars. In this paper we analyze the gravitational radiation emitted when such an ultrarelativistic blob is ejected from a massive object. We express the gravitational wave by the metric perturbation in the transverse-traceless gauge, and calculate its amplitude and angular dependence. We find that in the ultrarelativistic limit the gravitational wave has a wide angular distribution, like 1+cos θ. The typical burst's frequency is Doppler shifted, with the blueshift factor being strongly beamed in the forward direction. As a consequence, the energy flux carried by the gravitational radiation is beamed. In the second part of the paper we estimate the anticipated detection rate of such bursts by a gravitational-wave detector, for blobs ejected in supernova explosions. Dar and De Rujula recently proposed that ultrarelativistic blobs ejected from the central core in supernova explosions constitute the source of gamma-ray bursts. Substituting the most likely values of the parameters as suggested by their model, we obtain an estimated detection rate of about 1 per year by the advanced LIGO-II detector.

  15. The generation of gravitational radiation by escaping supernova neutrinos

    NASA Technical Reports Server (NTRS)

    Epstein, R.

    1978-01-01

    Formulae for the gravitational radiation due to the anisotropic axisymmetric emission of neutrinos from a small source are derived. We find that a burst of neutrinos released anisotropically from a supernova will generate a burst of gravitational radiation that may be comparable in amplitude and energy to the gravitational radiation generated by the fluid motion in the collapse of the supernova core.

  16. Radiative processes in external gravitational fields

    SciTech Connect

    Papini, Giorgio

    2010-07-15

    Kinematically forbidden processes may be allowed in the presence of external gravitational fields. These can be taken into account by introducing generalized particle momenta. The corresponding transition probabilities can then be calculated to all orders in the metric deviation from the field-free expressions by simply replacing the particle momenta with their generalized counterparts. The procedure applies to particles of any spin and to any gravitational fields. Transition probabilities, emission power, and spectra are, to leading order, linear in the metric deviation. It is also shown how a small dissipation term in the particle wave equations can trigger a strong backreaction that introduces resonances in the radiative process and deeply affects the resulting gravitational background.

  17. Core Collapse Supernovae Using CHIMERA: Gravitational Radiation from Non-Rotating Progenitors

    SciTech Connect

    Yakunin, Konstantin; Marronetti, Pedro; Mezzacappa, Anthony; Bruenn, S. W.; Lee, Ching-Tsai; Chertkow, Merek A; Hix, William Raphael; Blondin, J. M.; Lentz, Eric J; Messer, Bronson; Yoshida, S.

    2011-01-01

    The CHIMERA code is a multi-dimensional multi-physics engine dedicated primarily to the simulation of core collapse supernova explosions. One of the most important aspects of these explosions is their capacity to produce gravitational radiation that is detectable by earth-based laser-interferometric gravitational wave observatories such as LIGO and VIRGO. We present here preliminary gravitational signatures of two-dimensional models with non-rotating progenitors. These simulations exhibit explosions, which are followed for more than half a second after stellar core bounce.

  18. Gravitational radiation as radiation same level of electromagnetic and its generation in pulsed high-current discharge. Theory and experiment.

    NASA Astrophysics Data System (ADS)

    Fisenko, Stanislav; Fisenko, Igor

    2015-04-01

    The notion of gravitational radiation as a radiation of the same level as the electromagnetic radiation is based on theoretically proved and experimentally confirmed fact of existence of stationary states of an electron in its gravitational field characterized by the gravitational constant K = 1042 G (G is the Newtonian gravitational constant) and unrecoverable space-time curvature Λ. This paper gives an overview of the authors' works, which set out the relevant results. Additionally, data is provided on the broadening of the spectra characteristic radiation. The data show that this broadening can be explained only by the presence of excited states of electrons in their gravitational field. What is more, the interpretation of the new line of X-ray emission spectrum according to the results of observation of MOS-camera of XMM-Newton observatory is of interest. The given work contributes into further elaboration of the findings considering their application to dense high-temperature plasma of multiple-charge ions. This is due to quantitative character of electron gravitational radiation spectrum such that amplification of gravitational radiation may take place only in multiple-charge ion high-temperature plasma.

  19. Progress and Prospects toward a Space-based Gravitational-Wave Observatory

    NASA Technical Reports Server (NTRS)

    Baker, John

    2012-01-01

    Over the last few years there has been much activity in the effort to produce a space-based gravitational-wave observatory. These efforts have enriched the understanding of the scientific capabilities of such an observatory leading to broad recognition of its value as an astronomical instrument. At the same time, rapidly developing events in the US and Europe have lead to a more complicated outlook than the baseline Laser Interferometer Space Antenna (LISA) project plan of a few years ago. I will discuss recent progress and developments resulting from the European eLISA study and the SGO study in the US and prospects looking forward.

  20. Telescope Technology Development Results for a Space-Based Gravitational-Wave Observatory

    NASA Astrophysics Data System (ADS)

    Livas, Jeffrey C.; Sankar, Shannon R.

    2016-01-01

    Space-based Gravitational-wave Observatories will enable the systematic study of the low-frequency band (0.0001 - 1 Hz) of gravitational waves, where a rich array of astrophysical sources is expected. Optical telescopes play an important role in these observatories by enabling displacement measurements between pairs of freely falling proof masses. The telescopes deliver laser light efficiently from one sciencecraft to another over million-kilometer scale separations and must transmit and receive light simultaneously. Transmitting and receiving at the same time puts tight constraints on the scattered light performance. In addition, the required displacement measurement accuracy requires ~ 1 pm/√Hz pathlength stability through the telescope in the measurement band. We report preliminary measurements on a prototype telescope.This work was funded in part by NASA SAT grant 11-SAT11-0027.

  1. Gravitational radiation from massless particle collisions

    NASA Astrophysics Data System (ADS)

    Gruzinov, Andrei; Veneziano, Gabriele

    2016-06-01

    We compute classical gravitational bremsstrahlung from the gravitational scattering of two massless particles at leading order in the (centre of mass) deflection angle θ ∼ 4G\\sqrt{s}/b=8{GE}/b\\ll 1. The calculation, although non-perturbative in the gravitational constant, is surprisingly simple and yields explicit formulae—in terms of multidimensional integrals—for the frequency and angular distribution of the radiation. In the range {b}-1\\lt ω \\lt {({GE})}-1, the GW spectrum behaves like {log}(1/{GE}ω ){{d}}ω , is confined to cones of angular sizes (around the deflected particle trajectories) ranging from O(θ ) to O(1/ω b), and exactly reproduces, at its lower end, a well-known zero-frequency limit. At ω \\gt {({GE})}-1 the radiation is confined to cones of angular size of order θ {({GE}ω )}-1/2 resulting in a scale-invariant ({{d}}ω /ω ) spectrum. The total efficiency in GW production is dominated by this ‘high frequency’ region and is formally logarithmically divergent in the UV. If the spectrum is cutoff at the limit of validity of our approximations (where a conjectured bound on GW power is also saturated), the fraction of incoming energy radiated away turns out to be \\tfrac{1}{2π }{θ }2{log}{θ }-2 at leading logarithmic accuracy.

  2. Gravitational radiation, inspiraling binaries, and cosmology

    NASA Technical Reports Server (NTRS)

    Chernoff, David F.; Finn, Lee S.

    1993-01-01

    We show how to measure cosmological parameters using observations of inspiraling binary neutron star or black hole systems in one or more gravitational wave detectors. To illustrate, we focus on the case of fixed mass binary systems observed in a single Laser Interferometer Gravitational-wave Observatory (LIGO)-like detector. Using realistic detector noise estimates, we characterize the rate of detections as a function of a threshold SNR Rho(0), H0, and the binary 'chirp' mass. For Rho(0) = 8, H0 = 100 km/s/Mpc, and 1.4 solar mass neutron star binaries, the sample has a median redshift of 0.22. Under the same assumptions but independent of H0, a conservative rate density of coalescing binaries implies LIGO will observe about 50/yr binary inspiral events. The precision with which H0 and the deceleration parameter q0 may be determined depends on the number of observed inspirals. For fixed mass binary systems, about 100 observations with Rho(0) = 10 in the LIGO will give H0 to 10 percent in an Einstein-DeSitter cosmology, and 3000 will give q0 to 20 percent. For the conservative rate density of coalescing binaries, 100 detections with Rho(0) = 10 will require about 4 yrs.

  3. Gravitational radiation from extreme Kerr black hole

    NASA Technical Reports Server (NTRS)

    Sasaki, Misao; Nakamura, Takashi

    1989-01-01

    Gravitational radiation induced by a test particle falling into an extreme Kerr black hole was investigated analytically. Assuming the radiation is dominated by the infinite sequence of quasi-normal modes which has the limiting frequency m/(2M), where m is an azimuthal eigenvalue and M is the mass of the black hole, it was found that the radiated energy diverges logarithmically in time. Then the back reaction to the black hole was evaluated by appealing to the energy and angular momentum conservation laws. It was found that the radiation has a tendency to increase the ratio of the angular momentum to mass of the black hole, which is completely different from non-extreme case, while the contribution of the test particle is to decrease it.

  4. Towards a gravitational wave observatory designer: sensitivity limits of spaceborne detectors

    NASA Astrophysics Data System (ADS)

    Barke, S.; Wang, Y.; Esteban Delgado, J. J.; Tröbs, M.; Heinzel, G.; Danzmann, K.

    2015-05-01

    The most promising concept for low frequency (millihertz to hertz) gravitational wave observatories are laser interferometric detectors in space. It is usually assumed that the noise floor for such a detector is dominated by optical shot noise in the signal readout. For this to be true, a careful balance of mission parameters is crucial to keep all other parasitic disturbances below shot noise. We developed a web application that uses over 30 input parameters and considers many important technical noise sources and noise suppression techniques to derive a realistic position noise budget. It optimizes free parameters automatically and generates a detailed report on all individual noise contributions. Thus one can easily explore the entire parameter space and design a realistic gravitational wave observatory. In this document we describe the different parameters, present all underlying calculations, and compare the final observatory’s sensitivity with astrophysical sources of gravitational waves. We use as an example parameters currently assumed to be likely applied to a space mission proposed to be launched in 2034 by the European Space Agency. The web application itself is publicly available on the Internet at http://spacegravity.org/designer. Future versions of the web application will incorporate the frequency dependence of different noise sources and include a more detailed model of the observatory’s residual acceleration noise.

  5. Persistent Gravitational Radiation from Glitching Pulsars

    NASA Astrophysics Data System (ADS)

    Melatos, A.; Douglass, J. A.; Simula, T. P.

    2015-07-01

    Quantum mechanical simulations of neutron star rotational glitches, triggered by vortex avalanches in the superfluid stellar interior, reveal that vortices pin nonaxisymmetrically to the crust during the intervals between glitches. Hence a glitching neutron star emits a persistent current quadrupole gravitational wave signal at the star’s rotation frequency, whose interglitch amplitude is constant and determined by the avalanche history since birth. The signal can be detected in principle by coherent searches planned for the Laser Interferometer Gravitational Wave Observatory (LIGO), whether or not a glitch occurs during the observation, if the power-law distribution of glitch sizes extends up to {{Δ }}{{{Ω }}}{max}/{{Ω }}≳ {10}-6{η }-1{({{Δ }}φ )}-1{({{Ω }}/{10}3 {rad} {{{s}}}-1)}-3(D/1 {kpc}) in the targeted object, where {{Δ }}{{{Ω }}}{max} and {{Δ }}φ are the largest angular velocity jump and avalanche opening angle, respectively, to have occurred in a glitch since birth, Ω is the angular velocity at present, η is the crustal fraction of the moment of inertia, and D is the distance from the Earth. A major caveat concerning detectability is whether the nonaxisymmetries observed in existing simulations with ≲ {10}3 vortices extrapolate to realistic neutron stars with ≳ {10}15 vortices. The arguments for and against extrapolation are discussed critically in the context of avalanche dynamics in self-organized critical systems, but the issue cannot be resolved without larger simulations and tighter observational limits on η {{Δ }}φ {{Δ }}{{{Ω }}}{max} from future LIGO (non)detections and radio timing campaigns.

  6. Analytical model for ring heater thermal compensation in the Advanced Laser Interferometer Gravitational-wave Observatory.

    PubMed

    Ramette, Joshua; Kasprzack, Marie; Brooks, Aidan; Blair, Carl; Wang, Haoyu; Heintze, Matthew

    2016-04-01

    Advanced laser interferometer gravitational-wave detectors use high laser power to achieve design sensitivity. A small part of this power is absorbed in the interferometer cavity mirrors where it creates thermal lenses, causing aberrations in the main laser beam that must be minimized by the actuation of "ring heaters," which are additional heater elements that are aimed to reduce the temperature gradients in the mirrors. In this article we derive the first, to the best of our knowledge, analytical model of the temperature field generated by an ideal ring heater. We express the resulting optical aberration contribution to the main laser beam in this axisymmetric case. Used in conjunction with wavefront measurements, our model provides a more complete understanding of the thermal state of the cavity mirrors and will allow a more efficient use of the ring heaters in the Advanced Laser Interferometer Gravitational-wave Observatory. PMID:27139664

  7. Plans for a Next Generation Space-Based Gravitational-Wave Observatory (NGO)

    NASA Technical Reports Server (NTRS)

    Livas, Jeffrey C.; Stebbins, Robin T.; Jennrich, Oliver

    2012-01-01

    The European Space Agency (ESA) is currently in the process of selecting a mission for the Cosmic Visions Program. A space-based gravitational wave observatory in the low-frequency band (0.0001 - 1 Hz) of the gravitational wave spectrum is one of the leading contenders. This low frequency band has a rich spectrum of astrophysical sources, and the LISA concept has been the key mission to cover this science for over twenty years. Tight budgets have recently forced ESA to consider a reformulation of the LISA mission concept that wi" allow the Cosmic Visions Program to proceed on schedule either with the US as a minority participant, or independently of the US altogether. We report on the status of these reformulation efforts.

  8. A gravitational wave observatory operating beyond the quantum shot-noise limit

    NASA Astrophysics Data System (ADS)

    Ligo Scientific Collaboration; Abadie, J.; Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M.; Adams, C.; Adhikari, R.; Affeldt, C.; Allen, B.; Allen, G. S.; Amador Ceron, E.; Amariutei, D.; Amin, R. S.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Arain, M. A.; Araya, M. C.; Aston, S. M.; Atkinson, D.; Aufmuth, P.; Aulbert, C.; Aylott, B. E.; Babak, S.; Baker, P.; Ballmer, S.; Barker, D.; Barr, B.; Barriga, P.; Barsotti, L.; Barton, M. A.; Bartos, I.; Bassiri, R.; Bastarrika, M.; Batch, J.; Bauchrowitz, J.; Behnke, B.; Bell, A. S.; Belopolski, I.; Benacquista, M.; Berliner, J. M.; Bertolini, A.; Betzwieser, J.; Beveridge, N.; Beyersdorf, P. T.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Biswas, R.; Black, E.; Blackburn, J. K.; Blackburn, L.; Blair, D.; Bland, B.; Bock, O.; Bodiya, T. P.; Bogan, C.; Bondarescu, R.; Bork, R.; Born, M.; Bose, S.; Brady, P. R.; Braginsky, V. B.; Brau, J. E.; Breyer, J.; Bridges, D. O.; Brinkmann, M.; Britzger, M.; Brooks, A. F.; Brown, D. A.; Brummitt, A.; Buonanno, A.; Burguet-Castell, J.; Burmeister, O.; Byer, R. L.; Cadonati, L.; Camp, J. B.; Campsie, P.; Cannizzo, J.; Cannon, K.; Cao, J.; Capano, C. D.; Caride, S.; Caudill, S.; Cavagliá, M.; Cepeda, C.; Chalermsongsak, T.; Chalkley, E.; Charlton, P.; Chelkowski, S.; Chen, Y.; Christensen, N.; Cho, H.; Chua, S. S. Y.; Chung, S.; Chung, C. T. Y.; Ciani, G.; Clara, F.; Clark, D. E.; Clark, J.; Clayton, J. H.; Conte, R.; Cook, D.; Corbitt, T. R.; Cordier, M.; Cornish, N.; Corsi, A.; Costa, C. A.; Coughlin, M.; Couvares, P.; Coward, D. M.; Coyne, D. C.; Creighton, J. D. E.; Creighton, T. D.; Cruise, A. M.; Cumming, A.; Cunningham, L.; Cutler, R. M.; Dahl, K.; Danilishin, S. L.; Dannenberg, R.; Danzmann, K.; Daudert, B.; Daveloza, H.; Davies, G.; Daw, E. J.; Dayanga, T.; Debra, D.; Degallaix, J.; Dent, T.; Dergachev, V.; Derosa, R.; Desalvo, R.; Dhurandhar, S.; Diguglielmo, J.; di Palma, I.; Díaz, M.; Donovan, F.; Dooley, K. L.; Dorsher, S.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Dumas, J.-C.; Dwyer, S.; Eberle, T.; Edgar, M.; Edwards, M.; Effler, A.; Ehrens, P.; Engel, R.; Etzel, T.; Evans, K.; Evans, M.; Evans, T.; Factourovich, M.; Fairhurst, S.; Fan, Y.; Farr, B. F.; Farr, W.; Fazi, D.; Fehrmann, H.; Feldbaum, D.; Finn, L. S.; Fisher, R. P.; Flanigan, M.; Foley, S.; Forsi, E.; Fotopoulos, N.; Frede, M.; Frei, M.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T. T.; Friedrich, D.; Fritschel, P.; Frolov, V. V.; Fulda, P. J.; Fyffe, M.; Ganija, M. R.; Garcia, J.; Garofoli, J. A.; Geng, R.; Gergely, L. Á.; Gholami, I.; Ghosh, S.; Giaime, J. A.; Giampanis, S.; Giardina, K. D.; Gill, C.; Goetz, E.; Goggin, L. M.; González, G.; Gorodetsky, M. L.; Goßler, S.; Graef, C.; Grant, A.; Gras, S.; Gray, C.; Gray, N.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Grosso, R.; Grote, H.; Grunewald, S.; Guido, C.; Gupta, R.; Gustafson, E. K.; Gustafson, R.; Ha, T.; Hage, B.; 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.; Heefner, J.; Heintze, M. C.; Hendry, M. A.; Heng, I. S.; Heptonstall, A. W.; Herrera, V.; Hewitson, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Holt, K.; Hong, T.; Hooper, S.; Hosken, D. J.; Hough, J.; Howell, E. J.; Hughey, B.; Huynh-Dinh, T.; Husa, S.; Huttner, S. H.; Ingram, D. R.; Inta, R.; Isogai, T.; Ivanov, A.; Izumi, K.; Jacobson, M.; Jang, H.; Johnson, W. W.; Jones, D. I.; Jones, G.; Jones, R.; Ju, L.; Kalmus, P.; Kalogera, V.; Kamaretsos, I.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Katsavounidis, E.; Katzman, W.; Kaufer, H.; Kawabe, K.; Kawamura, S.; Kawazoe, F.; Kells, W.; Keppel, D. G.; Keresztes, Z.; Khalaidovski, A.; Khalili, F. Y.; Khazanov, E. A.; Kim, B.; Kim, C.; Kim, D.; Kim, H.; Kim, K.; Kim, N.; Kim, Y.-M.; King, P. J.; Kinsey, M.; Kinzel, D. L.; Kissel, J. S.; Klimenko, S.; Kokeyama, K.; Kondrashov, V.; Kopparapu, R.; Koranda, S.; Korth, W. Z.; Kozak, D.; Kringel, V.; Krishnamurthy, S.; Krishnan, B.; Kuehn, G.; Kumar, R.; Kwee, P.; Lam, P. K.; Landry, M.; Lang, M.; Lantz, B.; Lastzka, N.; Lawrie, C.; Lazzarini, A.; Leaci, P.; Lee, C. H.; Lee, H. M.; Leindecker, N.; Leong, J. R.; Leonor, I.; Li, J.; Lindquist, P. E.; Lockerbie, N. A.; Lodhia, D.; Lormand, M.; Luan, J.; Lubinski, M.; Lück, H.; Lundgren, A. P.; MacDonald, E.; Machenschalk, B.; Macinnis, M.; MacLeod, D. M.; Mageswaran, M.; Mailand, K.; Mandel, I.; Mandic, V.; Marandi, A.; Márka, S.; Márka, Z.; Markosyan, A.; Maros, E.; Martin, I. W.; Martin, R. M.; Marx, J. N.; Mason, K.; Matichard, F.; Matone, L.; Matzner, R. A.; Mavalvala, N.; Mazzolo, G.; McCarthy, R.; McClelland, D. E.; McGuire, S. C.; McIntyre, G.; McIver, J.; McKechan, D. J. A.; Meadors, G. D.; Mehmet, M.; Meier, T.; Melatos, A.; Melissinos, A. C.; Mendell, G.; Menendez, D.; Mercer, R. A.; Meshkov, S.; Messenger, C.; Meyer, M. S.; Miao, H.; Miller, J.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Miyakawa, O.; Moe, B.; Moesta, P.; Mohanty, S. D.; Moraru, D.; Moreno, G.; Mori, T.; Mossavi, K.; 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.; Nawrodt, R.; Necula, V.; Nelson, J.; Newton, G.; Nishizawa, A.; Nolting, D.; Nuttall, L.; O'Dell, J.; O'Reilly, B.; O'Shaughnessy, R.; Ochsner, E.; Oelker, E.; Oh, J. J.; Oh, S. H.; Ogin, G. H.; Oldenburg, R. G.; Osthelder, C.; Ott, C. D.; Ottaway, D. J.; Ottens, R. S.; Overmier, H.; Owen, B. J.; Page, A.; Pan, Y.; Pankow, C.; Papa, M. A.; Ajith, P.; Patel, P.; Pedraza, M.; Peiris, P.; Pekowsky, L.; Penn, S.; Peralta, C.; Perreca, A.; Phelps, M.; Pickenpack, M.; Pinto, I. M.; Pitkin, M.; Pletsch, H. J.; Plissi, M. V.; Pöld, J.; Postiglione, F.; Predoi, V.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prix, R.; Prokhorov, L.; Puncken, O.; Quetschke, V.; Raab, F. J.; Radkins, H.; Raffai, P.; Rakhmanov, M.; Ramet, C. R.; Rankins, B.; Mohapatra, S. R. P.; Raymond, V.; Redwine, K.; Reed, C. M.; Reed, T.; Reid, S.; Reitze, D. H.; Riesen, R.; Riles, K.; Robertson, N. A.; Robinson, C.; Robinson, E. L.; Roddy, S.; Rodriguez, C.; Rodruck, M.; Rollins, J.; Romano, J. D.; Romie, J. H.; Röver, C.; Rowan, S.; Rüdiger, A.; Ryan, K.; Ryll, H.; Sainathan, P.; Sakosky, M.; Salemi, F.; Samblowski, A.; Sammut, L.; Sancho de La Jordana, L.; Sandberg, V.; Sankar, S.; Sannibale, V.; Santamaría, L.; Santiago-Prieto, I.; Santostasi, G.; Sathyaprakash, B. S.; Sato, S.; Saulson, P. R.; Savage, R. L.; Schilling, R.; Schlamminger, S.; Schnabel, R.; Schofield, R. M. S.; Schulz, B.; Schutz, B. F.; Schwinberg, P.; Scott, J.; Scott, S. M.; Searle, A. C.; Seifert, F.; Sellers, D.; Sengupta, A. S.; Sergeev, A.; Shaddock, D. A.; Shaltev, M.; Shapiro, B.; Shawhan, P.; Shoemaker, D. H.; Sibley, A.; Siemens, X.; Sigg, D.; Singer, A.; Singer, L.; Sintes, A. M.; Skelton, G.; Slagmolen, B. J. J.; Slutsky, J.; Smith, R. J. E.; Smith, J. R.; Smith, M. R.; Smith, N. D.; Somiya, K.; Sorazu, B.; Soto, J.; Speirits, F. C.; Stein, A. J.; Steinert, E.; Steinlechner, J.; Steinlechner, S.; Steplewski, S.; Stefszky, M.; Stochino, A.; Stone, R.; Strain, K. A.; Strigin, S.; Stroeer, A. S.; Stuver, A. L.; Summerscales, T. Z.; Sung, M.; Susmithan, S.; Sutton, P. J.; Talukder, D.; Tanner, D. B.; Tarabrin, S. P.; Taylor, J. R.; Taylor, R.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Thüring, A.; Titsler, C.; Tokmakov, K. V.; Torres, C.; Torrie, C. I.; Traylor, G.; Trias, M.; Tseng, K.; Ugolini, D.; Urbanek, K.; Vahlbruch, H.; Vallisneri, M.; van Veggel, A. A.; Vass, S.; Vaulin, R.; Vecchio, A.; Veitch, J.; Veitch, P. J.; Veltkamp, C.; Villar, A. E.; Vitale, S.; Vorvick, C.; Vyatchanin, S. P.; Wade, A.; Waldman, S. J.; Wallace, L.; Wan, Y.; Wanner, A.; Wang, X.; Wang, Z.; Ward, R. L.; Wei, P.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Wen, L.; Wen, S.; Wessels, P.; West, M.; Westphal, T.; Wette, K.; Whelan, J. T.; Whitcomb, S. E.; White, D.; Whiting, B. F.; Wilkinson, C.; Willems, P. A.; Williams, H. R.; Williams, L.; Willke, B.; Winkelmann, L.; Winkler, W.; Wipf, C. C.; Wittel, H.; Wiseman, A. G.; Woan, G.; Wooley, R.; Worden, J.; Yablon, J.; Yakushin, I.; Yamamoto, K.; Yamamoto, H.; Yang, H.; Yeaton-Massey, D.; Yoshida, S.; Yu, P.; Zanolin, M.; Zhang, L.; Zhang, W.; Zhang, Z.; Zhao, C.; Zotov, N.; Zucker, M. E.; Zweizig, J.

    2011-12-01

    Around the globe several observatories are seeking the first direct detection of gravitational waves (GWs). These waves are predicted by Einstein's general theory of relativity and are generated, for example, by black-hole binary systems. Present GW detectors are Michelson-type kilometre-scale laser interferometers measuring the distance changes between mirrors suspended in vacuum. The sensitivity of these detectors at frequencies above several hundred hertz is limited by the vacuum (zero-point) fluctuations of the electromagnetic field. A quantum technology--the injection of squeezed light--offers a solution to this problem. Here we demonstrate the squeezed-light enhancement of GEO600, which will be the GW observatory operated by the LIGO Scientific Collaboration in its search for GWs for the next 3-4 years. GEO600 now operates with its best ever sensitivity, which proves the usefulness of quantum entanglement and the qualification of squeezed light as a key technology for future GW astronomy.

  9. Limb shape observations at the Pic du Midi Observatory. Determination of the solar gravitational moments

    NASA Astrophysics Data System (ADS)

    Rozelot, J. P.; Lefebvre, S.

    The accurate shape of the Sun has been actively debated since 1974. So far, balloon and satellite experiments achieved the required sensibility to measure the expected small asphericities of the solar limb shape. However, exceptional good meteorological conditions encountered during several missions at the Pic du Midi Observatory have permitted to measure the coefficients shape of the solar limb on the two first Legendre polynomials expansion. In theory, this photospheric outer shape is sensitive to the interior rate, and asphericities can be explained both in terms of gravitational moments and thermal wind. We present observations made at the Pic du Midi Observatory and we compare results with these obtained by SDS (Sofia et al., 1994, 1996) and SOHO/MDI (Kuhn, 1999). The accepted and dedicated PICARD space mission on this subject is briefly presented.

  10. Space-based gravitational wave observatories: Learning from the past, moving towards the future

    NASA Astrophysics Data System (ADS)

    Mueller, Guido; Cornish, Neil

    2014-03-01

    This century began with a planned launch of the joint NASA/ESA Laser Interferometer Space Antenna in 2011. In a remarkable reversal of fate, 2011 instead saw the end of the NASA/ESA partnership and the termination of the LISA project. This was despite the very high scientific ranking of a mHz gravitational wave observatory in both the US and Europe, and significant progress in technology development, mostly spearhead by industrial studies in Europe. The first half of the current decade continues to be dominated by struggles of the international community to get a LISA-like mission back on track for a launch in the next decade. Following a second place in ESA's L1 selection, the science theme ``The Gravitational Universe'' has now been selected as the L3 mission in Europe which is scheduled to launch in 2034 assuming no further delays or re-plans for the L1-L2-L3 mission sequence. On a more optimistic note, the upcoming launch of the LISA Pathfinder in 2015 and the first direct detections of gravitational waves by Advanced LIGO and by pulsar timing later in this decade may provide the necessary impetus to accelerate the development of a space-based gravitational wave detector.

  11. ESA’s L3 mission: A space-based gravitational-wave observatory

    NASA Astrophysics Data System (ADS)

    Mueller, Guido

    2016-04-01

    ESA selected the Gravitational Universe as the science theme for one of its future L-class missions. L3 will measure gravitational waves in the 10µHz to 100mHz window; probably the richest of all gravitational wave windows. Expected sources in this frequency band range from massive black hole mergers to extreme mass ratio inspirals to compact galactic binary systems.The L3 mission is expected to be based on the eLISA/LISA design which was submitted by the eLISA consortium as a notional mission concept. NASA started discussions with ESA how to join L3 and participates in ESA’s Gravitational Observatory Advisory Team. NASA is also in the process of setting up its own L3-Study team to look at potential US contributions to L3. This group will also act as the US partner for the eLISA consortium. In summary, the space component of the GW community has gained significant momentum over the last 12 months and a successful pathfinder mission and potential GW discoveries by Advanced LIGO and/or pulsar timing arrays should further strengthen the case for LISA.

  12. A Xylophone Detector of Gravitational Radiation

    NASA Technical Reports Server (NTRS)

    Tinto, Massimo

    1997-01-01

    We discuss spacecraft Doppler tracking searches for gravitational waves in which Doppler data recorded on the ground are linearly combined with Doppler measurements made on board a spacecraft. By using the four-link radio system first proposed by Vessot and Levine, we describe a new method for removing from the combined data the frequency fluctuations due to the Earth troposphere, ionosphere, and mechanical vibrations of the antenna on the ground. This technique provides also a way for reducing by several orders of magnitude, at selected Fourier components, the frequency fluctuations due to other noise sources, such as the clock on board the spacecraft or the antenna and buffeting of the probe by nongravitational forces. In this respect spacecraft Doppler tracking can be regarded as a xylophone detector of gravitational radiation. In the assumption of calibrating the frequency fluctuations induced by the interplanetary plasma, a strain sensitivity equal to 4.7 x 10(exp -18) at 10(exp -3) Hz is estimated. This experimental technique could be extended to other tests of the theory of relativity, and to radio science experiments that rely on high-precision Doppler measurements.

  13. Sub-Femto-g Free Fall for Space-Based Gravitational Wave Observatories: LISA Pathfinder Results

    NASA Astrophysics Data System (ADS)

    Armano, M.; Audley, H.; Auger, G.; Baird, J. T.; Bassan, M.; Binetruy, P.; Born, M.; Bortoluzzi, D.; Brandt, N.; Caleno, M.; Carbone, L.; Cavalleri, A.; Cesarini, A.; Ciani, G.; Congedo, G.; Cruise, A. M.; Danzmann, K.; de Deus Silva, M.; De Rosa, R.; Diaz-Aguiló, M.; Di Fiore, L.; Diepholz, I.; Dixon, G.; Dolesi, R.; Dunbar, N.; Ferraioli, L.; Ferroni, V.; Fichter, W.; Fitzsimons, E. D.; Flatscher, R.; Freschi, M.; García Marín, A. F.; García Marirrodriga, C.; Gerndt, R.; Gesa, L.; Gibert, F.; Giardini, D.; Giusteri, R.; Guzmán, F.; Grado, A.; Grimani, C.; Grynagier, A.; Grzymisch, J.; Harrison, I.; Heinzel, G.; Hewitson, M.; Hollington, D.; Hoyland, D.; Hueller, M.; Inchauspé, H.; Jennrich, O.; Jetzer, P.; Johann, U.; Johlander, B.; Karnesis, N.; Kaune, B.; Korsakova, N.; Killow, C. J.; Lobo, J. A.; Lloro, I.; Liu, L.; López-Zaragoza, J. P.; Maarschalkerweerd, R.; Mance, D.; Martín, V.; Martin-Polo, L.; Martino, J.; Martin-Porqueras, F.; Madden, S.; Mateos, I.; McNamara, P. W.; Mendes, J.; Mendes, L.; Monsky, A.; Nicolodi, D.; Nofrarias, M.; Paczkowski, S.; Perreur-Lloyd, M.; Petiteau, A.; Pivato, P.; Plagnol, E.; Prat, P.; Ragnit, U.; Raïs, B.; Ramos-Castro, J.; Reiche, J.; Robertson, D. I.; Rozemeijer, H.; Rivas, F.; Russano, G.; Sanjuán, J.; Sarra, P.; Schleicher, A.; Shaul, D.; Slutsky, J.; Sopuerta, C. F.; Stanga, R.; Steier, F.; Sumner, T.; Texier, D.; Thorpe, J. I.; Trenkel, C.; Tröbs, M.; Tu, H. B.; Vetrugno, D.; Vitale, S.; Wand, V.; Wanner, G.; Ward, H.; Warren, C.; Wass, P. J.; Wealthy, D.; Weber, W. J.; Wissel, L.; Wittchen, A.; Zambotti, A.; Zanoni, C.; Ziegler, T.; Zweifel, P.

    2016-06-01

    We report the first results of the LISA Pathfinder in-flight experiment. The results demonstrate that two free-falling reference test masses, such as those needed for a space-based gravitational wave observatory like LISA, can be put in free fall with a relative acceleration noise with a square root of the power spectral density of 5.2 ±0.1 fm s-2/√{Hz } , or (0.54 ±0.01 ) ×10-15 g/√{Hz } , with g the standard gravity, for frequencies between 0.7 and 20 mHz. This value is lower than the LISA Pathfinder requirement by more than a factor 5 and within a factor 1.25 of the requirement for the LISA mission, and is compatible with Brownian noise from viscous damping due to the residual gas surrounding the test masses. Above 60 mHz the acceleration noise is dominated by interferometer displacement readout noise at a level of (34.8 ±0.3 ) fm /√{Hz } , about 2 orders of magnitude better than requirements. At f ≤0.5 mHz we observe a low-frequency tail that stays below 12 fm s-2/√{Hz } down to 0.1 mHz. This performance would allow for a space-based gravitational wave observatory with a sensitivity close to what was originally foreseen for LISA.

  14. Stochastic microhertz gravitational radiation from stellar convection

    SciTech Connect

    Bennett, M. F.; Melatos, A.

    2014-09-01

    High Reynolds-number turbulence driven by stellar convection in main-sequence stars generates stochastic gravitational radiation. We calculate the wave-strain power spectral density as a function of the zero-age main-sequence mass for an individual star and for an isotropic, universal stellar population described by the Salpeter initial mass function and redshift-dependent Hopkins-Beacom star formation rate. The spectrum is a broken power law, which peaks near the turnover frequency of the largest turbulent eddies. The signal from the Sun dominates the universal background. For the Sun, the far-zone power spectral density peaks at S(f {sub peak}) = 5.2 × 10{sup –52} Hz{sup –1} at frequency f {sub peak} = 2.3 × 10{sup –7} Hz. However, at low observing frequencies f < 3 × 10{sup –4} Hz, the Earth lies inside the Sun's near zone and the signal is amplified to S {sub near}(f {sub peak}) = 4.1 × 10{sup –27} Hz{sup –1} because the wave strain scales more steeply with distance (∝d {sup –5}) in the near zone than in the far zone (∝d {sup –1}). Hence the Solar signal may prove relevant for pulsar timing arrays. Other individual sources and the universal background fall well below the projected sensitivities of the Laser Interferometer Space Antenna and next-generation pulsar timing arrays. Stellar convection sets a fundamental noise floor for more sensitive stochastic gravitational-wave experiments in the more distant future.

  15. Sub-Femto-g Free Fall for Space-Based Gravitational Wave Observatories: LISA Pathfinder Results.

    PubMed

    Armano, M; Audley, H; Auger, G; Baird, J T; Bassan, M; Binetruy, P; Born, M; Bortoluzzi, D; Brandt, N; Caleno, M; Carbone, L; Cavalleri, A; Cesarini, A; Ciani, G; Congedo, G; Cruise, A M; Danzmann, K; de Deus Silva, M; De Rosa, R; Diaz-Aguiló, M; Di Fiore, L; Diepholz, I; Dixon, G; Dolesi, R; Dunbar, N; Ferraioli, L; Ferroni, V; Fichter, W; Fitzsimons, E D; Flatscher, R; Freschi, M; García Marín, A F; García Marirrodriga, C; Gerndt, R; Gesa, L; Gibert, F; Giardini, D; Giusteri, R; Guzmán, F; Grado, A; Grimani, C; Grynagier, A; Grzymisch, J; Harrison, I; Heinzel, G; Hewitson, M; Hollington, D; Hoyland, D; Hueller, M; Inchauspé, H; Jennrich, O; Jetzer, P; Johann, U; Johlander, B; Karnesis, N; Kaune, B; Korsakova, N; Killow, C J; Lobo, J A; Lloro, I; Liu, L; López-Zaragoza, J P; Maarschalkerweerd, R; Mance, D; Martín, V; Martin-Polo, L; Martino, J; Martin-Porqueras, F; Madden, S; Mateos, I; McNamara, P W; Mendes, J; Mendes, L; Monsky, A; Nicolodi, D; Nofrarias, M; Paczkowski, S; Perreur-Lloyd, M; Petiteau, A; Pivato, P; Plagnol, E; Prat, P; Ragnit, U; Raïs, B; Ramos-Castro, J; Reiche, J; Robertson, D I; Rozemeijer, H; Rivas, F; Russano, G; Sanjuán, J; Sarra, P; Schleicher, A; Shaul, D; Slutsky, J; Sopuerta, C F; Stanga, R; Steier, F; Sumner, T; Texier, D; Thorpe, J I; Trenkel, C; Tröbs, M; Tu, H B; Vetrugno, D; Vitale, S; Wand, V; Wanner, G; Ward, H; Warren, C; Wass, P J; Wealthy, D; Weber, W J; Wissel, L; Wittchen, A; Zambotti, A; Zanoni, C; Ziegler, T; Zweifel, P

    2016-06-10

    We report the first results of the LISA Pathfinder in-flight experiment. The results demonstrate that two free-falling reference test masses, such as those needed for a space-based gravitational wave observatory like LISA, can be put in free fall with a relative acceleration noise with a square root of the power spectral density of 5.2±0.1  fm s^{-2}/sqrt[Hz], or (0.54±0.01)×10^{-15}  g/sqrt[Hz], with g the standard gravity, for frequencies between 0.7 and 20 mHz. This value is lower than the LISA Pathfinder requirement by more than a factor 5 and within a factor 1.25 of the requirement for the LISA mission, and is compatible with Brownian noise from viscous damping due to the residual gas surrounding the test masses. Above 60 mHz the acceleration noise is dominated by interferometer displacement readout noise at a level of (34.8±0.3)  fm/sqrt[Hz], about 2 orders of magnitude better than requirements. At f≤0.5  mHz we observe a low-frequency tail that stays below 12  fm s^{-2}/sqrt[Hz] down to 0.1 mHz. This performance would allow for a space-based gravitational wave observatory with a sensitivity close to what was originally foreseen for LISA. PMID:27341221

  16. Status of a Space-Based Gravitational-Wave Observatory at NASA

    NASA Astrophysics Data System (ADS)

    Stebbins, Robin

    2015-08-01

    For over two decades, NASA has studied a flight project to build a gravitational-wave observatory, and partnered with the European Space Agency (ESA) to formulate and study such a mission. The spectacular science and the well-defined and well-studied Laser Interferometer Space Antenna (LISA) mission concept got high recommendations in the U.S. astrophysics decadal surveys of 2000 and 2010.In 2013, ESA selected the science theme, the “Gravitational Universe,” for the third large mission opportunity, known as L3, under its Cosmic Vision Programme. The planned launch date is 2034. ESA is considering a 20% participation by an international partner, and NASA's Astrophysics Division has begun negotiating a NASA role. The US research community has studied the design consequences of a NASA contribution, evaluated the science benefits and identified the technology requirements for hardware that could be delivered by NASA.This talk will describe the current state of: mission concept studies, US participation in an ESA-led study, technology development, other relevant activities and preparation for the 2020 decadal survey.

  17. Compact vibration isolation and suspension for Australian International Gravitational Observatory: local control system.

    PubMed

    Dumas, Jean-Charles; Barriga, Pablo; Zhao, Chunnong; Ju, Li; Blair, David G

    2009-11-01

    High performance vibration isolators are required for ground based gravitational wave detectors. To attain very high performance at low frequencies we have developed multistage isolators for the proposed Australian International Gravitational Observatory detector in Australia. New concepts in vibration isolation including self-damping, Euler springs, LaCoste springs, Roberts linkages, and double preisolation require novel sensors and actuators. Double preisolation enables internal feedback to be used to suppress low frequency seismic noise. Multidegree of freedom control systems are required to attain high performance. Here we describe the control components and control systems used to control all degrees of freedom. Feedback forces are injected at the preisolation stages and at the penultimate suspension stage. There is no direct actuation on test masses. A digital local control system hosted on a digital signal processor maintains alignment and position, corrects drifts, and damps the low frequency linear and torsional modes without exciting the very high Q-factor test mass suspension. The control system maintains an optical cavity locked to a laser with a high duty cycle even in the absence of an autoalignment system. An accompanying paper presents the mechanics of the system, and the optical cavity used to determine isolation performance. A feedback method is presented, which is expected to improve the residual motion at 1 Hz by more than one order of magnitude. PMID:19947744

  18. Simulation of Merger of Two Black Holes and Gravitational Radiation

    NASA Video Gallery

    This movie shows a simulation of the merger of two black holes and the resulting emission of gravitational radiation. The colored fields represent a component of the curvature of space-time. The ou...

  19. Gravitational radiation by cosmic strings in a junction

    SciTech Connect

    Brandenberger, R.; Karouby, J.; Firouzjahi, H.; Khosravi, S.

    2009-01-15

    The formalism for computing the gravitational power radiation from excitations on cosmic strings forming a junction is presented and applied to the simple case of co-planar strings at a junction when the excitations are generated along one string leg. The effects of polarization of the excitations and of the back-reaction of the gravitational radiation on the small scale structure of the strings are studied.

  20. Cosmic string structure at the gravitational radiation scale

    SciTech Connect

    Polchinski, Joseph; Rocha, Jorge V.

    2007-06-15

    We use our model of the small scale structure on cosmic strings to develop further the result of Siemens, Olum, and Vilenkin that the gravitational radiation length scale on cosmic strings is smaller than the previously assumed {gamma}G{mu}t. We discuss some of the properties of cosmic string loops at this cutoff scale, and we argue that recent network simulations point to two populations of cosmic string loops, one near the horizon scale and one near the gravitational radiation cutoff.

  1. Gravitational radiation from collapsing magnetized dust

    SciTech Connect

    Sotani, Hajime; Yoshida, Shijun; Kokkotas, Kostas D.

    2007-04-15

    In this article we study the influence of magnetic fields on the axial gravitational waves emitted during the collapse of a homogeneous dust sphere. We found that while the energy emitted depends weakly on the initial matter perturbations it has strong dependence on the strength and the distribution of the magnetic field perturbations. The gravitational wave output of such a collapse can be up to an order of magnitude larger or smaller calling for detailed numerical 3D studies of collapsing magnetized configurations.

  2. Gravitational waves from individual supermassive black hole binaries in circular orbits: limits from the North American nanohertz observatory for gravitational waves

    SciTech Connect

    Arzoumanian, Z.; Brazier, A.; Chatterjee, S.; Cordes, J. M.; Dolch, T.; Lam, M. T.; Burke-Spolaor, S.; Chamberlin, S. J.; Ellis, J. A.; Demorest, P. B.; Deng, X.; Koop, M.; Ferdman, R. D.; Kaspi, V. M.; Garver-Daniels, N.; Lorimer, D. R.; Jenet, F.; Jones, G.; Lazio, T. J. W.; Lommen, A. N.; Collaboration: NANOGrav Collaboration; and others

    2014-10-20

    We perform a search for continuous gravitational waves from individual supermassive black hole binaries using robust frequentist and Bayesian techniques. We augment standard pulsar timing models with the addition of time-variable dispersion measure and frequency variable pulse shape terms. We apply our techniques to the Five Year Data Release from the North American Nanohertz Observatory for Gravitational Waves. We find that there is no evidence for the presence of a detectable continuous gravitational wave; however, we can use these data to place the most constraining upper limits to date on the strength of such gravitational waves. Using the full 17 pulsar data set we place a 95% upper limit on the strain amplitude of h {sub 0} ≲ 3.0 × 10{sup –14} at a frequency of 10 nHz. Furthermore, we place 95% sky-averaged lower limits on the luminosity distance to such gravitational wave sources, finding that d{sub L} ≳ 425 Mpc for sources at a frequency of 10 nHz and chirp mass 10{sup 10} M {sub ☉}. We find that for gravitational wave sources near our best timed pulsars in the sky, the sensitivity of the pulsar timing array is increased by a factor of ∼four over the sky-averaged sensitivity. Finally we place limits on the coalescence rate of the most massive supermassive black hole binaries.

  3. Gravitational radiation from primordial solitons and soliton-star binaries

    NASA Technical Reports Server (NTRS)

    Gleiser, Marcelo

    1989-01-01

    The possibility that both the formation of nontopological solitons in a primordial second-order phase transition and binary systems of soliton stars could generate a stochastic gravitational-wave background is examined. The present contribution of gravitational radiation to the energy density of the universe from these processes is estimated for a number of different models. The detectability of such contributions from the timing measurements of the millisecond pulsar and spaceborne laser interferometry is briefly discussed and compared to other cosmological and local sources of background gravitational waves.

  4. Gravitational radiation from magnetically funneled supernova fallback onto a magnetar

    SciTech Connect

    Melatos, A.; Priymak, M. E-mail: m.priymak@pgrad.unimelb.edu.au

    2014-10-20

    Protomagnetars spun up to millisecond rotation periods by supernova fallback are predicted to radiate gravitational waves via hydrodynamic instabilities for ∼10{sup 2} s before possibly collapsing to form a black hole. It is shown that magnetic funneling of the accretion flow (1) creates a magnetically confined polar mountain, which boosts the gravitational wave signal, and (2) 'buries' the magnetic dipole moment, delaying the propeller phase and assisting black hole formation.

  5. Arm locking for space-based laser interferometry gravitational wave observatories

    NASA Astrophysics Data System (ADS)

    Yu, Yinan; Mitryk, Shawn; Mueller, Guido

    2014-09-01

    Laser frequency stabilization is a critical part of the interferometry measurement system of space-based gravitational wave observatories such as the Laser Interferometer Space Antenna (LISA). Arm locking as a proposed frequency stabilization technique transfers the stability of the long arm lengths to the laser frequency. The arm locking sensor synthesizes an adequately filtered linear combination of the interspacecraft phase measurements to estimate the laser frequency noise, which can be used to control the laser frequency. At the University of Florida we developed the hardware-based University of Florida LISA Interferometer Simulator to study and verify laser frequency noise reduction and suppression techniques under realistic LISA-like conditions. These conditions include the variable Doppler shifts among the spacecraft, LISA-like signal travel times, optical transponders, realistic laser frequency, and timing noise. We review the different types of arm locking sensors and discuss their expected performance in LISA. The presented results are supported by results obtained during experimental studies of arm locking under relevant LISA-like conditions. We measured the noise suppression as well as initial transients and frequency pulling in the presence of Doppler frequency errors. This work has demonstrated the validity and feasibility of arm locking in LISA.

  6. Accretion Acceleration of Neutron Stars and Effects of Gravitational Radiation

    NASA Astrophysics Data System (ADS)

    Fu, Yan-yan; Zhang, Yue-zhu; Wei, Yi-huan; Zhang, Cheng-min; Yu, Shao-hua; Pan, Yuan-yue; Guo, Yuan-qi; Wang, De-hua

    2016-01-01

    In this paper we studied the neutron star's spin acceleration in the accretion process of the neutron star binary system, and the relation how the spin period changes with the accreted mass. We analyzed further the evolutions of both magnetic field and spin period of a neutron star, and compared the modeled results with the observational data of pulsars, to show that they are consistent with each other. Based on above studies, we investigated the effect of gravitational radiation on the spin-up process of a neutron star, and derived the change rate of the neutron star's spin period in the accretion process. We also estimated the critical angular velocity Ωcr, at which the accretion torque is balanced by that of gravitational radiation, and discussed the influence of gravitational radiation on the neutron star's spin evolution.

  7. Gravitational radiation from a cylindrical naked singularity

    SciTech Connect

    Nakao, Ken-ichi; Morisawa, Yoshiyuki

    2005-06-15

    We construct an approximate solution which describes the gravitational emission from a naked singularity formed by the gravitational collapse of a cylindrical thick shell composed of dust. The assumed situation is that the collapsing speed of the dust is very large. In this situation, the metric variables are obtained approximately by a kind of linear perturbation analysis in the background Morgan solution which describes the motion of cylindrical null dust. The most important problem in this study is what boundary conditions for metric and matter variables should be imposed at the naked singularity. We find a boundary condition that all the metric and matter variables are everywhere finite at least up to the first order approximation. This implies that the spacetime singularity formed by this high-speed dust collapse is very similar to that formed by the null dust and the final singularity will be a conical one. Weyl curvature is completely released from the collapsed dust.

  8. Gravitational radiation from preheating with many fields

    SciTech Connect

    Jr, John T. Giblin; Price, Larry R.; Siemens, Xavier E-mail: larry@gravity.phys.uwm.edu

    2010-08-01

    Parametric resonances provide a mechanism by which particles can be created just after inflation. Thus far, attention has focused on a single or many inflaton fields coupled to a single scalar field. However, generically we expect the inflaton to couple to many other relativistic degrees of freedom present in the early universe. Using simulations in an expanding Friedmann-Lemaître-Robertson-Walker spacetime, in this paper we show how preheating is affected by the addition of multiple fields coupled to the inflaton. We focus our attention on gravitational wave production — an important potential observational signature of the preheating stage. We find that preheating and its gravitational wave signature is robust to the coupling of the inflaton to more matter fields.

  9. Gravitational radiation theory. M.A. Thesis - Rice Univ.; [survey of current research

    NASA Technical Reports Server (NTRS)

    Wilson, T. L.

    1973-01-01

    A survey is presented of current research in the theory of gravitational radiation. The mathematical structure of gravitational radiation is stressed. Furthermore, the radiation problem is treated independently from other problems in gravitation. The development proceeds candidly through three points of view - scalar, rector, and tensor radiation theory - and the corresponding results are stated.

  10. Gravitational radiation from first-order phase transitions

    SciTech Connect

    Child, Hillary L.; Giblin, John T. Jr. E-mail: giblinj@kenyon.edu

    2012-10-01

    It is believed that first-order phase transitions at or around the GUT scale will produce high-frequency gravitational radiation. This radiation is a consequence of the collisions and coalescence of multiple bubbles during the transition. We employ high-resolution lattice simulations to numerically evolve a system of bubbles using only scalar fields, track the anisotropic stress during the process and evolve the metric perturbations associated with gravitational radiation. Although the radiation produced during the bubble collisions has previously been estimated, we find that the coalescence phase enhances this radiation even in the absence of a coupled fluid or turbulence. We comment on how these simulations scale and propose that the same enhancement should be found at the Electroweak scale; this modification should make direct detection of a first-order electroweak phase transition easier.

  11. Gravitational radiation from rotating monopole-string systems

    SciTech Connect

    Babichev, E.; Dokuchaev, V.; Kachelriess, M.

    2005-02-15

    We study the gravitational radiation from a rotating monopole-antimonopole pair connected by a string. While at not too high frequencies the emitted gravitational spectrum is described asymptotically by P{sub n}{proportional_to}n{sup -1}, the spectrum is exponentially suppressed in the high-frequency limit, P{sub n}{proportional_to}exp(-n/n{sub cr}). Below n{sub cr}, the emitted spectrum of gravitational waves is very similar to the case of an oscillating monopole pair connected by a string, and we argue, therefore, that the spectrum found holds approximately for any moving monopole-string system. As an application, we discuss the stochastic gravitational wave background generated by monopole-antimonopole pairs connected by strings in the early Universe and gravitational wave bursts emitted at present by monopole-string networks. We confirm that advanced gravitational wave detectors have the potential to detect a signal for string tensions as small as G{mu}{approx}10{sup -13}.

  12. Imprints of relic gravitational waves in cosmic microwave background radiation

    NASA Astrophysics Data System (ADS)

    Baskaran, D.; Grishchuk, L. P.; Polnarev, A. G.

    2006-10-01

    A strong variable gravitational field of the very early Universe inevitably generates relic gravitational waves by amplifying their zero-point quantum oscillations. We begin our discussion by contrasting the concepts of relic gravitational waves and inflationary “tensor modes”. We explain and summarize the properties of relic gravitational waves that are needed to derive their effects on cosmic microwave background (CMB) temperature and polarization anisotropies. The radiation field is characterized by four invariants I, V, E, B. We reduce the radiative transfer equations to a single integral equation of Voltairre type and solve it analytically and numerically. We formulate the correlation functions CℓXX' for X, X'=T, E, B and derive their amplitudes, shapes and oscillatory features. Although all of our main conclusions are supported by exact numerical calculations, we obtain them, in effect, analytically by developing and using accurate approximations. We show that the TE correlation at lower ℓ’s must be negative (i.e. an anticorrelation), if it is caused by gravitational waves, and positive if it is caused by density perturbations. This difference in TE correlation may be a signature more valuable observationally than the lack or presence of the BB correlation, since the TE signal is about 100 times stronger than the expected BB signal. We discuss the detection by WMAP of the TE anticorrelation at ℓ≈30 and show that such an anticorrelation is possible only in the presence of a significant amount of relic gravitational waves (within the framework of all other common assumptions). We propose models containing considerable amounts of relic gravitational waves that are consistent with the measured TT, TE and EE correlations.

  13. Inertia, gravitation, and radiation time delays

    SciTech Connect

    Graneau, P.

    1987-05-01

    This note explains how an instantaneous action-at-a-distance theory gives rise to time delays between a cause in one location and its effect at another. The key to this is a suitable law of induction which itself does not produce the time delay, but contains the cause in the form of a time derivative. The many-body solution process for an array of simultaneous induction equations then reveals retardation between cause and effect without the transport of energy at finite velocity. It is suggested that a suitable law of induction of inertia applied to an object in the solar system and the many-body universe may furnish the quantitative connection between inertia and Newtonian gravitation.

  14. Gravitational radiation and the ultimate speed in Rosen's bimetric theory of gravity

    NASA Technical Reports Server (NTRS)

    Caves, C. M.

    1980-01-01

    In Rosen's bimetric theory of gravity the (local) speed of gravitational radiation is determined by the combined effects of cosmological boundary values and nearby concentrations of matter. It is possible for the speed of gravitational radiation to be less than the speed of light. It is here shown that the emission of gravitational radiation prevents particles of nonzero rest mass from exceeding the speed of gravitational radiation. Observations of relativistic particles place limits on the speed of gravitational radiation and the cosmological boundary values today, and observations of synchroton radiation from compact radio sources place limits on the cosmological boundary values in the past.

  15. Gravitational anomaly and Hawking radiation near a weakly isolated horizon

    SciTech Connect

    Wu Xiaoning; Huang Chaoguang; Sun Jiarui

    2008-06-15

    Based on the idea of the work by Wilczek and his collaborators, we consider the gravitational anomaly near a weakly isolated horizon. We find that there exists a universal choice of tortoise coordinate for any weakly isolated horizon. Under this coordinate, the leading behavior of a quite arbitrary scalar field near a horizon is a 2-dimensional chiral scalar field. This means we can extend the idea of Wilczek and his collaborators to more general cases and show the relation between gravitational anomaly and Hawking radiation is a universal property of a black hole horizon.

  16. Gravitational anomaly and Hawking radiation near a weakly isolated horizon

    NASA Astrophysics Data System (ADS)

    Wu, Xiaoning; Huang, Chao-Guang; Sun, Jia-Rui

    2008-06-01

    Based on the idea of the work by Wilczek and his collaborators, we consider the gravitational anomaly near a weakly isolated horizon. We find that there exists a universal choice of tortoise coordinate for any weakly isolated horizon. Under this coordinate, the leading behavior of a quite arbitrary scalar field near a horizon is a 2-dimensional chiral scalar field. This means we can extend the idea of Wilczek and his collaborators to more general cases and show the relation between gravitational anomaly and Hawking radiation is a universal property of a black hole horizon.

  17. Radiation from highly relativistic geodesics. [gravitational wave generation

    NASA Technical Reports Server (NTRS)

    Misner, C. W.

    1974-01-01

    A number of recent works are reviewed concerning the generation and emission of gravitational waves. It is shown that at high frequencies, the generation of gravitational radiation is a local phenomenon. Two examples are described illustrating this generation when a high-energy particle collides against the space-time curvature. One, after Matzner and Nutku, uses a method of virtual photons; the other, after Chrzanowski and Misner, is based on the W.K.B. approximation, corresponding to geometric optics, for the inhomogeneous wave equation. This method uses a factorized integral representation of the Green function which is valid asymptotically to infinity in space.

  18. Mission and Instrument Design Trades for a Space-based Gravitational Wave Observatory to Maximize Science Return

    NASA Astrophysics Data System (ADS)

    Livas, Jeffrey; Baker, John; Stebbins, Robin; Thorpe, James; Larson, Shane; Sesana, Alberto

    2016-03-01

    A space-based gravitational wave observatory is required to access the rich array of astrophysical sources expected at frequencies between 0.0001 and 0.1 Hz. The European Space Agency (ESA) chose the Gravitational Universe as the science theme of its L3 launch opportunity. A call for mission proposals will be released soon after the completion of the LISA Pathfinder (LPF) mission. LPF is scheduled to start science operations in March 2016, and finish by the end of the year, so an optimized mission concept is needed now. There are a number of possible design choices for both the instrument and the mission. One of the goals for a good mission design is to maximize the science return while minimizing risk and keeping costs low. This presentation will review some of the main design choices for a LISA-like laser interferometry mission and the impact of these choices on cost, risk, and science return.

  19. Method for numerical relativity: simulation of axisymmetric gravitational collapse and gravitational radiation generation

    SciTech Connect

    Evans, C.R. II

    1984-01-01

    A method is presented that allows fully self-consistent numerical simulation of asymptotically flat axisymmetric nonrotating general relativistic systems. These techniques were developed to model and understand resulting relativistic effects in gravitational core collapse and gravitational radiation generation. Both vacuum (Brill) spacetimes and matter-filled configurations can be treated. The author uses the (3 + 1) composition of Arnowitt, Deser, and Misner to write general relativity in a dynamical form. The conformal approach, including the transverse-traceless decomposition of extrinsic curvature due to York, is used to solve the initial-value problem. In addition, these techniques are extended to provide a fully constrained evolution scheme. Several new boundary conditions, applied at large but finite radius, are derived for the elliptic constraint equations. The method uses a simplifying three-gauge, placing the metric in quasi-isotropic form. The resulting three-metric contains only two components that must be solved. One, the conformal factor, is fixed by the Hamiltonian constraint. The second has nice radiative features and is related in the weak-field limit to the usual transverse-traceless gravitational wave amplitude. The time slicing is determined by implementation of the maximal slicing condition.

  20. Thermal Stability Analysis for a Heliocentric Gravitational Radiation Detection Mission

    NASA Technical Reports Server (NTRS)

    Folkner, W.; McElroy, P.; Miyake, R.; Bender, P.; Stebbins, R.; Supper, W.

    1994-01-01

    The Laser Interferometer Space Antenna (LISA) mission is designed for detailed studies of low-frequency gravitational radiation. The mission is currently a candidate for ESA's post-Horizon 2000 program. Thermal noise affects the measurement in at least two ways. Thermal variation of the length of the optical cavity to which the lasers are stabilized introduces phase variations in the interferometer signal, which have to be corrected for by using data from the two arms separately.

  1. Gravitational-wave radiation from double compact objects with eLISA in the Galaxy

    NASA Astrophysics Data System (ADS)

    Liu, Jinzhong; Zhang, Yu

    2014-03-01

    The phase of inspiral of double compact objects (DCOs: NS + WD, NS + NS, BH + NS, and BH + BH binaries) in the disk field population of the Galaxy provides a potential source in the frequency range from 10-4 to 0.1 Hz, which can be detected by the European New Gravitational Observatory (NGO: eLISA is derived from the previous LISA proposal) project. In this frequency range, much stronger gravitational wave (GW) radiation can be obtained from DCO sources because they possess more mass than other compact binaries (e.g., close double white dwarfs). In this study, we aim to calculate the gravitational wave signals from the resolvable DCO sources in the Galaxy using a binary population synthesis approach, and determine physical properties of these binaries using Monte Carlo simulations. Combining the sensitivity curve of the eLISA detector and a confusion-limited noise floor of close double white dwarfs, we find that only a handful of DCO sources can be detected by the eLISA detector. The detectable number of DCO sources reaches 160; in the context of low-frequency eLISA observations we find that the number of NS + WD, NS + NS, BH + NS, and BH + BH objects are 132, 16, 3, and 6, respectively.

  2. A method for numerical relativity: Simulation of axisymmetric gravitational collapse and gravitational radiation generation

    NASA Astrophysics Data System (ADS)

    Evans, C. R., II

    A method is presented which allows fully self-consistent numerical simulation of asymptotically flat axisymmetric nonrotating general relativistic systems. These techniques have been developed to model and understand resulting relativistic effects in gravitational core collapse and gravitational radiation generation. Both vacuum (Brill) spacetimes and matter-filled configurations can be treated. The (3 + 1) decomposition of Arnowitt, Deser and Misner is used to write general relativity in a dynamical form. The conformal approach, including the transverse-traceless decomposition of extrinsic curvature due to York, is used to solve the initial value problem. In addition, these techniques are extended to provide a fully constrained evolution scheme. Several new boundary conditions, applied at large but finite radius, are derived for the elliptic constraint equations. This method uses a simplifying three-gauge, placing the metric in quasi-isotropic form.

  3. Gravitational Radiation from Compact Binary Pulsars

    NASA Astrophysics Data System (ADS)

    Antoniadis, John

    An outstanding question in modern Physics is whether general relativity (GR) is a complete description of gravity among bodies at macroscopic scales. Currently, the best experiments supporting this hypothesis are based on high-precision timing of radio pulsars. This chapter reviews recent advances in the field with a focus on compact binary millisecond pulsars with white-dwarf (WD) companions. These systems—if modeled properly—provide an unparalleled test ground for physically motivated alternatives to GR that deviate significantly in the strong-field regime. Recent improvements in observational techniques and advances in our understanding of WD interiors have allowed for a series of precise mass measurements is such systems. These masses, combined with high-precision radio timing of the pulsars, result to stringent constraints on the radiative properties of gravity, qualitatively very different from what was available in the past.

  4. Influence of gravitation on the propagation of electromagnetic radiation

    NASA Technical Reports Server (NTRS)

    Mashhoon, B.

    1975-01-01

    The existence of a general helicity-rotation coupling is demonstrated for electromagnetic waves propagating in the field of a slowly rotating body and in the Goedel universe. This coupling leads to differential focusing of circularly polarized radiation by a gravitational field which is detectable for a rapidly rotating collapsed body. The electromagnetic perturbations and their frequency spectrum are given for the Goedel universe. The spectrum of frequencies is bounded from below by the characteristic rotation frequency of the Goedel universe. If the universe were rotating, the differential focusing effect would be extremely small due to the present upper limit on the anisotropy of the microwave background radiation.

  5. Gravitational radiation in Bianchi Type V cosmological models

    SciTech Connect

    Hogan, P.A.

    1988-01-01

    This paper is concerned with the development of the theory of embedding gravitational radiation fields in expanding universes pioneered by Hawking. The problem of embedding such fields in the expanding Friedmann-Lemaitre-Robertson-Walker dust-filled universe, considered by Hawking, is reexamined in a new formalism which permits an easy analysis, in particular, of the relationship between the boundary conditions and the satisfaction, by the Weyl tensor, of the conventional peeling-off behavior. Since gravity wave detectors are expected to pick up plane-fronted gravitational waves, the main thrust of this paper concerns the development of a formulation of Bianchi Type V cosmological models which enables the embedding of such plane-fronted waves to be carried out. This is worked out explicitly in the case of a perfect fluid, with pressure proportional to energy density, and with the histories of the fluid particles orthogonal to the surfaces of homogeneity. 18 references.

  6. Observational limits on a millihertz stochastic background of gravitational radiation

    SciTech Connect

    Boughn, S.P.; Vanhook, S.J.; O'neill, C.M. Princeton Univ., NJ )

    1990-05-01

    An analysis of 100 station years of quiet seismic data shows no evidence of the excitation of earth by a stochastic background of gravitational radiation. The absence of excitation of the two quadrupole modes which couple most strongly to gravitational waves (GWs) implies 1 sigma upper limts on a GW background of 1.7 x 10 to the -5th J/cu cm Hz and 6.1 x 10 to the -6th J/cu m Hz at frequencies of 0.31 mHz and 1.72 mHz, respectively. Although these limits are factors of 1300 and 33 lower than previous limits at these frequencies they are both above the critical density of the universe per octave and are, therefore, relatively uninteresting from a cosmological point of view. 15 refs.

  7. High-Precision Lunar Ranging and Gravitational Parameter Estimation With the Apache Point Observatory Lunar Laser-ranging Operation

    NASA Astrophysics Data System (ADS)

    Johnson, Nathan H.

    This dissertation is concerned with several problems of instrumentation and data analysis encountered by the Apache Point Observatory Lunar Laser-ranging Operation. Chapter 2 considers crosstalk between elements of a single-photon avalanche photodiode detector. Experimental and analytic methods were developed to determine crosstalk rates, and empirical findings are presented. Chapter 3 details electronics developments that have improved the quality of data collected by detectors of the same type. Chapter 4 explores the challenges of estimating gravitational parameters on the basis of ranging data collected by this and other experiments and presents resampling techniques for the derivation of standard errors for estimates of such parameters determined by the Planetary Ephemeris Program (PEP), a solar-system model and data-fitting code. Possible directions for future work are discussed in Chapter 5. A manual of instructions for working with PEP is presented as an appendix.

  8. Escape of gravitational radiation from the field of massive bodies

    NASA Technical Reports Server (NTRS)

    Price, Richard H.; Pullin, Jorge; Kundu, Prasun K.

    1993-01-01

    We consider a compact source of gravitational waves of frequency omega in or near a massive spherically symmetric distribution of matter or a black hole. Recent calculations have led to apparently contradictory results for the influence of the massive body on the propagation of the waves. We show here that the results are in fact consistent and in agreement with the 'standard' viewpoint in which the high-frequency compact source produces the radiation as if in a flat background, and the background curvature affects the propagation of these waves.

  9. Gravitational radiation reaction and inspiral waveforms in the adiabatic limit.

    PubMed

    Hughes, Scott A; Drasco, Steve; Flanagan, Eanna E; Franklin, Joel

    2005-06-10

    We describe progress evolving an important limit of binaries in general relativity: stellar mass compact objects spiraling into much larger black holes. Such systems are of great observational interest. We have developed tools to compute for the first time the radiation from generic orbits. Using global conservation laws, we find the orbital evolution and waveforms for special cases. For generic orbits, inspirals and waveforms can be found by augmenting our approach with an adiabatic self-force rule due to Mino. Such waveforms should be accurate enough for gravitational-wave searches. PMID:16090377

  10. Gravitational Radiation Characteristics of Nonspinning Black-Hole Binaries

    NASA Technical Reports Server (NTRS)

    Kelly, B. J.; Baker, J. G.; Boggs, W. D.; Centrella, J. M.; vanMeter, J. R.; McWilliams, S. T.

    2008-01-01

    We present a detailed descriptive analysis of the gravitational radiation from binary mergers of non-spinning black holes, based on numerical relativity simulations of systems varying from equal-mass to a 6:1 mass ratio. Our analysis covers amplitude and phase characteristics of the radiation, suggesting a unified picture of the waveforms' dominant features in terms of an implicit rotating source, applying uniformly to the full wavetrain, from inspiral through ringdown. We construct a model of the late-stage frequency evolution that fits the l = m modes, and identify late-time relationships between waveform frequency and amplitude. These relationships allow us to construct a predictive model for the late-time waveforms, an alternative to the common practice of modelling by a sum of quasinormal mode overtones. We demonstrate an application of this in a new effective-one-body-based analytic waveform model.

  11. Gravitational Radiation Characteristics of Nonspinning Black-Hole Binaries

    NASA Technical Reports Server (NTRS)

    Kelly, Barnard

    2008-01-01

    "We present a detailed descriptive analysis of the gravitational radiation from binary mergers of non-spinning black holes, based on numerical relativity simulations of systems varying from equal-mass to a 6:1 mass ratio. Our analysis covers amplitude and phase characteristics of the radiation, suggesting a unified picture of the waveforms' dominant features in terms of an implicit rotating source. applying uniformly to the full wavetrain, from inspiral through ringdown. We construct a model of the late-stage frequency evolution that fits the $\\ell = m$ modes, and identify late-time relationships between waveform frequency and amplitude. These relationships allow us to construct a predictive model for the late-time waveforms, an alternative to the common practice of modelling by a sum of quasinormal mode overtones. We demonstrate an application of this in a new effective-one-body-based analytic waveform model."

  12. Space-Based Gravitational-Wave Observatory (SGO) Mission Concept Study

    NASA Technical Reports Server (NTRS)

    Livas, Jeffrey; McNamara, Paul; Jennrich, Oliver

    2012-01-01

    The LISA Mission Concept has been under study for over two decades as a space-based gravitational-wave detector capable of observing astrophysical sources in the 0.0001 to 1 Hz band. The concept has consistently received strong recommendations from various review panels based on the expected science, most recently from the US Astr02010 Decadal Review. Budget constraints have led both the US and European Space agencies to search for lower cost options. We report results from the US effort to explore the tradeoffs between mission cost and science return.

  13. Linking electromagnetic and gravitational radiation in coalescing binary neutron stars

    NASA Astrophysics Data System (ADS)

    Palenzuela, Carlos; Lehner, Luis; Liebling, Steven L.; Ponce, Marcelo; Anderson, Matthew; Neilsen, David; Motl, Patrick

    2013-08-01

    We expand on our study of the gravitational and electromagnetic emissions from the late stage of an inspiraling neutron star binary as presented in Palenzuela et al. [Phys. Rev. Lett. 111, 061105 (2013)]. Interactions between the stellar magnetospheres, driven by the extreme dynamics of the merger, can yield considerable outflows. We study the gravitational and electromagnetic waves produced during the inspiral and merger of a binary neutron star system using a full relativistic, resistive magnetohydrodynamics evolution code. We show that the interaction between the stellar magnetospheres extracts kinetic energy from the system and powers radiative Poynting flux and heat dissipation. These features depend strongly on the configuration of the initial stellar magnetic moments. Our results indicate that this power can strongly outshine pulsars in binaries and have a distinctive angular and time-dependent pattern. Our discussion provides more detail than Palenzuela et al., showing clear evidence of the different effects taking place during the inspiral. Our simulations include a few milliseconds after the actual merger and study the dynamics of the magnetic fields during the formation of the hypermassive neutron star. We also briefly discuss the possibility of observing such emissions.

  14. Critical phenomena in the aspherical gravitational collapse of radiation fluids

    NASA Astrophysics Data System (ADS)

    Baumgarte, Thomas W.; Montero, Pedro J.

    2015-12-01

    We study critical phenomena in the gravitational collapse of a radiation fluid. We perform numerical simulations in both spherical symmetry and axisymmetry, and observe critical scaling in both supercritical evolutions, which lead to the formation of a black hole, and subcritical evolutions, in which case the fluid disperses to infinity and leaves behind flat space. We identify the critical solution in spherically symmetric collapse, find evidence for its universality, and study the approach to this critical solution in the absence of spherical symmetry. For the cases that we consider, aspherical deviations from the spherically symmetric critical solution decay in damped oscillations in a manner that is consistent with the behavior found by Gundlach in perturbative calculations. Our simulations are performed with an unconstrained evolution code, implemented in spherical polar coordinates, and adopting "moving-puncture" coordinates.

  15. Nonlinear solutions of long-wavelength gravitational radiation

    NASA Astrophysics Data System (ADS)

    Salopek, D. S.

    1991-05-01

    In a significant improvement over homogeneous minisuperspace models, it is shown that the classical nonlinear evolution of inhomogeneous scalar fields and the metric is tractable when the wavelength of the fluctuations is larger than the Hubble radius. Neglecting second-order spatial gradients, one can solve the energy constraint as well as the evolution equations by invoking a transformation to new canonical variables. The Hamilton-Jacobi equation is separable and complete solutions are given for gravitational radiation and multiple scalar fields interacting through an exponential potential. Although the time parameter is arbitrary, the natural choice is the determinant of the three-metric. The momentum constraint may be simply expressed in terms of the new canonical variables which define the spatial coordinates. The long-wavelength analysis is essential for a proper formulation of stochastic inflation which enables one to model non-Gaussian primordial fluctuations for structure formation.

  16. Synchrotron Radiation from Outer Space and the Chandra X-Ray Observatory

    NASA Technical Reports Server (NTRS)

    Weisskopf, M. C.

    2006-01-01

    The universe provides numerous extremely interesting astrophysical sources of synchrotron X radiation. The Chandra X-ray Observatory and other X-ray missions provide powerful probes of these and other cosmic X-ray sources. Chandra is the X-ray component of NASA's Great Observatory Program which also includes the Hubble Space telescope, the Spitzer Infrared Telescope Facility, and the now defunct Compton Gamma-Ray Observatory. The Chandra X-Ray Observatory provides the best angular resolution (sub-arcsecond) of any previous, current, or planned (for the foreseeable near future) space-based X-ray instrumentation. We present here a brief overview of the technical capability of this X-Ray observatory and some of the remarkable discoveries involving cosmic synchrotron sources.

  17. Gravitational radiation damping and the three-body problem

    NASA Astrophysics Data System (ADS)

    Wardell, Zachary Edward

    2003-11-01

    A model of three-body motion is developed which includes the effects of gravitational radiation reaction. The radiation reaction due to the emission of gravitational waves is the only post-Newtonian effect that is included here. For simplicity, all of the motion is taken to be planar. Two of the masses are viewed as a binary system and the third mass, whose motion will be a fixed orbit around the center-of-mass of the binary system, is viewed as a perturbation. This model aims to describe the motion of a relativistic binary pulsar that is perturbed by a third mass. Numerical integration of this simplified model reveals that given the right initial conditions and parameters one can see resonances. These (m, n) resonances are defined by the resonance condition, mω = 2 nΩ, where m and n are relatively prime integers and ω and Ω are the angular frequencies of the binary orbit and third mass orbit (around the center-of- mass of the binary), respectively. The resonance condition consequently fixes a value for the semimajor axis of the binary orbit for the duration of the resonance; therefore, the binary energy remains constant on the average while its angular momentum changes during the resonance. Numerical integration of an equation of relative motion that approximates the binary gives evidence of such resonances. This paper outlines a method of averaging developed by Chicone, Mashhoon, and Retzloff which renders a nonlinear system that undergoes resonance capture into a mathematically amenable form. This method is applied to the present system and one arrives at an analytical solution that describes the average motion during resonance. Furthermore, prominent features of the full nonlinear system, such as the frequency of oscillation and antidamping, accord with their analytically derived formulae.

  18. Electrodynamics of Radiating Charges in a Gravitational Field

    NASA Astrophysics Data System (ADS)

    Grøn, Øyvind

    The electrodynamics of a radiating charge and its electromagnetic field based upon the Lorentz-Abraham-Dirac (LAD) equation are discussed both with reference to an inertial reference frame and a uniformly accelerated reference frame. It is demonstrated that energy and momentum are conserved during runaway motion of a radiating charge and during free fall of a charge in a field of gravity. This does not mean that runaway motion is really happening. It may be an unphysical solution of the LAD equation of motion of a radiating charge due to the unrealistic point particle model of the charge upon which it is based. However it demonstrates the consistency of classical electrodynamics, including the LAD equation which is deduced from Maxwell's equations and the principle of energy-momentum conservation applied to a radiating charge and its electromagnetic field. The decisive role of the Schott energy in this connection is made clear and an answer is given to the question: What sort of energy is the Schott energy and where is it found? It is the part of the electromagnetic field energy which is proportional to (minus) the scalar product of the velocity and acceleration of a moving accelerated charged particle. In the case of the electromagnetic field of a point charge it is localized at the particle. This energy is negative if the acceleration is in the same direction as the velocity and positive if it is in the opposite direction. During runaway motion the Schott energy becomes more and more negative and in the case of a charged particle with finite extension, it is localized in a region with increasing extension surrounding the particle. The Schott energy provides the radiated energy of a freely falling charge. Also it is pointed out that a proton and a neutron fall with the same acceleration in a uniform gravitational field, although the proton radiates and the neutron does not. It is made clear that the question as to whether or not a charge radiates has a reference

  19. Compact vibration isolation and suspension for Australian International Gravitational Observatory: performance in a 72 m Fabry Perot cavity.

    PubMed

    Barriga, P; Dumas, J C; Woolley, A A; Zhao, C; Blair, D G

    2009-11-01

    This paper describes the first demonstration of vibration isolation and suspension systems, which have been developed with view to application in the proposed Australian International Gravitational Observatory. In order to achieve optimal performance at low frequencies new components and techniques have been combined to create a compact advanced vibration isolator structure. The design includes two stages of horizontal preisolation and one stage of vertical preisolation with resonant frequencies approximately 100 mHz. The nested structure facilitates a compact design and enables horizontal preisolation stages to be configured to create a superspring configuration, where active feedback can enable performance close to the limit set by seismic tilt coupling. The preisolation stages are combined with multistage three-dimensional (3D) pendulums. Two isolators suspending mirror test masses have been developed to form a 72 m optical cavity with finesse approximately 700 in order to test their performance. The suitability of the isolators for use in suspended optical cavities is demonstrated through their ease of locking, long term stability, and low residual motion. An accompanying paper presents the local control system and shows how simple upgrades can substantially improve residual motion performance. PMID:19947743

  20. Investigation of Advanced Resonant-Mass Gravitational Radiation Detectors

    NASA Astrophysics Data System (ADS)

    Zhou, Zhiqing

    1994-01-01

    The sensitivity of resonant-mass gravitational radiation detectors depends on both the antenna cross-section and the detector noise. The cross-section is determined by the sound velocity VS and density rho of the antenna material, as well as the antenna geometry. The principal detector noise sources are thermal Nyquist noise and noise due to the readout electromechanical amplifier. The cross-section is proportional to rho V_sp{S}{5} for a given frequency and antenna geometry while the thermal noise is inversely proportional to the antenna's mechanical quality factor Q for a given temperature. Materials with high VS could, in principle, provide about a hundred-fold increase in the antenna cross -section as compared to current generation detectors. In this dissertation we report the results of measurements of the temperature-dependent mechanical losses in several suitable high sound velocity materials. The results show that the signal-to-noise ratios of detectors made of these materials could be improved by a factor of 15 to 100 at 4 K as compared to current detectors with aluminum antennas. A spherical gravitational wave antenna is very promising for gravitational wave astronomy because of its large cross-section, isotropic sky coverage, and the capability it can provide for determining the wave direction. In this dissertation several aspects of spherical detectors, including the eigenfunctions and eigenfrequencies of the normal-modes of an elastic sphere, the energy cross-section, and the response functions that are used to obtain the noise-free solution to the inverse problem are discussed. Using the maximum likelihood estimation method the inverse problem in the presence of noise is solved. We also determine the false-alarm probability and the detection probability for a network of spherical detectors and estimate the detectable event rates for supernovae core collapses and binary coalescences. Six identical cylindrical detectors, with a suitable arrangement of

  1. Spacecraft to Spacecraft Coherent Laser Tracking as a Xylophone Interferometer Detector of Gravitational Radiation

    NASA Technical Reports Server (NTRS)

    Tinto, M.

    1998-01-01

    Searches for gravitational radiation can be performed in space with two spacecraft tracking each other with coherent laser light. This experimental technique could be implemented with two spacecraft carrying an appropriate optical payload, or with the proposed broad-band, space-based laser interferometer detectors of gravitational waves operated in this non-interferometric mode.

  2. Spacecraft Doppler Tracking as a Xylophone Detector of Gravitational Radiation

    NASA Technical Reports Server (NTRS)

    Tinto, M.

    1995-01-01

    Spacecraft Doppler tracking is discussed for detecting gravitational waves in which Doppler data recorded on the ground are linearly combined with Doppler measurements made on board a spacecraft. A new method is derived for removing from combined data the frequency fluctuations due to the Earth troposphere, ionosphere, and mechanical vibrations of the antenna on the ground. The remaining non-zero gravitational wave signal could be used for detecting gravitational waves.

  3. r-mode instability: Analytical solution with gravitational radiation reaction

    SciTech Connect

    Dias, Oscar J.C.; Sa, Paulo M.

    2005-07-15

    Analytical r-mode solutions are investigated within the linearized theory in the case of a slowly rotating, Newtonian, barotropic, nonmagnetized, perfect-fluid star in which the gravitational radiation (GR) reaction force is present. For the GR reaction term we use the 3.5 post-Newtonian order expansion of the GR force, in order to include the contribution of the current quadrupole moment. We find the explicit expression for the r-mode velocity perturbations and we conclude that they are sinusoidal with the same frequency as the well-known GR force-free linear r-mode solution, and that the GR force drives the r-modes unstable with a growth time scale that agrees with the expression first found by Lindblom, Owen, and Morsink. We also show that the amplitude of these velocity perturbations is corrected, relatively to the GR force-free case, by a term of order {omega}{sup 6}, where {omega} is the angular velocity of the star.

  4. Managing radiation degradation of CCDs on the Chandra X-ray Observatory II

    NASA Technical Reports Server (NTRS)

    O'Dell, Stephen L.; Aldcroft, Thomas L.; Bissell, Bradley A.; Blackwell, William C.; Cameron, Robert A.; Chappell, Jon II.; DePasquale, Joseph M.; Gage, Kenneth R.; Grant, Catherine E.; Harbison, Christine F.

    2005-01-01

    The CCDs on the Chandra X-ray Observatory are vulnerable to radiation damage from low-energy protons scattered off the telescope's mirrors onto the focal plane. Following unexpected damage incurred early in the mission, the Chandra Team developed, implemented, and maintains a radiation-protection program. This program - involving scheduled radiation safing during radiation-belt passes, intervention based upon real-time space-weather conditions and radiation-environment modeling, and on-board radiation monitoring with autonomous radiation safing - has successfully managed the radiation damage to the CCDs. Since implementing the program, the charge-transfer inefficiency (CTI) has increased at an average annual rate of only 2.9x10^-6 (2.3%) for the front- illuminated CCDs and 0.95x10^-6 (6.5%) for the back-illuminated CCDs. This paper describes the current status of Chandra radiation-management program.

  5. Search for correlations between the University of Maryland and the University of Rome gravitational radiation antennas

    SciTech Connect

    Ferrari, V.; Pizzella, G.; Lee, M.; Weber, J.

    1982-05-15

    Results are presented for analyses of the outputs of gravitational radiation antennas in Rome and in Maryland during July 1978. These data give evidence for an external background exciting both antennas.

  6. On the contribution of a stochastic background of gravitational radiation to the timing noise of pulsars

    NASA Technical Reports Server (NTRS)

    Mashhoon, B.

    1982-01-01

    The influence of a stochastic and isotropic background of gravitational radiation on timing measurements of pulsars is investigated, and it is shown that pulsar timing noise may be used to establish a significant upper limit of about 10 to the -10th on the total energy density of very long-wavelength stochastic gravitational waves. This places restriction on the strength of very long wavelength gravitational waves in the Friedmann model, and such a background is expected to have no significant effect on the approximately 3 K electromagnetic background radiation or on the dynamics of a cluster of galaxies.

  7. Using ACIS on the Chandra X-ray Observatory as a Particle Radiation Monitor II

    NASA Technical Reports Server (NTRS)

    Grant, C. E.; Ford, P. G.; Bautz, M. W.; ODell, S. L.

    2012-01-01

    The Advanced CCD Imaging Spectrometer is an instrument on the Chandra X-ray Observatory. CCDs are vulnerable to radiation damage, particularly by soft protons in the radiation belts and solar storms. The Chandra team has implemented procedures to protect ACIS during high-radiation events including autonomous protection triggered by an on-board radiation monitor. Elevated temperatures have reduced the effectiveness of the on-board monitor. The ACIS team has developed an algorithm which uses data from the CCDs themselves to detect periods of high radiation and a flight software patch to apply this algorithm is currently active on-board the instrument. In this paper, we explore the ACIS response to particle radiation through comparisons to a number of external measures of the radiation environment. We hope to better understand the efficiency of the algorithm as a function of the flux and spectrum of the particles and the time-profile of the radiation event.

  8. Managing Radiation Degradation of CCDs on the Chandra X-ray Observatory

    NASA Technical Reports Server (NTRS)

    ODell, Stephen L.; Blackwell, William C.; Minow, Joseph I.; Cameron, Robert A.; Morris, David C.; Virani, Shanil N.; Six, N. Frank (Technical Monitor)

    2002-01-01

    The CCDs on the Chandra X ray Observatory are sensitive to radiation damage particularly from low-energy protons scattering off the telescope's mirrors onto the focal plane. In its highly elliptical orbit, Chandra passes through a spatially and temporally varying radiation environment, ranging from the radiation belts to the solar wind. Translating thc Advanced CCD Imaging Spectrometer (ACIS) out of the focal position during radiation-belt passages has prevented loss of scientific utility and eventually functionality. However, carefully managing the radiation damage during the remainder of the orbit, without unnecessarily sacrificing observing time, is essential to optimizing the scientific value of this exceptional observatory throughout its planned 10-year mission. In working toward this optimization, the Chandra team developed aid applied radiation-management strategies. These strategies include autonomous instrument safing triggered by the on-board radiation monitor, as well as monitoring, alerts, and intervention based upon real-time space-environment data from NOAA and NASA spacecraft. Furthermore, because Chandra often spends much of its orbit out of the solar wind (in the Earth's outer magnetosphere and magnetosheath), the team developed the Chandra Radiation Model to describe the complete low-energy-proton environment. Management of the radiation damage has thus far succeeded in limiting degradation of the charge-transfer inefficiency (CTI) to less than 4.4*10^-6 and 1.4*10^-6 per year for the front-illuminated and back-illuminated CCDs, respectively.

  9. Shelter from the Storm: Protecting the Chandra X-ray Observatory from Radiation

    NASA Astrophysics Data System (ADS)

    Cameron, Robert A.; Morris, David C.; Virani, Shanil N.; Wolk, Scott J.; Blackwell, William C.; Minow, Joseph I.; O'dell, Stephen L.

    NASA's Chandra X-ray Observatory was launched in July 1999, and the first images were recorded by the ACIS x-ray detector in August 1999. Shortly after first light, degradation of the energy resolution and charge transfer efficiency in the ACIS CCD detectors was observed, and this was quickly attributed to cumulative particle radiation damage in the CCD's, in particular from 100 keV to 200 keV protons. Since the onset of this radiation damage to ACIS, several improvements have been made to autonomous Chandra operation and ground-based operations and mission planning, to limit the effects of radiation while preserving optimum observing efficiency for the Observatory. These changes include implementing an automatic science instrument radiation protection system on Chandra, implementing a real-time radiation monitoring and alert system by the Science Operations Team, and improving the radiation prediction models used in mission planning for the Observatory. These satellite- and ground-based systems provide protection for Chandra from passages through the Earth's trapped radiation belts and outer magnetosphere and from flares and coronal mass ejections from the Sun. We describe the design and performance of the automatic on-board radiation protection system on Chandra, and the ground-based software systems and data products for real-time radiation monitoring. We also describe the development and characterize the performance of the Chandra Radiation Model (CRM), which provides predictions of the solar wind and magnetospheric proton fluxes along Chandra's orbit, indexed by the geomagnetic activity index, Kp. We compare the observed and predicted damage rates to ACIS based on net mission proton fluence, and outline planned enhancements to the CRM.

  10. A Giant Leap Towards a Space-based Gravitational-Wave Observatory: LISA Pathfinder, the LISA Test Package, and ST7-DRS

    NASA Astrophysics Data System (ADS)

    Thorpe, James; McNamara, Paul; Ziemer, John; LPF Team, LTP Team, ST7-DRS Team

    2015-01-01

    The science case for a space-based gravitational wave instrument observing in the milliHertz band covers a wide area of topics in astrophysics and fundamental physics including galaxy formation and evolution, black hole growth, compact object demographics, gravitational physics, and cosmology. This strong science case is largely responsible for the high rankings received by the Laser Interferometer Space Antenna (LISA) mission in major reviews in both the US and Europe. A key element of the development of LISA is the LISA Pathfinder (LPF) technology demonstrator mission, which will launch in the coming year. Led by ESA and a consortium of European national agencies and with a minority contribution from NASA, LPF will demonstrate several key technologies for the LISA concept. LPF includes two scientific payloads: the European LISA Technology Package (LTP) and the NASA-provided ST7-DRS. The mission will place two test masses in drag-free flight and measure the relative acceleration between them. This measurement will validate a number of technologies that are critical to LISA-like gravitational wave instruments including sensing and control of the test masses, drag-free control laws, micro-Newton thrusters, and picometer-level laser metrology. We will present an overview of the LISA Pathfinder mission, the LTP and ST7-DRS payloads, and their expected impact on the larger effort to realize a space-based gravitational wave observatory.

  11. The Chandra X-Ray Observatory Radiation Environment Model

    NASA Technical Reports Server (NTRS)

    Blackwell, W. C.; Minow, Joseph I.; Smith, Shawn; Swift, Wesley R.; ODell, Stephen L.; Cameron, Robert A.

    2003-01-01

    CRMFLX (Chandra Radiation Model of ion FluX) is an environmental risk mitigation tool for use as a decision aid in planning the operations times for Chandra's Advanced CCD Imaging Spectrometer (ACIS) detector. The accurate prediction of the proton flux environment with energies of 100 - 200 keV is needed in order to protect the ACIS detector against proton degradation. Unfortunately, protons of this energy are abundant in the region of space Chandra must operate, and the on-board Electron, Proton, and Helium Instrument (EPHIN) does not measure proton flux levels of the required energy range. In addition to the concerns arising from the radiation belts, substorm injections of plasma from the magnetotail may increase the protons flux by orders of magnitude in this energy range. The Earth's magnetosphere is a dynamic entity, with the size and location of the magnetopause driven by the highly variable solar wind parameters (number density, velocity, and magnetic field components). Operational times for the telescope must be made weeks in advance, decisions which are complicated by the variability of the environment. CRMFLX is an engineering model developed to address these problems and provides proton flux and fluence statistics for the terrestrial outer magnetosphere, magnetosheath, and solar wind for use in scheduling ACIS operations. CRMFLX implements a number of standard models to predict the bow shock, magnetopause, and plasma sheet boundaries based on the sampling of historical solar wind data sets. Measurements from the GEOTAIL and POLAR spacecraft are used to create the proton flux database. This paper describes the recently released CRMFLX v2 implementation that includes an algorithm that propagates flux from an observation location to other regions of the magnetosphere based on convective ExB and VB-curvature particle drift motions in electric and magnetic fields. This technique has the advantage of more completely filling out the database and makes maximum

  12. Gravitational radiation from binary neutron star mergers: Magnetic and microphysical effects

    NASA Astrophysics Data System (ADS)

    Neilsen, David; Anderson, Matthew; Lehner, Luis; Liebling, Steven L.; Motl, Patrick; Palenzuela, Carlos; Ponce, Marcelo

    2015-04-01

    Binary neutron star mergers will be important sources of gravitational radiation for Advanced LIGO. Understanding how different physical processes-such as magnetic and microphysical effects due to equations of state or neutrino cooling-are imprinted on the radiation is important for learning more about these systems. We perform a series of binary neutron star mergers to examine some of these effects on the gravitational radiation. We use three different realistic equations of state, ranging from soft to stiff, initially magnetized stars, and include neutrino cooling of the post-merger system using a leakage scheme. We discuss possible observational signatures for these systems.

  13. Study of gravitational radiation from cosmic domain walls

    SciTech Connect

    Kawasaki, Masahiro; Saikawa, Ken'ichi E-mail: saikawa@icrr.u-tokyo.ac.jp

    2011-09-01

    In this paper, following the previous study, we evaluate the spectrum of gravitational wave background generated by domain walls which are produced if some discrete symmetry is spontaneously broken in the early universe. We apply two methods to calculate the gravitational wave spectrum: One is to calculate the gravitational wave spectrum directly from numerical simulations, and another is to calculate it indirectly by estimating the unequal time anisotropic stress power spectrum of the scalar field. Both analysises indicate that the slope of the spectrum changes at two characteristic frequencies corresponding to the Hubble radius at the decay of domain walls and the width of domain walls, and that the spectrum between these two characteristic frequencies becomes flat or slightly red tilted. The second method enables us to evaluate the GW spectrum for the frequencies which cannot be resolved in the finite box lattice simulations, but relies on the assumptions for the unequal time correlations of the source.

  14. Spin-down of Pulsars, and Their Electromagnetic and Gravitational Wave Radiations

    NASA Astrophysics Data System (ADS)

    Yue-zhu, Zhang; Yan-yan, Fu; Yi-huan, Wei; Cheng-min, Zhang; Shao-hua, Yu; Yuan-yue, Pan; Yuan-qi, Guo; De-hua, Wang

    2016-04-01

    Pulsars posses extremely strong magnetic fields, and their magnetic axis does not coincide with their rotation axis, this causes the pulsars to emit electromagnetic radiations. Pulsars rely on their rotational energy to compensate for the energy loss caused by the electromagnetic radiation, which leads to the gradually decelerated spin of pulsars. According to the theoretical deduction, we have calculated the initial period of the Crab Nebula pulsar, and derived the period evolution of the pulsar at any time in the future under the effect of the electromagnetic radiation. Considered the possible existence of quadrupole moment in the mass distribution of a pulsar, the gravitational wave radiation will also make the pulsar spin down, hence the variation of spin period of the Crab pulsar under the effect of gravitational wave radiation is further analyzed. Finally, combining the two kinds of radiation mechanisms, the evolution of spin period of the Crab pulsar under the joint action of these two kinds of radiation mechanisms is analyzed.

  15. Prospects for detection of gravitational radiation by simultaneous Doppler tracking of several spacecraft

    NASA Technical Reports Server (NTRS)

    Estabrook, F. B.; Wahlquist, H. D.

    1978-01-01

    This paper reports a calculation of the effect of gravitational radiation on the observed Doppler shift of a sinusoidal electromagnetic signal transmitted to, and coherently transponded from, distant spacecraft. It is found that the effect of plane gravitational waves on such observations is not intuitively immediate, and in fact depends sensitively on the spacecraft direction, which suggests the possibility of detecting such plane waves by simultaneous Doppler tracking of several spacecraft. The need for broad band gravitational wave observations, the required stabilities of time keeping standards, and astrophysical sources expected in the Very Low Frequency band are briefly discussed.

  16. Astronomical polarization studies at radio and infrared wavelengths. Part 1: Gravitational deflection of polarized radiation

    NASA Technical Reports Server (NTRS)

    Dennison, B. K.

    1976-01-01

    The gravitational field is probed in a search for polarization dependence in the light bending. This involves searching for a splitting of a source image into orthogonal polarizations as the radiation passes through the solar gravitational field. This search was carried out using the techniques of very long and intermediate baseline interferometry, and by seeking a relative phase delay in orthogonal polarizations of microwaves passing through the solar gravitational field. In this last technique a change in the total polarization of the Helios 1 carrier wave was sought as the spacecraft passed behind the sun. No polarization splitting was detected.

  17. A study of the seasonal variations of the Chandra X-ray Observatory radiation model

    NASA Astrophysics Data System (ADS)

    DePasquale, Joseph M.; Virani, Shanil N.; Schwartz, Daniel A.; Cameron, Robert A.; Plucinsky, Paul P.; O'Dell, Stephen L.; Minow, Joseph I.; Blackwell, William C., Jr.

    2004-02-01

    The Chandra X-ray Observatory (CXO), launched in July of 1999, contains two focal-plane imaging detectors and two transmission-grating spectrometers. Maintaining an optimal performance level for the observatory is the job of the Chandra X-ray Center (CXC), located in Cambridge, MA. One very important aspect of the observatory's performance is the science observing efficiency. The single largest factor which reduces the observing efficiency of the observatory is the interruption of observations due to passage through the Earth's radiation belts approximately every 2 2/3 days. During radiation belt passages, observations are suspended on average for over 15 hours and the Advanced CCD Imaging Spectrometer (ACIS) is moved out of the focus of the telescope to minimize damage from low-energy (100-200 keV) protons. The CXC has been using the National Space Science Data Center's "near Earth" AE-8/AP-8 radiation belt model to predict the entry and exit from the radiation belts. However, it was discovered early in the mission that the AE-8/AP-8 model predictions were inadequate for science scheduling purposes and a 10ks "pad time" was introduced on ingress and egress of perigee to ensure protection from radiation damage. This pad time, totaling 20 ks per orbit, has recently been the subject of much analysis to determine if it can be reduced to maximize science observing efficiency. A recent analysis evaluating a possible correlation between the Chandra Radiation Model (CRM) and the Electron Proton Helium Instrument (EPHIN) found a greatest lower bound (GLB) in lieu of a correlation for the ingress and egress of each perigee. The GLB is a limit imposed on the CRM such that when the CRM exceeds this limit on ingress, this defines the new safing time and similarly for egress. We have shown that using this method we can regain a significant amount of lost science time at the expense of minimal radiation exposure. The GLB analysis also found that different GLB's produce varied

  18. Gravitational radiation from the radial infall of highly relativistic point particles into Kerr black holes

    NASA Astrophysics Data System (ADS)

    Cardoso, Vitor; Lemos, José P.

    2003-04-01

    In this paper, we consider the gravitational radiation generated by the collision of highly relativistic particles with rotating Kerr black holes. We use the Sasaki-Nakamura formalism to compute the waveform, energy spectra, and total energy radiated during this process. We show that the gravitational spectrum for high-energy collisions has definite characteristic universal features, which are independent of the spin of the colliding objects. We also discuss the possible connections between these results and black-hole black-hole collisions at the speed of light. Our results show that during the high-speed collision of a nonrotating hole with a rotating one, at most 35% of the total energy can get converted into gravitational waves. This 35% efficiency occurs only in the most optimistic situation, that of a zero impact parameter collision, along the equatorial plane, with an almost extreme Kerr black hole. In the general situation, the total gravitational energy radiated is expected to be much less, especially if the impact parameter increases. Thus, if one is able to produce black holes at the CERN Large Hadron Collider, at most 35% of the partons’ energy should be emitted during the so-called balding phase. This energy will be missing, since we do not have gravitational wave detectors able to measure such amplitudes. The collision at the speed of light between one rotating black hole and a nonrotating one or two rotating black holes turns out to be the most efficient gravitational wave generator in the Universe.

  19. Detecting a Non-Gaussian Stochastic Background of Gravitational Radiation

    NASA Astrophysics Data System (ADS)

    Drasco, Steve; Flanagan, Éanna É.

    2002-12-01

    We derive a detection method for a stochastic background of gravitational waves produced by events where the ratio of the average time between events to the average duration of an event is large. Such a signal would sound something like popcorn popping. Our derivation is based on the somewhat unrealistic assumption that the duration of an event is smaller than the detector time resolution.

  20. Analysis of spatial mode sensitivity of a gravitational wave interferometer and a targeted search for gravitational radiation from the Crab pulsar

    NASA Astrophysics Data System (ADS)

    Betzwieser, Joseph

    Over the last several years the Laser Interferometer Gravitational Wave Observatory (LIGO) has been making steady progress in improving the sensitivities of its three interferometers, two in Hanford, Washington, and one in Livingston, Louisiana. These interferometers have reached their target design sensitivities and have since been collecting data in their fifth science run for well over a year. On the way to increasing the sensitivities of the interferometers, difficulties with increasing the input laser power, due to unexpectedly high optical absorption, required the installation of a thermal compensation system. We describe a frequency resolving wave-front sensor, called the phase camera, which was used on the interferometer to examine the heating effects and corrections of the thermal compensation system. The phase camera was also used to help understand an output mode cleaner which was temporarily installed on the Hanford 4km interferometer. Data from the operational detectors was used to carry out two continuous gravitational wave searches directed at isolated neutron stars. The first, targeted RX J1856.5-3754, now known to be outside the LIGO detection band, was used as a test of a new multi-interferometer search code, and compared it to a well tested single interferometer search pulsar, over a physically motivated parameter space, to complement existing narrow time domain searches. The parameter space was chosen based on computational constraints, expected final sensitivity, and possible frequency differences due to free precession and a simple two component model. An upper limit on the strain of gravitational radiation from the Crab pulsar of 1.6 × 10^-24 was found with 95% confidence over a frequency band of 6 × 10^-3 Hz centered on twice the Crab pulsar's electromagnetic pulse frequency of 29.78 Hz. At the edges of the parameter space, this search is approximately 10^5 times more sensitive than the time domain searches. This is a preliminary result

  1. Using ACIS on the Chandra X-ray Observatory as a Particle Radiation Monitor

    NASA Astrophysics Data System (ADS)

    Grant, Catherine E.; Ford, P. G.; Bautz, M. W.; O'Dell, S. L.

    2013-04-01

    The Advanced CCD Imaging Spectrometer (ACIS) is one of two focal-plane instruments on the Chandra X-ray Observatory. The CCDs are vulnerable to radiation damage, particularly by soft protons in the Earth's radiation belts and from solar storms. The primary effect of this damage is to increase the charge-transfer inefficiency (CTI) of the 8 front-illuminated CCDs and decrease scientific performance. Soon after launch, the Chandra team implemented procedures to protect ACIS and remove the detector from the telescope focus during high-radiation events: planned protection during radiation-belt transits; autonomous protection triggered by an on-board radiation monitor; and manual intervention based upon assessment of space-weather conditions. As Chandra's multilayer insulation ages, elevated temperatures have reduced the effectiveness of the on-board radiation monitor for autonomous protection. The ACIS team has developed an algorithm which uses data from the CCDs themselves to detect periods of high radiation and a flight software patch to apply this algorithm is currently active on-board the instrument. We report on the status of this flight software patch and explore the ACIS response to particle radiation through comparisons to a number of external measures of the radiation environment. We hope to better understand the efficiency of the algorithm as a function of the flux and spectrum of the particles and the time-profile of the radiation event.

  2. INTEGRATED SACHS-WOLFE EFFECT FOR GRAVITATIONAL RADIATION

    SciTech Connect

    Laguna, Pablo; Larson, Shane L.; Spergel, David; Yunes, Nicolas

    2010-05-20

    Gravitational waves (GWs) are messengers carrying valuable information about their sources. For sources at cosmological distances, the waves will also contain the imprint left by the intervening matter. The situation is in close analogy with cosmic microwave photons, for which the large-scale structures the photons traverse contribute to the observed temperature anisotropies, in a process known as the integrated Sachs-Wolfe effect. We derive the GW counterpart of this effect for waves propagating on a Friedman-Robertson-Walker background with scalar perturbations. We find that the phase, frequency, and amplitude of the GWs experience Sachs-Wolfe-type integrated effects, in addition to the magnification effects on the amplitude from gravitational lensing. We show that for supermassive black hole binaries, the integrated effects could account for measurable changes on the frequency, chirp mass, and luminosity distance of the binary, thus unveiling the presence of inhomogeneities, and potentially dark energy, in the universe.

  3. HEAD I: Gravitational Radiation From Astrophysical Sources Introduction

    NASA Astrophysics Data System (ADS)

    Harding, A. K.

    1998-12-01

    There has been significant progress recently in improving the sensitivity of searches for gravitational waves. The thresholds of new detectors being planned or under construction may for the first time reach predicted levels of gravity waves from coalescing neutron stars. Space-based detectors may be sensitive to signals from coalescing massive black holes. This session will present aspects of both expected predictions, current measurements and future expectations for gravity wave detection.

  4. Gravitational radiation from neutron stars deformed by crustal Hall drift

    NASA Astrophysics Data System (ADS)

    Suvorov, A. G.; Mastrano, A.; Geppert, U.

    2016-07-01

    A precondition for the radio emission of pulsars is the existence of strong, small-scale magnetic field structures (`magnetic spots') in the polar cap region. Their creation can proceed via crustal Hall drift out of two qualitatively and quantitatively different initial magnetic field configurations: a field confined completely to the crust and another which penetrates the whole star. The aim of this study is to explore whether these magnetic structures in the crust can deform the star sufficiently to make it an observable source of gravitational waves. We model the evolution of these field configurations, which can develop, within ˜104-105 yr, magnetic spots with local surface field strengths ˜1014 G maintained over ≳106 yr. Deformations caused by the magnetic forces are calculated. We show that, under favourable initial conditions, a star undergoing crustal Hall drift can have ellipticity ɛ ˜ 10-6, even with sub-magnetar polar field strengths, after ˜105 yr. A pulsar rotating at ˜102 Hz with such ɛ is a promising gravitational wave source candidate. Since such large deformations can be caused only by a particular magnetic field configuration that penetrates the whole star and whose maximum magnetic energy is concentrated in the outer core region, gravitational wave emission observed from radio pulsars can thus inform us about the internal field structures of young neutron stars.

  5. Exploring the Physics of Compact Objects with Gravitational-Wave Astronomy

    NASA Astrophysics Data System (ADS)

    Brown, Duncan

    2016-03-01

    The Advanced Laser Interferometer Gravitational Wave Observatory (LIGO) has recently completed its first observing run. Future observations of gravitational waves by LIGO will open a new field in astronomy. The gravitational waves radiated by binaries containing neutron stars and/or black holes contain information about strong field gravity and the properties of dense matter. In this talk I will discuss the nuclear and gravitational physics that can be learned from the observation of compact-object mergers

  6. Managing Radiation Degradation of CCDs on the Chandra X-Ray Observatory--III

    NASA Technical Reports Server (NTRS)

    O'Dell, Stephen L.; Aldcroft, Thomas L.; Blackwell, William C.; Bucher, Sabina L.; Chappell, Jon H.; DePasquale, Joseph M.; Grant, Catherine E.; Juda, Michael; Martin, Eric R.; Minow, Joseph I.; Murray, Stephen S.; Plucinsky, Paul P.; Shropshire, Daniel P.; Spitzbart, Bradley J.; Viens, Paul R.; Wolk, Scott J.; Schwartz, Daniel A.

    2007-01-01

    The CCDs on the Chandra X-ray Observatory are vulnerable to radiation damage from low-energy protons scattered off the telescope's mirrors onto the focal plane. Following unexpected damage incurred early in the mission, the Chandra team developed, implemented, and maintains a radiation-protection program. This program--involving scheduled radiation safing during radiation-belt passes, intervention based upon real-time space-weather conditions and radiation-environment modeling, and on-board radiation monitoring with autonomous radiation safing--has successfully managed the radiation damage to the CCDs. Since implementing the program, the charge-transfer inefficiency (CTI) has increased at an average annual rate of only 3.2x 10(exp -6) (2.3 percent) for the front-illuminated CCDs and 1.0x10(exp -6) (6.7 percent) for the back-illuminated CCDs. This paper describes the current status of the Chandra radiation-management program, emphasizing enhancements implemented since the previous papers.

  7. Gravitational Radiation from Post-Newtonian Sources and Inspiralling Compact Binaries

    NASA Astrophysics Data System (ADS)

    Blanchet, Luc

    2014-02-01

    To be observed and analyzed by the network of gravitational wave detectors on ground (LIGO, VIRGO, etc.) and by the future detectors in space (eLISA, etc.), inspiralling compact binaries -- binary star systems composed of neutron stars and/or black holes in their late stage of evolution -- require high-accuracy templates predicted by general relativity theory. The gravitational waves emitted by these very relativistic systems can be accurately modelled using a high-order post-Newtonian gravitational wave generation formalism. In this article, we present the current state of the art on post-Newtonian methods as applied to the dynamics and gravitational radiation of general matter sources (including the radiation reaction back onto the source) and inspiralling compact binaries. We describe the post-Newtonian equations of motion of compact binaries and the associated Lagrangian and Hamiltonian formalisms, paying attention to the self-field regularizations at work in the calculations. Several notions of innermost circular orbits are discussed. We estimate the accuracy of the post-Newtonian approximation and make a comparison with numerical computations of the gravitational self-force for compact binaries in the small mass ratio limit. The gravitational waveform and energy flux are obtained to high post-Newtonian order and the binary's orbital phase evolution is deduced from an energy balance argument. Some landmark results are given in the case of eccentric compact binaries -- moving on quasi-elliptical orbits with non-negligible eccentricity. The spins of the two black holes play an important role in the definition of the gravitational wave templates. We investigate their imprint on the equations of motion and gravitational wave phasing up to high post-Newtonian order (restricting to spin-orbit effects which are linear in spins), and analyze the post-Newtonian spin precession equations as well as the induced precession of the orbital plane.

  8. Gravitational radiation from binary systems in alternative metric theories of gravity - Dipole radiation and the binary pulsar

    NASA Technical Reports Server (NTRS)

    Will, C. M.

    1977-01-01

    The generation of gravitational radiation in several currently viable metric theories of gravitation (Brans-Dicke, Rosen, Ni, and Lightman-Lee) is analyzed, and it is shown that these theories predict the emission of dipole gravitational radiation from systems containing gravitationally bound objects. In the binary system PSR 1913 + 16, this radiation results in a secular change in the orbital period of the system with a nominal magnitude of 3 parts in 100,000 per year. The size of the effect is proportional to the reduced mass of the system, to the square of the difference in (self-gravitational energy)/(mass) between the two components of the system, and to a parameter, xi, whose value varies from theory to theory. In general relativity xi equals 0, in Rosen's (1973) theory xi equals -20/3, and in Ni's (1973) theory xi equals -400/3. The current upper limit on such a secular period change is one part in 1 million per year. It is shown that further observations of the binary system that tighten this limit and that establish the masses of the components and the identity of the companion may provide a crucial test of otherwise viable alternatives to general relativity.

  9. Chandra X-Ray Observatory's Radiation Environment and the AP-8/AE-8 Model

    NASA Technical Reports Server (NTRS)

    Virani, S. N.; Plucinsky, P. P.; Butt, Y. M.; Mueller-Mellin, R.

    2000-01-01

    The Chandra X-ray Observatory (CXO) was launched on July 23, 1999 and reached its final orbit on August 7, 1999. The CXO is in a highly elliptical orbit, approximately 140,000 km x 10,000 km, and has a period of roughly 63.5 hours (approx. 2.6 days). It transits the Earth's Van Allen belts once per orbit during which no science observations can be performed due to the high radiation environment. The Chandra X-ray Observatory Center (CXC) currently uses the National Space Science Data Center's "near Earth" AP-8/AE-8 radiation belt model to predict the start and end times of passage through the radiation belts. However, our scheduling software only uses a simple dipole model of the Earth's magnetic field. The resulting B, L magnet coordinates, do not always give sufficiently accurate predictions of the start and end times of transit of the Van Allen belts. We show this by comparing to the data from Chandra's on-board radiation monitor, the EPHIN (Electron, Proton, Helium Instrument particle detector) instrument. We present evidence that demonstrates this mis- of the radiation belts as well as data that also demonstrate the significant variability of one radiation belt transit to the next as experienced by the CXO. We present an explanation for why the dipole implementation of the AP-8/AE-8 gives inaccurate results. We are also investigating use of the Magnetospheric Specification and Forecast Model (MSM) - a model that also accounts for radiation belt variability and geometry.

  10. The space microwave interferometer and the search for cosmic background gravitational wave radiation

    NASA Technical Reports Server (NTRS)

    Anderson, Allen Joel

    1989-01-01

    Present and planned investigations which use interplanetary spacecraft for gravitational wave searches are severely limited in their detection capability. This limitation has to do both with the Earth-based tracking procedures used and with the configuration of the experiments themselves. It is suggested that a much improved experiment can now be made using a multiarm interferometer designed with current operating elements. An important source of gravitational wave radiation, the cosmic background, may well be within reach of detection with these procedures. It is proposed to make a number of experimental steps that can now be carried out using TDRSS spacecraft and would conclude in the establishment of an operating multiarm microwave interferometer. This interferometer is projected to have a sensitivity to cosmic background gravitational wave radiation with an energy of less than 10(exp -4) cosmic closure density and to periodic waves generating spatial strain approaching 10(exp -19) in the range 0.1 to 0.001 Hz.

  11. Center of mass and spin for isolated sources of gravitational radiation

    NASA Astrophysics Data System (ADS)

    Kozameh, Carlos N.; Quiroga, Gonzalo D.

    2016-03-01

    We define the center of mass and spin of an isolated system in general relativity. The resulting relationships between these variables and the total linear and angular momentum of the gravitational system are remarkably similar to their Newtonian counterparts, though only variables at the null boundary of an asymptotically flat spacetime are used for their definition. We also derive equations of motion linking their time evolution to the emitted gravitational radiation. The results are then compared to other approaches. In particular, one obtains unexpected similarities as well as some differences with results obtained in the post-Newtonian literature. These equations of motion should be useful when describing the radiation emitted by compact sources, such as coalescing binaries capable of producing gravitational kicks, supernovas, or scattering of compact objects.

  12. Improving the Science Observing Efficiency of the Chandra X-ray Observatory via Chandra Radiation

    NASA Technical Reports Server (NTRS)

    Virani, Shanil; Schwartz, Daniel; Cameron, Robert; Plucinsky, Paul; ODell, Stephen; Minow, Joseph; Blackwell, William

    2003-01-01

    The Chandra X-ray Observatory (CXO), NASA' latest "Great Observatory", swas launched on July 23, 1999 and reached its final orbit on August 7, 1999. The CXO is in a highly elliptical orbit, approximately 140,000 km x 10,000 km, and has a period of approximately 63.5 hours (approx. 2.65 days). It transits the Earth's Van Allen belts once per orbit during which no science observations can be performed due to the high radiation environment. The Chandra X-ray Observatory Center currently uses the National Space Science Data Center's "near Earth" AP-8/AE-8 radiation belt model to predict the start and end times of passage through the radiation belts. Our earlier analysis demonstrated that our implementation of the AP-8/AE-8 model (a simple dipole model of the Earth's magnetic field) does not always give sufficiently accurate predictions of the start and end times of transit of the Van Allen belts. This led to a change in our operating procedure whereby we "padded" the start and end times of transit by 10 kiloseconds (ks) so that ACIS, the primary science instrument on-board Chandra, would not be exposed to the "fringes" of the Van Allen belts on ingress and egress for any given transit. This additional 20 ks per orbit during which Chandra is unable to perform science observations sums to approximately 3 Ms of "lost" science time per year and therefore reduces the science observing efficiency of the Observatory. To address the need for a higher fidelity radiation model appropriate for the Chandra orbit, the Chandra Radiation Model (CRM) was developed. The CRM is an ion model for the outer magnetosphere and is based on data from the EPIC/ICS instrument on-board the Geotail satellite as well as data from the CEPPAD/IPS instrument on-board the Polar satellite. With the production and implementation of the CRM, we present the results of a study designed to investigate the science observing time that may be recovered by using the CRM as a function of the additional low

  13. Gravitational radiation from compact binaries in scalar-tensor gravity

    NASA Astrophysics Data System (ADS)

    Lang, R. N.

    2015-05-01

    General relativity (GR) has been extensively tested in the solar system and in binary pulsars, but never in the strong-field, dynamical regime. Soon, gravitational-wave (GW) detectors like Advanced LIGO and eLISA will be able to probe this regime by measuring GWs from inspiraling and merging compact binaries. One particularly interesting alternative to GR is scalar-tensor gravity. We present progress in the calculation of second post-Newtonian (2PN) gravitational waveforms for inspiraling compact binaries in a general class of scalar- tensor theories. The waveforms are constructed using a standard GR method known as “direct integration of the relaxed Einstein equations,” appropriately adapted to the scalar-tensor case. We find that differences from general relativity can be characterized by a reasonably small number of parameters. Among the differences are new hereditary terms which depend on the past history of the source. In one special case, binary black hole systems, we find that the waveform is indistinguishable from that of general relativity. In another, mixed black hole- neutron star systems, all differences from GR can be characterized by only a single parameter.

  14. Gravitational radiation from compact binaries in scalar-tensor gravity

    NASA Astrophysics Data System (ADS)

    Lang, Ryan

    2014-03-01

    General relativity (GR) has been extensively tested in the solar system and in binary pulsars, but never in the strong-field, dynamical regime. Soon, gravitational-wave (GW) detectors like Advanced LIGO will be able to probe this regime by measuring GWs from inspiraling and merging compact binaries. One particularly interesting alternative to GR is scalar-tensor gravity. We present the calculation of second post-Newtonian (2PN) gravitational waveforms for inspiraling compact binaries in a general class of scalar-tensor theories. The waveforms are constructed using a standard GR method known as ``Direct Integration of the Relaxed Einstein equations,'' appropriately adapted to the scalar-tensor case. We find that differences from general relativity can be characterized by a reasonably small number of parameters. Among the differences are new hereditary terms which depend on the past history of the source. In one special case, mixed black hole-neutron star systems, all differences from GR can be characterized by only a single parameter. In another, binary black hole systems, we find that the waveform is indistinguishable from that of general relativity.

  15. Naked singularities in non-self-similar gravitational collapse of radiation shells

    SciTech Connect

    Joshi, P.S.; Dwivedi, I.H. )

    1992-03-15

    Non-self-similar gravitational collapse of imploding radiation is shown to give rise to a strong curvature naked singularity. The conditions are specified for the singularity to be globally naked and the strength of the same is examined along nonspacelike curves and along all the families of nonspacelike geodesics terminating at the singularity in the past.

  16. Spacecraft Doppler Tracking as a Narrow-Band Detector of Gravitational Radiation

    NASA Technical Reports Server (NTRS)

    Tinto, M.; Armstrong, J. W.

    1998-01-01

    We discuss a filtering technique for reducing the frequency fluctuations due to the troposphere, ionosphere, and mechanical vibrations of the ground antenna in spacecraft Doppler tracking searches for gravitational radiation. This method takes advantage of the sinusoidal behavior of the transfer function to the Doppler observable of these noise sources, which displays sharp nulls at selected Fourier components.

  17. Bianchi type-I magnetized radiating cosmological model in self creation theory of gravitation

    NASA Astrophysics Data System (ADS)

    Jain, Vimal Chand; Jain, Nikhil

    2015-06-01

    We have investigated Bianchi type-I cosmological model in the presence of magnetized field with disordered radiation in Barber's second self-creation theory of gravitation. To obtain exact solution we assume that the component of shear tensor is proportional to expansion ( θ). Some geometrical and physical properties of the model have also been discussed.

  18. DETECTION OF IMBHs WITH GROUND-BASED GRAVITATIONAL WAVE OBSERVATORIES: A BIOGRAPHY OF A BINARY OF BLACK HOLES, FROM BIRTH TO DEATH

    SciTech Connect

    Amaro-Seoane, Pau; Santamaria, LucIa E-mail: Lucia.Santamaria@aei.mpg.d

    2010-10-20

    Even though the existence of intermediate-mass black holes (IMBHs; black holes with masses ranging between 10{sup 2} M{sub sun} and 10{sup 4} M{sub sun}) has not yet been corroborated observationally, these objects are of high interest for astrophysics. Our understanding of the formation and evolution of supermassive black holes, as well as galaxy evolution modeling and cosmography would dramatically change if an IMBH were to be observed. From the point of view of traditional photon-based astronomy, which relies on the monitoring of innermost stellar kinematics, the direct detection of an IMBH seems to be rather far in the future. However, the prospect of the detection and characterization of an IMBH has good chances in lower frequency gravitational-wave (GW) astrophysics using ground-based detectors such as the Laser Interferometer Gravitational-Wave Observatory (LIGO), Virgo, and the future Einstein Telescope (ET). We present an analysis of the signal of a system of a binary of IMBHs based on a waveform model obtained with numerical relativity simulations coupled with post-Newtonian calculations at the highest available order. IMBH binaries with total masses between 200 and 20,000 M{sub sun} would produce significant signal-to-noise ratios in Advanced LIGO and Virgo and the ET. We have computed the expected event rate of IMBH binary coalescences for different configurations of the binary, finding interesting values that depend on the spin of the IMBHs. The prospects for IMBH detection and characterization with ground-based GW observatories would not only provide us with a robust test of general relativity, but would also corroborate the existence of these systems. Such detections should allow astrophysicists to probe the stellar environments of IMBHs and their formation processes.

  19. Gravitational Radiation of a Vibrating Physical String as a Model for the Gravitational Emission of an Astrophysical Plasma

    NASA Astrophysics Data System (ADS)

    Lewis, Ray A.; Modanese, Giovanni

    Vibrating media offer an important testing ground for reconciling conflicts between General Relativity, Quantum Mechanics and other branches of physics. For sources like a Weber bar, the standard covariant formalism for elastic bodies can be applied. The vibrating string, however, is a source of gravitational waves which requires novel computational techniques, based on the explicit construction of a conserved and renormalized energy-momentum tensor. Renormalization (in a classical sense) is necessary to take into account the effect of external constraints, which affect the emission considerably. Our computation also relaxes usual simplifying assumptions like far-field approximation, spherical or plane wave symmetry, TT gauge and absence of internal interference. In a further step towards unification, the method is then adapted to give the radiation field of a transversal Alfven wave in a rarefied astrophysical plasma, where the tension is produced by an external static magnetic field.

  20. Gravitational radiation from inspiralling compact binaries completed at the third post-Newtonian order.

    PubMed

    Blanchet, Luc; Damour, Thibault; Esposito-Farèse, Gilles; Iyer, Bala R

    2004-08-27

    The gravitational radiation from point particle binaries is computed at the third post-Newtonian (3PN) approximation of general relativity. Three previously introduced ambiguity parameters, coming from the Hadamard self-field regularization of the 3PN source-type mass quadrupole moment, are consistently determined by means of dimensional regularization, and proved to have the values xi=-9871/9240, kappa=0, and zeta=-7/33. These results complete the derivation of the general relativistic prediction for compact binary inspiral up to 3.5PN order, and should be of use for searching and deciphering the signals in the current network of gravitational wave detectors. PMID:15447090

  1. Gravitational radiation from a particle in bound orbit around a black hole; relativistic correction

    NASA Astrophysics Data System (ADS)

    Tiwari, Ashok; Khanal, Udayaraj

    2016-05-01

    Gravitational radiation from a system of two body, one as test particle and other as black hole (we assume, mi is mass of the test particle and m 2 is mass of black hole in bound orbits (orbital eccentricities e < 1) and E 2 < 1; E is the energy, is calculated with relativistic correction using the method of inertia tensor and multipole formalism. Plots of power versus eccentricity of the bound orbit of first kind are presented, and average total power radiated as a function of eccentricity is plotted according to inertia tensor method. According to multipole formalism the power radiated in gravitational waves from an bound orbit is given by enhancement factor g(n,e) times the function of other parameters is plotted. The calculations apply for arbitrary eccentricity of the relative orbit, assuming orbital velocities are small.

  2. A virtual radiation belt observatory: Looking forward to the electronic geophysical year

    NASA Astrophysics Data System (ADS)

    Baker, D. N.; Green, J. C.; Kroehl, H. W.; Kihn, E.; Virbo Team

    During the International Geophysical Year (1957-1958), member countries established many new capabilities pursuing the major IGY objectives of collecting geophysical data as widely as possible and providing free access to these data for all scientists around the globe. A key achievement of the IGY was the establishment of a worldwide system of data centers and physical observatories. The worldwide scientific community has now endorsed and is promoting an electronic Geophysical Year (eGY) initiative. The proposed eGY concept would both commemorate the 50th anniversary of the IGY in 2007-2008 and would provide a forward impetus to geophysics in the 21st century, similar to that provide by the IGY fifty years ago. The eGY concept advocates the establishment of a series of virtual geophysical observatories now being deployed in cyberspace. We are developing the concept of a Virtual Radiation Belt Observatory (ViRBO) that will bring together near-earth particle and field measurements acquired by NASA, NOAA, DoD, DOE, and other spacecraft. We discuss plans to aggregate these measurements into a readily accessible database along with analysis, visualization, and display tools that will make radiation belt information available and useful both to the scientific community and to the user community. We envision that data from the various agencies along with models being developed under the auspices of the National Science Foundation Center for Integrated Space Weather Modeling (CISM) will help us to provide an excellent `climatology' of the radiation belts over the past several decades. In particular, we would plan to use these data to drive physical models of the radiation belts to form a gridded database which would characterize particle and field properties on solar-cycle (11-year) time scales. ViRBO will also provide up-to-date specification of conditions for event analysis and anomaly resolution. We are even examining the possibilities for near-realtime acquisition of

  3. Impact of gravitational radiation higher order modes on single aligned-spin gravitational wave searches for binary black holes

    NASA Astrophysics Data System (ADS)

    Calderón Bustillo, Juan; Husa, Sascha; Sintes, Alicia M.; Pürrer, Michael

    2016-04-01

    Current template-based gravitational wave searches for compact binary coalescences use waveform models that omit the higher order modes content of the gravitational radiation emitted, considering only the quadrupolar (ℓ,|m |)=(2 ,2 ) modes. We study the effect of such omission for the case of aligned-spin compact binary coalescence searches for equal-spin (and nonspinning) binary black holes in the context of two versions of Advanced LIGO: the upcoming 2015 version, known as early Advanced LIGO (eaLIGO) and its zero-detuned high-energy power version, which we will refer to as Advanced LIGO (AdvLIGO). In addition, we study the case of a nonspinning search for initial LIGO (iLIGO). We do this via computing the effectualness of the aligned-spin SEOBNRv1 reduced order model waveform family, which only considers quadrupolar modes, toward hybrid post-Newtonian/numerical relativity waveforms which contain higher order modes. We find that for all LIGO versions losses of more than 10% of events occur in the case of AdvLIGO for mass ratio q ≥6 and total mass M ≥100 M⊙ due to the omission of higher modes, this region of the parameter space being larger for eaLIGO and iLIGO. Moreover, while the maximum event loss observed over the explored parameter space for AdvLIGO is of 15% of events, for iLIGO and eaLIGO, this increases up to (39,23)%. We find that omission of higher modes leads to observation-averaged systematic parameter biases toward lower spin, total mass, and chirp mass. For completeness, we perform a preliminar, nonexhaustive comparison of systematic biases to statistical errors. We find that, for a given signal-to-noise ratio, systematic biases dominate over statistical errors at much lower total mass for eaLIGO than for AdvLIGO.

  4. Backreaction of Hawking radiation on a gravitationally collapsing star I: Black holes?

    NASA Astrophysics Data System (ADS)

    Mersini-Houghton, Laura

    2014-11-01

    Particle creation leading to Hawking radiation is produced by the changing gravitational field of the collapsing star. The two main initial conditions in the far past placed on the quantum field from which particles arise, are the Hartle-Hawking vacuum and the Unruh vacuum. The former leads to a time-symmetric thermal bath of radiation, while the latter to a flux of radiation coming out of the collapsing star. The energy of Hawking radiation in the interior of the collapsing star is negative and equal in magnitude to its value at future infinity. This work investigates the backreaction of Hawking radiation on the interior of a gravitationally collapsing star, in a Hartle-Hawking initial vacuum. It shows that due to the negative energy Hawking radiation in the interior, the collapse of the star stops at a finite radius, before the singularity and the event horizon of a black hole have a chance to form. That is, the star bounces instead of collapsing to a black hole. A trapped surface near the last stage of the star's collapse to its minimum size may still exist temporarily. Its formation depends on the details of collapse. Results for the case of Hawking flux of radiation with the Unruh initial state, will be given in a companion paper II.

  5. Modeling the Spin Equilibrium of Neutron Stars in LMXBs Without Gravitational Radiation

    NASA Technical Reports Server (NTRS)

    Andersson, N.; Glampedakis, K.; Haskell, B.; Watts, A. L.

    2004-01-01

    In this paper we discuss the spin-equilibrium of accreting neutron stars in LMXBs. We demonstrate that, when combined with a naive spin-up torque, the observed data leads to inferred magnetic fields which are at variance with those of galactic millisecond radiopulsars. This indicates the need for either additional spin-down torques (eg. gravitational radiation) or an improved accretion model. We show that a simple consistent accretion model can be arrived at by accounting for radiation pressure in rapidly accreting systems (above a few percent of the Eddington accretion rate). In our model the inner disk region is thick and significantly sub-Keplerian, and the estimated equilibrium periods are such that the LMXB neutron stars have properties that accord well with the galactic millisecond radiopulsar sample. The implications for future gravitational-wave observations are also discussed briefly.

  6. Shearing and geodesic axially symmetric perfect fluids that do not produce gravitational radiation

    NASA Astrophysics Data System (ADS)

    Herrera, L.; Di Prisco, A.; Ospino, J.; Carot, J.

    2015-01-01

    Using a framework based on the 1 +3 formalism we carry out a study on axially and reflection symmetric perfect and geodesic fluids, looking for possible models of sources radiating gravitational waves. Therefore, the fluid should be necessarily shearing, for otherwise the magnetic part of the Weyl tensor vanishes, leading to a vanishing of the super-Poynting vector. However, for the family of perfect, geodesic fluids considered here, it appears that all possible cases reduce to conformally flat, shear-free, vorticity-free fluids, i.e., Friedman-Robertson-Walker. The super-Poynting vector vanishes and therefore no gravitational radiation is expected to be produced. The physical meaning of the obtained result is discussed.

  7. Relativistic astrophysics. [studies of gravitational radiation in asymptotic de sitter space and post Newtonian approximation

    NASA Technical Reports Server (NTRS)

    Smalley, L. L.

    1975-01-01

    The coordinate independence of gravitational radiation and the parameterized post-Newtonian approximation from which it is extended are described. The general consistency of the field equations with Bianchi identities, gauge conditions, and the Newtonian limit of the perfect fluid equations of hydrodynamics are studied. A technique of modification is indicated for application to vector-metric or double metric theories, as well as to scalar-tensor theories.

  8. Enhanced polarization of the cosmic microwave background radiation from thermal gravitational waves.

    PubMed

    Bhattacharya, Kaushik; Mohanty, Subhendra; Nautiyal, Akhilesh

    2006-12-22

    If inflation was preceded by a radiation era, then at the time of inflation there will exist a decoupled thermal distribution of gravitons. Gravitational waves generated during inflation will be amplified by the process of stimulated emission into the existing thermal distribution of gravitons. Consequently, the usual zero temperature scale invariant tensor spectrum is modified by a temperature dependent factor. This thermal correction factor amplifies the B-mode polarization of the cosmic microwave background radiation by an order of magnitude at large angles, which may now be in the range of observability of the Wilkinson Microwave Anisotropy Probe. PMID:17280339

  9. Reducing spurious gravitational radiation in binary-black-hole simulations by using conformally curved initial data

    NASA Astrophysics Data System (ADS)

    Lovelace, Geoffrey

    2009-06-01

    At early times in numerical evolutions of binary black holes, current simulations contain an initial burst of spurious gravitational radiation (also called 'junk radiation') which is not astrophysically realistic. The spurious radiation is a consequence of how the binary-black-hole initial data are constructed: the initial data are typically assumed to be conformally flat. In this paper, I adopt a curved conformal metric that is a superposition of two boosted, non-spinning black holes that are approximately 15 orbits from merger. I compare junk radiation of the superposed-boosted-Schwarzschild (SBS) initial data with the junk of corresponding conformally flat, maximally sliced (CFMS) initial data. The SBS junk is smaller in amplitude than the CFMS junk, with the junk's leading-order spectral modes typically being reduced by a factor of order 2 or more.

  10. On the gravitational field of a radiating, isothermal perfect gas cloud

    NASA Astrophysics Data System (ADS)

    Campos, L. M. B. C.

    2016-04-01

    The paper considers a static isotropic self-gravitating perfect gas in the presence of thermal radiation. The gravitational field is specified in terms of the radiation and gas pressures. Assuming that the thermodynamic internal energy is small compared with relativistic rest energy, it is shown that the gas pressure satisfies the Lane-Emden equation; the assumption of dominant intrinsic relativistic rest energy is satisfied by the hottest stars. Six-solutions of the Lane-Enden equation are obtained together with the corresponding gravitational fields. The basis for comparison is the singular solution I decaying like the inverse square of the radius, that is the leading term of the asymptotic solution V. Two semi-linear solutions are obtained using as variables nonlinear functions of the gas pressure, leading to nonlinear second-order differential equations that can be linearized; one solution II holds for small radius and leads to zero, finite or infinite central pressure, and the other solution III holds asymptomatically and exhibits pressure oscillations. The singular solution I for large radius is matched to a power series solution IV for small radius leading to a solution valid for all radii. The asymptotic solutions III and V: (i) coincide in their common domain of validity; (ii) can be truncated with good accuracy leading to the solution VI.

  11. A low-noise transimpedance amplifier for the detection of “Violin-Mode” resonances in advanced Laser Interferometer Gravitational wave Observatory suspensions

    SciTech Connect

    Lockerbie, N. A.; Tokmakov, K. V.

    2014-11-15

    This paper describes the design and performance of an extremely low-noise differential transimpedance amplifier, which takes its two inputs from separate photodiodes. The amplifier was planned to serve as the front-end electronics for a highly sensitive shadow-displacement sensing system, aimed at detecting very low-level “Violin-Mode” (VM) oscillations in 0.4 mm diameter by 600 mm long fused-silica suspension fibres. Four such highly tensioned fibres support the 40 kg test-masses/mirrors of the Advanced Laser Interferometer Gravitational wave Observatory interferometers. This novel design of amplifier incorporates features which prevent “noise-gain peaking” arising from large area photodiode (and cable) capacitances, and which also usefully separate the DC and AC photocurrents coming from the photodiodes. In consequence, the differential amplifier was able to generate straightforwardly two DC outputs, one per photodiode, as well as a single high-gain output for monitoring the VM oscillations—this output being derived from the difference of the photodiodes’ two, naturally anti-phase, AC photocurrents. Following a displacement calibration, the amplifier's final VM signal output was found to have an AC displacement responsivity at 500 Hz of (9.43 ± 1.20) MV(rms) m{sup −1}(rms), and, therefore, a shot-noise limited sensitivity to such AC shadow- (i.e., fibre-) displacements of (69 ± 13) picometres/√Hz at this frequency, over a measuring span of ±0.1 mm.

  12. A low-noise transimpedance amplifier for the detection of "Violin-Mode" resonances in Advanced Laser Interferometer Gravitational wave Observatory suspensions.

    PubMed

    Lockerbie, N A; Tokmakov, K V

    2014-11-01

    This paper describes the design and performance of an extremely low-noise differential transimpedance amplifier, which takes its two inputs from separate photodiodes. The amplifier was planned to serve as the front-end electronics for a highly sensitive shadow-displacement sensing system, aimed at detecting very low-level "Violin-Mode" (VM) oscillations in 0.4 mm diameter by 600 mm long fused-silica suspension fibres. Four such highly tensioned fibres support the 40 kg test-masses/mirrors of the Advanced Laser Interferometer Gravitational wave Observatory interferometers. This novel design of amplifier incorporates features which prevent "noise-gain peaking" arising from large area photodiode (and cable) capacitances, and which also usefully separate the DC and AC photocurrents coming from the photodiodes. In consequence, the differential amplifier was able to generate straightforwardly two DC outputs, one per photodiode, as well as a single high-gain output for monitoring the VM oscillations-this output being derived from the difference of the photodiodes' two, naturally anti-phase, AC photocurrents. Following a displacement calibration, the amplifier's final VM signal output was found to have an AC displacement responsivity at 500 Hz of (9.43 ± 1.20) MV(rms) m(-1)(rms), and, therefore, a shot-noise limited sensitivity to such AC shadow- (i.e., fibre-) displacements of (69 ± 13) picometres/√Hz at this frequency, over a measuring span of ±0.1 mm. PMID:25430131

  13. A low-noise transimpedance amplifier for the detection of "Violin-Mode" resonances in advanced Laser Interferometer Gravitational wave Observatory suspensions

    NASA Astrophysics Data System (ADS)

    Lockerbie, N. A.; Tokmakov, K. V.

    2014-11-01

    This paper describes the design and performance of an extremely low-noise differential transimpedance amplifier, which takes its two inputs from separate photodiodes. The amplifier was planned to serve as the front-end electronics for a highly sensitive shadow-displacement sensing system, aimed at detecting very low-level "Violin-Mode" (VM) oscillations in 0.4 mm diameter by 600 mm long fused-silica suspension fibres. Four such highly tensioned fibres support the 40 kg test-masses/mirrors of the Advanced Laser Interferometer Gravitational wave Observatory interferometers. This novel design of amplifier incorporates features which prevent "noise-gain peaking" arising from large area photodiode (and cable) capacitances, and which also usefully separate the DC and AC photocurrents coming from the photodiodes. In consequence, the differential amplifier was able to generate straightforwardly two DC outputs, one per photodiode, as well as a single high-gain output for monitoring the VM oscillations—this output being derived from the difference of the photodiodes' two, naturally anti-phase, AC photocurrents. Following a displacement calibration, the amplifier's final VM signal output was found to have an AC displacement responsivity at 500 Hz of (9.43 ± 1.20) MV(rms) m-1(rms), and, therefore, a shot-noise limited sensitivity to such AC shadow- (i.e., fibre-) displacements of (69 ± 13) picometres/√Hz at this frequency, over a measuring span of ±0.1 mm.

  14. Gravitational time delay in orthogonally polarized radiation passing by the sun

    NASA Technical Reports Server (NTRS)

    Harwit, M.

    1979-01-01

    Two parallel investigations into the degree, if any, to which orthogonally polarized rays are deflected differently on passing through the gravitational field of the sun were previously conducted. The first involved very long and intermediate length baseline radio interferometry. The second was initially based on observations of radiation transmitted by the Pioneer 6 spacecraft, on passing behind the sun in 1968. This work was extended by using Helios-A and Helios-B spacecraft. It was calculated that the differential deflection between orthogonally polarized components is less than one part in 10 to the 7th power of the total gravitational deflection, or less than about 10 to the -7th power arc sec, in total.

  15. Upper limits on the isotropic gravitational radiation background from pulsar timing analysis

    NASA Technical Reports Server (NTRS)

    Hellings, R. W.; Downs, G. S.

    1983-01-01

    A pulsar and the earth may be thought of as end masses of a free-mass gravitational wave antenna in which the relative motion of the masses is monitored by observing the Doppler shift of the pulse arrival times. Using timing residuals from PSR 1133 + 16, 1237 + 25, 1604-00, and 2045-16, an upper limit to the spectrum of the isotropic gravitational radiation background has been derived in the frequency band 4 x 10 to the -9th to 10 to the -7th Hz. This limit is found to be S(E) = 10 to the 21st f-cubed ergs/cu cm Hz, where S(E) is the energy density spectrum and f is the frequency in Hz. This would limit the energy density at frequencies below 10 to the -8th Hz to be 0.00014 times the critical density.

  16. Gravitational radiation by point particle eccentric binary systems in the linearised characteristic formulation of general relativity

    NASA Astrophysics Data System (ADS)

    Cedeño Montaña, C. E.; de Araujo, J. C. N.

    2016-04-01

    We study a binary system composed of point particles of unequal masses in eccentric orbits in the linear regime of the characteristic formulation of general relativity, generalising a previous study found in the literature in which a system of equal masses in circular orbits is considered. We also show that the boundary conditions on the time-like world tubes generated by the orbits of the particles can be extended beyond circular orbits. Concerning the power lost by the emission of gravitational waves, it is directly obtained from the Bondi's News function. It is worth stressing that our results are completely consistent, because we obtain the same result for the power derived by Peters and Mathews, in a different approach, in their seminal paper of 1963. In addition, the present study constitutes a powerful tool to construct extraction schemes in the characteristic formalism to obtain the gravitational radiation produced by binary systems during the inspiralling phase.

  17. Gravitational radiation from a spinning compact object around a supermassive Kerr black hole in circular orbit

    SciTech Connect

    Han Wenbiao

    2010-10-15

    The gravitational waves and energy radiation from a spinning compact object with stellar mass in a circular orbit in the equatorial plane of a supermassive Kerr black hole are investigated in this paper. The effect of how the spin acts on energy and angular moment fluxes is discussed in detail. The calculation results indicate that the spin of a small body should be considered in waveform-template production for the upcoming gravitational wave detections. It is clear that when the direction of spin axes is the same as the orbitally angular momentum ('positive' spin), spin can decrease the energy fluxes which radiate to infinity. For antidirection spin ('negative'), the energy fluxes to infinity can be enlarged. And the relations between fluxes (both infinity and horizon) and spin look like quadratic functions. From frequency shift due to spin, we estimate the wave-phase accumulation during the inspiraling process of the particle. We find that the time of particle inspiral into the black hole is longer for positive spin and shorter for negative compared with the nonspinning particle. Especially, for extreme spin value, the energy radiation near the horizon of the extreme Kerr black hole is much more than that for the nonspinning one. And consequently, the maximum binging energy of the extreme spinning particle is much larger than that of the nonspinning particle.

  18. Nonchaotic evolution of triangular configuration due to gravitational radiation reaction in the three-body problem

    NASA Astrophysics Data System (ADS)

    Yamada, Kei; Asada, Hideki

    2016-04-01

    Continuing work initiated in an earlier publication [H. Asada, Phys. Rev. D 80, 064021 (2009)], the gravitational radiation reaction to Lagrange's equilateral triangular solution of the three-body problem is investigated in an analytic method. The previous work is based on the energy balance argument, which is sufficient for a two-body system because the number of degrees of freedom (the semimajor axis and the eccentricity in quasi-Keplerian cases, for instance) equals that of the constants of motion such as the total energy and the orbital angular momentum. In a system with three (or more) bodies, however, the number of degrees of freedom is more than that of the constants of motion. Therefore, the present paper discusses the evolution of the triangular system by directly treating the gravitational radiation reaction force to each body. The perturbed equations of motion are solved by using the Laplace transform technique. It is found that the triangular configuration is adiabatically shrinking and is kept in equilibrium by increasing the orbital frequency due to the radiation reaction if the mass ratios satisfy the Newtonian stability condition. Long-term stability involving the first post-Newtonian corrections is also discussed.

  19. Emerging Hawking-Like Radiation from Gravitational Bremsstrahlung Beyond the Planck Scale.

    PubMed

    Ciafaloni, Marcello; Colferai, Dimitri; Veneziano, Gabriele

    2015-10-23

    We argue that, as a consequence of the graviton's spin-2, its bremsstrahlung in trans-Planckian-energy (E≫M(P)) gravitational scattering at small deflection angle can be nicely expressed in terms of helicity-transformation phases and their transfer within the scattering process. The resulting spectrum exhibits deeply sub-Planckian characteristic energies of order M(P)(2)/E≪M(P) (reminiscent of Hawking radiation), a suppressed fragmentation region, and a reduced rapidity plateau, in broad agreement with recent classical estimates. PMID:26551096

  20. Emerging Hawking-Like Radiation from Gravitational Bremsstrahlung Beyond the Planck Scale

    NASA Astrophysics Data System (ADS)

    Ciafaloni, Marcello; Colferai, Dimitri; Veneziano, Gabriele

    2015-10-01

    We argue that, as a consequence of the graviton's spin-2, its bremsstrahlung in trans-Planckian-energy (E ≫MP ) gravitational scattering at small deflection angle can be nicely expressed in terms of helicity-transformation phases and their transfer within the scattering process. The resulting spectrum exhibits deeply sub-Planckian characteristic energies of order MP2/E ≪MP (reminiscent of Hawking radiation), a suppressed fragmentation region, and a reduced rapidity plateau, in broad agreement with recent classical estimates.

  1. Gravitational instability of a quasi-homogeneous plasma cloud with radiation

    NASA Astrophysics Data System (ADS)

    Vranjes, J.

    1990-11-01

    The present consideration of small, propagating perturbations in the central region of a gas cloud takes radiative pressure into account and derives an instability criterion analogous to that of Jeans (1902). The basic state is treated locally as quasi-homogeneous; the first derivatives of all basic state quantities can accordingly be neglected, in keeping with the Poisson's equation describing the gravitational potential in the basic state. It is established that the inhomogeneity can act either to stabilize or destabilize the system, depending on the value of the second derivative of the basic state temperature.

  2. Theory-Agnostic Constraints on Black-Hole Dipole Radiation with Multiband Gravitational-Wave Astrophysics

    NASA Astrophysics Data System (ADS)

    Barausse, Enrico; Yunes, Nicolás; Chamberlain, Katie

    2016-06-01

    The aLIGO detection of the black-hole binary GW150914 opens a new era for probing extreme gravity. Many gravity theories predict the emission of dipole gravitational radiation by binaries. This is excluded to high accuracy in binary pulsars, but entire classes of theories predict this effect predominantly (or only) in binaries involving black holes. Joint observations of GW150914-like systems by aLIGO and eLISA will improve bounds on dipole emission from black-hole binaries by 6 orders of magnitude relative to current constraints, provided that eLISA is not dramatically descoped.

  3. Theory-Agnostic Constraints on Black-Hole Dipole Radiation with Multiband Gravitational-Wave Astrophysics.

    PubMed

    Barausse, Enrico; Yunes, Nicolás; Chamberlain, Katie

    2016-06-17

    The aLIGO detection of the black-hole binary GW150914 opens a new era for probing extreme gravity. Many gravity theories predict the emission of dipole gravitational radiation by binaries. This is excluded to high accuracy in binary pulsars, but entire classes of theories predict this effect predominantly (or only) in binaries involving black holes. Joint observations of GW150914-like systems by aLIGO and eLISA will improve bounds on dipole emission from black-hole binaries by 6 orders of magnitude relative to current constraints, provided that eLISA is not dramatically descoped. PMID:27367380

  4. 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.

  5. CONVERGENCE STUDIES OF MASS TRANSPORT IN DISKS WITH GRAVITATIONAL INSTABILITIES. II. THE RADIATIVE COOLING CASE

    SciTech Connect

    Steiman-Cameron, Thomas Y.; Durisen, Richard H.; Michael, Scott; McConnell, Caitlin R.; Boley, Aaron C. E-mail: durisen@astro.indiana.edu E-mail: carmccon@indiana.edu

    2013-05-10

    We conduct a convergence study of a protoplanetary disk subject to gravitational instabilities (GIs) at a time of approximate balance between heating produced by the GIs and radiative cooling governed by realistic dust opacities. We examine cooling times, characterize GI-driven spiral waves and their resultant gravitational torques, and evaluate how accurately mass transport can be represented by an {alpha}-disk formulation. Four simulations, identical except for azimuthal resolution, are conducted with a grid-based three-dimensional hydrodynamics code. There are two regions in which behaviors differ as resolution increases. The inner region, which contains 75% of the disk mass and is optically thick, has long cooling times and is well converged in terms of various measures of structure and mass transport for the three highest resolutions. The longest cooling times coincide with radii where the Toomre Q has its minimum value. Torques are dominated in this region by two- and three-armed spirals. The effective {alpha} arising from gravitational stresses is typically a few Multiplication-Sign 10{sup -3} and is only roughly consistent with local balance of heating and cooling when time-averaged over many dynamic times and a wide range of radii. On the other hand, the outer disk region, which is mostly optically thin, has relatively short cooling times and does not show convergence as resolution increases. Treatment of unstable disks with optical depths near unity with realistic radiative transport is a difficult numerical problem requiring further study. We discuss possible implications of our results for numerical convergence of fragmentation criteria in disk simulations.

  6. 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.

  7. Dynamic Universe Model predicts frequency shifting in electromagnetic radiation near gravitating masses

    NASA Astrophysics Data System (ADS)

    Naga Parameswara Gupta, Satyavarapu

    2016-07-01

    In this paper, Dynamic Universe Model studies the light rays and other electromagnetic radiation passing grazingly near any gravitating mass. This change in frequency will depend on relative direction of movement between mass and radiation. Change in frequency depends on relative direction between ray and the Gravitating mass. Here in this paper we will mathematically derive the results and show these predictions. Dynamic Universe Model uses a new type of Tensor. There are no differential or integral equations here. No singularities and body to body collisions in this model. Many papers were published in USA and CANADA. See Dynamic Universe Model Blog for further details and papers Dynamic Universe Model never reduces to General relativity on any condition. It uses a different type of mathematics based on Newtonian physics. This mathematics used here is simple and straightforward. As there are no differential equations present in Dynamic Universe Model, the set of equations give single solution in x y z Cartesian coordinates for every point mass for every time step Keywords: Dynamic Universe Model, Hubble Space telescope (HST), SITA simulations , singularity-free cosmology,

  8. Collapsing objects with the same gravitational trajectory can radiate away different amount of energy

    NASA Astrophysics Data System (ADS)

    Dai, De-Chang; Stojkovic, Dejan

    2016-07-01

    We study radiation emitted during the gravitational collapse from two different types of shells. We assume that one shell is made of dark matter and is completely transparent to the test scalar (for simplicity) field which belongs to the standard model, while the other shell is made of the standard model particles and is totally reflecting to the scalar field. These two shells have exactly the same mass, charge and angular momentum (though we set the charge and angular momentum to zero), and therefore follow the same geodesic trajectory. However, we demonstrate that they radiate away different amount of energy during the collapse. This difference can in principle be used by an asymptotic observer to reconstruct the physical properties of the initial collapsing object other than mass, charge and angular momentum. This result has implications for the information paradox and expands the list of the type of information which can be released from a collapsing object.

  9. Simulating radiative feedback and star cluster formation in GMCs - I. Dependence on gravitational boundedness

    NASA Astrophysics Data System (ADS)

    Howard, Corey S.; Pudritz, Ralph E.; Harris, William E.

    2016-09-01

    Radiative feedback is an important consequence of cluster formation in giant molecular clouds (GMCs) in which newly formed clusters heat and ionize their surrounding gas. The process of cluster formation, and the role of radiative feedback, has not been fully explored in different GMC environments. We present a suite of simulations which explore how the initial gravitational boundedness, and radiative feedback, affect cluster formation. We model the early evolution (<5 Myr) of turbulent, 106 M⊙ clouds with virial parameters ranging from 0.5 to 5. To model cluster formation, we use cluster sink particles, coupled to a raytracing scheme, and a custom subgrid model which populates a cluster via sampling an initial mass function (IMF) with an efficiency of 20 per cent per free-fall time. We find that radiative feedback only decreases the cluster particle formation efficiency by a few per cent. The initial virial parameter plays a much stronger role in limiting cluster formation, with a spread of cluster formation efficiencies of 37-71 per cent for the most unbound to the most bound model. The total number of clusters increases while the maximum mass cluster decreases with an increasing initial virial parameter, resulting in steeper mass distributions. The star formation rates in our cluster particles are initially consistent with observations but rise to higher values at late times. This suggests that radiative feedback alone is not responsible for dispersing a GMC over the first 5 Myr of cluster formation.

  10. Progress in gravitational wave detection

    NASA Astrophysics Data System (ADS)

    Cheng, Jing-Quan; Yang, De-Hua

    2005-09-01

    General theory of Einstein's relativity predicts the existence of gravitational wave when mass is accelerated. However, no material has direct effect when the gravitational wave passes. Therefore, gravitational wave can only be detected indirectly. The effort in gravitational wave detection was started in the 60s of last century by using a huge cylinder of aluminum. This paper introduced all the relevant projects in the gravitational wave detection. These projects include Weber's bar, Laser interferometer Gravitational wave Detector (LGD), Laser Interferometer Gravitational wave Observatory (LIGO), GEO600, VIRGO, TAMA300, Advanced LIGO, Large scale Cryogenic Gravitational wave Telescope (LCGO), and Laser Interferometer Space Antenna (LISA).

  11. Gravitational Radiation from Binary Black Holes: Advances in the Perturbative Approach

    NASA Astrophysics Data System (ADS)

    Lousto, C. O.

    2005-08-01

    After the work of Regge, Wheeler, Zerilli, Teukolsky and others in the 1970s, it became possible to accurately compute the gravitational radiation generated by the collision of two black holes (in the extreme-mass limit). It was soon evident that, to first perturbative order, a particle in a circular orbit would continue orbiting forever if the radiative corrections to the particle motion that make the orbit decay were not taken into account. When I entered the field in 1996, a quick search of the literature showed that this problem was still unsolved. A straightforward computation leads to infinities produced by the representation of the particle in terms of Dirac delta functions. Since 1938, when Dirac had solved the equivalent problem in electromagnetic theory, nobody had succeeded in regularizing this in a self-consistent manner. Fortunately, the solution was arrived at much sooner than we expected. In 1997, Mino, Sasaki and Tanaka, and Quinn and Wald published the equations of motion that a particle obeys after self-force corrections. This essentially gave birth to the field of radiation reaction/self-force computations. The aim of this programme is first to obtain the corrections to the geodesic motion of a particle in the background of a single black hole, and then to use this corrected trajectory to compute second-order perturbations of the gravitational field. This will give us the energy-momentum radiated to infinity and into the hole, as well as the waveforms that we will eventually be able to measure with ground- or space-based gravitational wave detectors. As mentioned, the programme as a whole will give us waveforms accurate to second perturbative order in the mass ratio of the black holes, i.e. Script O[(m/M)2]. This will be a good approximation for galactic binary black holes of the order of a few solar masses, in the right frequency range (few hundred Hertz) to be detected by ground-based gravitational wave interferometers such as LIGO and VIRGO

  12. Mergers of Non-spinning Black-hole Binaries: Gravitational Radiation Characteristics

    NASA Technical Reports Server (NTRS)

    Baker, John G.; Boggs, William D.; Centrella, Joan; Kelly, Bernard J.; McWilliams, Sean T.; vanMeter, James R.

    2008-01-01

    We present a detailed descriptive analysis of the gravitational radiation from black-hole binary mergers of non-spinning black holes, based on numerical simulations of systems varying from equal-mass to a 6:1 mass ratio. Our primary goal is to present relatively complete information about the waveforms, including all the leading multipolar components, to interested researchers. In our analysis, we pursue the simplest physical description of the dominant features in the radiation, providing an interpretation of the waveforms in terms of an implicit rotating source. This interpretation applies uniformly to the full wavetrain, from inspiral through ringdown. We emphasize strong relationships among the l = m modes that persist through the full wavetrain. Exploring the structure of the waveforms in more detail, we conduct detailed analytic fitting of the late-time frequency evolution, identifying a key quantitative feature shared by the l = m modes among all mass-ratios. We identify relationships, with a simple interpretation in terms of the implicit rotating source, among the evolution of frequency and amplitude, which hold for the late-time radiation. These detailed relationships provide sufficient information about the late-time radiation to yield a predictive model for the late-time waveforms, an alternative to the common practice of modeling by a sum of quasinormal mode overtones. We demonstrate an application of this in a new effective-one-body-based analytic waveform model.

  13. On the quasihydrostatic flows of radiatively cooling self-gravitating gas clouds

    SciTech Connect

    Meerson, B.; Megged, E.; Tajima, T.

    1995-03-01

    Two model problems are considered, illustrating the dynamics of quasihydrostatic flows of radiatively cooling, optically thin self-gravitating gas clouds. In the first problem, spherically symmetric flows in an unmagnetized plasma are considered. For a power-law dependence of the radiative loss function on the temperature, a one-parameter family of self-similar solutions is found. The authors concentrate on a constant-mass cloud, one of the cases, when the self-similarity indices are uniquely selected. In this case, the self-similar flow problem can be formally reduced to the classical Lane-Emden equation and therefore solved analytically. The cloud is shown to undergo radiative condensation, if the gas specific heat ratio {gamma} > 4/3. The condensation proceeds either gradually, or in the form of (quasihydrostatic) collapse. For {gamma} < 4/3, the cloud is shown to expand. The second problem addresses a magnetized plasma slab that undergoes quasihydrostatic radiative cooling and condensation. The problem is solved analytically, employing the Lagrangian mass coordinate.

  14. Gravitational Radiation from Binary Black Holes: Advances in the Perturbative Approach

    NASA Astrophysics Data System (ADS)

    Lousto, C. O.

    2005-08-01

    After the work of Regge, Wheeler, Zerilli, Teukolsky and others in the 1970s, it became possible to accurately compute the gravitational radiation generated by the collision of two black holes (in the extreme-mass limit). It was soon evident that, to first perturbative order, a particle in a circular orbit would continue orbiting forever if the radiative corrections to the particle motion that make the orbit decay were not taken into account. When I entered the field in 1996, a quick search of the literature showed that this problem was still unsolved. A straightforward computation leads to infinities produced by the representation of the particle in terms of Dirac delta functions. Since 1938, when Dirac had solved the equivalent problem in electromagnetic theory, nobody had succeeded in regularizing this in a self-consistent manner. Fortunately, the solution was arrived at much sooner than we expected. In 1997, Mino, Sasaki and Tanaka, and Quinn and Wald published the equations of motion that a particle obeys after self-force corrections. This essentially gave birth to the field of radiation reaction/self-force computations. The aim of this programme is first to obtain the corrections to the geodesic motion of a particle in the background of a single black hole, and then to use this corrected trajectory to compute second-order perturbations of the gravitational field. This will give us the energy-momentum radiated to infinity and into the hole, as well as the waveforms that we will eventually be able to measure with ground- or space-based gravitational wave detectors. As mentioned, the programme as a whole will give us waveforms accurate to second perturbative order in the mass ratio of the black holes, i.e. Script O[(m/M)2]. This will be a good approximation for galactic binary black holes of the order of a few solar masses, in the right frequency range (few hundred Hertz) to be detected by ground-based gravitational wave interferometers such as LIGO and VIRGO

  15. A historical fluence analysis of the radiation environment of the Chandra X-ray Observatory and implications for continued radiation monitoring

    NASA Astrophysics Data System (ADS)

    DePasquale, J. M.; Plucinsky, P. P.; Schwartz, D. A.

    2006-06-01

    Now in operation for over 6 years, the Chandra X-ray Observatory (CXO) has sampled a variety of space environments. Its highly elliptical orbit, with a 63.5 hr period, regularly takes the spacecraft through the Earth's radiation belts, the magnetosphere, the magnetosheath and into the solar wind. Additionally, the CXO has weathered several severe solar storms during its time in orbit. Given the vulnerability of Chandra's Charge Coupled Devices (CCDs) to radiation damage from low energy protons, proper radiation management has been a prime concern of the Chandra team. A comprehensive approach utilizing scheduled radiation safing, in addition to both on-board autonomous radiation monitoring and manual intervention, has proved successful at managing further radiation damage. However, the future of autonomous radiation monitoring on-board the CXO faces a new challenge as the multi-layer insulation (MLI) on its radiation monitor, the Electron, Proton, Helium Instrument (EPHIN), continues to degrade, leading to elevated temperatures. Operating at higher temperatures, the data from some EPHIN channels can become noisy and unreliable for radiation monitoring. This paper explores the full implication of the loss of EPHIN to CXO radiation monitoring by evaluating the fluences the CXO experienced during 40 autonomous radiation safing events from 2000 through 2005 in various hypothetical scenarios which include the use of EPHIN in limited to no capacity as a radiation monitor. We also consider the possibility of replacing EPHIN with Chandra's High Resolution Camera (HRC) for radiation monitoring.

  16. Measurement of a high electrical quality factor in a niobium resonator for a gravitational radiation detector

    NASA Technical Reports Server (NTRS)

    Folkner, W. M.; Moody, M. V.; Richard, J.-P.

    1989-01-01

    The mechanical and electrical quality factors of a 10-g niobium resonator were measured at 4.4 K and were found to be 8.1 x 10 to the 6th, and 3.8 x 10 to the 6th, respectively. The value for the electrical quality factor is high enough for a system operating at 50 mK at a sensitivity level of one phonon. The resonator's low damping properties make it suitable for use as a transducer for a cryogenic three-mode gravitational radiation detector. A practical design is given for the mounting of the resonator on a 2400-kg aluminum-bar detector. Projections are made for the sensitivity of a 2400-kg bar instrumented as a three-mode system with this resonator inductively coupled to a SQUID.

  17. Ultra--Low-Frequency Gravitational Radiation from Massive Black Hole Binaries

    NASA Astrophysics Data System (ADS)

    Rajagopal, Mohan; Romani, Roger W.

    1995-06-01

    For massive black hole binaries produced in galactic mergers, we examine the possibility of inspiral induced by interaction with field stars. We model the evolution of such binaries for a range of galaxy core and binary parameters, using numerical results from the literature to compute the binary's energy and angular momentum loss rates due to stellar encounters and including the effect of back-action on the field stars. We find that only a small fraction of binary systems can merge within a Hubble time via unassisted stellar dynamics. External perturbations may, however, cause efficient inspiral. Averaging over a population of central black holes and galaxy mergers, we computed the expected background of gravitational radiation with periods Pw ˜ 1-10 yr. Comparison with sensitivities from millisecond pulsar timing suggests that the strongest sources may be detectable with modest improvements to present experiments.

  18. Improving the Science Observing Efficiency of the Chandra X-Ray Observatory via the Chandra Radiation Model

    NASA Technical Reports Server (NTRS)

    Virani, Shanil; Schwartz, Daniel; Cameron, Robert; Plucinsky, Paul; O'Dell, Stephen; Munow, Joseph; Blackwell, William

    2003-01-01

    The Chandra X-ray Observatory (CXO), NASA's latest "Great Observatory", was launched on July 23, 1999 and reached its final orbit on August 7, 1999. The CXO is in a highly elliptical orbit, approximately 140,000 km x 10,000 km, and has a period of approximately 63.5 hours (N 2.65 days). It transits the Earth's Van Allen belts once per orbit during which no science observations can be performed due to the high radiation environment. The Chandra X-ray Observatory Center currently uses the National Space Science Data Center's "near Earth" AP-8/AE-8 radiation belt model to predict the start and end times of passage through the radiation belts. Our earlier analysis demonstrated that our implementation of the AP-8/AE-8 model (a simple dipole model of the Earth's magnetic field) does not always give sufficiently accurate predictions of the start and end times of transit of the Van Allen belts. This led to a change in our operating procedure whereby we "padded" the start and end times of transit by 10 kiloseconds (ks) so that ACIS, the primary science instrument on-board Chandra, would not be exposed to the "fringes" of the Van Allen belts on ingress and egress for any given transit. This additional 20 ks per orbit during which Chandra is unable to perform science observations sums to approximately 3 Ms of "lost" science time per year and therefore reduces the science observing efficiency of the Observatory. To address the need for a higher fidelity radiation model appropriate for the Chandra orbit, the Chandra Radiation Model (CRM) was developed. The CRM is an ion model for the outer magnetosphere and is based on data from the EPIC/ICS instrument on-board the Geotail satellite as well as data from the CEPPAD/IPS instrument on-board the Polar satellite. With the production and Implementation of the CRM, we present the results of a study designed to investigate the science observing time that may be recovered by using the CRM as a function of the additional low

  19. Improving the science observing efficiency of the Chandra X-ray Observatory via the Chandra radiation model

    NASA Astrophysics Data System (ADS)

    Virani, Shanil N.; DePasquale, Joseph M.; Schwartz, Daniel A.; Cameron, Robert A.; Plucinsky, Paul P.; O'Dell, Stephen L.; Minow, Joseph I.; Blackwell, William C., Jr.

    2004-02-01

    The Chandra X-ray Observatory (CXO), NASA's latest "Great Observatory", was launched on July 23, 1999 and reached its final orbit on August 7, 1999. The CXO is in a highly elliptical orbit, with an apogee altitude of 120,000 km and a perigee altitude 20,000 km, and has a period of approximately 63.5 hours (≍ 2.65 days). It transits the Earth's Van Allen belts once per orbit during which no science observations can be performed due to the high radiation environment. The Chandra X-ray Observatory Center currently uses the National Space Science Data Center's "near Earth" AP-8/AE-8 radiation belt model to predict the start and end times of passage through the radiation belts. Our earlier analysis (Virani et al, 2000) demonstrated that our implementation of the AP-8/AE-8 model (a simple dipole model of the Earth's magnetic field) does not always give sufficiently accurate predictions of the start and end times of transit of the Van Allen belts. This led to a change in our operating procedure whereby we "padded" the start and end times of transit as determined by the AE-8 model by 10 ks so that ACIS, the Advanced CCD Imaging Spectrometer and the primary science instrument on-board Chandra, would not be exposed to the "fringes" of the Van Allen belts on ingress and egress for any given transit. This additional 20 ks per orbit during which Chandra is unable to perform science observations integrates to approximately 3 Ms of "lost" science time per year and therefore reduces the science observing efficiency of the Observatory. To address the need for a higher fidelity radiation model appropriate for the Chandra orbit, the Chandra Radiation Model (CRM) was developed. The CRM is an ion model for the outer magnetosphere and is based on data from the EPIC/ICS instrument on-board the Geotail satellite as well as data from the CEPPAD/IPS instrument on-board the Polar satellite. With the production and implementation of the CRM Version 2.3, we present the results of a study

  20. Enhanced sensitivity of the LIGO gravitational wave detector by using squeezed states of light

    NASA Astrophysics Data System (ADS)

    Aasi, J.; Abadie, J.; Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M. R.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Affeldt, C.; Aguiar, O. D.; Ajith, P.; Allen, B.; Amador Ceron, E.; Amariutei, D.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C.; Ast, S.; Aston, S. M.; Atkinson, D.; Aufmuth, P.; Aulbert, C.; Austin, L.; Aylott, B. E.; Babak, S.; Baker, P. T.; Ballmer, S.; Bao, Y.; Barayoga, J. C.; Barker, D.; Barr, B.; Barsotti, L.; Barton, M. A.; Bartos, I.; Bassiri, R.; Batch, J.; Bauchrowitz, J.; Behnke, B.; Bell, A. S.; Bell, C.; Bergmann, G.; Berliner, J. M.; Bertolini, A.; Betzwieser, J.; Beveridge, N.; Beyersdorf, P. T.; Bhadbhade, T.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Biscans, S.; Black, E.; Blackburn, J. K.; Blackburn, L.; Blair, D.; Bland, B.; Bock, O.; Bodiya, T. P.; Bogan, C.; Bond, C.; Bork, R.; Born, M.; Bose, S.; Bowers, J.; Brady, P. R.; Braginsky, V. B.; Brau, J. E.; Breyer, J.; Bridges, D. O.; Brinkmann, M.; Britzger, M.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Buckland, K.; Brückner, F.; Buchler, B. C.; Buonanno, A.; Burguet-Castell, J.; Byer, R. L.; Cadonati, L.; Camp, J. B.; Campsie, P.; Cannon, K.; Cao, J.; Capano, C. D.; Carbone, L.; Caride, S.; Castiglia, A. D.; Caudill, S.; Cavaglià, M.; Cepeda, C.; Chalermsongsak, T.; Chao, S.; Charlton, P.; Chen, X.; Chen, Y.; Cho, H.-S.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, S. S. Y.; Chung, C. T. Y.; Ciani, G.; Clara, F.; Clark, D. E.; Clark, J. A.; Constancio Junior, M.; Cook, D.; Corbitt, T. R.; Cordier, M.; Cornish, N.; Corsi, A.; Costa, C. A.; Coughlin, M. W.; Countryman, S.; Couvares, P.; Coward, D. M.; Cowart, M.; Coyne, D. C.; Craig, K.; Creighton, J. D. E.; Creighton, T. D.; Cumming, A.; Cunningham, L.; Dahl, K.; Damjanic, M.; Danilishin, S. L.; Danzmann, K.; Daudert, B.; Daveloza, H.; Davies, G. S.; Daw, E. J.; Dayanga, T.; Deleeuw, E.; Denker, T.; Dent, T.; Dergachev, V.; Derosa, R.; Desalvo, R.; Dhurandhar, S.; di Palma, I.; Díaz, M.; Dietz, A.; Donovan, F.; Dooley, K. L.; Doravari, S.; Drasco, S.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Dumas, J.-C.; Dwyer, S.; Eberle, T.; Edwards, M.; Effler, A.; Ehrens, P.; Eikenberry, S. S.; Engel, R.; Essick, R.; Etzel, T.; Evans, K.; Evans, M.; Evans, T.; Factourovich, M.; Fairhurst, S.; Fang, Q.; Farr, B. F.; Farr, W.; Favata, M.; Fazi, D.; Fehrmann, H.; Feldbaum, D.; Finn, L. S.; Fisher, R. P.; Foley, S.; Forsi, E.; Fotopoulos, N.; 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.; Garcia, J.; Gehrels, N.; Gelencser, G.; Gergely, L. Á.; Ghosh, S.; Giaime, J. A.; Giampanis, S.; Giardina, K. D.; Gil-Casanova, S.; Gill, C.; Gleason, J.; Goetz, E.; González, G.; Gordon, N.; Gorodetsky, M. L.; Gossan, S.; Goßler, S.; Graef, C.; Graff, P. B.; Grant, A.; Gras, S.; Gray, C.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Griffo, C.; Grote, H.; Grover, K.; Grunewald, S.; Guido, C.; Gustafson, E. K.; Gustafson, R.; Hammer, D.; Hammond, G.; Hanks, J.; Hanna, C.; Hanson, J.; Haris, K.; Harms, J.; Harry, G. M.; Harry, I. W.; Harstad, E. D.; Hartman, M. T.; Haughian, K.; Hayama, K.; Heefner, J.; Heintze, M. C.; Hendry, M. A.; Heng, I. S.; Heptonstall, A. W.; Heurs, M.; Hewitson, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Holt, K.; Holtrop, M.; Hong, T.; Hooper, S.; Hough, J.; Howell, E. J.; Huang, V.; Huerta, E. A.; Hughey, B.; Huttner, S. H.; Huynh, M.; Huynh-Dinh, T.; Ingram, D. R.; Inta, R.; Isogai, T.; Ivanov, A.; Iyer, B. R.; Izumi, K.; Jacobson, M.; James, E.; Jang, H.; Jang, Y. J.; Jesse, E.; Johnson, W. W.; Jones, D.; Jones, D. I.; Jones, R.; Ju, L.; Kalmus, P.; Kalogera, V.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Kasturi, R.; Katsavounidis, E.; Katzman, W.; Kaufer, H.; Kawabe, K.; Kawamura, S.; Kawazoe, 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, Y.-M.; King, P. J.; Kinzel, D. L.; Kissel, J. S.; Klimenko, S.; Kline, J.; Kokeyama, K.; Kondrashov, V.; Koranda, S.; Korth, W. Z.; Kozak, D.; Kozameh, C.; Kremin, A.; Kringel, V.; Krishnan, B.; Kucharczyk, C.; Kuehn, G.; Kumar, P.; Kumar, R.; Kuper, B. J.; Kurdyumov, R.; Kwee, P.; Lam, P. K.; Landry, M.; Lantz, B.; Lasky, P. D.; Lawrie, C.; Lazzarini, A.; Le Roux, A.; Leaci, P.; Lee, C.-H.; Lee, H. K.; Lee, H. M.; Lee, J.; Leong, J. R.; Levine, B.; Lhuillier, V.; Lin, A. C.; Litvine, V.; Liu, Y.; Liu, Z.; Lockerbie, N. A.; Lodhia, D.; Loew, K.; Logue, J.; Lombardi, A. L.; Lormand, M.; Lough, J.; Lubinski, M.; Lück, H.; Lundgren, A. P.; MacArthur, J.; MacDonald, E.; Machenschalk, B.; Macinnis, M.; MacLeod, D. M.; Magaña-Sandoval, F.; Mageswaran, M.; Mailand, K.; Manca, G.; Mandel, I.; Mandic, V.; Márka, S.; Márka, Z.; Markosyan, A. S.; Maros, E.; Martin, I. W.; Martin, R. M.; Martinov, D.; Marx, J. N.; Mason, K.; Matichard, F.; Matone, L.; Matzner, R. A.; Mavalvala, N.; May, G.; Mazzolo, G.; McAuley, K.; McCarthy, R.; McClelland, D. E.; McGuire, S. C.; McIntyre, G.; McIver, J.; Meadors, G. D.; Mehmet, M.; Meier, T.; Melatos, A.; Mendell, G.; Mercer, R. A.; Meshkov, S.; Messenger, C.; Meyer, M. S.; Miao, H.; Miller, J.; Mingarelli, C. M. F.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moe, B.; Mokler, F.; Mohapatra, S. R. P.; Moraru, D.; Moreno, G.; Mori, T.; Morriss, S. R.; Mossavi, K.; Mow-Lowry, C. M.; Mueller, C. L.; Mueller, G.; Mukherjee, S.; Mullavey, A.; Munch, J.; Murphy, D.; Murray, P. G.; Mytidis, A.; Nanda Kumar, D.; Nash, T.; Nayak, R.; Necula, V.; Newton, G.; Nguyen, T.; Nishida, E.; Nishizawa, A.; Nitz, A.; Nolting, D.; Normandin, M. E.; Nuttall, L. K.; O'Dell, J.; O'Reilly, B.; O'Shaughnessy, R.; Ochsner, E.; Oelker, E.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Oppermann, P.; Osthelder, C.; Ott, C. D.; Ottaway, D. J.; Ottens, R. S.; Ou, J.; Overmier, H.; Owen, B. J.; Padilla, C.; Pai, A.; Pan, Y.; Pankow, C.; Papa, M. A.; Paris, H.; Parkinson, W.; Pedraza, M.; Penn, S.; Peralta, C.; Perreca, A.; Phelps, M.; Pickenpack, M.; Pierro, V.; Pinto, I. M.; Pitkin, M.; Pletsch, H. J.; Pöld, J.; Postiglione, F.; Poux, C.; Predoi, V.; Prestegard, T.; Price, L. R.; Prijatelj, M.; Privitera, S.; Prokhorov, L. G.; Puncken, O.; Quetschke, V.; Quintero, E.; Quitzow-James, R.; Raab, F. J.; Radkins, H.; Raffai, P.; Raja, S.; Rakhmanov, M.; Ramet, C.; Raymond, V.; Reed, C. M.; Reed, T.; Reid, S.; Reitze, D. H.; Riesen, R.; Riles, K.; Roberts, M.; Robertson, N. A.; Robinson, E. L.; Roddy, S.; Rodriguez, C.; Rodriguez, L.; Rodruck, M.; Rollins, J. G.; Romie, J. H.; Röver, C.; Rowan, S.; Rüdiger, A.; Ryan, K.; Salemi, F.; Sammut, L.; Sandberg, V.; Sanders, J.; Sankar, S.; Sannibale, V.; Santamaría, L.; Santiago-Prieto, I.; Santostasi, G.; Sathyaprakash, B. S.; Saulson, P. R.; Savage, R. L.; Schilling, R.; Schnabel, R.; Schofield, R. M. S.; Schuette, D.; Schulz, B.; Schutz, B. F.; Schwinberg, P.; Scott, J.; Scott, S. M.; Seifert, F.; Sellers, D.; Sengupta, A. S.; Sergeev, A.; Shaddock, D. A.; Shahriar, M. S.; Shaltev, M.; Shao, Z.; 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.; Son, E. J.; Sorazu, B.; Souradeep, T.; Stefszky, M.; Steinert, E.; Steinlechner, J.; Steinlechner, S.; Steplewski, S.; Stevens, D.; Stochino, A.; Stone, R.; Strain, K. A.; Strigin, S. E.; Stroeer, A. S.; Stuver, A. L.; Summerscales, T. Z.; Susmithan, S.; Sutton, P. J.; Szeifert, G.; Talukder, D.; Tanner, D. B.; Tarabrin, S. P.; Taylor, R.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Tiwari, V.; Tokmakov, K. V.; Tomlinson, C.; Torres, C. V.; Torrie, C. I.; Traylor, G.; Tse, M.; Ugolini, D.; Unnikrishnan, C. S.; Vahlbruch, H.; Vallisneri, M.; van der Sluys, M. V.; van Veggel, A. A.; Vass, S.; Vaulin, R.; Vecchio, A.; Veitch, P. J.; Veitch, J.; Venkateswara, K.; Verma, S.; Vincent-Finley, R.; Vitale, S.; Vo, T.; Vorvick, C.; Vousden, W. D.; Vyatchanin, S. P.; Wade, A.; Wade, L.; Wade, M.; Waldman, S. J.; Wallace, L.; Wan, Y.; Wang, M.; Wang, J.; 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.; Wiseman, A. G.; White, D. J.; Whiting, B. F.; Wiesner, K.; Wilkinson, C.; Willems, P. A.; Williams, L.; Williams, R.; Williams, T.; Willis, J. L.; Willke, B.; Wimmer, M.; Winkelmann, L.; Winkler, W.; Wipf, C.; Wittel, H.; Woan, G.; Wooley, R.; Worden, J.; Yablon, J.; Yakushin, I.; Yamamoto, H.; Yancey, C. C.; Yang, H.; Yeaton-Massey, D.; Yoshida, S.; Yum, H.; Zanolin, M.; Zhang, F.; Zhang, L.; Zhao, C.; Zhu, H.; Zhu, X. J.; Zotov, N.; Zucker, M. E.; Zweizig, J.

    2013-08-01

    Nearly a century after Einstein first predicted the existence of gravitational waves, a global network of Earth-based gravitational wave observatories is seeking to directly detect this faint radiation using precision laser interferometry. Photon shot noise, due to the quantum nature of light, imposes a fundamental limit on the attometre-level sensitivity of the kilometre-scale Michelson interferometers deployed for this task. Here, we inject squeezed states to improve the performance of one of the detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) beyond the quantum noise limit, most notably in the frequency region down to 150 Hz, critically important for several astrophysical sources, with no deterioration of performance observed at any frequency. With the injection of squeezed states, this LIGO detector demonstrated the best broadband sensitivity to gravitational waves ever achieved, with important implications for observing the gravitational-wave Universe with unprecedented sensitivity.

  1. Tail effect in gravitational radiation reaction: Time nonlocality and renormalization group evolution

    NASA Astrophysics Data System (ADS)

    Galley, Chad R.; Leibovich, Adam K.; Porto, Rafael A.; Ross, Andreas

    2016-06-01

    We use the effective field theory (EFT) framework to calculate the tail effect in gravitational radiation reaction, which enters at the fourth post-Newtonian order in the dynamics of a binary system. The computation entails a subtle interplay between the near (or potential) and far (or radiation) zones. In particular, we find that the tail contribution to the effective action is nonlocal in time and features both a dissipative and a "conservative" term. The latter includes a logarithmic ultraviolet (UV) divergence, which we show cancels against an infrared (IR) singularity found in the (conservative) near zone. The origin of this behavior in the long-distance EFT is due to the point-particle limit—shrinking the binary to a point—which transforms a would-be infrared singularity into an ultraviolet divergence. This is a common occurrence in an EFT approach, which furthermore allows us to use renormalization group (RG) techniques to resum the resulting logarithmic contributions. We then derive the RG evolution for the binding potential and total mass/energy, and find agreement with the results obtained imposing the conservation of the (pseudo) stress-energy tensor in the radiation theory. While the calculation of the leading tail contribution to the effective action involves only one diagram, five are needed for the one-point function. This suggests logarithmic corrections may be easier to incorporate in this fashion. We conclude with a few remarks on the nature of these IR/UV singularities, the (lack of) ambiguities recently discussed in the literature, and the completeness of the analytic post-Newtonian framework.

  2. Observable signatures of a black hole ejected by gravitational-radiation recoil in a galaxy merger.

    PubMed

    Loeb, Abraham

    2007-07-27

    According to recent simulations, the coalescence of two spinning black holes (BHs) could lead to a BH remnant with recoil speeds of up to thousands of km s(-1). Here we examine the circumstances resulting from a gas-rich galaxy merger under which the ejected BH would carry an accretion disk and be observable. As the initial BH binary emits gravitational radiation and its orbit tightens, a hole is opened in the disk which delays the consumption of gas prior to the eventual BH ejection. The punctured disk remains bound to the ejected BH within the region where the gas orbital velocity is larger than the ejection speed. For a approximately 10(7) M[middle dot in circle] BH the ejected disk has a characteristic size of tens of thousands of Schwarzschild radii and an accretion lifetime of approximately 10(7) yr. During that time, the ejected BH could traverse a considerable distance and appear as an off-center quasar with a feedback trail along the path it left behind. PMID:17678347

  3. Resonance behaviour and partial averaging in a three-body system with gravitational radiation damping

    NASA Astrophysics Data System (ADS)

    Wardell, Zachary E.

    2003-05-01

    In a previous investigation, a model of three-body motion was developed which included the effects of gravitational radiation reaction. The aim was to describe the motion of a relativistic binary pulsar that is perturbed by a third mass and look for resonances between the binary and third-mass orbits. Numerical integration of an equation of relative motion that approximates the binary gives evidence of such resonances. These (m:n) resonances are defined for the present purposes by the resonance condition, mω= 2nΩ, where m and n are relatively prime integers and ω and Ω are the angular frequencies of the binary orbit and third-mass orbit (around the centre of mass of the binary), respectively. The resonance condition consequently fixes a value for the semimajor axis a of the binary orbit for the duration of the resonance because of the Kepler relationship ω=a-3/2. This paper outlines a method of averaging developed by Chicone, Mashhoon and Retzloff, which renders a non-linear system that undergoes resonance capture into a mathematically amenable form. This method is applied to the present system and one arrives at an analytical solution that describes the average motion during resonance. Furthermore, prominent features of the full non-linear system, such as the frequency of oscillation and antidamping, accord with their analytically derived formulae.

  4. An experiment to distinguish between diffusive and specular surfaces for thermal radiation in cryogenic gravitational-wave detectors

    NASA Astrophysics Data System (ADS)

    Sakakibara, Yusuke; Kimura, Nobuhiro; Suzuki, Toshikazu; Yamamoto, Kazuhiro; Tokoku, Chihiro; Uchiyama, Takashi; Kuroda, Kazuaki

    2015-07-01

    In cryogenic gravitational-wave detectors, one of the most important issues is the fast cooling of their mirrors and keeping them cool during operation to reduce thermal noise. For this purpose, the correct estimation of thermal-radiation heat transfer through the pipe-shaped radiation shield is vital to reduce the heat load on the mirrors. However, the amount of radiation heat transfer strongly depends on whether the surfaces reflect radiation rays diffusely or specularly. Here, we propose an original experiment to distinguish between diffusive and specular surfaces. This experiment has clearly shown that the examined diamond-like carbon-coated surface is specular. This result emphasizes the importance of suppressing the specular reflection of radiation in the pipe-shaped shield.

  5. Gravitational wave astronomy using spaceborne detectors

    NASA Astrophysics Data System (ADS)

    Rubbo, Louis Joseph, IV

    This dissertation explores the use of spaceborne gravitational wave detectors as observatories for studying sources of gravitational radiation. The next decade will see the launch of the first space-based gravitational wave detector. Planning for several follow on missions is already underway. Before these observatories are constructed, extensive studies into their responses, expected output, and data analysis techniques must be completed. In this dissertation these issues are addressed using the proposed Laser Interferometer Space Antenna as an exemplary model. The first original work presented here is a complete description of the response of a spaceborne detector to arbitrary gravitational wave signals. Previous analyses worked either in the static or low frequency limits. Part of this investigation is a coordinate free derivation of the response of a general detector valid for all frequencies and for arbitrary motion. Following directly from this result is The LISA Simulator, a virtual model of the LISA detector, in addition to an adiabatic approximation that extends the low frequency limit by two decades in the frequency domain. Unlike most electromagnetic telescopes, gravitational wave observatories do not return an image of a particular source. Instead they return a set of time series. Encoded within these time series are all of the sources whose gravitational radiation passes through the detector during its observational run. The second original work presented here is the extraction of multiple monochromatic, binary sources using data from multiple time series. For binaries isolated in frequency space and with a large signal to noise ratio, it is shown that these sources can be removed to a level that is below the local effective noise. A concern for the LISA mission is the large number of gravitational wave sources located within the Milky Way galaxy. The superposition of these sources will form a confusion limited background in the output of the detector

  6. 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.

  7. Detectors of gravitational waves

    NASA Astrophysics Data System (ADS)

    Pizzella, G.

    Gravitational waves Motion of test bodies in a g.w. field Energy carried by gravitational waves Gravitational-wave sources Spinning star Double-star systems Fall into a Schwarzschild black hole Radiation from gravitational collapse Gravitational-wave detectors The nonresonant detectors The resonant detectors Electromechnical transducers Piezoelectric ceramic The capacitor The inductor Data analysis The Brownian noise The back-action The wide-band noise, data analysis and optimization The resonant transducer The Wiener-Kolmogoroff filter The cross-section and the effective temperature The antenna bandwidth The gravitational-wave experiments in the world The laser interferometers The resonant detectors

  8. Haystack Observatory

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Radio astronomy programs comprise three very-long-baseline interferometer projects, ten spectral line investigations, one continuum mapping in the 0.8 cm region, and one monitoring of variable sources. A low-noise mixer was used in mapping observations of 3C273 at 31 GHz and in detecting of a new methyl alcohol line at 36,169 MHz in Sgr B2. The new Mark 2 VLBI recording terminal was used in galactic H2O source observations using Haystack and the Crimean Observatory, USSR. One feature in W29 appears to have a diameter of 0.3 millisec of arc and a brightness temperature of 1.4 x 10 to the 15th power K. Geodetic baseline measurements via VLBI between Green Bank and Haystack are mutually consistent within a few meters. Radar investigations of Mercury, Venus, Mars, and the Moon have continued. The favorable opposition of Mars and improvements in the radar permit measurements on a number of topographic features with unprecedented accuracy, including scarps and crater walls. The floor of Mare Serenitatis slopes upward towards the northeast and is also the location of a strong gravitational anomaly.

  9. Gravitational radiation detection with spacecraft Doppler tracking - Limiting sensitivities and prospective missions

    NASA Technical Reports Server (NTRS)

    Estabrook, F. B.; Hellings, R. W.; Wahlquist, H. D.; Wolff, R. S.

    1979-01-01

    The prospects of using spacecraft Doppler tracking, in NASA missions, for the detection of gravitational waves are examined. The sensitivity limits of such detection are characterized in terms of plasma scintillation, troposphere scintillation, receiver noise, MDA and ODA quantization error, and clock jitter. Current and possible future NASA missions that will involve gravitational wave experiments are briefly reviewed, including the Galileo, solar polar, Halley/Tempel-2, and solar probe missions.

  10. Detecting high-frequency gravitational waves with optically levitated sensors.

    PubMed

    Arvanitaki, Asimina; Geraci, Andrew A

    2013-02-15

    We propose a tunable resonant sensor to detect gravitational waves in the frequency range of 50-300 kHz using optically trapped and cooled dielectric microspheres or microdisks. The technique we describe can exceed the sensitivity of laser-based gravitational wave observatories in this frequency range, using an instrument of only a few percent of their size. Such a device extends the search volume for gravitational wave sources above 100 kHz by 1 to 3 orders of magnitude, and could detect monochromatic gravitational radiation from the annihilation of QCD axions in the cloud they form around stellar mass black holes within our galaxy due to the superradiance effect. PMID:25166367

  11. 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.

  12. Reconstruction of global solar radiation time series from 1933 to 2013 at the Izaña Atmospheric Observatory

    NASA Astrophysics Data System (ADS)

    García, R. D.; Cuevas, E.; García, O. E.; Cachorro, V. E.; Pallé, P.; Bustos, J. J.; Romero-Campos, P. M.; de Frutos, A. M.

    2014-09-01

    This paper presents the reconstruction of the 80-year time series of daily global solar radiation (GSR) at the subtropical high-mountain Izaña Atmospheric Observatory (IZO) located in Tenerife (The Canary Islands, Spain). For this purpose, we combine GSR estimates from sunshine duration (SD) data using the Ångström-Prescott method over the 1933/1991 period, and GSR observations directly performed by pyranometers between 1992 and 2013. Since GSR measurements have been used as a reference, a strict quality control has been applied based on principles of physical limits and comparison with LibRadtran model. By comparing with high quality GSR measurements, the precision and consistency over time of GSR estimations from SD data have been successfully documented. We obtain an overall root mean square error (RMSE) of 9.2% and an agreement between the variances of GSR estimations and GSR measurements within 92%. Nonetheless, this agreement significantly increases when the GSR estimation is done considering different daily fractions of clear sky (FCS). In that case, RMSE is reduced by half, to about 4.5%, when considering percentages of FCS > 40% (~ 90% of days in the testing period). Furthermore, we prove that the GSR estimations can monitor the GSR anomalies in consistency with GSR measurements and, then, can be suitable for reconstructing solar radiation time series. The reconstructed IZO GSR time series between 1933 and 2013 confirms change points and periods of increases/decreases of solar radiation at Earth's surface observed at a global scale, such as the early brightening, dimming and brightening. This fact supports the consistency of the IZO GSR time series presented in this work, which may be a reference for solar radiation studies in the subtropical North Atlantic region.

  13. Analysis of Snow Albedo, Grain Size and Radiative Forcing based on the Airborne Snow Observatory (ASO) Imaging Spectroscopy Data

    NASA Astrophysics Data System (ADS)

    Seidel, F. C.; Painter, T. H.

    2013-12-01

    Climate is expected to be most vulnerable in mountainous and arctic regions where the atmosphere and the hydrosphere are directly linked to the cryosphere. A combination of modeling and large-scale observational efforts is required to investigate related scientific questions. NASA's Airborne Snow Observatory (ASO) at the Jet Propulsion Laboratory addresses some of these needs by establishing new quantitative observational capabilities in regional mapping of mountain snow properties. In addition, ASO's key products showed that we are able to achieve societal benefits by improving water resources management. We will show the first analysis of snow optical products (albedo, grain size, and radiative forcing) from the spring 2013 ASO campaign in the Sierra Nevada, CA, USA. In addition, we will present the retrieval methods used to derive these products based on airborne imaging spectroscopy, LiDAR, as well as radiative transfer models. The preliminary findings provide new important insights into the temporal and spatial aspects of Western US mountain snow and its melt.

  14. Gravitational Wave (GW) Radiation Pattern at the Focus of a High-Frequency GW (HFGW) Generator and Aerospace Applications

    NASA Astrophysics Data System (ADS)

    Baker, Robert M. L.; Davis, Eric W.; Woods, R. C.

    2005-02-01

    The Gravitational Wave (GW) radiation pattern is derived that results from a rod rotating about a pivot, a dumbbell rotating about its central axis, a pair of stars rotating about their orbital focus, or a stationary circular asymmetrical-array of tangentially jerking elements. The three-dimensional shape of the GW radiation pattern is like a dumbbell cross-section having its long axis perpendicular to the plane of motion or along the central axis of the stationary ring of sequentially jerking elements. The center of the radiation pattern is situated at the pivot, orbital-focus, or center of the stationary array. Knowledge of the GW radiation pattern allows for optimum placement of a detector. In the case of High-Frequency Gravitational Waves (HFGWs), in which the diffraction of the GW radiation is less than the dimensions of the ring of jerking elements, the radiation pattern is situated at the center of the ring and represents a focus or concentration point of the HFGWs, The concentration point extends over a diffraction-limited spot having a radius of λGW/π, where λGW is the wavelength of the HFGW. In the case of a superconductor, prior research, although speculative has shown that the GW wavelength is foreshortened by a factor of about 300. Thus there could be a much more concentrated diffraction-limited flux of HFGW at the focus. It is shown that the efficiency of a HFGW communications link could be approximately proportional to the sixth power of the HFGW frequency. Applications to space technology, involving aerospace communications, and Astronomy are discussed.

  15. Simulating Gravitational Radiation from Binary Black Holes Mergers as LISA Sources

    NASA Technical Reports Server (NTRS)

    Baker, John

    2005-01-01

    A viewgraph presentation on the simulation of gravitational waves from Binary Massive Black Holes with LISA observations is shown. The topics include: 1) Massive Black Holes (MBHs); 2) MBH Binaries; 3) Gravitational Wavws from MBH Binaries; 4) Observing with LISA; 5) How LISA sees MBH binary mergers; 6) MBH binary inspirals to LISA; 7) Numerical Relativity Simulations; 8) Numerical Relativity Challenges; 9) Recent Successes; 10) Goddard Team; 11) Binary Black Hole Simulations at Goddard; 12) Goddard Recent Advances; 13) Baker, et al.:GSFC; 13) Starting Farther Out; 14) Comparing Initial Separation; 15) Now with AMR; and 16) Conclusion.

  16. Bianchi VI cosmological models representing perfect fluid and radiation with electric-type free gravitational fields

    NASA Astrophysics Data System (ADS)

    Roy, S. R.; Banerjee, S. K.

    1992-11-01

    A homogeneous Bianchi type VIh cosmological model filled with perfect fluid, null electromagnetic field and streaming neutrinos is obtained for which the free gravitational field is of the electric type. The barotropic equation of statep = (γ-1)ɛ is imposed in the particular case of Bianchi VI0 string models. Various physical and kinematical properties of the models are discussed.

  17. Orbital Observatory GLAST - New Step in the Study of Cosmic Gamma Radiation: Mission Overview

    NASA Technical Reports Server (NTRS)

    Moiseev, Alexander

    2008-01-01

    This viewgraph presentation is a overview of the Gamma-ray Large Area Space Telescope (GLAST), now named Fermi Space Telescope. The new telescope is scheduled for launch in the middle of 2008. It contains the high energy gamma-ray telescope LAT (Large Area Telescope) and the GMB (GLAST Burst Monitor). The science objectives of GLAST cover almost every area of high energy astrophysics, including Active Galactic Nuclei (AGN), including Extragalactic background light (EBL), Gamma-ray bursts (GRB), Pulsars, Diffuse gamma-radiation, EGRET unidentified sources, Solar physics, Origin of Cosmic Rays and, Dark Matter and New Physics. Also included in this overview is a discussion of the preparation to the analysis of the science data.

  18. The effect of radiation pressure on planar, self-gravitating H II regions and its neutral environment

    NASA Astrophysics Data System (ADS)

    Rodríguez-Ramírez, J. C.; Raga, A. C.

    2016-08-01

    We study the hydrostatic configuration of an isothermal gas layer surrounding a planar distribution of stars, in which the gravitational effects (due to the stars and the self-gravity of the gas) and the radiation pressure due to dust absorption and photoionization of H are important. We consider an infinite planar distribution, and derive a model for the vertical stratification. We obtain the density profiles of a photoionized gas layer, which is covered by a neutral region. We find that the solutions range between cases in which the photoionized layer extends to infinity, to cases in which the vertical extent of the photoionized layer is negligible in comparison with the characteristic height of the enclosing, neutral layer. We find that in cases with a significant dust content, the effect of the radiation pressure together with the self-gravity generates dense, narrow neutral layers in which further star formation might occur.

  19. Beyond Advanced Gravitational Wave Detectors: Beating the Quantum Limit with Squeezed States of Light

    NASA Astrophysics Data System (ADS)

    Barsotti, Lisa

    2013-04-01

    After two decades of technology development, the first direct observation of gravitational waves appears to be imminent. Ground-based interferometric gravitational wave detectors world-wide are about to come back on-line after a major upgrade aimed to significantly improve their sensitivity. As these advanced detectors become a reality, the gravitational wave community is looking at new ways of further expanding their astrophysical reach. The quantum nature of light imposes a fundamental limit to the sensitivity that gravitational wave detectors can achieve, due to statistical fluctuations in the arrival time of photons at the interferometer output (shot noise) and the recoil of the mirrors due to radiation pressure noise. In this talk I will show how mature technology can be used to push interferometric precision measurement beyond the standard quantum limit by means of squeezed states of light, and current ideas on how to integrate this technology into the Advanced detectors of the Laser Interferometer Gravitational wave Observatory (LIGO).

  20. Angular velocity of gravitational radiation from precessing binaries and the corotating frame

    NASA Astrophysics Data System (ADS)

    Boyle, Michael

    2013-05-01

    This paper defines an angular velocity for time-dependent functions on the sphere and applies it to gravitational waveforms from compact binaries. Because it is geometrically meaningful and has a clear physical motivation, the angular velocity is uniquely useful in helping to solve an important—and largely ignored—problem in models of compact binaries: the inverse problem of deducing the physical parameters of a system from the gravitational waves alone. It is also used to define the corotating frame of the waveform. When decomposed in this frame, the waveform has no rotational dynamics and is therefore as slowly evolving as possible. The resulting simplifications lead to straightforward methods for accurately comparing waveforms and constructing hybrids. As formulated in this paper, the methods can be applied robustly to both precessing and nonprecessing waveforms, providing a clear, comprehensive, and consistent framework for waveform analysis. Explicit implementations of all these methods are provided in accompanying computer code.

  1. Gravitational Radiation - a New Window Onto the Universe. (Karl Schwarzschild Lecture 1996)

    NASA Astrophysics Data System (ADS)

    Thorne, K. S.

    A summary is given of the current status and plans for gravitational-wave searches at all plausible wavelengths, from the size of the observable universe to a few kilometers. The anticipated scientific payoff from these searches is described, including expectations for detailed studies of black holes and neutron stars, high-accuracy tests of general relativity, and hopes for the discovery of exotic new kinds of objects.

  2. Measurements of solar radiation at Mauna Loa Observatory, 1978-1985, with emphasis on the effects of the eruption of El Chichon. Data report

    SciTech Connect

    Dutton, E.G.; DeLuisi, J.J.; Austring, A.P.

    1987-07-01

    Results from three different projects that involved either absolute or relative measurement of solar radiation at the NOAA Mauna Loa Observatory are reported. Included are measurements, in summary form, of broadband solar irradiance, spectral aerosol optical depth, and spectral diffuse-sky irradiance. Each data set includes the influence of the stratospheric debris from the eruption of El Chichon. Procedures that were used to acquire and finalize the observational records are documented.

  3. Low-Frequency Gravitational Radiation from Coalescing Massive Black Hole Binaries in Hierarchical Cosmologies

    NASA Astrophysics Data System (ADS)

    Sesana, Alberto; Haardt, Francesco; Madau, Piero; Volonteri, Marta

    2004-08-01

    We compute the expected low-frequency gravitational wave signal from coalescing massive black hole (MBH) binaries at the center of galaxies in a hierarchical structure formation scenario in which seed holes of intermediate mass form far up in the dark halo ``merger tree.'' The merger history of dark matter halos and associated MBHs is followed via cosmological Monte Carlo realizations of the merger hierarchy from redshift z=20 to the present in a ΛCDM cosmology. MBHs get incorporated through halo mergers into larger and larger structures, sink to the center because of dynamical friction against the dark matter background, accrete cold material in the merger remnant, and form MBH binary systems. Stellar dynamical (three-body) interactions cause the hardening of the binary at large separations, while gravitational wave emission takes over at small radii and leads to the final coalescence of the pair. A simple scheme is applied in which the ``loss cone'' is constantly refilled and a constant stellar density core forms because of the ejection of stars by the shrinking binary. The integrated emission from inspiraling MBH binaries at all redshifts is computed in the quadrupole approximation and results in a gravitational wave background (GWB) with a well-defined shape that reflects the different mechanisms driving the late orbital evolution. The characteristic strain spectrum has the standard hc(f)~f-2/3 behavior only in the range f=10-9to10-6 Hz. At lower frequencies the orbital decay of MBH binaries is driven by the ejection of background stars (``gravitational slingshot''), and the strain amplitude increases with frequency, hc(f)~f. In this range the GWB is dominated by 109-1010 Msolar MBH pairs coalescing at 0<~z<~2. At higher frequencies, f>10-6Hz, the strain amplitude, as steep as hc(f)~f-1.3, is shaped by the convolution of last stable circular orbit emission by lighter binaries (102-107 Msolar) populating galaxy halos at all redshifts. We discuss the

  4. Shuttle and Transfer Orbit Thermal Analysis and Testing of the Chandra X-Ray Observatory Charge-Couple Device Imaging Spectrometer Radiator Shades

    NASA Technical Reports Server (NTRS)

    Sharp, John R.

    1999-01-01

    Thermal analyses of the Shuttle and Transfer Orbit of the Advanced X-Ray Astrophysics Facility Charge-Coupled Device (CCD) Imaging Spectrometer (ACIS), one of two science instruments on the Chandra X-Ray Observatory, revealed a low-earth orbit (LEO) overheating problem on the goldized Kapton faces of two radiator shades. The shades were coated with the goldized Kapton to provide a low hemispherical emittance to minimize direct and backloaded heating from the sun and the observatory and high specularity to optimize the coupling to space on two passive radiators which cool the focal plane to -120 C +/- 1 C during on-orbit operations. Since the observatory has a highly elliptical final orbit of 10,000 kilometers by 140,000 kilometers and the ACIS radiators and shades are oriented anti-sun, the high solar absorptance to emittance ratio of the goldized Kapton was not an issue. However, during Shuttle bay-to-earth operations, the short duration solar heating occurring near the eclipse entry and exit resulted in shade temperatures in excess of the cure temperature of the adhesive used to bond the goldized Kapton and honeycomb face-sheets. The detailed thermal analysis demonstrating the LEO overheating as well as the redesign options and thermal testing of a redesigned development unit shade are presented.

  5. Influence of dust charge fluctuation and polarization force on radiative condensation instability of magnetized gravitating dusty plasma

    NASA Astrophysics Data System (ADS)

    Prajapati, R. P.; Bhakta, S.

    2015-10-01

    The influence of dust charge fluctuation, thermal speed and polarization force due to massive charged dust grains is studied on the radiative condensation instability (RCI) of magnetized self-gravitating astrophysical dusty (complex) plasma. The dynamics of the charged dust and inertialess electrons are considered while the Boltzmann distributed ions are assumed to be thermal. The dusty fluid model is formulated and the general dispersion relations are derived analytically using the plane wave solutions under the long wavelength limits in both the presence and the absence of dust charge fluctuations. The combined effects of polarization force, dust thermal speed, dust charge fluctuation and dust cyclotron frequency are observed on the low frequency wave modes and radiative modified Jeans Instability. The classical criterion of RCI is also derived which remains unaffected due to the presence of these parameters. Numerical calculations have been performed to calculate the growth rate of the system and plotted graphically. We find that dust charge fluctuation, radiative cooling and polarization force have destabilizing while dust thermal speed and dust cyclotron frequency have stabilizing influence on the growth rate of Jeans instability. The results have been applied to understand the radiative cooling process in dusty molecular cloud when both the dust charging and polarization force are dominant.

  6. High-energy radiation from thunderstorms and lightning with the Large Observatory for x-ray Timing (LOFT) mission

    NASA Astrophysics Data System (ADS)

    Marisaldi, Martino; Smith, David M.; Brandt, Søren; Briggs, Michael S.; Budz-Jørgensen, Carl; Campana, Riccardo; Carlson, Brant E.; Celestin, Sebastien; Connaughton, Valerie; Cummer, Steven A.; Dwyer, Joseph R.; Fishman, Gerald J.; Fullekrug, Martin; Fuschino, Fabio; Gjesteland, Thomas; Neubert, Torsten; Østgaard, Nikolai; Tavani, Marco

    2015-04-01

    We explore the possible contributions of the Large Observatory for X-ray Timing (LOFT) mission to the study of high-energy radiation from thunderstorms and lightning. LOFT is a mission dedicated to X-ray timing studies of astrophysical sources, characterised by a very large effective area of about 8.5 square meters at 8 keV. Although the main scientific target of the mission is the fundamental physics of matter under extreme conditions, the peculiar instrument concept allows significant contributions to a wide range of other science topics, including the cross-disciplinary field of high-energy atmospheric physics, at the crossroad between geophysics, space physics and astrophysics. In this field we foresee the following major contributions: detect ˜ 700 Terrestrial Gamma-ray Flashes (TGFs) per year, probing the TGF intensity distribution at low fluence values and providing an unbiased sample of bright events thanks to the intrinsic robustness against dead-time and pile-up; provide the largest TGF detection rate surface density above the equator, allowing for correlation studies with lightning activity on short time scales and small regional scales, to probe the TGF / lightning relationship; lower by a factor ˜ 5 the minimum detectable fluence for Terrestrial Electron Beams (TEBs), an additional tool to probe TGF production mechanism and the lower edge of TGF intensity distribution; open up a discovery space for the detection of high-altitude electron beams and weak X-ray emissions associated to Transient Luminous Events (TLEs). LOFT has been studied as a candidate ESA M3 mission during an extensive assessment phase. The high level of readiness and maturity of the mission, as well as the clean and solid assessment of its unique science case, make LOFT a competitive mission with a compelling science case. For this reason, its development has been continued, aiming at new launch opportunities.

  7. COEXISTENCE OF GRAVITATIONALLY-BOUND AND RADIATION-DRIVEN C IV EMISSION LINE REGIONS IN ACTIVE GALACTIC NUCLEI

    SciTech Connect

    Wang Huiyuan; Wang Tinggui; Zhou Hongyan; Liu Bo; Dong Xiaobo; Wang Jianguo

    2011-09-01

    There are mutually contradictory views in the literature of the kinematics and structure of high-ionization line (e.g., C IV) emitting regions in active galactic nuclei (AGNs). Two kinds of broad emission line region (BELR) models have been proposed, outflow and gravitationally-bound BELR, which are supported, respectively, by blueshift of the C IV line and reverberation mapping observations. To reconcile these two apparently different models, we present a detailed comparison study between the C IV and Mg II lines using a sample of AGNs selected from the Sloan Digital Sky Survey. We find that the kinematics of the C IV region is different from that of Mg II, which is thought to be controlled by gravity. A strong correlation is found between the blueshift and asymmetry of the C IV profile and the Eddington ratio. This provides strong observational support for the postulation that the outflow is driven by radiation pressure. In particular, we find robust evidence that the C IV line region is largely dominated by outflow at high Eddington ratios, while it is primarily gravitationally-bounded at low Eddington ratios. Our results indicate that these two emitting regions coexist in most AGNs. The emission strength from these two gases varies smoothly with Eddington ratio in opposite ways. This explanation naturally reconciles the apparently contradictory views proposed in previous studies. Finally, candidate models are discussed which can account for both the enhancement of outflow emission and suppression of normal BEL in AGNs with high Eddington ratios.

  8. Nearly scale invariant spectrum of gravitational radiation from global phase transitions.

    PubMed

    Jones-Smith, Katherine; Krauss, Lawrence M; Mathur, Harsh

    2008-04-01

    Using a large N sigma model approximation we explicitly calculate the power spectrum of gravitational waves arising from a global phase transition in the early Universe and we confirm that it is scale invariant, implying an observation of such a spectrum may not be a unique feature of inflation. Moreover, the predicted amplitude can be over 3 orders of magnitude larger than the naive dimensional estimate, implying that even a transition that occurs after inflation may dominate in cosmic microwave background polarization or other gravity wave signals. PMID:18517931

  9. Low-mass neutron stars: universal relations, the nuclear symmetry energy and gravitational radiation

    NASA Astrophysics Data System (ADS)

    Silva, Hector O.; Sotani, Hajime; Berti, Emanuele

    2016-04-01

    The lowest neutron star masses currently measured are in the range 1.0 - 1.1~M⊙, but these measurement have either large uncertainties or refer to isolated neutron stars. The recent claim of a precisely measured mass M/M⊙ = 1.174 ± 0.004 (Martinez et al. 2015) in a double neutron star system suggests that low-mass neutron stars may be an interesting target for gravitational-wave detectors. Furthermore, Sotani et al. (2014) recently found empirical formulas relating the mass and surface redshift of nonrotating neutron stars to the star's central density and to the parameter η ≡ (K0L2)1/3, where K0 is the incompressibility of symmetric nuclear matter and L is the slope of the symmetry energy at saturation density. Motivated by these considerations, we extend the work by Sotani et al. (2014) to slowly rotating and tidally deformed neutron stars. We compute the moment of inertia, quadrupole moment, quadrupole ellipticity, tidal and rotational Love number and apsidal constant of slowly rotating neutron stars by integrating the Hartle-Thorne equations at second order in rotation, and we fit all of these quantities as functions of η and of the central density. These fits may be used to constrain η, either via observations of binary pulsars in the electromagnetic spectrum, or via near-future observations of inspiralling compact binaries in the gravitational-wave spectrum.

  10. Low-mass neutron stars: universal relations, the nuclear symmetry energy and gravitational radiation

    NASA Astrophysics Data System (ADS)

    Silva, Hector O.; Sotani, Hajime; Berti, Emanuele

    2016-07-01

    The lowest neutron star masses currently measured are in the range 1.0-1.1 M⊙, but these measurement have either large uncertainties or refer to isolated neutron stars. The recent claim of a precisely measured mass M/M⊙ = 1.174 ± 0.004 (Martinez et al. 2015) in a double neutron star system suggests that low-mass neutron stars may be an interesting target for gravitational-wave detectors. Furthermore, Sotani et al. recently found empirical formulas relating the mass and surface redshift of non-rotating neutron stars to the star's central density and to the parameter η ≡ (K0L2)1/3, where K0 is the incompressibility of symmetric nuclear matter and L is the slope of the symmetry energy at saturation density. Motivated by these considerations, we extend the work by Sotani et al. to slowly rotating and tidally deformed neutron stars. We compute the moment of inertia, quadrupole moment, quadrupole ellipticity, tidal and rotational Love number and apsidal constant of slowly rotating neutron stars by integrating the Hartle-Thorne equations at second order in rotation, and we fit all of these quantities as functions of η and of the central density. These fits may be used to constrain η, either via observations of binary pulsars in the electromagnetic spectrum, or via near-future observations of inspiralling compact binaries in the gravitational-wave spectrum.

  11. Interplanetary phase scintillation and the search for very low frequency gravitational radiation

    NASA Technical Reports Server (NTRS)

    Armstrong, J. W.; Woo, R.; Estabrook, F. B.

    1979-01-01

    Observations of radio-wave phase scintillation are reported which used the Viking spacecraft having an earth-spacecraft link very similar to that which will be used in very low-frequency (VLF) gravitational-wave searches. The phase power-spectrum level varies by seven orders of magnitude as the sun-earth-spacecraft (elongation) angle changes from 1 to 175 deg. It is noteworthy that a broad minimum in the S-band (2.3 GHz) phase fluctuation occurs in the antisolar direction; the corresponding fractional frequency stability (square root Allan variance) is about 3 x 10 to the -14th for 1000-s integration times. A simultaneous two-frequency two-station observation indicates that the contribution to the phase fluctuation from the ionosphere is significant but dominated by the contribution from the interplanetary medium. Nondispersive tropospheric scintillation was not detected (upper limit to fractional frequency stability about 5 x 10 to the -14th). Evidently, even observations in the antisolar direction will require higher radio frequencies, phase scintillation calibration, and correlation techniques in the data processing, for detection of gravitational bursts at the anticipated strain amplitude levels of no more than 10 to the -15th.

  12. Astronomical observatories

    NASA Technical Reports Server (NTRS)

    Ponomarev, D. N.

    1983-01-01

    The layout and equipment of astronomical observatories, the oldest scientific institutions of human society are discussed. The example of leading observatories of the USSR allows the reader to familiarize himself with both their modern counterparts, as well as the goals and problems on which astronomers are presently working.

  13. Ondrejov Observatory

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    The Ondrejov Observatory is located 20 miles from Prague in the village of Ondrejov. It was established in 1898 as a private observatory and donated to the state of Czechoslovakia in 1928. Since 1953 it has been part of the Astronomical Institute, Academy of Sciences of the Czech Republic; there are 40 astronomers....

  14. Amateur Observatories

    NASA Astrophysics Data System (ADS)

    Gavin, M.

    1997-08-01

    A roundup of amateur observatories in this country and abroad, with construction and location details, concluding with a detailed description and architect's drawing of the author's own observatory at Worcester Park, Surrey. The text of the 1996 Presidential Address to the British Astronomical Association.

  15. Gravitational radiation and angular momentum flux from a slowly rotating dynamical black hole

    SciTech Connect

    Wu, Yu-Huei; Wang, Chih-Hung

    2011-04-15

    A four-dimensional asymptotic expansion scheme is used to study the next-order effects of the nonlinearity near a spinning dynamical black hole. The angular-momentum flux and energy flux formula are then obtained by constructing the reference frame in terms of the compatible constant spinors and the compatibility of the coupling leading-order Newman-Penrose equations. By using the slow rotation and small-tide approximation for a spinning black hole, the horizon cross-section we chose is spherical symmetric. It turns out the flux formula is rather simple and can be compared with the known results. Directly from the energy flux formula of the slow-rotating dynamical horizon, we find that the physically reasonable condition on requiring the positivity of the gravitational energy flux yields that the shear will monotonically decrease with time. Thus a slow-rotating dynamical horizon will asymptotically approach an isolated horizon during late time.

  16. THE BENEFITS OF VLBI ASTROMETRY TO PULSAR TIMING ARRAY SEARCHES FOR GRAVITATIONAL RADIATION

    SciTech Connect

    Madison, D. R.; Chatterjee, S.; Cordes, J. M.

    2013-11-10

    Precision astrometry is an integral component of successful pulsar timing campaigns. Astrometric parameters are commonly derived by fitting them as parameters of a timing model to a series of pulse times of arrival (TOAs). TOAs measured to microsecond precision over spans of several years can yield position measurements with sub-milliarcsecond precision. However, timing-based astrometry can become biased if a pulsar displays any red spin noise or a red signal produced by the stochastic gravitational wave background. We investigate how noise of different spectral types is absorbed by timing models, leading to significant estimation biases in the astrometric parameters. We find that commonly used techniques for fitting timing models in the presence of red noise (Cholesky whitening) prevent the absorption of noise into the timing model remarkably well if the time baseline of observations exceeds several years, but are inadequate for dealing with shorter pulsar data sets. Independent of timing, pulsar-optimized very long baseline interferometry (VLBI) is capable of providing position estimates precise to the sub-milliarcsecond levels needed for high-precision timing. In order to make VLBI astrometric parameters useful in pulsar timing models, the transformation between the International Celestial Reference Frame (ICRF) and the dynamical solar system ephemeris used for pulsar timing must be constrained to within a few microarcseconds. We compute a transformation between the ICRF and pulsar timing frames and quantitatively discuss how the transformation will improve in coming years. We find that incorporating VLBI astrometry into the timing models of pulsars for which only a couple of years of timing data exist will lead to more realistic assessments of red spin noise and could enhance the amplitude of gravitational wave signatures in post-fit timing residuals by factors of 20 or more.

  17. Recent developments in the measurement of space time curvature. [resonant capacitor displacement sensor and multistage suspension system for gravitational radiation antenna

    NASA Technical Reports Server (NTRS)

    Richard, J.-P.

    1978-01-01

    Development of a highly sensitive resonant capacitor displacement sensor and a multistage suspension system for a low-temperature gravitational radiation antenna is discussed; the antenna is suitable for studying gravitational collapses. The sensitivity limit of the device is assessed as a function of preamplifier noise. Experiments indicate that an electric field of about 160,000 v/cm may be applied to the resonator surface without a significant increase in Brownian noise. Use of the resonant capacitor sensor with very high Q antennae is also considered.

  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. Joint approach for reducing eccentricity and spurious gravitational radiation in binary black hole initial data construction

    NASA Astrophysics Data System (ADS)

    Zhang, Fan; Szilágyi, Béla

    2013-10-01

    At the beginning of binary black hole simulations, there is a pulse of spurious radiation (or junk radiation) resulting from the initial data not matching astrophysical quasi-equilibrium inspiral exactly. One traditionally waits for the junk radiation to exit the computational domain before taking physical readings, at the expense of throwing away a segment of the evolution, and with the hope that junk radiation exits cleanly. We argue that this hope does not necessarily pan out, as junk radiation could excite long-lived constraint violation. Another complication with the initial data is that they contain orbital eccentricity that needs to be removed, usually by evolving the early part of the inspiral multiple times with gradually improved input parameters. We show that this procedure is also adversely impacted by junk radiation. In this paper, we do not attempt to eliminate junk radiation directly, but instead tackle the much simpler problem of ameliorating its long-lasting effects. We report on the success of a method that achieves this goal by combining the removal of junk radiation and eccentricity into a single procedure. Namely, we periodically stop a low resolution simulation; take the numerically evolved metric data and overlay it with eccentricity adjustments; run it through an initial data solver (i.e. the solver receives as free data the numerical output of the previous iteration); restart the simulation; repeat until eccentricity becomes sufficiently low; and then launch the high resolution “production run” simulation. This approach has the following benefits: (1) We do not have to contend with the influence of junk radiation on eccentricity measurements for later iterations of the eccentricity reduction procedure. (2) We reenforce constraints every time the initial data solver is invoked, removing the constraint violation excited by junk radiation previously. (3) The wasted simulation segment associated with the junk radiation’s evolution is

  20. Laboratory simulation of Euclid-like sky images to study the impact of CCD radiation damage on weak gravitational lensing

    NASA Astrophysics Data System (ADS)

    Prod'homme, T.; Verhoeve, P.; Oosterbroek, T.; Boudin, N.; Short, A.; Kohley, R.

    2014-07-01

    Euclid is the ESA mission to map the geometry of the dark universe. It uses weak gravitational lensing, which requires the accurate measurement of galaxy shapes over a large area in the sky. Radiation damage in the 36 Charge-Coupled Devices (CCDs) composing the Euclid visible imager focal plane has already been identified as a major contributor to the weak-lensing error budget; radiation-induced charge transfer inefficiency (CTI) distorts the galaxy images and introduces a bias in the galaxy shape measurement. We designed a laboratory experiment to project Euclid-like sky images onto an irradiated Euclid CCD. In this way - and for the first time - we are able to directly assess the effect of CTI on the Euclid weak-lensing measurement free of modelling uncertainties. We present here the experiment concept, setup, and first results. The results of such an experiment provide test data critical to refine models, design and test the Euclid data processing CTI mitigation scheme, and further optimize the Euclid CCD operation.

  1. Convergence of smoothed particle hydrodynamics simulations of self-gravitating accretion discs: sensitivity to the implementation of radiative cooling

    NASA Astrophysics Data System (ADS)

    Rice, W. K. M.; Forgan, D. H.; Armitage, P. J.

    2012-02-01

    Recent simulations of self-gravitating accretion discs, carried out using a three-dimensional smoothed particle hydrodynamics (SPH) code by Meru & Bate, have been interpreted as implying that three-dimensional global discs fragment much more easily than would be expected from a two-dimensional local model. Subsequently, global and local two-dimensional models have been shown to display similar fragmentation properties, leaving it unclear whether the three-dimensional results reflect a physical effect or a numerical problem associated with the treatment of cooling or artificial viscosity in SPH. Here, we study how fragmentation of self-gravitating disc flows in SPH depends upon the implementation of cooling. We run disc simulations that compare a simple cooling scheme, in which each particle loses energy based upon its internal energy per unit mass, with a method in which the cooling is derived from a smoothed internal energy density field. For the simple per particle cooling scheme, we find a significant increase in the minimum cooling time-scale for fragmentation with increasing resolution, matching previous results. Switching to smoothed cooling, however, results in lower critical cooling time-scales, and tentative evidence for convergence at the highest spatial resolution tested. We conclude that precision studies of fragmentation using SPH require careful consideration of how cooling (and, probably, artificial viscosity) is implemented, and that the apparent non-convergence of the fragmentation boundary seen in prior simulations is likely a numerical effect. In real discs, where cooling is physically smoothed by radiative transfer effects, the fragmentation boundary is probably displaced from the two-dimensional value by a factor that is only of the order of unity.

  2. NASA'S Great Observatories

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Why are space observatories important? The answer concerns twinkling stars in the night sky. To reach telescopes on Earth, light from distant objects has to penetrate Earth's atmosphere. Although the sky may look clear, the gases that make up our atmosphere cause problems for astronomers. These gases absorb the majority of radiation emanating from celestial bodies so that it never reaches the astronomer's telescope. Radiation that does make it to the surface is distorted by pockets of warm and cool air, causing the twinkling effect. In spite of advanced computer enhancement, the images finally seen by astronomers are incomplete. NASA, in conjunction with other countries' space agencies, commercial companies, and the international community, has built observatories such as the Hubble Space Telescope, the Compton Gamma Ray Observatory, and the Chandra X-ray Observatory to find the answers to numerous questions about the universe. With the capabilities the Space Shuttle provides, scientist now have the means for deploying these observatories from the Shuttle's cargo bay directly into orbit.

  3. Low-mass neutron stars: universal relations, the nuclear symmetry energy and gravitational radiation

    NASA Astrophysics Data System (ADS)

    O. Silva, Hector; Berti, Emanuele; Sotani, Hajime

    2016-03-01

    Compact objects such as neutron stars are ideal astrophysical laboratories to test our understanding of the fundamental interactions in the regime of supranuclear densities, unachievable by terrestrial experiments. Despite recent progress, the description of matter (i.e., the equation of state) at such densities is still debatable. This translates into uncertainties in the bulk properties of neutron stars, masses and radii for instance. Here we will consider low-mass neutron stars. Such stars are expected to carry important information on nuclear matter near the nuclear saturation point. It has recently been shown that the masses and surface redshifts of low-mass neutron stars smoothly depend on simple functions of the central density and of a characteristic parameter η associated with the choice of equation of state. Here we extend these results to slowly-rotating and tidally deformed stars and obtain empirical relations for various quantities, such as the moment of inertia, quadrupole moment and ellipticity, tidal and rotational Love numbers, and rotational apsidal constants. We discuss how these relations might be used to constrain the equation of state by future observations in the electromagnetic and gravitational-wave spectra.

  4. Taosi Observatory

    NASA Astrophysics Data System (ADS)

    Sun, Xiaochun

    Taosi observatory is the remains of a structure discovered at the later Neolithic Taosi site located in Xiangfen County, Shanxi Province, in north-central China. The structure is a walled enclosure on a raised platform. Only rammed-earth foundations of the structure remained. Archaeoastronomical studies suggest that this structure functioned as an astronomical observatory. Historical circumstantial evidence suggests that it was probably related to the legendary kingdom of Yao from the twenty-first century BC.

  5. Space-Based Gravitational-Wave Observations as Tools for Testing General Relativity

    NASA Technical Reports Server (NTRS)

    Will, Clifford M.

    2004-01-01

    We continued a project, to analyse the ways in which detection and study of gravitational waves could provide quantitative tests of general relativity, with particular emphasis on waves that would be detectable by space-based observatories, such as LISA. This work had three foci: 1) Tests of scalar-tensor theories of gravity that, could be done by analyzing gravitational waves from neutron stars inspiralling into massive black holes, as detectable by LISA; 2) Study of alternative theories of gravity in which the graviton could be massive, and of how gravitational-wave observations by space-based detectors, solar-system tests, and cosmological observations could constrain such theories; and 3) Study of gravitational-radiation back reaction of particles orbiting black holes in general relativity, with emphasis on the effects of spin.

  6. Evidence for Orbital Decay of RX J1914.4+2456: Gravitational Radiation and the Nature of the X-Ray Emission

    NASA Technical Reports Server (NTRS)

    Strohmayer, Tod E.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    RX J1914.4+2456 is a candidate double-degenerate binary (AM CVn) with a putative 569 s orbital period. If this identification is correct, then it has one of the shortest binary orbital periods known, and gravitational radiation should drive the orbital evolution and mass transfer if the binary is semi-detached. Here we report the results of a coherent timing study of the archival ROSAT data for RX J1914.4+2456. We performed a phase coherent timing analysis using all five ROSAT observations spanning a four-year period. We demonstrate that all the data can be phase connected, and we show that the 1.756 mHz orbital frequency is increasing at a rate of 1.5 +/- 0.4 x 10(exp -17) Hz/s consistent with the expected loss of angular momentum from the binary system via gravitational radiation. In addition to providing evidence for the emission of gravitational waves, our measurement of the orbital v(dot) constrains models for the X-ray emission and the nature of the secondary. If stable mass accretion drives the X-ray flux, then a positive v(dot) is inconsistent with a degenerate donor. A helium burning dwarf is compatible if indeed such systems can have periods as short as that of RX J1914.4+2456, an open theoretical question. Our measurement of a positive v(dot) is consistent with the unipolar induction model of Wu et al. which does not require accretion to drive the X-ray flux. We discuss how future timing measurements of RX J1914.4+2456 (and systems like it) with for example, Chandra and XMM-Newton, can provide a unique probe of the interaction between mass loss and gravitational radiation. We also discuss the importance of such measurements in the context of gravitational wave detection from space, such as is expected in the future with the LISA mission.

  7. Study the Effects of Charged Particle Radiation on Gravitational Sensors in Space

    NASA Technical Reports Server (NTRS)

    Lipa, John A.

    1999-01-01

    Space-flight charging of free floating masses poses an unusual problem-- how can one control charge on the object without exerting a significant force on it? One approach is to make contact to the object with a fine wire. However, for many precision applications no physical contact is permissible, so charge must be conveyed in, a more sophisticated manner. One method has already been developed: Gravitational Probe B (GP-B) uses an ultraviolet photo-emission system described in ref 1. This system meets the experiment requirements, yet poses a number of constraints, including high power dissipation (approximately 10 W peak, approximately 1 W average), low current output (approximately 10(exp -13) A), and potential reliability problems associated with fiber optics system and the UV source. The aim of the current research is to improve this situation and, if possible, develop a more rugged and lower power alternative, usable in a wide range of situations. An potential alternative to the UV electron source is a Spindt-type field emission cathode. These consist of an array of extremely sharp silicon tips mounted in a standard IC package with provision for biasing them relative to the case potential. They are attractive as electron sources for space applications due to their low power consumption (10(exp -5) W), high current levels (10(exp -9) to 10(exp -5) A), and the absence of mechanical switching. Unfortunately, existing cathodes require special handling to avoid contamination and gas absorption. These contaminants can cause severe current fluctuations and eventual destruction of the cathode tips. Another potential drawback is the absence of any data indicating the possibility of bipolar current flow. This capability is needed because of the large uncertainties in the net charge transfer from cosmic rays to a free floating mass in space. More recent devices reduce the current fluctuations and destructive arcing by mounting the tips on a resistive substrate rather than

  8. Keele Observatory

    NASA Astrophysics Data System (ADS)

    Theodorus van Loon, Jacco; Albinson, James; Bagnall, Alan; Bryant, Lian; Caisley, Dave; Doody, Stephen; Johnson, Ian; Klimczak, Paul; Maddison, Ron; Robinson, StJohn; Stretch, Matthew; Webb, John

    2015-08-01

    Keele Observatory was founded by Dr. Ron Maddison in 1962, on the hill-top campus of Keele University in central England, hosting the 1876 Grubb 31cm refractor from Oxford Observatory. It since acquired a 61cm research reflector, a 15cm Halpha solar telescope and a range of other telescopes. Run by a group of volunteering engineers and students under directorship of a Keele astrophysicist, it is used for public outreach as well as research. About 4,000 people visit the observatory every year, including a large number of children. We present the facility, its history - including involvement in the 1919 Eddington solar eclipse expedition which proved Albert Einstein's theory of general relativity - and its ambitions to erect a radio telescope on its site.

  9. Precision X-ray Timing of RX J0806.3+1527 with CHANDRA: Evidence for Gravitational Radiation from an Ultracompact Binary

    NASA Technical Reports Server (NTRS)

    Strohmayer, Tod

    2005-01-01

    RX J0806.3+1527 is a candidate double degenerate binary with possibly the shortest known orbital period. The source shows an $\\approx 100 \\%$ X-ray intensity modulation at the putative orbital frequency of 3.11 mHz (321.5 s). If the system is a detached, ultracompact binary gravitational radiation should drive spin-up with a magnitude of $\\dot\

  10. The Japanese space gravitational wave antenna - DECIGO

    NASA Astrophysics Data System (ADS)

    Kawamura, S.; Ando, M.; Nakamura, T.; Tsubono, K.; Tanaka, T.; Funaki, I.; Seto, N.; Numata, K.; Sato, S.; Ioka, K.; Kanda, N.; Takashima, T.; Agatsuma, K.; Akutsu, T.; Akutsu, T.; Aoyanagi, Koh-Suke; Arai, K.; Arase, Y.; Araya, A.; Asada, H.; Aso, Y.; Chiba, T.; Ebisuzaki, T.; Enoki, M.; Eriguchi, Y.; Fujimoto, M.-K.; Fujita, R.; Fukushima, M.; Futamase, T.; Ganzu, K.; Harada, T.; Hashimoto, T.; Hayama, K.; Hikida, W.; Himemoto, Y.; Hirabayashi, H.; Hiramatsu, T.; Hong, F.-L.; Horisawa, H.; Hosokawa, M.; Ichiki, K.; Ikegami, T.; Inoue, K. T.; Ishidoshiro, K.; Ishihara, H.; Ishikawa, T.; Ishizaki, H.; Ito, H.; Itoh, Y.; Kamagasako, S.; Kawashima, N.; Kawazoe, F.; Kirihara, H.; Kishimoto, N.; Kiuchi, K.; Kobayashi, S.; Kohri, K.; Koizumi, H.; Kojima, Y.; Kokeyama, K.; Kokuyama, W.; Kotake, K.; Kozai, Y.; Kudoh, H.; Kunimori, H.; Kuninaka, H.; Kuroda, K.; Maeda, K.-i.; Matsuhara, H.; Mino, Y.; Miyakawa, O.; Miyoki, S.; Morimoto, M. Y.; Morioka, T.; Morisawa, T.; Moriwaki, S.; Mukohyama, S.; Musha, M.; Nagano, S.; Naito, I.; Nakagawa, N.; Nakamura, K.; Nakano, H.; Nakao, K.; Nakasuka, S.; Nakayama, Y.; Nishida, E.; Nishiyama, K.; Nishizawa, A.; Niwa, Y.; Ohashi, M.; Ohishi, N.; Ohkawa, M.; Okutomi, A.; Onozato, K.; Oohara, K.; Sago, N.; Saijo, M.; Sakagami, M.; Sakai, S.-i.; Sakata, S.; Sasaki, M.; Sato, T.; Shibata, M.; Shinkai, H.; Somiya, K.; Sotani, H.; Sugiyama, N.; Suwa, Y.; Tagoshi, H.; Takahashi, K.; Takahashi, K.; Takahashi, T.; Takahashi, H.; Takahashi, R.; Takahashi, R.; Takamori, A.; Takano, T.; Taniguchi, K.; Taruya, A.; Tashiro, H.; Tokuda, M.; Tokunari, M.; Toyoshima, M.; Tsujikawa, S.; Tsunesada, Y.; Ueda, K.-i.; Utashima, M.; Yamakawa, H.; Yamamoto, K.; Yamazaki, T.; Yokoyama, J.; Yoo, C.-M.; Yoshida, S.; Yoshino, T.

    2008-07-01

    DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) is the future Japanese space gravitational wave antenna. The goal of DECIGO is to detect gravitational waves from various kinds of sources mainly between 0.1 Hz and 10 Hz and thus to open a new window of observation for gravitational wave astronomy. DECIGO will consist of three drag-free spacecraft, 1000 km apart from each other, whose relative displacements are measured by a Fabry—Perot Michelson interferometer. We plan to launch DECIGO pathfinder first to demonstrate the technologies required to realize DECIGO and, if possible, to detect gravitational waves from our galaxy or nearby galaxies.

  11. Observation of Gravitational Waves from a Binary Black Hole Merger

    NASA Astrophysics Data System (ADS)

    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.; Arain, M. A.; 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.; Barton, M. A.; 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.; Birnholtz, O.; 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.; Cabero, M.; Cadonati, L.; Cagnoli, G.; Cahillane, C.; Bustillo, J. Calderón; Callister, T.; Calloni, E.; Camp, J. B.; Cannon, K. C.; Cao, J.; Capano, C. D.; Capocasa, E.; Carbognani, F.; Caride, S.; Diaz, J. Casanueva; Casentini, C.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C. B.; Baiardi, L. Cerboni; 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.; Creighton, T. D.; Cripe, J.; Crowder, S. G.; Cruise, A. M.; Cumming, A.; Cunningham, L.; Cuoco, E.; Canton, T. Dal; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Darman, N. S.; Da Silva Costa, C. F.; Dattilo, V.; Dave, I.; Daveloza, H. P.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; De, S.; 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.; Feldbaum, D.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Finn, L. S.; Fiori, I.; Fiorucci, D.; Fisher, R. P.; Flaminio, R.; Fletcher, M.; Fong, H.; Fournier, J.-D.; Franco, S.; Frasca, S.; Frasconi, F.; Frede, M.; 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, Abhirup; Ghosh, Archisman; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gill, K.; Glaefke, A.; Gleason, J. R.; Goetz, E.; Goetz, R.; Gondan, L.; González, G.; Castro, J. M. Gonzalez; 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.

    2016-02-01

    On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0 ×10-21. It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203 000 years, equivalent to a significance greater than 5.1 σ . The source lies at a luminosity distance of 41 0-180+160 Mpc corresponding to a redshift z =0.0 9-0.04+0.03 . In the source frame, the initial black hole masses are 3 6-4+5M⊙ and 2 9-4+4M⊙ , and the final black hole mass is 6 2-4+4M⊙ , with 3. 0-0.5+0.5M⊙ c2 radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.

  12. Observation of Gravitational Waves from a Binary Black Hole Merger.

    PubMed

    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; Arain, M A; 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; Barton, M A; 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; Birnholtz, O; 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; Cabero, M; 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; Creighton, T D; Cripe, J; Crowder, S G; Cruise, A M; Cumming, A; Cunningham, L; Cuoco, E; Dal Canton, T; Danilishin, S L; D'Antonio, S; Danzmann, K; Darman, N S; Da Silva Costa, C F; Dattilo, V; Dave, I; Daveloza, H P; Davier, M; Davies, G S; Daw, E J; Day, R; De, S; 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; Feldbaum, D; Ferrante, I; Ferreira, E C; Ferrini, F; Fidecaro, F; Finn, L S; Fiori, I; Fiorucci, D; Fisher, R P; Flaminio, R; Fletcher, M; Fong, H; Fournier, J-D; Franco, S; Frasca, S; Frasconi, F; Frede, M; 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, Abhirup; Ghosh, Archisman; Ghosh, S; Giaime, J A; Giardina, K D; Giazotto, A; Gill, K; Glaefke, A; Gleason, J R; 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; Greenhalgh, R J S; 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; Healy, J; Heefner, J; Heidmann, A; Heintze, M C; Heinzel, G; 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; Jacobson, M B; Jacqmin, T; Jang, H; Jani, K; Jaranowski, P; Jawahar, S; Jiménez-Forteza, F; Johnson, W W; Johnson-McDaniel, N K; 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; Keppel, D G; 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; Koranda, S; Korobko, M; Korth, W Z; Kowalska, I; Kozak, D B; Kringel, V; Krishnan, B; Królak, A; Krueger, C; Kuehn, G; Kumar, P; Kumar, R; Kuo, L; Kutynia, A; Kwee, P; 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; London, L T; Lord, J E; Lorenzini, M; Loriette, V; Lormand, M; Losurdo, G; Lough, J D; Lousto, C O; Lovelace, G; 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; Pan, Y; 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; Pfeiffer, H P; Phelps, M; Piccinni, O; Pichot, M; Pickenpack, M; Piergiovanni, F; Pierro, V; Pillant, G; Pinard, L; Pinto, I M; Pitkin, M; Poeld, J H; 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; Ramet, C R; 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; Sampson, L M; Sanchez, E J; Sandberg, V; Sandeen, B; Sanders, G H; 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; Shaffer, T; 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, M 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; Stevenson, S P; 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; Vallisneri, M; 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; Waldman, S J; Walker, M; Wallace, L; Walsh, S; Wang, G; Wang, H; Wang, M; Wang, X; Wang, Y; Ward, H; 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; Wiesner, K; Wilkinson, C; Willems, P A; Williams, L; Williams, R D; Williamson, A R; Willis, J L; Willke, B; Wimmer, M H; Winkelmann, L; Winkler, W; Wipf, C C; Wiseman, A G; Wittel, H; Woan, G; Worden, J; Wright, J L; Wu, G; Yablon, J; Yakushin, I; 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

    2016-02-12

    On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10(-21). It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203,000 years, equivalent to a significance greater than 5.1σ. The source lies at a luminosity distance of 410(-180)(+160)  Mpc corresponding to a redshift z=0.09(-0.04)(+0.03). In the source frame, the initial black hole masses are 36(-4)(+5)M⊙ and 29(-4)(+4)M⊙, and the final black hole mass is 62(-4)(+4)M⊙, with 3.0(-0.5)(+0.5)M⊙c(2) radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger. PMID:26918975

  13. Gravitational and radiative effects on the escape of helium from the moon

    NASA Technical Reports Server (NTRS)

    Hodges, R. R., Jr.

    1978-01-01

    On the moon, and probably on Mercury and other similar regolith-covered bodies with tenuous atmosphere, the dominant gas is He-4. It arises as the radiogenic product of the decay of uranium and thorium within any planet, but its major source appears to be the alpha particle flux of the solar wind. The moon intercepts solar wind helium at an average rate of 1.1 times 10 to the 24th atom/sec, and loses it at the same rate. Some helium may escape directly as the result of the process of solar wind soil bombardment which may release previously trapped helium at superthermal speeds. Atmospheric models have been calculated with the total helium influx as source. Subsequent comparison of model and measured helium concentrations indicates that the fraction of helium escaping via the atmosphere may range from 20% to 100% of the solar wind influx. Of the escaping atmosphere, most of the helium (about 93%) becomes trapped in earth orbit, while about 5% gets trapped in satellite orbits about the moon. Owing to a 6 month lifetime for helium in solar radiation, the satellite atoms form a lunar corona that exceeds the lunar atmosphere in total abundance by a factor of 4 to 5.

  14. Effect of neutral collision and radiative heat-loss function on self-gravitational instability of viscous thermally conducting partially-ionized plasma

    SciTech Connect

    Kaothekar, Sachin; Soni, Ghanshyam D.; Chhajlani, Rajendra K.

    2012-12-15

    The problem of thermal instability and gravitational instability is investigated for a partially ionized self-gravitating plasma which has connection in astrophysical condensations. We use normal mode analysis method in this problem. The general dispersion relation is derived using linearized perturbation equations of the problem. Effects of collisions with neutrals, radiative heat-loss function, viscosity, thermal conductivity and magnetic field strength, on the instability of the system are discussed. The conditions of instability are derived for a temperature-dependent and density-dependent heat-loss function with thermal conductivity. Numerical calculations have been performed to discuss the effect of various physical parameters on the growth rate of the gravitational instability. The temperature-dependent heat-loss function, thermal conductivity, viscosity, magnetic field and neutral collision have stabilizing effect, while density-dependent heat-loss function has a destabilizing effect on the growth rate of the gravitational instability. With the help of Routh-Hurwitz's criterion, the stability of the system is discussed.

  15. On the Contribution of Density Perturbations and Gravitational Waves to the Lower Order Multipoles of the Cosmic Microwave Background Radiation

    NASA Astrophysics Data System (ADS)

    Dimitropoulos, A.; Grishchuk, L. P.; Sathyaprakash, B. S.

    The important studies of Peebles, and Bond and Efstathiou have led to the formula Cl=const./[l(l+1)] aimed at describing the lower order multipoles of the CMBR temperature variations caused by density perturbations with the flat spectrum. Clearly, this formula requires amendments, as it predicts an infinitely large monopole C0, and a dipole moment C1 only 6/2 times larger than the quadrupole C2, both predictions in conflict with observations. We restore the terms omitted in the course of the derivation of this formula, and arrive at a new expression. According to the corrected formula, the monopole moment is finite and small, while the dipole moment is sensitive to short-wavelength perturbations, and numerically much larger than the quadrupole, as one would expect on physical grounds. At the same time, the function l(l+1)Cl deviates from a horizontal line and grows with l, for l>=2. We show that the inclusion of the modulating (transfer) function terminates the growth and forms the first peak, recently observed. We fit the theoretical curves to the position and height of the first peak, as well as to the observed dipole, varying three parameters: red-shift at decoupling, red-shift at matter-radiation equality, and slope of the primordial spectrum. It appears that there is always a deficit, as compared with the COBE observations, at small multipoles, l~10. We demonstrate that a reasonable and theoretically expected amount of gravitational waves bridges this gap at small multipoles, leaving the other fits as good as before. We show that the observationally acceptable models permit somewhat ``blue'' primordial spectra. This allows one to avoid the infrared divergence of cosmological perturbations, which is otherwise present.

  16. Grand Observatory

    NASA Technical Reports Server (NTRS)

    Young, Eric W.

    2002-01-01

    Various concepts have been recently presented for a 100 m class astronomical observatory. The science virtues of such an observatory are many: resolving planets orbiting around other stars, resolving the surface features of other stars, extending our temporal reach back toward the beginning (at and before stellar and galactic development), improving on the Next Generation Space Telescope, and other (perhaps as yet) undiscovered purposes. This observatory would be a general facility instrument with wide spectral range from at least the near ultraviolet to the mid infrared. The concept espoused here is based on a practical, modular design located in a place where temperatures remain (and instruments could operate) within several degrees of absolute zero with no shielding or cooling. This location is the bottom of a crater located near the north or south pole of the moon, most probably the South Polar Depression. In such a location the telescope would never see the sun or the earth, hence the profound cold and absence of stray light. The ideal nature of this location is elaborated herein. It is envisioned that this observatory would be assembled and maintained remotely through the use of expert robotic systems. A base station would be located above the crater rim with (at least occasional) direct line-of-sight access to the earth. Certainly it would be advantageous, but not absolutely essential, to have humans travel to the site to deal with unexpected contingencies. Further, observers and their teams could eventually travel there for extended observational campaigns. Educational activities, in general, could be furthered thru extended human presence. Even recreational visitors and long term habitation might follow.

  17. The Gravitational Universe - ESA's L3 mission

    NASA Astrophysics Data System (ADS)

    Mueller, Guido; Ando, Masaki; Binetruy, Pierre; Bouyer, Philippe; Cacciapuoti, Luigi; Cruise, Mike; Favata, Fabio; Gehler, Martin; Genzel, Reinhard; Jennrich, Oliver; Kasevich, Mark; Klipstein, Bill; Perryman, Michael; Safa, Frederic; Schutz, Bernard; Stebbins, Robin; Vitale, Stefano

    2015-04-01

    Following the advice of ESA's Senior Survey Committee (SSC) the Science Programme Committee (SPC) decided in November 2013 to select the science theme ``The Gravitational Universe'' for their L3 mission. The Director of Science and Robotic Exploration (D/SRE) has established a Gravitational Observatory Advisory Team (GOAT) to advise on the scientific and technological approaches for a gravitational wave observatory with a planned launch date in 2034. Our team is comprised of scientists from Europe and the US as well as scientists and engineers from ESA and observers from NASA and JAXA. We meet about every ten weeks, evaluate the technical readiness of all necessary technologies, study the science impact of different mission designs, and will advise ESA on the required future technology development. We will report on our progress and plans forward to a future space-based gravitational-wave observatory. For JAXA.

  18. Republication of: Contributions to the theory of pure gravitational radiation. Exact solutions of the field equations of the general theory of relativity II

    NASA Astrophysics Data System (ADS)

    Jordan, Pascual; Ehlers, Jürgen; Sachs, Rainer K.

    2013-12-01

    This is an English translation of a paper by Pascual Jordan, Juergen Ehlers and Rainer Sachs, first published in 1961 in the proceedings of the Academy of Sciences and Literature in Mainz (Germany). The original paper was part 2 of a five-part series of articles containing the first summary of knowledge about exact solutions of Einstein's equations found until then. (Parts 1 and 4 of the series have already been reprinted, parts 3 and 5 will be printed as Golden Oldies in near future.) This second paper discusses the geometry of geodesic null congruences, the algebraic classification of the Weyl tensor by spinor methods, and applies these to a study of the propagation of gravitational and electromagnetic radiation. It has been selected by the Editors of General Relativity and Gravitation for republication in the Golden Oldies series of the journal. The republication is accompanied by an editorial note written by Malcolm A. H. MacCallum and Wolfgang Kundt.

  19. OSO-6 Orbiting Solar Observatory

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The description, development history, test history, and orbital performance analysis of the OSO-6 Orbiting Solar Observatory are presented. The OSO-6 Orbiting Solar Observatory was the sixth flight model of a series of scientific spacecraft designed to provide a stable platform for experiments engaged in the collection of solar and celestial radiation data. The design objective was 180 days of orbital operation. The OSO-6 has telemetered an enormous amount of very useful experiment and housekeeping data to GSFC ground stations. Observatory operation during the two-year reporting period was very successful except for some experiment instrument problems.

  20. Ice Observatory

    NASA Astrophysics Data System (ADS)

    blugerman, n.

    2015-10-01

    My project is to make ice observatories to perceive astral movements as well as light phenomena in the shape of cosmic rays and heat, for example.I find the idea of creating an observation point in space, that in time will change shape and eventually disappear, in consonance with the way we humans have been approaching the exploration of the universe since we started doing it. The transformation in the elements we use to understand big and small transformations, within the universe elements.

  1. Virtual Observatories

    NASA Astrophysics Data System (ADS)

    Genova, Françoise

    2011-06-01

    Astronomy has been at the forefront among scientific disciplines for the sharing of data, and the advent of the World Wide Web has produced a revolution in the way astronomers do science. The recent development of the concept of Virtual Observatory builds on these foundations. This is one of the truly global endeavours of astronomy, aiming at providing astronomers with seamless access to data and tools, including theoretical data. Astronomy on-line resources provide a rare example of a world-wide, discipline-wide knowledge infrastructure, based on internationally agreed interoperability standards.

  2. A Coincident Search for Radio and Gravitational Waves from Binary Neutron Star Mergers

    NASA Astrophysics Data System (ADS)

    Cardena, Brett

    2011-05-01

    The merger of neutron star-neutron star binary pairs may be accompanied by the prompt emission of a coherent low-frequency radio pulse. This radio transient is produced as synchrotron radiation caused by the spin and rotation of the surface charge density of a pulsar through the magnetosphere of a larger neutron star, usually referred to as a Magnetar . This type of merger event would also result in the release of a gravitational coalescence wave-form. We will discuss a coincident radio transient and gravitational wave search. This search is being conducted by two radio telescope arrays: The Long Wave Array (LWA) and the Eight-meter-wavelength Transient Array (ETA) in coordination with the Laser Interferometer Gravitational-Wave Observatory (LIGO). We will outline this ongoing coincident search and discuss some preliminary results.

  3. Detectable gravitational waves from very strong phase transitions in the general NMSSM

    NASA Astrophysics Data System (ADS)

    Huber, Stephan J.; Konstandin, Thomas; Nardini, Germano; Rues, Ingo

    2016-03-01

    We study the general NMSSM with an emphasis on the parameter regions with a very strong first-order electroweak phase transition (EWPT). In the presence of heavy fields coupled to the Higgs sector, the analysis can be problematic due to the existence of sizable radiative corrections. In this paper we propose a subtraction scheme that helps to circumvent this problem. For simplicity we focus on a parameter region that is by construction hidden from the current collider searches. The analysis proves that (at least) in the identified parameter region the EWPT can be very strong and striking gravitational wave signals can be produced. The corresponding gravitational stochastic background can potentially be detected at the planned space-based gravitational wave observatory eLISA, depending on the specific experiment design that will be approved.

  4. Periodic gravitational waves from small cosmic string loops

    NASA Astrophysics Data System (ADS)

    Dubath, Florian; Rocha, Jorge V.

    2007-07-01

    We consider a population of small, high-velocity cosmic string loops. We assume the typical length of these loops is determined by the gravitational radiation scale and use the results of Polchinski and Rocha which pointed out their highly relativistic nature. A study of the gravitational wave emission from such a population is carried out. The large Lorentz boost involved causes the lowest harmonics of the loops to fall within the frequency band of the Laser Interferometer Gravitational Wave Observatory detector. Because of this feature the gravitational waves emitted by such loops can be detected in a periodic search rather than in burst or stochastic analysis. It is shown that, for interesting values of the string tension (10-10≲Gμ≲10-8), the detector can observe loops at reasonably high redshifts and that detection is, in principle, possible. We compute the number of expected observations produced by such a process. For a 10 h search we find that this number is of order O(10-4). This is a consequence of the low effective number density of the loops traveling along the line of sight. However, small probabilities of reconnection and longer observation times can improve the result.

  5. NANOGrav Constraints on Gravitational Wave Bursts with Memory

    NASA Astrophysics Data System (ADS)

    Arzoumanian, Z.; Brazier, A.; Burke-Spolaor, S.; Chamberlin, S. J.; Chatterjee, S.; Christy, B.; Cordes, J. M.; Cornish, N. J.; Demorest, P. B.; Deng, X.; Dolch, T.; Ellis, J. A.; Ferdman, R. D.; Fonseca, E.; Garver-Daniels, N.; Jenet, F.; Jones, G.; Kaspi, V. M.; Koop, M.; Lam, M. T.; Lazio, T. J. W.; Levin, L.; Lommen, A. N.; Lorimer, D. R.; Luo, J.; Lynch, R. S.; Madison, D. R.; McLaughlin, M. A.; McWilliams, S. T.; Nice, D. J.; Palliyaguru, N.; Pennucci, T. T.; Ransom, S. M.; Siemens, X.; Stairs, I. H.; Stinebring, D. R.; Stovall, K.; Swiggum, J.; Vallisneri, M.; van Haasteren, R.; Wang, Y.; Zhu, W. W.; NANOGrav Collaboration

    2015-09-01

    Among efforts to detect gravitational radiation, pulsar timing arrays are uniquely poised to detect “memory” signatures, permanent perturbations in spacetime from highly energetic astrophysical events such as mergers of supermassive black hole binaries. The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) observes dozens of the most stable millisecond pulsars using the Arecibo and Green Bank radio telescopes in an effort to study, among other things, gravitational wave memory. We herein present the results of a search for gravitational wave bursts with memory (BWMs) using the first five years of NANOGrav observations. We develop original methods for dramatically speeding up searches for BWM signals. In the directions of the sky where our sensitivity to BWMs is best, we would detect mergers of binaries with reduced masses of {10}9 {M}⊙ out to distances of 30 Mpc; such massive mergers in the Virgo cluster would be marginally detectable. We find no evidence for BWMs. However, with our non-detection, we set upper limits on the rate at which BWMs of various amplitudes could have occurred during the time spanned by our data—e.g., BWMs with amplitudes greater than 10-13 must encounter the Earth at a rate less than 1.5 yr-1.

  6. Sunphotometry of the 2006-2007 aerosol optical/radiative properties at the Himalayan Nepal Climate Observatory-Pyramid (5079 m a.s.l.)

    NASA Astrophysics Data System (ADS)

    Gobbi, G. P.; Angelini, F.; Bonasoni, P.; Verza, G. P.; Marinoni, A.; Barnaba, F.

    2010-11-01

    In spite of being located at the heart of the highest mountain range in the world, the Himalayan Nepal Climate Observatory (5079 m a.s.l.) at the Ev-K2-CNR Pyramid is shown to be affected by the advection of pollution aerosols from the populated regions of southern Nepal and the Indo-Gangetic plains. Such an impact is observed along most of the period April 2006-March 2007 addressed here, with a minimum in the monsoon season. Backtrajectory-analysis indicates long-range transport episodes occurring in this year to originate mainly in the west Asian deserts. At this high altitude site, the measured aerosol optical depth is observed to be about one order of magnitude lower than the one measured at Ghandi College (60 m a.s.l.), in the Indo-Gangetic basin. As for Ghandi College, and in agreement with the in situ ground observations at the Pyramid, the fine mode aerosol optical depth maximizes during winter and minimizes in the monsoon season. Conversely, total optical depth maximizes during the monsoon due to the occurrence of elevated, coarse particle layers. Possible origins of these particles are wind erosion from the surrounding peaks and hydrated/cloud-processed aerosols. Assessment of the aerosol radiative forcing is then expected to be hampered by the presence of these high altitude particle layers, which impede an effective, continuous measurement of anthropogenic aerosol radiative properties from sky radiance inversions and/or ground measurements alone. Even though the retrieved absorption coefficients of pollution aerosols were rather large (single scattering albedo of the order of 0.6-0.9 were observed in the month of April 2006), the corresponding low optical depths (~0.03 at 500 nm) are expected to limit the relevant radiative forcing. Still, the high specific forcing of this aerosol and its capability of altering snow surface albedo provide good reasons for continuous monitoring.

  7. Sunphotometry of the 2006-2007 aerosol optical/radiative properties at the Himalayan Nepal Climate Observatory - Pyramid (5079 m a.s.l.)

    NASA Astrophysics Data System (ADS)

    Gobbi, G. P.; Angelini, F.; Bonasoni, P.; Verza, G. P.; Marinoni, A.; Barnaba, F.

    2010-01-01

    In spite of being located at the heart of the highest mountain range in the world, the Himalayan Nepal Climate Observatory (5079 m a.s.l.) at the Ev-K2-CNR Pyramid is shown to be affected by the advection of pollution aerosols from the populated regions of southern Nepal and the Indo-Gangetic plains. Such an impact is observed along most of the period April 2006-March 2007 addressed here, with a minimum in the monsoon season. Backtrajectory-analysis indicates long-range transport episodes occurring in this period to originate mainly in the West Asian deserts. At this high altitude site, the measured aerosol optical depth is observed to be: 1) about one order of magnitude lower than the one measured at Gandhi College (60 m a.s.l.), in the Indo-Gangetic basin, and 2) maximum during the monsoon period, due to the presence of elevated (cirrus-like) particle layers. Assessment of the aerosol radiative forcing results to be hampered by the persistent presence of these high altitude particle layers, which impede a continuous measurement of both the aerosol optical depth and its radiative properties from sky radiance inversions. Even though the retrieved absorption coefficients of pollution aerosols was rather large (single scattering albedo of the order of 0.6-0.9 were observed in the month of April 2006), the corresponding low optical depths (~0.03 at 500 nm) are expected to limit the relevant radiative forcings. Still, the high specific forcing of this aerosol and its capability of altering snow surface albedo provide good reason for continuous monitoring.

  8. Lunar astronomical observatories - Design studies

    NASA Technical Reports Server (NTRS)

    Johnson, Stewart W.; Burns, Jack O.; Chua, Koon Meng; Duric, Nebojsa; Gerstle, Walter H.

    1990-01-01

    The best location in the inner solar system for the grand observatories of the 21st century may be the moon. A multidisciplinary team including university students and faculty in engineering, astronomy, physics, and geology, and engineers from industry is investigating the moon as a site for astronomical observatories and is doing conceptual and preliminary designs for these future observatories. Studies encompass lunar facilities for radio astronomy and astronomy at optical, ultraviolet, and infrared wavelengths of the electromagnetic spectrum. Although there are significant engineering challenges in design and construction on the moon, the rewards for astronomy can be great, such as detection and study of earth-like planets orbiting nearby stars, and the task for engineers promises to stimulate advances in analysis and design, materials and structures, automation and robotics, foundations, and controls. Fabricating structures in the reduced-gravity environment of the moon will be easier than in the zero-gravity environment of earth orbit, as Apollo and space-shuttle missions have revealed. Construction of observatories on the moon can be adapted from techniques developed on the earth, with the advantage that the moon's weaker gravitational pull makes it possible to build larger devices than are practical on earth.

  9. Gravitational waves from the cosmological QCD transition

    NASA Astrophysics Data System (ADS)

    Mourão Roque, V. R. C.; Roque, G. Lugones o.; Lugones, G.

    2014-09-01

    We determine the minimum fluctuations in the cosmological QCD phase transition that could be detectable by the eLISA/NGO gravitational wave observatory. To this end, we performed several hydrodynamical simulations using a state-of-the-art equation of state derived from lattice QCD simulations. Based on the fact that the viscosity per entropy density of the quark gluon plasma obtained from heavy-ion collision experiments at the RHIC and the LHC is extremely small, we considered a non-viscous fluid in our simulations. Several previous works about this transition considered a first order transition that generates turbulence which follows a Kolmogorov power law. We show that for the QCD crossover transition the turbulent spectrum must be very different because there is no viscosity and no source of continuous energy injection. As a consequence, a large amount of kinetic energy accumulates at the smallest scales. From the hydrodynamic simulations, we have obtained the spectrum of the gravitational radiation emitted by the motion of the fluid, finding that, if typical velocity and temperature fluctuations have an amplitude Δ v /c ≳ 10-2 and/or Δ T/T_c ≳ 10-3, they would be detected by eLISA/NGO at frequencies larger than ˜ 10-4 Hz.

  10. Near-infrared radiation background, gravitational wave background, and star formation rate of Pop III and Pop II during cosmic reionization

    NASA Astrophysics Data System (ADS)

    Yang, Y. P.; Wang, F. Y.; Dai, Z. G.

    2015-10-01

    Context. The transition from Population III (Pop III) to Population II (Pop II) stars plays an important role in the history of the Universe. The huge amount of ionizing photons generated by Pop III stars begin to ionize the intergalactic medium (IGM) at the early stage of reionization. Meanwhile, the feedback from reionization and metal enrichment changes the evolution of different populations. The near-infrared radiation background (NIRB) and the stochastic background of gravitational waves (SBGWs) from these early stars will provide important information about the transition form Pop III to Pop II stars. Aims: We obtain the NIRB and SBGWs from the early stars, which are constrained by the observation of reionization and star formation rate (SFR). Methods: We studied the transition from Pop III to Pop II stars via the star formation model of different populations, which takes into account the reionization and the metal enrichment evolution. We calculated the two main metal pollution channels arising from the supernova-driven protogalactic outflows and genetic channel. We obtained the SFRs of Pop III and Pop II and their NIRB and SBGWs radiation. Results: We predict that the upper limit of metallicity in metal-enriched IGM (the galaxies that are polluted via the genetic channel) reaches Zcrit = 10-3.5 Z⊙ at z ~ 13 (z ~ 11), which is consistent with our star formation model. We constrain the SFR of Pop III stars from reionization observations. The peak intensity of NIRB is about 0.03 - 0.2 nWm-2 sr-1 at ~1 μm for z> 6. The predicted NIRB signal is consistent with the metallicity evolution. We also obtain the gravitational wave background from the black holes formed by these early stars. The predicted gravitational wave background has a peak amplitude of ΩGW ≃ 8 × 10-9 at ν = 158 Hz for Pop II star remnants. However, the background generated by Pop III.2 stars is much lower than that of Pop II stars, with a peak amplitude of ΩGW ≃ 1.2 × 10-11 at ν = 28

  11. Scalar Gravitational Waves

    NASA Astrophysics Data System (ADS)

    Mottola, Emil

    2016-03-01

    General Relativity receives quantum corrections relevant at macroscopic distance scales and near event horizons. These arise from the conformal scalar degree of freedom in the extended effective field theory (EFT) of gravity generated by the trace anomaly of massless quantum fields in curved space. Linearized around flat space this quantum scalar degree of freedom combines with the conformal part of the metric and predicts the existence of scalar spin-0 ``breather'' propagating gravitational waves in addition to the transverse tensor spin-2 waves of classical General Relativity. Estimates of the expected strength of scalar gravitational radiation from compact astrophysical sources are given.

  12. 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.

  13. NEW Fe IX LINE IDENTIFICATIONS USING SOLAR AND HELIOSPHERIC OBSERVATORY/SOLAR ULTRAVIOLET MEASUREMENT OF EMITTED RADIATION AND HINODE/EIS JOINT OBSERVATIONS OF THE QUIET SUN

    SciTech Connect

    Landi, E.; Young, P. R.

    2009-12-20

    In this work, we study joint observations of Hinode/EUV Imaging Spectrometer (EIS) and Solar and Heliospheric Observatory/Solar Ultraviolet Measurement of Emitted Radiation of Fe IX lines emitted by the same level of the high energy configuration 3s {sup 2}3p {sup 5}4p. The intensity ratios of these lines are dependent on atomic physics parameters only and not on the physical parameters of the emitting plasma, so that they are excellent tools to verify the relative intensity calibration of high-resolution spectrometers that work in the 170-200 A and 700-850 A wavelength ranges. We carry out extensive atomic physics calculations to improve the accuracy of the predicted intensity ratio, and compare the results with simultaneous EIS-SUMER observations of an off-disk quiet Sun region. We were able to identify two ultraviolet lines in the SUMER spectrum that are emitted by the same level that emits one bright line in the EIS wavelength range. Comparison between predicted and measured intensity ratios, wavelengths and energy separation of Fe IX levels confirms the identifications we make. Blending and calibration uncertainties are discussed. The results of this work are important for cross-calibrating EIS and SUMER, as well as future instrumentation.

  14. Probing the size of extra dimensions with gravitational wave astronomy

    SciTech Connect

    Yagi, Kent; Tanahashi, Norihiro; Tanaka, Takahiro

    2011-04-15

    In the Randall-Sundrum II braneworld model, it has been conjectured, according to the AdS/CFT correspondence, that a brane-localized black hole (BH) larger than the bulk AdS curvature scale l cannot be static, and it is dual to a four-dimensional BH emitting Hawking radiation through some quantum fields. In this scenario, the number of the quantum field species is so large that this radiation changes the orbital evolution of a BH binary. We derived the correction to the gravitational waveform phase due to this effect and estimated the upper bounds on l by performing Fisher analyses. We found that the Deci-Hertz Interferometer Gravitational Wave Observatory and the Big Bang Observatory (DECIGO/BBO) can give a stronger constraint than the current tabletop result by detecting gravitational waves from small mass BH/BH and BH/neutron star (NS) binaries. Furthermore, DECIGO/BBO is expected to detect 10{sup 5} BH/NS binaries per year. Taking this advantage, we find that DECIGO/BBO can actually measure l down to l=0.33 {mu}m for a 5 yr observation if we know that binaries are circular a priori. This is about 40 times smaller than the upper bound obtained from the tabletop experiment. On the other hand, when we take eccentricities into binary parameters, the detection limit weakens to l=1.5 {mu}m due to strong degeneracies between l and eccentricities. We also derived the upper bound on l from the expected detection number of extreme mass ratio inspirals with LISA and BH/NS binaries with DECIGO/BBO, extending the discussion made recently by McWilliams [Phys. Rev. Lett. 104, 141601 (2010)]. We found that these less robust constraints are weaker than the ones from phase differences.

  15. Gravitational wave detection in the laboratory.

    NASA Astrophysics Data System (ADS)

    Chen, Y. T.; Kawashima, N.; Othman, M.; Chia, S. P.; Karim, M.; Sanugi, B.; Lim, B. H.; Chong, K. K.

    1998-09-01

    After reviewing the research work of gravitational wave detection in the laboratory, particularly long base laser interferometer detectors, the authors report on the recent progress of gravitational wave detection using laser interferometer (Tianyin-100) in Malaysia. The authors also outline the brief plan for Tianyin-500 in the future as a full-scale observatory competitive to other projects such as Ligo, Geo600, etc.

  16. Sources of gravitational waves

    NASA Technical Reports Server (NTRS)

    Schutz, Bernard F.

    1989-01-01

    Sources of low frequency gravitational radiation are reviewed from an astrophysical point of view. Cosmological sources include the formation of massive black holes in galactic nuclei, the capture by such holes of neutron stars, the coalescence of orbiting pairs of giant black holes, and various means of producing a stochastic background of gravitational waves in the early universe. Sources local to our Galaxy include various kinds of close binaries and coalescing binaries. Gravitational wave astronomy can provide information that no other form of observing can supply; in particular, the positive identification of a cosmological background originating in the early universe would be an event as significant as was the detection of the cosmic microwave background.

  17. 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.

  18. Republication of: Contributions to the theory of gravitational radiation fields. Exact solutions of the field equations of the general theory of relativity V

    NASA Astrophysics Data System (ADS)

    Kundt, Wolfgang; Trümper, Manfred

    2016-04-01

    This is an English translation of a paper by Wolfgang Kundt and Manfred Trümper, first published in 1962 in the proceedings of the Academy of Sciences and Literature in Mainz (Germany). The original paper was the last of a five-part series of articles containing the first summary of knowledge about exact solutions of Einstein's equations found until then. (All the other parts of the series have already been re-published as Golden Oldies.) This fifth contribution summarizes key points of the earlier papers and applies them, in particular results from papers II and IV in the series, in the context of the propagation of gravitational radiation when matter is present. The paper has been selected by the Editors of General Relativity and Gravitation for re-publication in the Golden Oldies series of the journal. This republication is accompanied by an editorial note written by Malcolm A.H. MacCallum and by a brief autobiography of Manfred Trümper.

  19. Gravitational Wave Astronomy

    NASA Astrophysics Data System (ADS)

    Finn, Lee Samuel

    2012-03-01

    If two black holes collide in a vacuum, can they be observed? Until recently, the answer would have to be "no." After all, how would we observe them? Black holes are "naked" mass: pure mass, simple mass, mass devoid of any matter whose interactions might lead to the emission of photons or neutrinos, or any electromagnetic fields that might accelerate cosmic rays or leave some other signature that we could observe in our most sensitive astronomical instruments. Still, black holes do have mass. As such, they interact—like all mass—gravitationally. And the influence of gravity, like all influences, propagates no faster than that universal speed we first came to know as the speed of light. The effort to detect that propagating influence, which we term as gravitational radiation or gravitational waves, was initiated just over 50 years ago with the pioneering work of Joe Weber [1] and has been the object of increasingly intense experimental effort ever since. Have we, as yet, detected gravitational waves? The answer is still "no." Nevertheless, the accumulation of the experimental efforts begun fifty years ago has brought us to the point where we can confidently say that gravitational waves will soon be detected and, with that first detection, the era of gravitational wave astronomy—the observational use of gravitational waves, emitted by heavenly bodies—will begin. Data analysis for gravitational wave astronomy is, today, in its infancy and its practitioners have much to learn from allied fields, including machine learning. Machine learning tools and techniques have not yet been applied in any extensive or substantial way to the study or analysis of gravitational wave data. It is fair to say that this owes principally to the fields relative youth and not to any intrinsic unsuitability of machine learning tools to the analysis problems the field faces. Indeed, the nature of many of the analysis problems faced by the field today cry-out for the application of

  20. The challenge of detecting gravitational radiation is creating a new chapter in quantum electronics: Quantum nondemolition measurements

    NASA Technical Reports Server (NTRS)

    Braginsky, V. B.; Vorontsov, Y. I.; Thorne, K. S.

    1979-01-01

    Future gravitational wave antennas will be approximately 100 kilogram cylinders, whose end-to-end vibrations must be measured so accurately (10 to the -19th power centimeters) that they behave quantum mechanically. Moreover, the vibration amplitude must be measured over and over again without perturbing it (quantum nondemolition measurement). This contrasts with quantum chemistry, quantum optics, or atomic, nuclear, and elementary particle physics where measurements are usually made on an ensemble of identical objects, and care is not given to whether any single object is perturbed or destroyed by the measurement. Electronic techniques required for quantum nondemolition measurements are described as well as the theory underlying them.

  1. Coalescing binary systems of compact objects to (post) sup 5/2 -Newtonian order: Late-time evolution and gravitational radiation emission

    SciTech Connect

    Lincoln, C.W.

    1990-01-01

    The late-time evolution of binary systems of compact objects (neutron stars or black holes) is studied using the Damour-Derueele (post){sup 5/2}-Newtonian equations of motion with relativistic corrections of all orders up to and including radiation reaction. Using the method of close orbital elements from celestial mechanics, the author evolves the orbits to separations of r {approx} 2 m, where m is the total mass, at which point the (post){sup 5/2}-Newtonian approximation breaks down. With the orbits as input, he calculates the gravitational waveform and luminosity using a post-Newtonian formalism of Wagoner and Will. Results are obtained for systems containing various combinations of compact objects, for various values of the mass ratio m{sub 1}/m{sub 2}, and forg various initial values of the orbital eccentricity.

  2. Gravitational Wave Astrophysics: Opening the New Frontier

    NASA Technical Reports Server (NTRS)

    Centrella, Joan

    2011-01-01

    The gravitational wave window onto the universe is expected to open in 5 years, when ground-based detectors make the first detections in the high-frequency regime. Gravitational waves are ripples in spacetime produced by the motions of massive objects such as black holes and neutron stars. Since the universe is nearly transparent to gravitational waves, these signals carry direct information about their sources such as masses, spins, luminosity distances, and orbital parameters through dense, obscured regions across cosmic time. This article explores gravitational waves as cosmic messengers, highlighting key sources, detection methods, and the astrophysical payoffs across the gravitational wave spectrum. Keywords: Gravitational wave astrophysics; gravitational radiation; gravitational wave detectors; black holes.

  3. Theory and detection of gravitational waves

    NASA Astrophysics Data System (ADS)

    Pizzella, G.

    The role of gravitational waves in general relativity is examined. It is found that the gravitational waves are a particular solution of the Einstein equations. The computation of the energy flux emitted by moving bodies as gravitational waves is very similar to that for electromagnetic waves. A description of gravitational wave sources is presented, taking into account a spinning star, double star systems, the fall into a Schwarzschild black hole, and radiation from gravitational collapse. Questions regarding the interaction of gravitational waves with matter are explored, and the interaction of a gravitational wave with oscillators and an elastic cylinder is considered. Electromechanical transducers are discussed, giving attention to the piezoelectric ceramic, the capacitor, the inductor, the Brownian noise of the bar, the backreaction, the wide band noise, and data analysis. The design of a gravitational wave antenna is also described.

  4. The Japanese space gravitational wave antenna; DECIGO

    NASA Astrophysics Data System (ADS)

    Kawamura, S.; Ando, M.; Nakamura, T.; Tsubono, K.; Tanaka, T.; Funaki, I.; Seto, N.; Numata, K.; Sato, S.; Ioka, K.; Kanda, N.; Takashima, T.; Agatsuma, K.; Akutsu, T.; Akutsu, T.; Aoyanagi, K.-s.; Arai, K.; Arase, Y.; Araya, A.; Asada, H.; Aso, Y.; Chiba, T.; Ebisuzaki, T.; Enoki, M.; Eriguchi, Y.; Fujimoto, M.-K.; Fujita, R.; Fukushima, M.; Futamase, T.; Ganzu, K.; Harada, T.; Hashimoto, T.; Hayama, K.; Hikida, W.; Himemoto, Y.; Hirabayashi, H.; Hiramatsu, T.; Hong, F.-L.; Horisawa, H.; Hosokawa, M.; Ichiki, K.; Ikegami, T.; Inoue, K. T.; Ishidoshiro, K.; Ishihara, H.; Ishikawa, T.; Ishizaki, H.; Ito, H.; Itoh, Y.; Kamagasako, S.; Kawashima, N.; Kawazoe, F.; Kirihara, H.; Kishimoto, N.; Kiuchi, K.; Kobayashi, S.; Kohri, K.; Koizumi, H.; Kojima, Y.; Kokeyama, K.; Kokuyama, W.; Kotake, K.; Kozai, Y.; Kudoh, H.; Kunimori, H.; Kuninaka, H.; Kuroda, K.; Maeda, K.-i.; Matsuhara, H.; Mino, Y.; Miyakawa, O.; Miyoki, S.; Morimoto, M. Y.; Morioka, T.; Morisawa, T.; Moriwaki, S.; Mukohyama, S.; Musha, M.; Nagano, S.; Naito, I.; Nakagawa, N.; Nakamura, K.; Nakano, H.; Nakao, K.; Nakasuka, S.; Nakayama, Y.; Nishida, E.; Nishiyama, K.; Nishizawa, A.; Niwa, Y.; Ohashi, M.; Ohishi, N.; Ohkawa, M.; Okutomi, A.; Onozato, K.; Oohara, K.; Sago, N.; Saijo, M.; Sakagami, M.; Sakai, S.-i.; Sakata, S.; Sasaki, M.; Sato, T.; Shibata, M.; Shinkai, H.; Somiya, K.; Sotani, H.; Sugiyama, N.; Suwa, Y.; Tagoshi, H.; Takahashi, K.; Takahashi, K.; Takahashi, T.; Takahashi, H.; Takahashi, R.; Takahashi, R.; Takamori, A.; Takano, T.; Taniguchi, K.; Taruya, A.; Tashiro, H.; Tokuda, M.; Tokunari, M.; Toyoshima, M.; Tsujikawa, S.; Tsunesada, Y.; Ueda, K.-i.; Utashima, M.; Yamakawa, H.; Yamamoto, K.; Yamazaki, T.; Yokoyama, J.; Yoo, C.-M.; Yoshida, S.; Yoshino, T.

    2008-07-01

    DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) is the future Japanese space gravitational wave antenna. DECIGO is expected to open a new window of observation for gravitational wave astronomy especially between 0.1 Hz and 10 Hz, revealing various mysteries of the universe such as dark energy, formation mechanism of supermassive black holes, and inflation of the universe. The pre-conceptual design of DECIGO consists of three drag-free spacecraft, whose relative displacements are measured by a differential Fabry-Perot Michelson interferometer. We plan to launch two missions, DECIGO pathfinder and pre-DECIGO first and finally DECIGO in 2024.

  5. A New Multi-energy Neutrino Radiation-Hydrodynamics Code in Full General Relativity and Its Application to the Gravitational Collapse of Massive Stars

    NASA Astrophysics Data System (ADS)

    Kuroda, Takami; Takiwaki, Tomoya; Kotake, Kei

    2016-02-01

    We present a new multi-dimensional radiation-hydrodynamics code for massive stellar core-collapse in full general relativity (GR). Employing an M1 analytical closure scheme, we solve spectral neutrino transport of the radiation energy and momentum based on a truncated moment formalism. Regarding neutrino opacities, we take into account a baseline set in state-of-the-art simulations, in which inelastic neutrino-electron scattering, thermal neutrino production via pair annihilation, and nucleon-nucleon bremsstrahlung are included. While the Einstein field equations and the spatial advection terms in the radiation-hydrodynamics equations are evolved explicitly, the source terms due to neutrino-matter interactions and energy shift in the radiation moment equations are integrated implicitly by an iteration method. To verify our code, we first perform a series of standard radiation tests with analytical solutions that include the check of gravitational redshift and Doppler shift. A good agreement in these tests supports the reliability of the GR multi-energy neutrino transport scheme. We then conduct several test simulations of core-collapse, bounce, and shock stall of a 15{M}⊙ star in the Cartesian coordinates and make a detailed comparison with published results. Our code performs quite well to reproduce the results of full Boltzmann neutrino transport especially before bounce. In the postbounce phase, our code basically performs well, however, there are several differences that are most likely to come from the insufficient spatial resolution in our current 3D-GR models. For clarifying the resolution dependence and extending the code comparison in the late postbounce phase, we discuss that next-generation Exaflops class supercomputers are needed at least.

  6. Gravitational Waves from Neutron Stars: A Review

    NASA Astrophysics Data System (ADS)

    Lasky, Paul D.

    2015-09-01

    Neutron stars are excellent emitters of gravitational waves. Squeezing matter beyond nuclear densities invites exotic physical processes, many of which violently transfer large amounts of mass at relativistic velocities, disrupting spacetime and generating copious quantities of gravitational radiation. I review mechanisms for generating gravitational waves with neutron stars. This includes gravitational waves from radio and millisecond pulsars, magnetars, accreting systems, and newly born neutron stars, with mechanisms including magnetic and thermoelastic deformations, various stellar oscillation modes, and core superfluid turbulence. I also focus on what physics can be learnt from a gravitational wave detection, and where additional research is required to fully understand the dominant physical processes at play.

  7. Comparing numerical and analytic approximate gravitational waveforms

    NASA Astrophysics Data System (ADS)

    Afshari, Nousha; Lovelace, Geoffrey; SXS Collaboration

    2016-03-01

    A direct observation of gravitational waves will test Einstein's theory of general relativity under the most extreme conditions. The Laser Interferometer Gravitational-Wave Observatory, or LIGO, began searching for gravitational waves in September 2015 with three times the sensitivity of initial LIGO. To help Advanced LIGO detect as many gravitational waves as possible, a major research effort is underway to accurately predict the expected waves. In this poster, I will explore how the gravitational waveform produced by a long binary-black-hole inspiral, merger, and ringdown is affected by how fast the larger black hole spins. In particular, I will present results from simulations of merging black holes, completed using the Spectral Einstein Code (black-holes.org/SpEC.html), including some new, long simulations designed to mimic black hole-neutron star mergers. I will present comparisons of the numerical waveforms with analytic approximations.

  8. Demagnified gravitational waves from cosmological double neutron stars and gravitational wave foreground cleaning around 1 Hz

    SciTech Connect

    Seto, Naoki

    2009-11-15

    Gravitational waves (GWs) from cosmological double neutron star binaries (NS+NS) can be significantly demagnified by the strong gravitational lensing effect, and the proposed future missions such as the Big Bang Observer or Deci-hertz Interferometer Gravitational Wave Observatory might miss some of the demagnified GW signals below a detection threshold. The undetectable binaries would form a GW foreground, which might hamper detection of a very weak primordial GW signal. We discuss the outlook of this potential problem, using a simple model based on the singular isothermal sphere lens profile. Fortunately, it is expected that, for a presumable merger rate of NS+NSs, the residual foreground would be below the detection limit {omega}{sub GW,lim}{approx}10{sup -16} realized with the Big Bang Observer/Deci-hertz Interferometer Gravitational Wave Observatory by correlation analysis.

  9. FIRST INVESTIGATION OF THE COMBINED IMPACT OF IONIZING RADIATION AND MOMENTUM WINDS FROM A MASSIVE STAR ON A SELF-GRAVITATING CORE

    SciTech Connect

    Ngoumou, Judith; Hubber, David; Dale, James E.; Burkert, Andreas

    2015-01-01

    Massive stars shape the surrounding interstellar matter (ISM) by emitting ionizing photons and ejecting material through stellar winds. To study the impact of the momentum from the wind of a massive star on the surrounding neutral or ionized material, we implemented a new HEALPix-based momentum-conserving wind scheme in the smoothed particle hydrodynamics (SPH) code SEREN. A qualitative study of the impact of the feedback from an O7.5-like star on a self-gravitating sphere shows that on its own, the transfer of momentum from a wind onto cold surrounding gas has both a compressing and dispersing effect. It mostly affects gas at low and intermediate densities. When combined with a stellar source's ionizing ultraviolet (UV) radiation, we find the momentum-driven wind to have little direct effect on the gas. We conclude that during a massive star's main sequence, the UV ionizing radiation is the main feedback mechanism shaping and compressing the cold gas. Overall, the wind's effects on the dense gas dynamics and on the triggering of star formation are very modest. The structures formed in the ionization-only simulation and in the combined feedback simulation are remarkably similar. However, in the combined feedback case, different SPH particles end up being compressed. This indicates that the microphysics of gas mixing differ between the two feedback simulations and that the winds can contribute to the localized redistribution and reshuffling of gas.

  10. New Perspectives on Gravitation

    NASA Astrophysics Data System (ADS)

    Zhang, Yikun

    2003-04-01

    Based on radiation mechanics, a new rational mechanics proposed by the author, we can prove Newton's gravitational law and its conditions of validity. The gravitational coefficient is not a universal constant, but affected by many factors and can be both positive and negative. It is further shown how the gravitational coefficients are different for the planets in the solar system. The new rational mechanics expounds that the force causing an apple falling from a tree is not the same force causing the Earth revolving about the Sun. The gravitational force is the combining effect of shielding and shooting of gravitons between the Sun and Earth, whereas a dropped apple falling from a tree is due to the surface adsorption of Earth, called the blowing force. From this, we can rigorously prove that all electrically neutral bodies must fall with the same acceleration. However, any electrically charged bodies fall with different accelerations. It is also deduced that the weight of a magnet and its acceleration of falling depend on its orientation. So we have to distinguish weight and gravity. Moreover, the weight of a body may not be a conservative force on a planet.

  11. Gravitational wave emission from the single-degenerate channel of Type Ia supernovae.

    PubMed

    Falta, David; Fisher, Robert; Khanna, Gaurav

    2011-05-20

    The thermonuclear explosion of a C/O white dwarf as a Type Ia supernova (SN Ia) generates a kinetic energy comparable to that released by a massive star during a SN II event. Current observations and theoretical models have established that SNe Ia are asymmetric, and therefore--like SNe II--potential sources of gravitational wave (GW) radiation. We perform the first detailed calculations of the GW emission for a SN Ia of any type within the single-degenerate channel. The gravitationally confined detonation (GCD) mechanism predicts a strongly polarized GW burst in the frequency band around 1 Hz. Third-generation spaceborne GW observatories currently in planning may be able to detect this predicted signal from SNe Ia at distances up to 1 Mpc. If observable, GWs may offer a direct probe into the first few seconds of the SNe Ia detonation. PMID:21668216

  12. Gravitational waves and short gamma ray bursts

    NASA Astrophysics Data System (ADS)

    Predoi, Valeriu

    2012-07-01

    Short hard gamma-ray bursts (GRB) are believed to be produced by compact binary coalescences (CBC) { either double neutron stars or neutron star{black hole binaries. The same source is expected to emit strong gravitational radiation, detectable with existing and planned gravitational wave observatories. The focus of this work is to describe a series of searches for gravitational waves (GW) from compact binary coalescence (CBC) events triggered by short gamma-ray burst detections. Specifically, we will present the motivation, frameworks, implementations and results of searches for GW associated with short gamma-ray bursts detected by Swift, Fermi{GBM and the InterPlanetary Network (IPN) gamma-ray detectors. We will begin by presenting the main concepts that lay the foundation of gravitational waves emission, as they are formulated in the theory of General Relativity; we will also brie y describe the operational principles of GW detectors, together with explaining the main challenges that the GW detection process is faced with. Further, we will motivate the use of observations in the electromagnetic (EM) band as triggers for GW searches, with an emphasis on possible EM signals from CBC events. We will briefly present the data analysis techniques including concepts as matched{filtering through a collection of theoretical GW waveforms, signal{to{ noise ratio, coincident and coherent analysis approaches, signal{based veto tests and detection candidates' ranking. We will use two different GW{GRB search examples to illustrate the use of the existing coincident and coherent analysis methods. We will also present a series of techniques meant to improve the sensitivity of existing GW triggered searches. These include shifting background data in time in order to obtain extended coincident data and setting a prior on the GRB inclination angle, in accordance with astrophysical observations, in order to restrict the searched parameter space. We will describe the GW data analysis

  13. 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.

  14. Precision X-ray Timing of RX J0806.3+1527 with CHANDRA: Evidence for Gravitational Radiation from an Ultracompact Binary

    NASA Technical Reports Server (NTRS)

    Strohymayer, Tod E.

    2004-01-01

    RX J0806.3+1527 is a candidate double degenerate binary with possibly the shortest known orbital period. The source shows an approximately equal to 100% X-ray intensity modulation at the putative orbital frequency of 3.11 mHz (321.5 s). If the system is a detached, ultracompact binary gravitational radiation should drive spin-up with a magnitude of nu(sup dot) approximately 10(exp -16) Hz per second. Efforts to constrain the X-ray frequency evolution to date have met with mixed success, principally due to the sparseness of earlier observations. Here we describe the results of the first phase coherent X-ray monitoring campaign on RX J0806.3+1527 with Chandra. We obtained a total of 70 ksec of exposure in 6 epochs logarithmically spaced over 320 days. With these data we conclusively show that the X-ray frequency is increasing at a rate of 3.77 plus or minus 0.8 x 10(exp -16) Hz per second. Using the ephemeris derived from the new data we are able to phase up all the earlier Chandra and ROSAT data and show they are consistent with a constant nu(sup dot) = 3.63 plus or minus 0.06 x 10(exp -16) Hz per second over the past decade. This value appears consistent with that recently derived by Israel et al. largely from monitoring of the optical modulation, and is in rough agreement with the solutions reported initially by Hakala et al., based on ground-based optical observations. The large and stable nu(sup dot) over a decade is consistent with gravitational radiation losses driving the evolution. An intermediate polar (IP) scenario where the observed X-ray period is the spin period of an accreting white dwarf appears less tenable because the observed nu(sup dot) requires an m(sup dot) approximately equal to 4 x 10 (exp -8) solar mass yr(sup -l), that is much larger than that inferred from the observed X-ray luminosity (although this depends on the uncertain distance and bolometric corrections), and it is difficult to drive such a high m(sup dot) in a binary system with

  15. Efficiency of ETV diagrams as diagnostic tools for long-term period variations. II. Non-conservative mass transfer, and gravitational radiation

    NASA Astrophysics Data System (ADS)

    Nanouris, N.; Kalimeris, A.; Antonopoulou, E.; Rovithis-Livaniou, H.

    2015-03-01

    Context. The credibility of an eclipse timing variation (ETV) diagram analysis is investigated for various manifestations of the mass transfer and gravitational radiation processes in binary systems. The monotonicity of the period variations and the morphology of the respective ETV diagrams are thoroughly explored in both the direct impact and the accretion disk mode of mass transfer, accompanied by different types of mass and angular momentum losses (through a hot-spot emission from the gainer and via the L2/L3 points). Aims: Our primary objective concerns the traceability of each physical mechanism by means of an ETV diagram analysis. Also, possible critical mass ratio values are sought for those transfer modes that involve orbital angular momentum losses strong enough to dictate the secular period changes even when highly competitive mechanisms with the opposite direction act simultaneously. Methods: The dot{J-dot{P}} relation that governs the orbital evolution of a binary system is set to provide the exact solution for the period and the function expected to represent the subsequent eclipse timing variations. The angular momentum transport is parameterized through appropriate empirical relations, which are inferred from semi-analytical ballistic models. Then, we numerically determine the minimum temporal range over which a particular mechanism is rendered measurable, as well as the critical mass ratio values that signify monotonicity inversion in the period modulations. Results: Mass transfer rates comparable to or greater than 10-8 M⊙ yr-1 are measurable for typical noise levels of the ETV diagrams, regardless of whether the process is conservative. However, the presence of a transient disk around the more massive component defines a critical mass ratio (qcr ≈ 0.83) above which the period turns out to decrease when still in the conservative regime, rendering the measurability of the anticipated variations a much more complicated task. The effects of

  16. Conservative, gravitational self-force for a particle in circular orbit around a Schwarzschild black hole in a radiation gauge

    SciTech Connect

    Shah, Abhay G.; Friedman, John L.; Price, Larry R.; Keidl, Tobias S.; Kim, Dong-Hoon

    2011-03-15

    This is the second of two companion papers on computing the self-force in a radiation gauge; more precisely, the method uses a radiation gauge for the radiative part of the metric perturbation, together with an arbitrarily chosen gauge for the parts of the perturbation associated with changes in black-hole mass and spin and with a shift in the center of mass. In a test of the method delineated in the first paper, we compute the conservative part of the self-force for a particle in circular orbit around a Schwarzschild black hole. The gauge vector relating our radiation gauge to a Lorenz gauge is helically symmetric, implying that the quantity h{sub {alpha}{beta}u}{sup {alpha}u{beta}} must have the same value for our radiation gauge as for a Lorenz gauge; and we confirm this numerically to one part in 10{sup 14}. As outlined in the first paper, the perturbed metric is constructed from a Hertz potential that is in a term obtained algebraically from the retarded perturbed spin-2 Weyl scalar, {psi}{sub 0}{sup ret}. We use a mode-sum renormalization and find the renormalization coefficients by matching a series in L=l+1/2 to the large-L behavior of the expression for the self-force in terms of the retarded field h{sub {alpha}{beta}}{sup ret}; we similarly find the leading renormalization coefficients of h{sub {alpha}{beta}u}{sup {alpha}u{beta}} and the related change in the angular velocity of the particle due to its self-force. We show numerically that the singular part of the self-force has the form f{sub {alpha}}{sup S}=<{nabla}{sub {alpha}{rho}}{sup -1}>, the part of {nabla}{sub {alpha}{rho}}{sup -1} that is axisymmetric about a radial line through the particle. This differs only by a constant from its form for a Lorenz gauge. It is because we do not use a radiation gauge to describe the change in black-hole mass that the singular part of the self-force has no singularity along a radial line through the particle and, at least in this example, is spherically

  17. Conservative, gravitational self-force for a particle in circular orbit around a Schwarzschild black hole in a radiation gauge

    NASA Astrophysics Data System (ADS)

    Shah, Abhay G.; Keidl, Tobias S.; Friedman, John L.; Kim, Dong-Hoon; Price, Larry R.

    2011-03-01

    This is the second of two companion papers on computing the self-force in a radiation gauge; more precisely, the method uses a radiation gauge for the radiative part of the metric perturbation, together with an arbitrarily chosen gauge for the parts of the perturbation associated with changes in black-hole mass and spin and with a shift in the center of mass. In a test of the method delineated in the first paper, we compute the conservative part of the self-force for a particle in circular orbit around a Schwarzschild black hole. The gauge vector relating our radiation gauge to a Lorenz gauge is helically symmetric, implying that the quantity hαβuαuβ must have the same value for our radiation gauge as for a Lorenz gauge; and we confirm this numerically to one part in 1014. As outlined in the first paper, the perturbed metric is constructed from a Hertz potential that is in a term obtained algebraically from the retarded perturbed spin-2 Weyl scalar, ψ0ret. We use a mode-sum renormalization and find the renormalization coefficients by matching a series in L=ℓ+1/2 to the large-L behavior of the expression for the self-force in terms of the retarded field hαβret; we similarly find the leading renormalization coefficients of hαβuαuβ and the related change in the angular velocity of the particle due to its self-force. We show numerically that the singular part of the self-force has the form fαS=⟨∇αρ-1⟩, the part of ∇αρ-1 that is axisymmetric about a radial line through the particle. This differs only by a constant from its form for a Lorenz gauge. It is because we do not use a radiation gauge to describe the change in black-hole mass that the singular part of the self-force has no singularity along a radial line through the particle and, at least in this example, is spherically symmetric to subleading order in ρ.

  18. LISA in the gravitational wave decade

    NASA Astrophysics Data System (ADS)

    Conklin, John; Cornish, Neil

    2015-04-01

    With the expected direct detection of gravitational waves in the second half of this decade by Advanced LIGO and pulsar timing arrays, and with the launch of LISA Pathfinder in the summer of this year, 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. Recently, NASA has decided to join with ESA on the L3 mission as a junior partner. Both agencies formed a committee to advise them on the scientific and technological approaches for a space based gravitational wave observatory. The leading mission design, Evolved LISA or eLISA, is a slightly de-scoped version of the earlier LISA design. This talk will describe activities of the Gravitational Wave Science Interest Group (GWSIG) under the Physics of the Cosmos Program Analysis Group (PhysPAG), focusing on LISA technology development in both the U.S. and Europe, including the LISA Pathfinder mission.

  19. Magnetar asteroseismology with long-term gravitational waves

    SciTech Connect

    Kashiyama, Kazumi; Ioka, Kunihito

    2011-04-15

    Magnetic flares and induced oscillations of magnetars (supermagnetized neutron stars) are promising sources of gravitational waves (GWs). We suggest that the GW emission, if any, would last longer than the observed x-ray quasiperiodic oscillations (X-QPOs), calling for longer-term GW analyses lasting a day to months, compared to current searches' durations. Like the pulsar timing, the oscillation frequency would also evolve with time because of the decay or reconfiguration of the magnetic field, which is crucial for the GW detection. With the observed GW frequency and its time-derivatives, we can probe the interior magnetic field strength of {approx}10{sup 16} G and its evolution to open a new GW asteroseismology with the next generation interferometers like the advanced laser interferometer gravitational wave observatory, the advanced Virgo gravitational wave detector at the European Gravitational Observatory, the Large-scale cryogenic gravitational wave telescope, and the Einstein telescope.

  20. 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.

  1. Towers of Gravitational Theories

    NASA Astrophysics Data System (ADS)

    Goldberger, Walter D.; Rothstein, Ira Z.

    In this essay, we introduce a theoretical framework designed to describe black hole dynamics. The difficulties in understanding such dynamics stems from the proliferation of scales involved when one attempts to simultaneously describe all of the relevant dynamical degrees of freedom. These range from the modes that describe the black hole horizon, which are responsible for dissipative effects, to the long wavelength gravitational radiation that drains mechanical energy from macroscopic black hole bound states. We approach the problem from a Wilsonian point of view, by building a tower of theories of gravity each of which is valid at different scales. The methodology leads to multiple new results in diverse topics including phase transitions of Kaluza-Klein black holes and the interactions of spinning black hole in non-relativistic orbits. Moreover, our methods tie together speculative ideas regarding dualities for black hole horizons to real physical measurements in gravitational wave detectors.

  2. Towers of gravitational theories

    NASA Astrophysics Data System (ADS)

    Goldberger, Walter D.; Rothstein, Ira Z.

    2006-11-01

    In this essay we introduce a theoretical framework designed to describe black hole dynamics. The difficulties in understanding such dynamics stems from the proliferation of scales involved when one attempts to simultaneously describe all of the relevant dynamical degrees of freedom. These range from the modes that describe the black hole horizon, which are responsible for dissipative effects, to the long wavelength gravitational radiation that drains mechanical energy from macroscopic black hole bound states. We approach the problem from a Wilsonian point of view, by building a tower of theories of gravity each of which is valid at different scales. The methodology leads to multiple new results in diverse topics including phase transitions of Kaluza-Klein black holes and the interactions of spinning black hole in non-relativistic orbits. Moreover, our methods tie together speculative ideas regarding dualities for black hole horizons to real physical measurements in gravitational wave detectors.

  3. Gravitational Lensing

    NASA Astrophysics Data System (ADS)

    Saha, P.; Murdin, P.

    2000-11-01

    Gravity bends light rays in a way analogous to, but quantitatively different from, the way it bends trajectories of passing particles. If light from some bright object passes close enough to some foreground mass, that object's image will be altered. The effect is more like a piece of bathroom glass in the sky than a precision-ground and well-focused lens, but the terms `gravitational lensing' or ...

  4. 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.

  5. SOFIA: Stratospheric Observatory for Infrared Astronomy

    NASA Technical Reports Server (NTRS)

    Erickson, E. F.; Davidson, J. A.

    1993-01-01

    SOFIA, (Stratospheric Observatory for Infrared Astronomy) is a planned 2.5 meter telescope to be installed in a Boeing 747 aircraft and operated at altitudes from 41,000 to 46,000 feet. It will permit routine measurement of infrared radiation inaccessible from the ground-based sites, and observation of astronomical objects and transient events from anywhere in the world. The concept is based on 18 years of experience with NASA's Kuiper Airborne Observatory (KAO), which SOFIA would replace.

  6. Gravitational-wave stochastic background from cosmic strings.

    PubMed

    Siemens, Xavier; Mandic, Vuk; Creighton, Jolien

    2007-03-16

    We consider the stochastic background of gravitational waves produced by a network of cosmic strings and assess their accessibility to current and planned gravitational wave detectors, as well as to big bang nucleosynthesis (BBN), cosmic microwave background (CMB), and pulsar timing constraints. We find that current data from interferometric gravitational wave detectors, such as Laser Interferometer Gravitational Wave Observatory (LIGO), are sensitive to areas of parameter space of cosmic string models complementary to those accessible to pulsar, BBN, and CMB bounds. Future more sensitive LIGO runs and interferometers such as Advanced LIGO and Laser Interferometer Space Antenna (LISA) will be able to explore substantial parts of the parameter space. PMID:17501038

  7. 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

  8. Highlights in gravitation and cosmology

    NASA Astrophysics Data System (ADS)

    Iyer, B. R.; Vishveshwara, C. V.; Narlikar, Jayant V.; Kembhavi, Ajit K.

    1988-01-01

    Theoretical and observational studies in gravitation and cosmology are discussed in reviews and reports presented at the international conference held in Goa, India on December 14-19, 1987. Sections are devoted to classical relativity, quantum gravity, black holes and compact objects, and gravitational-radiation and gravity experiments. Particular attention is given to exact solutions of the Einstein equations and their classification, the asymptotic structure of isolated systems, the physical properties and parameters of radiative space-times, canonical quantization of generally covariant systems, field theories of quantum gravity, observational and theoretical aspects of dark matter, gravitational lenses, cosmic strings and galaxy formation, black-hole thermodynamics, the general relativity of compact objects, the general-relativistic problem of motion and binary pulsars, and relativity and fifth-force experiments.

  9. The Terzan 2 Cluster Taken by the High Energy Astronomy Observatory (HEAO)-2

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The dramatic change in x-ray emission from the Terzan 2 cluster is shown in this series of 2.5-minute exposures taken with the High Energy Astronomy Observatory (HEAO)-2/Einstein Observatory immediately before, during, and after the burst. Total exposure (20 minutes) of the object, including the outburst, is shown in the fourth photograph. These images represent the first observation of an x-ray burst in progress. The actual burst lasted 50 seconds. Among the rarest, and most bizarre, phenomena observed by x-ray astronomers are the so-called cosmic bursters (x-ray sources that suddenly and dramatically increase in intensity then subside). These sudden bursts of intense x-ray radiation apparently come from compact objects with a diameter smaller than 30 miles (48 kilometers). Yet, despite their minuscule size, a typical x-ray burster can release more x-ray energy in a single brief burst than our Sun does in an entire week. The HEAO-2, the first imaging and largest x-ray telescope built to date, was capable of producing actual photographs of x-ray objects. Shortly after launch, the HEAO-2 was nicknamed the Einstein Observatory by its scientific experimenters in honor of the centernial of the birth of Albert Einstein, whose concepts of relativity and gravitation have influenced much of modern astrophysics, particularly x-ray astronomy. The HEAO was designed and developed by TRW, Inc. under the project management of the Marshall Space Flight Center.

  10. Image of the Quasar 3C 273 Taken by the High Energy Astronomy Observatory (HEAO)-2

    NASA Technical Reports Server (NTRS)

    1979-01-01

    This image is an observation of Quasar 3C 273 by the High Energy Astronomy Observatory (HEAO)-2/Einstein Observatory. It reveals the presence of a new source (upper left) with a red shift that indicates that it is about 10 billion light years away. Quasars are mysterious, bright, star-like objects apparently located at the very edge of the visible universe. Although no bigger than our solar system, they radiate as much visible light as a thousand galaxies. Quasars also emit radio signals and were previously recognized as x-ray sources. The HEAO-2, the first imaging and largest x-ray telescope built to date, was capable of producing actual photographs of x-ray objects. Shortly after launch, the HEAO-2 was nicknamed the Einstein Observatory by its scientific experimenters in honor of the centernial of the birth of Albert Einstein, whose concepts of relativity and gravitation have influenced much of modern astrophysics, particularly x-ray astronomy. The HEAO-2 was designed and developed by TRW, Inc. under the project management of the Marshall Space Flight Center.

  11. Image of the Vela Supernova Remnant Taken by the High Energy Astronomy Observatory (HEAO)-2

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Like the Crab Nebula, the Vela Supernova Remnant has a radio pulsar at its center. In this image taken by the High Energy Astronomy Observatory (HEAO)-2/Einstein Observatory, the pulsar appears as a point source surrounded by weak and diffused emissions of x-rays. HEAO-2's computer processing system was able to record and display the total number of x-ray photons (a tiny bundle of radiant energy used as the fundamental unit of electromagnetic radiation) on a scale along the margin of the picture. The HEAO-2, the first imaging and largest x-ray telescope built to date, was capable of producing actual photographs of x-ray objects. Shortly after launch, the HEAO-2 was nicknamed the Einstein Observatory by its scientific experimenters in honor of the centernial of the birth of Albert Einstein, whose concepts of relativity and gravitation have influenced much of modern astrophysics, particularly x-ray astronomy. The HEAO-2, designed and developed by TRW, Inc. under the project management of the Marshall Space Flight Center, was launched aboard an Atlas/Centaur launch vehicle on November 13, 1978.

  12. Propagation of a spherical shock wave in mixture of non-ideal gas and small solid particles under the influence of gravitational field with conductive and radiative heat fluxes

    NASA Astrophysics Data System (ADS)

    Nath, G.

    2016-01-01

    Self-similar solutions are obtained for one-dimensional unsteady adiabatic flow behind a spherical shock wave propagating in a dusty gas with conductive and radiative heat fluxes under the influence of a gravitational field. The shock is assumed to be driven out by a moving piston and the dusty gas to be a mixture of non-ideal gas and small solid particles, in which solid particles are uniformly distributed. It is assumed that the equilibrium flow-conditions are maintained and variable energy input is continuously supplied by the piston. The heat conduction is expressed in terms of Fourier's law and the radiation is considered to be of the diffusion type for an optically thick grey gas model. The thermal conductivity K and the absorption coefficient αR are assumed to vary with temperature and density. The medium is assumed to be under the influence of a gravitational field due to central mass ( bar{m} ) at the origin (Roche Model). It is assumed that the gravitational effect of the mixture itself can be neglected compared with the attraction of the central mass. The initial density of the ambient medium is taken to be always constant. The effects of the variation of the gravitational parameter and nonidealness of the gas in the mixture are investigated. Also, the effects of an increase in (i) the mass concentration of solid particles in the mixture and (ii) the ratio of the density of solid particles to the initial density of the gas on the flow variables are investigated. It is shown that due to an increase in the gravitational parameter the compressibility of the medium at any point in the flow-field behind the shock decreases and all other flow variables and the shock strength are increased. Further, it is found that the presence of gravitational field increases the compressibility of the medium, due to which it is compressed and therefore the distance between the piston and the shock surface is reduced. The shock waves in dusty gas under the influence of a

  13. The Detection of Gravitational Waves

    NASA Astrophysics Data System (ADS)

    Braccini, Stefano; Fidecaro, Francesco

    The detection of gravitational waves is challenging researchers since half a century. The relative precision required, 10^{-21}, is difficult to imagine, this is 10^{-5} the diameter of a proton over several kilometres, using masses of tens of kilograms, or picometres over millions of kilometres. A theoretical description of gravitational radiation and its effects on matter, all consequence of the general theory of relativity, is given. Then the astrophysical phenomena that are candidates of gravitational wave emission are discussed, considering also amplitudes and rates. The binary neutron star system PSR1913+16, which provided the first evidence for energy loss by gravitational radiation in 1975, is briefly discussed. Then comes a description of the experimental developments, starting with ground-based interferometers, their working principles and their most important sources of noise. The earth-wide network that is being built describes how these instruments will be used in the observation era. Several other detection techniques, such as space interferometry, pulsar timing arrays and resonant detectors, covering different bands of the gravitational wave frequency spectrum complete these lectures.

  14. Gravitational Wave Detection: A Historical Perspective

    NASA Astrophysics Data System (ADS)

    Saulson, Peter

    2015-04-01

    The search for gravitational waves began at the Chapel Hill Conference in January 1957, and will reach a successful conclusion at a set of observatories around the globe about sixty years later. This talk will review the history of the early thought experiments, the program of resonant mass detectors (``Weber bars''), and the development of the large interferometric detectors like Advanced LIGO and Advanced Virgo that are, it is hoped, about to make the first detections of gravitational wave signals. I am pleased to acknowledge the support of the National Science Foundation for my research, most recently under NSF Grant PHY-1205835.

  15. General Relativity and Gravitation, 1989

    NASA Astrophysics Data System (ADS)

    Ashby, Neil; Bartlett, David F.; Wyss, Walker

    2005-10-01

    Part I. Classical Relativity and Gravitation Theory: 1. Global properties of exact solutions H. Friedrich; 2. Numerical relativity T. Nakamura; 3. How fast can a pulsar spin? J. L. Friedman; 4. Colliding waves in general relativity V. Ferrari; Part II. Relativistic Astrophysics, Early Universe, and Classical Cosmology: 5. Observations of cosmic microwave radiation R. B. Partridge; 6. Cosmic microwave background radiation (theory) M. Panek; 7. Inflation and quantum cosmology A. D. Linde; 8. Observations of lensing B. Fort; 9. Gravitational lenses: theory and interpretation R. Blandford; Part III. Experimental Gravitation and Gravitational Waves: 10. Solar system tests of GR: recent results and present plans I. Shapiro; 11. Laser interferometer detectors R. Weiss; 12. Resonant bar gravitational wave experiments G. Pizzella; 13. A non-inverse square law test E. Adelberger; Part IV. Quantum Gravity, Superstrings, Quantum Cosmology: 14. Cosmic strings B. Unruh; 15. String theory as a quantum theory of gravity G. Horowitz; 16. Progress in quantum cosmology J. B. Hartle; 17. Self-duality, quantum gravity, Wilson loops and all that A. V. Ashtekar; Part V. Summary Talk: 18. GR-12 Conference summary J. Ehlers II; Part VI. Reports on Workshops/Symposia: 19. Exact solutions and exact properties of Einstein equations V. Moncrieff; 20. Spinors, twistors and complex methods N. Woodhouse; 21. Alternative gravity theories M. Francaviglia; 22. Asymptotia, singularities and global structure B. G. Schmidt; 23. Radiative spacetimes and approximation methods T. Damour; 24. Algebraic computing M. MacCallum; 25. Numerical relativity J. Centrella; 26. Mathematical cosmology J. Wainwright; 27. The early universe M. Turner; 28. Relativistic astrophysics M. Abramowitz; 29. Astrophysical and observational cosmology B. Carr; 30. Solar system and pulsar tests of gravitation R. Hellings; 31. Earth-based gravitational experiments J. Faller; 32. Resonant bar and microwave gravitational wave

  16. General Relativity and Gravitation, 1989

    NASA Astrophysics Data System (ADS)

    Ashby, Neil; Bartlett, David F.; Wyss, Walker

    1990-11-01

    Part I. Classical Relativity and Gravitation Theory: 1. Global properties of exact solutions H. Friedrich; 2. Numerical relativity T. Nakamura; 3. How fast can a pulsar spin? J. L. Friedman; 4. Colliding waves in general relativity V. Ferrari; Part II. Relativistic Astrophysics, Early Universe, and Classical Cosmology: 5. Observations of cosmic microwave radiation R. B. Partridge; 6. Cosmic microwave background radiation (theory) M. Panek; 7. Inflation and quantum cosmology A. D. Linde; 8. Observations of lensing B. Fort; 9. Gravitational lenses: theory and interpretation R. Blandford; Part III. Experimental Gravitation and Gravitational Waves: 10. Solar system tests of GR: recent results and present plans I. Shapiro; 11. Laser interferometer detectors R. Weiss; 12. Resonant bar gravitational wave experiments G. Pizzella; 13. A non-inverse square law test E. Adelberger; Part IV. Quantum Gravity, Superstrings, Quantum Cosmology: 14. Cosmic strings B. Unruh; 15. String theory as a quantum theory of gravity G. Horowitz; 16. Progress in quantum cosmology J. B. Hartle; 17. Self-duality, quantum gravity, Wilson loops and all that A. V. Ashtekar; Part V. Summary Talk: 18. GR-12 Conference summary J. Ehlers II; Part VI. Reports on Workshops/Symposia: 19. Exact solutions and exact properties of Einstein equations V. Moncrieff; 20. Spinors, twistors and complex methods N. Woodhouse; 21. Alternative gravity theories M. Francaviglia; 22. Asymptotia, singularities and global structure B. G. Schmidt; 23. Radiative spacetimes and approximation methods T. Damour; 24. Algebraic computing M. MacCallum; 25. Numerical relativity J. Centrella; 26. Mathematical cosmology J. Wainwright; 27. The early universe M. Turner; 28. Relativistic astrophysics M. Abramowitz; 29. Astrophysical and observational cosmology B. Carr; 30. Solar system and pulsar tests of gravitation R. Hellings; 31. Earth-based gravitational experiments J. Faller; 32. Resonant bar and microwave gravitational wave

  17. The Milankovitch Orbital Elements and Their Application to the Long-term Orbit Evolution of Planetary Satellites Subject to Radiation and Gravitational Perturbations

    NASA Astrophysics Data System (ADS)

    Rosengren, Aaron; Scheeres, D. J.

    2013-05-01

    Abstract (2,250 Maximum Characters): In his monumental work on the astronomical theory of paleoclimates, Milutin Milankovitch (1879-1958) reformulated the classical method of perturbation of elements using the two vectorial integrals of the unperturbed two-body problem--the angular momentum (areal) vector and the Laplace vector. The vectorial integrals describe the spatial orientation, geometrical shape, and size of the osculating Keplerian orbit, and, together with the sixth scalar integral that represents the motion in time, constitutes a complete set of orbital elements. These elements are particularly useful in finding the first-order long-period and secular variations by averaging over the fast variables of the system. The application of the Milankovitch elements to the determination of oblateness and tidal effects leads to the equations for perturbed elements in which the small numerical divisors, the eccentricity and the sine of the inclination, are not present (Musen, P., J. Geophys. Res., 66, 1961; Allan, R.R., and Cook, G.E., Proc. R. Soc. A, 280, 1964). Tremaine et al. (AJ, 137, 2009) used the Milankovitch elements to study the classical Laplace plane, a region of space where the secular evolution of orbits driven by the combined effects of these forces is zero, so that the orbits are ``frozen.'' This talk will reintroduce the Milankovitch elements, present a completely nonsingular form of them, and show their application to the long-term orbit evolution of irregular satellites, binary asteroids, and other planetary systems. We will also show how the Laplace plane equilibrium can be generalized to accommodate non-gravitational forces, such as solar radiation perturbations.

  18. Gravitational wave background from Standard Model physics: qualitative features

    SciTech Connect

    Ghiglieri, J.; Laine, M.

    2015-07-16

    Because of physical processes ranging from microscopic particle collisions to macroscopic hydrodynamic fluctuations, any plasma in thermal equilibrium emits gravitational waves. For the largest wavelengths the emission rate is proportional to the shear viscosity of the plasma. In the Standard Model at T>160 GeV, the shear viscosity is dominated by the most weakly interacting particles, right-handed leptons, and is relatively large. We estimate the order of magnitude of the corresponding spectrum of gravitational waves. Even though at small frequencies (corresponding to the sub-Hz range relevant for planned observatories such as eLISA) this background is tiny compared with that from non-equilibrium sources, the total energy carried by the high-frequency part of the spectrum is non-negligible if the production continues for a long time. We suggest that this may constrain (weakly) the highest temperature of the radiation epoch. Observing the high-frequency part directly sets a very ambitious goal for future generations of GHz-range detectors.

  19. Gravitational waves from the fragmentation of a supersymmetric condensate

    SciTech Connect

    Kusenko, Alexander; Mazumdar, Anupam; Multamaeki, Tuomas

    2009-06-15

    We discuss the production of gravity waves from the fragmentation of a supersymmetric condensate in the early Universe. Supersymmetry predicts the existence of flat directions in the potential. At the end of inflation, the scalar fields develop large time-dependent vacuum expectation values along these flat directions. Under some general conditions, the scalar condensates undergo a fragmentation into nontopological solitons, Q-balls. We study this process numerically and confirm the recent analytical calculations showing that it can produce gravity waves observable by the Advanced Laser Interferometer Gravitational Wave Observatory, Laser Interferometer Space Antenna, and Big Bang Observer. The fragmentation can generate gravity waves with an amplitude as large as {omega}{sub GW}h{sup 2}{approx}10{sup -11} and with a peak frequency ranging from 1 mHz to 10 Hz, depending on the parameters. The discovery of such a relic gravitational background radiation can open a new window on the physics at the high scales, even if supersymmetry is broken well above the electroweak scale.

  20. Chiral primordial gravitational waves from a Lifshitz point.

    PubMed

    Takahashi, Tomohiro; Soda, Jiro

    2009-06-12

    We study primordial gravitational waves produced during inflation in quantum gravity at a Lifshitz point proposed by Horava. Assuming power-counting renormalizability, foliation-preserving diffeomorphism invariance, and the condition of detailed balance, we show that primordial gravitational waves are circularly polarized due to parity violation. The chirality of primordial gravitational waves is a quite robust prediction of quantum gravity at a Lifshitz point which can be tested through observations of cosmic microwave background radiation and stochastic gravitational waves. PMID:19658921

  1. INTERMAGNET and magnetic observatories

    USGS Publications Warehouse

    Love, Jeffrey J.; Chulliat, Arnaud

    2012-01-01

    A magnetic observatory is a specially designed ground-based facility that supports time-series measurement of the Earth’s magnetic field. Observatory data record a superposition of time-dependent signals related to a fantastic diversity of physical processes in the Earth’s core, mantle, lithosphere, ocean, ionosphere, magnetosphere, and, even, the Sun and solar wind.

  2. The Norwegian Naval Observatories

    NASA Astrophysics Data System (ADS)

    Pettersen, Bjørn Ragnvald

    2007-07-01

    Archival material has revealed milestones and new details in the history of the Norwegian Naval Observatories. We have identified several of the instrument types used at different epochs. Observational results have been extracted from handwritten sources and an extensive literature search. These allow determination of an approximate location of the first naval observatory building (1842) at Fredriksvern. No physical remains exist today. A second observatory was established in 1854 at the new main naval base at Horten. Its location is evident on military maps and photographs. We describe its development until the Naval Observatory buildings, including archives and instruments, were completely demolished during an allied air bomb raid on 23 February 1945. The first director, C.T.H. Geelmuyden, maintained scientific standards at the the Observatory between 1842 and 1870, and collaborated with university astronomers to investigate, develop, and employ time-transfer by telegraphy. Their purpose was accurate longitude determination between observatories in Norway and abroad. The Naval Observatory issued telegraphic time signals twice weekly to a national network of sites, and as such served as the first national time-service in Norway. Later the Naval Observatory focused on the particular needs of the Navy and developed into an internal navigational service.

  3. Beijing Ancient Observatory

    NASA Astrophysics Data System (ADS)

    Shi, Yunli

    The Beijing Ancient Observatory is now the only complete example of an observatory from the seventeenth century in the world. It is a monument to the prosperity of astronomy in traditional China. Its instruments are emblems of the encounter and amalgamation of Chinese and European Science in the seventeenth and eighteenth centuries.

  4. Svetloe Radio Astronomical Observatory

    NASA Technical Reports Server (NTRS)

    Smolentsev, Sergey; Rahimov, Ismail

    2013-01-01

    This report summarizes information about the Svetloe Radio Astronomical Observatory activities in 2012. Last year, a number of changes took place in the observatory to improve some technical characteristics and to upgrade some units to their required status. The report provides an overview of current geodetic VLBI activities and gives an outlook for the future.

  5. Zelenchukskaya Radio Astronomical Observatory

    NASA Technical Reports Server (NTRS)

    Smolentsev, Sergey; Dyakov, Andrei

    2013-01-01

    This report summarizes information about Zelenchukskaya Radio Astronomical Observatory activities in 2012. Last year a number of changes took place in the observatory to improve some technical characteristics and to upgrade some units to the required status. The report provides an overview of current geodetic VLBI activities and gives an outlook for the future.

  6. Strasbourg's "Academy" observatory

    NASA Astrophysics Data System (ADS)

    Heck, André

    2011-08-01

    The observing post located on the roof of Strasbourg's 19th-century "Academy" is generally considered as the second astronomical observatory of the city: a transitional facility between the (unproductive) turret lantern at the top of the Hospital Gate and the German (Wilhelminian) Observatory. The current paper reviews recent findings from archives (blueprints, inventories, correspondence, decrees and other documents) shedding some light on this observatory of which virtually nothing was known to this day. While being, thanks to Chrétien Kramp (1760-1826), an effective attempt to establish an actual observatory equipped with genuine instrumentation, the succession of political regimes in France and the continual bidding for moving the university to other locations, together with the faltering of later scholars, torpedoed any significant scientific usage of the place. A meridian instrument with a Cauchoix objective doublet was however recovered by the German observatory and is still existing.

  7. High Energy Astronomy Observatory (HEAO)-2

    NASA Technical Reports Server (NTRS)

    1982-01-01

    This artist's concept depicts the High Energy Astronomy Observatory (HEAO)-2 in orbit. The HEAO-2, the first imaging and largest x-ray telescope built to date, was capable of producing actual photographs of x-ray objects. Shortly after launch, the HEAO-2 was nicknamed the Einstein Observatory by its scientific experimenters in honor of the centernial of the birth of Albert Einstein, whose concepts of relativity and gravitation have influenced much of modern astrophysics, particularly x-ray astronomy. The HEAO-2, designed and developed by TRW, Inc. under the project management of the Marshall Space Flight Center, was launched aboard an Atlas/Centaur launch vehicle on November 13, 1978. The HEAO-2 was originally identified as HEAO-B but the designation was changed once the spacecraft achieved orbit.

  8. Environmental effects on lunar astronomical observatories

    NASA Technical Reports Server (NTRS)

    Johnson, Stewart W.; Taylor, G. Jeffrey; Wetzel, John P.

    1992-01-01

    The Moon offers a stable platform with excellent seeing conditions for astronomical observations. Some troublesome aspects of the lunar environment will need to be overcome to realize the full potential of the Moon as an observatory site. Mitigation of negative effects of vacuum, thermal radiation, dust, and micrometeorite impact is feasible with careful engineering and operational planning. Shields against impact, dust, and solar radiation need to be developed. Means of restoring degraded surfaces are probably essential for optical and thermal control surfaces deployed in long-lifetime lunar facilities. Precursor missions should be planned to validate and enhance the understanding of the lunar environment (e.g., dust behavior without and with human presence) and to determine environmental effects on surfaces and components. Precursor missions should generate data useful in establishing keepout zones around observatory facilities where rocket launches and landings, mining, and vehicular traffic could be detrimental to observatory operation.

  9. 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.

  10. The Virtual Observatory: I

    NASA Astrophysics Data System (ADS)

    Hanisch, R. J.

    2014-11-01

    The concept of the Virtual Observatory arose more-or-less simultaneously in the United States and Europe circa 2000. Ten pages of Astronomy and Astrophysics in the New Millennium: Panel Reports (National Academy Press, Washington, 2001), that is, the detailed recommendations of the Panel on Theory, Computation, and Data Exploration of the 2000 Decadal Survey in Astronomy, are dedicated to describing the motivation for, scientific value of, and major components required in implementing the National Virtual Observatory. European initiatives included the Astrophysical Virtual Observatory at the European Southern Observatory, the AstroGrid project in the United Kingdom, and the Euro-VO (sponsored by the European Union). Organizational/conceptual meetings were held in the US at the California Institute of Technology (Virtual Observatories of the Future, June 13-16, 2000) and at ESO Headquarters in Garching, Germany (Mining the Sky, July 31-August 4, 2000; Toward an International Virtual Observatory, June 10-14, 2002). The nascent US, UK, and European VO projects formed the International Virtual Observatory Alliance (IVOA) at the June 2002 meeting in Garching, with yours truly as the first chair. The IVOA has grown to a membership of twenty-one national projects and programs on six continents, and has developed a broad suite of data access protocols and standards that have been widely implemented. Astronomers can now discover, access, and compare data from hundreds of telescopes and facilities, hosted at hundreds of organizations worldwide, stored in thousands of databases, all with a single query.

  11. The Penllergare Observatory

    NASA Astrophysics Data System (ADS)

    Birks, J. L.

    2005-12-01

    This rather picturesque and historically important Victorian observatory was built by the wealthy John Dillwyn Llewelyn near to his mansion, some four miles north-west of Swansea, Wales. He had many scientific interests, in addition to astronomy, and was a notable pioneer of photography in Wales. Together with his eldest daughter, Thereza, (who married the grandson of the fifth Astronomer Royal, Nevil Maskelyne), he took some early photographs of the Moon from this site. This paper describes the construction of the observatory, and some of those primarily involved with it. Despite its having undergone restoration work in 1982, the state of the observatory is again the cause for much concern.

  12. Multiparameter investigation of gravitational slip

    SciTech Connect

    Daniel, Scott F.; Caldwell, Robert R.; Cooray, Asantha; Serra, Paolo; Melchiorri, Alessandro

    2009-07-15

    A detailed analysis of gravitational slip, a new post-general relativity cosmological parameter characterizing the degree of departure of the laws of gravitation from general relativity on cosmological scales, is presented. This phenomenological approach assumes that cosmic acceleration is due to new gravitational effects; the amount of spacetime curvature produced per unit mass is changed in such a way that a universe containing only matter and radiation begins to accelerate as if under the influence of a cosmological constant. Changes in the law of gravitation are further manifest in the behavior of the inhomogeneous gravitational field, as reflected in the cosmic microwave background, weak lensing, and evolution of large-scale structure. The new parameter {pi}{sub 0} is naively expected to be of order unity. However, a multiparameter analysis, allowing for variation of all of the standard cosmological parameters, finds that {pi}{sub 0}=0.09{sub -0.59}{sup +0.74}(2{sigma}), where {pi}{sub 0}=0 corresponds to a cosmological constant plus cold dark matter universe under general relativity. Future probes of the cosmic microwave background (Planck) and large-scale structure (Euclid) may improve the limits by a factor of 4.

  13. 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.

  14. Electromagnetic waves propagation nearby rotating gravitating astrophysical object with atmosphere

    NASA Astrophysics Data System (ADS)

    Gladyshev, V. O.; Tereshin, A. A.; Fomin, I. V.; Chelnokov, M. B.; Kauts, V. L.; Gladysheva, T. M.; Bazleva, D. D.

    The aim of the article to explore the effects of gravitational lensing and attraction of electromagnetic radiation in the description of the propagation of radiation nearby the atmospheres of rotating astrophysical objects.

  15. Global Health Observatory (GHO)

    MedlinePlus

    ... repository Reports Country statistics Map gallery Standards Global Health Observatory (GHO) data Monitoring health for the SDGs ... relevant web pages on the theme. Monitoring the health goal: indicators of overall progress Mortality and global ...

  16. Observatory Improvements for SOFIA

    NASA Technical Reports Server (NTRS)

    Peralta, Robert A.; Jensen, Stephen C.

    2012-01-01

    The Stratospheric Observatory for Infrared Astronomy (SOFIA) is a joint project between NASA and Deutsches Zentrum fuer Luft- und Raumfahrt (DLR), the German Space Agency. SOFIA is based in a Boeing 747 SP and flown in the stratosphere to observe infrared wavelengths unobservable from the ground. In 2007 Dryden Flight Research Center (DFRC) inherited and began work on improving the plane and its telescope. The improvements continue today with upgrading the plane and improving the telescope. The Observatory Verification and Validation (V&V) process is to ensure that the observatory is where the program says it is. The Telescope Status Display (TSD) will provide any information from the on board network to monitors that will display the requested information. In order to assess risks to the program, one must work through the various threats associate with that risk. Once all the risks are closed the program can work towards improving the observatory.

  17. Gravitational Wave Experiments - Proceedings of the First Edoardo Amaldi Conference

    NASA Astrophysics Data System (ADS)

    Coccia, E.; Pizzella, G.; Ronga, F.

    1995-07-01

    Table of Contents for the full book PDF is as follows: * Foreword * Notes on Edoardo Amaldi's Life and Activity * PART I. INVITED LECTURES * Sources and Telescopes * Sources of Gravitational Radiation for Detectors of the 21st Century * Neutrino Telescopes * γ-Ray Bursts * Space Detectors * LISA — Laser Interferometer Space Antenna for Gravitational Wave Measurements * Search for Massive Coalescing Binaries with the Spacecraft ULYSSES * Interferometers * The LIGO Project: Progress and Prospects * The VIRGO Experiment: Status of the Art * GEO 600 — A 600-m Laser Interferometric Gravitational Wave Antenna * 300-m Laser Interferometer Gravitational Wave Detector (TAMA300) in Japan * Resonant Detectors * Search for Continuous Gravitational Wave from Pulsars with Resonant Detector * Operation of the ALLEGRO Detector at LSU * Preliminary Results of the New Run of Measurements with the Resonant Antenna EXPLORER * Operation of the Perth Cryogenic Resonant-Bar Gravitational Wave Detector * The NAUTILUS Experiment * Status of the AURIGA Gravitational Wave Antenna and Perspectives for the Gravitational Waves Search with Ultracryogenic Resonant Detectors * Ultralow Temperature Resonant-Mass Gravitational Radiation Detectors: Current Status of the Stanford Program * Electromechanical Transducers and Bandwidth of Resonant-Mass Gravitational-Wave Detectors * Fully Numerical Data Analysis for Resonant Gravitational Wave Detectors: Optimal Filter and Available Information * PART II. CONTRIBUTED PAPERS * Sources and Telescopes * The Local Supernova Production * Periodic Gravitational Signals from Galactic Pulsars * On a Possibility of Scalar Gravitational Wave Detection from the Binary Pulsars PSR 1913+16 * Kazan Gravitational Wave Detector “Dulkyn”: General Concept and Prospects of Construction * Hierarchical Approach to the Theory of Detection of Periodic Gravitational Radiation * Application of Gravitational Antennae for Fundamental Geophysical Problems * On Production

  18. Big Bear Solar Observatory

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    Big Bear Solar Observatory (BBSO) is located at the end of a causeway in a mountain lake more than 2 km above sea level. The site has more than 300 sunny days a year and a natural inversion caused by the lake which makes for very clean images. BBSO is the only university observatory in the US making high-resolution observations of the Sun. Its daily images are posted at http://www.bbso.njit.e...

  19. Characterization of the high frequency response of LASER interferometer gravitational wave detectors

    NASA Astrophysics Data System (ADS)

    Butler, William E.

    This thesis describes a search for a stochastic background of gravitational waves at high frequency, 37.52 kHz. At this frequency the separation between the available instruments excludes the use of a correlation technique. Instead I rely on the spectral response of the LASER interferometer to isolate a possible signal from the underlying noise. This research was carried out at the LIGO (LASER Interferometer Gravitational Observatory) located in Hanford, WA and within the LIGO Scientific Collaboration (LSC). Chapter 1 serves as a general introduction to the present state of the search for gravitational waves (GW). I discuss the indirect observation of gravitational radiation as well as the expected sources for GW and their characteristics. I also discuss possible future developments, in particular the Advanced LIGO instruments and the LASER Interferometer Space Antenna (LISA). The characteristics of the large LASER interferometers, layout, terminology and necessary formulae are developed in Chapter 2. To carry out the proposed search it is essential that the frequency response of the interferometer be thoroughly understood, including possible noise sources. This was the subject of a series of experimental investigations using sideband injection and mirror excitations to characterize the IFO response in the region of the first free spectral range, which is at 37.52 kHz. The results of these experiments as well as their theoretical model are presented in Chapter 3. Contributions to the spectrum from mechanical noise are investigated in Chapter 4, and compared to the expected contribution thermal excitation. The results of my search are based on data obtained during the third science run of LIGO (S3) and are presented in Chapter 5. I show that a signal such as expected from a stochastic gravitational wave background is manifest in the data and compare it to the expected noise signal. This allows me to postulate a limit on a possible stochastic background. I also

  20. Theory and experiment in gravitational physics

    NASA Technical Reports Server (NTRS)

    Will, C. M.

    1981-01-01

    New technological advances have made it feasible to conduct measurements with precision levels which are suitable for experimental tests of the theory of general relativity. This book has been designed to fill a new need for a complete treatment of techniques for analyzing gravitation theory and experience. The Einstein equivalence principle and the foundations of gravitation theory are considered, taking into account the Dicke framework, basic criteria for the viability of a gravitation theory, experimental tests of the Einstein equivalence principle, Schiff's conjecture, and a model theory devised by Lightman and Lee (1973). Gravitation as a geometric phenomenon is considered along with the parametrized post-Newtonian formalism, the classical tests, tests of the strong equivalence principle, gravitational radiation as a tool for testing relativistic gravity, the binary pulsar, and cosmological tests.

  1. Gravitational wave emission from oscillating millisecond pulsars

    NASA Astrophysics Data System (ADS)

    Alford, Mark G.; Schwenzer, Kai

    2015-02-01

    Neutron stars undergoing r-mode oscillation emit gravitational radiation that might be detected on the Earth. For known millisecond pulsars the observed spin-down rate imposes an upper limit on the possible gravitational wave signal of these sources. Taking into account the physics of r-mode evolution, we show that only sources spinning at frequencies above a few hundred Hertz can be unstable to r-modes, and we derive a more stringent universal r-mode spin-down limit on their gravitational wave signal. We find that this refined bound limits the gravitational wave strain from millisecond pulsars to values below the detection sensitivity of next generation detectors. Young sources are therefore a more promising option for the detection of gravitational waves emitted by r-modes and to probe the interior composition of compact stars in the near future.

  2. Low-Frequency Gravitational-Wave Science with eLISA/ NGO

    NASA Technical Reports Server (NTRS)

    Amaro-Seoane, Pau; Aoudia, Sofiane; Babak, Stanislav; Binetruy, Pierre; Berti, Emanuele; Bohe, Alejandro; Caprini, Chiara; Colpi, Monica; Cornish, Neil J.; Danzmann, Karsten; Dufaux, Jean-Francois; Gair, Jonathan; Jennrich, Oliver; Jetzer, Philippe; Klein, Antoine; Lang, Ryan N.; Lobo, Alberto; Littenberg, Tyson; McWilliams, Sean T.; Nelemans, Gijs; Petiteau, Antoine; Porter, Edward K.; Schutz, Bernard F.; Stebbins, Robin; Vallisneri, Michele

    2011-01-01

    We review the expected science performance of the New Gravitational-Wave Observatory (NGO, a.k.a. eLISA), a mission under study by the European Space Agency for launch in the early 2020s. eLISA will survey the low-frequency gravitational-wave sky (from 0.1 mHz to 1 Hz), detecting and characterizing a broad variety of systems and events throughout the Universe, including the coalescences of massive black holes brought together by galaxy mergers; the inspirals of stellar-mass black holes and compact stars into central galactic black holes; several millions of ultracompact binaries, both detached and mass transferring, in the Galaxy; and possibly unforeseen sources such as the relic gravitational-wave radiation from the early Universe. eLISA's high signal-to-noise measurements will provide new insight into the structure and history of the Universe, and they will test general relativity in its strong-field dynamical regime.

  3. Low-frequency gravitational-wave science with eLISA/NGO

    NASA Astrophysics Data System (ADS)

    Amaro-Seoane, Pau; Aoudia, Sofiane; Babak, Stanislav; Binétruy, Pierre; Berti, Emanuele; Bohé, Alejandro; Caprini, Chiara; Colpi, Monica; Cornish, Neil J.; Danzmann, Karsten; Dufaux, Jean-François; Gair, Jonathan; Jennrich, Oliver; Jetzer, Philippe; Klein, Antoine; Lang, Ryan N.; Lobo, Alberto; Littenberg, Tyson; McWilliams, Sean T.; Nelemans, Gijs; Petiteau, Antoine; Porter, Edward K.; Schutz, Bernard F.; Sesana, Alberto; Stebbins, Robin; Sumner, Tim; Vallisneri, Michele; Vitale, Stefano; Volonteri, Marta; Ward, Henry

    2012-06-01

    We review the expected science performance of the New Gravitational-Wave Observatory (NGO, a.k.a. eLISA), a mission under study by the European Space Agency for launch in the early 2020s. eLISA will survey the low-frequency gravitational-wave sky (from 0.1 mHz to 1 Hz), detecting and characterizing a broad variety of systems and events throughout the Universe, including the coalescences of massive black holes brought together by galaxy mergers; the inspirals of stellar-mass black holes and compact stars into central galactic black holes; several millions of ultra-compact binaries, both detached and mass transferring, in the Galaxy; and possibly unforeseen sources such as the relic gravitational-wave radiation from the early Universe. eLISA’s high signal-to-noise measurements will provide new insight into the structure and history of the Universe, and they will test general relativity in its strong-field dynamical regime.

  4. Gravitational lens time delays and gravitational waves

    SciTech Connect

    Frieman, J.A. Department of Astronomy Astrophysics, University of Chicago, Chicago, Illinois 60637 ); Harari, D.D.; Surpi, G.C. )

    1994-10-15

    Using Fermat's principle, we analyze the effects of very long wavelength gravitational waves upon the images of a gravitationally lensed quasar. We show that the lens equation in the presence of gravity waves is equivalent to that of a lens with a different alignment between source, deflector, and observer in the absence of gravity waves. Contrary to a recent claim, we conclude that measurements of time delays in gravitational lenses cannot serve as a method to detect or constrain a stochastic background of gravitational waves of cosmological wavelengths, because the wave-induced time delay is observationally indistinguishable from an intrinsic time delay due to the lens geometry.

  5. Creating Griffith Observatory

    NASA Astrophysics Data System (ADS)

    Cook, Anthony

    2013-01-01

    Griffith Observatory has been the iconic symbol of the sky for southern California since it began its public mission on May 15, 1935. While the Observatory is widely known as being the gift of Col. Griffith J. Griffith (1850-1919), the story of how Griffith’s gift became reality involves many of the people better known for other contributions that made Los Angeles area an important center of astrophysics in the 20th century. Griffith began drawing up his plans for an observatory and science museum for the people of Los Angeles after looking at Saturn through the newly completed 60-inch reflector on Mt. Wilson. He realized the social impact that viewing the heavens could have if made freely available, and discussing the idea of a public observatory with Mt. Wilson Observatory’s founder, George Ellery Hale, and Director, Walter Adams. This resulted, in 1916, in a will specifying many of the features of Griffith Observatory, and establishing a committee managed trust fund to build it. Astronomy popularizer Mars Baumgardt convinced the committee at the Zeiss Planetarium projector would be appropriate for Griffith’s project after the planetarium was introduced in Germany in 1923. In 1930, the trust committee judged funds to be sufficient to start work on creating Griffith Observatory, and letters from the Committee requesting help in realizing the project were sent to Hale, Adams, Robert Millikan, and other area experts then engaged in creating the 200-inch telescope eventually destined for Palomar Mountain. A Scientific Advisory Committee, headed by Millikan, recommended that Caltech Physicist Edward Kurth be put in charge of building and exhibit design. Kurth, in turn, sought help from artist Russell Porter. The architecture firm of John C. Austin and Fredrick Ashley was selected to design the project, and they adopted the designs of Porter and Kurth. Philip Fox of the Adler Planetarium was enlisted to manage the completion of the Observatory and become its

  6. Binary Black Holes and Gravitational Waves

    NASA Technical Reports Server (NTRS)

    Centrella, Joan

    2007-01-01

    The final merger of two black holes releases a tremendous amount of energy, more than the combined light from all the stars in the visible universe. This energy is emitted in the form of gravitational waves, and observing these sources with gravitational wave detectors such as LIGO and LISA requires that we know the pattern or fingerprint of the radiation emitted. Since black hole mergers take place in regions of extreme gravitational fields, we need to solve Einstein's equations of general relativity on a computer in order to calculate these wave patterns.

  7. The pregalactic cosmic gravitational wave background

    NASA Technical Reports Server (NTRS)

    Matzner, Richard A.

    1989-01-01

    An outline is given that estimates the expected gravitational wave background, based on plausible pregalactic sources. Some cosmologically significant limits can be put on incoherent gravitational wave background arising from pregalactic cosmic evolution. The spectral region of cosmically generated and cosmically limited radiation is, at long periods, P greater than 1 year, in contrast to more recent cosmological sources, which have P approx. 10 to 10(exp -3).

  8. Phase transition dynamics and gravitational waves

    SciTech Connect

    Megevand, Ariel

    2009-04-20

    During a first-order phase transition, gravitational radiation is generated either by bubble collisions or by turbulence. For phase transitions which took place at the electroweak scale and beyond, the signal is expected to be within the sensitivity range of planned interferometers such as LISA or BBO. We review the generation of gravitational waves in a first-order phase transition and discuss the dependence of the spectrum on the dynamics of the phase transition.

  9. Everyday astronomy @ Sydney Observatory

    NASA Astrophysics Data System (ADS)

    Parello, S. L.

    2008-06-01

    Catering to a broad range of audiences, including many non-English speaking visitors, Sydney Observatory offers everything from school programmes to public sessions, day care activities to night observing, personal interactions to web-based outreach. With a history of nearly 150 years of watching the heavens, Sydney Observatory is now engaged in sharing the wonder with everybody in traditional and innovative ways. Along with time-honoured tours of the sky through two main telescopes, as well as a small planetarium, Sydney Observatory also boasts a 3D theatre, and offers programmes 363 days a year - rain or shine, day and night. Additionally, our website neversleeps, with a blog, YouTube videos, and night sky watching podcasts. And for good measure, a sprinkling of special events such as the incomparable Festival of the Stars, for which most of northern Sydney turns out their lights. Sydney Observatory is the oldest working observatory in Australia, and we're thrilled to be looking forward to our 150th Anniversary next year in anticipation of the International Year of Astronomy immediately thereafter.

  10. Gravitational waves from self-ordering scalar fields

    SciTech Connect

    Fenu, Elisa; Durrer, Ruth; Figueroa, Daniel G.; García-Bellido, Juan E-mail: daniel.figueroa@uam.es E-mail: juan.garciabellido@uam.es

    2009-10-01

    Gravitational waves were copiously produced in the early Universe whenever the processes taking place were sufficiently violent. The spectra of several of these gravitational wave backgrounds on subhorizon scales have been extensively studied in the literature. In this paper we analyze the shape and amplitude of the gravitational wave spectrum on scales which are superhorizon at the time of production. Such gravitational waves are expected from the self ordering of randomly oriented scalar fields which can be present during a thermal phase transition or during preheating after hybrid inflation. We find that, if the gravitational wave source acts only during a small fraction of the Hubble time, the gravitational wave spectrum at frequencies lower than the expansion rate at the time of production behaves as Ω{sub GW}(f) ∝ f{sup 3} with an amplitude much too small to be observable by gravitational wave observatories like LIGO, LISA or BBO. On the other hand, if the source is active for a much longer time, until a given mode which is initially superhorizon (kη{sub *} << 1), enters the horizon, for kη ∼> 1, we find that the gravitational wave energy density is frequency independent, i.e. scale invariant. Moreover, its amplitude for a GUT scale scenario turns out to be within the range and sensitivity of BBO and marginally detectable by LIGO and LISA. This new gravitational wave background can compete with the one generated during inflation, and distinguishing both may require extra information.

  11. Earth Atmosphere Observatory Formation at L2

    NASA Technical Reports Server (NTRS)

    Mettler, Edward; Acikmese, A. Behcet; Breckenridge, William G.; Mecenka, Steven A.; Tubbs, Eldred F.

    2004-01-01

    This paper is a product of research supported by NASA under RASC (the Revolutionary Aerospace Systems Concepts) program. It presents an overall system architecture, and covers issues of deployment, navigation, and control related to a formation of two spacecraft in the neighborhood of the Sun-Earth L2 Lagrange point (on the Sun-Earth line), that serves as an observatory of Earth's atmosphere. The observatory concept definition study was a multi-center NASA effort conducted in 2003, and covered a much wider scope than is presented in this focused paper.The Earth observatory at L2 is a unique design concept that can improve the knowledge and understanding of dynamic, chemical and radiative mechanisms that cause changes in the atmosphere, and can lead to the development of models and techniques to predict short and long-term climate changes.

  12. Swift Observatory Space Simulation Testing

    NASA Technical Reports Server (NTRS)

    Espiritu, Mellina; Choi, Michael K.; Scocik, Christopher S.

    2004-01-01

    The Swift Observatory is a Middle-Class Explorer (MIDEX) mission that is a rapidly re-pointing spacecraft with immediate data distribution capability to the astronomical community. Its primary objectives are to characterize and determine the origin of Gamma Ray Bursts (GRBs) and to use the collected data on GRB phenomena in order to probe the universe and gain insight into the physics of black hole formation and early universe. The main components of the spacecraft are the Burst Alert Telescope (BAT), Ultraviolet and Optical Telescope (UVOT), X-Ray Telescope (XRT), and Optical Bench (OB) instruments coupled with the Swift spacecraft (S/C) bus. The Swift Observatory will be tested at the Space Environment Simulation (SES) chamber at the Goddard Space Flight Center from May to June 2004 in order to characterize its thermal behavior in a vacuum environment. In order to simulate the independent thermal zones required by the BAT, XRT, UVOT, and OB instruments, the spacecraft is mounted on a chariot structure capable of maintaining adiabatic interfaces and enclosed in a modified, four section MSX fixture in order to accommodate the strategic placement of seven cryopanels (on four circuits), four heater panels, and a radiation source burst simulator mechanism. There are additionally 55 heater circuits on the spacecraft. To mitigate possible migration of silicone contaminants from BAT to the XRT and UVOT instruments, a contamination enclosure is to be fabricated around the BAT at the uppermost section of the MSX fixture. This paper discuses the test requirements and implemented thermal vacuum test configuration for the Swift Observatory.

  13. The International X-ray Observatory

    NASA Technical Reports Server (NTRS)

    Hornschemeier, A.

    2009-01-01

    The International X-Ray Observatory, a joint NASA-ESA-JAXA effort, is a next generation X-ray telescope that will answer many fundamental questions in contemporary astrophysics such as how do supermassive black holes influence galaxy evolution and how do galaxy clusters evolve (and how does this constrain dark energy and dark matter)? As a powerful astronomical observatory, IXO will also address questions ranging from the neutron star equation of state to the distribution and dynamical state of intergalactic material. X-ray spectroscopy, polarimetry, and timing studies provided by IXO's instruments will give detailed measures of abundances, temperatures, densities, magnetic fields and gravitational potentials. These measurements will be complementary to the next generation of observatories such as ALMA, JWST, and future ground-based optical-NIR telescopes. This mission will be ready for launch in the 2020-2021 timeframe and will launch on an Atlas V or Ariane V launch vehicle to L2. It employs a deployable optical bench to achieve the 20 meter focal length and a suite of five instruments. This talk will describe the motivating science for this mission as well as the spacecraft, instruments and optics

  14. High Energy Astronomy Observatory (HEAO)-2

    NASA Technical Reports Server (NTRS)

    1975-01-01

    This illustration is a schematic of the High Energy Astronomy Observatory (HEAO)-2 and its experiments. It shows the focal plane instruments (at the right) plus the associated electronics for operating the telescope as it transmitted its observations to the ground. A fifth instrument, the Monitor Proportional Counter, is located near the front of the telescope. Four separate astronomical instruments are located at the focus of this telescope and they could be interchanged for different types of observations as the observatory pointed at interesting areas of the Sky. Two of these instruments produced images; a High Resolution Imaging Detector and an Imaging Proportional Counter. The other two instruments, the Solid State Spectrometer and the Crystal Spectrometer, measured the spectra of x-ray objects. A fifth instrument, the Monitor Proportional Counter, continuously viewed space independently to study a wider band of x-ray wavelengths and to examine the rapid time variations in the sources. The HEAO-2 was nicknamed the Einstein Observatory by its scientific experimenters in honor of the centernial of the birth of Albert Einstein, whose concepts of relativity and gravitation have influenced much of modern astrophysics, particularly x-ray astronomy. The HEAO-2, designed and developed by TRW, Inc. under the project management of the Marshall Space Flight Center, was launched aboard an Atlas/Centaur launch vehicle on November 13, 1978. The HEAO-2 was originally identified as HEAO-B but the designation was changed once the spacecraft achieved orbit.

  15. 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.

  16. Combustion at reduced gravitational conditions

    NASA Technical Reports Server (NTRS)

    Berlad, A. L.; Wang, L. S.; Joshi, N.; Pai, C. I.

    1980-01-01

    The theoretical structures needed for the predictive analyses and interpretations for flame propagation and extinction for clouds of porous particulates are presented. Related combustion theories of significance to reduced gravitational studies of combustible media are presented. Nonadiabatic boundaries are required for both autoignition theory and for extinction theory. Processes that were considered include, pyrolysis and vaporization of particulates, heterogeneous and homogeneous chemical kinetics, molecular transport of heat and mass, radiative coupling of the medium to its environment, and radiative coupling among particles and volume elements of the combustible medium.

  17. WFIRST Observatory Performance

    NASA Technical Reports Server (NTRS)

    Kruk, Jeffrey W.

    2012-01-01

    The WFIRST observatory will be a powerful and flexible wide-field near-infrared facility. The planned surveys will provide data applicable to an enormous variety of astrophysical science. This presentation will provide a description of the observatory and its performance characteristics. This will include a discussion of the point spread function, signal-to-noise budgets for representative observing scenarios and the corresponding limiting sensitivity. Emphasis will be given to providing prospective Guest Observers with information needed to begin thinking about new observing programs.

  18. Yellowstone Volcano Observatory

    USGS Publications Warehouse

    Venezky, Dina Y.; Lowenstern, Jacob

    2008-01-01

    Eruption of Yellowstone's Old Faithful Geyser. Yellowstone hosts the world's largest and most diverse collection of natural thermal features, which are the surface expression of magmatic heat at shallow depths in the crust. The Yellowstone system is monitored by the Yellowstone Volcano Observatory (YVO), a partnership among the U.S. Geological Survey (USGS), Yellowstone National Park, and the University of Utah. YVO is one of five USGS Volcano Hazards Program observatories that monitor U.S. volcanoes for science and public safety. Learn more about Yellowstone and YVO at http://volcanoes.usgs.gov/yvo.

  19. 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…

  20. Detecting stochastic backgrounds of gravitational waves with pulsar timing arrays

    NASA Astrophysics Data System (ADS)

    Siemens, Xavier

    2016-03-01

    For the past decade the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) has been using the Green Bank Telescope and the Arecibo Observatory to monitor millisecond pulsars. NANOGrav, along with two other international collaborations, the European Pulsar Timing Array and the Parkes Pulsar Timing Array in Australia, form a consortium of consortia: the International Pulsar Timing Array (IPTA). The goal of the IPTA is to directly detect low-frequency gravitational waves which cause small changes to the times of arrival of radio pulses from millisecond pulsars. In this talk I will discuss the work of NANOGrav and the IPTA, as well as our sensitivity to stochastic backgrounds of gravitational waves. I will show that a detection of the background produced by supermassive black hole binaries is possible by the end of the decade. Supported by the NANOGrav Physics Frontiers Center.

  1. Torun Radio Astronomy Observatory

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    Torun Center for Astronomy is located at Piwnice, 15 km north of Torun, Poland. A part of the Faculty of Physics and Astronomy of the Nicolaus Copernicus University, it was created by the union of Torun Radio Astronomy Observatory (TRAO) and the Institute of Astronomy on 1 January 1997....

  2. Strasbourg's "First" astronomical observatory

    NASA Astrophysics Data System (ADS)

    Heck, André

    2011-08-01

    The turret lantern located at the top of the Strasbourg Hospital Gate is generally considered as the first astronomical observatory of the city, but such a qualification must be treated with caution. The thesis of this paper is that the idea of a tower-observatory was brought back by a local scholar, Julius Reichelt (1637-1717), after he made a trip to Northern Europe around 1666 and saw the "Rundetårn" (Round Tower) recently completed in Copenhagen. There, however, a terrace allowed (and still allows) the full viewing of the sky, and especially of the zenith area where the atmospheric transparency is best. However, there is no such terrace in Strasbourg around the Hospital Gate lantern. Reichelt had also visited Johannes Hevelius who was then developing advanced observational astronomy in Gdansk, but nothing of the kind followed in Strasbourg. Rather, the Hospital Gate observatory was built essentially for the prestige of the city and for the notoriety of the university, and the users of this observing post did not make any significant contributions to the progress of astronomical knowledge. We conclude that the Hospital Gate observatory was only used for rudimentary viewing of bright celestial objects or phenomena relatively low on the horizon.

  3. Armenian Virtual Observatory

    NASA Astrophysics Data System (ADS)

    Mickaelian, A. M.

    2015-07-01

    Vast amount of information continuously accumulated in astronomy requires finding new solutions for its efficient storage, use and dissemination, as well as accomplishing new research projects. Virtual Observatories (VOs) have been created in a number of countries to set up a new environment for these tasks. Based on them, the International Virtual Observatory Alliance (IVOA) was created in 2002, which unifies 19 VO projects, including Armenian Virtual Observatory (ArVO) founded in 2005. ArVO is a project of Byurakan Astrophysical Observatory (BAO) aimed at construction of a modern system for data archiving, extraction, acquisition, reduction, use and publication. ArVO technical and research projects are presented, including the Global Spectroscopic Database, which is being built based on Digitized First Byurakan Survey (DFBS). Quick optical identification of radio, IR or X-ray sources will be possible by plotting their positions in the DFBS or other spectroscopic plate and matching all available data. Accomplishment of new projects by combining data is so important that the International Council of Scientific Unions (ICSU) recently created World Data System (WDS) for unifying data coming from all science areas, and BAO has also joined it.

  4. High Energy Astronomy Observatory

    NASA Technical Reports Server (NTRS)

    1980-01-01

    An overview of the High Energy Astronomy Observatory 2 contributions to X-ray astronomy is presented along with a brief description of the satellite and onboard telescope. Observations relating to galaxies and galactic clusters, black holes, supernova remnants, quasars, and cosmology are discussed.

  5. Poznan acute Astronomical Observatory

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    This Poznan acute Astronomical Observatory is a unit of the Adam Mickiewicz University, located in Poznan acute, Poland. From its foundation in 1919, it has specialized in astrometry and celestial mechanics (reference frames, dynamics of satellites and small solar system bodies). Recently, research activities have also included planetary and stellar astrophysics (asteroid photometry, catalysmic b...

  6. Arecibo Observatory for All

    ERIC Educational Resources Information Center

    Bartus, P.; Isidro, G. M.; La Rosa, C.; Pantoja, C. A.

    2007-01-01

    We describe new materials available at the Arecibo Observatory for visitors with visual impairments. These materials include a guide in Braille that describes the telescope, explains some basic terms used in radio astronomy, and lists frequently asked questions. We have also designed a tactile model of the telescope. Our interest is in enabling…

  7. Gravitational-wave Mission Study

    NASA Technical Reports Server (NTRS)

    Mcnamara, Paul; Jennrich, Oliver; Stebbins, Robin T.

    2014-01-01

    In November 2013, ESA selected the science theme, the "Gravitational Universe," for its third large mission opportunity, known as L3, under its Cosmic Vision Programme. The planned launch date is 2034. ESA is considering a 20% participation by an international partner, and NASA's Astrophysics Division has indicated an interest in participating. We have studied the design consequences of a NASA contribution, evaluated the science benefits and identified the technology requirements for hardware that could be delivered by NASA. The European community proposed a strawman mission concept, called eLISA, having two measurement arms, derived from the well studied LISA (Laser Interferometer Space Antenna) concept. The US community is promoting a mission concept known as SGO Mid (Space-based Gravitational-wave Observatory Mid-sized), a three arm LISA-like concept. If NASA were to partner with ESA, the eLISA concept could be transformed to SGO Mid by the addition of a third arm, augmenting science, reducing risk and reducing non-recurring engineering costs. The characteristics of the mission concepts and the relative science performance of eLISA, SGO Mid and LISA are described. Note that all results are based on models, methods and assumptions used in NASA studies

  8. Gravitational Wave Propulsion

    NASA Astrophysics Data System (ADS)

    Fontana, Giorgio

    2005-02-01

    There is only one experimental proof that gravitational waves exist. With such a limitation, it may seem premature to suggest the possibility that gravitational waves can became a preferred space propulsion technique. The present understanding of the problem indicates that this is not the case. The emission of gravitational waves from astrophysical sources has been confirmed by observation, the respective detection at large distance from the source is difficult and actually we have no confirmation of a successful detection. Therefore the required preliminary discovery has been already made. This opinion is enforced by many different proposals for building the required powerful gravitational wave generators that have recently appeared in the literature and discussed at conferences. It is no longer reasonable to wait for additional confirmation of the existence of gravitational waves to start a program for building generators and testing their possible application to space travel. A vast literature shows that gravitational waves can be employed for space propulsion. Gravitational wave rockets have been proposed, non-linearity of Einstein equations allows the conversion of gravitational waves to a static gravitational field and ``artificial gravity assist'' may become a new way of travelling in space-time. Different approaches to gravitational wave propulsion are reviewed and compared. Gravitational wave propulsion is also compared to traditional rocket propulsion and an undeniable advantage can be demonstrated in terms of efficiency and performance. Testing the predictions will require gravitational wave generators with high power and wavelength short enough for producing high energy densities. Detectors designed for the specific application must be developed, taking into account that non-linearity effects are expected. The study and development of Gravitational wave propulsion is a very challenging endeavor, involving the most complex theories, sophisticated

  9. Gravitational wave astronomy - astronomy of the 21st century

    NASA Astrophysics Data System (ADS)

    Dhurandhar, S. V.

    2011-03-01

    An enigmatic prediction of Einstein's general theory of relativity is gravitational waves. With the observed decay in the orbit of the Hulse-Taylor binary pulsar agreeing within a fraction of a percent with the theoretically computed decay from Einstein's theory, the existence of gravitational waves was firmly established. Currently there is a worldwide effort to detect gravitational waves with inteferometric gravitational wave observatories or detectors and several such detectors have been built or being built. The initial detectors have reached their design sensitivities and now the effort is on to construct advanced detectors which are expected to detect gravitational waves from astrophysical sources. The era of gravitational wave astronomy has arrived. This article describes the worldwide effort which includes the effort on the Indian front - the IndIGO project -, the principle underlying interferometric detectors both on ground and in space, the principal noise sources that plague such detectors, the astrophysical sources of gravitational waves that one expects to detect by these detectors and some glimpse of the data analysis methods involved in extracting the very weak gravitational wave signals from detector noise.

  10. Gravitational wave astronomy-- astronomy of the 21st century

    NASA Astrophysics Data System (ADS)

    Dhurandhar, S. V.

    2011-12-01

    An enigmatic prediction of Einstein's general theory of relativity is gravitational waves. With the observed decay in the orbit of the Hulse-Taylor binary pulsar agreeing within a fraction of a percent with the theoretically computed decay from Einstein's theory, the existence of gravitational waves was firmly established. Currently there is a worldwide effort to detect gravitational waves with inteferometric gravitational wave observatories or detectors and several such detectors have been built or are being built. The initial detectors have reached their design sensitivities and now the effort is on to construct advanced detectors which are expected to detect gravitational waves from astrophysical sources. The era of gravitational wave astronomy has arrived. This article describes the worldwide effort which includes the effort on the Indian front-- the IndIGO project --, the principle underlying interferometric detectors both on ground and in space, the principal noise sources that plague such detectors, the astrophysical sources of gravitational waves that one expects to detect by these detectors and some glimpse of the data analysis methods involved in extracting the very weak gravitational wave signals from detector noise.

  11. Gravitational waves from perturbed stars

    NASA Astrophysics Data System (ADS)

    Ferrari, V.

    2011-12-01

    Non radial oscillations of neutron stars are associated with the emission of gravitational waves. The characteristic frequencies of these oscillations can be computed using the theory of stellar perturbations, and they are shown to carry detailed information on the internal structure of the emitting source. Moreover, they appear to be encoded in various radiative processes, as for instance, in the tail of the giant flares of Soft Gamma Repeaters. Thus, their determination is central to the theory of stellar perturbation. A viable approach to the problem consists in formulating this theory as a problem of resonant scattering of gravitational waves incident on the potential barrier generated by the spacetime curvature. This approach discloses some unexpected correspondences between the theory of stellar perturbations and the theory of quantum mechanics, and allows us to predict new relativistic effects.

  12. Gravitational waves from perturbed stars

    NASA Astrophysics Data System (ADS)

    Ferrari, V.

    2011-03-01

    Non radial oscillations of neutron stars are associated with the emission of gravitational waves. The characteristic frequencies of these oscillations can be computed using the theory of stellar perturbations, and they are shown to carry detailed information on the internal structure of the emitting source. Moreover, they appear to be encoded in various radiative processes, as for instance in the tail of the giant flares of Soft Gamma Repeaters. Thus, their determination is central to the theory of stellar perturbation. A viable approach to the problem consists in formulating this theory as a problem of resonant scattering of gravitational waves incident on the potential barrier generated by the spacetime curvature. This approach discloses some unexpected correspondences between the theory of stellar perturbations and the theory of quantum mechanics, and allows us to predict new relativistic effects.

  13. Post-Newtonian gravitational bremsstrahlung

    NASA Technical Reports Server (NTRS)

    Turner, M.; Will, C. M.

    1977-01-01

    Formulae and numerical results are presented for the gravitational radiation emitted during a low-deflection encounter between two massive bodies. Results are valid through post-Newtonian order within general relativity. The gravitational waveform, the total luminosity and total emitted energy, the angular distribution of emitted energy, and the frequency spectrum are discussed in detail. A method boosting the accuracy of these quantities to post Newtonian order is also presented. A numerical comparison of results with those of Peters, and of Kovacs and Thorne shows that the post Newtonian method is reliable to better than 0.1 percent at v = 0.1 c, to a few percent at v = 0.35 c, and to 10 to 20 percent at v = 0.5 c.

  14. From Measure Zero to Measure Hero: Periodic Kerr Orbits and Gravitational Wave Physics

    NASA Astrophysics Data System (ADS)

    Perez-Giz, Gabriel

    2011-12-01

    A direct observational detection of gravitational waves -- perhaps the most fundamental prediction of a theory of curved spacetime -- looms close at hand. Stellar mass compact objects spiraling into supermassive black holes have received particular attention as sources of gravitational waves detectable by space-based gravitational wave observatories. A well-established approach models such an extreme mass ratio inspirals (EMRI) as an adiabatic progression through a series of Kerr geodesics. Thus, the direct detection of gravitational radiation from EMRIs and the extraction of astrophysical information from those waveforms require a thorough knowledge of the underlying geodesic dynamics. This dissertation adopts a dynamical systems approach to the study of Kerr orbits, beginning with equatorial orbits. We deduce a topological taxonomy of orbits that hinges on a correspondence between periodic orbits and rational numbers. The taxonomy defines the entire dynamics, including aperiodic motion, since every orbit is in or near the periodic set. A remarkable implication of this periodic orbit taxonomy is that the simple precessing ellipse familiar from planetary orbits is not allowed in the strong-field regime. Instead, eccentric orbits trace out precessions of multi-leaf clovers in the final stages of inspiral. Furthermore, for any black hole, there is some orbital angular momentum value in the strong-field regime below which zoom-whirl behavior becomes unavoidable. We then generalize the taxonomy to help identify nonequatorial orbits whose radial and polar frequencies are rationally related, or in resonance. The thesis culminates by describing how those resonant orbits can be leveraged for an order of magnitude or more reduction in the computational cost of adiabatic order EMRI trajectories, which are so prohibitively expensive that no such relativistically correct inspirals have been generated to date.

  15. NASA's Great Observatories: Paper Model.

    ERIC Educational Resources Information Center

    National Aeronautics and Space Administration, Washington, DC.

    This educational brief discusses observatory stations built by the National Aeronautics and Space Administration (NASA) for looking at the universe. This activity for grades 5-12 has students build paper models of the observatories and study their history, features, and functions. Templates for the observatories are included. (MVL)

  16. ESO's Two Observatories Merge

    NASA Astrophysics Data System (ADS)

    2005-02-01

    On February 1, 2005, the European Southern Observatory (ESO) has merged its two observatories, La Silla and Paranal, into one. This move will help Europe's prime organisation for astronomy to better manage its many and diverse projects by deploying available resources more efficiently where and when they are needed. The merged observatory will be known as the La Silla Paranal Observatory. Catherine Cesarsky, ESO's Director General, comments the new development: "The merging, which was planned during the past year with the deep involvement of all the staff, has created unified maintenance and engineering (including software, mechanics, electronics and optics) departments across the two sites, further increasing the already very high efficiency of our telescopes. It is my great pleasure to commend the excellent work of Jorge Melnick, former director of the La Silla Observatory, and of Roberto Gilmozzi, the director of Paranal." ESO's headquarters are located in Garching, in the vicinity of Munich (Bavaria, Germany), and this intergovernmental organisation has established itself as a world-leader in astronomy. Created in 1962, ESO is now supported by eleven member states (Belgium, Denmark, Finland, France, Germany, Italy, The Netherlands, Portugal, Sweden, Switzerland, and the United Kingdom). It operates major telescopes on two remote sites, all located in Chile: La Silla, about 600 km north of Santiago and at an altitude of 2400m; Paranal, a 2600m high mountain in the Atacama Desert 120 km south of the coastal city of Antofagasta. Most recently, ESO has started the construction of an observatory at Chajnantor, a 5000m high site, also in the Atacama Desert. La Silla, north of the town of La Serena, has been the bastion of the organization's facilities since 1964. It is the site of two of the most productive 4-m class telescopes in the world, the New Technology Telescope (NTT) - the first major telescope equipped with active optics - and the 3.6-m, which hosts HARPS

  17. 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

  18. Alaska Volcano Observatory

    USGS Publications Warehouse

    Venezky, Dina Y.; Murray, Tom; Read, Cyrus

    2008-01-01

    Steam plume from the 2006 eruption of Augustine volcano in Cook Inlet, Alaska. Explosive ash-producing eruptions from Alaska's 40+ historically active volcanoes pose hazards to aviation, including commercial aircraft flying the busy North Pacific routes between North America and Asia. The Alaska Volcano Observatory (AVO) monitors these volcanoes to provide forecasts of eruptive activity. AVO is a joint program of the U.S. Geological Survey (USGS), the Geophysical Institute of the University of Alaska Fairbanks (UAFGI), and the State of Alaska Division of Geological and Geophysical Surveys (ADGGS). AVO is one of five USGS Volcano Hazards Program observatories that monitor U.S. volcanoes for science and public safety. Learn more about Augustine volcano and AVO at http://www.avo.alaska.edu.

  19. Mount Wilson Observatory

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    Mount Wilson Observatory, located in the San Gabriel Mountains near Pasadena, California, was founded in 1904 by George Ellery Hale with financial support from Andrew Carnegie. In the 1920s and 1930s, working at the 2.5 m Hooker telescope, Edwin Hubble made two of the most important discoveries in the history of astronomy: first, that `nebulae' are actually island universes—galaxies—each with bil...

  20. Arcetri Astrophysical Observatory

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    The Arcetri Astrophysical Observatory, a government research institute founded in 1972, is located close to the villa where Galileo spent the last 11 years of his life. Under the directorship of Giorgio Abetti (1921-53) it became the growth point of Italian astrophysics with emphasis on solar physics; a tradition continued by his successor Guglielmo Righini (1953-78). Since 1978 the activities ha...

  1. Megalithic observatory Kokino

    NASA Astrophysics Data System (ADS)

    Cenev, Gj.

    2006-05-01

    In 2001, on the footpath of a mountain peak, near the village of Kokino, archeologist Jovica Stankovski discovered an archeological site from The Bronze Age. The site occupies a large area and is scaled in two levels. Several stone seats (thrones) are dominant in this site and they are pointing towards the east horizon. The high concentration of the movable archeological material found on the upper platform probably indicates its use in a function containing still unknown cult activities. Due to precise measurements and a detailed archaeoastronomical analysis of the site performed in the past three years by Gjore Cenev, physicist from the Planetarium in Skopje, it was shown that the site has characteristics of a sacred site, but also of a Megalithic Observatory. The markers found in this observatory point on the summer and winter solstices and spring and autumn equinoxes. It can be seen that on both sides of the solstice markers, that there are markers for establishing Moon's positions. The markers are crafted in such a way that for example on days when special rites were performed (harvest rites for example) the Sun filled a narrow space of the marker and special ray lighted the man sitting on only one of the thrones, which of course had a special meaning. According to the positions of the markers that are used for Sun marking, especially on the solstice days, it was calculated that this observatory dates from 1800 B.C.

  2. Sierra Remote Observatories

    NASA Astrophysics Data System (ADS)

    Ringwald, Fred; Morgan, G. E.; Barnes, F. S., III; Goldman, D. S.; Helm, M. R.; Mortfield, P.; Quattrocchi, K. B.; Van Vleet, L.

    2009-05-01

    We report the founding of a new facility for astrophotography and small-telescope science. Sierra Remote Observatories are eight small observatories at 4610' altitude in the Sierra Nevada Mountains of California. The sky brightness during New Moon typically rates 3 on the Bortle scale. Typical seeing is 1.2", with a one-sigma range between 1.0" and 1.6", measured during 2007 June-September. All eight observatories are operated by remote control over the Internet, from as far away as Toronto and South Carolina. The telescopes range in aperture from 106 mm to 16 inches. Color images have so far been published in several magazines (Astronomy, Practical Astronomer, and Sky & Telescope) and on NASA's Astronomy Picture of the Day website. Science programs include time-resolved photometry of cataclysmic variables including the discovery of a 3.22-hour periodicity in the light curve of the nova-like V378 Pegasi, the serendipitous discovery of a previously undesignated spherical bubble in Cygnus, the discovery of three asteroids, and monitoring of Comet Lulin.

  3. The Russian Virtual Observatory

    NASA Astrophysics Data System (ADS)

    Dluzhnevskaya, O. B.; Malkov, O. Yu.; Kilpio, A. A.; Kilpio, E. Yu.; Kovaleva, D. A.; Sat, L. A.

    The Russian Virtual Observatory (RVO) will be an integral component of the International Virtual Observatory (IVO). The RVO has the main goal of integrating resources of astronomical data accumulated in Russian observatories and institutions (databases, archives, digitized glass libraries, bibliographic data, a remote access system to information and technical resources of telescopes etc.), and providing transparent access for scientific and educational purposes to the distributed information and data services that comprise its content. Another goal of the RVO is to provide Russian astronomers with on-line access to the rich volumes of data and metadata that have been, and will continue to be, produced by astronomical survey projects. Centre for Astronomical Data (CAD), among other Russian institutions, has had the greatest experience in collecting and distributing astronomical data for more than 20 years. Some hundreds of catalogs and journal tables are currently available from the CAD repository. More recently, mirrors of main astronomical data resources (VizieR, ADS, etc) are now maintained in CAD. Besides, CAD accumulates and makes available for the astronomical community information on principal Russian astronomical resources.

  4. Okayama astrophysical observatory wide field camera

    NASA Astrophysics Data System (ADS)

    Yanagisawa, Kenshi; Shimizu, Yasuhiro; Okita, Kiichi; Kuroda, Daisuke; Koyano, Hisashi; Tsutsui, Hironori; Toda, Hiroyuki; Izumiura, Hideyuki; Yoshida, Michitoshi; Ohta, Kouji; Kawai, Nobuyuki; Yamamuro, Tomoyasu

    2014-08-01

    Okayama Astrophysical Observatory Wide Field Camera: OAOWFC is a near-infrared (0.9-2.5 μm) survey telescope, whose aperture is 0.91m. It works at Y, J, H, and Ks bands. The optics are consisted of forward Cassegrain and quasi Schmidt which yield the image circle of Φ 52 mm or Φ 1.3 deg at the focal plane. The overall F-ratio is F/2.51 which is one of the fastest among near infrared imagers in the world. A HAWAII-1 detector array placed at the focal plane cuts the central 0.48 deg. x 0.48 deg. with a pixel scale of 1.67 arcsec/pix. It will be used to survey the Galactic plane for variability and search for transients such as Gamma-ray burst afterglows optical counterpart of gravitational wave sources.

  5. Gravitational waves from an early matter era

    SciTech Connect

    Assadullahi, Hooshyar; Wands, David

    2009-04-15

    We investigate the generation of gravitational waves due to the gravitational instability of primordial density perturbations in an early matter-dominated era which could be detectable by experiments such as laser interferometer gravitational wave observatory (LIGO) and laser interferometer space antenna (LISA). We use relativistic perturbation theory to give analytic estimates of the tensor perturbations generated at second order by linear density perturbations. We find that large enhancement factors with respect to the naive second-order estimate are possible due to the growth of density perturbations on sub-Hubble scales. However very large enhancement factors coincide with a breakdown of linear theory for density perturbations on small scales. To produce a primordial gravitational-wave background that would be detectable with LIGO or LISA from density perturbations in the linear regime requires primordial comoving curvature perturbations on small scales of order 0.02 for advanced LIGO or 0.005 for LISA; otherwise numerical calculations of the nonlinear evolution on sub-Hubble scales are required.

  6. Gravitational wave detector with cosmological reach

    NASA Astrophysics Data System (ADS)

    Dwyer, Sheila; Sigg, Daniel; Ballmer, Stefan W.; Barsotti, Lisa; Mavalvala, Nergis; Evans, Matthew

    2015-04-01

    Twenty years ago, construction began on the Laser Interferometer Gravitational-wave Observatory (LIGO). Advanced LIGO, with a factor of 10 better design sensitivity than Initial LIGO, will begin taking data this year, and should soon make detections a monthly occurrence. While Advanced LIGO promises to make first detections of gravitational waves from the nearby universe, an additional factor of 10 increase in sensitivity would put exciting science targets within reach by providing observations of binary black hole inspirals throughout most of the history of star formation, and high signal to noise observations of nearby events. Design studies for future detectors to date rely on significant technological advances that are futuristic and risky. In this paper we propose a different direction. We resurrect the idea of using longer arm lengths coupled with largely proven technologies. Since the major noise sources that limit gravitational wave detectors do not scale trivially with the length of the detector, we study their impact and find that 40 km arm lengths are nearly optimal, and can incorporate currently available technologies to detect gravitational wave sources at cosmological distances (z ≳7 ) .

  7. Virtual Energetic Particle Observatory (VEPO)

    NASA Technical Reports Server (NTRS)

    Cooper, John F.; Lal, Nand; McGuire, Robert E.; Szabo, Adam; Narock, Thomas W.; Armstrong, Thomas P.; Manweiler, Jerry W.; Patterson, J. Douglas; Hill, Matthew E.; Vandergriff, Jon D.; McKibben, Robert B.; Lopate, Clifford; Tranquille, Cecil

    2008-01-01

    The Virtual Energetic Particle Observatory (VEPO) focuses on improved discovery, access, and usability of heliospheric energetic particle and ancillary data products from selected spacecraft and sub-orbital instruments of the heliophysics data environment. The energy range of interest extends over the full range of particle acceleration from keV energies of suprathermal seed particles to GeV energies of galactic cosmic ray particles. Present spatial coverage is for operational and legacy spacecraft operating from the inner to the outer heliosphere, e.g. from measurements by the two Helios spacecraft to 0.3 AU to the inner heliosheath region now being traversed by the two Voyager spacecraft. This coverage will eventually be extended inward to ten solar radii by the planned NASA solar probe mission and at the same time beyond the heliopause into the outer heliosheath by continued Voyager operations. The geospace fleet of spacecraft providing near-Earth interplanetary measurements, selected magnetospheric spacecraft providing direct measurements of penetrating interplanetary energetic particles, and interplanetary cruise measurements from planetary spacecraft missions further extend VEPO resources to the domain of geospace and planetary interactions. Ground-based (e.g., neutron monitor) and high-altitude suborbital measurements can expand coverage to the highest energies of galactic cosmic rays affected by heliospheric interaction and of solar energetic particles. Science applications include investigation of solar flare and coronal mass ejection events. acceleration and transport of interplanetary particles within the inner heliosphere, cosmic ray interactions with planetary surfaces and atmospheres, sources of suprathermal and anomalous cosmic ray ions in the outer heliosphere, and solar cycle modulation of galactic cosmic rays. Robotic and human exploration, and eventual habitation, of planetary and space environments beyond the Earth require knowledge of radiation

  8. Virtual Energetic Particle Observatory (VEPO)

    NASA Astrophysics Data System (ADS)

    Cooper, J. F.; Lal, N.; McGuire, R. E.; Szabo, A.; Narock, T. W.; Armstrong, T. P.; Manweiler, J. W.; Patterson, J. D.; Hill, M. E.; Vandergriff, J. D.; McKibben, R. B.; Lopate, C.; Tranquille, C.

    2008-12-01

    The Virtual Energetic Particle Observatory (VEPO) focuses on improved discovery, access, and usability of heliospheric energetic particle and ancillary data products from selected spacecraft and sub-orbital instruments of the heliophysics data environment. The energy range of interest extends over the full range of particle acceleration from keV energies of suprathermal seed particles to GeV energies of galactic cosmic ray particles. Present spatial coverage is for operational and legacy spacecraft operating from the inner to the outer heliosphere, e.g. from measurements by the two Helios spacecraft to 0.3 AU to the inner heliosheath region now being traversed by the two Voyager spacecraft. This coverage will eventually be extended inward to ten solar radii by the planned NASA solar probe mission and at the same time beyond the heliopause into the outer heliosheath by continued Voyager operations. The geospace fleet of spacecraft providing near-Earth interplanetary measurements, selected magnetospheric spacecraft providing direct measurements of penetrating interplanetary energetic particles, and interplanetary cruise measurements from planetary spacecraft missions further extend VEPO resources to the domain of geospace and planetary interactions. Ground-based (e.g., neutron monitor) and high-altitude suborbital measurements can expand coverage to the highest energies of galactic cosmic rays affected by heliospheric interaction and of solar energetic particles. Science applications include investigation of solar flare and coronal mass ejection events, acceleration and transport of interplanetary particles within the inner heliosphere, cosmic ray interactions with planetary surfaces and atmospheres, sources of suprathermal and anomalous cosmic ray ions in the outer heliosphere, and solar cycle modulation of galactic cosmic rays. Robotic and human exploration, and eventual habitation, of planetary and space environments beyond the Earth require knowledge of radiation

  9. Shearfree cylindrical gravitational collapse

    SciTech Connect

    Di Prisco, A.; Herrera, L.; MacCallum, M. A. H.; Santos, N. O.

    2009-09-15

    We consider diagonal cylindrically symmetric metrics, with an interior representing a general nonrotating fluid with anisotropic pressures. An exterior vacuum Einstein-Rosen spacetime is matched to this using Darmois matching conditions. We show that the matching conditions can be explicitly solved for the boundary values of metric components and their derivatives, either for the interior or exterior. Specializing to shearfree interiors, a static exterior can only be matched to a static interior, and the evolution in the nonstatic case is found to be given in general by an elliptic function of time. For a collapsing shearfree isotropic fluid, only a Robertson-Walker dust interior is possible, and we show that all such cases were included in Cocke's discussion. For these metrics, Nolan and Nolan have shown that the matching breaks down before collapse is complete, and Tod and Mena have shown that the spacetime is not asymptotically flat in the sense of Berger, Chrusciel, and Moncrief. The issues about energy that then arise are revisited, and it is shown that the exterior is not in an intrinsic gravitational or superenergy radiative state at the boundary.

  10. Distributed Observatory Management

    NASA Astrophysics Data System (ADS)

    Godin, M. A.; Bellingham, J. G.

    2006-12-01

    A collection of tools for collaboratively managing a coastal ocean observatory have been developed and used in a multi-institutional, interdisciplinary field experiment. The Autonomous Ocean Sampling Network program created these tools to support the Adaptive Sampling and Prediction (ASAP) field experiment that occurred in Monterey Bay in the summer of 2006. ASAP involved the day-to-day participation of a large group of researchers located across North America. The goal of these investigators was to adapt an array of observational assets to optimize data collection and analysis. Achieving the goal required continual interaction, but the long duration of the observatory made sustained co-location of researchers difficult. The ASAP team needed a remote collaboration tool, the capability to add non-standard, interdisciplinary data sets to the overall data collection, and the ability to retrieve standardized data sets from the collection. Over the course of several months and "virtual experiments," the Ocean Observatory Portal (COOP) collaboration tool was created, along with tools for centralizing, cataloging, and converting data sets into common formats, and tools for generating automated plots of the common format data. Accumulating the data in a central location and converting the data to common formats allowed any team member to manipulate any data set quickly, without having to rely heavily on the expertise of data generators to read the data. The common data collection allowed for the development of a wide range of comparison plots and allowed team members to assimilate new data sources into derived outputs such as ocean models quickly. In addition to the standardized outputs, team members were able to produce their own specialized products and link to these through the collaborative portal, which made the experimental process more interdisciplinary and interactive. COOP was used to manage the ASAP vehicle program from its start in July 2006. New summaries were

  11. Astronomical publications of Melbourne Observatory

    NASA Astrophysics Data System (ADS)

    Andropoulos, Jenny Ioanna

    2014-05-01

    During the second half of the 19th century and the first half of the 20th century, four well-equipped government observatories were maintained in Australia - in Melbourne, Sydney, Adelaide and Perth. These institutions conducted astronomical observations, often in the course of providing a local time service, and they also collected and collated meteorological data. As well, some of these observatories were involved at times in geodetic surveying, geomagnetic recording, gravity measurements, seismology, tide recording and physical standards, so the term "observatory" was being used in a rather broad sense! Despite the international renown that once applied to Williamstown and Melbourne Observatories, relatively little has been written by modern-day scholars about astronomical activities at these observatories. This research is intended to rectify this situation to some extent by gathering, cataloguing and analysing the published astronomical output of the two Observatories to see what contributions they made to science and society. It also compares their contributions with those of Sydney, Adelaide and Perth Observatories. Overall, Williamstown and Melbourne Observatories produced a prodigious amount of material on astronomy in scientific and technical journals, in reports and in newspapers. The other observatories more or less did likewise, so no observatory of those studied markedly outperformed the others in the long term, especially when account is taken of their relative resourcing in staff and equipment.

  12. Time Evolution of Pure Gravitational Waves

    NASA Astrophysics Data System (ADS)

    Miyama, S. M.

    1981-03-01

    Numerical solutions to the Einstein equations in the case of pure gravitational waves are given. The system is assumed to be axially symmetric and non-rotating. The time symmetric initial data and the conformally flat initial data are obtained by solving the constraint equations at t=0. The time evolution of these initial data depends strongly on the initial amplitude of the gravitational waves. In the case of the low initial amplitude, waves only disperse to null infinity. By comparing the initial gravitational energy with the total energy loss through an r=constant surface, it is concluded that the Newman-Penrose method and the Gibbon-Hawking method are the most desirable for measuring the energy flux of gravitational radiation numerically. In the case that the initial ratio of the spatial extent of the gravitational waves to the Schwarzschild radius (M/2) is smaller than about 300, the waves collapse by themselves, leading to formation of a black hole. The analytic solutions of the linearized Einstein equations for the pure gravitational waves are also shown.

  13. Portable coastal observatories

    USGS Publications Warehouse

    Frye, Daniel; Butman, Bradford; Johnson, Mark; von der Heydt, Keith; Lerner, Steven

    2000-01-01

    Ocean observational science is in the midst of a paradigm shift from an expeditionary science centered on short research cruises and deployments of internally recording instruments to a sustained observational science where the ocean is monitored on a regular basis, much the way the atmosphere is monitored. While satellite remote sensing is one key way of meeting the challenge of real-time monitoring of large ocean regions, new technologies are required for in situ observations to measure conditions below the ocean surface and to measure ocean characteristics not observable from space. One method of making sustained observations in the coastal ocean is to install a fiber optic cable from shore to the area of interest. This approach has the advantage of providing power to offshore instruments and essentially unlimited bandwidth for data. The LEO-15 observatory offshore of New Jersey (yon Alt et al., 1997) and the planned Katama observatory offshore of Martha's Vineyard (Edson et al., 2000) use this approach. These sites, along with other cabled sites, will play an important role in coastal ocean science in the next decade. Cabled observatories, however, have two drawbacks that limit the number of sites that are likely to be installed. First, the cable and the cable installation are expensive and the shore station needed at the cable terminus is often in an environmentally sensitive area where competing interests must be resolved. Second, cabled sites are inherently limited geographically to sites within reach of the cable, so it is difficult to cover large areas of the coastal ocean.

  14. The PS1 Observatory

    NASA Astrophysics Data System (ADS)

    Kaiser, Nick; Morgan, J.; Pier, E.; Chambers, K.

    2007-12-01

    The Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) will use gigapixel cameras on multi-aperture telescopes to survey the sky in the visible and near-infrared bands. The first surveys will begin in 2008 using a single telescope system (PS1) has been deployed on Haleakala, Maui. This facility is currently undergoing commissioning tests. The PS1 telescope is a 1.8-m f/4 Richey-Chretien design that employs three 50 cm diameter correcting lens. The optical system produces a 3 degree diameter field of view at the focal plane. Images will be recorded on a 1.4 gigapixel CCD camera (described in an accompanying poster presentation). The survey programs will be conducted using g, r, i, and z filters which closely approximate the band-pass and response of those used in the Sloan Digital Sky Survey. These filters will be supplemented with a y band filter further to the infrared of z and a wide w filter for solar system observations. The images from the PS1 camera are supplemented by an Imaging Sky Probe that will provide co-pointed photometric calibration images of each target field. An all-sky camera at the observatory monitors sky conditions and transparency. The operation of the PS1 telescope is supported by the Observatory, Telescope, and Instrument Software (OTIS) system. The OTIS software interfaces the telescope control software provided by the vendor and the CCD camera computer systems. OTIS also records and archives environmental metadata from the dome and the observatory weather station.

  15. ESO's Two Observatories Merge

    NASA Astrophysics Data System (ADS)

    2005-02-01

    On February 1, 2005, the European Southern Observatory (ESO) has merged its two observatories, La Silla and Paranal, into one. This move will help Europe's prime organisation for astronomy to better manage its many and diverse projects by deploying available resources more efficiently where and when they are needed. The merged observatory will be known as the La Silla Paranal Observatory. Catherine Cesarsky, ESO's Director General, comments the new development: "The merging, which was planned during the past year with the deep involvement of all the staff, has created unified maintenance and engineering (including software, mechanics, electronics and optics) departments across the two sites, further increasing the already very high efficiency of our telescopes. It is my great pleasure to commend the excellent work of Jorge Melnick, former director of the La Silla Observatory, and of Roberto Gilmozzi, the director of Paranal." ESO's headquarters are located in Garching, in the vicinity of Munich (Bavaria, Germany), and this intergovernmental organisation has established itself as a world-leader in astronomy. Created in 1962, ESO is now supported by eleven member states (Belgium, Denmark, Finland, France, Germany, Italy, The Netherlands, Portugal, Sweden, Switzerland, and the United Kingdom). It operates major telescopes on two remote sites, all located in Chile: La Silla, about 600 km north of Santiago and at an altitude of 2400m; Paranal, a 2600m high mountain in the Atacama Desert 120 km south of the coastal city of Antofagasta. Most recently, ESO has started the construction of an observatory at Chajnantor, a 5000m high site, also in the Atacama Desert. La Silla, north of the town of La Serena, has been the bastion of the organization's facilities since 1964. It is the site of two of the most productive 4-m class telescopes in the world, the New Technology Telescope (NTT) - the first major telescope equipped with active optics - and the 3.6-m, which hosts HARPS

  16. NASA's Heliophysics System Observatory

    NASA Astrophysics Data System (ADS)

    Clarke, Steven

    2016-04-01

    NASA formulates and implements a national research program for understanding the Sun and its interactions with the Earth and the solar system and how these phenomena impact life and society. This research provides theory, data, and modeling development services to national and international space weather efforts utilizing a coordinated and complementary fleet of spacecraft, called the Heliophysics System Observatory (HSO), to understand the Sun and its interactions with Earth and the solar system, including space weather. This presentation will focus on NASA's role in space weather research and the contributions the agency continues to provide to the science of space weather, leveraging inter-agency and international collaborations for the benefit of society.

  17. Next Generation Virtual Observatories

    NASA Astrophysics Data System (ADS)

    Fox, P.; McGuinness, D. L.

    2008-12-01

    Virtual Observatories (VO) are now being established in a variety of geoscience disciplines beyond their origins in Astronomy and Solar Physics. Implementations range from hydrology and environmental sciences to solid earth sciences. Among the goals of VOs are to provide search/ query, access and use of distributed, heterogeneous data resources. With many of these goals being met and usage increasing, new demands and requirements are arising. In particular there are two of immediate and pressing interest. The first is use of VOs by non-specialists, especially for information products that go beyond the usual data, or data products that are sought for scientific research. The second area is citation and attribution of artifacts that are being generated by VOs. In some sense VOs are re-publishing (re-packaging, or generating new synthetic) data and information products. At present only a few VOs address this need and it is clear that a comprehensive solution that includes publishers is required. Our work in VOs and related semantic data framework and integration areas has lead to a view of the next generation of virtual observatories which the two above-mentioned needs as well as others that are emerging. Both of the needs highlight a semantic gap, i.e. that the meaning and use for a user or users beyond the original design intention is very often difficult or impossible to bridge. For example, VOs created for experts with complex, arcane or jargon vocabularies are not accessible to the non-specialist and further, information products the non-specialist may use are not created or considered for creation. In the second case, use of a (possibly virtual) data or information product (e.g. an image or map) as an intellectual artifact that can be accessed as part of the scientific publication and review procedure also introduces terminology gaps, as well as services that VOs may need to provide. Our supposition is that formalized methods in semantics and semantic web

  18. Strasbourg Observatory Archives Revisited

    NASA Astrophysics Data System (ADS)

    Heck, A.

    2002-12-01

    Official talks in France and Germany after World War I were generally of hatred and revenge. Strasbourg Observatory had just changed nationality (from Prussian to French) for the first time (this would happen again at the outbreak of WWII and after the conflict). Documents show that astronomers did not share the general attitude. For example the inventory book started in German was continued in French after 1918. It is moving to see those different handwritings in two different languages on the same pages -- making of that book a unique document in various respects, but also reminding us that the native language of the region was in fact Alsacian.

  19. Acquirement of the observatory code of Langkawi National Observatory

    NASA Astrophysics Data System (ADS)

    Loon, Chin Wei; Zainuddin, Mohd. Zambri; Ahmad, Nazhatulshima; Shukor, Muhammad Shamim; Tahar, Muhammad Redzuan

    2015-04-01

    Observatory code was assigned by The International Astronomical Union (IAU) Minor Planet Center (MPC) for a permanent observatory that intended to do astrometric CCD-observing program of minor planet or comets in solar system. The purpose of acquiring an observatory code is to document specific details about a particular observation site and the types of instruments used within the observatory. In addition, many astronomical centers and stations worldwide will know there is an active observatory at the particular location and international cooperation program in astronomy observation is possible. The Langkawi National Observatory has initiated an observation program to monitor minor planet, specifically those Near Earth Objects (NEOs) that may bring potentially hazardous to the Earth. In order to fulfil the requirement that stated by MPC for undertaking astrometric CCD-observing program, an observatory code was required. The instruments and methods that applied to obtain the observatory code will be discussed. The Langkawi National Observatory is now coded as O43 and listed in the MPC system, the single worldwide location for receipt and distribution of positional measurements of minor planets, comets and outer irregular natural satellites of major planets.

  20. Inflationary gravitational waves and the evolution of the early universe

    SciTech Connect

    Jinno, Ryusuke; Moroi, Takeo; Nakayama, Kazunori E-mail: moroi@hep-th.phys.s.u-tokyo.ac.jp

    2014-01-01

    We study the effects of various phenomena which may have happened in the early universe on the spectrum of inflationary gravitational waves. The phenomena include phase transitions, entropy productions from non-relativistic matter, the production of dark radiation, and decoupling of dark matter/radiation from thermal bath. These events can create several characteristic signatures in the inflationary gravitational wave spectrum, which may be direct probes of the history of the early universe and the nature of high-energy physics.

  1. Space-Based Gravitational-wave Mission Concept Studies

    NASA Technical Reports Server (NTRS)

    Livas, Jeffrey C.

    2012-01-01

    The LISA Mission Concept has been under study for over two decades as a spacebased gravitational-wave detector capable of observing astrophysical sources in the 0.0001 to 1 Hz band. The concept has consistently received strong recommendations from various review panels based on the expected science, most recently from the US Astr02010 Decadal Review. Budget constraints have led both the US and European Space agencies to search for lower cost options. We report results from the US effort to explore the tradeoffs between mission cost and science return, and in particular a family of mission concepts referred to as SGO (Space-based Gravitational-wave Observatory).

  2. 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)

  3. SOFIA: The Next Generation Airborne Observatory

    NASA Astrophysics Data System (ADS)

    Erickson, E. F.

    1995-10-01

    The United States and German Space Agencies (NASA and DARA) are collaborating in plans for SOFIA — The Stratospheric Observatory for Infrared Astronomy. It is a 2.5 meter telescope to be installed in a Boeing 747 aircraft and operated at altitudes from 41,000 to 45,000 feet. It will permit routine measurement of infrared radiation absorbed by the atmosphere at lower altitudes, and observation of astronomical objects and transient events from anywhere in the world. The concept is based on 20 years of experience with NASA's Kuiper Airborne Observatory (KAO), which SOFIA would replace. SOFIA will complement the capabilities of other future space missions, and will enable scientists to make observations which would otherwise be made from space.

  4. Strasbourg Observatory in World War II

    NASA Astrophysics Data System (ADS)

    Duerbeck, H. W.

    During World War II, the Reichsuniversitat Strassburg was installed by the German authorities and Johannes Hellerich (1888-1963) was appointed director of the Observatory. A review of his life and his astro- nomical career as an assistant and professor in Kiel, Hamburg, Strasbourg, and Muenster is given. His activity in Strasbourg from mid-1941 to mid-1943 was focussed on bringing the Observatory into working operations, and on carrying out the monitoring of solar radiation and atmospheric extinction. After being drafted to the army and spending some time as a prisoner of war, he returned to Hamburg to complete a review on variable-star research in wartime Germany. He was called to Muenster University in 1947 to teach astronomy, and, from 1949 onward, to serve as director of the small Astronomical Institute till his retirement in 1954.

  5. The Asiago Observatory's reflectogoniometer

    NASA Astrophysics Data System (ADS)

    Fornasier, S.; Pernechele, C.; Barbieri, C.

    1999-09-01

    We present the Asiago Astrophysical Observatory reflectogoniometer, a useful instrument which allows to perform laboratory studies of transmitted and diffuse light. In particular the instrument allows a complete characterization of the Bidirectional Reflectance Function (BDRF) for spherical shape samples and of the Transmittance Function for plane samples. The instrument is placed in an optical laboratory of the Asiago Astrophysical Observatory. Data are acquired by a CCD camera, equipped with its own frame grabber card, and analysed by a pc. Image calibration, i.e. the procedure that converts the value of each pixel of a CCD frame in a radiometric quantity, follows the standard sequence used for remote sensing application (bias, dark, flat fielding, distortion corrections, reflectogoniometric calibration, using a reflectometric standard), and it is implemented in a data reduction pipeline. The instrument tests performed until now have confirm that the imaging-goniophotometer is an instrument suitable for the quick characterization of diffusing surfaces in all the tree possible configuration: transmittance measurements (translucent plates), partial reflectance measurements (diffusing sheets), and bidirectional function characterization (coatings and paints). The goniophotometer may have different astronomical and industrial applications: it can be used for the characterization of absorbance properties of paints for baffling in spatial missions, of diffusive properties of flat field panels, of trasmittance properties of different glasses type and of reflective properties of rocks surfaces, like, for example, meteorites samples.

  6. Wendelstein Observatory Operations Software

    NASA Astrophysics Data System (ADS)

    Gössl, C. A.; Snigula, J. M.; Munzert, T.

    2014-05-01

    LMU München operates an astrophysical observatory on Mt. Wendelstein which has been equipped with a modern 2m-class telescope recently. The new Fraunhofer telescope is starting science operations now with a 64 Mpixel, 0.5°×0.5° FoV wide field camera and will successively be equipped with a three channel optical/NIR camera and two fibre coupled spectrographs (IFU spectrograph VIRUSW already in operation at the 2.7m McDonald, Texas and an upgraded Echelle spectrograph FOCES formerly operated at Calar Alto oberservatory, Spain). All instruments will be mounted simultaneously and can be activated within a minute. The observatory also operates a small 40cm telescope with a CCD-camera and a simple fibre coupled spectrograph for students lab and photometric monitoring as well as a large number of support equipment like a meteo station, allsky cameras, a multitude of webcams, in addition to a complex building control system environment. Here we describe the ongoing effort to build a centralised controlling interface for all. This includes remote/robotic operation, visualisation via browser technologies, and data processing and archiving.

  7. Wendelstein Observatory control software

    NASA Astrophysics Data System (ADS)

    Gössl, Claus; Snigula, Jan; Kodric, Mihael; Riffeser, Arno; Munzert, Tobias

    2014-07-01

    LMU München operates an astrophysical observatory on Mt. Wendelstein1 which has been equipped with a modern 2m-class telescope2, 3 recently. The new Fraunhofer telescope has started science operations in autumn 2013 with a 64 Mpixel, 0:5 x 0:5 square degree FoV wide field camera,4 and will successively be equipped with a 3 channel optical/NIR camera5 and 2 fibre coupled spectrographs (IFU spectrograph VIRUSW6 already in operation at the 2.7 McDonald, Texas and an upgraded Echelle spectrograph FOCES7, 8 formerly operated at Calar Alto oberservatory, Spain). All instruments will be mounted simultaneously and can be activated within a minute. The observatory also operates a small 40cm telescope with a CCD-camera and a simple fibre coupled spectrograph for students lab and photometric monitoring as well as a large number of support equipment like a meteo station, allsky cameras, a multitude of webcams, in addition to a complex building control system environment. Here we describe the ongoing effort to build a centralised controlling interface for all hardware. This includes remote/robotic operation, visualisation via web browser technologies, and data processing and archiving.

  8. Lepton asymmetry in the primordial gravitational wave spectrum

    SciTech Connect

    Ichiki, Kiyotomo; Yamaguchi, Masahide; Yokoyama, Jun'Ichi

    2007-04-15

    Effects of neutrino free streaming are evaluated on the primordial spectrum of gravitational radiation taking both neutrino chemical potential and masses into account. The former or the lepton asymmetry induces two competitive effects, namely, to increase anisotropic stress, which damps the gravitational wave more, and to delay the matter-radiation equality time, which reduces the damping. The latter effect is more prominent and a large lepton asymmetry would reduce the damping. We may thereby be able to measure the magnitude of lepton asymmetry from the primordial gravitational wave spectrum.

  9. Interaction of gravitational waves with magnetic and electric fields

    SciTech Connect

    Barrabes, C.; Hogan, P. A.

    2010-03-15

    The existence of large-scale magnetic fields in the universe has led to the observation that if gravitational waves propagating in a cosmological environment encounter even a small magnetic field then electromagnetic radiation is produced. To study this phenomenon in more detail we take it out of the cosmological context and at the same time simplify the gravitational radiation to impulsive waves. Specifically, to illustrate our findings, we describe the following three physical situations: (1) a cylindrical impulsive gravitational wave propagating into a universe with a magnetic field, (2) an axially symmetric impulsive gravitational wave propagating into a universe with an electric field and (3) a 'spherical' impulsive gravitational wave propagating into a universe with a small magnetic field. In cases (1) and (3) electromagnetic radiation is produced behind the gravitational wave. In case (2) no electromagnetic radiation appears after the wave unless a current is established behind the wave breaking the Maxwell vacuum. In all three cases the presence of the magnetic or electric fields results in a modification of the amplitude of the incoming gravitational wave which is explicitly calculated using the Einstein-Maxwell vacuum field equations.

  10. Stratospheric Observatory for Infrared Astronomy

    NASA Astrophysics Data System (ADS)

    Hamidouche, M.; Young, E.; Marcum, P.; Krabbe, A.

    2010-12-01

    We present one of the new generations of observatories, the Stratospheric Observatory For Infrared Astronomy (SOFIA). This is an airborne observatory consisting of a 2.7-m telescope mounted on a modified Boeing B747-SP airplane. Flying at an up to 45,000 ft (14 km) altitude, SOFIA will observe above more than 99 percent of the Earth's atmospheric water vapor allowing observations in the normally obscured far-infrared. We outline the observatory capabilities and goals. The first-generation science instruments flying on board SOFIA and their main astronomical goals are also presented.

  11. GPM Core Observatory Launch Animation

    NASA Video Gallery

    This animation depicts the launch of the Global Precipitation Measurement (GPM) Core Observatory satellite from Tanegashima Space Center, Japan. The launch is currently scheduled for Feb. 27, 2014....

  12. Gravitation and celestial mechanics investigations with Galileo

    NASA Technical Reports Server (NTRS)

    Anderson, J. D.; Armstrong, J. W.; Campbell, J. K.; Estabrook, F. B.; Krisher, T. P.; Lau, E. L.

    1992-01-01

    The gravitation and celestial mechanics investigations that are to be conducted during the cruise and Orbiter phases of the Galileo Mission cover four investigation categories: (1) the gravity fields of Jupiter and its four major satellites; (2) a search for gravitational radiation; (3) mathematical modeling of general relativistic effects on Doppler ranging data; and (4) improvements of the Jupiter ephemeris via Orbiter ranging. Also noted are two secondary objectives, involving a range fix during Venus flyby and the determination of the earth's mass on the bases of the two earth gravity assists used by the mission.

  13. Are cosmic strings gravitationally stable topological defects?

    NASA Astrophysics Data System (ADS)

    Gleiser, Reinaldo; Pullin, Jorge

    1989-08-01

    A possible mechanism for the dissapearance of an open cosmic string into gravitational radiation is described. This involves the splitting of an infinite straight cosmic string into two pieces whose ends are traveling outward at the speed of light with the associated emission of a gravitational shock wave. This model can also be used to describe the following situations: (1) the development of a growing region of different string tension within a cosmic string, and (2) the creation of a cosmic string in an otherwise flat background.

  14. Search for gravitational radiation from intermediate mass black hole binaries in data from the second LIGO-Virgo joint science run

    NASA Astrophysics Data System (ADS)

    Aasi, J.; Abbott, B. P.; Abbott, R.; Abbott, T.; Abernathy, M. R.; Accadia, T.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Affeldt, C.; Agathos, M.; Aggarwal, N.; Aguiar, O. D.; Ain, A.; Ajith, P.; Alemic, A.; Allen, B.; Allocca, A.; Amariutei, D.; Andersen, M.; Anderson, R.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C.; Areeda, J.; 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.; Barbet, M.; Barish, B. C.; Barker, D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barton, M. A.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Bauchrowitz, J.; Bauer, Th. S.; Bavigadda, V.; Behnke, B.; Bejger, M.; Beker, M. G.; Belczynski, C.; Bell, A. S.; Bell, C.; Bergmann, G.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Beyersdorf, P. T.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Biscans, S.; Bitossi, M.; Bizouard, M. A.; Black, E.; Blackburn, J. K.; Blackburn, L.; Blair, D.; Bloemen, S.; Blom, M.; Bock, O.; Bodiya, T. P.; Boer, M.; Bogaert, G.; Bogan, C.; Bond, C.; Bondu, F.; Bonelli, L.; Bonnand, R.; Bork, R.; Born, M.; Boschi, V.; Bose, Sukanta; Bosi, L.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Briant, T.; Bridges, D. O.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brückner, F.; Buchman, S.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Burman, R.; Buskulic, D.; Buy, C.; 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.; Celerier, C.; Cella, G.; Cepeda, C.; Cesarini, E.; Chakraborty, R.; Chalermsongsak, T.; Chamberlin, S. J.; 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, J. A.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Collette, C.; Colombini, M.; Cominsky, L.; Constancio, M.; Conte, A.; Cook, D.; Corbitt, T. R.; Cordier, M.; Cornish, N.; Corpuz, A.; Corsi, A.; Costa, C. A.; Coughlin, M. W.; Coughlin, S.; Coulon, J.-P.; Countryman, S.; Couvares, P.; Coward, D. M.; Cowart, M.; Coyne, D. C.; Coyne, R.; Craig, K.; Creighton, J. D. E.; Crowder, S. G.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dahl, K.; Canton, T. Dal; Damjanic, M.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dattilo, V.; Daveloza, H.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; Dayanga, T.; Debreczeni, G.; Degallaix, J.; Deléglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dereli, H.; Dergachev, V.; De Rosa, R.; DeRosa, R. T.; DeSalvo, R.; Dhurandhar, S.; Díaz, M.; Di Fiore, L.; Di Lieto, A.; Di Palma, I.; Di Virgilio, A.; Donath, A.; Donovan, F.; Dooley, K. L.; Doravari, S.; Dossa, S.; Douglas, R.; Downes, T. P.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dwyer, S.; Eberle, T.; Edo, T.; Edwards, M.; Effler, A.; Eggenstein, H.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Endrőczi, G.; Essick, R.; Etzel, T.; Evans, M.; Evans, T.; Factourovich, M.; Fafone, V.; Fairhurst, S.; Fang, Q.; Farinon, S.; Farr, B.; Farr, W. M.; Favata, M.; Fehrmann, H.; Fejer, M. M.; Feldbaum, D.; Feroz, F.; Ferrante, I.; Ferrini, F.; Fidecaro, F.; Finn, L. S.; Fiori, I.; Fisher, R. P.; Flaminio, R.; Fournier, J.-D.; Franco, S.; Frasca, S.; Frasconi, F.; Frede, M.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gair, J.; Gammaitoni, L.; Gaonkar, S.; Garufi, F.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gill, C.; Gleason, J.; Goetz, E.; Goetz, R.; Gondan, L.; González, G.; Gordon, N.; Gorodetsky, M. L.; Gossan, S.; Goßler, S.; Gouaty, R.; Gräf, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Groot, P.; Grote, H.; Grover, K.; Grunewald, S.; Guidi, G. M.; Guido, C.; Gushwa, K.; Gustafson, E. K.; Gustafson, R.; Hammer, D.; Hammond, G.; Hanke, M.; Hanks, J.; Hanna, C.; Hanson, J.; Harms, J.; Harry, G. M.; Harry, I. W.; Harstad, E. D.; Hart, M.; Hartman, M. T.; Haster, C.-J.; Haughian, K.; Heidmann, A.; Heintze, M.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Heptonstall, A. W.; Heurs, M.; Hewitson, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Holt, K.; Hooper, S.; Hopkins, P.; Hosken, D. J.; Hough, J.; Howell, E. J.; Hu, Y.; Huerta, E.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh, M.; Huynh-Dinh, T.; Ingram, D. R.; Inta, R.; Isogai, T.; Ivanov, A.; Iyer, B. R.; Izumi, K.; Jacobson, M.; James, E.

    2014-06-01

    This paper reports on an unmodeled, all-sky search for gravitational waves from merging intermediate mass black hole binaries (IMBHB). The search was performed on data from the second joint science run of the LIGO and Virgo detectors (July 2009-October 2010) and was sensitive to IMBHBs with a range up to ˜200 Mpc, averaged over the possible sky positions and inclinations of the binaries with respect to the line of sight. No significant candidate was found. Upper limits on the coalescence-rate density of nonspinning IMBHBs with total masses between 100 and 450 M⊙ and mass ratios between 0.25 and 1 were placed by combining this analysis with an analogous search performed on data from the first LIGO-Virgo joint science run (November 2005-October 2007). The most stringent limit was set for systems consisting of two 88 M⊙ black holes and is equal to 0.12 Mpc-3 Myr-1 at the 90% confidence level. This paper also presents the first estimate, for the case of an unmodeled analysis, of the impact on the search range of IMBHB spin configurations: the visible volume for IMBHBs with nonspinning components is roughly doubled for a population of IMBHBs with spins aligned with the binary's orbital angular momentum and uniformly distributed in the dimensionless spin parameter up to 0.8, whereas an analogous population with antialigned spins decreases the visible volume by ˜20%.

  15. Golden legacy from ESA's observatory

    NASA Astrophysics Data System (ADS)

    2003-07-01

    'milestone number' of 1000 scientific papers was reached. Even now ISO's data archive remains a valuable source of new results. For example, some of the latest papers describe the detection of water in 'protostars', which are stars in the process of being born, and studies of numerous nearby galaxies. "Of course we were confident ISO was going to do very well, but its actual productivity has been far beyond our expectations. The publication rate does not even seem to have peaked yet! We expect many more results," Salama says. Note for editors ISO's data archive contains scientific data from about 30 000 observations. Astronomers from all over the world have downloaded almost eight times the equivalent of the entire scientific archive. As much as 35% of all ISO observations have already been published at least once in prestigious scientific journals. ESA is now preparing to continue its infrared investigation of the Universe. The next generation of infrared space observatories is already in the pipeline. ISO is to be followed by the NASA SIRTF observatory to be launched later this year. Then, in 2007, ESA will follow up the pioneering work of ISO with the Herschel Space Observatory, which will become the largest imaging telescope ever put into space. ISO The Infrared Space Observatory (ISO) was launched in 1995 and operated from November that year to May 1998, when it ran out of the coolant needed to keep its detectors working. At the time it was the most sensitive infrared satellite ever launched and made particularly important studies of the dusty regions of the Universe, where visible light telescopes can see nothing. ESA will reopen its examination of the infrared Universe when Herschel is launched in 2007. Herschel Herschel will be the largest space telescope when, in 2007, it is launched on an Ariane-5 rocket, together with ESA’s cosmology mission, Planck. Herschel’s 3.5-metre diameter mirror will collect longwave infrared radiation from some of the coolest and most

  16. Observatory ends scientific investigations

    NASA Astrophysics Data System (ADS)

    Bell, Peter M.

    The Orbiting Astronomical Observatory (OAO-3), which was instrumental in the discovery of the first suspected black hole, wound up its scientific investigation at the end of 1980. Spacecraft science operations were terminated after 8½ years of operation. Named Copernicus, OAO-3 performed consistently beyond design specifications and 7½ years beyond project requirements. Its performance profile, according to the NASA-Goddard engineers and scientists, was ‘astonishing.’While formal scientific investigations were ended December 31, a series of engineering tests are still being made until February 15. At that time, all contact with the spacecraft will end. Project engineers are uncertain whether Copernicus will orient itself permanently toward the sun, begin a permanent orbital tumbling action, or a variation of both.

  17. The Sudbury Neutrino Observatory

    NASA Astrophysics Data System (ADS)

    Bellerive, A.; Klein, J. R.; McDonald, A. B.; Noble, A. J.; Poon, A. W. P.

    2016-07-01

    This review paper provides a summary of the published results of the Sudbury Neutrino Observatory (SNO) experiment that was carried out by an international scientific collaboration with data collected during the period from 1999 to 2006. By using heavy water as a detection medium, the SNO experiment demonstrated clearly that solar electron neutrinos from 8B decay in the solar core change into other active neutrino flavors in transit to Earth. The reaction on deuterium that has equal sensitivity to all active neutrino flavors also provides a very accurate measure of the initial solar flux for comparison with solar models. This review summarizes the results from three phases of solar neutrino detection as well as other physics results obtained from analyses of the SNO data.

  18. Orbiting Carbon Observatory

    NASA Technical Reports Server (NTRS)

    Miller, Charles E.

    2005-01-01

    Human impact on the environment has produced measurable changes in the geological record since the late 1700s. Anthropogenic emissions of CO2 today may cause the global climate to depart for its natural behavior for many millenia. CO2 is the primary anthropogenic driver of climate change. The Orbiting Carbon Observatory goals are to help collect measurements of atmospheric CO2, answering questions such as why the atmospheric CO2 buildup varies annually, the roles of the oceans and land ecosystems in absorbing CO2, the roles of North American and Eurasian sinks and how these carbon sinks respond to climate change. The present carbon cycle, CO2 variability, and climate uncertainties due atmospheric CO2 uncertainties are highlighted in this presentation.

  19. The virtual observatory registry

    NASA Astrophysics Data System (ADS)

    Demleitner, M.; Greene, G.; Le Sidaner, P.; Plante, R. L.

    2014-11-01

    In the Virtual Observatory (VO), the Registry provides the mechanism with which users and applications discover and select resources-typically, data and services-that are relevant for a particular scientific problem. Even though the VO adopted technologies in particular from the bibliographic community where available, building the Registry system involved a major standardisation effort, involving about a dozen interdependent standard texts. This paper discusses the server-side aspects of the standards and their application, as regards the functional components (registries), the resource records in both format and content, the exchange of resource records between registries (harvesting), as well as the creation and management of the identifiers used in the system based on the notion of authorities. Registry record authors, registry operators or even advanced users thus receive a big picture serving as a guideline through the body of relevant standard texts. To complete this picture, we also mention common usage patterns and open issues as appropriate.

  20. How beaming of gravitational waves compares to the beaming of electromagnetic waves: impacts to gravitational wave detection

    NASA Astrophysics Data System (ADS)

    Miller, Andrew L.; Wickramasinghe, Thulsi

    2016-05-01

    We focus on understanding the beaming of gravitational radiation from gamma ray bursts (GRBs) by approximating GRBs as linearly accelerated point masses. For accelerated point masses, it is known that gravitational radiation is beamed isotropicly at high speeds, and beamed along the polar axis at low speeds. Aside from this knowledge, there has been very little work done on beaming of gravitational radiation from GRBs, and the impact beaming could have on gravitational wave (GW) detection. We determine the following: (1) the observation angle at which the most power is emitted as a function of speed, (2) the maximum ratio of power radiated away as a function of speed, and (3) the angular distribution of power ratios at relativistic and non-relativistic speeds. Additionally the dependence of the beaming of GW radiation on speed is essentially the opposite of the beaming of electromagnetic (EM) radiation from GRBs. So we investigate why this is the case by calculating the angular EM radiation distribution from a linear electric quadrupole, and compare this distribution to the angular gravitational radiation distribution from a GRB.

  1. Global geodetic observatories

    NASA Astrophysics Data System (ADS)

    Boucher, Claude; Pearlman, Mike; Sarti, Pierguido

    2015-01-01

    Global geodetic observatories (GGO) play an increasingly important role both for scientific and societal applications, in particular for the maintenance and evolution of the reference frame and those applications that rely on the reference frame for their viability. The International Association of Geodesy (IAG), through the Global Geodetic Observing System (GGOS), is fully involved in coordinating the development of these systems and ensuring their quality, perenniality and accessibility. This paper reviews the current role, basic concepts, and some of the critical issues associated with the GGOs, and advocates for their expansion to enhance co-location with other observing techniques (gravity, meteorology, etc). The historical perspective starts with the MERIT campaign, followed by the creation of international services (IERS, IGS, ILRS, IVS, IDS, etc). It provides a basic definition of observing systems and observatories and the build up of the international networks and the role of co-locations in geodesy and geosciences and multi-technique processing and data products. This paper gives special attention to the critical topic of local surveys and tie vectors among co-located systems in sites; the agreement of space geodetic solutions and the tie vectors now place one of the most significant limitations on the quality of integrated data products, most notably the ITRF. This topic focuses on survey techniques, extrapolation to instrument reference points, computation techniques, systematic biases, and alignment of the individual technique reference frames into ITRF. The paper also discusses the design, layout and implementation of network infrastructure, including the role of GGOS and the benefit that would be achieved with better standardization and international governance.

  2. Sudbury Neutrino Observatory

    NASA Astrophysics Data System (ADS)

    Beier, E. W.

    1992-03-01

    This document is a technical progress report on work performed at the University of Pennsylvania during the current year on the Sudbury Neutrino Observatory project. The motivation for the experiment is the measurement of neutrinos emitted by the sun. The Sudbury Neutrino Observatory (SNO) is a second generation dedicated solar neutrino experiment which will extend the results of our work with the Kamiokande II detector by measuring three reactions of neutrinos rather than the single reaction measured by the Kamiokande experiment. The collaborative project includes physicists from Canada, the United Kingdom, and the United States. Full funding for the construction of this facility was obtained in Jan. 1990, and its construction is estimated to take five years. The motivation for the SNO experiment is to study the fundamental properties of neutrinos, in particular the mass and mixing parameters, which remain undetermined after decades of experiments in neutrino physics utilizing accelerators and reactors as sources of neutrinos. To continue the study of neutrino properties it is necessary to use the sun as a neutrino source. The long distance to the sun makes the search for neutrino mass sensitive to much smaller mass than can be studied with terrestrial sources. Furthermore, the matter density in the sun is sufficiently large to enhance the effects of small mixing between electron neutrinos and mu or tau neutrinos. This experiment, when combined with the results of the radiochemical Cl-37 and Ga-71 experiments and the Kamiokande II experiment, should extend our knowledge of these fundamental particles, and as a byproduct, improve our understanding of energy generation in the sun.

  3. Global Ionosphere Radio Observatory

    NASA Astrophysics Data System (ADS)

    Galkin, I. A.; Reinisch, B. W.; Huang, X. A.

    2014-12-01

    The Global Ionosphere Radio Observatory (GIRO) comprises a network of ground-based high-frequency vertical sounding sensors, ionosondes, with instrument installations in 27 countries and a central Lowell GIRO Data Center (LGDC) for data acquisition and assimilation, including 46 real-time data streams as of August 2014. The LGDC implemented a suite of technologies for post-processing, modeling, analysis, and dissemination of the acquired and derived data products, including: (1) IRI-based Real-time Assimilative Model, "IRTAM", that builds and publishes every 15-minutes an updated "global weather" map of the peak density and height in the ionosphere, as well as a map of deviations from the classic IRI climate; (2) Global Assimilative Model of Bottomside Ionosphere Timelines (GAMBIT) Database and Explorer holding 15 years worth of IRTAM computed maps at 15 minute cadence;. (3) 17+ million ionograms and matching ionogram-derived records of URSI-standard ionospheric characteristics and vertical profiles of electron density; (4) 10+ million records of the Doppler Skymaps showing spatial distributions over the GIRO locations and plasma drifts; (5) Data and software for Traveling Ionospheric Disturbance (TID) diagnostics; and (6) HR2006 ray tracing software mated to the "realistic" IRTAM ionosphere. In cooperation with the URSI Ionosonde Network Advisory Group (INAG), the LGDC promotes cooperative agreements with the ionosonde observatories of the world to accept and process real-time data of HF radio monitoring of the ionosphere, and to promote a variety of investigations that benefit from the global-scale, prompt, detailed, and accurate descriptions of the ionospheric variability.

  4. Emission of gravitational waves by precession of slim accretion disks dynamically driven by the Bardeen-Petterson effect

    NASA Astrophysics Data System (ADS)

    Alfonso, W. D.; Sánchez, L. A.; Mosquera, H. J.

    2015-11-01

    The electromagnetic radiation emitted from some astrophysical objects such as active galactic nuclei (AGN), micro-quasars (M-QSRs), and central engines of gamma-ray burst (GRBs), seems to have a similar physical origin: a powerful jet of plasma ejected from a localized system, presumably composed of an accretion disk encircling a compact object. This radiation is generally beamed in the polar directions and in some cases, it appears to have a spiral-like structure that could be explained if the central system itself precesses. In this work, we use the slim disk accretion model, presented by Popham et al. (1999), to studying the gravitational waves (GWs) emitted by the precession of the accretion disk around a solar-mass Kerr black hole (KBH). For practical purposes, this model describes the central engine of a class of GRBs when some astrophysical constrains are fulfilled. The induced precession considered here is driven by the Bardeen-Petterson effect, which results from the combination of viscous effects in such disks and the relativistic frame-dragging effect. We evaluate the feasibility of direct detection of the GWs computed for such a model and show that the precession of this kind of systems could be detected by gravitational wave observatories like DECIGO, ultimate-DECIGO, and BBO, with higher probability if such a class of sources are placed at distances less than 1 Mpc.

  5. Gravitational mass attraction measurement for drag-free references

    NASA Astrophysics Data System (ADS)

    Swank, Aaron J.

    Exciting new experiments in gravitational physics are among the proposed future space science missions around the world. Such future space science experiments include gravitational wave observatories, which require extraordinarily precise instruments for gravitational wave detection. In fact, future space-based gravitational wave observatories require the use of a drag free reference sensor, which is several orders of magnitude more precise than any drag free satellite launched to date. With the analysis methods and measurement techniques described in this work, there is one less challenge associated with achieving the high-precision drag-free satellite performance levels required by gravitational wave observatories. One disturbance critical to the drag-free performance is an acceleration from the mass attraction between the spacecraft and drag-free reference mass. A direct measurement of the gravitational mass attraction force is not easily performed. Historically for drag-free satellite design, the gravitational attraction properties were estimated by using idealized equations between a point mass and objects of regular geometric shape with homogeneous density. Stringent requirements are then placed on the density distribution and fabrication tolerances for the drag-free reference mass and satellite components in order to ensure that the allocated gravitational mass attraction disturbance budget is not exceeded due to the associated uncertainty in geometry and mass properties. Yet, the uncertainty associated with mass properties and geometry generate an unacceptable uncertainty in the mass attraction calculation, which make it difficult to meet the demanding drag-free performance requirements of future gravitational wave observatories. The density homogeneity and geometrical tolerances required to meet the overall drag-free performance can easily force the use of special materials or manufacturing processes, which are impractical or not feasible. The focus of

  6. Gravitational scaling dimensions

    SciTech Connect

    Hamber, Herbert W.

    2000-06-15

    A model for quantized gravitation based on simplicial lattice discretization is studied in detail using a comprehensive finite size scaling analysis combined with renormalization group methods. The results are consistent with a value for the universal critical exponent for gravitation, {nu}=1/3, and suggest a simple relationship between Newton's constant, the gravitational correlation length and the observable average space-time curvature. Some perhaps testable phenomenological implications of these results are discussed. To achieve a high numerical accuracy in the evaluation of the lattice path integral a dedicated parallel machine was assembled. (c) 2000 The American Physical Society.

  7. On Gravitational Repulsion

    NASA Astrophysics Data System (ADS)

    Piran, Tsvi

    1997-11-01

    The concepts of negative gravitational mass and gravitational repulsion are alien to general relativity. Still, we show here that small negative fluctuations~--- small dimples in the primordial density field~--- that act as if they have an effective negative gravitational mass, play a dominant role in shaping our Universe. These initially tiny perturbations repel matter surrounding them, expand and grow to become voids in the galaxy distribution. These voids~--- regions with a diameter of $40h^{-1}$ Mpc which are almost devoid of galaxies~--- are the largest objects in the Universe.

  8. Shot noise in gravitational-wave detectors with Fabry-Perot arms.

    PubMed

    Lyons, T T; Regehr, M W; Raab, F J

    2000-12-20

    Shot-noise-limited sensitivity is calculated for gravitational-wave interferometers with Fabry-Perot arms, similar to those being installed at the Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Italian-French Laser Interferometer Collaboration (VIRGO) facility. This calculation includes the effect of nonstationary shot noise that is due to phase modulation of the light. The resulting formula is experimentally verified by a test interferometer with suspended mirrors in the 40-m arms. PMID:18354690

  9. Parametric resonance and cosmological gravitational waves

    SciTech Connect

    Sa, Paulo M.; Henriques, Alfredo B.

    2008-03-15

    We investigate the production of gravitational waves due to quantum fluctuations of the vacuum during the transition from the inflationary to the radiation-dominated eras of the universe, assuming this transition to be dominated by the phenomenon of parametric resonance. The energy spectrum of the gravitational waves is calculated using the method of continuous Bogoliubov coefficients, which avoids the problem of overproduction of gravitons at large frequencies. We found, on the sole basis of the mechanism of quantum fluctuations, that the resonance field leaves no explicit and distinctive imprint on the gravitational-wave energy spectrum, apart from an overall upward or downward translation. Therefore, the main features in the spectrum are due to the inflaton field, which leaves a characteristic imprint at frequencies of the order of MHz/GHz.

  10. The North Pole Environmental Observatory

    NASA Astrophysics Data System (ADS)

    Morison, J.; Aagaard, K.; Falkner, K.; Heiberg, A.; McPhee, M.; Moritz, D.; Overland, J.; Perovich, D.; Richter-Menge, J.; Shimada, K.; Steele, M.; Takizawa, T.; Woodgate, R.

    2001-12-01

    The Arctic environment is changing. The North Pole Environmental Observatory (NPEO) was established as a type of program of long-term observations required to understand Arctic change. The North Pole region was chosen because it is central to observed changes, there is a reasonable past history of measurements, and there is often a large gap there in the coverage of surface measurements. NPEO has three main components, (1) an automated drifting station composed of several buoys to measure atmospheric, upper ocean, and ice variables, (2) a sub-surface mooring at the Pole measuring ocean properties and ice draft, and (3) an airborne hydrographic survey that provides a snapshot spatial description of upper ocean properties. The first observatory was established at the Pole in April 2000 by aircraft flying out of Alert. The drifting station portion consisted of ocean ice and meteorological buoys. Over one year the drifting station passed south through Fram Strait and stopped operating in the Greenland Sea. The airborne hydrographic survey made 6 stations between Alert, the Pole, and beyond. The sub-surface mooring was not deployed. In 2001 the drifting station was similar, but the operation was expanded to deploy a 4000-m mooring at the Pole. The mooring includes current meters, C-T sensors, ADCP, and an ice draft-profiling sonar. It will be recovered in 2002. The hydrographic survey covered a new line from the Pole to 85N, 170W. The 2000 hydrographic survey showed that the changes characterizing the Pole region in the 1990s persist, but with some deepening and some slight retreat toward climatology. The section from Alert shows that upper ocean conditions near the coast have become much like the Western Arctic with low mixed layer salinity and a secondary shallow temperature maximum. The observations indicate a general counterclockwise shift in water mass locations. Among other things, the NPEO 2000 drifting station data indicate the cold halocline is still thinner

  11. Search for gravitational wave radiation associated with the pulsating tail of the SGR 1806-20 hyperflare of 27 December 2004 using LIGO

    NASA Astrophysics Data System (ADS)

    Abbott, B.; Abbott, R.; Adhikari, R.; Agresti, J.; Ajith, P.; Allen, B.; Amin, R.; Anderson, S. B.; Anderson, W. G.; Arain, M.; Araya, M.; Armandula, H.; Ashley, M.; Aston, S.; Aufmuth, P.; Aulbert, C.; Babak, S.; Ballmer, S.; Bantilan, H.; Barish, B. C.; Barker, C.; Barker, D.; Barr, B.; Barriga, P.; Barton, M. A.; Bayer, K.; Belczynski, K.; Betzwieser, J.; Beyersdorf, P. T.; Bhawal, B.; Bilenko, I. A.; Billingsley, G.; Biswas, R.; Black, E.; Blackburn, K.; Blackburn, L.; Blair, D.; Bland, B.; Bogenstahl, J.; Bogue, L.; Bork, R.; Boschi, V.; Bose, S.; Brady, P. R.; Braginsky, V. B.; Brau, J. E.; Brinkmann, M.; Brooks, A.; Brown, D. A.; Bullington, A.; Bunkowski, A.; Buonanno, A.; Burmeister, O.; Busby, D.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Camp, J. B.; Cannizzo, J.; Cannon, K.; Cantley, C. A.; Cao, J.; Cardenas, L.; Casey, M. M.; Castaldi, G.; Cepeda, C.; Chalkey, E.; Charlton, P.; Chatterji, S.; Chelkowski, S.; Chen, Y.; Chiadini, F.; Chin, D.; Chin, E.; Chow, J.; Christensen, N.; Clark, J.; Cochrane, P.; Cokelaer, T.; Colacino, C. N.; Coldwell, R.; Conte, R.; Cook, D.; Corbitt, T.; Coward, D.; Coyne, D.; Creighton, J. D. E.; Creighton, T. D.; Croce, R. P.; Crooks, D. R. M.; Cruise, A. M.; Cumming, A.; Dalrymple, J.; D'Ambrosio, E.; Danzmann, K.; Davies, G.; Debra, D.; Degallaix, J.; Degree, M.; Demma, T.; Dergachev, V.; Desai, S.; Desalvo, R.; Dhurandhar, S.; Díaz, M.; Dickson, J.; di Credico, A.; Diederichs, G.; Dietz, A.; Doomes, E. E.; Drever, R. W. P.; Dumas, J.-C.; Dupuis, R. J.; Dwyer, J. G.; Ehrens, P.; Espinoza, E.; Etzel, T.; Evans, M.; Evans, T.; Fairhurst, S.; Fan, Y.; Fazi, D.; Fejer, M. M.; Finn, L. S.; Fiumara, V.; Fotopoulos, N.; Franzen, A.; Franzen, K. Y.; Freise, A.; Frey, R.; Fricke, T.; Fritschel, P.; Frolov, V. V.; Fyffe, M.; Galdi, V.; Garofoli, J.; Gholami, I.; Giaime, J. A.; Giampanis, S.; Giardina, K. D.; Goda, K.; Goetz, E.; Goggin, L.; González, G.; Gossler, S.; Grant, A.; Gras, S.; Gray, C.; Gray, M.; Greenhalgh, J.; Gretarsson, A. M.; Grosso, R.; Grote, H.; Grunewald, S.; Guenther, M.; Gustafson, R.; Hage, B.; Hammer, D.; Hanna, C.; Hanson, J.; Harms, J.; Harry, G.; Harstad, E.; Hayler, T.; Heefner, J.; Heng, I. S.; Heptonstall, A.; Heurs, M.; Hewitson, M.; Hild, S.; Hirose, E.; Hoak, D.; Hosken, D.; Hough, J.; Howell, E.; Hoyland, D.; Huttner, S. H.; Ingram, D.; Innerhofer, E.; Ito, M.; Itoh, Y.; Ivanov, A.; Jackrel, D.; Johnson, B.; Johnson, W. W.; Jones, D. I.; Jones, G.; Jones, R.; Ju, L.; Kalmus, P.; Kalogera, V.; Kamat, S.; Kasprzyk, D.; Katsavounidis, E.; Kawabe, K.; Kawamura, S.; Kawazoe, F.; Kells, W.; Keppel, D. G.; Khalili, F. Ya.; Kim, C.; King, P.; Kissel, J. S.; Klimenko, S.; Kokeyama, K.; Kondrashov, V.; Kopparapu, R. K.; Kozak, D.; Krishnan, B.; Kwee, P.; Lam, P. K.; Landry, M.; Lantz, B.; Lazzarini, A.; Lee, B.; Lei, M.; Leiner, J.; Leonhardt, V.; Leonor, I.; Libbrecht, K.; Lindquist, P.; Lockerbie, N. A.; Longo, M.; Lormand, M.; Lubiński, M.; Lück, H.; Machenschalk, B.; Macinnis, M.; Mageswaran, M.; Mailand, K.; Malec, M.; Mandic, V.; Marano, S.; Márka, S.; Markowitz, J.; Maros, E.; Martin, I.; Marx, J. N.; Mason, K.; Matone, L.; Matta, V.; Mavalvala, N.; McCarthy, R.; McClelland, D. E.; McGuire, S. C.; McHugh, M.; McKenzie, K.; McNabb, J. W. C.; McWilliams, S.; Meier, T.; Melissinos, A.; Mendell, G.; Mercer, R. A.; Meshkov, S.; Messaritaki, E.; Messenger, C. J.; Meyers, D.; Mikhailov, E.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Miyakawa, O.; Mohanty, S.; Moreno, G.; Mossavi, K.; Mowlowry, C.; Moylan, A.; Mudge, D.; Mueller, G.; Mukherjee, S.; Müller-Ebhardt, H.; Munch, J.; Murray, P.; Myers, E.; Myers, J.; Nash, T.; Newton, G.; Nishizawa, A.; Numata, K.; O'Reilly, B.; O'Shaughnessy, R.; Ottaway, D. J.; Overmier, H.; Owen, B. J.; Pan, Y.; Papa, M. A.; Parameshwaraiah, V.; Patel, P.; Pedraza, M.; Penn, S.; Pierro, V.; Pinto, I. M.; Pitkin, M.; Pletsch, H.; Plissi, M. V.; Postiglione, F.; Prix, R.; Quetschke, V.; Raab, F.; Rabeling, D.; Radkins, H.; Rahkola, R.; Rainer, N.; Rakhmanov, M.; Rawlins, K.; Ray-Majumder, S.; Re, V.; Rehbein, H.; Reid, S.; Reitze, D. H.; Ribichini, L.; Riesen, R.; Riles, K.; Rivera, B.; Robertson, N. A.; Robinson, C.; Robinson, E. L.; Roddy, S.; Rodriguez, A.; Rogan, A. M.; Rollins, J.; Romano, J. D.; Romie, J.; Route, R.; Rowan, S.; Rüdiger, A.; Ruet, L.; Russell, P.; Ryan, K.; Sakata, S.; Samidi, M.; de La Jordana, L. Sancho; Sandberg, V.; Sannibale, V.; Saraf, S.; Sarin, P.; Sathyaprakash, B. S.; Sato, S.; Saulson, P. R.; Savage, R.; Savov, P.; Schediwy, S.; Schilling, R.; Schnabel, R.; Schofield, R.; Schutz, B. F.; Schwinberg, P.; Scott, S. M.; Searle, A. C.; Sears, B.; Seifert, F.; Sellers, D.; Sengupta, A. S.; Shawhan, P.; Shoemaker, D. H.; Sibley, A.; Sidles, J. A.; Siemens, X.; Sigg, D.; Sinha, S.; Sintes, A. M.; Slagmolen, B. J. J.; Slutsky, J.; Smith, J. R.; Smith, M. R.; Somiya, K.; Strain, K. A.; Strom, D. M.; Stuver, A.; Summerscales, T. Z.; Sun, K.-X.; Sung, M.; Sutton, P. J.; Takahashi, H.; Tanner, D. B.; Tarallo, M.; Taylor, R.; Taylor, R.; Thacker, J.; Thorne, K. A.; Thorne, K. S.; Thüring, A.; Tinto, M.; Tokmakov, K. V.; Torres, C.; Torrie, C.; Traylor, G.; Trias, M.; Tyler, W.; Ugolini, D.; Ungarelli, C.; Urbanek, K.; Vahlbruch, H.; Vallisneri, M.; van den Broeck, C.; Varvella, M.; Vass, S.; Vecchio, A.; Veitch, J.; Veitch, P.; Villar, A.; Vorvick, C.; Vyachanin, S. P.; Waldman, S. J.; Wallace, L.; Ward, H.; Ward, R.; Watts, K.; Webber, D.; Weidner, A.; Weinert, M.; Weinstein, A.; Weiss, R.; Wen, S.; Wette, K.; Whelan, J. T.; Whitbeck, D. M.; Whitcomb, S. E.; Whiting, B. F.; Wilkinson, C.; Willems, P. A.; Williams, L.; Willke, B.; Wilmut, I.; Winkler, W.; Wipf, C. C.; Wise, S.; Wiseman, A. G.; Woan, G.; Woods, D.; Wooley, R.; Worden, J.; Wu, W.; Yakushin, I.; Yamamoto, H.; Yan, Z.; Yoshida, S.; Yunes, N.; Zanolin, M.; Zhang, J.; Zhang, L.; Zhao, C.; Zotov, N.; Zucker, M.; Zur Mühlen, H.; Zweizig, J.

    2007-09-01

    We have searched for gravitational waves (GWs) associated with the SGR 1806-20 hyperflare of 27 December 2004. This event, originating from a Galactic neutron star, displayed exceptional energetics. Recent investigations of the x-ray light curve’s pulsating tail revealed the presence of quasiperiodic oscillations (QPOs) in the 30 2000 Hz frequency range, most of which coincides with the bandwidth of the LIGO detectors. These QPOs, with well-characterized frequencies, can plausibly be attributed to seismic modes of the neutron star which could emit GWs. Our search targeted potential quasimonochromatic GWs lasting for tens of seconds and emitted at the QPO frequencies. We have observed no candidate signals above a predetermined threshold, and our lowest upper limit was set by the 92.5 Hz QPO observed in the interval from 150 s to 260 s after the start of the flare. This bound corresponds to a (90% confidence) root-sum-squared amplitude hrss-det⁡90%=4.5×10-22strainHz-1/2 on the GW waveform strength in the detectable polarization state reaching our Hanford (WA) 4 km detector. We illustrate the astrophysical significance of the result via an estimated characteristic energy in GW emission that we would expect to be able to detect. The above result corresponds to 7.7×1046erg (=4.3×10-8M⊙c2), which is of the same order as the total (isotropic) energy emitted in the electromagnetic spectrum. This result provides a means to probe the energy reservoir of the source with the best upper limit on the GW waveform strength published and represents the first broadband asteroseismology measurement using a GW detector.

  12. Search for gravitational wave radiation associated with the pulsating tail of the SGR 1806-20 hyperflare of 27 December 2004 using LIGO

    SciTech Connect

    Abbott, B.; Abbott, R.; Adhikari, R.; Agresti, J.; Anderson, S. B.; Araya, M.; Armandula, H.; Ballmer, S.; Barish, B. C.; Bhawal, B.; Billingsley, G.; Black, E.; Blackburn, K.; Bork, R.; Boschi, V.; Busby, D.; Cardenas, L.; Cepeda, C.; Chatterji, S.; Coyne, D.

    2007-09-15

    We have searched for gravitational waves (GWs) associated with the SGR 1806-20 hyperflare of 27 December 2004. This event, originating from a Galactic neutron star, displayed exceptional energetics. Recent investigations of the x-ray light curve's pulsating tail revealed the presence of quasiperiodic oscillations (QPOs) in the 30-2000 Hz frequency range, most of which coincides with the bandwidth of the LIGO detectors. These QPOs, with well-characterized frequencies, can plausibly be attributed to seismic modes of the neutron star which could emit GWs. Our search targeted potential quasimonochromatic GWs lasting for tens of seconds and emitted at the QPO frequencies. We have observed no candidate signals above a predetermined threshold, and our lowest upper limit was set by the 92.5 Hz QPO observed in the interval from 150 s to 260 s after the start of the flare. This bound corresponds to a (90% confidence) root-sum-squared amplitude h{sub rss-det}{sup 90%} = 4.5x10{sup -22} strain Hz{sup -1/2} on the GW waveform strength in the detectable polarization state reaching our Hanford (WA) 4 km detector. We illustrate the astrophysical significance of the result via an estimated characteristic energy in GW emission that we would expect to be able to detect. The above result corresponds to 7.7x10{sup 46} erg (=4.3x10{sup -8} M{sub {center_dot}}c{sup 2}), which is of the same order as the total (isotropic) energy emitted in the electromagnetic spectrum. This result provides a means to probe the energy reservoir of the source with the best upper limit on the GW waveform strength published and represents the first broadband asteroseismology measurement using a GW detector.

  13. Ancient "Observatories" - A Relevant Concept?

    NASA Astrophysics Data System (ADS)

    Belmonte, Juan Antonio

    It is quite common, when reading popular books on astronomy, to see a place referred to as "the oldest observatory in the world". In addition, numerous books on archaeoastronomy, of various levels of quality, frequently refer to the existence of "prehistoric" or "ancient" observatories when describing or citing monuments that were certainly not built with the primary purpose of observing the skies. Internet sources are also guilty of this practice. In this chapter, the different meanings of the word observatory will be analyzed, looking at how their significances can be easily confused or even interchanged. The proclaimed "ancient observatories" are a typical result of this situation. Finally, the relevance of the concept of the ancient observatory will be evaluated.

  14. LIGO and the Search for Gravitational Waves

    SciTech Connect

    Robertson, Norna A.

    2006-10-16

    Gravitational waves, predicted to exist by Einstein's General Theory of Relativity but as yet undetected, are expected to be emitted during violent astrophysical events such as supernovae, black hole interactions and the coalescence of compact binary systems. Their detection and study should lead to a new branch of astronomy. However the experimental challenge is formidable: ground-based detection relies on sensing displacements of order 10{sup -18} m over a frequency range of tens of hertz to a few kHz. There is currently a large international effort to commission and operate long baseline interferometric detectors including those that comprise LIGO - the Laser Interferometer Gravitational-Wave Observatory - in the USA. In this talk I will give an introduction to the topic of gravitational wave detection and in particular review the status of the LIGO project which is currently taking data at its design sensitivity. I will also look to the future to consider planned improvements in sensitivity for such detectors, focusing on Advanced LIGO, the proposed upgrade to the LIGO project.

  15. Gravitational-wave joy

    NASA Astrophysics Data System (ADS)

    seyithocuk; jjeherrera; eltodesukane; GrahamRounce; rloldershaw; Beaker, Dr; Sandhu, G. S.; Ophiuchi

    2016-03-01

    In reply to the news article on the LIGO collaboration's groundbreaking detection of gravitational waves, first predicted by Einstein 100 years ago, from two black holes colliding (pp5, 6-7 and http://ow.ly/Ylsyt).

  16. Observation of Gravitational Waves

    NASA Astrophysics Data System (ADS)

    Gonzalez, Gabriela

    2016-06-01

    On September 14 2015, the two LIGO gravitational wave detectors in Hanford, Washington and Livingston, Louisiana registered a nearly simultaneous signal with time-frequency properties consistent with gravitational-wave emission by the merger of two massive compact objects. Further analysis of the signals by the LIGO Scientific Collaboration and Virgo Collaboration revealed that the gravitational waves detected by LIGO came from the merger of a binary black hole (BBH) system approximately 420 Mpc distant (z=0.09) with constituent masses of 36 and 29 M_sun. I will describe the details of the observation, the status of ground-based interferometric detectors, and prospects for future observations in the new era of gravitational wave astronomy.

  17. Yang-Mills Gravity in Flat Space-Time II:. Gravitational Radiations and Lee-Yang Force for Accelerated Cosmic Expansion

    NASA Astrophysics Data System (ADS)

    Hsu, Jong-Ping

    Within Yang-Mills gravity with translation group T(4) in flat space-time, the invariant action involving quadratic translation gauge-curvature leads to quadrupole radiations, which are shown to be consistent with experiments. The radiation power turns out to be the same as that in Einstein's gravity to the second-order approximation. We also discuss an interesting physical reason for the accelerated cosmic expansion based on the long-range Lee-Yang force of Ub(1) gauge field associated with the established conservation law of baryon number. We show that the Lee-Yang force can be related to a linear potential ∝ r, provided the gauge field satisfies a fourth-order differential equation in flat space-time. Furthermore, we consider an experimental test of the Lee-Yang force related to the accelerated cosmic expansion. The necessity of generalizing Lorentz transformations for accelerated frames of reference and accelerated Wu-Doppler effects are briefly discussed.

  18. VESO: Virtual Earth-Sun Observatory

    NASA Astrophysics Data System (ADS)

    Gonzalez-Esparza, A.; Cifuentes-Nava, G.; Hernandez-Quintero, E.; Lara-Sanchez, A.; Valdes-Galicia, J. F.

    2007-12-01

    We present the Virtual Earth-Sun Observatory (VESO) at the web site http://www.veso.unam.mx. This site shows a real time integrated database obtained from four instruments of the Instituto de Geofisica-UNAM studying Sun- Earth connection phenomena. (1) The Solar Radio Interferometer (RIS, Radio Interferómetro Solar) measures the lower solar atmosphere radiation at 7.5 GHz, revealing microwave bursts associated with solar activity. (2) The Mexican Array Radio Telescope (MEXART, Observatorio de Centelleo Interplanetario de Coeneo) will detect solar wind large-scale disturbances between Sun and Earth(e.g., Interplanetary counterparts of Coronal Mass Ejections (ICMES)and Stream Interaction Regions (SIR)) employing the interplanetary scintillation technique (IPS) operating at 140 MHz. (3) The Cosmic Ray Observatory (RC) detects high energy galactic and solar particles, whose flow is affected by magnetic disturbances in the solar wind, and (4) the Teoloyucan Geomagnetic Observatory (TEO) measures the variations in the Earth´s magnetic field. The VESO instruments provide data from four different points of the complex chain of the solar terrestrial relations and allow the study of intense solar events and in possible consequences in causing geomagnetic activity. The VESO project is part of the celebration of the International Heliophysical Year (IHY) and the Electronic Geophysical Year (EGY) in Mexico.

  19. Binary Black Holes and Gravitational Waves

    NASA Technical Reports Server (NTRS)

    Centrella, Joan

    2007-01-01

    The final merger of two black holes releases a tremendous amount of energy, more than the combined light from all the stars in the visible universe. This energy is emitted in the form of gravitational waves, and observing these sources with gravitational wave detectors such as LIGO and LISA requires that we know the pattern or fingerprint of the radiation emitted. Since black hole mergers take place in regions of extreme gravitational fields, we need to solve Einstein's equations of general relativity on a computer in order to calculate these wave patterns. For more than 30 years, scientists have tried to compute these wave patterns. However, their computer codes have been plagued by problems that caused them to crash. This situation has changed dramatically in the past 2 years, with a series of amazing breakthroughs. This discussion examines these gravitational patterns, showing how a spacetime is constructed on a computer to build a simulation laboratory for binary black hole mergers. The focus is on recent advances that are revealing these waveforms, and the dramatic new potential for discoveries that arises when these sources will be observed by the space-based gravitational wave detector LISA.

  20. Relativistic theory of gravitation

    SciTech Connect

    Logunov, A.A.; Mestvirishvili, M.A.

    1986-01-01

    In the present paper a relativistic theory of gravitation (RTG) is unambiguously constructed on the basis of the special relativity and geometrization principle. In this a gravitational field is treated as the Faraday--Maxwell spin-2 and spin-0 physical field possessing energy and momentum. The source of a gravitational field is the total conserved energy-momentum tensor of matter and of a gravitational field in Minkowski space. In the RTG the conservation laws are strictly fulfilled for the energy-moment and for the angular momentum of matter and a gravitational field. The theory explains the whole available set of experiments on gravity. By virtue of the geometrization principle, the Riemannian space in our theory is of field origin, since it appears as an effective force space due to the action of a gravitational field on matter. The RTG leads to an exceptionally strong prediction: The universe is not closed but just ''flat.'' This suggests that in the universe a ''missing mass'' should exist in a form of matter.

  1. Detectability of Gravitational Waves from High-Redshift Binaries

    NASA Astrophysics Data System (ADS)

    Rosado, Pablo A.; Lasky, Paul D.; Thrane, Eric; Zhu, Xingjiang; Mandel, Ilya; Sesana, Alberto

    2016-03-01

    Recent nondetection of gravitational-wave backgrounds from pulsar timing arrays casts further uncertainty on the evolution of supermassive black hole binaries. We study the capabilities of current gravitational-wave observatories to detect individual binaries and demonstrate that, contrary to conventional wisdom, some are, in principle, detectable throughout the Universe. In particular, a binary with rest-frame mass ≳1010M⊙ can be detected by current timing arrays at arbitrarily high redshifts. The same claim will apply for less massive binaries with more sensitive future arrays. As a consequence, future searches for nanohertz gravitational waves could be expanded to target evolving high-redshift binaries. We calculate the maximum distance at which binaries can be observed with pulsar timing arrays and other detectors, properly accounting for redshift and using realistic binary waveforms.

  2. Detectability of Gravitational Waves from High-Redshift Binaries.

    PubMed

    Rosado, Pablo A; Lasky, Paul D; Thrane, Eric; Zhu, Xingjiang; Mandel, Ilya; Sesana, Alberto

    2016-03-11

    Recent nondetection of gravitational-wave backgrounds from pulsar timing arrays casts further uncertainty on the evolution of supermassive black hole binaries. We study the capabilities of current gravitational-wave observatories to detect individual binaries and demonstrate that, contrary to conventional wisdom, some are, in principle, detectable throughout the Universe. In particular, a binary with rest-frame mass ≳10^{10}M_{⊙} can be detected by current timing arrays at arbitrarily high redshifts. The same claim will apply for less massive binaries with more sensitive future arrays. As a consequence, future searches for nanohertz gravitational waves could be expanded to target evolving high-redshift binaries. We calculate the maximum distance at which binaries can be observed with pulsar timing arrays and other detectors, properly accounting for redshift and using realistic binary waveforms. PMID:27015470

  3. First upper limits from LIGO on gravitational wave bursts

    NASA Astrophysics Data System (ADS)

    Abbott, B.; Abbott, R.; Adhikari, R.; Ageev, A.; Allen, B.; Amin, R.; Anderson, S. B.; Anderson, W. G.; Araya, M.; Armandula, H.; Asiri, F.; Aufmuth, P.; Aulbert, C.; Babak, S.; Balasubramanian, R.; Ballmer, S.; Barish, B. C.; Barker, D.; Barker-Patton, C.; Barnes, M.; Barr, B.; Barton, M. A.; Bayer, K.; Beausoleil, R.; Belczynski, K.; Bennett, R.; Berukoff, S. J.; Betzwieser, J.; Bhawal, B.; Bilenko, I. A.; Billingsley, G.; Black, E.; Blackburn, K.; Bland-Weaver, B.; Bochner, B.; Bogue, L.; Bork, R.; Bose, S.; Brady, P. R.; Braginsky, V. B.; Brau, J. E.; Brown, D. A.; Brozek, S.; Bullington, A.; Buonanno, A.; Burgess, R.; Busby, D.; Butler, W. E.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Camp, J. B.; Cantley, C. A.; Cardenas, L.; Carter, K.; Casey, M. M.; Castiglione, J.; Chandler, A.; Chapsky, J.; Charlton, P.; Chatterji, S.; Chen, Y.; Chickarmane, V.; Chin, D.; Christensen, N.; Churches, D.; Colacino, C.; Coldwell, R.; Coles, M.; Cook, D.; Corbitt, T.; Coyne, D.; Creighton, J. D.; Creighton, T. D.; Crooks, D. R.; Csatorday, P.; Cusack, B. J.; Cutler, C.; D'Ambrosio, E.; Danzmann, K.; Davies, R.; Daw, E.; Debra, D.; Delker, T.; Desalvo, R.; Dhurandhar, S.; Díaz, M.; Ding, H.; Drever, R. W.; Dupuis, R. J.; Ebeling, C.; Edlund, J.; Ehrens, P.; Elliffe, E. J.; Etzel, T.; Evans, M.; Evans, T.; Fallnich, C.; Farnham, D.; Fejer, M. M.; Fine, M.; Finn, L. S.; Flanagan, E.; Freise, A.; Frey, R.; Fritschel, P.; Frolov, V.; Fyffe, M.; Ganezer, K. S.; Giaime, J. A.; Gillespie, A.; Goda, K.; González, G.; Goßler, S.; Grandclément, P.; Grant, A.; Gray, C.; Gretarsson, A. M.; Grimmett, D.; Grote, H.; Grunewald, S.; Guenther, M.; Gustafson, E.; Gustafson, R.; Hamilton, W. O.; Hammond, M.; Hanson, J.; Hardham, C.; Harry, G.; Hartunian, A.; Heefner, J.; Hefetz, Y.; Heinzel, G.; Heng, I. S.; Hennessy, M.; Hepler, N.; Heptonstall, A.; Heurs, M.; Hewitson, M.; Hindman, N.; Hoang, P.; Hough, J.; Hrynevych, M.; Hua, W.; Ingley, R.; Ito, M.; Itoh, Y.; Ivanov, A.; Jennrich, O.; Johnson, W. W.; Johnston, W.; Jones, L.; Jungwirth, D.; Kalogera, V.; Katsavounidis, E.; Kawabe, K.; Kawamura, S.; Kells, W.; Kern, J.; Khan, A.; Killbourn, S.; Killow, C. J.; Kim, C.; King, C.; King, P.; Klimenko, S.; Kloevekorn, P.; Koranda, S.; Kötter, K.; Kovalik, J.; Kozak, D.; Krishnan, B.; Landry, M.; Langdale, J.; Lantz, B.; Lawrence, R.; Lazzarini, A.; Lei, M.; Leonhardt, V.; Leonor, I.; Libbrecht, K.; Lindquist, P.; Liu, S.; Logan, J.; Lormand, M.; Lubiński, M.; Lück, H.; Lyons, T. T.; Machenschalk, B.; Macinnis, M.; Mageswaran, M.; Mailand, K.; Majid, W.; Malec, M.; Mann, F.; Marin, A.; Márka, S.; Maros, E.; Mason, J.; Mason, K.; Matherny, O.; Matone, L.; Mavalvala, N.; McCarthy, R.; McClelland, D. E.; McHugh, M.; McNamara, P.; Mendell, G.; Meshkov, S.; Messenger, C.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Miyakawa, O.; Miyoki, S.; Mohanty, S.; Moreno, G.; Mossavi, K.; Mours, B.; Mueller, G.; Mukherjee, S.; Myers, J.; Nagano, S.; Nash, T.; Naundorf, H.; Nayak, R.; Newton, G.; Nocera, F.; Nutzman, P.; Olson, T.; O'Reilly, B.; Ottaway, D. J.; Ottewill, A.; Ouimette, D.; Overmier, H.; Owen, B. J.; Papa, M. A.; Parameswariah, C.; Parameswariah, V.; Pedraza, M.; Penn, S.; Pitkin, M.; Plissi, M.; Pratt, M.; Quetschke, V.; Raab, F.; Radkins, H.; Rahkola, R.; Rakhmanov, M.; Rao, S. R.; Redding, D.; Regehr, M. W.; Regimbau, T.; Reilly, K. T.; Reithmaier, K.; Reitze, D. H.; Richman, S.; Riesen, R.; Riles, K.; Rizzi, A.; Robertson, D. I.; Robertson, N. A.; Robison, L.; Roddy, S.; Rollins, J.; Romano, J. D.; Romie, J.; Rong, H.; Rose, D.; Rotthoff, E.; Rowan, S.; Rüdiger, A.; Russell, P.; Ryan, K.; Salzman, I.; Sanders, G. H.; Sannibale, V.; Sathyaprakash, B.; Saulson, P. R.; Savage, R.; Sazonov, A.; Schilling, R.; Schlaufman, K.; Schmidt, V.; Schofield, R.; Schrempel, M.; Schutz, B. F.; Schwinberg, P.; Scott, S. M.; Searle, A. C.; Sears, B.; Seel, S.; Sengupta, A. S.; Shapiro, C. A.; Shawhan, P.; Shoemaker, D. H.; Shu, Q. Z.; Sibley, A.; Siemens, X.; Sievers, L.; Sigg, D.; Sintes, A. M.; Skeldon, K.; Smith, J. R.; Smith, M.; Smith, M. R.; Sneddon, P.; Spero, R.; Stapfer, G.; Strain, K. A.; Strom, D.; Stuver, A.; Summerscales, T.; Sumner, M. C.; Sutton, P. J.; Sylvestre, J.; Takamori, A.; Tanner, D. B.; Tariq, H.; Taylor, I.; Taylor, R.; Thorne, K. S.; Tibbits, M.; Tilav, S.; Tinto, M.; Tokmakov, K. V.; Torres, C.; Torrie, C.; Traeger, S.; Traylor, G.; Tyler, W.; Ugolini, D.; Vallisneri, M.; van Putten, M.; Vass, S.; Vecchio, A.; Vorvick, C.; Vyachanin, S. P.; Wallace, L.; Walther, H.; Ward, H.; Ware, B.; Watts, K.; Webber, D.; Weidner, A.; Weiland, U.; Weinstein, A.; Weiss, R.; Welling, H.; Wen, L.; Wen, S.; Whelan, J. T.; Whitcomb, S. E.; Whiting, B. F.; Willems, P. A.; Williams, P. R.; Williams, R.; Willke, B.; Wilson, A.; Winjum, B. J.; Winkler, W.

    2004-05-01

    We report on a search for gravitational wave bursts using data from the first science run of the Laser Interferometer Gravitational Wave Observatory (LIGO) detectors. Our search focuses on bursts with durations ranging from 4 to 100 ms, and with significant power in the LIGO sensitivity band of 150 to 3000 Hz. We bound the rate for such detected bursts at less than 1.6 events per day at a 90% confidence level. This result is interpreted in terms of the detection efficiency for ad hoc waveforms (Gaussians and sine Gaussians) as a function of their root-sum-square strain hrss; typical sensitivities lie in the range hrss˜10-19 10-17 strain/√(Hz), depending on the waveform. We discuss improvements in the search method that will be applied to future science data from LIGO and other gravitational wave detectors.

  4. Chandra X-Ray Observatory Concept

    NASA Technical Reports Server (NTRS)

    1995-01-01

    This is an artist's concept of the Chandra X-Ray Observatory (CXO), formerly Advanced X-Ray Astrophysics Facility (AXAF), fully developed in orbit in a star field with Earth. In 1999, the AXAF was renamed the CXO in honor of the late Indian-American Novel Laureate Subrahmanyan Chandrasekhar. The CXO is the most sophisticated and the world's most powerful x-ray telescope ever built. It is designed to observe x-rays from high energy regions of the Universe, such as hot gas in the renmants of exploded stars. It produces picture-like images of x-ray emissions analogous to those made in visible light, as well as gathers data on the chemical composition of x-ray radiating objects. The CXO helps astronomers world-wide better understand the structure and evolution of the universe by studying powerful sources of x-ray such as exploding stars, matter falling into black holes, and other exotic celestial objects. The Observatory has three major parts: (1) the x-ray telescope, whose mirrors will focus x-rays from celestial objects; (2) the science instruments that record the x-rays so that x-ray images can be produced and analyzed; and (3) the spacecraft, which provides the environment necessary for the telescope and the instruments to work. TRW, Inc. was the prime contractor for the development the CXO and NASA's Marshall Space Flight Center was responsible for its project management. The Smithsonian Astrophysical Observatory controls science and flight operations of the CXO for NASA from Cambridge, Massachusetts. The Observatory was launched July 22, 1999 aboard the Space Shuttle Columbia, STS-93 mission. (Image courtesy of TRW).

  5. Chandra X-Ray Observatory Concept

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This is a computer rendering of the fully developed Chandra X-ray Observatory (CXO), formerly Advanced X-Ray Astrophysics Facility (AXAF), in orbit in a star field. In 1999, the AXAF was renamed the CXO in honor of the late Indian-American Novel Laureate Subrahmanyan Chandrasekhar. The CXO is the most sophisticated and the world's most powerful x-ray telescope ever built. It is designed to observe x-rays from high energy regions of the Universe, such as hot gas in the renmants of exploded stars. It produces picture-like images of x-ray emissions analogous to those made in visible light, as well as gathers data on the chemical composition of x-ray radiating objects. The CXO helps astronomers world-wide better understand the structure and evolution of the universe by studying powerful sources of x-rays such as exploding stars, matter falling into black holes, and other exotic celestial objects. The Observatory has three major parts: (1) the x-ray telescope, whose mirrors will focus x-rays from celestial objects; (2) the science instruments that record the x-rays so that x-ray images can be produced and analyzed; and (3) the spacecraft, which provides the environment necessary for the telescope and the instruments to work. TRW, Inc. was the prime contractor for the development of the CXO and NASA's Marshall Space Flight Center was responsible for its project management. The Smithsonian Astrophysical Observatory controls science and flight operations of the CXO for NASA from Cambridge, Massachusetts. The Observatory was launched July 22, 1999 aboard the Space Shuttle Columbia, STS-93 mission. (Image courtesy of TRW).

  6. Chandra X-Ray Observatory Computer Rendering

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This is a computer rendering of the fully developed Chandra X-Ray Observatory (CXO), formerly Advanced X-Ray Astrophysics Facility (AXAF). In 1999, the AXAF was renamed the CXO in honor of the late Indian-American Novel Laureate Subrahmanyan Chandrasekhar. The CXO is the most sophisticated and the world's most powerful x-ray telescope ever built. It is designed to observe x-rays from high energy regions of the Universe, such as hot gas in the renmants of exploded stars. It produces picture-like images of x-ray emissions analogous to those made in visible light, as well as gathers data on the chemical composition of x-ray radiating objects. The CXO helps astronomers world-wide better understand the structure and evolution of the universe by studying powerful sources of x-ray such as exploding stars, matter falling into black holes, and other exotic celestial objects. The Observatory has three major parts: (1) the x-ray telescope, whose mirrors will focus x-rays from celestial objects; (2) the science instruments that record the x-rays so that x-ray images can be produced and analyzed; and (3) the spacecraft, which provides the environment necessary for the telescope and the instruments to work. TRW, Inc. was the prime contractor for the development of the CXO and NASA's Marshall Space Flight Center was responsible for its project management. The Smithsonian Astrophysical Observatory controls science and flight operations of the CXO for NASA from Cambridge, Massachusetts. The Observatory was launched July 22, 1999 aboard the Space Shuttle Columbia, STS-93 mission. (Image courtesy of TRW).

  7. Klimovskaya: A new geomagnetic observatory

    NASA Astrophysics Data System (ADS)

    Soloviev, A. A.; Sidorov, R. V.; Krasnoperov, R. I.; Grudnev, A. A.; Khokhlov, A. V.

    2016-05-01

    In 2011 Geophysical Center RAS (GC RAS) began to deploy the Klimovskaya geomagnetic observatory in the south of Arkhangelsk region on the territory of the Institute of Physiology of Natural Adaptations, Ural Branch, Russian Academy of Sciences (IPNA UB RAS). The construction works followed the complex of preparatory measures taken in order to confirm that the observatory can be constructed on this territory and to select the optimal configuration of observatory structures. The observatory equipping stages are described in detail, the technological and design solutions are described, and the first results of the registered data quality control are presented. It has been concluded that Klimovskaya observatory can be included in INTERMAGNET network. The observatory can be used to monitor and estimate geomagnetic activity, because it is located at high latitudes and provides data in a timely manner to the scientific community via the web-site of the Russian-Ukrainian Geomagnetic Data Center. The role of ground observatories such as Klimovskaya remains critical for long-term observations of secular variation and for complex monitoring of the geomagnetic field in combination with low-orbiting satellite data.

  8. X ray timing observations and gravitational physics

    NASA Technical Reports Server (NTRS)

    Michelson, Peter F.; Wood, Kent S.

    1989-01-01

    Photon-rich x ray observations on bright compact galactic sources will make it possible to detect many fast processes that may occur in these systems on millisecond and submillisecond timescales. Many of these processes are of direct relevance to gravitational physics because they arise in regions of strong gravity near neutron stars and black holes where the dynamical timescales for compact objects of stellar mass are milliseconds. To date, such observations have been limited by the detector area and telemetry rates available. However, instruments such as the proposed X ray Large Array (XLA) would achieve collecting areas of about 100 sq m. This instrument has been described elsewhere (Wood and Michelson 1988) and was the subject of a recent prephase A feasibility study at Marshall Space Flight Center. Observations with an XLA class instrument will directly impact five primary areas of astrophysics research: the attempt to detect gravitational radiation, the study of black holes, the physics of mass accretion onto compact objects, the structure of neutron stars and nuclear matter, and the characterization of dark matter in the universe. Those observations are discussed that are most directly relevant to gravitational physics: the search for millisecond x ray pulsars that are potential sources of continuous gravitational radiation; and the use of x ray timing observations to probe the physical conditions in extreme relativistic regions of space near black holes, both stellar-sized and supermassive.

  9. Relic gravitational waves produced after preheating

    SciTech Connect

    Khlebnikov, S.; Tkachev, I. |

    1997-07-01

    We show that gravitational radiation is produced quite efficiently in interactions of classical waves created by resonant decay of a coherently oscillating field. As an important example we consider simple models of chaotic inflation, where we find that today{close_quote}s ratio of energy density in gravitational waves per octave to the critical density of the Universe can be as large as 10{sup {minus}12} at the maximal wavelength of order 10{sup 5} cm. In the pure {lambda}{phi}{sup 4}/4 model with inflaton self-coupling {lambda}=10{sup {minus}13}, the maximal today{close_quote}s wavelength of gravitational waves produced by this mechanism is of order 10{sup 6} cm, close to the upper bound of operational LIGO and TIGA frequencies. The energy density of waves in this model, though, is likely to be well below the sensitivity of LIGO or TIGA at such frequencies. We discuss the possibility that in other models the interaction of classical waves can lead to an even stronger gravitational radiation background. {copyright} {ital 1997} {ital The American Physical Society}

  10. The Solar Dynamics Observatory

    NASA Technical Reports Server (NTRS)

    Pesnell, William D.

    2008-01-01

    The Solar Dynamics Observatory (SDO) is the first Space Weather Mission in NASA's Living With a Star Program. SDO's main goal is to understand, driving towards a predictive capability, those solar variations that influence life on Earth and humanity's technological systems. The past decade has seen an increasing emphasis on understanding the entire Sun, from the nuclear reactions at the core to the development and loss of magnetic loops in the corona. SDO's three science investigations (HMI, AIA, and EVE) will determine how the Sun's magnetic field is generated and structured, how this stored magnetic energy is released into the heliosphere and geospace as the solar wind, energetic particles, and variations in the solar irradiance. SDO will return full-disk Dopplergrams, full-disk vector magnetograms, full-disk images at nine EIUV wavelengths, and EUV spectral irradiances, all taken at a rapid cadence. This means you can 'observe the database' to study events, but we can also move forward in producing quantitative models of what the Sun is doing today. SDO is scheduled to launch in 2008 on an Atlas V rocket from the Kennedy Space Center, Cape Canaveral, Florida. The satellite will fly in a 28 degree inclined geosynchronous orbit about the longitude of New Mexico, where a dedicated Ka-band ground station will receive the 150 Mbps data flow. How SDO data will transform the study of the Sun and its affect on Space Weather studies will be discussed.

  11. Gravitational-wave detection using redshifted 21-cm observations

    SciTech Connect

    Bharadwaj, Somnath; Guha Sarkar, Tapomoy

    2009-06-15

    A gravitational-wave traversing the line of sight to a distant source produces a frequency shift which contributes to redshift space distortion. As a consequence, gravitational waves are imprinted as density fluctuations in redshift space. The gravitational-wave contribution to the redshift space power spectrum has a different {mu} dependence as compared to the dominant contribution from peculiar velocities. This, in principle, allows the two signals to be separated. The prospect of a detection is most favorable at the highest observable redshift z. Observations of redshifted 21-cm radiation from neutral hydrogen hold the possibility of probing very high redshifts. We consider the possibility of detecting primordial gravitational waves using the redshift space neutral hydrogen power spectrum. However, we find that the gravitational-wave signal, though present, will not be detectable on superhorizon scales because of cosmic variance and on subhorizon scales where the signal is highly suppressed.

  12. Architecture of Chinese Virtual Observatory

    NASA Astrophysics Data System (ADS)

    Cui, Chen-Zhou; Zhao, Yong-Heng

    2004-06-01

    Virtual Observatory (VO) is brought forward under the background of progresses of astronomical technologies and information technologies. VO architecture design embodies the combination of above two technologies. As an introduction of VO, principle and workflow of Virtual Observatory are given firstly. Then the latest progress on VO architecture is introduced. Based on the Grid technology, layered architecture model and service-oriented architecture model are given for Chinese Virtual Observatory. In the last part of the paper, some problems on architecture design are discussed in detail.

  13. Development of Mykolaiv Virtual Observatory

    NASA Astrophysics Data System (ADS)

    Mazhaev, A.; Protsyuk, Yu.

    Results obtained in 2010-2013 on the development of astronomical databases and web services are presented. Mykolaiv Virtual Observatory (MVO) is a part of the Ukrainian Virtual Observatory (UkrVO). At present, MVO consists of three major databases containing data on: astrometric catalogues, photographic plates, CCD observations. The databases facilitate the process of data mining and provide easy access to the textual and graphic information on the results of observations and their reduction obtained during the whole history of Nikolaev Astronomical Observatory (NAO).

  14. Beyond concordance cosmology with magnification of gravitational-wave standard sirens.

    PubMed

    Camera, Stefano; Nishizawa, Atsushi

    2013-04-12

    We show how future gravitational-wave detectors would be able to discriminate between the concordance Λ cold dark matter cosmological model and up-to-date competing alternatives, e.g., dynamical dark energy (DE) models or modified gravity (MG) theories. Our method consists of using the weak-lensing magnification effect that affects a standard-siren signal because of its traveling through the Universe's large scale structure. As a demonstration, we present constraints on DE and MG from proposed gravitational-wave detectors, namely Einstein Telescope and DECI-Hertz Interferometer Gravitational-Wave Observatory and Big-Bang Observer. PMID:25167243

  15. Astronomers Discover Six-Image Gravitational Lens

    NASA Astrophysics Data System (ADS)

    2001-08-01

    -Smithsonian Center for Astrophysics (CfA). "When we understand this system, we will have a much clearer picture of how galaxies are changed by being part of a bigger cluster of galaxies," he added. B1359+154 was discovered in 1999 by the Cosmic Lens All-Sky Survey, an international collaboration of astronomers who use radio telescopes to search the sky for gravitational lenses. Images made by the NSF's Very Large Array in New Mexico and by Britain's MERLIN radio telescope showed six objects suspected of being gravitational-lens images, but the results were inconclusive. Rusin and his team used the VLBA and HST in 1999 and 2000 to make more-detailed studies of B1359+154. The combination of data from the VLBA and HST convinced the astronomers that B1359+154 actually consists of six lensed images of a single background galaxy. The VLBA images were made from data collected during observations at a radio frequency of 1.7 GHz. "This is a great example of modern, multi-wavelength astronomy," said Rusin. "We need the radio telescopes to detect the gravitational lenses in the first place, then we need the visible-light information from Hubble to show us additional detail about the structure of the system." Armed with the combined VLBA and HST data about the positions and brightnesses of the six images of the background galaxy as well as the positions of the three intermediate galaxies, the astronomers did computer simulations to show how the gravitation of the three galaxies could produce the lens effect. They were able to design a computer model of the system that, in fact, produces the six images seen in B1359+154. "Our computer model certainly is not perfect, and we need to do more observations of this system to refine it, but we have clearly demonstrated that the three galaxies we see can produce a six-image lens system," said Martin Norbury, a graduate student at Jodrell Bank Observatory in Britain. "We think this work will give us an excellent tool for studying much-denser clusters of

  16. Dyadosphere formed in gravitational collapse

    SciTech Connect

    Ruffini, Remo; Xue Shesheng

    2008-10-10

    We first recall the concept of Dyadosphere (electron-positron-photon plasma around a formed black holes) and its motivation, and recall on (i) the Dirac process: annihilation of electron-positron pairs to photons; (ii) the Breit-Wheeler process: production of electron-positron pairs by photons with the energy larger than electron-positron mass threshold; the Sauter-Euler-Heisenberg effective Lagrangian and rate for the process of electron-positron production in a constant electric field. We present a general formula for the pair-production rate in the semi-classical treatment of quantum mechanical tunneling. We also present in the Quantum Electro-Dynamics framework, the calculations of the Schwinger rate and effective Lagrangian for constant electromagnetic fields. We give a review on the electron-positron plasma oscillation in constant electric fields, and its interaction with photons leading to energy and number equipartition of photons, electrons and positrons. The possibility of creating an overcritical field in astrophysical condition is pointed out. We present the discussions and calculations on (i) energy extraction from gravitational collapse; (ii) the formation of Dyadosphere in gravitational collapsing process, and (iii) its hydrodynamical expansion in Reissner Nordstroem geometry. We calculate the spectrum and flux of photon radiation at the point of transparency, and make predictions for short Gamma-Ray Bursts.

  17. Constraints on singular evolution from gravitational baryogenesis

    NASA Astrophysics Data System (ADS)

    Oikonomou, V. K.

    2016-02-01

    We investigate how the gravitational baryogenesis mechanism can potentially constrain the form of a Type IV singularity. Specifically, we study two different models with interesting phenomenology, that realize two distinct Type IV singularities, one occurring at the end of inflation and one during the radiation domination era or during the matter domination era. As we demonstrate, the Type IV singularities occurring at the matter domination era or during the radiation domination era are constrained by the gravitational baryogenesis, in such a way so that these do not render the baryon to entropy ratio singular. Both the cosmological models we study cannot be realized in the context of ordinary Einstein-Hilbert gravity, and hence our work can only be realized in the context of F(R) gravity and more generally in the context of modified gravity only.

  18. History of the Marseille Observatory

    NASA Astrophysics Data System (ADS)

    Prévot, Marie-Louise; Caplan, James

    The Marseille Observatory was founded in 1702 by the Jesuit order. It was located near the Vieux Port until the 1860s, when it was taken over as an annex to the Paris Observatory, directed by Le Verrier, and moved to its present location on the Plateau Longchamp. It again became independent in 1873. For information on the early history of the observatory we are largely indebted to F.X. von Zach, who spent several years in Marseille, and who was a good friend of J. Thulis, director from 1801 to 1810. Some aspects of the foundation and early history of the observatory, and of the lives of some of the astronomers who worked there, are presented and illustrated. Our collection of old instruments and documents are described.

  19. Haystack Observatory Technology Development Center

    NASA Technical Reports Server (NTRS)

    Beaudoin, Chris; Corey, Brian; Niell, Arthur; Cappallo, Roger; Whitney, Alan

    2013-01-01

    Technology development at MIT Haystack Observatory were focused on four areas in 2012: VGOS developments at GGAO; Digital backend developments and workshop; RFI compatibility at VLBI stations; Mark 6 VLBI data system development.

  20. Islamic Astronomical Instruments and Observatories

    NASA Astrophysics Data System (ADS)

    Heidarzadeh, Tofigh

    This chapter is a brief survey of astronomical instruments being used and developed in Islamic territories from the eighth to the fifteenth centuries as well as a concise account of major observatories and observational programs in this period.

  1. The Infrared Space Observatory (ISO)

    NASA Technical Reports Server (NTRS)

    Helou, George; Kessler, Martin F.

    1995-01-01

    ISO, scheduled to launch in 1995, will carry into orbit the most sophisticated infrared observatory of the decade. Overviews of the mission, instrument payload and scientific program are given, along with a comparison of the strengths of ISO and SOFIA.

  2. On propagation of electromagnetic and gravitational waves in the expanding Universe

    NASA Astrophysics Data System (ADS)

    Gladyshev, V. O.

    2016-07-01

    The purpose of this study was to obtain an equation for the propagation time of electromagnetic and gravitational waves in the expanding Universe. The velocity of electromagnetic waves propagation depends on the velocity of the interstellar medium in the observer's frame of reference. Gravitational radiation interacts weakly with the substance, so electromagnetic and gravitational waves propagate from a remote astrophysical object to the terrestrial observer at different time. Gravitational waves registration enables the inverse problem solution - by the difference in arrival time of electromagnetic and gravitational-wave signal, we can determine the characteristics of the emitting area of the astrophysical object.

  3. The New Era of Sub-millimeter Cosmoloty: First Results from Herschel Space Observatory

    SciTech Connect

    Cooray, Asantha

    2010-12-01

    This talk will summarize some of the first science results from the Herschel Space Observatory, now imaging the universe at 100 to 500 microns. The results come from the SPIRE Instrument Team's science program (HerMES) and a separate large area survey, Herschel-ATLAS. At the sub-mm wavelengths, we are sensitive to the thermal re-radiation by dust in star-forming galaxies and previous studies had already shown the presence of a large number of galaxies in the distant universe that remain hidden to the visible light. With Herschel, we are now finally able to obtain adequate statistics on this galaxy population, their nature and evolution, and connections to galaxies we see in the local universe. I will also show several cosmological results, including studies that can be done with a large population of gravitationally lensed sub-mm galaxies by foreground massive galaxies and the dark matter properties of bright and faint sub-mm galaxies as revealed by clustering and fluctuation studies. I will also summarize the scientific goals of the Herschel-SPIRE Legacy Survey, a program proposed to ESA to cover 4000 sq. degrees with SPIRE in a fast-scan mode with the ultimate goal of recovering a catalog of 2.5 to 3 million bright sub-mm sources for future studies with ALMA, CCAT, and SPICA.

  4. The sky pattern of the linearized gravitational memory effect

    NASA Astrophysics Data System (ADS)

    Mädler, Thomas; Winicour, Jeffrey

    2016-09-01

    The gravitational memory effect leads to a net displacement in the relative positions of test particles. This memory is related to the change in the strain of the gravitational radiation field between infinite past and infinite future retarded times. There are three known sources of the memory effect: (i) the loss of energy to future null infinity by massless fields or particles, (ii) the ejection of massive particles to infinity from a bound system and (iii) homogeneous, source-free gravitational waves. In the context of linearized theory, we show that asymptotic conditions controlling these known sources of the gravitational memory effect rule out any other possible sources with physically reasonable stress–energy tensors. Except for the source-free gravitational waves, the two other known sources produce gravitational memory with E-mode radiation strain, characterized by a certain curl-free sky pattern of their polarization. Thus our results show that the only known source of B-mode gravitational memory is of primordial origin, corresponding in the linearized theory to a homogeneous wave entering from past null infinity.

  5. Gauss-Bonnet gravitational baryogenesis

    NASA Astrophysics Data System (ADS)

    Odintsov, S. D.; Oikonomou, V. K.

    2016-09-01

    In this letter we study some variant forms of gravitational baryogenesis by using higher order terms containing the partial derivative of the Gauss-Bonnet scalar coupled to the baryonic current. This scenario extends the well known theory that uses a similar coupling between the Ricci scalar and the baryonic current. One appealing feature of the scenario we study is that the predicted baryon asymmetry during a radiation domination era is non-zero. We calculate the baryon to entropy ratio for the Gauss-Bonnet term and by using the observational constraints we investigate which are the allowed forms of the R + F (G) gravity controlling the evolution. Also we briefly discuss some alternative higher order terms that can generate a non-zero baryon asymmetry, even in the conformal invariance limit.

  6. Relic gravitational waves and extended inflation

    NASA Technical Reports Server (NTRS)

    Turner, Michael S.; Wilczek, Frank

    1990-01-01

    In extended inflation, a new version of inflation where the transition from an inflationary to a radiation-dominated universe is accomplished by bubble nucleation, bubble collisions supply a potent - and potentially detectable - source of gravitational waves. The energy density in relic gravitons from bubble collisions is expected to be about 0.00005 of closure density. Their characteristic wavelength depends on the reheating temperature. If black holes are produced by bubble collisions, they will evaporate, producing shorter-wavelength gravitons.

  7. "Spaghetti" design for gravitational wave superconducting antenna

    NASA Astrophysics Data System (ADS)

    Gulian, A.; Foreman, J.; Nikoghosyan, V.; Nussinov, S.; Sica, L.; Tollaksen, J.

    2014-05-01

    A new concept for detectors of gravitational wave radiation is discussed. Estimates suggest that strain sensitivity essentially better than that of the existing devices can be achieved in the wide frequency range. Such sensitivity could be obtained with devices about one meter long. Suggested device consists of multi-billion bimetallic superconducting wires ("spaghettis") and requires cryogenic operational temperatures (~0.3K in the case considered).

  8. Cryogenic, polar lunar observatories

    NASA Technical Reports Server (NTRS)

    Burke, J. D.

    1988-01-01

    In a geological vein, it is noted that some permanently shadowed regions on the Moon could provide natural passive cooling environments for astronomical detectors. A telescope located in one of the low, dark, polar regions could operate with only passive cooling at 40 K or perhaps lower, depending on how well it could be insulated from the ground and surrounded by radiation shields to block heat and light from any nearby warm or illuminated objects.

  9. Observational evidence for gravitationally trapped massive axion(-like) particles

    NASA Astrophysics Data System (ADS)

    Dilella, L.; Zioutas, K.

    2003-04-01

    Several unexpected astrophysical observations can be explained by gravitationally captured massive axions or axion-like particles, which are produced inside the Sun or other stars and are accumulated over cosmic times. Their radiative decay in solar outer space would give rise to a `self-irradiation' of the whole star, providing the time-independent component of the corona heating source (we do not address here the flaring Sun). In analogy with the Sun-irradiated Earth atmosphere, the temperature and density gradient in the corona-chromosphere transition region is suggestive for an omnipresent irradiation of the Sun, which is the strongest evidence for the generic axion-like scenario. The same mechanism is compatible with phenomena like the solar wind, the X-rays from the dark-side of the Moon, the X-ray background radiation, the diffuse X-ray excesses (below ~1 keV), the non-cooling of oldest stars, etc. A temperature of ~106 K is observed in various places, while the radiative decay of a population of such elusive particles mimics a hot gas, which fits unexpected astrophysical X-ray observations. Furthermore, the recently reconstructed quiet solar X-ray spectrum during solar minimum supports this work, since it covers the expected energy range, and it is consistent with the result of a simulation based on Kaluza-Klein axions above ~1 keV. The derived axion luminosity (La~0.16Lsolar) fits the cosmic energy density spectrum and is compatible within 2/σ with the recent SNO result, showing the important interplay between any exotic energy loss mechanism and neutrino production. At lower energies, using also a ROSAT observation, only ~3% of the X-ray intensity is explained. Data from orbiting X-ray telescopes provide upper limits for particle decay rates 1 a.u. from the Sun, and suggest new types of searches on Earth or in space. In particular, X-ray observatories, with an unrivalled equivalent fiducial volume of ~103 m3 for the 0.1-10 keV range, can search for the

  10. Sofia Observatory Performance and Characterization

    NASA Technical Reports Server (NTRS)

    Temi, Pasquale; Miller, Walter; Dunham, Edward; McLean, Ian; Wolf, Jurgen; Becklin, Eric; Bida, Tom; Brewster, Rick; Casey, Sean; Collins, Peter; Jakob, Holger; Killebrew, Jana; Lampater, Ulrich; Mandushev, Georgi; Marcum, Pamela; Meyer, Allan; Pfueller, Enrico; Reinacher, Andreas; Roeser, Hans-Peter; Savage, Maureen; Teufel, Stefan; Wiedemann, Manuel

    2012-01-01

    The Stratospheric Observatory for Infrared Astronomy (SOFIA) has recently concluded a set of engineering flights for Observatory performance evaluation. These in-flight opportunities have been viewed as a first comprehensive assessment of the Observatory's performance and will be used to address the development activity that is planned for 2012, as well as to identify additional Observatory upgrades. A series of 8 SOFIA Characterization And Integration (SCAI) flights have been conducted from June to December 2011. The HIPO science instrument in conjunction with the DSI Super Fast Diagnostic Camera (SFDC) have been used to evaluate pointing stability, including the image motion due to rigid-body and flexible-body telescope modes as well as possible aero-optical image motion. We report on recent improvements in pointing stability by using an Active Mass Damper system installed on Telescope Assembly. Measurements and characterization of the shear layer and cavity seeing, as well as image quality evaluation as a function of wavelength have been performed using the HIPO+FLITECAM Science Instrument configuration (FLIPO). A number of additional tests and measurements have targeted basic Observatory capabilities and requirements including, but not limited to, pointing accuracy, chopper evaluation and imager sensitivity. SCAI activities included in-flight partial Science Instrument commissioning prior to the use of the instruments as measuring engines. This paper reports on the data collected during the SCAI flights and presents current SOFIA Observatory performance and characterization.

  11. Gravitational Thermodynamics for Interstellar Gas and Weakly Degenerate Quantum Gas

    NASA Astrophysics Data System (ADS)

    Zhu, Ding Yu; Shen, Jian Qi

    2016-03-01

    The temperature distribution of an ideal gas in gravitational fields has been identified as a longstanding problem in thermodynamics and statistical physics. According to the principle of entropy increase (i.e., the principle of maximum entropy), we apply a variational principle to the thermodynamical entropy functional of an ideal gas and establish a relationship between temperature gradient and gravitational field strength. As an illustrative example, the temperature and density distributions of an ideal gas in two simple but typical gravitational fields (i.e., a uniform gravitational field and an inverse-square gravitational field) are considered on the basis of entropic and hydrostatic equilibrium conditions. The effect of temperature inhomogeneity in gravitational fields is also addressed for a weakly degenerate quantum gas (e.g., Fermi and Bose gas). The present gravitational thermodynamics of a gas would have potential applications in quantum fluids, e.g., Bose-Einstein condensates in Earth’s gravitational field and the temperature fluctuation spectrum in cosmic microwave background radiation.

  12. Pulsar polarization measurements and the nonsymmetric gravitational theory

    NASA Technical Reports Server (NTRS)

    Krisher, Timothy P.

    1991-01-01

    Because of the breakdown of the Einstein equivalence principle in the nonsymmetric gravitational theory (NGT) of Moffat, orthogonally polarized electromagnetic waves can propagate at different velocities in a gravitational field. Moffat has proposed that galactic dark matter, in the form of cosmions, may act as a significant source of gravity in the NGT. We discuss how observations of the highly polarized radiation from distant pulsars could provide significant limits on the strength of the coupling of cosmions in the NGT.

  13. Fermi Gamma-Ray Observatory-Science Highlights for the First 8 Months

    NASA Technical Reports Server (NTRS)

    Moiseev, Alexander

    2009-01-01

    This viewgraph presentation reviews the science highlights for the first 8 months of the Fermi Gamma-Ray Observatory. Results from pulsars, flaring AGN, gamma ray bursts, diffuse radiation, LMC and electron spectrum are also presented.

  14. OGRAN setup in the BNO INR RAS in neutrino-gravitational correlation experiment

    NASA Astrophysics Data System (ADS)

    Bezrukov, L. B.; Krysanov, V. A.; Motylev, A. M.; Oreshkin, S. I.; Popov, S. M.; Rudenko, V. N.; Semenov, V. V.; Silin, V. A.; Yudin, I. S.

    This article describes the uncooled opto-acoustical gravitational antenna constructed for a multi-channel mode operation in the deep underground laboratory of the Baksan Neutrino Observatory in parallel with Baksan underground scintillation telescope involved in the collapse searching program.

  15. Gravitation: Foundations and Frontiers

    NASA Astrophysics Data System (ADS)

    Padmanabhan, T.

    2010-01-01

    1. Special relativity; 2. Scalar and electromagnetic fields in special relativity; 3. Gravity and spacetime geometry: the inescapable connection; 4. Metric tensor, geodesics and covariant derivative; 5. Curvature of spacetime; 6. Einstein's field equations and gravitational dynamics; 7. Spherically symmetric geometry; 8. Black holes; 9. Gravitational waves; 10. Relativistic cosmology; 11. Differential forms and exterior calculus; 12. Hamiltonian structure of general relativity; 13. Evolution of cosmological perturbations; 14. Quantum field theory in curved spacetime; 15. Gravity in higher and lower dimensions; 16. Gravity as an emergent phenomenon; Notes; Index.

  16. Supersymmetry and gravitational duality

    SciTech Connect

    Argurio, Riccardo; Dehouck, Francois; Houart, Laurent

    2009-06-15

    We study how the supersymmetry algebra copes with gravitational duality. As a playground, we consider a charged Taub-Newman-Unti-Tamburino(NUT) solution of D=4, N=2 supergravity. We find explicitly its Killing spinors, and the projection they obey provides evidence that the dual magnetic momenta necessarily have to appear in the supersymmetry algebra. The existence of such a modification is further supported using an approach based on the Nester form. In the process, we find new expressions for the dual magnetic momenta, including the NUT charge. The same expressions are then rederived using gravitational duality.

  17. Pioneering in gravitational physiology

    NASA Technical Reports Server (NTRS)

    Soffen, G. A.

    1983-01-01

    Gravity affects biology at almost all levels above that of the cell organelle. Attention is presently given to progress made in the understanding of gravitational effects through studies employing centrifuges, clinostats, inverted preparations, linear devices, water immersion, free fall, and short- and long-term spaceflight. The cardiovascular changes which cause malaise and illness during the first few days of extended space missions are the direct result of fluid translocation from the lower extremities. Upon reentry, there is hypovolumnia and a cardiovascular deconditioning that can include tachycardia, changes in arterial blood pressure, narrow pulse pressure, and syncope. Attention is also given to NASA's gravitational physiology reseach program.

  18. Adding light to the gravitational waves on the null cone

    NASA Astrophysics Data System (ADS)

    Babiuc, Maria

    2014-03-01

    Recent interesting astrophysical observations point towards a multi-messenger, multi-wavelength approach to understanding strong gravitational sources, like compact stars or black hole collisions, supernovae explosions, or even the big bang. Gravitational radiation is properly defined only at future null infinity, but usually is estimated at a finite radius, and then extrapolated. Our group developed a characteristic waveform extraction tool, implemented in an open source code, which computes the gravitational waves infinitely far from their source, in terms of compactified null cones, by numerically solving Einstein equation in Bondi space-time coordinates. The goal is extend the capabilities of the code, by solving Einstein-Maxwell's equations together with the Maxwell's equations, to obtain the energy radiated asymptotically at infinity, both in gravitational and electromagnetic waves. The purpose is to analytically derive and numerically calculate both the gravitational waves and the electromagnetic counterparts at infinity, in this characteristic framework. The method is to treat the source of gravitational and electromagnetic radiation as a black box, and therefore the code will be very flexible, with potentially large applicability.

  19. LIGO Education and Outreach at Twin Observatories

    NASA Astrophysics Data System (ADS)

    Thacker, John

    2007-04-01

    LIGO has twin Gravitational Wave observatories in Hanford, WA and Livingston, LA. Both sites have active outreach programs but each has a different emphasis and methodology. We will briefly describe the nature of these outreach programs. We will then focus attention on the Livingston facility since its outreach program is centered on a new 9000 sq.ft. Science Education Center. We will describe the facility and its exhibits then discuss the structure of the outreach program at the Center. The objectives of the Center are to: communicate LIGO-related science concepts to the public; strengthen skills and abilities of in-service and pre-service teachers and enhance the science and mathematics skills of a broad spectrum of students in Louisiana and the surrounding region. By partnering with a museum (The Exploratorium), a university (Southern University at Baton Rouge) and a state education agency for education reform, LA GEAR UP, we have been able to quickly open up opportunities. Benefiting from our fine collaborators, we've been able to create positive impact in the local science education community in a relatively brief time span.

  20. The Carl Sagan solar and stellar observatories as remote observatories

    NASA Astrophysics Data System (ADS)

    Saucedo-Morales, J.; Loera-Gonzalez, P.

    In this work we summarize recent efforts made by the University of Sonora, with the goal of expanding the capability for remote operation of the Carl Sagan Solar and Stellar Observatories, as well as the first steps that have been taken in order to achieve autonomous robotic operation in the near future. The solar observatory was established in 2007 on the university campus by our late colleague A. Sánchez-Ibarra. It consists of four solar telescopes mounted on a single equatorial mount. On the other hand, the stellar observatory, which saw the first light on 16 February 2010, is located 21 km away from Hermosillo, Sonora at the site of the School of Agriculture of the University of Sonora. Both observatories can now be remotely controlled, and to some extent are able to operate autonomously. In this paper we discuss how this has been accomplished in terms of the use of software as well as the instruments under control. We also briefly discuss the main scientific and educational objectives, the future plans to improve the control software and to construct an autonomous observatory on a mountain site, as well as the opportunities for collaborations.

  1. 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)

  2. The Suitability of Hybrid Waveforms for Advanced Gravitational Wave Detectors

    NASA Astrophysics Data System (ADS)

    MacDonald, Ilana R.

    The existence of Gravitational Waves from binary black holes is one of the most interesting predictions of General Relativity. These ripples in space-time should be visible to ground-based gravitational wave detectors worldwide in the next few years. One such detector, the Laser Interferometer Gravitational-wave Observatory (LIGO) is in the process of being upgraded to its Advanced sensitivity which should make gravitational wave detections routine. Even so, the signals that LIGO will detect will be faint compared to the detector noise, and so accurate waveform templates are crucial. In this thesis, we present a detailed analysis of the accuracy of hybrid gravitational waveforms. Hybrids are created by stitching a long post-Newtonian inspiral to the late inspiral, merger, and ringdown produced by numerical relativity simulations. We begin our investigation with a study of the systematic errors in the numerical waveform, and errors due to hybridization and choice of detector noise. For current NR waveforms, the largest source of error comes from the unknown high-order terms in the post-Newtonian waveform, which we first explore for equal-mass, non-spinning binaries, and also for unequal-mass, non-spinning binaries. We then consider the potential reduction in hybrid errors if these higher-order terms were known. Finally, we investigate the possibility of using hybrid waveforms as a detection template bank and integrating NR+PN hybrids into the LIGO detection pipeline.

  3. Beyond LISA: Exploring future gravitational wave missions

    NASA Astrophysics Data System (ADS)

    Crowder, Jeff; Cornish, Neil J.

    2005-10-01

    The Advanced Laser Interferometer Antenna (ALIA) and the Big Bang Observer (BBO) have been proposed as follow on missions to the Laser Interferometer Space Antenna (LISA). Here we study the capabilities of these observatories, and how they relate to the science goals of the missions. We find that the Advanced Laser Interferometer Antenna in Stereo (ALIAS), our proposed extension to the ALIA mission, will go considerably further toward meeting ALIA’s main scientific goal of studying intermediate mass black holes. We also compare the capabilities of LISA to a related extension of the LISA mission, the Laser Interferometer Space Antenna in Stereo (LISAS). Additionally, we find that the initial deployment phase of the BBO would be sufficient to address the BBO’s key scientific goal of detecting the Gravitational Wave Background, while still providing detailed information about foreground sources.

  4. 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.

  5. Probing gravitational dark matter

    NASA Astrophysics Data System (ADS)

    Ren, Jing; He, Hong-Jian

    2015-03-01

    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 χs. It is a Bbb Z2 odd singlet under the standard model (SM) gauge group, and naturally joins the unique dimension-4 interaction with Ricci curvature, ξsχs2Script R, where ξs is the dimensionless nonminimal coupling. We demonstrate that this gravitational interaction ξsχs2Script R, together with Higgs-curvature nonminimal coupling term ξhH†HScript R, induces effective couplings between χs2 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.

  6. 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.

  7. Extragalactic Gravitational Collapse

    NASA Astrophysics Data System (ADS)

    Rees, Martin J.

    After some introductory "numerology", routes towards black hole formation are briefly reviewed; some properties of black holes relevant to theories for active galactic nuclei are then described. Applications are considered to specific models for energy generation and the production of relativistic beams. The paper concludes with a discussion of extragalactic sources of gravitational waves.

  8. GEOSCOPE Observatory Recent Developments

    NASA Astrophysics Data System (ADS)

    Leroy, N.; Pardo, C.; Bonaime, S.; Stutzmann, E.; Maggi, A.

    2010-12-01

    The GEOSCOPE observatory consists of a global seismic network and a data center. The 31 GEOSCOPE stations are installed in 19 countries, across all continents and on islands throughout the oceans. They are equipped with three component very broadband seismometers (STS1 or STS2) and 24 or 26 bit digitizers, as required by the Federation of Seismic Digital Network (FDSN). In most stations, a pressure gauge and a thermometer are also installed. Currently, 23 stations send data in real or near real time to GEOSCOPE Data Center and tsunami warning centers. In 2009, two stations (SSB and PPTF) have been equipped with warpless base plates. Analysis of one year of data shows that the new installation decreases long period noise (20s to 1000s) by 10 db on horizontal components. SSB is now rated in the top ten long period stations for horizontal components according to the LDEO criteria. In 2010, Stations COYC, PEL and RER have been upgraded with Q330HR, Metrozet electronics and warpless base plates. They have been calibrated with the calibration table CT-EW1 and the software jSeisCal and Calex-EW. Aluminum jars are now installed instead of glass bells. A vacuum of 100 mbars is applied in the jars which improves thermal insulation of the seismometers and reduces moisture and long-term corrosion in the sensor. A new station RODM has just been installed in Rodrigues Island in Mauritius with standard Geoscope STS2 setup: STS2 seismometer on a granite base plate and covered by cooking pot and thermal insulation, it is connected to Q330HR digitizer, active lightning protection, Seiscomp PC and real-time internet connection. Continuous data of all stations are collected in real time or with a delay by the GEOSCOPE Data Center in Paris where they are validated, archived and made available to the international scientific community. Data are freely available to users by different interfaces according data types (see : http://geoscope.ipgp.fr) - Continuous data in real time coming

  9. Testing gravity with gravitational wave source counts

    NASA Astrophysics Data System (ADS)

    Calabrese, Erminia; Battaglia, Nicholas; Spergel, David N.

    2016-08-01

    We show that the gravitational wave source counts distribution can test how gravitational radiation propagates on cosmological scales. This test does not require obtaining redshifts for the sources. If the signal-to-noise ratio (ρ) from a gravitational wave source is proportional to the strain then it falls as {R}-1, thus we expect the source counts to follow {{d}}{N}/{{d}}ρ \\propto {ρ }-4. However, if gravitational waves decay as they propagate or propagate into other dimensions, then there can be deviations from this generic prediction. We consider the possibility that the strain falls as {R}-γ , where γ =1 recovers the expected predictions in a Euclidean uniformly-filled Universe, and forecast the sensitivity of future observations to deviations from standard General Relativity. We first consider the case of few objects, seven sources, with a signal-to-noise from 8 to 24, and impose a lower limit on γ, finding γ \\gt 0.33 at 95% confidence level. The distribution of our simulated sample is very consistent with the distribution of the trigger events reported by Advanced LIGO. Future measurements will improve these constraints: with 100 events, we estimate that γ can be measured with an uncertainty of 15%. We generalize the formalism to account for a range of chirp masses and the possibility that the signal falls as {exp}(-R/{R}0)/{R}γ .

  10. Gamma-ray-burst beaming and gravitational-wave observations.

    PubMed

    Chen, Hsin-Yu; Holz, Daniel E

    2013-11-01

    Using the observed rate of short-duration gamma-ray bursts (GRBs) it is possible to make predictions for the detectable rate of compact binary coalescences in gravitational-wave detectors. We show that the nondetection of mergers in the existing LIGO/Virgo data constrains the beaming angles and progenitor masses of gamma-ray bursts, although these limits are fully consistent with existing expectations. We make predictions for the rate of events in future networks of gravitational-wave observatories, finding that the first detection of a neutron-star-neutron-star binary coalescence associated with the progenitors of short GRBs is likely to happen within the first 16 months of observation, even in the case of only two observatories (e.g., LIGO-Hanford and LIGO-Livingston) operating at intermediate sensitivities (e.g., advanced LIGO design sensitivity, but without signal recycling mirrors), and assuming a conservative distribution of beaming angles (e.g., all GRBs beamed within θ(j) = 30°). Less conservative assumptions reduce the waiting time until first detection to a period of weeks to months, with an event detection rate of >/~10/yr. Alternatively, the compact binary coalescence model of short GRBs can be ruled out if a binary is not seen within the first two years of operation of a LIGO-Hanford, LIGO-Livingston, and Virgo network at advanced design sensitivity. We also demonstrate that the gravitational wave detection rate of GRB triggered sources (i.e., those seen first in gamma rays) is lower than the rate of untriggered events (i.e., those seen only in gravitational waves) if θ(j)≲30°, independent of the noise curve, network configuration, and observed GRB rate. The first detection in gravitational waves of a binary GRB progenitor is therefore unlikely to be associated with the observation of a GRB. PMID:24237502

  11. Observatory Bibliographies as Research Tools

    NASA Astrophysics Data System (ADS)

    Rots, Arnold H.; Winkelman, S. L.

    2013-01-01

    Traditionally, observatory bibliographies were maintained to provide insight in how successful a observatory is as measured by its prominence in the (refereed) literature. When we set up the bibliographic database for the Chandra X-ray Observatory (http://cxc.harvard.edu/cgi-gen/cda/bibliography) as part of the Chandra Data Archive ((http://cxc.harvard.edu/cda/), very early in the mission, our objective was to make it primarily a useful tool for our user community. To achieve this we are: (1) casting a very wide net in collecting Chandra-related publications; (2) including for each literature reference in the database a wealth of metadata that is useful for the users; and (3) providing specific links between the articles and the datasets in the archive that they use. As a result our users are able to browse the literature and the data archive simultaneously. As an added bonus, the rich metadata content and data links have also allowed us to assemble more meaningful statistics about the scientific efficacy of the observatory. In all this we collaborate closely with the Astrophysics Data System (ADS). Among the plans for future enhancement are the inclusion of press releases and the Chandra image gallery, linking with ADS semantic searching tools, full-text metadata mining, and linking with other observatories' bibliographies. This work is supported by NASA contract NAS8-03060 (CXC) and depends critically on the services provided by the ADS.

  12. Stratospheric Observatory for Infrared Astronomy (SOPHIA) Mirror Coating Facility

    NASA Astrophysics Data System (ADS)

    Austin, Ed

    The joint US and German project, Stratospheric Observatory for Infrared Astronomy (SOFIA), to develop and operate a 2.5 meter infrared airborne telescope in a Boeing 747-SP began late last year. Universities Space Research Association (USRA), teamed with Raytheon E-Systems and United Airlines, was selected by NASA to develop and operate SOPHIA. The 2.5 meter telescope will be designed and built by a consortium of German companies. The observatory is expected to operate for over 29 years with the first science flights beginning in 2001. The SOPHIA Observatory will fly at and above 12.5 km, where the telescope will collect radiation in the wavelength range from 0.3 micrometers to a 1.6 millimeters. Universities Space Research Association (USRA) with support from NASA is currently evaluating methods of recoating the primary mirror in preparation for procurement of mirror coating equipment. The decision analysis technique, decision criteria and telescope specifications will be discussed.

  13. The High Energy Astronomy Observatory X-ray Telescope

    NASA Technical Reports Server (NTRS)

    Miller, R.; Austin, G.; Koch, D.; Jagoda, N.; Kirchner, T.; Dias, R.

    1978-01-01

    The High Energy Astronomy Observatory-Mission B (HEAO-B) is a satellite observatory for the purpose of performing a detailed X-ray survey of the celestial sphere. Measurements will be made of stellar radiation in the range 0.2 through 20 keV. The primary viewing requirement is to provide final aspect solution and internal alignment information to correlate an observed X-ray image with the celestial sphere to within one-and-one-half arc seconds. The Observatory consists of the HEAO Spacecraft together with the X-ray Telescope. The Spacecraft provides the required attitude control and determination system, data telemetry system, space solar power system, and interface with the launch vehicle. The X-ray Telescope includes a high resolution mirror assembly, optical bench metering structure, X-ray detectors, detector positioning system, detector electronics and aspect sensing system.

  14. Enhancing the International X-ray Observatory

    NASA Astrophysics Data System (ADS)

    Danner, Rolf; Dailey, D.; Lillie, C.

    2010-03-01

    We present results of systems studies expected to significantly enhance the science utility and reduce technical as well as cost risks for the International X-ray Observatory (IXO). Our Northrop Grumman team draws on the experience of building and operating Chandra and others of NASA's premier astrophysical observatories (Compton Gamma Ray Observatory, James Webb Space Telescope) as well as our experience as a leading developer of deployable space structures. For IXO, we have developed (a) an optical bench concept that has the potential to increase the focal length from 20 to 25 m within the current mass and stability requirements; (b) an instrument and system layout that increases the accessible field of regard; and (c) a number of design choices based on flight proven concepts that reduce cost risk. Our concept for the IXO deployable bench is a Tensegrity structure formed by two telescoping booms (compression) and a hexapod cable (tension) truss. This arrangement achieves the required stiffness for the optical bench at minimal mass while employing only high TRL components and flight proven elements. While the overall concept is innovative and will require further evaluation, it is based on existing elements, can be fully tested on the ground and does not require any new technology. We have also explored the options opened by using hinged, articulating solar panels, and found that when used along with a fully enclosed MLI tent surrounding the optical bench, and an instrument module utilizing radially facing radiator panels, the enhanced configuration will enable us to greatly increase IXO's field of regard without distorting the optical bench beyond acceptable tolerances, making more of the sky accessible for observation at any given time.

  15. Enhancing the International X-Ray Observatory

    NASA Astrophysics Data System (ADS)

    Dailey, Dean; Danner, Rolf; Lillie, Chuck

    2009-09-01

    We present preliminary results of systems studies expected to significantly enhance the science utility and reduce technical as well as cost risks for the International X-ray Observatory (IXO). Our Northrop Grumman team draws on the experience of building and operating Chandra and others of NASA's premier astrophysical observatories (Compton Gamma Ray Observatory, James Webb Space Telescope) as well as our experience as a leading developer of deployable space structures. For IXO, we have developed (a) an optical bench concept that increases the focal length from 20 to 25 m within the current mass and stability requirements; (b) an instrument and system layout that increases the accessible field of regard; and (c) a number of design choices based on flight proven concepts that reduce cost risk. Our concept for the IXO deployable bench is a tensegrity structure formed by two telescoping booms (compression) and a hexapod cable (tension) truss. This arrangement achieves the required stiffness for the optical bench at minimal mass while employing only high TRL components and flight proven elements. While the overall concept is innovative and will require further evaluation, it is based on existing elements, can be fully tested on the ground and does not require any new technology. We have also explored the options opened by using hinged, articulating solar panels, and found that when used along with a fully enclosed MLI tent surrounding the optical bench, and an instrument module utilizing radially facing radiator panels, the enhanced configuration will enable us to greatly increase IXO's field of regard without distorting the optical bench beyond acceptable tolerances, making more of the sky accessible for observation at any given time.

  16. Enhancing the International X-ray Observatory

    NASA Astrophysics Data System (ADS)

    Danner, Rolf; Dailey, D.; Lillie, C.

    2010-01-01

    We present preliminary results of systems studies expected to significantly enhance the science utility and reduce technical as well as cost risks for the International X-ray Observatory (IXO). Our Northrop Grumman team draws on the experience of building and operating Chandra and others of NASA's premier astrophysical observatories (Compton Gamma Ray Observatory, James Webb Space Telescope) as well as our experience as a leading developer of deployable space structures. For IXO, we have developed (a) an optical bench concept that increases the focal length from 20 to 25 m within the current mass and stability requirements; (b) an instrument and system layout that increases the accessible field of regard; and (c) a number of design choices based on flight proven concepts that reduce cost risk. Our concept for the IXO deployable bench is a Tensegrity structure formed by two telescoping booms (compression) and a hexapod cable (tension) truss. This arrangement achieves the required stiffness for the optical bench at minimal mass while employing only high TRL components and flight proven elements. While the overall concept is innovative and will require further evaluation, it is based on existing elements, can be fully tested on the ground and does not require any new technology. We have also explored the options opened by using hinged, articulating solar panels, and found that when used along with a fully enclosed MLI tent surrounding the optical bench, and an instrument module utilizing radially facing radiator panels, the enhanced configuration will enable us to greatly increase IXO's field of regard without distorting the optical bench beyond acceptable tolerances, making more of the sky accessible for observation at any given time.

  17. Enhancing the International X-ray Observatory

    NASA Astrophysics Data System (ADS)

    Danner, Rolf; Dailey, D.; Lillie, C.

    2010-02-01

    We present results of systems studies expected to significantly enhance the science utility and reduce technical as well as cost risks for the International X-ray Observatory (IXO). Our Northrop Grumman team draws on the experience of building and operating Chandra and others of NASA's premier astrophysical observatories (Compton Gamma Ray Observatory, James Webb Space Telescope) as well as our experience as a leading developer of deployable space structures. For IXO, we have developed (a) an optical bench concept that has the potential to increase the focal length from 20 to 25 m within the current mass and stability requirements; (b) an instrument and system layout that increases the accessible field of regard; and (c) a number of design choices based on flight proven concepts that reduce cost risk. Our concept for the IXO deployable bench is a Tensegrity structure formed by two telescoping booms (compression) and a hexapod cable (tension) truss. This arrangement achieves the required stiffness for the optical bench at minimal mass while employing only high TRL components and flight proven elements. While the overall concept is innovative and will require further evaluation, it is based on existing elements, can be fully tested on the ground and does not require any new technology. We have also explored the options opened by using hinged, articulating solar panels, and found that when used along with a fully enclosed MLI tent surrounding the optical bench, and an instrument module utilizing radially facing radiator panels, the enhanced configuration will enable us to greatly increase IXO's field of regard without distorting the optical bench beyond acceptable tolerances, making more of the sky accessible for observation at any given time.

  18. The exoplanet microlensing survey by the proposed WFIRST Observatory

    NASA Astrophysics Data System (ADS)

    Barry, Richard; Kruk, Jeffery; 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

    2011-10-01

    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.

  19. 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.

  20. Magdalena Ridge Observatory Project Overview

    NASA Astrophysics Data System (ADS)

    Laubscher, Bryan E.; Buscher, David F.; Chang, Mark J.; Cobb, Michael L.; Haniff, Chris A.; Horton, Richard F.; Jorgensen, Anders M.; Klinglesmith, Dan; Loos, Gary; Nemzek, Robert J.

    The Magdalena Ridge Observatory (MRO) is a project with the goal of building a state of the art observatory on Magdalena Ridge west of Socorro New Mexico. This observatory will be sited above 3700 meters and will consist of a 10-element 400-meter baseline optical/infrared imaging interferometer and a separate 2.4-meter telescope with fast response capability. The MRO consortium members include New Mexico Institute of Mining and Technology University of Puerto Rico Mew Mexico Highlands University New Mexico State University and the Los Alamos National Laboratory. The University of Cambridge is a joint participant in the current design phase of the interferometer and expects to join the consortium. We will present an overview of the optical interferometer and single telescope designs and review their instrumentation and science programs

  1. Visits to La Plata Observatory

    NASA Astrophysics Data System (ADS)

    Feinstein, A.

    1985-03-01

    La Plata Observatory will welcome visitors to ESO-La Silla that are willing to make a stop at Buenos Aires on their trip to Chile or on their way back. There is a nice guesthouse at the Observatory that can be used, for a couple of days or so, by astronomers interested in visiting the Observatory and delivering talks on their research work to the Argentine colleagues. No payments can, however, be made at present. La Plata is at 60 km from Buenos Aires. In the same area lie the Instituto de Astronomia y Fisica dei Espacio (IAFE), in Buenos Aires proper, and the Instituto Argentino de Radioastronomia (IAR). about 40 km from Buenos Aires on the way to La Plata. Those interested should contacl: Sr Decano Prof. Cesar A. Mondinalli, or Dr Alejandro Feinstein, Observatorio Astron6mico, Paseo dei Bosque, 1900 La Plata, Argentina. Telex: 31216 CESLA AR.

  2. Technology progress of Virtual Observatory

    NASA Astrophysics Data System (ADS)

    Cui, Chenzhou; Zhao, Yongheng; Zhao, Gang; Zhang, Yanxia

    2002-12-01

    The project of Virtual Observatory (VO) is the result of breakthroughs in telescope, detector, computer and Internet technologies. The combination with the new information technology is the major characteristic of the VO development. Extensible markup language (XML) and Grid as two trends of information technology will be adopted widely in the VO. The VO architecture is based upon the standard layered architecture of Grid. In the paper, technologies related in each layer of the VO architecture are introduced. The global Virtual Observatory provides new chances for Chinese astronomy. Using the abundant resources in the Internet and chances provided by open-source software, Chinese astronomers should cooperate with national IT experts and push the Virtual Observatory projects of China as soon as possible.

  3. Non-gravitational perturbations and satellite geodesy

    SciTech Connect

    Milani, A.; Nobill, A.M.; Farinella, P.

    1987-01-01

    This book presents the basic ideas of the physics of non-gravitational perturbations and the mathematics required to compute their orbital effects. It conveys the relevance of the different problems that must be solved to achieve a given level of accuracy in orbit determination and in recovery of geophysically significant parameters. Selected Contents are: Orders of Magnitude of the Perturbing Forces, Tides and Apparent Forces, Tools from Celestial Mechanics, Solar Radiation Pressure-Direct Effects: Satellite-Solar Radiation Interaction, Long-Term Effects on Semi-Major Axis, Radiation Pressure-Indirect Effects: Earth-Reflected Radiation Pressure, Anisotropic Thermal Emission, Drag: Orbital Perturbations by a Drag-Like Force, and Charged Particle Drag.

  4. The Compton Observatory Science Workshop

    NASA Technical Reports Server (NTRS)

    Shrader, Chris R. (Editor); Gehrels, Neil (Editor); Dennis, Brian (Editor)

    1992-01-01

    The Compton Observatory Science Workshop was held in Annapolis, Maryland on September 23-25, 1991. The primary purpose of the workshop was to provide a forum for the exchange of ideas and information among scientists with interests in various areas of high energy astrophysics, with emphasis on the scientific capabilities of the Compton Observatory. Early scientific results, as well as reports on in-flight instrument performance and calibrations are presented. Guest investigator data products, analysis techniques, and associated software were discussed. Scientific topics covered included active galaxies, cosmic gamma ray bursts, solar physics, pulsars, novae, supernovae, galactic binary sources, and diffuse galactic and extragalactic emission.

  5. High Energy Astronomy Observatory (HEAO)

    NASA Technical Reports Server (NTRS)

    1972-01-01

    This is an artist's concept describing the High Energy Astronomy Observatory (HEAO). The HEAO project involved the launching of three unmarned scientific observatories into low Earth orbit between 1977 and 1979 to study some of the most intriguing mysteries of the universe; pulsars, black holes, neutron stars, and super nova. This concept was painted by Jack Hood of the Marshall Space Flight Center (MSFC). Hardware support for the imaging instruments was provided by American Science and Engineering. The HEAO spacecraft were built by TRW, Inc. under project management of the MSFC.

  6. Lunar Observatories: Why, Where, and When?

    NASA Technical Reports Server (NTRS)

    Lowman, D. Paul, Jr.; Durst, Steve; Chen, Peter C.

    1999-01-01

    The value of Moon-based astronomical instruments has been repeatedly supported by several major studies and conferences, such as the "Astrophysics from the Moon" meeting held in Annapolis, Maryland, in 1990 (Mumma and Smith, 1990). A comprehensive review of the advantages of lunar observatories was published in the same year by Burns et al. (1990). However, the decade since then has seen a number of major developments bearing on the topic of lunar observatories, including the following. Two space astronomy programs have been outstandingly successful since 1990: the Cosmic Background Explorer ((COBE) and the Hubble Space Telescope (HST). These instruments have shown for the first time the structure of the universe in the first stages of its creation, i.e., the "Big Bang." One result of these discoveries has been to focus new space astronomy programs on fundamental problems such as shape of the universe, evolution of galaxies, and the nature of "dark" matter. Since these questions involve the very earliest stages of the history of the universe, to study them requires observation of extremely distant objects. Because of the expansion of the universe, all radiation from such objects is greatly redshifted, into the infrared region of the spectrum. For this reason, the Next Generation Space Telescope, the successor to HST, will be an infrared telescope.

  7. Gravitational wave astronomy and cosmology

    NASA Astrophysics Data System (ADS)

    Hughes, Scott A.

    2014-09-01

    The first direct observation of gravitational waves' action upon matter has recently been reported by the BICEP2 experiment. Advanced ground-based gravitational-wave detectors are being installed. They will soon be commissioned, and then begin searches for high-frequency gravitational waves at a sensitivity level that is widely expected to reach events involving compact objects like stellar mass black holes and neutron stars. Pulsar timing arrays continue to improve the bounds on gravitational waves at nanohertz frequencies, and may detect a signal on roughly the same timescale as ground-based detectors. The science case for space-based interferometers targeting millihertz sources is very strong. The decade of gravitational-wave discovery is poised to begin. In this writeup of a talk given at the 2013 TAUP conference, we will briefly review the physics of gravitational waves and gravitational-wave detectors, and then discuss the promise of these measurements for making cosmological measurements in the near future.

  8. Tools for Coordinated Planning Between Observatories

    NASA Technical Reports Server (NTRS)

    Jones, Jeremy; Fishman, Mark; Grella, Vince; Kerbel, Uri; Maks, Lori; Misra, Dharitri; Pell, Vince; Powers, Edward I. (Technical Monitor)

    2001-01-01

    With the realization of NASA's era of great observatories, there are now more than three space-based telescopes operating in different wavebands. This situation provides astronomers with a unique opportunity to simultaneously observe with multiple observatories. Yet scheduling multiple observatories simultaneously is highly inefficient when compared to observations using only one single observatory. Thus, programs using multiple observatories are limited not due to scientific restrictions, but due to operational inefficiencies. At present, multi-observatory programs are conducted by submitting observing proposals separately to each concerned observatory. To assure that the proposed observations can be scheduled, each observatory's staff has to check that the observations are valid and meet all the constraints for their own observatory; in addition, they have to verify that the observations satisfy the constraints of the other observatories. Thus, coordinated observations require painstaking manual collaboration among the observatory staff at each observatory. Due to the lack of automated tools for coordinated observations, this process is time consuming, error-prone, and the outcome of the requests is not certain until the very end. To increase observatory operations efficiency, such manpower intensive processes need to undergo re-engineering. To overcome this critical deficiency, Goddard Space Flight Center's Advanced Architectures and Automation Branch is developing a prototype effort called the Visual Observation Layout Tool (VOLT). The main objective of the VOLT project is to provide visual tools to help automate the planning of coordinated observations by multiple astronomical observatories, as well as to increase the scheduling probability of all observations.

  9. Overview of the Chandra X-Ray Observatory Facility

    NASA Technical Reports Server (NTRS)

    Weisskopf, M. C.; Six, N. Frank (Technical Monitor)

    2002-01-01

    The Chandra X-Ray Observatory (originally called the Advanced X-Ray Astrophysics Facility - AXAF) is the X-Ray component of NASA's "Great Observatory" Program. Chandra is a NASA facility that provides scientific data to the international astronomical community in response to scientific proposals for its use. The Observatory is the product of the efforts of many organizations in the United States and Europe. The Great Observatories also include the Hubble Space Telescope for space-based observations of astronomical objects primarily in the visible portion of the electromagnetic spectrum, the now defunct Compton Gamma- Ray Observatory that was designed to observe gamma-ray emission from astronomical objects, and the soon-to-be-launched Space Infrared Telescope Facility (SIRTF). The Chandra X-Ray Observatory (hereafter CXO) is sensitive to X-rays in the energy range from below 0.1 to above 10.0 keV corresponding to wavelengths from 12 to 0.12 nanometers. The relationship among the various parts of the electromagnetic spectrum, sorted by characteristic temperature and the corresponding wavelength, is illustrated. The German physicist Wilhelm Roentgen discovered what he thought was a new form of radiation in 1895. He called it X-radiation to summarize its properties. The radiation had the ability to pass through many materials that easily absorb visible light and to free electrons from atoms. We now know that X-rays are nothing more than light (electromagnetic radiation) but at high energies. Light has been given many names: radio waves, microwaves, infrared, visible, ultraviolet, X-ray and gamma radiation are all different forms. Radio waves are composed of low energy particles of light (photons). Optical photons - the only photons perceived by the human eye - are a million times more energetic than the typical radio photon, whereas the energies of X-ray photons range from hundreds to thousands of times higher than that of optical photons. Very low temperature systems

  10. Loud and Bright: Gravitational and possible electromagnetic signals induced by binary neutron star mergers

    NASA Astrophysics Data System (ADS)

    Palenzuela, Carlos; Lehner, Luis; Ponce, Marcelo; Thompson, Chris; Liebling, Steve; Neilsen, Dave; Hirschmann, Eric; Anderson, Matt; Motl, Patrick

    2013-04-01

    Our main goal is to investigate how the strongly gravitating and highly dynamical behavior of magnetized binary neutron stars can affect the plasma in the magnetosphere in such a way that powerful electromagnetic emissions can be induced, as well as stressing its connection with gravitational waves produced by the system. Such phenomena is a natural candidate for bright (EM) and loud (GW) emissions, as pulsars are strong electromagnetic emitters on one hand, and merging binary neutron stars are powerful sources of gravitational radiation.

  11. eLISA and the Gravitational Universe

    NASA Astrophysics Data System (ADS)

    Danzmann, Karsten

    2015-08-01

    The last century has seen enormous progress in our understanding of the Universe. We know the life cycles of stars, the structure of galaxies, the remnants of the big bang, and have a general understanding of how the Universe evolved. We have come remarkably far using electromagnetic radiation as our tool for observing the Universe. However, gravity is the engine behind many of the processes in the Universe, and much of its action is dark. Opening a gravitational window on the Universe will let us go further than any alternative. Gravity has its own messenger: Gravitational waves, ripples in the fabric of spacetime. They travel essentially undisturbed and let us peer deep into the formation of the first seed black holes, exploring redshifts as large as z ~ 20, prior to the epoch of cosmic re-ionisation. Exquisite and unprecedented measurements of black hole masses and spins will make it possible to trace the history of black holes across all stages of galaxy evolution, and at the same time constrain any deviation from the Kerr metric of General Relativity. eLISA will be the first ever mission to study the entire Universe with gravitational waves. eLISA is an all-sky monitor and will offer a wide view of a dynamic cosmos using gravitational waves as new and unique messengers to unveil The Gravitational Universe. It provides the closest ever view of the early processes at TeV energies, has guaranteed sources in the form of verification binaries in the Milky Way, and can probe the entire Universe, from its smallest scales around singularities and black holes, all the way to cosmological dimensions.

  12. Superconducting Antenna Concept for Gravitational Waves

    NASA Astrophysics Data System (ADS)

    Gulian, A.; Foreman, J.; Nikoghosyan, V.; Nussinov, S.; Sica, L.; Tollaksen, J.

    The most advanced contemporary efforts and concepts for registering gravitational waves are focused on measuring tiny deviations in large arm (kilometers in case of LIGO and thousands of kilometers in case of LISA) interferometers via photons. In this report we discuss a concept for the detection of gravitational waves using an antenna comprised of superconducting electrons (Cooper pairs) moving in an ionic lattice. The major challenge in this approach is that the tidal action of the gravitational waves is extremely weak compared with electromagnetic forces. Any motion caused by gravitational waves, which violates charge neutrality, will be impeded by Coulomb forces acting on the charge carriers (Coulomb blockade) in metals, as well as in superconductors. We discuss a design, which avoids the effects of Coulomb blockade. It exploits two different superconducting materials used in a form of thin wires -"spaghetti." The spaghetti will have a diameter comparable to the London penetration depth, and length of about 1-10 meters. To achieve competitive sensitivity, the antenna would require billions of spaghettis, which calls for a challenging manufacturing technology. If successfully materialized, the response of the antenna to the known highly periodic sources of gravitational radiation, such as the Pulsar in Crab Nebula will result in an output current, detectable by superconducting electronics. The antenna will require deep (0.3K) cryogenic cooling and magnetic shielding. This design may be a viable successor to LISA and LIGO concepts, having the prospect of higher sensitivity, much smaller size and directional selectivity. This concept of compact antenna may benefit also terrestrial gradiometry.

  13. NOAA Atmospheric Baseline Observatories in the Arctic: Alaska & Greenland

    NASA Astrophysics Data System (ADS)

    Vasel, B. A.; Butler, J. H.; Schnell, R. C.; Crain, R.; Haggerty, P.; Greenland, S.

    2013-12-01

    The National Oceanic and Atmospheric Administration (NOAA) operates two year-round, long-term climate research facilities, known as Atmospheric Baseline Observatories (ABOs), in the Arctic Region. The Arctic ABOs are part of a core network to support the NOAA Global Monitoring Division's mission to acquire, evaluate, and make available accurate, long-term records of atmospheric gases, aerosol particles, and solar radiation in a manner that allows the causes of change to be understood. The observatory at Barrow, Alaska (BRW) was established in 1973 and is now host to over 200 daily measurements. Located a few kilometers to the east of the village of Barrow at 71.3° N it is also the northernmost point in the United States. Measurement records from Barrow are critical to our understanding of the Polar Regions including exchange among tundra, atmosphere, and ocean. Multiple data sets are available for carbon cycle gases, halogenated gases, solar radiation, aerosol properties, ozone, meteorology, and numerous others. The surface, in situ carbon dioxide record alone consists of over 339,000 measurements since the system was installed in July 1973. The observatory at Summit, Greenland (SUM) has been a partnership with the National Science Foundation (NSF) Division of Polar Programs since 2004, similar to that for South Pole. Observatory data records began in 1997 from this facility located at the top of the Greenland ice sheet at 72.58° N. Summit is unique as the only high-altitude (3200m), mid-troposphere, inland, Arctic observatory, largely free from outside local influences such as thawing tundra or warming surface waters. The measurement records from Summit help us understand long-range transport across the Arctic region, as well as interactions between air and snow. Near-real-time data are available for carbon cycle gases, halogenated gases, solar radiation, aerosol properties, meteorology, ozone, and numerous others. This poster will highlight the two facilities

  14. Gravitational coset models

    NASA Astrophysics Data System (ADS)

    Cook, Paul P.; Fleming, Michael

    2014-07-01

    The algebra A {/D - 3 + + +} dimensionally reduces to the E D-1 symmetry algebra of (12 - D)-dimensional supergravity. An infinite set of five-dimensional gravitational objects embedded in D-dimensions is constructed by identifying the null geodesic motion on cosets embedded in the generalised Kac-Moody algebra A {/D - 3 + + +}. By analogy with super-gravity these are bound states of dual gravitons. The metric interpolates continuously between exotic gravitational solutions generated by the action of an affine sub-group. We investigate mixed-symmetry fields in the brane sigma model, identify actions for the full interpolating bound state and investigate the dualisation of the bound state to a solution of the Einstein-Hilbert action via the Hodge dual on multiforms. We conclude that the Hodge dual is insufficient to reconstruct solutions to the Einstein-Hilbert action from mixed-symmetry tensors.

  15. 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.

  16. 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.

  17. 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.

  18. Gravitational lensing by gravastars

    NASA Astrophysics Data System (ADS)

    Kubo, Tomohiro; Sakai, Nobuyuki

    2016-04-01

    As a possible method to detect gravastars (gravitational-vacuum-star), which was originally proposed by Mazur and Mottola, we study their gravitational lensing effects. Specifically, we adopt a spherical thin-shell model of a gravastar developed by Visser and Wiltshire, which connects interior de Sitter geometry and exterior Schwarzschild geometry, and assume that its surface is optically transparent. We calculate the image of a companion which rotates around the gravastar; we find that some characteristic images appear, depending on whether the gravastar possess unstable circular orbits of photons (Model 1) or not (Model 2). For Model 2, we calculate the total luminosity change, which is called microlensing effects; the maximal luminosity could be considerably larger than the black hole with the same mass.

  19. 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.

  20. 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