Science.gov

Sample records for lyman series profiles

  1. Lyman Alpha Line Profile Observations from SORCE SOLSTICE

    NASA Astrophysics Data System (ADS)

    Snow, M. A.; Machol, J. L.; Woods, T. N.; Quemerais, E.; Gruyer, J.

    2015-12-01

    The SOLar-STellar Irradiance Comparison Experiment (SOLSTICE) on the SOlar Radiation and Climate Experiment (SORCE) makes daily measurements of the solar Lyman alpha profile with 0.1 nm spectral resolution. We will present analysis on how the shape of the line evolves over the solar cycle. For comparison, we have convolved observations from SUMER/SOHO with the SOLSTICE profile.

  2. Modeling the detailed Lyman-α line profile

    NASA Astrophysics Data System (ADS)

    Schoell, Micha; Haberreiter, Margit; Schmutz, Werner; Shapiro, Alexander

    2013-04-01

    The variability of the solar spectral irradiance is an important driver in global circulation models. The Lyman-α spectral line is of particular interest as it exhibits a high variability and has strong impact on the ozone concentration and temperature in the Earth's atmosphere. For a complete understanding of the variation of the Lyman-α line it is important to be able to model its detailed line profile. We present recent work on the improvement of the modeling efforts of this important spectral line. We employ an updated version of the COde for Solar Irradiance (COSI) along with existing model atmospheres with an improved implementation of the temperature and turbulent velocity in the chromosphere and transition region. With the latest modifications we are able to reproduce high resolution observations taken with the SUMER instrument onboard of SOHO. This is an important step towards the reliable reconstruction of the irradiance in the Lyman-α spectral line.

  3. Lyman alpha solar spectral irradiance line profile observations and models

    NASA Astrophysics Data System (ADS)

    Snow, Martin; Machol, Janet; Quemerais, Eric; Curdt, Werner; Kretschmar, Matthieu; Haberreiter, Margit

    2016-04-01

    Solar lyman alpha solar spectral irradiance measurements are available on a daily basis, but only the 1-nm integrated flux is typically published. The International Space Science Institute (ISSI) in Bern, Switzerland has sponsored a team to make higher spectral resolution data available to the community. Using a combination of SORCE/SOLSTICE and SOHO/SUMER observations plus empirical and semi-empirical modeling, we will produce a dataset of the line profile. Our poster will describe progress towards this goal.

  4. Non-LTE modelling of prominence fine structures using hydrogen Lyman-line profiles

    NASA Astrophysics Data System (ADS)

    Schwartz, P.; Gunár, S.; Curdt, W.

    2015-05-01

    Aims: We perform a detailed statistical analysis of the spectral Lyman-line observations of the quiescent prominence observed on May 18, 2005. Methods: We used a profile-to-profile comparison of the synthetic Lyman spectra obtained by 2D single-thread prominence fine-structure model as a starting point for a full statistical analysis of the observed Lyman spectra. We employed 2D multi-thread fine-structure models with random positions and line-of-sight velocities of each thread to obtain a statistically significant set of synthetic Lyman-line profiles. We used for the first time multi-thread models composed of non-identical threads and viewed at line-of-sight angles different from perpendicular to the magnetic field. Results: We investigated the plasma properties of the prominence observed with the SoHO/SUMER spectrograph on May 18, 2005 by comparing the histograms of three statistical parameters characterizing the properties of the synthetic and observed line profiles. In this way, the integrated intensity, Lyman decrement ratio, and the ratio of intensity at the central reversal to the average intensity of peaks provided insight into the column mass and the central temperature of the prominence fine structures.

  5. The intrinsic H I Lyman-alpha line profiles of late-type stars

    NASA Technical Reports Server (NTRS)

    Neff, J. E.; Landsman, W. B.; Bookbinder, J. A.; Linsky, J. L.

    1990-01-01

    The Lyman-alpha line of neutral hydrogen is probably the most important cooling channel for chromospheric plasma in late-type stars, yet it is also the least studied major line in the far ultraviolet. The scattering of much of the stellar Lyman-alpha flux by interstellar hydrogen, coupled with the geocoronal emission foreground, seriously complicates the analysis of the Lyman-alpha spectra. The influence of the local interstellar medium on the observed profiles was circumvented by observing stars with radial velocities sufficiently high to Doppler shift the center of the stellar emission line out of the interstellar absorption core. There are several stars that have high radial velocities by virtue of their presence in close binary systems. High resolution IUE (International Ultraviolet Explorer) spectra of Ly alpha line of two such eclipsing binary stars, AR Lac and TY Pyx, are obtained, at each orbital quadrature phase, when the projected orbital velocity is a maximum. By combining the spectra from opposite quadratures it is possible to piece together the entire stellar emission profiles. The third star in this study, delta Lep, is a single star with a high space velocity.

  6. Auroral Lyman α and H2 bands from the giant planets 3. Lyman α spectral profile including charge exchange and radiative transfer effects and H2 color ratios

    NASA Astrophysics Data System (ADS)

    Rego, D.; Prangé, R.; Ben Jaffel, L.

    1999-03-01

    In this paper, third of a series of three dealing with a model of auroral H and H2 emission in the giant planets, we focus on the characteristics of the emergent emission, the only one which can be compared with observations. As the Jovian atmosphere is optically thick at 1215.67 Å, modeling of emergent auroral Lyman α line profiles requires the use of a radiative transfer code to model the transport of photons from the auroral source to the top of the atmosphere. Here, radiative transfer effects are modeled using the ``doubling and adding'' method. This radiative transfert code is self-consistently coupled with the energy degradation code used in the first two papers to compute the excitation rate along the path of precipitating particles as a function of wavelength. Input parameters are the identity and the energy of the incoming particles. We find that the auroral Lyman α line profile shows a central reversal due to the atmospheric H overlying the emitting layer. The shape of the emergent line is almost only sensitive to the column of H in the line of sight to the emission, related, via the atmospheric model used, to the the particle penetration depth (i.e. their energy). In addition, in the case of proton precipitation, charge exchange produces fast H atoms (Hf) which precipitate with the protons. Hf can also be excited and radiate Lyman α photons. This produces a second, Doppler shifted, component, of the Lyman α profile. This component may represent as much as 77.4% of the total Lyman α intensity for 10 keV protons, and it decreases with incident proton energy. It also extends over a broad wavelength range (up to 56 Å for 1 MeV proton). Detection of this component would unambiguously identify protons as the particles responsible for the Jovian aurorae. However, for high proton energies, the escaping flux may be too weak to be detected. Finally, following earlier analyses of IUE auroral spectra, we compute the color ratio C between the fluxes escaping

  7. The Analysis of the H Lyman α Emission Line Profile from Jupiter's Aurora

    NASA Astrophysics Data System (ADS)

    Rego, Daniel; Clarke, John T.; Jaffel, Lotfi Ben; Ballester, Gilda E.; Prangé, Renée; McConnell, Jack

    2001-04-01

    We present the analysis and modeling of the emission spectra of the jovian northern auroral region taken from May 28 to June 3, 1993, with the Goddard High Resolution Spectrograph on board the Hubble Space Telescope. They extend from 1204 to 1240 Â covering H Lyman α and part of the Werner and the Lyman bands of H 2. We used the 2×2 arcsec large science aperture combined with the G160M grating (spectral resolution of 570 mÂ) centred on Jupiter's central meridian. The auroral region studied extends from 50 to 60° north latitudes and from 130 to 220° System III longitudes. Within the 1 arcsec pointing uncertainty, most of the region delineated by the theoretical ovals at 5.9 and 30 jovian radii (R J) in the VIP4 model of J. E. C. Connerney, M. H. Acuna, N. F. Ness, and T. Satoh (1998, New models of Jupiter's magnetic field constrained by the Io flux tube footprint. J. Geophys. Res. 103, 11,929-11,939), including the auroral oval derived from the Wide Field Planetary Camera 2 images by J. T. Clarke, G. E. Ballester, J. T. Trauger, R. Evans, J. E. P. Connerney, K. Stapelfeld, D. Crisp, P. D. Feldman, C. J. Burrows, S. Casertano, J. S. Gallagher, R. E. Griffiths, J. J. Hester, J. G. Hoessel, J. A. Holtzman, J. E. Krist, V. Meadows, J. R. Mould, P. A. Scowen, A. M. Watson, and J. A. Westphal (1996, Far-ultraviolet imaging of Jupiter's aurora and the Io "footprint". Science274, 404-409), was sampled. We derive auroral brightnesses (averaged over the slit) ranging from 20 kR in the 190-220° longitude region to 30 kR in the 130-160° longitude range. We use the theoretical model developed by D. Rego, R. Prangé, and L. Ben Jaffel (1999, Auroral Lyman α and H 2 bands from the giant planets. 3. Lyman α intensity and spectral profile including radiative effects and H 2 color ratios. J. Geophys. Res. Planets.104, 5939-5954), which calculates self-consistently the auroral Lyman α line profile for electron and proton precipitations and a given frequency redistribution

  8. Kinetic-Energy Distribution of D(2p) Atoms from Analysis of the D Lyman-Alpha Line Profile

    NASA Technical Reports Server (NTRS)

    Ciocca, M.; Ajello, Joseph M.; Liu, Xianming; Maki, Justin

    1997-01-01

    The kinetic-energy distribution of D(2p) atoms resulting from electron-impact dissociation of D2 has been measured. A high-resolution vacuum ultraviolet spectrometer was employed for the first measurement of the D Lyman-alpha (D L(alpha)) emission line profiles at 20- and 100-eV excitation energies. Analysis of the deconvoluted line profile of D L(alpha) at 100 eV reveals the existence of a narrow line central peak of 29+/-2 mA full width at half maximum and a broad pedestal wing structure about 190 mA wide. The wings of the line can be used to determine the fast atom distribution. The wings of D L(alpha) arise from dissociative excitation of a series of doubly excited states that cross the Franck-Condon region between 23 and 40 eV. The fast atom distribution at 100-eV electron impact energy spans the energy range from 1 to 10 eV with a peak value near 6 eV. Slow D(2p) atoms characterized by a distribution function with peak energy near 100 meV produce the central peak profile, which is nearly independent of the impact energy. The deconvoluted line profiles of the central peak at 20 eV for dissociative excitation of D2 and H2 are fitted with an analytical function for use in calibration of space flight instrumentation equipped with a D/H absorption cell. The kinetic-energy and line profile results are compared to similar measurements for H2. The absolute cross sections for the line center (slow atoms) and wings (fast atoms) and total emission line profile were measured from threshold to 400 eV. Analytical model coefficients are given for the energy dependence of the measured slow atom cross section.

  9. The Ly(alpha) Line Profiles of Ultraluminous Infrared Galaxies: Fast Winds and Lyman Continuum Leakage

    NASA Technical Reports Server (NTRS)

    Martin, Crystal L.; Dijkstra, Mark; Henry, Alaina L.; Soto, Kurt T.; Danforth, Charles W.; Wong, Joseph

    2015-01-01

    We present new Hubble Space Telescope Cosmic Origins Spectrograph far-ultraviolet (far-UV) spectroscopy and Keck Echellete optical spectroscopy of 11 ultraluminous infrared galaxies (ULIRGs), a rare population of local galaxies experiencing massive gas inflows, extreme starbursts, and prominent outflows. We detect Ly(alpha) emission from eight ULIRGs and the companion to IRAS09583+4714. In contrast to the P Cygni profiles often seen in galaxy spectra, the Ly(alpha) profiles exhibit prominent, blueshifted emission out to Doppler shifts exceeding -1000 km/s in three H II-dominated and two AGN-dominated ULIRGs. To better understand the role of resonance scattering in shaping the Ly(alpha) line profiles, we directly compare them to non-resonant emission lines in optical spectra. We find that the line wings are already present in the intrinsic nebular spectra, and scattering merely enhances the wings relative to the line core. The Ly(alpha) attenuation (as measured in the COS aperture) ranges from that of the far-UV continuum to over 100 times more. A simple radiative transfer model suggests the Ly(alpha) photons escape through cavities which have low column densities of neutral hydrogen and become optically thin to the Lyman continuum in the most advanced mergers. We show that the properties of the highly blueshifted line wings on the Ly(alpha) and optical emission-line profiles are consistent with emission from clumps of gas condensing out of a fast, hot wind. The luminosity of the Ly(alpha) emission increases nonlinearly with the ULIRG bolometric luminosity and represents about 0.1-1% of the radiative cooling from the hot winds in the H II-dominated ULIRGs.

  10. Latitudinal properties of the Lyman alpha and O VI profiles in the extended solar corona

    NASA Astrophysics Data System (ADS)

    Zangrilli, L.; Nicolosi, P.; Poletto, G.; Noci, G.; Romoli, M.; Kohl, J. L.

    1999-02-01

    We have analysed the latitudinal properties of the profiles of the H I Lyman alpha line at 1215.6 protect Angstroms and of the O VI doublet at 1031.9 protect Angstroms and 1037.6 protect Angstroms in the extended solar corona, between 1.5 R_sun and 2.0 R_sun. Observations have been performed with the UltraViolet Coronagraph Spectrometer (UVCS) on board the ESA-NASA solar satellite SOHO (SOlar and Heliospheric Observatory). The results show that these lines have quite a different behaviour with latitude: the Ly alpha line has larger full width at half maximum (FWHM) values in the streamer region and narrower ones towards polar latitudes, while the O VI lines have a minimum FWHM at the center of the streamer, which almost steadily increases towards polar regions. The observations have been analysed looking also for an interpretation in terms of selective heating mechanisms. The implications of our results for coronal heating theories are also examined. In particular we discuss the possibility for the presence of the ion-cyclotron coronal heating mechanism. Moreover, we point out an interesting correlation between the intensity of the coronal lines and their widths, which may be relevant to the open question of the different morphological features visible in the Ly alpha and O VI lines.

  11. On the detection of heliospheric interface properties from interstellar/interplanetary Lyman-alpha profiles - Example of Baranov's two-shock model

    NASA Astrophysics Data System (ADS)

    Quemerais, E.; Malama, Iu. G.; Lallement, R.; Bertaux, J. L.

    Interstellar/interplanetary neutral H atoms which are observed towards the upwind (UW) and downwind (DW) directions do not originate from the same region of the heliospheric interface. If the neutral/plasma coupling is not negligible, the variations of the plasma properties with the distance to the stagnation line are imprinted in the neutral atoms and in the relationship between the UW and DW Lyman-alpha spectral profiles, whatever the distance to the heliospheric shock and to the heliopause. This effect is checked both on the Prognoz 5/6 backscattered Lyman-alpha data and in the case of the Baranov type interface. Hydrogen absorption cell data interpretation is much improved when inhomogeneities of the interstellar wind are taken into account. Lyman-alpha profiles derived from the Monte Carlo neutral flow model of Malama (1990) show the predicted macroscopic effects. These results tend to show that information on the type of the interface at the heliopause can be derived from precise Lyman-alpha line shape measurements and from comparison with line shapes computed from a homogeneous interstellar flow model.

  12. A New SBUV Ozone Profile Time Series

    NASA Technical Reports Server (NTRS)

    McPeters, Richard

    2011-01-01

    Under NASA's MEaSUREs program for creating long term multi-instrument data sets, our group at Goddard has re-processed ozone profile data from a series of SBUV instruments. We have processed data from the Nimbus 7 SBUV instrument (1979-1990) and data from SBUV/2 instruments on NOAA-9 (1985-1998), NOAA-11 (1989-1995), NOAA-16 (2001-2010), NOAA-17 (2002-2010), and NOAA-18 (2005-2010). This reprocessing uses the version 8 ozone profile algorithm but now uses the Brion, Daumont, and Malicet (BMD) ozone cross sections instead of the Bass and Paur cross sections. The new cross sections have much better resolution, and extended wavelength range, and a more consistent temperature dependence. The re-processing also uses an improved cloud height climatology based on the Raman cloud retrievals of OMI. Finally, the instrument-to-instrument calibration is set using matched scenes so that ozone diurnal variation in the upper stratosphere does not alias into the ozone trands. Where there is no instrument overlap, SAGE and MLS are used to estimate calibration offsets. Preliminary analysis shows a more coherent time series as a function of altitude. The net effect on profile total column ozone is on average an absolute reduction of about one percent. Comparisons with ground-based systems are significantly better at high latitudes.

  13. Lyman horizons in the early phases of the epoch of reionization

    NASA Astrophysics Data System (ADS)

    Vonlanthen, P.; Semelin, B.

    2011-12-01

    It has been shown that the radial profile of the Lyman-α flux around light sources emitting in the Lyman band during the early phases of the epoch of reionization is characterized by a series of step-like discontinuities. This property originates in the fact that the neutral intergalactic medium is optically thick at the frequencies of all the Lyman-series lines. We show that, through unsaturated Wouthuysen-Field coupling, these spherical discontinuities are also present in the redshifted 21 cm signal of neutral hydrogen. We use realistic 3D numerical simulations with full radiative transfer calculation in the first five Lyman lines in order to study the properties of these discontinuities and the possibility for detection with the future Square Kilometre Array. Although challenging, these observations could provide a diagnostic tool to disentangle the cosmological signal and residuals from imperfect foreground removal.

  14. Interplanetary Lyman-alpha spectral profiles and intensities for both repulsive and attractive solar force fields Predicted absorption pattern by a hydrogen cell

    NASA Astrophysics Data System (ADS)

    Lallement, R.; Bertaux, J. L.; Dalaudier, F.

    1985-09-01

    The velocity of H atoms in the vicinity of the sun can be modified through ionization by solar-wind charge exchange and solar EUV photoionization, and through solar gravity. A computer-code model was developed to study these effects in detail; the model includes line profile computation in the repulsive case when the solar Lyman-alpha radiation pressure exceeds solar gravity. The model also predicts the distributions of the intensity I(phi) and reduction factor R(phi) of the intensity when the H cell is activated to observation planes perpendicular to the sun-earth line as a function of angle phi. This particular geometry applies to the space experiment flown on the Prognoz 5 and 6 spacecraft. The basic findings of the parametric study are presented.

  15. On the Role of the State in the Governing of Higher Education: A Bibliography of Lyman A. Glenny. Public Administration Series: Bibliography P-929.

    ERIC Educational Resources Information Center

    Quay, Richard H.

    A bibliography of materials authored or coauthored by Lyman A. Glenny from 1951 through 1981 on the role of the state in the governance of higher education is presented. Topics include the following: quality and accountability and statewide review procedures; the role of the state in the governance of higher education; response to stress at 10…

  16. Characteristics of the local interstellar hydrogen determined from PROGNOZ 5 and 6 interplanetary Lyman-alpha line profile measurements with a hydrogen absorption cell

    NASA Astrophysics Data System (ADS)

    Bertaux, J. L.; Lallement, R.; Kurt, V. G.; Mironova, E. N.

    1985-09-01

    The flow of interstellar H atoms in the solar system was observed through resonance scattering of solar Lyman-alpha protons with two Lyman-alpha photometers on the Prognoz 5 and 6 satellites. Data collected at five different locations in the solar system were compared with a model of the interstellar H flow, modified by solar interaction. Five parameters describing atomic hydrogen of the local interstellar medium and two parameters describing the solar interaction were derived simultaneously to give a good fit of the upwind hemisphere. The solar Lyman-alpha flux at line center was determined along with the ionization rate of H atoms.

  17. The solar hydrogen Lyman α to Lyman β line ratio

    NASA Astrophysics Data System (ADS)

    Lemaire, P.; Vial, J.-C.; Curdt, W.; Schühle, U.; Woods, T. N.

    2012-06-01

    Aims: We investigate the variation in the solar hydrogen Lyman α (Lyα) to Lyman β (Lyβ) line ratio as a function of the solar activity by taking into account new results obtained by SoHO/SUMER and TIMED/SEE. Methods: We reanalyze data of quiet and active regions previously collected with the LPSP multichannel instrument on OSO8. We then re-examine data obtained on the solar disk with SUMER and compare them with previous data. In a second step, we use the full Sun H i Lyβ profiles to determine the Lyβ contribution to the SEE profiles obtained with a 0.4 nm full width at half-maximum. The variation in the Lyα to Lyβ line ratio is then measured for part of the solar cycle 23 (2002-2008). Results: We determine the radiance line ratio of the solar H i Lyα to Lyβ line for a quiet Sun area and the relation between the ratio of the Lyα to Lyβ irradiance and the Lyα solar irradiance.

  18. Computational Method for the Systematic Identification of Analog Series and Key Compounds Representing Series and Their Biological Activity Profiles.

    PubMed

    Stumpfe, Dagmar; Dimova, Dilyana; Bajorath, Jürgen

    2016-08-25

    A computational methodology is introduced for detecting all unique series of analogs in large compound data sets, regardless of chemical relationships between analogs. No prior knowledge of core structures or R-groups is required, which are automatically determined. The approach is based upon the generation of retrosynthetic matched molecular pairs and analog networks from which distinct series are isolated. The methodology was applied to systematically extract more than 17 000 distinct series from the ChEMBL database. For comparison, analog series were also isolated from screening compounds and drugs. Known biological activities were mapped to series from ChEMBL, and in more than 13 000 of these series, key compounds were identified that represented substitution sites of all analogs within a series and its complete activity profile. The analog series, key compounds, and activity profiles are made freely available as a resource for medicinal chemistry applications. PMID:27501131

  19. Rocket borne solar eclipse experiment to measure the temperature structure of the solar corona via lyman-. cap alpha. line profile observations

    SciTech Connect

    Argo, H.V.

    1981-01-01

    A rocket borne experiment to measure the temperature structure of the inner solar corona via the doppler broadening of the resonance hydrogen Lyman-..cap alpha.. (lambda1216A) radiation scattered by ambient neutral hydrogen atoms was attempted during the 16 Feb 1980 solar eclipse. Two Nike-Black Brant V sounding rockets carrying instrumented payloads were launched into the path of the advancing eclipse umbra from the San Marco satellite launch platform 3 miles off the east coast of Kenya.

  20. The Lyman alpha coronagraph

    NASA Technical Reports Server (NTRS)

    Kohl, J. L.; Reeves, E. M.; Kirkham, B.

    1977-01-01

    The rocket-borne Lyman alpha coronagraph (RLAC) is to be used in the absence of a natural solar eclipse to determine coronal temperatures from measurements of the line width of Lyman-alpha and to determine neutral hydrogen densities of coronal material from the absolute intensity. The coronagraph consists of a 75-cm Fastie-Ebert scanning spectrometer with an AMR 641 photoelectric detection system, an off-axis parabolic primary mirror, and an occulting system. A special optical arrangement achieves rejection of radiation from the solar disk.

  1. Reproducing the kinematics of damped Lyman α systems

    NASA Astrophysics Data System (ADS)

    Bird, Simeon; Haehnelt, Martin; Neeleman, Marcel; Genel, Shy; Vogelsberger, Mark; Hernquist, Lars

    2015-02-01

    We examine the kinematic structure of damped Lyman α systems (DLAs) in a series of cosmological hydrodynamic simulations using the AREPO code. We are able to match the distribution of velocity widths of associated low-ionization metal absorbers substantially better than earlier work. Our simulations produce a population of DLAs dominated by haloes with virial velocities around 70 km s-1, consistent with a picture of relatively small, faint objects. In addition, we reproduce the observed correlation between velocity width and metallicity and the equivalent width distribution of Si II. Some discrepancies of moderate statistical significance remain; too many of our spectra show absorption concentrated at the edge of the profile and there are slight differences in the exact shape of the velocity width distribution. We show that the improvement over previous work is mostly due to our strong feedback from star formation and our detailed modelling of the metal ionization state.

  2. Modeling Solar Lyman Alpha Irradiance

    NASA Technical Reports Server (NTRS)

    Pap, J.; Hudson, H. S.; Rottman, G. J.; Willson, R. C.; Donnelly, R. F.; London, J.

    1990-01-01

    Solar Lyman alpha irradiance is estimated from various solar indices using linear regression analyses. Models developed with multiple linear regression analysis, including daily values and 81-day running means of solar indices, predict reasonably well both the short- and long-term variations observed in Lyman alpha. It is shown that the full disk equivalent width of the He line at 1083 nm offers the best proxy for Lyman alpha, and that the total irradiance corrected for sunspot effect also has a high correlation with Lyman alpha.

  3. Skylab observations of H I Lyman-alpha

    NASA Technical Reports Server (NTRS)

    Roussel-Dupre, D.

    1982-01-01

    The H I Lyman-alpha profiles obtained with the Skylab SO82-B spectrograph at spectral and spatial resolutions of 60 mA and 2 arcsec x 60 arcsec are presented. Profile variations are illustrated from center to limb, at different heights above the limb, and over a cell and network boundary. The Lyman-alpha core exhibits weak or no limb darkening, whereas the line wings show weak limb darkening. Above the limb, the Lyman-alpha core integrated intensity and line width remain in essence constant up to plus 12 arcsec and may result from resonance scattering of chromospheric radiation by coronal neutral hydrogen or from spicules. On the disk, intensities in the line core are seen as correlating well with the H-alpha network; however, the Lyman-alpha wing intensities are found to correlate better with the transition region lines. The average of profiles acquired over the cell and network region is found to be similar to profiles obtained in the cell.

  4. Rotational modulation of hydrogen Lyman alpha flux from 44ii Bootis

    NASA Technical Reports Server (NTRS)

    Vilhu, O.; Neff, J. E.; Rahunen, T.

    1988-01-01

    Observations with IUE that cover the entire 6.4 hr orbital cycle of the late-type contact binary 44i Bootis are presented. Intrinsic stellar hydrogen Lyman alpha emission flux was determined from low-resolution IUE spectra, compensating for geocoronal emission and for interstellar absorption. The variation of the stellar Lyman alpha emission flux correlates well with the variation of the C II and C IV emission fluxes, and shows orbital modulation in phase with the visual light curve. The ratio of Lyman alpha to CII flux (15 to 20) is similar to that observed in solar active regions. Hydrogen Lyman alpha emission is thus one of the most important cooling channels in the outer atmosphere of 44i Boo. A high-resolution spectrum of the Lyman alpha line was obtained between orbital phases 0.0 and 0.6. The integrated flux in the observed high-resolution Lyman alpha profile is consistent with the fluxes determined using low-resolution spectra, and the composite profile indicates that both components of this binary have equally active chromospheres and transition regions. The uncertainty in the interstellar hydrogen column density cannot mimic the observed variation in the integrated Lyman alpha flux, because the stellar line is very much broader than the interstellar absorption.

  5. Biography Today: Profiles of People of Interest to Young Readers. Scientists & Inventors Series, Volume 5.

    ERIC Educational Resources Information Center

    Abbey, Cherie D., Ed.

    This book, a special volume focusing on computer-related scientists and inventors, provides 12 biographical profiles of interest to readers ages 9 and above. The Biography Today series was created to appeal to young readers in a format they can enjoy reading and readily understand. Each entry provides at least one picture of the individual…

  6. Biography Today: Profiles of People of Interest to Young Readers. Author Series, Volume 3.

    ERIC Educational Resources Information Center

    Harris, Laurie Lanzen, Ed.; Abbey, Cherie D., Ed.

    This is the third volume of the "Biography Today Author Series." Each volume contains alphabetically arranged sketches. Each entry provides at least one picture of the individual profiled with additional information about the birth, youth, early memories, education, first jobs, marriage and family, career highlights, memorable experiences,…

  7. Biography Today: Profiles of People of Interest to Young Readers. Author Series, Volume 4.

    ERIC Educational Resources Information Center

    Harris, Laurie Lanzen, Ed.; Abbey, Cherie D., Ed.

    This is the fourth volume of the "Biography Today Author Series." Each volume contains alphabetically arranged sketches. Each entry provides at least one picture of the individual profiled with additional information about the birth, youth, early memories, education, first jobs, marriage and family, career highlights, memorable experiences,…

  8. Biography Today: Sports Series. Profiles of People of Interest to Young Readers. Volume 3, 1999.

    ERIC Educational Resources Information Center

    Harris, Laurie Lanzen, Ed.; Abbey, Cherie D., Ed.

    This third volume is part of a series of biographies that profile individuals of interest to young people over the age of 9 years. The entries in this volume include Joe Dumars, basketball; Jim Harbaugh, football; Dominik Hasek, hockey; Michelle Kwan, figure skating; Rebecca Lobo, basketball; Greg Maddux, baseball; Fatuma Roba, marathon running;…

  9. Biography Today: Profiles of People of Interest to Young Readers. Sports Series, Volume 9.

    ERIC Educational Resources Information Center

    Abbey, Cherie D., Ed.

    This ninth volume of the "Biography Today Sports" series is intended to appeal to young readers in a format they can enjoy reading and readily understand. Each alphabetically-arranged sketch provides at least one picture of the individual profiled, and bold-faced rubrics lead the reader to information on birth, youth, early memories, education,…

  10. Biography Today: Sports Series. Profiles of People of Interest to Young Readers, Volume 4.

    ERIC Educational Resources Information Center

    Harris, Laurie Lanzen, Ed.; Abbey, Cherie D., Ed.

    This book is the fourth in a series of biographies on today's sports figures designed for students age 9 years and older. It contains alphabetically arranged sketches of the sports figures. Each entry provides at least one picture of the individual profiled. Bold faced rubrics lead the reader to information on birth, youth, early memories,…

  11. Biography Today: Profiles of People of Interest to Young Readers. Author Series, Volume 12.

    ERIC Educational Resources Information Center

    Abbey, Cherie D., Ed.

    This special subject volume, "Biography Today Author Series," Volume 12, was designed to appeal to young readers in a format they can enjoy reading and readily understand. Each volume contains alphabetically arranged sketches; each entry provides at least one photograph of the individual profiled, and bold-faced rubrics lead the reader to…

  12. FUSE/Lyman grant

    NASA Technical Reports Server (NTRS)

    Hurwitz, M.; Bowyer, S.

    1986-01-01

    A variety of options for a short wavelength spectrometer for the Lyman telescope has been studied, and the optimum configuration for this instrument identified. In this spectrometer option study it is assumed (consistent with performance goals outlined by the project) that the instrument, whose prime spectral domain is 900-12000A, will incorporate a grazing incidence telescope which will maintain good collecting efficiency down to 100A. In particular it is assumed that the telescope will have an effective focal length of 10 meters, an image quality of 1.5", and will provide a diverging f/10 beam. Designs compatible with this telescope are analyzed, and it is determined that a two-element grazing incidence spectrometer using as its first optic an ellipsoid to re-focus the beam and a varied line-space plane diffraction grating to disperse the light is the best overall design. This spectrometer could be fed by a small pick-off mirror located just behind the prime focus of the telescope and would clear the light path when not in use. A test of the diffraction efficiency of a low blaze angle grating is undertaken, which is the only technical uncertainty in the spectrometer design.

  13. Spectroscopy of 7 radio-loud QSOs at 2 < z < 6: giant Lyman α emission nebulae accreting on to host galaxies

    NASA Astrophysics Data System (ADS)

    Roche, Nathan; Humphrey, Andrew; Binette, Luc

    2014-10-01

    We performed long-slit optical spectroscopy (Gran Telescopio Canarias-Optical System for Imaging and low Resolution Integrated Spectroscopy) of 6 radio-loud quasi-stellar objects (QSOs) at redshifts 2 < z < 3, known to have giant (˜50-100 kpc) Lyman α emitting nebulae, and detect extended Lyman α emission for 4, with surface brightness ˜10-16 erg cm-2 s-1 arcsec-2 and line full width at half-maximum 400-1100 (mean 863) km s- 1. We also observed the z ≃ 5.9 radio-loud QSO, SDSS J2228+0110, and found evidence of a ≥10 kpc extended Lyman α emission nebula, a new discovery for this high-redshift object. Spatially resolved kinematics of the 5 nebulae are examined by fitting the Lyman α wavelength at a series of positions along the slit. We found the line-of-sight velocity Δ(v) profiles to be relatively flat. However, 3 of the nebulae appear systematically redshifted by 250-460 km s- 1 relative to the Lyman α line of the QSO (with no offset for the other two), which we argue is evidence for infall. One of these (Q0805+046) had a small (˜100 km s- 1) velocity shift across its diameter and a steep gradient at the centre. Differences in line-of-sight kinematics between these 5 giant nebulae and similar nebulae associated with high-redshift radio galaxies (which can show steep velocity gradients) may be due to an orientation effect, which brings infall/outflow rather than rotation into greater prominence for the sources observed `on-axis' as QSOs.

  14. Rufus A. Lyman: Pharmacy's Lamplighter

    PubMed Central

    2009-01-01

    Rufus Ashley Lyman, a physician, was one of the most prominent leaders in US pharmacy education during the first half of the 20th century. He remains the only individual to be the founding dean at colleges of pharmacy at 2 state universities. His role in the creation and sustenance of the American Journal of Pharmaceutical Education provided a platform for a national community and a sounding board for faculty members and others interested in professional education. His efforts to increase pharmacy educational standards were instrumental in the abandonment of the 2-year graduate in pharmacy (PhG) degree and the universal acceptance of the 4-year bachelor of science (BS) degree. Lyman's simple approach and fierce championship of his beliefs led to his recognition as a lamplighter for the profession. Curt P. Wimmer, chair of the New York Branch of the American Pharmaceutical Association (now the American Pharmacists Association (APhA), introduced the 1947 Remington Honor Medalist, Rufus Ashley Lyman. Wimmer mentioned that Lyman worked as a lamplighter in Omaha, Nebraska, during medical school. Continuing the lamplighter analogy, Wimmer cited Lyman's work as a pharmacy educator and editor: “in the councils of your colleagues, your lamp became a torch emitting red hot sparks that often burnt and seared and scorched—but always made for progress.”1 This description provides an evocative image of one of the most prominent pharmacy educators and leaders of the first half of the 20th century. PMID:19777099

  15. Analytic Lyman-alpha wing diagnostics and the chromospheric excitation balance in cool dwarfs

    NASA Technical Reports Server (NTRS)

    Gayley, K. G.

    1994-01-01

    I show that the Lyman alpha wings of cool dwarfs can be understood in terms of a very simple model, based on a simplified representation of the chromospheric hydrogen excitation balance and approximate analytic wing diagnostics in partial redistribution. Much of the complexity of the radiation transfer in the partially coherent and steeply temperature-sensitive Lyman alpha line is circumvented by this technique. The result is an expedient scheme for inverting the Lyman alpha wing profile to determine the characteristic free electron density and its gradient in the middle chromosphere. This represents an important new diagnostic for constraining chromospheric models and their radiative losses. I apply this diagnostic to the Lyman alpha wing profiles of the Sun and AU Mic and show that current instrumentation, most notably the Goddard High Resolution Spectrograph (GHRS) on the Hubble Space Telescope, is capable of providing the necessary data.

  16. Interplanetary Lyman-beta emissions

    NASA Technical Reports Server (NTRS)

    Paresce, F.

    1973-01-01

    Derivation of the intensity of the diffuse hydrogen Lyman-beta glow at 1025 A which is due to resonance scattering of the solar H I 1025 A line by interstellar and interplanetary hydrogen. Two sources of neutral hydrogen are considered: the local interstellar medium interacting with the solar system, and the dust deionization of the H(+) component of the solar wind. It is shown that if the dust geometrical factor is less than or equal to five quintillionths per cm, observations of backscattered Lyman-beta radiation will provide a unique determination of the density and temperature of the local interstellar medium.

  17. LYMAN - The far ultraviolet explorer

    NASA Technical Reports Server (NTRS)

    Moos, Warren; Osantowski, John F.

    1989-01-01

    The LYMAN FUSE mission concept for far ultraviolet astronomy is presented. The wavelength window from 100 to 1200 A provides access to a wide range of important scientific problems in cosmology, galactic structure, stellar evolution, and planetary magnetospheres, which cannot be studied in any other way. The LYMAN FUSE Phase A study is examining in detail mission operations, instrumentation technology, the construction of the instrument module, and the interfaces between the Instrument Module and the Explorer Platform Mission. Most of the mission observing time will be allotted through a competitive Guest Observer program analogous to that in operation for the IUE.

  18. Lyman-Alpha Observations of High Radial Velocity Stars

    NASA Astrophysics Data System (ADS)

    Bookbinder, Jay

    1990-12-01

    H I LYMAN -ALPHA (LY-A) IS ONE OF THE MOST IMPORTANT LINES EMITTED BY PLASMA IN THE TEMPERATURE RANGE OF 7000 TO 10 TO THE FIFTH POWER K IN LATE-TYPE STARS. IT IS A MAJOR COMPONENT OF THE TOTAL RADIATIVE LOSS RATE, AND IT PLAYS A CRUCIAL ROLE IN DETERMINING THE ATMOSPHERIC STRUCTURE AND IN FLUORESCING OTHER UV LINES. YET IT IS ALSO THE LEAST STUDIED MAJOR LINE IN THE FAR UV, BECAUSE MOST OF THE LINE FLUX IS ABSORBED BY THE ISM ALONG THE LINE OF SIGHT AND BECAUSE IT IS STRONGLY COMTAMINATED BY THE GEOCORONAL BACKGROUND. A KNOWLEDGE OF THE Ly-A PROFILE IS ALSO IMPORTANT FOR STUDIES OF DEUTERIUM IN THE INTERSTELLAR MEDIUM. BY OBSERVING HIGH RADIAL VELOCITY STARS WE WILL OBTAIN FOR THE FIRST TIME HIGH RESOLUTION SPECTRA OF THE CORE OF A STELLAR H I LYMAN-A EMISSION LINE PROFILE.

  19. Results of the mission profile life test. [for J-series mercury ion engines

    NASA Technical Reports Server (NTRS)

    Bechtel, R. T.; Trump, G. E.; James, E. L.

    1982-01-01

    Seven J series 30-cm diameter thrusters have been tested in segments of up to 5,070 hr, for 14,541 hr in the Mission Profile Life Test facility. Test results have indicated the basic thruster design to be consistent with the lifetime goal of 15,000 hr at 2-A beam. The only areas of concern identified which appear to require additional verification testing involve contamination of mercury propellant isolators, which may be due to facility constituents, and the ability of specially covered surfaces to contain sputtered material and prevent flake formation. The ability of the SCR, series resonant inverter power processor to operate the J series thruster and autonomous computer control of the thruster/processor system were demonstrated.

  20. Coupling the emission of ionizing radiation and Lyman alpha

    NASA Astrophysics Data System (ADS)

    Scarlata, Claudia; Hayes, Matthew; Miller, Brendan P.; Pushnig, Johannes; Jansson, Gustav

    2016-01-01

    The class of objects that reionized the intergalactic hydrogen remains an observational and theoretical challenge. Recently, the shape of the Lyman-alpha (Lya) emission line profile has been proposed as a way to pre-select Lyman Continuum (LyC) leaking galaxies. We present results of deep spectroscopic observations obtained with the Cosmic Origin Spectrograph on the HST of a sample of 4 Lya-emitting galaxies at z~0.3, chosen to be candidate LyC leaking galaxies, on the grounds of blueshifted peaks of Lya emission/symmetric extended Lya wings. We do not detect ionizing radiation escaping from these objects, with upper 3sigma limits on the absolute escape fraction of LyC photons between 14 and 2%.

  1. Direct Detection of Lyman Continuum Escape from Local Starburst Galaxies with the Cosmic Origins Spectrograph

    NASA Astrophysics Data System (ADS)

    Leitherer, Claus; Hernandez, Svea; Lee, Janice C.; Oey, M. S.

    2016-05-01

    We report on the detection of Lyman continuum radiation in two nearby starburst galaxies. Tol 0440-381, Tol 1247-232, and Mrk 54 were observed with the Cosmic Origins Spectrograph on board the Hubble Space Telescope. The three galaxies have radial velocities of ˜13,000 km s‑1, permitting a ˜35 Å window on the restframe Lyman continuum shortward of the Milky Way Lyman edge at 912 Å. The chosen instrument configuration using the G140L grating covers the spectral range from 912 to 2000 Å. We developed a dedicated background subtraction method to account for the temporal and spatial background variations of the detector, which is crucial at the low flux levels around 912 Å. This modified pipeline allowed us to significantly improve the statistical and systematic detector noise and will be made available to the community. We detect Lyman continuum in all three galaxies. However, we conservatively interpret the emission in Tol 0440-381 as an upper limit due to possible contamination by geocoronal Lyman series lines. We determined the current star formation properties from the far-ultraviolet continuum and spectral lines and used synthesis models to predict the Lyman continuum radiation emitted by the current population of hot stars. We discuss various model uncertainties such as, among others, atmospheres and evolution models. Lyman continuum escape fractions were derived from a comparison between the observed and predicted Lyman continuum fluxes. Tol 1247-232, Mrk 54, and Tol 0440-381 have absolute escape fractions of (4.5 ± 1.2)%, (2.5 ± 0.72)%, and <(7.1 ± 1.1)%, respectively.

  2. Direct Detection of Lyman Continuum Escape from Local Starburst Galaxies with the Cosmic Origins Spectrograph

    NASA Astrophysics Data System (ADS)

    Leitherer, Claus; Hernandez, Svea; Lee, Janice C.; Oey, M. S.

    2016-05-01

    We report on the detection of Lyman continuum radiation in two nearby starburst galaxies. Tol 0440-381, Tol 1247-232, and Mrk 54 were observed with the Cosmic Origins Spectrograph on board the Hubble Space Telescope. The three galaxies have radial velocities of ∼13,000 km s‑1, permitting a ∼35 Å window on the restframe Lyman continuum shortward of the Milky Way Lyman edge at 912 Å. The chosen instrument configuration using the G140L grating covers the spectral range from 912 to 2000 Å. We developed a dedicated background subtraction method to account for the temporal and spatial background variations of the detector, which is crucial at the low flux levels around 912 Å. This modified pipeline allowed us to significantly improve the statistical and systematic detector noise and will be made available to the community. We detect Lyman continuum in all three galaxies. However, we conservatively interpret the emission in Tol 0440-381 as an upper limit due to possible contamination by geocoronal Lyman series lines. We determined the current star formation properties from the far-ultraviolet continuum and spectral lines and used synthesis models to predict the Lyman continuum radiation emitted by the current population of hot stars. We discuss various model uncertainties such as, among others, atmospheres and evolution models. Lyman continuum escape fractions were derived from a comparison between the observed and predicted Lyman continuum fluxes. Tol 1247-232, Mrk 54, and Tol 0440-381 have absolute escape fractions of (4.5 ± 1.2)%, (2.5 ± 0.72)%, and <(7.1 ± 1.1)%, respectively.

  3. The Re-Analysis of Ozone Profile Data from a 41-Year Series of SBUV Instruments

    NASA Technical Reports Server (NTRS)

    Kramarova, Natalya; Frith, Stacey; Bhartia, Pawan K.; McPeters, Richard; Labow, Gordon; Taylor, Steven; Fisher, Bradford

    2012-01-01

    In this study we present the validation of ozone profiles from a number of Solar Back Scattered Ultra Violet (SBUV) and SBUV/2 instruments that were recently reprocessed using an updated (Version 8.6) algorithm. The SBUV dataset provides the longest available record of global ozone profiles, spanning a 41-year period from 1970 to 2011 (except a 5-year gap in the 1970s) and includes ozone profile records obtained from the Nimbus-4 BUV and Nimbus-7 SBUV instruments, and a series of SBUV(/2) instruments launched on NOAA operational satellites (NOAA 09, 11, 14, 16, 17, 18, 19). Although modifications in instrument design were made in the evolution from the BUV instrument to the modern SBUV(/2) model, the basic principles of the measurement technique and retrieval algorithm remain the same. The long term SBUV data record allows us to create a consistent, calibrated dataset of ozone profiles that can be used for climate studies and trend analyses. In particular, we focus on estimating the various sources of error in the SBUV profile ozone retrievals using independent observations and analysis of the algorithm itself. For the first time we include in the metadata a quantitative estimate of the smoothing error, defined as the error due to profile variability that the SBUV observing system cannot inherently measure. The magnitude of the smoothing error varies with altitude, latitude, season and solar zenith angle. Between 10 and 1 hPa the smoothing errors for the SBUV monthly zonal mean retrievals are of the order of 1 %, but start to increase above and below this layer. The largest smoothing errors, as large as 15-20%, were detected in in the troposphere. The SBUV averaging kernels, provided with the ozone profiles in version 8.6, help to eliminate the smoothing effect when comparing the SBUV profiles with high vertical resolution measurements, and make it convenient to use the SBUV ozone profiles for data assimilation and model validation purposes. The smoothing error can

  4. Time-series analysis of temperature profiles from VIRTIS Venus Express data

    NASA Astrophysics Data System (ADS)

    Grassi, D.; Migliorini, A.; Politi, R.; Montabone, L.; Piccioni, G.; Drossart, P.

    2012-04-01

    Nighttime infrared observations of the VIRTIS instrument on board Venus Express have already demonstrated their potential in the study of air temperature fields of the Venusian mesosphere. The entire available dataset acquired by the VIRTIS-M IR channel was processed at moderate spatial resolution (i.e. averaging pixels in 8x8 boxes) to derive an unprecedented dataset of air temperature profiles in the pressure range 100-0.1 mbar, covering mostly the latitudes south of 45S. We presented in Grassi et al. (2010, doi:10.1029/2009JE003553) an analysis of the mean properties of temperature profiles, once binned in the latitude/local time/pressure space. Here we discuss the preliminary findings of time-series analysis of data from individual bins. Despite the sparsity of most series, Lomb-Scargle periodogram can be effectively applied in the regions south of 70S, where better coverage is made possible by specific properties of Venus Express orbit. Here the algorithm is able to extract a clear signature related to a period of about 115-120 Earth days, i.e. one Venus solar day, particularly strong at the level around 10 mbar. Further analysis of average temperature fields in the latitude - longitude space demonstrated, for different local times during night, that air temperatures east of Lada Terra (most specifically in a region centered around 130°E and about 60° wide) are about 10K warmer than in other longitudes at 75S.

  5. Lyman-Alpha aurora

    SciTech Connect

    Durrance, S.T.; Clarke, J.T.

    1984-10-01

    The existence of intense and variable H Ly a emission from Uranus is demonstrated utilizing the monochromatic imaging capabilities of the International Ultraviolet Explorer satellite. A series of 14 observations, using the IUE short wavelength spectrograph in low dispersion and covering the period from 3 March 1982 through 2 September 1983, shows the disk averaged Ly a brightness of Uranus to vary between 690 and 2230 Rayleighs. Model calculations indicates that 400 R of this emission can be attributed to resonant scattering of solar Ly a radiation. An upper limit of 100 R is obtained for the Raman scattering of solar Ly a by H2 (1280 A). This implies that 300 R is contributed to the planetary Ly a emission by Rayleigh scattering. In addition to being unexpectedly strong, the Uranian Ly a emission has been observed to vary by a factor of two in one 24 hr period and by about 50% in one 5 hr period.

  6. An in vitro comparison of torsional stress and cyclic fatigue resistance of ProFile GT and ProFile GT Series X rotary nickel-titanium files.

    PubMed

    Kramkowski, Thomas R; Bahcall, James

    2009-03-01

    The purpose of this in vitro study was to compare the torsional stress and cyclic fatigue characteristics of ProFile GT (Dentsply Tulsa Dental, Tulsa, OK) and ProFile GT Series X (Dentsply Tulsa Dental). Files of 0.04 and 0.06 taper, 25 mm in length, and ISO sizes of 20 and 30 tips were compared (n = 25 per test group). Torque stress resistance was evaluated by measuring the torque in gram-centimeters (g-cm) and angle of deflection (degrees of rotation) required for instrument separation with use of a torsiometer instrument. Cyclic fatigue was determined by recording the time until breakage of a file rotating in a simulated canal with an applied 45 degrees or 60 degrees curve. The files were operated in a cyclic fatigue instrument that simulated clinical rotary file usage with a constant cyclical axial motion. There was no statistical difference (p > 0.05) when comparing the torque (g-cm) required to induce a torsional failure of ProFile GT and ProFile GT Series X files of identical file sizes. The angle of deflection (degrees of rotation) of ProFile GT was significantly greater (p < or = 0.001) before separation than ProFile GT Series X for all file sizes tested except 20/.04 (p > 0.05). There was no statistical difference (p > 0.05) in cyclic fatigue failure for ProFile GT and ProFile GT Series X in a canal with a curvature of 45 degrees . In the 60 degrees canal curvature, ProFile GT was found to be significantly more resistant (p = 0.005) to fracture because of cyclic fatigue than ProFile GT Series X for file size 30/.06 and significant (p < or = 0.001) for files sizes 20/.06 and 30/.04. There was no difference (p > 0.05) in cyclic fatigue resistance in the 60 degrees canal for ProFile GT and ProFile GT Series X for file size 20/.04. PMID:19249605

  7. Weighing the Low-Redshift Lyman-alpha Forest

    NASA Technical Reports Server (NTRS)

    Shull, Mike

    2005-01-01

    In 2003-2004, our FUSE research group prepared several major surveys of the amount of baryonic matter in the intergalactic medium (IGM), using the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite. These surveys include measurements of the Lyman-alpha absorption line of neutral hydrogen (H I), the far-ultraviolet (1032,1038 Angstrom) doublet of highly ionized oxygen ( O VI), the higher Lyman-series lines (Ly-beta, Ly-gamma, etc) of H I, and the 977 Angstrom line of c III. As an overview, our FUSE spectroscopic studies, taken together with data from the Hubble Space Telescope, show that approximately 30% of the normal matter is contained in intergalactic hydrogen gas clouds (the Lyman-alpha forest). Another 5-10% resides in hotter gas at temperatures of 10(exp 5) to 10(exp 6) K, visible in 0 VI and C III absorption. Along with the matter attributed to galaxies, we have now accounted for approximately HALF of all the baryonic matter in the universe. Where is the other half? That matter my exist in even hotter gas, invisible through the ultraviolet absorption lines, but perhaps detectable through X-ray absorption lines of more highly ionized oxygen and neon.

  8. Case Series: Fractional Anisotropy Profiles of the Cerebellar Peduncles in Adolescents Born Preterm With Ventricular Dilation.

    PubMed

    Travis, Katherine E; Leitner, Yael; Ben-Shachar, Michal; Yeom, Kristen W; Feldman, Heidi M

    2016-03-01

    This case series assesses white matter microstructure of the cerebellar peduncles in 4 adolescents born preterm with enlarged ventricles and reduced white matter volume in the cerebrum but no apparent injury to the cerebellum. Subjects (ages 12-17 years, gestational age 26-32 weeks, birth weight 825-2211 g) were compared to a normative sample of 19 full-term controls (9-17 years, mean gestational age 39 weeks, mean birth weight 3154 g). Tract profiles for each of the cerebellar peduncles were generated by calculating fractional anisotropy at 30 points along the central portion of each tract. One or more case subjects exhibited higher fractional anisotropy beyond the 90th percentile in the inferior, middle, and superior cerebellar peduncles. Findings demonstrate that differences in cerebellar white matter microstructure can be detected in the absence of macrostructural cerebellar abnormalities. PMID:26116381

  9. Experimental investigation of uranium-series isotope mobility in a basaltic weathering profile

    NASA Astrophysics Data System (ADS)

    Dosseto, Anthony; Menozzi, Davide; Kinsley, Leslie

    2015-04-01

    The measurement of uranium (U)-series isotopes in regolith can be used to determine the formation rate of weathering profiles. This approach aims at following how the U-series isotope composition of primary minerals (i.e. those derived from the parent material) vary during the development of the weathering profile. Nevertheless, regolith samples are a complex mixture of primary minerals, secondary minerals that are the residue of primary mineral weathering, secondary minerals that precipitate from pore water, minerals derived from atmospheric deposition and organic matter. In this study, firstly we aim at isolating primary minerals and the secondary minerals derived from them, by evaluating a sequential extraction procedure designed to eliminate carbonates, Fe-Mn oxides and organic matter. Secondly, we investigate the behaviour of U-series isotopes during primary mineral dissolution by applying a mild HF/HCl etching solution to the residues of the sequential extraction. These experiments were performed on bedrock, saprolite and soil derived from a basaltic weathering profile in south-eastern Australia. Results show that up to 50% of U is removed during sequential extraction, suggesting that (i) there is a large pool of labile U in the bedrock and (ii) secondary phases and organic matter account for a large fraction of the U budget in bulk saprolite and soil. Sequential extraction has little impact on the (234U/238U) activity ratio of bedrock and saprolite, whilst it shows a decrease in soil. This suggests that the pool of U removed from bedrock and saprolite has a (234U/238U) similar to that of primary minerals; but in the soil, the U removed (mostly from organic matter) is enriched in 234U. This is expected as organic matter uptakes U from pore solutions, which are generally enriched in 234U. During HF/HCl etching, the (234U/238U) of bedrock and saprolite is greater than 1. Sheng and Kuroda [1] previously proposed that (234U/238U) >1 in rocks could be explained by

  10. Lyman Alpha Spicule Observatory (LASO)

    NASA Technical Reports Server (NTRS)

    Chamberlin, Phillip C.

    2011-01-01

    The Lyman Alpha Spicule Observatory (LASO) sounding rocket will observe smallscale eruptive events called "Rapid Blue-shifted Events" (RBEs) [Rouppe van der Voort et al., 2009], the on-disk equivalent of Type-II spicules, and extend observations that explore their role in the solar coronal heating problem [De Pontieu et al., 2011]. LASO utilizes a new and novel optical design to simultaneously observe two spatial dimensions at 4.2" spatial resolution (2.1" pixels) over a 2'x2' field of view with high spectral resolution of 66mAngstroms (33mAngstroms pixels) across a broad 20Angstrom spectral window. This spectral window contains three strong chromospheric and transition region emissions and is centered on the strong Hydrogen Lyman-a emission at 1216Angstroms. This instrument makes it possible to obtain new data crucial to the physical understanding of these phenomena and their role in the overall energy and momentum balance from the upper chromosphere to lower corona. LASO was submitted March 2011 in response to the ROSES SHP-LCAS call.

  11. Lyman Alpha Spicule Observatory (LASO)

    NASA Astrophysics Data System (ADS)

    Chamberlin, Phillip C.; Allred, J.; Airapetian, V.; Gong, Q.; Fontenla, J.; McIntosh, S.; de Pontieu, B.

    2011-05-01

    The Lyman Alpha Spicule Observatory (LASO) sounding rocket will observe small-scale eruptive events called "Rapid Blue-shifted Events” (RBEs), the on-disk equivalent of Type-II spicules, and extend observations that explore their role in the solar coronal heating problem. LASO utilizes a new and novel optical design to simultaneously observe two spatial dimensions at 4.2" spatial resolution (2.1” pixels) over a 2'x2' field of view with high spectral resolution of 66mÅ (33mÅ pixels) across a broad 20Å spectral window. This spectral window contains three strong chromospheric and transition region emissions and is centered on the strong Hydrogen Lyman-α emission at 1216Å. This instrument makes it possible to obtain new data crucial to the physical understanding of these phenomena and their role in the overall energy and momentum balance from the upper chromosphere to lower corona. LASO was submitted March 2011 in response to the ROSES SHP-LCAS call.

  12. Lyman Alpha Spicule Observatory (LASO)

    NASA Astrophysics Data System (ADS)

    Chamberlin, P. C.; Allred, J. C.; Airapetian, V.; Gong, Q.; Mcintosh, S. W.; De Pontieu, B.; Fontenla, J. M.

    2011-12-01

    The Lyman Alpha Spicule Observatory (LASO) sounding rocket will observe small-scale eruptive events called "Rapid Blue-shifted Events" (RBEs) [Rouppe van der Voort et al., 2009], the on-disk equivalent of Type-II spicules, and extend observations that explore their role in the solar coronal heating problem [De Pontieu et al., 2011]. LASO utilizes a new and novel optical design to simultaneously observe two spatial dimensions at 4.2" spatial resolution (2.1" pixels) over a 2'x2' field of view with high spectral resolution of 66mÅ (33mÅ pixels) across a broad 20Å spectral window. This spectral window contains three strong chromospheric and transition region emissions and is centered on the strong Hydrogen Lyman-α emission at 1216Å. This instrument makes it possible to obtain new data crucial to the physical understanding of these phenomena and their role in the overall energy and momentum balance from the upper chromosphere to lower corona. LASO was submitted March 2011 in response to the ROSES SHP-LCAS call.

  13. Changes in weight loss and lipid profiles after a dietary purification program: a prospective case series

    PubMed Central

    Callahan, Erica

    2013-01-01

    Objective The purpose of this case series was to describe immediate changes to weight and lipid profiles after a 21-day Standard Process whole food supplement and dietary modification program. Methods Changes in weight and lipid profiles were measured for 7 participants (6 men and 1 woman) participating in a 21-day program. The dietary modifications throughout the Standard Process program were consumption of (1) unlimited fresh or frozen vegetables and fruits and preferably twice as many vegetables as fruits, (2) ½ to 1 cup of cooked lentils or brown rice each day, (3) 4 to 7 teaspoons of cold pressed oils per day, and (4) at least 64 oz of water a day. After day 10 of the program, participants were allowed to consume 1 to 2 servings of baked, broiled, or braised poultry or fish per day. Participants consumed a whey protein–based shake as meal replacement 2 times per day. Nutritional supplementation included a cleanse product on days 1 to 7, soluble fiber supplementation including oat bran concentrate and apple pectin on all days, and “green food” supplementation on days 8 to 21. Results Weight loss ranged between 5.2 (2.4 kg) and 19.9 lb (9.0 kg) (average, 11.7 lb; 5.3 kg). Total cholesterol levels decreased with ranges between 11 and 77 mg/dL, and low-density lipoprotein cholesterol levels decreased in a range between 7 and 67 mg/dL. Conclusion After participating in a dietary program, the 7 participants demonstrated short-term weight loss and improvements in their lipid profiles. PMID:23997722

  14. Lyman alpha airglow observations from SORCE SOLSTICE

    NASA Astrophysics Data System (ADS)

    Dolinar, E.; Snow, M.; Holsclaw, G.; Thomas, G. E.; Woods, T. N.

    2010-12-01

    The Solar Stellar Irradiance Comparison Experiment (SOLSTICE) instrument on board the Solar Radiation Climate Experiment (SORCE) spacecraft in low Earth orbit observes stars every orbit for in-flight calibration. It also observes several star-free regions of the sky near the wavelength of Lyman alpha to correct for airglow emission in the stellar measurements. Although the airglow measurements are only taken during the eclipse portion of the orbit, the look directions cover nearly the entire anti-sunward hemisphere. This seven-year record of Lyman alpha airglow observations (2003-2010) shows the response of the Hydrogen geocorona to changes in the solar Lyman alpha irradiance over the solar cycle.

  15. Lyman edges - Signatures of accretion disks

    NASA Astrophysics Data System (ADS)

    Kinney, A. L.

    1992-05-01

    Accretion disks are thought to provide the ultraviolet emission seen in the big blue bump of quasars. However, observations of the UV spectra of quasars do not show the additional signatures predicted by the accretion disk models. This paper will concentrate on just one of those signatures - the Lyman edge. Two studies are briefly discussed which explore the Lyman edge region of both high and low redshift quasars (Antonucci, Kinney, and Ford 1989 and Koratkar, Kinney, and Bohlin 1992). Both studies find that Lyman edges are not present in quasar spectra as frequently as predicted by the models or at the strength predicted by accretion disk models.

  16. Asperger syndrome in India: findings from a case-series with respect to clinical profile and comorbidity.

    PubMed

    Sreedaran, Priya; Ashok, M V

    2015-01-01

    Asperger syndrome (AS) is an autism spectrum disorder with a high rate of psychiatric comorbidity. We describe the clinical profile and psychiatric comorbidity in a series of affected individuals referred to an Indian general hospital psychiatry setting. Gilliam Asperger's disorder scale was used to evaluate the clinical characteristics while Mini-International Neuropsychiatric Interview (MINI)-KID and MINI-PLUS were used to assess psychiatric comorbidity. The profile of subjects with AS in our case-series appears similar to that published elsewhere with high rates of psychiatric comorbidity. Mental health professionals should evaluate for psychiatric comorbidity in individuals with autism spectrum disorders. PMID:25969609

  17. New analysis of the Voyager UVS H Lyman-alpha emission of Saturn

    NASA Technical Reports Server (NTRS)

    Jaffel, L. Ben; Prange, R.; Sandel, B. R.; Yelle, R. V.; Emerich, C.; Feng, D.; Hall, D. T.

    1995-01-01

    The limb to limb Lyman-alpha reflectivities observed with the Voyager ultraviolet spectrometer (UVS) instruments during the fly-by of Saturn are reanalyzed using a revised H Lyman-alpha sensitivity for the Voyager 1 instrument. The new sensitivity reconciles the measured intensities to those of Voyager 2 and gives a coherent set of data. To fit the UV airglow observations, four sources are considered: (1) H resonance and H2 Rayleigh scattering of solar Lyman-alpha radiation, (2) the interplanetary Lyman-alpha radiation, (3) a possible internal source of unknown origin, (4) the possibility of atmospheric turbulence recently proposed to explain the Lyman-alpha bulge of Jupiter. The analysis supports neither a dominant collisional excitation source for the UV emissions nor the presence of strong atmospheric turbulence. The best fit, in terms of brightness but also in terms of shape of the limb to limb profile (that is to say independent on the absolute calibrations), is obtained for pure resonance and Rayleigh scattering of solar and interstellar wind line in an atmosphere enriched in atomic hydrogen up to three times the standard model. Influx of water from the rings of Saturn may provide a means for producing such enhanced H densities in the upper atmosphere.

  18. On the analysis of the H Lyman-alpha dayglow of Jupiter, Saturn and Uranus

    NASA Astrophysics Data System (ADS)

    Emerich, C.; Ben Jaffel, L.; Prange, R.

    1993-05-01

    A new radiative transfer model, particularly well adapted to calculations in inhomogeneous atmospheres, has been applied, during the last four years, to analyze new and older Lyman-alpha airglow data from three giant planets. We review all the results obtained so far. Several features which were not accounted for by using the previous transfer codes were satisfactorily simulated, using essentially the scattering of the solar and the interplanetary Lyman-alpha lines by hydrogen in the upper atmospheres. The search for a good fit both in intensity and in shape of the limb to limb data, and/or of the line profiles, provided constraints on the dynamics of the atmospheres, through the estimate of either the eddy diffusion coefficient, the total H column density, or of the possibility of some nonthermal turbulence processes at high altitude. Consequently, the need for an 'electroglow' process for the Lyman-alpha emission was considerably reduced and may be dismissed in the majority of cases.

  19. Free-energy-based methods for binding profile determination in a congeneric series of CDK2 inhibitors.

    PubMed

    Fidelak, Jérémy; Juraszek, Jarek; Branduardi, Davide; Bianciotto, Marc; Gervasio, Francesco Luigi

    2010-07-29

    Free-energy pathway methods show great promise in computing the mode of action and the free energy profile associated with the binding of small molecules with proteins, but are generally very computationally demanding. Here we apply a novel approach based on metadynamics and path collective variables. We show that this combination is able to find an optimal reaction coordinate and the free energy profile of binding with explicit solvent and full flexibility, while minimizing human intervention and computational costs. We apply it to predict the binding affinity of a congeneric series of 5 CDK2 inhibitors. The predicted binding free energy profiles are in accordance with experiment. PMID:20593892

  20. Population Profiles; A Series of 14 Units, Plus Extras, for the Study of Demography. Numbers 8 and 9.

    ERIC Educational Resources Information Center

    Lee, Everett S.; Bouvier, Leon F.

    "Growth and Future of Cities" and "The Nation's Minorities" are units eight and nine, respectively from the fourteen-units series Population Profiles. The former initiates its consideration of our urban future with two divergent points of view on population distribution. Those views are brought into perspective by an historical investigation of…

  1. Simultaneous measurements of the hydrogen airglow emissions of Lyman alpha, Lyman beta, and Balmer alpha.

    NASA Technical Reports Server (NTRS)

    Weller, C. S.; Meier, R. R.; Tinsley, B. A.

    1971-01-01

    Comparison of Lyman-alpha, 740- to 1050-A, and Balmer-alpha airglow measurements made at 134 deg solar-zenith angle on Oct. 13, 1969, with resonance-scattering models of solar radiation. Model comparison with Lyman-alpha data fixes the hydrogen column abundance over 215 km to 2 x 10 to the 13th per cu cm within a factor of 2. Differences between the Lyman-alpha model and data indicate a polar-equatorial departure from spherical symmetry in the hydrogen distribution. A Lyman-beta model based on the hydrogen distribution found to fit the Lyman-alpha data fits the spatial variation of the 740- to 1050-A data well from 100 to 130 km, but it does not fit the data well at higher altitudes; thus the presence of more rapidly absorbed shorter-wavelength radiation is indicated. This same resonance-scattering model yields Balmer-alpha intensities that result in good spatial agreement with the Balmer-alpha measurements, but a fivefold increase in the measured solar line center Lyman-beta flux is required (as required for the Lyman-beta measurement). The intensity ratio of Lyman-beta and Balmer-alpha at night is found to be a simple measure of the hydrogen optical depth if measurements with good accuracy can be made in the visible and ultraviolet spectrum.

  2. Bed surface bed profile adjustments to a series of water pulses in gravel bed rivers

    NASA Astrophysics Data System (ADS)

    Ferrer-Boix, C.; Hassan, M. A.

    2014-12-01

    This research aims to explore the interactions between the bed surface texture, the bed topography and the sediment transport (rate and grain size distribution) to a series of water pulses in gravel bed-rivers. We conducted a set of runs in a 18 m-long tilting flume, 1 m-wide. Low flow discharges (Q = 65 l/s) during periods of variable duration (between t = 10 h and t = 1 h) were alternated with high flow rates (Q = 90 l/s) of constant duration (t = 1.5 h). Sediment was fed at a constant rate (Qfeed = 7.5 kg/h) throughout the runs. Eight experiments were consecutively conducted: the final configuration of the previous run was the initial condition for the subsequent experiment. The initial bed texture of the experiments was obtained after a 280 h-long run at low flow, the last 40 h of which under starving conditions. The initial bed slope was S0 = 0.022 m/m. A poorly-sorted grain size distribution (Dg = 5.65 mm and sg = 3.05) was used as a feeding material. The same material was used as the initial condition for the antecedent experiment (280 h-long). Intensive measurements of the bed surface, bed topography and sediment transport were taken during the runs. Provisional results of the experimental campaign demonstrate that: (i) bed topography rapidly adjusts to water pulses: bed aggrades during low flow periods to subsequently degrade during water pulses. However, the rate of change of the bed profile decreases with the number of water pulses; (ii) the surface texture maintains an approximately invariant texture during the runs with no significant changes before and after the pulses; (iii) bedload transport dramatically adjusts to water pulses (increasing its rate and getting coarser). The relative increase in the bedload transport during the pulses diminishes as the number of pulses increases. A detailed analysis of the evolution of the bed profile shows the formation of transverse ribs during low flow periods which slowly migrate upstream. These bedforms are not

  3. Biography Today: Profiles of People of Interest to Young Readers. Author Series, Volume 1.

    ERIC Educational Resources Information Center

    Harris, Laurie Lanzen, Ed.

    The serialized reference work "Biography Today" is initiating a "Subject Series" that in five separate volumes will encompass: authors, artists, scientists, and inventors, sports figures, and world leaders. This is the first volume in the "Author Series." There will be no duplication between the regular series and the special subject volumes. This…

  4. Sun-as-a-Star Observation of Flares in Lyman α by the PROBA2/LYRA Radiometer

    NASA Astrophysics Data System (ADS)

    Kretzschmar, M.; Dominique, M.; Dammasch, I. E.

    2013-08-01

    There are very few reports of flare signatures in the solar irradiance at H i Lyman α at 121.5 nm, i.e. the strongest line of the solar spectrum. The LYRA radiometer onboard PROBA2 has observed several flares for which unambiguous signatures have been found in its Lyman-α channel. Here we present a brief overview of these observations followed by a detailed study of one of them: the M2 flare that occurred on 8 February 2010. For this flare, the flux in the LYRA Lyman-α channel increased by 0.6 %, which represents about twice the energy radiated in the GOES soft X-ray channel and is comparable with the energy radiated in the He ii line at 30.4 nm. The Lyman-α emission represents only a minor part of the total radiated energy of this flare, for which a white-light continuum was detected. Additionally, we found that the Lyman-α flare profile follows the gradual phase but peaks before other wavelengths. This M2 flare was very localized and had a very brief impulsive phase, but more statistics are needed to determine if these factors influence the presence of a Lyman-α flare signal strong enough to appear in the solar irradiance.

  5. Soil formation rates determined from Uranium-series isotope disequilibria in soil profiles from the southeastern Australian highlands

    NASA Astrophysics Data System (ADS)

    Suresh, P. O.; Dosseto, A.; Hesse, P. P.; Handley, H. K.

    2013-10-01

    The sustainability of soil resources is determined by the balance between the rates of production and removal of soils. Samples from four weathering profiles at Frogs Hollow in the upper catchment area of the Murrumbidgee River (southeastern Australia) were analyzed for their uranium-series (U-series) isotopic composition to estimate soil production rates. Sequential leaching was conducted on sample aliquots to assess how U-series nuclides are distributed between primary and secondary minerals. Soil is increasingly weathered from bottom to top which is evident from the decrease in (234U/238U) ratios and increase in relative quartz content with decreasing soil depth. One soil profile shows little variation in mineralogy and U-series geochemistry with depth, explained by the occurrence of already extensively weathered saprolite, so that further weathering has minimal effect on mineralogy and geochemistry. Al2O3 is mobilized from these soils, and hence a silicon-based weathering index treating Al2O3 as mobile is introduced, which increases with decreasing soil depth, in all profiles. Leached and unleached aliquots show similar mineralogy with slight variation in relative concentrations, whereas the elemental and isotopic composition of uranium and thorium show notable differences between leached and unleached samples. Unleached samples show systematic variations in uranium-series isotopic compositions with depth compared to leached samples. This is most likely explained by the mobilization of U and Th from the samples during leaching. Soil residence times are calculated by modeling U-series activity ratios for each profile separately. Inferred timescales vary up to 30 kyr for unleached aliquots from profile F1 to up to 12 kyr for both leached and unleached aliquots from profile F2. Muscovite content shows a linear relationship with U-series derived soil residence times. This relationship provides an alternative method to estimate residence timescales for profiles with

  6. The Lyman alpha reference sample

    NASA Astrophysics Data System (ADS)

    Adamo, Angela; Östlin, Göran; Hayes, Matthew; Melinder, Jens; Bik, Arjan

    2015-08-01

    The Lyman apha reference sample (LARS) is a major multiwavelength imaging and spectroscopic HST campaign of local normal star-forming galaxies, UV-luminous starburst systems, and luminous infrared galaxies. The aim of this survey is to probe what physical conditions and processes regulate the emission of Lyα radiation on local and global galactic scales. The Lyα line is widely used to identify and confirm galaxies in the distant universe, close to the epoch when the first galaxies formed and when the universe was reionized. However, the fact that Lyα is a resonant line makes it optically thick even at relatively low neutral hydrogen column densities, this means that the radiative transport of Lyα photons through galaxies is a complex problem where the structure, kinematics and dust content, and neutral hydrogen content of the interstellar medium all contribute to the process. In this poster we present the unique Lyα maps of the extended LARS sample (i.e. 42 galaxies). These initial results of the LARS survey reveal that when Lyα manages to escape it does so in the form of diffuse scattering halos.

  7. Lyman-alpha imagery of Comet Kohoutek

    NASA Technical Reports Server (NTRS)

    Carruthers, G. R.; Opal, C. B.; Page, T. L.; Meier, R. R.; Prinz, D. K.

    1974-01-01

    Electrographic imagery of Comet Kohoutek in the 1100-1500 A wavelength range was obtained from a sounding rocket on Jan. 8, 1974, and from the Skylab space station on 13 occasions between Nov. 26, 1973 and Feb. 2, 1974. These images are predominantly due to Lyman-alpha (1216 A) emission from the hydrogen coma of the comet. The rocket pictures have been calibrated for absolute sensitivity and a hydrogen production rate has been determined. However, the Skylab camera suffered degradation of its sensitivity during the mission, and its absolute sensitivity for each observation can only be estimated by comparison of the comet images with those taken by the rocket camera, with imagery of the geocoronal Lyman-alpha glow, of the moon in reflected Lyman-alpha, and of ultraviolet-bright stars. The rocket and geocoronal comparisons are used to derive a preliminary, qualitative history of the development of the cometary hydrogen coma and the associated hydrogen production rate.

  8. 238U, 232Th profiling and U-series isotope analysis of fossil teeth by laser ablation-ICPMS

    NASA Astrophysics Data System (ADS)

    Eggins, Stephen; Grün, Rainer; Pike, Alistair W. G.; Shelley, Michael; Taylor, Lois

    2003-05-01

    U and Th concentration profiles in fossil hominid and faunal teeth have been measured by laser ablation ICPMS. These profiles record diverse modes of U and Th uptake, particularly within enamel, that can be broadly related to the state of sample preservation. Observed U profiles are in general inconsistent with existing diffusion-adsorption models developed for U-uptake in bone and teeth. Where the models appear applicable, calculated diffusion rates are several orders of magnitude smaller than previous estimates. Laser ablation ICPMS offers a means of rapidly characterizing U and Th distributions in the enamel and dentine components of teeth as a precursor to ESR and U-series dating. In particular, it should allow the identification of teeth (and also bone) samples that have simple U-uptake histories and are amenable to precise dating by time-consuming and expensive Th-U and Pa-U TIMS techniques. We also demonstrated the use of laser ablation ICPMS to measure U-series isotopes in dentine and enamel samples with relatively high U concentrations (>20 ppm). These results, obtained using a quadrupole ICPMS, illustrate significant promise for in situ U-series isotope analysis, particularly when combined with the greater sensitivity and multi-collection capabilities of new sector ICPMS instrumentation. The latter may permit precise isotope ratio measurements on samples containing only a few ppm of U.

  9. Administrative Information Systems: The 1985 Profile and Five-Year Trends. CAUSE Monograph Series.

    ERIC Educational Resources Information Center

    Thomas, Charles R.; van Hoesen, Dana S.

    Information is presented about the administrative computing activities of colleges and universities belonging to CAUSE (the professional association for computing and information technology in higher education). Profiles and trends are provided based on 1985 Member Institution Profile Surveys conducted in 1980, 1983, and 1985. A total of 350…

  10. Quantifying Groundwater Discharge and Streambed Heat Flux in Fortune Creek, British Columbia, Using Time Series of Streambed Temperature Profiles

    NASA Astrophysics Data System (ADS)

    McGrath, E. O.; Nichol, C.; Wei, A.

    2009-05-01

    Time series of streambed temperature profiles and hydraulic head measurements in piezometers were used to characterize groundwater discharge to a small salmonid stream in the interior of British Columbia. Of particular interest was the heat flux into and out of the streamed resulting from groundwater discharge, in light of providing cool water habitat for salmonid species. The larger study objectives were to link salmonid habitat use to habitat quality, including water temperature. Over the summer of 2008, streambed temperature profiles were collected at eight locations along the stream and in two piezometers in a known groundwater upwelling area. Water levels were recorded continuously in the piezometers. Streambed temperature profiles were used in an analytical solution of the one dimensional groundwater and heat flow equation to estimate groundwater flux into and out of the stream. In addition, a time- series analytical model was used to quantify groundwater and heat flux throughout the low flow season using transient temperature profile data. Groundwater flux estimates derived from the models were compared to flux estimates derived from head measurements and slug testing of the piezometers. Heat flux estimates from groundwater were incorporated into an energy balance model assessing the cooling effect of groundwater discharge on stream temperatures.

  11. HETDEX: Developing the HET's Second Generation Low Resolution Spectrograph for Probing Lyman-alpha Emitting Galaxies

    NASA Astrophysics Data System (ADS)

    Chonis, Taylor S.; Hill, G. J.; Lee, H.; Tuttle, S. E.; Vattiat, B. L.; Gebhardt, K.; Finkelstein, S. L.; Adams, J. J.; HETDEX Collaboration

    2012-01-01

    HETDEX will map the power spectrum of 0.8 million blindly discovered Lyman-alpha Emitting Galaxies (LAE) using a revolutionary new array of massively replicated fiber-fed spectrographs dubbed the Visible Integral-Field Replicable Unit Spectrograph (VIRUS). In the era of the Hobby-Eberly Telescope wide-field upgrade and VIRUS, the current Low Resolution Spectrograph (LRS) must be replaced with a fiber instrument. We discuss the development of the second generation LRS (LRS2), which is a multi-channel instrument based on the VIRUS design. In its current design phase, it is fed by a 287 fiber microlens coupled integral field unit that covers 7” x 12” with 0.62” resolution. The instrument covers 3720 Å to 4700 Å at R ≈ 1900 and 4600 Å to 7000 Å at R ≈1200. With the purpose of making the instrument ideal for follow-up observations of LAE in the HETDEX survey, we discuss the science drivers for selecting the instrument's spectral resolution. We test the utility of the instrument and pilot a future study with LRS2 by presenting R ≈ 2000 spectra taken with the VIRUS prototype spectrograph (VIRUS-P) in a high-resolution mode at the McDonald Observatory Harlan J. Smith 2.7 m telescope. These LAE were originally discovered in the HETDEX Pilot Survey and their Lyman-alpha line profiles are constrained by near-infrared observations of rest-frame optical emission lines that set the systemic redshift of the galaxies. We discuss the velocity offsets of the Lyman-alpha line from the systemic line center and compare the line profiles to theoretical predictions and to similar observations for Lyman-break galaxies. Our observations provide an example of how LRS2 can be used to probe Lyman-alpha emission in 2 < z < 3 star forming galaxies.

  12. A Sounding Rocket Experiment for the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP)

    NASA Technical Reports Server (NTRS)

    Kubo, M.; Kano, R.; Kobayashi, K.; Ishikawa, R.; Bando, T.; Narukage, N.; Katsukawa, Y.; Ishikawa, S.; Suematsu, Y.; Hara, H.; Tsuneta, S.; Shimizu, T.; Sakao, T.; Ichimoto, K.; Winebarger, A.; Cirtain, J.; De Pontieu, B.; Casini, R.; Auchere, F.; Trujillo, Bueno J.; Manso, Sainz R.; Ramos, Asensio A.; Stepan, J.; Belluzi, L.; Carlsson, M.

    2014-01-01

    A sounding-rocket experiment called the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is presently under development to measure the linear polarization profiles caused by scattering processes and the Hanle effect in the hydrogen Lyman-alpha line (121.567nm). Accurate measurements of the linear polarization signals caused by scattering processes and the Hanle effect are essential to explore the strength and structures of weak magnetic fields. The primary target of future solar telescopes is to measure the weak magnetic field in outer solar atmospheres (from the chromosphere to the corona through the transition region). The hydrogen Lyman-alpha-line is one of the best lines for the diagnostics of magnetic fields in the outer solar atmospheres. CLASP is to be launched in 2015, and will provide, for the first time, the observations required for magnetic field measurements in the upper chromosphere and transition region. CLASP is designed to have a polarimetric sensitivity of 0.1% and a spectral resolution of 0.01nm for the Lyman-alpha line. CLASP will measure two orthogonal polarizations simultaneously for about 5-minute flight. Now the integration of flight mirrors and structures is in progress. In addition to our strategy to realize such a high-precision spectro-polarimetry in the UV, we will present a progress report on our pre-launch evaluation of optical and polarimetric performances of CLASP.

  13. High efficiency SNAP survey for Lyman alpha emitters at low redshift

    NASA Astrophysics Data System (ADS)

    McCandliss, Stephan

    2014-10-01

    The goal of this proposal is to provide the first statistically significant survey of star-forming galaxies with Lyman alpha emission at redshifts 0.02 < z < 0.24. It will provide an overall assessment of the evolution in Lyman alpha luminosity at the lowest redshifts and allowed detailed studies of the physical processes that shape the Lyman alpha profile and govern escape in multi-phase, kinematic media. It will also provide a serendipitous search for star-forming galaxies with high LyC escape fractions that are analogous to those commonly invoked as being responsible for initiating and sustaining the epoch of reionization. The SNAP survey proposed here employing the G140L mode of COS offers a highly efficient means to examine the Lyman alpha emission properties of our candidate emitters and to inform our choice of objects that could warrant deeper integrations in future observations. These data have high UV legacy value and will be of broad interest to the star-forming galaxy community, so we have elected to waive the proprietary period.

  14. Shedding Lyman Alpha Light on Cosmological Reionization

    NASA Astrophysics Data System (ADS)

    Rhoads, James E.; Malhotra, Sangeeta; Ammons, S. Mark; Dressler, Alan; Gonzalez, Alicia; Finkelstein, Steven; Hibon, Pascale; Jiang, Tianxing; Lee, Janice; Mobasher, Bahram; Monson, Andy; Persson, S. Eric; Probst, Ronald; Swaters, Rob; Tilvi, Vithal S.; Veilleux, Sylvain; Wang, Junxian; Zabludoff, Ann; Zheng, Zhenya

    2015-08-01

    Lyman alpha photons are a powerful tool for studying reionization. They interact strongly with neutral hydrogen, so that neutral intergalactic gas acts to hide Lyman alpha light from our instruments. I will discuss two ongoing narrowband surveys to study the Epoch of Reionization. The Deep And Wide Narrowband (DAWN) survey is a 40 night NOAO survey program to look for Lyman alpha emission at redshift 7.7, using the NEWFIRM camera on the 4m Mayall Telescope at Kitt Peak National Observatory. The First Light And Reionization Experiment (FLARE) is pursuing a corresponding survey at redshift 8.8, using the FourStar camera on the Magellan telescope. Both surveys are motivated by the application of Lyman alpha lines to the study of reionization. Reionization marked the first global impact that gravitationally bound objects (stars and/or black holes) had on the universe around them, and also the last time that most hydrogen atoms did anything noteworthy. I will present results from both the DAWN and FLARE surveys, which have identified candidate galaxies near redshifts 7.7 and 8.8 in multiple fields.

  15. Epileptic Electroencephalography Profile Associates with Attention Problems in Children with Fragile X Syndrome: Review and Case Series.

    PubMed

    Cowley, Benjamin; Kirjanen, Svetlana; Partanen, Juhani; Castrén, Maija L

    2016-01-01

    Fragile X syndrome (FXS) is the most common cause of inherited intellectual disability and a variant of autism spectrum disorder (ASD). The FXS population is quite heterogeneous with respect to comorbidities, which implies the need for a personalized medicine approach, relying on biomarkers or endophenotypes to guide treatment. There is evidence that quantitative electroencephalography (EEG) endophenotype-guided treatments can support increased clinical benefit by considering the patient's neurophysiological profile. We describe a case series of 11 children diagnosed with FXS, aged one to 14 years, mean 4.6 years. Case data are based on longitudinal clinically-observed reports by attending physicians for comorbid symptoms including awake and asleep EEG profiles. We tabulate the comorbid EEG symptoms in this case series, and relate them to the literature on EEG endophenotypes and associated treatment options. The two most common endophenotypes in the data were diffuse slow oscillations and epileptiform EEG, which have been associated with attention and epilepsy respectively. This observation agrees with reported prevalence of comorbid behavioral symptoms for FXS. In this sample of FXS children, attention problems were found in 37% (4 of 11), and epileptic seizures in 45% (5 of 11). Attention problems were found to associate with the epilepsy endophenotype. From the synthesis of this case series and literature review, we argue that the evidence-based personalized treatment approach, exemplified by neurofeedback, could benefit FXS children by focusing on observable, specific characteristics of comorbid disease symptoms. PMID:27462212

  16. Epileptic Electroencephalography Profile Associates with Attention Problems in Children with Fragile X Syndrome: Review and Case Series

    PubMed Central

    Cowley, Benjamin; Kirjanen, Svetlana; Partanen, Juhani; Castrén, Maija L.

    2016-01-01

    Fragile X syndrome (FXS) is the most common cause of inherited intellectual disability and a variant of autism spectrum disorder (ASD). The FXS population is quite heterogeneous with respect to comorbidities, which implies the need for a personalized medicine approach, relying on biomarkers or endophenotypes to guide treatment. There is evidence that quantitative electroencephalography (EEG) endophenotype-guided treatments can support increased clinical benefit by considering the patient's neurophysiological profile. We describe a case series of 11 children diagnosed with FXS, aged one to 14 years, mean 4.6 years. Case data are based on longitudinal clinically-observed reports by attending physicians for comorbid symptoms including awake and asleep EEG profiles. We tabulate the comorbid EEG symptoms in this case series, and relate them to the literature on EEG endophenotypes and associated treatment options. The two most common endophenotypes in the data were diffuse slow oscillations and epileptiform EEG, which have been associated with attention and epilepsy respectively. This observation agrees with reported prevalence of comorbid behavioral symptoms for FXS. In this sample of FXS children, attention problems were found in 37% (4 of 11), and epileptic seizures in 45% (5 of 11). Attention problems were found to associate with the epilepsy endophenotype. From the synthesis of this case series and literature review, we argue that the evidence-based personalized treatment approach, exemplified by neurofeedback, could benefit FXS children by focusing on observable, specific characteristics of comorbid disease symptoms. PMID:27462212

  17. The Advancement President and the Academy: Profiles in Institutional Leadership. Series on Higher Education.

    ERIC Educational Resources Information Center

    Murphy, Mary Kay, Ed.

    This book presents 15 essays concerning the growing importance of institutional advancement experience to winning and successfully conducting a college or university presidency. This is a series of essays by successful university CEOs who achieved their positions from an advancement background and who clearly understand the importance of…

  18. Biography Today: Profiles of People of Interest to Young Readers. Author Series, Volume 7.

    ERIC Educational Resources Information Center

    Harris, Laurie Lanzen, Ed.; Abbey, Cherie D., Ed.

    This book presents biographical profiles of 10 authors of interest to readers ages 9 and above and was created to appeal to young readers in a format they can enjoy reading and readily understand. Biographies were prepared after extensive research, and each volume contains a cumulative index, a general index, a place of birth index, and a birthday…

  19. Biography Today: Profiles of People of Interest to Young Readers. Sports Series, Volume 7.

    ERIC Educational Resources Information Center

    Abbey, Cherie D., Ed.

    This volume provides biographies on sports figures. Each entry offers at least one picture of the individual profiled, and bold-faced rubrics lead to information on birth, youth, early memories, education, first jobs, marriage and family, career highlights, memorable experiences, hobbies, and honors and awards. Each entry ends with a list of…

  20. Biography Today: Profiles of People of Interest to Young Readers. Scientists & Inventors Series.

    ERIC Educational Resources Information Center

    Abbey, Cherie D., Ed.

    2002-01-01

    This volume on "Scientists and Inventors" was created to appeal to young readers in a format they can enjoy reading and can readily understand. Each volume contains alphabetically arranged sketches of outstanding people. Each entry provides at least one picture of the individual profiled, and bold-faced rubrics lead the reader to information on…

  1. Occupational Competency Profile for Health Occupations Education Program: Health Agency Assessment. Information Series: Report No. 10.

    ERIC Educational Resources Information Center

    Walters, Norma J.

    This assessment instrument is intended to provide health occupations teachers and state departments of education with information needed to revise and improve the curriculum used in training prospective health occupations teachers and in updating certification requirements for practicing health care professionals. The profile lists the…

  2. Brazil: Secondary Education Profile. A Summary of "Secondary Education: Time to Move Forward." Secondary Education Series.

    ERIC Educational Resources Information Center

    Larach, Linda

    This paper provides a brief profile of the state of secondary education in Brazil. An overview of the organizational structure, objectives, curricular offerings, system size, and governance structure of secondary education is provided. Issues relating to the quality, equity, management, and financing of the system are discussed, and promising…

  3. Biography Today: Profiles of People of Interest to Young Readers. Author Series, Volume 14.

    ERIC Educational Resources Information Center

    Abbey, Cherie D., Ed.

    This special subject volume of biographies of authors was created to appeal to young readers in a format they can enjoy reading and readily understand. Each entry provides at least one picture of the individual profiled, and bold-faced rubrics lead the reader to information on birth, youth, early memories, education, first jobs, marriage and…

  4. Biography Today: Profiles of People of Interest to Young Readers. Sports Series.

    ERIC Educational Resources Information Center

    Abbey, Cherie D., Ed.

    2002-01-01

    This book presents biographical profiles of 10 athletes of interest to readers ages 9 and above and was created to appeal to young readers in a format they can enjoy and readily understand. Biographies were prepared after extensive research, and each volume contains a cumulative index, a general index, a place of birth index, and a birthday index.…

  5. Biography Today: Profiles of People of Interest to Young Readers. Sports Series, Volume 8.

    ERIC Educational Resources Information Center

    Abbey, Cherie D., Ed.

    This volume provides biographies on sports figures. Each entry offers at least one picture of the individual profiled, and bold-faced rubrics lead to information on birth, youth, early memories, education, first jobs, marriage and family, career highlights, memorable experiences, hobbies, and honors and awards. Each entry ends with a list of…

  6. Biography Today. Profiles of People of Interest to Young Readers. Artists Series. Vol. 1, 1996.

    ERIC Educational Resources Information Center

    Harris, Laurie Lanzen, Ed.; Abbey, Cherie D., Ed.

    This issue of "Biography Today" features 18 short biographies about artists in a format young readers can enjoy and understand. Each entry provides at least one picture of the individual profiled, and bold-faced rubrics lead the reader to information on birth, youth, early memories, education, first jobs, marriage and family, career highlights,…

  7. School Satisfaction: A Statistical Profile of Cities and Suburbs. ETS Leadership 2000 Series.

    ERIC Educational Resources Information Center

    Carnevale, Anthony P.; Desrochers, Donna M.

    This document profiles opinions on education quality in 55 of the largest cities in the United States. The findings were drawn from a survey analyzed by the Educational Testing Service in which parents were asked their opinions on the public elementary schools in their neighborhood, their views on crime and neighborhood choice, and whether…

  8. Biography Today: Scientists & Inventors Series. Profiles of People of Interest to Young Readers. Vol. 1, 1996.

    ERIC Educational Resources Information Center

    Harris, Laurie Lanzen, Ed.; Abbey, Cherie D., Ed.

    This issue of "Biography Today" looks at scientists and inventors and is created to appeal to young readers in a format they can and enjoy and easily understand. Each entry provides at least one picture of the individual profiled, and bold-faced rubrics lead the reader to information on birth, youth, early memories, education, first jobs, marriage…

  9. Biography Today: Profiles of People of Interest to Young Readers. Author Series, Volume 9.

    ERIC Educational Resources Information Center

    Abbey, Cherie D., Ed.

    This book presents biographical profiles of 10 authors of interest to readers ages 9 and above and was created to appeal to young readers in a format they can enjoy and readily understand. Biographies were prepared after extensive research, and each volume contains a cumulative index, a general index, a place of birth index, and a birthday index.…

  10. Io's Atmosphere Silhouetted in Transit by Jupiter Lyman-alpha

    NASA Astrophysics Data System (ADS)

    Retherford, Kurt

    2014-10-01

    Io's active volcanos both directly establish local gas plumes and indirectly establish a more global sublimation atmosphere, through plume deposited sulfur dioxide frost patches. Despite decades of study and recent observational advances the very basic question about the relative role of each of these sources is unresolved. The correlation between volcanic activity variability and Io's dramatic influence on numerous time-variable phenomenon in the Jupiter system cannot be causally linked until this answer is in hand. Our experienced team has developed a novel approach to use STIS in a new way to obtain global radial profiles of SO2 scale height distributions above both plume and sublimation dominated regions. We exploit the bright Lyman-alpha dayglow of Jupiter as a background illumination source together with the strongly absorptive nature of SO2 at 121.6 nm to image Io's atmosphere in silhouette with unprecedented detail during transit events. Our program provides the following key information for SO2: 1) First high-altitude (>400 km) radial measurements of tangential column densities and scale heights; 2) First clear measurement of sublimation densities at polar locations; 3) Volcanic densities for large and mid-sized plumes (possibly new ones); 4) Globally distributed limb profiles allowing strong distinctions between plume and sublimation dominated locations; 5) Repeated imaging on a few day and a few week timescales for improved plume variability constraints; and 6) Lyman-alpha reflectance imaging at Io central lon. ~180 deg, filling a gap in previous coverage. These new information are critical to breaking through an impasse in our understanding of Io's atmosphere.

  11. Mapping forest height, foliage height profiles and disturbance characteristics with time series of gap-filled Landsat and ALI imagery

    NASA Astrophysics Data System (ADS)

    Helmer, E.; Ruzycki, T. S.; Wunderle, J. M.; Kwit, C.; Ewert, D. N.; Voggesser, S. M.; Brandeis, T. J.

    2011-12-01

    We mapped tropical dry forest height (RMSE = 0.9 m, R2 = 0.84, range 0.6-7 m) and foliage height profiles with a time series of gap-filled Landsat and Advanced Land Imager (ALI) imagery for the island of Eleuthera, The Bahamas. We also mapped disturbance type and age with decision tree classification of the image time series. Having mapped these variables in the context of studies of wintering habitat of an endangered Nearctic-Neotropical migrant bird, the Kirtland's Warbler (Dendroica kirtlandii), we then illustrated relationships between forest vertical structure, disturbance type and counts of forage species important to the Kirtland's Warbler. The ALI imagery and the Landsat time series were both critical to the result for forest height, which the strong relationship of forest height with disturbance type and age facilitated. Also unique to this study was that seven of the eight image time steps were cloud-gap-filled images: mosaics of the clear parts of several cloudy scenes, in which cloud gaps in a reference scene for each time step are filled with image data from alternate scenes. We created each cloud-cleared image, including a virtually seamless ALI image mosaic, with regression tree normalization of the image data that filled cloud gaps. We also illustrated how viewing time series imagery as red-green-blue composites of tasseled cap wetness (RGB wetness composites) aids reference data collection for classifying tropical forest disturbance type and age.

  12. Seeing Galaxies Through the Forest: Spectral Stacking of Damped Lyman Alpha Systems

    NASA Astrophysics Data System (ADS)

    Yen, Steffi; Jorgenson, R.; Murphy, M.

    2013-01-01

    Damped Lyman alpha Systems (DLAs) are the highest column density (N(HI) >= 2x10^20 cm^-2) neutral gas absorbers detected in the sightlines to distant quasars. DLAs dominate the neutral gas mass content of the Universe from z=[0,5], suggesting that they are the reservoirs of neutral gas for star formation across cosmic time. However, the nature of DLAs is not fully understood because they are detected in absorption against the light of background quasars. The resulting spectra contain absorption from the Lyman alpha forest, a series of smaller neutral hydrogen lines, essentially filaments of neutral gas in the IGM. At high redshifts (z >= 2), the forest becomes quite thick, making it difficult to distinguish intervening forest lines from metal lines of the DLA. By employing the technique of spectral stacking, we essentially subtract the incoherent Lyman alpha forest lines, enabling us to measure metal lines that typically fall in the forest region, such as O VI, N V, and molecular hydrogen. In addition, the increased signal-to-noise ratio in the DLA stack allows us to search for the presence of weak metal lines and/or Lyman alpha emission not typically seen in a single DLA spectrum. We will present the results obtained from our stack of 97 high-resolution (FWHM ~ 8 km/s) VLT/UVES spectra. Initial analysis of the stack shows a possible detection of Lyman alpha emission in the DLA trough. We will combine this VLT/UVES stack with a previously created stack of ~110 Keck/HIRES spectra to create the highest signal-to-noise ratio, high-resolution DLA spectral stack. Analysis of this final stack will shed new light on our understanding of the role of DLAs in galaxy formation and evolution. This work was conducted by a Research Experience for Undergraduates (REU) position at the University of Hawai'i's Institute for Astronomy and funded by the NSF.

  13. Cytotoxicity Profiles for a Series of Triorganophosphinegold(I) Dithiocarbamates and Triorganophosphinegold(I) Xanthates

    PubMed Central

    de Vos, Dick; Ho, Soo Yei

    2004-01-01

    A series of triorganophosphinegold(1) dithiocarbamate (R3PAuS2CNR'2) and xanthate (R3PAuS2COR') complexes have been prepared and characterised spectroscopically. Based on crystallographic evidence, the molecules feature linear gold(1) geometries defined by sulphur and phosphorus donors. The complexes, along with a series of known anti-cancer agents, have been screened against a panel of seven human cancer cell lines. Uniformly, the dithiocarbamate derivatives are more active than their xanthate counterparts, with the most active complex being Et3PAu(S2CNEt2), and are more active than cisplatin in all cell lines screened but, not as potent as taxol. PMID:18365074

  14. High-resolution spectroscopy for Cepheids distance determination. IV. Time series of Hα line profiles

    NASA Astrophysics Data System (ADS)

    Nardetto, N.; Groh, J. H.; Kraus, S.; Millour, F.; Gillet, D.

    2008-10-01

    Context: In recent years, infrared interferometry has revealed the presence of faint dusty circumstellar envelopes (CSE) around Cepheids. However the size, shape, chemical nature, and the interaction of the CSE with the star itself are still under investigation. The presence of a CSE might have an effect on the angular diameter estimates used in the interferometric Baade-Wesselink and surface-brightness methods of determining the distance of Cepheids. Aims: By studying Hα profiles as a function of the period, we investigate the permanent mass loss and the CSE around Cepheids. Our high spectral- and time-resolution data, combined with a very good S/N, will be useful in constraining future hydrodynamical models of Cepheids atmosphere and their close environment. Methods: We present HARPS (High Accuracy Radial velocity Planetary Search project developed by the European Southern Observatory.) high-resolution spectroscopy (R = 120 000) of eight galactic Cepheids: R Tra, S Cru, Y Sgr, β Dor, zeta Gem, RZ Vel, ell Car, and RS Pup, providing a good period sampling (P = 3.39 d to P = 41.52 d). The Hα line profiles are described for all stars using a 2D (wavelength versus pulsation phase) representation. For each star, an average spectral line profile is derived, together with its first moment (γ-velocity) and its asymmetry (γ-asymmetry). Results: Short-period Cepheids show Hα line profiles following the pulsating envelope of the star, while long-period Cepheids show very complex line profiles and, in particular, large asymmetries. We find a new relationship between the period of Cepheids and their γ-velocities and -asymmetries. These results may be related to the dynamical structure of the atmosphere and to a permanent mass loss of Cepheids. In particular, we confirm for ell Car a dominant absorption component whose velocity is constant and nearly of zero km s-1 in the stellar rest frame. This component is attributed to the presence of circumstellar envelope

  15. Continuous Time Series of Water Vapor Profiles from a Combination of Raman Lidar and Microwave Radiometer

    NASA Astrophysics Data System (ADS)

    Foth, Andreas; Baars, Holger; Di Girolamo, Paolo; Pospichal, Bernhard

    2016-06-01

    In this paper, we present a method to retrieve continuous water vapor profiles from a combination of a Raman lidar and a microwave radiometer. The integrated water vapor from the microwave radiometer is used to calibrate the Raman lidar operationally resulting in small biases compared to radiosondes. The height limitations for Raman lidars (cloud base and daylight contamination) can be well compensated by the application of a two-step algorithm combining the Raman lidars mass mixing ratio and the microwave radiometers brightness temperatures.

  16. Lyman Alpha Photochemistry in the Solar Nebula

    NASA Technical Reports Server (NTRS)

    Fegley, Bruce, Jr.

    1997-01-01

    The purpose of the project "Lyman Alpha Photochemistry in the Solar Nebula" was to model photochemistry in the primitive solar nebula and the early solar systems. As part of the modeling, it was necessary to model the composition of the gas and dust accreted by the solar nebula. This final report contains a list of publications where the results of this project have been published.

  17. Does the Lyman Limit System (LLS) evolve strongly?

    NASA Astrophysics Data System (ADS)

    Fan, X.-H.; Chen, J.-S.

    1993-10-01

    Using well established statistical properties for Lyman α forest, Lyman Limit System (LLS) and the damped Lyman α system in high redshift QSOs, the computer Monte-Carlo simulated QSO spectra are constructed. The spectra are then used to calculate the average Lyman absorption D_A_ and D_B_ as a function of redshift. Both LLS models with moderate evolution suggested by Sargent et al., and with strong evolution suggested by Lanzetta are tested. The results favor the latter one, which indicates that there are much more optically thick hydrogen absorbers in the earlier epoch of the Universe.

  18. Relativistic effects in Lyman-α forest

    NASA Astrophysics Data System (ADS)

    Iršič, Vid; Di Dio, Enea; Viel, Matteo

    2016-02-01

    We present the calculation of the Lyman-alpha (Lyman-α) transmitted flux fluctuations with full relativistic corrections to the first order. Even though several studies exist on relativistic effects in galaxy clustering, this is the first study to extend the formalism to a different tracer of underlying matter at unique redshift range (z=2-5). Furthermore, we show a comprehensive application of our calculations to the Quasar-Lyman-α cross-correlation function. Our results indicate that the signal of relativistic effects are sizeable at Baryonic Acoustic Oscillation (BAO) scale mainly due to the large differences in density bias factors of our tracers. We construct an observable, the anti-symmetric part of the cross-correlation function, that is dominated by the relativistic signal and offers a new way to measure the relativistic terms at relatively small scales. The analysis shows that relativistic effects are important when considering cross-correlations between tracers with very different biases, and should be included in the data analysis of the current and future surveys. Moreover, the idea presented in this paper is highly complementary to other techniques and observables trying to isolate the effect of the relativistic corrections and thus test the validity of the theory of gravity beyond the Newtonian regime.

  19. Lyman-α Absorption from Heliotail ENAs

    NASA Astrophysics Data System (ADS)

    Wood, Brian E.; Izmodenov, Vladislav V.

    2010-12-01

    The energetic neutral atoms (ENAs) that the Interstellar Boundary Explorer (IBEX) is currently studying are messengers from the termination shock and beyond. Ultraviolet spectra from the Hubble Space Telescope (HST) provide another way to study these ENAs, which are capable of producing detectable absorption signatures in HST Lyman-α spectra of nearby stars. This broad, shallow absorption is only observed within 20° of the downwind direction. Only the lengthy downwind lines of sight through the long heliotail build up enough column density of ENAs to yield detectable absorption. The absorption therefore represents the first real observational detection of the heliotail. We try to connect ENA fluxes observed by IBEX with the Lyman-α absorption observed by HST. In the downwind direction, IBEX observes ENA fluxes that increase towards lower energies, at least to 0.2 keV, but consistency with the HST measurements seems to require that the ENA fluxes at least flatten if not decrease below 0.2 keV. The ``ribbon'' of ENAs detected by IBEX is not detected in Lyman-α absorption, which may be a problem for any explanation of the ribbon that proposes a source beyond our heliosphere.

  20. Lyman Alpha Mapping Project (LAMP) Brightness Maps

    NASA Astrophysics Data System (ADS)

    Retherford, Kurt D.; Gladstone, G.; Stern, S.; Egan, A. F.; Miles, P. F.; Parker, J. W.; Greathouse, T. K.; Davis, M. W.; Slater, D. C.; Kaufmann, D. E.; Versteeg, M. H.; Feldman, P. D.; Hurley, D. M.; Pryor, W. R.; Hendrix, A. R.

    2010-10-01

    The Lyman Alpha Mapping Project (LAMP) is an ultraviolet (UV) spectrograph on the Lunar Reconnaissance Orbiter (LRO) that is designed to map the lunar albedo at far-UV wavelengths. LAMP primarily measures interplanetary Hydrogen Lyman-alpha sky-glow and far-UV starlight reflected from the night-side lunar surface, including permanently shadowed regions (PSRs) near the poles. Dayside observations are also obtained. Brightness maps sorted by wavelength (including the Lyman-alpha wavelength of 121.6 nm) are reported for the polar regions, with a few regions of interest reported in more detail. LAMP's spectral range of 58 nm to 196 nm includes a water ice spectral feature near 160 nm, which provides a diagnostic tool for detecting water on the lunar surface that is complementary to recent discoveries using infrared and radio frequency techniques. Progress towards producing far-UV albedo maps and searching for water ice signatures will be reported. We'll discuss how LAMP data may address questions regarding how water is formed on the moon, transported through the lunar atmosphere, and deposited in the PSRs.

  1. Saprolite Formation Rates using U-series Isotopes in a Granodiorite Weathering Profile from Boulder Creek CZO (Colorado, USA)

    NASA Astrophysics Data System (ADS)

    Pelt, Eric; Chabaux, Francois; Mills, T. Joseph; Anderson, Suzanne P.; Foster, Melissa A.

    2015-04-01

    Timescales of weathering profile formation and evolution are important kinetic parameters linked to erosion, climatic, and biological processes within the critical zone. In order to understand the complex kinetics of landscape evolution, water and soil resources, along with climate change, these parameters have to be estimated for many different contexts. The Betasso catchment, within the Boulder Creek Critical Zone Observatory (BC-CZO) in Colorado, is a mountain catchment in Proterozoic granodiorite uplifted in the Laramide Orogeny ca. 50 Ma. In an exposure near the catchment divide, an approximately 1.5 m deep profile through soil and saprolite was sampled and analysed for bulk U-series disequilibria (238U-234U-230Th-226Ra) to estimate the profile weathering rate. The (234U/238U), (230Th/234U) and (226Ra/230Th) disequilibria through the entire profile are small but vary systematically with depth. In the deepest samples, values are close to equilibrium. Above this, values are progressively further from equilibrium with height in the profile, suggesting a continuous leaching of U and Ra compared to Th. The (234U/238U) disequilibria remain < 1 along the profile, suggesting no significant U addition from pore waters. Only the shallowest sample (~20 cm depth) highlights a 226Ra excess, likely resulting from vegetation cycling. In contrast, variations of Th content and (230Th/232Th) - (238U/232Th) activity ratios in the isochron diagram are huge, dividing the profile into distinct zones above and below 80 cm depth. Below 80 cm, the Th content gradually increases upward from 1.5 to 3.5 ppm suggesting a relative accumulation linked to chemical weathering. Above 80 cm, the Th content jumps to ~15 ppm with a similar increase of Th/Ti or Th/Zr ratios that clearly excludes the same process of relative accumulation. This strong shift is also observed in LREE concentrations, such as La, Ce and Nd, and in Sr isotopic composition, which suggests an external input of radiogenic

  2. Bayesian and Profile Likelihood Approaches to Time Delay Estimation for Stochastic Time Series of Gravitationally Lensed Quasars

    NASA Astrophysics Data System (ADS)

    Tak, Hyungsuk; Mandel, Kaisey; van Dyk, David A.; Kashyap, Vinay; Meng, Xiao-Li; Siemiginowska, Aneta

    2016-01-01

    The gravitational field of a galaxy can act as a lens and deflect the light emitted by a more distant object such as a quasar. If the galaxy is a strong gravitational lens, it can produce multiple images of the same quasar in the sky. Since the light in each gravitationally lensed image traverses a different path length and gravitational potential from the quasar to the Earth, fluctuations in the source brightness are observed in the several images at different times. We infer the time delay between these fluctuations in the brightness time series data of each image, which can be used to constrain cosmological parameters. Our model is based on a state-space representation for irregularly observed time series data generated from a latent continuous-time Ornstein-Uhlenbeck process. We account for microlensing variations via a polynomial regression in the model. Our Bayesian strategy adopts scientifically motivated hyper-prior distributions and a Metropolis-Hastings within Gibbs sampler. We improve the sampler by using an ancillarity-sufficiency interweaving strategy, and adaptive Markov chain Monte Carlo. We introduce a profile likelihood of the time delay as an approximation to the marginal posterior distribution of the time delay. The Bayesian and profile likelihood approaches complement each other, producing almost identical results; the Bayesian method is more principled but the profile likelihood is faster and simpler to implement. We demonstrate our estimation strategy using simulated data of doubly- and quadruply-lensed quasars from the Time Delay Challenge, and observed data of quasars Q0957+561 and J1029+2623.

  3. Testing the utility of a geographical profiling approach in three rape series of a single offender: a case study.

    PubMed

    Santtila, Pekka; Zappalà, Angelo; Laukkanen, Manne; Picozzi, Massimo

    2003-01-01

    The purpose of the study was to test the potential utility of a geographical profiling approach for three separate series of rapes committed by a single offender. Two different mathematical distance-decay functions using either a normal distribution with a mean distance and standard deviation based on previous research or a truncated negative exponential function based on distances between crime sites in the series under investigation were applied to each of the series giving prioritised search areas the accuracy of which was then assessed. The prioritised area that had to be searched before the home base of the offender could be located varied from 7.60 km(2) or 2.15% of the total search area at its best to 15 1.10 km(2) or 42.66% at its worst for the normal distribution based on previous research and from 42.06 km(2) or 11.88% to no improvement when the truncated negative exponential function was used. The functions used showed less predictive ability when the offender was a commuter. Explanations for the variations in the findings as well as suggestions for improvements were outlined in the discussion. PMID:12505470

  4. Understanding the physics driving the values of Lyman-alpha forest bias parameters

    NASA Astrophysics Data System (ADS)

    Cieplak, Agnieszka M.; Slosar, Anze

    2016-01-01

    With the advancement of Lyman-alpha forest power spectrum measurements to larger scales and to greater precision, it is crucial that we also improve our understanding of the bias between the measured flux and the underlying matter power spectrum, especially for future percent level cosmology constraints. In order to develop an intuition for the physics driving the values of the density and velocity bias parameters of the Lyman-alpha forest, we have run a series of hydrodynamic SPH simulations to test existing approximations found in the literature. Through a series of progressively more realistic scenarios, we first introduce flux based on the Fluctuating Gunn Peterson Approximation, just using the density fields, then introduce redshift space distortions, as well as thermal broadening, and finally, analyzing the full hydrodynamic part of the simulations. We find surprising agreement between the analytical approximations developed by Seljak (2012) and the numerical methods in the limit of linear redshift space-distortions and no thermal broadening. Specifically, we find that the prediction of the analytical velocity bias expression is exact in the limit of no thermal broadening, and speculate that the measurement of this bias along with a small-scale measurement of the flux PDF, could yield a possible probe of the thermal state of the IGM. A deeper understanding of the large-scale Lyman-alpha biasing will also help us in using the large-scale clustering of the forest as a cosmological probe beyond baryon acoustic oscillations.

  5. Dynamic Agricultural Land Unit Profile Database Generation using Landsat Time Series Images

    NASA Astrophysics Data System (ADS)

    Torres-Rua, A. F.; McKee, M.

    2012-12-01

    government efforts for a given occurrence at the land unit level, and affecting the potential economic trade-off level in the area. In this study a framework is proposed to create and continuously update a land unit profile database using historical Landsat satellite imagery records. An experimental test is implemented for the agricultural lands in Central Utah. This location was selected because of their success in increasing the efficiency of water use and control along the entire irrigation system. A set of crop health metrics from the literature (NDVI, LAI, NDWI) is calculated and evaluated to measure crop response to farm management for its evaluation in time. The resulting land unit profile database is then tested to determine land unit profile groups based on land unit management characteristics. Comparison with essential inputs (water availability and climate conditions) and crop type (outputs) on a year basis is provided.

  6. A Sounding Rocket Experiment for the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP)

    NASA Astrophysics Data System (ADS)

    Kubo, M.; Kano, R.; Kobayashi, K.; Bando, T.; Narukage, N.; Ishikawa, R.; Tsuneta, S.; Katsukawa, Y.; Ishikawa, S.; Suematsu, Y.; Hara, H.; Shimizu, T.; Sakao, T.; Ichimoto, K.; Goto, M.; Holloway, T.; Winebarger, A.; Cirtain, J.; De Pontieu, B.; Casini, R.; Auchère, F.; Trujillo Bueno, J.; Manso Sainz, R.; Belluzzi, L.; Asensio Ramos, A.; Štěpán, J.; Carlsson, M.

    2014-10-01

    A sounding-rocket experiment called the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is presently under development to measure the linear polarization profiles in the hydrogen Lyman-alpha (Lyα) line at 121.567 nm. CLASP is a vacuum-UV (VUV) spectropolarimeter to aim for first detection of the linear polarizations caused by scattering processes and the Hanle effect in the Lyα line with high accuracy (0.1%). This is a fist step for exploration of magnetic fields in the upper chromosphere and transition region of the Sun. Accurate measurements of the linear polarization signals caused by scattering processes and the Hanle effect in strong UV lines like Lyα are essential to explore with future solar telescopes the strength and structures of the magnetic field in the upper chromosphere and transition region of the Sun. The CLASP proposal has been accepted by NASA in 2012, and the flight is planned in 2015.

  7. Pluto's Extended Atmosphere: New Horizons Alice Lyman-α Imaging

    NASA Astrophysics Data System (ADS)

    Retherford, Kurt D.; Gladstone, G. Randall; Stern, S. Alan; Weaver, Harold A.; Young, Leslie A.; Ennico, Kimberly A.; Olkin, Cathy B.; Cheng, Andy F.; Greathouse, Thomas K.; Hinson, David P.; Kammer, Joshua A.; Linscott, Ivan R.; Parker, Alex H.; Parker, Joel Wm.; Pryor, Wayne R.; Schindhelm, Eric; Singer, Kelsi N.; Steffl, Andrew J.; Strobel, Darrell F.; Summers, Michael E.; Tsang, Constantine C. C.; Tyler, G. Len; Versteeg, Maarten H.; Woods, William W.; Cunningham, Nathaniel J.; Curdt, Werner

    2015-11-01

    Pluto's upper atmosphere is expected to extend several planetary radii, proportionally more so than for any planet in our solar system. Atomic hydrogen is readily produced at lower altitudes due to photolysis of methane and transported upward to become an important constituent. The Interplanetary Medium (IPM) provides a natural light source with which to study Pluto's atomic hydrogen atmosphere. While direct solar Lyman-α emissions dominate the signal at 121.6 nm at classical solar system distances, the contribution of diffuse illumination by IPM Lyman-α sky-glow is roughly on par at Pluto (Gladstone et al., Icarus, 2015). Hydrogen atoms in Pluto's upper atmosphere scatter these bright Lyα emission lines, and detailed simulations of the radiative transfer for these photons indicate that Pluto would appear dark against the IPM Lyα background. The Pluto-Alice UV imaging spectrograph on New Horizons conducted several observations of Pluto during the encounter to search for airglow emissions, characterize its UV reflectance spectra, and to measure the radial distribution of IPM Lyα near the disk. Our early results suggest that these model predictions for the darkening of IPM Lyα with decreasing altitude being measureable by Pluto-Alice were correct. We'll report our progress toward extracting H and CH4 density profiles in Pluto's upper atmosphere through comparisons of these data with detailed radiative transfer modeling. These New Horizons findings will have important implications for determining the extent of Pluto's atmosphere and related constraints to high-altitude vertical temperature structure and atmospheric escape.This work was supported by NASA's New Horizons project.

  8. Coastal environmental profile of South Jahore, Malaysia. Technical pub. series 6

    SciTech Connect

    Not Available

    1991-01-01

    Malaysia's South Johore region has undergone rapid development recently, seriously damaging its ecologically sensitive and important coastal resources. The report profiles the area's coastal environment and identies major environmental problems, as well as chief obstacles to sustainable development. Chapter 2 describes South Johore's physical environment, physiography, climate, and geology. Chapters 3-7 cover in detail the area's natural resource endowment; coastal ecosystems; population and socioeconomics; land use; and fisheries and aquaculture. Chapter 8 focuses on economic sectors other than aquaculture, including agriculture, forestry, livestock, shipping, industry, and transportation, while Chapter 9 covers tourism and its potential impact on South Johore's ecology. Chapter 10 reviews the major types of environmental degradation in the region, including various types of coastal pollution, forest destruction, and coastal erosion. The laws, regulations, and institutions that govern environmental management are covered in Chapter 11. Chapter 12 concludes the report with an overview of the chief constraints to effective environmental management.

  9. On the Lack of Correlation Between Mg II 2796, 2803 Angstrom and Lyman alpha Emission in Lensed Star-Forming Galaxies

    NASA Technical Reports Server (NTRS)

    Rigby, Jane Rebecca; Bayliss, M. B.; Gladders, M. D.; Sharon, K.; Wuyts, E.; Dahle, H.

    2014-01-01

    We examine the Mg II 2796, 2803 Angstrom, Lyman alpha, and nebular line emission in five bright star-forming galaxies at 1.66 less than z less than 1.91 that have been gravitationally lensed by foreground galaxy clusters. All five galaxies show prominent Mg II emission and absorption in a P Cygni profile. We find no correlation between the equivalent widths of Mg II and Lyman alpha emission. The Mg II emission has a broader range of velocities than do the nebular emission line profiles; the Mg II emission is redshifted with respect to systemic by 100 to 200 km s(exp-1). When present, Lyman alpha is even more redshifted. The reddest components of Mg II and Lyman alpha emission have tails to 500-600 km s(exp-1), implying a strong outflow. The lack of correlation in the Mg II and Lyman alpha equivalent widths, the differing velocity profiles, and the high ratios of Mg II to nebular line fluxes together suggest that the bulk of Mg II emission does not ultimately arise as nebular line emission, but may instead be reprocessed stellar continuum emission.

  10. Evolution of Lyman-α Emitters, Lyman-break Galaxies and Elliptical Galaxies

    NASA Astrophysics Data System (ADS)

    Mori, M.; Umemura, M.

    2008-10-01

    High redshift Lyman-α emitters (LAEs) and Lyman-break galaxies (LBGs) possibly provide a significant key for the embryology of galaxies. LBGs have been argued as candidate progenitors of present-day elliptical galaxies in terms of their observed properties. But, what evolutionary stages LBGs correspond to and how they are related to LAEs are still under debate. Here, we present an ultra-high-resolution hydrodynamic simulation of galaxy formation. We show that, at the earliest stages of less than 3×10^8 years, continual supernova explosions produce multitudinous hot bubbles and cooled HI shells in between. The HI shells radiate intense Lyman-α emission like LAEs. We found that the bubbly structures produced are quite similar to the observed features in the Lyman-α surface brightness distribution of the extended LAEs. After 10^9 years, the galaxy emission is dominated by stellar continuum, exhibiting an LBG-like spectrum. Also, we find that, as a result of purely dynamical evolution over 13 billion years, the properties of this galaxy match those of present-day elliptical galaxies well. It is implied that the major episode of star formation and chemical enrichment in elliptical galaxies is almost completed in the evolutionary path from LAEs to LBGs.

  11. Lyman alpha SMM/UVSP absolute calibration and geocoronal correction

    NASA Technical Reports Server (NTRS)

    Fontenla, Juan M.; Reichmann, Edwin J.

    1987-01-01

    Lyman alpha observations from the Ultraviolet Spectrometer Polarimeter (UVSP) instrument of the Solar Maximum Mission (SMM) spacecraft were analyzed and provide instrumental calibration details. Specific values of the instrument quantum efficiency, Lyman alpha absolute intensity, and correction for geocoronal absorption are presented.

  12. Variations in solar Lyman alpha irradiance on short time scales

    NASA Technical Reports Server (NTRS)

    Pap, J. M.

    1992-01-01

    Variations in solar UV irradiance at Lyman alpha are studied on short time scales (from days to months) after removing the long-term changes over the solar cycle. The SME/Lyman alpha irradiance is estimated from various solar indices using linear regression analysis. In order to study the nonlinear effects, Lyman alpha irradiance is modeled with a 5th-degree polynomial as well. It is shown that the full-disk equivalent width of the He line at 1083 nm, which is used as a proxy for the plages and active network, can best reproduce the changes observed in Lyman alpha. Approximately 72 percent of the solar-activity-related changes in Lyman alpha irradiance arise from plages and the network. The network contribution is estimated by the correlation analysis to be about 19 percent. It is shown that significant variability remains in Lyman alpha irradiance, with periods around 300, 27, and 13.5d, which is not explained by the solar activity indices. It is shown that the nonlinear effects cannot account for a significant part of the unexplained variation in Lyman alpha irradiance. Therefore, additional events (e.g., large-scale motions and/or a systematic difference in the area and intensity of the plages and network observed in the lines of Ca-K, He 1083, and Lyman alpha) may explain the discrepancies found between the observed and estimated irradiance values.

  13. Large scale temporal interplanetary Lyman α intensity variations: model calculations

    NASA Astrophysics Data System (ADS)

    Summanen, T.

    1996-07-01

    In this work we have studied how temporally and latitudinally varying ionization rates of the interplanetary hydrogen change interplanetary hydrogen densities and Lyman α intensities. Our results confirm the earlier results by Ruciński and Bzowski, [1995] and also show that small changes in the ionization rate do not change the temporal behaviour of the Lyman α intensity.

  14. Trend analysis of the 20-year time series of stratospheric ozone profiles observed by the GROMOS microwave radiometer at Bern

    NASA Astrophysics Data System (ADS)

    Moreira, L.; Hocke, K.; Eckert, E.; von Clarmann, T.; Kämpfer, N.

    2015-10-01

    The ozone radiometer GROMOS (GROund-based Millimeter-wave Ozone Spectrometer) has been performing continuous observations of stratospheric ozone profiles since 1994 above Bern, Switzerland (46.95° N, 7.44° E, 577 m). GROMOS is part of the Network for the Detection of Atmospheric Composition Change (NDACC). From November 1994 to October 2011, the ozone line spectra were measured by a filter bench (FB). In July 2009, a fast Fourier transform spectrometer (FFTS) was added as a back end to GROMOS. The new FFTS and the original FB measured in parallel for over 2 years. The ozone profiles retrieved separately from the ozone line spectra of FB and FFTS agree within 5 % at pressure levels from 30 to 0.5 hPa, from October 2009 to August 2011. A careful harmonisation of both time series has been carried out by taking the FFTS as the reference instrument for the FB. This enables us to assess the long-term trend derived from stratospheric ozone observations at Bern. The trend analysis was performed by using a robust multilinear parametric trend model which includes a linear term, the solar variability, the El Niño-Southern Oscillation (ENSO) index, the quasi-biennial oscillation (QBO), the annual and semi-annual oscillation and several harmonics with period lengths between 3 and 24 months. Over the last years, some experimental and modelling trend studies have shown that the stratospheric ozone trend is levelling off or even turning positive. With our observed ozone profiles, we are able to support this statement by reporting a statistically significant trend of +3.14 % decade-1 at 4.36 hPa (37.76 km), covering the period from January 1997 to January 2015, above Bern. Additionally, we have estimated a negative trend over this period of -3.94 % decade-1 at 0.2 hPa (59 km).

  15. Trend analysis of the 20 years time series of stratospheric ozone profiles observed by the GROMOS microwave radiometer at Bern

    NASA Astrophysics Data System (ADS)

    Moreira, L.; Hocke, K.; Eckert, E.; von Clarmann, T.; Kämpfer, N.

    2015-06-01

    The ozone radiometer GROMOS (GROund-based Millimeterwave Ozone Spectrometer) performs continuous observations of stratospheric ozone profiles since 1994 above Bern, Switzerland. GROMOS is part of the Network for the Detection of Atmospheric Composition Change (NDACC). From November 1994 to October 2011, the ozone line spectra were measured by a filter bench (FB). In July 2009, a Fast-Fourier-Transform spectrometer (FFTS) has been added as backend to GROMOS. The new FFTS and the original FB measured in parallel for over two years. The ozone profiles retrieved separately from the ozone line spectra of FB and FFTS agree within 5 % at pressure levels from 30 to 0.5 hPa, from October 2009 to August 2011. A careful harmonisation of both time series has been carried out by taking the FFTS as the reference instrument for the FB. This enables us to assess the long-term trend derived from more than 20 years of stratospheric ozone observations at Bern. The trend analysis has been performed by using a robust multilinear parametric trend model which includes a linear term, the solar variability, the El Niño-Southern Oscillation (ENSO) index, the quasi-biennial oscillation (QBO), the annual and semi-annual oscillation and several harmonics with period lengths between 3 and 24 months. Over the last years, some experimental and modelling trend studies have shown that the stratospheric ozone trend is levelling off or even turning positive. With our observed ozone profiles, we are able to support this statement by reporting a statistically significant trend of +3.14 % decade-1 at 4.36 hPa, covering the period from January 1997 to January 2015, above Bern. Additionally, we have estimated a negative trend over this period of -3.94 % decade-1 at 0.2 hPa.

  16. Finding high-redshift voids using Lyman α forest tomography

    NASA Astrophysics Data System (ADS)

    Stark, Casey W.; Font-Ribera, Andreu; White, Martin; Lee, Khee-Gan

    2015-11-01

    We present a new method of finding cosmic voids using tomographic maps of Lyα forest flux. We identify cosmological voids with radii of 2-12 h-1 Mpc in a large N-body simulation at z = 2.5, and characterize the signal of the high-redshift voids in density and Lyα forest flux. The void properties are similar to what has been found at lower redshifts, but they are smaller and have steeper radial density profiles. Similarly to what has been found for low-redshift voids, the radial velocity profiles have little scatter and agree very well with the linear theory prediction. We run the same void finder on an ideal Lyα flux field and tomographic reconstructions at various spatial samplings. We compare the tomographic map void catalogues to the density void catalogue and find good agreement even with modest-sized voids (r > 6 h-1 Mpc). Using our simple void-finding method, the configuration of the ongoing COSMOS Lyman Alpha Mapping And Tomography Observations (CLAMATO) survey covering 1 deg2 would provide a sample of about 100 high-redshift voids. We also provide void-finding forecasts for larger area surveys, and discuss how these void samples can be used to test modified gravity models, study high-redshift void galaxies, and to make an Alcock-Paczynski measurement. To aid future work in this area, we provide public access to our simulation products, catalogues, and sample tomographic flux maps.

  17. LAMP: The Lyman Alpha Mapping Project on NASA's Lunar Reconnaissance Orbiter Mission

    NASA Astrophysics Data System (ADS)

    Gladstone, G. Randall; Stern, S. Alan; Retherford, Kurt D.; Black, Ronald K.; Slater, David C.; Davis, Michael W.; Versteeg, Maarten H.; Persson, Kristian B.; Parker, Joel W.; Kaufmann, David E.; Egan, Anthony F.; Greathouse, Thomas K.; Feldman, Paul D.; Hurley, Dana; Pryor, Wayne R.; Hendrix, Amanda R.

    2010-01-01

    The Lyman Alpha Mapping Project (LAMP) is a far-ultraviolet (FUV) imaging spectrograph on NASA’s Lunar Reconnaissance Orbiter (LRO) mission. Its main objectives are to (i) identify and localize exposed water frost in permanently shadowed regions (PSRs), (ii) characterize landforms and albedos in PSRs, (iii) demonstrate the feasibility of using natural starlight and sky-glow illumination for future lunar surface mission applications, and (iv) characterize the lunar atmosphere and its variability. As a byproduct, LAMP will map a large fraction of the Moon at FUV wavelengths, allowing new studies of the microphysical and reflectance properties of the regolith. The LAMP FUV spectrograph will accomplish these objectives by measuring the signal reflected from the night-side lunar surface and in PSRs using both the interplanetary HI Lyman- α sky-glow and FUV starlight as light sources. Both these light sources provide fairly uniform, but faint, illumination. With the expected LAMP sensitivity, by the end of the primary 1-year LRO mission, the SNR for a Lyman- α albedo map should be >100 in polar regions >1 km2, providing useful FUV constraints to help characterize subtle compositional and structural features. The LAMP instrument is based on the flight-proven Alice series of spectrographs flying on the Rosetta comet mission and the New Horizons Pluto mission. A general description of the LAMP instrument and its initial ground calibration results are presented here.

  18. A Possible Solution to the Lyman/Balmer Line Problem in Hot DA White Dwarfs

    NASA Astrophysics Data System (ADS)

    Preval, Simon P.; Barstow, Martin A.; Badnell, Nigel R.; Holberg, Jay B.; Hubeny, Ivan

    2015-06-01

    Arguably, the best method for determining the effective temperature (Teff) and surface gravity (log g) of a DA white dwarf is by fitting the Hydrogen Lyman and Balmer absorption features. However, as has been shown for white dwarfs with Teff>50,000K, the calculated value from the Lyman and Balmer lines are discrepant, which worsens with increasing temperature. Many different solutions have been suggested, ranging from the input physics used to calculate the models, to interstellar reddening. We will focus on the former, and consider three variables. The first is the atomic data used, namely the number of transitions included in line blanketing treatments and the photoionization cross sections. The second is the stark broadening treatment used to synthesise the Lyman and Balmer line profiles, namely the calculations performed by Lemke (1997) and Tremblay & Bergeron (2009). Finally, the third is the atmospheric content. The model grids are calculated with a pure H composition, and a metal polluted composition using the abundances of Preval et al. (2013). We present the preliminary results of our analysis, whereby we have determined the Teff for a small selection of white dwarfs. We plan to extend our analysis by allowing metallicity to vary in future model grids.

  19. Hydrogen density in the dayside venusian exosphere derived from Lyman-α observations by SPICAV on Venus Express

    NASA Astrophysics Data System (ADS)

    Chaufray, J.-Y.; Bertaux, J.-L.; Quémerais, E.; Villard, E.; Leblanc, F.

    2012-02-01

    A series of observations of the venusian hydrogen corona made by SPICAV on Venus Express are analyzed to estimate the amount of hydrogen in the exosphere of Venus. These observations were made between November 2006 and July 2007 at altitudes from 1000 km to 8000 km on the dayside. The Lyman-α brightness profiles derived are reproduced by the sum of a cold hydrogen population dominant below ˜2000 km and a hot hydrogen population dominant above ˜4000 km. The temperature (˜300 K) and hydrogen density at 250 km (˜10 5 cm -3) derived for the cold populations, near noon, are in good agreement with previous observations. Strong dawn-dusk exospheric asymmetry is observed from this set of observations, with a larger exobase density on the dawn side than on the dusk side, consistent with asymmetry previously observed in the venusian thermosphere, but with a lower dawn/dusk contrast. The hot hydrogen density derived is very sensitive to the sky background estimate, but is well constrained near 5000 km. The density of the hot population is reproduced by the exospheric model from Hodges (Hodges, R.R. [1999]. J. Geophys. Res. 104, 8463-8471) in which the hot population is produced by neutral-ions interactions in the thermosphere of Venus.

  20. Data-model comparison search analysis of coincident PBO Balmer α, EURD Lyman β geocoronal measurements from March 2000

    NASA Astrophysics Data System (ADS)

    Bishop, J.; Mierkiewicz, E. J.; Roesler, F. L.; Gómez, J. F.; Morales, C.

    2004-05-01

    Recent Lyman series and Balmer series airglow measurements provide a fresh opportunity to investigate the density distribution and variability of atomic hydrogen in the upper atmosphere. Dedicated nightside Balmer α Fabry-Perot spectrometer measurements at the Pine Bluff Observatory (PBO), University of Wisconsin-Madison, have been acquired since late 1999 taking advantage of several technological advances. Extreme ultraviolet spectral radiance measurements by the Espectrógrafo Ultravioleta extremo para la Radiación Difusa (EURD) instrument on the Spanish MINISAT-1 satellite from October 1997 to December 2001 provide extensive sets of geocoronal Lyman β, Lyman γ and He 584 Å emission intensities. In this paper, coincident EURD Lyman β and PBO Balmer α radiance measurements from the early March 2000 new moon period are presented. In addition to serving as examples of the data sets now available, the data volume poses an analysis challenge not faced in prior geocoronal studies. A data-model comparison search procedure employing resonance radiation transport results for extensive sets of parametric density distribution models is being developed for use in analyses of multiple large data sets; this is described, and example results for the PBO and EURD March 2000 data sets are presented. The tightness of the constraints obtained for the solar line-center Lyman β irradiance and the atomic hydrogen column abundance is somewhat surprising, given the crudeness of the parameter binning in the search procedure and the fact that a small number of recognized corrections remain to be made to each data set.

  1. Study of an Extended EUV Filament Using SoHO/SUMER Observations of the Hydrogen Lyman Lines. II. Lyman α Line Observed During a Multi-wavelength Campaign

    NASA Astrophysics Data System (ADS)

    Schwartz, P.; Schmieder, B.; Heinzel, P.; Kotrč, P.

    2012-12-01

    A filament and its channel close to the solar disk were observed in the complete hydrogen Lyman spectrum, and in several EUV lines by the SUMER (Solar Ultraviolet Measurement of Emitted Radiation) and CDS (Coronal Diagnostic Spectrometer) spectrographs on the SoHO satellite, and in Hα by ground-based telescopes during a multi-instrument campaign in May 2005. It was a good opportunity to get an overview of the volume and the density of the cold plasma in the filament channel; these are essential parameters for coronal mass ejections. We found that the width of the filament depends on the wavelength in which the filament is observed (around 15 arcsec in Hα, 30 arcsec in Lα, and 60 arcsec in EUV). In Lα the filament is wider than in Hα because cool plasma, not visible in Hα, is optically thick at the Lα line center, and its presence blocks the coronal emission. We have derived physical plasma properties of this filament fitting the Lyman spectra and Hα profiles by using a 1D isobaric NLTE model. The vertical temperature profile of the filament slab is flat ( T≈7000 K) with an increase to ≈ 20 000 K at the top and the bottom of the slab. From an analysis of the Lα and Hα source functions we have concluded that these lines are formed over the whole filament slab. We have estimated the geometrical filling factor in the filament channel. Its low value indicates the presence of multi-threads.

  2. Origin of the Lyman excess in early-type stars

    NASA Astrophysics Data System (ADS)

    Cesaroni, R.; Sánchez-Monge, Á.; Beltrán, M. T.; Molinari, S.; Olmi, L.; Treviño-Morales, S. P.

    2016-04-01

    Context. Ionized regions around early-type stars are believed to be well-known objects, but until recently, our knowledge of the relation between the free-free radio emission and the IR emission has been observationally hindered by the limited angular resolution in the far-IR. The advent of Herschel has now made it possible to obtain a more precise comparison between the two regimes, and it has been found that about a third of the young H ii regions emit more Lyman continuum photons than expected, thus presenting a Lyman excess. Aims: With the present study we wish to distinguish between two scenarios that have been proposed to explain the existence of the Lyman excess: (i) underestimation of the bolometric luminosity, or (ii) additional emission of Lyman-continuum photons from an accretion shock. Methods: We observed an outflow (SiO) and an infall (HCO+) tracer toward a complete sample of 200 H ii regions, 67 of which present the Lyman excess. Our goal was to search for any systematic difference between sources with Lyman excess and those without. Results: While the outflow tracer does not reveal any significant difference between the two subsamples of H ii regions, the infall tracer indicates that the Lyman-excess sources are more associated with infall signposts than the other objects. Conclusions: Our findings indicate that the most plausible explanation for the Lyman excess is that in addition to the Lyman continuum emission from the early-type star, UV photons are emitted from accretion shocks in the stellar neighborhood. This result suggests that high-mass stars and/or stellar clusters containing young massive stars may continue to accrete for a long time, even after the development of a compact H ii region. Based on observations carried out with the IRAM 30 m Telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain).

  3. Nearby Galaxies as Damped Lyman alpha Absorbers

    NASA Astrophysics Data System (ADS)

    Rao, Sandhya

    1993-12-01

    The evolution of the neutral hydrogen content of galaxies as a function of time is an important constraint on processes in galactic evolution. We present a comprehensive, statistical description of the HI content and distribution within galaxies at the present epoch and compare these statistics with the properties of HI associated with ``damped Lyman alpha '' absorption systems at high redshift that are observed in the spectra of QSOs. Omega_ {HI}(z=0), the HI mass density at the present epoch relative to the present critical mass density, is found to be (2.3 +/- 0.6) times 10(-4) h75(-1) , consistent with the decreasing trend of the HI content with time deduced from QSO absorption line statistics for redshifts from about 4 to 0.5 (Lanzetta 1993). Spiral galaxies contain an overwhelming 94% of this neutral hydrogen mass. The rest is contained in irregulars (3%), and S0s plus ellipticals (3%). Spirals also offer the largest cross-section to line-of-sight absorption of light from QSOs. By considering nearby spirals as potential absorbers, the interception probability as a function of the HI column density, N(HI), is derived for comparison with the cross-sections inferred from observations of damped Lyman alpha systems. Consistent with previous studies, the comparison shows that the damped Ly alpha lines are created by absorbers that subtend larger cross-sections than present-day spirals by a factor of 5 implying that galaxies were either larger or more numerous at z ~ 2.5. We are also investigating the statistics of damped Lyman alpha absorbers in the redshift range 0.2 1.5.

  4. Fiscal Profiles, 2006: "The Fourteenth in a Periodic Series of Factsheets about the Financing of California Higher Education." California Postsecondary Education Commission Report 06-13

    ERIC Educational Resources Information Center

    California Postsecondary Education Commission, 2006

    2006-01-01

    Fiscal Profiles, 2006 is the fourteenth in a series of periodic reports by the California Postsecondary Education Commission of statistical information on the financing of the State's public higher education institutions. It also includes selected financial and enrollment information on public elementary and secondary education and on California's…

  5. H I Lyman-alpha Equivalent Widths of Stellar Populations

    NASA Astrophysics Data System (ADS)

    Peña-Guerrero, María A.; Leitherer, Claus

    2013-12-01

    We have compiled a library of stellar Lyman-alpha (Lyα) equivalent widths in O and B stars using the model atmosphere codes CMFGEN and TLUSTY, respectively. The equivalent widths range from about 0 to 30 Å in absorption for early-O to mid-B stars. The purpose of this library is for the prediction of the underlying stellar Lyα absorption in stellar populations of star-forming galaxies with nebular Lyα emission. We implemented the grid of individual equivalent widths into the Starburst99 population synthesis code to generate synthetic Lyα equivalent widths for representative star formation histories. A starburst observed after 10 Myr will produce a stellar Lyα line with an equivalent width of ~ - 10 ± 4 Å in absorption for a Salpeter initial mass function. The lower value (deeper absorption) results from an instantaneous burst, and the higher value (shallower line) from continuous star formation. Depending on the escape fraction of nebular Lyα photons, the effect of stellar Lyα on the total profile ranges from negligible to dominant. If the nebular escape fraction is 10%, the stellar absorption and nebular emission equivalent widths become comparable for continuous star formation at ages of 10-20 Myr.

  6. Lyman Spitzer: Astronomer, Physicist, Engineer, and Mountaineer

    NASA Astrophysics Data System (ADS)

    Morton, D. C.

    2006-12-01

    NASA's naming of the Spitzer Space Telescope after Lyman Spitzer was a most appropriate choice, recognizing an outstanding scientist who also contributed extensively to space astronomy. As an astronomer he was a leading authority in the physics of both the interstellar medium and stellar dynamics, wrote textbooks for both fields, and guided many research students. As a physicist he conceived the Stellarator for magnetic confinement, managed a laboratory for controlled fusion, and wrote a textbook on plasma physics. As an engineer he led the development of the payload for the successful Copernicus satellite, which fulfilled his 1946 proposal for an extraterrestrial observatory. His mountaineering included first ascents on Baffin Island and in the Canadian Rockies as well as the summit of the challenging Mt Waddington in the Coast Range.

  7. EUVL mask inspection at Hydrogen Lyman Alpha

    NASA Astrophysics Data System (ADS)

    Jota, Thiago S.; Milster, Tom D.

    2012-11-01

    Mask inspection is an outstanding challenge for Extreme Ultra-Violet Lithography (EUVL). The purpose of this investigation is to compare imaging characteristics of ArF and KrF inspection sources to imaging characteristics using a source at the Lyman-alpha line of Hydrogen at 121.6nm (HLA). HLA provides a raw resolution improvement of 37% to ArF and 51% to KrF, based on proportional wavelength scaling. The HLA wavelength is in an atmospheric transmission window, so a vacuum environment is not required. Our comparison uses rigorous vector imaging techniques to simulate partially coherent illumination schemes and reasonably accurate mask material properties and dimensions. Contrast is evaluated for representative spatial frequencies. Imaging and detection of defects are also considered with NILS and MEEF. The goal is high throughput inspection with maximum resolution, contrast, and sensitivity.

  8. Search for partial systemic Lyman edges in nearby quasars

    NASA Technical Reports Server (NTRS)

    Koratkar, A. P.; Kinney, A. L.; Bohlin, R. C.

    1992-01-01

    IUE archival spectra of nearby quasars with redshifts in the range 0.4-2.3 were searched for changes in the continuum at the systemic Lyman edge positions. Thirty-nine percent of the sample do not show any discontinuities. Twenty-nine percent of the sample show complete Lyman edges at redshifts less than the quasar redshift. These objects have associated narrow absorption lines; hence the intervening gas responsible for the absorption is extrinsic to the quasar and its environment. Twenty-two percent of the sample show Lyman edges at the quasar redshift with associated narrow absorption lines. In these objects the gas is associated with the AGN or its host galaxy. Ten percent of the sample have Lyman edges with no known associated absorption lines. If Lyman edge discontinuities are due to optically thick, geometrically thin accretion disks, which are randomly oriented to the line of sight, these results indicate that the Lyman edge discontinuity, either in emission or absorption, has to be not more than 15 percent in most quasars.

  9. A model for the disc Lyman alpha emission of Uranus

    SciTech Connect

    Jaffel, L.B.; Vidal-Madjar, A. ); Prange, R.; Emerich, C. ); McConnell, J.C. )

    1991-06-01

    A new efficient radiative transfer algorithm for inhomogeneous atmospheres has been used to simulate the limb to limb Lyman {alpha} reflectivities observed with the Voyager ultraviolet spectrometer during the flyby of Uranus. It was shown that complete frequency redistribution should be adequate to describe the disc emissions. The model atmosphere used was derived using a combination of Voyager measurements and modeling. Atomic H densities calculated had sources derivable directly from solar FUV and EUV fluxes. To fit the observations, four contributions are evaluated: (1) the resonance scattering of solar Lyman {alpha} radiation, (2) Rayleigh-Raman scattering of solar Lyman {alpha} radiation, (3) the resonance scattering of interplanetary Lyman {alpha} radiation, and (4) a possible internal source of unknown origin. From comparison with the observations, and provided that the published Voyager calibrations are correct, it is shown that only atmospheres with low eddy diffusion coefficients (K{sub H}{le}100 cm{sup 2} s{sup {minus}1}) and an internal source could simulate both the shape and the strength of the measured disc emission. The main results are then that the direct solar Lyman {alpha} scattering contribution (type 1 plus type 2) is of the order of 760 R, the scattering of interplanetary Lyman {alpha} contributes about 320 R, and a small additional internal source providing about 100-500 R is needed to match the measurements. Further, the analysis of the disc intensities suggests that there is no strong variation of K with latitude.

  10. Molecular profiles of screen detected vs. symptomatic breast cancer and their impact on survival: results from a clinical series

    PubMed Central

    2013-01-01

    Background Stage shift is widely considered a major determinant of the survival benefit conferred by breast cancer screening. However, factors and mechanisms underlying such a prognostic advantage need further clarification. We sought to compare the molecular characteristics of screen detected vs. symptomatic breast cancers and assess whether differences in tumour biology might translate into survival benefit. Methods In a clinical series of 448 women with operable breast cancer, the Kaplan-Meier method and the log-rank test were used to estimate the likelihood of cancer recurrence and death. The Cox proportional hazard model was used for the multivariate analyses including mode of detection, age at diagnosis, tumour size, and lymph node status. These same models were applied to subgroups defined by molecular subtypes. Results Screen detected breast cancers tended to show more favourable clinicopathological features and survival outcomes compared to symptomatic cancers. The luminal A subtype was more common in women with mammography detected tumours than in symptomatic patients (68.5 vs. 59.0%, p=0.04). Data analysis across categories of molecular subtypes revealed significantly longer disease free and overall survival for screen detected cancers with a luminal A subtype only (p=0.01 and 0.02, respectively). For women with a luminal A subtype, the independent prognostic role of mode of detection on recurrence was confirmed in Cox proportional hazard models (p=0.03). An independent role of modality of detection on survival was also suggested (p=0.05). Conclusions Molecular subtypes did not substantially explain the differences in survival outcomes between screened and symptomatic patients. However, our results suggest that molecular profiles might play a role in interpreting such differences at least partially. Further studies are warranted to reinterpret the efficacy of screening programmes in the light of tumour biology. PMID:23305429

  11. Profiles.

    ERIC Educational Resources Information Center

    School Arts, 1979

    1979-01-01

    Profiles seven Black, Native American, and Chicano artists and art teachers: Hale A. Woodruff, Allan Houser, Luis Jimenez, Betrand D. Phillips, James E. Pate, I, and Fernando Navarro. This article is part of a theme issue on multicultural art. (SJL)

  12. Lyman continuum galaxies: Observed Lyman continuum flux measurements at z ~ 3-4 and mechanisms behind the escape

    NASA Astrophysics Data System (ADS)

    Cooke, Jeff; Ryan-Weber, Emma; Garel, Thibault; Gonzalo Diaz, C.

    2016-06-01

    Measuring the surviving Lyman continuum (LyC) flux and inferred ionizing photon escape fraction (f_esc) of Lyman break galaxies has proved challenging, in part due to the historical selection criteria based on a Lyman continuum break. A few galaxies, largely serendipitous, have been detected with measurable LyC flux but have colors inconsistent with Lyman break galaxy expectations for their specific redshifts. I will discuss our physically motivated technique that provides an accurate measure of the average f_esc for the z ~ 3 Lyman break galaxy population that has also identified a population of galaxies, termed Lyman continuum galaxies (LCGs) with high expected levels of surviving LyC flux. I will present the results of our program that uses 30-band photometry, HST imaging, and deep medium-band IR imaging from the ZFOURGE survey to select z ~ 3-4 LCGs. We obtained very deep Keck spectroscopy that has confirmed the LCG population and has directly measured the predicted level of LyC flux. In addition, our program has obtained deep Keck infrared spectroscopy to calibrate restframe optical nebular emission-line models used to predict the LyC escape fraction, with the aim to measure the f_esc of galaxies at the Epoch of Reionization where direct LyC flux detection is not possible.

  13. Variability of the Lyman alpha flux with solar activity

    SciTech Connect

    Lean, J.L.; Skumanich, A.

    1983-07-01

    A three-component model of the solar chromosphere, developed from ground based observations of the Ca II K chromospheric emission, is used to calculate the variability of the Lyman alpha flux between 1969 and 1980. The Lyman alpha flux at solar minimum is required in the model and is taken as 2.32 x 10/sup 11/ photons/cm/sup 2//s. This value occurred during 1975 as well as in 1976 near the commencement of solar cycle 21. The model predicts that the Lyman alpha flux increases to as much as 5 x 10/sup 11/ photons/cm/sup 2//s at the maximum of the solar cycle. The ratio of the average fluxes for December 1979 (cycle maximum) and July 1976 (cycle minimum) is 1.9. During solar maximum the 27-day solar rotation is shown to cause the Lyman alpha flux to vary by as much as 40% or as little as 5%. The model also shows that the Lyman alpha flux varies over intermediate time periods of 2 to 3 years, as well as over the 11-year sunspot cycle. We conclude that, unlike the sunspot number and the 10.7-cm radio flux, the Lyman alpha flux had a variability that was approximately the same during each of the past three cycles. Lyman alpha fluxes calculated by the model are consistent with measurements of the Lyman alpha flux made by 11 of a total of 14 rocket experiments conducted during the period 1969--1980. The model explains satisfactorily the absolute magnitude, long-term trends, and the cycle variability seen in the Lyman alpha irradiances by the OSO 5 satellite experiment. The 27-day variability observed by the AE-E satellite experiment is well reproduced. However, the magntidue of the AE-E 1 Lyman alpha irradiances are higher than the model calculations by between 40% and 80%. We suggest that the assumed calibration of the AE-E irradiances is in error.

  14. Bio-optical profile data report: Joint Global Ocean Flux Study, Hawaii Ocean Time-Series, HOT-3, R/V Moana Wave, 6-10 January 1989

    NASA Technical Reports Server (NTRS)

    Collins, Donald J.; Rhea, W. Joseph; Tran, An Van

    1990-01-01

    Time-series measurements of the incident surface downwelling irradiance and vertical profiles of the Bio-optical properties of the ocean have been measured during the third cruise of the Hawaii Ocean Time-Series to the ALOHA site, 22 degrees 56.4 minutes N, 157 degrees 54.6 minutes W, north of the island of Oahu, Hawaii, during the period January 6 to 10, 1989. A summary of these data is presented to permit investigators an overview of the data collected. The data are available in digital form for scientific investigators.

  15. Magnetic Turbulence and Line Broadening in Simulations of Lyman-Alpha Absorption

    NASA Astrophysics Data System (ADS)

    Gurvich, Alex; Burkhart, Blakesley K.; Bird, Simeon

    2016-01-01

    We use the Illustris cosmological AREPO simulations to study the effects of gas turbulence and magnetic fields on measurements from the Lyman-Alpha forest. We generate simulated Lyman-Alpha spectra and plot the distributions of Column Density (CDD) and Doppler Width (b) both by adhering to the canonical method of fitting Voigt profiles to absorption lines and by directly measuring the column density and equivalent widths from snapshot data .We investigate the effects of additional unresolved gas turbulence in Illustris by adding an additional broadening term to the line profiles to mimic turbulent broadening. When we do this, we find a measurable effect in the CDD and an offset in the mean of the b distribution corresponding to the additional turbulence. We also compare different MHD runs in AREPO we find that the CDD can measurably differentiate between magnetic seed field at redshifts as low as z=0.1, but we do not find that the b distribution is affected at a detectable level. Our work suggests that the effects of turbulence and magnetic fields from z=2-0.1 can potentially be measured with these diagnostics. This work was supported in part by the NSF REU and DoD ASSURE programs under NSF grant no. 1262851 and by the Smithsonian Institution.

  16. Resolution of the discrepancy between Balmer alpha emission rates, the solar Lyman beta flux, and models of geocoronal hydrogen concentration

    NASA Technical Reports Server (NTRS)

    Levasseur, A.-C.; Meier, R. R.; Tinsley, B. A.

    1976-01-01

    New satellite Balmer alpha measurements and solar Lyman beta flux and line profile measurements, together with new measurements of the zodiacal light intensity used in correcting both ground and satellite Balmer alpha measurements for the effects of the Fraunhofer line in the zodiacal light, have been used in a reevaluation of the long-standing discrepancy between ground-based Balmer alpha emission rates and other geocoronal hydrogen parameters. The solar Lyman beta line center flux is found to be (4.1 plus or minus 1.3) billion photons per sq cm per sec per angstrom at S(10.7) equals 110 and, together with a current hydrogen model which has 92,000 atoms per cu cm at 650 km for T(inf) equals 950 K, gives good agreement between calculated Balmer alpha emission rates and the ground-based and satellite measurements.

  17. Obituary: Lyman Francis Kells, 1917-2004

    NASA Astrophysics Data System (ADS)

    Hockey, Thomas

    2007-12-01

    Lyman Francis Kells was born in Seattle, Washington, on 19 May 1917. He earned a 1938 BS in Chemistry from the University of Washington. He received a PhD. in 1944, also from the University of Washington. Kells held research positions at the Carbide and Carbon Chemicals Corporation of New York, New York, from 1944 through 1946; the Standard Oil Development Company of New Jersey, from 1946 through 1948; and Allied Chemical Corporation of Morristown, New Jersey, from 1951 through 1961. His wartime work involved the separation of Uranium isotopes by gaseous diffusion, based on a method developed in part by Harold Urey. Kells was on the faculty of Hunter College 1948-1949, an Assistant Professor at Iona College 1949-1951, a Special Lecturer at Newark College of Engineering in 1961, an Assistant Professor of Chemistry at East Tennessee State University 1962-1964, and a Professor of Chemistry at Westmar College 1964-1974. He died on 4 November 2004 in Seattle, Washington. Kells was a member of the American Association for the Advancement of Science, the American Chemical Society, the Astronomical Society of the Pacific, and the New York Academy of Science, as well as this Society. He was a Unitarian. Kells is survived by his daughters Leila Stefani Newcomb and Christina V. Cohen.

  18. Dynamic Stark broadening of Lyman

    NASA Astrophysics Data System (ADS)

    Stambulchik, Evgeny; Demura, Alexander V.

    2016-02-01

    Calculating lineshapes of atomic radiative transitions broadened by plasma is a complex problem lacking a general analytic solution, and several models have been suggested to treat it. Lyman-α is the simplest transition; paradoxically however, calculating the broadening of this spectral line in plasma results in a significant spread between different models. Here, we argue that the quasistatic broadening regime is never realized for the line core in a one-component plasma; instead, the broadening due to either electrons or ions alone evolves from the impact regime to another regime, also dynamical in nature. In the latter (referred to here as ‘rotational’ broadening), the linewidth only depends on the typical frequency of the plasma microfields and is independent of both the microfield magnitudes and the atomic properties of the transition. We also demonstrate that rotational broadening is asymptotically reached in the high-density/low-temperature limit by other transitions with an unshifted central component, such as the Balmer-α line. A simple expression is suggested interpolating between the two asymptotic regimes, applicable to broadening due to electrons and ions alike. The treatment is further extended to realistic two-component plasmas. Comparison to results of accurate computer simulations shows a good agreement over a very large range of plasma parameters, both for the case of one- and two-component plasmas.

  19. Solar wind observations by Lyman alpha

    NASA Technical Reports Server (NTRS)

    Kyroelae, E.; Summanen, T.

    1995-01-01

    The interaction between the solar wind and the local interstellar matter takes place at two distinct regions. The plasma component of the interstellar matter meets the solar wind at the heliospheric interface region and it is excluded from entering into the heliosphere. The neutral component consisting mainly of the hydrogen atoms flows through the whole heliosphere. It gets, however, partly ionized by charge exchange collisions with solar wind protons and energetic photons from the Sun. The neutral atom trajectories are also affected by the radiation pressure from the Sun. While the properties of the interface region are still too sparsely known to be useful for solar wind studies the neutral H distribution near the Sun has been used successfully for this purpose. Measuring Lyman alpha light scattered by neutral hydrogen atoms can serve as a remote sensing measurement of the solar wind's three-dimensional and temporal distribution. In this work we will particularly focus on the solar cycle effects on the neutral hydrogen distribution and how it affects the solar wind monitoring.

  20. 100 Most Popular Business Leaders for Young Adults: Biographical Sketches and Professional Paths. Profiles and Pathways Series.

    ERIC Educational Resources Information Center

    Logan, Rochelle; Halverstadt, Julie

    This book, which is intended as a reference for teenagers and educators, profiles the lives and professional paths of the 100 most popular business leaders for young adults. Those profiled were selected for a number of reasons, including the following: their names are recognizable; they are associated with businesses and industries that are…

  1. The Characteristic Dimension of Lyman-Alpha Forest Clouds Toward Q0957+561

    NASA Technical Reports Server (NTRS)

    Dolan, J. F.; Michalitsianos, A. G.; Hill, R. J.; Nguyen, Q. T.; Fisher, Richard (Technical Monitor)

    2000-01-01

    Far-ultraviolet spectra of the gravitational lens components Q0957+561 A and B were obtained with the Hubble Space Telescope Faint Object Spectrograph to investigate the characteristic dimension of Lyman-alpha forest clouds in the direction of the quasar. If one makes the usual assumption that the absorbing structures are spherical clouds with a single radius, that radius can be found analytically from the ratio of Lyman-alpha lines in only one line of sight to the number in both. A simple power series approximation to this solution, accurate everywhere to better than 1%, will be presented. Absorption lines in Q0957+561 having equivalent width greater than 0.3 A in the observer's frame not previously identified as interstellar lines, metal lines, or higher order Lyman lines were taken to be Ly-alpha forest lines. The existence of each line in this consistently selected set was then verified by its presence in two archival FOS spectra with approximately 1.5 times higher signal to noise than our spectra. Ly-alpha forest lines appear at 41 distinct wavelengths in the spectra of the two images. One absorption line in the spectrum of image A has no counterpart in the spectrum of image B, and one line in image B has no counterpart in image A. Based on the separation of the lines of sight over the redshift range searched for Ly-alpha forest lines, the density of the absorbing clouds in the direction of Q0957+561 must change significantly over a radius R = 160 (+120, -70) h (sup -1) (sub 50) kpc (H (sub 0) 50 h (sub 50) km s (sup -1) kpc (sup -1), q (sub 0) = 1/2). The 95% confidence interval on R extends from (50 950) h (sup -1) (sub 50) kpc.

  2. Green Peas and diagnostics for Lyman continuum leaking in star-forming dwarf galaxies

    NASA Astrophysics Data System (ADS)

    Thuan, Trinh

    2014-10-01

    One of the key questions in observational cosmology is the identification of the sources responsible for cosmic reionization. The general consensus is that a population of faint low-mass galaxies must be responsible for the bulk of the ionizing photons. However, attempts at identifying individual galaxies showing Lyman continuum (LyC) leakage have so far not been successful, both at high and low redshifts. We propose here to observe directly the LyC of five so-called "Green Pea" (GP) galaxies. GPs share many of the properties of the Lyman Break galaxies at high z (compactness, low mass, low metallicity, high specific star formation rate, gas-rich and clumpy morphology) and may constitute local examples of the long sought-after LyC leaking galaxies. The five GPs have been identified by searching the Sloan Data Release 10 spectral data base of 2 million spectra for non-AGN emission-line objects that meet the following criteria: high [OIII]5007/[OII]3727 ratios, large GALEX FUV fluxes, and redshifted enough (z~0.3) so that the LyC is shifted into the sensitive spectral range of COS. Our unique GP sample will allow us to combine for the first time four fundamental tests for LyC leaking in galaxies and validate their usefulness as LyC leaking indicators : 1) direct measurements of the LyC; 2) high [OIII]/[OII] ratios; 3) characteristics of the Lyman alpha line profile; and 4) residual intensities in the low-ionization ISM absorption UV lines.

  3. The Lyman edge test of the quasar emission mechanism

    NASA Technical Reports Server (NTRS)

    Antonucci, R. R. J.; Kinney, A. L.; Ford, H. C.

    1989-01-01

    The Lyman edge region in the spectra of 11 high-redshift quasars is studied using data designed to detect broadened Lyman edge absorption predicted by thermal models of the 'big blue bump' continuum component, especially thin accretion disks. Three objects have broadened, partial edges near the systemic redshifts, as expected for thermal models. In two cases, however, narrow Lyamn lines with the edge absorption, ruling out the disk interpretation. Thus, the data are negative for thermal models, at least for opaque thin accretion disks.

  4. Stellar lyman alpha emission and the local interstellar medium

    NASA Technical Reports Server (NTRS)

    Simon, Theodore

    1992-01-01

    Under the auspices of this ADP program, a systematic study was made of IUE archival images in order to extract spectra of the Lyman alpha region and to measure the stellar Lyman alpha flux for as many late-type stars as possible. The Lyman alpha resonance line is a powerful cooling channel for the hot chromospheres of solar-type stars, but has not been studied before in any systematic fashion across the H-R diagram. A major deterrent which has limited the use of Lyman alpha in the study of stellar chromospheres is the contamination of this spectral feature caused by the scattering of solar Lyman alpha photons in the Earth's exosphere. This scattered light is monochromatically imaged through the entrance slot of the IUE telescope and is superposed onto the stellar spectrum. In all but the shortest exposures with IUE, this 'geocoronal emission' overwhelms the stellar flux and makes it impossible to directly measure the strength of the stellar chromospheric feature. The IUESIPS processing contains no provision for correcting standard G.O. output products for this contamination. The first task was to develop a scheme for removing the geocoronal flux, specifically from low-dispersion spectra taken with the Short-Wavelength Camera of IUE. The strategy adopted was to fit a 'sky model' to the spatially-resolved geocoronal emission observed through the large science aperture of the telescope, using the spectral orders on either side of the central ones where the stellar emission is concentrated. The model emission was then subtracted from the observed image, leaving behind the corrected stellar Lyman alpha emission. The details of this fitting procedure are described. Having devised a successful method for removing the unwanted geocoronal emission, the correction procedure was applied to 366 archival images which, from inspection of the photowrites in the IUE browse file, seemed especially promising. In this survey, Lyman alpha emission were eventually detected in the

  5. Performance Characterization of the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) CCD Cameras

    NASA Technical Reports Server (NTRS)

    Joiner, Reyann; Kobayashi, Ken; Winebarger, Amy; Champey, Patrick

    2014-01-01

    The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a sounding rocket instrument which is currently being developed by NASA's Marshall Space Flight Center (MSFC) and the National Astronomical Observatory of Japan (NAOJ). The goal of this instrument is to observe and detect the Hanle effect in the scattered Lyman-Alpha UV (121.6nm) light emitted by the Sun's Chromosphere to make measurements of the magnetic field in this region. In order to make accurate measurements of this effect, the performance characteristics of the three on-board charge-coupled devices (CCDs) must meet certain requirements. These characteristics include: quantum efficiency, gain, dark current, noise, and linearity. Each of these must meet predetermined requirements in order to achieve satisfactory performance for the mission. The cameras must be able to operate with a gain of no greater than 2 e(-)/DN, a noise level less than 25e(-), a dark current level which is less than 10e(-)/pixel/s, and a residual nonlinearity of less than 1%. Determining these characteristics involves performing a series of tests with each of the cameras in a high vacuum environment. Here we present the methods and results of each of these performance tests for the CLASP flight cameras.

  6. Performance Characterization of the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) CCD Cameras

    NASA Technical Reports Server (NTRS)

    Joiner, Reyann; Kobayashi, Ken; Winebarger, Amy; Champey, Patrick

    2014-01-01

    The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a sounding rocket instrument currently being developed by NASA's Marshall Space Flight Center (MSFC), the National Astronomical Observatory of Japan (NAOJ), and other partners. The goal of this instrument is to observe and detect the Hanle effect in the scattered Lyman-Alpha UV (121.6nm) light emitted by the Sun's chromosphere. The polarized spectrum imaged by the CCD cameras will capture information about the local magnetic field, allowing for measurements of magnetic strength and structure. In order to make accurate measurements of this effect, the performance characteristics of the three on- board charge-coupled devices (CCDs) must meet certain requirements. These characteristics include: quantum efficiency, gain, dark current, read noise, and linearity. Each of these must meet predetermined requirements in order to achieve satisfactory performance for the mission. The cameras must be able to operate with a gain of 2.0+/- 0.5 e--/DN, a read noise level less than 25e-, a dark current level which is less than 10e-/pixel/s, and a residual non- linearity of less than 1%. Determining these characteristics involves performing a series of tests with each of the cameras in a high vacuum environment. Here we present the methods and results of each of these performance tests for the CLASP flight cameras.

  7. Influence of dense quantum plasmas on fine-structure splitting of Lyman doublets of hydrogenic systems

    SciTech Connect

    De, Madhab Ray, Debasis

    2015-05-15

    Relativistic calculations are performed to study the effects of oscillatory quantum plasma screening on the fine-structure splitting between the components of Lyman-α and β line doublets of atomic hydrogen and hydrgen-like argon ion within dense quantum plasmas, where the effective two-body (electron–nucleus) interaction is modeled by the Shukla–Eliasson oscillatory exponential cosine screened-Coulomb potential. The numerical solutions of the radial Dirac equation for the quantum plasma-embedded atomic systems reveal that the oscillatory quantum screening effect suppresses the doublet (energy) splitting substantially and the suppression becomes more prominent at large quantum wave number k{sub q}. In the absence of the oscillatory cosine screening term, much larger amount of suppression is noticed at larger values of k{sub q}, and the corresponding results represent the screening effect of an exponential screened-Coulomb two-body interaction. The Z{sup 4} scaling of the Lyman doublet splitting in low-Z hydrogen isoelectronic series of ions in free space is violated in dense quantum plasma environments. The relativistic data for the doublet splitting in the zero screening (k{sub q} = 0) case are in very good agreement with the NIST reference data, with slight discrepancies (∼0.2%) arising from the neglect of the quantum electrodynamic effects.

  8. Performance Characterization of the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) CCD Cameras

    NASA Astrophysics Data System (ADS)

    Joiner, R. K.; Kobayashi, K.; Winebarger, A. R.; Champey, P. R.

    2014-12-01

    The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a sounding rocket instrument which is currently being developed by NASA's Marshall Space Flight Center (MSFC) and the National Astronomical Observatory of Japan (NAOJ). The goal of this instrument is to observe and detect the Hanle effect in the scattered Lyman-Alpha UV (121.6nm) light emitted by the Sun's Chromosphere to make measurements of the magnetic field in this region. In order to make accurate measurements of this effect, the performance characteristics of the three on-board charge-coupled devices (CCDs) must meet certain requirements. These characteristics include: quantum efficiency, gain, dark current, noise, and linearity. Each of these must meet predetermined requirements in order to achieve satisfactory performance for the mission. The cameras must be able to operate with a gain of no greater than 2 e­-/DN, a noise level less than 25e-, a dark current level which is less than 10e-/pixel/s, and a residual non-linearity of less than 1%. Determining these characteristics involves performing a series of tests with each of the cameras in a high vacuum environment. Here we present the methods and results of each of these performance tests for the CLASP flight cameras.

  9. H I Lyman-alpha in the sun - The effects of partial redistribution in the line wings

    NASA Technical Reports Server (NTRS)

    Roussel-Dupre, D.

    1983-01-01

    A form for the Lyman-alpha redistribution function that is modified to include the effects of collisional coupling between different energy states is presented. It is noted that this extends the work of Yelnik et al. (1981) and Roussel-Dupre(1982). By separating the source function into its primary components at all heights, the formation of Lyman-alpha radiation is investigated in detail. Frequencies in the line wing can be mapped back in such a way that the heights of formation for a change in lambda of plus or minus 0.5-6 A span the entire solar chromosphere. The usefulness of the Lyman-alpha wing as an atmospheric probe, however, is limited by long thermalization lengths, which result from almost coherent scattering outside of the Doppler core. When the line profiles calculated from the chromospheric models of Vernazza et al. (1981) are compared with the quiet-sun observations of Roussel-Dupre, agreement is found in integrated core intensities and in the line wing shape and normalized center-to-limb behavior. The calculated wing intensities, however, are a factor of four too small.

  10. Comparing Local Starbursts to High-Redshift Galaxies: A Search for Lyman-Break Analogs

    NASA Technical Reports Server (NTRS)

    Petty, Sara M.; de Mello, Duila F.; Gallagher III, John S.; Gardner, Jonathan; Lotz, Jennifer M.; Mountain, C. Matt; Smith, Linda J.

    2008-01-01

    We compare the restframe far-ultraviolet (FUV) morphologies of 8 nearby interacting and starburst galaxies (Arp 269, M 82, Mrk 08, NGC 0520, NGC 1068, NGC 3079, NGC 3310, NGC 7673) with 54 galaxies at z approx.1.5 and 46 galaxies at z approx.4 in the Great Observatories Origins Deep Survey (GOODS) images taken with the Advanced Camera for Surveys onboard the Hubble Space Telescope. We calculate the Gini coefficient (G), the second order moment of 20% of the brightest pixels (M20), and the S ersic index (n). We find that 20% (11/54) of z approx.1.5 and 37% (17/46) of z approx.4 galaxies are bulge-like, using G and M20. We also find approx.70% of the z approx.1.5 and z approx.4 galaxies have exponential disks with n > 0.8. The 2D profile combined with the nonparametric methods provides more detail, concerning the nature of disturbed systems, such as merger and post-merger types. We also provide qualitative descriptions of each galaxy system and at each redshift. We conclude that Mrk 08, NGC 3079, and NGC 7673 have similar morphologies as the starburst FUV restframe galaxies and Lyman-break galaxies at z approx.1.5 and 4, and determine that they are Lyman-break analogs.

  11. Analysis of coronal H I Lyman alpha measurements from a rocket flight on 1979 April 13

    NASA Technical Reports Server (NTRS)

    Withbroe, G. L.; Kohl, J. L.; Weiser, H.; Noci, G.; Munro, R. H.

    1982-01-01

    It is noted that measurements of the profiles of resonantly scattered hydrogen Lyman-alpha coronal radiation have been used in determining hydrogen kinetic temperatures from 1.5 to 4 solar radii from sun center in a quiet region of the corona. Proton temperatures derived using the line widths decrease with height from 2.6 x 10 to the 6th K at 1.5 solar radii to 1.2 x 10 to the 6th K at 4 solar radii. These measurements, together with temperatures for lower heights determined from earlier Skylab and eclipse data, suggest that there is a maximum in the quiet coronal proton temperature at about 1.5 solar radii. Comparison of measured Lyman-alpha intensities with those calculated using a representative model for the radial variation of the coronal electron density yields information on the magnitude of the electron temperature gradient and suggests that the solar wind flow was subsonic for distances less than 4 solar radii.

  12. Mariner 6, 7, and 9 ultraviolet spectrometer experiment - Analysis of hydrogen Lyman alpha data

    NASA Technical Reports Server (NTRS)

    Anderson, D. E., Jr.

    1974-01-01

    Four Lyman alpha airglow measurements of the limb and disk of Mars, made by ultraviolet spectrometers on Mariner 6 and 7 in 1969 and Mariner 9 in 1971, are analyzed to determine the amount and distribution of atomic hydrogen above 80 km. The variation of atomic hydrogen with altitude is calculated by using time-independent chemical diffusion models from 80 to 250 km, and an exospheric model is used above 250 km. By employing radiative transfer theory that includes effects of pure absorption and accounts for temperature variations in the atmosphere, a spherical model of the airglow Lyman alpha emission is used to produce theoretical intensities for comparison with the data. It is found that (1) the exospheric temperature and distribution in 1971 are consistent with those determined in 1969, (2) the vertical optical depth above 80 km was 2.2 in 1969 and 5 in 1971, and (3) the derived atomic hydrogen distribution from 80 to 250 km requires a source of atomic hydrogen above 80 km. Comparison of observed profiles with chemical diffusion models implies a large downward flow of atomic hydrogen at 80 km coupled with a large upward flow of molecular hydrogen.-

  13. THE LYMAN ALPHA REFERENCE SAMPLE: EXTENDED LYMAN ALPHA HALOS PRODUCED AT LOW DUST CONTENT

    SciTech Connect

    Hayes, Matthew; Oestlin, Goeran; Duval, Florent; Guaita, Lucia; Melinder, Jens; Sandberg, Andreas; Schaerer, Daniel; Verhamme, Anne; Orlitova, Ivana; Mas-Hesse, J. Miguel; Oti-Floranes, Hector; Adamo, Angela; Atek, Hakim; Cannon, John M.; Herenz, E. Christian; Kunth, Daniel; Laursen, Peter

    2013-03-10

    We report on new imaging observations of the Lyman alpha emission line (Ly{alpha}), performed with the Hubble Space Telescope, that comprise the backbone of the Lyman alpha Reference Sample. We present images of 14 starburst galaxies at redshifts 0.028 < z < 0.18 in continuum-subtracted Ly{alpha}, H{alpha}, and the far ultraviolet continuum. We show that Ly{alpha} is emitted on scales that systematically exceed those of the massive stellar population and recombination nebulae: as measured by the Petrosian 20% radius, R{sub P20}, Ly{alpha} radii are larger than those of H{alpha} by factors ranging from 1 to 3.6, with an average of 2.4. The average ratio of Ly{alpha}-to-FUV radii is 2.9. This suggests that much of the Ly{alpha} light is pushed to large radii by resonance scattering. Defining the Relative Petrosian Extension of Ly{alpha} compared to H{alpha}, {xi}{sub Ly{alpha}} = R {sup Ly{alpha}}{sub P20}/R {sup H{alpha}}{sub P20}, we find {xi}{sub Ly{alpha}} to be uncorrelated with total Ly{alpha} luminosity. However, {xi}{sub Ly{alpha}} is strongly correlated with quantities that scale with dust content, in the sense that a low dust abundance is a necessary requirement (although not the only one) in order to spread Ly{alpha} photons throughout the interstellar medium and drive a large extended Ly{alpha} halo.

  14. Biography Today: Profiles of People of Interest to Young Readers. World Leaders Series: Modern African Leaders. Volume 2.

    ERIC Educational Resources Information Center

    Harris, Laurie Lanzen, Ed.; Abbey, Cherie D., Ed.

    This book provides biographical profiles of 16 leaders of modern Africa of interest to readers ages 9 and above and was created to appeal to young readers in a format they can enjoy reading and easily understand. Biographies were prepared after extensive research, and this volume contains a name index, a general index, a place of birth index, and…

  15. Occupational Competency Profile for Health Occupations Education Program: Teacher Self-Assessment. Information Series: Report No. 11.

    ERIC Educational Resources Information Center

    Walters, Norma J.

    This assessment instrument is intended to assist teachers in evaluating the relevance of the competencies included in the health occupations education curriculum they are teaching and in assessing their own continuing education needs. The profile lists the competencies required of persons working at the following sites: hospital departments…

  16. Building Local Leadership for Change: A National Scan of Parent Leadership Training Programs. Program Profiles. Education Policy for Action Series

    ERIC Educational Resources Information Center

    Henderson, Anne T.

    2010-01-01

    The program profiles presented in this paper provide background for the research report "Building Local Leadership for Change: A National Scan of Parent Leadership Training Programs." The full report describes four types of parent leadership training programs identified in the scan and gives examples of each. These four types are: (1) Parent…

  17. Biography Today: Profiles of People of Interest to Young Readers. World Leaders Series: Environmental Leaders 2. Volume 3.

    ERIC Educational Resources Information Center

    Hillstrom, Kevin, Ed.; Hillstrom, Laurie, Ed.

    This book provides biographical profiles of 11 environmental leaders of interest to readers ages 9 and above and was created to appeal to young readers in a format they can enjoy reading and readily understand. Biographies were prepared after extensive research, and each volume contains a cumulative index, a general index, a place of birth index,…

  18. Profiles in Online Learning: A Series on Leadership--Tom Layton: Judo and the Art of Technology Innovation.

    ERIC Educational Resources Information Center

    Danielson, Larry

    1998-01-01

    Profiles a high school technology teacher and creator of CyberSchool, a distance learning program of the Eugene (Oregon) School District. Discusses Tom Layton's education, early work experience, establishment of a high school English-as-a-Second-Language (ESL) program, integration of computers into the classroom, reputation as a technology leader,…

  19. A Profile of Southern Agriculture Students. Journal Series No. 1-810032 of the Alabama Agricultural Experiment Station.

    ERIC Educational Resources Information Center

    Dunkelberger, John E.; And Others

    Questionnaires which focused on attributes of undergraduate agriculture students and their reasons for enrolling in agriculture were returned by 3,182 students attending land-grant universities in the South, and a profile of Southern agriculture students evolved. During the 1970's, more women and fewer Blacks enrolled in agricultural curricula.…

  20. Bioinformatics analysis of time-series genes profiling to explore key genes affected by age in fracture healing.

    PubMed

    Wang, Wei; Shen, Hao; Xie, Jingjing; Zhou, Qiang; Chen, Yu; Lu, Hua

    2014-06-01

    The present study was aimed to explore possible key genes and bioprocess affected by age during fracture healing. GSE589, GSE592 and GSE1371 were downloaded from gene expression omnibus database. The time-series genes of three age levels rats were firstly identified with hclust function in R. Then functional and pathway enrichment analysis for selected time-series genes were performed. Finally, the VennDiagram package of R language was used to screen overlapping n time-series genes. The expression changes of time-series genes in the rats of three age levels were classified into two types: one was higher expressed at 0 day, decreased at 3 day to 2 week, and increased from 4 to 6 week; the other was the opposite. Functional and pathways enrichment analysis showed that 12 time-series genes of adult and old rats were significantly involved in ECM-receptor interaction pathway. The expression changes of 11 genes were consistent with time axis, 10 genes were up-regulated at 3 days after fracture, and increased slowly in 6 week, while Itga2b was down-regulated. The functions of 106 overlapping genes were all associated with growth and development of bone after fracture. The key genes in ECM-receptor interaction pathway including Spp1, Ibsp, Tnn and Col3a1 have been reported to be related to fracture in literatures. The difference during fracture healing in three age levels rats is mainly related to age. The Spp1, Ibsp, Tnn and Col3a1 are possible potential age-related genes and ECM-receptor interaction pathway is the potential age-related process during fracture healing. PMID:24627361

  1. Joint Lyman α emitters - quasars reionization constraints

    NASA Astrophysics Data System (ADS)

    Baek, S.; Ferrara, A.; Semelin, B.

    2012-06-01

    We present a novel method to investigate c reionization, using joint spectral information on high-redshift Lyman α emitters (LAEs) and quasi-stellar objects (QSOs). Although LAEs have been proposed as reionization probes, their use is hampered by the fact their Lyα line is damped not only by intergalactic H I but also internally by dust. Our method allows us to overcome such degeneracy. First, we carefully calibrate a reionization simulation with QSO absorption line experiments. Then we identify LAEs (? and equivalent width >20 Å) in two simulation boxes at z= 5.7 and 6.6 and we build synthetic images/spectra of a prototypical LAE. The surface brightness maps show the presence of a scattering halo extending up to 150 kpc from the galaxye. For each LAE we then select a small box of (10 h-1 Mpc)3 around it and derive the optical depth τ along three viewing axes. At redshift 5.7, we find that the Lyα transmissivity ?, almost independent of the halo mass. This constancy arises from the conspiracy of two effects: (i) the intrinsic Lyα line width and (ii) the infall peculiar velocity. At higher redshift, z= 6.6, where ? the transmissivity is instead largely set by the local H I abundance and ? consequently increases with halo mass, Mh, from 0.15 to 0.3. Although outflows are present, they are efficiently pressure confined by infall in a small region around the LAE; hence they only marginally affect transmissivity. Finally, we cast line of sight originating from background QSOs passing through foreground LAEs at different impact parameters, and compute the quasar transmissivity (?). At small impact parameters, d < 1 cMpc, a positive correlation between ? and Mh is found at z= 5.7, which tends to become less pronounced (i.e. flatter) at larger distances. Quantitatively, a roughly 10× increase (from 5 × 10-3 to 6 × 10-2) of ? is observed in the range log Mh= (10.4-11.6). This correlation becomes even stronger at z= 6.6. By cross-correlating ? and ?, we can obtain a

  2. Variability of Lyman-alpha emission from Jupiter

    NASA Technical Reports Server (NTRS)

    Cochran, W. D.; Barker, E. S.

    1979-01-01

    The Jovian Lyman-alpha emission line was reobserved in 1978 March using the high-resolution spectrometer of the Copernicus satellite. An intensity of 8.3 plus or minus 2.9 kilorayleighs was measured. This value represents a significant increase in intensity over previous (1976) Copernicus observations, but is lower than the recent (1979) values obtained by Voyager 1 and IUE. The increase in intensity has been accompanied by a significant increase in line width giving strong support to the theory that the emission results from resonant scattering of the solar Lyman-alpha line by H atoms in the upper Jovian atmossphere. The strength of Jovian Lyman-alpha emission correlates well with the level of solar activity. The solar extreme ultraviolet radiation varies with the solar cycle. This radiation causes the dissociation of H2 and CH4 into H atoms in the Jovian atmosphere. Therefore, in times of high solar activity, the H column density will increase, causing the observed strong Jovian Lyman-alpha emission.

  3. Redistribution of radiation for the wings of Lyman-alpha

    NASA Technical Reports Server (NTRS)

    Yelnik, J.-B.; Burnett, K.; Cooper, J.; Ballagh, R. J.; Voslamber, D.

    1981-01-01

    Earlier work on redistribution of radiation by collisions for isolated lines is extended to overlapping lines, and an explicit expression for the frequency redistribution is given for Lyman-alpha. This expression is valid, even when the emitted photon is in the (non-impact) line wings. A simple physical explanation of the result is possible.

  4. Search for Lyman Limit Absorption Edge in Quasar Continuum

    NASA Astrophysics Data System (ADS)

    Sun, W.-H.; Malkan, M. A.; Chang, Thomas H. W.

    1993-12-01

    We examine the low resolution UV spectra of the 37 quasars in HST Key Project to search for intrinsic Lyman absorption edge which may be a signature of thermal accretion disks. Only 28 QSOs have proper redshifts to place the region of interest in the G160L window. We fit the L_β with two gaussians to remove the line. We then avoid 20 and 50 Angstroms on the blue and red sides of 912 Angstroms in the rest frame, and take 80 Angstroms bins (rest frame) on both sides but further out for analysis. We compare the single power-law fitting (to the entire range across the edge), with the two power-law fitting to blue and red bands. We also measure the percentage drop of flux over the Lyman limit. There are 7 objects with intrinsically noisy spectra, which were presumably caused by intervening Lyman absorption systems. Applying the two methods on the rest 21 objects, we found {24%} candidates to have possible rest frame Lyman limit absorption edges. Same analyses have also been performed on optical spectra of medium- to high-redshift QSOs from Lick Observatory and Hale Observatory. Similar results were also found.

  5. Esthetic Considerations for Reconstructing Implant Emergence Profile Using Titanium and Zirconia Custom Implant Abutments: Fifty Case Series Report.

    PubMed

    Kutkut, Ahmad; Abu-Hammad, Osama; Mitchell, Richard

    2015-10-01

    Titanium and zirconia custom implant abutments are now commonly used for esthetic implant dentistry. Custom implant abutments allow the clinician to improve an implant's emergence profile, to customize cervical margins in accordance with the anatomy of the natural root, and to compensate for poor implant angulation. All of these are essential for optimum esthetic outcomes. Computer-aided design/computer-aided machining (CAD/CAM) technology allows the clinician to design custom implant abutment configurations and create natural-looking superstructures that are in harmony with the adjacent dentition and soft tissue. The CAD/CAM technique provides precise fit, reduces the cost of the procedure, and eliminates dimensional inaccuracies inherent in the conventional waxing and casting technique. The aim of this report is to describe a simplified technique for reconstructing emergence profiles during implant restoration using milled titanium and zirconia custom implant abutments. The results of 50 consecutive cases are reported. PMID:24175922

  6. Solar minimum Lyman. alpha. sky background observations from Pioneer Venus orbiter ultraviolet spectrometer: Solar wind latitude variation

    SciTech Connect

    Ajello, J.M. )

    1990-09-01

    Measurements of interplanetary H I Lyman {alpha} over a large portion of the celestial sphere were made at the recent solar minimum by the Pioneer Venus orbiter ultraviolet spectrometer. These measurements were performed during a series of spacecraft maneuvers conducted to observe Halley's comet in early 1986. Analysis of these data using a model of the passage of interstellar wind hydrogen through the solar wind system shows that the rate of charge exchange with solar wind protons is 30% less over the solar poles than in the ecliptic. This result is in agreement with a similar experiment performed with Mariner 10 at the previous solar minimum.

  7. Solar minimum Lyman alpha sky background observations from Pioneer Venus orbiter ultraviolet spectrometer - Solar wind latitude variation

    NASA Technical Reports Server (NTRS)

    Ajello, J. M.

    1990-01-01

    Measurements of interplanetary H I Lyman alpha over a large portion of the celestial sphere were made at the recent solar minimum by the Pioneer Venus orbiter ultraviolet spectrometer. These measurements were performed during a series of spacecraft maneuvers conducted to observe Halley's comet in early 1986. Analysis of these data using a model of the passage of interstellar wind hydrogen through the solar system shows that the rate of charge exchange with solar wind protons is 30 percent less over the solar poles than in the ecliptic. This result is in agreement with a similar experiment performed with Mariner 10 at the previous solar minimum.

  8. Warm Comptonization in AGN: Effect on the iron Kα line and the Lyman edge

    NASA Astrophysics Data System (ADS)

    Abrassart, A.; Dumont, A. M.

    2001-12-01

    It has been suggested that the broad fluorescent X-ray Iron line profile observed in Seyfert 1 galaxies could be explained by Compton scattering in a hot Thomson thick medium, either by reflection (Abrassart 99) or by transmission (Misra and Kembhavi 1998). Here, using our transfer codes TITAN and NOAR (Dumont et al. 1999), we show that for the latter, the iron line and edge can be made consistent with the observed ones, provided the ionization parameter ξ exceeds 106 erg.cm.s-1, and the incident spectra has a low enough Compton temperature. This model implies a small black hole mass and an accretion rate close to the Eddington value. A very important effect of such a medium on the line of sight of the central UV/X-ray source is to smooth any intrinsic Lyman edge, thus solving a long standing puzzle. .

  9. Spectro-polarimetry of a Lyman-alpha Nebula at z=3.09

    NASA Astrophysics Data System (ADS)

    Beck, Melanie; Scarlata, Claudia; Hayes, Matthew

    2015-01-01

    We present a follow-up study to the imaging polarimetry performed by Hayes, Scarlata & Siana (2011) on one of the largest Lyman-alpha (Lya) nebula currently known, dubbed LAB1. We obtain deep, spatially resolved spectro-polarimetric measurements of LAB1, whose extended Lya emission is likely due to Lya photons produced from a powerful star-forming galaxy and scattered at large radii by the surrounding neutral gas. However, questions still remain on the precise nature of the kinematics in the system. We find spectrally integrated polarization consistent with our prior imaging results. We find wavelength dependent polarization consistent with zero at line center and rising to approximately 12% in the wing of the line profile which supports the idea of a large scale outflow. We discuss how the detected wavelength dependence of the Lya polarization can help in constraining the geometry of the scattering nebula.

  10. Star Formation in Damped Lyman-alpha systems and the Outskirts of Lyman Break Galaxies

    NASA Astrophysics Data System (ADS)

    Rafelski, Marc Alexander

    In this thesis we begin to unify two pictures of the high redshift universe: absorption line systems such as damped Lyman alpha systems (DLAs) that provide the fuel for star formation, and compact star forming regions such as Lyman break galaxies (LBGs) which form the majority of stars. Wolfe & Chen (2006) find that the in situ star formation in DLAs is less than 5% of what is expected from the Kennicutt-Schmidt (KS) relation, but they do not constrain DLAs associated with bright star-forming regions such as LBGs. In this work we search for spatially-extended star formation in the outskirts of LBGs at z ∼3. To this end, we create a sample of z ∼3 LBGs in the Hubble Ultra Deep Field (UDF) by using photometric redshifts enabled by the introduction of an extremely deep u -band image. By stacking these galaxies, we find spatially extended low surface brightness emission around LBGs in the V -band image of the UDF, corresponding to the z ∼3 rest-frame far-ultraviolet light, which is a sensitive measure of star formation rates (SFRs). We connect this emission around LBGs to the expected emission from DLAs, and the results suggest that the SFR efficiency in such gas at z ∼3 is between factors of 10 and 50 lower than predictions based on the KS relation. This decreased efficiency is likely due to the lower metallicity of DLA gas. In addition, we measure the metallicity evolution of DLAs out to z ∼5, and find a continued decrease of metallicity with increasing redshift and a metallicity "floor"' around one thousandth of the solar value. We also compare the metallicity distribution and chemistry of DLAs and halo stars, and find that they are not inconsistent. Lastly, we study the photometric variability of stars in the Galactic center in order to further our understanding of the massive young stars forming in the presence of a super massive black hole. All together, these results improve our understanding of star formation and provide constraints for models and

  11. Long-term series of tropospheric water vapour amounts and HDO/H2O ratio profiles above Jungfraujoch.

    NASA Astrophysics Data System (ADS)

    Lejeune, B.; Mahieu, E.; Schneider, M.; Hase, F.; Servais, C.; Demoulin, P.

    2012-04-01

    Water vapour is a crucial climate variable involved in many processes which widely determine the energy budget of our planet. In particular, water vapour is the dominant greenhouse gas in the Earth's atmosphere and its radiative forcing is maximum in the middle and upper troposphere. Because of the extremely high variability of water vapour concentration in time and space, it is challenging for the available relevant measurement techniques to provide a consistent data set useful for trend analyses and climate studies. Schneider et al. (2006a) showed that ground-based Fourier Transform Infrared (FTIR) spectroscopy, performed from mountain observatories, allows for the detection of H2O variabilities up to the tropopause. Furthermore, the FTIR measurements allow the retrieval of HDO amounts and therefore the monitoring of HDO/H2O ratio profiles whose variations act as markers for the source and history of the atmospheric water vapour. In the framework of the MUSICA European project (Multi-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water, http://www.imk-asf.kit.edu/english/musica.php), a new approach has been developed and optimized by M. Schneider and F. Hase, using the PROFFIT algorithm, to consistently retrieve tropospheric water vapour profiles from high-resolution ground-based infrared solar spectra and so taking benefit from available long-term data sets of ground-based observations. The retrieval of the water isotopologues is performed on a logarithmic scale from 14 micro-windows located in the 2600-3100 cm-1 region. Other important features of this new retrieval strategy are: a speed dependant Voigt line shape model, a joint temperature profile retrieval and an interspecies constraint for the HDO/H2O profiles. In this contribution, we will combine the quality of the MUSICA strategy and of our observations, which are recorded on a regular basis with FTIR spectrometers, under clear-sky conditions, at the NDACC site

  12. Clinical Profile of Concurrent Dengue Fever and Plasmodium vivax Malaria in the Brazilian Amazon: Case Series of 11 Hospitalized Patients

    PubMed Central

    Magalhães, Belisa M. L.; Alexandre, Márcia A. A.; Siqueira, André M.; Melo, Gisely C.; Gimaque, João B. L.; Bastos, Michele S.; Figueiredo, Regina M. P.; Carvalho, Ricardo C.; Tavares, Michel A.; Naveca, Felipe G.; Alonso, Pedro; Bassat, Quique; Lacerda, Marcus V. G.; Mourão, Maria P. G.

    2012-01-01

    Malaria and dengue fever are the most prevalent vector-borne diseases worldwide. This study aims to describe the clinical profile of patients with molecular diagnosis of concurrent malaria and dengue fever in a tropical-endemic area. Eleven patients with concurrent dengue virus (DENV) and Plasmodium vivax infection are reported. Similar frequencies of DENV-2, DENV-3, and DENV-4 were found, including DENV-3/DENV-4 co-infection. In eight patients, the World Health Organization (WHO) criteria for severe malaria could be fulfilled (jaundice being the most common). Only one patient met severe dengue criteria, but warning signs were present in 10. Syndromic surveillance systems must be ready to identify this condition to avoid misinterpretation of severity attributed to a single disease. PMID:23033396

  13. A LYMAN BREAK GALAXY IN THE EPOCH OF REIONIZATION FROM HUBBLE SPACE TELESCOPE GRISM SPECTROSCOPY

    SciTech Connect

    Rhoads, James E.; Malhotra, Sangeeta; Cohen, Seth; Zheng Zhenya; Stern, Daniel; Dickinson, Mark; Pirzkal, Norbert; Grogin, Norman; Koekemoer, Anton; Peth, Michael A.; Spinrad, Hyron; Reddy, Naveen; Hathi, Nimish; Budavari, Tamas; Ferreras, Ignacio; Gardner, Jonathan P.; Gronwall, Caryl; Haiman, Zoltan; Kuemmel, Martin; Meurer, Gerhardt; and others

    2013-08-10

    We present observations of a luminous galaxy at z = 6.573-the end of the reionization epoch-which has been spectroscopically confirmed twice. The first spectroscopic confirmation comes from slitless Hubble Space Telescope Advanced Camera for Surveys grism spectra from the PEARS survey (Probing Evolution And Reionization Spectroscopically), which show a dramatic continuum break in the spectrum at rest frame 1216 A. The second confirmation is done with Keck + DEIMOS. The continuum is not clearly detected with ground-based spectra, but high wavelength resolution enables the Ly{alpha} emission line profile to be determined. We compare the line profile to composite line profiles at z = 4.5. The Ly{alpha} line profile shows no signature of a damping wing attenuation, confirming that the intergalactic gas is ionized at z = 6.57. Spectra of Lyman breaks at yet higher redshifts will be possible using comparably deep observations with IR-sensitive grisms, even at redshifts where Ly{alpha} is too attenuated by the neutral intergalactic medium to be detectable using traditional spectroscopy from the ground.

  14. Lyman-alpha observations of Comet West /1975n/

    NASA Technical Reports Server (NTRS)

    Opal, C. B.; Carruthers, G. R.

    1977-01-01

    The rate of hydrogen production of Comet West is studied through rocket observation of solar Lyman-alpha radiation resonantly scattered by the escaping hydrogen atoms. Two sets of Lyman-alpha exposure sequences are used to obtain computer-smoothed brightness contour (isophote) maps covering a density range of 100:1. A simple radial outflow model is applied to the contour maps to determine the rate of hydrogen production (3.2 by 10 to the 30th power atoms/sec.) Discrepancies between the observed shape of the outer isophotes and predicted models may be explained by optical depth effects, or by the presence of small pieces of the comet's nucleus distributed along the orbit. Hydrogen, carbon, and oxygen production for Comet West and Comet Kohoutek are compared; differences may be accounted for by variations in the composition or evolution of the two comets.

  15. GALEX Imaging Search for Lyman Continuum Emission at z 1

    NASA Astrophysics Data System (ADS)

    Friedman, Peter G.; Small, T. A.; Deharveng, J. M.; Milliard, B.

    2009-01-01

    We present the status and results of a search for Lyman continuum emission from galaxies at z 1. We use GALEX data in the Extended Groth Strip. Our method is to stack FUV image flux at locations of DEEP2 redshift catalog galaxies in the redshift range 1 < z < 1.5. In this range, the GALEX FUV band (1350-1800 A) is sensitive only to rest wavelengths below 912 A. We normalize FUV flux to NUV flux and calculate the Lyman continuum emission escape fraction by fitting SED models to broad-band fluxes from ground-based surveys of the same galaxies. GALEX is a NASA Small Explorer mission with contributions from France and South Korea. This work uses data from the AEGIS collaboration, which is supported by grants from the National Science Foundation, NASA, and the Keck Observatory.

  16. GALEX Imaging Search for Lyman Continuum Emission at z 1

    NASA Astrophysics Data System (ADS)

    Friedman, Peter G.; Small, T. A.; Deharveng, J. M.; Milliard, B.

    2010-01-01

    We present the status and results of a search for Lyman continuum emission from galaxies at z 1. We use GALEX data in the Extended Groth Strip. Our method is to stack FUV image flux at locations of DEEP2 redshift catalog galaxies in the redshift range 1 < z < 1.5. In this range, the GALEX FUV band (1350-1800 A) is sensitive only to rest wavelengths below 912 A. We normalize FUV flux to NUV flux and calculate the Lyman continuum emission escape fraction by fitting SED models to broad-band fluxes from ground-based surveys of the same galaxies. GALEX is a NASA Small Explorer mission with contributions from France and South Korea. This work uses data from the AEGIS collaboration, which is supported by grants from the National Science Foundation, NASA, and the Keck Observatory.

  17. Lyman Continuum Emission Search at z 1 Using GALEX Imaging

    NASA Astrophysics Data System (ADS)

    Friedman, Peter G.; Small, T. A.; Deharveng, J. M.; Milliard, B.

    2007-12-01

    We present the status and results of a search for Lyman continuum emission from galaxies at z 1. We use GALEX data in the Extended Groth Strip. Our method is to stack FUV image flux at locations of DEEP2 redshift catalog galaxies in the redshift range 1 < z < 1.5. In this range, the GALEX FUV band (1350-1800 A) is sensitive only to rest wavelengths below 912 A. We normalize FUV flux to NUV flux and calculate the Lyman continuum emission escape fraction by fitting SED models to broad-band fluxes from ground-based surveys of the same galaxies. GALEX is a NASA Small Explorer mission with contributions from France and South Korea. This work uses data from the AEGIS collaboration, which is supported by grants from the National Science Foundation, NASA, and the Keck Observatory.

  18. New interpretations of extraterrestrial Lyman-alpha observations.

    NASA Technical Reports Server (NTRS)

    Blum, P. W.; Fahr, H. J.

    1972-01-01

    The solar Lyman-alpha radiation pressure affects the orbits and the velocities of the interstellar particles entering the solar system. This leads to enhanced particle losses in the heliosphere, since particles spend a longer time crossing it. This causes a stronger decrease of the density with decreasing distances from the sun than had been calculated without accounting for the radiation pressure. Furthermore, the emission pattern of the solar Lyman-alpha radiation is anisotropic and rotates with the sun in a 27-day period. This causes a temporal change in the location of the intensity extrema. At the same time it produces hydrogen density anisotropies with extrema deviating in their directions from those which had been calculated without consideration of the radiation pressure.

  19. The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP)

    NASA Technical Reports Server (NTRS)

    Ishikawa, Shin-nosuke; Kano, R.; Kobayashi, K.; Bando, T.; Narukage, N..; Ishikawa, R.; Kubo, M.; Katsukawa, Y.; Suematsu, Y.; Hara, H.; Shimizu, T.; Sakao, T.; Ichimoto, K.; Giono, G.; Holloway, T.; Winebarger, A.; Cirtain, J.; DePontieu, B.; Casini, R.; Auchere F.; Bueno, J. Trujillo; Sainz, R. Manso; Belluzzi, L.; Ramos, A. Asensio; Stepan, J.; Carlsson, M.

    2014-01-01

    To Understand energy release process in the Sun including solar flares, it is essentially important to measure the magnetic field of the atmosphere of the Sun. Magnetic field measurement of the upper layers (upper chromosphere and above) was technically difficult and not well investigated yet. Upper chromosphere and transition region magnetic field measurement by Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP) sounding rocket to be launched in 2015. The proposal is already selected and developments of the flight components are going.

  20. Photoelectron Emission and Lyman Alpha Measurements by the CHAMPS Rockets

    NASA Astrophysics Data System (ADS)

    Sternovsky, Z.; Robertson, S. H.; Dickson, S.; Gausa, M. A.; Friedrich, M.; Horanyi, M.

    2012-12-01

    The daytime CHAMPS (CHarge And mass of Meteoritic smoke ParticleS) sounding rocket carried a suit of instruments for the monitoring of photoemission current and Lyman alpha flux as a function of altitude. The results show that photoemission is significant down to 60-75 km altitude, depending on the photo-emitting surface. Lyman alpha was detected to about 65 km altitude. The daytime CHAMPS rocket launched on 13 October 13:50 UT from the Andøya Rocket Range, Norway. The CHAMPS instruments detected layers of particles, probably of meteoric origin, charged both positive and negative in the 63-93 km altitude range. The CHAMPS payloads were also designed to characterize the plasma environment and thus also carried Faraday rotation antennas and electron and ion probes. Solar UV plays an important role in charge balance for both the rocket body and meteoric smoke particles. Photoelectron emission was monitored by a set of three detectors consisting of an emitting surface (Platinum, Aluminum and Zirconium) biased at -10 V and placed behind a fine grid. The Al and Zr surfaces produced similar signals with photoemission measureable above 75 km altitude. The Pt surface emitted photoelectrons even below 60 km altitude. The different behavior of Pt can possibly be due to exposure to atomic oxygen, though further analysis is necessary. The solar Lyman alpha radiation was measured by a UV photodiode placed behind a pair or filters to reduce the contribution to the signal from visible light. Lyman alpha was detected down to 65 km altitude, which confirms that photo-detachment and photoelectric charging needs to be considered for the charge balance of particle layers in the mesosphere region. All instruments were calibrated at the facilities of the Laboratory for Atmospheric and Space Physics at the University of Colorado.

  1. Zenith angle dependence of the geocoronal Lyman-alpha glow.

    NASA Technical Reports Server (NTRS)

    Paresce, F.; Kumar, S.; Bowyer, S.

    1972-01-01

    Review of the observations made on the zenith angle dependence and intensity of the geocoronal hydrogen Lyman-alpha glow by means of one of four extreme ultraviolet photometers flown to an altitude of 264 km on a Nike Tomahawk rocket launched from Thumba, India, in March 1970. The results obtained are compared with Meier and Mange's (1970) theoretical predictions. The possible causes for the discrepancies found are discussed.

  2. Dynamical and Stellar Masses of Lyman-alpha Galaxies

    NASA Astrophysics Data System (ADS)

    Rhoads, James E.; Malhotra, S.; McLinden, E.; Richardson, M. L.; Finkelstein, S. L.; Tilvi, V. S.

    2012-01-01

    We have observed strong nebular lines of [OIII] and H alpha for Lyman-alpha galaxies at z=2-3.1 using Keck+NIRSPEC, LBT+LUCIFER, and Gemini+NIFS. [OIII] 5007 is strong enough to dominate the 2 micron K band fluxes of these galaxies, and leads to an overestimate of the stellar mass of the galaxy by an order of magnitude. After correcting for the observed [OIII] lines, we infer low masses and young ages for these galaxies. We also use the physical widths of the rest-optical lines, combined with spatial sizes from HST imaging, to obtain direct dynamical mass estimates of Lyman alpha galaxies (which cannot be done using the resonantly scattered Lyman alpha line). Finally, we combine our stellar mass estimates and line widths to place these galaxies on the baryonic Tully-Fisher relation. We find that the stellar masses required to reproduce the observed light are lower than one would expect based on the galaxies' line widths. The stellar mass densities of these galaxies are comparable to those of elliptical galaxies today. We gratefully acknowledge support from NSF grant NSF-AST-0808165.

  3. The Lyman-alpha Imager onboard Solar Polar Orbit Telescope

    NASA Astrophysics Data System (ADS)

    Li, Baoquan; Li, Haitao; Zhou, Sizhong; Jiang, Bo

    2013-12-01

    Solar Polar ORbit Telescope (SPORT) was originally proposed in 2004 by the National Space Science Center, Chinese Academy of Sciences, which is currently being under background engineering study phase in China. SPORT will carry a suite of remote-sensing and in-situ instruments to observe coronal mass ejections (CMEs), solar high-latitude magnetism, and the fast solar wind from a polar orbit around the Sun. The Lyman-alpha Imager (LMI) is one of the key remotesensing instruments onboard SPORT with 45arcmin FOV, 2000mm effective focal length and 1.4arcsec/pixel spatial resolution . The size of LMI is φ150×1000mm, and the weight is less than10kg, including the 7kg telescope tube and 3kg electronic box. There are three 121.6nm filters used in the LMI optical path, so the 98% spectral purity image of 121.6nm can be achieved. The 121.6nm solar Lyman-alpha line is produced in the chromosphere and very sensitive to plasma temperature, plasma velocity and magnetism variation in the chromosphere. Solar Lyman-alpha disk image is an ideal tracker for corona magnetism variation.

  4. Analysis of Radiation Pneumonitis Risk Using a Generalized Lyman Model

    SciTech Connect

    Tucker, Susan L. Liu, H. Helen; Liao Zhongxing; Wei Xiong; Wang Shulian; Jin Hekun; Komaki, Ritsuko; Martel, Mary K.; Mohan, Radhe

    2008-10-01

    Purpose: To introduce a version of the Lyman normal-tissue complication probability (NTCP) model adapted to incorporate censored time-to-toxicity data and clinical risk factors and to apply the generalized model to analysis of radiation pneumonitis (RP) risk. Methods and Materials: Medical records and radiation treatment plans were reviewed retrospectively for 576 patients with non-small cell lung cancer treated with radiotherapy. The time to severe (Grade {>=}3) RP was computed, with event times censored at last follow-up for patients not experiencing this endpoint. The censored time-to-toxicity data were analyzed using the standard and generalized Lyman models with patient smoking status taken into account. Results: The generalized Lyman model with patient smoking status taken into account produced NTCP estimates up to 27 percentage points different from the model based on dose-volume factors alone. The generalized model also predicted that 8% of the expected cases of severe RP were unobserved because of censoring. The estimated volume parameter for lung was not significantly different from n = 1, corresponding to mean lung dose. Conclusions: NTCP models historically have been based solely on dose-volume effects and binary (yes/no) toxicity data. Our results demonstrate that inclusion of nondosimetric risk factors and censored time-to-event data can markedly affect outcome predictions made using NTCP models.

  5. Analysis of solar Lyman alpha radiation in the heliosphere

    NASA Astrophysics Data System (ADS)

    Fayock, B.; Zank, G. P.; Heerikhuisen, J.

    2013-06-01

    Various NASA spacecraft have measured ultraviolet radiation in the heliosphere at different locations over time. Much of this data corresponds to back-scattered Lyman-alpha radiation from neutral hydrogen, particularly in the context of planetary atmospheric measurements and inferred solar activity. Less attention has been devoted to using this data in the context of large-scale heliospheric simulations with complex global models. A 3D Monte Carlo simulation has been developed for analysis of Lyman-alpha scattering using global heliospheric models developed within CSPAR as a background. The simulation tracks individual photons in a sun-centered spherical coordinate system with a radial limit of 1000 AU while retaining statistics for each cell within the grid space, which is defined by the global input data. Two of the statistics collected are the number of scatters and the total distance traveled by photons within a cell. Those photons directed towards the sun provide a measure of backscatter intensity that can be compared to antisolar observations of Lyman-alpha photons by spacecraft. Preliminary results reveal a similar trend of intensity between simulation in the upwind direction and reduced Voyager data, suggesting an accurate portrayal of neutral hydrogen in the heliosphere.

  6. The Lyman alpha forest of the high-z quasar 0000-263

    NASA Technical Reports Server (NTRS)

    Penprase, Bryan; Gilmozzi, Roberto; Bowen, David; Madau, Piero

    1993-01-01

    Medium-resolution (delta(v) = 45 km/s) optical spectra of the bright, high-redshift (z = 4.1) quasar 0000-263 taken at the ESO 3.5-m NTT telescope were analyzed to determine the distribution of column densities, velocities and line widths of the Lyman-alpha forest absorption components. The values of NH, b, and z were determined by fitting Voigt profiles to the lines, and convolving with a Gaussian instrumental response function. Over 350 components with log N(sub H) greater than 13.2 were identified. An analysis of the dependence of the number of components with z reveals that the number evolution of components obeys the power law dN/dz varies as (1+z)(sup gamma), where gamma = 0.5 +/- 0.4 for the sample of 182 lines with log N(sub H) greater than 14.0. The distribution of component strengths is found to obey f(N(sub H)) varies as N(sub h)(sup -beta), where beta = -1.55 for components with log(N(sub H)) is greater than 14.7, and beta = -0.68 for the components with log(N(sub H)) greater than 13.5. A distinct break in the f(N(sub H)) histogram is also observed, at log(N(sub H)) is approximately 14.7. The results are briefly considered in the context of theoretical models of quasar Lyman alpha clouds and their evolution.

  7. Probing the circumgalactic medium at high-redshift using composite BOSS spectra of strong Lyman α forest absorbers

    NASA Astrophysics Data System (ADS)

    Pieri, Matthew M.; Mortonson, Michael J.; Frank, Stephan; Crighton, Neil; Weinberg, David H.; Lee, Khee-Gan; Noterdaeme, Pasquier; Bailey, Stephen; Busca, Nicolas; Ge, Jian; Kirkby, David; Lundgren, Britt; Mathur, Smita; Pâris, Isabelle; Palanque-Delabrouille, Nathalie; Petitjean, Patrick; Rich, James; Ross, Nicholas P.; Schneider, Donald P.; York, Donald G.

    2014-06-01

    We present composite spectra constructed from a sample of 242 150 Lyman α (Lyα) forest absorbers at redshifts 2.4 < z < 3.1 identified in quasar spectra from the Baryon Oscillation Spectroscopic Survey (BOSS) as part of Data Release 9 of the Sloan Digital Sky Survey III. We select forest absorbers by their flux in bins 138 km s-1 wide (approximately the size of the BOSS resolution element). We split these absorbers into five samples spanning the range of flux -0.05 ≤ F < 0.45. Tests on a smaller set of high-resolution spectra show that our three strongest absorption samples would probe circumgalactic regions (projected separation <300 proper kpc and |Δv| < 300 km s-1) in about 60 per cent of cases for very high signal-to-noise ratio. Within this subset, weakening Lyα absorption is associated with decreasing purity of circumgalactic selection once BOSS noise is included. Our weaker two Lyα absorption samples are dominated by the intergalactic medium. We present composite spectra of these samples and a catalogue of measured absorption features from H I and 13 metal ionization species, all of which we make available to the community. We compare measurements of seven Lyman series transitions in our composite spectra to single line models and obtain further constraints from their associated excess Lyman limit opacity. This analysis provides results consistent with column densities over the range 14.4 ≲ log (N_{H I}) ≲ 16.45. We compare our measurements of metal absorption to a variety of simple single-line, single-phase models for a preliminary interpretation. Our results imply clumping on scales down to ˜30 pc and near-solar metallicities in the circumgalactic samples, while high-ionization metal absorption consistent with typical IGM densities and metallicities is visible in all samples.

  8. Probing the High Redshift IGM: SPH+P{(3}) MG Simulations of the Lyman-alpha Forest

    NASA Astrophysics Data System (ADS)

    Wadsley, J.; Bond, J. R.

    1996-12-01

    Our understanding of the Lyman-alpha forest has received a great boost with the advent of the Keck Telescope and large 3D hydrodynamical simulations. We simulate the high redshift universe using the SPH technique with a P{(3}) MG (Particle-Particle Particle-MultiGrid) non-periodic gravity solver. We employ a high resolution (1 kpc) inner volume, essential for capturing the complex gas physics, larger medium and low resolution volumes surrounding it, essential for correct larger scale tidal fields, and a self-consistently applied, uniform tidal field to model the influence of ultra long waves. Such care is needed because the power per decade in the density fluctuations falls off very slowly in the dwarf galaxy regime of relevance to Lyman alpha clouds. The oft-used periodic boundary condition approach to simulations is ill-suited to proper treatment of the tides. We use constrained field realizations to probe a selection of environments, including voids, quiescent regions, proto-dwarf galaxies and regions experiencing strong tides, such as large galaxy halos and galaxy-galaxy filamentary bridges. We statistically combine our simulations to provide a more comprehensive sample of the universe, including ``rare event'' regions which are difficult to obtain in unrestricted FFT-based approaches. We fit Voigt profiles to the Lyman alpha spectra computed from our simulations direct comparison with the data, e.g., the column density distribution, line widths, temperatures, multiple line-of-sight correlations and the HI (and HeII) flux decrements. We demonstrate the importance of (1) the photoionizing UV flux level and history, (2) tidal environment and (3) differing cosmologies, including CDM and CDM+Lambda. With galaxy-scale rms fluctuations ~ 1 at z=3 and a UV choice motivated by proximity effect observations, the simulations give results in excellent agreement with the data.

  9. 75 FR 53323 - Certificate of Alternative Compliance for the Offshore Supply Vessel LYMAN MARTIN

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-31

    ... SECURITY Coast Guard Certificate of Alternative Compliance for the Offshore Supply Vessel LYMAN MARTIN... Alternative Compliance was issued for the offshore supply vessel LYMAN MARTIN as required by 33 U.S.C. 1605(c... Title 33, Code of Federal Regulation, parts 81 and 89, has been issued for the offshore supply...

  10. Measurement of precipitation induced FUV emission and Geocoronal Lyman Alpha from the IMI mission

    NASA Technical Reports Server (NTRS)

    Mende, Stephen B.; Fuselier, S. A.; Rairden, R. L.

    1995-01-01

    This final report describes the activities of the Lockheed Martin Palo Alto Research Laboratory in studying the measurement of ion and electron precipitation induced Far Ultra-Violet (FUV) emissions and Geocoronal Lyman Alpha for the NASA Inner Magnetospheric Imager (IMI) mission. this study examined promising techniques that may allow combining several FUV instruments that would separately measure proton aurora, electron aurora, and geocoronal Lyman alpha into a single instrument operated on a spinning spacecraft. The study consisted of two parts. First, the geocoronal Lyman alpha, proton aurora, and electron aurora emissions were modeled to determine instrument requirements. Second, several promising techniques were investigated to determine if they were suitable for use in an IMI-type mission. Among the techniques investigated were the Hydrogen gas cell for eliminating cold geocoronal Lyman alpha emissions, and a coded aperture spectrometer with sufficient resolution to separate Doppler shifted Lyman alpha components.

  11. Lyman alpha radiation in external galaxies

    NASA Technical Reports Server (NTRS)

    Neufeld, David A.; Mckee, Christopher F.

    1990-01-01

    The Ly alpha line of atomic hydrogen is often a luminous component of the radiation emitted by distant galaxies. Except for those galaxies which have a substantial central source of non-stellar ionizing radiation, most of the Ly alpha radiation emitted by galaxies is generated within regions of the interstellar medium which are photoionized by starlight. Conversely, much of the energy radiated by photoionized regions is carried by the Ly alpha line. Only hot, massive stars are capable of ionizing hydrogen in the interstellar medium which surrounds them, and because such stars are necessarily short-lived, Ly alpha emission traces regions of active star formation. Researchers argue that the strength of the Ly alpha emission observed from external galaxies may be used to estimate quantitatively the dust content of the emitting region, while the Ly alpha line profile is sensitive to the presence of shock waves. Interstellar dust particles and shock waves are intimately associated with the process of star formation in two senses. First, both dust particles and shock waves owe their existence to stellar activity; second, they may both serve as agents which facilitate the formation of stars, shocks by triggering gravitational instabilities in the interstellar gas that they compress, and dust by shielding star-forming molecular clouds from the ionizing and dissociative effects of external UV radiation. By using Ly alpha observations as a probe of the dust content in diffuse gas at high redshift, we might hope to learn about the earliest epochs of star formation.

  12. Clinico-radiological profile and outcome of dengue patients with central nervous system manifestations: A case series in an Eastern India tertiary care hospital

    PubMed Central

    Pal, Souren; Sen, Kaushik; Biswas, Nirendra Mohan; Ghosal, Anirban; Rousan Jaman, S. K.; Yashavantha Kumar, K. Y.

    2016-01-01

    Background and Objective: Dengue, an acute viral disease, transmitted by Aedes mosquitoes, has a variable clinical spectrum ranging from asymptomatic infection to life-threatening dengue hemorrhagic fever and dengue shock syndrome. However, neurological complications, in general, are unusual but have been observed more frequently in the recent past, and some studies highlighted varied neurological complications during the course of illness. Although dengue is classically considered a nonneurotropic virus, there is increasing evidence for dengue viral neurotropism. In this study, we have evaluated clinico-radiological profile and outcome of nine serologically confirmed dengue patients having varied manifestations of central nervous system (CNS) involvement. Materials and Methods: All the consecutive patients presented with neurological complications with positive serology for dengue infection (IgM positivity) in Department of Medicine, in a tertiary care hospital in Eastern India from August 2013 to October 2014 were included in the study. These patients were subjected to a detailed clinical evaluation, laboratory assessment including complete hemogram, coagulation profile, liver function test, serum electrolytes, and routine CSF (Cerebrospinal Fluid) study with the exclusion of other common neuroinvasive pathogens. Results: Out of 9 patients with neurological complications associated with confirmed dengue infection, 2 (22%) patients had dengue encephalopathy, 5 (56%) patients have dengue encephalitis, 1 (11%) patient had dengue meningitis, and 1 (11%) patient had postdengue immune-mediated CNS involvement. Conclusion: This case series reaffirms the occurrence of varied CNS manifestations in dengue virus infection and underlines the importance of inclusion of dengue in the differential diagnosis of acute encephalitis syndrome. PMID:26933357

  13. Downflow dryout in a heated ribbed vertical annulus with a cosine power profile (Results from test series ECS-2, WSR, and ECS-2cE)

    SciTech Connect

    Larson, T.K.; Anderson, J.L.; Condie, K.G.

    1990-12-01

    Experiments designed to investigate surface dryout in a heated, ribbed annulus test section simulating one of the annular coolant channels of a Savannah River Plant production reactor Mark 22 fuel assembly have been conducted at the Idaho National Engineering Laboratory. The inner surface of the annulus was constructed of aluminum and was electrically heated to provide an axial cosine power profile and a flat azimuthal power shape. Data presented in this report are from the ECS-2, WSR, and ECS-2cE series of tests. These experiments were conducted to examine the onset of wall thermal excursion for a range of flow, inlet fluid temperature, and annulus outlet pressure. Hydraulic boundary conditions on the test section represent flowrates (0.1--1.4 1/s), inlet fluid temperatures (293--345 K), and outlet pressures (-18--139.7 cm of water relative to the bottom of the heated length (61--200 cm of water relative to the bottom of the lower plenum)) expected to occur during the Emergency Coolant System (ECS) phase of postulated Loss-of-Coolant Accident in a production reactor. The onset of thermal excursion based on the present data is consistent with data gathered in test rigs with flat axial power profiles. The data indicate that wall dryout is primarily a function of liquid superficial velocity. Air entrainment rate was observed to be a strong function of the boundary conditions (primarily flowrate and liquid temperature), but had a minor effect on the power at the onset of thermal excursion for the range of conditions examined. 14 refs., 33 figs., 13 tabs.

  14. The Lyman alpha reference sample. VI. Lyman alpha escape from the edge-on disk galaxy Mrk 1486

    NASA Astrophysics Data System (ADS)

    Duval, Florent; Östlin, Göran; Hayes, Matthew; Zackrisson, Erik; Verhamme, Anne; Orlitova, Ivana; Adamo, Angela; Guaita, Lucia; Melinder, Jens; Cannon, John M.; Laursen, Peter; Rivera-Thorsen, Thoger; Herenz, E. Christian; Gruyters, Pieter; Mas-Hesse, J. Miguel; Kunth, Daniel; Sandberg, Andreas; Schaerer, Daniel; Månsson, Tore

    2016-03-01

    Context. Recent numerical simulations suggest that the strength of the Lyman alpha (Lyα) line of star-forming disk galaxies strongly depends on the inclination at which they are observed: from edge-on to face-on, we expect to see a change from a strongly attenuated Lyα line to a strong Lyα emission line. Aims: We aim to understand how a strong Lyα emission line is able to escape from the low-redshift highly inclined (edge-on) disk galaxy Mrk 1486 (z ~ 0.0338). To our knowledge, this work is the first observational study of Lyα transport inside an edge-on disk galaxy. Methods: Using a large set of HST imaging and spectroscopic data, we investigated the interstellar medium (ISM) structure and the dominant source of Lyα radiation inside Mrk 1486. Moreover, using a 3D Monte Carlo Lyα radiation transfer code, we studied the radiative transfer of Lyα and UV continuum photons inside a 3D geometry of neutral hydrogen (HI) and dust that models the ISM structure at the galaxy center. Our numerical simulations predicted the Lyα line profile that we then compared to the one observed in the HST/COS spectrum of Mrk 1486. Results: While a pronounced Lyα absorption line emerges from the disk of Mrk 1486, very extended Lyα structures are observed at large radii from the galaxy center: a large Lyα-halo and two very bright Lyα regions located slightly above and below the disk plane. The analysis of IFU Hα spectroscopic data of Mrk 1486 indicates the presence of two bipolar outflowing halos of HI gas at the same location as these two bright Lyα regions. Comparing different diagnostic diagrams (such as [OIII]5007/Hβ versus [OI]6300/Hα) to photo- and shock-ionization models, we find that the Lyα production of Mrk 1486 is dominated by photoionization inside the galaxy disk. From this perspective, our numerical simulations succeed in reproducing the strength and shape of the observed Lyα emission line of Mrk 1486 by assuming a scenario in which the Lyα photons are

  15. The Lyman β forest as a cosmic thermometer

    SciTech Connect

    Iršič, Vid; Viel, Matteo E-mail: viel@oats.inaf.it

    2014-12-01

    We present a comprehensive analysis of high resolution hydrodynamic simulations in terms of Lyman α and Lyman β one dimensional flux power spectra P{sub αα} and P{sub ββ}). In particular, we focus on the behaviour that the flux auto-power spectra and cross-power spectra P{sub αβ}) display when the intergalactic medium (IGM) thermal history is changed in a range of values that bracket a reference model, while cosmological parameters are kept fixed to best fit the cosmic microwave background data. We present empirical fits that describe at the sub-percent level the dependence of the power spectra on the thermal parameters. At the largest scales, the power spectra show a constant bias between each other that is set by the parameters describing the IGM thermal state. The cross-power spectrum has an oscillatory pattern and crosses zero at a scale which depends on T{sub 0}, the IGM temperature at the mean density, for reasonable values of the power-law index γ of the IGM temperature-density relation T=T{sub 0}(1+δ){sup γ-1}). By performing a Fisher matrix analysis, we find that the power spectrum P{sub ββ} is more sensitive to the thermal history than P{sub αα} alone, due to the fact that it probes denser regions than Lyman α. When we combine the power and cross spectra the constraints on γ can be improved by a factor ∼ 4, while the constraints on T{sub 0} improve by a factor of ∼ 2. We address the role of signal-to-noise and resolution by mocking realistic observations and we conclude that the framework presented in this work can significantly improve the knowledge of the IGM thermal state, which will in turn guarantee better constraints on IGM-derived cosmological parameters.

  16. Weathering and denudation rates determined by the combined analysis of Uranium series nuclides and in situ Beryllium in a weathering profile (Vosges massif, Strengbach catchment, France)

    NASA Astrophysics Data System (ADS)

    Ackerer, Julien; Chabaux, François; Van der Woerd, Jerome; Pelt, Eric; Kali, Elise; Pierret, Marie Claire; Viville, Daniel; Wyns, Robert; Negrel, Philippe

    2015-04-01

    The determination of soil sustainability is a major issue for societies. It is crucial to estimate the soil formation and denudation rates to evaluate the landscapes stability and their response to natural or anthropological forcings. In this work, we propose to combine the analysis of Uranium-Thorium-Radium isotopes with the cosmogenic in situ Beryllium in a weathering profile located in the Strengbach catchment to estimate both production rate of regolith and denudation rate of soil and to establish a soil mass balance at millennial timescales. The weathering profile is located on the summit of the watershed and extending from the top soil to the granitic fractured bedrock at 2 m depth. Whole rock data shows different trends of variation of major and trace element concentrations and also of U-Th-Ra disequilibria in the upper part of the regolith (0-80 cm) and the deeper part of the fractured saprolith and/or bedrock (100cm-200cm). Modeling of the U-Th-Ra data in this deeper part of the profile, using a particle swarm optimization model dedicated to isotopic ratios leads to a regolith production rate at the summit of the watershed of 35 ± 9 T/km²/year. In addition, a numerical optimization for nonlinear inverse problem has been performed to estimate the regolith residence time and the mean denudation rate at the summit from the Beryllium data. The results show that the regolith residence time is about 14 000 years and the mean denudation rate is 32 ± 8 T/km²/year. The consistency between the regolith production rate and the soil denudation rate suggests therefore that in such a temperate context, the long-term mass balance of soil developed on granitic bedrock would be close to a steady state. The data also highlights that the determination of a weathering production rate from analysis of Uranium series nuclides in whole rock samples cannot be easily obtained by analyzing only surficial soil samples, and requires the analysis of the deeper fractured saprolith

  17. Rest-Optical Morphology of 2Lyman Alpha Emitters: Comparison with Rest-UV and Other High-redshift Galaxies

    NASA Astrophysics Data System (ADS)

    Bond, Nicholas

    2013-10-01

    Lyman Alpha Emitting galaxies {LAEs} seen at redshifts 2 and 3 are progenitors of typical present-day galaxies like the Milky Way seen in their initial stage of star formation. LAEs are younger, lower in mass, and less chemically evolved than the better-studied Lyman break galaxies {LBGs}, and HST imaging probes the physical properties of these objects at sub-kiloparsec resolution.We will use archival WFC3-NIR images of the HUDF, CANDELS GOODS-S, and ERS GOODS-S to study the rest-frame optical morphology of 66 Lyman Alpha Emitters at z=2.1 and z=3.1, along with comparison samples of star-forming BzK galaxies and Lyman break galaxies at similar redshifts. For objects with sufficient signal-to-noise, we will determine Sersic profiles, CAS {Concentration/Asymmetry/clumpinesS}, and internal color dispersions. We will use an existing pipeline, which we developed and applied to rest-UV ACS images of these galaxies, enabling object-by-object comparisons of rest-optical and rest-UV morphology.Our results will reveal the nature of star formation in low-mass high-redshift galaxies where the bulk of present-day stars were formed and will provide a crucial point of comparison to the morphology of continuum-selected galaxies studied by the CANDELS team. We will illustrate if the distribution between clumpy and/or merger-driven star formation is correlated with galaxy properties such as mass or dust extinction. Our results will also improve the interpretation of morphological studies at z>4, where only rest-UV HST images are available. It will also allow for evolutionary comparisons with rest-UV morphologies at lower redshifts that are underway from UVUDF.

  18. A coronagraphic absorbing cloud reveals the narrow-line region and extended Lyman α emission of QSO J0823+0529

    NASA Astrophysics Data System (ADS)

    Fathivavsari, H.; Petitjean, P.; Noterdaeme, P.; Pâris, I.; Finley, H.; López, S.; Srianand, R.; Sánchez, P.

    2015-11-01

    We report long-slit spectroscopic observations of the quasar SDSS J082303.22+052907.6 (z_{C IV}} ˜ 3.1875), whose broad-line region (BLR) is partly eclipsed by a strong damped Lyman α (DLA; logN(H I) = 21.7) cloud. This allows us to study the narrow-line region (NLR) of the quasar and the Lyman α emission from the host galaxy. Using CLOUDY models that explain the presence of strong N V and P V absorption together with the detection of Si II* and O I** absorption in the DLA, we show that the density and the distance of the cloud to the quasar are in the ranges 180 < nH < 710 cm-3 and 580 > r0 > 230 pc, respectively. Sizes of the neutral (˜2-9pc) and highly ionized phases (˜3-80pc) are consistent with the partial coverage of the C IV BLR by the C IV absorption from the DLA (covering factor of ˜0.85). We show that the residuals are consistent with emission from the NLR with C IV/Lyman α ratios varying from 0 to 0.29 through the profile. Remarkably, we detect extended Lyman α emission up to 25 kpc to the north and west directions and 15 kpc to the south and east. We interpret the emission as the superposition of strong emission in the plane of the galaxy up to 10 kpc with emission in a wind of projected velocity ˜500 km s-1 which is seen up to 25 kpc. The low metallicity of the DLA (0.27 solar) argues for at least part of this gas being infalling towards the active galactic nucleus and possibly being located where accretion from cold streams ends up.

  19. Monitoring vegetation recovery in fire-affected areas using temporal profiles of spectral signal from time series MODIS and LANDSAT satellite images

    NASA Astrophysics Data System (ADS)

    Georgopoulou, Danai; Koutsias, Nikos

    2015-04-01

    Vegetation phenology is an important element of vegetation characteristics that can be useful in vegetation monitoring especially when satellite remote sensing observations are used. In that sense temporal profiles extracted from spectral signal of time series MODIS and LANDSAT satellite images can be used to characterize vegetation phenology and thus to be helpful for monitoring vegetation recovery in fire-affected areas. The aim of this study is to explore the vegetation recovery pattern of the catastrophic wildfires that occurred in Peloponnisos, southern Greece, in 2007. These fires caused the loss of 67 lives and were recognized as the most extreme natural disaster in the country's recent history. Satellite remote sensing data from MODIS and LANDSAT satellites in the period from 2000 to 2014 were acquired and processed to extract the temporal profiles of the spectral signal for selected areas within the fire-affected areas. This dataset and time period analyzed together with the time that these fires occurred gave the opportunity to create temporal profiles seven years before and seven years after the fire. The different scale of the data used gave us the chance to understand how vegetation phenology and therefore the recovery patterns are influenced by the spatial resolution of the satellite data used. Different metrics linked to key phenological events have been created and used to assess vegetation recovery in the fire-affected areas. Our analysis was focused in the main land cover types that were mostly affected by the 2007 wildland fires. Based on CORINE land-cover maps these were agricultural lands highly interspersed with large areas of natural vegetation followed by sclerophyllous vegetation, transitional woodland shrubs, complex cultivation patterns and olive groves. Apart of the use of the original spectral data we estimated and used vegetation indices commonly found in vegetation studies as well as in burned area mapping studies. In this study we

  20. Modeled and observed N2 Lyman-Birge-Hopfield band emissions: A comparison

    NASA Astrophysics Data System (ADS)

    Eastes, R. W.; Murray, D. J.; Aksnes, A.; Budzien, S. A.; Daniell, R. E.; Krywonos, A.

    2011-12-01

    A thorough understanding of how the N2 Lyman-Birge-Hopfield (LBH) band emissions vary with altitude is essential to the use of this emission by space-based remote sensors. In this paper, model-to-model comparisons are first performed to elucidate the influence of the solar irradiance spectrum, intrasystem cascade excitation, and O2 photoabsorption on the limb profile. Next, the observed LBH emissions measured by the High resolution Ionospheric and Thermospheric Spectrograph aboard the Advanced Research and Global Observation Satellite are compared with modeled LBH limb profiles to determine which combination of parameters provides the best agreement. The analysis concentrates on the altitude dependence of the LBH (1,1) band, the brightest LBH emission in the observations. In the analysis, satellite drag data are used to constrain the neutral densities used for the data-to-model comparisons. For the average limb profiles on two of the three days analyzed (28, 29, and 30 July 2001), calculations using direct excitation alone give slightly better agreement with the observations than did calculations with cascading between the singlet electronic N2 states (a1Πg, a‧Σ-u, and w1Δu) however, the differences between the observed profiles and either model are possibly greater than the differences between the models. Nevertheless, both models give excellent agreement with the observations, indicating that current models provide an adequate description of the altitude variation of the N2 LBH (1,1) band emissions. Consequently, when using the LBH bands to remotely sense thermospheric temperatures, which can be used to provide an unprecedented view of the thermosphere, the temperatures derived have a negligible dependence on the model used.

  1. Lyman alpha initiated winds in late-type stars

    NASA Technical Reports Server (NTRS)

    Haisch, B. M.; Van Der Hucht, K. A.; Linsky, J. L.

    1979-01-01

    One of the first major results of the IUE survey of late-type stars was the discovery of a sharp division in the HR diagram between stars with solar type spectra (chromosphere and transition region lines) and those with non-solar type spectra (only chromosphere lines). This result is especially interesting in view of observational evidence for mass loss from G and K giants and super-giants discussed recently by both Reimers and Stencel. In the present paper models of both hot coronae and cool wind flows are calculated using stellar model chromospheres as starting points for stellar wind calculations in order to investigate the possibility of having a 'supersonic transition locus' in the HR diagram dividing hot coronae from cool winds. It is concluded from these models that the Lyman-alpha flux may play an important role in determining the location of a stellar wind critical point. The interaction of Lyman-alpha radiation pressure with Alfven waves in producing strong, low temperature stellar winds in the star Arcturus is investigated.

  2. Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP)

    NASA Technical Reports Server (NTRS)

    Kano, Ryohei; Bando, Takamasa; Narukage, Noriyuki; Ishikawa, Ryoko; Kubo, Masahito; Katsukawa, Yukio; Ishikawa, Shin-­nosuke; Hara, Hirohisa; Suematsu, Yoshinori; Giono, Gabriel; Shimizu, Toshifumi; Sakao, Taro; Ichimoto, Kiyoshi; Goto, Motoshi; Winebarger, amy; Kobayashi, Ken; Trujullo Bueno, Javier; Auchere, Frederic

    2015-01-01

    Chromosphere, the transition layer of the sun is a region to switch to the magnetic pressure dominated from plasma pressure dominated, simultaneous observation of the detailed magnetic field measurement and plasma of dynamic phenomenon here is what is the frontier of the next solar physics. As This is a challenge that has just mentioned, even the next solar observation satellite plan SOLAR-C, in the experiments we had used a NASA sounding rocket for the first time in the SOLAR-C plan, will address the chromosphere-transition layer magnetic field measurement there. It is, is a Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) plan, the linear polarization of Lyman ?? emission lines chromosphere-transition layer shoots (121.6nm) were detected in 0.1 percent of high accuracy, a new technique called Hanre effect I get the magnetic field information of chromosphere-transition layer. In Japan, the US and Europe joint observation in November 2012 as a rocket experiment is adopted to NASA this plan that full-scale start-up, start from assembly work is 2014 spring flight observation device, currently, it is where the alignment of the optical elements have been implemented. After this, it is planned to continue with the performance evaluation towards the observation implementation of summer 2015. In addition to once again explain the contents of the plan In this presentation, we report an overview of the entire development and preparation current status.

  3. Evolution of high-redshift Lyman-limit absorption systems

    SciTech Connect

    Lanzetta, K.M. )

    1991-07-01

    Results are presented of a new spectroscopic survey of high-redshift Lyman-limit absorption systems. Based on this data set, the rate of incidence of the Lyman-limit systems with z greater than about 2.5 is found to evolve strongly with redshift in the sense that the product of the number density per unit comoving volume and the absorption cross section increases with increasing redshift. If the observed evolution indicates intrinsic evolution of the absorbers, this result suggests that the evolution detected previously for the C IV-selected absorbers over a similar redshift range is not naturally interpreted as evolution of the ionization level of the absorbers rather than as a chemical enrichment effect. The data are also used to investigate the H I column density distribution and to examine the multiple-component structure of the absorbing complexes. The H I column density distribution is found to be well fitted by a power-law form. 35 refs.

  4. Lyman-alpha forests cool warm dark matter

    NASA Astrophysics Data System (ADS)

    Baur, Julien; Palanque-Delabrouille, Nathalie; Yèche, Christophe; Magneville, Christophe; Viel, Matteo

    2016-08-01

    The free-streaming of keV-scale particles impacts structure growth on scales that are probed by the Lyman-alpha forest of distant quasars. Using an unprecedentedly large sample of medium-resolution QSO spectra from the ninth data release of SDSS, along with a state-of-the-art set of hydrodynamical simulations to model the Lyman-alpha forest in the non-linear regime, we issue one of the tightest bounds to date, from Ly-α data alone, on pure dark matter particles: mX>4.09 keV (95% CL) for early decoupled thermal relics such as a hypothetical gravitino, and correspondingly ms>24.4 keV (95% CL) for a non-resonantly produced right-handed neutrino. This limit depends on the value on ns, and Planck measures a higher value of ns than SDSS-III/BOSS. Our bounds thus change slightly when Ly-α data are combined with CMB data from Planck 2016. The limits shift to mX>2.96 keV (95% CL) and ms>16.0 keV (95% CL). Thanks to SDSS-III data featuring smaller uncertainties and covering a larger redshift range than SDSS-I data, our bounds confirm the most stringent results established by previous works and are further at odds with a purely non-resonantly produced sterile neutrino as dark matter.

  5. [OIII] Emission and Gas Kinematics in a Lyman-alpha Blob at z ~ 3.1

    NASA Astrophysics Data System (ADS)

    McLinden, Emily; Rhoads, J. E.; Malhotra, S.; Hibon, P.; Tilvi, V.

    2013-01-01

    We present spectroscopic measurements of the [OIII] emission line from two subregions of strong Lyman-alpha emission in a radio-quiet Lyman-alpha blob (LAB). The blob under study is LAB1 at z ~ 3.1 first reported, by Steidel et al (2000). The [OIII] detections are from the two Lyman break galaxies embedded in the blob halo. We made our [OIII] measurements with LUCIFER on the 8.4m Large Binocular Telescope and NIRSPEC on 10m Keck Telescope. Comparing the redshift of the [OIII] to Lyman-alpha redshifts allows us to take a step towards understanding the kinematics of the gas in the blob. Using both LUCIFER and NIRSPEC we consistently find velocity offsets between the [OIII] and Lyman-alpha redshifts consistent with 0 km/s in both subregions studied (ranging from -43.88 ± 69.01 -- 36.58 ± 63.85 km/s). We discuss the possible implications of this result, as it could downplay the role of winds and outflows in powering the Lyman-alpha emission in this LAB, since a velocity offset between nebular emission lines and Lyman-alpha are often interpreted as evidence of large-scale outflows.

  6. Shaping ability of ProFile.04 Taper Series 29 rotary nickel-titanium instruments in simulated root canals. Part 2.

    PubMed

    Thompson, S A; Dummer, P M

    1997-01-01

    The aim of this study was to determine the shaping ability of ProFile.04 Taper Series 29 rotary nickel-titanium instruments in simulated canals. A total of 40 simulated root canals made up of four different shapes in terms of angle and position of curvature were prepared by ProFile instruments using a step-down approach. Part 2 of this two-part report describes the efficacy of the instruments in terms of prevalence of canal aberrations, the amount and direction of canal transportation and the overall postoperative shape. No zips, perforations or danger zones were created although 24 specimens (60%) had ledges on the outer wall of the canal. The incidence of ledges differed significantly (P < 0.001) between the canal shapes. At specific points along the canal length there were highly significant differences (P < 0.001) in total canal width and in the amount of material removed from the inner and outer aspects of the curve between the various canal shapes. Overall, 40 degrees canals were wider than 20 degrees canals and canals with curves which began 8 mm from the orifice were wider than 12 mm canals. The direction of canal transportation at the end-point of preparation was balanced between inner and outer in the 8 mm canals, but more often towards the outer in the 12 mm canals. At the apex of the curve, transportation was invariably towards the outer aspect of the curvature. At the beginning of the curve, transportation was more balanced between inner and outer. Mean absolute transportation, ignoring direction, was generally greater in 40 degrees canals and in those with the curve beginning 8 mm from the orifice. Of particular importance was the finding that excessive resin was removed from the outer aspect of the canal at the apex of the curve which was often associated with irregular widened areas or ledges. This is in contrast to the pattern of tissue removal found with stainless steel hand instruments where more resin is removed from the inner aspect of the

  7. Connecting faint-end slopes of the Lyman α emitter and Lyman-break galaxy luminosity functions

    NASA Astrophysics Data System (ADS)

    Gronke, M.; Dijkstra, M.; Trenti, M.; Wyithe, S.

    2015-05-01

    We predict Lyman α (Lyα) luminosity functions (LFs) of Lyα-selected galaxies (Lyα emitters, or LAEs) at z = 3-6 using the phenomenological model. This model combines observed UV-LFs of Lyman-break galaxies (LBGs, or drop-out galaxies), with constraints on their distribution of Lyα line strengths as a function of UV-luminosity and redshift. Our analysis shows that while Lyα LFs of LAEs are generally not Schechter functions, these provide a good description over the luminosity range of log10(Lα/erg s-1) = 41-44. Motivated by this result, we predict Schechter function parameters at z = 3-6. Our analysis further shows that (i) the faint-end slope of the Lyα LF is steeper than that of the UV-LF of LBGs, (with a median αLyα < -2.0 at z ≳ 4), and (ii) a turnover in the Lyα LF of LAEs at Lyα luminosities 1040 ≲ Lα ≲ 1041 erg s-1 may signal a flattening of UV-LF of LBGs at -12 > MUV > -14. We discuss the implications of these results - which can be tested directly with upcoming surveys - for the Epoch of Reionization.

  8. Monte Carlo treatment of Lyman-alpha radiation in a plane-parallel atmosphere.

    NASA Technical Reports Server (NTRS)

    Modali, S. B.; Brandt, J. C.; Kastner, S. O.

    1972-01-01

    A Monte Carlo technique involving Stokes vectors is used to obtain the state of polarization and intensity of solar Lyman-alpha photons as they diffuse through a plane-parallel homogeneous model of earth's hydrogen envelope. Fine structure of Lyman-alpha and Doppler redistribution of frequencies are taken into account. Comparison of the results with Heath's observed upper limit for polarization of 1.5 per cent implies an optical thickness tau greater than 7 and intensities of 8-10 kilorayleighs for a solar Lyman-alpha flux of 5.8 ergs per sq cm per sec.

  9. The Lyman alpha reference sample. II. Hubble space telescope imaging results, integrated properties, and trends

    SciTech Connect

    Hayes, Matthew; Östlin, Göran; Duval, Florent; Sandberg, Andreas; Guaita, Lucia; Melinder, Jens; Rivera-Thorsen, Thøger; Adamo, Angela; Schaerer, Daniel; Verhamme, Anne; Orlitová, Ivana; Mas-Hesse, J. Miguel; Otí-Floranes, Héctor; Cannon, John M.; Pardy, Stephen; Atek, Hakim; Kunth, Daniel; Laursen, Peter; Herenz, E. Christian

    2014-02-10

    We report new results regarding the Lyα output of galaxies, derived from the Lyman Alpha Reference Sample, and focused on Hubble Space Telescope imaging. For 14 galaxies we present intensity images in Lyα, Hα, and UV, and maps of Hα/Hβ, Lyα equivalent width (EW), and Lyα/Hα. We present Lyα and UV radial light profiles and show they are well-fitted by Sérsic profiles, but Lyα profiles show indices systematically lower than those of the UV (n ≈ 1-2 instead of ≳ 4). This reveals a general lack of the central concentration in Lyα that is ubiquitous in the UV. Photometric growth curves increase more slowly for Lyα than the far ultraviolet, showing that small apertures may underestimate the EW. For most galaxies, however, flux and EW curves flatten by radii ≈10 kpc, suggesting that if placed at high-z only a few of our galaxies would suffer from large flux losses. We compute global properties of the sample in large apertures, and show total Lyα luminosities to be independent of all other quantities. Normalized Lyα throughput, however, shows significant correlations: escape is found to be higher in galaxies of lower star formation rate, dust content, mass, and nebular quantities that suggest harder ionizing continuum and lower metallicity. Six galaxies would be selected as high-z Lyα emitters, based upon their luminosity and EW. We discuss the results in the context of high-z Lyα and UV samples. A few galaxies have EWs above 50 Å, and one shows f{sub esc}{sup Lyα} of 80%; such objects have not previously been reported at low-z.

  10. Two Lensed Lyman-α Emitting Galaxies at z~ 5

    NASA Astrophysics Data System (ADS)

    Bayliss, Matthew B.; Wuyts, Eva; Sharon, Keren; Gladders, Michael D.; Hennawi, Joseph F.; Koester, Benjamin P.; Dahle, Håkon

    2010-09-01

    We present observations of two strongly lensed z ~ 5 Lyman-α emitting galaxies that were discovered in the Sloan Giant Arcs Survey (SGAS). We identify the two sources as SGAS J091541+382655 at z = 5.200 and SGAS J134331+415455 at z = 4.994. We measure their AB magnitudes at (i, z) = (23.34 ± 0.09, 23.29 ± 0.13) mag and (i, z) = (23.78 ± 0.18, 24.24+0.18 -0.16) mag and the rest-frame equivalent widths of the Lyman-α emission at 25.3 ± 4.1 Å and 135.6 ± 20.3 Å for SGAS J091541+382655 and SGAS J134331+415455, respectively. Each source is strongly lensed by a massive galaxy cluster in the foreground, and the magnifications due to gravitational lensing are recovered from strong lens modeling of the foreground lensing potentials. We use the magnification to calculate the intrinsic, unlensed Lyman-α and UV continuum luminosities for both sources, as well as the implied star formation rates. We find SGAS J091541+382655 and SGAS J134341+415455 to be galaxies with (L Ly-α, L UV) <= (0.6 L* Ly-α, 2 L*UV) and (L Ly-α, L UV) = (0.5 L* Ly-α, 0.9 L*UV), respectively. Comparison of the spectral energy distributions of both sources against stellar population models produces estimates of the mass in young stars in each galaxy; we report an upper limit of M stars <= 7.9+3.7 -2.5 × 107 M sun h -1 0.7 for SGAS J091531+382655 and a range of viable masses for SGAS J134331+415455 of 2 × 108 M sun h -1 0.7< M stars < 6 × 109 M sun h -1 0.7. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência e Tecnologia (Brazil) and Ministerio de Ciencia, Tecnología e Innovaci

  11. Analysis of solar Lyman-alpha scattering in the heliosphere

    NASA Astrophysics Data System (ADS)

    Fayock, Brian

    Computational models of the global heliospheric interaction with the local interstellar medium have evolved to include very fine and complex physical details. While these models began from theory, the observations and measurements of various spacecraft have been able to provide comparisons to simulations over time, resulting in corrections, adjustments, or additions to certain aspects, and thus a better understanding of the problem. One aspect of great interest is the interaction of neutral hydrogen within the heliosphere. Its inclusion into models is quite complex and still in need of verification. The results of our model are able to provide such a verification. With an interest in neutral hydrogen, Pioneer 10, Voyager 1, and Voyager 2 can provide a relative measure of the local density of hydrogen at the location of the spacecraft by means of Lyman-alpha intensity observations. Their continuous collection of data at increasing radii has revealed trends of decreasing intensity that can be analyzed and compared with radiative transfer simulations performed on neutral hydrogen distributions resulting from the global heliospheric models. Many simulations have been developed in the past, but none has been able to provide results that match the long-term trend, until now. This thesis describes the analysis of Lyman-alpha radiation in the heliosphere by means of a new three-dimensional Monte Carlo radiative transfer technique applied to the background neutral hydrogen distribution provided by a state-of-the-art three-dimensional magnetohydrodynamic-neutral kinetic model, both of which have been developed within the Center for Space Plasma and Aeronomic Research at the University of Alabama in Huntsville. The results of backscatter intensity are compared directly to previously reduced Pioneer 10, Voyager 1, and Voyager 2 ultraviolet data sets, which describe the anti-solar intensity of Lyman-alpha radiation out to almost 50 astronomical units. The similarity between the

  12. The dependence of modeled OI 1356 and N2 Lyman Birge Hopfield auroral emissions on the neutral atmosphere

    NASA Technical Reports Server (NTRS)

    Germany, G. A.; Torr, M. R.; Richards, P. G.; Torr, D. G.

    1990-01-01

    The sensitivity of selected auroral emissions to anticipated changes in the neutral atmosphere was investigated from the results of a series of sensitivity studies conducted using an auroral emission code developed by Richards and Torr (1990). In particular, the behavior of OI 1356 and two Lyman Birge Hopfield (LBH) bands and their ratios to each other with changing atmospheric composition was examined. It was found that, for anticipated average uncertainties in the neutral atmosphere (factor 2 at auroral altitudes), the resultant change in the modeled intensities is comparable to or less than the uncertainty in the neutral atmosphere. The variation in the I 1356/I 1838 ratio over the equivalent of a solar cycle is less than 50 percent, and the summer-to-winter changes are approximately a factor of 2.

  13. Towards physics responsible for large-scale Lyman-α forest bias parameters

    NASA Astrophysics Data System (ADS)

    Cieplak, Agnieszka M.; Slosar, Anže

    2016-03-01

    Using a series of carefully constructed numerical experiments based on hydrodynamic cosmological SPH simulations, we attempt to build an intuition for the relevant physics behind the large scale density (bδ) and velocity gradient (bη) biases of the Lyman-α forest. Starting with the fluctuating Gunn-Peterson approximation applied to the smoothed total density field in real-space, and progressing through redshift-space with no thermal broadening, redshift-space with thermal broadening and hydrodynamically simulated baryon fields, we investigate how approximations found in the literature fare. We find that Seljak's 2012 analytical formulae for these bias parameters work surprisingly well in the limit of no thermal broadening and linear redshift-space distortions. We also show that his bη formula is exact in the limit of no thermal broadening. Since introduction of thermal broadening significantly affects its value, we speculate that a combination of large-scale measurements of bη and the small scale flux PDF might be a sensitive probe of the thermal state of the IGM. We find that large-scale biases derived from the smoothed total matter field are within 10-20% to those based on hydrodynamical quantities, in line with other measurements in the literature.

  14. Towards physics responsible for large-scale Lyman-α forest bias parameters

    DOE PAGESBeta

    Agnieszka M. Cieplak; Slosar, Anze

    2016-03-08

    Using a series of carefully constructed numerical experiments based on hydrodynamic cosmological SPH simulations, we attempt to build an intuition for the relevant physics behind the large scale density (bδ) and velocity gradient (bη) biases of the Lyman-α forest. Starting with the fluctuating Gunn-Peterson approximation applied to the smoothed total density field in real-space, and progressing through redshift-space with no thermal broadening, redshift-space with thermal broadening and hydrodynamically simulated baryon fields, we investigate how approximations found in the literature fare. We find that Seljak's 2012 analytical formulae for these bias parameters work surprisingly well in the limit of no thermalmore » broadening and linear redshift-space distortions. We also show that his bη formula is exact in the limit of no thermal broadening. Since introduction of thermal broadening significantly affects its value, we speculate that a combination of large-scale measurements of bη and the small scale flux PDF might be a sensitive probe of the thermal state of the IGM. Lastly, we find that large-scale biases derived from the smoothed total matter field are within 10–20% to those based on hydrodynamical quantities, in line with other measurements in the literature.« less

  15. Lyman-α Spectra from Multiphase Outflows, and their Connection to Shell Models

    NASA Astrophysics Data System (ADS)

    Gronke, M.; Dijkstra, M.

    2016-07-01

    We perform Lyman-α (Lyα) Monte-Carlo radiative transfer calculations on a suite of 2500 models of multiphase, outflowing media, which are characterized by 14 parameters. We focus on the Lyα spectra emerging from these media and investigate which properties are dominant in shaping the emerging Lyα profile. Multiphase models give rise to a wide variety of emerging spectra, including single-, double-, and triple-peaked spectra. We find that the dominant parameters in shaping the spectra include (i) the cloud covering factor, f c , which is in agreement with earlier studies, and (ii) the temperature and number density of residual H i in the hot ionized medium. We attempt to reproduce spectra emerging from multiphase models with “shell models” which are commonly used to fit observed Lyα spectra, and investigate the connection between shell-model parameters and the physical parameters of the clumpy media. In shell models, the neutral hydrogen content of the shell is one of the key parameters controlling Lyα radiative transfer. Because Lyα spectra emerging from multiphase media depend much less on the neutral hydrogen content of the clumps, the shell-model parameters such as H i column density (but also shell velocity and dust content) are generally not well matched to the associated physical parameters of the clumpy media.

  16. Gas kinematics of Lyman Alpha Blobs at z=2-3

    NASA Astrophysics Data System (ADS)

    Yang, Yujin

    2015-08-01

    High-redshift Lyman alpha nebulae (Ly-alpha "blobs", LABs) are the site of massive galaxy formation and their early interaction with the intergalactic medium. Research in the past decade has struggled to make progress on the question of what powers these huge Ly-alpha halos and whether the Ly-alpha-emitting gas is outflowing or infalling. First, I will present our optical and NIR spectroscopic observations for the Ly-alpha and the redshifted nebular emission lines such as [OII], [OIII] and Halpha. Using three independent measures --- the velocity offset between the Ly-alpha line and the nonresonant [O III] or Halpha line, the offset of stacked interstellar metal absorption lines, and the spectrally resolved [O III] line profile --- we study the kinematics of gas along the line of sight to galaxies within each blob center. All these kinematic measures show that there are only weak outflows, therefore excluding gas inflows and extreme hyper/superwinds as a source of the extended Ly-alpha emission. I will also present the first detection of molecular gas from a Ly-alpha blob and our on-going effort to characterize the physical conditions of its ISM. The large velocity gradient (LVG) modeling using PdBI observations of CO(3-2), CO(5-4), CO(7-6), CI(2-1) lines suggests that two-phase medium is required to explain the blob's CO SEDs and dust continuum.

  17. Properties of Lyman-alpha Absorbers at High-Redshift

    NASA Astrophysics Data System (ADS)

    Peroux, C.

    2001-09-01

    In recent years, an extremely successful method to observationally study early stages of galaxy formation has been provided by the study of quasar absorbers. Quasar absorption lines are systems intercepting our line-of-sight to a given quasar and thus produce a feature in the quasar spectrum. Damped Lyman-α systems (hereafter DLAs) have N (H I) > 2 × 1020 atoms cm-2, and were originally thought to be the precursors of present day disk galaxies but there is evidence that they may be dominated by gas-rich proto-dwarf galaxies representing the basic building blocks of hierarchical growth of structure. Since their detection is independent of their size, shape, and covering factor, they provide a unbiased method with which to study early galaxies. DLAs are a subset of Lyman-limit Systems (hereafter LLS) which have hydrogen column densities N (H I) > 1.6 × 1017 atoms cm-2. At z < 1, they are probably associated with galactic halos. Finally, the Lyman-α forest is composed of many small column density systems ranging from N (H I) =1012 to 1.6 × 1017 atoms cm-2. This thesis presents a sample of 66 bright z ⪆ 4 quasars observed with the 4 m Cerro Tololo Inter-American Observatory telescope and the 4.2 m William Hershel telescope. The first part of the study concentrates on the quasars themselves via the fitting of quasar continua and the measurement of continuum depression parameters characterising the mean absorption across the Lyman-α forest. The quasar spectra are then analysed to investigate the absorption systems they contain. This led to the discovery of 26 new DLAs, 34 LLS and many associated metal lines which enables the analysis of the evolution of the column density distribution, f(N,z), and the total mass in high-column density neutral hydrogen quasar absorbers. The observed number of LLS per unit redshift is used to constrain f(N,z) below the DLA limit in the range N(HI) = 1.6 × 1017 to 2× 1020 atoms cm-2. The joint analysis shows unambiguously that f

  18. Telescope baffle performance for Lyman Far Ultraviolet Spectrographic Explorer

    NASA Astrophysics Data System (ADS)

    Morbey, Christopher; Hutchings, J. B.

    1993-07-01

    The Lyman Far Ultraviolet Spectrographic Explorer telescope is a Wolter type II glancing incidence design with an aperture of 64 cm. Because the spacecraft is required to guide on stars fainter than m(v) = 16, a visible light baffle is necessary to protect the FOV from the stray light that results from out-of-field bright sources. Such a baffle system is described here. Total point-source transmittances are computed for incident beams in the range 0-70 deg. Estimates for background brightness on the detector are made for the contribution from direct sunlight and earthshine. Scattering from the black surfaces of the baffle, the vanes, and diffraction at the structure's edges are taken into consideration.

  19. Integral field observations of damped Lyman-α galaxies

    NASA Astrophysics Data System (ADS)

    Christensen, L.; Sánchez, S. F.; Jahnke, K.; Becker, T.; Kelz, A.; Wisotzki, L.; Roth, M. M.

    2004-02-01

    We report preliminary results from a targeted investigation on quasars containing damped Lyman-α absorption (DLA) lines as well strong metal absorption lines, carried out with the Potsdam Multi Aperture Spectrophotometer (PMAS). We search for line-emitting objects at the same redshift as the absorption lines and close to the line of sight of the QSOs. We have observed and detected the already confirmed absorbing galaxies in Q2233+131 (zabs=3.15) and Q0151+045 (zabs=0.168), while failing to find spectral signatures for the z=0.091 absorber in Q0738+313. From the Q2233+131 DLA galaxy, we have detected extended Lyα emission from an area of 3″×5″.

  20. Copernicus observations of interstellar absorption at Lyman alpha

    NASA Technical Reports Server (NTRS)

    Bohlin, R. C.

    1975-01-01

    Column densities NH of atomic hydrogen have been derived for 40 OB stars from spectral scans at Lyman alpha obtained by the Copernicus (OAO-3) satellite. The stars are all between 60 and 1100 pc away with a range of mean densities n sub H of 0.01 to 2.5 atoms cm-3. The gas to color-excess ratio in clouds varies from 1 to 3 times the mean outside of clouds. The presence of molecular hydrogen correlates with E(B-V), but the best tracer for H2 is atomic hydrogen. The mean density of the gas for all 40 stars is much smaller than the mean of 0.7 atoms cm-3 obtained from 21-cm observations, because the brightest stars with less than average amounts of matter in the line of sight were selected for observation.

  1. Optical design of Lyman/FUSE. [Far UV Spectroscopic Explorer

    NASA Technical Reports Server (NTRS)

    Content, D. A.; Davila, P. M.; Osantowski, J. F.; Saha, T. T.; Wilson, M. E.

    1990-01-01

    The optical system for the proposed Lyman/Far UV Spectroscopic Explorer (FUSE) orbiting observatory is described and illustrated with drawings and graphs of predicted performance. The system comprises (1) an FUV channel based on a 1.84-m-diameter Rowland circle spectrograph with five high-density modified ellipsiodal near-normal-incidence gratings and an array of four MAMA detectors; (2) an EUV channel with ellipsoidal mirror, planar varied-line-space grating, microchannel-plate array, and wedge-and-strip anode detector; (3) a 70-cm Wolter II glancing-incidence telescope; and (4) a CCD-detector fine-error sensor to provide accurate pointing (within 200 marcsec rms). The resolving powers of the spectrographs are 30,000 in the FUV and 300-600 (wavelength-dependent) in the EUV.

  2. A model for the disc Lyman alpha emission of Uranus

    NASA Technical Reports Server (NTRS)

    Ben Jaffel, L.; Prange, R.; Emerich, C.; Vidal-Madjar, A.; Mcconnell, J. C.

    1991-01-01

    A new efficient radiative transfer algorithm for nonhomogeneous model atmospheres has been applied to the Uranian atmosphere. The contribution of the scatter solar Lyman-alpha to the Uranain emission is of the order of 300 R, and the Rayleigh contribution may reach 450 R for small values of the eddy diffusion coefficient (EDC). The total solar contribution may then reach about 750 R for a solar flux of 2.5 x 10 to the 11th photons/sq cm/s/A. A level of up to 400 R is confirmed in some directions for the interstellar wind contribution. The values of the atmospheric EDC necessary to mimic the observations are 50-100 sq cm/s. A small additional source located on the dayside Uranian atmosphere seems necessary correctly to fit the shape of the limb to limb intensity variation, especially near the limbs. Its contribution to the emergent intensity would range from 100 to 500 R.

  3. Spacelab Lyman Alpha-White Light Coronagraph Program

    NASA Technical Reports Server (NTRS)

    Kohl, J. L.

    1986-01-01

    The Spacelab Lyman Alpha Coronagraph (SLAC) of the Smithsonian Astrophysical Observatory (SAO) and the White Light Coronagraph (WLC) to be provided by the High Altitude Observatory (HAO) are two separate coronagraphs which would be operated in a joint fashion during Spacelab missions to be flown by the Space Shuttle. The two instruments would be used to perform joint observations of solar coronal structures from 1.2 to 8.0 solar radii from sun-center in vacuum ultraviolet and visible radiations. Temperatures, densities, and flow velocities throughout the solar wing acceleration region of the inner solar corona were measured. The Phase I Definition activity resulted in the successful definition and preliminary design of the experiment/instrumentation subsystem and associated software, ground support equipment and interfaces to the extended required to accurately estimate the scope of the investigation and prepare an Investigational Development Plan; the performance of the necessary functional, operations, and safety analyses necessary to complete the Experiment Requirements document.

  4. Equilibrium slab models of Lyman-alpha clouds

    NASA Technical Reports Server (NTRS)

    Charlton, Jane C.; Salpeter, Edwin E.; Hogan, Craig J.

    1993-01-01

    Solutions for the equilibrium configuration of a slab with ionizing radiation incident equally from both sides are explored. Radiation effects (photoionization, Ly-alpha photon trapping, and mock gravity) as well as external pressure and self gravity (with and without dark matter) are included. The general formalism is applied to structure growth on small scales at very high z due to mock gravity on dust. Emphasis is placed on the application of slab models at z of less than 5, particularly those that may correspond to Ly-alpha forest, Lyman limit, and damped Ly-alpha systems. The regime with a dominant outward force contributed by trapping of Ly-alpha photons is discussed. General expressions are given for the equilibrium, including dark matter, assuming various relationships between the density of the dark matter halo and the total gas column density.

  5. Stellar Lyman-alpha emission and the local interstellar medium

    NASA Technical Reports Server (NTRS)

    Landsman, Wayne; Simon, Theodore

    1991-01-01

    The UV spectra now available in the IUE archives have been systematically searched for the presence of Lyman-alpha emission in late-type stars. The results provide the first survey of the behavior of the Ly-alpha emission line across most of the cool half of the H-R diagram. The normalized Ly-alpha emission flux is strongest in the chromospherically active RS CVn stars and in the dMe stars. The range of normalized flux values is much smaller among F-type stars than in stars of later spectral type. A dropoff appears in the flux levels of stars at B-V less than 0.30 mag. The measurements are used to search for evidence of possible high column density clouds in the local ISM. The cloud previously identified toward Alpha Oph may be seen in the reduced flux observed toward Beta Oph.

  6. SubLymE: The Sub-Lyman α Explorer

    NASA Astrophysics Data System (ADS)

    Green, James C.; France, Kevin

    2015-01-01

    The Sub-Lyman α Explorer (SubLymE) is a proposed Small Explorer mission. It will provide multi-color imaging in the 102 - 120 nm spectral window with 2 arc second resolution and a field of view of 7 arc minutes. Arc second class astronomical imaging has never been done in this bandpass previously. SubLymE will enable a host of previously impossible astronomical observations but its optical design and operational planning have been optimized around these key projects. 1) Directly measure the Lyman continuum flux from low-redshift galaxies to quantify the mean fesc and determine the stellar contribution to the ionization of the intergalactic medium during the epoch of re-ionization and the modern universe. 2) Conduct a deep survey of local galaxies to identify and quantify the role of O stars in their energy-mass and chemical cycles and their interaction with the circumgalactic medium. 3) Map star forming regions in the Milky Way and Magellanic clouds to understand the physics in their proto-planetary disks at the distances ( < 10 AU) which will become their future habitable zones. 4) Observe all local K and M dwarfs known to host exo-planets to quantify the ultraviolet environment in which their planetary atmospheres must exist. 5) Map the energetics of supernova remnants in the primary cooling line of hot gas (O VI 103.2 nm) to quantify their contributions to the mass-energy-chemical cycles in galaxies . Following the completion of the planned surveys, we propose an ongoing guest observer program for SubLymE.

  7. The properties of Lyman break galaxies at z~ 5

    NASA Astrophysics Data System (ADS)

    Bremer, M. N.; Lehnert, M. D.; Waddington, I.; Hardcastle, M. J.; Boyce, P. J.; Phillipps, S.

    2004-01-01

    In a recent paper, Lehnert & Bremer have photometrically selected a sample of Lyman break galaxies at z > 4.8 from a single VLT/FORS2 pointing and spectroscopically confirmed half of them to be at 4.8 < z < 5.8. To study the properties of such galaxies further, we have photometrically selected a similar sample (VAB > 28, iAB < 26.3, iAB-zAB > 0) from the Hubble Space Telescope Advanced Camera for Surveys (HST ACS) images of the Chandra Deep Field-South. This selection results in a sample of 44 sources from ~150 arcmin2. We find that such galaxies are often barely resolved in the ACS images, having half-light radii of 0.1-0.3 arcsec (<2 kpc). They show no difference in spatial clustering from sources selected by iAB < 26.3, iAB-zAB > 0, which are generally galaxies of lower redshift. However, their distribution over the field is not uniform and their surface density varies considerably over areas comparable to a single 8-m or HST pointing. A reliable determination of the surface and volume densities of such galaxies requires a sky area considerably larger than the current ACS imaging of this field. No individual Lyman break candidate was detected to a 3σ limit of 6 × 10-17 erg s-1 cm-2 at 0.5-5 keV by Chandra (a limiting luminosity of below 2 × 1043 erg s-1 at z~ 5.3). By summing over all positions, we find that the mean source must be undetected at a level at least a factor of 4 times fainter than this. This rules out anything other than a weak active galactic nucleus (AGN) contribution to the emission from these objects; we conclude that luminous AGNs made little contribution to the final stages of re-ionization of the Universe.

  8. Mapping High-Velocity H-alpha and Lyman-alpha Emission from Supernova 1987A

    NASA Technical Reports Server (NTRS)

    France, Kevin; McCray, Richard; Fransson, Claes; Larsson, Josefin; Frank, Kari A.; Burrows, David N.; Challis, Peter; Kirshner, Robert P.; Chevalier, Roger A.; Garnavich, Peter; Heng, Kevin; Lawrence, Stephen S.; Lundqvist, Peter; Smith, Nathan; Sonneborn, George

    2015-01-01

    We present new Hubble Space Telescope images of high-velocity H-alpha and Lyman-alpha emission in the outer debris of SN 1987A. The H-alpha images are dominated by emission from hydrogen atoms crossing the reverse shock. For the first time we observe emission from the reverse shock surface well above and below the equatorial ring, suggesting a bipolar or conical structure perpendicular to the ring plane. Using the H-alpha imaging, we measure the mass flux of hydrogen atoms crossing the reverse shock front, in the velocity intervals (-7,500 < V(sub obs) < -2,800 km/s) and (1,000 < V(sub obs) < 7,500 km/s), ?M(sub H) = 1.2 × 10(exp -3) M/ y. We also present the first Lyman-alpha imaging of the whole remnant and new Chandra X-ray observations. Comparing the spatial distribution of the Lyman-alpha and X-ray emission, we observe that the majority of the high-velocity Lyman-alpha emission originates interior to the equatorial ring. The observed Lyman-alpha/H-alpha photon ratio, R(L-alpha/H-alpha) approx. = 17, is significantly higher than the theoretically predicted ratio of approx. = 5 for neutral atoms crossing the reverse shock front. We attribute this excess to Lyman-alpha emission produced by X-ray heating of the outer debris. The spatial orientation of the Lyman-alpha and X-ray emission suggests that X-ray heating of the outer debris is the dominant Lyman-alpha production mechanism in SN 1987A at this phase in its evolution.

  9. Copernicus measurement of the Jovian Lyman-alpha emission and its aeronomical significance

    NASA Technical Reports Server (NTRS)

    Atreya, S. K.; Kerr, R. B.; Upson, W. L., II; Festou, M. C.; Donahue, T. M.; Barker, E. S.; Cochran, W. D.; Bertaux, J. L.

    1982-01-01

    It is pointed out that the intensity of the Lyman-alpha emission is a good indicator of the principal aeronomical processes on the major planets. The high-resolution ultraviolet spectrometer aboard the Orbiting Astronomical Observatory Copernicus was used in 1980 April and May to detect the Jovian Lyman-alpha emission by spectroscopically discriminating it from other Doppler shifted Lyman-alpha emissions such as those of the geocorona, and the interplanetary medium. Taking into consideration the reported emission data, it appears that an unusually large energy input due to the particle precipitation in the auroral region must have been responsible for the large observed Lyman-alpha intensity during the Voyager encounter. At most other times, the observed Jovian Lyman-alpha intensity can be explained, within the range of statistical uncertainty, by a model that takes into consideration the solar EUV flux, the solar Lyman-alpha flux, the high exospheric temperature, and the eddy diffusion coefficient without energy input from the auroral sources.

  10. Response of the low ionosphere to X-ray and Lyman-α solar flare emissions

    NASA Astrophysics Data System (ADS)

    Raulin, Jean-Pierre; Trottet, GéRard; Kretzschmar, Matthieu; Macotela, Edith L.; Pacini, Alessandra; Bertoni, Fernando C. P.; Dammasch, Ingolf E.

    2013-01-01

    Using soft X-ray measurements from detectors onboard the Geostationary Operational Environmental Satellite (GOES) and simultaneous high-cadence Lyman-α observations from the Large Yield Radiometer (LYRA) onboard the Project for On-Board Autonomy 2 (PROBA2) ESA spacecraft, we study the response of the lower part of the ionosphere, the D region, to seven moderate to medium-size solar flares that occurred in February and March of 2010. The ionospheric disturbances are analyzed by monitoring the resulting sub-ionospheric wave propagation anomalies detected by the South America Very Low Frequency (VLF) Network (SAVNET). We find that the ionospheric disturbances, which are characterized by changes of the VLF wave phase, do not depend on the presence of Lyman-α radiation excesses during the flares. Indeed, Lyman-α excesses associated with flares do not produce measurable phase changes. Our results are in agreement with what is expected in terms of forcing of the lower ionosphere by quiescent Lyman-α emission along the solar activity cycle. Therefore, while phase changes using the VLF technique may be a good indicator of quiescent Lyman-α variations along the solar cycle, they cannot be used to scale explosive Lyman-α emission during flares.

  11. The Deepest Spectrum in the Universe? Line Emission from Lyman-alpha Clouds at z 3

    NASA Astrophysics Data System (ADS)

    Bunker, Andrew J.; Rauch, M.; Haehnelt, M.; Becker, G.; Marleau, F.; Graham, J.; Research, European; Inter-Galactic Medium, Training Network on the

    2007-12-01

    We present the results of an extremely deep long-slit optical spectroscopic search for low-luminosity Lyman-alpha emitters. Over several years we have accumulated 150-hours integration on a single field with 8-10m telescopes (VLT/FORS2, Gemini/GMOS and Keck/LRIS) at a spectral resolution of 300km/s. This is the deepest spectrum ever obtained - our 1 sigma sensitivity to line emission in a 1 arcsec2 aperture is 1019erg/cm2/s. We have significant detections of 30 emission line objects, which are most likely Lyman-alpha emitters at 2.7Lyman continuum background. Many of the line emitters are significantly spatially extended (with median size 4arcsec, 30kpc) and could plausibly be the host population of the high column density Lyman-alpha absorption clouds seen in QSO spectra (the Damped Lyman-alpha Systems and the Lyman-Limit Systems).

  12. An extreme O III emitter at z=3.2: a low metallicity Lyman continuum source

    NASA Astrophysics Data System (ADS)

    de Barros, S.; Vanzella, E.

    2015-12-01

    We investigate the physical properties of a Lyman continuum emitter candidate at z=3.212 with photometric coverage from U to MIPS 24μm band and VIMOS/VLT and MOSFIRE/Keck spectroscopy. Investigation of the UV spectrum confirms a direct spectroscopic detection of the Lyman continuum emission with S/N>5. Non-zero Lyα flux at the systemic redshift and high Lyman-α escape fraction suggest a low HI column density. The weak C and Si low-ionization absorption lines are also consistent with a low covering fraction along the line of sight. The O IIIdoub+Hβ equivalent width is one of the largest reported for a galaxy at z>3 (EW(O IIIdoub+Hβ)} ≃q 1600Å, rest-frame; 6700Å observed-frame) and the NIR spectrum shows that this is mainly due to an extremely strong [OIII] emission. The large observed O III/O II ratio (>10) and high ionization parameter are consistent with prediction from photoionization models in case of a density-bounded nebula scenario. This source is currently the first high-z example of a Lyman continuum emitter exhibiting indirect and direct evidences of a Lyman continuum leakage and having physical properties consistent with theoretical expectation from Lyman continuum emission from a density-bounded nebula.

  13. The impact of different physical processes on the statistics of Lyman-limit and damped Lyman α absorbers

    NASA Astrophysics Data System (ADS)

    Altay, Gabriel; Theuns, Tom; Schaye, Joop; Booth, C. M.; Dalla Vecchia, Claudio

    2013-12-01

    We compute the z = 3 neutral hydrogen column density distribution function f(NHI) for 19 simulations drawn from the Overwhelmingly Large Simulations project using a post-processing correction for self-shielding calculated with full radiative transfer of the ionizing background radiation. We investigate how different physical processes and parameters affect the abundance of Lyman-limit systems (LLSs) and damped Lyman α absorbers including: (i) metal-line cooling; (ii) the efficiency of feedback from supernovae and active galactic nuclei; (iii) the effective equation of state for the interstellar medium; (iv) cosmological parameters; (v) the assumed star formation law and (vi) the timing of hydrogen reionization. We find that the normalization and slope, D = d log _{10} f /d log _{10} N_{H I}, of f(NHI) in the LLS regime are robust to changes in these physical processes. Among physically plausible models, f(NHI) varies by less than 0.2 dex and D varies by less than 0.18 for LLSs. This is primarily due to the fact that these uncertain physical processes mostly affect star-forming gas which contributes less than 10 per cent to f(NHI) in the LLS column density range. At higher column densities, variations in f(NHI) become larger (approximately 0.5 dex at f(NHI) = 1022 cm-2 and 1.0 dex at f(NHI) = 1022 cm-2) and molecular hydrogen formation also becomes important. Many of these changes can be explained in the context of self-regulated star formation in which the amount of star-forming gas in a galaxy will adjust such that outflows driven by feedback balance inflows due to accretion. Tools to reproduce all figures in this work can be found at the following url: https://bitbucket.org/galtay/hi-cddf-owls-1

  14. The Lyman alpha reference sample. III. Properties of the neutral ISM from GBT and VLA observations

    SciTech Connect

    Pardy, Stephen A.; Cannon, John M.; Melinder, Jens E-mail: jcannon@macalester.edu; and others

    2014-10-20

    We present new H I imaging and spectroscopy of the 14 UV-selected star-forming galaxies in the Lyman Alpha Reference Sample (LARS), aimed for a detailed study of the processes governing the production, propagation, and escape of Lyα photons. New H I spectroscopy, obtained with the 100 m Green Bank Telescope (GBT), robustly detects the H I spectral line in 11 of the 14 observed LARS galaxies (although the profiles of two of the galaxies are likely confused by other sources within the GBT beam); the three highest redshift galaxies are not detected at our current sensitivity limits. The GBT profiles are used to derive fundamental H I line properties of the LARS galaxies. We also present new pilot H I spectral line imaging of five of the LARS galaxies obtained with the Karl G. Jansky Very Large Array (VLA). This imaging localizes the H I gas and provides a measurement of the total H I mass in each galaxy. In one system, LARS 03 (UGC 8335 or Arp 238), VLA observations reveal an enormous tidal structure that extends over 160 kpc from the main interacting systems and that contains >10{sup 9} M {sub ☉} of H I. We compare various H I properties with global Lyα quantities derived from Hubble Space Telescope measurements. The measurements of the Lyα escape fraction are coupled with the new direct measurements of H I mass and significantly disturbed H I velocities. Our robustly detected sample reveals tentative correlations between the total H I mass and linewidth, and key Lyα tracers. Further, on global scales, these data support a complex coupling between Lyα propagation and the H I properties of the surrounding medium.

  15. Latitudinal structure and north-south asymmetry of the solar wind from Lyman-alpha remote sensing by SWAN

    NASA Astrophysics Data System (ADS)

    Bzowski, M.; Mäkinen, T.; Kyrölä, E.; Summanen, T.; Quémerais, E.

    2003-09-01

    Based on SWAN/SOHO observations carried out during 1996-2002, we analyze latitudinal profiles of the heliospheric backscatter Lyman-alpha radiation. We use these results to investigate the ionization field of neutral hydrogen in the inner heliosphere and the latitudinal distribution of the solar wind mass flux. The the depth and latitudinal range of the equatorial depression in the Lyman-alpha backscatter glow (the so-called ``groove'') are correlated with the corresponding parameters of the ionization field. We show that the groove is entirely due to latitudinal anisotropy of the solar wind, since, as we are able to demonstrate, the photoionization rate remains spherically symmetric throughout the solar cycle. During the last solar minimum the groove was well developed and stable. During the ascending phase of solar activity, it expanded in latitude (first south, then north), and disappeared altogether during the solar maximum. Shortly after the maximum it reappeared, but its structure was more complex than during the ascending phase. The groove feature is correlated with the equatorial band occupied by the slow solar wind, while the polar maxima of the Lyman-alpha intensity correspond to the fast solar wind from the polar holes. The groove observations (supported by appropriate modeling) show that during the last solar minimum the mass flux of the fast solar wind from the north and south polar holes were different from each other: a true north-south asymmetry between the polar regions was detected. During the solar minimum, the area occupied by the slow solar wind was quite stable and offset slightly to the south with respect to the solar equator: it extended to about 30° N and 35° S from the beginning of observations in May 1996 till 1998. Then it expanded by about 10degr north and south, and subsequently migrated towards southern latitudes, so that it engulfed the south pole in May/June 2000. The north region of the fast wind survived longer and disappeared

  16. Development of Flight Slit-Jaw Optics for Chromospheric Lyman-Alpha SpectroPolarimeter

    NASA Technical Reports Server (NTRS)

    Kubo, Masahito; Suematsu, Yoshinori; Kano, Ryohei; Bando, Takamasa; Hara, Hirohisa; Narukage, Noriyuki; Katsukawa, Yukio; Ishikawa, Ryoko; Ishikawa, Shin-nosuke; Kobiki, Toshihiko; Tsuneta, Saku; Kobayashi, Ken; Winebarger, Amy; Takeyama, Norihide; Kanai, Yoshikazu; Sakakibara, Yoshiko

    2015-01-01

    In sounding rocket experiment CLASP, I have placed a slit a mirror-finished around the focal point of the telescope. The light reflected by the mirror surface surrounding the slit is then imaged in Slit-jaw optical system, to obtain the a-ray Lyman secondary image. This image, not only to use the real-time image in rocket flight rocket oriented direction selection, and also used as a scientific data showing the spatial structure of the Lyman alpha emission line intensity distribution and solar chromosphere around the observation area of the polarimetric spectroscope. Slit-jaw optical system is a two off-axis mirror unit part including a parabolic mirror and folding mirror, Lyman alpha transmission filter, the optical system magnification 1x consisting camera. The camera is supplied from the United States, and the other was carried out fabrication and testing in all the Japanese side. Slit-jaw optical system, it is difficult to access the structure, it is necessary to install the low place clearance. Therefore, influence the optical performance, the fine adjustment is necessary optical elements are collectively in the form of the mirror unit. On the other hand, due to the alignment of the solar sensor in the US launch site, must be removed once the Lyman alpha transmission filter holder including a filter has a different part from the mirror unit. In order to make the structure simple, stray light measures Aru to concentrate around Lyman alpha transmission filter. To overcome the difficulties of performing optical alignment in Lyman alpha wavelength absorbed by the atmosphere, it was planned 'following four steps in order to reduce standing time alignment me. 1. is measured in advance refractive index at Lyman alpha wavelength of Lyman alpha transmission filter (121.567nm), to prepare a visible light Firuwo having the same optical path length in the visible light (630nm).2. The mirror structure CLASP before mounting unit standing, dummy slit and camera standing

  17. Development of Flight Slit-Jaw Optics for Chromospheric Lyman-Alpha SpectroPolarimeter

    NASA Technical Reports Server (NTRS)

    Kubo, Masahito; Suematsu, Yoshinori; Kano, Ryohei; Bando, Takamasa; Hara, Hirohisa; Narukage, Noriyuki; Katsukawa, Yukio; Ishikawa, Ryoko; Ishikawa, Shin-nosuke; Kobiki, Toshihiko; Tsuneta, Saku; Kobayashi, Ken; Winebarger, Amy; Takeyama, Norihide; Kanai, Yoshikazu; Sakakibara, Yoshiko

    2015-01-01

    In sounding rocket experiment CLASP, I have placed a slit a mirror-finished around the focal point of the telescope. The light reflected by the mirror surface surrounding the slit is then imaged in Slit-jaw optical system, to obtain the alpha-ray Lyman secondary image. This image, not only to use the real-time image in rocket flight rocket oriented direction selection, and also used as a scientific data showing the spatial structure of the Lyman alpha emission line intensity distribution and solar chromosphere around the observation area of the polarimetric spectroscope. Slit-jaw optical system is a two off-axis mirror unit part including a parabolic mirror and folding mirror, Lyman alpha transmission filter, the optical system magnification 1x consisting camera. The camera is supplied from the United States, and the other was carried out fabrication and testing in all the Japanese side. Slit-jaw optical system, it is difficult to access the structure, it is necessary to install the low place clearance. Therefore, influence the optical performance, the fine adjustment is necessary optical elements are collectively in the form of the mirror unit. On the other hand, due to the alignment of the solar sensor in the US launch site, must be removed once the Lyman alpha transmission filter holder including a filter has a different part from the mirror unit. In order to make the structure simple, stray light measures Aru to concentrate around Lyman alpha transmission filter. To overcome the difficulties of performing optical alignment in Lyman alpha wavelength absorbed by the atmosphere, it was planned following four steps in order to reduce standing time alignment me. 1: is measured in advance refractive index at Lyman alpha wavelength of Lyman alpha transmission filter (121.567nm), to prepare a visible light Firuwo having the same optical path length in the visible light (630nm). 2: The mirror structure CLASP before mounting unit standing, dummy slit and camera standing

  18. The Lyman alpha reference sample. VII. Spatially resolved Hα kinematics

    NASA Astrophysics Data System (ADS)

    Herenz, Edmund Christian; Gruyters, Pieter; Orlitova, Ivana; Hayes, Matthew; Östlin, Göran; Cannon, John M.; Roth, Martin M.; Bik, Arjan; Pardy, Stephen; Otí-Floranes, Héctor; Mas-Hesse, J. Miguel; Adamo, Angela; Atek, Hakim; Duval, Florent; Guaita, Lucia; Kunth, Daniel; Laursen, Peter; Melinder, Jens; Puschnig, Johannes; Rivera-Thorsen, Thøger E.; Schaerer, Daniel; Verhamme, Anne

    2016-03-01

    We present integral field spectroscopic observations with the Potsdam Multi-Aperture Spectrophotometer of all 14 galaxies in the z ~ 0.1 Lyman Alpha Reference Sample (LARS). We produce 2D line-of-sight velocity maps and velocity dispersion maps from the Balmer α (Hα) emission in our data cubes. These maps trace the spectral and spatial properties of the LARS galaxies' intrinsic Lyα radiation field. We show our kinematic maps that are spatially registered onto the Hubble Space Telescope Hα and Lyman α (Lyα) images. We can conjecture a causal connection between spatially resolved Hα kinematics and Lyα photometry for individual galaxies, however, no general trend can be established for the whole sample. Furthermore, we compute the intrinsic velocity dispersion σ0, the shearing velocity vshear, and the vshear/σ0 ratio from our kinematic maps. In general LARS galaxies are characterised by high intrinsic velocity dispersions (54 km s-1 median) and low shearing velocities (65 km s-1 median). The vshear/σ0 values range from 0.5 to 3.2 with an average of 1.5. It is noteworthy that five galaxies of the sample are dispersion-dominated systems with vshear/σ0< 1, and are thus kinematically similar to turbulent star-forming galaxies seen at high redshift. When linking our kinematical statistics to the global LARS Lyα properties, we find that dispersion-dominated systems show higher Lyα equivalent widths and higher Lyα escape fractions than systems with vshear/σ0> 1. Our result indicates that turbulence in actively star-forming systems is causally connected to interstellar medium conditions that favour an escape of Lyα radiation. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC).The reduced data cubes (FITS files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130

  19. Ultraviolet Continuum of the Quasar PKS 0405-123: Lyman Edge in the Accretion Disk Spectrum

    NASA Astrophysics Data System (ADS)

    Lee, G.; Kriss, G. A.; Davidsen, A. F.; Zheng, W.

    1995-05-01

    We study the characteristics of the ultraviolet continuum of the quasar PKS 0405-123 using the archival HST/FOS spectrum. The spectrum from 1150 to 3300 Angstroms shows a steeply rising continuum in F_λ with a strong absorption feature ~ 100 Angstroms wide around the intrinsic Lyman limit of this z=0.574 quasar. The spectrum also shows Lyman absorption line systems in the wavelength range of the broad absorption feature. A Lyalpha absorption line whose corresponding Lyman limit could contribute to the broad absorption feature is also identified. We investigate the possibility that the broad absorption feature may be due to the sum of the contributions from each Lyman absorption system. The estimated opacity due to the Lyman absorption systems in the region of the broad absorption feature, however, is not high enough to completely account for it. We thus propose that a significant part of the continuum drop in the broad absorption feature may be due to a broadened Lyman edge in the spectrum of an accretion disk. We model the ultraviolet continuum using an alpha -disk with an adiabatic vertical structure. We compute the emitted spectrum by solving the radiative transfer numerically. The observed spectrum is corrected for relativistic effects assuming a Schwarzschild metric, and we also consider the effect of Comptonization by a surrounding hot corona on the observed spectrum. A realistic disk spectrum with a significant amount of Comptonization describes the steep continuum shape and the broad Lyman edge feature, and it is consistent with the X-ray flux observed with EINSTEIN observatory IPC. This work was supported by NASA Grant NAG 5-1630 to the FOS team and NASA contract NAS 5-27000 to the Johns Hopkins University.

  20. SIZING UP Ly{alpha} AND LYMAN BREAK GALAXIES

    SciTech Connect

    Malhotra, Sangeeta; Rhoads, James E.; McLinden, Emily; Finkelstein, Steven L.; Hathi, Nimish; Nilsson, Kim; Pirzkal, Norbert

    2012-05-10

    We measure the sizes for a sample of 174 Ly{alpha}-selected galaxies with broadband imaging with the Hubble Space Telescope. Over the redshift range 2.25 < z < 6, Ly{alpha}-selected galaxies have a characteristic, constant, small size in rest-frame ultraviolet (UV) light. Coupled with a characteristic star formation intensity (i.e., UV luminosity per unit area), this can explain their non-evolving ultraviolet continuum luminosity function. This is in contrast to Lyman break galaxies (LBGs) over the same redshift range, which have been previously shown to increase in linear size as H(z){sup -1}. The compact physical size seems to be a critical determining factor in whether a galaxy will show Ly{alpha} emission or not. The L{sub *} of LBGs and its evolution with redshift can be derived from a simple model where the star formation intensity has an upper limit set by feedback processes, independent of redshift. The increase in L{sub *} of LBGs is mainly driven by the increase in linear size over redshifts for z = 2-7. Since Ly{alpha} galaxies do not grow in linear size, they do not show an increase in L{sub *}.

  1. Lyman-Werner UV escape fractions from primordial haloes

    NASA Astrophysics Data System (ADS)

    Schauer, Anna T. P.; Whalen, Daniel J.; Glover, Simon C. O.; Klessen, Ralf S.

    2015-12-01

    Population III (Pop III) stars can regulate star formation in the primordial Universe in several ways. They can ionize nearby haloes, and even if their ionizing photons are trapped by their own haloes, their Lyman-Werner (LW) photons can still escape and destroy H2 in other haloes, preventing them from cooling and forming stars. LW escape fractions are thus a key parameter in cosmological simulations of early reionization and star formation but have not yet been parametrized for realistic haloes by halo or stellar mass. To do so, we perform radiation hydrodynamical simulations of LW UV escape from 9-120 M⊙ Pop III stars in 105-107 M⊙ haloes with ZEUS-MP. We find that photons in the LW lines (i.e. those responsible for destroying H2 in nearby systems) have escape fractions ranging from 0 to 85 per cent. No LW photons escape the most massive halo in our sample, even from the most massive star. Escape fractions for photons elsewhere in the 11.18-13.6 eV energy range, which can be redshifted into the LW lines at cosmological distances, are generally much higher, being above 60 per cent for all but the least massive stars in the most massive haloes. We find that shielding of H2 by neutral hydrogen, which has been neglected in most studies to date, produces escape fractions that are up to a factor of 3 smaller than those predicted by H2 self-shielding alone.

  2. Damped Lyman α absorbers as a probe of stellar feedback

    NASA Astrophysics Data System (ADS)

    Bird, Simeon; Vogelsberger, Mark; Haehnelt, Martin; Sijacki, Debora; Genel, Shy; Torrey, Paul; Springel, Volker; Hernquist, Lars

    2014-12-01

    We examine the abundance, clustering and metallicity of Damped Lyman α Absorbers (DLAs) in a suite of hydrodynamic cosmological simulations using the moving mesh code AREPO. We incorporate models of supernova and AGN feedback, as well as molecular hydrogen formation. We compare our simulations to the column density distribution function at z = 3, the total DLA abundance at z = 2-4, the measured DLA bias at z = 2.3 and the DLA metallicity distribution at z = 2-4. Our preferred models produce populations of DLAs in good agreement with most of these observations. The exception is the DLA abundance at z < 3, which we show requires stronger feedback in 1011-12 h-1 M⊙ mass haloes. While the DLA population probes a wide range of halo masses, we find the cross-section is dominated by haloes of mass 1010-1011 h-1 M⊙ and virial velocities 50-100 km s-1. The simulated DLA population has a linear theory bias of 1.7, whereas the observations require 2.17 ± 0.2. We show, however, that non-linear growth increases the bias in our simulations to 2.3 at k = 1 h Mpc-1, the smallest scale observed. The scale-dependence of the bias is, however, very different in the simulations compared against the observations. We show that, of the observations we consider, the DLA abundance and column density function provide the strongest constraints on the feedback model.

  3. Sub-Lyman-alpha observations of supernova remnants

    NASA Technical Reports Server (NTRS)

    Long, K. S.

    1993-01-01

    The first map of O VI lambda 1035 emission of the Cygnus Loop has now been obtained with Voyager. The first good spectra of the sub-Lyman-alpha region in the Cygnus Loop and in the Large Magellanic Cloud (LMC) remnant N49 have been obtained with the Hopkins Ultraviolet Telescope. The lines detected below 1200 A include S VI lambda lambda 933,945, C III lambda 977, N III lambda 991, and O VI lambda lambda 1032,1038. The O VI luminosities of the Cygnus Loop and of N49 exceed their soft X-ray luminosities. There is O VI emission at the primary shock front in the Cygnus Loop and from the bright optical filaments. The HUT spectra of the Cygnus Loop can be interpreted in terms of shocks with velocities of 170-190 km/s; the differences between the two spectra are due to the time since the beginning of the shock-cloud encounter.

  4. Variability of Lyman-alpha emission from Jupiter

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The Jovian Lyman-alpha emission line was again observed in 1978 using the high resolution spectrometer on the Copernicus satellite. In intensity of 8.4+3.0 kilo Rayleighs was measured. This value represents a significant increase in intensity over previous (1976) Copernicus observations, but is lower than the recent (1979) values obtained by Voyager I and IUE. The increase in intensity was accompanied by a significant increase in line width, giving strong support to the theory that the emission results from resonant scattering of the solar Ly-alpha line by H atoms in the upper Jovian atmosphere. The strength of Jovian Ly-alpha emission correlates well with the level of solar activity. The solar extreme ultraviolet radiation varies with the solar cycle. This radiation causes the dissociation of H2 and CH4 into H atoms in the Jovian atmosphere. Therefore, in times of high solar activity, the H column density will increase, causing the observed stronger Jovian Ly-alpha emission.

  5. Coupling the emission of ionizing radiation and Lyman alpha

    NASA Astrophysics Data System (ADS)

    Hayes, Matthew

    2013-10-01

    The class of objects that reionized intergalactic hydrogen remains an observational and theoretical problem that is in contention for being the most prominent puzzle piece in contemporary astrophysics. The current consensus - determined almost entirely by ruling out bright active galaxies - is that the process was possibly begun and almost certainly finished by faint, lower-mass galaxies forming their early generations of stars. Recent observations of z 3 galaxies may even have identified the analog populations.However understanding how the emitted ionizing power of galaxies is causally related to their {robustly determined} physical properties is not a study that can be performed at high-z: neither the spatial information nor the standard multi-wavelength diagnostics are available. Moreover, on a case-by-case basis, the intervening IGM absorption is impossible to determine. These considerations have spawned a number of detailed studies with UV space telescopes, the synthesis of which however is that a characteristic population of Lyman continuum {LyC} emitting objects has not yet been identified. We show in this proposal that we have identified a characteristic trait in galaxy spectra that is highly indicative of LyC emission, by combining {a} high-z phenomenological studies, {b} new high-resolution UV spectra of local galaxies, and {c} sophisticated models of radiation transport. Believing that we have determined the signature, we propose to test the new hypothesis with deep spectroscopic observations with HST/COS under the Cycle 21 UV initiative.

  6. Cosmology from the BOSS Lyman-Alpha Forest

    NASA Astrophysics Data System (ADS)

    Font-Ribera, Andreu; SDSS-III Collaboration

    2015-01-01

    After six years of observations, the Baryon Oscillation Spectroscopic Survey (BOSS) ended last summer, and recently made its data public (SDSS Data Release 12). During these years, it has used the SDSS telescope to obtain spectra of 1.5 million galaxies to get very accurate measurements of the Baryon Acoustic Oscillations (BAO) scale at redshift z ~0.5. At the same time, BOSS observed over 184 000 high redshift quasars (z>2.15) with the goal of detecting the BAO feature in the clustering of the intergalactic medium, using a technique known as the Lyman alpha forest (LyaF).In this talk I will overview several results from the LyaF working group in BOSS, including the measurement of BAO at z=2.4 both from the auto-correlation of the LyaF (Delubac et al. 2014), and from its cross-correlation with quasars (Font-Ribera et al. 2014). From the combination of these studies we are able to measure the expansion rate of the Universe 11 billion years ago with a 2% uncertainty.

  7. New Horizons Cruise Observations of Lyman-α Emissions from the Interplanetary Medium

    NASA Astrophysics Data System (ADS)

    Gladstone, G. Randall; Stern, S. Alan; Pryor, Wayne R.

    Initial results are presented for observations of interplanetary Lyman-α and Lyman-β emissions in the outer solar system obtained by the Alice ultraviolet spectrograph on the New Horizons spacecraft (the first new such data from outside the orbit of Saturn since the Voyager spacecraft). The observations consist of 6∘ ×360∘ great-circle swaths on the sky, centered on the ecliptic direction λ = 51. 3∘, β = 44. 8∘, which passes within ˜ 33∘ of the upstream and downstream directions of the interstellar wind. To date, three such scans have been acquired: on October 7, 2007, October 18, 2008, and June 19, 2010 (at which times the New Horizons spacecraft was 7.6, 11.3, and 17.0 AU from the Sun, respectively). The data compare fairly well with model simulations, although the brightness of interplanetary Lyman-α emissions falls off more slowly than expected with radial distance from the Sun. The ratio of Lyman-α/Lyman-β brightnesses in the interplanetary medium agrees well with previous measurements by the Voyager ultraviolet spectrometers.

  8. Design and Fabrication of the All-Reflecting H-Lyman alpha Coronagraph/Polarimeter

    NASA Technical Reports Server (NTRS)

    Hoover, Richard B.; Johnson, R. Barry; Fineschi, Silvano; Walker, Arthur B. C., Jr.; Baker, Phillip C.; Zukic , Muamer; Kim, Jongmin

    1993-01-01

    We have designed, analyzed, and are now fabricating an All-Reflecting H-Lyman alpha Coronagraph/Polarimeter for solar research. This new instrument operates in a narrow bandpass centered at lambda 1215.7 A-the neutral hydrogen Lyman alpha (Ly-alpha) line. It is shorter and faster than the telescope which produced solar Ly-alpha images as a part of the MSSTA payload that was launched on May 13, 1991. The Ly-alpha line is produced and linearly polarized in the solar corona by resonance scattering, and the presence of a magnetic field modifies this polarization according to the Hanle effect. The Lyman alpha Coronagraph/Polarimeter instrument has been designed to measure coronal magnetic fields by interpreting, via the Hanle effect, the measured linear polarization of the coronal Ly-alpha line. Ultrasmooth mirrors, polarizers, and filters are being flow-polished for this instrument from CVD silicon carbide substrates. These optical components will be coated using advanced induced transmission and absorption thin film multilayer coatings, to optimize the reflectivity and polarization properties at 1215.7 A. We describe some of the solar imaging results obtained with the MSSTA Lyman alpha coronagraph. We also discuss the optical design parameters and fabrication plans for the All-Reflecting H-Lyman alpha Coronagraph/Polarimeter.

  9. The Lyman break analogue Haro 11: spatially resolved chemodynamics with VLT FLAMES

    NASA Astrophysics Data System (ADS)

    James, B. L.; Tsamis, Y. G.; Walsh, J. R.; Barlow, M. J.; Westmoquette, M. S.

    2013-04-01

    Using VLT/Fibre Large Array Multi Element Spectrograph (FLAMES) optical integral field unit observations, we present the first spatially resolved spectroscopic study of the well-known blue compact galaxy Haro 11, thought to be a local analogue to high-redshift Lyman break galaxies. Haro 11 displays complex emission line profiles, consisting of narrow (full width at half-maximum, FWHM ≲ 200 km s-1) and broad (FWHM ˜ 200-300 km s-1) components. We identify three distinct emission knots kinematically connected to one another. A chemodynamical analysis is presented, revealing that spatially resolved ionic and elemental abundances do not agree with those derived from integrated spectra across the galaxy. We conclude that this is almost certainly due to the surface brightness weighting of electron temperature in integrated spectra, leading to higher derived abundances. We find that the eastern knot has a low gas density, but a higher temperature (by ˜4000 K) and consequently an oxygen abundance ˜0.4 dex lower than the neighbouring regions. A region of enhanced N/O is found specifically in Knot C, confirming previous studies that found anomalously high N/O ratios in this system. Maps of the Wolf-Rayet (WR) feature at 4686 Å reveal large WR populations (˜900-1500 stars) in Knots A and B. The lack of WR stars in Knot C combined with an age of ˜7.4 Myr suggests that a recently completed WR phase may be responsible for the observed N/O excess. Conversely, the absence of N-enriched gas and strong WR emission in Knots A and B suggests that we are observing these regions at an epoch where stellar ejecta has yet to cool and mix with the interstellar medium.

  10. The high-ion content and kinematics of low-redshift Lyman limit systems

    SciTech Connect

    Fox, Andrew J.; Tumlinson, Jason; Bordoloi, Rongmon; Lehner, Nicolas; Howk, J. Christopher; Tripp, Todd M.; Katz, Neal; Prochaska, J. Xavier; Werk, Jessica K.; Oppenheimer, Benjamin D.; Davé, Romeel

    2013-12-01

    We study the high-ion content and kinematics of the circumgalactic medium around low-redshift galaxies using a sample of 23 Lyman limit systems (LLSs) at 0.08 < z < 0.93 observed with the Cosmic Origins Spectrograph on board the Hubble Space Telescope. In Lehner et al., we recently showed that low-z LLSs have a bimodal metallicity distribution. Here we extend that analysis to search for differences between the high-ion and kinematic properties of the metal-poor and metal-rich branches. We find that metal-rich LLSs tend to show higher O VI columns and broader O VI profiles than metal-poor LLSs. The total H I line width (Δv {sub 90} statistic) in LLSs is not correlated with metallicity, indicating that the H I kinematics alone cannot be used to distinguish inflow from outflow and gas recycling. Among the 17 LLSs with O VI detections, all but two show evidence of kinematic sub-structure, in the form of O VI-H I centroid offsets, multiple components, or both. Using various scenarios for how the metallicities in the high-ion and low-ion phases of each LLS compare, we constrain the ionized hydrogen column in the O VI phase to lie in the range log N(H II) ∼ 17.6-20. The O VI phase of LLSs is a substantial baryon reservoir, with M(high-ion) ∼ 10{sup 8.5-10.9} (r/150 kpc){sup 2} M {sub ☉}, similar to the mass in the low-ion phase. Accounting for the O VI phase approximately doubles the contribution of low-z LLSs to the cosmic baryon budget.

  11. Can the Lyman Continuum Leaked Out of H II Regions Explain Diffuse Ionized Gas?

    NASA Astrophysics Data System (ADS)

    Seon, Kwang-Il

    2009-09-01

    We present an attempt to explain the diffuse Hα emission of a face-on galaxy M 51 with the "standard" photoionization model, in which the Lyman continuum (Lyc) escaping from H II regions propagates large distances into the diffuse interstellar medium (ISM). The diffuse Hα emission of M 51 is analyzed using thin slab models and exponential disk models in the context of the "on-the-spot" approximation. The scale height of the ionized gas needed to explain the diffuse Hα emission with the scenario is found to be of the order of ~1-2 kpc, consistent with those of our Galaxy and edge-on galaxies. The model also provides a vertical profile, when the galaxy is viewed edge-on, consisting of two-exponential components. However, it is found that an incredibly low absorption coefficient of κ0 ≈ 0.4-0.8 kpc-1 at the galactic plane, or, equivalently, an effective cross section as low as σeff ~ 10-5 of the photoionization cross section at 912 Å is required to allow the stellar Lyc photons to travel through the H I disk. Such a low absorption coefficient is out of accord with the properties of the ISM. Furthermore, we found that even the model that has the diffuse ionized gas (DIG) phase only and no H I gas phase shows highly concentrated Hα emissions around H II regions, and can account for only lsim26% of the Hα luminosity of the DIG. This result places a strong constraint on the ionizing source of the DIG. We also report that the Hα intensity distribution functions not only of the DIG, but also of H II regions in M 51, appear to be lognormal.

  12. The High-Ion Content and Kinematics of Low-Redshift Lyman Limit Systems

    NASA Astrophysics Data System (ADS)

    Fox, Andrew; Lehner, N.; Tumlinson, J.; Howk, J. C.; Tripp, T. M.; Prochaska, J. X.; O'Meara, J.; Werk, J.; Bordoloi, R.; Katz, N.; Oppenheimer, B.; Dave, R.

    2014-01-01

    We study the high-ionization phase and kinematics of the circumgalactic medium around low-redshift galaxies in a sample of 23 low-z (0.08Lyman Limit Systems (LLSs) observed with the Cosmic Origins Spectrograph onboard HST. In Lehner et al. (2013), we recently showed that low-z LLSs have a bimodal metallicity distribution. Here we extend that analysis to search for differences between the high-ion and kinematic properties of the metal-poor and metal-rich branches. We find that metal-rich LLSs tend to show higher O VI columns and broader O VI profiles than metal-poor LLSs. The total H I line width (dv90 statistic) in LLSs is not correlated with metallicity, indicating that the H I kinematics alone cannot be used to distinguish inflow and outflow in LLSs. Among the 17 LLSs with O VI detections, all but two show evidence of kinematic sub-structure, in the form of O VI-H I centroid offsets, multiple components, or both. Using various scenarios for how the metallicity in the high-ion and low-ion phases of each LLS compare, we constrain the ionized hydrogen column in the O VI phase to lie in the range log N(H II 17.6-20. Therefore, the O VI phase of LLSs traces a substantial baryon reservoir, with M(high-ion 10^{8.9-10.9}(r/150 kpc)^2 solar masses, similar to the mass in the low-ion phase. Accounting for the O VI phase approximately doubles the contribution of low-z LLSs to the cosmic baryon budget.

  13. Bright z ~ 3 Lyman break galaxies in deep wide field surveys

    NASA Astrophysics Data System (ADS)

    Bian, Fuyan

    In my thesis I investigate the luminous z ˜ 3 Lyman break galaxies in deep wide field surveys. In the first part of the thesis, I use the LBT/LUCIFER to observe a lensed high-redshift star-forming galaxy (J0900+2234) at z = 2.03. With the high S/N near-IR spectroscopic observations, I reveal the detailed physical properties of this high-redshift galaxy, including SFR, metallicity, dust extinction, dynamical mass, and electron number density. In the second part of the thesis, I select a large sample of LBGs at z ˜ 3 from our new LBT Bootes field survey, and study the bright end luminosity function (LF), stellar mass function (SMF) and clustering properties of bright LBGs (1L* < L < 2.5L*). Together with other LF and SMF measurements, the evolution of LF and SMF can be well described by continuously rising star formation history model. Using the clustering measurements in this work and other works, a tight relation between the average host galaxy halo mass and the galaxy star formation rate is found, which can be interpreted as arising from cold flow accretion. The relation also suggests that the cosmic star formation efficiency is about 5%-20% of the total cold flow mass. This cosmic star formation efficiency does not evolve with redshift (from z ˜ 5 to z ˜ 3), hosting dark matter halo mass (1011 -- 1013 M⊙ ), or galaxy luminosity (from 0.3L* to 3L* ). In the third and fourth parts, with the spectroscopic follow-up observations of the bright LBGs, I establish a sample of spectroscopically-confirmed ultraluminous LBGs (ULBGs) in NOAO Boo¨tes field. With this new ULBG sample, the rest-frame UV LF of LBG at M1700A = -23.0 was measured for the first time. I find that the ULBGs have larger outflow velocity, broader Lyalpha emission and ISM absorption line profiles, and more prominent C IV P-Cygni profile. This profile may imply a top-heavy IMF in these ULBGs. The ULBGs have larger stellar mass and SFR, but smaller dust extinction than the typical L* LBGs at z ˜ 2

  14. Identification of a novel series of BET family bromodomain inhibitors: binding mode and profile of I-BET151 (GSK1210151A).

    PubMed

    Seal, Jonathan; Lamotte, Yann; Donche, Frédéric; Bouillot, Anne; Mirguet, Olivier; Gellibert, Françoise; Nicodeme, Edwige; Krysa, Gael; Kirilovsky, Jorge; Beinke, Soren; McCleary, Scott; Rioja, Inma; Bamborough, Paul; Chung, Chun-Wa; Gordon, Laurie; Lewis, Toni; Walker, Ann L; Cutler, Leanne; Lugo, David; Wilson, David M; Witherington, Jason; Lee, Kevin; Prinjha, Rab K

    2012-04-15

    A novel series of quinoline isoxazole BET family bromodomain inhibitors are discussed. Crystallography is used to illustrate binding modes and rationalize their SAR. One member, I-BET151 (GSK1210151A), shows good oral bioavailability in both the rat and minipig as well as demonstrating efficient suppression of bacterial induced inflammation and sepsis in a murine in vivo endotoxaemia model. PMID:22437115

  15. ZrCo as a new H2 storage and getter for Lyman alpha radiation sources

    NASA Astrophysics Data System (ADS)

    Woyke, Thomas; Schiller, Cornelius; Schmidt, Ulrich; Schober, Tilman; Zöger, Martin

    1995-01-01

    In the past, in sealed-off Lyman- alpha radiation sources (121.57 nm), uranium hydride was used as the hydrogen reservoir. We found that the zirconium-cobalt alloy ZrCo, which has similar thermodynamic properties, can also be used for hydrogen storage in such lamps. Like uranium, ZrCo acts as a getter for atmospheric contaminants. The advantage of the use of ZrCo lies in much easier and safer handling during production and disposal of the lamps. Using ZrCo, we succeeded in producing radiation sources with a large Lyman- alpha radiation output and high spectral purity, which were successfully applied in a Lyman- alpha fluorescence hygrometer for stratospheric observations.

  16. Atmospheric Physics and Earth Observations: Observations of Lyman-agr Emissions of Hydrogen and Deuterium.

    PubMed

    Bertaux, J L; Goutail, F; Kockarts, G

    1984-07-13

    A spectrophotometer was flown on Spacelab 1 to study various mechanisms of Lyman-alpha emission in the upper atmosphere. The use of absorption cells filled with H(2) and D(2) gases allowed us to discriminate a number of weak Lyman-alpha emissions heretofore masked by the strong H geocoronal emission due to resonance scattering of solar photons. Preliminary results are presented on three topics: the first optical detection of the deuterium Lyman-alpha emission at 110 kilometers, with an intensity of 330 rayleighs indicating an eddy diffusion coefficient of 1.3 x 10(6) square centimeters per second; auroral proton precipitations seen on both the night and the day side; and an emission located above 250 kilometers of altitude, interpreted as the result of charge exchange of magnetospheric protons with geocoronal atoms. PMID:17837930

  17. Theoretical Predictions of Large Scale Clustering in the Lyman-alpha Forest

    NASA Astrophysics Data System (ADS)

    Cieplak, Agnieszka M.; Slosar, Anze; Khandai, Nishikanta

    2015-01-01

    With the recent progress of Lyman-alpha forest power spectrum measurements, understanding of the bias between the measured flux and the underlying matter power spectrum is becoming crucial to the percent level cosmological interpretation of these measurements. Whereas previous theoretical studies of this bias have used N-body and hydro-PM simulations, we have run hydrodynamic simulations to study the response of the Lyman-alpha forest clustering to large wavelength modes of the underlying matter large-scale structure. Our results demonstrate that this can be simulated by evolving smaller, curved universe cosmologies, representing the same universe with different overdense patches. We use these to study the assumptions of the analytical bias formula derived by Seljak (2012), and compare these results with previous numerical methods of determining bias. With several forthcoming large data sets, such theoretical predictions are important to fully understand the clustering of the Lyman-alpha forest.

  18. Self-regulating galaxy formation. I - H II disk and Lyman-alpha pressure

    NASA Technical Reports Server (NTRS)

    Cox, D. P.

    1985-01-01

    The nascent interstellar medium and star formation model are incorporated into a scenario for the formation epoch of spiral galaxies. The structure, star formation time scale, and luminosity of a self-gravitating isothermal disk are evaluated as functions of the disk surface density. The importance of radiation pressure, particularly that of Lyman-alpha, in maintaining an inflated disk and halting infall is discussed. The Lyman-alpha pressure also supports a considerable halo of material in the vicinity of the disk. A first-order infall scenario and the time-dependent properties of the system it constructs are presented. Disk properties are evaluated at the epoch at which further material is supportable against infall by Lyman-alpha pressure. The two-dimensional family of disk galaxies whose scales and surface density are expressible in terms of fundamental constants and which arise from the three parameter sets of perturbations in the Hubble flow are determined.

  19. Variability of Lyman-alpha and the ultraviolet continuum of 3C 446

    NASA Technical Reports Server (NTRS)

    Bregman, J. N.; Glassgold, A. E.; Huggins, P. J.; Kinney, A. L.

    1986-01-01

    IUE observations have been conducted over the 1230-3175 A range for the violently variable quasar 3C 446, beginning in June 1980, at intervals of 1.2, 2.2, 0.5, and 0.4 yr. Strong absorption of the continuum was found below 1830 A, probably corresponding to a Lyman edge at z of 1.00 + or - 0.01. The absence of Mg II 2798 A absorption implies that the column density is in the lower end of the range, unless the gas is metal-poor. The Lyman-alpha emission line was detected in five spectra; relative to the number of ionizing protons, the line strengths are the same as in normal quasars, and line equivalent widths are small due to the continuum's rise redward of 912 A, which is much steeper than in normal quasars. The Lyman-alpha line and the nearby continuum vary so as to maintain constant equivalent width.

  20. A Spectroscopic Search for Leaking Lyman Continuum at Zeta Approximately 0.7

    NASA Technical Reports Server (NTRS)

    Bridge, Carrie R.; Teplitz, Harry I.; Siana, Brian; Scarlata, Claudia; Rudie, Gwen C.; Colbert, James; Ferguson, Henry C.; Brown, Thomas M.; Conselice, Christopher J.; Armus, Lee; Salvato, Mara; DeMello, Duilia F.; Dickinson, Mark; Gardner, Jonathan P.; Giavalisco, Mauro

    2010-01-01

    We present the results of rest-frame, UV slitless spectroscopic observations of a sample of 32 z approx. 0.7 Lyman Break Galaxy (LBG) analogs in the COSMOS field. The spectroscopic search was performed with the Solar Blind Channel (SBC) on HST. While we find no direct detections of the Lyman Continuum we achieve individual limits (3sigma) of the observed non-ionizing UV to Lyman continuum flux density ratios, f(sub nu)(1500A)/f(sub nu)(830A) of 20 to 204 (median of 73.5) and 378.7 for the stack. Assuming an intrinsic Lyman Break of 3.4 and an optical depth of Lyman continuum photons along the line of sight to the galaxy of 85% we report an upper limit for the relative escape fraction in individual galaxies of 0.02 - 0.19 and a stacked 3sigma upper limit of 0.01. We find no indication of a relative escape fraction near unity as seen in some LBGs at z approx. 3. Our UV spectra achieve the deepest limits to date at any redshift on the escape fraction in individual sources. The contrast between these z approx. 0.7 low escape fraction LBG analogs with z approx. 3 LBGs suggests that either the processes conducive to high f(sub esc) are not being selected for in the z less than or approx.1 samples or the average escape fraction is decreasing from z approx. 3 to z approx. 1. We discuss possible mechanisms which could affect the escape of Lyman continuum photons

  1. Equilibrium Slab Models of Lyman-Alpha Clouds

    NASA Technical Reports Server (NTRS)

    Charlton, Jane C.; Salpeter, Edwin E.; Hogan, Craig J.

    1993-01-01

    We model the L(sub y(alpha)) clouds as slabs of hydrogen with an ionizing extragalactic radiation field incident from both sides. In general, the equilibrium configuration of a slab at redshift z approx. less than 5 is determined by a balance of the gas pressure, gravity (including the effects of a dark matter halo), and the pressure exerted by the inter-galactic medium, P(sub ext). These models have been used to make predictions of the number of slabs as a function of the neutral hydrogen column density, N(sub H). A break in the curve is predicted at the transition between regimes where gravity and pressure are the dominant confining forces, with a less rapid decrease at larger N(sub H). The transition from optically thin to optically thick slabs leads to a gap in the distribution, whose location is governed largely by the spectrum of ionizing radiation. There are certain parallels between lines of sight through the outer HI disk of spiral galaxy with increasing radius, and the progression from damped, to Lyman limit, to forest clouds. We discuss briefly the possibility that at least some of the observed low z forest clouds may be a separate population, associated with galaxies, as suggested by the observations of Bahcall et al. This population could dominate the forest at present if the dark matter attached to galaxies should lead to gravity confinement for this disk population, while the isolated clouds remain pressure confined. The formalism developed in this paper will allow a more detailed study. We also discuss a more general parameter study of the equilibrium configuration of slabs, including mock gravity and L(sub y(alpha)) photon trapping.

  2. eLARS - extending the Lyman Alpha Reference Sample

    NASA Astrophysics Data System (ADS)

    Oestlin, Goeran

    2013-10-01

    Despite its pivotal importance in high-z astrophysics, Lyman alpha {LyA} imaging is a relatively unexplored territory, due to its reliance on HST for far UV imaging. Our team has pioneered systematic LyA imaging in the local universe and developed techniques for producing photometrically accurate images using HST. We recently finished LARS, the first systematic LyA imaging study of 14 UV+H-alpha selected starbursts in the local universe. We found further evidence for LyA variation on physical scales from 30 pc to several kpc, often in a manner uncorrelated with the UV continuum, H-alpha or the galaxy in general. Specifically, we find that when LyA is bright and when a lot of LyA manages to escape, it is always found in the form of a large scale halo. This is, in all such cases, more extended than the UV or H-alpha emission, but rarely symmetric.While these results are fascinating, LARS consists of extreme starbursts that contribute only a small fraction of the total UV and star-formation density at low and intermediate {z 2} redshifts. Given the importance of the LyA line for finding galaxies and for galaxy evolution studies it is imperative to now generalize the investigation and produce a fully representative quantitative framework. We here propose to image a sample of 28 local galaxies, dominated by more disk like objects {c.f. the irregular objects of LARS}, and the kind of objects than dominate the local FUV luminosity function. Specifically, we will investigate the effects of geometry and galaxy orientation of the emergent LyA emission.

  3. Observed perturbations of the velocity distribution of interstellar hydrogen atoms in the solar system with Prognoz Lyman-alpha measurements

    NASA Astrophysics Data System (ADS)

    Lallement, R.; Bertaux, J. L.; Kurt, V. G.; Mironova, E. N.

    1984-11-01

    Observations of the interplanetary Lyman α emission made at five different places in the solar system with high apogee satellites Prognoz 5 and Prognoz 6 are reported. This Lyα emission is the result of resonance scattering of solar photons by H atoms of the local interstellar medium (LISM) flowing in the solar system at the velocity - Vw and the spectral profile is an image of the velocity distribution of the atoms. A hydrogen absorption cell was used to analyze the spectral profile, the variation of Doppler shift with looking direction providing its spectral scanning. A first estimate of the LISM temperature is derived, T ≅ 8000K, and also an approximate location of Vw in fair agreement with previous measurements. The observed variation of the heating effect is of 3000K, and is independent of the existence of a potential galactic background in the vicinity of the Lyα wavelength. An upper limit of this background is found to be 15 Rayleigh.

  4. In situ measurement of water vapor in the stratosphere with a cryogenically cooled Lyman-alpha hygrometer

    NASA Technical Reports Server (NTRS)

    Schwab, J. J.; Weinstock, E. M.; Nee, J. B.; Anderson, J. G.

    1990-01-01

    In situ measurements of water vapor in the stratosphere with a new instrument are reported. The instrument has been designed to observe daytime water vapor from a multiinstrument balloon gondola that simultaneously measures free radicals such as OH, HO2, and O3 in the stratosphere up to 40 km. Lyman-alpha photofragment fluorescence is used to measure water molecules in a flowing sample of ambient air. A brief description of the instrument is given, followed by the results of the first four balloon flights. The measured mixing ratio for this flight varies from 3.0-5.5 ppmv over the altitude range of 17-34 km. Adjustments in the cooling protocol for the flights of July 6, 1988, July 28, and August 25, 1989, result in a much higher signal-to-noise ratio. Profiles from these three flights are similar to, but somewhat higher, than the 1987 profile. Implications of measurements are discussed, as are the issues of short- and long-term variability of stratospheric water vapor.

  5. UV Spectral Variability and the Lyman-Alpha Forest in the Lensed Quasar Q0957+561

    NASA Technical Reports Server (NTRS)

    Dolan, J. F.; Michalitsianos, A. G.; Nguyen, Q. T.; Hill, R. J.

    1999-01-01

    Far-ultraviolet spectra of the gravitational lens components Q0957+561 A and B were obtained with the Hubble Space Telescope Faint Object Spectrograph (FOS) at five equally spaced epochs, one every two weeks. We confirm the flux variability of the quasar's Lyman-alpha and O VI lambda 1037 emission lines reported in IUE (International Ultraviolet Explorer) spectra. The fluxes in these lines vary on a time scale of weeks in the local rest frame (LRF), independently of each other and of the surrounding continuum. The individual spectra of each image were co-added to investigate the properties of the Lyman-alpha forest along the two lines of sight to the quasar. Absorption lines having equivalent width W (sub lambda) greater than or equal to 0.3 Angstroms in the LRF not previously identified as interstellar lines, metal lines, or higher order Lyman lines were taken to be LY-alpha forest lines. The existence of each line in this consistently selected set was then verified by its presence in two archival FOS spectra with approx. 1.5 times higher signal to noise than our co-added spectra. Ly-alpha forest lines with W (sub lambda) greater than or equal to 0.3 Angstroms appear at 42 distinct wavelengths in the spectra of the two images. Two absorption lines in the spectrum of image A have no counterpart at that wavelength in the spectrum of image B, and two lines in image B have no counterpart in image A. Based on the separation of the lines of sight at the redshift of the absorption lines appearing in only one spectrum, the density of the absorbing clouds in the direction of Q0957+561 must change significantly over a distance of 79 (+34, -26) h (sub 50) (sup -1) kpc in the simplified model where the absorbers are treated as spherical clouds and the characteristic dimension is the radius. (We adopt H (sub 0)= 50 h (sub 50) km s (sup -1) kpc (sup -1), q (sub 0) = 1/2, and LAMBDA = 0 throughout the paper.) The two limits define the 68% confidence interval on the

  6. The Lyman-continuum photon production efficiency in the high-redshift Universe

    NASA Astrophysics Data System (ADS)

    Wilkins, Stephen M.; Feng, Yu; Di-Matteo, Tiziana; Croft, Rupert; Stanway, Elizabeth R.; Bouwens, Rychard J.; Thomas, Peter

    2016-05-01

    The Lyman-continuum photon production efficiency (ξion) is a critical ingredient for inferring the number of photons available to reionize the intergalactic medium. To estimate the theoretical production efficiency in the high-redshift Universe we couple the BlueTides cosmological hydrodynamical simulation with a range of stellar population synthesis models. We find Lyman-continuum photon production efficiencies of log10(ξion/erg-1 Hz) ≈ 25.1-25.5 depending on the choice of stellar population synthesis model. These results are broadly consistent with recent observational constraints at high-redshift though favour a model incorporating the effects of binary evolution.

  7. Detection of Lyman-beta and Helium Resonance Radiation in the Night Sky.

    PubMed

    Young, J M; Carruthers, G R; Holmes, J C; Johnson, C Y; Patterson, N P

    1968-05-31

    A rocket-borne photometer has detected far ultraviolet night glow radiations that are identified as Lyman-beta (HI 1026 angstroms), and the helium lines at 304 or 584 angstroms, or at both. At an altitude of 227 kilometers the measured intensity for Lyman-beta was about 10 rayleighs. The discrimination characteristics of the broad-band helium radiation filter give helium line intensities, at 227 kilometers, of 4.8 and 12 rayleighs, respectively, pending identification of the wavelength of the radiation as 304 or 584 angstroms. These ultraviolet radiations appear sufficient to maintain the night E and F(1) regions of the ionosphere. PMID:17768892

  8. OGO-5 measurements of the Lyman-alpha sky background in 1970 and 1971

    NASA Technical Reports Server (NTRS)

    Thomas, G. E.; Krassa, R. F.

    1974-01-01

    The results of measurements of the Lyman-alpha sky background emission at 1216 A, made by two different UV photometers during the last three 'spin-up' maneuvers (enabling more than 50% of the sky to be observed) are examined. The processed data revealed a smooth variation of Lyman-alpha brightness from a broad maximum near RA = 269 deg, declination = -20 deg to a broader minimum near RA = 50 deg, declination = +20 deg. The maximum/minimum intensity ratio is found to be on the order of 4.

  9. Stationary Inverted Balmer and Lyman populations for a CW HI water-plasma laser

    NASA Astrophysics Data System (ADS)

    Mills, Randell L.

    2002-10-01

    Stationary inverted H Balmer and Lyman populations were observed from a low pressure water-vapor microwave discharge plasma. The ionization and population of excited atomic hydrogen levels was attributed to energy provided by a catalytic resonance energy transfer between hydrogen atoms and molecular oxygen formed in the water plasma. The catalysis mechanism was supported by the observation of O^2+ and H Balmer line broadening of 55 eV compared to 1 eV for hydrogen alone. The high hydrogen atom temperature with a relatively low electron temperature, Te = 2 eV, exhibited characteristics of cold recombining plasmas. These conditions of a water plasma favored an inverted population in the lower levels. Thus, the catalysis of atomic hydrogen may pump a cw HI laser. From our results, laser oscillations are may be possible from (i) n = 3, n = 4, n = 5, n = 6, n = 7, and n = 8 to n = 2, (ii) n = 4, n = 5, n = 6, and n = 7 to n = 3 and (iii) n = 5 and n = 6 to n = 4. Lines of the Balmer series of n = 5, and n = 6 to n = 2 and the Paschen series of n = 5 to n = 3 were of particular importance because of the potential to design blue and 1.3 micron infrared lasers, respectively, which are ideal for many communications and microelectronics applications. At a microwave input power of 9W/cm^3, a collisional radiative model showed that the hydrogen excited state population distribution was consistent with an n = 1arrow5,6 pumping power of an unprecedented 200W/cm^3. High power hydrogen gas lasers are anticipated at wavelengths, over a broad spectral range from far infrared to violet which may be miniaturized to micron dimensions. Such a hydrogen laser represents the first new atomic gas laser in over a decade, and it may prove to be the most efficient, versatile, and useful of all. A further application is the direct generation of electrical power using photovoltaic conversion of the spontaneous or stimulated water vapor plasma emission.

  10. A connection between extremely strong damped Lyman-α systems and Lyman-α emitting galaxies at small impact parameters

    NASA Astrophysics Data System (ADS)

    Noterdaeme, P.; Petitjean, P.; Pâris, I.; Cai, Z.; Finley, H.; Ge, J.; Pieri, M. M.; York, D. G.

    2014-06-01

    We present a study of ~100 high redshift (z ~ 2-4) extremely strong damped Lyman-α systems (ESDLA, with N(H i) ≥ 0.5 × 1022cm-2) detected in quasar spectra from the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey (SDSS-III) Data Release 11. We study the neutral hydrogen, metal, and dust content of this elusive population of absorbers and confirm our previous finding that the high column density end of the N(H i) frequency distribution has a relatively shallow slope with power-law index -3.6, similar to what is seen from 21-cm maps in nearby galaxies. The stacked absorption spectrum indicates a typical metallicity ~1/20th solar, similar to the mean metallicity of the overall DLA population. The relatively small velocity extent of the low-ionisation lines suggests that ESDLAs do not arise from large-scale flows of neutral gas. The high column densities involved are in turn more similar to what is seen in DLAs associated with gamma-ray burst afterglows (GRB-DLAs), which are known to occur close to star-forming regions. This indicates that ESDLAs arise from a line of sight passing at very small impact parameters from the host galaxy, as observed in nearby galaxies. This is also supported by simple theoretical considerations and recent high-z hydrodynamical simulations. We strongly substantiate this picture by the first statistical detection of Ly α emission with ⟨LESDLA(Ly α)⟩ ≃ (0.6 ± 0.2) × 1042 erg s-1 in the core of ESDLAs (corresponding to about 0.1 L⋆ at z ~ 2-3), obtained through stacking the fibre spectra (of radius 1 ″ corresponding to ~8 kpc at z ~ 2.5). Statistical errors on the Ly α luminosity are of the order of 0.1 × 1042 erg s-1 but we caution that the measured Ly α luminosity may be overestimated by ~35% due to sky light residuals and/or FUV emission from the quasar host and that we have neglected flux-calibration uncertainties. We estimate a more conservative uncertainty of 0.2 × 1042 erg s-1. The

  11. Lyman Alpha Emitting Galaxies in the Nearby Universe

    NASA Astrophysics Data System (ADS)

    Hayes, Matthew

    2015-07-01

    The Lyman alpha emission line (Lyα) of neutral hydrogen (Hi) is intrinsically the brightest emission feature in the spectrum of astrophysical nebulae, making it a very attractive observational feature with which to survey galaxies. Moreover as an ultraviolet resonance line, Lyα possesses several unique characteristics that make it useful to study the properties of the interstellar medium and ionising stellar population at all cosmic epochs. In this review, I present a summary of Lyα observations of galaxies in the nearby universe. By ultraviolet continuum selection, at the magnitudes reachable with current facilities, only ≈ 5% of the local galaxy population shows a Lyα equivalent width (W Lyα) that exceeds 20 Å. This fraction increases dramatically at higher redshifts, but only in the local universe can we study galaxies in detail and assemble unprecedented multi-wavelength datasets. I discuss many local Lyα observations, showing that when galaxies show net Lyα emission, they ubiquitously also produce large-scale halos of scattered Lyα, that dominate the integrated luminosity. Concerning global measurements, we discuss how W Lyα and the Lyα escape fraction (f Lyα esc) are higher (W Lyα ≳ 20 Å and f Lyα esc ≳ 10%) in galaxies that represent the less massive and younger end of the distribution for local objects. This is connected with various properties, such that Lyα-emitting galaxies have lower metal abundances (median value of 12 + log(O/H) ~ 8.1) and dust reddening. However, the presence of galactic outflows/winds is also vital to Doppler shift the Lyα line out of resonance with the atomic gas, and high W Lyα is found only among galaxies with winds faster than ~ 50 km s-1. The empirical evidence is then assembled into a coherent picture, and the requirement for star-formation-driven feedback is discussed in the context of an evolutionary sequence where the interstellar medium is accelerated and/or subject to hydrodynamical instabilities

  12. DYNAMICS OF LYMAN BREAK GALAXIES AND THEIR HOST HALOS

    SciTech Connect

    Lowenthal, James D.; Koo, David C.; Van Kampen, Eelco E-mail: koo@ucolick.or E-mail: evkampen@eso.or

    2009-09-20

    We present deep two-dimensional spectra of 22 candidate and confirmed Lyman break galaxies (LBGs) at redshifts 2 < z < 4 in the Hubble Deep Field (HDF) obtained at the Keck II telescope. The targets were preferentially selected with spatial extent and/or multiple knot morphologies, and we used slitmasks and individual slits tilted to optimize measurement of any spatially resolved kinematics. Our sample is more than 1 mag fainter and is at higher redshift than the kinematic LBG targets previously studied by others. The median target magnitude was I {sub 814} = 25.3, and total exposure times ranged from 10 to 50 ks. We measure redshifts, some new, ranging from z = 0.2072 to z = 4.056, including two interlopers at z < 1, and resulting in a sample of 14 LBGs with a median redshift z = 2.424. The morphologies and kinematics of the close pairs and multiple knot sources in our sample are generally inconsistent with galaxy formation scenarios postulating that LBGs occur only at the bottom of the potential wells of massive host halos; rather, they support 'collisional starburst' models with significant major merger rates and a broad halo occupation distribution. For 13 LBGs with possible kinematic signatures, we estimate a simple dynamical mass, subject to numerous caveats and uncertainties, of the galaxies and/or their host dark matter halos. Dynamical mass estimates of individual galaxies range from 4 x 10{sup 9} h {sup -1} M{sub sun} to 1.1 x 10{sup 11} h {sup -1} M{sub sun} and mass estimates of halos, based on close LBG pairs, range from <10{sup 10} h {sup -1} to {approx}10{sup 14} h {sup -1} M{sub sun} with a median value 1 x 10{sup 13} M{sub sun}. Comparison with a recent numerical galaxy formation model implies that indeed the pairwise velocities might not reflect true dynamical masses. We compare our dynamical mass estimates directly to stellar masses estimated for the same galaxies from SEDs, and find no evidence for a strong correlation. The diversity of

  13. Lyman alpha emitter evolution in the reionization epoch

    NASA Astrophysics Data System (ADS)

    Dayal, P.; Ferrara, A.; Saro, A.; Salvaterra, R.; Borgani, S.; Tornatore, L.

    2009-12-01

    Combining cosmological smoothed particle hydrodynamics (SPH) simulations with a previously developed Lyα production/transmission model and the Early Reionization Model (ERM; reionization ends at redshift z ~ 7), we obtain Lyα and UV luminosity functions (LFs) for lyman alpha emitters (LAEs) at 5.7 <= z <= 7.6. Matching model results to observations at z ~ 5.7 requires escape fractions of Lyα,fα = 0.3, and UV (non-ionizing) continuum photons, fc = 0.22, corresponding to a colour excess, E(B - V) = 0.15. We find that (i) fc increases towards higher redshifts, due the decreasing mean dust content of galaxies, (ii) the evolution of fα/fc hints at the dust content of the interstellar medium becoming progressively inhomogeneous/clumped with decreasing redshift. Using the model assumptions, clustering of sources has little effect on the Lyα LF for a cosmic hydrogen neutral fraction χHI <= 10-4, a value attained at z <= 6.6 in the ERM. However, during the initial reionization phases (z >~ 7), the clustering photoionization boost becomes important. We quantify the physical properties of observed LAEs and their redshift evolution, for which we give handy analytical fitting functions. Halo (stellar) masses are in the range 10.0 < logMh < 11.8 (8.1 < logM* < 10.4) with Mh ~ M0.64*. The star formation rates are , mass-weighted mean ages are t* > 20 Myr at all redshifts, while the mean stellar metallicity increases from Z = 0.12Zsolar at z ~ 7.6 to Z = 0.22Zsolar at z ~ 5.7; both t* and Z positively correlate with stellar mass. The brightest LAEs are all characterized by large and intermediate ages (~200Myr), while objects in the faint end of the Lyα LF show large age and star formation rate spreads. With no more free parameters, the spectral energy distributions of three LAE at z ~ 5.7 observed by Lai et al. (2007) are well reproduced by an intermediate age (182-220 Myr) stellar population and the above E(B - V) value. The model uncertainties, mostly related to the

  14. N2 Lyman-Birge-Hopfield dayglow from ATLAS 1

    NASA Technical Reports Server (NTRS)

    Torr, Marsha R.; Torr, D. G.; Chang, T.; Richards, P.; Germany, G.

    1994-01-01

    Spectral measurements of the far ultraviolet dayglow were made from the ATLAS 1 shuttle mission using an intensified charge coupled device (CCD) imaging spectrometer array. The instrument imaged relatively large (177 A) segments of the spectrum simultaneously and had the capability to image altitude in the second dimension of the two-dimensional focal plane detector when the entrance slit of the instrument was oriented perpendicular to the limb of the Earth. The far ultraviolet (FUV) channel of the instrument used a CsTe photocathode rather than the more conventionally used and more solar blind CsI photocathode material. As a result, the spectra were also measured with good sensitivity at FUV wavelengths longer than 1500 A. In this paper, data are selected of specific interest to a study of the N2 Lyman-Birge-Hopfield system using two shuttle attitudes: In the first the field of view was held at a fixed tangent ray height of approximately 140 km while scanning in wavelength, providing repeated FUV spectra over a range of latitudes and allowing comparison with our thermospheric airglow model. In the second observing sequence the line of sight of the instrument was scanned down through the atmosphere but covered about 75% of the full wavelength range. This sequence allows comparison of height dependence,including O2 absorption effects, with the thermospheric model. In all cases, relatively good agreement is obtained with the model (run strictly in a predictive mode) in comparisions in which the line of sight must be intergrated along a path that spans a considerable range of conditions (height, local time, latitude, solar zenith angle). In the case of the data sets examined in this study the vibrational population distributions show mixed results. In one case the distribution agrees well with a theoretical model based on direct electron impact excitation without a significant cascade contribution. A second case indicated a lower population in nu' = 3 and a higher

  15. Lyman-α forest constraints on decaying dark matter

    NASA Astrophysics Data System (ADS)

    Wang, Mei-Yu; Croft, Rupert A. C.; Peter, Annika H. G.; Zentner, Andrew R.; Purcell, Chris W.

    2013-12-01

    We present an analysis of high-resolution N-body simulations of decaying dark matter cosmologies focusing on the statistical properties of the transmitted Lyman-α (Lyα) forest flux in the high-redshift intergalactic medium (IGM). In this type of model a dark matter particle decays into a slightly less massive stable dark matter daughter particle and a comparably light particle. The small mass splitting provides a nonrelativistic kick velocity Vk=cΔM/M to the daughter particle resulting in free-streaming and subsequent damping of small-scale density fluctuations. Current Lyα forest power spectrum measurements probe comoving scales up to ˜2-3h-1Mpc at redshifts z˜2-4, providing one of the most robust ways to probe cosmological density fluctuations on relatively small scales. The suppression of structure growth due to the free-streaming of dark matter daughter particles also has a significant impact on the neutral hydrogen cloud distribution, which traces the underlying dark matter distribution well at high redshift. We exploit Lyα forest power spectrum measurements to constrain the amount of free-streaming of dark matter in such models and thereby place limits on decaying dark matter based only on the dynamics of cosmological perturbations without any assumptions about the interactions of the decay products. We use a suite of dark-matter-only simulations together with the fluctuating Gunn-Peterson approximation to derive the Lyα flux distribution. We argue that this approach should be sufficient for our main purpose, which is to demonstrate the power of the Lyα forest to constrain decaying dark matter models. We find that Sloan Digital Sky Survey 1D Lyα forest power spectrum data place a lifetime-dependent upper limit Vk≲30-70km/s for decay lifetimes ≲10Gyr. This is the most stringent model-independent bound on invisible dark matter decays with small mass splittings. For larger mass splittings (large Vk), Lyα forest data restrict the dark matter

  16. Properties of nearby interstellar hydrogen deduced from Lyman-alpha sky background measurements

    NASA Technical Reports Server (NTRS)

    Thomas, G. E.

    1972-01-01

    For a sufficiently rapid relative motion of the solar system and the nearby interstellar gas, neutral atoms may be expected to penetrate the heliosphere before becoming ionized. Recent satellite measurements of the Lyman alpha emission above the geocorona indicate such an interstellar wind of neutral hydrogen emerging from the direction of Sagittarius and reaching to within a few astronomical units of the sun. A detailed model of the scattering of solar Lyman alpha from the spatial distribution of neutral hydrogen in interplanetary space is presented. This asymmetric distribution is established by solar wind and solar ultraviolet ionization processes along the trajectories of the incoming hydrogen atoms. The values of the interstellar density, the relative velocity, and the gas temperature are adjusted to agree with the Lyman alpha measurements. The results may be interpreted in terms of two models, the cold model and the hot model of the interstellar gas, depending on whether galactic Lyman alpha emission is present at its maximum allowable value or negligibly small.

  17. A Lyman-alpha tunable acousto-optic filter for detecting superthermal flare protons

    NASA Technical Reports Server (NTRS)

    Mickey, Donald L.

    1994-01-01

    The goal of this project was to develop and characterize a narrow-band, tunable filter for use near the Lyman-alpha line of hydrogen at 121.6 nm. Such a filter could form the critical component of an instrument to observe asymmetries in the solar Lyman-alpha line, caused by energetic protons accelerated during the impulsive phase of solar flares. Characteristic charge-exchange nonthermal emission at Lyman alpha should be produced when sub-MeV protons are injected into the chromosphere, but no instrument suitable for their detection has been developed. Such an instrument would require a narrow-band (less than 0.01 nm) tunable filter with aperture and throughput consistent with imaging a solar active region at 0.1 second intervals. The development of acousto-optic tunable filters (AOTF) suitable for use as compact, simple tunable filters for astronomical work suggested an investigation into the use of an AOTF at Lyman-alpha.

  18. Resolving Lyman-alpha Emission On Physical Scales < 270 pc at z > 4

    NASA Astrophysics Data System (ADS)

    Bayliss, Matthew

    2014-10-01

    We propose ACS-WFC Ramp narrowband imaging of six strongly lensed Lyman-alpha Emitters (LAEs) at z > 4 that will spatially resolve the Lyman-alpha line emitting regions on scales < 270 pc. The best available observations (HST, Spitzer, 10m ground based telescopes) are unable to provide robust measurements of the structure of these galaxies from blank field studies, but strong gravitational lensing provides a unique opportunity to peer into the heart of young star forming galaxies at high redshift and address outstanding questions regarding their morphology and evolution. Strong lensing magnifies each of our target LAEs, increasing the effective spatial resolution of ACS-WFC such that the point spread function will correspond to physical scales < 270 parsecs within all six z > 4 galaxies. Additionally, the boost in flux due to gravitational lensing makes our proposed targets the brightest sources of their kind at these redshifts, in spite of the fact that they are intrinsically ~L* LAEs. The proposed observations will probe the morphological properties of Lyman-alpha and UV continuum emission in typical/representative high-redshift LAEs with signal-to-noise and spatial resolution comparable to studies of Lyman-alpha emitting galaxies in the z ~ 0.1 universe. The resulting data will bridge the gap between deep ground-based studies of blank field LAEs at high redshift, and detailed studies of low-redshift LAEs.

  19. A Search for z>6.5 Lyman-alpha Emitting Galaxies with WISP

    NASA Astrophysics Data System (ADS)

    Bagley, Micaela B.; Scarlata, Claudia; Dai, Yu Sophia; Rafelski, Marc; Baronchelli, Ivano; Colbert, James W.; Dominguez, Alberto; Hathi, Nimish P.; Henry, Alaina L.; Malkan, Matthew Arnold; Martin, Crystal L.; Mehta, Vihang; Pahl, Anthony; Ross, Nathaniel; Rutkowski, Michael J.; Teplitz, Harry I.; WISP Team

    2016-01-01

    The observed number density of Lyman-alpha emitting galaxies at z>6 provides an important probe of the reionization history of the universe. Because Lyman-alpha photons are very sensitive to the presence of neutral hydrogen, the evolution of the galaxy number density above redshift 6 can be used as a measurement on the progress of reionization. However, the Lyman-alpha luminosity function is currently poorly constrained at high-z. We present the results of a systematic search for Lyman-alpha emitters (LAEs) at redshifts of ~6.5 to 7.5 using the HST WFC3 Infrared Spectroscopic Parallels (WISP) survey. WISP's uncorrelated fields are well-suited to the study of bright LAEs, minimizing the effects of clustering introduced by a patchy reionization. From the 30 deepest WISP fields, we compile a sample of single-line emitters, confirm redshifts with broadband colors, and identify LAE candidates that have "dropped out" (are undetected at the 1 sigma level) of the WFC3 UVIS filters. By combining our results with other z~7 studies, we determine whether the number density of LAEs evolves past z~6.5.

  20. Comparison between solar wind latitude distribution derived from Lyman-alpha observations and ULYSSES measurements

    NASA Astrophysics Data System (ADS)

    Quemarais, E.; Lallement, R.; Bertaux, J. L.; Sandel, B. R.

    1995-06-01

    The all-sky interplanetary Lyman-alpha pattern is sensitive to the latitude distribution of the solar wind because of destruction of neutral H by charge-exchange with solar wind protons. Lyman-alpha intensities recorded by Prognoz 5 and 6 in 1976 in a few parts of the sky were demonstrating a decrease of solar wind mass flux by about 30 % from equator to pole, when assuming a sinusoidal variation of this mass flux (harmonic distribution). A new analysis with a discrete variation with latitude has shown a decrease from 0 to 30 deg and then a plateau of constant mass flux up to the pole. This distribution bears a striking resemblance with Ulysses in-situ measurements, showing a clear similarity at 19 years interval. The Ulysses measurements were then used as a model input to calculate an all-sky Lyman-alpha pattern, either with a discrete model or with a harmonic solar wind variation with the same Ulysses equator-to-pole variation. There are conspicuous differences between the two Lyman-alpha patterns, in particular in the downwind region which are discussed in the context of future all-sky measurements with SWAN experiment on SOHO.

  1. Comparison between solar wind latitude distribution derived from Lyman-alpha observations and Ulysses measurements

    NASA Technical Reports Server (NTRS)

    Quemarais, E.; Lallement, R.; Bertaux, J. L.; Sandel, B. R.

    1995-01-01

    The all-sky interplanetary Lyman-alpha pattern is sensitive to the latitude distribution of the solar wind because of destruction of neutral H by charge-exchange with solar wind protons. Lyman-alpha intensities recorded by Prognoz 5 and 6 in 1976 in a few parts of the sky were demonstrating a decrease of solar wind mass flux by about 30 % from equator to pole, when assuming a sinusoidal variation of this mass flux (harmonic distribution). A new analysis with a discrete variation with latitude has shown a decrease from 0 to 30 deg and then a plateau of constant mass flux up to the pole. This distribution bears a striking resemblance with Ulysses in-situ measurements, showing a clear similarity at 19 years interval. The Ulysses measurements were then used as a model input to calculate an all-sky Lyman-alpha pattern, either with a discrete model or with a harmonic solar wind variation with the same Ulysses equator-to-pole variation. There are conspicuous differences between the two Lyman-alpha patterns, in particular in the downwind region which are discussed in the context of future all-sky measurements with SWAN experiment on SOHO.

  2. Precise Determination of the Lyman-1 Transition Energy in Hydrogen-like Gold Ions with Microcalorimeters

    NASA Astrophysics Data System (ADS)

    Kraft-Bermuth, S.; Andrianov, V.; Bleile, A.; Echler, A.; Egelhof, P.; Grabitz, P.; Kilbourne, C.; Kiselev, O.; McCammon, D.; Scholz, P.

    2014-09-01

    The precise determination of the transition energy of the Lyman-1 line in hydrogen-like heavy ions provides a sensitive test of quantum electrodynamics in very strong Coulomb fields. We report the determination of the Lyman-1 transition energy of gold ions (Au) with microcalorimeters at the experimental storage ring at GSI. X-rays produced by the interaction of 125 MeV/u Au ions with an internal argon gas-jet target were detected. The detector array consisted of 14 pixels with silicon thermistors and Sn absorbers, for which an energy resolution of 50 eV for an X-ray energy of 59.5 keV was obtained in the laboratory. The Lyman-1 transition energy was determined for each pixel in the laboratory frame, then transformed into the emitter frame and averaged. A Dy-159 source was used for energy calibration. The absolute positions of the detector pixels, which are needed for an accurate correction of the Doppler shift, were determined by topographic measurements and by scanning a collimated Am-241 source across the cryostat window. The energy of the Lyman-1 line in the emitter frame is eV, in good agreement with theoretical predictions. The systematic error is dominated by the uncertainty in the position of the cryostat relative to the interaction region of beam and target.

  3. Design and fabrication of the All-Reflecting H-Lyman-alpha Coronagraph/Polarimeter

    NASA Technical Reports Server (NTRS)

    Hoover, Richard B.; Johnson, R. B.; Fineschi, Silvano; Walker, Arthur B. C., Jr.; Baker, Phillip C.; Zukic, Muamer; Kim, Jongmin

    1993-01-01

    We have designed, analyzed, and are now fabricating an All-Reflecting H-Lyman-alpha Coronagraph/Polarimeter for solar research. This new instrument operates in a narrow bandpass centered at 215.7 A - the neutral hydrogen Ly-alpha line. It is shorter and faster than the telescope which produced solar Ly-alpha images as a part of the MSSTA payload that was launched on May 13, 1991. The Ly-alpha line is produced and linearly polarized in the solar corona by resonance scattering, and the presence of a magnetic field modifies this polarization according to the Hanle effect. The Lyman-alpha Coronagraph/Polarimeter instrument has been designed to measure coronal magnetic fields by interpreting, via the Hanle effect, the measured linear polarization of the coronal Ly-alpha line. Ultrasmooth mirrors, polarizers, and filters are being flow-polished for this instrument from CVD silicon carbide substrates. These optical components will be coated using advanced induced transmission and absorption thin film multilayer coatings to optimize the reflectivity and polarization properties at 1215.7 A. We describe some of the solar imaging results obtained with the MSSTA Lyman-alpha coronagraph. We also discuss the optical design parameters and fabrication plans for the All-Reflecting H-Lyman-alpha Coronagraph/Polarimeter.

  4. Muscarinic subtypes profile modulation within a series of new antagonists, bridged bicyclic derivatives of 2,2-diphenyl-[1,3]-dioxolan-4-ylmethyl-dimethylamine.

    PubMed

    Piergentili, Alessandro; Gentili, Francesco; Ghelfi, Francesca; Marucci, Gabriella; Pigini, Maria; Quaglia, Wilma; Giannella, Mario

    2003-09-01

    A set of new muscarinic antagonists, bridged bicyclic derivatives of 2,2-diphenyl-[1,3]-dioxolan-4-ylmethyl-dimethylamine (1), was synthesized and tested to evaluate their affinity and selectivity for M(1), M(2), M(3) and M(4) receptor subtypes. The conformational constraint of 1 in a bicyclic structure, and the variation in distance and stereochemistry of the active functions allowed us to modulate the selectivity of interaction with the M(1)-M(3) receptor subtypes. The most interesting compound was (cis,trans)-2-(2,2-diphenylethyl)-5-methyl-tetrahydro-[1,3]dioxolo[4,5-c]pyrrole oxalate (6), which is equipotent with Pirenzepine on rabbit vas deferens (M(1)-putative) but shows a better selectivity profile. PMID:12927850

  5. Large-scale 3D mapping of the intergalactic medium using the Lyman α forest

    NASA Astrophysics Data System (ADS)

    Ozbek, Melih; Croft, Rupert A. C.; Khandai, Nishikanta

    2016-03-01

    Maps of the large-scale structure of the Universe at redshifts 2-4 can be made with the Lyman α forest which are complementary to low-redshift galaxy surveys. We apply the Wiener interpolation method of Caucci et al. to construct three-dimensional maps from sets of Lyman α forest spectra taken from cosmological hydrodynamic simulations. We mimic some current and future quasar redshift surveys [Baryon Oscillation Spectroscopic Survey (BOSS), extended BOSS (eBOSS) and Mid-Scale Dark Energy Spectroscopic Instrument (MS-DESI)] by choosing similar sightline densities. We use these appropriate subsets of the Lyman α absorption sightlines to reconstruct the full three-dimensional Lyman α flux field and perform comparisons between the true and the reconstructed fields. We study global statistical properties of the intergalactic medium (IGM) maps with autocorrelation and cross-correlation analysis, slice plots, local peaks and point-by-point scatter. We find that both the density field and the statistical properties of the IGM are recovered well enough that the resulting IGM maps can be meaningfully considered to represent large-scale maps of the Universe in agreement with Caucci et al., on larger scales and for sparser sightlines than had been tested previously. Quantitatively, for sightline parameters comparable to current and near future surveys the correlation coefficient between true and reconstructed fields is r > 0.9 on scales >30 h-1 Mpc. The properties of the maps are relatively insensitive to the precise form of the covariance matrix used. The final BOSS quasar Lyman α forest sample will allow maps to be made with a resolution of ˜30 h-1 Mpc over a volume of ˜15 h-3 Gpc3 between redshifts 1.9 and 2.3.

  6. Evaporation of the planet HD 189733b observed in H I Lyman

    NASA Astrophysics Data System (ADS)

    Lecavelier Des Etangs, A.; Ehrenreich, D.; Vidal-Madjar, A.; Ballester, G. E.; Désert, J.-M.; Ferlet, R.; Hébrard, G.; Sing, D. K.; Tchakoumegni, K.-O.; Udry, S.

    2010-05-01

    We observed three transits of the extrasolar planet HD 189733b in H i Lyman-α and in a few other lines in the ultraviolet with HST/ACS, in the search for atmospheric signatures. We detect a transit signature in the Lyman-α light curve with a transit depth of 5.05 ± 0.75%. This depth exceeds the occultation depth produced by the planetary disk alone at the 3.5σ level (statistical). Other stellar emission lines are less bright, and, taken individually, they do not show the transit signature, while the whole spectra redward of the Lyman-α line has enough photons to show a transit signature consistent with the absorption by the planetary disk alone. The transit depth's upper limits in the emission lines are 11.1% for O i λ1305 Å and 5.5% for C ii λ1335 Å lines. The presence of an extended exosphere of atomic hydrogen around HD 189733b producing 5% absorption of the full unresolved Lyman-α line flux shows that the planet is losing gas. The Lyman-α light curve is well-fitted by a numerical simulation of escaping hydrogen in which the planetary atoms are pushed by the stellar radiation pressure. We constrain the escape rate of atomic hydrogen to be between 109 and 1011 g s-1 and the ionizing extreme UV flux between 2 and 40 times the solar value (1-σ), with higher escape rates corresponding to larger EUV flux. The best fit is obtained for dM/dt = 1010 g s-1 and an EUV flux FEUV = 20 times the solar value. HD 189733b is the second extrasolar planet for which atmospheric evaporation has been detected.

  7. In situ measurement of water vapor in the stratosphere with a cryogenically cooled Lyman-Alpha hygrometer

    SciTech Connect

    Schwab, J.J. ); Weinstock, E.M.; Nee, J.B.; Anderson, J.G. )

    1990-08-20

    In situ measurements of water vapor in the stratosphere with a new instrument are reported. The instrument has been designed to observe daytime water vapor from a multi-instrument balloon gondola that simultaneously measures free radicals such as OH, HO{sub 2}, and O{sub 3} in the stratosphere up to 40 km. Lyman-alpha photofragment fluorescence is used to measure water molecules in a flowing sample of ambient air. Outgassing from the interior walls of the instrument is avoided by cooling the walls with liquid nitrogen to a temperature near or below the dewpoint of the environment and by drawing air through the instrument with a fan. A brief description of the instrument is given, followed by the results of the first four balloon flights. Because frost formation in the scattering chamber resulted in a large and variable background, the data from July 15, 1987, have a relatively modest signal-to-noise ratio. The measured mixing ratio for this flight varies from 3.0-5.5 ppmv over the altitude range of 17-34 km. Adjustments in the cooling protocol for the flights of July 6, 1988, July 28, and August 25, 1989, result in a much higher signal-to-noise ratio. Profiles from these three flights are similar to, but somewhat higher, than the 1987 profile. The July 1988 and August 1989 profiles exhibit the highest mixing ratios, reaching peak values of about 6.5 ppmv near 35 km. Implications of these four measurements are discussed, as are the issues of short- and long-term variability of stratospheric water vapor.

  8. The ESO UVES advanced data products quasar sample - VI. Sub-damped Lyman α metallicity measurements and the circumgalactic medium

    NASA Astrophysics Data System (ADS)

    Quiret, S.; Péroux, C.; Zafar, T.; Kulkarni, V. P.; Jenkins, E. B.; Milliard, B.; Rahmani, H.; Popping, A.; Rao, S. M.; Turnshek, D. A.; Monier, E. M.

    2016-06-01

    The circumgalactic medium (CGM) can be probed through the analysis of absorbing systems in the line of sight to bright background quasars. We present measurements of the metallicity of a new sample of 15 sub-damped Lyman α absorbers (sub-DLAs, defined as absorbers with 19.0 < log N(H I) < 20.3) with redshift 0.584 ≤ zabs ≤ 3.104 from the ESO Ultra-Violet Echelle Spectrograph (UVES) Advanced Data Products Quasar Sample (EUADP). We combine these results with other measurements from the literature to produce a compilation of metallicity measurements for 92 sub-DLAs as well as a sample of 362 DLAs. We apply a multi-element analysis to quantify the amount of dust in these two classes of systems. We find that either the element depletion patterns in these systems differ from the Galactic depletion patterns or they have a different nucleosynthetic history than our own Galaxy. We propose a new method to derive the velocity width of absorption profiles, using the modelled Voigt profile features. The correlation between the velocity width ΔV90 of the absorption profile and the metallicity is found to be tighter for DLAs than for sub-DLAs. We report hints of a bimodal distribution in the [Fe/H] metallicity of low redshift (z < 1.25) sub-DLAs, which is unseen at higher redshifts. This feature can be interpreted as a signature from the metal-poor, accreting gas and the metal-rich, outflowing gas, both being traced by sub-DLAs at low redshifts.

  9. Exciting positronium with a solid-state UV laser: the Doppler-broadened Lyman-α transition

    NASA Astrophysics Data System (ADS)

    Deller, A.; Edwards, D.; Mortensen, T.; Isaac, C. A.; van der Werf, D. P.; Telle, H. H.; Charlton, M.

    2015-09-01

    A tunable, pulsed laser was used to excite the Lyman-α transition (1S-2P) of positronium (Ps). The laser system has a large bandwidth of Δ ν =225 GHz at λ =243 nm, providing significant coverage of the Doppler-broadened, single-photon transition. The infra-red fundamental of a Nd:YAG laser was converted to ultraviolet by a series of solid-state, nonlinear processes, centred about an unseeded optical parametric oscillator, from which the bulk of the ultimate bandwidth derives. The Ps atoms were created by bombarding mesoporous silica with positrons, and the Doppler-width of the 1S-2P transition of the resulting ensemble was measured to be Δ ν =672+/- 43 GHz (equivalent to T≈ 300 K). It is envisaged that the UV laser will be incorporated into a two-step process to efficiently form Rydberg states of Ps, with potential applications in synthesis of cold antihydrogen, gravity measurements with antimatter, or for injection of electrons and positrons into a stellarator.

  10. Iridium(I) Compounds as Prospective Anticancer Agents: Solution Chemistry, Antiproliferative Profiles and Protein Interactions for a Series of Iridium(I) N-Heterocyclic Carbene Complexes.

    PubMed

    Gothe, Yvonne; Marzo, Tiziano; Messori, Luigi; Metzler-Nolte, Nils

    2016-08-22

    A series of structurally related mono- and bis-NHC-iridium(I) (NHC: N-heterocyclic carbene) complexes have been investigated for their suitability as potential anticancer drugs. Their spectral behaviour in aqueous buffers under physiological-like conditions and their cytotoxicity against the cancer cell lines MCF-7 and HT-29 are reported. Notably, almost all complexes exhibit significant cytotoxic effects towards both cancer cell lines. In general, the cationic bis-carbene complexes show higher stability and greater anticancer activity than their neutral mono-carbene analogues with IC50 values in the high nanomolar range. Furthermore, to gain initial mechanistic insight, the interactions of these iridium(I)-NHC complexes with two model proteins, namely lysozyme and cytochrome c, were explored by HR-ESI-MS analyses. The different protein metalation patterns of the complexes can be roughly classified into two distinct groups. Those interactions give us a first idea about the possible mechanism of action of this class of compounds. Overall, our findings show that iridium(I)-NHC complexes represent very interesting candidates for further development as new metal-based anticancer drugs. PMID:27443984

  11. An extreme [O III] emitter at z = 3.2: a low metallicity Lyman continuum source

    NASA Astrophysics Data System (ADS)

    de Barros, S.; Vanzella, E.; Amorín, R.; Castellano, M.; Siana, B.; Grazian, A.; Suh, H.; Balestra, I.; Vignali, C.; Verhamme, A.; Zamorani, G.; Mignoli, M.; Hasinger, G.; Comastri, A.; Pentericci, L.; Pérez-Montero, E.; Fontana, A.; Giavalisco, M.; Gilli, R.

    2016-01-01

    Aims: Cosmic reionization is an important process occurring in the early epochs of the Universe. However, because of observational limitations due to the opacity of the intergalactic medium to Lyman continuum photons, the nature of ionizing sources is still not well constrained. While high-redshift star-forming galaxies are thought to be the main contributors to the ionizing background at z> 6, it is impossible to directly detect their ionizing emission. Therefore, looking at intermediate redshift analogues (z ~ 2-4) can provide useful hints about cosmic reionization. Methods: We investigate the physical properties of one of the best Lyman continuum emitter candidate at z = 3.212 found in the GOODS-S/CANDELS field with photometric coverage from the U to the MIPS 24 μm band and VIMOS/VLT and MOSFIRE/Keck spectroscopy. These observations allow us to derive physical properties such as stellar mass, star formation rate, age of the stellar population, dust attenuation, metallicity, and ionization parameter, and to determine how these parameters are related to the Lyman continuum emission. Results: Investigation of the UV spectrum confirms a direct spectroscopic detection of the Lyman continuum emission with S/N> 5. Non-zero Lyα flux at the systemic redshift and high Lyman-α escape fraction (fesc(Lyα) ≥ 0.78) suggest a low H i column density. The weak C and Si low-ionization absorption lines are also consistent with a low covering fraction along the line of sight. The subsolar abundances are consistent with a young and extreme starburst. The [O iii]λλ4959,5007+Hβ equivalent width (EW) is one of the largest reported for a galaxy at z> 3 (EW( [ O iii ] λλ4959,5007 + Hβ) ≃ 1600 Å, rest-frame; 6700 Å observed-frame) and the near-infrared spectrum shows that this is mainly due to an extremely strong [O iii] emission. The large observed [O iii]/[O ii] ratio (>10) and high ionization parameter are consistent with prediction from photoionization models in the

  12. Estimation of the solar Lyman alpha flux from ground based measurements of the Ca II K line

    NASA Technical Reports Server (NTRS)

    Rottman, G. J.; Livingston, W. C.; White, O. R.

    1990-01-01

    Measurements of the solar Lyman alpha and Ca II K from October 1981 to April 1989 show a strong correlation (r = 0.95) that allows estimation of the Lyman alpha flux at 1 AU from 1975 to December 1989. The estimated Lyman alpha strength of 3.9 x 10 to the 11th + or - 0.15 x 10 to the 11th photons/s sq cm on December 7, 1989 is at the same maximum levels seen in Cycle 21. Relative to other UV surrogates (sunspot number, 10.7 cm radio flux, and He I 10830 line strength), Lyman alpha estimates computed from the K line track the SME measurements well from solar maximum, through solar minimum, and into Cycle 22.

  13. Development of a Lyman-α Imaging Solar Telescope for the Satellite

    NASA Astrophysics Data System (ADS)

    Jang, M.; Oh, H.-S.; Rim, C.-S.; Park, J.-S.; Kim, J.-S.; Son, D.

    2005-09-01

    Long term observations of full-disk Lyman-α irradiance have been made by the instruments on various satellites. In addition, several sounding rockets dating back to the 1950s and up through the present have measured the Lyman-α irradiance. Previous full disk Lyman-α images of the sun have been very interesting and useful scientifically, but have been only five-minute ``snapshots" obtained on sounding rocket flights. All of these observations to date have been snapshots, with no time resolution to observe changes in the chromospheric structure as a result of the evolving magnetic field, and its effect on the Lyman-α intensity. The Lyman-α Imaging Solar Telescope(LIST) can provide a unique opportunity for the study of the sun in the Lyman-α region with the high time and spatial resolution for the first time. Up to the 2nd year development, the preliminary design of the optics, mechanical structure and electronics system has been completed. Also the mechanical structure analysis, thermal analysis were performed and the material for the structure was chosen as a result of these analyses. And the test plan and the verification matrix were decided. The operation systems, technical and scientific operation, were studied and finally decided. Those are the technical operation, mechanical working modes for the observation and safety, the scientific operation and the process of the acquired data. The basic techniques acquired through the development of satellite based solar telescope are essential for the construction of space environment forecast system in the future. The techniques which we developed through this study, like mechanical, optical and data processing techniques, could be applied extensively not only to the process of the future production of flight models of this kind, but also to the related industries. Also, we can utilize the scientific achievements which are obtained throughout the project. And these can be utilized to build a high resolution

  14. A young star-forming galaxy at z = 3.5 with an extended Lyman α halo seen with MUSE

    NASA Astrophysics Data System (ADS)

    Patrício, Vera; Richard, Johan; Verhamme, Anne; Wisotzki, Lutz; Brinchmann, Jarle; Turner, Monica L.; Christensen, Lise; Weilbacher, Peter M.; Blaizot, Jérémy; Bacon, Roland; Contini, Thierry; Lagattuta, David; Cantalupo, Sebastiano; Clément, Benjamin; Soucail, Geneviève

    2016-03-01

    Spatially resolved studies of high-redshift galaxies, an essential insight into galaxy formation processes, have been mostly limited to stacking or unusually bright objects. We present here the study of a typical (L*, M⋆ = 6 × 109 M⊙) young lensed galaxy at z = 3.5, observed with Multi Unit Spectroscopic Explorer (MUSE), for which we obtain 2D resolved spatial information of Lyα and, for the first time, of C III] emission. The exceptional signal-to-noise ratio of the data reveals UV emission and absorption lines rarely seen at these redshifts, allowing us to derive important physical properties (Te ˜ 15600 K, ne ˜ 300 cm-3, covering fraction fc ˜ 0.4) using multiple diagnostics. Inferred stellar and gas-phase metallicities point towards a low-metallicity object (Zstellar = ˜0.07 Z⊙ and ZISM < 0.16 Z⊙). The Lyα emission extends over ˜10 kpc across the galaxy and presents a very uniform spectral profile, showing only a small velocity shift which is unrelated to the intrinsic kinematics of the nebular emission. The Lyα extension is approximately four times larger than the continuum emission, and makes this object comparable to low-mass LAEs at low redshift, and more compact than the Lyman-break galaxies and Lyα emitters usually studied at high redshift. We model the Lyα line and surface brightness profile using a radiative transfer code in an expanding gas shell, finding that this model provides a good description of both observables.

  15. Feasibility of hydrogen density estimation from tomographic sensing of Lyman alpha emission

    NASA Astrophysics Data System (ADS)

    Waldrop, L.; Kamalabadi, F.; Ren, D.

    2015-12-01

    In this work, we describe the scientific motivation, basic principles, and feasibility of a new approach to the estimation of neutral hydrogen (H) density in the terrestrial exosphere based on the 3-D tomographic sensing of optically thin H emission at 121.6 nm (Lyman alpha). In contrast to existing techniques, Lyman alpha tomography allows for model-independent reconstruction of the underlying H distribution in support of investigations regarding the origin and time-dependent evolution of exospheric structure. We quantitatively describe the trade-off space between the measurement sampling rate, viewing geometry, and the spatial and temporal resolution of the reconstruction that is supported by the data. We demonstrate that this approach is feasible from either earth-orbiting satellites such as the stereoscopic NASA TWINS mission or from a CubeSat platform along a trans-exosphere trajectory such as that enabled by the upcoming Exploration Mission 1 launch.

  16. Competition between pressure and gravity confinement in Lyman Alpha forest observations

    NASA Technical Reports Server (NTRS)

    Charlton, Jane C.; Salpeter, Edwin E.; Linder, Suzanne M.

    1994-01-01

    A break in the distribution function of Lyman Alpha clouds (at a typical redshift of 2.5) has been reported by Petit-jean et al. (1993). This feature is what would be expected from a transition between pressure confinement and gravity confinement (as predicted in Charlton, Salpeter & Hogan 1993). The column density at which the feature occurs has been used to determine the external confining pressure approximately 10 per cu cm K, which could be due to a hot, intergalactic medium. For models that provide a good fit to the data, the contribution of the gas in clouds to omega is small. The specific shape of the distribution function at the transition (predicted by models to have a nonmonotonic slope) can serve as a diagnostic of the distribution of dark matter around Lyman Alpha forest clouds, and the present data already eliminate certain models.

  17. Polar solar wind and interstellar wind properties from interplanetary Lyman-alpha radiation measurements

    NASA Technical Reports Server (NTRS)

    Witt, N.; Blum, P. W.; Ajello, J. M.

    1981-01-01

    The analysis of Mariner 10 observations of Lyman-alpha resonance radiation shows an increase of interplanetary neutral hydrogen densities above the solar poles. This increase is caused by a latitudinal variation of the solar wind velocity and/or flux. Using both the Mariner 10 results and other solar wind observations, the values of the solar wind flux and velocity with latitude are determined for several cases of interest. The latitudinal variation of interplanetary hydrogen gas, arising from the solar wind latitudinal variation, is shown to be most pronounced in the inner solar system. From this result it is shown that spacecraft Lyman-alpha observations are more sensitive to the latitudinal anisotropy for a spacecraft location in the inner solar system near the downwind axis.

  18. Lyman-alpha imagery of comet Kohoutek, and far-UV magnitudes of stars

    NASA Technical Reports Server (NTRS)

    Page, T.

    1974-01-01

    The Apollo-16 S201 electronographic camera backup model was modified for use on the Skylab AMS-SAL, which reduced its 20 deg FOV to about 7 deg unvignetted. Over 500 frames were exposed by automatic sequencer through LiF and CaF2. The Lyman-alpha halo of comet Kohoutek has been analyzed for nine occasions, and its long, pointed tail was imaged in 1250-1600 A only near perihelion. Far-UV magnitudes and colors are being derived for about 200 stars, nebulae, and galaxies. Redshifted Lyman-alpha emission from intergalactic atomic hydrogen was not detected in 7 clusters of galaxies. About 25% of the exposed frames were degraded by water damage, electrical discharges, decline in photocathode sensitivity, and loss of AMS mirror reflectance.

  19. Lyman-alpha measurements of neutral hydrogen in the outer geocorona and in interplanetary space.

    NASA Technical Reports Server (NTRS)

    Thomas, G. E.; Bohlin, R. C.

    1972-01-01

    Results of hydrogen Lyman-alpha (1216 A) measurements made on a continuous basis by a two-channel photometer on Ogo 5 from March 1968 to June 1971. The highly elliptical orbit provided measurements of both the outer geocorona and of the 1216-A sky background emission, since geocoronal scattering is minimal at the apogee distance of 150,000 km. Selected data (through 1970) are presented, as well as an interpretation of the three principal discoveries to date - namely, (1) a pronounced antisolar enhancement of the geocoronal scattering beyond 70,000 km, which is regarded as evidence for a hydrogen 'geotail' produced by solar Lyman-alpha radiation pressure; (2) a clear correlation of periodic variations in the sky background emission with solar activity associated with solar rotation; and (3) an annual variation of the 1216-A sky background emission, caused by the earth's orbital motion within the cavity created by the solar wind in the nearby interstellar hydrogen.

  20. Self-regulating galaxy formation. Part 1: HII disk and Lyman alpha pressure

    NASA Technical Reports Server (NTRS)

    Cox, D. P.

    1983-01-01

    Assuming a simple but physically based prototype for behavior of interstellar material during formation of a disk galaxy, coupled with the lowest order description of infall, a scenario is developed for self-regulated disk galaxy formation. Radiation pressure, particularly that of Lyman depha (from fluorescence conversion Lyman continuum), is an essential component, maintaining an inflated disk and stopping infall when only a small fraction of the overall perturbation has joined the disk. The resulting galaxies consist of a two dimensional family whose typical scales and surface density are expressable in terms of fundamental constants. The model leads naturally to galaxies with a rich circumgalactic environment and flat rotation curves (but is weak in its analysis of the subsequent evolution of halo material).

  1. Dust properties of Lyman-break galaxies at z ~ 3

    NASA Astrophysics Data System (ADS)

    Álvarez-Márquez, J.; Burgarella, D.; Heinis, S.; Buat, V.; Lo Faro, B.; Béthermin, M.; López-Fortín, C. E.; Cooray, A.; Farrah, D.; Hurley, P.; Ibar, E.; Ilbert, O.; Koekemoer, A. M.; Lemaux, B. C.; Pérez-Fournon, I.; Rodighiero, G.; Salvato, M.; Scott, D.; Taniguchi, Y.; Vieira, J. D.; Wang, L.

    2016-03-01

    Context. Since the mid-1990s, the sample of Lyman-break galaxies (LBGs) has been growing thanks to the increasing sensitivities in the optical and in near-infrared telescopes for objects at z> 2.5. However, the dust properties of the LBGs are poorly known because the samples are small and/or biased against far-infrared (far-IR) or submillimeter (submm) observations. Aims: This work explores from a statistical point of view the far-IR and submm properties of a large sample of LBGs at z ~ 3 that cannot be individually detected from current far-IR observations. Methods: We select a sample of 22, 000 LBGs at 2.5

  2. Performance Characterization of UV Science Cameras Developed for the Chromospheric Lyman-Alpha Spectro-Polarimeter

    NASA Technical Reports Server (NTRS)

    Champey, Patrick; Kobayashi, Ken; Winebarger, Amy; Cirtain, Jonathan; Hyde, David; Robertson, Bryan; Beabout, Brent; Beabout, Dyana; Stewart, Mike

    2014-01-01

    The NASA Marshall Space Flight Center (MSFC) has developed a science camera suitable for sub-orbital missions for observations in the UV, EUV and soft X-ray. Six cameras will be built and tested for flight with the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP), a joint National Astronomical Observatory of Japan (NAOJ) and MSFC sounding rocket mission. The goal of the CLASP mission is to observe the scattering polarization in Lyman-alpha and to detect the Hanle effect in the line core. Due to the nature of Lyman-alpha polarization in the chromosphere, strict measurement sensitivity requirements are imposed on the CLASP polarimeter and spectrograph systems; science requirements for polarization measurements of Q/I and U/I are 0.1 percent in the line core. CLASP is a dual-beam spectro- polarimeter, which uses a continuously rotating waveplate as a polarization modulator, while the waveplate motor driver outputs trigger pulses to synchronize the exposures. The CCDs are operated in frame-transfer mode; the trigger pulse initiates the frame transfer, effectively ending the ongoing exposure and starting the next. The strict requirement of 0.1 percent polarization accuracy is met by using frame-transfer cameras to maximize the duty cycle in order to minimize photon noise. Coating the e2v CCD57-10 512x512 detectors with Lumogen-E coating allows for a relatively high (30 percent) quantum efficiency at the Lyman-alpha line. The CLASP cameras were designed to operate with a gain of 2.0 +/- 0.5, less than or equal to 25 e- readout noise, less than or equal to 10 e-/second/pixel dark current, and less than 0.1percent residual non-linearity. We present the results of the performance characterization study performed on the CLASP prototype camera; system gain, dark current, read noise, and residual non-linearity.

  3. Performance Characterization of UV Science Cameras Developed for the Chromospheric Lyman-Alpha Spectro-Polarimeter

    NASA Technical Reports Server (NTRS)

    Champey, P.; Kobayashi, K.; Winebarger, A.; Cirtain, J.; Hyde, D.; Robertson, B.; Beabout, D.; Beabout, B.; Stewart, M.

    2014-01-01

    The NASA Marshall Space Flight Center (MSFC) has developed a science camera suitable for sub-orbital missions for observations in the UV, EUV and soft X-ray. Six cameras will be built and tested for flight with the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP), a joint National Astronomical Observatory of Japan (NAOJ) and MSFC sounding rocket mission. The goal of the CLASP mission is to observe the scattering polarization in Lyman-alpha and to detect the Hanle effect in the line core. Due to the nature of Lyman-alpha polarization in the chromosphere, strict measurement sensitivity requirements are imposed on the CLASP polarimeter and spectrograph systems; science requirements for polarization measurements of Q/I and U/I are 0.1 percent in the line core. CLASP is a dual-beam spectro-polarimeter, which uses a continuously rotating waveplate as a polarization modulator, while the waveplate motor driver outputs trigger pulses to synchronize the exposures. The CCDs are operated in frame-transfer mode; the trigger pulse initiates the frame transfer, effectively ending the ongoing exposure and starting the next. The strict requirement of 0.1 percent polarization accuracy is met by using frame-transfer cameras to maximize the duty cycle in order to minimize photon noise. Coating the e2v CCD57-10 512x512 detectors with Lumogen-E coating allows for a relatively high (30 percent) quantum efficiency at the Lyman-alpha line. The CLASP cameras were designed to operate with 10 e-/pixel/second dark current, 25 e- read noise, a gain of 2.0 +/- 0.5 and 1.0 percent residual non-linearity. We present the results of the performance characterization study performed on the CLASP prototype camera; dark current, read noise, camera gain and residual non-linearity.

  4. Calculation of the quasi-energies and resonances behavior of the hydrogen Lyman-alpha problem

    NASA Technical Reports Server (NTRS)

    Ruyten, Wilhelmus M.

    1992-01-01

    Recently, Bakshi and Kalman presented numerical results for the quasi-energies of the n = 2 multiplet in the hydrogen Lyman-alpha transition for a plasma in which both strong static and oscillating electric fields are present. Recent work on related magnetic and optical resonance problems provides a simplified mathematical treatment, as well as greater insight into the complex resonance behavior of this interaction.

  5. More confirmed damped Lyman-Alpha systems from the Las Campanas/Palomar survey

    NASA Technical Reports Server (NTRS)

    Lu, Limin; Wolfe, Arthur M.

    1994-01-01

    We present moderate-resolution spectra of six high-redshift quasars which contain nine candidate damped Lyman alpha absorption systems identified in the Las Campanas/Palomar survey of Lanzetta et al. (ApJS, 77, 1 (1991)). Eight of the nine candidate damped Lyman alpha absorption systems are confirmed (one tentative), including seven with N(H I) greater than or equal to 2 x 10(exp 20) /sq cm. The remaining one turns out to be due to blending of many narrow absorption lines. Accurate absorption redshifts, H I column densities, and metal-line equivalent widths are provided for these systems in order to facilitate future studies of detailed physical condition and chemical abundances. We briefly discuss the 18 other metal-line systems identified along these sight lines. The z(sub abs) = 2.6527 system toward Q 2231-00 is interesting in that it shows strong O VI (lambda) (lambda) 1031, 1037 absorption. The O VI ion is one of the best diagnostics of hot gas, and high resolution studies of the O VI absorption is likely to yield important clues regarding the ionization mechanism of the metal-line systems. Another system, at z(sub abs) = 2.3771 toward Q 2239-38, shows relatively strong Zn II and Cr II absorption, clearly indicating that it belongs to the same class absorbers as the damped Lyman systems. We have not obtained metal abundances for this system because the H(sub I) column density is not available. We also find a Lyman limit absorption system at z(sub abs)= 3.5090 toward Q 2239-38 which does not show obvious metal absorption lines. More sensitive observations are required to check on this interesting possibility.

  6. More confirmed damped Lyman-Alpha systems from the Las Campanas/Palomar survey

    NASA Astrophysics Data System (ADS)

    Lu, Limin; Wolfe, Arthur M.

    1994-07-01

    We present moderate-resolution spectra of six high-redshift quasars which contain nine candidate damped Lyman alpha absorption systems identified in the Las Campanas/Palomar survey of Lanzetta et al. (ApJS, 77, 1 (1991)). Eight of the nine candidate damped Lyman alpha absorption systems are confirmed (one tentative), including seven with N(H I) greater than or equal to 2 x 1020 /sq cm. The remaining one turns out to be due to blending of many narrow absorption lines. Accurate absorption redshifts, H I column densities, and metal-line equivalent widths are provided for these systems in order to facilitate future studies of detailed physical condition and chemical abundances. We briefly discuss the 18 other metal-line systems identified along these sight lines. The zabs = 2.6527 system toward Q 2231-00 is interesting in that it shows strong O VI (lambda) (lambda) 1031, 1037 absorption. The O VI ion is one of the best diagnostics of hot gas, and high resolution studies of the O VI absorption is likely to yield important clues regarding the ionization mechanism of the metal-line systems. Another system, at zabs = 2.3771 toward Q 2239-38, shows relatively strong Zn II and Cr II absorption, clearly indicating that it belongs to the same class absorbers as the damped Lyman systems. We have not obtained metal abundances for this system because the HI column density is not available. We also find a Lyman limit absorption system at zabs= 3.5090 toward Q 2239-38 which does not show obvious metal absorption lines. More sensitive observations are required to check on this interesting possibility.

  7. Heliospheric interface modifications of interstellar neutral hydrogen compatible with Lyman alpha glow observations

    NASA Astrophysics Data System (ADS)

    Quemerais, E.; Lallement, R.; Bertaux, J. L.

    1992-11-01

    The paper presents results of calculations performed to interpret the interplanetary Lyman-alpha line shape measurements acquired aboard Prognoz 5 and 6 in 1976 and 1977. It is shown that some discrepancies between the Prognoz 5/6 data and a standard homogeneous model are alleviated when initial (far from the sun) velocity and temperature distributions varying with the distance to the stagnation line are considered.

  8. Fermi acceleration of Lyman-alpha photons by shocks

    NASA Technical Reports Server (NTRS)

    Neufeld, David A.; Mckee, Christopher F.

    1988-01-01

    The repeated scattering of Ly-alpha radiation across a shock front results in a systematic blueshift which may greatly exceed the shock velocity vs and is proportional to cube root of (Nvs), where N is the column density of hydrogen atoms on either side of the shock front. The blueshifting process is similar to the Fermi acceleration of cosmic rays and may be responsible for the blue asymmetric line profiles that have been observed in high-redshift Ly-alpha galaxies. The Ly-alpha line profile in 3C 326.1 is accounted for by a model in which shocks, driven into a population of interstellar clouds by a radio lobe, trigger the formation of ionizing stars and Fermi accelerate the Ly-alpha radiation emitted by H II regions surrounding those stars. Galaxy mergers, particularly between galaxies with low dust content, should produce Ly-alpha lines with strong blue wings.

  9. Lyman Alpha Blobs in a Filament at z=2.38

    NASA Technical Reports Server (NTRS)

    Williger, G.; Francis, P.; Mushotzky, R.; Palunas, P.; Teplitz, H.; Weaver, K.; White, R.; Woodgate, B.

    2004-01-01

    Bright, extended Lyman-alpha nebulae (known as blobs) appear to be common in the densest environments at high redshift, and may be an important stage in galaxy evolution. Up to now, Chandra data have not distinguished between the possible excitation mechanisms, but suggest that we are seeing dense excitation mechanisms, but suggest that we are seeing dense intracluster gas either falling into forming galaxies (cooling flows) or being expelled into the intracluster medium, enriching it. Optical and X-ray evidence also suggests that some blobs harbor AGN. We took a 20 ksec exposure with Chandra of four Lyman-alpha blobs in a large filament at $z=2.38$, which completed the X-ray observations of all currently known blobs. We will present flux constraints for the blobs from the Chandra data and optical spectra of the field taken with the AAT+2dF (see accompanying poster by Woodgate et al.). Possible mechanisms for the extended emission of the Lyman-alpha blobs will be discussed.

  10. Latitudinal distribution of solar wind as deduced from Lyman alpha measurements - an improved method

    NASA Astrophysics Data System (ADS)

    Summanen, T.; Lallement, R.; Bertaux, J. L.; Kyrola, E.

    1993-08-01

    In this work we examine the possibility of deducing the latitudinal distribution of the solar ionization rate using Prognoz 6 Lyman-alpha data in a more general and flexible way than previously examined. Using a so-called hot model for the hydrogen distribution and the optically thin model for the resonance scattering, theoretical Lyman-alpha intensity for the interstellar hydrogen is calculated and compared with the intensity data measured by Prognoz 6. Varying the latitudinal dependence of the ionization rate, the distributions which produce the best fit with the data are analyzed for four different measuring sessions. As a result, we get four ionization rate distributions that have two common features. The ionization rate is enhanced near the solar equator, and large broad plateaus exist around heliographic latitudes +/- 30 to +/- 70 deg. The latitudinal distribution of the average ionization rate about the solar minimum deviates clearly from the spherically symmetric and sinusoidally with the latitude-varying models used so far. The growth of the solar wind mass flux from the solar polar areas toward the equator corresponds to the earlier results found from Lyman-alpha measurements.

  11. The Lyman-alpha Solar Telescope for the ASO-S

    NASA Astrophysics Data System (ADS)

    Li, Hui

    2015-08-01

    The Lyman-alpha Solar Telescope (LST) is one of the payloads for the proposed Space-Borne Advanced Solar Observatory (ASO-S). LST consists of a Solar Disk Imager (SDI) with a field-of-view (FOV) of 1.2 Rsun, a Solar Corona Imager (SCI) with an FOV of 1.1 - 2.5 Rsun, and a full-disk White-light Solar Telescope (WST) with an FOV of 1.2 Rsun, which also serves as the guiding telescope. The SCI is designed to work at the Lyman-alpha waveband and white-light, while the SDI will work at the Lyman-alpha waveband only. The WST works both in visible (for guide) and ultraviolet (for science) white-light. The LST will observe the Sun from disk-center up to 2.5 solar radii for both solar flares and coronal mass ejections. In this presentation, I will give an introduction to LST, including scientific objectives, science requirement, instrument design and current status.

  12. Mapping of the Moon in the Ultraviolet: the Lyman Alpha Mapping Project

    NASA Astrophysics Data System (ADS)

    Horvath, D. G.; Retherford, K. D.; Gladstone, G. R.; Stern, S. A.; Egan, A. F.; Miles, P. F.; Parker, J. Wm.; Greathouse, T. K.; Davis, M. W.; Slater, D. C.; Kaufmann, D. E.; Versteeg, M. H.; Feldman, P. D.; Hurley, D. M.; Pryor, W. R.; Hendrix, A. R.

    2010-10-01

    The Lyman Alpha Mapping Project (LAMP) is an ultraviolet (UV) spectrograph on the Lunar Reconnaissance Orbiter (LRO) that is designed to map the lunar albedo at far-UV wavelengths. LAMP primarily measures interplanetary HI Lyman-alpha sky-glow and FUV starlight reflected from the night-side lunar surface, including permanently shadowed regions (PSRs) near the poles. Dayside observations are also obtained. Calibration data, collected monthly, will monitor instrument functionality. Brightness maps sorted by wavelength (including the Lyman-alpha wavelength of 121.6 nm) are reported for the polar regions, with a few regions of interest reported in more detail. LAMP's spectral range of 58 nm to 196 nm includes a water ice spectral feature near 160 nm, which provides a diagnostic tool for detecting water on the lunar surface that is complementary to recent discoveries using infrared and radio frequency techniques. Progress towards producing far-UV albedo maps and searching for water ice signatures will be reported. We'll discuss how LAMP data may address questions regarding how water is formed on the moon, transported through the lunar atmosphere, and deposited in the PSRs.

  13. Understanding the Large Scale Clustering of the Lyman-alpha Forest

    NASA Astrophysics Data System (ADS)

    Cieplak, Agnieszka; Slosar, Anze; Khandai, Nishikanta

    2015-04-01

    The Lyman-alpha forest has become a powerful probe of cosmological parameters by measuring large scale structure at intermediate redshift. With upcoming surveys increasing the scope of these measurements, understanding of the bias between the measured flux and the underlying matter power spectrum is becoming crucial to the percent level cosmological interpretation of these observations. We therefore employ cosmological hydrodynamic simulations to study the response of the Lyman-alpha forest clustering to large wavelength modes of the underlying matter large-scale structure and compare these to previous theoretical studies of this bias which used only N-body and hydro-PM simulations. We demonstrate this response by evolving smaller, curved universe cosmologies, representing the same universe with different overdense patches, and we use these to study the assumption of the analytical bias formula derived by Seljak (2012). A full theoretical understanding of this bias is important to fully understand the clustering of the Lyman-alpha forest and its cosmological implications.

  14. The Lyman Alpha Imaging-Monitor Experiment (LAIME) for TESIS/CORONAS-PHOTON

    NASA Astrophysics Data System (ADS)

    Damé, L.; Koutchmy, S.; Kuzin, S.; Lamy, P.; Malherbe, J.-M.; Noëns, J.-C.

    LAIME the Lyman Alpha Imaging-Monitor Experiment is a remarkably simple no mechanisms and compact 100x100x400 mm full Sun imager to be flown with TESIS on the CORONAS-PHOTON mission launch expected before mid-2008 As such it will be the only true chromospheric imager to be flown in the next years supporting TESIS EUV-XUV imaging SDO and the Belgian LYRA Lyman Alpha flux monitor on the ESA PROBA-2 microsatellite launch expected in September 2007 We will give a short description of this unique O60 mm aperture imaging telescope dedicated to the investigating of the magnetic sources of solar variability in the UV and chromospheric and coronal disruptive events rapid waves Moreton waves disparitions brusques of prominences filaments eruptions and CMEs onset The resolution pixel is 2 7 arcsec the field of view 1 4 solar radius and the acquisition cadence could be as high as 1 image minute The back thinned E2V CCD in the focal plane is using frame transfer to avoid shutter and mechanisms Further more the double Lyman Alpha filtering allows a 40 AA FWHM bandwidth and excellent rejection yet providing a vacuum seal design of the telescope MgF2 entrance window Structural stability of the telescope focal length 1 m is preserved by a 4-INVAR bars design with Aluminium compensation in a large pm 10 o around 20 o

  15. Comparison of electron width models for fast line profile calculations

    NASA Astrophysics Data System (ADS)

    Iglesias, Carlos A.

    2016-03-01

    The first non-vanishing term in the perturbation expansion of the electron contribution to the line width, commonly used in spectral line broadening by plasmas, was previously expressed in terms of the thermally averaged bremsstrahlung Gaunt factor. The approximations in the derivation, however, suggest that the result is uncertain. The electron width formula is tested with the hydrogen Balmer series and found suspect. Calculations for the He II Lyman series also display similar difficulties. The limitation of this electron width formulation is traced to the absence of an explicit strong collision cutoff beyond which the second-order theory is invalid.

  16. Assiniboine Series.

    ERIC Educational Resources Information Center

    Allen, Minerva

    This series of illustrated booklets presents 13 Indian stories in a bilingual format of English and Assiniboine, an Indian tribal language. Written on the first grade level, the stories have the following titles: (1) "Orange Tree in Lodgepole"; (2) "Pretty Flower"; (3) Inktomi and the Rock"; (4) "Inktomi and the Ducks"; (5) "Inktomi and the…

  17. Properties of high-redshift Lyman-alpha clouds. I - Statistical analysis of the Schneider-Schmidt-Gunn quasars

    NASA Technical Reports Server (NTRS)

    Press, William H.; Rybicki, George B.; Schneider, Donald P.

    1993-01-01

    Techniques for statistical analysis of the Lyman-alpha forest in high-redshift quasars are developed, and applied to the low-resolution (25 A) spectra of 29 of the 33 quasars in the Schneider-Schmidt-Gunn sample. We extrapolate each quasar's continuum shortward of Lyman-alpha emission, then consider each spectral bin of each quasar to be an (approximately) independent measurement of the absorption due to the Lyman-alpha clouds. With several thousand such measurements thus available, we can obtain good determinations of some interesting properties of clouds in the redshift range 2.5-4.3 without actually resolving any single cloud. We find that the mean absorption increases with z approximately as a power law (1 + z) exp (gamma + 1) with gamma = 2.46 +/- 0.37. The mean ratio of Lyman-alpha to Lyman-beta absorption in the clouds is 0.476 +/- 0.054. We also detect, and obtain ratios, for Lyma-gamma, delta, and possibly epsilon.

  18. KECK SPECTROSCOPY OF FAINT 3>z>7 LYMAN BREAK GALAXIES: A HIGH FRACTION OF LINE EMITTERS AT REDSHIFT SIX

    SciTech Connect

    Stark, Daniel P.; Ellis, Richard S.; Ouchi, Masami

    2011-02-10

    As Ly{alpha} photons are scattered by neutral hydrogen, a change with redshift in the Ly{alpha} equivalent width (EW) distribution of distant galaxies offers a promising probe of the degree of ionization in the intergalactic medium and hence when cosmic reionization ended. This simple test is complicated by the fact that Ly{alpha} emission can also be affected by variations in the kinematics and dust content of the host galaxies. In the first paper in this series, we demonstrated both a luminosity- and redshift-dependent trend in the fraction of Ly{alpha} emitters seen within color-selected 'Lyman break' galaxies (LBGs) over the range 3 < z < 6; lower luminosity galaxies and those at higher redshift show an increased likelihood of strong emission. Here, we present the results from 12.5 hr exposures with the Keck DEIMOS spectrograph focused primarily on LBGs at z {approx_equal} 6 which enable us to confirm the redshift dependence of line emission more robustly and to higher redshift than was hitherto possible. We find that 54% {+-} 11% of faint z {approx_equal} 6 LBGs show strong (W{sub Ly{alpha},0}>25 A) emission, an increase of 55% from a sample of similarly luminous z {approx_equal} 4 galaxies. With a total sample of 74 z {approx_equal} 6 LBGs, we determine the luminosity-dependent Ly{alpha} EW distribution. Assuming continuity in these trends to the new population of z {approx_equal} 7 sources located with the Hubble WFC3/IR camera, we predict that unless the neutral fraction rises in the intervening 200 Myr, the success rate for spectroscopic confirmation using Ly{alpha} emission should be high.

  19. The Spacelab Lyman alpha and white light coronagraphs program

    NASA Technical Reports Server (NTRS)

    Kohl, J. L.; Withbroe, G. L.; Weiser, H.; Macqueen, R. M.; Munro, R. H.

    1981-01-01

    The Harvard-Smithsonian Center for Astrophysics and the High Altitude Observatory have defined a joint coronagraphs experiment for a future Spacelab mission. The instrumentation package would include an ultraviolet light coronagraph to measure the intensity and profiles of spectral lines formed between 1.2 and 8 solar radii from sun center and a white light coronagraph to measure the intensity and polarization of visible light. The overall goals of the joint program are to use new coronal plasma diagnostic techniques to understand the physical processes and mechanisms operating in the solar corona, to understand the acceleration of high-speed and low-speed solar wind streams and to extrapolate this knowledge to other stars in order to help understand the physics of stellar coronae and stellar mass loss.

  20. Detection of auroral hydrogen Lyman-Alpha emission from Uranus

    SciTech Connect

    Clarke, J.T.

    1982-12-15

    A series of observations of Uranus obtained with the short-wavelength spectrographs of the International Ultraviolet Explorer Observatory in 1982 April and June have revealed unexpectedly strong H Ly..cap alpha.. emission which varied between 430 and 850 Rayleighs in observed disk-averaged brightness over the course of these observations. The variability of the emission alone indicates that much of the emission must be produced by charged particle excitation of H in Uranus's upper atmosphere. In addition, comparison of these data with a model for resonant scattering of solar H Ly..cap alpha.. emission indicates that, over a wide range of model conditions, an emission brightness of even 430 Rayleighs (which was the lowest observed value) corresponds to an H column density on the order of 10/sup 17/ cm/sup -2/ in Uranus's upper atmosphere. At 20 AU from the Sun, solar EUV photodissociation of H/sub 2/ is insufficient to produce such a high column abundance of H, further supporting the identification of charged particle precipitation in Uranus's upper atmosphere. These data thus offer the first strong evidence for the presence of aurorae and therefore a magnetic field on Uranus.

  1. Constraining the temperature-density relation of the intergalactic medium with the Lyman α and β forests

    NASA Astrophysics Data System (ADS)

    Boera, Elisa; Murphy, Michael T.; Becker, George D.; Bolton, James S.

    2016-02-01

    The post-reionization thermal state of the intergalactic medium is characterized by a power-law relationship between temperature and density, with a slope determined by the parameter γ. We describe a new method to measure γ using the ratio of flux curvature in the Lyman α and β forests. At a given redshift, this curvature ratio incorporates information from the different gas densities traced by Lyman α and β absorption. It is relatively simple and fast to compute and appears robust against several observational uncertainties. We apply this technique to a sample of 27 high-resolution quasar spectra from the Very Large Telescope. While promising statistical errors on γ appear to be achievable with these spectra, to reach its full potential, the dependence of the curvature ratio on the thermal state of the gas in the foreground Lyman α forest will require further, detailed forward modelling.

  2. New Horizons Alice sky Lyman-α at Pluto encounter: Importance for photochemistry

    NASA Astrophysics Data System (ADS)

    Retherford, K. D.; Gladstone, R.; Stern, S. A.; Weaver, H. A., Jr.; Young, L. A.; Olkin, C.; Cheng, A. F.; Greathouse, T.; Kammer, J.; Linscott, I.; Parker, A. H.; Parker, J. W.; Schindhelm, E.; Singer, K. N.; Steffl, A.; Strobel, D. F.; Summers, M. E.; Tsang, C.; Tyler, G. L.; Versteeg, M.; Woods, W. W.; Ennico Smith, K.; Hinson, D. P.; Pryor, W. R.; Cunningham, N. J.; Curdt, W.

    2015-12-01

    The third zone of our solar system, including the Pluto system, has a unique illumination environment at UV wavelengths. While direct solar Lyman-α emissions dominate the signal at 121.6 nm at classical solar system distances, the contribution of illumination by Interplanetary Medium (IPM) Lyman-α sky-glow is roughly on par at Pluto (Gladstone et al. 2015). The Pluto-Alice UV imaging spectrograph on New Horizons conducted several dedicated sky scans to measure the IPM Lyman-α both en route to and while at Pluto. These scans provide 6° by 360° great-circle swaths while spinning the spacecraft. Three sets of scans conducted en route are reported in Gladstone et al. (2012). During the Pluto encounter, sets of scans with six such swaths evenly spaced ~30° apart for all-sky coverage were obtained just before closest approach and again just after. These measurements agree well with brightness variations expected for IPM brightnesses peaking in the sunward direction and interspersed with detections of UV bright stars and other sky features. Previous studies estimated contributions of ~2/3rds direct solar Lyα and 1/3rd IPM Lyα. Our early results suggest that these model predictions need revision. These findings have important implications for determining the rates of photochemical reactions within Pluto's atmosphere that are driven by UV photons at 121.6 nm. Similarly, new constraints are provided to the rates of photolysis on Charon's polar winter nightside. These constraints are useful for understanding the volatile transport and long-term stability of the dark red region near Charon's pole discovered by New Horizons.

  3. A Critical Test of the Nature of Lyman Continuum Emission at z~3

    NASA Astrophysics Data System (ADS)

    Shapley, Alice

    2012-10-01

    Escaping Lyman-continuum {LyC} radiation from star-forming galaxies is likely responsible for the reionization of the universe. However, the direct measurement of escaping LyC radiation has proven exceptionally challenging. Recent spectroscopic and imaging detections of LyC emission from z 3 galaxies have revealed unexpectedly high values for the escape fraction of LyC photons, as well as spatial offsets between the apparent LyC emission and non-ionizing UV continuum. These results may indicate the processes governing the production and escape of LyC photons from distant star-forming galaxies, but may also signify contamination by low-redshift interlopers near the line of sight. We have obtained ultra-deep ground-based data probing the LyC region at z 2.85 in the Q1549+19 field. Our sample includes both spectroscopically confirmed Lyman Break Galaxies {LBGs} and Lyman-Alpha Emitters {LAEs}, with 24 apparent detections of LyC radiation. However, without high spatial resolution redshift estimates for the specific regions associated with apparent LyC emission in the vicinity of LBGs and LAEs, our interpretation of these intriguing sources is fundamentally limited. Spatially-resolved photometric redshifts based on multi-band HST imaging represents the most effective path forward. Here we propose for 32 orbits of deep WFC3/F336W, ACS/F606W, WFC3/F125W, and WFC3/160W observations in two pointings covering the majority of our apparent LyC detections. Analysis of these data will robustly remove contamination from low-redshift interlopers, and reveal the processes through which galaxies reionized the universe and maintained the ionizing background.

  4. Searching for Lyman alpha emission from a possible Zel'dovich pancake

    NASA Technical Reports Server (NTRS)

    Cox, Caroline; Schulman, Eric; Bregman, Joel N.

    1993-01-01

    The detection of 2 x 10(exp 14) solar mass of neutral hydrogen at a redshift of 3.397 has been reported. Top-down theories of structure formation predict such a mass of hydrogen collapsing to form a protocluster of galaxies. We sought to observe this object in Lyman-alpha, which could be produced through ionization by the metagalactic ionizing radiation field or through internal ionization processes. On 29 Apr. 1992, the region of the reported HI emission for 1800 seconds with the 1.3 meter McGraw-Hill reflector at Michigan-Dartmouth-M.I.T. Observatory was observed. Because the H1 emission reported has a transverse scale of 300 sec, a 1/3.06 reducing camera and a Thomson CCD were used to obtain a field of view of about 600 sec by 840 sec. A filter 88 A wide, centered at 5354 A was used; Lyman-alpha emission at z = 3.4 is redshifted to 5347 A. In order to avoid saturating the CCD with a bright star in the field, nine 200 second exposures were taken. The combination of these images shows no obvious extended Lyman-alpha emission at a level of about 28 magnitudes per square arcsecond. The field observed also shows a distant cluster of galaxies. In order to determine if the cluster could in any way be associated with the cloud of neutral hydrogen at z = 3.4, we sought to estimate its redshift from the size and magnitude of the galaxies and of the cluster as a whole. Omega = 1 and H(sub O) = 50 km s(sup -1) Mpc(sup -1) were adopted; our redshift estimates range from z = 0.2 to z = 0.6. The cluster is clearly not associated with the HI cloud at z = 3.4.

  5. The Lyman continuum escape fraction of low mass star-forming galaxies at z~1.

    NASA Astrophysics Data System (ADS)

    Rutkowski, Michael J.; Scarlata, Claudia; Haardt, Francesco; Siana, Brian D.; Rafelski, Marc; Henry, Alaina L.; Hayes, Matthew; Salvato, Mara; Pahl, Anthony; Mehta, Vihang; Beck, Melanie; Malkan, Matthew Arnold; Teplitz, Harry I.

    2016-01-01

    Star-forming galaxies (SFGs) in the high redshift universe (z>6) are believed to ionize neutral hydrogen in the intergalactic medium during the epoch of reionization. We tested this assumption by studying likely analogs of these SFGs in archival HST grism spectroscopy with GALEX UV and ground-based optical images at the redshift range in which we can directly measure the rest-frame Lyman continuum (λ<912Å, LyC) emission. We selected ~1400 SFGs for study on the presence of strong Hα emission and strongly selected against those SFGs whose GALEX FUV photometry could be contaminated by low redshift interlopers along the line of sight to produce a sample of ~600 z~1 SFGs. We made no unambiguous detection of escaping Lyman continuum radiation in individual galaxies in this sample, and stacked the individual non-detections in order to constrain the absolute Lyman continuum escape fraction, fesc<2% (3σ). We sub-divided this sample and stacked SFGs to measure upper limits to fesc with respect to stellar mass,luminosity and relative orientation. For z~1 high Hα equivalent width (EW>200Å) SFGs, we found for the first time an upper limit to fesc<9%. We discuss the implications of these limits for the ionizing emissivity of high redshift SFGs during the epoch of reionization. We conclude that reionization by SFGs is only marginally consistent with independent Planck observations of the CMB electron scattering opacity unless the LyC escape fraction of SFGs increases with redshift and an unobserved population of faint (MUV<-13 AB) SFGs contributes significantly to the UV background.

  6. A SPECTROSCOPIC SEARCH FOR LEAKING LYMAN CONTINUUM AT z {approx} 0.7

    SciTech Connect

    Bridge, Carrie R.; Siana, Brian; Salvato, Mara; Rudie, Gwen C.; Teplitz, Harry I.; Scarlata, Claudia; Colbert, James; Armus, Lee; Conselice, Christopher J.; Ferguson, Henry C.; Brown, Thomas M.; Giavalisco, Mauro; De Mello, Duilia F.; Gardner, Jonathan P.

    2010-09-01

    We present the results of rest-frame, UV slitless spectroscopic observations of a sample of 32 z {approx} 0.7 Lyman break galaxy (LBG) analogs in the COSMOS field. The spectroscopic search was performed with the Solar Blind Channel on the Hubble Space Telescope. We report the detection of leaking Lyman continuum (LyC) radiation from an active galactic nucleus-starburst composite. While we find no direct detections of LyC emission in the remainder of our sample, we achieve individual lower limits (3{sigma}) of the observed non-ionizing UV-to-LyC flux density ratios, f{sub {nu}} (1500 A)/f{sub {nu}}(830 A) of 20 to 204 (median of 73.5) and 378.7 for the stack. Assuming an intrinsic Lyman break of 3.4 and an intergalactic medium transmission of LyC photons along the line of sight to the galaxy of 85%, we report an upper limit for the relative escape fraction in individual galaxies of 0.02-0.19 and a stacked 3{sigma} upper limit of 0.01. We find no indication of a relative escape fraction near unity as seen in some LBGs at z {approx} 3. Our UV spectra achieve the deepest limits to date at any redshift for the escape fraction in individual sources. The contrast between these z {approx} 0.7 low escape fraction LBG analogs with z {approx} 3 LBGs suggests that either the processes conducive to high f{sub esc} are not being selected for in the z {approx}< 1 samples or the average escape fraction is decreasing from z {approx} 3 to z {approx} 1. We discuss possible mechanisms that could affect the escape of LyC photons.

  7. The Lyman-Continuum Fluxes and Stellar Parameters of O and Early B-Type Stars

    NASA Technical Reports Server (NTRS)

    Vacca, William D.; Garmany, Catherine D.; Shull, J. Michael

    1996-01-01

    Using the results of the most recent stellar atmosphere models applied to a sample of hot stars, we construct calibrations of effective temperature (T(sub eff)), and gravity (log(sub g)) with a spectral type and luminosity class for Galactic 0-type and early B-type stars. From the model results we also derive an empirical relation between the bolometric correction and T(sub eff) and log g. Using a sample of stars with known distances located in OB associations in the Galaxy and the Large Magellanic Cloud, we derive a new calibration of M(sub v) with spectral class. With these new calibrations and the stellar atmosphere models of Kurucz, we calculate the physical parameters and ionizing photon luminosities in the H(0) and He(0) continua for O and early B-type stars. We find substantial differences between our values of the Lyman- continuum luminosity and those reported in the literature. We also discuss the systematic discrepancy between O-type stellar masses derived from spectroscopic models and those derived from evolutionary tracks. Most likely, the cause of this 'mass discrepancy' lies primarily in the atmospheric models, which are plane parallel and hydrostatic and therefore do not account for an extended atmosphere and the velocity fields in a stellar wind. Finally, we present a new computation of the Lyman-continuum luminosity from 429 known O stars located within 2.5 kpc of the Sun. We find the total ionizing luminosity from this population ((Q(sub 0)(sup T(sub ot))) = 7.0 x 10(exp 51) photons/s) to be 47% larger than that determined using the Lyman continuum values tabulated by Panagia.

  8. The interstellar deuterium-to-hydrogen ratio - A reevaluation of Lyman absorption-line measurements

    NASA Technical Reports Server (NTRS)

    Mccullough, Peter R.

    1992-01-01

    The D/H ratio in the local interstellar medium is evaluated based upon previously published measurements of Lyman absorption lines together with the hypothesis that the D/H ratio is constant. A unique value for the D/H ratio of 1.5 (+/- 0.2) x 10 exp -5 by number is shown to be consistent with all published determinations made with the Copernicus and the International Ultraviolet Explorer satellites. The possibility that the D/H ratio may vary substantially in the local interstellar medium is considered and found to be unnecessary.

  9. The effect of latitudinally varying solar wind flux on the Lyman alpha sky background

    NASA Astrophysics Data System (ADS)

    Summanen, T.; Kyrola, E.; Lallement, R.; Bertaux, J.-L.

    A model for the ionization rate, which accepts any latitudinal structure for the solar wind flux was used. It is possible to study different kinds of models for the latitudinal density structure, if the latitudinal dependence of the solar wind velocity is known (e.g., from interplanetary scintillation observations). Simulated measurements were compared with the Lyman alpha intensity data from Prognoz 5 and 6 satellites. The latest results are presented. The SOHO spacecraft, to be launched in 1995 to the first Lagrange point between the Sun and the Earth, will provide new data from the SWAN (a study of Solar Wind ANisotropies) experiment measuring Lymann alpha intensity.

  10. Spatially resolved Lyman-alpha emission from a virtual dwarf galaxy

    NASA Astrophysics Data System (ADS)

    Verhamme, Anne

    2015-02-01

    In the context of the first light of MUSE, Integral Field Unit (IFU) spectrograph of second generation installed recently at VLT, we compute mock IFU Lyman-alpha (lyα) observations of a virtual dwarf galaxy, to help understanding and interpreting forthcoming observations. This study is an extension of the work carried out in Verhamme et al. (2012), where we studied the spatially integrated lyα properties of a dwarf galaxy. With the same data, we now investigate the spatial variations of lyα spectra.

  11. Lyman-alpha fluorescence from hydrogen photofragments of CH4 and H2O

    NASA Technical Reports Server (NTRS)

    Wu, C. Y. R.; Judge, D. L.

    1981-01-01

    The process of H-Lyman-alpha fluorescence produced through photodissociation of CH4 and H2O provides an example for the usefulness of the detection of fluorescence of dissociation fragments as an aid in identifying some high lying Rydberg states. In the first experiment reported, an electron storage ring synchrotron radiation source was used. The fluorescence produced was detected with a solar blind photomultiplier and a Cs photocathode with a spectral sensitivity in the wavelength range from 1050 to 1950 A. In the second experiment considered, an intense atomic line source was employed.

  12. Signatures of solar wind latitudinal structure in interplanetary Lyman-alpha emissions - Mariner 10 observations

    NASA Technical Reports Server (NTRS)

    Kumar, S.; Broadfoot, A. L.

    1979-01-01

    A detailed analysis is conducted which shows that signatures in the interplanetary Lyman-alpha emissions observed in three different data sets from Mariner 10 (corresponding to different locations of the spacecraft) provide firm evidence that the intensity departures are correlated with a decrease in solar wind flux with increasing latitude. It is suggested that observations of the interplanetary emission can be used to monitor average solar wind activity at high latitudes. The asymmetry in the solar radiation field as a source of observed departures in L-alpha data is considered and attention is given to the interstellar hydrogen and helium density.

  13. Factors Affecting VUV Emission Spectrum near Lyman-{alpha} from a Hydrogen Plasma Source

    SciTech Connect

    Ogino, K.; Kasuya, T.; Shimamoto, S.; Wada, M.; Kimura, Y.; Nishiura, M.

    2011-09-26

    Vacuum ultra violet (VUV) emission spectra from plasmas near walls of different metallic materials were measured to estimate the effect upon the local production rate of vibrational excited hydrogen molecules due to plasma wall interaction. Among Cu, Mo, Ni, Ta and Ti, the intensity of band spectrum around Lyman-{alpha} had become the largest when Cu wall was used while it was the smallest for Ti. The role of particle reflection from the plasma electrode surface upon the H{sup -} production by a pure electron volume process is discussed.

  14. Evaluation of miniature vacuum ultraviolet lamps for stability and operating characteristics, Lyman-Alpha task

    NASA Technical Reports Server (NTRS)

    Hurd, W. A.

    1985-01-01

    Modifications required to change the near ultraviolet source in the Optical Contamination Monitor to a source with output at or near the Lyman-Alpha hydrogen line are discussed. The effort consisted of selecting, acquiring and testing candidate miniature ultraviolet lamps with significant output in or near 121.6 nm. The effort also included selection of a miniature dc high-voltage power supply capable of operating the lamp. The power supply was required to operate from available primary power supplied by the Optical Effect Module (DEM) and it should be flight qualified or have the ability to be qualified by the user.

  15. Evidence for Shocks and Increased SFE in the Lyman Alpha Reference Sample

    NASA Astrophysics Data System (ADS)

    Puschnig, Johannes; Hayes, Matthew; Östlin, Göran

    2015-02-01

    We report on first molecular gas observations in the Lyman Alpha Reference Sample (LARS; Hayes et al. 2013, 2014, Östlin et al. 2014), which were performed using the 45m telescope at the Nobeyama Radio Observatory (NRO). The beamsize at the observed 12CO (1-0) emission is ~ 15'' corresponding to ~ 12kpc at the given redshift of z ~ 0.04. We detected strong 12CO emission in LARS 3 (Arp 238), marginally detected LARS 8 (SDSS 1250+0734) and derived an upper limit for LARS 9 (IRAS 08208+2816).

  16. Optimal extraction of quasar Lyman limit absorption systems from the IUE archive

    NASA Technical Reports Server (NTRS)

    Tytler, David

    1992-01-01

    The IUE archive contains a wealth of information on Lyman limit absorption systems (LLS) in quasar spectra. QSO spectra from the IUE data base were optimally extracted, coadded, and analyzed to yield a homogeneous samples of LLS at low red shifts. This sample comprise 36 LLS, twice the number previously analyzed low z samples. These systems are ideal for the determination of the origin, redshift evolution, ionization, velocity dispersions and the metal abundances of absorption systems. Two of them are also excellent targets for the primordial Deuterium to Hydrogen ratio.

  17. How Lyman Alpha Emission Depends on Galaxy Stellar Mass

    NASA Astrophysics Data System (ADS)

    Oyarzún, Grecco A.; Blanc, Guillermo A.; González, Valentino; Mateo, Mario; Bailey, John I., III; Finkelstein, Steven L.; Lira, Paulina; Crane, Jeffrey D.; Olszewski, Edward W.

    2016-04-01

    In this work, we show how the stellar mass (M *) of galaxies affects the 3 < z < 4.6 Lyα equivalent width (EW) distribution. To this end, we design a sample of 629 galaxies in the M * range 7.6\\lt {log}{M}*/{M}ȯ \\lt 10.6 from the 3D-HST/CANDELS survey. We perform spectroscopic observations of this sample using the Michigan/Magellan Fiber System, allowing us to measure Lyα fluxes and use 3D-HST/CANDELS ancillary data. In order to study the Lyα EW distribution dependence on M *, we split the whole sample in three stellar mass bins. We find that, in all bins, the distribution is best represented by an exponential profile of the form {dN}({M}*)/d{EW}={W}0{({M}*)}-1A({M}*){e}-{EW/{W}0({M}*)}. Through a Bayesian analysis, we confirm that lower M * galaxies have higher Lyα EWs. We also find that the fraction A of galaxies featuring emission and the e-folding scale W 0 of the distribution anti-correlate with M *, recovering expressions of the forms A({M}*)=-0.26(.13){log}{M}*/{M}ȯ +3.01(1.2) and {W}0({M}*)=-15.6(3.5){log}{M}*/{M}ȯ +166(34). These results are crucial for proper interpretation of Lyα emission trends reported in the literature that may be affected by strong M * selection biases.

  18. The Lyman-Alpha Forest in the Lensed Quasar Q0957+561 and the Characteristic Dimension of the Absorbing Clouds

    NASA Technical Reports Server (NTRS)

    Dolan, Joseph; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    Far-ultraviolet spectra of the gravitational lens components Q0957+561 A and 9 were obtained with the Hubble Space Telescope Faint Object Spectrograph (FOS) at five equally spaced epochs, one every two weeks. We confirm the flux variability of the quasar's Lyman-alpha and 0 VI emission lines reported by Dolan et al. (1995) in IUE spectra. The fluxes in these lines vary on a time scale of weeks in the observer's rest frame, independently of each other and of the surrounding continuum. The individual spectra of each image were co-added to investigate the properties of the Lyman-alpha forest along the two lines of sight to the quasar. Absorption lines having equivalent width W > 0.3 A in the observer's frame not previously identified by Michalitsianos et al. (1997) as interstellar lines, metal lines, or higher order Lyman lines were taken to be Ly-alpha forest lines. The existence of each line in this consistently selected set was then verified by its presence in two archival FOS spectra with -1.5 times higher signal to noise than our co-added spectra. Ly-alpha forest lines with W > 0.3 A appear at 41 distinct wavelengths in the spectra of the two images. one absorption line in the spectrum of image A has no counterpart in the spectrum of image B and one line in image B has no counterpart in image A. Based on the separation of the lines of sight over the redshift range searched for Ly-forest lines, the density of the absorbing clouds in the direction of Q0957+561 must change significantly over a distance R = 160 (+120, -70)/ h(sub 50) kpc in the simplified model where the absorbers are treated as spherical clouds and the characteristic dimension, R, is the radius. (We adopt H(sub 0) = 50 h(sub 50) km/s/ kpc, q(sub 0) = 1/2, and lambda = 0 throughout the paper.) The 95% confidence interval on R extends from (50 - 950)/h(sub 50) kpc We show in the Appendix that the fraction of Ly-alpha forest lines that appear in only one spectrum can be expressed as a rapidly

  19. Photochemical decomposition of N2O by Lyman-alpha radiation: scientific basis for a chemical actinometer.

    PubMed

    Rajappan, Mahesh; Büttner, Michael; Cox, Charlie; Yates, John T

    2010-03-18

    A novel IR method for measuring the kinetics of N(2)O photodecomposition has been devised and used to calibrate the flux of Lyman-alpha (10.2 eV) radiation from a H(2)/Ar microwave discharge lamp. The photodecomposition of N(2)O occurs with a weak pressure dependence due to the operation of a wall effect consuming some photogenerated active oxygen species. This effect is removed by working at high N(2)O pressures. The Lyman-alpha flux from the lamp is 1.28 +/- 0.36 x 10(15) photons cm(-2) s(-1). PMID:20155946

  20. Biograph™ series.

    PubMed

    2005-01-01

    Medical imaging is one of the fastest growing areas in healthcare. Combined imaging systems are at the forefront of this growth, transforming the industry by uniting functional imaging such as PET, with diagnostic multi-slice CT, thus providing an anatomical map for accurate localization, diagnosis and, finally, treatment of diseases. Dedication and consistent innovation enables Siemens Medical Solutions to offer the Biograph™ PET/CT series. This imaging system offers a high technological standard in line with excellent image quality and speed for maximum patient comfort and increased diagnostic confidence for physicians. PMID:16395982

  1. A Very Large Array search for emission from HI associated with nearby Lyman alpha absorbers

    NASA Technical Reports Server (NTRS)

    Van Gorkom, J. H.; Bahcall, J. N.; Jannuzi, B. T.; Schneider, D. P.

    1993-01-01

    We present a sensitive Very Large Array (VLA) search for H I emission from the vicinity of the Lyman alpha clouds in the Virgo Cluster, which were recently discovered with Hubble Space Telescope (HST) in absorption toward the nearest quasar 3C273. We searched an area of 40 by 40 arcmin centered on 3C273, covering a velocity range from 840 to 1840 km/s. The bandpass was self-calibrated on 3C273 leading to a spectral dynamic range of better than 10(exp 5) to 1. No H I was detected. The rms noise in the final images corresponds to a 3 sigma column density sensitivity of 2.8 x 10(exp 19) sq cm on scales of a few kpc. Small H I clouds could have been detected down to a few times 10(exp 6) solar mass. Our failure to detect H I emission at the higher column densities sets a lower limit to the radius of the Lyman alpha clouds of 3.9 kpc, assuming a spherical geometry.

  2. Electric field induced Lyman-α emission of a hydrogen beam for electric field measurements.

    PubMed

    Chérigier-Kovacic, L; Ström, P; Lejeune, A; Doveil, F

    2015-06-01

    Electric field induced Lyman-α emission is a new way of measuring weak electric fields in vacuum and in a plasma. It is based on the emission of Lyman-α radiation (121.6 nm) by a low-energy metastable H atom beam due to Stark-quenching of the 2s level induced by the field. In this paper, we describe the technique in detail. Test measurements have been performed in vacuum between two plates polarized at a controlled voltage. The intensity of emitted radiation, proportional to the square of the field modulus, has been recorded by a lock-in technique, which gives an excellent signal to noise ratio. These measurements provide an in situ calibration that can be used to obtain the absolute value of the electric field. A diagnostic of this type can help to address a long standing challenge in plasma physics, namely, the problem of measuring electric fields without disturbing the equilibrium of the system that is being studied. PMID:26133836

  3. The 21-cm signature of the first stars during the Lyman-Werner feedback era

    NASA Astrophysics Data System (ADS)

    Fialkov, Anastasia; Barkana, Rennan; Visbal, Eli; Tseliakhovich, Dmitriy; Hirata, Christopher M.

    2013-07-01

    The formation of the first stars is an exciting frontier area in astronomy. Early redshifts (z ˜ 20) have become observationally promising as a result of a recently recognized effect of a supersonic relative velocity between the dark matter and gas. This effect produces prominent structure on 100 comoving Mpc scales, which makes it much more feasible to detect 21-cm fluctuations from the epoch of first heating. We use semi-numerical hybrid methods to follow for the first time the joint evolution of the X-ray and Lyman-Werner radiative backgrounds, including the effect of the supersonic streaming velocity on the cosmic distribution of stars. We incorporate self-consistently the negative feedback on star formation induced by the Lyman-Werner radiation, which dissociates molecular hydrogen and thus suppresses gas cooling. We find that the feedback delays the X-ray heating transition by Δz ˜ 2, but leaves a promisingly large fluctuation signal over a broad redshift range. The large-scale power spectrum is predicted to reach a maximal signal-to-noise ratio of S/N ˜ 3-4 at z ˜ 18 (for a projected first-generation instrument), with S/N >1 out to z ˜ 22-23. We hope to stimulate additional numerical simulations as well as observational efforts focused on the epoch prior to cosmic reionization.

  4. Lyman-{alpha} constraints on warm and on warm-plus-cold dark matter models

    SciTech Connect

    Boyarsky, Alexey; Lesgourgues, Julien; Ruchayskiy, Oleg

    2009-05-15

    We revisit Lyman-{alpha} bounds on the dark matter mass in {Lambda} Warm Dark Matter ({Lambda}WDM) models, and derive new bounds in the case of mixed Cold plus Warm models ({Lambda}CWDM), using a set up which is a good approximation for several theoretically well-motivated dark matter models. We combine WMAP5 results with two different Lyman-{alpha} data sets, including observations from the Sloan Digital Sky Survey. We pay a special attention to systematics, test various possible sources of error, and compare the results of different statistical approaches. Expressed in terms of the mass of a non-resonantly produced sterile neutrino, our bounds read m{sub NRP} {>=} 8 keV (frequentist 99.7% confidence limit) or m{sub NRP} {>=} 12.1 keV (Bayesian 95% credible interval) in the pure {Lambda}WDM limit. For the mixed model, we obtain limits on the mass as a function of the warm dark matter fraction F{sub WDM}. Within the mass range studied here (5 keV < m{sub NRP} < {infinity}), we find that any mass value is allowed when F{sub WDM} < 0.6 (frequentist 99.7% confidence limit); similarly, the Bayesian joint probability on (F{sub WDM}, 1/m{sub NRP}) allows any value of the mass at the 95% confidence level, provided that F{sub WDM} < 0.35.

  5. The hydrogen coma of Comet P/Halley observed in Lyman-alpha using sounding rockets

    NASA Technical Reports Server (NTRS)

    Mccoy, R. P.; Meier, R. R.; Keller, H. U.; Opal, C. B.; Carruthers, G. R.

    1992-01-01

    Hydrogen Lyman-alpha (121.6 nm) images of Comet P/Halley were obtained using sounding rockets launched from White Sands Missile Range on 24.5 February and 13.5 March 1986. The second rocket was launched 13 hours before the fly-by of the Giotto spacecraft. An electrographic camera on both flights provided Lyman-alpha images covering a 20 field of view with 3 arcmin resolution. The data from both flights have been compared with a time-dependent model of hydrogen kinetics. To match the measured isophote contours, hydrogen sources with velocity components of 8 km/s and 20 km/s (from OH and H2O respectively) as well as a low velocity component (about 2 km/s) are required. This low velocity component is thought to result from thermalization of fast hydrogen atoms within the collision zone, providing an important diagnostic of temperature and density near the nucleus. Hydrogen production rates of 3.8 x 10 exp 30/s and 1.7 x 10 exp 30/s have been obtained for the two observations.

  6. Electric field induced Lyman-α emission of a hydrogen beam for electric field measurements

    SciTech Connect

    Chérigier-Kovacic, L. Doveil, F.; Ström, P.; Lejeune, A.

    2015-06-15

    Electric field induced Lyman-α emission is a new way of measuring weak electric fields in vacuum and in a plasma. It is based on the emission of Lyman-α radiation (121.6 nm) by a low-energy metastable H atom beam due to Stark-quenching of the 2s level induced by the field. In this paper, we describe the technique in detail. Test measurements have been performed in vacuum between two plates polarized at a controlled voltage. The intensity of emitted radiation, proportional to the square of the field modulus, has been recorded by a lock-in technique, which gives an excellent signal to noise ratio. These measurements provide an in situ calibration that can be used to obtain the absolute value of the electric field. A diagnostic of this type can help to address a long standing challenge in plasma physics, namely, the problem of measuring electric fields without disturbing the equilibrium of the system that is being studied.

  7. Scattered Lyman-alpha radiation of comet 2012/S1 (ISON) observed by SUMER/SOHO

    NASA Astrophysics Data System (ADS)

    Curdt, W.; Boehnhardt, H.; Germerott, D.; Schuehle, U.; Solanki, S.; Teriaca, L.; Vincent, J.

    2014-07-01

    During its recent perihelion passage, comet ISON came so close to the Sun that it appeared in the field of view (FOV) of the SUMER spectrometer on SOHO and allowed unique observations at far-UV wavelengths with high spatial and temporal resolution. We report results of these observations completed during the comet's encounter with the Sun on November 28.75, 2013. Our data show the dust tail trailing behind the predicted position of the nucleus seen in Lyman-alpha emission as light from the solar disk that is scattered by micron-sized dust particles. The arrow-shaped tail is offset from the trajectory and not aligned with it. We model the dust emission and dynamics to reproduce the appearance of the tail. We could not detect any signature of cometary gas or plasma around the expected position of the nucleus and conclude that the out-gassing processes must have stopped before the comet entered our FOV. Also the model we used to reproduce the observed dust tail needs a sharp fall-off of the dust production hours before perihelion. We compare the radiance of the dust tail to the Lyman-alpha emission of the disk for an estimate of the dust column density. After observing 18 years mostly solar targets, this was the first time that SUMER completed spectroscopic observations of a comet.

  8. Lenses in the forest: cross--correlation of the Lyman-alpha flux with CMB lensing

    SciTech Connect

    Vallinotto, Alberto; Das, Sudeep; Spergel, David N.; Viel, Matteo; /Trieste Observ. /INFN, Trieste

    2009-03-01

    We present a theoretical estimate for a new observable: the cross-correlation between the Lyman-{alpha}-flux fluctuations in quasar (QSO) spectra and the convergence of the cosmic microwave background (CMB) as measured along the same line-of-sight. As a first step toward the assessment of its detectability, we estimate the signal-to-noise ratio using linear theory. Although the signal-to-noise is small for a single line-of-sight and peaks at somewhat smaller redshifts than those probed by the Lyman-{alpha} forest, we estimate a total signal-to-noise of 9 for cross-correlating QSO spectra of SDSSIII with Planck and 20 for cross-correlating with a future polarization based CMB experiment. The detection of this effect would be a direct measure of the neutral hydrogen-matter cross-correlation and could provide important information on the growth of structures at large scales in a redshift range which is still poorly probed by observations.

  9. Impacts of Geomagnetic Storms on the Terrestrial H-Exosphere Using Twins-Lyman Stereo Data

    NASA Astrophysics Data System (ADS)

    Nass, U.; Zoennchen, J.; Fahr, H. J.; Goldstein, J.

    2015-12-01

    Based on continuously monitored Lyman-alpha data registered by the TWINS1/2-LAD instruments we have studied the impact of a weaker and a stronger geomagnetic storm on the exospheric H-density distribution between heights of 3--8 Earth-radii. As is well known, solar Lyman-alpha radiation is resonantly backscattered from geocoronal neutral hydrogen (H). The resulting resonance glow intensity in the optically thin regime is proportional to H column density along the line of sight (LOS). Here we present the terrestrial exospheric response to geomagnetic storms. We quantify the reaction to geomagnetic activity in form of amplitude and temporal response of the H-density, sampled at different geocentric distances. We find that even in case of a weak storm, the exospheric H-density in regions above the exobase reacts with a suprisingly large increase in a remarkably short time period of less than half a day. Careful analysis of this geomagnetic density effect indicates that it is an expansion in the radial scale height of the exospheric H-density, developing from exobasic heights.

  10. The Keck + Magellan Survey for Lyman Limit Absorption. III. Sample Definition and Column Density Measurements

    NASA Astrophysics Data System (ADS)

    Prochaska, J. Xavier; O'Meara, John M.; Fumagalli, Michele; Bernstein, Rebecca A.; Burles, Scott M.

    2015-11-01

    We present an absorption-line survey of optically thick gas clouds—Lyman Limit Systems (LLSs)—observed at high dispersion with spectrometers on the Keck and Magellan telescopes. We measure column densities of neutral hydrogen {N}{{H} {{I}}} and associated metal-line transitions for 157 LLSs at {z}{LLS}=1.76-4.39 restricted to {10}17.3 {{cm}}-2≤slant {N}{{H} {{I}}}\\lt {10}20.3 {{cm}}-2. An empirical analysis of ionic ratios indicates an increasing ionization state of the gas with decreasing {N}{{H} {{I}}} and that the majority of LLSs are highly ionized, confirming previous expectations. The Si+/H0 ratio spans nearly four orders of magnitude, implying a large dispersion in the gas metallicity. Fewer than 5% of these LLSs have no positive detection of a metal transition; by z˜ 3, nearly all gas that is dense enough to exhibit a very high Lyman limit opacity has previously been polluted by heavy elements. We add new measurements to the small subset of LLS (≈5%-10%) that may have super-solar abundances. High Si+/Fe+ ratios suggest an α-enhanced medium, whereas the Si+/C+ ratios do not exhibit the super-solar enhancement inferred previously for the Lyα forest.

  11. Lyman Break Analogs: Constraints on the Formation of Extreme Starbursts at Low and High Redshift

    NASA Technical Reports Server (NTRS)

    Goncalves, Thiago S.; Overzier, Roderik; Basu-Zych, Antara; Martin, D. Christopher

    2011-01-01

    Lyman Break Analogs (LBAs), characterized by high far-UV luminosities and surface brightnesses as detected by GALEX, are intensely star-forming galaxies in the low-redshift universe (z approximately equal to 0.2), with star formation rates reaching up to 50 times that of the Milky Way. These objects present metallicities, morphologies and other physical properties similar to higher redshift Lyman Break Galaxies (LBGs), motivating the detailed study of LBAs as local laboratories of this high-redshift galaxy population. We present results from our recent integral-field spectroscopy survey of LBAs with Keck/OSIRIS, which shows that these galaxies have the same nebular gas kinematic properties as high-redshift LBGs. We argue that such kinematic studies alone are not an appropriate diagnostic to rule out merger events as the trigger for the observed starburst. Comparison between the kinematic analysis and morphological indices from HST imaging illustrates the difficulties of properly identifying (minor or major) merger events, with no clear correlation between the results using either of the two methods. Artificial redshifting of our data indicates that this problem becomes even worse at high redshift due to surface brightness dimming and resolution loss. Whether mergers could generate the observed kinematic properties is strongly dependent on gas fractions in these galaxies. We present preliminary results of a CARMA survey for LBAs and discuss the implications of the inferred molecular gas masses for formation models.

  12. THE KINEMATICS OF IONIZED GAS IN LYMAN-BREAK ANALOGS AT z {approx} 0.2

    SciTech Connect

    Goncalves, Thiago S.; Martin, D. Christopher; Wyder, Ted K.; Basu-Zych, Antara; Overzier, Roderik; Law, David R.; Mallery, Ryan; Rich, R. Michael; Schiminovich, David; Heckman, Timothy H.

    2010-12-01

    We present results for 19 'Lyman-break analogs' observed with Keck/OSIRIS with an adaptive-optics-assisted spatial resolution of less than 200 pc. We detect satellites/companions, diffuse emission, and velocity shear, all with high signal-to-noise ratios. These galaxies present remarkably high velocity dispersion along the line of sight ({approx}70 km s{sup -1}), much higher than standard star-forming spirals in the low-redshift universe. We artificially redshift our data to z {approx} 2.2 to allow for a direct comparison with observations of high-z Lyman-break galaxies and find striking similarities between both samples. This suggests that either similar physical processes are responsible for their observed properties, or, alternatively, that it is very difficult to distinguish between different mechanisms operating in the low- versus high-redshift starburst galaxies based on the available data. The comparison between morphologies in the UV/optical continuum and our kinemetry analysis often shows that neither is by itself sufficient to confirm or completely rule out the contribution from recent merger events. We find a correlation between the kinematic properties and stellar mass, in that more massive galaxies show stronger evidence for a disk-like structure. This suggests a co-evolutionary process between the stellar mass buildup and the formation of morphological and dynamical substructure within the galaxy.

  13. A GALEX Imaging Search for Lyman Continuum Emission at z 1 in the EGS

    NASA Astrophysics Data System (ADS)

    Friedman, Peter G.; Small, T. A.; Deharveng, J. M.; Milliard, B.; GALEX Science Team

    2006-12-01

    We are using GALEX imaging data in the Extended Groth Strip (EGS) to search for Lyman continuum emission from galaxies at z 1. Our method is to sum FUV image flux at locations of DEEP2 catalog galaxies in the redshift range 1 < z < 1.5, for which the GALEX FUV band (1350-1800A) is sensitive only to rest wavelengths below 912 A. We subtract sky flux using control locations near each catalog galaxy. Using photometric catalogs we veto galaxy and control locations near sources that might add spurious FUV flux. We normalize FUV flux using NUV flux to derive the Lyman continuum emission escape fraction. We use various galaxy attributes from DEEP2 spectra and other data to bin galaxies to search for galaxy populations with higher escape fractions. Such a finding might shed light on differences in escape fraction measurements in the literature. GALEX is a NASA Small Explorer mission with contributions from France and South Korea. This work uses data from the AEGIS collaboration, which is supported by grants from the National Science Foundation, NASA, and the Keck Observatory.

  14. Indications for axial asymmetries in the interplanetary hydrogen distribution derived from Pioneer-10 Lyman-alpha data

    NASA Technical Reports Server (NTRS)

    Scherer, K.; Judge, D. L.

    1992-01-01

    It is presently noted that Pioneer 10's highly spatially resolved Lyman-alpha data exhibit a backscattered resonance glow with a persistent spatially-resolved asymmetry. The first harmonic amplitude ranges from about 5-10 percent of the mean value, and is observed continuously throughout the two years of this analysis period.

  15. THE GREAT OBSERVATORIES ORIGINS DEEP SURVEY: CONSTRAINTS ON THE LYMAN CONTINUUM ESCAPE FRACTION DISTRIBUTION OF LYMAN-BREAK GALAXIES AT 3.4 < z < 4.5

    SciTech Connect

    Vanzella, E.; Nonino, M.; Fontanot, F.; Cristiani, S.; Tozzi, P.; Giavalisco, M.; Inoue, A. K.; Grazian, A.; Giallongo, E.; Boutsia, K.; Fontana, A.; Pentericci, L.; Dickinson, M.; Stern, D.; Ferguson, H.; Spinrad, H.; Rosati, P.

    2010-12-10

    We use ultra-deep ultraviolet VLT/VIMOS intermediate-band and VLT/FORS1 narrowband imaging in the GOODS Southern field to derive limits on the distribution of the escape fraction (f{sub esc}) of ionizing radiation for L {>=} L*{sub z=3} Lyman-break galaxies (LBGs) at redshift 3.4-4.5. Only one LBG, at redshift z = 3.795, is detected in its Lyman continuum (LyC; S/N {approx_equal} 5.5), the highest redshift galaxy currently known with a direct detection. Its ultraviolet morphology is quite compact (R{sub eff} = 0.8 kpc physical). Three out of seven active galactic nuclei are also detected in their LyC, including one at redshift z = 3.951 and z{sub 850} = 26.1. From stacked data (LBGs), we set an upper limit to the average f{sub esc} in the range 5%-20%, depending on how the data are selected (e.g., by magnitude and/or redshift). We undertake extensive Monte Carlo simulations that take into account intergalactic attenuation, stellar population synthesis models, dust extinction, and photometric noise in order to explore the moments of the distribution of the escaping radiation. Various distributions (exponential, log-normal, and Gaussian) are explored. We find that the median f{sub esc} is lower than {approx_equal}6% with an 84% percentile limit not larger than 20%. If this result remains valid for fainter LBGs down to current observational limits, then the LBG population might be not sufficient to account for the entire photoionization budget at the redshifts considered here, with the exact details dependent upon the assumed ionizing background and QSO contribution thereto. It is possible that f{sub esc} depends on the UV luminosity of the galaxies, with fainter galaxies having higher f{sub esc}, and estimates of f{sub esc} from a sample of faint LBGs from HUDF (i{sub 775} {<=}28.5) are in broad quantitative agreement with such a scenario.

  16. A Study of the Contribution of the Damped Lyman α Systems and Lyman Break Galaxies to the Metal Content of the High-Redshift Universe

    NASA Astrophysics Data System (ADS)

    Lanfranchi, Gustavo; Friaça, Amancio C. S.

    We investigate the evolutionary history of the Universe's metal content through chemical abundances, taken from the literature, and predictions from chemical evolution models. The estimated abundances of several elements (C, N, O, S, Si, Fe, Cr, Zn) were taken from observations of QSOs absorption line systems over a wide range of redshift ( z ˜ 0.5 - 4.5). First, the observational data is analysed with robust statistical methods, which reveals important features: the metallicity of the QSOs absorption line systems increases with N(HI) until it reaches a peak at log(N(HI)) ˜ 20 - 20.5, and then declines suggesting a selection effect; there is an underabundance of Fe and Cr with respect to Zn in Damped Lyman α Systems (DLAS); the [α/Fe] ratio in DLAs is suprasolar; there is a trend of decreasing abundance with increasing N(HI) for Fe, Cr, Zn, Si and S in DLAs. After the statistical analysis, the observational data is compared with predictions of chemical evolution models. We apply different models to these systems due to the uncertainties about the nature of the QSOs absorption line systems. The DLAs are investigated with one zone models describing: a) dwarf galaxies with galactic winds and b) disk galaxies with infall. A chemodynamical model for spheroids is used to study the Lyman Break Galaxies (LBGs). In order to compare the observational data with the models, we use the ratios [N/α] and [α/Fe]. These ratios in DLAs are only partially reproduced by the disk and dwarf galaxy models suggesting that the DLAs come from a variety of morphological types of galaxies and not only one (Lanfranchi & Friaça, in preparation). They also imply a typically long timescale for the star formation in these systems. In contrast, the observational constraints for the LBGs are met by models for spheroid formation with typically short timescales for star formation ( ≈ 10 Gyr^{-1}), giving support to a scenario for galaxy formation in which there is a dichotomy between the

  17. THE HST/ACS+WFC3 SURVEY FOR LYMAN LIMIT SYSTEMS. II. SCIENCE

    SciTech Connect

    O'Meara, John M.; Prochaska, J. Xavier; Worseck, Gabor; Madau, Piero

    2013-03-10

    We present the first science results from our Hubble Space Telescope survey for Lyman limit absorption systems (LLS) using the low dispersion spectroscopic modes of the Advanced Camera for Surveys and the Wide Field Camera 3. Through an analysis of 71 quasars, we determine the incidence frequency of LLS per unit redshift and per unit path length, l(z) and l(X), respectively, over the redshift range 1 < z < 2.6, and find a weighted mean of l(X) =0.29 {+-} 0.05 for 2.0 < z < 2.5 through a joint analysis of our sample and that of Ribaudo et al. Through stacked spectrum analysis, we determine a median (mean) value of the mean free path to ionizing radiation at z = 2.4 of {lambda}{sup 912}{sub mfp} = 243(252) h {sup -1}{sub 72} Mpc, with an error on the mean value of {+-}43 h {sup -1}{sub 72} Mpc. We also re-evaluate the estimates of {lambda}{sup 912}{sub mfp} from Prochaska et al. and place constraints on the evolution of {lambda}{sup 912}{sub mfp} with redshift, including an estimate of the ''breakthrough'' redshift of z = 1.6. Consistent with results at higher z, we find that a significant fraction of the opacity for absorption of ionizing photons comes from systems with N{sub H{sub I}} {<=}10{sup 17.5} cm{sup -2} with a value for the total Lyman opacity of {tau}{sup Lyman}{sub eff} = 0.40 {+-} 0.15. Finally, we determine that at minimum, a 5-parameter (4 power law) model is needed to describe the column density distribution function f(N{sub H{sub I}}, X) at z {approx} 2.4, find that f(N{sub H{sub I}}, X) undergoes no significant change in shape between z {approx} 2.4 and z {approx} 3.7, and provide our best fit model for f(N{sub H{sub I}}, X).

  18. Lyman Continuum Escape Fraction of Star-forming Dwarf Galaxies at z ˜ 1

    NASA Astrophysics Data System (ADS)

    Rutkowski, Michael J.; Scarlata, Claudia; Haardt, Francesco; Siana, Brian; Henry, Alaina; Rafelski, Marc; Hayes, Matthew; Salvato, Mara; Pahl, Anthony J.; Mehta, Vihang; Beck, Melanie; Malkan, Matthew; Teplitz, Harry I.

    2016-03-01

    To date, no direct detection of Lyman continuum emission has been measured for intermediate-redshift (z˜ 1) star-forming galaxies. We combine Hubble Space Telescope grism spectroscopy with GALEX UV and ground-based optical imaging to extend the search for escaping Lyman continuum to a large (˜600) sample of z˜ 1 low-mass ({log}(\\bar{M}) ≃ 9.3{M}⊙ ), moderately star-forming (\\bar{{{\\Psi }}} ≲ 10{M}⊙ yr-1) galaxies selected initially on Hα emission. The characteristic escape fraction of LyC from star-forming galaxies (SFGs) that populate this parameter space remains weakly constrained by previous surveys, but these faint (sub-L⋆) SFGs are assumed to play a significant role in the reionization of neutral hydrogen in the intergalactic medium (IGM) at high redshift z\\gt 6. We do not make an unambiguous detection of escaping LyC radiation from this z˜ 1 sample, individual non-detections to constrain the absolute Lyman continuum escape fraction, {f}{esc} \\lt 2.1% (3σ). We measure an upper limit of {f}{esc} \\lt 9.6% from a sample of SFGs selected on high Hα equivalent width (EW \\gt 200 {{\\mathringA }}), which are thought to be close analogs of high redshift sources of reionization. For reference, we also present an emissivity-weighted escape fraction that is useful for measuring the general contribution SFGs to the ionizing UV background. In the discussion, we consider the implications of these intermediate redshift constraints for the reionization of hydrogen in the IGM at high (z\\gt 6) redshift. If we assume our z˜ 1 SFGs, for which we measure this emissivity-weighted {f}{esc}, are analogs to the high redshift sources of reionization, we find it is difficult to reconcile reionization by faint ({M}{UV}≲ -13) SFGs with a low escape fraction ({f}{esc} \\lt 3%), with constraints from independent high redshift observations. If {f}{esc} evolves with redshift, reionization by SFGs may be consistent with observations from Planck.

  19. Narrowband Lyman-continuum imaging of galaxies at z ∼ 2.85

    SciTech Connect

    Mostardi, R. E.; Shapley, A. E.; Nestor, D. B.; Steidel, C. C.; Trainor, R. F.; Reddy, N. A.

    2013-12-10

    We present results from a survey for z ∼ 2.85 Lyman-continuum (LyC) emission in the HS1549+1933 field and place constraints on the amount of ionizing radiation escaping from star-forming galaxies. Using a custom narrowband filter (NB3420) tuned to wavelengths just below the Lyman limit at z ≥ 2.82, we probe the LyC spectral region of 49 Lyman break galaxies (LBGs) and 91 Lyα emitters (LAEs) spectroscopically confirmed at z ≥ 2.82. Four LBGs and seven LAEs are detected in NB3420. Using V-band data probing the rest-frame nonionizing UV, we observe that many NB3420-detected galaxies exhibit spatial offsets between their LyC and nonionizing UV emission and are characterized by extremely blue NB3420–V colors, corresponding to low ratios of nonionizing to ionizing radiation (F {sub UV}/F {sub LyC}) that are in tension with current stellar population synthesis models. We measure average values of (F {sub UV}/F {sub LyC}) for our LBG and LAE samples, correcting for foreground galaxy contamination and H I absorption in the intergalactic medium. We find (F{sub UV}/F{sub LyC}){sub corr}{sup LBG}=82±45 and (F{sub UV}/F{sub LyC}){sub corr}{sup LAE}=7.4±3.6. These flux density ratios correspond, respectively, to relative LyC escape fractions of f{sub esc,} {sub rel}{sup LBG}=5%--8% and f{sub esc,} {sub rel}{sup LAE}=18%--49%, absolute LyC escape fractions of f{sub esc}{sup LBG}=1%--2% and f{sub esc}{sup LAE}=5%--15%, and a comoving LyC emissivity from star-forming galaxies of 8.8-15.0 × 10{sup 24} erg s{sup –1} Hz{sup –1} Mpc{sup –3}. In order to study the differential properties of galaxies with and without LyC detections, we analyze narrowband Lyα imaging and rest-frame near-infrared imaging, finding that while LAEs with LyC detections have lower Lyα equivalent widths on average, there is no substantial difference in the rest-frame near-infrared colors of LBGs or LAEs with and without LyC detections. These preliminary results are consistent with an

  20. Latitudinal dependence of solar proton flux derived from interplanetary Lyman alpha emission

    NASA Astrophysics Data System (ADS)

    Nakagawa, H.; Fukunishi, H.; Watanabe, S.; Takahashi, Y.; Taguchi, M.; Bertaux, J.; Quemerais, E.; Lallement, R.

    2004-12-01

    There is a uniform flow of the interplanetary hydrogen in the solar system. The distribution of interplanetary neutral hydrogen is sensitive to solar wind proton flux, which has a latitudinal distribution, because interplanetary neutral hydrogen atoms are mainly ionized through a process of charge-exchange with solar wind protons (contributing to 80% of the total ionization rate). Rucinski et al. [1996] estimated the ionization rate of the interplanetary hydrogen in an average solar activity condition: 6.4±0.14 [10E-7/s] for charge exchange with protons. The most practical technique for determining the latitudinal dependence of the interplanetary hydrogen is observation of resonant backscatter of solar Lyman ƒ¿ emission at 121.6 nm. The interplanetary Lyman ƒ¿ emission has been measured by the ultraviolet imaging spectrometer (UVS) on board the Nozomi spacecraft crusing on its Mars transfer orbit with a periapsis of 1 AU and an apoapsis 1.5 AU from the Sun. The field-of-view of UVS is perpendicular to the spin axis of the spacecraft, which is controlled toward the Earth. The spatial resolution of UVS is 1.41 degrees in a plane perpendicular to the spin axis and 0.29 degrees in a plane including the spin axis. Spatial distributions are obtained from the full sky scanning of UVS with spin and orbital motions of the Nozomi spacecraft. One-year UVS data enable us to construct a full sky image of Lyman ƒ¿ emission. We present the results obtained from Nozomi/UVS data analysis for the period of 1999-2002. From a fitting of model calculations to the observed data, it is confirmed that a latitudinal anisotropy with the higher ionization region at the equator is reduced toward solar maximum. Finally, higher ionization region are found at the poles than at the equator near solar maximum. Basically, this change is produced by variations in the latitudinal dependence of persistent solar wind proton flux. However, proton flux from transient CMEs also affects the

  1. Indirect Evidence for Escaping Ionizing Photons in Local Lyman Break Galaxy Analogs

    NASA Astrophysics Data System (ADS)

    Alexandroff, Rachael M.; Heckman, Timothy M.; Borthakur, Sanchayeeta; Overzier, Roderik; Leitherer, Claus

    2015-09-01

    A population of early star-forming galaxies is the leading candidate for the re-ionization of the universe. It is still unclear, however, what conditions and physical processes would enable a significant fraction of the ionizing (Lyman continuum) photons to escape from these gas-rich galaxies. In this paper we present the results of the analysis of Hubble Space Telescope Cosmic Origins Spectrograph far-UV (FUV) spectroscopy plus ancillary multi-waveband data of a sample of 22 low-redshift galaxies that are good analogs to typical star-forming galaxies at high redshift. We measure three parameters that provide indirect evidence of the escape of ionizing radiation (leakiness): (1) the residual intensity in the cores of saturated interstellar low-ionization absorption lines, which indicates incomplete covering by that gas in the galaxy; (2) the relative amount of blueshifted Lyα line emission, which can indicate the existence of holes in the neutral hydrogen on the front-side of the galaxy outflow, and (3) the relative weakness of the [S ii] optical emission lines that trace matter-bounded H ii regions. We show that our residual intensity measures are only negligibly affected by infilling from resonance emission lines. We find all three diagnostics agree well with one another. We use these diagnostics to rank-order our sample in terms of likely leakiness, noting that a direct measure of escaping Lyman continuum has recently been made for one of the leakiest members of our sample. We then examine the correlations between our ranking and other proposed diagnostics of leakiness. We find a good correlation with the equivalent width of the Lyα emission line, but no significant correlations with either the flux ratio of the [O iii]/[O ii] emission lines or the ratio of star-formation rates derived from the (dust-corrected) FUV and Hα luminosities. Turning to galaxy properties, we find the strongest correlations with leakiness are with the compactness of the star

  2. New approach for precise computation of Lyman-α forest power spectrum with hydrodynamical simulations

    NASA Astrophysics Data System (ADS)

    Borde, Arnaud; Palanque-Delabrouille, Nathalie; Rossi, Graziano; Viel, Matteo; Bolton, James S.; Yèche, Christophe; LeGoff, Jean-Marc; Rich, Jim

    2014-07-01

    Current experiments are providing measurements of the flux power spectrum from the Lyman-α forests observed in quasar spectra with unprecedented accuracy. Their interpretation in terms of cosmological constraints requires specific simulations of at least equivalent precision. In this paper, we present a suite of cosmological N-body simulations with cold dark matter and baryons, specifically aiming at modeling the low-density regions of the inter-galactic medium as probed by the Lyman-α forests at high redshift. The simulations were run using the GADGET-3 code and were designed to match the requirements imposed by the quality of the current SDSS-III/BOSS or forthcoming SDSS-IV/eBOSS data. They are made using either 2 × 7683 simeq 1 billion or 2 × 1923 simeq 14 million particles, spanning volumes ranging from (25 Mpc h-1)3 for high-resolution simulations to (100 Mpc h-1)3 for large-volume ones. Using a splicing technique, the resolution is further enhanced to reach the equivalent of simulations with 2 × 30723 simeq 58 billion particles in a (100 Mpc h-1)3 box size, i.e. a mean mass per gas particle of 1.2 × 105Msolar h-1. We show that the resulting power spectrum is accurate at the 2% level over the full range from a few Mpc to several tens of Mpc. We explore the effect on the one-dimensional transmitted-flux power spectrum of four cosmological parameters (ns, σ8, Ωm and H0) and two astrophysical parameters (T0 and γ) that are related to the heating rate of the intergalactic medium. By varying the input parameters around a central model chosen to be in agreement with the latest Planck results, we built a grid of simulations that allows the study of the impact on the flux power spectrum of these six relevant parameters. We improve upon previous studies by not only measuring the effect of each parameter individually, but also probing the impact of the simultaneous variation of each pair of parameters. We thus provide a full second-order expansion, including

  3. Imaging of High Redshift Starburst galaxies in the light of Lyman alpha

    NASA Astrophysics Data System (ADS)

    Beckwith, Steven

    1997-07-01

    The PI is the designated director for STScI but has no experience with HST. The purpose of this proposal is to gain experience with the facility by carrying out a modest observational program that is unique and will not conflict with any community programs. The proposed science is divided into priority 1 and priority 2, for 6 + 4 orbits. This division will allow allocation in parts, if the pressure on DDT is large and the total of 10 orbits unusually difficult to schedule. The priority 1 science is rather predictable and, hence, conservative, consisting of the brightest of the objects under study. The priority 2 science is somewhat riskier, because it is more difficult to estimate object brightnesses in the filters to be used on HST. Both priority 1 and priority 2 observations allow for a large degree of serendipity, because the fields are likely to have more starburst galaxies at the observed redshifts that may show up in Lyman alpha. Exploration of the high redshift u niverse and discovery of the most distant objects is still in its infancy. Only recently have the tools been available to detect normal galaxies at redshifts larger than one when the first galaxies were created {Pescarelle et al. 1996; Hu & McMahon 1996; Cowie & Hu 1998; Steidel et al. 1996}. It seems likely that young galaxies will have a variety of different signatures {Franceschini et al. 1998; Guideroni et al. 1997}, so that it will be necessary to use several diverse techniques to uncover all of them: searches at optical, infrared, x-ray, and radio wavelengths, for example. It is already known that many of the optically selected galaxies using the "dropout" technique are reddened by dust {Pettini et al. 1997}. We carried out two surveys for infrared emission-line galaxies by imaging through narrow {Resolving power 100} and broad band filters between 1 and 2.5 microns and identifying objects that appeared brighter in the narrow filters. Our first survey was designed to uncover emission lines at

  4. Direct method gas-phase oxygen abundances of four Lyman break analogs

    SciTech Connect

    Brown, Jonathan S.; Croxall, Kevin V.; Pogge, Richard W.

    2014-09-10

    We measure the gas-phase oxygen abundances in four Lyman break analogs using auroral emission lines to derive direct abundances. The direct method oxygen abundances of these objects are generally consistent with the empirically derived strong-line method values, confirming that these objects are low oxygen abundance outliers from the mass-metallicity (MZ) relation defined by star forming Sloan Digital Sky Survey galaxies. We find slightly anomalous excitation conditions (Wolf-Rayet features) that could potentially bias the empirical estimates toward high values if caution is not exercised in the selection of the strong-line calibration. The high rate of star formation and low oxygen abundance of these objects is consistent with the predictions of the fundamental metallicity relation, in which the infall of relatively unenriched gas simultaneously triggers an episode of star formation and dilutes the interstellar medium of the host galaxy.

  5. Voyager measurements of hydrogen Lyman-α diffuse emission from the Milky Way.

    PubMed

    Lallement, Rosine; Quémerais, Eric; Bertaux, Jean-Loup; Sandel, Bill R; Izmodenov, Vlad

    2011-12-23

    Doppler-shifted hydrogen Lyman-alpha (Lyα) emission from galaxies is currently measured and used in cosmology as an indicator of star formation. Until now, the Milky Way emission has not been detected, owing to far brighter local sources, including the H (hydrogen) glow, i.e., solar Lyα radiation backscattered by interstellar atoms that flow within the solar system. Because observations from the Voyager spacecraft, now leaving the heliosphere, are decreasingly affected by the H glow, the ultraviolet spectrographs are detecting Lyα diffuse emission from our Galaxy. The surface brightness toward nearby star-forming regions is about 3 to 4 rayleighs. The escape fraction of the radiation from the brightest H II regions is on the order of 3% and is highly spatially variable. These results will help in constraining models of Lyα radiation transfer in distant galaxies. PMID:22144462

  6. The Lyman α forest as a tool for disentangling non-Gaussianities

    SciTech Connect

    Chongchitnan, Sirichai

    2014-10-01

    Detection of primordial non-Gaussianity will give us an unprecedented detail of the physics of inflation. As observational probes are now exploring new expanses of the inflationary landscape, it is crucial to distinguish and disentangle effects of various non-Gaussianities beyond f{sub NL}. In this work, we calculate the effects of non-Gaussianities parametrized by f{sub NL} and the cubic-order g{sub NL}, on the Lyman α-forest flux measurements. We give the expressions of the bias due to f{sub NL} and g{sub NL}, which can be deduced from accurate measurements of the transmitted flux. We show how these two effects can be cleanly disentangled via a flux transformation, which also keeps the error in check.

  7. Absolute wavelength measurement of the Lyman-{alpha} transitions of hydrogenic Mg{sup 11+}

    SciTech Connect

    Hoelzer, G.; Foerster, E.; Kloepfel, D.; Beiersdorfer, P.; Brown, G.V.; Crespo Lopez-Urrutia, J.R.; Widmann, K.

    1998-02-01

    The wavelengths of the 1s{sub 1/2}-2p{sub 1/2} and 1s{sub 1/2}-2p{sub 3/2} Lyman-{alpha} transitions have been measured in hydrogenic Mg{sup 11+} with an accuracy as high as 24 ppm. The measurement was carried out on an electron-beam ion trap and utilized a quasimonolithic crystal setup absolutely calibrated relative to optical standards. The resulting values for the two transitions were 0.84250{plus_minus}0.00004 and 0.84190{plus_minus}0.00002nm, respectively. The measurement confirms calculations of the 1s-2p wavelengths and tests the size of the 1s Lamb shift to within 13{percent}. {copyright} {ital 1998} {ital The American Physical Society}

  8. Nonadiabatic behavior of the polarization of electric-field-induced Lyman-. alpha. radiation

    SciTech Connect

    Plotzke, O.; Wille, U.; Hippler, R.; Lutz, H.O. Bereich Schwerionenphysik, Hahn-Meitner-Institut Berlin, Berlin )

    1990-12-10

    The linear polarization of Lyman-{alpha} radiation emitted when hydrogen atoms in the metastable 2{ital s}{sub 1/2} state traverse an external electric field is studied as a function of the effective rise time of the field for field strengths extending from very small values up to 6 keV/cm. With decreasing rise time, the measured polarization exhibits a transition from {ital adiabatic} to {ital sudden} behavior. The transition region is centered at a rise time which is approximately equal to the characteristic time associated with the 2{ital s}{sub 1/2-}2{ital p}{sub 1/2} Lamb splitting in the unperturbed hydrogen system. The experimental data are well described by the results of a time-dependent theory.

  9. A cross-check for H0 from Lyman-α Forest and Baryon Acoustic Oscillations

    NASA Astrophysics Data System (ADS)

    Busti, V. C.; Guimarães, R. N.; Lima, J. A. S.

    2016-04-01

    A new method is proposed to infer the Hubble constant H0 through the observed mean transmitted flux from high-redshift quasars and the baryon acoustic oscillations (BAOs). A semi-analytical model for the cosmological-independent volume density distribution function was adopted; it allowed us to obtain constraints on the cosmological parameters once a moderate knowledge of the Inter Galactic Medium (IGM) parameters is assumed. Our analysis, based on two different samples of Lyman-α forest and the BAO measurement, restricts (h, Ωm) to the intervals 0.19 ≤ Ωm ≤ 0.23 and 0.53 ≤ h ≤ 0.82 (1σ). Although the constraints are weaker compared with other estimates, we point out that, with a bigger sample and a better knowledge of the IGM, this method could provide complementary results to measure the Hubble constant independently of the cosmic distance ladder.

  10. Solar wind decrease at high heliographic latitudes detected from Prognoz interplanetary Lyman alpha mapping

    NASA Astrophysics Data System (ADS)

    Lallement, R.; Bertaux, J. L.; Kurt, V. G.

    1985-02-01

    New evidence for a latitudinal decrease of the solar wind mass flux is presented from observations of the interplanetary Lyman alpha emission collected in 1976 and 1977 with satellites Prognoz 5 and 6. The flow of interstellar hydrogen atoms in the solar system is ionized by EUV solar radiation and charge exchange with solar wind protons which accounts for about 80% of the total ionization rate. The resulting gradual decrease of the neutral H density from the upwind region down to the downwind region observed from Ly α intensity measurements allowed the determination of the absolute value of the total ionization rate β for one H atom at 1 AU against ionization. Collected in 1976 and 1977 at five places in the solar system, the measurements are compared to different models.

  11. Resonance-enhanced two-photon ionization of ions by Lyman alpha radiation in gaseous nebulae.

    PubMed

    Johansson, S; Letokhov, V

    2001-01-26

    One of the mysteries of nebulae in the vicinity of bright stars is the appearance of bright emission spectral lines of ions, which imply fairly high excitation temperatures. We suggest that an ion formation mechanism, based on resonance-enhanced two-photon ionization (RETPI) by intense H Lyman alpha radiation (wavelength of 1215 angstroms) trapped inside optically thick nebulae, can produce these spectral lines. The rate of such an ionization process is high enough for rarefied gaseous media where the recombination rate of the ions formed can be 10(-6) to 10(-8) per second for an electron density of 10(3) to 10(5) per cubic centimeter in the nebula. Under such conditions, the photo-ions formed may subsequently undergo further RETPI, catalyzed by intense He i and He ii radiation, which also gets enhanced in optically thick nebulae that contain enough helium. PMID:11158669

  12. A Lyman Break Galaxy in the Epoch of Reionization from Hubble Space Telescope (HST) Grism Spectroscopy

    NASA Technical Reports Server (NTRS)

    Rhoads, James E.; Malhotra, Sangeeta; Stern, Daniel K.; Gardner, Jonathan P.; Dickinson, Mark; Pirzkal, Norbert; Spinrad, Hyron; Reddy, Naveen; Dey, Arjun; Hathi, Nimish; Grogin, Norman; Koekemoer, Anton; Peth, Michael A.; Cohen, Seth; Budavari, Tamas; Ferreras, Ignacio; Gronwall, Caryl; Haiman, Zoltan; Meurer, Gernhardt; Straughn, Amber N.

    2013-01-01

    Slitless grism spectroscopy from space offers dramatic advantages for studying high redshift galaxies: high spatial resolution to match the compact sizes of the targets, a dark and uniform sky background, and simultaneous observation over fields ranging from five square arcminutes (HST) to over 1000 square arcminutes (Euclid). Here we present observations of a galaxy at z = 6.57 the end of the reioinization epoch identified using slitless HST grism spectra from the PEARS survey (Probing Evolution And Reionization Spectroscopically) and reconfirmed with Keck + DEIMOS. This high redshift identification is enabled by the depth of the PEARS survey. Substantially higher redshifts are precluded for PEARS data by the declining sensitivity of the ACS grism at greater than lambda 0.95 micrometers. Spectra of Lyman breaks at yet higher redshifts will be possible using comparably deep observations with IR-sensitive grisms.

  13. Low-redshift Lyman-alpha absorption lines and the dark matter halos of disk galaxies

    NASA Technical Reports Server (NTRS)

    Maloney, Philip

    1992-01-01

    Ultraviolet observations of the low-redshift quasar 3C 273 using the Hubble Space Telescope have revealed many more Lyman-alpha absorption lines than would be expected from extrapolation of the absorption systems seen toward QSOs at z about 2. It is shown here that these absorption lines can plausibly be produced by gas at large radii in the disks of spiral and irregular galaxies; the gas is confined by the dark matter halos and ionized and heated by the extragalactic radiation field. This scenario does not require the extragalactic ionizing radiation field to decline as rapidly with decreasing z as the QSO emissivity. Observations of Ly-alpha absorption through the halos of known galaxies at low redshift will constrain both the extragalactic background and the properties of galactic halos.

  14. X-Ray Emission from Ultraviolet Luminous Galaxies and Lyman Break Galaxies

    NASA Technical Reports Server (NTRS)

    Hornschemeier, Ann; Ptak, A. F.; Salim, S.; Heckman, T. P.; Overzier, R.; Mallery, R.; Rich, M.; Strickland, D.; Grimes, J.

    2009-01-01

    We present results from an XMM mini-survey of GALEX-selected Ultraviolet-Luminous Galaxies (UVLGs) that appear to include an interesting subset that are analogs to the distant (3Lyman Break Galaxies (LBGs). The 2-10 kev X-ray emission of LBGs appear to be broadly similar to that of galaxies in the local Universe, possibly indicating similarity in the production of accreting binaries over large evolutionary timescales in the Universe. We have detected luminous X-ray emission from one UVLG that permits basic X-ray spectroscopic analysis, and have direct X-ray constraints on a total of 6 UVLGs. We find evidence for likely large scatter in the assumed X-ray/star-formation rate relation for LBGs.

  15. Glauber calculations of polarization of Lyman-alpha resulting from e/-/-H/1s/ collisions.

    NASA Technical Reports Server (NTRS)

    Gerjuoy, E.; Thomas, B. K.; Sheorey, V. B.

    1972-01-01

    We have calculated the polarization fraction of the Lyman-alpha radiation emitted in e/-/-H/1s/ collisions using the Glauber, Born, and various Vainshtein approximations, and have compared these predictions with observation. We find that the Born, Glauber and all forms of the Vainshtein yield results which are very close to each other and to the data in the energy range from 30 to 700 eV. The comparatively small differences between the various approximations are detailed in the text; also, the reason for the close agreement of the predicted polarization fractions - although the computed 1s-2p total and differential cross sections are not so close - is explained. With respect to the Glauber approximation, the importance of computing the phase integral along a direction perpendicular to the momentum transfer q at each value of q, is stressed.

  16. Mariner 9 ultraviolet spectrometer experiment - Mars airglow spectroscopy and variations in Lyman alpha.

    NASA Technical Reports Server (NTRS)

    Barth, C. A.; Stewart, A. I.; Hord, C. W.; Lane, A. L.

    1972-01-01

    Mariner 9 ultraviolet spectrometer observations show the Mars airglow consists principally of emissions that arise from the interaction of solar ultraviolet radiation with carbon dioxide, the principal constituent of the Mars atmosphere. Two minor constituents, atomic hydrogen and atomic oxygen, also produce airglow emissions. The airglow measurements show that ionized carbon dioxide is only a minor constituent of the ionosphere. Using the airglow measurements of atomic oxygen, it is possible to infer that the major ion is ionized molecular oxygen. The escape rate of atomic hydrogen measured by Mariner 9 is approximately the same as that measured two years earlier by Mariner 6 and 7. If the current escape rate has been operating for 4.5 billion years and if water vapor is the ultimate source, an amount of oxygen has been generated that is far in excess of that observed at present. Mariner 9 observations of Mars Lyman alpha emission over a period of 120 days show variations of 20%.

  17. Voyager Measurements of Hydrogen Lyman-α Diffuse Emission from the Milky Way

    NASA Astrophysics Data System (ADS)

    Lallement, Rosine; Quémerais, Eric; Bertaux, Jean-Loup; Sandel, Bill R.; Izmodenov, Vlad

    2011-12-01

    Doppler-shifted hydrogen Lyman-alpha (Lyα) emission from galaxies is currently measured and used in cosmology as an indicator of star formation. Until now, the Milky Way emission has not been detected, owing to far brighter local sources, including the H (hydrogen) glow, i.e., solar Lyα radiation backscattered by interstellar atoms that flow within the solar system. Because observations from the Voyager spacecraft, now leaving the heliosphere, are decreasingly affected by the H glow, the ultraviolet spectrographs are detecting Lyα diffuse emission from our Galaxy. The surface brightness toward nearby star-forming regions is about 3 to 4 rayleighs. The escape fraction of the radiation from the brightest H II regions is on the order of 3% and is highly spatially variable. These results will help in constraining models of Lyα radiation transfer in distant galaxies.

  18. All-Solid-State Laser Amplifiers for Intense Lyman-α Generation

    NASA Astrophysics Data System (ADS)

    Oishi, Yu; Okamura, Kotaro; Miyazaki, Koji; Saito, Norihito; Iwasaki, Masahiko; Wada, Satoshi

    We have developed an all-solid-state high energy 1062.78 nm pulse amplifier system toward efficient Lyman-α generation using two-photon resonance four-wave mixing in Kr gas. Nd:YSAG and Nd:YGAG crystals were applied to regenerative amplifier in order to investigate whether suitable for amplification of 1062.78 nm light. The higher gain was obtained by use of Nd:YGAG crystal. Moreover, we have developed Nd:YGAG ceramic for subsequent power amplifiers to overcome an inhomogeneity in large aperture Nd:YGAG single crystal. 100 mJ level 1062.78 nm pulses have been obtained using Nd:YGAG ceramic amplifier.

  19. The 27-day versus 13.5-day variations in the solar Lyman-alpha radiation and the radio wave absorption in the lower ionosphere over Europe

    NASA Technical Reports Server (NTRS)

    Delamorena, B. A.; Lastovicka, Jan; Rapoport, Z. TS.; Alberca, L.

    1989-01-01

    In order to clarify the question of solar periods in absorption, the pattern was studied of the solar Lyman-alpha radiation (the principal ionizing agent of the lower ionosphere) and of the radio wave absorption at five widely spaced places in Europe. When the solar Lyman-alpha flux variability is very well developed, then it dominates in the lower ionospheric variability. The most pronounced Lyman-alpha variation on time scale day-month is the solar rotation variation (about 27 days). When the Lyman-alpha variability is developed rather poorly, as it is typical for periods dominated by the 13.5 day variability, then the lower ionospheric variability appears to be dominated by variations of meteorological origin. The conclusions hold for all five widely spaced placed in Europe.

  20. INCORPORATING SINGLE NUCLEOTIDE POLYMORPHISMS INTO THE LYMAN MODEL TO IMPROVE PREDICTION OF RADIATION PNEUMONITIS

    PubMed Central

    Tucker, Susan L.; Li, Minghuan; Xu, Ting; Gomez, Daniel; Yuan, Xianglin; Yu, Jinming; Liu, Zhensheng; Yin, Ming; Guan, Xiaoxiang; Wang, Li-E; Wei, Qingyi; Mohan, Radhe; Vinogradskiy, Yevgeniy; Martel, Mary; Liao, Zhongxing

    2012-01-01

    Purpose To determine whether single nucleotide polymorphisms (SNPs) in genes associated with DNA repair, cell cycle, transforming growth factor beta, tumor necrosis factor and receptor, folic acid metabolism, and angiogenesis can significantly improve the fit of the Lyman-Kutcher-Burman (LKB) normal-tissue complication probability (NTCP) model of radiation pneumonitis (RP) risk among patients with non-small cell lung cancer (NSCLC). Methods and Materials Sixteen SNPs from 10 different genes (XRCC1, XRCC3, APEX1, MDM2, TGFβ, TNFα, TNFR, MTHFR, MTRR, and VEGF) were genotyped in 141 NSCLC patients treated with definitive radiotherapy, with or without chemotherapy. The LKB model was used to estimate the risk of severe (Grade ≥3) RP as a function of mean lung dose (MLD), with SNPs and patient smoking status incorporated into the model as dose-modifying factors. Multivariate (MV) analyses were performed by adding significant factors to the MLD model in a forward stepwise procedure, with significance assessed using the likelihood-ratio test. Bootstrap analyses were used to assess the reproducibility of results under variations in the data. Results Five SNPs were selected for inclusion in the multivariate NTCP model based on MLD alone. SNPs associated with an increased risk of severe RP were in genes for TGFβ, VEGF, TNFα, XRCC1 and APEX1. With smoking status included in the MV model, the SNPs significantly associated with increased risk of RP were in genes for TGFβ, VEGF, and XRCC3. Bootstrap analyses selected a median of 4 SNPs per model fit, with the 6 genes listed above selected most often. Conclusions This study provides evidence that SNPs can significantly improve the predictive ability of the Lyman MLD model. With a small number of SNPs, it was possible to distinguish cohorts with >50% risk versus <10% risk of RP when exposed to high MLDs. PMID:22541966

  1. Incorporating Single-nucleotide Polymorphisms Into the Lyman Model to Improve Prediction of Radiation Pneumonitis

    SciTech Connect

    Tucker, Susan L.; Li Minghuan; Xu Ting; Gomez, Daniel; Yuan Xianglin; Yu Jinming; Liu Zhensheng; Yin Ming; Guan Xiaoxiang; Wang Lie; Wei Qingyi; Mohan, Radhe; Vinogradskiy, Yevgeniy; Martel, Mary; Liao Zhongxing

    2013-01-01

    Purpose: To determine whether single-nucleotide polymorphisms (SNPs) in genes associated with DNA repair, cell cycle, transforming growth factor-{beta}, tumor necrosis factor and receptor, folic acid metabolism, and angiogenesis can significantly improve the fit of the Lyman-Kutcher-Burman (LKB) normal-tissue complication probability (NTCP) model of radiation pneumonitis (RP) risk among patients with non-small cell lung cancer (NSCLC). Methods and Materials: Sixteen SNPs from 10 different genes (XRCC1, XRCC3, APEX1, MDM2, TGF{beta}, TNF{alpha}, TNFR, MTHFR, MTRR, and VEGF) were genotyped in 141 NSCLC patients treated with definitive radiation therapy, with or without chemotherapy. The LKB model was used to estimate the risk of severe (grade {>=}3) RP as a function of mean lung dose (MLD), with SNPs and patient smoking status incorporated into the model as dose-modifying factors. Multivariate analyses were performed by adding significant factors to the MLD model in a forward stepwise procedure, with significance assessed using the likelihood-ratio test. Bootstrap analyses were used to assess the reproducibility of results under variations in the data. Results: Five SNPs were selected for inclusion in the multivariate NTCP model based on MLD alone. SNPs associated with an increased risk of severe RP were in genes for TGF{beta}, VEGF, TNF{alpha}, XRCC1 and APEX1. With smoking status included in the multivariate model, the SNPs significantly associated with increased risk of RP were in genes for TGF{beta}, VEGF, and XRCC3. Bootstrap analyses selected a median of 4 SNPs per model fit, with the 6 genes listed above selected most often. Conclusions: This study provides evidence that SNPs can significantly improve the predictive ability of the Lyman MLD model. With a small number of SNPs, it was possible to distinguish cohorts with >50% risk vs <10% risk of RP when they were exposed to high MLDs.

  2. Optical-to-IR Photometric Properties of Lyman Break Galaxies in the HDF-North

    NASA Astrophysics Data System (ADS)

    Papovich, C.; Dickinson, M.; Ferguson, H.; NICMOS HDF--N GO Team

    1999-12-01

    We present the photometric properties of Lyman Break Galaxies (LBGs) in the Hubble Deep Field North (HDF--N) using deep seven--band photometry from WFPC2 (UBVI, Williams et al. 1996), NICMOS (JH, Dickinson et al. 2000), and newly derived Ks--band photometry from ground--based KPNO data (Dickinson 1997; Papovich & Dickinson 2000). For the 27 HDF galaxies with spectroscopic redshifts 2.0 ≲ z ≲ 3.5, our photometry spans rest frame wavelengths extending from the Lyman limit through rest--frame λ 0 ≳ 5000 Angstroms. In this poster, we compare the spectral energy distributions (SEDs) of the LBGs to empirical spectral templates from Kinney et al. (1996) and Coleman, Wu, & Weedman (1980), and to population synthesis models from Bruzual & Charlot (1996). We consider general constraints on galaxy ages, star formation histories, and extinction. By selection, the LBGs contain strong, blue UV continua. In general, they are well fit by local starburst templates. To fit the SEDs of specific galaxies, most require modest but non--zero reddening. At rest--frame optical wavelengths, many galaxies show evidence for significant contributions from longer lived (A and later) stars, but none appear to be dominated by old (red) stellar populations. In some cases, there may be significant broad band flux contributions from strong nebular emission lines ([N 2]+Hα , [O 3]+Hβ , [O 2]). We discuss the implications for the evolutionary history of these galaxies using these empirical results. Support for this work is provided by NASA through grant GO-07817.01-96A.

  3. Isotope effect in the photochemical decomposition of CO2 (ice) by Lyman-α radiation

    NASA Astrophysics Data System (ADS)

    Yuan, Chunqing; Yates, John T.

    2013-04-01

    The photochemical decomposition of CO2(ice) at 75 K by Lyman-α radiation (10.2 eV) has been studied using transmission infrared spectroscopy. An isotope effect in the decomposition of the CO2 molecule in the ice has been discovered, favoring 12CO2 photodecomposition over 13CO2 by about 10%. The effect is caused by electronic energy transfer from the excited CO2 molecule to the ice matrix, which favors quenching of the heavier electronically-excited 13CO2 molecule over 12CO2. The effect is similar to the Menzel-Gomer-Redhead isotope effect in desorption from adsorbed molecules on surfaces when electronically excited. An enhancement of the rate of formation of lattice-trapped CO and CO3 species is observed for the photolysis of the 12CO2 molecule compared to the 13CO2 molecule in the ice. Only 0.5% of the primary photoexcitation results in O-CO bond dissociation to produce trapped-CO and trapped-CO3 product molecules and the majority of the electronically-excited CO2 molecules return to the ground state. Here either vibrational relaxation occurs (majority process) or desorption of CO2 occurs (minority process) from highly vibrationally-excited CO2 molecules in the ice. The observation of the 12C/13C isotope effect in the Lyman-α induced photodecomposition of CO2 (ice) suggests that over astronomical time scales the isotope enrichment effect may distort historical information derived from isotope ratios in space wherever photochemistry can occur.

  4. A ground-based imaging study of galaxies causing damped Lyman α (DLA), sub-DLA and Lyman limit system absorption in quasar spectra

    NASA Astrophysics Data System (ADS)

    Rao, Sandhya M.; Belfort-Mihalyi, Michèle; Turnshek, David A.; Monier, Eric M.; Nestor, Daniel B.; Quider, Anna

    2011-09-01

    We present results from a search for galaxies that give rise to damped Lyman α (DLA), sub-DLA and Lyman limit system (LLS) absorption at redshifts 0.1 ≲z≲ 1 in the spectra of background quasars. The sample was formed from a larger sample of strong Mg II absorbers (Wλ27960≥ 0.3 Å) whose H I column densities were determined by measuring the Lyα line in Hubble Space Telescope ultraviolet spectra. Photometric redshifts, galaxy colours and proximity to the quasar sightline, in decreasing order of importance, were used to identify galaxies responsible for the absorption. Our sample includes 80 absorption systems for which the absorbing galaxies have been identified, of which 54 are presented here for the first time. In some cases a reasonable identification for the absorbing galaxy could not be made. The main results of this study are (i) the surface density of galaxies falls off exponentially with increasing impact parameter, b, from the quasar sightline relative to a constant background of galaxies, with an e-folding length of ≈46 kpc. Galaxies with b≳ 100 kpc calculated at the absorption redshift are statistically consistent with being unrelated to the absorption system, and are either background or foreground galaxies. (ii) ? is inversely correlated with b at the 3.0σ level of significance. DLA galaxies are found systematically closer to the quasar sightline, by a factor of 2, than are galaxies which give rise to sub-DLAs or LLSs. The median impact parameter is 17.4 kpc for the DLA galaxy sample, 33.3 kpc for the sub-DLA sample and 36.4 kpc for the LLS sample. We also find that the decline in ? with b can be roughly described by an exponential with an e-folding length of 12 kpc that occurs at ?. (iii) Absorber galaxy luminosity relative to L*, L/L*, is not significantly correlated with Wλ27960, ? or b. (iv) DLA, sub-DLA and LLS galaxies comprise a mix of spectral types, but are inferred to be predominantly late-type galaxies based on their spectral

  5. The large-scale cross-correlation of Damped Lyman alpha systems with the Lyman alpha forest: first measurements from BOSS

    SciTech Connect

    Font-Ribera, Andreu; Miralda-Escudé, Jordi; Arnau, Eduard; Carithers, Bill; Ross, Nicholas P.; White, Martin; Lee, Khee-Gan; Noterdaeme, Pasquier; Pâris, Isabelle; Petitjean, Patrick; Rollinde, Emmanuel; Rich, James; Schneider, Donald P.; York, Donald G. E-mail: miralda@icc.ub.edu

    2012-11-01

    We present the first measurement of the large-scale cross-correlation of Lyα forest absorption and Damped Lyman α systems (DLA), using the 9th Data Release of the Baryon Oscillation Spectroscopic Survey (BOSS). The cross-correlation is clearly detected on scales up to 40h{sup −1}Mpc and is well fitted by the linear theory prediction of the standard Cold Dark Matter model of structure formation with the expected redshift distortions, confirming its origin in the gravitational evolution of structure. The amplitude of the DLA-Lyα cross-correlation depends on only one free parameter, the bias factor of the DLA systems, once the Lyα forest bias factors are known from independent Lyα forest correlation measurements. We measure the DLA bias factor to be b{sub D} = (2.17±0.20)β{sub F}{sup 0.22}, where the Lyα forest redshift distortion parameter β{sub F} is expected to be above unity. This bias factor implies a typical host halo mass for DLAs that is much larger than expected in present DLA models, and is reproduced if the DLA cross section scales with halo mass as M{sub h}{sup α}, with α = 1.1±0.1 for β{sub F} = 1. Matching the observed DLA bias factor and rate of incidence requires that atomic gas remains extended in massive halos over larger areas than predicted in present simulations of galaxy formation, with typical DLA proper sizes larger than 20 kpc in host halos of masses ∼ 10{sup 12}M{sub ☉}. We infer that typical galaxies at z ≅ 2 to 3 are surrounded by systems of atomic clouds that are much more extended than the luminous parts of galaxies and contain ∼ 10% of the baryons in the host halo.

  6. Hydrogen Balmer alpha intensity distributions and line profiles from multiple scattering theory using realistic geocoronal models

    NASA Technical Reports Server (NTRS)

    Anderson, D. E., Jr.; Meier, R. R.; Hodges, R. R., Jr.; Tinsley, B. A.

    1987-01-01

    The H Balmer alpha nightglow is investigated by using Monte Carlo models of asymmetric geocoronal atomic hydrogen distributions as input to a radiative transfer model of solar Lyman-beta radiation in the thermosphere and atmosphere. It is shown that it is essential to include multiple scattering of Lyman-beta radiation in the interpretation of Balmer alpha airglow data. Observations of diurnal variation in the Balmer alpha airglow showing slightly greater intensities in the morning relative to evening are consistent with theory. No evidence is found for anything other than a single sinusoidal diurnal variation of exobase density. Dramatic changes in effective temperature derived from the observed Balmer alpha line profiles are expected on the basis of changing illumination conditions in the thermosphere and exosphere as different regions of the sky are scanned.

  7. Country Education Profiles: Albania.

    ERIC Educational Resources Information Center

    International Bureau of Education, Geneva (Switzerland).

    One of a series of profiles prepared by the Cooperative Educational Abstracting Service, this brief outline provides basic background information on educational principles, system of administration, structure and organization, curricula, and teacher training in Albania. Statistics provided by the Unesco Office of Statistics show enrollment at all…

  8. Investigation of Lyman-limit absorption in QSO spectra - indirect evidence for evolution of the multicomponent nature of the absorbers

    SciTech Connect

    Lanzetta, K.M.

    1988-09-01

    This paper reexamines the redshift distribution of the class of QSO absorption-line systems that are optically-thick to Lyman continuum radiation (i.e., the Lyman-limit systems LLS), using a sample of 129 QSOs for which suitable data are available. It was found that the LLSs are uniformly distributed in velocity, relative to the background QSOs, and that the rate of incidence of the systems does not strongly evolve with redshift; the observed redshift distribution is consistent with nonevolving absorbers in a standard Friedmann cosmology with the deceleration parameter equal to 0.5. The reason for the discrepancy of this finding with data published on systems selected on the basis of Mg II absorption is discussed. It is suggested that the number of separate velocity components comprising the Mg II absorption lines decreases with time. 63 references.

  9. Experimental investigation of the relation between H- negative ion density and Lyman-α emission intensity in a microwave discharge

    NASA Astrophysics Data System (ADS)

    Aleiferis, S.; Tarvainen, O.; Svarnas, P.; Bacal, M.; Béchu, S.

    2016-03-01

    A new mechanism for producing negative ions in low density and low power hydrogen plasmas was proposed recently. It refers to anion formation due to collisions between hydrogen atoms being in the first excited state. The proposed mechanism was indirectly supported by the quadratic relation observed between the extracted negative ion current and Lyman-α radiation of a filament-driven arc discharge, when borrowed data from the literature were combined. The present work provides experimental data comparing directly the absolute negative ion density and Lyman-α radiation in an ECR-driven hydrogen plasma source. The previously mentioned quadratic relation is not observed in the specific source studied, underlying the difficulty of distinguishing between the proposed mechanism and other negative ion production paths.

  10. Laboratory studies of UV emissions of H2 by electron impact - The Werner- and Lyman-band systems

    NASA Technical Reports Server (NTRS)

    Ajello, J. M.; Srivastava, S. K.; Yung, Y. L.

    1982-01-01

    The vacuum ultraviolet electron-impact-induced fluorescence emissions of H2 were studied for the Lyman and Werner band systems in the range of 120-170 nm, using an optical system containing a photomultiplier and a spectrometer, over an energy range from threshold to 400 eV. The emission cross sections for the Lyman and Werner transitions at 100 eV are determined. The cross-section ratio is in excellent agreement with theoretical calculations and experimental data for the optical oscillator strengths. The cross-section for cascading to the B state is stated as a percentage of the total emission cross section at both 100 and 300 eV, increasing substantially at 20 eV. The vibrational population distribution of the B state is found to be a function of electron-impact energy as the importance of cascading relative to direct excitation changes with electron-impact energy.

  11. Rest-Frame Mid-Infrared Detection of an Extremely Luminous Lyman Break Galaxy with the Spitzer Infrared Spectrograph (IRS)

    NASA Technical Reports Server (NTRS)

    Teplitz, H. I.; Charmandaris, V.; Armus, L.; Appleton, P. N.; Houck, J. R.; Soifer, B. T.; Weedman, D.; Brandl, B. R.; vanCleve, J.; Grillmair, C.; Uchid, K. I.

    2004-01-01

    We present the first rest-frame of approximately 4 microns detection of a Lyman break galaxy. The data were obtained using the 16 microns imaging capability of the Spitzer Infrared Spectrograph. The target object, J134026.44+634433.2, is an extremely luminous Lyman break galaxy at z=2.79, first identified in Sloan Digital Sky Survey (SDSS) spectra (as reported by Bentz et al.). The source is strongly detected with a flux of 0.94 +/- 0.02 mJy. Combining Spitzer and SDSS photometry with supporting ground-based J- and K-band data, we show that the spectral energy distribution is consistent with an actively star-forming galaxy. We also detect other objects in the Spitzer field of view, including a very red mid-infrared source. We find no evidence of a strong lens among the mid-infrared sources.

  12. Temporally Resolved Spectral Structure of 821 nm Broad-Area Laser Diode Seeder for Muonium Lyman-Alpha Generation

    NASA Astrophysics Data System (ADS)

    Okamura, Kotaro; Saito, Norihito; Miyazaki, Koji; Oishi, Yu; Louchev, Oleg; Iwasaki, Masahiko; Wada, Satoshi

    To match the Lyman-alpha bandwidth with the Doppler-broadening of thermal Muonium, 230 GHz bandwidth is required for the 821 nm output of OPO + OPA, hence that of their seeder. We selected a broad-area laser diode with bandwidth-selection using a thin solid etalon and successfully realized bandwidth- and wavelength- tunable output which satisfied the requirements.

  13. Performance Characterization of UV Science Cameras Developed for the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP)

    NASA Technical Reports Server (NTRS)

    Champey, Patrick; Kobayashi, Ken; Winebarger, Amy; Cirtin, Jonathan; Hyde, David; Robertson, Bryan; Beabout, Brent; Beabout, Dyana; Stewart, Mike

    2014-01-01

    The NASA Marshall Space Flight Center (MSFC) has developed a science camera suitable for sub-orbital missions for observations in the UV, EUV and soft X-ray. Six cameras will be built and tested for flight with the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP), a joint National Astronomical Observatory of Japan (NAOJ) and MSFC sounding rocket mission. The goal of the CLASP mission is to observe the scattering polarization in Lyman-alpha and to detect the Hanle effect in the line core. Due to the nature of Lyman-alpha polarization in the chromosphere, strict measurement sensitivity requirements are imposed on the CLASP polarimeter and spectrograph systems; science requirements for polarization measurements of Q/I and U/I are 0.1% in the line core. CLASP is a dual-beam spectro-polarimeter, which uses a continuously rotating waveplate as a polarization modulator, while the waveplate motor driver outputs trigger pulses to synchronize the exposures. The CCDs are operated in frame-transfer mode; the trigger pulse initiates the frame transfer, effectively ending the ongoing exposure and starting the next. The strict requirement of 0.1% polarization accuracy is met by using frame-transfer cameras to maximize the duty cycle in order to minimize photon noise. Coating the e2v CCD57-10 512x512 detectors with Lumogen-E coating allows for a relatively high (30%) quantum efficiency at the Lyman-$\\alpha$ line. The CLASP cameras were designed to operate with =10 e- /pixel/second dark current, = 25 e- read noise, a gain of 2.0 and =0.1% residual non-linearity. We present the results of the performance characterization study performed on the CLASP prototype camera; dark current, read noise, camera gain and residual non-linearity.

  14. The latitudinal dependence of the solar ionization rate as deduced from the Prognoz-6 Lyman-alpha measurements

    NASA Astrophysics Data System (ADS)

    Summanen, T.; Kyrola, E.; Lallement, R.; Bertaux, J. L.

    The latitudinal dependence of the solar ionization is studied using the Lyman-alpha measurements by the Prognoz-6 spacecraft during the solar minimum 1976-77. Applying a hot model for the interplanetary H-gas we have searched for an optimal ionization function to comply with the measurements. Using the optimal ionization function we have studied the latitudinal variation of the solar wind mass flux and the proton density.

  15. The Electron Excitation Function of H Lyman-(alpha) from Threshold to 1.8 keV

    NASA Technical Reports Server (NTRS)

    James, G. K.; Slevin, J. A.; Shemansky, D. E.; McConkey, J. W.; Dziczek, D.; Kanik, I.; Ajello, J. M.

    1996-01-01

    The excitation function of prompt Lyman-(alpha) radiation, produced by electron impact excitation of atomic hydrogen, has been measured for the first time over an extended energy range from threshold to 1.8 keV. Measurments were obtained in a crossed-beams experiment using both magnetically confined and electrostatically focused electrons in collision with atomic hydrogen produced by an intense discharge source.

  16. Diagnosing the reionization of the universe - The absorption spectrum of the intergalactic medium and Lyman alpha clouds

    NASA Technical Reports Server (NTRS)

    Giroux, Mark L.; Shapiro, Paul R.

    1991-01-01

    The thermal and ionization evolution of a uniform intergalactic medium composed of H and He and undergoing reionization is studied. The diagnosis of the metagalactic ionizing radiation background at z of about three using metal line ratios for Lyman limit quasar absorption line systems is addressed. The use of the He II Gunn-Peterson effect to diagnose the reionization source and/or nature of the Hy-alpha forest clouds is considered.

  17. Aberration-corrected aspheric grating designs for the Lyman/Far-Ultraviolet Spectroscopic Explorer high-resolution spectrograph - A comparison

    NASA Technical Reports Server (NTRS)

    Trout, Catherine; Content, David; Davila, Pam

    1992-01-01

    Two approaches to reducing the optical aberrations of concave diffraction gratings have been studied to obtain candidate grating designs for the Lyman/Far-Ultraviolet Spectroscopic Explorer mission. The first approach involves shaping the grating substrate while using straight and equally spaced grooves. The second approach involves using a gating substrate with a relatively simple figure and holographically controlling the groove curvature and spacing. Specific designs derived from both approaches are analyzed and compared.

  18. COMPARISON OF PIONEER 10, VOYAGER 1, AND VOYAGER 2 ULTRAVIOLET OBSERVATIONS WITH ANTI-SOLAR LYMAN-ALPHA BACKSCATTER SIMULATIONS

    SciTech Connect

    Fayock, B.; Zank, G. P.; Heerikhuisen, J. E-mail: garyp.zank@gmail.com

    2013-09-20

    Observations made by ultraviolet (UV) detectors on board Pioneer 10, Voyager 1, and Voyager 2 can be used to analyze the distribution of neutral hydrogen throughout the heliosphere, including the interaction regions of the solar wind and local interstellar medium. Previous studies of the long-term trend of decreasing intensity with increasing heliocentric distance established the need for more sophisticated heliospheric models. Here we use state-of-the-art three-dimensional (3D) magnetohydrodynamic (MHD) neutral models to simulate Lyman-alpha backscatter as would be seen by the three spacecrafts, exploiting a new 3D Monte Carlo radiative transfer code under solar minimum conditions. Both observations and simulations of the UV backscatter intensity are normalized for each spacecraft flight path at {approx}15 AU, and we focus on the slope of decreasing intensity over an increasing heliocentric distance. Comparisons of simulations with Voyager 1 Lyman-alpha data results in a very close match, while the Pioneer 10 comparison is similar due to normalization, but not considered to be in agreement. The deviations may be influenced by a low resolution of photoionization in the 3D MHD-neutral model, a lack of solar cycle activity in our simulations, and possibly issues with instrumental sensitivity. Comparing the slope of Voyager 2 and the simulated intensities yields an almost identical match. Our results predict a large increase in the Lyman-alpha intensity as the hydrogen wall is approached, which would signal an imminent crossing of the heliopause.

  19. Sowing Black Hole Seeds: Forming Direct Collapse Black Holes With Realistic Lyman-Werner Radiation Fields in Cosmological Simulations

    NASA Astrophysics Data System (ADS)

    Holley-Bockelmann, Kelly; Dunn, Glenna; Bellovary, Jillian M.; Christensen, Charlotte

    2016-01-01

    Luminous quasars detected at redshifts z > 6 require that the first black holes form early and grow to ~109 solar masses within one Gyr. Our work uses cosmological simulations to study the formation and early growth of direct collapse black holes. In the pre-reionization epoch, molecular hydrogen (H2) causes gas to fragment and form Population III stars, but Lyman-Werner radiation can suppress H2 formation and allow gas to collapse directly into a massive black hole. The critical flux required to inhibit H2 formation, Jcrit, is hotly debated, largely due to the uncertainties in the source radiation spectrum, H2 self-shielding, and collisional dissociation rates. Here, we test the power of the direct collapse model in a non-uniform Lyman-Werner radiation field, using an updated version of the SPH+N-body tree code Gasoline with H2 non-equilibrium abundance tracking, H2 cooling, and a modern SPH implementation. We vary Jcrit from 30 to 104 J21 to study the effect on seed black holes, focusing on black hole formation as a function of environment, halo mass, metallicity, and proximity of the Lyman-Werner source. We discuss the constraints on massive black hole occupation fraction in the quasar epoch, and implications for reionization, high-redshift X-ray background radiation, and gravitational waves.

  20. PEP/HerMES/COSMOS: What are the dust properties of z ˜ 3 lyman break galaxies?

    NASA Astrophysics Data System (ADS)

    Álvarez-Márquez, A.; Burgarella, D.; Buat, V.; Heinis, S.; Pep/Hermes/Cosmos Teams

    2015-05-01

    Context. Since the mid-90's, the sample of Lyman break galaxies has been growing up thanks to the deeper and deeper sensitivities of the telescope in optical and in near-infrared for objects at z > 2.5. However, the dust properties of these Lyman break galaxies are still elusive of badly known because the samples are small and/or biased.} Aims. We explore the dust properties in a statistical way of a sample of Lyman break galaxies (LBGs) that can not be individually detected in Herschel maps. Methods. We apply a stacking method in the Herschel and AzTEC maps to LBGs selected at 2.5 < z < 3.5 by dropout technique. Thanks to the size of the sample (˜22 000 LBGs), we can split it in several bins as a function of their ultraviolet luminosity (L_{FUV}), their ultraviolet slope (β_{UV}) and their stellar mass (M_{*}) to better catch their variety. The stacking is corrected for the incompleteness in the priors and for the clustering of the stacked galaxies in ultraviolet. Results. We obtain the full infrared spectral energy distributions of our LBGs as a function of their L_{FUV}, their β_{UV} and their M_* and we can characterize them in terms of their dust attenuation A_{FUV}, their star formation rate (SFR).

  1. Predicting the Extreme-UV and Lyman-α Fluxes Received by Exoplanets from their Host Stars

    NASA Astrophysics Data System (ADS)

    Linsky, Jeffrey L.; France, Kevin; Ayres, Thomas R.

    2015-01-01

    Extreme-UV (EUV) radiation from the chromospheres, transition regions, and coronae of host stars (spectral types F, G, K, and M) ionize and heat the outer atmospheres of exoplanets leading to mass loss that is observed during transits and can change the exoplanet's atmosphere. Lyman-α emission from host stars controls the photochemistry in the upper layers of planetary atmospheres by photodissociating important molecules including H_2O, CO_2, CH_4, thereby increasing the oxygen and ozone mixing ratios important for habitability. Both the EUV and strong Lyman-α radiation are largely absorbed by the interstellar medium and must be reconstructed or estimated to understand the radiation environment of exoplanets. In two recent papers, tet{Linsky2013} and tet{Linsky2014}, we have presented robust methods for predicting the intrinsic Lyman-α and EUV fluxes from main sequence cool stars. Solar models and satellite observations (HST, FUSE, and EUVE) provide tests for the feasibility of these methods.

  2. Molecular Gas in the Lensed Lyman Break Galaxy cB58

    NASA Astrophysics Data System (ADS)

    Baker, Andrew J.; Tacconi, Linda J.; Genzel, Reinhard; Lehnert, Matthew D.; Lutz, Dieter

    2004-03-01

    We have used the IRAM Plateau de Bure Interferometer to map CO (3-2) emission from the gravitationally lensed Lyman break galaxy MS 1512-cB58. This is the first detection of a molecular emission line in any Lyman break system; its integrated intensity implies a total molecular gas mass of (6.6+5.8-4.3)×109 h-20.7 Msolar, while its width implies a dynamical mass of (1.0+0.6-0.4)×1010csc2i h-10.7 Msolar (for a flat ΩΛ=0.7 cosmology). These estimates are in excellent concordance with nearly all parameters of the system measured at other wavelengths and yield a consistent picture of past and future star formation with no obvious discrepancies requiring explanation by differential lensing. In particular, we find that the age and remaining lifetime of the current episode of star formation are likely to be similar, the surface densities of star formation and molecular gas mass are related by a Schmidt law, and the fraction of baryonic mass already converted into stars is sufficient to account for the observed enrichment of the interstellar medium to 0.4 Zsolar. Barring substantial gas inflow or a major merger, the stars forming in the current episode will have mass and coevality at z=0 similar to those of a spiral bulge. Assuming that cB58 is a typical Lyman break galaxy apart from its magnification, its global parameters suggest that the prescriptions for star formation used in some semianalytic models of galaxy evolution require moderate revision, although the general prediction that gas mass fraction should increase with redshift is validated. The length of cB58's star formation episode relative to the time elapsed over the redshift range 2.5<=z<=3.5 strongly argues against scenarios in which observed LBGs cohabit their halos with a large number of similar but ``dormant'' systems whose starbursts have faded or not yet begun. As a useful empirical result, we find that the observed line/continuum ratio for cB58 is similar to those of high-redshift systems with quite

  3. Population Profiles: A Series of Units on Specific Topics for the Study of Demography. Number 17. The Family - What Is Its Situation Today? Is It Imperilled as an Institution?

    ERIC Educational Resources Information Center

    Scudder, Townsend, Ed.

    The sociological factors related to marriage and divorce are discussed in this Population Profile. Statistics concerning marital status, marriage stability, divorce, and remarriage are presented and discussed. Alternate life styles are included in the publication, as well as predictions for the future based on present trends. This publication is…

  4. The escape of Lyman photons from a young starburst: the case of Haro11†

    NASA Astrophysics Data System (ADS)

    Hayes, Matthew; Östlin, Göran; Atek, Hakim; Kunth, Daniel; Mas-Hesse, J. Miguel; Leitherer, Claus; Jiménez-Bailón, Elena; Adamo, Angela

    2007-12-01

    Lyman α (Lyα) is one of the dominant tools used to probe the star-forming galaxy population at high redshift (z). However, astrophysical interpretations of data drawn from Lyα alone hinge on the Lyα escape fraction which, due to the complex radiative transport, may vary greatly. Here, we map the Lyα emission from the local luminous blue compact galaxy Haro11, a known emitter of Lyα and the only known candidate for low-z Lyman continuum emission. To aid in the interpretation, we perform a detailed ultraviolet and optical multiwavelength analysis and model the stellar population, dust distribution, ionizing photon budget, and star-cluster population. We use archival X-ray observations to further constrain properties of the starburst and estimate the neutral hydrogen column density. The Lyα morphology is found to be largely symmetric around a single young star-forming knot and is strongly decoupled from other wavelengths. From general surface photometry, only very slight correlation is found between Lyα and Hα, E(B - V), and the age of the stellar population. Only around the central Lyα bright cluster do we find the Lyα/Hα ratio at values predicted by the recombination theory. The total Lyα escape fraction is found to be just 3 per cent. We compute that ~90 per cent of the Lyα photons that escape do so after undergoing multiple resonance scattering events, masking their point of origin. This leads to a largely symmetric distribution and, by increasing the distance that photons must travel to escape, decreases the escape probability significantly. While dust must ultimately be responsible for the destruction of Lyα, it plays a little role in governing the observed morphology, which is regulated more by interstellar medium kinematics and geometry. We find tentative evidence for local Lyα equivalent width in the immediate vicinity of star clusters being a function of cluster age, consistent with hydrodynamic studies. We estimate the intrinsic production

  5. X-Ray Properties of Lyman Break Galaxies in the Hubble Deep Field North Region

    NASA Technical Reports Server (NTRS)

    Nandra, K.; Mushotzky, R. F.; Arnaud, K.; Steidel, C. C.; Adelberger, K. L.; Gardner, J. P.; Teplitz, H. I.; Windhorst, R. A.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    We describe the X-ray properties of a large sample of z approximately 3 Lyman Break Galaxies (LBGs) in the region of the Hubble Deep Field North, derived from the 1 Ms public Chandra observation. Of our sample of 148 LBGs, four are detected individually. This immediately gives a measure of the bright AGN (active galactic nuclei) fraction in these galaxies of approximately 3 per cent, which is in agreement with that derived from the UV (ultraviolet) spectra. The X-ray color of the detected sources indicates that they are probably moderately obscured. Stacking of the remainder shows a significant detection (6 sigma) with an average luminosity of 3.5 x 10(exp 41) erg/s per galaxy in the rest frame 2-10 keV band. We have also studied a comparison sample of 95 z approximately 1 "Balmer Break" galaxies. Eight of these are detected directly, with at least two clear AGN based on their high X-ray luminosity and very hard X-ray spectra respectively. The remainder are of relatively low luminosity (< 10(exp 42) erg/s, and the X-rays could arise from either AGN or rapid star-formation. The X-ray colors and evidence from other wavebands favor the latter interpretation. Excluding the clear AGN, we deduce a mean X-ray luminosity of 6.6 x 10(exp 40) erg/s, a factor approximately 5 lower than the LBGs. The average ratio of the UV and X-ray luminosities of these star forming galaxies L(sub UV)/L (sub X), however, is approximately the same at z = 1 as it is at z = 3. This scaling implies that the X-ray emission follows the current star formation rate, as measured by the UV luminosity. We use our results to constrain the star formation rate at z approximately 3 from an X-ray perspective. Assuming the locally established correlation between X-ray and far-IR (infrared) luminosity, the average inferred star formation rate in each Lyman break galaxy is found to be approximately 60 solar mass/yr, in excellent agreement with the extinction-corrected UV estimates. This provides an external

  6. Zinc abundances in Galactic bulge field red giants: Implications for damped Lyman-α systems

    NASA Astrophysics Data System (ADS)

    Barbuy, B.; Friaça, A. C. S.; da Silveira, C. R.; Hill, V.; Zoccali, M.; Minniti, D.; Renzini, A.; Ortolani, S.; Gómez, A.

    2015-08-01

    Context. Zinc in stars is an important reference element because it is a proxy to Fe in studies of damped Lyman-α systems (DLAs), permitting a comparison of chemical evolution histories of bulge stellar populations and DLAs. In terms of nucleosynthesis, it behaves as an alpha element because it is enhanced in metal-poor stars. Abundance studies in different stellar populations can give hints to the Zn production in different sites. Aims: The aim of this work is to derive the iron-peak element Zn abundances in 56 bulge giants from high resolution spectra. These results are compared with data from other bulge samples, as well as from disk and halo stars, and damped Lyman-α systems, in order to better understand the chemical evolution in these environments. Methods: High-resolution spectra were obtained using FLAMES+UVES on the Very Large Telescope. We computed the Zn abundances using the Zn i lines at 4810.53 and 6362.34 Å. We considered the strong depression in the continuum of the Zn i 6362.34 Å line, which is caused by the wings of the Ca i 6361.79 Å line suffering from autoionization. CN lines blending the Zn i 6362.34 Å line are also included in the calculations. Results: We find [Zn/Fe] = +0.24 ± 0.02 in the range -1.3 < [Fe/H] < -0.5 and [Zn/Fe] = + 0.06 ± 0.02 in the range -0.5 < [Fe/H] < -0.1, whereas for [Fe/H] ≥ -0.1, it shows a spread of -0.60 < [Zn/Fe] < + 0.15, with most of these stars having low [Zn/Fe] < 0.0. These low zinc abundances at the high metallicity end of the bulge define a decreasing trend in [Zn/Fe] with increasing metallicities. A comparison with Zn abundances in DLA systems is presented, where a dust-depletion correction was applied for both Zn and Fe. When we take these corrections into account, the [Zn/Fe] vs. [Fe/H] of the DLAs fall in the same region as the thick disk and bulge stars. Finally, we present a chemical evolution model of Zn enrichment in massive spheroids, representing a typical classical bulge evolution

  7. Studying low-redshift universe through observation of Damped Lyman-alpha quasar absorbers

    NASA Astrophysics Data System (ADS)

    Gharanfoli, Soheila

    2009-06-01

    In recent years, an extremely successful method to study galaxy formation and evolution, has been provided by observation of quasar absorbers. Quasar absorbers are systems intercepting our line-of-sight to a given quasar and thus produce a feature in the quasar spectrum, the so-called absorption lines. The Damped Lyman-a (DLA) and sub-Damped Lyman-a (sub-DLA) absorption features in quasar spectra are believed to be produced by intervening galaxies. However, the connection of quasar absorbers to galaxies is not well-understood, since attempts to image the absorbing galaxies have often failed. DLAs and sub-DLAs were originally thought to be the precursors of present day disk galaxies, but there is evidence that they may be dominated by gas-rich, proto-dwarf galaxies representing the basic building blocks of hierarchical growth of structure. While most DLAs appear to be metal-poor, a population of metal-rich absorbers, mostly sub-DLAs, has been discovered in recent spectroscopic studies. It is of great interest to image these metal-rich absorbers, especially with high spatial resolution, to understand the connection between the stellar and interstellar content of the underlying galaxies. This dissertation consists of several projects designed to further our understanding of galaxies and galactic structures associated with intervening quasar absorption lines. Two projects were completed that involved the imaging of 13 DLA/sub-DLA galaxies at z < 1. High angular resolution near-infrared images were obtained, using the Hokupa'a Adaptive Optics system with the QUIRC near-infrared camera on the 8-m Gemini-North telescope, and the Laser Guide Star Adaptive Optics system on the 10-m Keck telescope. Detailed properties of the identified absorber galaxies are described. They are shown to be drawn from a variety of morphological types with a range of luminosities, sizes, and impact parameters. In the other set of projects, follow-up spectroscopy was performed to confirm the

  8. A High-Resolution Hubble Space Telescope Study of Apparent Lyman Continuum Leakers at z~3

    NASA Astrophysics Data System (ADS)

    Mostardi, R. E.; Shapley, A. E.; Steidel, C. C.; Trainor, R. F.; Reddy, N. A.; Siana, B.

    2015-09-01

    We present U336V606J125H160 follow-up Hubble Space Telescope (HST) observations of 16 z ˜ 3 candidate Lyman continuum (LyC) emitters in the HS1549+1919 field. With these data, we obtain high spatial-resolution photometric redshifts of all sub-arcsecond components of the LyC candidates in order to eliminate foreground contamination and identify robust candidates for leaking LyC emission. Of the 16 candidates, we find one object with a robust LyC detection that is not due to foreground contamination. This object (MD5) resolves into two components; we refer to the LyC-emitting component as MD5b. MD5b has an observed 1500 Å to 900 Å flux-density ratio of {({F}{UV}/{F}{LyC})}{obs}=4.0+/- 2.0, compatible with predictions from stellar population synthesis models. Assuming minimal IGM absorption, this ratio corresponds to a relative (absolute) escape fraction of {f}{esc,{rel}}{MD5{{b}}} = 75%-100% ({f}{esc,{abs}}{MD5{{b}}} = 14%-19%). The stellar population fit to MD5b indicates an age of ≲50 Myr, which is in the youngest 10% of the HST sample and the youngest third of typical z ˜ 3 Lyman break galaxies, and may be a contributing factor to its LyC detection. We obtain a revised, contamination-free estimate for the comoving specific ionizing emissivity at z = 2.85, indicating (with large uncertainties) that star-forming galaxies provide roughly the same contribution as QSOs to the ionizing background at this redshift. Our results show that foreground contamination prevents ground-based LyC studies from obtaining a full understanding of LyC emission from z ˜ 3 star-forming galaxies. Future progress in direct LyC searches is contingent upon the elimination of foreground contaminants through high spatial-resolution observations, and upon acquisition of sufficiently deep LyC imaging to probe ionizing radiation in high-redshift galaxies.

  9. Evidence for Black Hole Growth in Local Analogs to Lyman Break Galaxies

    NASA Technical Reports Server (NTRS)

    Jia, Jianjun; Ptak, Andrew; Heckman, Timothy M.; Overzier, Roderik A.; Hornschemeier, Ann; LaMassa, Stephanie M.

    2011-01-01

    We have used XMM-Newton to observe six Lyman break analogs (LBAs): members of the rare population of local galaxies that have properties that are very similar to distant Lyman break galaxies. Our six targets were specifically selected because they have optical emission-line properties that are intermediate between starbursts and Type 2 (obscured) active galactic nuclei (AGNs). Our new X-ray data provide an important diagnostic of the presence of an AGN. We find X-ray luminosities of order 10(sup 42) erg per second and ratios of X-ray to far-IR lummositles that are higher than values in pure starburst galaxies by factors ranging from approximately 3 to 30. This strongly suggests the presence of an AGN in at least some of the galaxies. The ratios of the luminosities of the hard (2-10 keV) X-ray to [O III] emission line are low by about an order of magnitude compared with Type 1 AGN, but are consistent with the broad range seen in Type 2 AGN. Either the AGN hard X-rays are significantly obscured or the [O III] emission is dominated by the starburst. We searched for an iron emission line at approximately 6.4 ke V, which is a key feature of obscured AGNs, but only detected emission at the approximately 2sigma level. Finally, we find that the ratios of the mid-infrared (24 micrometer) continuum to [O III]lambda 5007 luminosities in these LBAs are higher than the values for Type 2 AGN by an average of 0.8 dex. Combining all these clues, we conclude that an AGN is likely to be present, but that the bolometric luminosity is produced primarily by an intense starburst. If these black holes are radiating at the Eddington limit, their masses would lie in the range of 10(sup 5) - 10(sup 6) solar mass. These objects may offer ideal local laboratories to investigate the processes by which black holes grew in the early universe.

  10. A HUBBLE SPACE TELESCOPE STUDY OF LYMAN LIMIT SYSTEMS: CENSUS AND EVOLUTION

    SciTech Connect

    Ribaudo, Joseph; Lehner, Nicolas; Howk, J. Christopher

    2011-07-20

    We present a survey for optically thick Lyman limit absorbers at z < 2.6 using archival Hubble Space Telescope observations with the Faint Object Spectrograph and Space Telescope Imaging Spectrograph. We identify 206 Lyman limit systems (LLSs), increasing the number of cataloged LLSs at z < 2.6 by a factor of {approx}10. We compile a statistical sample of 50 {tau}{sub LLS} {>=} 2 LLSs drawn from 249 QSO sight lines that avoid known targeting biases. The incidence of such LLSs per unit redshift, l(z) = dn/dz, at these redshifts is well described by a single power law, l(z){proportional_to}(1 + z){sup {gamma}}, with {gamma} = 1.33 {+-} 0.61 at z < 2.6, or with {gamma} = 1.83 {+-} 0.21 over the redshift range 0.2 {<=} z {<=} 4.9. The incidence of LLSs per absorption distance, l(X), decreases by a factor of {approx}1.5 over the {approx}0.6 Gyr from z = 4.9 to 3.5; l(X) evolves much more slowly at low redshifts, decreasing by a similar factor over the {approx}8 Gyr from z = 2.6 to 0.25. We show that the column density distribution function, f(N{sub HI}), at low redshift is not well fitted by a single power-law index (f(N{sub HI}) {proportional_to} N{sup -}{beta}{sub HI}) over the column density range 13 {<=} log N{sub HI} {<=} 22 or log N{sub HI} {>=} 17.2. While low- and high-redshift f(N{sub HI}) distributions are consistent for log N{sub HI}>19.0, there is some evidence that f(N{sub HI}) evolves with z for log N{sub HI} {approx}< 17.7, possibly due to the evolution of the UV background and galactic feedback. Assuming LLSs are associated with individual galaxies, we show that the physical cross section of the optically thick envelopes of galaxies decreased by a factor of {approx}9 from z {approx} 5 to 2 and has remained relatively constant since that time. We argue that a significant fraction of the observed population of LLSs arises in the circumgalactic gas of sub-L{sub *} galaxies.

  11. A Direct Detection of Gas Accretion: The Lyman Limit System in 3C 232

    NASA Astrophysics Data System (ADS)

    Stocke, John T.; Keeney, Brian A.; Danforth, Charles W.

    2010-06-01

    The gas added to and removed from galaxies over cosmic time greatly affects their stellar populations and star formation rates. QSO absorption line studies in close QSO/galaxy pairs create a unique opportunity to study the physical conditions and kinematics of this gas. Here we present new Hubble Space Telescope (HST) images of the QSO/galaxy pair, 3C 232/NGC 3067. The quasar spectrum contains a Lyman limit (NHi = 1 × 1020 cm-2) absorption system (LLS) at cz = 1421 km s-1 that is associated with the nearby Sab galaxy NGC 3067. Previous work identifies this absorber as a high-velocity cloud (HVC) in NGC 3067 but the kinematics of the absorbing gas, infalling or outflowing, were uncertain. The HST images presented here establish the orientation of NGC 3067 and so establish that the LLS/HVC is infalling. Using this system as a prototype, we extend these results to higher-z Mgii/LLS to suggest that Mgii/LLSs are a sightline sampling of the so-called `cold mode accretion' (CMA) infalling onto luminous galaxies. To match the observed Mgii absorber statistics, the CMA must be more highly ionised at higher redshifts. The key observations needed to further the study of low-z LLSs is HST UV spectroscopy, for which a new instrument, the Cosmic Origins Spectrograph, has just been installed greatly enhancing our observational capabilities.

  12. Primordial lithium in z~0, metal-poor damped Lyman alpha systems

    NASA Astrophysics Data System (ADS)

    Cooke, Ryan

    2013-10-01

    A longstanding challenge for the standard model of Big Bang Nucleosynthesis is to explain the discrepancy between the predicted and observed primordial lithium abundance; the most metal-poor stars are deficient in Li by a factor of 3-4 relative to the standard model prediction. We propose to use the combined efforts of HST+COS and ground-based optical echelle spectrographs, to measure the primordial Li abundance in clouds of near-pristine gas at low redshift. To this end, we have compiled a prime list of sure candidate low-redshift damped Lyman-alpha systems {DLAs} that are in front of bright quasars. This combination is essential to detect the weak Li absorption lines arising in the ISM of external galaxies. For a small investment of HST time, we will confirm these systems as new low-redshift DLAs - almost tripling the current number of known systems - and discern the optimum clouds where the primordial abundance of Li can be measured. The sought-after data will also provide new opportunities to study the detailed properties of DLAs and their host galaxies, as well as the greater environments in which they reside.

  13. LYMAN BREAK GALAXIES AT z approx 5: REST-FRAME UV SPECTRA. III

    SciTech Connect

    Kajino, Hiroki; Ohta, Kouji; Yabe, Kiyoto; Yuma, Suraphong; Iwata, Ikuru; Akiyama, Masayuki; Tamura, Naoyuki; Aoki, Kentaro; Sawicki, Marcin

    2009-10-10

    We present results of optical spectroscopic observations of candidates of Lyman break galaxies (LBGs) at z approx 5 in the region, including the GOODS-N and the J0053+1234 regions by using Gemini Multi-Object Spectrograph North and South, respectively. Among 25 candidates, five objects are identified to be at z approx 5 (two of them were already identified by an earlier study) and one object very close to the color-selection window turned out to be a foreground galaxy. With this spectroscopically identified sample and those from previous studies, we derived the lower limits on the number density of bright (M{sub UV} < -22.0 mag) LBGs at z approx 5. These lower limits are comparable to or slightly smaller than the number densities of UV luminosity functions (UVLFs) that show the smaller number density among z approx 5 UVLFs in literature. However, by considering that there remain many LBG candidates without spectroscopic observations, the number density of bright LBGs is expected to increase by a factor of two or more. The evidence for the deficiency of UV luminous LBGs with large Lyalpha equivalent widths was reinforced. We discuss possible causes for the deficiency and prefer the interpretation of dust absorption.

  14. Solar Cycle Variations of O VI and H I Lyman Alpha Intensities in the Solar Corona

    NASA Astrophysics Data System (ADS)

    Miralles, M. P.; Panasyuk, A. V.; Strachan, L.; Gardner, L. D.; Suleiman, R. M.; Smith, P. L.; Kohl, J. L.

    2000-05-01

    UVCS/SOHO measurements of O VI (103.2 and 103.7 nm) and H I Lyman alpha intensities in the solar corona have been made from 1996 to the present spanning the rising phase of cycle 23. During solar minimum the corona consisted of large coronal holes at the poles and quiescent streamers at the equator. During the ascending phase of the cycle, the corona presented high latitude streamers and finally polar streamers as the Sun approached solar maximum. Recent observations of the solar corona show the presence of coronal holes at the equator and streamers at the poles. Our observations provide descriptions of these structures over the rising phase of the solar cycle. We compare the properties of quiescent equatorial streamers which occurred at solar minimum to high latitude and polar streamers observed toward solar maximum. We also compare solar minimum polar coronal holes to equatorial coronal holes present at solar maximum. We discuss how these results are related to the plasma properties. This work is supported by NASA under Grant NAG5-7822 to the Smithsonian Astrophysical Observatory, by the Italian Space Agency and by PRODEX (Swiss contribution).

  15. An integral field spectroscopic survey for high redshift damped Lyman-α galaxies

    NASA Astrophysics Data System (ADS)

    Christensen, L.; Wisotzki, L.; Roth, M. M.; Sánchez, S. F.; Kelz, A.; Jahnke, K.

    2007-06-01

    Aims:We search for galaxy counterparts to damped Lyman-α absorbers (DLAs) at z > 2 towards nine quasars, which have 14 DLAs and 8 sub-DLAs in their spectra. Methods: We use integral field spectroscopy to search for Lyα emission line objects at the redshifts of the absorption systems. Results: Besides recovering two previously confirmed objects, we find six statistically significant candidate Lyα emission line objects. The candidates are identified as having wavelengths close to the DLA line where the background quasar emission is absorbed. In comparison with the six currently known Lyα emitting DLA galaxies the candidates have similar line fluxes and line widths, while velocity offsets between the emission lines and systemic DLA redshifts are larger. The impact parameters are larger than 10 kpc, and lower column density systems are found at larger impact parameters. Conclusions: Assuming that a single gas cloud extends from the QSO line of sight to the location of the candidate emission line, we find that the average candidate DLA galaxy is surrounded by neutral gas with an exponential scale length of ~5 kpc. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA), operated by the Max-Planck Institut für Astronomie and the Instituto Astrofisica de Andalucia (CSIC). Full Fig. [see full text] is only available in electronic form at http://www.aanda.org

  16. High HI column density lyman limit absorption in z>4 quasars

    NASA Astrophysics Data System (ADS)

    Storrie-Lombardi, L. J.; McMahon, R. G.; Irwin, M. J.; Hazard, C.

    1992-12-01

    The high HI column density Lyman Limit absorption line systems (LLS) are the parent population from which absorbers that are selected on the basis of MgII absorption are drawn. At z=0.5--1.0 the MgII systems have been shown to be associated with the extended halos of bright galaxies (Bergeron & Boisse 1991). Recent work on LLS evolution by Sargent, Steidel & Boksenberg(1989) and Lanzetta(1991) disagree considerably in the form of evolution observed. Whilst SSB claim no evolution in number density up to z=3.5, Lanzetta reports evidence for strong evolution in the number density of LLS for z > 2.5. We shall present results of a low resolution absorption line study of z>4 quasars. The z>4 quasar sample is the ~ 20 brightest non-BAL quasars from the APM z>4 quasar survey. Our observations have been combined with HST observations in low redshift quasars to enable a new determination of the evolution of LLS over the redshift range 0.5 to 4.5. These observations extend absorption line studies to higher redshifts than have been possible before.

  17. Constraints on the gas masses of low-z damped Lyman α systems

    NASA Astrophysics Data System (ADS)

    Mazumdar, Parichay; Kanekar, Nissim; Prochaska, J. Xavier

    2014-09-01

    We report a deep search for redshifted H I 21 cm emission from three damped and sub-damped Lyman α absorbers (DLAs) at z ≈ 0.1 with the Green Bank Telescope (GBT). No evidence for a redshifted H I 21 cm emission signal was obtained in the GBT spectra of two absorbers, with the data on the third rendered unusable by terrestrial interference. The non-detections of H I 21 cm emission yield strong constraints on the H I masses of the associated galaxies, MH I < 2.3 × 109 × (Δ V/100)1/2 M⊙ for the sub-DLA at z = 0.0830 towards J1553+3548 and MH I < 2.7 × 109 × (Δ V/100)1/2 M⊙ for the DLA at z = 0.0963 towards J1619+3342, where ΔV is the H I 21 cm line width, in km s-1. This continues the trend of low H I masses found in all low-z DLAs and sub-DLAs that have been searched for redshifted H I 21 cm emission. Low-redshift absorbers with relatively low H I column densities, ≲ few × 1020 cm-2, thus do not typically arise in massive gas-rich galaxies.

  18. The application of artificial neural networks for telescope guidance - A feasibility study for Lyman FUSE

    NASA Astrophysics Data System (ADS)

    Ozard, Siobhan; Morbey, Christopher

    1993-06-01

    Since the fine error sensor camera of the Lyman Far-Ultraviolet Spectrographic Explorer (FUSE) has significant residual field curvature aberration, the star images over the field of view have a wide variety of shapes. A search for appropriate backup guiding techniques led to the investigation of artificial neural networks (ANNs). Such a technique is shown to be capable of learning the image shapes of stars if they are sufficiently different. This study investigates the feasibility of using image patterns as positional references for telescope guidance to satisfy redundancy requirements for the mission. For this initial simulation, the ANN was trained to categorize images according to how far they were from the center of the field of view (radius). We found that a nonlinear, single hidden layer ANN learned 90 percent of the training patterns, then correctly classified 89 percent of a set of patterns randomly spread over the field of view. This indicates that the network interpolates between training images. Half of the misclassifications are attributed to the image pattern degradation caused by the secondary support structure spider.

  19. Performance characteristics of the imaging MAMA detector systems for SOHO, STIS, and FUSE/Lyman

    NASA Technical Reports Server (NTRS)

    Timothy, J. G.

    1991-01-01

    Imaging Extreme Ultraviolet (EUV) Multi-Anode Microchannel Array (MAMA) detector systems with formats of 360 x 1024 pixels and pixel dimensions of 25 x 25 sq microns are being fabricated and tested for flight in two instruments on the ESA/NASA Solar and Heliospheric Observatory (SOHO). In addition, very-large-format (1024 x 1024)- and (2048 x 2048)-pixel Far Ultraviolet (FUV) and EUV MAMA detectors with pixel dimensions of 25 x 25 sq microns are being fabricated and tested for use in the NASA Goddard Space Flight Center's Hubble Space Telescope Imaging Spectrograph (STIS), a second-generation instrument scheduled for in-orbit installation in 1997. Finally, FUV MAMA detectors with formats of 224 x 960 pixels and pixel dimensions of 14 x 14 sq microns are being evaluated as prototypes of the detector for the prime FUV spectrograph of the Far Ultraviolet Spectroscopic Explorer (FUSE/Lyman) mission. The configurations and performance characteristics of the different detector systems are described, and the plans for further development of the Advanced Technology MAMA detector system discussed.

  20. EFFECT OF HALO BIAS AND LYMAN LIMIT SYSTEMS ON THE HISTORY OF COSMIC REIONIZATION

    SciTech Connect

    Kaurov, Alexander A.; Gnedin, Nickolay Y. E-mail: gnedin@fnal.gov

    2013-07-01

    We extend the existing analytical model of reionization by Furlanetto et al. to include the biasing of reionization sources and additional absorption by Lyman limit systems. Both effects enhance the original model in non-trivial ways, but do not change its qualitative features. Our model is, by construction, consistent with the observed evolution of the galaxy luminosity function at z {approx}< 8 and with the observed evolution of Ly{alpha} forest at z {approx}< 6. We find that the same model can match the Wilkinson Microwave Anisotropy Probe/Planck constraint on the Thompson optical depth and the South Pole Telescope and EDGES constraints on the duration of reionization for values of the relative escape fraction that are consistent with the observational measurements at lower redshifts. However, such a match is only possible if dwarf galaxies contribute substantially to the ionizing photon budget. The latter condition is inconsistent with simulations and observational upper limits on the escape fraction from dwarfs at z {approx} 3. Whether such a disagreement is due to the different nature of z > 6 galaxies, the inadequacy of simulations and/or some of the observational constraints, or indicates an additional source of ionizing radiation at z > 8 remains to be seen.

  1. Central powering of the largest Lyman-α nebula is revealed by polarized radiation.

    PubMed

    Hayes, Matthew; Scarlata, Claudia; Siana, Brian

    2011-08-18

    High-redshift Lyman-α (Lyα) blobs are extended, luminous but rare structures that seem to be associated with the highest peaks in the matter density of the Universe. Their energy output and morphology are similar to those of powerful radio galaxies, but the source of the luminosity is unclear. Some blobs are associated with ultraviolet or infrared bright galaxies, suggesting an extreme starburst event or accretion onto a central black hole. Another possibility is gas that is shock-excited by supernovae. But not all blobs are associated with galaxies, and these ones may instead be heated by gas falling into a dark-matter halo. The polarization of the Lyα emission can in principle distinguish between these options, but a previous attempt to detect this signature returned a null detection. Here we report observations of polarized Lyα from the blob LAB1 (ref. 2). Although the central region shows no measurable polarization, the polarized fraction (P) increases to ∼20 per cent at a radius of 45 kiloparsecs, forming an almost complete polarized ring. The detection of polarized radiation is inconsistent with the in situ production of Lyα photons, and we conclude that they must have been produced in the galaxies hosted within the nebula, and re-scattered by neutral hydrogen. PMID:21850104

  2. Physical properties of local star-forming analogues to z ˜ 5 Lyman-break galaxies

    NASA Astrophysics Data System (ADS)

    Greis, Stephanie M. L.; Stanway, Elizabeth R.; Davies, Luke J. M.; Levan, Andrew J.

    2016-07-01

    Intense, compact, star-forming galaxies are rare in the local Universe but ubiquitous at high redshift. We interpret the 0.1-22 μm spectral energy distributions of a sample of 180 galaxies at 0.05 < z < 0.25 selected for extremely high surface densities of inferred star formation in the ultraviolet. By comparison with well-established stellar population synthesis models, we find that our sample comprises young (˜60-400 Myr), moderate mass (˜6 × 109 M⊙) star-forming galaxies with little dust extinction (mean stellar continuum extinction Econt(B - V) ˜ 0.1) and find star formation rates of a few tens of solar masses per year. We use our inferred masses to determine a mean specific star formation rate for this sample of ˜10-9 yr-1, and compare this to the specific star formation rates in distant Lyman-break galaxies (LBGs), and in other low-redshift populations. We conclude that our sample's characteristics overlap significantly with those of the z ˜ 5 LBG population, making ours the first local analogue population well tuned to match those high-redshift galaxies. We consider implications for the origin and evolution of early galaxies.

  3. Spatially resolved star-formation in nearby analogues of Lyman break galaxies

    NASA Astrophysics Data System (ADS)

    Appel, Sabrina; Baker, Andrew J.; Hall, Kirsten

    2016-01-01

    At redshifts of z > 1.5, UV-selected galaxy populations (such as z ~ 3 Lyman break galaxies = LBGs) have the largest number of spectroscopic redshifts. As a result, LBGs have an important role in our understanding of the history of galaxy formation. However, LBGs are rather poorly understood at longer wavelengths, and thus our understanding of the total star formation rates and (especially) gas masses in such galaxies is incomplete. A common strategy is to assume that the Kennicutt-Schmidt relation between star formation rate (SFR) surface density and gas mass surface density holds, even in these high redshift galaxies where testing the relation directly is not feasible. To help assess the validity of this assumption, we examine the Kennicutt-Schmidt relation in selected nearby (z ~ 0.2) starburst galaxies in the hope of better understanding key questions regarding star formation processes in UV-selected galaxies. Several nearby galaxies with high UV luminosities and surface brightnesses, reminiscent of those found in LBGs, were identified and used for this project. We have obtained new, spatially resolved observations of these nearby analogues in Paschen alpha emission and carbon monoxide emission, from the ESO Very Large Telescope and the IRAM Plateau de Bure Interferometer, respectively. We examine whether the galaxies follow the expected Kennicutt-Schmidt relation, and investigate any implied variation in gas depletion times between and within galaxies. This research has been supported by National Science Foundation grant AST-0955810.

  4. Water vapor content in the polar atmosphere measured by Lyman-alpha/OH fluorescence method

    NASA Technical Reports Server (NTRS)

    Iwasaka, Y.; Saitoh, S.; Ono, A.

    1985-01-01

    The water vapor of the polar stratosphere possibly plays an important role in various aeronomical processes; for example, OH radical formation through photodissociation of H2O, formation of water cluster ions, radiative energy transfer in the lower stratosphere, condensation onto particulate matter, and so on. In addition to these, it has been speculated, from the viewpoint of global transport and/or budget of water vapor, that the polar stratosphere functions as an active sink. STANFORD (1973) emphasized the existence of the stratospheric Cist cloud in the polar stratosphere which brought a large loss rate of stratospheric water vapor through a so-called freeze-out of cloud particles from the stratosphere into the troposphere. However, these geophysically interesting problems unfortunately remain to be solved, owing to the lack of measurements on water vapor distribution and its temporal variation in the polar stratosphere. The water vapor content measured at Syowa Station (69.00 deg S, 39.35 deg E), Antarctica using a balloon-borne hygrometer (Lyman - alpha/OH fluorescence type) is discussed.

  5. Limits on Lyman Continuum Escape from z = 2.2 Hα-emitting Galaxies

    NASA Astrophysics Data System (ADS)

    Sandberg, A.; Östlin, G.; Melinder, J.; Bik, A.; Guaita, L.

    2015-11-01

    The leakage of Lyman continuum (LyC) photons from star-forming galaxies is an elusive parameter. When observed, it provides a wealth of information on star formation in galaxies and on the geometry of the interstellar medium, and puts constraints on the role of star-forming galaxies in the reionization of the universe. Hα-selected galaxies at z∼ 2 trace the highest star formation population at the peak of cosmic star formation history, providing a base for directly measuring LyC escape. Here we present this method and highlight its benefits as well as caveats. We also use the method on 10 Hα emitters in the Chandra Deep Field South at z=2.2, also imaged with the Hubble Space Telescope in the ultraviolet. We find no individual LyC detections, and our stack puts a 5σ upper limit on the average absolute escape fraction of <24%, consistent with similar studies. With future planned observations, the sample sizes should rapidly increase and the method presented here should provide very robust constraints on the escape fraction.

  6. The Moon's Permanently Shadowed Regions as Observed by LRO's Lyman Alpha Mapping Project (LAMP) Instrument

    NASA Astrophysics Data System (ADS)

    Gladstone, R.; Retherford, K. D.; Stern, S. A.; Egan, A.; Miles, P. F.; Versteeg, M.; Slater, D.; Davis, M. W.; Parker, J.; Kaufmann, D.; Greathouse, T. K.; Steffl, A. J.; Mukherjee, J.; Horvath, D.; Rojas, P.; Feldman, P. D.; Hurley, D. M.; Pryor, W. R.; Hendrix, A. R.

    2011-12-01

    Although of great interest for science and resource utilization, the Moon's permanently shadowed regions (PSRs) near each pole present difficult targets for remote sensing. The Lyman Alpha Mapping Project (LAMP) instrument on the Lunar Reconnaissance Orbiter (LRO) mission is able to map PSRs at far-ultraviolet (FUV) wavelengths using two faint sources of illumination from the night sky: the all-sky Lyα glow produced as interplanetary medium (IPM) H atoms scatter the Sun's Lyα emissions, and the much fainter source from UV-bright stars. Since the reflected light from these two sources produces only a few hundred events per second in the photon-counting LAMP instrument, building maps with useful signal-to-noise (SNR) ratios requires the careful accumulation of the observations from thousands of individual LRO orbits. In this talk we present the latest FUV albedo maps obtained by LAMP of the Moon's southern and northern polar regions. The results show that 1) most PSR regions are darker at all FUV wavelengths, consistent with their surface soils having much larger porosities than non-PSR regions (e.g., P~0.9 or so), and 2) most PSRs are somewhat "redder" (i.e., more reflective at the longer FUV wavelengths) than non-PSR regions, consistent with the presence of ~1-2% water frost at the surface.

  7. SPECTROSCOPIC CONFIRMATION OF FAINT LYMAN BREAK GALAXIES NEAR REDSHIFT FIVE IN THE HUBBLE ULTRA DEEP FIELD

    SciTech Connect

    Rhoads, James E.; Malhotra, Sangeeta; Cohen, Seth; Grogin, Norman; Hathi, Nimish; Ryan, Russell; Straughn, Amber; Windhorst, Rogier A. Pirzkal, Norbert; Xu Chun; Koekemoer, Anton; Panagia, Nino; Dickinson, Mark; Ferreras, Ignacio; Gronwall, Caryl; Kuemmel, Martin; Walsh, Jeremy; Meurer, Gerhardt; Pasquali, Anna; Yan, H.-J.

    2009-05-20

    We present the faintest spectroscopically confirmed sample of z {approx} 5 Lyman break galaxies (LBGs) to date. The sample is based on slitless grism spectra of the Hubble Ultra Deep Field region from the Grism ACS Program for Extragalactic Science (GRAPES) and Probing Evolution and Reionization Spectroscopically (PEARS) projects, using the G800L grism on the Hubble Space Telescope Advanced Camera for Surveys. We report here confirmations of 39 galaxies, preselected as candidate LBGs using photometric selection criteria. We compare a 'traditional' V-dropout selection, based on the work of Giavalisco et al., to a more liberal one (with V - i > 0.9), and find that the traditional criteria are about 64% complete and 81% reliable. We also study the Ly{alpha} emission properties of our sample. We find that Ly{alpha} emission is detected in {approx}1/4 of the sample, and that the liberal V-dropout color selection includes {approx}55% of previously published line-selected Ly{alpha} sources. Finally, we examine our stacked two-dimensional spectra. We demonstrate that strong, spatially extended ({approx}1'') Ly{alpha} emission is not a generic property of these LBGs, but that a modest extension of the Ly{alpha} photosphere (compared to the starlight) may be present in those galaxies with prominent Ly{alpha} emission.

  8. THE NATURE OF DAMPED LYMAN-α AND Mg II ABSORBERS EXPLORED THROUGH THEIR DUST CONTENTS

    SciTech Connect

    Fukugita, Masataka; Ménard, Brice

    2015-02-01

    We estimate the abundance of dust in damped Lyman-α absorbers (DLAs) by statistically measuring the excess reddening they induce on their background quasars. We detect systematic reddening behind DLAs consistent with the SMC-type reddening curve and inconsistent with the Milky Way type. We find that the derived dust-to-gas ratio is, on average, inversely proportional to the column density of neutral hydrogen, implying that the amount of dust is constant, regardless of the column density of hydrogen. It means that the average metallicity is inversely proportional to the column density of hydrogen, unless the average dust-to-metal ratio varies with the hydrogen column density. This indicates that the prime origin of metals seen in DLAs is not by in situ star formation, with which Z∼N{sub H} {sub I}{sup +0.4} is expected from the empirical star formation law, contrary to our observation. We interpret the metals observed in absorbers to be deposited dominantly from nearby galaxies by galactic winds ubiquitous in intergalactic space. When extrapolating the relation between dust-to-gas ratio and H I column density to lower column density, we find a value that is consistent with what is observed for Mg II absorbers.

  9. On the Lyman continuum escape fraction of galaxies at z~2-3

    NASA Astrophysics Data System (ADS)

    Vasei, Kaveh

    2016-06-01

    Escaping Lyman-continuum (LyC) radiation from star-forming galaxies is likely responsible for the reionization of the Universe, yet direct detection of LyC has proven to be exceptionally challenging. Despite numerous efforts only a few galaxies have yet been confirmed as LyC leakers, leading people to use indirect methods to infer the escape fraction. Using a 10-orbit WFC3/UVIS F275W filter image of the Cosmic Horseshoe (a lensed galaxy at z=2.4), we show that these indirect determinations should be interpreted only as upper-limits on the escape fraction. We will also present Hubble measurements of the LyC escape fraction of more than 30 galaxies at z~3.1 in the SSA22 field, including 11 candidate emitters from deep Keck imaging. These data include the deepest near-UV images with Hubble and will probe escape fractions of 5-10% (at 3 sigma). Finally, we will conclude with implications for galaxy contributions to the ionizing background and Reionization.

  10. Non-parametric 3D map of the intergalactic medium using the Lyman-alpha forest

    NASA Astrophysics Data System (ADS)

    Cisewski, Jessi; Croft, Rupert A. C.; Freeman, Peter E.; Genovese, Christopher R.; Khandai, Nishikanta; Ozbek, Melih; Wasserman, Larry

    2014-05-01

    Visualizing the high-redshift Universe is difficult due to the dearth of available data; however, the Lyman-alpha forest provides a means to map the intergalactic medium at redshifts not accessible to large galaxy surveys. Large-scale structure surveys, such as the Baryon Oscillation Spectroscopic Survey (BOSS), have collected quasar (QSO) spectra that enable the reconstruction of H I density fluctuations. The data fall on a collection of lines defined by the lines of sight (LOS) of the QSO, and a major issue with producing a 3D reconstruction is determining how to model the regions between the LOS. We present a method that produces a 3D map of this relatively uncharted portion of the Universe by employing local polynomial smoothing, a non-parametric methodology. The performance of the method is analysed on simulated data that mimics the varying number of LOS expected in real data, and then is applied to a sample region selected from BOSS. Evaluation of the reconstruction is assessed by considering various features of the predicted 3D maps including visual comparison of slices, probability density functions (PDFs), counts of local minima and maxima, and standardized correlation functions. This 3D reconstruction allows for an initial investigation of the topology of this portion of the Universe using persistent homology.

  11. Eight per cent leakage of Lyman continuum photons from a compact, star-forming dwarf galaxy.

    PubMed

    Izotov, Y I; Orlitová, I; Schaerer, D; Thuan, T X; Verhamme, A; Guseva, N G; Worseck, G

    2016-01-14

    One of the key questions in observational cosmology is the identification of the sources responsible for ionization of the Universe after the cosmic 'Dark Ages', when the baryonic matter was neutral. The currently identified distant galaxies are insufficient to fully reionize the Universe by redshift z ≈ 6 (refs 1-3), but low-mass, star-forming galaxies are thought to be responsible for the bulk of the ionizing radiation. As direct observations at high redshift are difficult for a variety of reasons, one solution is to identify local proxies of this galaxy population. Starburst galaxies at low redshifts, however, generally are opaque to Lyman continuum photons. Small escape fractions of about 1 to 3 per cent, insufficient to ionize much surrounding gas, have been detected only in three low-redshift galaxies. Here we report far-ultraviolet observations of the nearby low-mass star-forming galaxy J0925+1403. The galaxy is leaking ionizing radiation with an escape fraction of about 8 per cent. The total number of photons emitted during the starburst phase is sufficient to ionize intergalactic medium material that is about 40 times as massive as the stellar mass of the galaxy. PMID:26762455

  12. Pollen dispersal by catapult: Experiments of Lyman J. Briggs on the flower of mountain laurel

    USGS Publications Warehouse

    Nimmo, John R.; Hermann, Paula M.; Kirkham, M.B.; Landa, Edward R.

    2014-01-01

    The flower of Kalmia latifolia L. employs a catapult mechanism that flings its pollen to considerable distances. Physicist Lyman J. Briggs investigated this phenomenon in the 1950s after retiring as longtime director of the National Bureau of Standards, attempting to explain how hydromechanical effects inside the flower’s stamen could make it possible. Briggs’s unfinished manuscript implies that liquid under negative pressure generates stress, which, superimposed on the stress generated from the flower’s growth habit, results in force adequate to propel the pollen as observed. With new data and biophysical understanding to supplement Briggs’s experimental results and research notes, we show that his postulated negative-pressure mechanism did not play the exclusive and crucial role that he credited to it, though his revisited investigation sheds light on various related processes. Important issues concerning the development and reproductive function of Kalmia flowers remain unresolved, highlighting the need for further biophysical advances.

  13. Non-LTE effects on the strength of the Lyman edge in quasar accretion disks

    NASA Technical Reports Server (NTRS)

    Stoerzer, H.; Hauschildt, P. H.; Allard, F.

    1994-01-01

    We have calculated UV/EUV (300 A which is less than or equal to lambda which is less than or equal to 1500 A) continuous energy distributions of accretion disks in the centers of active galactic nuclei (AGNs) for disk luminosities in the range 0.1 L(sub Edd) less than or equal to L(sub acc) less than 1.0 L(sub Edd) and central masses ranging from 10(exp 8) solar mass to 10(exp 9) solar mass. The vertical gas pressure structure of the disk and the disk height are obtained analytically; the temperature stratification and the resulting continuum radiation fields are calculated numerically. We have included non-Local Thermodynamic Equilibrium (LTE) effects of both the ionization equilibrium and the level populations of hydrogen and helium. We show that these non-LTE effects reduce the strength of the Lyman edge when comapred to the LTE case. In non-LTE we find that the edge can be weakly in emission or absorption for disks seen face-on, depending on the disk parameters.

  14. Remote diagnostic of the hydrogen wall through measurements of the backscattered solar Lyman alpha radiation by Voyager 1/UVS in 1993-2003

    NASA Astrophysics Data System (ADS)

    Katushkina, O. A.; Quémerais, E.; Izmodenov, V. V.; Alexashov, D. B.; Sandel, B. R.

    2016-01-01

    We perform a new analysis of the Lyman alpha data obtained by Voyager 1 during the spatial scans in 1993-2003 while Voyager 1 was at 53-88 AU from the Sun. These data are the important source of information on the hydrogen distribution in the outer heliosphere. A sophisticated global kinetic-MHD model of the heliospheric interface and a radiative transfer model are used for the analysis. It is shown for the first time that the ratio of the Lyman alpha intensities detected in the downwind and upwind lines of sight in the outer heliosphere is sensitive to the configuration (peak value and location) of the hydrogen wall. The hydrogen wall is a source of Doppler-shifted backscattered Lyman alpha photons, so it can be seen from inside the heliosphere. Therefore, Voyager 1/ultraviolet spectrometer (UVS) Lyman alpha data can be used for remote sensing of the hydrogen wall. We show that our current global model of the outer heliosphere, which is consistent with many other measurements including Lyman alpha data from both Voyager 1 and 2 in 1980-1993, provides a systematically larger downwind to upwind intensity ratio compared with the UVS data in 1993-2003. In order to decrease the ratio, a higher and/or closer hydrogen wall is needed.

  15. The ionizing photon production efficiency of compact z ~ 0.3 Lyman continuum leakers and comparison with high-redshift galaxies

    NASA Astrophysics Data System (ADS)

    Schaerer, D.; Izotov, Y. I.; Verhamme, A.; Orlitová, I.; Thuan, T. X.; Worseck, G.; Guseva, N. G.

    2016-06-01

    We have recently discovered five Lyman continuum leaking galaxies at z ~ 0.3 that were selected for their compactness, intense star formation, and high [O iii]λ5007/[O ii] λ3727 ratio. Here we derive their ionizing photon production efficiency, ξion, a fundamental quantity for inferring the number of photons available to reionize the Universe. This is the first time this is done for galaxies with confirmed strong Lyman continuum escape (fesc ~ 6-13%). We find an ionizing photon production per unit UV luminosity, ξion, that is higher by a factor 2-6 than the canonical value when reported to their observed UV luminosity. After correction for extinction, this value is close to the canonical value. The properties of our five Lyman continuum leakers are found to be very similar to those of the previously reported confirmed z = 3.218 leaker Ion2 and very similar to those of typical star-forming galaxies at z ≳ 6. Our results suggest that UV bright galaxies at high-z such as Lyman-break galaxies can be Lyman continuum leakers and that their contribution to cosmic reionization may be underestimated.

  16. Validation of the Harvard Lyman-α in situ water vapor instrument: Implications for the mechanisms that control stratospheric water vapor

    NASA Astrophysics Data System (ADS)

    Weinstock, E. M.; Smith, J. B.; Sayres, D. S.; Pittman, J. V.; Spackman, J. R.; Hintsa, E. J.; Hanisco, T. F.; Moyer, E. J.; St. Clair, J. M.; Sargent, M. R.; Anderson, J. G.

    2009-12-01

    Building on previously published details of the laboratory calibrations of the Harvard Lyman-α photofragment fluorescence hygrometer (HWV) on the NASA ER-2 and WB-57 aircraft, we describe here the validation process for HWV, which includes laboratory calibrations and intercomparisons with other Harvard water vapor instruments at water vapor mixing ratios from 0 to 10 ppmv, followed by in-flight intercomparisons with the same Harvard hygrometers. The observed agreement exhibited in the laboratory and during intercomparisons helps corroborate the accuracy of HWV. In light of the validated accuracy of HWV, we present and evaluate a series of intercomparisons with satellite and balloon borne water vapor instruments made from the upper troposphere to the lower stratosphere in the tropics and midlatitudes. Whether on the NASA ER-2 or WB-57 aircraft, HWV has consistently measured about 1-1.5 ppmv higher than the balloon-borne NOAA/ESRL/GMD frost point hygrometer (CMDL), the NOAA Cryogenic Frost point Hygrometer (CFH), and the Microwave Limb Sounder (MLS) on the Aura satellite in regions of the atmosphere where water vapor is <10 ppmv. Comparisons in the tropics with the Halogen Occultation Experiment (HALOE) on the Upper Atmosphere Research Satellite show large variable differences near the tropopause that converge to ˜10% above 460 K, with HWV higher. Results we show from the Aqua Validation and Intercomparison Experiment (AquaVIT) at the AIDA chamber in Karlsruhe do not reflect the observed in-flight differences. We illustrate that the interpretation of the results of comparisons between modeled and measured representations of the seasonal cycle of water entering the lower tropical stratosphere is dictated by which data set is used.

  17. Generation of geographical profile

    NASA Astrophysics Data System (ADS)

    Shen, Zhi-Bin; Zhang, Yuan-Biao; Liang, Kai-Fa; Lu, Zhen-Xing

    2010-08-01

    To provide help for the police's investigation on serial criminals, we develop a mathematical model in the paper. First, we use Inherently Continuous Model and Improved Kinetic Model to generate the offender's geographical profile. However, there is a difference in two models' results. For better synthesizing the difference, we develop a Combination Model and generate a new geographical profile. As a result, we estimate the offender's location and carry on a series of analysis. What's more, the models created can be applied in other fields, such as market's investigation, military operations and so on.

  18. Polarization measurements of the Lyman-(alpha)1 x-ray emission lines of hydrogenlike Ar17+ and Fe25+ at high electron impact energies

    SciTech Connect

    Robbins, D L; Beiersdorfer, P; Faenov, A Y; Pikuz, T A; Thorn, D B; Chen, H; Reed, K J; Smith, A J; Brown, G V; Kelley, R L; Kilbouren, C A; Porter, F S

    2006-01-29

    We have measured the polarization of the 2p{sub 3/2} {yields} 1s{sub 1/2} Lyman-{alpha}{sub 1} x-ray line of hydrogenlike Ar{sup 17+} and Fe{sup 25+} at electron impact energies ranging from 7 to 25 threshold units. The highly charged argon and iron ions were produced using the Lawrence Livermore National Laboratory SuperEBIT electron beam ion trap. A combination of two crystal spectrometers and a microcalorimeter were used to record the Lyman-{alpha} x-ray emission of Ar{sup 17+} and Fe{sup 25+} and to infer the polarization of the Lyman-{alpha}{sub 1} line. Our results show a systematic discrepancy with the predictions of distorted-wave calculations.

  19. [O III] Emission and Gas Kinematics in a Lyman-alpha Blob at z ~ 3.1

    NASA Astrophysics Data System (ADS)

    McLinden, Emily M.; Malhotra, Sangeeta; Rhoads, James E.; Hibon, Pascale; Weijmans, Anne-Marie; Tilvi, Vithal

    2013-04-01

    We present spectroscopic measurements of the [O III] emission line from two subregions of strong Lyα emission in a radio-quiet Lyman-alpha blob (LAB). The blob under study is LAB1 at z ~ 3.1, and the [O III] detections are from the two Lyman break galaxies (LBGs) embedded in the blob halo. The [O III] measurements were made with LUCIFER on the 8.4 m Large Binocular Telescope and NIRSPEC on 10 m Keck Telescope. Comparing the redshift of the [O III] measurements to Lyα redshifts from SAURON allows us to take a step toward understanding the kinematics of the gas in the blob. Using both LUCIFER and NIRSPEC we find velocity offsets between the [O III] and Lyα redshifts that are modestly negative or consistent with 0 km s-1 in both subregions studied (ranging from -72 ± 42- + 6 ± 33 km s-1). A negative offset means Lyα is blueshifted with respect to [O III] a positive offset then implies Lyα is redshifted with respect to [O III]. These results may imply that outflows are not primarily responsible for Lyman alpha escape in this LAB, since outflows are generally expected to produce a positive velocity offset. In addition, we present an [O III] line flux upper limit on a third region of LAB1, a region that is unassociated with any underlying galaxy. We find that the [O III] upper limit from the galaxy-unassociated region of the blob is at least 1.4-2.5 times fainter than the [O III] flux from one of the LBG-associated regions and has an [O III] to Lyα ratio measured at least 1.9-3.4 times smaller than the same ratio measured from one of the LBGs.

  20. Performance characterization of UV science cameras developed for the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP)

    NASA Astrophysics Data System (ADS)

    Champey, P.; Kobayashi, K.; Winebarger, A.; Cirtain, J.; Hyde, D.; Robertson, B.; Beabout, D.; Beabout, B.; Stewart, M.

    2014-07-01

    The NASA Marshall Space Flight Center (MSFC) has developed a science camera suitable for sub-orbital missions for observations in the UV, EUV and soft X-ray. Six cameras will be built and tested for flight with the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP), a joint National Astronomical Observatory of Japan (NAOJ) and MSFC sounding rocket mission. The goal of the CLASP mission is to observe the scattering polarization in Lyman-α and to detect the Hanle effect in the line core. Due to the nature of Lyman-α polarizationin the chromosphere, strict measurement sensitivity requirements are imposed on the CLASP polarimeter and spectrograph systems; science requirements for polarization measurements of Q/I and U/I are 0.1% in the line core. CLASP is a dual-beam spectro-polarimeter, which uses a continuously rotating waveplate as a polarization modulator, while the waveplate motor driver outputs trigger pulses to synchronize the exposures. The CCDs are operated in frame-transfer mode; the trigger pulse initiates the frame transfer, effectively ending the ongoing exposure and starting the next. The strict requirement of 0.1% polarization accuracy is met by using frame-transfer cameras to maximize the duty cycle in order to minimize photon noise. The CLASP cameras were designed to operate with ≤ 10 e-/pixel/second dark current, ≤ 25 e- read noise, a gain of 2.0 +- 0.5 and ≤ 1.0% residual non-linearity. We present the results of the performance characterization study performed on the CLASP prototype camera; dark current, read noise, camera gain and residual non-linearity.

  1. [O III] EMISSION AND GAS KINEMATICS IN A LYMAN-ALPHA BLOB AT z {approx} 3.1

    SciTech Connect

    McLinden, Emily M.; Malhotra, Sangeeta; Rhoads, James E.; Hibon, Pascale; Weijmans, Anne-Marie; Tilvi, Vithal

    2013-04-10

    We present spectroscopic measurements of the [O III] emission line from two subregions of strong Ly{alpha} emission in a radio-quiet Lyman-alpha blob (LAB). The blob under study is LAB1 at z {approx} 3.1, and the [O III] detections are from the two Lyman break galaxies (LBGs) embedded in the blob halo. The [O III] measurements were made with LUCIFER on the 8.4 m Large Binocular Telescope and NIRSPEC on 10 m Keck Telescope. Comparing the redshift of the [O III] measurements to Ly{alpha} redshifts from SAURON allows us to take a step toward understanding the kinematics of the gas in the blob. Using both LUCIFER and NIRSPEC we find velocity offsets between the [O III] and Ly{alpha} redshifts that are modestly negative or consistent with 0 km s{sup -1} in both subregions studied (ranging from -72 {+-} 42- + 6 {+-} 33 km s{sup -1}). A negative offset means Ly{alpha} is blueshifted with respect to [O III] a positive offset then implies Ly{alpha} is redshifted with respect to [O III]. These results may imply that outflows are not primarily responsible for Lyman alpha escape in this LAB, since outflows are generally expected to produce a positive velocity offset. In addition, we present an [O III] line flux upper limit on a third region of LAB1, a region that is unassociated with any underlying galaxy. We find that the [O III] upper limit from the galaxy-unassociated region of the blob is at least 1.4-2.5 times fainter than the [O III] flux from one of the LBG-associated regions and has an [O III] to Ly{alpha} ratio measured at least 1.9-3.4 times smaller than the same ratio measured from one of the LBGs.

  2. Neutrino Masses, Cosmological Parameters and Dark Energy from the Transmitted Flux in the Lyman-alpha Forest

    NASA Astrophysics Data System (ADS)

    Rossi, Graziano; Palanque-Delabrouille, N.; Yeche, C.; Borde, A.; Rich, J.; Viel, M.; Lesgourgues, J.

    2013-01-01

    The signature left in quasar spectra by the presence of neutral hydrogen in the Universe allows one to constrain the sum of the neutrino masses with unprecedented sensitivity, with respect to laboratory experiments. At the forefront of elementary particle physics and cosmology, this may also shed a new light on the neutrino mass hierarchy, and on the absolute mass scale of neutrinos. In addition, constrains on cosmological parameters and on the dark energy equation of state can be derived, from a joint parameter estimation. This however requires a detailed modeling of the line-of-sight power spectrum of the transmitted flux in the Lyman-alpha forest on scales ranging from a few to hundreds of Mpcs, which in turns demands for the inclusion and careful treatment of cosmological neutrinos. In particular, since massive neutrinos are known to significantly alter structure formation, one needs to quantify their free-streaming effect consistently. We develop here a new hydrodynamical code which incorporates cold dark matter, gas, and is also able to reproduce the impact of massive neutrinos on the one-dimensional power spectrum with a novel technique. In synergy with corresponding experimental work from state-of-the-art surveys such as BOSS, and with upcoming or future large-scale-structure probes (e.g. Planck, Euclid), this will allow one to constrain the sum of the neutrino massses and the main cosmological parameters with unprecedented statistical significance. The theoretical study presented here will be combined with topological techniques to investigate dark energy and the expansion history of the Universe directly from the Lyman-alpha transmitted flux. The method will be also relevant for BigBOSS, which is expected to produce Lyman-alpha forest data along ~600,000 distant QSOs, and the data will be used to study the line-of-sight one-dimensional fluctuations.

  3. Lyman alpha emitting galaxies at high redshift: Direct detection of young galaxies in a young universe

    NASA Astrophysics Data System (ADS)

    Dawson, Steven Arthur

    /DEIMOS follow-up observations to candidates selected in the Large Area Lyman Alpha (LALA) survey. We conclude that if there is evolution in the Lya luminosity function over these epochs, its significance is below the statistical uncertainty of these data. This result supports the conclusion from several smaller samples of high-redshift Lya---emitters that the intergalactic medium remains largely reionized from the local universe out to z [approximate] 6.5. However, it is somewhat at odds with the pronounced drop in the cosmic star formation rate density recently measured between z ~ 3 and z ~ 6 in Lyman-break galaxies, and therefore potentially sheds light on the relationship between the two populations. (Abstract shortened by UMI.)

  4. VizieR Online Data Catalog: Extremely strong damped Lyman-α systems (Noterdaeme+, 2014)

    NASA Astrophysics Data System (ADS)

    Noterdaeme, P.; Petitjean, P.; Paris, I.; Cai, Z.; Finley, H.; Ge, J.; Pieri, M. M.; York, D. G.

    2014-07-01

    We present a study of ~100 high redshift (z ~2-4) extremely strong damped Lyman-α systems (ESDLA, with N(HI)>=0.5x1022cm-2) detected in quasar spectra from the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey (SDSS-III) Data Release 11. We study the neutral hydrogen, metal, and dust content of this elusive population of absorbers and confirm our previous finding that the high column density end of the N(HI) frequency distribution has a relatively shallow slope with power-law index -3.6, similar to what is seen from 21-cm maps in nearby galaxies. The stacked absorption spectrum indicates a typical metallicity ~1/20th solar, similar to the mean metallicity of the overall DLA population. The relatively small velocity extent of the low-ionisation lines suggests that ESDLAs do not arise from large-scale flows of neutral gas. The high column densities involved are in turn more similar to what is seen in DLAs associated with gamma-ray burst afterglows (GRB-DLAs), which are known to occur close to star-forming regions. This indicates that ESDLAs arise from a line of sight passing at very small impact parameters from the host galaxy, as observed in nearby galaxies. This is also supported by simple theoretical considerations and recent high-z hydrodynamical simulations. We strongly substantiate this picture by the first statistical detection of Lyα emission with =~(0.6+/-0.2)x1042erg/s in the core of ESDLAs (corresponding to about 0.1L* at z~2-3), obtained through stacking the fibre spectra (of radius 1" corresponding to ~8kpc at z~2.5). Statistical errors on the Lyα luminosity are of the order of 0.1x1042erg/s but we caution that the measured Lyα luminosity may be overestimated by ~35% due to sky light residuals and/or FUV emission from the quasar host and that we have neglected flux-calibration uncertainties. We estimate a more conservative uncertainty of 0.2x1042erg/s. The properties of the Lyα line (luminosity distribution

  5. NARROWBAND IMAGING OF ESCAPING LYMAN-CONTINUUM EMISSION IN THE SSA22 FIELD

    SciTech Connect

    Nestor, Daniel B.; Shapley, Alice E.; Steidel, Charles C.; Siana, Brian

    2011-07-20

    We present the results of an ultradeep, narrowband imaging survey for Lyman-continuum (LyC) emission at z {approx} 3 in the SSA22a field. We employ a custom narrowband filter centered at {lambda} = 3640 A (NB3640), which probes the LyC region for galaxies at z {>=} 3.06. We also analyze new and archival NB4980 imaging tuned to the wavelength of the Ly{alpha} emission line at z = 3.09, and archival broadband B, V, and R images of the non-ionizing UV continuum. Our NB3640 images contain 26 z {>=} 3.06 Lyman break galaxies (LBGs) as well as a set of 130 Ly{alpha} emitters (LAEs), identified by their excess NB4980 flux relative to the BV continuum. Six LBGs and 28 LAEs are detected in the NB3640 image. LBGs appear to span a range of NB3640-R colors, while LAEs appear bimodal in their NB3640-R properties. We estimate average UV-to-LyC flux density ratios, corrected for foreground contamination and intergalactic medium absorption, finding (F{sub UV}/F{sub LyC}){sup LBG}{sub corr} = 11.3{sup +10.3}{sub -5.4}, which implies an LBG LyC escape fraction f{sup LyC}{sub esc} {approx} 0.1, and (F{sub UV}/F{sub LyC}){sup LAE}{sub corr} = 2.2{sup +0.9}{sub -0.6}. The strikingly blue LAE flux density ratios defy interpretation in terms of standard stellar population models. Assuming (F{sub UV}/F{sub LyC}){sup LBG}{sub corr} applies down to L = 0.1L*, we estimate a galaxy contribution to the intergalactic hydrogen ionization rate that is consistent with independent estimates based on the Ly{alpha} forest opacity at z {approx_equal} 3. If we assume that (F{sub UV}/F{sub LyC}){sup LAE}{sub corr} holds at the faintest luminosities, the galaxy contribution significantly exceeds that inferred from the Ly{alpha} forest. We interpret our results in terms of a model where LyC photons escape over only {approx}10%-20% of solid angle. When advantageously oriented, a galaxy will exhibit a low UV-to-LyC ratio, an effect enhanced for more compact galaxies. This model, however, does not adequately

  6. Lyman Alpha Camera for Io's SO2 atmosphere and Europa's water plumes

    NASA Astrophysics Data System (ADS)

    McEwen, Alfred S.; Sandel, Bill; Schneider, Nick

    2014-05-01

    The Student Lyman-Alpha Mapper (SLAM) was conceived for the Io Volcano Observer (IVO) mission proposal (McEwen et al., 2014) to determine the spatial and temporal variations in Io's SO2 atmosphere by recording the H Ly-α reflection over the disk (Feldman et al., 2000; Feaga et al., 2009). SO2 absorbs at H Ly-α, thereby modulating the brightness of sunlight reflected by the surface, and measures the density of the SO2 atmosphere and its variability with volcanic activity and time of day. Recently, enhancements at the Ly-α wavelength (121.57 nm) were seen near the limb of Europa and interpreted as active water plumes ~200 km high (Roth et al., 2014). We have a preliminary design for a very simple camera to image in a single bandpass at Ly-α, analogous to a simplified version of IMAGE EUV (Sandel et al. 2000). Our goal is at least 50 resolution elements across Io and/or Europa (~75 km/pixel), ~3x better than HST STIS, to be acquired at a range where the radiation noise is below 1E-4 hits/pixel/s. This goal is achieved with a Cassegrain-like telescope with a 10-cm aperture. The wavelength selection is achieved using a simple self-filtering mirror in combination with a solar-blind photocathode. A photon-counting detector based on a sealed image intensifier preserves the poisson statistics of the incoming photon flux. The intensifier window is coated with a solar-blind photocathode material (CsI). The location of each photon event is recorded by a position-sensitive anode based on crossed delay-line or wedge-and-strip technology. The sensitivity is 0.01 counts/pixel/sec/R, sufficient to estimate SO2 column abundances ranging from 1E15 to 1E17 per cm2 in a 5 min (300 sec) exposure. Sensitivity requirements to search for and image Europa plumes may be similar. Io's Ly-α brightness of ~3 kR exceeds the 0.8 kR brightness of Europa's plume reported by Roth et al. (2014), but the plume brightness is a direct measurement rather than inferring column abundance from

  7. Radiation Transport of Heliospheric Lyman-alpha from Combined Cassini and Voyager Data Sets

    NASA Technical Reports Server (NTRS)

    Pryor, W.; Gangopadhyay, P.; Sandel, B.; Forrester, T.; Quemerais, E.; Moebius, E.; Esposito, L.; Stewart, I.; McClintock, W.; Jouchoux, A.; Colwell, J.; Izmodenov, V.; Malama, Y.; Shemansky, D.; Ajello, J.; Hansen, C.; Bzowski, M.

    2008-01-01

    Heliospheric neutral hydrogen scatters solar Lyman-alpha radiation from the Sun with '27-day' intensity modulations observed near Earth due to the Sun's rotation combined with Earth's orbital motion. These modulations are increasingly damped in amplitude at larger distances from the Sun due to multiple scattering in the heliosphere, providing a diagnostic of the interplanetary neutral hydrogen density independent of instrument calibration. This paper presents Cassini data from 2003-2004 obtained downwind near Saturn at approximately 10 AU that at times show undamped '27-day' waves in good agreement with the single-scattering models of Pryor et al., 1992. Simultaneous Voyager 1 data from 2003- 2004 obtained upwind at a distance of 88.8-92.6 AU from the Sun show waves damped by a factor of -0.21. The observed degree of damping is interpreted in terms of Monte Carlo multiple-scattering calculations (e.g., Keller et al., 1981) applied to two heliospheric hydrogen two-shock density distributions (discussed in Gangopadhyay et al., 2006) calculated in the frame of the Baranov-Malama model of the solar wind interaction with the two-component (neutral hydrogen and plasma) interstellar wind (Baranov and Malama 1993, Izmodenov et al., 2001, Baranov and Izmodenov, 2006). We conclude that multiple scattering is definitely occurring in the outer heliosphere. Both models compare favorably to the data, using heliospheric neutral H densities at the termination shock of 0.085 cm(exp -3) and 0.095 cm(exp -3). This work generally agrees with earlier discussions of Voyager data in Quemerais et al., 1996 showing the importance of multiple scattering but is based on Voyager data obtained at larger distances from the Sun (with larger damping) simultaneously with Cassini data obtained closer to the Sun.

  8. Narrow-band surveys for very high redshift Lyman-α emitters

    NASA Astrophysics Data System (ADS)

    Nilsson, K. K.; Orsi, A.; Lacey, C. G.; Baugh, C. M.; Thommes, E.

    2007-11-01

    Context: Many current and future surveys aim to detect the highest redshift (z ⪆ 7) sources through their Lyman-α (Lyα) emission, using the narrow-band imaging method. However, to date the surveys have only yielded non-detections and upper limits as no survey has reached the necessary combination of depth and area to detect these very young star forming galaxies. Aims: We aim to calculate model luminosity functions and mock surveys of Lyα emitters at z ⪆ 7 based on a variety of approaches calibrated and tested on observational data at lower redshifts. Methods: We calculate model luminosity functions at different redshifts based on three different approaches: a semi-analytical model based on CDM, a simple phenomenological model, and an extrapolation of observed Schechter functions at lower redshifts. The results of the first two models are compared with observations made at redshifts z ˜ 5.7 and z ˜ 6.5, and they are then extrapolated to higher redshift. Results: We present model luminosity functions for redshifts between z = 7{-}12.5 and give specific number predictions for future planned or possible narrow-band surveys for Lyα emitters. We also investigate what constraints future observations will be able to place on the Lyα luminosity function at very high redshift. Conclusions: It should be possible to observe z = 7{-}10 Lyα emitters with present or near-future instruments if enough observing time is allocated. In particular, large area surveys such as ELVIS (Emission Line galaxies with VISTA Survey) will be useful in collecting a large sample. However, to get a large enough sample to constrain well the z ≥ 10 Lyα luminosity function, instruments further in the future, such as an ELT, will be necessary.

  9. The physical properties of z > 2 Lyman limit systems: new constraints for feedback and accretion models

    NASA Astrophysics Data System (ADS)

    Fumagalli, Michele; O'Meara, John M.; Prochaska, J. Xavier

    2016-02-01

    We study the physical properties of a homogeneous sample of 157 optically thick absorption line systems at redshifts ˜1.8-4.4, selected from a high-dispersion spectroscopic survey of Lyman limit systems (LLSs). By means of multiple ionization models and Bayesian techniques, we derive the posterior probability distribution functions for the density, metallicity, temperature and dust content of the absorbing gas. We find that z > 2 LLSs are highly ionized with ionization parameters between -3 ≲ log U ≲ -2, depending on the H I column density. LLSs are characterized by low temperatures (T < 5 × 104K) and reside in dust-poor environments. Between z ˜ 2.5-3.5, ˜80 per cent of the LLSs have physical densities between nH ˜ 10- 3.5-10- 2 cm- 3 for the assumed UV background, but we caution that a degeneracy between the ionization parameter and the intensity of the radiation field prevents robust inference on the density and sizes of LLSs. Conversely, metallicity estimates are less sensitive to the assumptions behind ionization corrections. LLSs at z > 2 are characterized by a broad unimodal distribution over > 4 orders of magnitude, with a peak at log Z/Z⊙ ˜ -2. LLSs are metal poor, significantly less enriched than DLAs, with ˜70 per cent of the metallicity PDF below log Z/Z⊙ ≤ -1.5. The median metallicity of super LLSs with log N_{H I}≥ 19 rapidly evolves with redshift, with a 10-fold increase between z ˜ 2.1-3.6 (˜1.5 Gyr). Based on this sample, we find that LLSs at z = 2.5-3.5 account for ˜15 per cent of all the metals produced by UV-selected galaxies. The implications for theories of cold gas accretion and metal ejection from galaxies are also discussed.

  10. FAR-INFRARED PROPERTIES OF LYMAN BREAK GALAXIES FROM COSMOLOGICAL SIMULATIONS

    SciTech Connect

    Cen Renyue

    2011-12-15

    Utilizing state-of-the-art adaptive mesh refinement cosmological hydrodynamic simulations with ultra-high resolution (114 h{sup -1} pc) and a large sample size ({>=}3300 galaxies of stellar mass {>=}10{sup 9} M{sub Sun }), we show how the stellar light of Lyman break galaxies at z = 2 is distributed between optical/ultraviolet (UV) and far-infrared (FIR) bands. With a single scalar parameter for dust obscuration we can simultaneously reproduce the observed UV luminosity function for the entire range (3-100 M{sub Sun} yr{sup -1}) and extant FIR luminosity function at the bright end ({>=}20 M{sub Sun} yr{sup -1}). We quantify that galaxies more massive or having higher star formation rate (SFR) tend to have larger amounts of dust obscuration mostly due to a trend in column density and in a minor part due to a mass (or SFR)-metallicity relation. It is predicted that the FIR luminosity function in the range SFR = 1-100 M{sub Sun} yr{sup -1} is a power law with a slope of about -1.7. We further predict that there is a 'galaxy desert' at SFR{sub FIR} < 0.02(SFR{sub UV}/10 M{sub Sun} yr{sup -1}){sup 2.1} M{sub Sun} yr{sup -1} in the SFR{sub UV} - SFR{sub FIR} plane. Detailed distributions of SFR{sub FIR} at a fixed SFR{sub UV} are presented. Upcoming observations by the Atacama Large Millimeter Array should test this model. If confirmed, it validates the predictions of the standard cold dark matter model and has important implications on the intrinsic SFR function of galaxies at high redshift.

  11. The non-linear power spectrum of the Lyman alpha forest

    NASA Astrophysics Data System (ADS)

    Arinyo-i-Prats, Andreu; Miralda-Escudé, Jordi; Viel, Matteo; Cen, Renyue

    2015-12-01

    The Lyman alpha forest power spectrum has been measured on large scales by the BOSS survey in SDSS-III at z~ 2.3, has been shown to agree well with linear theory predictions, and has provided the first measurement of Baryon Acoustic Oscillations at this redshift. However, the power at small scales, affected by non-linearities, has not been well examined so far. We present results from a variety of hydrodynamic simulations to predict the redshift space non-linear power spectrum of the Lyα transmission for several models, testing the dependence on resolution and box size. A new fitting formula is introduced to facilitate the comparison of our simulation results with observations and other simulations. The non-linear power spectrum has a generic shape determined by a transition scale from linear to non-linear anisotropy, and a Jeans scale below which the power drops rapidly. In addition, we predict the two linear bias factors of the Lyα forest and provide a better physical interpretation of their values and redshift evolution. The dependence of these bias factors and the non-linear power on the amplitude and slope of the primordial fluctuations power spectrum, the temperature-density relation of the intergalactic medium, and the mean Lyα transmission, as well as the redshift evolution, is investigated and discussed in detail. A preliminary comparison to the observations shows that the predicted redshift distortion parameter is in good agreement with the recent determination of Blomqvist et al., but the density bias factor is lower than observed. We make all our results publicly available in the form of tables of the non-linear power spectrum that is directly obtained from all our simulations, and parameters of our fitting formula.

  12. The clustering and halo occupation distribution of Lyman-break galaxies at z ˜ 4

    NASA Astrophysics Data System (ADS)

    Park, Jaehong; Kim, Han-Seek; Wyithe, J. Stuart B.; Lacey, C. G.; Baugh, C. M.; Barone-Nugent, R. L.; Trenti, M.; Bouwens, R. J.

    2016-09-01

    We investigate the clustering of Lyman-break galaxies (LBGs) at z ˜ 4. Using the hierarchical galaxy formation model GALFORM, we predict, for the first time using a semi-analytical model with feedback from active galactic nuclei (AGN), the angular correlation function (ACF) of LBGs and find agreement within 3σ with new measurements of the ACF from surveys including the Hubble eXtreme Deep Field (XDF) and Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) field. Our simulations confirm the conclusion reached using independent models that although the predicted ACFs reproduce the trend of increased clustering with luminosity, the dependence is less strong than observed. We find that for the detection limits of the XDF field, central LBGs at z ˜ 4 predominantly reside in haloes of mass ˜1011-1012 h-1 M⊙ and that satellites reside in larger haloes of mass ˜1012-1013 h-1 M⊙. The model predicts fewer bright satellite LBGs at z ˜ 4 than is inferred from measurements of the ACF at small scales. By analysing the halo occupation distribution (HOD) predicted by the model, we find evidence that AGN feedback affects the HOD of central LBGs in massive haloes. This is a new high-redshift test of this important feedback mechanism. We investigate the effect of photometric errors in the observations on the ACF predictions. We find that the observational uncertainty in the galaxy luminosity reduces the clustering amplitude and that this effect increases towards faint galaxies, particularly on small scales. To compare properties of model with observed LBGs, this uncertainty must be considered.

  13. Determining attenuation laws down to the Lyman break in z~0.3 galaxies

    NASA Astrophysics Data System (ADS)

    Boquien, Mederic

    2013-10-01

    Star formation is the fundamental process transforming baryonic matter in the Universe, and governing the cycling of gas in-and-out of galaxies. Tracing accurately star formation is of critical importance to discriminate between galaxy evolution models.The UV is where massive young stars emit the bulk of their energy and the wavelength of choice to track the evolution of the star formation across cosmic times. Presence of dust, however, impacts the UV emission from galaxies, by dimming and reddening it. Correcting the UV for dust attenuation is thus a crucial requirement to derive the physical parameters of galaxies. Significant variations from the widely used "starburst law" are observed from one galaxy to another, which may reflect systematic variations with stellar populations or galaxy morphology. These uncharacterized variations pose an important limitation to our ability to quantify properties of high-redshift galaxies, a regime where the starburst law is almost universally applied.In order to determine and parametrize attenuation laws in the UV down to the Lyman break we propose to perform COS FUV spectroscopy on a sample of 8 star-forming galaxies at z~0.3. While broadband data can constrain dust masses and optical depth, they cannot reliably constrain the attenuation law itself due to degeneracies between the competing effects of stellar populations and dust. The combination of COS spectra with existing broadband observations will be crucial to address this issue. This will allow us to constrain dust models and will have a broad impact on the study of galaxies from the galactic neighborhood to ultra-high redshifts.

  14. Archival Search for METAL LINES in QUASAR LYMAN-ALPHA SYSTEMS

    NASA Astrophysics Data System (ADS)

    Tytler, David

    1995-07-01

    QSO Lyman-alpha forest absorption systems have traditionally been considered intergalactic primordial gas clouds, but new data suggest that many of them at high redshift contain metals with abundances of C/H eq -3, which means 10^-3 solar. We propose to search for metals in HST spectra of LyAlpha forest systems at low redshift. The search has two parts: first we look for 2 Sigma metal lines at the expected positions of known LyAlpha lines, and we estimate the number of chance identifications. Second, we align and coadd spectra at the expected positions of the metal lines in each LyAlpha systems. We will look for the strong metal lines {C IV, O VI, N V, C III, Mg X and Ne VIII} in this composite. There are five reasons why we expect to find metals. {1} We are finding C IV in LyAlpha clouds at high z. {2} The number of C IV systems increases with decreasing redshift. {3} In general, abundances should be higher at low z. {4} We are now identifying many low redshift LyAlpha lines with the outer regions of galaxies. {5} O VI should be stronger than C IV. O VI is not easily seen at high z because of confusion in the LyAlpha forest, but it will be accessible in HST data. With 100 LyAlpha systems from the HST spectra of 167 QSOs we should reach a limit of C/H <= -2.3 for C IV, and worse for other ions. If we find metals, we begin to determine if they are more common in LyAlpha clouds which are associated with galaxies, and especially whether they occur in clouds which are intergalactic.

  15. Lyman Break Galaxies at z ~ 5: Rest-Frame UV Spectra. III.

    NASA Astrophysics Data System (ADS)

    Kajino, Hiroki; Ohta, Kouji; Iwata, Ikuru; Yabe, Kiyoto; Yuma, Suraphong; Akiyama, Masayuki; Tamura, Naoyuki; Aoki, Kentaro; Sawicki, Marcin

    2009-10-01

    We present results of optical spectroscopic observations of candidates of Lyman break galaxies (LBGs) at z ~ 5 in the region, including the GOODS-N and the J0053+1234 regions by using Gemini Multi-Object Spectrograph North and South, respectively. Among 25 candidates, five objects are identified to be at z ~ 5 (two of them were already identified by an earlier study) and one object very close to the color-selection window turned out to be a foreground galaxy. With this spectroscopically identified sample and those from previous studies, we derived the lower limits on the number density of bright (MUV < -22.0 mag) LBGs at z ~ 5. These lower limits are comparable to or slightly smaller than the number densities of UV luminosity functions (UVLFs) that show the smaller number density among z ~ 5 UVLFs in literature. However, by considering that there remain many LBG candidates without spectroscopic observations, the number density of bright LBGs is expected to increase by a factor of two or more. The evidence for the deficiency of UV luminous LBGs with large Lyα equivalent widths was reinforced. We discuss possible causes for the deficiency and prefer the interpretation of dust absorption. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the National Science Foundation on behalf of the Gemini partnership: the NSF (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência e Tecnologia (Brazil), and SECYT (Argentina).

  16. Lyman Break Galaxies at z˜5: Rest-Frame UV Spectra. II

    NASA Astrophysics Data System (ADS)

    Ando, Masataka; Ohta, Kouji; Iwata, Ikuru; Akiyama, Masayuki; Aoki, Kentaro; Tamura, Naoyuki

    2007-08-01

    We present spectroscopy results of Lyman break galaxies (LBGs) at z˜5 in the J0053+1234 field. Among five bright candidates with z'<25.0mag, two objects are confirmed to be at z˜5. The equivalent widths (EWs) of Lyα emission of the 2 LBGs are not so strong as to be detected as Lyα emitters, and one of them shows strong low-ionization interstellar (LIS) metal absorption lines. Two faint objects with z'geq25.0 mag are also confirmed to be at z˜5, and their spectra show strong Lyα emission in contrast to bright ones. These results suggest a deficiency of strong Lyα emission in bright LBGs at z ˜ 5, as discussed in our previous paper. Combined with our previous spectra of LBGs at z˜5, obtained around the Hubble Deep Field-North (HDF-N), we made a composite spectrum of luminous (M_{1400} leq 21.5mag) LBGs at z˜5. The resultant spectrum shows weak Ly α emission and strong LIS absorptions, which suggest that the bright LBGs at z˜5 have chemically evolved at least to ˜0.1 solar metallicity. For a part of our sample in the HDF-N region, we obtained near-to-mid infrared data, which constrain the stellar masses of these objects. With the stellar mass and the metallicity estimated from the LIS absorptions, the metallicities of the LBGs at z˜5 tend to be lower than those of galaxies with the same stellar mass at z lesssim 2, although the uncertainty is very large.

  17. Solar wind decrease at high heliographic latitudes detected from Prognoz interplanetary Lyman alpha mapping

    SciTech Connect

    Lallement, R.; Bertaux, J.L.; Kurt, V.G.

    1985-02-01

    New evidence for a latitudinal decrease of the solar wind mass flux is presented from observations of the interplanetary Lyman alpha emission collected in 1976 and 1977 with satellites Prognoz 5 and 6. The flow of interstellar hydrogen atoms in the solar system is ionized by EUV solar radiation and charge exchange with solar wind protons which accounts for about 80% of the total ionization rate. The resulting gradual decrease of the neutral H density from the upwind region down to the downwind region observed from Ly ..cap alpha.. intensity measurements allowed the determination of the absolute value of the total ionization rate ..beta.. for one H atom at 1 AU against ionization. Collected in 1976 and 1977 at five places in the solar system, The measurements are first compared to a model which assumes isotropy of the EUV and solar wind. Strong departures are obvious toward high-latitude regions, especially when the observer is in the downwind region where the solar wind ionization has had more time to act (cumulative effect). A model was constructed which include a decrease of the ionization rate with heliographic latitude. The adjustment of data allowed for the measurement of the absolute value of the total ionization rate and implies a 50% latitude decrease of the ionization rate due to charge exchange with the solar wind, from ..beta../sub s//sub w/ = (3.9 +- 0.5) x 10/sup -8/ s/sup -1/ at the equator to ..beta../sub s//sub w/ = (2.0 +- 0.5) x 10/sup -8/ s/sup -1/ at the pole. The corresponding absolute value of the solar wind proton flux is (2.4-3.6) x 10/sup 8/ cm/sup -2/ s/sup -1/ at the equator and twice less at the pole if a constant velocity is assumed for the solar wind.

  18. A Resolved Map of the Infrared Excess in a Lyman Break Galaxy at z = 3

    NASA Astrophysics Data System (ADS)

    Koprowski, M. P.; Coppin, K. E. K.; Geach, J. E.; Hine, N. K.; Bremer, M.; Chapman, S.; Davies, L. J. M.; Hayashino, T.; Knudsen, K. K.; Kubo, M.; Lehmer, B. D.; Matsuda, Y.; Smith, D. J. B.; van der Werf, P. P.; Violino, G.; Yamada, T.

    2016-09-01

    We have observed the dust continuum of 10 z = 3.1 Lyman break galaxies with the Atacama Large Millimeter/submillimeter Array at ∼450 mas resolution in Band 7. We detect and resolve the 870 μm emission in one of the targets with a flux density of S 870 = 192 ± 57 μJy, and measure a stacked 3σ signal of S 870 = 67 ± 23 μJy for the remaining nine. The total infrared luminosities are L 8–1000 = (8.4 ± 2.3) × 1010 L ⊙ for the detection and L 8–1000 = (2.9 ± 0.9) × 1010 L ⊙ for the stack. With Hubble Space Telescope Advanced Camera for Surveys I-band imaging we map the rest-frame UV emission on the same scale as the dust, effectively resolving the “infrared excess” (IRX = L FIR/L UV) in a normal galaxy at z = 3. Integrated over the galaxy we measure IRX = 0.56 ± 0.15, and the galaxy-averaged UV slope is β = ‑1.25 ± 0.03. This puts the galaxy a factor of ∼10 below the IRX–β relation for local starburst nuclei of Meurer et al. However, IRX varies by more than a factor of 3 across the galaxy, and we conclude that the complex relative morphology of the dust relative to UV emission is largely responsible for the scatter in the IRX–β relation at high-z. A naive application of a Meurer-like dust correction based on the UV slope would dramatically overestimate the total star formation rate, and our results support growing evidence that when integrated over the galaxy, the typical conditions in high-z star-forming galaxies are not analogous to those in the local starburst nuclei used to establish the Meurer relation.

  19. The dust content of damped Lyman α systems in the Sloan Digital Sky Survey

    NASA Astrophysics Data System (ADS)

    Murphy, Michael T.; Bernet, Martin L.

    2016-01-01

    The dust content of damped Lyman α systems (DLAs) is an important observable for understanding their origin and the neutral gas reservoirs of galaxies. While the average colour excess of DLAs, E(B - V), is known to be ≲ 15 millimagnitude (mmag), both detections and non-detections with ˜2 mmag precision have been reported. Here we find 3.2σ statistical evidence for DLA dust-reddening of 774 Sloan Digital Sky Survey (SDSS) quasars by comparing their fitted spectral slopes to those of ˜7000 control quasars. The corresponding E(B - V) is 3.0 ± 1.0 mmag, assuming a Small Magellanic Cloud (SMC) dust extinction law, and it correlates strongly (3.5σ) with the metal content, characterized by the Si II λ1526 absorption-line equivalent width, providing additional confidence that the detection is due to dust in the DLAs. Evolution of E(B - V) over the redshift range 2.1 < z < 4.0 is limited to <2.5 mmag per unit redshift (1σ), consistent with the known, mild DLA metallicity evolution. There is also no apparent relationship with neutral hydrogen column density, N_{H I}, though the data are consistent with a mean E(B-V)/N_{H I}=(3.5± 1.0)× 10^{-24} mag cm2, approximately the ratio expected from the SMC scaled to the lower metallicities typical of DLAs. We implement the SDSS selection algorithm in a portable code to assess the potential for systematic, redshift-dependent biases stemming from its magnitude and colour-selection criteria. The effect on the mean E(B - V) is negligible (<5 per cent) over the entire redshift range of interest. Given the broad potential usefulness of this implementation, we make it publicly available.

  20. Harnessing High Redshift Beacons: IRS Spectra of Lensed Lyman Break Galaxies

    NASA Astrophysics Data System (ADS)

    Siana, Brian; Coppin, Kristen; Ebeling, Harald; Edge, Alastair; Ellis, Richard; Kneib, Jean-Paul; Pettini, Max; Richard, Johan; Smail, Ian; Swinbank, Mark; Teplitz, Harry

    2007-05-01

    Star-formation at high redshift occurs in two types of galaxies: dusty Ultra-Luminous Infrared Galaxies (ULIRGs) and UV-bright Lyman Break Galaxies (LBGs). In both populations dust absorbs most of the ultraviolet (UV) light from young stars and re-emits the energy in the infrared (IR). Therefore, detailed studies of the dust and the infrared SEDs of these galaxies are critical for understanding these important evolutionary stages in galaxy formation. ULIRGs at z ~ 2-3 are luminous enough for both submm detection and Spitzer IRS spectroscopy, so much has been learned recently about their interstellar medium and IR SEDs. LBGs are too faint to be detected with submm imaging or IRS spectroscopy so little can be discovered about their dust content and IR SEDs prior to JWST and ALMA. Fortunately, there exist a few rare examples of LBGs which are strongly lensed by a foreground cluster or galaxy, and are magnified by factors of 10-30. We can therefore study in detail the infrared properties of this otherwise inaccessible population. Our group will obtain (in an approved Cycle-3 program) IRS spectroscopy of the most famous LBG, cB58, but it is clearly dangerous to draw wide-ranging conclusions about the LBG population based on this single object. We therefore propose for a detailed Spitzer study of the only other known bright lensed LBGs: the 'Cosmic Eye' and the '8-O'clock Arc'. The requested program uses IRS spectroscopy, IRS Peak-Up 16 micron, MIPS 70 micron, and IRAC imaging to fully characterize the gas and dust in the ISM of these galaxies and determine the shape of the IR SEDs. Together, the three lensed sources span the full range of star-formation rates and dust attenuation levels observed in LBGs. Therefore, we can correlate these properties with the infrared SEDs and emission-line properties (PAHs) and apply the correlations when examining the entire LBG population.

  1. The evolution of neutral gas in damped Lyman α systems from the XQ-100 survey

    NASA Astrophysics Data System (ADS)

    Sánchez-Ramírez, R.; Ellison, S. L.; Prochaska, J. X.; Berg, T. A. M.; López, S.; D'Odorico, V.; Becker, G. D.; Christensen, L.; Cupani, G.; Denney, K. D.; Pâris, I.; Worseck, G.; Gorosabel, J.

    2016-03-01

    We present a sample of 38 intervening damped Lyman α (DLA) systems identified towards 100 z > 3.5 quasars, observed during the XQ-100 survey. The XQ-100 DLA sample is combined with major DLA surveys in the literature. The final combined sample consists of 742 DLAs over a redshift range approximately 1.6 < zabs < 5.0. We develop a novel technique for computing Ω_{H I}^DLA as a continuous function of redshift, and we thoroughly assess and quantify the sources of error therein, including fitting errors and incomplete sampling of the high column density end of the column density distribution function. There is a statistically significant redshift evolution in Ω_{H I}^DLA (≥3σ) from z ˜ 2 to z ˜ 5. In order to make a complete assessment of the redshift evolution of Ω_{H I}, we combine our high-redshift DLA sample with absorption surveys at intermediate redshift and 21-cm emission line surveys of the local universe. Although Ω_{H I}^DLA, and hence its redshift evolution, remains uncertain in the intermediate-redshift regime (0.1 < zabs < 1.6), we find that the combination of high-redshift data with 21-cm surveys of the local universe all yield a statistically significant evolution in Ω_{H I} from z ˜ 0 to z ˜ 5 (≥3σ). Despite its statistical significance, the magnitude of the evolution is small: a linear regression fit between Ω_{H I} and z yields a typical slope of ˜0.17 × 10-3, corresponding to a factor of ˜4 decrease in Ω_{H I} between z = 5 and z = 0.

  2. The clustering and halo occupation distribution of Lyman-break galaxies at z ˜ 4

    NASA Astrophysics Data System (ADS)

    Park, Jaehong; Kim, Han-Seek; Wyithe, J. Stuart B.; Lacey, C. G.; Baugh, C. M.; Barone-Nugent, R. L.; Trenti, M.; Bouwens, R. J.

    2016-06-01

    We investigate the clustering of Lyman-break galaxies (LBGs) at z ˜ 4. Using the hierarchical galaxy formation model GALFORM, we predict, for the first time using a semi-analytical model with feedback from active galactic nuclei (AGN), the angular correlation function (ACF) of LBGs and find agreement within 3 σ with new measurements of the ACF from surveys including the Hubble eXtreme Deep Field (XDF) and CANDELS field. Our simulations confirm the conclusion reached using independent models that although the predicted ACFs reproduce the trend of increased clustering with luminosity, the dependence is less strong than observed. We find that for the detection limits of the XDF field central LBGs at z ˜ 4 predominantly reside in haloes of mass ˜1011 - 1012h-1M⊙ and that satellites reside in larger haloes of mass ˜1012 - 1013h-1M⊙. The model predicts fewer bright satellite LBGs at z ˜ 4 than is inferred from measurements of the ACF at small scales. By analysing the halo occupation distribution (HOD) predicted by the model, we find evidence that AGN feedback affects the HOD of central LBGs in massive haloes. This is a new high-redshift test of this important feedback mechanism. We investigate the effect of photometric errors in the observations on the ACF predictions. We find that the observational uncertainty in the galaxy luminosity reduces the clustering amplitude and that this effect increases towards faint galaxies, particularly on small scales. To compare properties of model with observed LBGs this uncertainty must be considered.

  3. Magellan LDSS3 emission confirmation of galaxies hosting metal-rich Lyman α absorption systems

    NASA Astrophysics Data System (ADS)

    Straka, Lorrie A.; Johnson, Sean; York, Donald G.; Bowen, David V.; Florian, Michael; Kulkarni, Varsha P.; Lundgren, Britt; Péroux, Celine

    2016-06-01

    Using the Low Dispersion Survey Spectrograph 3 at the Magellan II Clay Telescope, we target candidate absorption host galaxies detected in deep optical imaging (reaching limiting apparent magnitudes of 23.0-26.5 in g, r, i, and z filters) in the fields of three QSOs, each of which shows the presence of high metallicity, high N_{H I} absorption systems in their spectra (Q0826-2230: zabs = 0.9110, Q1323-0021: zabs = 0.7160, Q1436-0051: zabs = 0.7377, 0.9281). We confirm three host galaxies at redshifts 0.7387, 0.7401, and 0.9286 for two of the Lyman α absorption systems (one with two galaxies interacting). For these systems, we are able to determine the star formation rates (SFRs); impact parameters (from previous imaging detections); the velocity shift between the absorption and emission redshifts; and, for one system, also the emission metallicity. Based on previous photometry, we find these galaxies have L > L*. The [O II] SFRs for these galaxies are in the range 11-25 M⊙ yr-1 (uncorrected for dust), while the impact parameters lie in the range 35-54 kpc. Despite the fact that we have confirmed galaxies at 50 kpc from the QSO, no gradient in metallicity is indicated between the absorption metallicity along the QSO line of sight and the emission line metallicity in the galaxies. We confirm the anticorrelation between impact parameter and N_{H I} from the literature. We also report the emission redshift of five other galaxies: three at zem > zQSO, and two (L < L*) at zem < zQSO not corresponding to any known absorption systems.

  4. High-redshift star formation in a time-dependent Lyman-Werner background

    NASA Astrophysics Data System (ADS)

    Visbal, Eli; Haiman, Zoltán; Terrazas, Bryan; Bryan, Greg L.; Barkana, Rennan

    2014-11-01

    The first generation of stars produces a background of Lyman-Werner (LW) radiation which can photodissociate molecular hydrogen, increasing the mass of dark matter haloes required to host star formation. Previous studies have determined the critical mass required for efficient molecular cooling with a constant LW background. However, the true background is expected to increase rapidly at early times. Neglecting this evolution could underestimate star formation in small haloes that may have started to cool in the past when the LW intensity was much lower. Background evolution is a large source of uncertainty in pre-reionization predictions of the cosmological 21cm signal, which can be observed with future radio telescopes. To address this, we perform zero-dimensional one-zone calculations that follow the density, chemical abundances, and temperature of gas in the central regions of dark matter haloes, including hierarchical growth and an evolving LW background. We begin by studying the physics of haloes subjected to a background that increases exponentially with redshift. We find that when the intensity increases more slowly than JLW(z)∝10-z/5, cooling in the past is a relatively small effect. We then self-consistently compute the cosmological LW background over z = 15-50 and find that cooling in the past due to an evolving background has a modest impact. Finally, we compare these results to three-dimensional hydrodynamical cosmological simulations with varying LW histories. While only a small number of haloes were simulated, the results are consistent with our one-zone calculations.

  5. Production of N2 Vegard-Kaplan and Lyman-Birge-Hopfield emissions on Pluto

    NASA Astrophysics Data System (ADS)

    Jain, Sonal Kumar; Bhardwaj, Anil

    2015-01-01

    We have developed a model to calculate the emission intensities of various vibrational transitions of N2 triplet band and Lyman-Birge-Hopfield (LBH) band emissions in the dayglow of Pluto for solar minimum, moderate, and maximum conditions. The calculated overhead intensities of Vegard-Kaplan (A3Σu+ -X1 Σg+) , First Positive (B3Πg -A3 Σu+) , Second Positive (C3Πu -B3Πg) , Wu-Benesch (W3Δu -B3Πg) , Reverse First Positive, and LBH (a1Πg -X1 Σg+) bands of N2 are 17 (74), 14.8 (64), 2.4 (10.8), 2.9 (12.7), 2.9 (12.5), and 2.3 (10) R, respectively, for solar minimum (maximum) condition. We have predicted the overhead and limb intensities of VK (150-190 nm) and LBH (120-190 nm) bands of N2 on Pluto for the New Horizons (NH) flyby condition that can be observed by ALICE: the ultraviolet imaging spectrograph also know as P-ALICE. The predicted limb intensities of VK and LBH bands peak at radial distance of ∼2000 km with the value of about 5 (13) and 9.5 (22) R for solar zenith angle 60° (0°), respectively. We have also calculated overhead and limb intensities of few prominent transition of CO Fourth Positive bands for NH flyby condition.

  6. HETDEX: Probing the Chemical Evolution of the Universe with Lyman Alpha Emitting Galaxies

    NASA Astrophysics Data System (ADS)

    Finkelstein, Steven L.; Hill, G. J.; Gebhardt, K.; Blanc, G.; Drory, N.; HETDEX Collaboration

    2012-01-01

    The Hobby Eberly Telescope Dark Energy Experiment (HETDEX) will discover 0.8 million Lyman alpha emitting galaxies (LAEs) at 1.9 < z < 3.5 over 300 square degrees beginning in Fall 2012. This unprecedentedly large volume probed will allow the discovery of large samples of bright LAEs, enabling follow-up science which cannot be done for the bulk of the LAE population, as they form the faint end of the galaxy luminosity function. Combining the HETDEX sample with the new generation of multi-object near-infrared (NIR) spectrographs will allow direct measurements of LAE physical properties, which are of interest as LAEs appear similar to galaxies at very high redshifts (z > 7) , and LAEs are also the likely progenitors of present-day Milky Way-like galaxies. Here we present results from the HETDEX pilot survey, which discovered 100 LAEs with a single integral field spectrograph mounted on the McDonald Observatory 2.7m telescope. We have detected rest-frame optical emission lines from five of these galaxies with the single-slit NIR spectrograph NIRSPEC on the Keck II 10m telescope. From the ratio of the upper limit on the (undetected) [NII] flux to the observed Halpha line strength, all five LAEs appear to have low metallicities (< 50% solar). The brightest LAE in our sample lies significantly below the mass-metallicity relation for continuum-selected galaxies at the same redshift. The remaining LAEs may also lie below this relation, however their fainter Halpha fluxes result in higher limits on the [NII]/Halpha flux ratio. Thus deeper integrations, requiring multi-object spectrographs (MOS) to be feasible, are necessary. The field-of-view of the next generation of MOS NIR spectrographs will be able to simultaneously observe > 10 HETDEX LAEs to a much deeper depth, providing a significant boost in our ability to probe the chemical enrichment of this enigmatic galaxy population.

  7. Cross-correlation of the cosmic 21-cm signal and Lyman α emitters during reionization

    NASA Astrophysics Data System (ADS)

    Sobacchi, Emanuele; Mesinger, Andrei; Greig, Bradley

    2016-07-01

    Interferometry of the cosmic 21-cm signal is set to revolutionize our understanding of the Epoch of Reionization (EoR), eventually providing 3D maps of the early Universe. Initial detections however will be low signal to noise, limited by systematics. To confirm a putative 21-cm detection, and check the accuracy of 21-cm data analysis pipelines, it would be very useful to cross-correlate against a genuine cosmological signal. The most promising cosmological signals are wide-field maps of Lyman α emitting galaxies (LAEs), expected from the Subaru Hyper-Suprime Cam ultradeep field (UDF). Here we present estimates of the correlation between LAE maps at z ˜ 7 and the 21-cm signal observed by both the Low Frequency Array (LOFAR) and the planned Square Kilometre Array Phase 1 (SKA1). We adopt a systematic approach, varying both: (i) the prescription of assigning LAEs to host haloes; and (ii) the large-scale structure of neutral and ionized regions (i.e. EoR morphology). We find that the LAE-21cm cross-correlation is insensitive to (i), thus making it a robust probe of the EoR. A 1000 h observation with LOFAR would be sufficient to discriminate at ≳ 1σ a fully ionized Universe from one with a mean neutral fraction of bar{x}_{H I}≈ 0.50, using the LAE-21 cm cross-correlation function on scales of R ≈ 3-10 Mpc. Unlike LOFAR, whose detection of the LAE-21 cm cross-correlation is limited by noise, SKA1 is mostly limited by ignorance of the EoR morphology. However, the planned 100 h wide-field SKA1-Low survey will be sufficient to discriminate an ionized Universe from one with bar{x}_{H I}=0.25, even with maximally pessimistic assumptions.

  8. Unification and Infinite Series

    ERIC Educational Resources Information Center

    Leyendekkers, J. V.; Shannon, A. G.

    2008-01-01

    Some infinite series are analysed on the basis of the hypergeometric function and integer structure and modular rings. The resulting generalized functions are compared with differentiation of the "mother" series. (Contains 1 table.)

  9. Lenses in the forest: cross correlation of the Lyman-alpha flux with cosmic microwave background lensing.

    PubMed

    Vallinotto, Alberto; Das, Sudeep; Spergel, David N; Viel, Matteo

    2009-08-28

    We present a theoretical estimate for a new observable: the cross correlation between the Lyman-alpha flux fluctuations in quasar spectra and the convergence of the cosmic microwave background as measured along the same line of sight. As a first step toward the assessment of its detectability, we estimate the signal-to-noise ratio using linear theory. Although the signal-to-noise is small for a single line of sight and peaks at somewhat smaller redshifts than those probed by the Lyman-alpha forest, we estimate a total signal-to-noise of 9 for cross correlating quasar spectra of SDSS-III with Planck and 20 for cross correlating with a future polarization based cosmic microwave background experiment. The detection of this effect would be a direct measure of the neutral hydrogen-matter cross correlation and could provide important information on the growth of structures at large scales in a redshift range which is still poorly probed. PMID:19792781

  10. Observations of a groove in the interplanetary Lyman alpha pattern as the signature of enhanced ionisation in the neutral sheet

    NASA Astrophysics Data System (ADS)

    Bertaux, J. L.; Quemerais, E.; Lallement, R.; Summanen, T.; Kyrola, E.

    1995-06-01

    We report several observations of the Lyman alpha interplanetary emission recorded by a photometer flown in 1976-1977 on board the Soviet spacecraft Prognoz-5 and Prognoz-6. Several scans made in a plane perpendicular to the sun were cutting through the maximum emission region. where the interstellar hydrogen is approaching nearest to the sun (upwind region). On each of these scans is observed a dip in the intensity curve near the ecliptic plane. about 30 deg wide and approximately equals 10% deep. They reveal the presence of a new feature of the interplanetary emission. a 'groove' aligned approximately with the ecliptic plane. This groove is present only near the upwind direction, and is interpreted as the result of enhanced ionisation of interstellar H by charge-exchange with the solar wind in a sheet of approximately 30 deg around the average position of the neutral sheet at this time of solar this Lyman alpha groove is a prime target for future observations with SWAN experiment on SOHO.

  11. Observations of a groove in the interplanetary Lyman alpha pattern as the signature of enhanced ionisation in the neutral sheet

    NASA Technical Reports Server (NTRS)

    Bertaux, J. L.; Quemerais, E.; Lallement, R.; Summanen, T.; Kyrola, E.

    1995-01-01

    We report several observations of the Lyman alpha interplanetary emission recorded by a photometer flown in 1976-1977 on board the Soviet spacecraft Prognoz-5 and Prognoz-6. Several scans made in a plane perpendicular to the sun were cutting through the maximum emission region. where the interstellar hydrogen is approaching nearest to the sun (upwind region). On each of these scans is observed a dip in the intensity curve near the ecliptic plane. about 30 deg wide and approximately equals 10% deep. They reveal the presence of a new feature of the interplanetary emission. a 'groove' aligned approximately with the ecliptic plane. This groove is present only near the upwind direction, and is interpreted as the result of enhanced ionisation of interstellar H by charge-exchange with the solar wind in a sheet of approximately 30 deg around the average position of the neutral sheet at this time of solar this Lyman alpha groove is a prime target for future observations with SWAN experiment on SOHO.

  12. Optical Alignment of the Chromospheric Lyman-Alpha SpectroPolarimeter using Sophisticated Methods to Minimize Activities under Vacuum

    NASA Technical Reports Server (NTRS)

    Giono, G.; Katsukawa, Y.; Ishikawa, R.; Narukage, N.; Kano, R.; Kubo, M.; Ishikawa, S.; Bando, T.; Hara, H.; Suematsu, Y.; Winebarger, A.; Kobayashi, K.

    2016-01-01

    The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a sounding-rocket instrument developed at the National Astronomical Observatory of Japan (NAOJ) as a part of an international collaboration. The in- strument main scientific goal is to achieve polarization measurement of the Lyman-alpha line at 121.56 nm emitted from the solar upper-chromosphere and transition region with an unprecedented 0.1% accuracy. For this purpose, the optics are composed of a Cassegrain telescope coated with a "cold mirror" coating optimized for UV reflection and a dual-channel spectrograph allowing for simultaneous observation of the two orthogonal states of polarization. Although the polarization sensitivity is the most important aspect of the instrument, the spatial and spectral resolutions of the instrument are also crucial to observe the chromospheric features and resolve the Ly- pro les. A precise alignment of the optics is required to ensure the resolutions, but experiments under vacuum conditions are needed since Ly-alpha is absorbed by air, making the alignment experiments difficult. To bypass this issue, we developed methods to align the telescope and the spectrograph separately in visible light. We will explain these methods and present the results for the optical alignment of the CLASP telescope and spectrograph. We will then discuss the combined performances of both parts to derive the expected resolutions of the instrument, and compare them with the flight observations performed on September 3rd 2015.

  13. A cosmic web filament revealed in Lyman-α emission around a luminous high-redshift quasar.

    PubMed

    Cantalupo, Sebastiano; Arrigoni-Battaia, Fabrizio; Prochaska, J Xavier; Hennawi, Joseph F; Madau, Piero

    2014-02-01

    Simulations of structure formation in the Universe predict that galaxies are embedded in a 'cosmic web', where most baryons reside as rarefied and highly ionized gas. This material has been studied for decades in absorption against background sources, but the sparseness of these inherently one-dimensional probes preclude direct constraints on the three-dimensional morphology of the underlying web. Here we report observations of a cosmic web filament in Lyman-α emission, discovered during a survey for cosmic gas fluorescently illuminated by bright quasars at redshift z ≈ 2.3. With a linear projected size of approximately 460 physical kiloparsecs, the Lyman-α emission surrounding the radio-quiet quasar UM 287 extends well beyond the virial radius of any plausible associated dark-matter halo and therefore traces intergalactic gas. The estimated cold gas mass of the filament from the observed emission-about 10(12.0 ± 0.5)/C(1/2) solar masses, where C is the gas clumping factor-is more than ten times larger than what is typically found in cosmological simulations, suggesting that a population of intergalactic gas clumps with subkiloparsec sizes may be missing in current numerical models. PMID:24463517

  14. Abundances and kinematics of a candidate sub-damped Lymanα galaxy toward PHL 1226

    NASA Astrophysics Data System (ADS)

    Christensen, L.; Schulte-Ladbeck, R. E.; Sánchez, S. F.; Becker, T.; Jahnke, K.; Kelz, A.; Roth, M. M.; Wisotzki, L.

    2005-01-01

    The spectrum of the quasar PHL 1226 is known to have a strong Mg II and sub-damped Lymanα (sub-DLA) absorption line system with N(H I)=(5±2)×1019 cm-2 at z=0.1602. Using integral field spectra from the Potsdam Multi Aperture Spectrophotometer (PMAS) we investigate a galaxy at an impact parameter of 6.4 arcsec which is most probably responsible for the absorption lines. A fainter galaxy at a similar redshift and a slightly larger distance from the QSO is known to exist, but we assume that the absorption is caused by the more nearby galaxy. From optical Balmer lines we estimate an intrinsic reddening consistent with 0, and a moderate star formation rate of 0.5 M⊙ >yr-1, is inferred from the Hα luminosity. Using nebular emission line ratios we find a solar oxygen abundance 12+log(O/H)=8.7±0.1 and a solar nitrogen to oxygen abundance ratio log(N/O)=-1.0±0.2. This abundance is larger than those of all known sub-DLA systems derived from analyses of metal absorption lines in quasar spectra. On the other hand, the properties are compatible with the most metal rich galaxies responsible for strong Mg II absorption systems. These two categories can be reconciled if we assume an abundance gradient similar to local galaxies. Under that assumption we predict abundances 12+log(O/H)=7.1 and log(N/O)=-1.9 for the sub-DLA cloud, which is similar to high redshift DLA and sub-DLA systems. We find evidence for a rotational velocity of ˜200 km s-1 over a length of ˜7 kpc. From the geometry and kinematics of the galaxy we estimate that the absorbing cloud does not belong to a rotating disk, but could originate in a rotating halo. Based on observations obtained at the German-Spanish Astronomical Center, Calar Alto, operated by the Max-Planck-Institut für Astronomie Heidelberg jointly with the Spanish National Commission for Astronomy.

  15. Differential evolution of the UV luminosity function of Lyman break galaxies from z ~ 5 to 3

    NASA Astrophysics Data System (ADS)

    Iwata, I.; Ohta, K.; Tamura, N.; Akiyama, M.; Aoki, K.; Ando, M.; Kiuchi, G.; Sawicki, M.

    2007-04-01

    We report the ultraviolet luminosity function (UVLF) of Lyman break galaxies at z ~ 5 derived from a deep and wide survey using the prime focus camera of the 8.2 m Subaru telescope (Suprime-Cam). Target fields consist of two blank regions of the sky, namely, the region including the Hubble Deep Field-North and the J0053+1234 region, and the total effective surveyed area is 1290 arcmin2. Applications of carefully determined colour selection criteria in V - Ic and Ic - z' yield a detection of 853 z ~ 5 candidates with z'AB < 26.5 mag. The UVLF at z ~ 5 based on this sample shows no significant change in the number density of bright (L >~ L*z=3) LBGs from that at z ~ 3, while there is a significant decline in the LF's faint end with increasing look-back time. This result means that the evolution of the number densities is differential with UV luminosity: the number density of UV luminous objects remains almost constant from z ~ 5 to 3 (the cosmic age is about 1.2 to 2.1 Gyr) while the number density of fainter objects gradually increases with cosmic time. This trend becomes apparent thanks to the small uncertainties in number densities both in the bright and faint parts of LFs at different epochs that are made possible by the deep and wide surveys we use. We discuss the origins of this differential evolution of the UVLF along the cosmic time and suggest that our observational findings are consistent with the biased galaxy evolution scenario: a galaxy population hosted by massive dark haloes starts active star formation preferentially at early cosmic time, while less massive galaxies increase their number density later. We also calculated the UV luminosity density by integrating the UVLF and at z ~ 5 found it to be 38.8+6.7-4.1 per cent of that at z ~ 3 for the luminosity range L > 0.1L*z=3. By combining our results with those from the literature, we find that the cosmic UV luminosity density marks its peak at and then slowly declines towards higher redshift. Based on

  16. Metal-rich damped/subdamped Lyman α quasar absorbers at z < 1

    NASA Astrophysics Data System (ADS)

    Péroux, C.; Meiring, J. D.; Kulkarni, V. P.; Ferlet, R.; Khare, P.; Lauroesch, J. T.; Vladilo, G.; York, D. G.

    2006-10-01

    Damped Lyman α absorbers (DLAs), seen in absorption against a background quasar, provide the most detailed probes available of element abundances in the Universe over >90per cent of its age. DLAs can be used to observationally measure the global mean metallicity in the Universe and its evolution with time. Paradoxically, these observations are more difficult at lower redshifts, where the absorber rest-frame ultraviolet (UV) spectra are cut-off due to the atmospheric absorption. We present here high-resolution Very Large Telescope/Ultraviolet and Visual Echelle Spectrograph observations of several elements contained in three DLAs and one sub-DLA with 0.6 < zabs < 0.9. We detect MgI, MgII, FeII, ZnII, CrII, MnII, TiII and CaII. Our observations more than double the high-resolution sample of [Zn/H] at z < 1. We also report the discovery of three metal-rich systems, whereas most previous measurements show low NHI-weighted mean metallicity projecting to about 1/6th solar level at z = 0. We derive [Zn/H] = -0.11 +/- 0.04 at zabs = 0.725, [Zn/H] = -0.54 +/- 0.20 at zabs = 0.740 and [Zn/H] = -0.49 +/- 0.22 at zabs = 0.652, plus one additional upper limit ([Zn/H] < -0.36 at zabs = 0.842). These measurements confirm the existence of quasar absorbers with relatively high metallicities based on abundance estimates free from the effect of dust depletion. Possible implications of these results for the metallicity of neutral gas phase in the past ~8 Gyr are presented and compared with models. Based on observations made during programme ESO 74.A-0597 at the European Southern Observatory with Ultraviolet and Visual Echelle Spectrograph (UVES) on the 8.2-m KUEYEN telescope operated at the Paranal Observatory, Chile. E-mail: cperoux@eso.org

  17. Star formation rate and extinction in faint z ∼ 4 Lyman break galaxies

    SciTech Connect

    To, Chun-Hao; Wang, Wei-Hao; Owen, Frazer N.

    2014-09-10

    We present a statistical detection of 1.5 GHz radio continuum emission from a sample of faint z ∼ 4 Lyman break galaxies (LBGs). To constrain their extinction and intrinsic star formation rate (SFR), we combine the latest ultradeep Very Large Array 1.5 GHz radio image and the Hubble Space Telescope Advanced Camera for Surveys (ACS) optical images in the GOODS-N. We select a large sample of 1771 z ∼ 4 LBGs from the ACS catalog using B {sub F435W}-dropout color criteria. Our LBG samples have I {sub F775W} ∼ 25-28 (AB), ∼0-3 mag fainter than M{sub UV}{sup ⋆} at z ∼ 4. In our stacked radio images, we find the LBGs to be point-like under our 2'' angular resolution. We measure their mean 1.5 GHz flux by stacking the measurements on the individual objects. We achieve a statistical detection of S {sub 1.5} {sub GHz} = 0.210 ± 0.075 μJy at ∼3σ for the first time on such a faint LBG population at z ∼ 4. The measurement takes into account the effects of source size and blending of multiple objects. The detection is visually confirmed by stacking the radio images of the LBGs, and the uncertainty is quantified with Monte Carlo simulations on the radio image. The stacked radio flux corresponds to an obscured SFR of 16.0 ± 5.7 M {sub ☉} yr{sup –1}, and implies a rest-frame UV extinction correction factor of 3.8. This extinction correction is in excellent agreement with that derived from the observed UV continuum spectral slope, using the local calibration of Meurer et al. This result supports the use of the local calibration on high-redshift LBGs to derive the extinction correction and SFR, and also disfavors a steep reddening curve such as that of the Small Magellanic Cloud.

  18. THE LYMAN ALPHA MORPHOLOGY OF LOCAL STARBURST GALAXIES: RELEASE OF CALIBRATED IMAGES

    SciTech Connect

    Oestlin, Goeran; Hayes, Matthew; Kunth, Daniel; Atek, Hakim; Mas-Hesse, J. Miguel; Leitherer, Claus; Petrosian, Artashes E-mail: matthew.hayes@unige.ch

    2009-09-15

    We present reduced and calibrated high resolution Lyman-alpha (Ly{alpha}) images for a sample of six local star-forming galaxies. Targets were selected to represent a range in luminosity and metallicity and to include both known Ly{alpha} emitters and nonemitters. Far ultraviolet imaging was carried out with the Solar Blind Channel of the Advanced Camera for Surveys on the Hubble Space Telescope (HST) in the F122M (Ly{alpha} online) and F140LP (continuum) filters. The resulting Ly{alpha} images are the product of careful modeling of both the stellar and nebular continua, facilitated by supporting HST imaging at {lambda} {approx} 2200, 3300, 4400, 5500, H{alpha}, and 8000 A, combined with Starburst 99 evolutionary synthesis models, and prescriptions for dust extinction on the continuum. In all, the resulting morphologies in Ly{alpha}, H{alpha}, and UV continuum are qualitatively very different and we show that the bulk of Ly{alpha} emerges in a diffuse component resulting from resonant scattering events. Ly{alpha} escape fractions, computed from integrated H{alpha} luminosities and recombination theory, are found never to exceed 14%. Internal dust extinction is estimated in each pixel and used to correct Ly{alpha} fluxes. However, the extinction corrections are far too small (by factors from 2.6 to infinity) to reconcile the emerging global Ly{alpha} luminosities with standard recombination predictions. Surprisingly, when comparing the global equivalent widths of Ly{alpha} and H{alpha}, the two quantities appear to be anticorrelated, which may be due to the evolution of mechanical feedback from the starburst. This calls for caution in the interpretation of Ly{alpha} observations in terms of star formation rates. The images presented have a physical resolution 3 orders of magnitude better than attainable at high redshifts from the ground with current instrumentation and our images may therefore serve as useful templates for comparing with observations and modeling of

  19. Analyzing low signal-to-noise FUSE spectra. Confirmation of Lyman continuum escape from Haro 11

    NASA Astrophysics Data System (ADS)

    Leitet, E.; Bergvall, N.; Piskunov, N.; Andersson, B.-G.

    2011-08-01

    Context. Galaxies are believed to be the main providers of Lyman continuum (LyC) photons during the early phases of the cosmic reionization. Little is known however, when it comes to escape fractions and the mechanisms behind the leakage. To learn more, one may look at local objects, but so far only one low-z galaxy has shown any signs of emitting LyC radiation. With data from the Far Ultraviolet Spectroscopic Explorer (FUSE), we previously found an absolute escape fraction of ionizing photons (fesc) of 4-10% for the blue compact galaxy Haro 11. However, using a revised version of the reduction pipeline on the same data set, Grimes and collaborators were unable to confirm this and derived an upper limit of fesc ≲ 2% . Aims: We attempt to determine whether Haro 11 is emitting ionizing radiation to a significant level or not. We also investigate the performance of the reduction pipeline for faint targets such as Haro 11, and introduce a new approach to the background subtraction. Methods: The final version of the reduction pipeline, CalFUSE v3.2, was applied to the same Haro 11 data set as the two previous authors used. At these faint flux levels, both FUSE and CalFUSE are pushed to their limits, and a detailed analysis was undertaken to monitor the performance of the pipeline. We show that non-simultaneous background estimates are insuffient when working with data of low signal-to-noise ratio (S/N), and a new background model was developed based on a direct fit to the detector response. Results: We find that one has to be very careful when using CalFUSE v3.2 on low S/N data, and especially when dealing with sources where signal might originate from off-center regions. Applying the new background fit, a significant signal is detected in the LyC in both detector segments covering these wavelengths. Thus, the leakage is confirmed with a flux density of f900 = 4.0 × 10-15 erg s-1 cm-2 Å-1 (S/N = 4.6), measured on the airglow free regions in the LyC for the night

  20. The VLT LBG redshift survey - V. Characterizing the z = 3.1 Lyman α emitter population

    NASA Astrophysics Data System (ADS)

    Bielby, R. M.; Tummuangpak, P.; Shanks, T.; Francke, H.; Crighton, N. H. M.; Bañados, E.; González-López, Jorge; Infante, L.; Orsi, A.

    2016-03-01

    We present a survey of z ˜ 3 Lyα emitters (LAEs) within the fields of the VLT Lyman break galaxies (LBG) redshift survey. The data encompass five independent survey fields co-spatial with spectroscopic LBG data and covering a larger total area than previously analysed for LAE number counts and clustering. This affords an improved analysis over previous work by minimizing the effects of cosmic variance and allowing the cross-clustering analysis of LAEs and LBGs. Our photometric sample consists of ≈600 LAE candidates, over an area of 1.07 deg2, with equivalent widths of ≳65 Å and a flux limit of ≈2 × 10-17 erg cm-2 s-1. From spectroscopic follow-up, we measured a success rate of 78 ± 18 per cent. We find the R-band continuum luminosity function to be ˜10 times lower than the luminosity function of LBGs at this redshift, consistent with previous studies. Exploiting the large area of the survey, we estimate the LAE auto-correlation function and find a clustering length of r0 = 2.86 ± 0.33 h-1 Mpc, low compared to the z ˜ 3 LBG population, but somewhat higher than previous LAE measurements. This corresponds to a median halo mass of MDM = 1011.0±0.3 h-1 M⊙. We present an analysis of clustering length versus continuum magnitude and find that the measurements for LAEs and LBGs are consistent at faint magnitudes. Our combined data set of LAEs and LBGs allows us to measure, for the first time, the LBG-LAE cross-correlation, finding a clustering length of r0 = 3.29 ± 0.57 h-1 Mpc and a LAE halo mass of 1011.1±0.4 h-1 M⊙. Overall, we conclude that LAEs inhabit primarily low-mass haloes, but form a relatively small proportion of the galaxy population found in such haloes.

  1. Imprecision profiling.

    PubMed

    Sadler, William A

    2008-08-01

    * Imprecision profiles express precision characteristics of an assay over a range of concentration values. They can convert large quantities of potentially complex data into an easily interpreted graphical summary. * Imprecision profile estimation does not require precisely structured data. This implies that structured method evaluation data can be easily compared with, or merged with, less structured internal quality control (QC) data (or with data from any other source). * Although originally conceived for immunoassays, imprecision profiles could, in principle, be used as a summary method with any measurement system where precision varies with level of measurand. PMID:18852854

  2. Series Transmission Line Transformer

    DOEpatents

    Buckles, Robert A.; Booth, Rex; Yen, Boris T.

    2004-06-29

    A series transmission line transformer is set forth which includes two or more of impedance matched sets of at least two transmissions lines such as shielded cables, connected in parallel at one end ans series at the other in a cascading fashion. The cables are wound about a magnetic core. The series transmission line transformer (STLT) which can provide for higher impedance ratios and bandwidths, which is scalable, and which is of simpler design and construction.

  3. Fourier Series Operating Package

    NASA Technical Reports Server (NTRS)

    Charnow, Milton L.

    1961-01-01

    This report presents a computer program for multiplying, adding, differentiating, integrating, "barring" and scalarly multiplying "literal" Fourier series as such, and for extracting the coefficients of specified terms.

  4. Leadership Profiles.

    ERIC Educational Resources Information Center

    Teach, Beverly; And Others

    1994-01-01

    Presents profiles of two leaders in the field of educational media and technology: Carolyn Guss and Mendel Sherman, both retired professors from Indiana University's program in Information Systems Technology. (KRN)

  5. Pioneer Profile.

    ERIC Educational Resources Information Center

    Butcher, Channa Beth

    1987-01-01

    Profiles Herbert A. Sweet, founder and director of Acorn Farms Day Camp (Indiana) for 44 years. Includes reminiscences about the camp's program, staffing, food, World War II, affiliation with the American Camping Association, and camps/directors of today. (NEC)

  6. Drafting. Occupational Competency Analysis Profile.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. Vocational Instructional Materials Lab.

    This Drafting Occupational Competency Analysis Profile (OCAP) is one of a series of competency lists, verified by expert workers, that have evolved from a modified DACUM (Developing a Curriculum) job analysis process involving business, industry, labor, and community agency representatives from throughout Ohio. This OCAP identifies the…

  7. Welding. Occupational Competency Analysis Profile.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. Vocational Instructional Materials Lab.

    This Occupational Competency Analysis Profile (OCAP), which is one of a series of OCAPs developed to identify the skills that Ohio employers deem necessary to entering a given occupation/occupational area, lists the occupational, academic, and employability skills required of individuals entering the occupation of welder. The introduction explains…

  8. Accounting. Occupational Competency Analysis Profile.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. Vocational Instructional Materials Lab.

    This Accounting Occupational Competency Analysis Profile (OCAP) is one of a series of competency lists, verified by expert workers, that have evolved from a modified DACUM (Developing a Curriculum) job analysis process involving business, industry, labor, and community agency representatives from throughout Ohio. This OCAP identifies the…

  9. AN ULTRAVIOLET ULTRA-LUMINOUS LYMAN BREAK GALAXY AT Z = 2.78 IN NDWFS BOOeTES FIELD {sup ,} {sup ,}

    SciTech Connect

    Bian Fuyan; Fan Xiaohui; Jiang Linhua; McGreer, Ian; Wang Ran; Dey, Arjun; Green, Richard F.; Maiolino, Roberto; Walter, Fabian; Lin, Yen-Ting

    2012-10-01

    We present one of the most ultraviolet (UV) luminous Lyman break galaxies (LBGs; J1432+3358) at z = 2.78, discovered in the NOAO Deep Wide-Field Survey Booetes field. The R-band magnitude of J1432+3358 is 22.29 AB, more than two magnitudes brighter than typical L* LBGs at this redshift. The deep z-band image reveals two components of J1432+3358 separated by 1.''0 with a flux ratio of 3:1. The high signal-to-noise ratio rest-frame UV spectrum shows Ly{alpha} emission line and interstellar medium absorption lines. The absence of N V and C IV emission lines, and the non-detection in X-ray and radio wavelengths and mid-infrared (MIR) colors indicates weak or no active galactic nuclei (<10%) in this galaxy. The galaxy shows a broader line profile, with a FWHM of about 1000 km s{sup -1} and a larger outflow velocity ( Almost-Equal-To 500 km s{sup -1}) than those of typical z {approx} 3 LBGs. The physical properties are derived by fitting the spectral energy distribution (SED) with stellar synthesis models. The dust extinction, E(B - V) = 0.12, is similar to that in normal LBGs. The star formation rates (SFRs) derived from the SED fitting and the dust-corrected UV flux are consistent with each other, {approx}300 M{sub Sun} yr{sup -1}, and the stellar mass is (1.3 {+-} 0.3) Multiplication-Sign 10{sup 11} M{sub Sun }. The SFR and stellar mass in J1432+3358 are about an order of magnitude higher than those in normal LBGs. The SED-fitting results support that J1432+3358 has a continuous star formation history, with a star formation episode of 6.3 Multiplication-Sign 10{sup 8} yr. The morphology of J1432+3358 and its physical properties suggest that J1432+3358 is in an early phase of a 3:1 merger process. The unique properties and the low space number density ({approx}10{sup -7} Mpc{sup -3}) are consistent with the interpretation that such galaxies are either found in a short unobscured phase of the star formation or that a small fraction of intensive star-forming galaxies are

  10. A powerful radio galaxy at z=3.6 in a giant rotating Lyman α halo.

    NASA Astrophysics Data System (ADS)

    van Ojik, R.; Roettgering, H. J. A.; Carilli, C. L.; Miley, G. K.; Bremer, M. N.; Macchetto, F.

    1996-09-01

    We present the discovery and detailed observations of the radio galaxy 1243+036 at a redshift of z=3.57. The radio source was selected on the basis of its extremely steep radio spectrum, suggesting that it might be very distant. The radio source was identified with a galaxy of R magnitude 22.5. Subsequent spectroscopy showed strong Lyman α and [O III]λλ5007,4959 emission, indicating that the object is a radio galaxy at z=3.57. High resolution (0.2") radio maps show an FRII type radio source with a sharply bent radio structure. Strong depolarization of the radio emission indicates that the source is embedded in a magneto-ionic medium. The most spectacular feature of 1243+036 is the presence of a Lyα halo of luminosity ~10^44.5^erg/s which extends over ~20" (135kpc). A 0.6" resolution Lyα image shows that the emission line gas is aligned with the main axis of the radio source and has structure down to the scale of the resolution. High resolution spectra show that the Lyα emitting gas has complex kinematic structure. The gas contained within the radio structure has a relatively high velocity width (~1500km/s FWHM). The component of the Lyα emission that coincides with the bend in the radio structure is blueshifted with respect to the peak of the emission by 1100km/s. There is low surface brightness Lyα emission aligned with, but extending 40kpc beyond both sides of the radio source. This halo has a narrow velocity width (~250km/s FWHM) and a velocity gradient of 450km/s over the extent of the emission. The presence of the quiescent Lyα component aligned with the AGN axis, but outside the radio source, is strong evidence that photoionization by anisotropically emitted radiation from the active nucleus is occurring. Various mechanisms for the origin and kinematics of the Lyα halo are discussed. Because the halo extends beyond the radio structure with less violent and more ordered kinematics than inside the radio structure, we conclude that the outer halo and

  11. Nurturing Lyman break galaxies: observed link between environment and spectroscopic features

    NASA Astrophysics Data System (ADS)

    Cooke, J.; Omori, Y.; Ryan-Weber, E. V.

    2013-08-01

    We examine the effects of magnitude, colour and Lyα equivalent width (EW) on the spatial distribution of z ˜ 3 Lyman break galaxies (LBGs) and report significant differences in the two-point autocorrelation functions. The results are obtained using samples of ˜10 000-55 000 LBGs from the Canada-France-Hawaii Telescope Legacy Survey Deep Fields. We find that magnitude has a larger effect on the autocorrelation function amplitude on small scales (≲1 h^{-1}_{70} Mpc, the one-halo term) and that colour is more influential on large scales (≳1 h^{-1}_{70} Mpc, the two-halo term). We find the most significant differences between autocorrelation functions for LBGs with dominant net Lyα EW in absorption (aLBGs) and dominant net Lyα EW in emission (eLBGs) determined from ≳95 per cent pure samples of each population using a photometric technique calibrated from ˜1000 spectra. The aLBG autocorrelation function has a higher two-halo amplitude than the full LBG sample and has a one-halo term departure from a power-law fit near ˜1 h^{-1}_{70} Mpc, corresponding to the virial radii of MDM ˜ 1013 M⊙ dark matter haloes. In contrast, the eLBG autocorrelation function has a one-halo term departure at ˜0.12 h^{-1}_{70} Mpc, suggesting parent haloes of MDM ˜ 1011 M⊙ and a two-halo term that exhibits a curious `hump' on intermediate scales that we localize to the faintest, bluest members. The aLBG-eLBG cross-correlation function exhibits an anticorrelation component that reinforces different physical locations for a significant fraction of aLBGs and eLBGs. We introduce a `shell' model for the eLBG autocorrelation function and find that the form can be reproduced assuming that a significant fraction of eLBGs have a shell-like spatial distribution. Based on the analysis of all LBG subsamples, and considering the natural asymmetric distribution of LBGs on the colour-magnitude diagram, we conclude that aLBGs are more likely to reside in group-like environments hosting

  12. Lower GI Series

    MedlinePlus

    ... GI series can help diagnose the cause of • abdominal pain • bleeding from the anus • changes in bowel habits • ... GI series should seek immediate medical attention: • severe abdominal pain • bloody bowel movements or bleeding from the anus • ...

  13. Fourier Series Optimization Opportunity

    ERIC Educational Resources Information Center

    Winkel, Brian

    2008-01-01

    This note discusses the introduction of Fourier series as an immediate application of optimization of a function of more than one variable. Specifically, it is shown how the study of Fourier series can be motivated to enrich a multivariable calculus class. This is done through discovery learning and use of technology wherein students build the…

  14. Lyman-alpha line as a solar activity index for calculations of solar spectrum in the EUV region

    NASA Astrophysics Data System (ADS)

    Nusinov, Anatoliy; Kazachevskaya, Tamara; Katyushina, Valeria; Woods, Thomas

    It is investigated a possibility of retrieval of solar spectrum data using intensity observational data of the only solar spectral line L (Hydrogen Lyman-alpha, 121.6 nm).Using as an example spectra obtained by SEE instruments on TIMED satellite, it was shown, that both for lines and for continuum in the spectral range 27-105 nm, which is essential for ionization processes in the ionosphere, a correlation between their intensities and L was high. Therefore it becomes possible to use L measurements data as a natural solar activity index for calculations of EUV solar emission spectrum for solving aeronomical problems. It is noticed, that EUV model, obtained with using SEE data, does not allow to calculate correctly critical frequencies of ionospheric E-layer owing to low intensities of lines 97.7 and 102.6 nm, which produce the main part of ionization in ionospheric E-region.

  15. Fitting methods for baryon acoustic oscillations in the Lyman-α forest fluctuations in BOSS data release 9

    SciTech Connect

    Kirkby, David; Margala, Daniel; Blomqvist, Michael; Slosar, Anže; Bailey, Stephen; Carithers, Bill; Busca, Nicolás G.; Bautista, Julian E.; Brownstein, Joel R.; Dawson, Kyle S.; Croft, Rupert A.C.; Font-Ribera, Andreu; Miralda-Escudé, Jordi; Myers, Adam D.; Nichol, Robert C.; Pâris, Isabelle; Petitjean, Patrick; and others

    2013-03-01

    We describe fitting methods developed to analyze fluctuations in the Lyman-α forest and measure the parameters of baryon acoustic oscillations (BAO). We apply our methods to BOSS Data Release 9. Our method is based on models of the three-dimensional correlation function in physical coordinate space, and includes the effects of redshift-space distortions, anisotropic non-linear broadening, and broadband distortions. We allow for independent scale factors along and perpendicular to the line of sight to minimize the dependence on our assumed fiducial cosmology and to obtain separate measurements of the BAO angular and relative velocity scales. Our fitting software and the input files needed to reproduce our main BOSS Data Release 9 results are publicly available.

  16. The Lyman continuum escape fraction of galaxies at z = 3.3 in the VUDS-LBC/COSMOS field

    NASA Astrophysics Data System (ADS)

    Grazian, A.; Giallongo, E.; Gerbasi, R.; Fiore, F.; Fontana, A.; Le Fèvre, O.; Pentericci, L.; Vanzella, E.; Zamorani, G.; Cassata, P.; Garilli, B.; Le Brun, V.; Maccagni, D.; Tasca, L. A. M.; Thomas, R.; Zucca, E.; Amorín, R.; Bardelli, S.; Cassarà, L. P.; Castellano, M.; Cimatti, A.; Cucciati, O.; Durkalec, A.; Giavalisco, M.; Hathi, N. P.; Ilbert, O.; Lemaux, B. C.; Paltani, S.; Ribeiro, B.; Schaerer, D.; Scodeggio, M.; Sommariva, V.; Talia, M.; Tresse, L.; Vergani, D.; Bonchi, A.; Boutsia, K.; Capak, P.; Charlot, S.; Contini, T.; de la Torre, S.; Dunlop, J.; Fotopoulou, S.; Guaita, L.; Koekemoer, A.; López-Sanjuan, C.; Mellier, Y.; Merlin, E.; Paris, D.; Pforr, J.; Pilo, S.; Santini, P.; Scoville, N.; Taniguchi, Y.; Wang, P. W.

    2016-01-01

    Context. The ionizing Lyman continuum flux escaping from high-redshift galaxies into the intergalactic medium is a fundamental quantity to understand the physical processes involved in the reionization epoch. However, from an observational point of view, direct detections of HI ionizing photons at high redshifts are feasible for galaxies mainly in the interval z ~ 3-4. Aims: We have investigated a sample of star-forming galaxies at z ~ 3.3 to search for possible detections of Lyman continuum ionizing photons escaping from galaxy halos. Methods: We used deep ultraviolet (UV) imaging in the COSMOS field, obtained with the prime focus camera LBC at the LBT telescope, along with a catalogue of spectroscopic redshifts obtained by the VIMOS Ultra Deep Survey (VUDS) to build a sample of 45 galaxies at z ~ 3.3 with L> 0.5 L∗. We obtained deep LBC images of galaxies with spectroscopic redshifts in the interval 3.27 Lyman edge at 912 Å. Their flux ratio is related to the ionizing escape fraction after statistical removal of the absorption by the intergalactic medium along the line of sight. Results: A subsample of ten galaxies apparently shows escape fractions >28%, but a detailed analysis of their properties reveals that, with the exception of two marginal detections (S/N ~ 2) in the U-band, all the other eight galaxies are most likely contaminated by the UV flux of low-redshift interlopers located close (in angular position) to the high-z targets. The average escape fraction derived from the stacking of the cleaned sample was constrained to fescrel < 2%. The implied hydrogen photoionization rate is a factor two lower than that needed to keep the intergalactic medium ionized at z ~ 3, as observed in the Lyman-α forest of high

  17. A surface chemistry model for the altitude dependence of the N2 Lyman-Birge-Hopfield glow on spacecraft

    NASA Technical Reports Server (NTRS)

    Cuthbertson, J. W.; Langer, W. D.

    1989-01-01

    Low-orbiting spacecraft have been observed to cause UV emission in the N2 Lyman-Birge-Hopfield bands. The chemical processes expected to underlie this emission are examined. Recombination between incident and adsorbed N atoms has been proposed as the source of radiating excited N2. However, the cubic dependence of the intensity, as N2 concentration cubed or N2 concentration squared x O concentration, has not been explained. It is suggested that this can be explained by a model where adsorption of nitrogen on the spacecraft surface is balanced mainly by the removal of N from the surface by atomic oxygen. On the basis of these assumptions a mathematical model for the production of excited N2 is constructed. It is shown that for large enough reaction efficiencies the model predicts a magnitude and altitude dependence for the emission which can explain the measurements reported by other investigators.

  18. Enhancement of Lyman-. alpha. radiation following foil-induced dissociation of fast ionic hydrogen clusters H sub n sup +

    SciTech Connect

    Farizon, M.; Clouvas, A.; de Castro Faria, N.V.; Farizon-Mazuy, B.; Gaillard, M.J.; Gerlic, E. ); Denis, A.; Desesquelles, J.; Ouerdane, Y. )

    1991-01-01

    We have measured the Lyman-{alpha} radiation following foil breakup of hydrogen ionic clusters H{sub {ital n}}{sup +} ({ital n}=2 and {ital n}=3 to 61, odd) with velocities above and around the Bohr velocity. An enhancement of this radiation was observed and could reach a factor of 3 with respect to the proton case of the same velocity. Cluster mass number, velocity, and thickness dependences of the relative population of the 2{ital p} state in hydrogen fragments following H{sub {ital n}}{sup +} foil dissociation have been extracted. A specific collective effect on the 2{ital p}-state hydrogen has been observed and interpreted in terms of charge-exchange processes.

  19. SERI Wind Energy Program

    SciTech Connect

    Noun, R. J.

    1983-06-01

    The SERI Wind Energy Program manages the areas or innovative research, wind systems analysis, and environmental compatibility for the U.S. Department of Energy. Since 1978, SERI wind program staff have conducted in-house aerodynamic and engineering analyses of novel concepts for wind energy conversion and have managed over 20 subcontracts to determine technical feasibility; the most promising of these concepts is the passive blade cyclic pitch control project. In the area of systems analysis, the SERI program has analyzed the impact of intermittent generation on the reliability of electric utility systems using standard utility planning models. SERI has also conducted methodology assessments. Environmental issues related to television interference and acoustic noise from large wind turbines have been addressed. SERI has identified the causes, effects, and potential control of acoustic noise emissions from large wind turbines.

  20. Variability of Solar UV Irradiance Related to Bright Magnetic Features Observed in Call K-Line: Relationship between Lyman alpha and K-line Report for UARS funding agency

    NASA Technical Reports Server (NTRS)

    Zirin, Harold; Cameron, Robert

    1999-01-01

    In this report we comment on the relationship between the Lyman alpha and Calcium K-line emission from the Sun. We firstly examine resolved Lyman alpha images (from TRACE) and resolved K-line images. We find that the Lyman alpha emission is consistent with a linear dependence on the K-line emission. As this is in conflict with the analysis of Johannesson et al.(1995, 1998) we proceed by comparing the disk integrated Lyman alpha flux as a function of ratio between the disk integrated Mg II core and wing fluxes (Johannesson et al (1998) having previously found a linear dependence between this index and the BBSO K-line index). We find that a reasonably good fit can be obtained, however note the discrepancies which lead Johannesson et al to consider the square root relationship. We suggest an alternative interpretation of the discrepancy.