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Sample records for absorption line shape

  1. Line shape studies in CW dye laser intracavity absorption

    NASA Astrophysics Data System (ADS)

    Kumar, P.; Brink, G. O.; Spence, S.; Lakkaraju, H. S.

    1980-01-01

    The line shape of the signals observed by intracavity absorption in an atomic beam of barium is studied as a function of absorber density. Complex structure is observed consisting of both absorption and enhancement features. Comparison is made with models of intracavity absorption, and it is concluded that the rate equation model in its present form does not explain the structure. On the other hand the super-regen model does seem able to partially account for the observed structure. The complexity of the line shape will directly affect those workers who are using intracavity absorption as a spectroscopic technique.

  2. Intracavity absorption line shape and the super-regen model

    NASA Astrophysics Data System (ADS)

    Lewellen, L. R.; Brink, G. O.

    1981-10-01

    Intracavity absorption has been observed in a short lived excited state of helium produced in an RF discharge inside the dye laser cavity. The line shape consists of an absorption feature with two symmetric enhancement wings. The central absorption feature is considerably broadened over the natural width, and this is shown to be in agreement with the superregen model. It is also shown that under certain conditions the ICA signal inverts so that the central feature becomes enhanced and the symmetric wings appear as absorption. This result is also in agreement with predictions of the model.

  3. Effects of velocity averaging on the shapes of absorption lines

    NASA Technical Reports Server (NTRS)

    Pickett, H. M.

    1980-01-01

    The velocity averaging of collision cross sections produces non-Lorentz line shapes, even at densities where Doppler broadening is not apparent. The magnitude of the effects will be described using a model in which the collision broadening depends on a simple velocity power law. The effect of the modified profile on experimental measures of linewidth, shift and amplitude will be examined and an improved approximate line shape will be derived.

  4. Multi-harmonic measurements of line shape under low absorption conditions

    NASA Astrophysics Data System (ADS)

    Lan, L. J.; Ding, Y. J.; Peng, Z. M.; Du, Y. J.; Liu, Y. F.; Li, Z.

    2014-06-01

    We propose a method that employs the ratios of the 2nd and 4th harmonics at the line center to measure line shape under low absorption conditions. To verify this method, the transition of CO2 at 6,982.0678 cm-1 is selected to measure line shape by using the proposed method and direct absorption spectroscopy in laboratory conditions. The results from both methods have a high degree of consistency. This satisfactory agreement indicates the validity of the proposed method.

  5. Line shape of 57Co sources exhibiting self absorption

    NASA Astrophysics Data System (ADS)

    Spiering, H.; Ksenofontov, V.; Leupold, O.; Kusz, J.; Deák, L.; Németh, Z.; Bogdán, C.; Bottyán, L.; Nagy, D. L.

    2016-12-01

    The effect of selfabsorption in Mössbauer sources is studied in detail. Spectra were measured using an old 57 C o/ R h source of 74 M B q activity with an original activity of ca. 3.7 G B q and a 0.15 G B q 57 C o/ α - F e source magnetized by an in-plane magnetic field of 0.2 T. The 57 C o/ α - F e source of a thickness of 25 μ was used both from the active and the inactive side giving cause to very different selfabsorption effects. The absorber was a single crystal of ferrous ammonium sulphate hexahydrate (FAS). Its absorption properties were taken over from a detailed study (Bull et al., Hyperfine Interact. 94(1-3), 1; Spiering et al. 2). FAS (space group P21/c) crystallizes as flat plates containing the (overline {2}01) plane. The γ-direction was orthogonal to the crystal plate. The 57 C o atoms of the 57 C o/ R h source were assumed to be homogeneously distributed over a 6 μ thick Rh foil and to follow a one dimensional diffusion profile in the 25 μ Fe-foil. The diffusion length was fitted to 10 μ. The theory follows the Blume-Kistner equations for forward scattering (Blume and Kistner, Phys. Rev. 171, 417, 3) by integrating over the source sampled up to 128 layers.

  6. Asymmetry between absorption and photoluminescence line shapes of TPD: spectroscopic fingerprint of the twisted biphenyl core.

    PubMed

    Scholz, Reinhard; Gisslén, Linus; Himcinschi, Cameliu; Vragović, Igor; Calzado, Eva M; Louis, Enrique; San Fabián Maroto, Emilio; Díaz-García, María A

    2009-01-01

    We analyze absorption, photoluminescence (PL), and resonant Raman spectra of N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD), with the aim of providing a microscopic interpretation of a significant Stokes shift of about 0.5 eV that makes this material suitable for stimulated emission. The optical spectra were measured for TPD dissolved in toluene and chloroform, as well as for polystyrene films doped with varying amounts of TPD. In addition, we measured preresonant and resonant Raman spectra, giving direct access to the vibrational modes elongated in the relaxed excited geometry of the molecule. The experimental data are interpreted with calculations of the molecular geometry in the electronic ground state and the optically excited state using density functional theory. Several strongly elongated high-frequency modes within the carbon rings results in a vibronic progression with a calculated spacing of 158 meV, corroborated by the observation of vibrational sidebands in the PL spectra. The peculiarities of the potential energy surfaces related to a twisting around the central bond in the biphenyl core of TPD allow to quantify the asymmetry between the line shapes observed in absorption and emission. PMID:19086796

  7. Line-Parameter Measurements and Stringent Tests of Line-Shape Models Based on Cavity-Enhanced Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Bielska, Katarzyna; Fleisher, Adam J.; Hodges, Joseph T.; Lin, Hong; Long, David A.; Reed, Zachary D.; Sironneau, Vincent; Truong, Gar-Wing; Wójtewicz, Szymon

    2014-06-01

    Laser methods that are based on cavity-enhanced absorption spectroscopy (CEAS) are well-suited for measuring molecular line parameters under conditions of low optical density, and as such they are complementary to broadband Fourier-transform spectroscopy (FTS) techniques. Attributes of CEAS include relatively low detection limits, accurate and precise detuning axes and high fidelity measurements of line shape. In many cases these performance criteria are superior to those obtained using direct laser absorption spectroscopy and FTS-based systems. In this presentation we will survey several examples of frequency-stabilized cavity ring-down spectroscopy (FS-CRDS)1 measurements obtained with laser spectrometers developed at the National Institute of Standards and Technology (NIST) in Gaithersburg Maryland. These experiments, which are motivated by atmospheric monitoring and remote-sensing applications that require high-precision and accuracy, involve nearinfrared transitions of carbon dioxide, water, oxygen and methane. We discuss spectra with signal-to-noise ratios exceeding 106, frequency axes with absolute uncertainties in the 10 kHz to 100 kHz range and linked to a Cs clock, line parameters with relative uncertainties at the 0.2 % level and isotopic ratios measured with a precision of 0.03 %. We also present FS-CRDS measurements of CO2 line intensities which are measured at atmospheric concentration levels and linked to gravimetric standards for CO2 in air, and we quantify pressure-dependent deviations between various theoretical line profiles and measured line shapes. Finally we also present recent efforts to increase data throughput and spectral coverage in CEAS experiments. We describe three new high-bandwidth CEAS techniques including frequency-agile, rapid scanning spectroscopy (FARS)2, which enables continuous-wave measurements of cavity mode linewidth and acquisition of ringdown decays with no dead time during laser frequency tuning, heterodyne

  8. A far wing line shape theory and its application to the foreign-broadened water continuum absorption. III

    NASA Technical Reports Server (NTRS)

    Ma, Q.; Tipping, R. H.

    1992-01-01

    The far wing line shape theory developed previously and applied to the calculation of the continuum absorption of pure water vapor is extended to foreign-broadened continua. Explicit results are presented for H2O-N2 and H2O-CO2 in the frequency range from 0 to 10,000/cm. For H2O-N2 the positive and negative resonant frequency average line shape functions and absorption coefficients are computed for a number of temperatures between 296 and 430 K for comparison with available laboratory data. In general the agreement is very good.

  9. Time-averaging approximation in the interaction picture: Absorption line shapes for coupled chromophores with application to liquid water

    NASA Astrophysics Data System (ADS)

    Yang, Mino; Skinner, J. L.

    2011-10-01

    The time-averaging approximation (TAA), originally developed to calculate vibrational line shapes for coupled chromophores using mixed quantum/classical methods, is reformulated. In the original version of the theory, time averaging was performed for the full one-exciton Hamiltonian, while herein the time averaging is performed on the coupling (off-diagonal) Hamiltonian in the interaction picture. As a result, the influence of the dynamic fluctuations of the transition energies is more accurately described. We compare numerical results of the two versions of the TAA with numerically exact results for the vibrational absorption line shape of the OH stretching modes in neat water. It is shown that the TAA in the interaction picture yields theoretical line shapes that are in better agreement with exact results.

  10. Pulsed Airborne Lidar Measurements of Atmospheric CO2 Column Absorption and Line Shapes from 3-13 km Altitudes

    NASA Technical Reports Server (NTRS)

    Abshire, James; Riris, Haris; Allan, Graham; Weaver, Clark; Mao, Jianping; Sun, Xiaoli; Hasselbrack, William

    2010-01-01

    US Department of Energy's (DOE) SGP ARM site at altitudes from 3-8 km. These flights were coordinated with DOE investigators who flew an in-situ CO2 sensor on a Cessna aircraft under the path. The increasing CO2 line absorptions with altitudes were evident and comparison with in-situ measurements showed agreements to 6 ppm. In spring 2009 we improved the aircraft's nadir window and during July and August we made 9 additional 2 hour long flights and measured the atmospheric CO2 absorption and line shapes using the 1572.33 nm CO2 line. Measurements were made at stepped altitudes from 3-13 km over a variety of surface types in Nebraska, Illinois, the SGP ARM site, and near and over the Chesapeake Bay in North Carolina and eastern Virginia. Strong laser signals and clear CO2 line shapes were observed at all altitudes, and some measurements were made through thin clouds. The flights over the ARM site were underflown with in-situ measurements made from the DOE Cessna. Analysis shows that the average signal levels follow predicted values, the altimetry measurements had an uncertainty of about 4 m, and that the average optical line depths follow the number density calculated from in-situ sensor readings. The Oklahoma and east coast flights were coordinated with a LaRC/ITT CO2 lidar on the LaRC UC-12 aircraft, a LaRC in-situ CO2 sensor, and the Oklahoma flights also included a JPL CO2 lidar on a Twin Otter aircraft. More details of the flights, measurements, analysis and scaling to space will be described in the presentation.

  11. Pulsed Airborne Lidar measurements of Atmospheric CO2 Column Absorption and Line Shapes from 3-13 km altitudes

    NASA Astrophysics Data System (ADS)

    Abshire, James; Riris, Haris; Allan, Graham; Weaver, Clark; Mao, Jianping; Sun, Xiaoli; Hasselbrack, William

    2010-05-01

    US Department of Energy's (DOE) SGP ARM site at altitudes from 3-8 km. These flights were coordinated with DOE investigators who flew an in-situ CO2 sensor on a Cessna aircraft under the path. The increasing CO2 line absorptions with altitudes were evident and comparison with in-situ measurements showed agreements to 6 ppm. In spring 2009 we improved the aircraft's nadir window and during July and August we made 9 additional 2 hour long flights and measured the atmospheric CO2 absorption and line shapes using the 1572.33 nm CO2 line. Measurements were made at stepped altitudes from 3-13 km over a variety of surface types in Nebraska, Illinois, the SGP ARM site, and near and over the Chesapeake Bay in North Carolina and eastern Virginia. Strong laser signals and clear Co2 line shapes were observed at all altitudes, and some measurements were made through thin clouds. The flights over the ARM site were underflown with in-situ measurements made from the DOE Cessna. Analysis shows that the average signal levels follow predicted values, the altimetry measurements had an uncertainty of about 4 m, and that the average optical line depths follow the number density calculated from in-situ sensor readings. The Oklahoma and east coast flights were coordinated with a LaRC/ITT CO2 lidar on the LaRC UC-12 aircraft, a LaRC in-situ CO2 sensor, and the Oklahoma flights also included a JPL CO2 lidar on a Twin Otter aircraft. More details of the flights, measurements, analysis and scaling to space will be described in the presentation.

  12. Pulsed Airborne Lidar measurements of Atmospheric CO2 Column Absorption and Line Shapes from 3-13 km altitudes

    NASA Astrophysics Data System (ADS)

    Abshire, J. B.; Riris, H.; Allan, G. R.; Weaver, C. J.; Hasselbrack, W. E.; Sun, X.

    2009-12-01

    increasing CO2 line absorptions with altitudes were evident and comparison with in-situ measurements showed agreements to 6 ppm. This spring we improved the aircraft’s nadir window. During July and August 2009 we made 9 additional 2 hour long flights and measured the atmospheric CO2 absorption and line shapes using the 1572.33 nm CO2 line. Measurements were made at stepped altitudes from 3-13 km over a variety of surface types in Nebraska, Illinois, the SGP ARM site, and near and over the Chesapeake Bay in North Carolina and Virginia. Strong laser signals and clear line shapes were observed at all altitudes, and some measurements were made through thin clouds. The flights over the ARM site were underflown with in-situ measurements made from the DOE Cessna. The Oklahoma and east coast flights were coordinated with a LaRC/ITT CO2 lidar on the LaRC UC-12 aircraft, a LaRC in-situ CO2 sensor, and the Oklahoma flights also included a JPL CO2 lidar on a Twin Otter aircraft. Ed Browell and Gary Spiers led the LaRC and JPL teams. More details of the flights, measurements and their analysis will be described in the presentation.

  13. Pulsed Airborne Lidar Measurements of Atmospheric CO2 Column Absorption and Line Shapes from 3-13 km Altitudes

    NASA Technical Reports Server (NTRS)

    Abshire, J. B.; Riris, H.; Allan, G. R.; Weaver, C.; Hasselbrack, W.; Sun, X.

    2009-01-01

    altitudes were evident and comparison with in-situ measurements showed agreements to 6 ppm. This spring we improved the aircraft's nadir window. During July and August 2009 we made 9 additional 2 hour long flights and measured the atmospheric C02 absorption and line shapes using the 1572.33 nm C02 line. Measurements were made at stepped altitudes from 3-13 km over a variety of surface types in Nebraska, Illinois, the SGP ARM site, and near and over the Chesapeake Bay in North Carolina and Virginia. Strong laser signals and clear line shapes were observed at all altitudes, and some measurements were made through thin clouds. The flights over the ARM site were underflown with in-situ measurements made from the DOE Cessna. The Oklahoma and east coast t1ights were coordinated with a LaRC/ITT C02 lidar on the LaRC UC-12 aircraft, a LaRC insitu C02 sensor, and the Oklahoma flights also included a JPL C02 lidar on a Twin Otter aircraft. Ed Browell and Gary Spiers led the LaRC and JPL teams. More details of the t1ights, measurements and analysis will be described in the presentation.

  14. Beyond the single-atom response in absorption line shapes: probing a dense, laser-dressed helium gas with attosecond pulse trains.

    PubMed

    Liao, Chen-Ting; Sandhu, Arvinder; Camp, Seth; Schafer, Kenneth J; Gaarde, Mette B

    2015-04-10

    We investigate the absorption line shapes of laser-dressed atoms beyond the single-atom response, by using extreme ultraviolet (XUV) attosecond pulse trains to probe an optically thick helium target under the influence of a strong infrared (IR) field. We study the interplay between the IR-induced phase shift of the microscopic time-dependent dipole moment and the resonant-propagation-induced reshaping of the macroscopic XUV pulse. Our experimental and theoretical results show that as the optical depth increases, this interplay leads initially to a broadening of the IR-modified line shape, and subsequently, to the appearance of new, narrow features in the absorption line. PMID:25910116

  15. A far wing line shape theory and its application to the water continuum absorption in the infrared region. I

    NASA Technical Reports Server (NTRS)

    Ma, Q.; Tipping, R. H.

    1991-01-01

    The present theory for the continuous absorption that is due to the far-wing contribution of allowed lines is based on the quasistatic approximation for the far wing limit and the binary collision approximation of one absorber molecule and one bath molecule. The validity of the theory is discussed, and numerical results of the water-continuum absorption in the IR region are presented for comparison with experimental data. Good agreement is obtained for both the magnitude and temperature dependence of the absorption coefficients.

  16. Mars Ozone Absorption Line Shapes from Infrared Heterodyne Spectra Applied to GCM-Predicted Ozone Profiles and to MEX/SPICAM Column Retrievals

    NASA Astrophysics Data System (ADS)

    Fast, Kelly Elizabeth; Kostiuk, T.; Hewagama, T.; Livengood, T. A.; Delgado, J. D.; Annen, J.; Lefèvre, F.

    2008-09-01

    We present the application of infrared heterodyne line shapes of ozone on Mars to those produced by radiative transfer modeling of ozone profiles predicted by general circulation models (GCM), and to contemporaneous column abundances measured by Mars Express SPICAM. Ozone is an important tracer of photochemistry Mars’ atmosphere, serving as an observable with which to test predictions of photochemistry-coupled GCMs. Infrared heterodyne spectroscopy at 9.5 μm with spectral resolving power >1,000,000 is the only technique that can directly measure fully-resolved line shapes of Martian ozone features from the surface of the Earth. Measurements were made with Goddard Space Flight Center's Heterodyne Instrument for Planetary Wind And Composition (HIPWAC) at the NASA Infrared Telescope Facility (IRTF) on Mauna Kea, Hawai'i on February 21-24 2008 UT at Ls=35°, on or near the MEX orbital path. The HIPWAC observations were used to test GCM predictions. For example, a GCM-generated ozone profile for 60°N 112°W was scaled so that a radiative transfer calculation of its absorption line shape matched an observed HIPWAC absorption feature at the same areographic position, local time, and season. The RMS deviation of the model from the data was slightly smaller for the GCM-generated profile than for a line shape produced by a constant-with-height profile, even though the total column abundances were the same, showing potential for testing and constraining GCM ozone profiles. The resulting ozone column abundance from matching the model to the HIPWAC line shape was 60% higher than that observed by SPICAM at the same areographic position one day earlier and 2.5 hours earlier in local time. This could be due to day-to-day, diurnal, or north polar region variability, or to measurement sensitivity to the ozone column and its distribution, and these possibilities will be explored. This work was supported by NASA's Planetary Astronomy Program.

  17. Mars Ozone Absorption Line Shapes from Infrared Heterodyne Spectra Applied to GCM-Predicted Ozone Profiles and to MEX/SPICAM Column Retrievals

    NASA Technical Reports Server (NTRS)

    Fast, Kelly E.; Kostiuk, T.; Annen, J.; Hewagama, T.; Delgado, J.; Livengood, T. A.; Lefevre, F.

    2008-01-01

    We present the application of infrared heterodyne line shapes of ozone on Mars to those produced by radiative transfer modeling of ozone profiles predicted by general circulation models (GCM), and to contemporaneous column abundances measured by Mars Express SPICAM. Ozone is an important tracer of photochemistry Mars' atmosphere, serving as an observable with which to test predictions of photochemistry-coupled GCMs. Infrared heterodyne spectroscopy at 9.5 microns with spectral resolving power >1,000,000 is the only technique that can directly measure fully-resolved line shapes of Martian ozone features from the surface of the Earth. Measurements were made with Goddard Space Flight Center's Heterodyne instrument for Planetary Wind And Composition (HIPWAC) at the NASA Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii on February 21-24 2008 UT at Ls=35deg on or near the MEX orbital path. The HIPWAC observations were used to test GCM predictions. For example, a GCM-generated ozone profile for 60degN 112degW was scaled so that a radiative transfer calculation of its absorption line shape matched an observed HIPWAC absorption feature at the same areographic position, local time, and season. The RMS deviation of the model from the data was slightly smaller for the GCM-generated profile than for a line shape produced by a constant-with-height profile, even though the total column abundances were the same, showing potential for testing and constraining GCM ozone-profiles. The resulting ozone column abundance from matching the model to the HIPWAC line shape was 60% higher than that observed by SPICAM at the same areographic position one day earlier and 2.5 hours earlier in local time. This could be due to day-to-day, diurnal, or north polar region variability, or to measurement sensitivity to the ozone column and its distribution, and these possibilities will be explored. This work was supported by NASA's Planetary Astronomy Program.

  18. Theoretical investigation of the broad one-photon absorption line-shape of a flexible symmetric carbazole derivative.

    PubMed

    Liu, Yanli; Cerezo, Javier; Santoro, Fabrizio; Rizzo, Antonio; Lin, Na; Zhao, Xian

    2016-08-17

    The one-photon absorption spectrum of a carbazole derivative has been studied by employing density functional response theory combined with a mixed quantum/classical (QC) approach to simulate the spectral shape. In a first step of our analysis we employed the vertical gradient (VG) vibronic model to investigate the role of Franck-Condon (FC) profiles of the first ten electronic excited states of the system, underlying most of the range of the experimental spectrum. We then focussed on the first six excited states covering the low-energy region of the spectrum, and investigated the effect of inter-state electronic couplings on the spectral shapes within Herzberg-Teller (HT) theory. Furthermore, in order to introduce the broadening effects due to the two inter-ring torsions, we employed a QC approach, adopting VG vibronic models for high-frequency modes and computing the contribution of the torsions to the spectrum from the distribution of the excitation energies along a two-dimensional relaxed potential energy. Finally, we estimated the solvent inhomogeneous broadening by computing the solvent reorganization energy using a polarizable continuum model. Our calculations allow us to obtain a non-phenomenological description of the low-energy part of the spectrum in semi-quantitative agreement with experiment and to dissect the relative importance of solvent, torsional flexibility, FC vibronic progressions, and inter-state couplings in determining its broad spectral shapes and the modulation of its intensity. Our analysis also clearly highlights that the investigated carbazole represents a big challenge for available methodologies due to the existence of many close-lying excited electronic states coupled by internal low-frequency and high-frequency motions and by solvent fluctuations. The study of their impact on the spectra at the HT level is only approximate and more refined treatments would require a fully quantum-dynamical calculation on the manifold of the coupled

  19. Attosecond transient absorption in dense gases: Exploring the interplay between resonant pulse propagation and laser-induced line-shape control

    NASA Astrophysics Data System (ADS)

    Liao, Chen-Ting; Sandhu, Arvinder; Camp, Seth; Schafer, Kenneth J.; Gaarde, Mette B.

    2016-03-01

    We investigate the evolution of extreme ultraviolet (XUV) spectral line shapes in an optically thick helium gas under near-infrared (IR) perturbation. In our experimental and theoretical work, we systematically vary the IR intensity, time-delay, gas density, and IR polarization parameters to study line-shape modifications induced by collective interactions in a regime beyond the single-atom response of a thin, dilute gas. In both experiment and theory, we find that specific features in the frequency-domain absorption profile, and their evolution with propagation distance, can be attributed to the interplay between resonant attosecond pulse propagation and IR-induced phase shifts. Our calculations show that this interplay also manifests itself in the time domain, with the IR pulse influencing the reshaping of the XUV pulse propagating in the resonant medium.

  20. Atlas of Infrared Absorption Lines

    NASA Technical Reports Server (NTRS)

    Park, J. H.

    1977-01-01

    This atlas of infrared absorption line contains absorption line parameters (line strength vs. wavenumber) from 500 to 7000 cm(exp-1) for 15 gases: H2O, CO2, O3, N2O, CO, CH4, O2, SO2, NO, NO2, NH3, HCl, HF, HNO3 and CH3Cl.

  1. Inertial solvent dynamics and the analysis of spectral line shapes: Temperature-dependent absorption spectrum of beta-carotene in nonpolar solvent.

    PubMed

    Burt, Jim A; Zhao, Xihua; McHale, Jeanne L

    2004-03-01

    The influence of solvent dynamics on optical spectra is often described by a stochastic model which assumes exponential relaxation of the time-correlation function for solvent-induced frequency fluctuations. In contrast, theory and experiment suggest that the initial (subpicosecond) phase of solvent relaxation, resulting from inertial motion of the solvent, is a Gaussian function of time. In this work, we employ numerical and analytical calculations to compare the predicted absorption line shapes and the derived solvent reorganization energies obtained from exponential (Brownian oscillator) versus Gaussian (inertial) solvent dynamics. Both models predict motional narrowing as the ratio kappa = Lambda/Delta is increased, where Lambda and Delta are the frequency and variance, respectively, of the solvent-induced frequency fluctuations. However, the motional narrowing limit is achieved at lower values of kappa for the Brownian oscillator model compared to the inertial model. For a given line shape, the derived value of the solvent reorganization energy lambdasolv is only weakly dependent on the solvent relaxation model employed, though different solvent parameters Lambda and Delta are obtained. The two models are applied to the analysis of the temperature-dependent absorption spectrum of beta-carotene in isopentane and CS2. The derived values of lambdasolv using the Gaussian model are found to be in better agreement with the high temperature limit of Delta2/2kBT than are the values obtained using the Brownian oscillator model. In either approach, the solvent reorganization energy is found to increase slightly with temperature as a result of an increase in the variance Delta of the solvent-induced frequency fluctuations. PMID:15268604

  2. Inertial solvent dynamics and the analysis of spectral line shapes: Temperature-dependent absorption spectrum of β-carotene in nonpolar solvent

    NASA Astrophysics Data System (ADS)

    Burt, Jim A.; Zhao, Xihua; McHale, Jeanne L.

    2004-03-01

    The influence of solvent dynamics on optical spectra is often described by a stochastic model which assumes exponential relaxation of the time-correlation function for solvent-induced frequency fluctuations. In contrast, theory and experiment suggest that the initial (subpicosecond) phase of solvent relaxation, resulting from inertial motion of the solvent, is a Gaussian function of time. In this work, we employ numerical and analytical calculations to compare the predicted absorption line shapes and the derived solvent reorganization energies obtained from exponential (Brownian oscillator) versus Gaussian (inertial) solvent dynamics. Both models predict motional narrowing as the ratio κ=Λ/Δ is increased, where Λ and Δ are the frequency and variance, respectively, of the solvent-induced frequency fluctuations. However, the motional narrowing limit is achieved at lower values of κ for the Brownian oscillator model compared to the inertial model. For a given line shape, the derived value of the solvent reorganization energy λsolv is only weakly dependent on the solvent relaxation model employed, though different solvent parameters Λ and Δ are obtained. The two models are applied to the analysis of the temperature-dependent absorption spectrum of β-carotene in isopentane and CS2. The derived values of λsolv using the Gaussian model are found to be in better agreement with the high temperature limit of Δ2/2kBT than are the values obtained using the Brownian oscillator model. In either approach, the solvent reorganization energy is found to increase slightly with temperature as a result of an increase in the variance Δ of the solvent-induced frequency fluctuations.

  3. Pulse shaping with transmission lines

    DOEpatents

    Wilcox, R.B.

    1985-08-15

    A method and apparatus for forming shaped voltage pulses uses passive reflection from a transmission line with nonuniform impedance. The impedance of the reflecting line varies with length in accordance with the desired pulse shape. A high voltage input pulse is transmitted to the reflecting line. A reflected pulse is produced having the desired shape and is transmitted by pulse removal means to a load. Light activated photoconductive switches made of silicon can be utilized. The pulse shaper can be used to drive a Pockels cell to produce shaped optical pulses.

  4. Pulse shaping with transmission lines

    DOEpatents

    Wilcox, Russell B.

    1987-01-01

    A method and apparatus for forming shaped voltage pulses uses passive reflection from a transmission line with nonuniform impedance. The impedance of the reflecting line varies with length in accordance with the desired pulse shape. A high voltage input pulse is transmitted to the reflecting line. A reflected pulse is produced having the desired shape and is transmitted by pulse removal means to a load. Light activated photoconductive switches made of silicon can be utilized. The pulse shaper can be used to drive a Pockels cell to produce shaped optical pulses.

  5. Line, Shape, Color.

    ERIC Educational Resources Information Center

    Greenman, Geri

    2002-01-01

    Describes an art project used with beginning high school art students that teaches them about continuous line drawing. Explains that the students create portraits of themselves, or another student, using glue, black construction paper, and chalk. (CMK)

  6. Do Atoms Really "Emit" Absorption Lines?

    ERIC Educational Resources Information Center

    Brecher, Kenneth

    1991-01-01

    Presents three absorption line sources that enhance student understanding of the phenomena associated with the interaction of light with matter and help dispel the misconception that atoms "emit" absorption lines. Sources include neodymium, food coloring and other common household liquids, and fluorescent materials. (MDH)

  7. Absorption line CW EPR using an amplitude modulated longitudinal field.

    PubMed

    Fedin, Matvey; Gromov, Igor; Schweiger, Arthur

    2004-11-01

    In standard continuous wave electron paramagnetic resonance (CW-EPR) experiments, the first derivative of absorption lines is detected. This type of a line shape is caused by the magnetic field modulation and is usually an undesired feature, since the sensitivity of CW-EPR drastically decreases with increasing linewidth. A new approach is introduced, which allows for the measurement of absorption line EPR spectra in systems with broad inhomogeneous lines. The method makes use of multiple-photon transitions that are induced in spin systems when a transverse microwave and a longitudinal radio frequency field are simultaneously applied. The absorption lines are obtained by using amplitude modulation of the radio frequency field and slight saturation of the spectral lines. The basics of the new approach are discussed and experimental examples are given. PMID:15504685

  8. The determination of absorption cross sections and line profiles in vibrational overtone spectra with the use of intracavity absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Bettermann, H.; Kleist, E.; Kok, R.

    1993-03-01

    This contribution presents quantitative absorption data concerning the 7 th CH overtone stretching vibrations of n-hexane and of methylcyclopentane. The transitions are adapted to Lorentzian and Gaussian line shapes. The bank shape analyses yield the spectral positions, absorption cross sections and linewidths of the investigated transitions.

  9. On the statistics of quasar absorption lines

    NASA Astrophysics Data System (ADS)

    Zuiderwijk, E. J.

    1984-12-01

    The distribution of absorption lines in 13 quasar spectra is analyzed and shown to be fully consistent with the hypothesis of randomly, but not uniformly, distributed absorption features. The analysis by Libby et al. (1984), in which it is claimed that the number of wavelength coincidences among absorption lines in different quasar spectra (as measured in the rest frame of the quasars) is much larger than expected, implying absorbers in the quasars themselves, is totally invalid. Instead, the number of these coincidences is fully commensurate with the expected one on the assumption of randomness.

  10. Nebular UV Absorption Lines in Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Dinerstein, Harriet

    We propose to continue our Cycle 1 program of studying the Lyman and Werner bands of H_2, seen in absorption against the UV continua of planetary nebula central stars, which arise within neutral-molecular envelopes surrounding the ionized gas. These are the pump lines for a fluorescent cascade of near-infrared emission lines which are observed in many planetary nebulae. By observing the UV lines we can probe the chemical and thermal structure of the envelopes, as well as measure molecular column densities and clarify the excitation processes for the infrared lines. In Cycle 1 we were granted time for three targets, one of which was successfully observed shortly before submission of this proposal. Although the data were not yet available for examination, similar target observed by the project team revealed a rich set of H_2 circumstellar absorption features, demonstrating the feasibility of our program. FUSE spectra also include absorption features from atomic species such as O I and C II, which give rise to important far-infrared fine-structure cooling lines that likewise have been observed from planetary nebulae. In Cycle 2, we add as a secondary goal a search for nebular components of the O VI 032, 1038 AA absorption lines, which trace the presence of hot shocked gas, in nebulae with anomalously strong optical recombination lines of ions of oxygen and nitrogen. This will test a plausible hypothesis for the origin of this anomaly.

  11. Non-Voigt Lyalpha Absorption Line Profiles.

    PubMed

    Outram; Carswell; Theuns

    2000-02-01

    Recent numerical simulations have lead to a paradigm shift in our understanding of the intergalactic medium and the loss of a physical justification for Voigt profile fitting of the Lyalpha forest. Many individual lines seen in simulated spectra have significant departures from the Voigt profile, yet could be well fitted by a blend of two or more such lines. We discuss the expected effect on the line profiles due to ongoing gravitational structure formation and Hubble expansion. We develop a method to detect departures from Voigt profiles of the absorption lines in a statistical way and apply this method to simulated Lyalpha forest spectra, confirming that the profiles seen do statistically differ from Voigt profiles. PMID:10622758

  12. Absorption-line measurements of AGN outflows

    NASA Astrophysics Data System (ADS)

    Fields, Dale L.

    Investigations into the elemental abundances in two nearby active galaxies, the narrow-line Seyfert 1 Markarian 1044 and the Seyfert 1 Markarian 279, are reported. Spectra from three space-based observatories HST, FUSE, and CHANDRA, are used to measure absorption lines in material outflowing from the nucleus. I make multi-wavelength comparisons to better convert the ionic column densities into elemental column densities which can then be used to determine abundances (metallicities). Narrow-line Seyfert 1 galaxies are known to have extreme values of a number of properties compared to active galactic nuclei (AGNs) as a class. In particular, emission-line studies have suggested that NLS1s are unusually metal-rich compared to broad-line AGNs of comparable luminosity. To test these suggestions I perform absorption-line studies on the NLS1 Markarian 1044, a nearby and bright AGN. I use lines of H I, C IV, N V, and O VI to properly make the photoionization correction through the software Cloudy and determine abundances of Carbon, Nitrogen and Oxygen. I find two results. The first is that Markarian 1044 has a bulk metallicity greater than five times solar. The second is that the N/C ratio in Markarian 1044 is consistent with a solar mixture. This is in direct contradiction of extrapolations from local H II regions which state N/ C should scale with bulk metallicity. This implies a different enrichment history in Markarian 1044 than in the Galactic disk. I also report discovery of three new low-redshift Lya forest lines with log N HI >= 12:77 in the spectrum of Markarian 1044. This number is consistent with the 2.6 expected Lya forest lines in the path length to Markarian 1044. I also investigate the CHANDRA X-ray spectrum of Markarian 279, a broad-line Seyfert 1. I use a new code, PHASE, to self-consistently model the entire absorption spectrum simultaneously. Using solely the X-ray spectrum I am able to determine the physical parameters of this absorber to a degree only

  13. Line-Shape Transition of Collision Broadened Lines

    NASA Astrophysics Data System (ADS)

    Harde, H.; Katzenellenbogen, N.; Grischkowsky, D.

    1995-02-01

    Using the newly developed technique of THz time-domain spectroscopy, we have measured the far-wing absorption line profile of the ensemble of collision broadened ground state rotational lines of methylchloride vapor out to more than 200 linewidths from resonance, corresponding to frequency offsets as much as 5× the resonant frequency. On these far wings the measured absorption is approximately an order of magnitude less than that predicted by the van Vleck-Weisskopf theory. Our observations show that at higher frequencies a transition occurs from the regime of the van Vleck-Weisskopf theory to the regime of the Lorentz theory.

  14. Ionization states of metallic absorption-line systems in continua of quasars

    NASA Technical Reports Server (NTRS)

    Denda, Kiyomi; Ikeuchi, Satoru

    1993-01-01

    Ionization states of metallic absorption-line systems in continua of quasars (QSO's) are studied, assuming that the metallic lines arise in gaseous halos of high-redshift galaxies in photoionization equilibrium under the background UV radiation, and constraints on the intensity and spectral shape of the UV radiation are obtained. Then a structure of absorbers suitable for all of the metallic absorption line systems are discussed.

  15. Absorption Line Profiles for 39 Rapidly Rotating Stars

    NASA Astrophysics Data System (ADS)

    Stoeckley, T. R.; Carroll, R. W.; Miller, R. D.

    1984-05-01

    Absorption lines of He II, HeI, MgII and other ions have been measured in 169 photographic coude spectra for 39 rapidly rotating B-type stars on the main sequence. All 1500 separate line profiles have been analysed with a procedure of differential corrections by least-squares to yield the following parameters and their error estimates: half-width, central depth, equivalent width and shape parameter. The shape parameter includes Voigt profiles and also `super-Gaussian' and `super-damping' profiles. Up to 15 separately measured line profiles in each star have been superimposed to yield better composite profiles with point scatter as small as 0.5 per cent. In addition, a preliminary value of V sin i is derived for each line of each star, and a mean value (including error bars) is derived for each star. Results are compared and discussed, with reference to forthcoming work incorporating stellar distortion, gravity darkening, and other second-order effects, which will allow determinations of axial inclination and differential rotation of individual stars, using the data sets presented here and elsewhere.

  16. An improved quasistatic line-shape theory: The effects of molecular motion on the line wings

    NASA Technical Reports Server (NTRS)

    Ma, Q.; Tipping, Richard H.

    1994-01-01

    A theory is presented for the modification of the line-shape functions and absorption coefficient due to the breakdown of the quasistatic approximation. This breakdown arises from the effects of molecular motion and increases the absorption in the near wings. Numerical calculations for the high-frequency wing of the nu(sub 3) band of CO2 broadened by Ar are reported and it is shown that these effects are significant near the bandhead. The importance of such corrections in other spectral regions and for other systems is discussed briefly.

  17. Abundances in 8 QSO Absorption Line Systems

    NASA Astrophysics Data System (ADS)

    Lauroesch, James Thomas

    1995-01-01

    An analysis is given of high resolution observations of metal-absorption line systems in the spectra of 4 QSOs made with the echelle spectrograph on the Mayall 4-meter telescope at Kitt Peak National Observatory. High spectral -resolution (9 to 18 km cdot s^{ -1}) observations were obtained for the QSOs S5 0014 + 813, H 0913 + 072, B2 1225 + 317, and HS 1946 + 7658; column densities were derived for the heavy element line systems. Abundances and/or abundance ratios have been determined for 8 systems and a variety of H I column densities in the redshift range 1-3.4 are probed. The systems studies are generally relatively poor in heavy elements, and appear to be similar in heavy element abundances to the gas out of which the Galactic halo stars of similar metallicity formed. Indications of the halo star-abundance sample include the observed ratios of (N/Si), (Al/Si), and (Mn/Fe). The existence of associated H II regions is inferred for a number of damped systems, and it is suggested that the possibly significant amount of gas in H II regions in damped Lyman-alpha systems can be constrained by the comparison of the column densities of O I, N I, N II, Si II, and S II in these systems. The ratio of N(Al II)/N(Al III) is shown to be a poor indicator of the amount of ionized gas in some cases. The abundances of Si as determined from N(Si II)/N(H I) suggest that there is a relatively rapid decrease in abundances in these systems at z _sp{ ~}> 2. Such a decrease in abundances is what would be expected if the galactic (thin) disks did not form before redshifts of z {~} 2. The use of Si II is important, since the weakness of the Zn II lines at low abundances (due to the low relative abundance of Zn compared to elements such as Si) will result in few detections, and in upper limits that are difficult to interpret. The observed drop in abundances is consistent with the decrease in number of heavy-element absorption systems at high redshifts, a result that is found in

  18. Haptic perception of shapes and line drawings

    NASA Astrophysics Data System (ADS)

    Wijntjes, M. W. A.

    2008-09-01

    In this thesis various aspect of haptic perception were studied. The first part of the thesis is mainly concerned with haptic perception of two-dimensional shapes and line drawings. We first studied the angular acuity of two-dimensional shapes an found that the manner of exploration as well as the local and global stimulus properties influence angular acuity. Secondly we studied identification of line drawings by touch. We found that the size of the picture influences identifiability. We also found that observers seem to use a hypothesis driven strategy: on average 23% of the total exploration time was spend on confirming the final hypothesis. In the next chapter on line drawing identification we report a finding that helped to explain why identifying a line drawing by touch is such a difficult task. We found that if observers were not able to identify a picture and were given the opportunity to sketch what they had just felled, in 30% of the cases they could identify their own sketch. A line drawing is easily processed with vision, but if the input is made sequential instead of simultaneous, identification becomes very difficult. This is because the structure of the input has changed and cannot be used to match the internal representations. Similar to sequential vision, if a line drawing is explored by touch, then the structure of the percept is what could be called `one-dimensional'; that is, a sequential description. Observers experience difficulty in mentally switching between these two structures. What can be done is restructuring the representation from sequential to simultaneous by producing a sketch. This explains the recognition-after-sketching-effect. In the second part of the thesis we aspect of haptic perception of three-dimensional curvature. First we studied real, solid shapes and virtual shapes generated by a robotic interface. One of the purposes was to study the contribution of two isolated geometric cues. We found that the surface orientation is a

  19. Relation between size dispersion and line shape in quantum dot ensembles

    NASA Astrophysics Data System (ADS)

    Nikolaev, V. V.; Averkiev, N. S.

    2009-12-01

    We propose a method to model the density of optical transitions, absorption, and differential-absorption spectra of quantum dot ensembles. The developed approach combines physical straightforwardness of the conventional Gaussian-peak modeling with a more preside account of the influence of size dispersion on the line shape of quantum dots.

  20. [A Detection Technique for Gas Concentration Based on the Spectral Line Shape Function].

    PubMed

    Zhou, Mo; Yang, Bing-chu; Tao, Shao-hua

    2015-04-01

    The methods that can rapidly and precisely measure concentrations of various gases have extensive applications in the fields such as air quality analysis, environmental pollution detection, and so on. The gas detection method based on the tunable laser absorption spectroscopy is considered a promising technique. For the infrared spectrum detection techniques, the line shape function of an absorption spectrum of a gas is an important parameter in qualitative and quantitative analysis of a gas. Specifically, how to obtain the line shape function of an absorption spectrum of a gas quickly and accurately is a key problem in the gas detection fields. In this paper we analyzed several existing line shape functions and proposed a method to calculate precisely the line shape function of a gas, and investigated the relation between the gas concentration and the peak value of a line shape function. Then we experimentally measured the absorption spectra of an acetylene gas in the wavelength range of 1,515-1,545 nm with a tunable laser source and a built-in spectrometer. With Lambert-Beer law we calculated the peak values of the line shape function of the gas at the given frequencies, and obtained a fitting curve for the line shape function in the whole waveband by using a computer program. Comparing the measured results with the calculated results of the Voigt function, we found that there was a deviation-between the experimental results and the calculated results. And we found that the measured concentration of the acetylene gas by using the fitting curve of the line shape function was more accurate and compatible with the actual situation. Hence, the empirical formula for the line shape function obtained from the experimental results would be more suitable for the concentration measurement of a gas. As the fitting curve for the line shape function of the acetylene gas has been deduced from the experiment, the corresponding peak values of the spectral lines can be

  1. Influence of line interference on the vibration-rotation band shapes

    NASA Astrophysics Data System (ADS)

    Bulanin, M. O.; Dokuchaev, A. B.; Tonkov, M. V.; Filippov, N. N.

    1984-06-01

    The shapes of the CO, v3 CO2 and v3 N2O fundamental vibration-rotation bands have been studied at various temperatures and in the presence of several perturbing gases. Also the half-widths of CO vibration-rotation lines have been measured at 78 K. In the region of line wings, the measured absorption coefficients deviate from those given by the superposition of Lorentzian profiles. These deviations are explained by the collision-induced line interference that causes redistribution of absorption inside the band. A theory of line mixing is formulated which is based on Markov approximation and on the strong collision model. Simple analytical expressions are obtained for the band shape. The computed shapes are in satisfactory agreement with the experimental results. The deviations from the Lorentz absorption observed in pure CO and in CO-N2 at low temperature are partially ascribed to the formation of van der Waals dimers.

  2. Infra-red absorption lines by molecules in grain mantles

    NASA Astrophysics Data System (ADS)

    Hagen, W.; Allamandola, L. J.; Greenberg, J. M.

    1980-06-01

    The laboratory spectrum of a solid mixture of H2O, CO, CH3OH, and NH3 at a temperature of 10 K reproduces the shape and peak positions of interstellar features. It is shown that the broad absorption features evident in the MIR spectra of some astronomical objects associated with interstellar dust can be explained by absorptions of molecules in grain mantles.

  3. Majorana approach to the stochastic theory of line shapes

    NASA Astrophysics Data System (ADS)

    Komijani, Yashar; Coleman, Piers

    2016-08-01

    Motivated by recent Mössbauer experiments on strongly correlated mixed-valence systems, we revisit the Kubo-Anderson stochastic theory of spectral line shapes. Using a Majorana representation for the nuclear spin we demonstrate how to recast the classic line-shape theory in a field-theoretic and diagrammatic language. We show that the leading contribution to the self-energy can reproduce most of the observed line-shape features including splitting and line-shape narrowing, while the vertex and the self-consistency corrections can be systematically included in the calculation. This approach permits us to predict the line shape produced by an arbitrary bulk charge fluctuation spectrum providing a model-independent way to extract the local charge fluctuation spectrum of the surrounding medium. We also derive an inverse formula to extract the charge fluctuation from the measured line shape.

  4. The relativistic Doppler broadening of the line absorption profile

    NASA Astrophysics Data System (ADS)

    Kichenassamy, S.; Krikorian, R.; Nikogosian, A.

    1982-06-01

    The classical results of Doppler broadening of the line absorption profile are generalized to a relativistic gas in thermal equilibrium by taking into account the relativistic variance of the volume absorption coefficients of the gas, as derived by L. H. Thomas. This variance produces a small correction, even in the non-relativistic approximation.

  5. The Hubble Space Telescope quasar absorption line key project. II - Data calibration and absorption-line selection

    NASA Technical Reports Server (NTRS)

    Schneider, Donald P.; Hartig, George F.; Jannuzi, Buell T.; Kirhakos, Sofia; Saxe, David H.; Weymann, Ray J.; Bahcall, John N.; Bergeron, Jacqueline; Boksenberg, Alec; Sargent, W. L. W.

    1993-01-01

    We present the observational and data processing aspects of the Hubble Space Telescope Quasar Absorption Line Key Project. Topics discussed include the observational technique, calibration of the data, software that simulates the data, the automated procedure used to identify and characterize the absorption features, and the determination of the sensitivity limits of the survey.

  6. Active Galactic Nuclei Probed by QSO Absorption Lines

    NASA Astrophysics Data System (ADS)

    Misawa, Toru

    2007-07-01

    Quasars are the extremely bright nuclei found in about 10% of galaxies. A variety of absorption features (known collectively as quasar absorption lines) are detected in the rest-frame UV spectra of these objects. While absorption lines that have very broad widths originate in gas that is probably physocally related to the quasars, narrow absorption lines (NALs) were thought to arise in galaxies and/or in the intter-alacttic medium between the quasars and us. Using high-resolution spectra of quasars, it is found that a substantial fraction of NALs arise in gas in the immediate vicinity of the quasars. A dramatically variable, moderately-broad absorption line in the spectrum of the quasar HS 1603+3820l is also found. The variability of this line is monitored in a campaign with Subaru telescope. These observational results are compared to models for outflows from the quasars, specifically, models for accretion disk winds and evaporating obscuring tori. It is quite important to determine the mechanism of outflow because of its cosmological implications. The outflow could expel angular momentum from the accretion disk and enable quasars to accrete and shine. In addition, the outflow may also regulate star formation in the early stages of the assembly of the host galaxy and enrich the interstellar and intergalactic medium with metals.

  7. Broad Absorption Line Quasar catalogues with Supervised Neural Networks

    NASA Astrophysics Data System (ADS)

    Scaringi, Simone; Cottis, Christopher E.; Knigge, Christian; Goad, Michael R.

    2008-12-01

    We have applied a Learning Vector Quantization (LVQ) algorithm to SDSS DR5 quasar spectra in order to create a large catalogue of broad absorption line quasars (BALQSOs). We first discuss the problems with BALQSO catalogues constructed using the conventional balnicity and/or absorption indices (BI and AI), and then describe the supervised LVQ network we have trained to recognise BALQSOs. The resulting BALQSO catalogue should be substantially more robust and complete than BI-or AI-based ones.

  8. Broad Absorption Line Quasar catalogues with Supervised Neural Networks

    SciTech Connect

    Scaringi, Simone; Knigge, Christian; Cottis, Christopher E.; Goad, Michael R.

    2008-12-05

    We have applied a Learning Vector Quantization (LVQ) algorithm to SDSS DR5 quasar spectra in order to create a large catalogue of broad absorption line quasars (BALQSOs). We first discuss the problems with BALQSO catalogues constructed using the conventional balnicity and/or absorption indices (BI and AI), and then describe the supervised LVQ network we have trained to recognise BALQSOs. The resulting BALQSO catalogue should be substantially more robust and complete than BI-or AI-based ones.

  9. Line-by-line pulse shaping control for optical arbitrary waveform generation.

    PubMed

    Jiang, Z; Leaird, D E; Weiner, A M

    2005-12-12

    We demonstrate a fundamental operation for generating complex waveforms in the optical domain - line-by-line pulse shaping control for optical arbitrary waveform generation (O-AWG). Independent manipulation of the spectral amplitude and phase of individual lines from a mode-locked frequency comb, or spectral line-by-line pulse shaping, leads to synthesis of user-specified ultrafast optical waveforms with unprecedented control. Coupled with recent advances in frequency stabilized mode-locked lasers, line-by-line pulse shaping control should have significant impact to fields drawing upon developments in the field of ultrafast science. PMID:19503258

  10. The low-ion QSO absorption-line systems

    SciTech Connect

    Lanzetta, K.M.

    1988-01-01

    Various techniques are used to investigate the class of QSO absorption-line systems that exhibit low-ion absorption lines. Four separate investigations are conducted as follows: Spectroscopy of 32 QSOs at red wavelengths is presented and used to investigate intermediate-redshift MgII absorption. A total of 22 Mg II doublets are detected, from which properties of the Mg II absorbers are derived. Marginal evidence for intrinsic evolution of the number density of the Mg II absorbers with redshift is found. The data are combined with previous observations of C IV and C II seen in the same QSOs at blue wavelengths, and the properties of Mg II- and C IV-selected systems are compared. A sample is constructed of 129 QSOs for which are available published data suitable for detecting absorption-line systems that are optically thick to Lyman continuum radiation. A total of 53 such Lyman-limit systems are found, from which properties of the Lyman-limit systems are derived. It is found that the rate of incidence of the systems does not strongly evolved with redshift. This result is contrasted with the evolution found previously for systems selected on the basis of Mg II absorption. Spectroscopy at red wavelengths of eight QSOs with known damped Ly{alpha} absorption systems is presented. Spectroscopic and spectrophotometric observations aimed at detecting molecular hydrogen and dust in the z = 2.796 damped Ly{alpha} absorber toward Q1337 + 113 are presented.

  11. Extreme Variability in a Broad Absorption Line Quasar

    NASA Astrophysics Data System (ADS)

    Stern, Daniel; Graham, Matthew; Arav, Nahum; Djorgovski, Stanislav G.; Chamberlain, Carter; Barth, Aaron J.; Donalek, Ciro; Drake, Andrew J.; Glikman, Eilat; Jun, Hyunsung David; Mahabal, Ashish A.; Steidel, Charles C.

    2016-01-01

    We report on extreme spectral variability seen in a broad absorption line quasar over the past decade, initially identified from the Catalina Real-time Transient Survey (CRTS). Photometrically, the source had a visual magnitude of V = 17.3 between 2002 and 2008. Then, over the following 5 years, the source slowly brightened by approximately one magnitude, to V = 16.2. A combination of archival and newly acquired spectra reveal the source to be an iron low-ionization broad absorption line (Fe-LoBAL) quasar with extreme changes in its absorption spectrum. Some absorption features completely disappear over the 9 years of optical spectra, while other features remain essentially unchanged. Absorption systems separated by several 1000 km/s in velocity show coordinated changes in the depths of their troughs, correlated with the flux changes. Therefore, we interpret the variability in the absorption troughs to be due to changes in photoionization, rather than due to motion of material into our line of sight. This source highlights the sort of rare transition objects that astronomy will now be finding through dedicated time domain surveys.

  12. Apodization Control of Line Shape in Spectrometer

    NASA Technical Reports Server (NTRS)

    Pires, Antonio; Niple, Edward; Evans, Nathan L.

    1987-01-01

    Kaiser-Bessel apodization function reduces unwanted sidebands. Report discusses apodization in Fourier-transform spectrometer (FTS) for Advanced Moisture and Temperature Sounder (AMTS). Purpose of apodization in instrument to control shape of spectrum in wavenumber space to keep radiation at other wavelengths in passband of spectrometer out of AMTS wavenumber channel.

  13. Line shape in a free-jet hypersonic expansion investigated by cavity ring-down spectroscopy and computational fluid dynamics

    NASA Astrophysics Data System (ADS)

    Suas-David, Nicolas; Kulkarni, Vinayak; Benidar, Abdessamad; Kassi, Samir; Georges, Robert

    2016-08-01

    Experiments are carried out for spectroscopic studies using hypersonic jet of carbon monoxide seeded in argon as a carrier gas. Probing of this jet using cavity ring-down spectroscopy revealed a double peak structure for various absorption lines. Flow field simulation using computational fluid dynamics is used to understand the shape of such lines integrated over line of sight. Absorption contribution from warmer non-isentropic part of the jet, owing to its transverse velocity variation, is found responsible for those line shapes.

  14. Temperature-insensitive laser frequency locking near absorption lines

    NASA Astrophysics Data System (ADS)

    Kostinski, Natalie; Olsen, Ben A.; Marsland, Robert; McGuyer, Bart H.; Happer, William

    2011-03-01

    Combined magnetically induced circular dichroism and Faraday rotation of an atomic vapor are used to develop a variant of the dichroic atomic vapor laser lock that eliminates lock sensitivity to temperature fluctuations of the cell. Operating conditions that eliminate first-order sensitivity to temperature fluctuations can be determined by low-frequency temperature modulation. This temperature-insensitive gyrotropic laser lock can be accurately understood with a simple model, that is in excellent agreement with observations in potassium vapor at laser frequencies in a 2 GHz range about the 770.1 nm absorption line. The methods can be readily adapted for other absorption lines.

  15. Temperature-insensitive laser frequency locking near absorption lines

    SciTech Connect

    Kostinski, Natalie; Olsen, Ben A.; Marsland, Robert III; McGuyer, Bart H.; Happer, William

    2011-03-15

    Combined magnetically induced circular dichroism and Faraday rotation of an atomic vapor are used to develop a variant of the dichroic atomic vapor laser lock that eliminates lock sensitivity to temperature fluctuations of the cell. Operating conditions that eliminate first-order sensitivity to temperature fluctuations can be determined by low-frequency temperature modulation. This temperature-insensitive gyrotropic laser lock can be accurately understood with a simple model, that is in excellent agreement with observations in potassium vapor at laser frequencies in a 2 GHz range about the 770.1 nm absorption line. The methods can be readily adapted for other absorption lines.

  16. AFGL atmospheric absorption line parameters compilation - 1982 edition

    NASA Technical Reports Server (NTRS)

    Rothman, L. S.; Gamache, R. R.; Barbe, A.; Goldman, A.; Gillis, J. R.; Brown, L. R.; Toth, R. A.; Flaud, J.-M.; Camy-Peyret, C.

    1983-01-01

    The latest edition of the AFGL atmospheric absorption line parameters compilation for the seven most active infrared terrestrial absorbers is described. Major modifications to the atlas for this edition include updating of water-vapor parameters from 0 to 4300 per cm, improvements to line positions for carbon dioxide, substantial modifications to the ozone bands in the middle to far infrared, and improvements to the 7- and 2.3-micron bands of methane. The atlas now contains about 181,000 rotation and vibration-rotation transitions between 0 and 17,900 per cm. The sources of the absorption parameters are summarized.

  17. Dispersion studies of the 22 GHz water vapor line shape. II - Instrumental correction.

    NASA Technical Reports Server (NTRS)

    Dillon, T. A.; Liebe, H. J.

    1971-01-01

    Anomalies in the resonance dispersion of the pressure-broadened water vapor line at a frequency of 22.235 GHz are resolved. The pressure-scanning differential-refraction spectrometer gives rise to a signal enhancement as the line center moves within the width of the dispersion discriminator. Resonance absorption prevents the frequency of peak transmitted power from coinciding with the resonance condition of zero phase. The results reported for the 23.6 GHz rotational line of ethylene oxide show a Lorentzian molecular line shape.

  18. PREFACE: XXI International Conference on Spectral Line Shapes (ICSLS 2012)

    NASA Astrophysics Data System (ADS)

    Devdariani, Alexander Z.

    2012-12-01

    The 21st International Conference on Spectral Line Shapes, ICSLS, was held in the historic main building of St Petersburg State University (St. Petersburg, Russia) on 3-9 June 2012. The event continued the tradition started in 1978 in Meudon Observatory in Paris. Representatives of line shape physics have since met every two years in different locations in Europe and North America. The most recent events were held in St John's, Newfoundland, Canada (2010), Valladolid, Spain (2008), and Auburn, AL (USA). Traditionally, the conferences consider experimental and theoretical issues of studying spectral line shapes, diagnostic utilization of spectral line profiles observed in absorption, emission or scattering of electromagnetic radiation by atoms, molecules, and clusters in different environments, including neutral environments, laboratory low and fusion plasmas, astrophysical conditions, and planetary atmospheres. The Conference was attended by over 100 professionals from Europe, Asia, America, Africa and New Zealand. The conference program was put together in such a way so as to exclude any parallel sessions. Five afternoon sessions featured 19 invited talks and 20 oral contributions, and two evening sessions offered 61 poster presentations, including post-deadline posters. This setup allowed for a relaxed and unhurried discussion of results and facilitated productive networking. The invited talks were selected by recommendation of members of the International Scientific Committee. The Organizers would like to thank all the members of the International Scientific Committee for their proposals on the agenda and their valuable advice. When considering candidates for oral contributions, the organizers took into account the suggestions and preferences of potential conference participants. When selecting the theses of poster presentations, the organizers focused on the topics in line with the theme of the conference and studies with well-formulated results. It must be

  19. Intermediate-redshift galaxy halos - Results from QSO absorption lines

    SciTech Connect

    Lanzetta, K.M.; Bowen, D. Royal Greenwich Observatory, Cambridge )

    1990-07-01

    For a sample of Mg II-selected QSO absorption-line systems for which the absorbing galaxies have been successfully identified, the rest-frame equivalent widths of the Mg II 2796-A absorption lines are examined as a function of the known impact parameters between the background QSOs and the absorbing galaxies. There appears to exist a relationship between the equivalent widths and the impact parameters, in the sense that larger equivalent widths occur at smaller impact parameters. No trend of the doublet ratio is found with impact parameter, and neither the equivalent widths nor the doublet ratios are correlated with the absolute luminosities or redshifts of the absorbing galaxies. These results apparently indicate that the main factor that determines the equivalent width of a particular absorption system is the impact parameter between the background QSO and the absorbing galaxy. 32 refs.

  20. Interstellar MG II Absorption Lines from Low-Redshift Galaxies

    NASA Astrophysics Data System (ADS)

    Bowen, David V.; Blades, J. Chris; Pettini, Max

    1995-08-01

    We have used the GHRS aboard HST to search for interstellar Mg II 2796, 2803 absorption from the disks and halos of 17 low-redshift galaxies, using as probes QSOs and extragalactic supernovae whose sight lines pass close to, or through, intervening galaxies. The galaxies studied are of diverse morphological type, reside in different environments, and lie at separations of p' ≃ 2-113 h-1 kpc from a QSO line of sight. Ten of 11 galaxies at separations 31-113 h-1 kpc show no absorption to equivalent width limits of W(λ2796) <40-90 mÅ, which corresponds to N(Mg II) ≃1-4 × 1012 cm-2. Six galaxies lie at p' ≤ 9 kpc, and of these, four (NGC 4319, the LMC, M81, and the Milky Way) show absorption. Two early-type galaxies (NGC 1380 and Leo I) show no absorption at p' < 9 kpc: these nondetections are surprising because the separations are small and point to the possibility that the existence of extended absorbing halos may be a function of galaxy type. All of the galaxies which produce absorption are plausibly members of interacting systems. For absorbing galaxies probed below 9 kpc, the sight line passes within the optical radius of the galaxy, where the interstellar medium (ISM) is expected to have a high covering factor, and we do not attribute the absorption to the interactions. However, we do find that the environment of the absorbing galaxies affects the characteristics of the absorption detected the strength of lines, the complexity of line components, the ionization state of the gas and we warn of the dangers inherent in constructing models of generic halos based on statistical properties of QSO absorption-line surveys. Our data suggest that the covering factor of Mg II absorption is high for galaxies within ≍10 kpc, but very small beyond ≍30 h-1 kpc, a result consistent with the size found of Mg II halos deduced for galaxies at redshifts z > 0.2. The low-redshift galaxies observed in this study which show Mg II absorption are probably drawn from the same

  1. Fine-structure Constancy Measurements in QSO Absorption Lines

    NASA Astrophysics Data System (ADS)

    Whitmore, Jonathan B.

    2013-01-01

    The ESO Large Programme 185.A-0745 has awarded 10 nights on the VLT-UVES spectrograph for the study of the possible variation in the fine structure constant. We will present the fine-structure measurements from two lines of sight and several absorption systems. We will also present updated systematic error analyses.

  2. SPECTROPOLARIMETRY OF RADIO-SELECTED BROAD ABSORPTION LINE QUASARS

    SciTech Connect

    DiPompeo, M. A.; Brotherton, M. S.; Becker, R. H.; Gregg, M. D.; Tran, H. D.; White, R. L.; Laurent-Muehleisen, S. A.

    2010-07-15

    We report spectropolarimetry of 30 radio-selected broad absorption line (BAL) quasars with the Keck Observatory, 25 from the sample of Becker et al. Both high- and low-ionization BAL quasars are represented, with redshifts ranging from 0.5 to 2.5. The spectropolarimetric properties of radio-selected BAL quasars are very similar to those of radio-quiet BAL quasars: a sizeable fraction (20%) shows large continuum polarization (2%-10%) usually rising toward short wavelengths; emission lines are typically less polarized than the continuum; and absorption line troughs often show large polarization jumps. There are no significant correlations between polarization properties and radio properties, including those indicative of system orientation, suggesting that BAL quasars are not simply normal quasars seen from an edge-on perspective.

  3. A SURVEY OF ALKALI LINE ABSORPTION IN EXOPLANETARY ATMOSPHERES

    SciTech Connect

    Jensen, Adam G.; Redfield, Seth; Endl, Michael; Cochran, William D.; Koesterke, Lars; Barman, Travis S. E-mail: sredfield@wesleyan.edu E-mail: wdc@astro.as.utexas.edu E-mail: barman@lowell.edu

    2011-12-20

    We obtained over 90 hr of spectroscopic observations of four exoplanetary systems with the Hobby-Eberly Telescope. Observations were taken in transit and out of transit, and we analyzed the differenced spectra-i.e., the transmission spectra-to inspect it for absorption at the wavelengths of the neutral sodium (Na I) doublet at {lambda}{lambda}5889, 5895 and neutral potassium (K I) at {lambda}7698. We used the transmission spectrum at Ca I {lambda}6122-which shows strong stellar absorption but is not an alkali metal resonance line that we expect to show significant absorption in these atmospheres-as a control line to examine our measurements for systematic errors. We use an empirical Monte Carlo method to quantify these systematic errors. In a reanalysis of the same data set using a reduction and analysis pipeline that was derived independently, we confirm the previously seen Na I absorption in HD 189733b at a level of (- 5.26 {+-} 1.69) Multiplication-Sign 10{sup -4} (the average value over a 12 A integration band to be consistent with previous authors). Additionally, we tentatively confirm the Na I absorption seen in HD 209458b (independently by multiple authors) at a level of (- 2.63 {+-} 0.81) Multiplication-Sign 10{sup -4}, though the interpretation is less clear. Furthermore, we find Na I absorption of (- 3.16 {+-} 2.06) Multiplication-Sign 10{sup -4} at <3{sigma} in HD 149026b; features apparent in the transmission spectrum are consistent with real absorption and indicate this may be a good target for future observations to confirm. No other results (Na I in HD 147506b and Ca I and K I in all four targets) are significant to {>=}3{sigma}, although we observe some features that we argue are primarily artifacts.

  4. Oscillator strength measurements of atomic absorption lines from stellar spectra

    NASA Astrophysics Data System (ADS)

    Lobel, Alex

    2011-05-01

    Herein we develop a new method to determine oscillator strength values of atomic absorption lines with state-of-the-art detailed spectral synthesis calculations of the optical spectrum of the Sun and of standard spectral reference stars. We update the log(gf) values of 911 neutral lines observed in the KPNO-FTS flux spectrum of the Sun and high-resolution echelle spectra (R = 80 000) of Procyon (F5 IV-V) and Eps Eri (K2 V) observed with large signal-to-noise (S/N) ratios of 2000 using the new Mercator-Hermes spectrograph at La Palma Observatory (Spain). We find for 483 Fe I, 85 Ni I, and 51 Si I absorption lines in the sample a systematic overestimation of the literature log(gf) values with central line depths below 15%. We employ a curve-of-growth analysis technique to test the accuracy of the new oscillator strength values and compare calculated equivalent line widths to the Moore, Minnaert, and Houtgast atlas of the Sun. The online SpectroWeb database at http://spectra.freeshell.org interactively displays the observed and synthetic spectra and provides the new log(gf) values together with important atomic line data. The graphical database is under development for stellar reference spectra of every spectral sub-class observed with large spectral resolution and S/N ratios.

  5. Spectral Line Shapes as a Diagnostic Tool in Magnetic Fusion

    SciTech Connect

    Stamm, R; Capes, H; Demura, A; Godbert-Mouret, L; Koubiti, M; Marandet, Y; Mattioli, M; Rosato, J; Rosmej, F; Fournier, K B

    2006-07-22

    Spectral line shapes and intensities are used for obtaining information on the various regions of magnetic fusion devices. Emission from low principal quantum numbers of hydrogen isotopes is analyzed for understanding the complex recycling mechanism. Lines emitted from high principal quantum numbers of hydrogen and helium are dominated by Stark effect, allowing an electronic density diagnostic in the divertor. Intensities of lines emitted by impurities are fitted for a better knowledge of ion transport in the confined plasma.

  6. Pressure dependence of Se absorption lines in AlSb

    SciTech Connect

    Hsu, L. |; Haller, E.E.; Ramdas, A.K.

    1996-09-01

    Using far infrared absorption spectroscopy, the authors have investigated electronic transition spectra of Se donors in AlSb as a function of hydrostatic pressure. At least two distinct ground to bound excited state transition lines, which depend quadratically on the pressure, can be seen. At pressures between 30 and 50 kbar, evidence of an anti-crossing between one of the electronic transitions and a peak which they attribute to the 2 zone center LO phonon mode can be seen.

  7. The missing UV absorption lines of NGC 4151

    NASA Technical Reports Server (NTRS)

    Leech, K. J.; Penston, M. V.; Snijders, M. A. J.; Ward, M. J.; Gull, T. R.

    1990-01-01

    Near simultaneous high dispersion long and short wavelength International Ultraviolet Explorer (IUE) observations of the Seyfert galaxy NGC 4151 are discussed. Previous observations revealed a narrow absorption system in Mg II not present in Ly alpha or C IV. The new observations confirm the presence of this system in Mg II and its absence in the other lines. Possible reasons for this are discussed. Future Hubble Space Telescope studies of NGC 4151 are discussed.

  8. Interstellar absorption lines in the galaxy NGC 1705

    SciTech Connect

    York, D.G.; Caulet, A.; Rybski, P.M.; Gallagher, J.S.; Blades, J.C. Lowell Observatory, Flagstaff, AZ Space Telescope Science Institute, Baltimore, MD )

    1990-03-01

    The possibility is considered, and shown to be plausible, that the strong C IV and Si IV absorption lines in low-resolution ultraviolet spectra of gas-rich dwarf galaxies are primarily interstellar, not stellar as has been supposed. The argument is based on analogies with H II regions in the Local Group, on low-resolution equivalent width measurements of gas-rich dwarf galaxies from the literature and on high-resolution UV spectra of NGC 1705. 48 refs.

  9. Interstellar absorption lines in the galaxy NGC 1705

    NASA Technical Reports Server (NTRS)

    York, Donald G.; Caulet, Adeline; Rybski, Paul M.; Gallagher, John S.; Blades, J. Chris

    1990-01-01

    The possibility is considered, and shown to be plausible, that the strong C IV and Si IV absorption lines in low-resolution ultraviolet spectra of gas-rich dwarf galaxies are primarily interstellar, not stellar as has been supposed. The argument is based on analogies with H II regions in the Local Group, on low-resolution equivalent width measurements of gas-rich dwarf galaxies from the literature and on high-resolution UV spectra of NGC 1705.

  10. Study of the Auger line shape of polyethylene and diamond

    NASA Technical Reports Server (NTRS)

    Dayan, M.; Pepper, S. V.

    1984-01-01

    The KVV Auger electron line shapes of carbon in polyethylene and diamond have been studied. The spectra were obtained in derivative form by electron beam excitation. They were treated by background subtraction, integration and deconvolution to produce the intrinsic Auger line shape. Electron energy loss spectra provided the response function in the deconvolution procedure. The line shape from polyethylene is compared with spectra from linear alkanes and with a previous spectrum of Kelber et al. Both spectra are compared with the self-convolution of their full valence band densities of states and of their p-projected densities. The experimental spectra could not be understood in terms of existing theories. This is so even when correlation effects are qualitatively taken into account account to the theories of Cini and Sawatzky and Lenselink.

  11. Electron line shape of the KATRIN monitor spectrometer

    NASA Astrophysics Data System (ADS)

    Slezák, M.; Bauer, S.; Dragoun, O.; Erhard, M.; Schlösser, K.; Špalek, A.; Vénos, D.; Zbořil, M.

    2013-12-01

    Conversion electrons emitted from 83mKr implanted into a solid substrate will serve as a powerful tool for monitoring of the energy scale stability in the KATRIN neutrino experiment. An appropriate description of the conversion line shape is essential to determine the energy of the emitted electrons. It is shown that the Doniach-Šunjić line shape gives a significantly better fit to the conversion electron spectra than the previously used double Voigt model. The electron spectra were obtained with the KATRIN MAC-E filter monitor spectrometer.

  12. Universal Representation of the H-like Spectral Line Shapes

    NASA Astrophysics Data System (ADS)

    Bureyeva, L.

    2009-05-01

    A universal approach for the calculation of Rydberg atom line shapes in plasmas is developed. It is based on analytical formulas for the intensity distribution in radiation transitions n→n' between highly excited atomic states with large values of principal quantum numbers n, n'≫1, with Δ n = n-n'≪n, and on the Frequency Fluctuation Model (FFM) to account of electron and ion thermal motion effects. The theory allows to describe a transition from the static to the impact broadening domains for every hydrogen spectral line. A new approach to extremely fast line shape calculations with account of charged particle dynamic effect was proposed. The approach is based on the close analogy between the static-impact broadening transition in the spectral line shape theory and the Doppler-Lorentz broadening in the Dicke narrowing effect theory. The precision of the new approach was tested by the comparison of hydrogen-alpha and beta line shapes calculations with the FFM results. The excellent agreement was discovered, the computer time decreased two orders of magnitudes as compared with the FFM.

  13. PREFACE: XXI International Conference on Spectral Line Shapes (ICSLS 2012)

    NASA Astrophysics Data System (ADS)

    Devdariani, Alexander Z.

    2012-12-01

    The 21st International Conference on Spectral Line Shapes, ICSLS, was held in the historic main building of St Petersburg State University (St. Petersburg, Russia) on 3-9 June 2012. The event continued the tradition started in 1978 in Meudon Observatory in Paris. Representatives of line shape physics have since met every two years in different locations in Europe and North America. The most recent events were held in St John's, Newfoundland, Canada (2010), Valladolid, Spain (2008), and Auburn, AL (USA). Traditionally, the conferences consider experimental and theoretical issues of studying spectral line shapes, diagnostic utilization of spectral line profiles observed in absorption, emission or scattering of electromagnetic radiation by atoms, molecules, and clusters in different environments, including neutral environments, laboratory low and fusion plasmas, astrophysical conditions, and planetary atmospheres. The Conference was attended by over 100 professionals from Europe, Asia, America, Africa and New Zealand. The conference program was put together in such a way so as to exclude any parallel sessions. Five afternoon sessions featured 19 invited talks and 20 oral contributions, and two evening sessions offered 61 poster presentations, including post-deadline posters. This setup allowed for a relaxed and unhurried discussion of results and facilitated productive networking. The invited talks were selected by recommendation of members of the International Scientific Committee. The Organizers would like to thank all the members of the International Scientific Committee for their proposals on the agenda and their valuable advice. When considering candidates for oral contributions, the organizers took into account the suggestions and preferences of potential conference participants. When selecting the theses of poster presentations, the organizers focused on the topics in line with the theme of the conference and studies with well-formulated results. It must be

  14. VERY LARGE TELESCOPE SPECTROPOLARIMETRY OF BROAD ABSORPTION LINE QSOs

    SciTech Connect

    DiPompeo, M. A.; Brotherton, M. S.; De Breuck, C.

    2011-03-15

    We present spectropolarimetry of 19 confirmed and four possible bright, southern broad absorption line (BAL) quasars from the European Southern Observatory Very Large Telescope. A wide range of redshifts is covered in the sample (from 0.9 to 3.4), and both low- and high-ionization quasars are represented, as well as radio-loud and radio-quiet BALQSOs. We continue to confirm previously established spectropolarimetric properties of BALQSOs, including the generally rising continuum polarization with shorter wavelengths and comparatively large fraction with high broadband polarization (6 of 19 with polarizations >2%). Emission lines are polarized less than or similar to the continuum, except in a few unusual cases, and absorption troughs tend to have higher polarizations. A search for correlations between polarization properties has been done, identifying two significant or marginally significant correlations. These are an increase in continuum polarization with decreasing optical luminosity (increasing absolute B magnitude) and decreasing C IV emission-line polarization with increased continuum polarization.

  15. Common lines in the rest-frame absorption-line spectra of QSOs?

    NASA Astrophysics Data System (ADS)

    Varshni, Y. P.; Singh, D.

    1985-02-01

    Libby et al. (1984) have studied the absorption-line data for 13 QSOs in the rest-frames of the QSOs. It is shown that the number of groups in which 5 lines or more lie within a wavelength interval of 1.0 Å found by these authors is insignificantly different from that that would be expected from chance coincidences. Consequently, there is no evidence that the rest-frame wavelengths at which these groups occur have any special significance.

  16. High-dispersion absorption-line spectroscopy of AE Aqr

    NASA Astrophysics Data System (ADS)

    Echevarría, J.; Smith, Robert Connon; Costero, R.; Zharikov, S.; Michel, R.

    2008-07-01

    High-dispersion time-resolved spectroscopy of the unique magnetic cataclysmic variable AE Aqr is presented. A radial velocity analysis of the absorption lines yields K2 = 168.7 +/- 1kms-1. Substantial deviations of the radial velocity curve from a sinusoid are interpreted in terms of intensity variations over the secondary star's surface. A complex rotational velocity curve as a function of orbital phase is detected which has a modulation frequency of twice the orbital frequency, leading to an estimate of the binary inclination angle that is close to 70°. The minimum and maximum rotational velocities are used to indirectly derive a mass ratio of q = 0.6 and a radial velocity semi-amplitude of the white dwarf of K1 = 101 +/- 3kms-1. We present an atmospheric temperature indicator, based on the absorption-line ratio of FeI and CrI lines, whose variation indicates that the secondary star varies from K0 to K4 as a function of orbital phase. The ephemeris of the system has been revised, using more than 1000 radial velocity measurements, published over nearly five decades. From the derived radial velocity semi-amplitudes and the estimated inclination angle, we calculate that the masses of the stars are M1 = 0.63 +/- 0.05Msolar M2 = 0.37 +/- 0.04Msolar, and their separation is a = 2.33 +/- 0.02Rsolar. Our analysis indicates the presence of a late-type star whose radius is larger, by a factor of nearly 2, than the radius of a normal main-sequence star of the same mass. Finally, we discuss the possibility that the measured variations in the rotational velocity, temperature and spectral type of the secondary star as functions of orbital phase may, like the radial velocity variations, be attributable to regions of enhanced absorption on the star's surface.

  17. High Precision Assembly Line Synthesis for Molecules with Tailored Shapes

    PubMed Central

    Burns, Matthew; Essafi, Stephanie; Bame, Jessica R.; Bull, Stephanie P.; Webster, Matthew P.; Balieu, Sebastien; Dale, James W.; Butts, Craig P.; Harvey, Jeremy N.; Aggarwal, Varinder K.

    2014-01-01

    Molecular assembly lines, where molecules undergo iterative processes involving chain elongation and functional group manipulation are hallmarks of many processes found in Nature. We have sought to emulate Nature in the development of our own molecular assembly line through iterative homologations of boronic esters. Here we report a reagent (α-lithioethyl triispopropylbenzoate) which inserts into carbon-boron bonds with exceptionally high fidelity and stereocontrol. Through repeated iteration we have converted a simple boronic ester into a complex molecule (a carbon chain with ten contiguous methyl groups) with remarkably high precision over its length, its stereochemistry and therefore its shape. Different stereoisomers were targeted and it was found that they adopted different shapes (helical/linear) according to their stereochemistry. This work should now enable scientists to rationally design and create molecules with predictable shape, which could have an impact in all areas of molecular sciences where bespoke molecules are required. PMID:25209797

  18. X-ray line shapes of metals: Exact solutions of a final-state interaction model

    NASA Astrophysics Data System (ADS)

    Swarts, Coenraad A.; Dow, John D.

    2005-10-01

    By means of model calculations for an independent-electron metal, we obtain exact line shapes for the photon absorption, emission, and photoemission spectra of core states, including electronic relaxation. In all cases we find an x-ray edge anomaly. For the absorption and emission spectra this anomaly is superposed on a continuum resembling Elliott exciton theory. We display how the spectra evolve from the exciton limit to the free-electron limit as the final-state interaction strength is decreased or the Fermi energy increased. We compare the spectra obtained for different final-state interactions and find that different types of interactions produce different spectral shapes. Away from threshold the absorption and emission profiles show an enhancement of the free-electron result, as predicted by the screened-exciton theory. Our results offer potential explanations for (i) incompatibilities between threshold exponents and exponents extracted from other data, (ii) the occurrence of nearly symmetric x-ray photoemission lines, and (iii) the lack of mirror symmetry of absorption and emission edges.

  19. Laser line shape and spectral density of frequency noise

    SciTech Connect

    Stephan, G.M.; Blin, S.; Besnard, P.; Tam, T.T.; Tetu, M.

    2005-04-01

    Published experimental results show that single-mode laser light is characterized in the microwave range by a frequency noise which essentially includes a white part and a 1/f (flicker) part. We theoretically show that the spectral density (the line shape) which is compatible with these results is a Voigt profile whose Lorentzian part or homogeneous component is linked to the white noise and the Gaussian part to the 1/f noise. We measure semiconductor laser line profiles and verify that they can be fit with Voigt functions. It is also verified that the width of the Lorentzian part varies like 1/P where P is the laser power while the width of the Gaussian part is more of a constant. Finally, we theoretically show from first principles that laser line shapes are also described by Voigt functions where the Lorentzian part is the laser Airy function and the Gaussian part originates from population noise.

  20. Vibronic line shapes of PTCDA oligomers in helium nanodroplets.

    PubMed

    Roden, Jan; Eisfeld, Alexander; Dvořák, Matthieu; Bünermann, Oliver; Stienkemeier, Frank

    2011-02-01

    Oligomers of the organic semiconductor 3,4,9,10-perylene-tetracarboxylic-dianhydride, C(24)H(8)O(6) (PTCDA) are studied by means of helium nanodroplet isolation spectroscopy. In contrast to the monomer absorption spectrum, which exhibits clearly separated, very sharp absorption lines, it is found that the oligomer spectrum consists of three main peaks having an apparent width orders of magnitude larger than the width of the monomer lines. Using a simple theoretical model for the oligomer, in which a Frenkel exciton couples to internal vibrational modes of the monomers, these experimental findings are nicely reproduced. The three peaks present in the oligomer spectrum can already be obtained taking only one effective vibrational mode of the PTCDA molecule into account. The inclusion of more vibrational modes leads to quasicontinuous spectra, resembling the broad oligomer spectra. PMID:21303160

  1. Ultraviolet observations of interstellar absorption lines toward SN 1987A

    NASA Technical Reports Server (NTRS)

    Savage, Blair D.; Jenkins, Edward B.; Joseph, Charles L.; De Boer, Klass S.

    1989-01-01

    High-dispersion IUE echelle spectra of SN 1987A were averaged in order to obtain UV absorption-line profiles of the highest possible quality in the direction of SN 1987A. The profiles for Si IV and C IV are quite similar and have much less structure than the Al III profile. On relating column densities, while the C IV and Si IV ratio is relatively constant over the 0-100 km/s velocity range, the C IV to Al III and Si IV to Al III ratios vary by nearly a factor of 10. This suggests that the C IV and Si IV along this sight line in the Galaxy and its halo may have a common origin which differs from that for Al III.

  2. Spectral line parameters including line shapes in the 2ν3 Q branch of 12CH4

    NASA Astrophysics Data System (ADS)

    Devi, V. Malathy; Benner, D. Chris; Sung, Keeyoon; Brown, Linda R.; Crawford, Timothy J.; Yu, Shanshan; Smith, Mary Ann H.; Mantz, Arlan W.; Boudon, Vincent; Ismail, Syed

    2016-07-01

    In this study, we report the first experimental measurements of spectral line shape parameters (self- and air-broadened Lorentz half-widths, pressure-shifts, and line mixing (via off-diagonal relaxation matrix elements) coefficients and their temperature dependences, where appropriate) for transitions in the 2ν3 Q branch manifolds, Q(11)-Q(1) of methane (12CH4), in the 5996.5-6007-cm-1 region. The analysis included 23 high-resolution, high signal-to-noise laboratory absorption spectra recorded with the Bruker IFS-125HR Fourier transform spectrometer (FTS) at JPL. The experimental data were obtained using 12C-enriched 12CH4 and dilute mixtures of 12CH4 in dry air in the 130-296 K range using a room-temperature long path absorption cell and, two custom-built coolable cells. In the analysis, an interactive multispectrum fitting software was employed where all the 23 spectra (11 self-broadened and 12 air-broadened) were fit simultaneously. By carefully applying reasonable constraints to the parameters for severely blended lines, we were able to determine a self-consistent set of broadening, shift and line mixing (relaxation matrix coefficients) parameters for CH4-CH4 and CH4-air collisions. In the majority of cases, a quadratic speed dependence parameter common for all transitions in each Q(J) manifold was determined. However, temperature dependences of the Q branch line mixing parameter could not be determined from the present data. Since no other experimental line shape measurements have been reported for this Q-branch, the present results are compared to available values in the HITRAN2012 database.

  3. Monitoring the variability of intrinsic absorption lines in quasar spectra , ,

    SciTech Connect

    Misawa, Toru; Charlton, Jane C.; Eracleous, Michael

    2014-09-01

    We have monitored 12 intrinsic narrow absorption lines (NALs) in five quasars and seven mini-broad absorption lines (mini-BALs) in six quasars for a period of 4-12 yr (1-3.5 yr in the quasar rest-frame). We present the observational data and the conclusions that follow immediately from them, as a prelude to a more detailed analysis. We found clear variability in the equivalent widths (EWs) of the mini-BAL systems but no easily discernible changes in their profiles. We did not detect any variability in the NAL systems or in narrow components that are often located at the center of mini-BAL profiles. Variations in mini-BAL EWs are larger at longer time intervals, reminiscent of the trend seen in variable BALs. If we assume that the observed variations result from changes in the ionization state of the mini-BAL gas, we infer lower limits to the gas density ∼10{sup 3}-10{sup 5} cm{sup –3} and upper limits on the distance of the absorbers from the central engine of the order of a few kiloparsecs. Motivated by the observed variability properties, we suggest that mini-BALs can vary because of fluctuations of the ionizing continuum or changes in partial coverage while NALs can vary primarily because of changes in partial coverage.

  4. The orientation and polarization of broad absorption line quasars

    NASA Astrophysics Data System (ADS)

    DiPompeo, M. A.; Brotherton, M. S.; De Breuck, C.

    2013-01-01

    We present new spectropolarimetric observations of eight radio-loud broad absorption line (BAL) quasars, and combine these new data with our previous spectropolarimetric atlases (of both radio-loud and radio-quiet objects; DiPompeo et al. 2010, DiPompeo et al. 2011a) in order to investigate the polarization properties of BAL quasars as a group. The total (radio-selected) sample includes 36 (26) high-ionization and 22 (15) low-ionization BAL quasars (HiBALs and LoBALs, respectively). On average, we confirm that broad emission lines are polarized at a level similar to or less than the continuum and broad absorption troughs are more highly polarized, but we note that these properties are not true for all individual objects. Of the whole sample, 18 (31 per cent) have high (>2 per cent) continuum polarization, including 45 per cent of the LoBALs and 22 per cent of the HiBALs. We identify a few correlations between polarization and other quasar properties, as well as some interesting non-correlations. In particular, continuum polarization does not correlate with radio spectral index, which suggests that the polarization is not due to a standard geometry and preferred viewing angle to BAL quasars. The polarization also does not correlate with the amount of intrinsic dust reddening, indicating that the polarization is not solely due to direct light attenuation either. Polarization does appear to depend on the minimum BAL outflow velocity, confirming the results of previous studies and it may correlate with the maximum outflow velocity. We also find that continuum polarization anticorrelates with the polarization in the C iv broad emission and broad absorption. These results suggest that the polarization of BAL quasars cannot be described by one simple model, and that the scatterer location and geometry can vary significantly from object to object.

  5. Extension of the quasistatic far-wing line shape theory to multicomponent anisotropic potentials

    NASA Technical Reports Server (NTRS)

    Ma, Q.; Tipping, R. H.

    1994-01-01

    The formalism developed previously for the calculation of the far-wing line shape function and the corresponding absorption coefficient using a single-component anisotropic interaction term and the binary collision and quasistatic approximations is generalized to multicomponent anisotropic potential functions. Explicit expressions are presented for several common cases, including the long-range dipole-dipole plus dipole-quadrupole interaction and a linear molecule interacting with a perturber atom. After determining the multicomponent functional representation for the interaction between the CO2 and Ar from previously published data, we calculate the theoretical line shape function and the corresponding absorption due to the nu(sub 3) band of CO2 in the frequency range 2400-2580 cm(exp -1) and compare our results with previous calculations carried out using a single-component anisotropic interaction, and with the results obtained assuming Lorentzian line shapes. The principal uncertainties in the present results, possible refinements of the theoretical formalism, and the applicability to other systems are discussed briefly.

  6. Emission line shape of B850 band of light-harvesting complex II

    NASA Astrophysics Data System (ADS)

    Kumar, Praveen; Jang, Seogjoo

    2011-03-01

    A theoretical framework is developed for the emission line shape of the single complex spectroscopy (SCS). The quantum mechanical characteristics of the single complex emission line shapes for the model B850 band of the light harvesting complex 2 of purple bacteria are studied including both static and quasi-static disorders within the exciton Hamiltonian. The bath is modeled as an infinite sum of harmonic oscillators. For the Gaussian type of disorder, we examined the dependencies of the spectral line shapes on the temperature, polarization of the radiation, and on the type of exciton-bath coupling. Theoretically obtained emission profile is also compared with the absorption profile in the frequency domain. It is observed that emission profile contains an extra inhomogeneous term coming from the entanglement of the system and bath degrees of freedom in the initial equilibrium density operator. Contribution of this term to the overall emission line shape is studied in detail. This research was supported by the Department of Energy, Office of Basic Energy Sciences.

  7. QSO Lyalpha Absorption Lines in Galaxy Superclusters and Voids

    NASA Astrophysics Data System (ADS)

    Stocke, J. T.; Shull, J. M.; Penton, S.; Burks, G.; Donahue, M.

    1993-12-01

    We have used the Hubble Space Telescope (HST) Goddard High Resolution Spectrograph (GHRS) to search for Lyalpha absorption clouds in nearby galaxy voids (cz <= 10,000 km s(-1) ). Thus far, we have obtained GHRS spectra (G160M, 1225 -- 1255 Angstroms, 0.25 Angstroms resolution) of three very bright Active Galactic Nuclei, Mrk 501, I Zw I, and Mrk 335, at V <= 14.5. We find 4 probable (4.0 sigma - 4.5 sigma ) and 4 definite (5 sigma - 16 sigma ) Lyalpha absorption lines, with equivalent widths W_λ = 50 - 200 m Angstroms, corresponding to column densities N(H I) = 10(13) -- 10(14) cm(-2) , assuming a typical Doppler parameter of b = 25 km s(-1) . Based on an updated version of the CfA redshift survey (Huchra and Clemens, private communication), most of these Lyalpha systems appear to be associated with supercluster - sized ``strings'' of galaxies similar to the ``Great Wall''. Toward Mrk 501, the nearest bright galaxy at the redshift of the strongest (200 m Angstroms) Lyalpha cloud lies 500 h75(-1) kpc off the line of sight. Models of H I disks exposed to the intergalactic ionizing radiation field (Dove & Shull 1994, ApJ, 423, in press) show that the N(H I) = 10(13) cm(-2) contour in a typical spiral galaxy is reached at 100 kpc radial extent. Thus, the Lyalpha absorbers associated with galaxy-string systems may be the result of H I in an extended halo, in dwarf satellite galaxies (M_B > -15), or in tidally-stripped gas. Most importantly for cosmological origins of baryons, one (4.3 sigma ) Lyalpha absorption line in the spectrum of Mrk 501 lies within the galaxy void in the foreground of the ``Great Wall''. The nearest bright galaxy, to a level M_B <= -18.5 for H_0 = 75 km s(-1) Mpc(-1) , is more than 5 Mpc away. A pencil-beam survey of faint galaxies to M_B = -16.0 finds no galaxy within 100 h75(-1) kpc of the line of sight, at or near the absorber redshift.

  8. The shape of spectral lines: The importance of the far wings

    NASA Technical Reports Server (NTRS)

    Tipping, Richard

    1995-01-01

    Spectroscopy, the study of the interaction of radiation and matter, provides most of the information we have gleaned about the composition, structure, and evolution of the universe. As is well known, by measuring the frequencies of spectral lines in absorption or emission, one can uniquely infer the presence of atoms or molecules as well as their physical state and environment (e.g., solid or gaseous, neutral or ionized, moving or stationary, etc.). Furthermore, by studying the intensities of these lines, one can determine the abundance (i.e., number of a particular species per unit volume). Although less well known, the shape of the spectral lines, in particular, the structure of the far wings, plays a very important role in many important atmospheric phenomena such as the greenhouse effect or the absorption of harmful ultraviolet radiation. Although first measured more than 50 years ago, the anomalous absorption of radiation by water vapor in the earth's atmosphere was postulated to be due to far wings of allowed lines. However, only within the past few years has a quantitative verification of this hypothesis been possible through the development of an accurate theoretical description of the shape of self-broadened water lines. During the summer, work has been done on improving this theory and in comparing the results to other theories valid near the center of the lines. The relevance of this work to measurements of greenhouse gases, of earth-based measurements of the 3 K cosmic background radiation, of satellite-based measurements of the atmospheres of the earth and other planets, and other similar problems will be discussed briefly.

  9. Line-shapes analysis with ultra-high accuracy

    NASA Astrophysics Data System (ADS)

    Wcisło, Piotr; Cygan, Agata; Lisak, Daniel; Ciuryło, Roman

    2014-11-01

    We present analysis of the R7 Q8 O2 B-band rovibronic transition measured with ultra-high signal-to-noise ratio by Pound-Drever-Hall-locked frequency-stabilized cavity-ring- down spectroscopy. For line-shape calculations ab intio in spirt approach was used based on numerical solution of the proper transport/relaxation equation. Consequences for spectroscopic determination of the Boltzmann constant as well as precise determination of the line position in the Doppler limited spectroscopy are indicated.

  10. Broad Balmer-Line Absorption in SDSS J172341.10+555340.5

    NASA Astrophysics Data System (ADS)

    Aoki, Kentaro

    2010-10-01

    We present the discovery of Balmer-line absorption from Hα to H9 in an iron low-ionizaton broad absorption line (FeLoBAL) quasar, SDSS J172341.10+555340.5, by near-infrared spectroscopy with the Cooled Infrared Spectrograph and Camera for OHS (CISCO) attached to the Subaru Telescope. The redshift of the Balmer-line absorption troughs is 2.0530±0.0003, and it is blueshifted by 5370 km s-1 from the Balmer emission lines. It is more than 4000 km s-1 blueshifted from the previously known UV absorption lines. We detected relatively strong (EWrest = 20 Å) [OIII] emission lines that are similar to those found in other broad absorption line quasars with Balmer-line absorption. We also derived the column density of neutral hydrogen of 5.2 × 1017 cm-2 by using the curve of growth and taking account of Lyα trapping. We searched for UV absorption lines that had the same redshift with Balmer-line absorption, and found Ali III and Fe III absorption lines at z = 2.053 that correspond to previously unidentified absorption lines, and the presence of other blended troughs that were difficult to identify.

  11. First Observation of the {Lambda}(1405) Line Shape in Electroproduction

    SciTech Connect

    Iowa State U.; Carnegie Mellon U.

    2013-10-01

    We report the first observation of the line shape of the {Lambda}(1405) from electroproduction, and show that it is not a simple Breit-Wigner resonance. Electroproduction of K{sup +}{Lambda}(1405) off the proton was studied by using data from CLAS at Jefferson Lab in the range 1.0line shape. In our fits, the line shape corresponds approximately to predictions of a two-pole meson-baryon picture of the {Lambda}(1405), with a lower mass pole near 1368 MeV/c{sup 2} and a higher mass pole near 1423 MeV/c{sup 2}. Furthermore, with increasing photon virtuality the mass distribution shifts toward the higher mass pole.

  12. Radio Structures of Compact Quasars with Broad Absorption Lines

    NASA Astrophysics Data System (ADS)

    Kunert-Bajraszewska, Magdalena; Gawroński, Marcin P.

    2010-05-01

    Broad absorption lines (BALs), seen in a small fraction of both the radio-quiet and radio-loud quasar populations, are probably caused by the outflow of gas with high velocities and are part of the accretion process. The presence of BALs is due to a geometrical effect and/or it is connected with the quasar evolution. Using the final release of FIRST survey combined with a catalog of BAL QSOs from SDSS/DR3, we have constructed a new sample of compact radio-loud BAL QSOs, which constitutes the majority of radio-loud BAL QSOs. The main goal of this project is to study the origin of BALs by analysis of the BAL QSOs radio morphology, orientation, and jet evolution using the European VLBI Network (EVN) at 1.6 GHz and the Very Long Baseline Array (VLBA) at 5 and 8.4 GHz.

  13. The intrinsic fraction of broad-absorption line quasars

    NASA Astrophysics Data System (ADS)

    Knigge, Christian; Scaringi, Simone; Goad, Michael R.; Cottis, Christopher E.

    2008-05-01

    We carefully reconsider the problem of classifying broad-absorption line quasars (BALQSOs) and derive a new, unbiased estimate of the intrinsic BALQSO fraction from the Sloan Digital Sky Survey (SDSS) DR3 quasi-stellar object (QSO) catalogue. We first show that the distribution of objects selected by the so-called `absorption index' (AI) is clearly bimodal in logAI, with only one mode corresponding to definite BALQSOs. The surprisingly high BALQSO fractions that have recently been inferred from AI-based samples are therefore likely to be overestimated. We then present two new approaches to the classification problem that are designed to be more robust than the AI, but also more complete than the traditional `balnicity index' (BI). Both approaches yield observed BALQSO fractions around 13.5 per cent, while a conservative third approach suggests an upper limit of 18.3 per cent. Finally, we discuss the selection biases that affect our observed BALQSO fraction. After correcting for these biases, we arrive at our final estimate of the intrinsic BALQSO fraction. This is fBALQSO = 0.17 +/- 0.01(stat) +/- 0.03(sys) with an upper limit of fBALQSO ~= 0.23. We conclude by pointing out that the bimodality of the logAI distribution may be evidence that the BAL-forming region has clearly delineated physical boundaries.

  14. Quasar Broad Absorption Line Variability on Multiyear Timescales

    NASA Astrophysics Data System (ADS)

    Gibson, Robert R.; Brandt, W. N.; Schneider, Donald P.; Gallagher, S. C.

    2008-03-01

    We use quantitative metrics to characterize the variation of C IV λ1549 broad absorption lines (BALs) over 3-6 (rest-frame) years in a sample of 13 quasars at 1.7 <= z<= 2.8 and compare the results to previous studies of BAL variability on shorter timescales. The strong BALs in our study change in complex ways over 3-6 yr. Variation occurs in discrete regions only a few thousand kilometers per second wide, and the distribution of the change in absorption equivalent width broadens over time. We constrain the typical C IV BAL lifetime to be at least a few decades. While we do not find evidence to support a scenario in which the variation is primarily driven by photoionization on multiyear timescales, there is some indication that the variation is produced by changes in outflow geometry. We do not observe significant changes in the BAL onset velocity, indicating that the absorber is either far from the source or is being continually replenished and is azimuthally symmetric. It is not possible in a human lifetime to expand the timescales in our study by more than a factor of a few using optical spectroscopy. However, the strong variation we have observed in some BALs indicates that future studies of large numbers of BAL QSOs will be valuable to constrain BAL lifetimes and the physics of variation.

  15. Quasar Outflow Constraints using Broad Absorption Line Variability Studies

    NASA Astrophysics Data System (ADS)

    McGraw, Sean; Shields, Joseph C.; Hamann, Fred; Capellupo, Daniel M.; Gallagher, Sarah; Brandt, W. Niel; Herbst, Hanna

    2016-01-01

    Quasar outflows are plausible candidates for AGN feedback processes influencing the host galaxy and may explain the established correlations between the supermassive black hole (SMBH) and the surrounding bulge. In order to better understand feedback and the physical conditions of the outflowing gas, observational constraints on absorber kinematics and energetics are needed. We are utilizing multiple epoch, rest frame UV quasar spectra to establish limits on outflow locations and total column densities for the purpose of estimating wind kinetic energies and momenta. We are also investigating the variability patterns of broad absorption lines (BALs) and mini-BALs across a range of ionization states to probe underlying connections between the various classes of absorbers. This work employs observations from the Sloan Digital Sky Survey, Hobby Eberly Telescope, and MDM observatory. We detect BAL variability in 3 out of 12 FeLoBAL quasars over multiple year timescales and conclude that the variable absorbers lie within tens of parsecs of the SMBH based on interpretations of the Fe II and Mg II BALS. We also measure significant BAL changes across daily to yearly timescales in a sample of 71 quasars with plausible detections of the P V 1117,1128 BAL. Detecting phosphorus in absorption is notable because it traces high column density outflows and is therefore relevant for studying AGN feedback. Constraints on outflow energetics and other selected results will be presented.

  16. Outflow and hot dust emission in broad absorption line quasars

    SciTech Connect

    Zhang, Shaohua; Zhou, Hongyan; Wang, Huiyuan; Wang, Tinggui; Xing, Feijun; Jiang, Peng; Zhang, Kai E-mail: whywang@mail.ustc.edu.cn

    2014-05-01

    We have investigated a sample of 2099 broad absorption line (BAL) quasars with z = 1.7-2.2 built from the Sloan Digital Sky Survey Data Release Seven and the Wide-field Infrared Survey. This sample is collected from two BAL quasar samples in the literature and is refined by our new algorithm. Correlations of outflow velocity and strength with a hot dust indicator (β{sub NIR}) and other quasar physical parameters—such as an Eddington ratio, luminosity, and a UV continuum slope—are explored in order to figure out which parameters drive outflows. Here β{sub NIR} is the near-infrared continuum slope, which is a good indicator of the amount of hot dust emission relative to the accretion disk emission. We confirm previous findings that outflow properties moderately or weakly depend on the Eddington ratio, UV slope, and luminosity. For the first time, we report moderate and significant correlations of outflow strength and velocity with β{sub NIR} in BAL quasars. It is consistent with the behavior of blueshifted broad emission lines in non-BAL quasars. The statistical analysis and composite spectra study both reveal that outflow strength and velocity are more strongly correlated with β{sub NIR} than the Eddington ratio, luminosity, and UV slope. In particular, the composites show that the entire C IV absorption profile shifts blueward and broadens as β{sub NIR} increases, while the Eddington ratio and UV slope only affect the high and low velocity part of outflows, respectively. We discuss several potential processes and suggest that the dusty outflow scenario, i.e., that dust is intrinsic to outflows and may contribute to the outflow acceleration, is most likely.

  17. Monitoring the Variability of Intrinsic Absorption Lines in Quasar Spectra

    NASA Astrophysics Data System (ADS)

    Misawa, Toru; Charlton, Jane C.; Eracleous, Michael

    2014-09-01

    We have monitored 12 intrinsic narrow absorption lines (NALs) in five quasars and seven mini-broad absorption lines (mini-BALs) in six quasars for a period of 4-12 yr (1-3.5 yr in the quasar rest-frame). We present the observational data and the conclusions that follow immediately from them, as a prelude to a more detailed analysis. We found clear variability in the equivalent widths (EWs) of the mini-BAL systems but no easily discernible changes in their profiles. We did not detect any variability in the NAL systems or in narrow components that are often located at the center of mini-BAL profiles. Variations in mini-BAL EWs are larger at longer time intervals, reminiscent of the trend seen in variable BALs. If we assume that the observed variations result from changes in the ionization state of the mini-BAL gas, we infer lower limits to the gas density ~103-105 cm-3 and upper limits on the distance of the absorbers from the central engine of the order of a few kiloparsecs. Motivated by the observed variability properties, we suggest that mini-BALs can vary because of fluctuations of the ionizing continuum or changes in partial coverage while NALs can vary primarily because of changes in partial coverage. Based on data collected at Subaru telescope, which is operated by the National Astronomical Observatory of Japan. Based on observations obtained at the European Southern Observatory at La Silla, Chile in programs 65.O-0063(B), 65.O-0474(A), 67.A-0078(A), 68.A-0461(A), 69.A-0204(A), 70.B-0522(A), 072.A-0346(A), 076.A-0860(A), 079.B-0469(A), and 166.A-0106(A).

  18. Seepage from canals having variable shape and partial lining

    NASA Astrophysics Data System (ADS)

    Mirnateghi, A.; Bruch, J. C.

    1983-07-01

    The numerical models presented here are solutions to the steady two-dimensional flow through a porous medium from canals of variable shape with partial lining. Two main cases are studied. The first case is the seepage flow from canals with impervious lining on their sloping sides. The second case is for seepage from canals in which the impervious lining is located on the base of the canal and the sides are unlined. The Baiocchi transformation and method is used to develop a boundary value problem which is then solved by the finite-difference successive over-relaxation method with projection. A sample problem of each case is presented. The discharge rates and free surfaces of the seepage flows are obtained through the numerical scheme, and are compared with available analytical results.

  19. On the origins of C IV absorption profile diversity in broad absorption line quasars

    NASA Astrophysics Data System (ADS)

    Baskin, Alexei; Laor, Ari; Hamann, Fred

    2015-05-01

    There is a large diversity in the C IV broad absorption line (BAL) profile among BAL quasars (BALQs). We quantify this diversity by exploring the distribution of the C IV BAL properties, full width at half-maximum (FWHM), maximum depth of absorption and its velocity shift (vmd), using the Sloan Digital Sky Survey DR7 quasar catalogue. We find the following: (i) Although the median C IV BAL profile in the quasar rest-frame becomes broader and shallower as the UV continuum slope (αUV at 1700-3000 Å) gets bluer, the median individual profile in the absorber rest-frame remains identical, and is narrow (FWHM = 3500 km s-1) and deep. Only 4 per cent of BALs have FWHM > 10 000 km s-1. (ii) As the He II emission equivalent width (EW) decreases, the distributions of FWHM and vmd extend to larger values, and the median maximum depth increases. These trends are consistent with theoretical models in which softer ionizing continua reduce overionization, and allow radiative acceleration of faster BAL outflows. (iii) As αUV becomes bluer, the distribution of vmd extends to larger values. This trend may imply faster outflows at higher latitudes above the accretion disc plane. (iv) For non-BALQs, the C IV emission line decreases with decreasing He II EW, and becomes more asymmetric and blueshifted. This suggests an increasing relative contribution of emission from the BAL outflow to the C IV emission line as the ionizing spectral energy distribution (SED) gets softer, which is consistent with the increasing fraction of BALQs as the ionizing SED gets softer.

  20. Shape of the absorption and fluorescence spectra of condensed phases and transition energies.

    PubMed

    Lagos, Miguel; Paredes, Rodrigo

    2014-11-13

    General integral expressions for the temperature-dependent profile of the spectral lines of photon absorption and emission by atomic or molecular species in a condensed environment are derived with no other hypothesis than: (a) The acoustic vibrational modes of the condensed host medium constitute the thermodynamic energy reservoir at a given constant temperature, and local electronic transitions modifying the equilibrium configuration of the surroundings are multiphonon events, regardless of the magnitude of the transition energy. (b) Electron-phonon coupling is linear in the variations of the bond length. The purpose is to develop a theoretical tool for the analysis of the spectra, allowing us to grasp highly accurate information from fitting the theoretical line shape function to experiment, including those spectra displaying wide features. The method is illustrated by applying it to two dyes, Lucifer Yellow CH and Coumarin 1, which display fluorescence maxima of 0.41 and 0.51 eV fwhm. Fitting the theoretical curves to the spectra indicates that the neat excitation energies are 2.58 eV ± 2.5% and 3.00 eV ± 2.0%, respectively. PMID:25321927

  1. The Physical Nature of Polar Broad Absorption Line Quasars

    NASA Technical Reports Server (NTRS)

    Ghost, Kajal; Punsly, Brian

    2007-01-01

    It has been shown based on radio variability arguments that some BALQSOs (broad absorption line quasars) are viewed along the polar axis (o rthogonal to accretion disk) in the recent article of Zhou et a. Thes e arguments are based on the brightness temperature, T(sub b) exceedi ng 10(exp 12) K which leads to the well-known inverse Compton catastr ophe unless the radio jet is relativistic and is viewed along its axi s. In this letter, we expand the Zhou et al sample of polar BALQSOs u sing their techniques applied to SDSS DR5. In the process, we clarify a mistake in their calculation of brightness temperature. The expanded sample of high T(sub b) BALQSOS, has an inordinately large fraction of LoBALQSOs (low ionization BALQSOs). We consider this an important clue to understanding the nature of the polar BALQSOs. This is expec ted in the polar BALQSO analytical/numerical models of Punsly that pr edicted that LoBALQSOs occur when the line of sight is very close to the polar axis, where the outflow density is the highest.

  2. Broad absorption line variability in radio-loud quasars

    NASA Astrophysics Data System (ADS)

    Welling, C. A.; Miller, B. P.; Brandt, W. N.; Capellupo, D. M.; Gibson, R. R.

    2014-05-01

    We investigate C IV broad absorption line (BAL) variability within a sample of 46 radio-loud quasars (RLQs), selected from Sloan Digital Sky Survey (SDSS)/Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) data to include both core-dominated (39) and lobe-dominated (7) objects. The sample consists primarily of high-ionization BAL quasars, and a substantial fraction have large BAL velocities or equivalent widths; their radio luminosities and radio-loudness values span ˜2.5 orders of magnitude. We have obtained 34 new Hobby-Eberly Telescope spectra of 28 BAL RLQs to compare to earlier SDSS data, and we also incorporate archival coverage (primarily dual-epoch SDSS) for a total set of 78 pairs of equivalent width measurements for 46 BAL RLQs, probing rest-frame time-scales of ˜80-6000 d (median 500 d). In general, only modest changes in the depths of segments of absorption troughs are observed, akin to those seen in prior studies of BAL radio-quiet quasars (RQQs). Also similar to previous findings for RQQs, the RLQs studied here are more likely to display BAL variability on longer rest-frame time-scales. However, typical values of |{Δ}EW| and |{Δ}EW|/ are ˜40 ± 20 per cent lower for BAL RLQs when compared with those of a time-scale-matched sample of BAL RQQs. Optical continuum variability is of similar amplitude in BAL RLQs and BAL RQQs; for both RLQs and RQQs, continuum variability tends to be stronger on longer time-scales. BAL variability in RLQs does not obviously depend upon their radio luminosities or radio-loudness values, but we do find tentative evidence for greater fractional BAL variability within lobe-dominated RLQs. Enhanced BAL variability within more edge-on (lobe-dominated) RLQs supports some geometrical dependence to the outflow structure.

  3. Doppler-shifted neutral beam line shape and beam transmission

    SciTech Connect

    Kamperschroer, J.H.; Grisham, L.R.; Kokatnur, N.; Lagin, L.J.; Newman, R.A.; O`Connor, T.E.; Stevenson, T.N.; von Halle, A.

    1994-04-01

    Analysis of Doppler-shifted Balmer-{alpha} line emission from the TFTR neutral beam injection systems has revealed that the line shape is well approximated by the sum of two Gaussians, or, alternatively, by a Lorentzian. For the sum of two Gaussians, the broad portion of the distribution contains 40% of the beam power and has a divergence five times that of the narrow part. Assuming a narrow 1/e- divergence of 1.3{degrees} (based on fits to the beam shape on the calorimeter), the broad part has a divergence of 6.9{degrees}. The entire line shape is also well approximated by a Lorentzian with a half-maximum divergence of 0.9{degrees}. Up to now, fusion neutral beam modelers have assumed a single Gaussian velocity distribution, at the extraction plane, in each direction perpendicular to beam propagation. This predicts a beam transmission efficiency from the ion source to the calorimeter of 97%. Waterflow calorimetry data, however, yield a transmission efficiency of {approximately}75%, a value in rough agreement with predictions of the Gaussian or Lorentzian models presented here. The broad wing of the two Gaussian distribution also accurately predicts the loss in the neutralizer. An average angle of incidence for beam loss at the exit of the neutralizer is 2.2{degrees}, rather than the 4.95{degrees} subtended by the center of the ion source. This average angle of incidence, which is used in computing power densities on collimators, is shown to be a function of beam divergence.

  4. Analysis of the line shape of electrically detected ferromagnetic resonance

    NASA Astrophysics Data System (ADS)

    Harder, M.; Cao, Z. X.; Gui, Y. S.; Fan, X. L.; Hu, C.-M.

    2011-08-01

    This work reviews and examines two particular issues related with the new technique of electrical detection of ferromagnetic resonance (FMR). This powerful technique has been broadly applied for studying magnetization and spin dynamics over the past ten years. The first issue is the relation and distinction between different mechanisms that give rise to a photovoltage via FMR in spintronic devices, and the second is the proper analysis of the FMR line shape, which has become the “Achilles heel” in interpreting experimental results, especially for either studying the spin pumping effect or quantifying spin Hall angles via the electrically detected FMR.

  5. DISCOVERY OF THE TRANSITION OF A MINI-BROAD ABSORPTION LINE INTO A BROAD ABSORPTION LINE IN THE SDSS QUASAR J115122.14+020426.3

    SciTech Connect

    Hidalgo, Paola Rodriguez; Eracleous, Michael; Charlton, Jane; Hamann, Fred; Murphy, Michael T.; Nestor, Daniel

    2013-09-20

    We present the detection of a rare case of dramatic strengthening in the UV absorption profiles in the spectrum of the quasar J115122.14+020426.3 between observations {approx}2.86 yr apart in the quasar rest frame. A spectrum obtained in 2001 by the Sloan Digital Sky Survey shows a C IV ''mini-broad'' absorption line (FWHM = 1220 km s{sup -1}) with a maximum blueshift velocity of {approx}9520 km s{sup -1}, while a later spectrum from the Very Large Telescope shows a significantly broader and stronger absorption line, with a maximum blueshift velocity of {approx}12, 240 km s{sup -1} that qualifies as a broad absorption line. A similar variability pattern is observed in two additional systems at lower blueshifted velocities and in the Ly{alpha} and N V transitions as well. One of the absorption systems appears to be resolved and shows evidence for partial covering of the quasar continuum source (C{sub f} {approx} 0.65), indicating a transverse absorber size of, at least, {approx}6 Multiplication-Sign 10{sup 16} cm. In contrast, a cluster of narrower C IV lines appears to originate in gas that fully covers the continuum and broad emission line sources. There is no evidence for changes in the centroid velocity of the absorption troughs. This case suggests that at least some of the absorbers that produce ''mini-broad'' and broad absorption lines in quasar spectra do not belong to intrinsically separate classes. Here, the ''mini-broad'' absorption line is most likely interpreted as an intermediate phase before the appearance of a broad absorption line due to their similar velocities. While the current observations do not provide enough constraints to discern among the possible causes for this variability, future monitoring of multiple transitions at high resolution will help achieve this goal.

  6. Shape of collision-broadened lines of carbon monoxide

    NASA Astrophysics Data System (ADS)

    Seleznev, A. F.; Fedoseev, G. V.; Koshelev, M. A.; Tretyakov, M. Yu.

    2015-08-01

    We consider lineshape of the rotational spectrum of a CO molecule under the conditions of prevailing collisional broadening. Several series of experimental data obtained at relatively high (up to 1000) signal-to-noise ratio of self-broadening and broadening by noble gases have been analyzed. We used for analysis several well known models beyond the Voigt profile. It is confirmed that the use of the Hartman-Tran profile needs certain requirements in order to obtain meaningful and unambiguous results. A simple numerical simulation is suggested to evaluate the result of the model usage for any particular set of experimental data. Parameters of the collisional line narrowing were obtained. It is shown that under the experimental conditions, deviations of the shape of the observed lines from the Voigt profile are solely due to the wind effect.

  7. Propagation of femtosecond pulse with self-similar shape in medium with nonlinear absorption

    NASA Astrophysics Data System (ADS)

    Trofimov, Vyacheslav A.; Zakharova, Irina G.

    2015-05-01

    We investigate the propagation of laser pulse with self-similar shape in homogeneous medium with various mechanisms of nonlinear absorption: multi-photon absorption or resonant nonlinearity under detuning the frequency, corresponding to energy transition, from the current frequency of wave packet, or nonlinear absorption with its saturation. Both types of sign for frequency detuning are considered. This results in appearance of a refractive index grating which induced a laser pulse self-action. We analyze also the influence of the laser pulse self-modulation due to cubic nonlinearity on existence of the laser pulse propagation mode with self-similar shape. We develop an analytical solution of the corresponding nonlinear eigenfunction problem for laser pulse propagation in medium with nonlinear absorption. This solution is confirmed by computer simulation of the eigenfunction problem for Schrödinger equation with considered nonlinearity. This mode of laser pulse propagation is very important for powerful TW laser pulse propagating in glass.

  8. THE VIEWING ANGLES OF BROAD ABSORPTION LINE VERSUS UNABSORBED QUASARS

    SciTech Connect

    DiPompeo, M. A.; Brotherton, M. S.; De Breuck, C.

    2012-06-10

    It was recently shown that there is a significant difference in the radio spectral index distributions of broad absorption line (BAL) quasars and unabsorbed quasars, with an overabundance of BAL quasars with steeper radio spectra. This result suggests that source orientation does play into the presence or absence of BAL features. In this paper, we provide more quantitative analysis of this result based on Monte Carlo simulations. While the relationship between viewing angle and spectral index does indeed contain a lot of scatter, the spectral index distributions are different enough to overcome that intrinsic variation. Utilizing two different models of the relationship between spectral index and viewing angle, the simulations indicate that the difference in spectral index distributions can be explained by allowing BAL quasar viewing angles to extend about 10 Degree-Sign farther from the radio jet axis than non-BAL sources, though both can be seen at small angles. These results show that orientation cannot be the only factor determining whether BAL features are present, but it does play a role.

  9. Absolute absorption on the potassium D lines: theory and experiment

    NASA Astrophysics Data System (ADS)

    Hanley, Ryan K.; Gregory, Philip D.; Hughes, Ifan G.; Cornish, Simon L.

    2015-10-01

    We present a detailed study of the absolute Doppler-broadened absorption of a probe beam scanned across the potassium D lines in a thermal vapour. Spectra using a weak probe were measured on the 4S \\to 4P transition and compared to the theoretical model of the electric susceptibility detailed by Zentile et al (2015 Comput. Phys. Commun. 189 162-74) in the code named ElecSus. Comparisons were also made on the 4S \\to 5P transition with an adapted version of ElecSus. This is the first experimental test of ElecSus on an atom with a ground state hyperfine splitting smaller than that of the Doppler width. An excellent agreement was found between ElecSus and experimental measurements at a variety of temperatures with rms errors ˜ {10}-3. We have also demonstrated the use of ElecSus as an atomic vapour thermometry tool, and present a possible new measurement technique of transition decay rates which we predict to have a precision of ˜3 {kHz}.

  10. X-Ray Continua of Broad Absorption Line Quasars

    NASA Technical Reports Server (NTRS)

    Mathur, S.

    1999-01-01

    The targets for this program, PG1416-129 and LBQS 2212-1759 were known to be Broad Absorption Line Quasars (BALQSOs). BALQSOs are highly absorbed in soft X-rays. Good high energy response of Rossi-XTE made them ideal targets for observation. We observed LBQS 2212-1759 with PCA. We have now analyzed the data and found that the source was not detected. Since our target was expected to be faint, reliable estimate of background was very important. With the release of new FTOOLS (version 4.1) we were able to do so. We also analyzed a well known bright object and verified our results with the published data. This gave us confidence in the non-detection of our target LBQS 2212-1759. We are currently investigating the implications of this non-detection. Due to some scheduling problems, our second target PG1416-129 was not observed in A01. It was observed on 06/26/98. This target was detected with RXTE. We are now working on the spectral analysis with XSPEC.

  11. Fano line shapes in the branch-baffle system

    NASA Astrophysics Data System (ADS)

    Gou, Bo; Zhao, Yufang; Duan, Gaoyan; Wang, Lulu; Chen, Zhao; Cui, Runa; Zhang, Yong; Yu, Li

    2014-12-01

    A compact branch-baffle system, consisting of a branch resonator and a baffle in the metal-dielectric-metal waveguide (MDM), is proposed. A novel and efficient circuit model is developed to present the mechanisms of the plasmonic system. The model predicts two sharp asymmetric Fano line shapes, which are caused by the interactions between the branch resonator and the constructed branch-baffle resonator, exhibiting good agreement with the finite-element simulation results. The peaks of the two Fano line shapes are investigated by the relative phase method and demonstrated referring to the field distributions. The physical mechanisms of the remaining three resonances in the transmission spectrum are also carefully studied. From the analysis, the five resonances can all be precisely calculated and designed in theory. Considering the compact structure, multiple Fano resonances may be adjusted in different ways. Also, the transmittance of the Fano resonances is highly efficient (0.8). The proposed structure can have important applications in high-resolution and high-sensitivity nano-plasmonic devices.

  12. PREFACE: XXII International Conference on Spectral Line Shapes 2014

    NASA Astrophysics Data System (ADS)

    Parigger, C. G.

    2014-11-01

    The 22nd International Conference on Spectral Line Shapes (ICSLS) was convened at The University of Tennessee Space Institute (UTSI) at Tullahoma, Tennessee, USA, during June 1 to 6, 2014. A variety of topics of interest to the line shape community were addressed during invited and contributed oral and poster presentations. General categories of the ICSLS 2014 scientific contents included Astrophysics, Biomedical Physics, High and Low Temperature Plasma Physics, Magnetic Fusion Physics, Neutrals Atomic-Molecular-Optical (AMO) Physics, and Applied Physics. Research interests at UTSI and at the Center for Laser Applications (CLA) focus on Applied Physics and Plasma Physics areas such as laser-induced breakdown spectroscopy, spectroscopy with ultra-short light pulses, combustion diagnostics, to name a few. Consequently, the presentations during the conference addressed a variety of these topics. Attendance at the conference included researchers from North America, Africa, Asia and Europe, with an international representation showing 250 authors and co-authors with over 25 different citizenships, and 100 participants at the Conference. Figure 1 shows a photo of Conference attendees. The schedule included 82 contributions, 41 oral and 41 poster presentations. The 29 invited, 12 contributed oral and 41 contributed poster presentations were selected following communication with the international organizing committee members. A smart phone ''app'' was also utilized, thanks to Elsevier, to communicate electronic versions of the posters during the conference. Special thanks go to the members of the international and local committees for their work in organizing the 22nd ICSLS. In addition, thank you notes also go to the peer reviewers for the proceedings. Following the success of the IOP: Journal of Physics Conference Series selected for the 21st ICSLS publication, the proceedings papers report ongoing research activities. Papers submitted amount to 68 in number, or 83% of

  13. Line by Line Analysis of Carbon Dioxide Absorption for Predicting Global Warming

    NASA Astrophysics Data System (ADS)

    Smith, D. C.

    2010-12-01

    The anthropologic cause of global warming rests on the impact of CO2 on the green house effect. Previous derivations of the increase in the CO2 Forcing Function caused by doubling of atmospheric CO2 from 320 ppm to 640 ppm reported a value of 4 W/M2( Ramananathan,V,et al, J.of Geophysical Research Vol 84, C8,p4949, Aug.1979) This value leads to a calculated temperature rise of 1 deg.K (Charney,J. et al,”Carbon Dioxide and Climate: A Scientific Assessment”, National Academy of Science, Washington D.C., 1979). This increase in global temperature leads to an increase in water vapor if it is assumed that the relative humidity is constant. This ampflication leads to a calculated temperature rise of an additional 2 deg.K. Different arguments as to the effects of the earth’s albido change, clouds, and the oceans also impact the earths global warming with predictions of total temperature rise of as high as 6 deg.K { IPCC,2007 Summary for Policymakers. In: Climate Change 2007: The Physical Sciences Basis. Contributions of Working Group 1 to the Fourth Assessment Report of the IPCC [ Solomon,S,D. et al (eds)] Cambridge University Press, NY,USA}. Regardless of the other effects, the only way that man can be held responsible for global warming is by CO2 emissions and the resulting increase in the Forcing Function. This paper challenges the magnitude of the 4 W/M2 Forcing Function. The earth radiates in the 4 to 30 micron wavelength range. CO2 has absorption bands in the 4, 10, and 15 micron wavelengths (Hertzberg G. Molecular Spectra & Molecular Structure,Norstrand Co.,1960). McClatchey has tabulated the line stengths for all CO2 transitions and they are used to calculate the atmospheric absorption (McClatchey,R, et al “AFCRL Atmospheric Absorption Line Parameter Compilation”,AFCRL-TR-0096,1973). Detailed calculations of the CO2 line absorption in the 8 to 12 micron atmospheric window shows an increase of 0.3 W/M2 for CO2 doubling. The increase in absorbed fluence in

  14. Experimental study of absorption band controllable planar metamaterial absorber using asymmetrical snowflake-shaped configuration

    NASA Astrophysics Data System (ADS)

    Huang, Yongjun; Tian, Yiran; Wen, Guangjun; Zhu, Weiren

    2013-05-01

    In this paper, we systematically discuss a novel planar metamaterial absorber (PMA) based on asymmetrical snowflake-shaped resonators, which can exhibit two distinctly different absorption states, single- and dual-band absorptions, by controlling the branch lengths of the proposed resonators. Numerical simulations and experimental measurements are employed to investigate these two kinds of absorption characteristic in an X-band rectangular waveguide. Both results indicate that such a PMA exhibits a wide range of controllable operating frequencies for the single- and dual-band conditions. The proposed PMA is simple and easy to make, and it has wide applications in the fields of stealth technologies, thermal detectors, and imaging.

  15. Anomalous optogalvanic line shapes of argon metastable transitions in a hollow cathode lamp

    NASA Technical Reports Server (NTRS)

    Ruyten, W. M.

    1993-01-01

    Anomalous optogalvanic line shapes were observed in a commercial hollow cathode lamp containing argon buffer gas. Deviations from Gaussian line shapes were particularly strong for transitions originating from the 3P2 metastable level of argon. The anomalous line shapes can be described reasonably well by the assumption that two regions in the discharge are excited simultaneously, each giving rise to a purely Gaussian line shape, but with different polarities, amplitudes, and linewidths.

  16. Final-state effects on photoemission line shapes at finite temperature

    SciTech Connect

    S {o}ndergaard, Ch.; Hofmann, Ph.; Schultz, Ch.; Moreno, M. S.; Gayone, J. E.; Vicente Alvarez, M. A.; Zampieri, G.; Lizzit, S.; Baraldi, A.

    2001-06-15

    We have measured angle-resolved photoemission spectra from Al(001) over a large range of temperatures and photon energies. These data were analyzed using a model that allows one to calculate the photoemission intensity for transitions with the simultaneous excitation/absorption of 0, 1, 2, etc., phonons. By making a simple simulation of the line shape, we show that the so-called direct transition (or quasiparticle) peaks always contain a significant contribution from photoemission events with a simultaneous excitation and/or absorption of 1 and 2 phonons, i.e., from transitions that are actually indirect. At low photon energies and/or low temperatures these contributions are small; but as the photon energy or the temperature is raised they increase relative to the elastic or zero-phonon contribution and eventually become the dominant contribution to the so-called direct transition peak. The effect of these phonon-assisted transitions is a significant change of the photoemission line shape. Our model gives a good description of the temperature dependence in the experimental data but only if the phonon-assisted contributions to the photoemission peak are taken into account.

  17. Tracing inflows and outflows with absorption lines in circumgalactic gas

    NASA Astrophysics Data System (ADS)

    Ford, Amanda Brady; Davé, Romeel; Oppenheimer, Benjamin D.; Katz, Neal; Kollmeier, Juna A.; Thompson, Robert; Weinberg, David H.

    2014-10-01

    We examine how H I and metal absorption lines within low-redshift galaxy haloes trace the dynamical state of circumgalactic gas, using cosmological hydrodynamic simulations that include a well-vetted heuristic model for galactic outflows. We categorize inflowing, outflowing, and ambient gas based on its history and fate as tracked in our simulation. Following our earlier work, showing that the ionization level of absorbers was a primary factor in determining the physical conditions of absorbing gas, we show here that it is also a governing factor for its dynamical state. Low-ionization metal absorbers (e.g. Mg II) tend to arise in gas that will fall on to galaxies within several Gyr, while high-ionization metal absorbers (e.g. O VI) generally trace material that was deposited by outflows many Gyr ago. Inflowing gas is dominated by enriched material that was previously ejected in an outflow; hence, accretion at low redshifts is typically substantially enriched. Recycling wind material is preferentially found closer to galaxies, and is more dominant in lower mass haloes since high-mass haloes have more hot gas that is able to support itself against infall. Low-mass haloes also tend to re-eject more of their accreted material, owing to our outflow prescription that employs higher mass loading factors for lower mass galaxies. Typical H I absorbers trace unenriched ambient material that is not participating in the baryon cycle, but stronger H I absorbers arise in cool, enriched inflowing gas. Instantaneous radial velocity measures of absorbers are generally poor at distinguishing between inflowing and outflowing gas, except in the case of very recent outflows. These results suggest that probing halo gas using a range of absorbers can provide detailed information about the amount and physical conditions of material that is participating in the baryon cycle.

  18. Predicting accurate line shape parameters for CO2 transitions

    NASA Astrophysics Data System (ADS)

    Gamache, Robert R.; Lamouroux, Julien

    2013-11-01

    The vibrational dependence of CO2 half-widths and line shifts are given by a modification of the model proposed by Gamache and Hartmann [Gamache R, Hartmann J-M. J Quant Spectrosc Radiat Transfer 2004;83:119]. This model allows the half-widths and line shifts for a ro-vibrational transition to be expressed in terms of the number of vibrational quanta exchanged in the transition raised to a power and a reference ro-vibrational transition. Calculations were made for 24 bands for lower rotational quantum numbers from 0 to 160 for N2-, O2-, air-, and self-collisions with CO2. These data were extrapolated to J″=200 to accommodate several databases. Comparison of the CRB calculations with measurement gives very high confidence in the data. In the model a Quantum Coordinate is defined by (c1 |Δν1|+c2 |Δν2|+c3|Δν3|)p. The power p is adjusted and a linear least-squares fit to the data by the model expression is made. The procedure is iterated on the correlation coefficient, R, until [|R|-1] is less than a threshold. The results demonstrate the appropriateness of the model. The model allows the determination of the slope and intercept as a function of rotational transition, broadening gas, and temperature. From the data of the fits, the half-width, line shift, and the temperature dependence of the half-width can be estimated for any ro-vibrational transition, allowing spectroscopic CO2 databases to have complete information for the line shape parameters.

  19. Absorption line metrology by optical feedback frequency-stabilized cavity ring-down spectroscopy

    NASA Astrophysics Data System (ADS)

    Burkart, Johannes; Kassi, Samir

    2015-04-01

    Optical feedback frequency-stabilized cavity ring-down spectroscopy (OFFS-CRDS) is a near-shot-noise-limited technique combining a sensitivity of with a highly linear frequency axis and sub-kHz resolution. Here, we give an in-depth review of the key elements of the experimental setup encompassing a highly stable V-shaped reference cavity, an integrated Mach-Zehnder modulator and a tightly locked ring-down cavity with a finesse of 450,000. Carrying out a detailed analysis of the spectrometer performance and its limitations, we revisit the photo-electron shot-noise limit in CRDS and discuss the impact of optical fringes. We demonstrate different active schemes for fringe cancelation by varying the phase of parasitic reflections. The proof-of-principle experiments reported here include a broadband high-resolution spectrum of carbon dioxide at 1.6 µm and an isolated line-shape measurement with a signal-to-noise ratio of 80,000. Beyond laboratory-based absorption line metrology for fundamental research, OFFS-CRDS holds a considerable potential for field laser measurements of trace gas concentrations and isotopic ratios by virtue of its small sample volume and footprint, the robust cavity-locking scheme and supreme precision.

  20. Observation of Fano line shapes in infrared vibrational spectra of CO2 adsorbed on Cu(997) and Cu(111).

    PubMed

    Koitaya, Takanori; Shiozawa, Yuichiro; Mukai, Kozo; Yoshimoto, Shinya; Yoshinobu, Jun

    2016-02-01

    Adsorption states of carbon dioxide on the Cu(997) and Cu(111) surfaces were investigated by infrared reflection absorption spectroscopy, temperature programmed desorption, and X-ray photoelectron spectroscopy. CO2 molecules are physisorbed on the Cu(997) surface at temperatures below 70 K; neither chemisorption nor dissociation of CO2 occurs on the Cu(997) surface at this low temperature. However, the vibrational spectra of adsorbed CO2 depend significantly on the substrate temperature and coverage. IR spectra of CO2 vibrational modes at 70 K show asymmetric Fano line shapes, while only normal absorption bands are observed when CO2 is adsorbed at 20 K. Fano line shapes are also observed for CO2 on Cu(111) at 85 K. The observation of Fano effect indicates the coupling between the electronic continuum states of the Cu surface and the internal vibrational modes of CO2 even in such physisorbed system. PMID:26851930

  1. Observation of Fano line shapes in infrared vibrational spectra of CO2 adsorbed on Cu(997) and Cu(111)

    NASA Astrophysics Data System (ADS)

    Koitaya, Takanori; Shiozawa, Yuichiro; Mukai, Kozo; Yoshimoto, Shinya; Yoshinobu, Jun

    2016-02-01

    Adsorption states of carbon dioxide on the Cu(997) and Cu(111) surfaces were investigated by infrared reflection absorption spectroscopy, temperature programmed desorption, and X-ray photoelectron spectroscopy. CO2 molecules are physisorbed on the Cu(997) surface at temperatures below 70 K; neither chemisorption nor dissociation of CO2 occurs on the Cu(997) surface at this low temperature. However, the vibrational spectra of adsorbed CO2 depend significantly on the substrate temperature and coverage. IR spectra of CO2 vibrational modes at 70 K show asymmetric Fano line shapes, while only normal absorption bands are observed when CO2 is adsorbed at 20 K. Fano line shapes are also observed for CO2 on Cu(111) at 85 K. The observation of Fano effect indicates the coupling between the electronic continuum states of the Cu surface and the internal vibrational modes of CO2 even in such physisorbed system.

  2. Shaping of broad IR absorption in proton transfer equilibrating OH⋯N hydrogen bonded systems

    NASA Astrophysics Data System (ADS)

    Schreiber, V. M.; Rospenk, M.; Kulbida, A. I.; Sobczyk, L.

    1997-10-01

    The temperature dependence of UV and IR absorption spectra of chlorophenols with tributylamine (TBA) were studied in solution and in low temperature matrices. The UV spectra allowed us to estimate the proton transfer (PT) equilibrium constants and thermodynamic parameters for this process. A strong negative entropy effect was confirmed. In cases when proton transfer species are detected in UV spectrum, a frequency broad absorption below 700 cm -1 usually appears, which we ascribe to non-aggregated species. The potential energy curve for the proton motion is then characterized most probably by a low lying second minimum or a shoulder. The increase of charge separation evoked by aggregation or by enhancement of solvent polarity leads to disappearance of low frequency wing of broad absorption. The involvement of low frequency modes of TBA and phenol moieties, particularly bending δCNC and δNCC modes in shaping of the low frequency part of broad absorption was shown.

  3. Studying Velocity Turbulence from Doppler-broadened Absorption Lines: Statistics of Optical Depth Fluctuations

    SciTech Connect

    Lazarian, A.; Pogosyan, D.

    2008-10-10

    We continue our work on developing techniques for studying turbulence with spectroscopic data. We show that Doppler-broadened absorption spectral lines, in particular, saturated absorption lines, can be used within the framework of the previously introduced technique termed the velocity coordinate spectrum (VCS). The VCS relates the statistics of fluctuations along the velocity coordinate to the statistics of turbulence; thus, it does not require spatial coverage by sampling directions in the plane of the sky. We consider lines with different degree of absorption and show that for lines of optical depth less than one, our earlier treatment of the VCS developed for spectral emission lines is applicable, if the optical depth is used instead of intensity. This amounts to correlating the logarithms of absorbed intensities. For larger optical depths and saturated absorption lines, we show that only wings of the line are available for the analysis. In terms of the VCS formalism, this results in introducing an additional window, whose size decreases with the increase of the optical depth. As a result, strongly saturated absorption lines only carry the information about the small-scale turbulence. Nevertheless, the contrast of the fluctuations corresponding to the small-scale turbulence increases with the increase of the optical depth, which provides advantages for studying turbulence by combining lines with different optical depths. By combining different absorption lines one can develop a tomography of the turbulence in the interstellar gas in all its complexity.

  4. What Drives the Outflows in Broad Absorption Line QSOs?

    NASA Technical Reports Server (NTRS)

    Begelman, Mitchell C.

    1997-01-01

    We have made progress in the areas related to the propulsion and confinement of gas responsible for broad absorption troughts in QSOs: Radiative Acceleration in BALQSOs; The "Ghost" of Lyman (alpha); and Magnetic Confinement of Absorbing Gas.

  5. The Hubble Space Telescope Quasar Absorption Line Key Project: The Unusual Absorption-Line System in the Spectrum of PG 2302+029--Ejected or Intervening?

    NASA Technical Reports Server (NTRS)

    Jannuzi, B. T.; Hartig, G. F.; Kirhakos, S.; Sargent, W. L. W.; Turnshek, D. A.; Weymann, R. J.; Bahcall, J. N.; Bergeron, J.; Boksenberg, A.; Savage, B. D.; Schneider, D. P.; Wolfe, A. M.

    1996-01-01

    We report the discovery of a high-ionization broad absorption line system at a redshift of z(sub abs) = 0.695 in the spectrum of the z(sub em) = 1.052 radio-quiet quasar PG 2302+029. Broad absorption with FWHM from 3000 to 5000 km/s is detected from C iv, N v, and O vi in Hubble Space Telescope (HST) Faint Object Spectrograph spectra of the quasar. A narrow-line system (FWHM approx. 250 km/s) at z(sub abs) = 0.7016 is resolved from the broad blend and includes absorption by Ly alpha and the C iv, N v, and O vi doublets. No absorption by low-ionization metal species (e.g., Si II and Mg II) is detected in the HST or ground-based spectra for either the broad or the narrow system. The centroids of the broad system lines are displaced by approx. 56,000 km/s to the blue of the quasar's broad emission lines. The reddest extent of the broad-line absorption is more than 50,000 km/s from the quasar. The properties of this system are unprecedented, whether it is an intervening or an ejected system.

  6. High resolution gamma-ray astronomy - Observations and predictions of line shapes

    NASA Technical Reports Server (NTRS)

    Bhattacharya, Dipen; Gehrels, Neil

    1991-01-01

    The shapes of gamma-ray lines carry unique information about the physical processes and conditions in astrophysical sites. Galactic center and SN 1987A lines have been observationally resolved allowing their shapes to be studied. There are also significant new theoretical results concerning line shapes from Type I supernovae, supernova remnants and the interstellar medium. New work is presented on a simple treatment of line profiles for rotating disks and spherical shells.

  7. Absorption Efficiencies of Forsterite. I: DDA Explorations in Grain Shape and Size

    NASA Technical Reports Server (NTRS)

    Lindsay, Sean S.; Wooden, Diane; Harker, David E.; Kelley, Michael S.; Woodward, Charles E.; Murphy, Jim R.

    2013-01-01

    We compute the absorption efficiency (Q(sub abs)) of forsterite using the discrete dipole approximation (DDA) in order to identify and describe what characteristics of crystal grain shape and size are important to the shape, peak location, and relative strength of spectral features in the 8 - 40 micron wavelength range. Using the DDSCAT code, we compute Q(sub abs) for non-spherical polyhedral grain shapes with a(sub eff) = 0.1 micron. The shape characteristics identified are: 1) elongation/reduction along one of three crystallographic axes; 2) asymmetry, such that all three crystallographic axes are of different lengths; and 3) the presence of crystalline faces that are not parallel to a specific crystallographic axis, e.g., non-rectangular prisms and (di)pyramids. Elongation/reduction dominates the locations and shapes of spectral features near 10, 11, 16, 23.5, 27, and 33.5 micron, while asymmetry and tips are secondary shape effects. Increasing grain sizes (0.1 - 1.0 micron) shifts the 10, 11 micron features systematically towards longer wavelengths and relative to the 11 micron feature increases the strengths and slightly broadens the longer wavelength features. Seven spectral shape classes are established for crystallographic a-, b-, and c-axes and include columnar and platelet shapes plus non-elongated or equant grain shapes. The spectral shape classes and the effects of grain size have practical application in identifying or excluding columnar, platelet or equant forsterite grain shapes in astrophysical environs. Identification of the shape characteristics of forsterite from 8 - 40 micron spectra provides a potential means to probe the temperatures at which forsterite formed.

  8. ABSORPTION EFFICIENCIES OF FORSTERITE. I. DISCRETE DIPOLE APPROXIMATION EXPLORATIONS IN GRAIN SHAPE AND SIZE

    SciTech Connect

    Lindsay, Sean S.; Wooden, Diane H.; Harker, David E.; Kelley, Michael S.; Woodward, Charles E.; Murphy, Jim R. E-mail: diane.h.wooden@nasa.gov E-mail: msk@astro.umd.edu E-mail: murphy@nmsu.edu

    2013-03-20

    We compute the absorption efficiency (Q{sub abs}) of forsterite using the discrete dipole approximation in order to identify and describe what characteristics of crystal grain shape and size are important to the shape, peak location, and relative strength of spectral features in the 8-40 {mu}m wavelength range. Using the DDSCAT code, we compute Q{sub abs} for non-spherical polyhedral grain shapes with a{sub eff} = 0.1 {mu}m. The shape characteristics identified are (1) elongation/reduction along one of three crystallographic axes; (2) asymmetry, such that all three crystallographic axes are of different lengths; and (3) the presence of crystalline faces that are not parallel to a specific crystallographic axis, e.g., non-rectangular prisms and (di)pyramids. Elongation/reduction dominates the locations and shapes of spectral features near 10, 11, 16, 23.5, 27, and 33.5 {mu}m, while asymmetry and tips are secondary shape effects. Increasing grain sizes (0.1-1.0 {mu}m) shifts the 10 and 11 {mu}m features systematically toward longer wavelengths and relative to the 11 {mu}m feature increases the strengths and slightly broadens the longer wavelength features. Seven spectral shape classes are established for crystallographic a-, b-, and c-axes and include columnar and platelet shapes plus non-elongated or equant grain shapes. The spectral shape classes and the effects of grain size have practical application in identifying or excluding columnar, platelet, or equant forsterite grain shapes in astrophysical environs. Identification of the shape characteristics of forsterite from 8 to 40 {mu}m spectra provides a potential means to probe the temperatures at which forsterite formed.

  9. Effect of interdiffusion on nonlinear intraband light absorption in Gaussian-shaped double quantum rings

    NASA Astrophysics Data System (ADS)

    Aziz-Aghchegala, V. L.; Mughnetsyan, V. N.; Kirakosyan, A. A.

    2015-06-01

    The effect of interdiffusion on electronic states and nonlinear light absorption in Gaussian-shaped double quantum rings is studied. The confining potential, electron energy spectrum, wave functions and absorption coefficient are obtained for different values of diffusion parameter. The effect of the variation of Gaussian parameters is considered as well. The selection rules for the intraband transitions in the cases of the light polarization parallel and perpendicular to the quantum rings' axis are obtained. It is shown that the interdiffusion can be used as an effective tool for the purposeful manipulation of the electric and optical properties of the considered structure.

  10. Is there a connection between broad absorption line quasars and narrow-line Seyfert 1 galaxies?

    SciTech Connect

    Grupe, Dirk; Nousek, John A.

    2015-02-01

    We consider whether broad absorption line quasars (BAL QSOs) and narrow-line Seyfert 1 galaxies (NLS1s) are similar, as suggested by Brandt and Gallagher and Boroson. For this purpose, we constructed a sample of 11 BAL QSOs from existing Chandra and Swift observations. We found that BAL QSOs and NLS1s both operate at high Eddington ratios L/L{sub Edd}, although BAL QSOs have slightly lower L/L{sub Edd}. BAL QSOs and NLS1s in general have high Fe ii/Hβ and low [O iii]/Hβ ratios following the classic “Boroson and Green” eigenvector 1 relation. We also found that the mass accretion rates M-dot of BAL QSOs and NLS1s are more similar than previously thought, although some BAL QSOs exhibit extreme mass accretion rates of more than 10 M{sub ⊙} yr{sup −1}. These extreme mass accretion rates may suggest that the black holes in BAL QSOs are relativistically spinning. Black hole masses in BAL QSOs are a factor of 100 larger than NLS1s. From their location on a M−σ plot, we find that BAL QSOs contain fully developed black holes. Applying a principal component analysis to our sample, we find eigenvector 1 to correspond to the Eddington ratio L/L{sub Edd}, and eigenvector 2 to black hole mass.

  11. Is There a Connection between Broad Absorption Line Quasars and Narrow-Line Seyfert 1 Galaxies?

    NASA Astrophysics Data System (ADS)

    Grupe, Dirk; Nousek, John. A.

    2015-02-01

    We consider whether broad absorption line quasars (BAL QSOs) and narrow-line Seyfert 1 galaxies (NLS1s) are similar, as suggested by Brandt & Gallagher and Boroson. For this purpose, we constructed a sample of 11 BAL QSOs from existing Chandra and Swift observations. We found that BAL QSOs and NLS1s both operate at high Eddington ratios L/{{L}Edd}, although BAL QSOs have slightly lower L/{{L}Edd}. BAL QSOs and NLS1s in general have high Fe ii/Hβ and low [O iii]/Hβ ratios following the classic “Boroson & Green” eigenvector 1 relation. We also found that the mass accretion rates \\dot{M} of BAL QSOs and NLS1s are more similar than previously thought, although some BAL QSOs exhibit extreme mass accretion rates of more than 10 {{M}⊙ } yr-1. These extreme mass accretion rates may suggest that the black holes in BAL QSOs are relativistically spinning. Black hole masses in BAL QSOs are a factor of 100 larger than NLS1s. From their location on a M-σ plot, we find that BAL QSOs contain fully developed black holes. Applying a principal component analysis to our sample, we find eigenvector 1 to correspond to the Eddington ratio L/{{L}Edd}, and eigenvector 2 to black hole mass.

  12. Annular shape silver lined proportional counter for on-line pulsed neutron yield measurement

    NASA Astrophysics Data System (ADS)

    Dighe, P. M.; Das, D.

    2015-04-01

    An annular shape silver lined proportional counter is developed to measure pulsed neutron radiation. The detector has 314 mm overall length and 235 mm overall diameter. The central cavity of 150 mm diameter and 200 mm length is used for placing the neutron source. Because of annular shape the detector covers >3π solid angle of the source. The detector has all welded construction. The detector is developed in two halves for easy mounting and demounting. Each half is an independent detector. Both the halves together give single neutron pulse calibration constant of 4.5×104 neutrons/shot count. The detector operates in proportional mode which gives enhanced working conditions in terms of dead time and operating range compared to Geiger Muller based neutron detectors.

  13. Evidence for Active Galactic Nucleus Feedback in the Broad Absorption Lines and Reddening of Mrk 231

    NASA Astrophysics Data System (ADS)

    Leighly, Karen M.; Terndrup, Donald M.; Baron, Eddie; Lucy, Adrian B.; Dietrich, Matthias; Gallagher, Sarah C.

    2014-06-01

    We present the first J-band spectrum of Mrk 231, which reveals a large He I* λ10830 broad absorption line with a profile similar to that of the well-known Na I broad absorption line. Combining this spectrum with optical and UV spectra from the literature, we show that the unusual reddening noted by Veilleux et al. is explained by a reddening curve like those previously used to explain low values of total-to-selective extinction in Type Ia supernovae. The nuclear starburst may be the origin and location of the dust. Spatially resolved emission in the broad absorption line trough suggests nearly full coverage of the continuum emission region. The broad absorption lines reveal higher velocities in the He I* lines (produced in the quasar-photoionized H II region) compared with the Na I and Ca II lines (produced in the corresponding partially ionized zone). Cloudy simulations show that a density increase is required between the H II and partially ionized zones to produce ionic column densities consistent with the optical and IR absorption line measurements and limits, and that the absorber lies ~100 pc from the central engine. These results suggest that the He I* lines are produced in an ordinary quasar BAL wind that impacts upon, compresses, and accelerates the nuclear starburst's dusty effluent (feedback in action), and the Ca II and Na I lines are produced in this dusty accelerated gas. This unusual circumstance explains the rarity of Na I absorption lines; without the compression along our line of sight, Mrk 231 would appear as an ordinary iron low-ionization, broad absorption line quasar.

  14. Foreign-gas broadening of nitrous oxide absorption lines.

    NASA Technical Reports Server (NTRS)

    Tubbs, L. D.; Williams, D.

    1972-01-01

    We have measured the foreign-gas broadening coefficients for collisional broadening of lines in the nu-3 fundamental of N2O by He, Ne, Ar, Kr, Xe, H2, D2, and CH4. These coefficients, which give the ratio of the line-broadening ability of these gases to the line-broadening ability of N2, can be used with recent measurements and calculations of N2 broadening to obtain optical collision cross sections.

  15. Line shape analysis of two-dimensional infrared spectra

    PubMed Central

    Guo, Qi; Pagano, Philip; Li, Yun-Liang; Kohen, Amnon; Cheatum, Christopher M.

    2015-01-01

    Ultrafast two-dimensional infrared (2D IR) spectroscopy probes femtosecond to picosecond time scale dynamics ranging from solvation to protein motions. The frequency-frequency correlation function (FFCF) is the quantitative measure of the spectral diffusion that reports those dynamics and, within certain approximations, can be extracted directly from 2D IR line shapes. A variety of methods have been developed to extract the FFCF from 2D IR spectra, which, in principle, should give the same FFCF parameters, but the complexity of real experimental systems will affect the results of these analyses differently. Here, we compare five common analysis methods using both simulated and experimental 2D IR spectra to understand the effects of apodization, anharmonicity, phasing errors, and finite signal-to-noise ratios on the results of each of these analyses. Our results show that although all of the methods can, in principle, yield the FFCF under idealized circumstances, under more realistic experimental conditions they behave quite differently, and we find that the centerline slope analysis yields the best compromise between the effects we test and is most robust to the distortions that they cause. PMID:26049447

  16. Brain blood vessel segmentation using line-shaped profiles

    NASA Astrophysics Data System (ADS)

    Babin, Danilo; Pižurica, Aleksandra; De Vylder, Jonas; Vansteenkiste, Ewout; Philips, Wilfried

    2013-11-01

    Segmentation of cerebral blood vessels is of great importance in diagnostic and clinical applications, especially for embolization of cerebral aneurysms and arteriovenous malformations (AVMs). In order to perform embolization of the AVM, the structural and geometric information of blood vessels from 3D images is of utmost importance. For this reason, the in-depth segmentation of cerebral blood vessels is usually done as a fusion of different segmentation techniques, often requiring extensive user interaction. In this paper we introduce the idea of line-shaped profiling with an application to brain blood vessel and AVM segmentation, efficient both in terms of resolving details and in terms of computation time. Our method takes into account both local proximate and wider neighbourhood of the processed pixel, which makes it efficient for segmenting large blood vessel tree structures, as well as fine structures of the AVMs. Another advantage of our method is that it requires selection of only one parameter to perform segmentation, yielding very little user interaction.

  17. Ugo Fano, Enrico Fermi, and spectral line shapes

    NASA Astrophysics Data System (ADS)

    Clark, Charles W.

    2005-03-01

    Ugo Fano's 1961 paper on spectral line shapes^1 was recently ranked as the third highest in citation impact of all papers published in the entire Physical Review series.^2 In the course of preparing an article for a NIST Centennial volume,^3 I became interested in the history of the results presented in Fano’s seminal paper, and will present my findings in this talk. An amusing sidelight concerns the role played by Enrico Fermi in the development of the famous ``Fano profile'' formula. I had been told this story by Fano when I was his graduate student, but uncertain of my recollection of the details, I did not publish it in his obituary.^4 I later learned that the archives of the Royal Society of London contain Fano's own written version of the tale, which will be presented in this talk. The story sheds light on the nature of Enrico Fermi's interactions with his students, and confirms accounts concerning the way in which he did his theoretical work.^5 ^1 U. Fano,``Effects of Configuration Interaction on Intensities and Phase Shifts,'' Phys. Rev. 124, 1866-1878 (1961)^2 S. Redner, physics/0407137 (2004)^3 http://nvl.nist.gov/pub/nistpubs/sp958-lide/116-119.pdf^4 C. W. Clark, Nature 410, 164 (2001)^5 F. Rasetti, in Collected Papers, vol. I, E. Fermi (University of Chicago Press, 1962), p. 178

  18. Extended Pre-Transit Structures and the Exosphere Detected for HD189733b in Optical Hydrogen Balmer Line Absorption

    NASA Astrophysics Data System (ADS)

    Redfield, Seth; Cauley, P. Wilson; Jensen, Adam G.; Barman, Travis; Endl, Michael; Cochran, William

    2015-12-01

    We present two separate observations of HD189733b in the three strongest hydrogen Balmer lines (H-alpha, H-beta, and H-gamma), with HiRES on Keck I that show definitive in-transit absorption, confirming the detection with the HET by Jensen et al. (2012), as well as, significant pre-transit absorption. Recently, pre-transit absorption in UV metal transitions of the hot Jupiter exoplanets HD 189733b and WASP12-b have been interpreted as being caused by material compressed in a planetary bow shock, however our observations are the first to densely time-sample and redundantly detect these extended planetary structures. While our first observations (obtained in 2013 and presented in Cauley et al. 2015), were consistent with a bow shock, our subsequent observation taken in August 2015 show pre-transit absorption but with a pattern that is inconsistent with the 2013 model. Instead, the observations indicate significant variability in the strength and timing of the pre-transit absorption. We also find differences in the strength of the in-transit exospheric absorption as well. These changes could be indicative of variability in the extreme stellar wind properties found at just 8 stellar radii, which could drive the extended atmospheric interaction between star and planet. The pre-transit absorption in 2013 was first observed 65 minutes prior to transit (corresponding to a linear distance of ~7 planetary radii), although it could have started earlier. The pre-transit signal in 2015, which is well sampled, is first detected 165 minutes prior to transit (a linear distance of ~17 planetary radii). The line shape of the pre-transit feature and the shape of the time series absorption provide the strongest constraints on the morphology and physical characteristics of extended structures around the exoplanet. The absorption strength observed in the Balmer lines indicates an optically thick, but physically small, geometry. If part of this extended structure is a bow shock mediated

  19. Effect of a progressive sound wave on the profiles of spectral lines. 2: Asymmetry of faint Fraunhofer lines. [absorption spectra

    NASA Technical Reports Server (NTRS)

    Kostyk, R. I.

    1974-01-01

    The absorption coefficient profile was calculated for lines of different chemical elements in a medium with progressive sound waves. Calculations show that (1) the degree and direction of asymmetry depend on the atomic ionization potential and the potential of lower level excitation of the individual line; (2) the degree of asymmetry of a line decreases from the center toward the limb of the solar disc; and (3) turbulent motions 'suppress' the asymmetry.

  20. Radio line and continuum observations of quasar-galaxy pairs and the origin of low reshift quasar absorption line systems

    NASA Technical Reports Server (NTRS)

    Carilli, C. L.; Vangorkom, J. H.; Hauxthausen, E. M.; Stocke, J. T.; Salzer, J.

    1990-01-01

    There are a number of known quasars for which our line of sight to the high redshift quasar passes within a few Holmberg radii of a low redshift galaxy. In a few of these cases, spectra of the quasar reveal absorption by gas associated with the low redshift galaxy. A number of these pairs imply absorption by gas which lies well outside the optical disk of the associated galaxy, leading to models of galaxies with 'halos' or 'disks' of gas extending to large radii. The authors present observations of 4 such pairs. In three of the four cases, they find that the associated galaxy is highly disturbed, typically due to a gravitational interaction with a companion galaxy, while in the fourth case the absorption can be explained by clouds in the optical disk of the associated galaxy. They are led to an alternative hypothesis concerning the origin of the low redshift absorption line systems: the absorption is by gas clouds which have been gravitationally stripped from the associated galaxy. These galaxies are rapidly evolving, and should not be used as examples of absorption by clouds in halos of field spirals. The authors conclude by considering the role extended gas in interacting systems plays in the origin of higher redshift quasar absorption line systems.

  1. Gamma–Gamma Absorption in the Broad Line Region Radiation Fields of Gamma-Ray Blazars

    NASA Astrophysics Data System (ADS)

    Böttcher, Markus; Els, Paul

    2016-04-01

    The expected level of γγ absorption in the Broad Line Region (BLR) radiation field of γ-ray loud Flat Spectrum Radio Quasars (FSRQs) is evaluated as a function of the location of the γ-ray emission region. This is done self-consistently with parameters inferred from the shape of the spectral energy distribution (SED) in a single-zone leptonic EC-BLR model scenario. We take into account all geometrical effects both in the calculation of the γγ opacity and the normalization of the BLR radiation energy density. As specific examples, we study the FSRQs 3C279 and PKS 1510-089, keeping the BLR radiation energy density at the location of the emission region fixed at the values inferred from the SED. We confirm previous findings that the optical depth due to γγ absorption in the BLR radiation field exceeds unity for both 3C279 and PKS 1510-089 for locations of the γ-ray emission region inside the inner boundary of the BLR. It decreases monotonically, with distance from the central engine and drops below unity for locations within the BLR. For locations outside the BLR, the BLR radiation energy density required for the production of GeV γ-rays rapidly increases beyond observational constraints, thus making the EC-BLR mechanism implausible. Therefore, in order to avoid significant γγ absorption by the BLR radiation field, the γ-ray emission region must therefore be located near the outer boundary of the BLR.

  2. Ultrafast transient absorption studies of hematite nanoparticles: the effect of particle shape on exciton dynamics.

    PubMed

    Fitzmorris, Bob C; Patete, Jonathan M; Smith, Jacqueline; Mascorro, Xiomara; Adams, Staci; Wong, Stanislaus S; Zhang, Jin Z

    2013-10-01

    Much progress has been made in using hematite (α-Fe2 O3 ) as a potentially practical and sustainable material for applications such as solar-energy conversion and photoelectrochemical (PEC) water splitting; however, recent studies have shown that the performance can be limited by a very short charge-carrier diffusion length or exciton lifetime. In this study, we performed ultrafast studies on hematite nanoparticles of different shapes to determine the possible influence of particle shape on the exciton dynamics. Nanorice, multifaceted spheroidal nanoparticles, faceted nanocubes, and faceted nanorhombohedra were synthesized and characterized by using SEM and XRD techniques. Their exciton dynamics were investigated by using femtosecond transient absorption (TA) spectroscopy. Although the TA spectral features differ for the four samples studied, their decay profiles are similar, which can be fitted with time constants of 1-3 ps, approximately 25 ps, and a slow nanosecond component extending beyond the experimental time window that was measured (2 ns). The results indicate that the overall exciton lifetime is weakly dependent on the shape of the hematite nanoparticles, even though the overall optical absorption and scattering are influenced by the particle shape. This study suggests that other strategies need to be developed to increase the exciton lifetime or to lengthen the exciton diffusion length in hematite nanostructures. PMID:24058060

  3. X-ray Emission and Absorption Lines During the SSS Phase of RS Ophiuchi

    NASA Astrophysics Data System (ADS)

    Schönrich, R. A.; Ness, J.-U.

    2008-12-01

    The high-resolution X-ray spectra of the sixth outburst of RS Ophiuchi revealed P Cygni-like line profiles. We use the column densities of selected isolated absorption lines to derive the nitrogen-to-oxygen abundance ratio. We next discuss the origin of the emission lines, which may originate from the shock, and the absorption and emission lines may thus have a different formation history. Finally, we discuss the correlation of high-amplitude variability detected during the early SSS phase with variability in the hardness ratio that follows the same pattern but is shifted by 1000~sec.

  4. - and Air-Broadened Line Shape Parameters of 12CH_4 : 4500-4620 CM-1

    NASA Astrophysics Data System (ADS)

    Devi, V. Malathy; Benner, D. Chris; Sung, Keeyoon; Brown, Linda; Crawford, Timothy J.; Smith, Mary Ann H.; Mantz, Arlan; Predoi-Cross, Adriana

    2014-06-01

    Accurate knowledge of spectral line shape parameters is important for infrared transmission and radiance calculations in the terrestrial atmosphere. We report the self- and air-broadened Lorentz widths, shifts and line mixing coefficients along with their temperature dependences for methane absorption lines in the 2.2 μm spectral region. For this, we obtained a series of high-resolution, high S/N spectra of 99.99% 12C-enriched samples of pure methane and its dilute mixtures in dry air at cold temperatures down to 150 K using the Bruker IFS 125HR Fourier transform spectrometer at JPL. The coolable absorption cell had an optical path of 20.38 cm and was specially built to reside inside the sample compartment of the Bruker FTS. The 13 spectra used in the analysis consisted of seven pure 12CH_4 spectra at pressures from 4.5 to 169 Torr and six air-broadened spectra with total sample pressures of 113-300 Torr and methane volume mixing ratios between 4 and 9.7%. These 13 spectra were fit simultaneously using the multispectrum least-squares fitting technique. The results will be compared to existing values reported in the literature. K. Sung, A. W. Mantz, L. R. Brown, et al., J. Mol. Spectrosc., 162 (2010) 124-134. D. C. Benner, C. P. Rinsland, V. Malathy Devi, M. A. H. Smith and D. Atkins, JQSRT, 53 (1995) 705-721. Research described in this paper was performed at Connecticut College, the College of William and Mary, NASA Langley Research Center and the Jet Propulsion Laboratory, California Institute of Technology, under contracts and cooperative agreements with the National Aeronautics and Space Administration.

  5. Probing low-redshift galaxies using quasar absorption lines with an emphasis on Ca II absorption

    NASA Astrophysics Data System (ADS)

    Sardane, Gendith M.

    We searched for intervening CaII absorption in nearly 95,000 quasar spectra with i≤20 from the Sloan Digital Sky Survey(SDSS) data releases DR7+DR9. Our identification of >400 CaII systems is the largest compilation of CaII absorbers in a blind search. (Abstract shortened by ProQuest.).

  6. Spectral line-shapes investigation with Pound-Drever-Hall-locked frequency-stabilized cavity ring-down spectroscopy

    NASA Astrophysics Data System (ADS)

    Cygan, A.; Wójtewicz, S.; Domysławska, J.; Masłowski, P.; Bielska, K.; Piwiński, M.; Stec, K.; Trawiński, R. S.; Ozimek, F.; Radzewicz, C.; Abe, H.; Ido, T.; Hodges, J. T.; Lisak, D.; Ciuryło, R.

    2013-10-01

    A review of recent experiments involving a newly developed Pound-Drever-Hall-locked frequency-stabilized cavity ring-down spectroscopy (PDH-locked FS-CRDS) system is presented. By comparison to standard FS-CRDS, the PDH lock of the probe laser to the ring-down cavity optimized coupling into the cavity, thus increasing the ring-down signal acquisition rate nearly 300-fold to 14 kHz and reducing the noise-equivalent absorption coefficient by more than an order of magnitude to 7 × 10-11 cm-1. We discuss how averaging approximately 1000 spectra yielded a signal-to-noise ratio of 220000. We also discuss how the spectrum frequency axis was linked to an optical frequency comb, thus enabling absolute frequency measurements of molecular optical transitions at sub-MHz levels. Applications of the spectrometer to molecular line-shape studies are also presented. For these investigations, we use semi-classical line-shape models that consider the influence of Dicke narrowing as well as the speed dependence of the pressure broadening and shifting to fit spectra. We show that the improved precision and spectrum fidelity of the spectrometer enable precise determinations of line-shape parameters. We also discuss the importance of line-shape analysis with regard to the development of new spectroscopic databases as well as in the optical determination of the Boltzmann constant.

  7. CRIRES spectroscopy and empirical line-by-line identification of FeH molecular absorption in an M dwarf

    NASA Astrophysics Data System (ADS)

    Wende, S.; Reiners, A.; Seifahrt, A.; Bernath, P. F.

    2010-11-01

    Molecular FeH provides a large number of sharp and isolated absorption lines that can be used to measure radial velocity, rotation, or magnetic field strength with high accuracy. Our aim is to provide an FeH atlas for M-type stars in the spectral region from 986 nm to 1077 nm (Wing-Ford band). To identify these lines in CRIRES spectra of the magnetically inactive, slowly rotating, M5.5 dwarf GJ1002, we calculated model spectra for the selected spectral region with theoretical FeH line data. In general this line list agrees with the observed data, but several individual lines differ significantly in position or in line strength. After identification of as many as possible FeH lines, we corrected the line data for position and line strength to provide an accurate atlas of FeH absorption lines for use in high precision spectroscopy of low mass stars. For all lines, we used a Voigt function to obtain their positions and equivalent widths. Identification with theoretical lines was done by hand. For confirmation of the identified lines, we used statistical methods, cross-correlation techniques, and line intensities. Eventually, we were able to identify FeH lines from the (0,0), (1,0), (1,1), (2,1), (2,2), (3,2), and (4,3) vibrational bands in the observed spectra and correct the positions of the lines if necessary. The deviations between theoretical and observed positions follow a normal distribution approximately around zero. In order to empirically correct the line strength, we determined Teff, instrumental broadening (rotational broadening) and a van der Waals enhancement factor for the FeH lines in GJ1002. We also give the scaling factors for the Einstein A values to correct the line strengths. With the identified lines, we derived rotational temperatures from the line intensities for GJ1002. We conclude that FeH lines can be used for a wide variety of applications in astrophysics. With the identified lines it will be possible for example to characterize magnetically

  8. Line Positions, Intensities And Line Shape Parameters Of PH3 Near 4.4 µm

    NASA Astrophysics Data System (ADS)

    Venkataraman, Malathy; Benner, D. C.; Kleiner, I.; Brown, L. R.; Sams, R. L.; Fletcher, L. N.

    2012-10-01

    Accurate knowledge of spectral line parameters in the 2000 to 2400 cm-1 region of PH3 is important for the CASSINI/VIMS exploration of dynamics and chemistry of Saturn and for the correct interpretation of future Jovian observations by JUNO and ESA’s newly-selected mission JUICE. Since the available intensity information for phosphine is inconsistent, we measured line positions and intensities for over 4000 individual transitions in the 2ν2, ν2+ν4, 2ν4, ν1 and the ν3 bands from analyzing high-resolution, high S/N spectra recorded at room temperature using two Fourier transform spectrometers (FTS); the Bruker IFS 125 HR FTS at PNNL and the Kitt Peak FTS at the National Solar Observatory in Arizona. In addition to line positions and intensities, self-broadened half width and self-induced pressure-shift coefficients were also measured for about 800 transitions for the various bands. The strong Coriolis and other types of interactions occurring among the various vibrational levels result in a large number of forbidden transitions as well as cause A+A- splittings in transitions with K″ that are multiples of 3. Line mixing was detected between several A+A- pairs of transitions; and self- line mixing coefficients were measured for several such pairs of transitions by applying the off-diagonal relaxation matrix formalism of Levy et al.1 A multispectrum nonlinear least squares technique2 employing a non-Voigt line shape including line mixing and speed dependence was used in fitting all the spectra simultaneously. Present results are compared with other reported values. This research is supported by NASA’s Outer Planets Research Program. References [1] A. Lévy et al., In “Spectroscopy of the Earth’s Atmosphere and Interstellar Medium”, Ed. K, Narahari Rao and A. Weber, Boston, Academic Press; p, 261-337 (1992). [2] D. C. Benner et al., J Quant. Spectrosc. Radiat. Transfer 53, 705, 1995.

  9. On-Line Wavelength Calibration of Pulsed Laser for CO2 Differential Absorption LIDAR

    NASA Astrophysics Data System (ADS)

    Xiang, Chengzhi; Ma, Xin; Han, Ge; Liang, Ailin; Gong, Wei

    2016-06-01

    Differential absorption lidar (DIAL) remote sensing is a promising technology for atmospheric CO2 detection. However, stringent wavelength accuracy and stability are required in DIAL system. Accurate on-line wavelength calibration is a crucial procedure for retrieving atmospheric CO2 concentration using the DIAL, particularly when pulsed lasers are adopted in the system. Large fluctuations in the intensities of a pulsed laser pose a great challenge for accurate on-line wavelength calibration. In this paper, a wavelength calibration strategy based on multi-wavelength scanning (MWS) was proposed for accurate on-line wavelength calibration of a pulsed laser for CO2 detection. The MWS conducted segmented sampling across the CO2 absorption line with appropriate number of points and range of widths by using a tunable laser. Complete absorption line of CO2 can be obtained through a curve fitting. Then, the on-line wavelength can be easily found at the peak of the absorption line. Furthermore, another algorithm called the energy matching was introduced in the MWS to eliminate the backlash error of tunable lasers during the process of on-line wavelength calibration. Finally, a series of tests was conducted to elevate the calibration precision of MWS. Analysis of tests demonstrated that the MWS proposed in this paper could calibrate the on-line wavelength of pulsed laser accurately and steadily.

  10. SIMPLE MODELS OF METAL-LINE ABSORPTION AND EMISSION FROM COOL GAS OUTFLOWS

    SciTech Connect

    Prochaska, J. Xavier; Rubin, Kate

    2011-06-10

    We analyze the absorption and emission-line profiles produced by a set of simple, cool gas wind models motivated by galactic-scale outflow observations. We implement Monte Carlo radiative transfer techniques that track the propagation of scattered and fluorescent photons to generate one-dimensional spectra and two-dimensional spectral images. We focus on the Mg II {lambda}{lambda}2796, 2803 doublet and Fe II UV1 multiplet at {lambda} {approx} 2600 A, but the results are applicable to other transitions that trace outflows (e.g., Na I, H I Ly{alpha}, Si II). By design, the resonance transitions show blueshifted absorption but one also predicts strong resonance and fine-structure line emission at roughly the systemic velocity. This line-emission 'fills in' the absorption, reducing the equivalent width by up to 50%, shifting the absorption-line centroid by tens of km s{sup -1}, and reducing the effective opacity near systemic. Analysis of cool gas outflows that ignores this line emission may incorrectly infer that the gas is partially covered, measure a significantly lower peak optical depth, and/or conclude that gas at systemic velocity is absent (e.g., an interstellar or slowly infalling component). Because the Fe II lines are connected by optically thin transitions to fine-structure levels, their profiles more closely reproduce the intrinsic opacity of the wind. Together these results naturally explain the absorption and emission-line characteristics observed for star-forming galaxies at z < 1. We also study a scenario promoted to describe the outflows of z {approx} 3 Lyman break galaxies and find profiles inconsistent with the observations due to scattered photon emission. Although line emission complicates the analysis of absorption-line profiles, the surface brightness profiles offer a unique means of assessing the morphology and size of galactic-scale winds. Furthermore, the kinematics and line ratios offer powerful diagnostics of outflows, motivating deep

  11. Simple Models of Metal-line Absorption and Emission from Cool Gas Outflows

    NASA Astrophysics Data System (ADS)

    Prochaska, J. Xavier; Kasen, Daniel; Rubin, Kate

    2011-06-01

    We analyze the absorption and emission-line profiles produced by a set of simple, cool gas wind models motivated by galactic-scale outflow observations. We implement Monte Carlo radiative transfer techniques that track the propagation of scattered and fluorescent photons to generate one-dimensional spectra and two-dimensional spectral images. We focus on the Mg II λλ2796, 2803 doublet and Fe II UV1 multiplet at λ ≈ 2600 Å, but the results are applicable to other transitions that trace outflows (e.g., Na I, H I Lyα, Si II). By design, the resonance transitions show blueshifted absorption but one also predicts strong resonance and fine-structure line emission at roughly the systemic velocity. This line-emission "fills in" the absorption, reducing the equivalent width by up to 50%, shifting the absorption-line centroid by tens of km s-1, and reducing the effective opacity near systemic. Analysis of cool gas outflows that ignores this line emission may incorrectly infer that the gas is partially covered, measure a significantly lower peak optical depth, and/or conclude that gas at systemic velocity is absent (e.g., an interstellar or slowly infalling component). Because the Fe II lines are connected by optically thin transitions to fine-structure levels, their profiles more closely reproduce the intrinsic opacity of the wind. Together these results naturally explain the absorption and emission-line characteristics observed for star-forming galaxies at z < 1. We also study a scenario promoted to describe the outflows of z ~ 3 Lyman break galaxies and find profiles inconsistent with the observations due to scattered photon emission. Although line emission complicates the analysis of absorption-line profiles, the surface brightness profiles offer a unique means of assessing the morphology and size of galactic-scale winds. Furthermore, the kinematics and line ratios offer powerful diagnostics of outflows, motivating deep, spatially extended spectroscopic

  12. Detectability of cold streams into high-redshift galaxies by absorption lines

    NASA Astrophysics Data System (ADS)

    Goerdt, Tobias; Dekel, Avishai; Sternberg, Amiel; Gnat, Orly; Ceverino, Daniel

    2012-08-01

    Cold gas streaming along the dark matter filaments of the cosmic web is predicted to be the major source of fuel for disc buildup, violent disc instability and star formation in massive galaxies at high redshift. We investigate to what extent such cold gas is detectable in the extended circumgalactic environment of galaxies via Lyα absorption and selected low-ionization metal absorption lines. We model the expected absorption signatures using high-resolution zoom-in adaptive mesh refinement cosmological simulations. In the post-processing, we distinguish between self-shielded gas and unshielded gas. In the self-shielded gas, which is optically thick to Lyman continuum radiation, we assume pure collisional ionization for species with an ionization potential greater than 13.6 eV. In the optically-thin, unshielded gas, these species are also photoionized by the metagalactic radiation. In addition to absorption of radiation from background quasars, we compute the absorption line profiles of radiation emitted by the galaxy at the centre of the same halo. We predict the strength of the absorption signal for individual galaxies without stacking. We find that the Lyα absorption profiles produced by the streams are consistent with observations of absorption and emission Lyα profiles in high-redshift galaxies. Due to the low metallicities in the streams, and their low covering factors, the metal absorption features are weak and difficult to detect.

  13. The interstellar absorption-line spectrum of Mu Ophiuchi

    NASA Technical Reports Server (NTRS)

    Cardelli, J.; Boehm-Vitense, E.

    1982-01-01

    UV interstellar lines have been measured on high-resolution, long- and short-wavelength IUE spectra of the B8 V star Mu Oph. Column densities for the observed atoms and ions have been determined as well as turbulent velocities. The interstellar spectrum of Mu Oph is similar to the ones for Rho Oph and Zeta Oph. The ionization equilibria of several elements give consistent limits for the electron density. The C I line arising from different fine-structure levels are studied to yield estimates on the physical conditions in the cloud. Relative depletion of elements in the cloud seen in the interstellar spectrum of Mu Oph follows the same pattern as seen in the interstellar spectra of Zeta Oph and six other stars in the Rho Oph cloud complex.

  14. Broadening of infrared absorption lines at reduced temperatures - Carbon dioxide.

    NASA Technical Reports Server (NTRS)

    Tubbs, L. D.; Williams, D.

    1972-01-01

    An evacuated high-resolution Czerny-Turner spectrograph, which is described in this paper, has been used to determine the strengths S and self-broadening parameters for lines in the R branch of the nu (sub 3) fundamental of carbon dioxide at 298 and at 207 K. The values of self-broadening parameters at 207 K are greater than those to be expected on the basis of a fixed collision cross section.

  15. The Milky Way's Hot Gas Kinematics: Signatures in Current and Future OVII Absorption Line Observations

    NASA Astrophysics Data System (ADS)

    Miller, Matthew J.; Hodges-Kluck, Edmund J.; Bregman, Joel N.

    2016-02-01

    Detections of z ≈ 0 oxygen absorption and emission lines indicate the Milky Way hosts a hot (˜ {10}6 K), low-density plasma extending ≳ 50 {{kpc}} into the Mily Way’s halo. Current X-ray telescopes cannot resolve the line profiles, but the variation of their strengths on the sky constrains the radial gas distribution. Interpreting the O vii Kα absorption line strengths has several complications, including optical depth and line of sight velocity effects. Here, we present model absorption line profiles accounting for both of these effects to show the lines can exhibit asymmetric structures and be broader than the intrinsic Doppler width. The line profiles encode the hot gas rotation curve, the net inflow or outflow of hot gas, and the hot gas angular momentum profile. We show how line of sight velocity effects impact the conversion between equivalent width and the column density, and provide modified curves of growth accounting for these effects. As an example, we analyze the LMC sight line pulsar dispersion measure and O vii equivalent width to show the average gas metallicity is ≳ 0.6{Z}⊙ and b ≳ 100 km s-1. Determining these properties offers valuable insights into the dynamical state of the Milky Way’s hot gas, and improves the line strength interpretation. We discuss future strategies to observe these effects with an instrument that has a spectral resolution of about 3000, a goal that is technically possible today.

  16. Selective-adsorption line shapes in the scattering of 4He by LiF(001)

    NASA Astrophysics Data System (ADS)

    Wesner, David A.; Frankl, Daniel R.

    1981-08-01

    Selective-adsorption line shapes were experimentally studied in 17-meV 4He-atom scattering from a LiF(001) crystalline surface. The specular and several diffracted beams were measured for a variety of incidence conditions. Specular line shapes obey the three rules put forth by Wolfe and Weare. The specular and diffracted-beam line shapes obey the rules formulated recently by Celli, Garcia, and Hutchison in all cases except for the specular Wolfe-Weare rule-2 case. In this case the mixed-extrema structure predicted by Wolfe and Weare is seen. This line shape is very sensitive to surface temperature and age, confirming a recent prediction of Wolfe and Weare concerning inelastic effects on the selective-adsorption line shapes.

  17. Line shape modeling in warm and dense hydrogen plasmas

    NASA Astrophysics Data System (ADS)

    Ferri, S.; Calisti, A.; Mossé, C.; Talin, B.; Gigosos, M. A.; González, M. A.

    2007-05-01

    A study of hydrogen lines emitted in warm ( T˜1eV) and dense ( N≥1018cm -3) plasmas is presented. Under such plasma conditions, the electronic and the ionic contributions to the line width are comparable, and the general question related to a transition from impact to quasi-static broadening arises not only for the far wings but also for the core of spectral lines. The transition from impact to quasi-static broadening for electrons is analyzed by means of Frequency Fluctuation Model (FFM). In parallel, direct integration of the semi-classical evolution equation is performed using electron electric fields calculated by Molecular Dynamics (MD) simulations that permit one to correctly describe the emitter environment. New cross comparisons between benchmark MD simulations and FFM are carried out for electron broadening of the Balmer series lines, and, especially, for the Hα line, for which a few experiments in the warm and dense plasma regimes are available.

  18. Discovery of Broad Soft X-ray Absorption Lines from the Quasar Wind in PDS 456

    NASA Astrophysics Data System (ADS)

    Reeves, J. N.; Braito, V.; Nardini, E.; Behar, E.; O’Brien, P. T.; Tombesi, F.; Turner, T. J.; Costa, M. T.

    2016-06-01

    High-resolution soft X-ray spectroscopy of the prototype accretion disk wind quasar, PDS 456, is presented. Here, the XMM-Newton reflection grating spectrometer spectra are analyzed from the large 2013–2014 XMM-Newton campaign, consisting of five observations of approximately 100 ks in length. During the last observation (OBS. E), the quasar is at a minimum flux level, and broad absorption line (BAL) profiles are revealed in the soft X-ray band, with typical velocity widths of {σ }{{v}}˜ {{10,000}} km s‑1. During a period of higher flux in the third and fourth observations (OBS. C and D, respectively), a very broad absorption trough is also present above 1 keV. From fitting the absorption lines with models of photoionized absorption spectra, the inferred outflow velocities lie in the range ˜ 0.1{--}0.2c. The absorption lines likely originate from He and H-like neon and L-shell iron at these energies. A comparison with earlier archival data of PDS 456 also reveals a similar absorption structure near 1 keV in a 40 ks observation in 2001, and generally the absorption lines appear most apparent when the spectrum is more absorbed overall. The presence of the soft X-ray BALs is also independently confirmed by an analysis of the XMM-Newton EPIC spectra below 2 keV. We suggest that the soft X-ray absorption profiles could be associated with a lower ionization and possibly clumpy phase of the accretion disk wind, where the latter is known to be present in this quasar from its well-studied iron K absorption profile and where the wind velocity reaches a typical value of 0.3c.

  19. Stimuli-Responsive Shape Switching of Polymer Colloids by Temperature-Sensitive Absorption of Solvent.

    PubMed

    Wang, Huaguang; Li, Binghui; Yodh, Arjun G; Zhang, Zexin

    2016-08-16

    The dynamic manipulation of colloidal particle shape offers a novel design mechanism for the creation of advanced responsive materials. To this end, we introduce a versatile new strategy for shape control of anisotropic polymeric colloidal particles. The concept utilizes temperature-sensitive absorption of a suitable solvent from a binary mixture. Specifically, increasing the temperature in the vicinity of the demixing transition of a binary mixture causes more solvent to be absorbed into the polymeric colloidal particle, which, in turn, lowers the glass transition temperature of the polymer inside the particle, with a concomitant decrease in viscosity. The balance between the internal viscosity and surface tension of the particle is thus disrupted, and the anisotropic shape of the particle shifts to become more spherical. Subsequent rapid temperature quenching can halt the process, leaving the particle with an intermediate anisotropy. The resultant shape anisotropy control provides new routes for studies of the phase transitions of anisotropic colloids and enables the fabrication of unique particles for materials applications. PMID:27409766

  20. Discovery of carbon radio recombination lines in absorption towards Cygnus A

    NASA Astrophysics Data System (ADS)

    Oonk, J. B. R.; van Weeren, R. J.; Salgado, F.; Morabito, L. K.; Tielens, A. G. G. M.; Rottgering, H. J. A.; Asgekar, A.; White, G. J.; Alexov, A.; Anderson, J.; Avruch, I. M.; Batejat, F.; Beck, R.; Bell, M. E.; van Bemmel, I.; Bentum, M. J.; Bernardi, G.; Best, P.; Bonafede, A.; Breitling, F.; Brentjens, M.; Broderick, J.; Brüggen, M.; Butcher, H. R.; Ciardi, B.; Conway, J. E.; Corstanje, A.; de Gasperin, F.; de Geus, E.; de Vos, M.; Duscha, S.; Eislöffel, J.; Engels, D.; van Enst, J.; Falcke, H.; Fallows, R. A.; Fender, R.; Ferrari, C.; Frieswijk, W.; Garrett, M. A.; Grießmeier, J.; Hamaker, J. P.; Hassall, T. E.; Heald, G.; Hessels, J. W. T.; Hoeft, M.; Horneffer, A.; van der Horst, A.; Iacobelli, M.; Jackson, N. J.; Juette, E.; Karastergiou, A.; Klijn, W.; Kohler, J.; Kondratiev, V. I.; Kramer, M.; Kuniyoshi, M.; Kuper, G.; van Leeuwen, J.; Maat, P.; Macario, G.; Mann, G.; Markoff, S.; McKean, J. P.; Mevius, M.; Miller-Jones, J. C. A.; Mol, J. D.; Mulcahy, D. D.; Munk, H.; Norden, M. J.; Orru, E.; Paas, H.; Pandey-Pommier, M.; Pandey, V. N.; Pizzo, R.; Polatidis, A. G.; Reich, W.; Scaife, A. M. M.; Schoenmakers, A.; Schwarz, D.; Shulevski, A.; Sluman, J.; Smirnov, O.; Sobey, C.; Stappers, B. W.; Steinmetz, M.; Swinbank, J.; Tagger, M.; Tang, Y.; Tasse, C.; Veen, S. ter; Thoudam, S.; Toribio, C.; van Nieuwpoort, R.; Vermeulen, R.; Vocks, C.; Vogt, C.; Wijers, R. A. M. J.; Wise, M. W.; Wucknitz, O.; Yatawatta, S.; Zarka, P.; Zensus, A.

    2014-02-01

    We present the first detection of carbon radio recombination line absorption along the line of sight to Cygnus A. The observations were carried out with the Low Frequency Array in the 33-57 MHz range. These low-frequency radio observations provide us with a new line of sight to study the diffuse, neutral gas in our Galaxy. To our knowledge this is the first time that foreground Milky Way recombination line absorption has been observed against a bright extragalactic background source. By stacking 48 carbon α lines in the observed frequency range we detect carbon absorption with a signal-to-noise ratio of about 5. The average carbon absorption has a peak optical depth of 2 × 10-4, a line width of 10 km s-1 and a velocity of +4 km s-1 with respect to the local standard of rest. The associated gas is found to have an electron temperature Te ˜ 110 K and density ne ˜ 0.06 cm-3. These properties imply that the observed carbon α absorption likely arises in the cold neutral medium of the Orion arm of the Milky Way. Hydrogen and helium lines were not detected to a 3σ peak optical depth limit of 1.5 × 10-4 for a 4 km s-1 channel width. Radio recombination lines associated with Cygnus A itself were also searched for, but are not detected. We set a 3σ upper limit of 1.5 × 10-4 for the peak optical depth of these lines for a 4 km s-1 channel width.

  1. Modeling of Line Shapes using Continuous Time Random Walk Theory

    NASA Astrophysics Data System (ADS)

    Capes, H.; Christova, M.; Boland, D.; Bouzaher, A.; Catoire, F.; Godbert-Mouret, L.; Koubiti, M.; Mekkaoui, S.; Rosato, J.; Marandet, Y.; Stamm, R.

    2010-11-01

    In order to provide a general framework where the Stark broadening of atomic lines in plasmas can be calculated, we model the plasma stochastic electric field by using the CTRW approach [1,2]. This allows retaining non Markovian terms in the Schrödinger equation averaged over the electric field fluctuations. As an application we consider a special case of a non separable CTRW process, the so called Kangaroo process [3]. An analytic expression for the line profile is finally obtained for arbitrary waiting time distribution functions. An application to the hydrogen Lyman α line is discussed.

  2. Abinitio calculations of the spectral shapes of CO2 isolated lines including non-Voigt effects and comparisons with experiments

    NASA Astrophysics Data System (ADS)

    Hartmann, J.-M.; Tran, H.; Ngo, N. H.; Landsheere, X.; Chelin, P.; Lu, Y.; Liu, A.-W.; Hu, S.-M.; Gianfrani, L.; Casa, G.; Castrillo, A.; Lepère, M.; Delière, Q.; Dhyne, M.; Fissiaux, L.

    2013-01-01

    We present a fully ab initio model and calculations of the spectral shapes of absorption lines in a pure molecular gas under conditions where the influences of collisions and of the Doppler effect are significant. Predictions of the time dependence of dipole autocorrelation functions (DACFs) are made for pure CO2 at room temperature using requantized classical molecular dynamics simulations. These are carried, free of any adjusted parameter, on the basis of an accurate anisotropic intermolecular potential. The Fourier-Laplace transforms of these DACFs then yield calculated spectra which are analyzed, as some measured ones, through fits using Voigt line profiles. Comparisons between theory and various experiments not only show that the main line-shape parameters (Lorentz pressure-broadening coefficients) are accurately predicted, but that subtle observed non-Voigt features are also quantitatively reproduced by the model. These successes open renewed perspectives for the understanding of the mechanisms involved (translational-velocity and rotational-state changes and their dependences on the molecular speed) and the quantification of their respective contributions. The proposed model should also be of great help for the test of widely used empirical line-shape models and, if needed, the construction of more physically based ones.

  3. DISENTANGLING THE CIRCUMNUCLEAR ENVIRONS OF CENTAURUS A. II. ON THE NATURE OF THE BROAD ABSORPTION LINE

    SciTech Connect

    Espada, D.; Matsushita, S.; Sakamoto, K.; Peck, A. B.; Henkel, C.; Iono, D.; Israel, F. P.; Muller, S.; Petitpas, G.; Pihlstroem, Y.; Taylor, G. B.; Trung, D. V.

    2010-09-01

    We report on atomic gas (H I) and molecular gas (as traced by CO(2-1)) redshifted absorption features toward the nuclear regions of the closest powerful radio galaxy, Centaurus A (NGC 5128). Our H I observations using the Very Long Baseline Array allow us to discern with unprecedented sub-parsec resolution H I absorption profiles toward different positions along the 21 cm continuum jet in the inner 0.''3 (or 5.4 pc). In addition, our CO(2-1) data obtained with the Submillimeter Array probe the bulk of the absorbing molecular gas with little contamination by emission, which was not possible with previous CO single-dish observations. We shed light on the physical properties of the gas in the line of sight with these data, emphasizing the still open debate about the nature of the gas that produces the broad absorption line ({approx}55 km s{sup -1}). First, the broad H I line is more prominent toward the central and brightest 21 cm continuum component than toward a region along the jet at a distance {approx}20 mas (or 0.4 pc) further from the nucleus. This indicates that the broad absorption line arises from gas located close to the nucleus, rather than from diffuse and more distant gas. Second, the different velocity components detected in the CO(2-1) absorption spectrum match well with other molecular lines, such as those of HCO{sup +}(1-0), except the broad absorption line that is detected in HCO{sup +}(1-0) (and most likely related to that of the H I). Dissociation of molecular hydrogen due to the active galactic nucleus seems to be efficient at distances r {approx}< 10 pc, which might contribute to the depth of the broad H I and molecular lines.

  4. H{beta} LINE WIDTHS AS AN ORIENTATION INDICATOR FOR LOW-IONIZATION BROAD ABSORPTION LINE QUASARS

    SciTech Connect

    Punsly, Brian; Zhang Shaohua E-mail: brian.punsly@comdev-usa.co

    2010-12-20

    There is evidence from radio-loud quasars to suggest that the distribution of the H{beta} broad emission line (BEL) gas is arranged in a predominantly planar orientation, and this result may well also apply to radio-quiet quasars. This would imply that the observed FWHM of the H{beta} BELs is dependent on the orientation of the line of sight to the gas. If this view is correct then we propose that the FWHM can be used as a surrogate, in large samples, to determine the line of sight to the H{beta} BELs in broad absorption line quasars (BALQSOs). The existence of broad UV absorption lines (BALs) means that the line of sight to BALQSOs must also pass through the BAL out-flowing gas. It is determined that there is a statistically significant excess of narrow-line profiles in the SDSS DR7 archival spectra of low-ionization broad absorption line quasars (LoBALQSOs), indicating that BAL gas flowing close to the equatorial plane does not commonly occur in these sources. We also find that the data is not well represented by random lines of sight to the BAL gas. Our best fit indicates two classes of LoBALQSOs, the majority ({approx}2/3) are polar outflows that are responsible for the enhanced frequency of narrow-line profiles, and the remainder are equatorial outflows. We further motivated the line of sight explanation of the narrow-line excess in LoBALQSOs by considering the notion that the skewed distribution of line profiles is driven by an elevated Eddington ratio in BALQSOs. We constructed a variety of control samples comprised of non-LoBALQSOs matched to a de-reddened LoBALQSO sample in redshift, luminosity, black hole mass, and Eddington ratio. It is demonstrated that the excess of narrow profiles persists within the LoBALQSO sample relative to each of the control samples with no reduction of the statistical significance. Thus, we eliminate the possibility that the excess narrow lines seen in the LoBALQSOs arise from an enhanced Eddington ratio.

  5. 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.

  6. Laboratory verification of on-line lithium analysis using ultraviolet absorption spectrometry

    SciTech Connect

    Beemster, B.J.; Schlager, K.J.; Schloegel, K.M.; Kahle, S.J.; Fredrichs, T.L.

    1992-12-31

    Several laboratory experiments were performed to evaluate the capability of absorption spectrometry in the ultraviolet-visible wavelength range with the objective of developing methods for on-line analysis of lithium directly in the primary coolant of Pressurized Water Reactors using optical probes. Although initial laboratory tests seemed to indicate that lithium could be detected using primary absorption (detection of natural spectra unassisted by reagents), subsequent field tests demonstrated that no primary absorption spectra existed for lithium in the ultraviolet-visible wavelength range. A second series of tests that were recently conducted did, however, confirm results reported in the literature to the effect that reagents were available that will react with lithium to form chelates that possess detectable absorption and fluorescent signatures. These results point to the possible use of secondary techniques for on-line analysis of lithium.

  7. The effect of moisture absorption on the physical properties of polyurethane shape memory polymer foams

    PubMed Central

    Yu, Ya-Jen; Hearon, Keith; Wilson, Thomas S.; Maitland, Duncan J.

    2011-01-01

    The effect of moisture absorption on the glass transition temperature (Tg) and stress/strain behavior of network polyurethane shape memory polymer (SMP) foams has been investigated. With our ultimate goal of engineering polyurethane SMP foams for use in blood contacting environments, we have investigated the effects of moisture exposure on the physical properties of polyurethane foams. To our best knowledge, this study is the first to investigate the effects of moisture absorption at varying humidity levels (non-immersion and immersion) on the physical properties of polyurethane SMP foams. The SMP foams were exposed to differing humidity levels for varying lengths of time, and they exhibited a maximum water uptake of 8.0% (by mass) after exposure to 100% relative humidity for 96 h. Differential scanning calorimetry results demonstrated that water absorption significantly decreased the Tg of the foam, with a maximum water uptake shifting the Tg from 67 °C to 5 °C. Samples that were immersed in water for 96 h and immediately subjected to tensile testing exhibited 100% increases in failure strains and 500% decreases in failure stresses; however, in all cases of time and humidity exposure, the plasticization effect was reversible upon placing moisture-saturated samples in 40% humidity environments for 24 h. PMID:21949469

  8. The effect of moisture absorption on the physical properties of polyurethane shape memory polymer foams

    NASA Astrophysics Data System (ADS)

    Yu, Ya-Jen; Hearon, Keith; Wilson, Thomas S.; Maitland, Duncan J.

    2011-08-01

    The effect of moisture absorption on the glass transition temperature (Tg) and the stress/strain behavior of network polyurethane shape memory polymer (SMP) foams has been investigated. With our ultimate goal of engineering polyurethane SMP foams for use in blood-contacting environments, we have investigated the effects of moisture exposure on the physical properties of polyurethane foams. To the best of our knowledge, this study is the first to investigate the effects of moisture absorption at varying humidity levels (non-immersion and immersion) on the physical properties of polyurethane SMP foams. The SMP foams were exposed to differing humidity levels for varying lengths of time, and they exhibited a maximum water uptake of 8.0% (by mass) after exposure to 100% relative humidity for 96 h. Differential scanning calorimetry results demonstrated that water absorption significantly decreased the Tg of the foam, with a maximum water uptake shifting the Tg from 67 to 5 °C. Samples that were immersed in water for 96 h and immediately subjected to tensile testing exhibited 100% increases in failure strains and 500% decreases in failure stresses; however, in all cases of time and humidity exposure, the plasticization effect was reversible upon placing moisture-saturated samples in 40% humidity environments for 24 h.

  9. PG 1700 + 518 - a low-redshift, broad absorption line QSO

    SciTech Connect

    Pettini, M.; Boksenberg, A.

    1985-07-01

    The first high-resolution optical spectra and lower resolution UV spectra of PG 1700 + 518, the only known broad-absorption-line (BAL) QSO at low emission redshift (0.288) are presented. The optical data were obtained with the Isaac Newton Telescope on the island of La Palma and the UV data with the International Ultraviolet Explorer satellite. The outstanding feature of the optical spectrum is a strong, broad Mg II absorption trough, detached from the Mg II emission line and indicative of ejection velocities of between 7000 and 18,000 km/s. Also detected were narrow (FWHM = 350 km/s) Mg II absorption lines at absolute z = 0.2698, which are probably related to the mass ejection phenomenon. It is concluded that the emission-line spectrum is similar to that of other low-redshift QSOs although there are some obvious differences from typical BAL QSOs, most notably in the unusually low level of ionization of both emission-line and broad absorption line gas. 21 references.

  10. Multiple Velocity Components in the C IV Absorption Line of NGC 5548

    NASA Technical Reports Server (NTRS)

    Mathur, Smita; Elvis, Martin; Wilkes, Belinda

    1999-01-01

    We have observed the much-studied Seyfert 1 galaxy NGC 5548 with the Goddard High-Resolution Spectrograph (GHRS) on the Hubble Space Telescope (HST). Our 14 ks observation covers the C IV emission line at a resolution of greater than 20,000. Our purpose was to study the absorption line found at lower resolution by IUE and the HST Faint Object Spectrograph. We found that the C IV absorption line resolves into six separate doublets with equivalent widths of 0.07-0.38 Angstrom. The absorption lines have blueshifts relative to the systemic velocity of the galaxy of 380-1250 km s(exp -1), except for one, which has a redshift of 250 km s(exp -1), suggesting both inflow and outflow. The inflowing component may be related to the accretion flow into the nuclear black hole. All the doublet lines are resolved by the GHRS. Three doublets are narrow, with FWHM greater than or approximately 100 km s(exp -1), and three are broad, FWHM approximately 160-290 km s(exp -1). We find evidence of partial covering by the narrow absorption lines. Either (but not both) of the two strongest broad doublets could be from the same material that produces the X-ray ionized absorber seen in soft X-rays. The remaining five systems must be at least 10 times less ionized (and so of lower total column density) to remain consistent with the X-ray spectra.

  11. Universal FFM Hydrogen Spectral Line Shapes Applied to Ions and Electrons

    NASA Astrophysics Data System (ADS)

    Mossé, C.; Calisti, A.; Ferri, S.; Talin, B.; Bureyeva, L. A.; Lisitsa, V. S.

    2008-10-01

    We present a method for the calculation of hydrogen spectral line shapes based on two combined approaches: Universal Model and FFM procedure. We start with the analytical functions for the intensities of the Stark components of radiative transitions between highly excited atomic states with large values of principal quantum numbers n,n'γ1, with Δn = n-n'≪n for the specific cases of Hn-α line (Δn = 1) and Hn-β line (Δn = 2). The FFM line shape is obtained by averaging on the electric field of the Hooper's field distribution for ion and electron perturber dynamics and by mixing the Stark components with a jumping frequency rate ve (vi) where v = N1/3u (N is electron density and u is the ion or electron thermal velocity). Finally, the total line shape is given by convolution of ion and electron line shapes. Hydrogen line shape calculations for Balmer Hα and Hβ lines are compared to experimental results in low density plasma (Ne˜1016-1017cm-3) and low electron temperature in order of 10 000K. This method relying on analytic expressions permits fast calculation of Hn-α and Hn-β lines of hydrogen and could be used in the study of the Stark broadening of radio recombination lines for high principal quantum number.

  12. Radiatively driven winds for different power law spectra. [for explaining narrow and broad quasar absorption lines

    NASA Technical Reports Server (NTRS)

    Beltrametti, M.

    1980-01-01

    The analytic solutions for radiatively driven winds are given for the case in which the winds are driven by absorption of line and continuum radiation. The wind solutions are analytically estimated for different parameters of the central source and for different power law spectra. For flat spectra, three sonic points can exist; it is shown, however, that only one of these sonic points is physically realistic. Parameters of the central source are given which generate winds of further interest for explaining the narrow and broad absorption lines in quasars. For the quasar model presented here, winds which could give rise to the narrow absorption lines are generated by central sources with parameters which are not realistic for quasars.

  13. Modelling of the X-ray broad absorption features in Narrow-Line Seyfert 1s

    NASA Astrophysics Data System (ADS)

    Porquet, Delphine; Mouchet, Martine; Dumont Anne-Marie

    2000-09-01

    We investigate the origin of the broad absorption features detected near 1-1.4 keV in several Narrow-Line Seyfert 1 galaxies, by modelling the absorbing medium with various physical parameters, using the ionization code PEGAS. The observed properties of the X-ray absorption features can be reproduced by taking into account the peculiar soft X-ray excess which is well fitted by a blackbody plus an underlying power law. We equally stress that the emission coming from the absorbing medium (related to the covering factor) has a strong influence on the resulting X-ray spectrum, in particular on the apparent position and depth of the absorption features. A non-solar iron abundance may be required to explain the observed deep absorption. We also investigate the influence of an additional collisional ionization process ("hybrid case") on the predicted absorption features.

  14. Monochromatic calculations of atmospheric radiative transfer due to molecular line absorption

    NASA Technical Reports Server (NTRS)

    Chou, M.-D.; Kouvaris, L.

    1986-01-01

    Sensitivity studies related to the effects of line cutoff, spectral resolution, and temperature and pressure interpolations in radiative transfer have been performed so that a data set of absorption coefficients for water vapor, CO2, and O3 may be created efficiently. Results show that computations of absorption coefficients are affected only slightly by cutting a line off at a wave number 190 times the Lorentz half width from the center, or equivalently, cutting off 0.33 percent of the line intensity from the wings. To achieve a relative cooling rate error smaller than 2 percent, it is sufficient to precompute the absorption coefficient at three temperatures (210, 250, and 290 K) and 19 pressures with Delta (log 10 p) = 0.2. The absorption coefficient at other conditions can be interpolated linearly with pressure and exponentially with a quadratic in temperature. For the spectral resolution the absorption coefficients can be adequately computed at 0.01, 0.002, 0.005, and 0.025/cm intervals in the thermal water vapor, the CO2 and O3 bands, and the solar water vapor bands, respectively, which limits the error to only a few percent in the cooling and heating rates. Using the precomputed absorption coefficients, repeated monochromatic calculations of atmospheric heating/cooling rates for radiation model developments and for comparison with less detailed calculations are no longer difficult.

  15. The η Car Campaign with UVES at the ESO VLT II. Interstellar and circumstellar absorption lines

    NASA Astrophysics Data System (ADS)

    Weis, K.; Bomans, D. J.; Stahl, O.; Davidson, K.; Humphreys, R. M.; Gull, T. R.

    2005-09-01

    We monitored η Car and the Homunculus using the ESO VLT UVES spectrograph between 2002 and 2004 (see Weis et al., this proceedings). In these high dispersion spectra practically all interstellar absorption features known in the 3000 Å to 10000 Å regime are present (e.g. 4 Ti II lines, 3 Fe I lines, the Ca I line, both Na I doublets, the two K I doublets, and the Ca II doublets, several molecular lines, and a number of diffuse interstellar bands). Near-UV STIS spectra show many low ionization absorption lines (e.g. Gull et al., this proceedings), but there are several differences in the velocity structure and line strengths between these lines of sight, e.g. we do not detect multiple absorption components between -350 to -550 km s-1 in the UVES spectra. Changes over time are present in e.g. the Ca II lines, with small column density changes in the (probably interstellar) +80 km s-1 component and large changes in the -510 km s-1 component, which is most probably located in the outer shell of the Homunculus (see e.g. Nielsen et al., this proceedings). Similar changes in the Ti II 3384 Å component at -147 km s-1 are present, too. With the data set, we not only follow the temporal evolution of the circumstellar absorption components (presumably originating near η Car and in the Homunculus) before, during and after the event, but also search for changes along our long-slits centered on the star and on FOS4. Indeed, the -147 km s-1 component of the Ti II 3384 Å lines shows line strength variations over the southeast lobe of the Homunculus. A preliminary search for very high velocity absorption lines from the outer ejected using only one of our spectra already yielded a possible detection at -1500 km s-1. Clearly a detailed analysis of the absorption lines in the UVES data will provide many new insights into the structure and physics of η Car's ejecta.

  16. Narrow absorption lines with two observations from the Sloan Digital Sky Survey

    NASA Astrophysics Data System (ADS)

    Chen, Zhi-Fu; Gu, Qiu-Sheng; Chen, Yan-Mei; Cao, Yue

    2015-07-01

    We assemble 3524 quasars from the Sloan Digital Sky Survey (SDSS) with repeated observations to search for variations of the narrow C IV λ λ 1548,1551 and Mg II λ λ 2796,2803 absorption doublets in spectral regions shortward of 7000 Å in the observed frame, which corresponds to time-scales of about 150-2643 d in the quasar rest frame. In these quasar spectra, we detect 3580 C IV absorption systems with zabs = 1.5188-3.5212 and 1809 Mg II absorption systems with zabs = 0.3948-1.7167. In term of the absorber velocity (β) distribution in the quasar rest frame, we find a substantial number of C IV absorbers with β < 0.06, which might be connected to absorption of quasar outflows. The outflow absorption peaks at υ ≈ 2000 km s^{-1} and drops rapidly below this peak value. Among 3580 C IV absorption systems, 52 systems (˜1.5 per cent) show obvious variations in equivalent widths in the absorber rest frame (Wr): 16 enhanced, 16 emerged, 12 weakened and 8 disappeared systems, respectively. We find that changes in Wrλ1548 are related neither to the time-scales of the two SDSS observations nor to absorber velocities in the quasar rest frame. Variable absorption in low-ionization species is important to constrain the physical conditions of the absorbing gas. There are two variable Mg II absorption systems measured from SDSS spectra detected by Hacker et al. However, in our Mg II absorption sample, we find that neither shows variable absorption with confident levels of >4σ for λ2796 lines and >3σ for λ2803 lines.

  17. HI Absorption Lines Detected from the Arecibo Legacy Fast ALFA Survey Data

    NASA Astrophysics Data System (ADS)

    Zhong-zu, Wu; Martha P, Haynes; Riccardo, Giovanelli; Ming, Zhu; Ru-rong, Chen

    2015-10-01

    We present some preliminary results of an on-going study of HI 21-cm absorption lines based on the 40% survey data released by the Arecibo Legacy Fast Arecibo L-band Feed Array (ALFALFA). (1) Ten HI candidate absorbers have been detected. Five of them are previously published in the literature, and the rest of them are new detections that need further confirmation. (2) For those sources with no detected absorptions, we have calculated the upper limit of their foreground HI column density NHI. The statistical result of the NHI distribution indicates that the ratio Ts/f between the averaged spin temperature and coverage factor for DLAs (the damped Lyα systems) might be larger than 500 K. The radio frequency interference (RFI) and standing wave are the main factors affecting the detection of HI absorption lines, which have been analyzed and discussed as well in order to find a method of solution. Our study can serve as a pathfinder for the future large-scale search of HI 21-cm absorption lines using the Five-Hundred-Meter Aperture Spherical Radio Telescope (FAST), which is an Arecibo-type radio telescope currently under construction in China with greatly increased sensitivity, bandwidth, and observational sky area. As prospects, we have discussed two types of observational studies of HI absorption lines toward extragalactic sources using the FAST telescope.

  18. VizieR Online Data Catalog: QSOs narrow absorption line variability (Hacker+, 2013)

    NASA Astrophysics Data System (ADS)

    Hacker, T. L.; Brunner, R. J.; Lundgren, B. F.; York, D. G.

    2013-06-01

    Catalogues of 2,522 QAL systems and 33 variable NAL systems detected in SDSS DR7 quasars with repeat observations. The object identifiers, position coordinates, and plate-MJD-fibre designations are taken from the SpecObjAll table in the SDSS Catalogue Archive Server (CAS) while the quasar redshifts (zqso) are from Hewett & Wild (2010, Cat. J/MNRAS/405/2302). The absorption system redshift (zabs), system grade, and detected lines are outputs of the York et al. (2013, in. prep.) QAL detection pipeline. Some absorption lines are flagged based on alternate identifications (a), proximity of masked pixels (b), or questionable continuum fits (c). (3 data files).

  19. Absorption lines in the spectrum of Q0248 + 4302 due to a foreground tidal tail

    SciTech Connect

    Sargent, W.L.W.; Steidel, C.C. California Univ., Berkeley )

    1990-08-01

    The strong absorption lines in the spectrum of the quasar Q0248 + 4302 are discussed. The absorption has been shown to be produced in a sinuous tidal tail which emanates from the nearby galaxy pair G0248 + 4302A,B. There is a velocity difference of about 260 km/s between the systemic redshift of the interacting galaxies and the redshift of the tidal tail at a galactocentric distance of about 11/h kpc. The large velocity spread observed in the tail gas is probably responsible for the unusual strength of the interstellar lines. 18 refs.

  20. Electric field distribution and exciton recombination line shape in GaAs

    NASA Astrophysics Data System (ADS)

    Schuster, J.; Kim, T. Y.; Batke, E.; Reuter, D.; Wieck, A. D.

    2016-05-01

    We studied the photoluminescence line shapes of free and bound excitons in a n-modulation doped {{Al}}1-x{{Ga}}x{As}–GaAs heterostructure with linearly increasing electric field in the p-doped buffer. At small laser excitation power the line shapes of the neutral donor bound and free excitons deviate strongly from a simple Lorentzian, whereas the neutral acceptor bound exciton is not obviously affected. Asymmetric lines of sawtooth-type form are observed for the donor bound and the free exciton. The line asymmetry could be traced back to the field dependent exciton binding energy and the field distribution in our heterostructure. A simple analytical model can account for the field dependent line shapes and a fit to the experimental lines gives a satisfactory agreement.

  1. The dependence of C IV broad absorption line properties on accompanying Si IV and Al III absorption: relating quasar-wind ionization levels, kinematics, and column densities

    SciTech Connect

    Filiz Ak, N.; Brandt, W. N.; Schneider, D. P.; Trump, J. R.; Hall, P. B.; Anderson, S. F.; Hamann, F.; Myers, Adam D.; Pâris, I.; Petitjean, P.; Ross, Nicholas P.; Shen, Yue; York, Don

    2014-08-20

    We consider how the profile and multi-year variability properties of a large sample of C IV Broad Absorption Line (BAL) troughs change when BALs from Si IV and/or Al III are present at corresponding velocities, indicating that the line of sight intercepts at least some lower ionization gas. We derive a number of observational results for C IV BALs separated according to the presence or absence of accompanying lower ionization transitions, including measurements of composite profile shapes, equivalent width (EW), characteristic velocities, composite variation profiles, and EW variability. We also measure the correlations between EW and fractional-EW variability for C IV, Si IV, and Al III. Our measurements reveal the basic correlated changes between ionization level, kinematics, and column density expected in accretion-disk wind models; e.g., lines of sight including lower ionization material generally show deeper and broader C IV troughs that have smaller minimum velocities and that are less variable. Many C IV BALs with no accompanying Si IV or Al III BALs may have only mild or no saturation.

  2. Is the Na D Absorption Line Useful For Integrated Light Stellar Population Studies In Galaxies?

    NASA Astrophysics Data System (ADS)

    Bergmann, Marcel; Milvang-Jensen, B.

    2009-01-01

    The Sodium Na D absorption line at 5895 Angstroms is one of the strongest absorption features in stellar photospheres, but has been rarely used in integrated light stellar population studies of galaxies. A principal reason why it has not been used is the suspicion that interstellar absorption within the galaxies may enhance or alter the absorption profile of the combined stellar light, thus giving an errant description of the stellar population. As a project undertaken during the National Virtual Observatory Summer School, we have investigated to what extent ISM absorption seems to alter the measurements. We use VO tools to create multiple galaxy samples: a sample expected to have little ISM (cluster galaxies, which are mainly ellipticals), and two samples with higher expected levels of ISM (HI-detected galaxies and morphologically late-type galaxies). After culling the samples to match the same distribution of (older) ages and (higher) metallicities, we find that the Na D vs. velocity dispersion correlation is not significantly different for the samples with and without ISM, and all have similar levels of scatter. Consequently, the Na D line seems like a promising tool for evolutionary studies comparing high and low redshift galaxy samples. Our continuing work focuses on the effects of possible ISM absorption on the line-of-sight velocity profile as derived from the Na D line compared to Mgb and Ca H & K absorption features. This research has made use of data obtained from and software provided by the US National Virtual Observatory, which is sponsored by the National Science Foundation. We thank the US-VO and the NSF for the partial funding they provided to attend this meeting.

  3. Sensitivity of the curve-to-growth technique utilized in rocket experiments to determine the line shape of solar He I resonance lines

    NASA Technical Reports Server (NTRS)

    Wu, C. Y. R.; Ogawa, H. S.

    1986-01-01

    The sensitivity of the curve-of-growth (COG) technique utilized in rocket measurements to determine the line profiles of the solar He I resonance emissions is theoretically examined with attention to the possibility of determining the line core shape using this technique. The line at 584.334 A is chosen as an illustration. Various possible source functions of the solar line have been assumed in the computation of the integrated transmitted intensity. A recent observational data set obtained by the present researchers is used as the constraint of the computation. It is confirmed that the COG technique can indeed provide a good measurement of the solar line width. However, to obtain detailed knowledge of the solar profile at line center and in the core region, (1) it is necessary to be able to carry out relative solar flux measurements with a 1-percent or better precision, and (2) it must be possible to measure the He gas pressure in the absorption cell to lower than 0.1 mtorr. While these numbers apply specifically to the present geometry, the results are readily scaled to other COG measurements using other experimental parameters.

  4. Instrument Line Shape Modeling and Correction for Off-Axis Detectors in Fourier Transform Spectrometry

    NASA Technical Reports Server (NTRS)

    Bowman, K.; Worden, H.; Beer, R.

    1999-01-01

    Spectra measured by off-axis detectors in a high-resolution Fourier transform spectrometer (FTS) are characterized by frequency scaling, asymmetry and broadening of their line shape, and self-apodization in the corresponding interferogram.

  5. Measurement of the absorption line profiles of water vapour isotopomers at 1.39 {mu}m using the methods of diode laser spectroscopy

    SciTech Connect

    Kuz'michev, A S; Nadezhdinskii, Aleksandr I; Ponurovskii, Ya Ya

    2011-07-31

    The issues related to high-precision measurement of the absorption line profiles of water vapour and its isotopomers using the methods of diode laser spectroscopy in the near IR range aimed at the analysis and detection of greenhouse gases are considered. The absorption line shape of H{sub 2}{sup 16}O is investigated as a function of pressure of different buffer gases. The influence of the instrument function of the diode laser (DL) on the precision of measuring the line profile is studied. From fitting the profile of Doppler-broadened H{sub 2}{sup 16}O absorption line to a model profile the lasing line width of the DL with a fibre pigtail is determined. The frequencies and intensities of absorption lines of water isotopomers H{sub 2}{sup 16}O, H{sub 2}{sup 17}O, H{sub 2}{sup 18}O, and HDO are measured in the range of DL oscillation. Analytical spectral regions are chosen for distant probing of water vapour using an airborne lab. (laser spectroscopy)

  6. A Search for Line Shape and Depth Variations in 51 Pegasi and τ Bootis

    NASA Astrophysics Data System (ADS)

    Brown, Timothy M.; Kotak, Rubina; Horner, Scott D.; Kennelly, Edward J.; Korzennik, Sylvain; Nisenson, P.; Noyes, Robert W.

    1998-02-01

    Spectroscopic observations of 51 Pegasi and τ Bootis show no periodic changes in the shapes of their line profiles; these results for 51 Peg are in significant conflict with those reported by Gray & Hatzes. Our detection limits are small enough to rule out nonradial pulsations as the cause of the variability in τ Boo, but not in 51 Peg. The absence of line shape changes is consistent with these stars' radial velocity variability arising from planetary mass companions.

  7. Nanoscale Liquid Jets Shape New Line of Business

    NASA Technical Reports Server (NTRS)

    2003-01-01

    Just as a pistol shrimp stuns its prey by quickly closing its oversized claw to shoot out a shock-inducing, high-velocity jet of water, NanoMatrix, Inc., is sending shockwaves throughout the nanotechnology world with a revolutionary, small-scale fabrication process that uses powerful liquid jets to cut and shape objects. Emanuel Barros, a former project engineer at NASA s Ames Research Center, set out to form the Santa Cruz, California-based NanoMatrix firm and materialize the micro/nano cutting process partially inspired by the water-spewing crustacean. Early on in his 6-year NASA career, Barros led the development of re-flown flight hardware for an award-winning Spacelab project called NeuroLab. This project, the sixteenth and final Spacelab mission, focused on a series of experiments to determine the effects of microgravity on the development of the mammalian nervous system.

  8. Laser plasma diagnostics and self-absorption measurements of the Hβ Balmer series line

    NASA Astrophysics Data System (ADS)

    Gautam, Ghaneshwar; Parigger, Christian G.; Surmick, David M.; EL Sherbini, Ashraf M.

    2016-02-01

    In this work, the peak-separation of the Balmer series hydrogen beta line was measured to determine the electron density of laser-induced plasma from spatially and temporally resolved spectra collected in laboratory air at standard ambient temperature and pressure. The self-absorption phenomenon is investigated by using a mirror that retro-reflects the emitted radiation through the plasma. The experimental data with and without the mirror were analyzed with available hydrogen beta computer simulations. Hardly any self-absorption was found as indicated by the correction factors that only marginally differ from unity. The obtained electron density values are also compared with the electron densities from nearby nitrogen lines. The hydrogen beta Hβ peak-separation method yields reliable results for an electron density of the order of 1 ×1017cm-3 for time delays of 5 μs from plasma generation, which confirms that self-absorption is insignificant for such electron densities.

  9. High-Resolution Spectroscopy of Quasars and Quasar Absorption-Line Systems

    NASA Technical Reports Server (NTRS)

    Shull, J. Michael

    1995-01-01

    Topic cover in this paper included new observations of QSO absorption lines by the Keck Telescope HIRES spectrometer and the Hubble Space Telescope. An overview of the major scientific issues in this field is followed by a brief summary of a panel discussion that addressed future instrumental possibilities that could answer some of these questions.

  10. Modeling the double-trough structure observed in broad absorption line QSOs using radiative acceleration

    NASA Technical Reports Server (NTRS)

    Arav, Nahum; Begelman, Mitchell C.

    1994-01-01

    We present a model explaining the double trough, separated by delta v approximately = 5900 km/s, observed in the C IV lambda-1549 broad absorption line (BAL) in a number of BALQSOs. The model is based on radiative acceleration of the BAL outflow, and the troughs result from modulations in the radiative force. Specifically, where the strong flux from the Lyman-alpha lambda-1215 broad emission line is redshifted to the frequency of the N V lambda-1240 resonance line, in the rest frame of the accelerating N V ions, the acceleration increases and the absorption is reduced. At higher velocities the Lyman-alpha emission is redshifted out of the resonance and the N V ions experience a declining flux which causes the second absorption trough. A strongly nonlinear relationship between changes in the flux and the optical depth in the lines is shown to amplify the expected effect. This model produces double troughs for which the shallowest absorption between the two troughs occurs at v approximately = 5900 km/s. Indeed, we find that a substantial number of the observed objects show this feature. A prediction of the model is that all BALQSOs that show a double-trough signature will be found to have an intrinsic sharp drop in their spectra shortward of approximately 1200 A.

  11. Cross section calculations of astrophysical interest. [for theories of absorption and emission lines

    NASA Technical Reports Server (NTRS)

    Gerjuoy, E.

    1974-01-01

    Cross sections are discussed for rotational excitation associated with theories of absorption and emission lines from molecules in space with emphasis on H2CO, CO, and OH by collisions with neutral particles such H, H2, and He. The sensitivity of the Thaddeus equation for the H2CO calculation is examined.

  12. P Cygni profiles in zeta Ophiuchi and zeta Puppis. [far UV absorption lines

    NASA Technical Reports Server (NTRS)

    Morton, D. C.

    1976-01-01

    Detailed P Cygni profiles are plotted using data from selected regions of the far-UV spectra of zeta OPh and zeta Pup obtained by the Copernicus satellite. Equivalent widths and velocity shifts of both emission and absorption features are also presented. For zeta Oph, it is found that only the C IV and N V resonance lines exhibit the P Cygni phenomenon; for zeta Pup, the resonance lines of C III, N III, Si IV, C IV, P V, S VI, N V, and O VI all show strong P Cygni lines, although the emission component seems to be absent in N III. For both stars, it is shown that parts of most absorption profiles exceed the escape velocity, indicating mass ejection. The short-wavelength edges of the resonance lines are found to average about -1590 km/s in zeta Oph and about -2660 km/s in zeta Pup, with no significant dependence on ionization potential. It is noted that the equivalent width of the emission component is always considerably less than that of the absorption component, suggesting that absorption occurs close to the stellar surface.

  13. Robotic U-shaped assembly line balancing using particle swarm optimization

    NASA Astrophysics Data System (ADS)

    Mukund Nilakantan, J.; Ponnambalam, S. G.

    2016-02-01

    Automation in an assembly line can be achieved using robots. In robotic U-shaped assembly line balancing (RUALB), robots are assigned to workstations to perform the assembly tasks on a U-shaped assembly line. The robots are expected to perform multiple tasks, because of their capabilities. U-shaped assembly line problems are derived from traditional assembly line problems and are relatively new. Tasks are assigned to the workstations when either all of their predecessors or all of their successors have already been assigned to workstations. The objective function considered in this article is to maximize the cycle time of the assembly line, which in turn helps to maximize the production rate of the assembly line. RUALB aims at the optimal assignment of tasks to the workstations and selection of the best fit robot to the workstations in a manner such that the cycle time is minimized. To solve this problem, a particle swarm optimization algorithm embedded with a heuristic allocation (consecutive) procedure is proposed. The consecutive heuristic is used to allocate the tasks to the workstation and to assign a best fit robot to that workstation. The proposed algorithm is evaluated using a wide variety of data sets. The results indicate that robotic U-shaped assembly lines perform better than robotic straight assembly lines in terms of cycle time.

  14. Spectro web: oscillator strength measurements of atomic absorption lines in the sun and procyon

    NASA Astrophysics Data System (ADS)

    Lobel, A.

    2008-10-01

    We update the online SpectroWeb database of spectral standard reference stars with 1178 oscillator strength values of atomic absorption lines observed in the optical spectrum of the Sun and Procyon (α CMi A). The updated line oscillator strengths are measured with best fits to the disk-integrated KPNO-FTS spectrum of the Sun observed between 4000 Å and 6800 Å using state-of-the-art detailed spectral synthesis calculations. A subset of 660 line oscillator strengths is validated with synthetic spectrum calculations of Procyon observed with ESO-UVES between 4700 Å and 6800 Å. The new log(gf)-values in SpectroWeb are improvements upon the values offered in the online Vienna Atomic Line Database (VALD). We find for neutral iron-group elements, such as Fe I, Ni I, Cr I, and Ti I, a statistically significant over-estimation of the VALD log((gf)-values for weak absorption lines with normalized central line depths below 15 %. For abundant lighter elements (e.g. Mg I and Ca I) this trend is statistically not significantly detectable, with the exception of Si I for which the log(gf)-values of 60 weak and medium-strong lines are substantially decreased to best fit the observed spectra. The newly measured log(gf)-values are available in the SpectroWeb database at http://spectra.freeshell.org, which interactively displays the observed and computed stellar spectra, together with corresponding atomic line data.

  15. A summary of transition probabilities for atomic absorption lines formed in low-density clouds

    NASA Technical Reports Server (NTRS)

    Morton, D. C.; Smith, W. H.

    1973-01-01

    A table of wavelengths, statistical weights, and excitation energies is given for 944 atomic spectral lines in 221 multiplets whose lower energy levels lie below 0.275 eV. Oscillator strengths were adopted for 635 lines in 155 multiplets from the available experimental and theoretical determinations. Radiation damping constants also were derived for most of these lines. This table contains the lines most likely to be observed in absorption in interstellar clouds, circumstellar shells, and the clouds in the direction of quasars where neither the particle density nor the radiation density is high enough to populate the higher levels. All ions of all elements from hydrogen to zinc are included which have resonance lines longward of 912 A, although a number of weaker lines of neutrals and first ions have been omitted.

  16. Direct Insights Into Observational Absorption Line Analysis Methods of the Circumgalactic Medium Using Cosmological Simulations

    NASA Astrophysics Data System (ADS)

    Churchill, Christopher W.; Vander Vliet, Jacob R.; Trujillo-Gomez, Sebastian; Kacprzak, Glenn G.; Klypin, Anatoly

    2015-03-01

    We study the circumgalactic medium (CGM) of a z = 0.54 simulated dwarf galaxy using hydroART simulations. We present our analysis methods, which emulate observations, including objective absorption line detection, apparent optical depth (AOD) measurements, Voigt profile (VP) decomposition, and ionization modeling. By comparing the inferred CGM gas properties from the absorption lines directly to the gas selected by low ionization H i and Mg ii, and by higher ionization C iv and O vi absorption, we examine how well observational analysis methods recover the “true” properties of CGM gas. In this dwarf galaxy, low ionization gas arises in sub-kiloparsec “cloud” structures, but high ionization gas arises in multiple extended structures spread over 100 kpc; due to complex velocity fields, highly separated structures give rise to absorption at similar velocities. We show that AOD and VP analysis fails to accurately characterize the spatial, kinematic, and thermal conditions of high ionization gas. We find that H i absorption selected gas and O vi absorption gas arise in totally distinct physical gas structures, calling into question current observational techniques employed to infer metallicities and the total mass of “warm-hot” CGM gas. We present a method to determine whether C iv and O vi absorbing gas is photo or collisionally ionized and whether the assumption of ionization equilibrium is sound. As we discuss, these and additional findings have strong implications for how accurately currently employed observational absorption line methods recover the true gas properties, and ultimately, our ability to understand the CGM and its role in galaxy evolution.

  17. Magnetic nanoparticles for power absorption: Optimizing size, shape and magnetic properties

    SciTech Connect

    Gonzalez-Fernandez, M.A.; Torres, T.E.; Andres-Verges, M.; Costo, R.; Presa, P. de la; Serna, C.J.; Morales, M.P.; Marquina, C.; Ibarra, M.R.; Goya, G.F.

    2009-10-15

    We present a study on the magnetic properties of naked and silica-coated Fe{sub 3}O{sub 4} nanoparticles with sizes between 5 and 110 nm. Their efficiency as heating agents was assessed through specific power absorption (SPA) measurements as a function of particle size and shape. The results show a strong dependence of the SPA with the particle size, with a maximum around 30 nm, as expected for a Neel relaxation mechanism in single-domain particles. The SiO{sub 2} shell thickness was found to play an important role in the SPA mechanism by hindering the heat outflow, thus decreasing the heating efficiency. It is concluded that a compromise between good heating efficiency and surface functionality for biomedical purposes can be attained by making the SiO{sub 2} functional coating as thin as possible. - Graphical Abstract: The magnetic properties of Fe{sub 3}O{sub 4} nanoparticles from 5 to 110 nm are presented, and their efficiency as heating agents discussed as a function of particle size, shape and surface functionalization.

  18. Optical bistability involving photonic crystal microcavities and Fano line shapes

    NASA Astrophysics Data System (ADS)

    Cowan, A. R.; Young, Jeff F.

    2003-10-01

    The reflectivity of a single-channel waveguide mode upon resonantly coupling to a Kerr-active nonlinear resonant cavity is calculated analytically, including the effects of two-photon absorption. The resonant reflectivity takes the form of a Fano resonance because the solution includes linear reflections from perturbations downstream of the localized cavity. Instead of using a Hamiltonian formulation of the scattering problem, an intuitive set of basis states is used to expand the Green’s function of the electric field wave equation. All resulting overlap functions describing the linear coupling between guided and localized states, and the nonlinear renormalization of the material’s refractive index, are in terms of well-defined physical quantities. Although derived in the context of photonic crystal-based waveguides and cavities, the treatment is valid for any low-loss waveguide-resonator geometry that satisfies specific weak coupling criteria. For a cavity consisting of Al0.18Ga0.82As, hosting a localized mode at 1.55 μm with a Q of 4000 and a mode volume of 0.055 μm3, we predict the onset of bistable reflection at incident powers of ˜40 mW. The downstream reflections lead to hysteresis loops in the reflectivity that are topologically distinct from conventional Lorentzian-derived loops characteristic of isolated Fabry-Perot cavities. We provide a stability argument that reveals the unstable branches of these unique hysteresis loops, and we illustrate some of the rich bistable behaviors that can be engineered with such downstream sources.

  19. Atlas of absorption lines from 0 to 17 900 cm(-1)

    NASA Technical Reports Server (NTRS)

    Park, J. H.; Rothman, L. S.; Rinsland, C. P.; Smith, M. A. H.; Richardson, D. J.; Larsen, J. C.

    1981-01-01

    Plots of absorption line strength versus line position for wavenumbers from 0 to 17,900 cm(-1) are shown for 20 atmospheric gases (H2O, CO2, O3, N2O, CO, CH4, O2, NO, SO2, NO2, NH3, HNO3, OH, HF, HCl, HBr, HI, ClO, OCS, H2CO). Also shown are similar plots of lower-state energy values for adsorption lines for the strongly adsorbing atmospheric gases (H2O, CO2, O3, and CH4) for wavenumbers from 0 to 5000 cm(-1).

  20. Measurement of (222)Rn by absorption in plastic scintillators and alpha/beta pulse shape discrimination.

    PubMed

    Mitev, Krasimir K

    2016-04-01

    This work demonstrates that common plastic scintillators like BC-400, EJ-200 and SCSF-81 absorb radon and their scintillation pulse decay times are different for alpha- and beta-particles. This allows the application of pulse shape analysis for separation of the pulses of alpha- and beta-particles emitted by the absorbed radon and its progeny. It is shown that after pulse shape discrimination of beta-particles' pulses, the energy resolution of BC-400 and EJ-200 alpha spectra is sufficient to separate the peaks of (222)Rn, (218)Po and (214)Po and allows (222)Rn measurements that are unaffected by the presence of thoron ((220)Rn) in the environment. The alpha energy resolution of SCSF-81 in the experiments degrades due to imperfect collection of the light emitted inside the scintillating fibers. The experiments with plastic scintillation microspheres (PSM) confirm previous findings of other researchers that PSM have alpha-/beta-discrimination properties and show suitability for radon measurements. The diffusion length of radon in BC-400 and EJ-200 is determined. The pilot experiments show that the plastic scintillators are suitable for radon-in-soil-gas measurements. Overall, the results of this work suggest that it is possible to develop a new type of radon measurement instruments which employ absorption in plastic scintillators, pulse-shape discrimination and analysis of the alpha spectra. Such instruments can be very compact and can perform continuous, real-time radon measurements and thoron detection. They can find applications in various fields from radiation protection to earth sciences. PMID:26851823

  1. Breit-Wigner-Fano line shapes in Raman spectra of graphene

    NASA Astrophysics Data System (ADS)

    Hasdeo, Eddwi H.; Nugraha, Ahmad R. T.; Dresselhaus, Mildred S.; Saito, Riichiro

    2014-12-01

    Excitation of electron-hole pairs in the vicinity of the Dirac cone by the Coulomb interaction gives rise to an asymmetric Breit-Wigner-Fano line shape in the phonon Raman spectra in graphene. This asymmetric line shape appears due to the interference effect between the phonon spectra and the electron-hole pair excitation spectra. The calculated Breit-Wigner-Fano asymmetric factor 1 /qBWF as a function of the Fermi energy shows a V-shaped curve with a minimum value at the charge neutrality point and gives good agreement with the experimental results.

  2. Absorption-line profiles in a companion spectrum of a mass-losing cool supergiant

    NASA Technical Reports Server (NTRS)

    Rodrigues, Liliya L.; Boehm-Vitense, Erika

    1992-01-01

    Cool star winds can best be observed in resonance absorption lines seen in the spectrum of a hot companion, due to the wind passing in front of the blue star. We calculated absorption line profiles that would be seen in the ultraviolet part of the blue companion spectrum. Line profiles are derived for different radial dependences of the cool star wind and for different orbital phases of the binary. Bowen and Wilson find theoretically that stellar pulsations drive mass loss. We therefore apply our calculations to the Cepheid binary S Muscae which has a B5V companion. We find an upper limit for the Cepheid mass loss of M less than or equal to 7 x 10 (exp -10) solar mass per year provided that the stellar wind of the companion does not influence the Cepheid wind at large distances.

  3. Absorption line profiles in a companion spectrum of a mass losing cool supergiant

    NASA Technical Reports Server (NTRS)

    Rodrigues, Liliya L.; Boehm-Vitense, Erika

    1990-01-01

    Cool star winds can best be observed in resonance absorption lines seen in the spectrum of a hot companion, due to the wind passing in front of the blue star. We calculated absorption line profiles that would be seen in the ultraviolet part of the blue companion spectrum. Line profiles are derived for different radial dependences of the cool star wind and for different orbital phases of the binary. Bowen and Wilson find theoretically that stellar pulsations drive mass loss. We therefore apply our calculations to the Cepheid binary S Muscae which has a B5V companion. We find an upper limit for the Cepheid mass loss of M less than or equal to 7 x 10(exp -10) solar mass per year provided that the stellar wind of the companion does not influence the Cepheid wind at large distances.

  4. Mechanical behavior and shape optimization of lining structure for subsea tunnel excavated in weathered slot

    NASA Astrophysics Data System (ADS)

    Li, Peng-fei; Zhou, Xiao-jun

    2015-12-01

    Subsea tunnel lining structures should be designed to sustain the loads transmitted from surrounding ground and groundwater during excavation. Extremely high pore-water pressure reduces the effective strength of the country rock that surrounds a tunnel, thereby lowering the arching effect and stratum stability of the structure. In this paper, the mechanical behavior and shape optimization of the lining structure for the Xiang'an tunnel excavated in weathered slots are examined. Eight cross sections with different geometric parameters are adopted to study the mechanical behavior and shape optimization of the lining structure. The hyperstatic reaction method is used through finite element analysis software ANSYS. The mechanical behavior of the lining structure is evidently affected by the geometric parameters of crosssectional shape. The minimum safety factor of the lining structure elements is set to be the objective function. The efficient tunnel shape to maximize the minimum safety factor is identified. The minimum safety factor increases significantly after optimization. The optimized cross section significantly improves the mechanical characteristics of the lining structure and effectively reduces its deformation. Force analyses of optimization process and program are conducted parametrically so that the method can be applied to the optimization design of other similar structures. The results obtained from this study enhance our understanding of the mechanical behavior of the lining structure for subsea tunnels. These results are also beneficial to the optimal design of lining structures in general.

  5. Spectral line shapes of L-shell transitions in Ne-like iron

    NASA Astrophysics Data System (ADS)

    Mancini, Roberto C.

    2016-05-01

    Photon-energy-resolved large-scale opacity calculations employ Stark broadened spectral line shapes only to account for the contribution of K-shell line transitions. Detailed ion broadening effects are not considered for L- and M-shell transitions. We present Stark broadening calculations for the line profiles of L-shell transitions linking ground state and singly excited states in Ne-like iron ions. These detailed line shapes have been computed in the standard Stark broadening theory approximation taking into account the effect of both static ions and dynamic electrons. The results show the importance of the ion's effect on the line broadening of several L-shell line transitions.

  6. Spectral shapes of Ar-broadened HCl lines in the fundamental band by classical molecular dynamics simulations and comparison with experiments

    SciTech Connect

    Tran, H.; Domenech, J.-L.

    2014-08-14

    Spectral shapes of isolated lines of HCl perturbed by Ar are investigated for the first time using classical molecular dynamics simulations (CMDS). Using reliable intermolecular potentials taken from the literature, these CMDS provide the time evolution of the auto-correlation function of the dipole moment, whose Fourier-Laplace transform leads to the absorption spectrum. In order to test these calculations, room temperature spectra of various lines in the fundamental band of HCl diluted in Ar are measured, in a large pressure range, with a difference-frequency laser spectrometer. Comparisons between measured and calculated spectra show that the CMDS are able to predict the large Dicke narrowing effect on the shape of HCl lines and to satisfactorily reproduce the shapes of HCl spectra at different pressures and for various rotational quantum numbers.

  7. An isolated line-shape model to go beyond the Voigt profile in spectroscopic databases and radiative transfer codes

    NASA Astrophysics Data System (ADS)

    Ngo, N. H.; Lisak, D.; Tran, H.; Hartmann, J.-M.

    2013-11-01

    We demonstrate that a previously proposed model opens the route for the inclusion of refined non-Voigt profiles in spectroscopic databases and atmospheric radiative transfer codes. Indeed, this model fulfills many essential requirements: (i) it takes both velocity changes and the speed dependences of the pressure-broadening and -shifting coefficients into account. (ii) It leads to accurate descriptions of the line shapes of very different molecular systems. Tests made for pure H2, CO2 and O2 and for H2O diluted in N2 show that residuals are down to ≃0.2% of the peak absorption, (except for the untypical system of H2 where a maximum residual of ±3% is reached), thus fulfilling the precision requirements of the most demanding remote sensing experiments. (iii) It is based on a limited set of parameters for each absorption line that have known dependences on pressure and can thus be stored in databases. (iv) Its calculation requires very reasonable computer costs, only a few times higher than that of a usual Voigt profile. Its inclusion in radiative transfer codes will thus induce bearable CPU time increases. (v) It can be extended in order to take line-mixing effects into account, at least within the so-called first-order approximation.

  8. Self- and Air-Broadened Line Shape Parameters of (12)CH(4) : 4500-4620 cm(-1)

    NASA Astrophysics Data System (ADS)

    Devi, V. Malathy; Benner, D. Chris; Sung, K.; Brown, L. R.; Crawford, T. J.; Smith, M. A. H.; Mantz, A. W.; Predoi-Cross, A.

    2014-06-01

    Accurate knowledge of spectral line shape parameters is important for infrared transmission and radiance calculations in the terrestrial atmosphere. We report the self and air-broadened Lorentz widths, shifts and line mixing coefficients along with their temperature dependencies for methane absorption lines in the 2.2 µm spectral region. For this, we obtained a series of high-resolution, high S/N spectra of 99.99% 12C-enriched samples of pure methane and its dilute mixtures in dry air at cold temperatures down to 150 K using the Bruker IFS 125HR Fourier transform spectrometer at JPL. The coolable absorption cell had an optical path of 20.38 cm and was specially built to reside inside the sample compartment of the Bruker FTS1. The 13 spectra used in the analysis consisted of seven pure 12CH4 spectra at pressures from 4.5 to 169 Torr and six air-broadened spectra with total sample pressures of 113-300 Torr and methane volume mixing ratios between 4 and 9.7%. These 13 spectra were fit simultaneously using the multispectrum least-squares fitting technique2. The results will be compared to existing values reported in the literature3. as part of the GNU EPrints system , and is freely redistributable under the GPL .

  9. Time variations of narrow absorption lines in high resolution quasar spectra

    NASA Astrophysics Data System (ADS)

    Boissé, P.; Bergeron, J.; Prochaska, J. X.; Péroux, C.; York, D. G.

    2015-09-01

    Aims: We have searched for temporal variations of narrow absorption lines in high resolution quasar spectra. A sample of five distant sources were assembled, for which two spectra are available, either VLT/UVES or Keck/HIRES, which were taken several years apart. Methods: We first investigate under which conditions variations in absorption line profiles can be detected reliably from high resolution spectra and discuss the implications of changes in terms of small-scale structure within the intervening gas or intrinsic origin. The targets selected allow us to investigate the time behaviour of a broad variety of absorption line systems by sampling diverse environments: the vicinity of active nuclei, galaxy halos, molecular-rich galaxy disks associated with damped Lyα systems, as well as neutral gas within our own Galaxy. Results: Intervening absorption lines from Mg ii, Fe ii, or proxy species with lines of lower opacity tracing the same kind of (moderately ionised) gas appear in general to be remarkably stable (1σ upper limits as low as 10% for some components on scales in the range 10-100 au), even for systems at zabs ≈ ze. Marginal variations are observed for Mg ii lines towards PKS 1229-021 at zabs = 0.83032; however, we detect no systems that display any change as large as those reported in low resolution SDSS spectra. The lack of clear variations for low β Mg ii systems does not support the existence of a specific population of absorbers made of swept-up gas towards blazars. In neutral or diffuse molecular media, clear changes are seen for Galactic Na i lines towards PKS 1229-02 (decrease in N by a factor of four for one of the five components over 9.7 yr), corresponding to structure on a scale of about 35 au, in good agreement with known properties of the Galactic interstellar medium. Tentative variations are detected for H2J = 3 lines towards FBQS J2340-0053 at zabs = 2.05454 (≃35% change in column density, N, over 0.7 yr in the rest frame), suggesting

  10. Hawaii 167: A compact absorption-line object at z = 2.35

    NASA Technical Reports Server (NTRS)

    Cowie, L. L.; Songaila, A.; Hu, E. M.; Egami, E.; Huang, J.-S.; Pickles, A. J.; Ridgway, S. E.; Wainscoat, R. J.; Weymann, R. J.

    1994-01-01

    During the course of the Hawaii K-band (2.1 micrometer) survey we have detected a compact object, Hawaii 167, lying at a redshift of 2.33, in which are seen both low- and high-ionization absorption lines. In the near-infrared we see broad H alpha emission at a redshift of 2.35 but do not detect the other Balmer lines, (O II) lambda 3727, or (O III) lambda 5007. The absence of strong Mg II or C IV emission in the rest ultraviolet suggests that, at these wavelengths, we may be seeing a poststarburst galaxy rather than a quasar. Indeed, this class of object may be common enough to represent a major episode of galaxy formation, possibly the formation of the spheroids. However, Q0059-2735, the most extreme member of the class of Mg II absorbing broad absorption line quasars, is very similar to the present object, and there may be an evolutionary sequence or some other close connection between Hawaii 167 and the broad absorption line quasars.

  11. [Laser induced breakdown spectra of coal sample and self-absorption of the spectral line].

    PubMed

    Zhang, Gui-yin; Ji, Hui; Jin, Yi-dong

    2014-12-01

    The LIBS of one kind of household fuel coal was obtained with the first harmonic output 532 nm of an Nd·YAG laser as radiation source. With the assignment of the spectral lines, it was found that besides the elements C, Si, Mg, Fe, Al, Ca, Ti, Na and K, which are reported to be contained in coal, the presented sample also contains trace elements, such as Cd, Co, Hf, Ir, Li, Mn, Ni, Rb, Sr, V, W, Zn, Zr etc, but the spectral lines corresponding to O and H elements did not appear in the spectra. This is owing to the facts that the transition probability of H and O atoms is small and the energy of the upper level for transition is higher. The results of measurement also show that the intensity of spectral line increases with the laser pulse energy and self-absorption of the spectral lines K766.493 nm and K769.921 nm will appear to some extent. Increasing laser energy further will make self-absorption more obvious. The presence of self-absorption can be attributed to two factors. One is the higher transition rate of K atoms, and the other is that the increase in laser intensity induces the enhancement of the particle number density in the plasma. PMID:25881446

  12. THE PHYSICAL CONDITIONS OF THE INTRINSIC N V NARROW ABSORPTION LINE SYSTEMS OF THREE QUASARS

    SciTech Connect

    Wu Jian; Charlton, Jane C.; Misawa, Toru; Eracleous, Michael; Ganguly, Rajib E-mail: misawatr@shinshu-u.ac.j

    2010-10-20

    We employ detailed photoionization models to infer the physical conditions of intrinsic narrow absorption line systems found in high-resolution spectra of three quasars at z = 2.6-3.0. We focus on a family of intrinsic absorbers characterized by N V lines that are strong relative to the Ly{alpha} lines. The inferred physical conditions are similar for the three intrinsic N V absorbers, with metallicities greater than 10 times the solar value (assuming a solar abundance pattern), and with high ionization parameters (log U {approx} 0). Thus, we conclude that the unusual strength of the N V lines results from a combination of partial coverage, a high ionization state, and high metallicity. We consider whether dilution of the absorption lines by flux from the broad emission line region can lead us to overestimate the metallicities and we find that this is an unlikely possibility. The high abundances that we infer are not surprising in the context of scenarios in which metal enrichment takes place very early on in massive galaxies. We estimate that the mass outflow rate in the absorbing gas (which is likely to have a filamentary structure) is less than a few M{sub sun} yr{sup -1} under the most optimistic assumptions, although it may be embedded in a much hotter, more massive outflow.

  13. On the Origin of the Wide HI Absorption Line Towards Sgr A *

    NASA Astrophysics Data System (ADS)

    Dwarakanath, K. S.; Goss, W. M.; Zhao, J. H.; Lang, C. C.

    2004-09-01

    We have imaged a region of ~5 extent surrounding Sgr A* in the HI 21 cm-line absorption using the Very Large Array. A Gaussian decomposition of the optical depth spectra at positions within ~2(~5 pcat 8.5 kpc) of Sgr A* detects a wide linw underlying the many narrow absorption lines. The wide line has a mean peak optical depth of 0.32 ± 0.12 centered at a mean velocity of Vlsr = -4 ± 15 km s-1. The mean full width half maximum is 119 ± 42 km s-1. Such a wide line is absent in the spectra at positions beyond ~2 from Sgr A*. The position-velocity diagrams do not reveal any diffuse feature which could be attributed to a large number of HI clouds along the line of sight to Sgr A*. Consequently, the wide line has no implications either to a global population of shocked HI clouds in the Galaxy or to the energetics of the interstellar medium as was earlier thought.

  14. The Suzaku Observation of NGC 3516: Complex Absorption and the Broad and Narrow Fe K Lines

    NASA Technical Reports Server (NTRS)

    Markowitz, Alex; Reeves, James N.; Miniutti, Giovanni; Serlemitsos, Peter; Kunieda, Hideyo; Taqoob, Tahir; Fabian, Andrew C.; Fukazawa, Yasushi; Mushotzky, Richard; Okajima, Takashi; Gallo, Luigi; Awaki, Hisamitsu; Griffiths, Richard E.

    2007-01-01

    We present results from a 150 ksec Suzaku observation of the Seyfert 1 NGC 3516 in October 2005. The source was in a relatively highly absorbed state. Our best-fit model is consistent with partial covering by a lowly-ionized absorber with a column density near 5x10(exp 22) cm(exp -2) and with a covering fraction 96-100 percent. Narrow K-shell absorption features due to He- and H-like Fe confirm the presence of a high-ionization absorbing component as well. A broad Fe K(alpha) diskline is required in all fits, even after the complex absorption is taken into account; an additional partial-covering component is an inadequate substitute for the continuum curvature associated with the broad line. The narrow Fe Ka line at 6.4 keV is resolved, yielding a velocity width commensurate with the optical Broad Line Region. The strength of the Compton reflection hump suggests a contribution mainly from the broad Fe line origin. We include in our model soft band emission lines from He- and H-like ions and radiative recombination lines, consistent with photo-ionization, though a small contribution from collisional ionization is possible.

  15. Dust depletion of Ca and Ti in QSO absorption-line systems

    NASA Astrophysics Data System (ADS)

    Guber, C. R.; Richter, P.

    2016-06-01

    Aims: To explore the role of titanium- and calcium-dust depletion in gas in and around galaxies, we systematically study Ti/Ca abundance ratios in intervening absorption-line systems at low and high redshift. Methods: We investigate high-resolution optical spectra obtained by the UVES instrument at the Very Large Telescope (VLT) and spectroscopically analyze 34 absorption-line systems at z ≤ 0.5 to measure column densities (or limits) for Ca ii and Ti ii. We complement our UVES data set with previously published absorption-line data on Ti/Ca for redshifts up to z ~ 3.8. Our absorber sample contains 110 absorbers including damped Lyman α systems (DLAs), sub-DLAs, and Lyman-Limit systems (LLS). We compare our Ti/Ca findings with results from the Milky Way and the Magellanic Clouds and discuss the properties of Ti/Ca absorbers in the general context of quasar absorption-line systems. Results: Our analysis indicates that there are two distinct populations of absorbers with either high or low Ti/Ca ratios with a separation at [Ti/Ca] ≈ 1. While the calcium-dust depletion in most of the absorbers appears to be severe, the titanium depletions are mild in systems with high Ti/Ca ratios. The derived trend indicates that absorbers with high Ti/Ca ratios have dust-to-gas ratios that are substantially lower than in the Milky Way. We characterize the overall nature of the absorbers by correlating Ti/Ca with other observables (e.g., metallicity, velocity-component structure) and by modeling the ionization properties of singly-ionized Ca and Ti in different environments. Conclusions: We conclude that Ca ii and Ti ii bearing absorption-line systems trace predominantly neutral gas in the disks and inner halo regions of galaxies, where the abundance of Ca and Ti reflects the local metal and dust content of the gas. Our study suggests that the Ti/Ca ratio represents a useful measure for the gas-to-dust ratio and overall metallicity in intervening absorption-line systems.

  16. Line parameters including temperature dependences of air- and self-broadened line shapes of 12C16O2: 2.06-μm region

    NASA Astrophysics Data System (ADS)

    Benner, D. Chris; Devi, V. Malathy; Sung, Keeyoon; Brown, Linda R.; Miller, Charles E.; Payne, Vivienne H.; Drouin, Brian J.; Yu, Shanshan; Crawford, Timothy J.; Mantz, Arlan W.; Smith, Mary Ann H.; Gamache, Robert R.

    2016-08-01

    This study reports the results from analyzing a number of high resolution, high signal-to-noise ratio (S/N) spectra in the 2.06-μm spectral region for pure CO2 and mixtures of CO2 in dry air. A multispectrum nonlinear least squares curve fitting technique has been used to retrieve the various spectral line parameters. The dataset includes 27 spectra: ten pure CO2, two 99% 13C-enriched CO2 and fifteen spectra of mixtures of 12C-enriched CO2 in dry air. The spectra were recorded at various gas sample temperatures between 170 and 297 K. The absorption path lengths range from 0.347 to 49 m. The sample pressures for the pure CO2 spectra varied from 1.1 to 594 Torr; for the two 13CO2 spectra the pressures were ∼10 and 146 Torr. For the air-broadened spectra, the pressures of the gas mixtures varied between 200 and 711 Torr with CO2 volume mixing ratios ranging from 0.014% to 0.203%. The multispectrum fitting technique was applied to fit simultaneously all these spectra to retrieve consistent set of line positions, intensities, and line shape parameters including their temperature dependences; for this, the Voigt line shape was modified to include line mixing (via the relaxation matrix formalism) and quadratic speed dependence. The new results are compared to select published values, including recent ab initio calculations. These results are required to retrieve the column averaged dry air mole fraction (XCO2) from space-based observations, such as the Orbiting Carbon Observatory-2 (OCO-2) satellite mission that NASA launched in July 2014.

  17. Reionisation and High-Redshift Galaxies: The View from Quasar Absorption Lines

    NASA Astrophysics Data System (ADS)

    Becker, George D.; Bolton, James S.; Lidz, Adam

    2015-12-01

    Determining when and how the first galaxies reionised the intergalactic medium promises to shed light on both the nature of the first objects and the cosmic history of baryons. Towards this goal, quasar absorption lines play a unique role by probing the properties of diffuse gas on galactic and intergalactic scales. In this review, we examine the multiple ways in which absorption lines trace the connection between galaxies and the intergalactic medium near the reionisation epoch. We first describe how the Ly α forest is used to determine the intensity of the ionising ultraviolet background and the global ionising emissivity budget. Critically, these measurements reflect the escaping ionising radiation from all galaxies, including those too faint to detect directly. We then discuss insights from metal absorption lines into reionisation-era galaxies and their surroundings. Current observations suggest a buildup of metals in the circumgalactic environments of galaxies over z ~ 6 to 5, although changes in ionisation will also affect the evolution of metal line properties. A substantial fraction of metal absorbers at these redshifts may trace relatively low-mass galaxies. Finally, we review constraints from the Ly α forest and quasar near zones on the timing of reionisation. Along with other probes of the high-redshift Universe, absorption line data are consistent with a relatively late end to reionisation (5.5 ≲ z ≲ 7); however, the constraints are still fairly week. Significant progress is expected to come through improved analysis techniques, increases in the number of known high-redshift quasars from optical and infrared sky surveys, large gains in sensitivity from next-generation observing facilities, and synergies with other probes of the reionisation era.

  18. N-H stretching vibrations of guanosine-cytidine base pairs in solution: ultrafast dynamics, couplings, and line shapes.

    PubMed

    Fidder, Henk; Yang, Ming; Nibbering, Erik T J; Elsaesser, Thomas; Röttger, Katharina; Temps, Friedrich

    2013-02-01

    Dynamics and couplings of N-H stretching vibrations of chemically modified guanosine-cytidine (G·C) base pairs in chloroform are investigated with linear infrared spectroscopy and ultrafast two-dimensional infrared (2D-IR) spectroscopy. Comparison of G·C absorption spectra before and after H/D exchange reveals significant N-H stretching absorption in the region from 2500 up to 3300 cm(-1). Both of the local stretching modes ν(C)(NH(2))(b) of the hydrogen-bonded N-H moiety of the cytidine NH(2) group and ν(G)(NH) of the guanosine N-H group contribute to this broad absorption band. Its complex line shape is attributed to Fermi resonances of the N-H stretching modes with combination and overtones of fingerprint vibrations and anharmonic couplings to low-frequency modes. Cross-peaks in the nonlinear 2D spectra between the 3491 cm(-1) free N-H oscillator band and the bands centered at 3145 and 3303 cm(-1) imply N-H···O═C hydrogen bond character for both of these transitions. Time evolution illustrates that the 3303 cm(-1) band is composed of a nearly homogeneous band absorbing at 3301 cm(-1), ascribed to ν(G)(NH(2))(b), and a broad inhomogeneous band peaking at 3380 cm(-1) with mainly guanosine carbonyl overtone character. Kinetics and signal strengths indicate a <0.2 ps virtually complete population transfer from the excited ν(G)(NH(2))(b) mode to the ν(G)(NH) mode at 3145 cm(-1), suggesting lifetime broadening as the dominant source for the homogeneous line shape of the 3301 cm(-1) transition. For the 3145 cm(-1) band, a 0.3 ps population lifetime was obtained. PMID:23317104

  19. Remote estimation of phytoplankton size fractions using the spectral shape of light absorption.

    PubMed

    Wang, Shengqiang; Ishizaka, Joji; Hirawake, Toru; Watanabe, Yuji; Zhu, Yuanli; Hayashi, Masataka; Yoo, Sinjae

    2015-04-20

    Phytoplankton size structure plays an important role in ocean biogeochemical processes. The light absorption spectra of phytoplankton provide a great potential for retrieving phytoplankton size structure because of the strong dependence on the packaging effect caused by phytoplankton cell size and on different pigment compositions related to phytoplankton taxonomy. In this study, we investigated the variability in light absorption spectra of phytoplankton in relation to the size structure. Based on this, a new approach was proposed for estimating phytoplankton size fractions. Our approach use the spectral shape of the normalized phytoplankton absorption coefficient (a(ph)(λ)) through principal component analysis (PCA). Values of a(ph)(λ) were normalized to remove biomass effects, and PCA was conducted to separate the spectral variance of normalized a(ph)(λ) into uncorrelated principal components (PCs). Spectral variations captured by the first four PC modes were used to build relationships with phytoplankton size fractions. The results showed that PCA had powerful ability to capture spectral variations in normalized a(ph)(λ), which were significantly related to phytoplankton size fractions. For both hyperspectral a(ph)(λ) and multiband a(ph)(λ), our approach is applicable. We evaluated our approach using wide in situ data collected from coastal waters and the global ocean, and the results demonstrated a good and robust performance in estimating phytoplankton size fractions in various regions. The model performance was further evaluated by a(ph)(λ) derived from in situ remote sensing reflectance (R(rs)(λ)) with a quasi-analytical algorithm. Using R(rs)(λ) only at six bands, accurate estimations of phytoplankton size fractions were obtained, with R(2) values of 0.85, 0.61, and 0.76, and root mean-square errors of 0.130, 0.126, and 0.112 for micro-, nano-, and picophytoplankton, respectively. Our approach provides practical basis for remote estimation of

  20. The Hubble Space Telescope quasar absorption line key project. III - First observational results on Milky Way gas

    NASA Technical Reports Server (NTRS)

    Savage, Blair D.; Lu, Limin; Bahcall, John N.; Bergeron, Jacqueline; Boksenberg, Alec; Hartig, George F.; Jannuzi, Buell T.; Kirhakos, Sofia; Lockman, Felix J.; Sargent, W. L. W.

    1993-01-01

    Absorption lines found near zero redshift due to Milky Way disk and halo gas in the spectra of 15 quasars observed with the Faint Object Spectrograph (FOS) of the HST at a resolution of about 230 km/s are reported. Results show that Milky Way absorption lines comprise about 44 percent of all absorption lines seen in the first group of Key Project FOS spectra. Milky Way lines were observed for 3C 273 and H1821 + 643. Limits to the Mg-to-H abundance ratio obtained for very high velocity Mg II absorption detections imply gas-phase Mg abundances for the very high velocity gas ranging from more than 0.059 to more than 0.32 times the solar abundance. In all cases where high-velocity H I emission is seen, corresponding high-velocity metal-line absorption is observed.

  1. Spectral line shapes of self-broadened P-branch transitions of oxygen B band

    NASA Astrophysics Data System (ADS)

    Wójtewicz, S.; Cygan, A.; Masłowski, P.; Domysławska, J.; Lisak, D.; Trawiński, R. S.; Ciuryło, R.

    2014-09-01

    We used the Pound-Drever-Hall-locked frequency-stabilized cavity ring-down spectrometer assisted by the optical frequency comb for systematic line-shape study of self-broadened P-branch transitions of the O216B band [b1Σg+(v=1)←X3Σg-(v=0)]. In the line-shape analysis we take into account the line-narrowing effects described by Dicke narrowing or the speed dependence of collisional broadening. The relation between the parameters describing Dicke narrowing with the use of the soft- and hard-collision models is discussed and verified experimentally in the low pressure regime using the multispectrum fitting technique. We report line positions with uncertainties of about 170 kHz, the collisional broadening coefficients with 0.45% uncertainties, and line intensities with 0.5% uncertainties. We compare these results to data available in the literature.

  2. Interstellar absorption in the Mg II resonance line k2 and h2 emissions

    NASA Technical Reports Server (NTRS)

    Boehm-Vitense, E.

    1981-01-01

    High-resolution (0.2 A) IUE spectra for the long wavelength range (1800-3000 A) have been studied. It is shown that narrow interstellar Mg II lines are seen in the center of the k2 and h2 emissions from nearby stars with large rotational velocities. For all observed stars, the radial velocity of the central k3 absorption component in the rest system of the star is strongly correlated with the mirror image of the radial velocity of the stars; this shows that a major fraction if not all of the k3 absorption is due to interstellar absorption in the solar neighborhood. The violet to red asymmetry of the k2 emission also correlates with the radial velocities of the star; this shows that the shift of k3 is due to the velocity shift of the local interstellar cloud with respect to the star.

  3. The Hubble Space Telescope Quasar Absorption Line Key Project. XIV. The Evolution of Lyα Absorption Lines in the Redshift Interval z = 0-1.5

    NASA Astrophysics Data System (ADS)

    Weymann, Ray J.; Jannuzi, Buell T.; Lu, Limin; Bahcall, John N.; Bergeron, Jacqueline; Boksenberg, Alec; Hartig, George F.; Kirhakos, Sofia; Sargent, W. L. W.; Savage, Blair D.; Schneider, Donald P.; Turnshek, David A.; Wolfe, Arthur M.

    1998-10-01

    We present the results of an analysis of the rate of evolution of the Lyα absorption lines in the redshift interval 0.0 to ~1.5 based upon a sample of 987 Lyα absorption lines identified in the spectra of 63 QSOs obtained with the Faint Object Spectrograph (FOS) of the Hubble Space Telescope (HST). These spectra were obtained as part of the QSO Absorption Line Survey, an HST Key Project during the first four years of observations with the telescope. Fits to the evolution of the number of absorbers per unit redshift (dN/dz) of the form dN/dz = A × (1 + z)γ continue to yield values of γ in the range 0.1-0.3, decidedly flatter than results from ground-based data pertaining to the redshift range z > 1.7. These results are consistent with our previous results based on a much smaller sample of lines, but the uncertainties in the fit have been greatly reduced. The combination of the HST and ground-based data suggest a marked transition in the rate of evolution of the Lyα lines at a redshift of about 1.7. The 19 Lyα lines from an additional higher redshift QSO from our sample for which tentative line identifications are available (UM 18; zem = 1.89) support the suggestion of a rapid increase at around this redshift. We derive the cumulative distribution of the full sample of Lyα lines and show that the distribution in redshift can indeed be well represented by a power law of the form (1 + z)γ. For this same sample, the distribution of equivalent widths of the Lyα absorbers above a rest equivalent width of 0.1 Å is fit quite well by an exponential. Comparing samples of Lyα lines, one set of which has redshifts the same as, or very near to, the redshifts of ions from heavy elements and another set in which no ions from heavy elements have been identified, we find that the Lyα systems with heavy element detections have a much steeper slope than the high rest equivalent width portion of the Lyman-only sample. We argue that this result is not likely to be due to

  4. Effect of higher-order multipole moments on the Stark line shape

    NASA Astrophysics Data System (ADS)

    Gomez, T. A.; Nagayama, T.; Kilcrease, D. P.; Montgomery, M. H.; Winget, D. E.

    2016-08-01

    Spectral line shapes are sensitive to plasma conditions and are often used to diagnose electron density of laboratory plasmas as well as astrophysical plasmas. Stark line-shape models take into account the perturbation of the radiator's energy structure due to the Coulomb interaction with the surrounding charged particles. Solving this Coulomb interaction is challenging and is commonly approximated via a multipole expansion. However, most models include only up to the second term of the expansion (the dipole term). While there have been studies on the higher-order terms due to one of the species (i.e., either ions or electrons), there is no model that includes the terms beyond dipole from both species. Here, we investigate the importance of the higher-order multipole terms from both species on the Hβ line shape. First, we find that it is important to include higher-order terms consistently from both ions and electrons to reproduce measured line-shape asymmetry. Next, we find that the line shape calculated with the dipole-only approximation becomes inaccurate as density increases. It is necessary to include up to the third (quadrupole) term to compute the line shape accurately within 2%. Since most existing models include only up to the dipole terms, the densities inferred with such models are in question. We find that the model without the quadrupole term slightly underestimates the density, and the discrepancy becomes as large as 12% at high densities. While the case of study is limited to Hβ, we expect similar impact on other lines.

  5. Effect of higher-order multipole moments on the Stark line shape

    NASA Astrophysics Data System (ADS)

    Gomez, T. A.; Nagayama, T.; Kilcrease, D. P.; Montgomery, M. H.; Winget, D. E.

    2016-08-01

    Spectral line shapes are sensitive to plasma conditions and are often used to diagnose electron density of laboratory plasmas as well as astrophysical plasmas. Stark line-shape models take into account the perturbation of the radiator's energy structure due to the Coulomb interaction with the surrounding charged particles. Solving this Coulomb interaction is challenging and is commonly approximated via a multipole expansion. However, most models include only up to the second term of the expansion (the dipole term). While there have been studies on the higher-order terms due to one of the species (i.e., either ions or electrons), there is no model that includes the terms beyond dipole from both species. Here, we investigate the importance of the higher-order multipole terms from both species on the H β line shape. First, we find that it is important to include higher-order terms consistently from both ions and electrons to reproduce measured line-shape asymmetry. Next, we find that the line shape calculated with the dipole-only approximation becomes inaccurate as density increases. It is necessary to include up to the third (quadrupole) term to compute the line shape accurately within 2%. Since most existing models include only up to the dipole terms, the densities inferred with such models are in question. We find that the model without the quadrupole term slightly underestimates the density, and the discrepancy becomes as large as 12% at high densities. While the case of study is limited to H β , we expect similar impact on other lines.

  6. Ultraviolet Fe VII absorption lines in planetary nebula nuclei, hot subdwarfs, and hot degenerate objects

    NASA Technical Reports Server (NTRS)

    Feibelman, Walter A.; Bruhweiler, Frederick C.

    1990-01-01

    Results are reported from a search for Fe VII absorption lines in data from high-dispersion IUE-SWP observations of PN nuclei (PNN), hot subdwarfs (HSDs), and hot white dwarfs (HWDs). The data-reduction techniques employed are outlined, and the results are presented in extensive tables and sample spectra and characterized in detail. Absorption in at least one of the four Fe VII lines above 120 nm wavelength is found in 22 of 51 PNN, and possibly in 10 HSDs, in the pulsating HWD PG 1159 - 035, and in the PNN K1 - 16. It is concluded that Fe VII is more common in WD progenitors such as PNN than previously predicted and is especially typical of the more luminous low-gravity stars.

  7. Discovery of an X-ray Violently Variable Broad Absorption Line Quasar

    NASA Technical Reports Server (NTRS)

    Ghosh, Kajal K.; Gutierrez, Carlos M.; Punsly, Brian; Chevallier, Loic; Goncalves, Anabela C.

    2006-01-01

    In this letter, we report on a quasar that is violently variable in the X-rays, XVV. It is also a broad absorption line quasar (BALQSO) that exhibits both high ionization and low ionization UV absorption lines (LoBALQSO). It is very luminous in the X-rays (approximately 10(exp 46) ergs s(sup -l) over the entire X-ray band). Surprisingly, this does not over ionize the LoBAL outflow. The X-rays vary by a factor of two within minutes in the quasar rest frame, which is shorter than 1/30 of the light travel time across a scale length equal to the black hole radius. We concluded that the X-rays are produced in a relativistic jet beamed toward earth in which variations in the Doppler enhancement produce the XVV behavior.

  8. Neutral atomic absorption lines and far-UV extinction: Possible implications for depletions and grain parameters

    NASA Astrophysics Data System (ADS)

    Welty, Daniel E.

    1990-07-01

    Researchers examine nine lines of sight within the Galaxy and one in the Large Magellanic Cloud (LMC) for which data on both neutral atomic absorption lines (Snow 1984; White 1986; Welty, Hobbs, and York 1989) and far UV extinction (Bless and Savage 1972; Jenkins, Savage, and Spitzer 1986) are available, in order to test the assumption that variations in gamma/alpha will cancel in taking ratios of the ionization balance equation, and to try to determine to what extent that assumption has affected the aforementioned studies of depletions and grain properties.

  9. The VLBI structure of radio-loud Broad Absorption Line quasars

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Jiang, D. R.; Gu, M.

    2016-02-01

    The nature and origin of Broad Absorption Line (BAL) quasars and their relationship to non-BAL quasars are an open question. The BAL quasars are probably normal quasars seen along a particular line of sight. Alternatively, they are young or recently refueled. The high resolution radio morphology of BAL quasars is very important to understand the radio properties of BAL quasars. We present VLBA observations at L and C bands for a sample of BAL quasars. The observations will help us to explore the VLBI radio properties, and distinguish the present models of explaining BAL phenomena.

  10. Neutral atomic absorption lines and far-UV extinction: Possible implications for depletions and grain parameters

    NASA Technical Reports Server (NTRS)

    Welty, Daniel E.

    1990-01-01

    Researchers examine nine lines of sight within the Galaxy and one in the Large Magellanic Cloud (LMC) for which data on both neutral atomic absorption lines (Snow 1984; White 1986; Welty, Hobbs, and York 1989) and far UV extinction (Bless and Savage 1972; Jenkins, Savage, and Spitzer 1986) are available, in order to test the assumption that variations in gamma/alpha will cancel in taking ratios of the ionization balance equation, and to try to determine to what extent that assumption has affected the aforementioned studies of depletions and grain properties.

  11. Wavelength Locking to CO2 Absorption Line-Center for 2-Micron Pulsed IPDA Lidar Application

    NASA Technical Reports Server (NTRS)

    Refaat, Tamer F.; Petros, Mulugeta; Antill, Charles W.; Singh, Upendra N.; Yu, Jirong

    2016-01-01

    An airborne 2-micron triple-pulse integrated path differential absorption (IPDA) lidar is currently under development at NASA Langley Research Center (LaRC). This IPDA lidar system targets both atmospheric carbon dioxide (CO2) and water vapor (H2O) column measurements. Independent wavelength control of each of the transmitted laser pulses is a key feature for the success of this instrument. The wavelength control unit provides switching, tuning and locking for each pulse in reference to a 2-micron CW (Continuous Wave) laser source locked to CO2 line-center. Targeting the CO2 R30 line center, at 2050.967 nanometers, a wavelength locking unit has been integrated using semiconductor laser diode. The CO2 center-line locking unit includes a laser diode current driver, temperature controller, center-line locking controller and CO2 absorption cell. This paper presents the CO2 center-line locking unit architecture, characterization procedure and results. Assessment of wavelength jitter on the IPDA measurement error will also be addressed by comparison to the system design.

  12. Surprises from a Deep ASCA Spectrum of the Broad Absorption Line Quasar PHL 5200

    NASA Technical Reports Server (NTRS)

    Mathur, Smita; Matt, G.; Green, P. J.; Elvis, M.; Singh, K. P.

    2002-01-01

    We present a deep (approx. 85 ks) ASCA observation of the prototype broad absorption line quasar (BALQSO) PHL 5200. This is the best X-ray spectrum of a BALQSO yet. We find the following: (1) The source is not intrinsically X-ray weak. (2) The line-of-sight absorption is very strong, with N(sub H) = 5 x 10(exp 23)/sq cm. (3) The absorber does not cover the source completely; the covering fraction is approx. 90%. This is consistent with the large optical polarization observed in this source, implying multiple lines of sight. The most surprising result of this observation is that (4) the spectrum of this BALQSO is not exactly similar to other radio-quiet quasars. The hard X-ray spectrum of PHL 5200 is steep, with the power-law spectral index alpha approx. 1.5. This is similar to the steepest hard X-ray slopes observed so far. At low redshifts, such steep slopes are observed in narrow-line Seyfert 1 (NLS1) galaxies, believed to be accreting at a high Eddington rate. This observation strengthens the analogy between BALQSOs and NLS1 galaxies and supports the hypothesis that BALQSOs represent an early evolutionary state of quasars. It is well accepted that the orientation to the line of sight determines the appearance of a quasar: age seems to play a significant role as well.

  13. The spatial and kinematic structure of QSO metal-line absorption systems

    NASA Technical Reports Server (NTRS)

    Lanzetta, Kenneth M.

    1992-01-01

    Recent attempts to infer the spatial and kinematic distributions of the material responsible for absorption lines observed in the spectra of background QSOs are presented. Current models of the absorbing regions are compared, and initial observational results are described. This research is expected to lead eventually to a detailed picture of the extended gaseous halo regions of galaxies at early evolutionary stages and to an understanding of the physical processes at work in these halos.

  14. What Quasars Really Look Like: Unification of the Emission and Absorption Line Regions

    NASA Technical Reports Server (NTRS)

    Elvis, Martin

    2000-01-01

    We propose a simple unifying structure for the inner regions of quasars and AGN. This empirically derived model links together the broad absorption line (BALS), the narrow UV/X-ray ionized absorbers, the BELR, and the 5 Compton scattering/fluorescing regions into a single structure. The model also suggests an alternative origin for the large-scale bi-conical outflows. Some other potential implications of this structure are discussed.

  15. The Evolution of Quasar C IV and Si IV Broad Absorption Lines over Multi-year Timescales

    NASA Astrophysics Data System (ADS)

    Gibson, Robert R.; Brandt, W. N.; Gallagher, S. C.; Hewett, Paul C.; Schneider, Donald P.

    2010-04-01

    We investigate the variability of C IV λ1549 broad absorption line (BAL) troughs over rest-frame timescales of up to ≈7 yr in 14 quasars at redshifts z >~ 2.1. For nine sources at sufficiently high redshift, we also compare the C IV and Si IV λ1400 absorption variation. We compare shorter and longer term variability using spectra from up to four different epochs per source and find complex patterns of variation in the sample overall. The scatter in the change of absorption equivalent width (EW), ΔEW, increases with the time between observations. BALs do not, in general, strengthen or weaken monotonically, and variation observed over shorter (lsimmonths) timescales is not predictive of multi-year variation. We find no evidence for asymmetry in the distribution of ΔEW that would indicate that BALs form and decay on different timescales, and we constrain the typical BAL lifetime to be gsim30 yr. The BAL absorption for one source, LBQS 0022+0150, has weakened and may now be classified as a mini-BAL. Another source, 1235+1453, shows evidence of variable, blue continuum emission that is relatively unabsorbed by the BAL outflow. C IV and Si IV BAL shape changes are related in at least some sources. Given their high velocities, BAL outflows apparently traverse large spatial regions and may interact with parsec-scale structures such as an obscuring torus. Assuming BAL outflows are launched from a rotating accretion disk, notable azimuthal symmetry is required in the outflow to explain the relatively small changes observed in velocity structure over times up to 7 yr.

  16. Spectroscopic Line Shapes of Vibrational Quanta in the Presence of Molecular Resonances.

    PubMed

    Meierott, Stefan; Néel, Nicolas; Kröger, Jörg

    2016-07-01

    Line shapes of molecular vibrational quanta in inelastic electron tunneling spectroscopy may indicate the strength of electron-vibration coupling, the hybridization of the molecule with its environment, and the degree of vibrational damping by electron-hole pair excitation. Bare as well as C60-terminated Pb tips of a scanning tunneling microscope and clean as well as C60-covered Pb(111) surfaces were used in low-temperature experiments. Depending on the overlap of orbital and vibrational spectral ranges different spectroscopic line shapes of molecular vibrational quanta were observed. The energy range covered by the molecular resonance was altered by modifying the adsorption configuration of the molecule terminating the tip apex. Concomitantly, the line shapes of different vibrational modes were affected. The reported observations represent an experimental proof to theoretical predictions on the contribution from resonant processes to inelastic electron tunneling. PMID:27280313

  17. Line shapes in CP/MAS NMR spectra of half-integer quadrupolar nuclei

    NASA Astrophysics Data System (ADS)

    Hayashi, Shigenobu; Hayamizu, Kikuko

    1993-02-01

    Cross polarization (CP) from 1H to quadrupolar nuclei with S = 3/2 has been carried out under magic-angle-spinning (MAS) conditions for powder samples of Na 2B 4O 7·10H 2O and H 3BO 3. The line shapes in the CP/MAS NMR spectra are different from those in the spectra measured with the single pulse sequence combined with 1H dipolar decoupling. Furthermore, the line shapes are found to be dependent on the measuring conditions such as the pulse amplitude for the quadrupolar nuclei. The spin-locking experiments demonstrate that line shapes in CP/MAS NMR spectra are largely dependent on the spin-locking efficiency.

  18. Line shapes in sub-Doppler DAVLL in the 87Rb-D2 line

    NASA Astrophysics Data System (ADS)

    Choi, Gyeong-Won; Noh, Heung-Ryoul

    2016-05-01

    We present a theoretical and experimental study of the sub-Doppler dichroic atomic vapor laser lock (DAVLL) for the D2 transition line of 87Rb atoms. The experimental results of the sub-Doppler DAVLL spectra are compared with calculated results using both accurate density matrix equations and approximate rate equations. We find good agreement between the experimental and calculated results. In particular, the coherence effect must be included in the signal for the cycling transition line.

  19. The HST quasar absorption line key project. 4: HST faint-object spectrograph and ground-based observations of the unusual low-redshift broad absorption-line quasi-stellar object PG 0043+039

    NASA Technical Reports Server (NTRS)

    Turnshek, David A.; Espey, Brian R.; Kopko, Michael, Jr.; Rauch, Michael; Weymann, Ray J.; Jannuzi, Buell T.; Boksenberg, Alec; Bergeron, Jacqueline; Hartig, George F.; Sargent, W. L. W.

    1994-01-01

    Hubble Space Telescope Faint Object Spectrograph (HST FOS) observations have shown that the spectrum of the low-redshift (z(sub em) approximately equal to 0.384) QSO PG 0043+039 exhibits weak broad absorption lines (BALs). The BALs were discovered during the course of UV spectrophotometry made for the HST Quasar Absorption Line Key Project. The HST data are analyzed along with ground-based optical and IUE spectrophotometry. The object is found to have a number of atypical properties relative to normal non-BAL QSOs. The observed continuum is atypical in the sense that it is much weaker than that of a normal optically selected QSO at rest wavelengths approximately less than 2200 A. Intrinsic reddening of E(B-V) approximately equal to 0.11 mag by dust similar to that found in the SMC at the redshift of PG 0043+039 conservatively accounts for the observed continuum shape moderately well. These observed characteristics are typical of low-ionization BAL QSOs, but convincing evidence for BALs due to low-ionization transitions of Mg II, Al III, Al II, or C II does not exist. Therefore, this object may be a misaligned BAL QSO having many of the characteristics of low-ionization BAL QSOs with the sight line passing through a putative dusty region, but evidently missing clouds of high enough column density to produce observable low-ionization BALs. If the intrinsic dust-extinction model is correct, the observations suggest that the dust is not confined to the presumably higher density, low-ionization BAL clouds, but that it has drifted to nearby high-ionization BAL regions. We also consider other possible mechanisms for producing the shape of the continuous energy distribution which cannot be ruled out. We compare the Fe II emission in PG 0043+039 with that in another Key Project QSO, NGC 2841-UB 3, which has optical Fe II emission comparable in strength to that in PG 0043+039, but has anomalously weak UV Fe II emission. In addition, from an analysis of UV and optical

  20. The Sloan Digital Sky Survey Reverberation Mapping Project: Rapid CIV Broad Absorption Line Variability

    NASA Astrophysics Data System (ADS)

    Grier, C. J.; Hall, P. B.; Brandt, W. N.; Trump, J. R.; Shen, Yue; Vivek, M.; Filiz Ak, N.; Chen, Yuguang; Dawson, K. S.; Denney, K. D.; Green, Paul J.; Jiang, Linhua; Kochanek, C. S.; McGreer, Ian D.; Pâris, I.; Peterson, B. M.; Schneider, D. P.; Tao, Charling; Wood-Vasey, W. M.; Bizyaev, Dmitry; Ge, Jian; Kinemuchi, Karen; Oravetz, Daniel; Pan, Kaike; Simmons, Audrey

    2015-06-01

    We report the discovery of rapid variations of a high-velocity C iv broad absorption line trough in the quasar SDSS J141007.74+541203.3. This object was intensively observed in 2014 as a part of the Sloan Digital Sky Survey Reverberation Mapping Project, during which 32 epochs of spectroscopy were obtained with the Baryon Oscillation Spectroscopic Survey spectrograph. We observe significant (>4σ) variability in the equivalent width (EW) of the broad (˜4000 km s-1 wide) C iv trough on rest-frame timescales as short as 1.20 days (˜29 hr), the shortest broad absorption line variability timescale yet reported. The EW varied by ˜10% on these short timescales, and by about a factor of two over the duration of the campaign. We evaluate several potential causes of the variability, concluding that the most likely cause is a rapid response to changes in the incident ionizing continuum. If the outflow is at a radius where the recombination rate is higher than the ionization rate, the timescale of variability places a lower limit on the density of the absorbing gas of ne ≳ 3.9 × 105 cm-3. The broad absorption line variability characteristics of this quasar are consistent with those observed in previous studies of quasars, indicating that such short-term variability may in fact be common and thus can be used to learn about outflow characteristics and contributions to quasar/host-galaxy feedback scenarios.

  1. Measurability of Kinetic Temperature from Metal Absorption-Line Spectra Formed in Chaotic Media

    NASA Astrophysics Data System (ADS)

    Levshakov, Sergei A.; Takahara, Fumio; Agafonova, Irina I.

    1999-06-01

    We present a new method for recovering the kinetic temperature of the intervening diffuse gas to an accuracy of 10%. The method is based on the comparison of unsaturated absorption-line profiles of two species with different atomic weights. The species are assumed to have the same temperature and bulk motion within the absorbing region. The computational technique involves the Fourier transform of the absorption profiles and the consequent entropy-regularized χ2-minimization (ERM) to estimate the model parameters. The procedure is tested using synthetic spectra of C+, Si+, and Fe+ ions. The comparison with the standard Voigt fitting analysis is performed, and it is shown that the Voigt deconvolution of the complex absorption-line profiles may result in estimated temperatures that are not physical. We also successfully analyze Keck telescope spectra of C II λ1334 and Si II λ1260 lines observed at the redshift z=3.572 toward the quasar Q1937-1009 by Tytler et al. Based in part on data obtained at the W. M. Keck Observatory, which is jointly operated by the University of California and the California Institute of Technology.

  2. Correlation of QSO absorption lines in universes dominated by cold dark matter

    NASA Technical Reports Server (NTRS)

    Salmon, J.; Hogan, C.

    1986-01-01

    Theoretical predictions for the redshift correlations between QSO absorption-line systems are investigated in the context of 'cold dark matter' cosmological models. Particles in 'particle-mesh' N-body simulations are interpreted as absorbing clouds at epochs corresponding to mean redshifts, z, of 0.0, 1.25, and 3.0. The velocity correlation function for absorbing clouds is found by passing lines-of-sight through the systems and computing velocity differences for those particles which lie close to the lines. It depends strongly on z and Omega but only weakly, if at all, on the number density, diameter or mass of the clouds. Two interpretations are possible: (1) the heavy element absorption systems are associated with galaxies which are an unbiased sample of the mass distribution in an Omega(0) = 0.2 universe or (2) the Lyman-alpha absorbers are an unbiased sample of the mass in an Omega(0) = 1 universe and the heavy-element absorption systems, like galaxies, are more strongly clustered than the mass.

  3. A new analysis of fine-structure constant measurements and modelling errors from quasar absorption lines

    NASA Astrophysics Data System (ADS)

    Wilczynska, Michael R.; Webb, John K.; King, Julian A.; Murphy, Michael T.; Bainbridge, Matthew B.; Flambaum, Victor V.

    2015-12-01

    We present an analysis of 23 absorption systems along the lines of sight towards 18 quasars in the redshift range of 0.4 ≤ zabs ≤ 2.3 observed on the Very Large Telescope (VLT) using the Ultraviolet and Visual Echelle Spectrograph (UVES). Considering both statistical and systematic error contributions we find a robust estimate of the weighted mean deviation of the fine-structure constant from its current, laboratory value of Δα/α = (0.22 ± 0.23) × 10-5, consistent with the dipole variation reported in Webb et al. and King et al. This paper also examines modelling methodologies and systematic effects. In particular, we focus on the consequences of fitting quasar absorption systems with too few absorbing components and of selectively fitting only the stronger components in an absorption complex. We show that using insufficient continuum regions around an absorption complex causes a significant increase in the scatter of a sample of Δα/α measurements, thus unnecessarily reducing the overall precision. We further show that fitting absorption systems with too few velocity components also results in a significant increase in the scatter of Δα/α measurements, and in addition causes Δα/α error estimates to be systematically underestimated. These results thus identify some of the potential pitfalls in analysis techniques and provide a guide for future analyses.

  4. VLBI survey of compact broad absorption line quasars with balnicity index BI = 0

    NASA Astrophysics Data System (ADS)

    Cegłowski, M.; Kunert-Bajraszewska, M.; Roskowiński, C.

    2015-06-01

    We present high-resolution observations, using both the European VLBI Network (EVN) at 1.7 GHz and the Very Long Baseline Array (VLBA) at 5 and 8.4 GHz, to image radio structures of 14 compact sources classified as broad absorption line (BAL) quasars based on the absorption index (AI). All sources but one were resolved, with the majority showing core-jet morphology typical for radio-loud quasars. We discuss in detail the most interesting cases. The high radio luminosities and small linear sizes of the observed objects indicate they are strong young active galactic nuclei. Nevertheless, the distribution of the radio-loudness parameter, log RI, of a larger sample of AI quasars shows that the objects observed by us constitute the most luminous, small subgroup of the AI population. Additionally, we report that for the radio-loudness parameter, the distribution of AI quasars and that for those selected using the traditional balnicity index differ significantly. Strong absorption is connected with lower log RI and thus probably larger viewing angles. Since the AI quasars have on average larger log RI, the orientation can mean that we see them less absorbed. However, we suggest that the orientation is not the only parameter that affects the detected absorption. That the strong absorption is associated with the weak radio emission is equally important and worth exploring.

  5. Constraining the variation of the fine-structure constant with observations of narrow quasar absorption lines

    SciTech Connect

    Songaila, A.; Cowie, L. L.

    2014-10-01

    The unequivocal demonstration of temporal or spatial variability in a fundamental constant of nature would be of enormous significance. Recent attempts to measure the variability of the fine-structure constant α over cosmological time, using high-resolution spectra of high-redshift quasars observed with 10 m class telescopes, have produced conflicting results. We use the many multiplet (MM) method with Mg II and Fe II lines on very high signal-to-noise, high-resolution (R = 72, 000) Keck HIRES spectra of eight narrow quasar absorption systems. We consider both systematic uncertainties in spectrograph wavelength calibration and also velocity offsets introduced by complex velocity structure in even apparently simple and weak narrow lines and analyze their effect on claimed variations in α. We find no significant change in α, Δα/α = (0.43 ± 0.34) × 10{sup –5}, in the redshift range z = 0.7-1.5, where this includes both statistical and systematic errors. We also show that the scatter in measurements of Δα/α arising from absorption line structure can be considerably larger than assigned statistical errors even for apparently simple and narrow absorption systems. We find a null result of Δα/α = (– 0.59 ± 0.55) × 10{sup –5} in a system at z = 1.7382 using lines of Cr II, Zn II, and Mn II, whereas using Cr II and Zn II lines in a system at z = 1.6614 we find a systematic velocity trend that, if interpreted as a shift in α, would correspond to Δα/α = (1.88 ± 0.47) × 10{sup –5}, where both results include both statistical and systematic errors. This latter result is almost certainly caused by varying ionic abundances in subcomponents of the line: using Mn II, Ni II, and Cr II in the analysis changes the result to Δα/α = (– 0.47 ± 0.53) × 10{sup –5}. Combining the Mg II and Fe II results with estimates based on Mn II, Ni II, and Cr II gives Δα/α = (– 0.01 ± 0.26) × 10{sup –5}. We conclude that spectroscopic measurements of

  6. Constraining the Variation of the Fine-structure Constant with Observations of Narrow Quasar Absorption Lines

    NASA Astrophysics Data System (ADS)

    Songaila, A.; Cowie, L. L.

    2014-10-01

    The unequivocal demonstration of temporal or spatial variability in a fundamental constant of nature would be of enormous significance. Recent attempts to measure the variability of the fine-structure constant α over cosmological time, using high-resolution spectra of high-redshift quasars observed with 10 m class telescopes, have produced conflicting results. We use the many multiplet (MM) method with Mg II and Fe II lines on very high signal-to-noise, high-resolution (R = 72, 000) Keck HIRES spectra of eight narrow quasar absorption systems. We consider both systematic uncertainties in spectrograph wavelength calibration and also velocity offsets introduced by complex velocity structure in even apparently simple and weak narrow lines and analyze their effect on claimed variations in α. We find no significant change in α, Δα/α = (0.43 ± 0.34) × 10-5, in the redshift range z = 0.7-1.5, where this includes both statistical and systematic errors. We also show that the scatter in measurements of Δα/α arising from absorption line structure can be considerably larger than assigned statistical errors even for apparently simple and narrow absorption systems. We find a null result of Δα/α = (- 0.59 ± 0.55) × 10-5 in a system at z = 1.7382 using lines of Cr II, Zn II, and Mn II, whereas using Cr II and Zn II lines in a system at z = 1.6614 we find a systematic velocity trend that, if interpreted as a shift in α, would correspond to Δα/α = (1.88 ± 0.47) × 10-5, where both results include both statistical and systematic errors. This latter result is almost certainly caused by varying ionic abundances in subcomponents of the line: using Mn II, Ni II, and Cr II in the analysis changes the result to Δα/α = (- 0.47 ± 0.53) × 10-5. Combining the Mg II and Fe II results with estimates based on Mn II, Ni II, and Cr II gives Δα/α = (- 0.01 ± 0.26) × 10-5. We conclude that spectroscopic measurements of quasar absorption lines are not yet capable of

  7. Multiple Absorption-line Spectroscopy of the Intergalactic Medium. I. Model

    NASA Astrophysics Data System (ADS)

    Yao, Yangsen; Shull, J. Michael; Danforth, Charles W.; Keeney, Brian A.; Stocke, John T.

    2011-04-01

    We present a physically based absorption-line model for the spectroscopic study of the intergalactic medium (IGM). This model adopts results from Cloudy simulations and theoretical calculations by Gnat & Sternberg to examine the resulting observational signatures of the absorbing gas with the following ionization scenarios: collisional ionization equilibrium (CIE), photoionization equilibrium, hybrid (photo- plus collisional ionization), and non-equilibrium cooling. As a demonstration, we apply this model to new observations made with the Cosmic Origins Spectrograph aboard the Hubble Space Telescope of the IGM absorbers at z ~ 0.1877 along the 1ES 1553+113 sight line. We identify Lyα, C III, O VI, and N V absorption lines with two distinct velocity components (blue at zb = 0.18757; red at zr = 0.18772) separated by Δ(cz)/(1 + z) ≈ 38 km s-1. Joint analyses of these lines indicate that none of the examined ionization scenarios can be applied with confidence to the blue velocity component, although photoionization seems to play a dominant role. For the red component, CIE can be ruled out, but pure photoionization and hybrid scenarios (with T < 1.3 × 105 K) are more acceptable. The constrained ranges of hydrogen density and metallicity of the absorbing gas are n H = (1.9-2.3) × 10-5 cm-3 and Z = (0.43-0.67) Z sun. These constraints indicate O VI and H I ionization fractions, f O VI = 0.10-0.15 and f H I = (3.2-5.1) × 10-5, with total hydrogen column density N H = (0.7-1.2) × 1018 cm-2. This demonstration shows that the joint analysis of multiple absorption lines can constrain the ionization state of an absorber, and results used to estimate the baryonic matter contained in the absorber.

  8. Fast calculation of the Voight profile absorption line of gas for the atmospheric transmission function determination

    NASA Astrophysics Data System (ADS)

    Chayanova, Eleonora A.; Ivanovsky, A. I.; Borisov, Yury A.; Glazkov, V. N.; Bankova, T. V.

    2004-01-01

    A fast method is offered for calculation of Voight spectral absorption line contour. A line profile is represented by a sum of terms of an absolutely converging series, containing undimensioned parameters a and b, connected with a property of the absorbing molecule, atmospheric temperature and pressure. The value b changes in a large limit from zero at the line center to 1000 and more at far wing of the line. The value a, describing a ratio of the Lorenz and Doppler effects, changes from a value ~5 near the surface of the Earth to 10-5 in the stratosphere. Twenty terms of series ensure the high accuracy of the approximation for values b ranging from 0 to 5. The deviation from accurate Voight contour formula is less than 4*10-4 or 0.04%. However, a large b value implies increase the number of terms, and the computing time increases accordingly. Numerical integration of Voight formula by Gauss-Hermite quadrature is simple, fast and accurate calculation for a value b> 5. In this case the deviation from accurate Voight formula is less than 2*10-5 or 0.002%. Using the proposed approximation of the Voight profile line, the atmospheric transmission function was computed for the path Sun- satellite represented as a net of tangent heights relative to the Earth"s surface up to 100 km with 1 km step. The computation method involves 29 spectral channels of the water absorption region (933-959 nm) and 14 channels of the molecular oxygen absorption region (758-771 nm). The computations were performed for certain profiles of H2O, O2, temperature and pressure. The computations results were compared with experimental data.

  9. Line-shape flattening resulting from hypersonic nozzle wedge flow in low-pressure chemical lasers

    SciTech Connect

    Livingston, P.M.; Bullock, D.L.

    1980-07-01

    The new hypersonic wedge nozzle (HYWN) supersonic wedge nozzle design produces a significant component of directed gas flow along the optical axis of a laser cavity comparable to thermal speeds. The gain-line-shape function is broadened and the refractive-index line shape is also spread as a function of wedge-flow half-angle. An analytical treatment as well as a numerical study is presented that evaluates the Doppler-directed-flow impact on the number of longitudinal modes and their frequencies as well as on gain and refractive-index saturation of those that lase in a Fabry--Perot cavity.

  10. Line-shape flattening resulting from hypersonic nozzle wedge flow in low-pressure chemical lasers.

    PubMed

    Livingston, P M; Bullock, D L

    1980-07-01

    The new hypersonic wedge nozzle (HYWN) supersonic wedge nozzle design produces a significant component of directed gas flow along the optical axis of a laser cavity comparable to thermal speeds. The gain-line-shape function is broadened and the refractive-index line shape is also spread as a function of wedge-flow half-angle. An analytical treatment as well as a numerical study is presented that evaluates the Doppler-directed-flow impact on the number of longitudinal modes and their frequencies as well as on gain and refractive-index saturation of those that lase in a Fabry-Perot cavity. PMID:19693204

  11. WAVELENGTH MEASUREMENTS OF K TRANSITIONS OF OXYGEN, NEON, AND MAGNESIUM WITH X-RAY ABSORPTION LINES

    SciTech Connect

    Liao Jinyuan; Zhang Shuangnan; Yao Yangsen

    2013-09-10

    Accurate atomic transition data are important in many astronomical research areas, especially for studies of line spectroscopy. Whereas transition data of He-like and H-like ions (i.e., ions in high-charge states) have been accurately calculated, the corresponding data of K transitions of neutral or low-ionized metal elements are still very uncertain. Spectroscopy of absorption lines produced in the interstellar medium (ISM) has been proven to be an effective way to measure the central wavelengths of these atomic transitions. In this work, we analyze 36 Chandra High Energy Transmission Grating observations to search for and measure the ISM absorption lines along sight lines to 11 low-mass X-ray binaries. We correct the Galactic rotation velocity to the rest frame for every observation and then use two different methods to merge all the corrected spectra to a co-added spectrum. However, the co-added spectra obtained by this method exhibit biases, toward to either observations with high counts or lines with high signal-to-noise ratios. We do a Bayesian analysis of several significantly detected lines to obtain the systematic uncertainty and the bias correction for other lines. Compared to previous studies, our results improve the wavelength accuracy by a factor of two to five and significantly reduce the systematic uncertainties and biases. Several weak transitions (e.g., 1s-2p of Mg IV and Mg V; 1s-3p of Mg III and Mg V) are also detected for the first time, albeit with low significance; future observations with improved accuracy are required to confirm these detections.

  12. Absorption Line Analysis to Interprete and Constrain Cosmological Simulations of Galaxy Evolution with Feedback

    NASA Astrophysics Data System (ADS)

    Churchill, Christopher

    2011-10-01

    The mammoth challenge for contemporary studies of galaxy formation and evolution are to establish detailed models in the cosmological context in which both the few parsec scale physics within galaxies are self-consistently unified and made consistent with the observed universe of galaxies. They key diagnostics reside with the gas physics, which dictate virtually every aspect of galaxy formation and evolution. The small scale physics includes stellar feedback, gas cooling, heating, and advection and the multiphase interstellar medium; the large scale physics includes intergalactic accretion, local merging, effects of supernovae driven winds, and the development of extended metal-enriched gas halos.Absorption line data have historically proven to be {and shall in the future} virtually the most powerful tool for understanding gas physics on all spatial scales over the majority of the age of the universe- the key to success. Simply stated, absorption lines are one of astronomy's most powerful observational windows on the universe {galaxy formation, galaxy winds, IGM metal enrichment, etc.}. The high quality and vast numbers of absorption line data {obtained with HST and FUSE} probe a broad range of gas structures {ISM, HVCs, halos, IGM} over the full cosmic span when galaxies are actively evolving.We propose to use LCDM hydrodynamic cosmological simulations employing a Eulerian Gasdynamics plus N-body Adaptive Refinement Tree {ART} code to develop and refine our understanding of stellar feedback physics and its role in governing the gas physics that regulates the evolution of galaxies and the IGM. We aim to substantially progress our understanding of all possible gas phases embedded within and extending far from galaxies. Our methodology is to apply a series of quantitative observational constraints from absorption line systems to better understand extended galaxy halos and the influence of the cosmological environment of the simulated galaxies: {1} galaxy halos

  13. Spectral line shapes and frequencies of the molecular oxygen B-band R-branch transitions

    NASA Astrophysics Data System (ADS)

    Domysławska, Jolanta; Wójtewicz, Szymon; Masłowski, Piotr; Cygan, Agata; Bielska, Katarzyna; Trawiński, Ryszard S.; Ciuryło, Roman; Lisak, Daniel

    2015-04-01

    We present the line-shape parameters for the first 11 lines of the oxygen B-band R-branch self-broadened transitions measured at low pressures by the Pound-Drever-Hall-locked frequency-stabilized cavity ring-down spectrometer (PDH-locked FS-CRDS) linked to the optical frequency comb. The collisional self-broadening, shifting and narrowing parameters were determined together with the quadratic speed-dependence as well as phase- and velocity-changing correlations parameters. The absolute frequencies of the transitions with combined standard uncertainties below 150 kHz are reported. Dependence of line parameters on choice of the line-shape model is discussed.

  14. Determination of the line shapes of atomic nitrogen resonance lines by magnetic scans

    NASA Technical Reports Server (NTRS)

    Lawrence, G. M.; Stone, E. J.; Kley, D.

    1976-01-01

    A technique is given for calibrating an atomic nitrogen resonance lamp for use in determining column densities of atoms in specific states. A discharge lamp emitting the NI multiplets at 1200 A and 1493 A is studied by obtaining absorption by atoms in a magnetic field (0-2.5 T). This magnetic scanning technique enables the determination of the absorbing atom column density, and an empirical curve of growth is obtained because the atomic f-value is known. Thus, the calibrated lamp can be used in the determination of atomic column densities.

  15. UNSHIFTED METASTABLE He I* MINI-BROAD ABSORPTION LINE SYSTEM IN THE NARROW-LINE TYPE 1 QUASAR SDSS J080248.18+551328.9

    SciTech Connect

    Ji, Tuo; Zhou, Hongyan; Jiang, Peng; Wang, Tinggui; Wang, Huiyuan; Liu, Wenjuan; Yang, Chenwei; Ge, Jian; Hamann, Fred; Komossa, S.; Yuan, Weimin; Zuther, Jens; Lu, Honglin; Zuo, Wenwen

    2015-02-10

    We report the identification of an unusual absorption-line system in the quasar SDSS J080248.18+551328.9 and present a detailed study of the system, incorporating follow-up optical and near-IR spectroscopy. A few tens of absorption lines are detected, including He I*, Fe II*, and Ni II*, which arise from metastable or excited levels, as well as resonant lines in Mg I, Mg II, Fe II, Mn II, and Ca II. All of the isolated absorption lines show the same profile of width Δv ∼ 1500 km s{sup –1} centered at a common redshift as that of the quasar emission lines, such as [O II], [S II], and hydrogen Paschen and Balmer series. With narrow Balmer lines, strong optical Fe II multiplets, and weak [O III] doublets, its emission-line spectrum is typical for that of a narrow-line Seyfert 1 galaxy (NLS1). We have derived reliable measurements of the gas-phase column densities of the absorbing ions/levels. Photoionization modeling indicates that the absorber has a density of n {sub H} ∼ (1.0-2.5) × 10{sup 5} cm{sup –3} and a column density of N {sub H} ∼ (1.0-3.2) × 10{sup 21} cm{sup –2} and is located at R ∼100-250 pc from the central supermassive black hole. The location of the absorber, the symmetric profile of the absorption lines, and the coincidence of the absorption- and emission-line centroid jointly suggest that the absorption gas originates from the host galaxy and is plausibly accelerated by stellar processes, such as stellar winds and/or supernova explosions. The implications for the detection of such a peculiar absorption-line system in an NLS1 are discussed in the context of coevolution between supermassive black hole growth and host galaxy buildup.

  16. SPECTRAL POLARIZATION OF THE REDSHIFTED 21 cm ABSORPTION LINE TOWARD 3C 286

    SciTech Connect

    Wolfe, Arthur M.; Jorgenson, Regina A.; Robishaw, Timothy; Heiles, Carl; Xavier Prochaska, J. E-mail: raj@ast.cam.ac.uk E-mail: heiles@astro.berkeley.edu

    2011-05-20

    A reanalysis of the Stokes-parameter spectra obtained of the z = 0.692 21 cm absorption line toward 3C 286 shows that our original claimed detection of Zeeman splitting by a line-of-sight magnetic field, B{sub los} = 87 {mu}G, is incorrect. Because of an insidious software error, what we reported as Stokes V is actually Stokes U: the revised Stokes V spectrum indicates a 3{sigma} upper limit of B{sub los}< 17 {mu}G. The correct analysis reveals an absorption feature in fractional polarization that is offset in velocity from the Stokes I spectrum by -1.9 km s{sup -1}. The polarization position-angle spectrum shows a dip that is also significantly offset from the Stokes I feature, but at a velocity that differs slightly from the absorption feature in fractional polarization. We model the absorption feature with three velocity components against the core-jet structure of 3C 286. Our {chi}{sup 2} minimization fitting results in components with differing (1) ratios of H I column density to spin temperature, (2) velocity centroids, and (3) velocity dispersions. The change in polarization position angle with frequency implies incomplete coverage of the background jet source by the absorber. It also implies a spatial variation of the polarization position angle across the jet source, which is observed at frequencies higher than the 839.4 MHz absorption frequency. The multi-component structure of the gas is best understood in terms of components with spatial scales of {approx}100 pc comprised of hundreds of low-temperature (T {<=} 200 K) clouds with linear dimensions of <<100 pc. We conclude that previous attempts to model the foreground gas with a single uniform cloud are incorrect.

  17. Concentration Dependence of Line Shapes in the ν_1 + ν_3 Band of Acetylene

    NASA Astrophysics Data System (ADS)

    Cich, Matthew; Forthomme, Damien; Hall, Gregory; McRaven, C.; Sears, Trevor

    2014-06-01

    Using an extended cavity diode laser locked to a frequency comb, the line shape of the P(11) line in the ν_1 + ν_3 combination band of acetylene has been studied as a function of varying concentration of the absorber in nitrogen. Mixture concentrations of 1, 5 and 10% at 296 K and pressures between a few Torr and one atmosphere were made and the measurements analyzed using two different speed-dependent broadening models. These experiments are designed to test the additivity of contributions to pressure broadening and shift in speed-dependent line shape modeling, i.e. whether the lineshape parameters follow partial pressure weighting in the binary mixtures. P(11) is relatively isolated with respect to underlying hot band transitions and neighboring transitions of the same band, but it was found that the accurate positions of underlying hot band transitions were crucial to the successful modeling of the observed line shapes, even though these lines are typically 100-1000 times weaker than P(11) itself and are many Doppler line widths removed from the line center. Positions of the hot band lines quoted in the HITRAN database, which are derived from the analysis of high resolution FTIR spectra, are of the order of 10's of MHz in error. In parallel work, we have measured the positions of many of these lines by saturation dip spectroscopy. Progress in the analysis of the data and the new saturation dip line center measurements will be reported. [1] C. P. McRaven, et al. Paper RI05, 68th International Symposium on Molecular Spectroscopy, 2013 Acknowledgments: Work at Brookhaven National Laboratory was carried out under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy and supported by its Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences.

  18. Ultraviolet Fe VII absorption and Fe II emission lines of central stars of planetary nebulae

    NASA Technical Reports Server (NTRS)

    Cheng, Kwang-Ping; Feibelman, Walter A.; Bruhweiler, Frederick C.

    1991-01-01

    The SWP camera of the IUE satellite was used in the high-dispersion mode to search for Fe VII absorption and Fe II high-excitation emission lines in five additional very hot central stars of planetary nebulae. Some of the Fe VII lines were detected at 1208, 1239, and 1332 A in all the objects of this program, LT 5, NGC 6058, NGC 7094, A43, and Lo 1 (= K1-26), as well as some of the Fe II emission lines at A 1360, 1776, 1869, 1881, 1884, and 1975 A. Two additional objects, NGC 2867 and He 2-131, were obtained from the IUE archive and were evaluated. The present study probably exhausts the list of candidates that are sufficiently bright and hot to be reached with the high-dispersion mode of the IUE.

  19. An absorption line in the ultraviolet spectrum of 40 Eridani B

    NASA Technical Reports Server (NTRS)

    Greenstein, J. L.

    1980-01-01

    Two excellent low-resolution spectra show an absorption line of equivalent width 3 A, near 1391 A, in the typical DA (hydrogen atmosphere) white dwarf 40 Eri B. The line is confirmed by a high-resolution spectrum and is the first seen in any DA star. Ultraviolet fluxes and the profile of Lyman-alpha confirm an effective temperature near 17,000 K. If the line is Si IV, it requires a temperature near 40,000 K. Unattractive possibilities are a hot circumstellar absorbing envelope dependent on accretion from companions, or formation at large optical depth in a transparent atmosphere with high Si/H. A suggestion that H2 should be considered leads to the possible interpretation as the (0, 5) transition of the Lyman band, formed at small optical depth. The band should be stronger in cooler DAs.

  20. Evidence for active galactic nucleus feedback in the broad absorption lines and reddening of MRK 231 {sup ,}

    SciTech Connect

    Leighly, Karen M.; Baron, Eddie; Lucy, Adrian B.; Terndrup, Donald M.; Dietrich, Matthias; Gallagher, Sarah C.

    2014-06-20

    We present the first J-band spectrum of Mrk 231, which reveals a large He I* λ10830 broad absorption line with a profile similar to that of the well-known Na I broad absorption line. Combining this spectrum with optical and UV spectra from the literature, we show that the unusual reddening noted by Veilleux et al. is explained by a reddening curve like those previously used to explain low values of total-to-selective extinction in Type Ia supernovae. The nuclear starburst may be the origin and location of the dust. Spatially resolved emission in the broad absorption line trough suggests nearly full coverage of the continuum emission region. The broad absorption lines reveal higher velocities in the He I* lines (produced in the quasar-photoionized H II region) compared with the Na I and Ca II lines (produced in the corresponding partially ionized zone). Cloudy simulations show that a density increase is required between the H II and partially ionized zones to produce ionic column densities consistent with the optical and IR absorption line measurements and limits, and that the absorber lies ∼100 pc from the central engine. These results suggest that the He I* lines are produced in an ordinary quasar BAL wind that impacts upon, compresses, and accelerates the nuclear starburst's dusty effluent (feedback in action), and the Ca II and Na I lines are produced in this dusty accelerated gas. This unusual circumstance explains the rarity of Na I absorption lines; without the compression along our line of sight, Mrk 231 would appear as an ordinary iron low-ionization, broad absorption line quasar.

  1. Unlocking the secrets of absorption line complexes in the intergalactic medium

    NASA Astrophysics Data System (ADS)

    O'Shea, Brian

    2013-10-01

    It is well-established that the fraction of baryons in the Universe that are observable drops from nearly 100% at z 3 to less than 50% by z 0. Simulations predict that most of the missing baryons are located in the IGM at moderate densities and at temperatures of 10^5-10^7 K - gas that is generally in the filaments of the cosmic web and in circumgalactic regions. This gas is typically detected in the low-z Lyman alpha forest by measuring UV absorption lines of highly ionized metals, such as CIV and OVI. However, significant uncertainties exist relating to the physical conditions of the gas associated with these lines {such as temperature, metallicity, and ionization state}, which severely limits our ability to understand the physical environment of these absorbers. We propose to clarify the relationship between the multi-species absorption line complexes seen in QSO spectra and the physical conditions of the corresponding absorbing gas. We will do this using synthetic observing tools and the largest, most detailed simulations of the IGM to date, which include a new sophisticated treatment of non-equilibrium gas chemistry. We will create catalogs that enable conversion between specific combinations of observed absorption lines and the equivalent physical gas distribition, will calculate the total baryon content that is traceable with each ion, and will devise tests to distinguish between the circumgalactic and truly intergalactic medium. This work will be critical to the interpretation of previous and ongoing HST studies of the IGM - particularly those using the Cosmic Origins Spectrograph - and directly addresses the HST Cycle 21 Ultraviolet Initiative.

  2. Atlas of Absorption Lines from 0 to 17900 Cm (sup)-1

    NASA Technical Reports Server (NTRS)

    Park, J. H.; Rothman, L. S.; Rinsland, C. P.; Pickett, H. M.; Richardson, D. J.; Namkung, J. S.

    1987-01-01

    Plots of logarithm (base 10) of absorption line strength versus wavenumber from 0 to 17900/cm(sup)-1 are shown for the 28 atmospheric gases (H2O, CO2, O3, N2O, CO, CH4, O2, NO, SO2, NO2, NH3, HNO3, OH, HF, HCl, HBr, HI, ClO, OCS, H2CO, HOCl, N2, HCN, CH3Cl, H2O2, C2H2, C2H6, PH3), which appear in the 1986 Air Force Geophysics Laboratory high-resolution transmission molecular absorption data base (HITRAN) compilation, and for O(P-3), O-18 isotopic ozone, and HO2 from the 1984 JPL compilation in the 0- to 200/cm(sup)-1 region, and infrared solar CO lines at 4500 K. Also shown are plots of logarithm (base 10) of approximate infrared absorption cross sections of 11 heavy molecules versus wavenumber. The cross-section data cover 700 to 1800/cm(sup)-1 and are included as a separate data file in the 1986 HITRAN database.

  3. Radiation Pressure-Driven Magnetic Disk Winds in Broad Absorption Line Quasi-Stellar Objects

    NASA Technical Reports Server (NTRS)

    DeKool, Martin; Begelman, Mitchell C.

    1995-01-01

    We explore a model in which QSO broad absorption lines (BALS) are formed in a radiation pressure-driven wind emerging from a magnetized accretion disk. The magnetic field threading the disk material is dragged by the flow and is compressed by the radiation pressure until it is dynamically important and strong enough to contribute to the confinement of the BAL clouds. We construct a simple self-similar model for such radiatively driven magnetized disk winds, in order to explore their properties. It is found that solutions exist for which the entire magnetized flow is confined to a thin wedge over the surface of the disk. For reasonable values of the mass-loss rate, a typical magnetic field strength such that the magnetic pressure is comparable to the inferred gas pressure in BAL clouds, and a moderate amount of internal soft X-ray absorption, we find that the opening angle of the flow is approximately 0.1 rad, in good agreement with the observed covering factor of the broad absorption line region.

  4. Atlas of absorption lines from 0 to 17900 cm (sup)-1

    SciTech Connect

    Park, J.H.; Rothman, L.S.; Rinsland, C.P.; Pickett, H.M.; Richardson, D.J.; Namkung, J.S.

    1987-09-01

    Plots of logarithm (base 10) of absorption line strength versus wavenumber from 0 to 17900/cm(sup)-1 are shown for the 28 atmospheric gases (H/sub 2/O, CO/sub 2/, O/sub 3/, N/sub 2/O, CO, CH/sub 4/, O/sub 2/, NO, SO/sub 2/, NO/sub 2/, NH/sub 3/, HNO/sub 3/, OH, HF, HCl, HBr, HI, ClO, OCS, H/sub 2/CO, HOCl, N/sub 2/, HCN, CH/sub 3/Cl, H/sub 2/O/sub 2/, C/sub 2/H/sub 2/, C/sub 2/H/sub 6/, PH/sub 3/), which appear in the 1986 Air Force Geophysics Laboratory high-resolution transmission molecular absorption data base (HITRAN) compilation, and for O(P-3), O-18 isotopic ozone, and HO2 from the 1984 JPL compilation in the 0- to 200/cm(sup)-1 region, and infrared solar CO lines at 4500 K. Also shown are plots of logarithm (base 10) of approximate infrared absorption cross sections of 11 heavy molecules versus wavenumber. The cross-section data cover 700 to 1800/cm(sup)-1 and are included as a separate data file in the 1986 HITRAN database.

  5. Effects of energy distribution of interface traps on recombination dc current-voltage line shape

    NASA Astrophysics Data System (ADS)

    Chen, Zuhui; Jie, Bin B.; Sah, Chih-Tang

    2006-12-01

    The effects of energy distributions of Si /SiO2 interface traps in the energy gap of oxidized silicon on the current versus voltage line shape of the electron-hole recombination current are analyzed using the steady-state Shockley-Read-Hall kinetics. Slater's [Insulators, Semiconductors and Metals; Quantum Theory of Molecules and Solids (McGraw-Hill, New York, 1967)] localized bulk perturbation theory applied by us to the interface anticipates U-shaped energy distributions of the density of neutral electron and hole interface traps from random variations of the Si:Si and Si:O bond angles and lengths. Conservation in dissipative transition energy anticipates the rate of electron capture into neutral electron trap to be faster for electron trap energy levels nearer the conduction band edge, and similarly, the rate of hole capture into neutral hole trap to be faster for hole trap energy levels nearer the valence band edge. Line shape broadening is analyzed for discrete and U-shaped energy distributions of interface trap energy levels. The broadened line shapes observed in past experiments, previously attributed to spatial variations of surface dopant impurity concentrations, could also arise from energy distributions of interface trap energy levels.

  6. Orbital signatures of Fano-Kondo line shapes in STM adatom spectroscopy

    NASA Astrophysics Data System (ADS)

    Frank, Sebastian; Jacob, David

    2015-12-01

    We investigate the orbital origin of the Fano-Kondo line shapes measured in STM spectroscopy of magnetic adatoms on metal substrates. To this end we calculate the low-bias tunnel spectra of a Co adatom on the (001) and (111) Cu surfaces with our density functional theory-based ab initio transport scheme augmented by local correlations. In order to associate different d orbitals with different Fano line shapes we only correlate individual 3 d orbitals instead of the full Co 3 d shell. We find that Kondo peaks arising in different d levels indeed give rise to different Fano features in the conductance spectra. Hence, the shape of measured Fano features allows us to draw some conclusions about the orbital responsible for the Kondo resonance, although the actual shape is also influenced by temperature, effective interaction, and charge fluctuations. Comparison with a simplified model shows that line shapes are mostly the result of interference between tunneling paths through the correlated d orbital and the s p -type orbitals on the Co atom. Very importantly, the amplitudes of the Fano features vary strongly among orbitals, with the 3 z2 orbital featuring by far the largest amplitude due to its strong direct coupling to the s -type conduction electrons.

  7. Spectral line shapes of P-branch transitions of oxygen B-band

    NASA Astrophysics Data System (ADS)

    Wójtewicz, Szymon; Cygan, Agata; Masłowski, Piotr; Domysławska, Jolanta; Wcisło, Piotr; Zaborowski, Mikołaj; Lisak, Daniel; Trawiński, Ryszard S.; Ciuryło, Roman

    2014-06-01

    The precise line-shape measurements of self- and foreign-broadened P-branch transitions of the oxygen B band near 689 nm are presented. Data were obtained using the Pound-Drever-Hall-locked frequency-stabilized cavity ring-down spectrometer assisted by the optical frequency comb.1,2 This technique enables us to achieve high spectral resolution (about 1 MHz) and high signal-to-noise ratio spectra (above 10000:1) of weak transitions.3,4 It is showed that the inclusion of the line-narrowing effects (Dicke narrowing or the speed dependence of collisional broadening) is necessary to properly model measured line shapes. The multispectrum fitting technique is used to minimize correlation between line-shape parameters. Relations between the line narrowing obtained from different line-shape models in the low pressure limit (below 5 kPa) were verified experimentally. Line positions with uncertainties of about 170 kHz, intensities and the collisional broadening coefficients with uncertainties of about 0.5% are reported and compared to data available in the literature.5 The research is part of the program of the National Laboratory FAMO in Toruń, Poland, and is supported by the Polish National Science Centre Projects no. DEC-2011/01/B/ST2/00491 and UMO-2012/05/N/ST2/02717. The research is also supported by the Foundation for Polish Science TEAM and HOMING PLUS Projects co-financed by the EU European Regional Development Fund. A. Cygan is partially supported by the Foundation for Polish Science START Project.

  8. Low-pressure line-shape study in molecular oxygen with absolute frequency reference

    NASA Astrophysics Data System (ADS)

    Domysławska, J.; Wójtewicz, S.; Cygan, A.; Bielska, K.; Lisak, D.; Masłowski, P.; Trawiński, R. S.; Ciuryło, R.

    2013-11-01

    We present a line-shape analysis of the rovibronic R1 Q2 transition of the oxygen B band resolved by the Pound-Drever-Hall-locked frequency-stabilized cavity ring-down spectroscopy technique in the low pressure range. The frequency axis of the spectra is linked by the ultra-narrow diode laser to the optical frequency comb in order to measure the absolute frequency at each point of the recorded spectra. Experimental spectra are fitted with various line-shape models: the Voigt profile, the Galatry profile, the Nelkin-Ghatak profile, the speed-dependent Voigt profile, and the speed-dependent Nelkin-Ghatak profile with quadratic and hypergeometric approximations for the speed dependence of collisional broadening and shifting. The influences of Dicke narrowing, speed-dependent effects, and correlation between phase- and velocity-changing collisions on the line shape are investigated. Values of line-shape parameters, including the absolute frequency of the transition 435685.24828(46) GHz, are reported.

  9. Dependence of line shapes in femtosecond broadband stimulated Raman spectroscopy on pump-probe time delay

    PubMed Central

    Yoon, Sangwoon; McCamant, David W.; Kukura, Philipp; Mathies, Richard A.; Zhang, Donghui; Lee, Soo-Y.

    2005-01-01

    The effect of the time delay between the picosecond Raman pump and the femtosecond Stokes probe pulse on the Raman gain line shape in femtosecond broadband stimulated Raman spectroscopy (FSRS) is presented. Experimental data are obtained for cyclohexane to investigate the dependence of the FSRS line shape on this time delay. Theoretical simulations of the line shapes as a function of the time delay using the coupled wave theory agree well with experimental data, recovering broad line shapes at positive time delays and narrower bands with small Raman loss side wings at negative time delays. The analysis yields the lower bounds of the vibrational dephasing times of 2.0 ps and 0.65 ps for the 802 and 1027 cm−1 modes for cyclohexane, respectively. The theoretical description and simulation using the coupled wave theory are also consistent with the observed Raman gain intensity profile over time delay, reaching the maximum at a slightly negative time delay (∼−21 ps), and show that the coupled wave theory is a good model for describing FSRS. PMID:15638596

  10. A comparison of neutral hydrogen 21 cm observations with UV and optical absorption-line measurements

    NASA Technical Reports Server (NTRS)

    Giovanelli, R.; York, D. G.; Shull, J. M.; Haynes, M. P.

    1978-01-01

    Several absorption components detected in visible or UV lines have been identified with emission features in new high-resolution, high signal-to-noise 21 cm observations. Stars for which direct overlap is obtained are HD 28497, lambda Ori, mu Col, HD 50896, rho Leo, HD 93521, and HD 219881. With the use of the inferred H I column densities from 21 cm profiles, rather than the integrated column densities obtained from L-alpha, more reliable densities can be derived from the existence of molecular hydrogen. Hence the cloud thicknesses are better determined; and 21 cm emission maps near these stars can be used to obtain dimensions on the plane of the sky. It is now feasible to derive detailed geometries for isolated clumps of gas which produce visual absorption features.

  11. Effect of line, soaking and cooking time on water absorption, texture and splitting of red kidney beans.

    PubMed

    Zamindar, Nafiseh; Baghekhandan, Mohamad Shahedi; Nasirpour, Ali; Sheikhzeinoddin, Mahmoud

    2013-02-01

    Dry beans are rich sources of dietary fiber and phytochemicals such as flavonoids and phenolics that exhibit good functional properties. In current study line, cooking and soaking time effects were investigated on water absorption, splitting and texture of different Iranian red kidney beans to determine the best lines and the best soaking time related to them for industrial use. D81083 line had the highest level of water absorption after 24 h soaking followed by Akhtar and KS31164 lines while Azna, Goli and Naz lines had the lowest level of water absorption (p < 0.05). Akhtar and Sayyad had the highest level of splitting while KS31164 had the lowest level of splitting (p < 0.05). Soaking of Akhtar line for 24 h caused the highest level of water absorption accompanied with low splitting level. 24 h soaking and longer cooking time is recommended for Sayyad, while 12 h soaking and longer cooking time is recommended for KS31164 line. 24 h soaking causes higher level of water absorption and lower level of splitting in Derakhshan line. The effects of line, cooking and soaking time on red bean texture were significant (p < 0.01). PMID:24425894

  12. Dipole-dipole resonance line shapes in a cold Rydberg gas

    NASA Astrophysics Data System (ADS)

    Richards, B. G.; Jones, R. R.

    2016-04-01

    We have explored the dipole-dipole mediated, resonant energy transfer reaction, 32 p3 /2+32 p3 /2→32 s +33 s , in an ensemble of cold 85Rb Rydberg atoms. Stark tuning is employed to measure the population transfer probability as a function of the total electronic energy difference between the initial and final atom-pair states over a range of Rydberg densities, 2 ×108≤ρ ≤3 ×109 cm-3. The observed line shapes provide information on the role of beyond nearest-neighbor interactions, the range of Rydberg atom separations, and the electric field inhomogeneity in the sample. The widths of the resonance line shapes increase approximately linearly with the Rydberg density and are only a factor of 2 larger than expected for two-body, nearest-neighbor interactions alone. These results are in agreement with the prediction [B. Sun and F. Robicheaux, Phys. Rev. A 78, 040701(R) (2008), 10.1103/PhysRevA.78.040701] that beyond nearest-neighbor exchange interactions should not influence the population transfer process to the degree once thought. At low densities, Gaussian rather than Lorentzian line shapes are observed due to electric field inhomogeneities, allowing us to set an upper limit for the field variation across the Rydberg sample. At higher densities, non-Lorentzian, cusplike line shapes characterized by sharp central peaks and broad wings reflect the random distribution of interatomic distances within the magneto-optical trap (MOT). These line shapes are well reproduced by an analytic expression derived from a nearest-neighbor interaction model and may serve as a useful fingerprint for characterizing the position correlation function for atoms within the MOT.

  13. Low redshift Lyman alpha absorption lines and the dark matter halos of disk galaxies

    NASA Technical Reports Server (NTRS)

    Maloney, Philip

    1993-01-01

    Recent observations using the Hubble Space Telescope of the z = 0.156 QSO 3C 273 have discovered a surprisingly large number of Ly-alpha absorption lines. In particular, Morris et al. found 9 certain and 7 possible Ly-alpha lines with equivalent widths above 25 mA. This is much larger (by a factor of 5-10) than the number expected from extrapolation of the high-redshift behavior of the Ly-alpha forest. Within the context of pressure-confined models for the Ly-alpha clouds, this behavior can be understood if the ionizing background declines sharply between z is approximately 2 and z is approximately 0. However, this requires that the ionizing photon flux drop as rapidly as the QSO volume emissivity; moreover, the absorbers must have a space density n(sub O) is approximately 2.6(N/10)h/((D/100 kpc)(sup 2)) Mpc(sup -3) where D is the present-day diameter of the absorbers. It is somewhat surprising that such necessarily fragile objects could have survived in such numbers to the present day. It is shown that it is plausible that the atomic hydrogen extents of spiral and irregular galaxies are large enough to produce the observed number of Ly-alpha absorption lines toward 3C 273, and that the neutral column densities and doppler b-values expected under these conditions fall in the range found by Morris et al. (1991).

  14. Heterodyne detection of the 752.033-GHz H2O rotational absorption line

    NASA Technical Reports Server (NTRS)

    Dionne, G. F.; Fitzgerald, J. F.; Chang, T. S.; Litvak, M. M.; Fetterman, H. R.

    1980-01-01

    A tunable high resolution two stage heterodyne radiometer was developed for the purpose of investigating the intensity and lineshape of the 752.033 GHz rotational transition of water vapor. Single-sideband system noise temperatures of approximately 45,000 K were obtained using a sensitive GaAs Schottky diode as the first stage mixer. First local oscillator power was supplied by a CO2 laser pumped formic acid laser (761.61 GHz), generating an X-band IF signal with theoretical line center at 9.5744 GHz. Second local oscillator power was provided by means of a 3 GHz waveguide cavity filter with only 9 dB insertion loss. In absorption measurements of the H2O taken from a laboratory simulation of a high altitude rocket plume, the center frequency of the 752 GHz line was determined to within 1 MHz of the reported value. A rotational temperature 75 K, a linewidth 5 MHz and a Doppler shift 3 MHz were measured with the line-of-sight intersecting the simulated-plume axis at a distance downstream of 30 nozzle diameters. These absorption data were obtained against continuum background radiation sources at temperatures of 1175 and 300 K.

  15. Symmetry-Breaking in Cationic Polymethine Dyes: Part 2. Shape of Electronic Absorption Bands Explained by the Thermal Fluctuations of the Solvent Reaction Field.

    PubMed

    Masunov, Artëm E; Anderson, Dane; Freidzon, Alexandra Ya; Bagaturyants, Alexander A

    2015-07-01

    The electronic absorption spectra of the symmetric cyanines exhibit dramatic dependence on the conjugated chain length: whereas short-chain homologues are characterized by the narrow and sharp absorption bands of high intensity, the long-chain homologues demonstrate very broad, structureless bands of low intensity. Spectra of the intermediate homologues combine both features. These broad bands are often explained using spontaneous symmetry-breaking and charge localization at one of the termini, and the combination of broad and sharp features was interpreted as coexistence of symmetric and asymmetric species in solution. These explanations were not supported by the first principle simulations until now. Here, we employ a combination of time-dependent density functional theory, a polarizable continuum model, and Franck-Condon (FC) approximation to predict the absorption line shapes for the series of 2-azaazulene and 1-methylpyridine-4-substituted polymethine dyes. To simulate inhomogeneous broadening by the solvent, the molecular structures are optimized in the presence of a finite electric field of various strengths. The calculated FC line shapes, averaged with the Boltzmann weights of different field strengths, reproduce the experimentally observed spectra closely. Although the polarizable continuum model accounts for the equilibrium solvent reaction field at absolute zero, the finite field accounts for the thermal fluctuations in the solvent, which break the symmetry of the solute molecule. This model of inhomogeneous broadening opens the possibility for computational studies of thermochromism. The choice of the global hybrid exchange-correlation functional SOGGA11-X, including 40% of the exact exchange, plays the critical role in the success of our model. PMID:26087319

  16. Improved Frequency Fluctuation Model for Spectral Line Shape Calculations in Fusion Plasmas

    NASA Astrophysics Data System (ADS)

    Ferri, S.; Calisti, A.; Mossé, C.; Talin, B.; Lisitsa, V.

    2010-10-01

    A very fast method to calculate spectral line shapes emitted by plasmas accounting for charge particle dynamics and effects of an external magnetic field is proposed. This method relies on a new formulation of the Frequency Fluctuation Model (FFM), which yields to an expression of the dynamic line profile as a functional of the static distribution function of frequencies. This highly efficient formalism, not limited to hydrogen-like systems, allows to calculate pure Stark and Stark-Zeeman line shapes for a wide range of density, temperature and magnetic field values, which is of importance in plasma physics and astrophysics. Various applications of this method are presented for conditions related to fusion plasmas.

  17. Instabilities in line-driven stellar winds. III - Wave propagation in the case of pure line absorption

    NASA Technical Reports Server (NTRS)

    Owocki, S. P.; Rybicki, G. B.

    1986-01-01

    The spatial and temporal evolution of small-amplitude velocity perturbations is examined in the idealized case of a stellar wind that is driven by pure line absorption of the star's continuum radiation. It is established that the instability in the supersonic region is of the advective type relative to the star, but of the absolute type relative to the wind itself. It is also shown that the inward propagation of information in such a wind is limited to the sound speed, in contrast to the theory of Abbott, which predicts inward propagation faster than sound. This apparent contradiction is resolved through an extensive discussion of the analytically soluble case of zero sound speed.

  18. IMPROVED AND QUALITY-ASSESSED EMISSION AND ABSORPTION LINE MEASUREMENTS IN SLOAN DIGITAL SKY SURVEY GALAXIES

    SciTech Connect

    Oh, Kyuseok; Yi, Sukyoung K.; Sarzi, Marc; Schawinski, Kevin

    2011-08-01

    We present a new database of absorption and emission-line measurements based on the entire spectral atlas from the Sloan Digital Sky Survey (SDSS) 7th data release of galaxies within a redshift of 0.2. Our work makes use of the publicly available penalized pixel-fitting (pPXF) and gas and absorption line fitting (gandalf) IDL codes, aiming to improve the existing measurements for stellar kinematics, the strength of various absorption-line features, and the flux and width of the emissions from different species of ionized gas. Our fit to the stellar continuum uses both standard stellar population models and empirical templates obtained by combining a large number of stellar spectra in order to fit a subsample of high-quality SDSS spectra for quiescent galaxies. Furthermore, our fit to the nebular spectrum includes an exhaustive list of both recombination and forbidden lines. Foreground Galactic extinction is implicitly treated in our models, whereas reddening in the SDSS galaxies is included in the form of a simple dust screen component affecting the entire spectrum that is accompanied by a second reddening component affecting only the ionized gas emission. In order to check for systematic departures from the rather standard set of assumptions that enters our models, we provide a quality assessment for our fit to the SDSS spectra in our sample, for both the stellar continuum and the nebular emissions and across different wavelength regions. This quality assessment also allows the identification of objects with either problematic data or peculiar features. We hope to foster the discovery potential of our database; therefore, our spectral fit is available to the community. For example, based on the quality assessment around the H{alpha} and [N II] {lambda}6584 lines, approximately 1% of the SDSS spectra classified as 'galaxies' by the SDSS pipeline do in fact require additional broad lines to be matched, even though they do not show a strong continuum from an active

  19. Improved and Quality-assessed Emission and Absorption Line Measurements in Sloan Digital Sky Survey Galaxies

    NASA Astrophysics Data System (ADS)

    Oh, Kyuseok; Sarzi, Marc; Schawinski, Kevin; Yi, Sukyoung K.

    2011-08-01

    We present a new database of absorption and emission-line measurements based on the entire spectral atlas from the Sloan Digital Sky Survey (SDSS) 7th data release of galaxies within a redshift of 0.2. Our work makes use of the publicly available penalized pixel-fitting (pPXF) and gas and absorption line fitting (gandalf) IDL codes, aiming to improve the existing measurements for stellar kinematics, the strength of various absorption-line features, and the flux and width of the emissions from different species of ionized gas. Our fit to the stellar continuum uses both standard stellar population models and empirical templates obtained by combining a large number of stellar spectra in order to fit a subsample of high-quality SDSS spectra for quiescent galaxies. Furthermore, our fit to the nebular spectrum includes an exhaustive list of both recombination and forbidden lines. Foreground Galactic extinction is implicitly treated in our models, whereas reddening in the SDSS galaxies is included in the form of a simple dust screen component affecting the entire spectrum that is accompanied by a second reddening component affecting only the ionized gas emission. In order to check for systematic departures from the rather standard set of assumptions that enters our models, we provide a quality assessment for our fit to the SDSS spectra in our sample, for both the stellar continuum and the nebular emissions and across different wavelength regions. This quality assessment also allows the identification of objects with either problematic data or peculiar features. We hope to foster the discovery potential of our database; therefore, our spectral fit is available to the community. For example, based on the quality assessment around the Hα and [N II] λ6584 lines, approximately 1% of the SDSS spectra classified as "galaxies" by the SDSS pipeline do in fact require additional broad lines to be matched, even though they do not show a strong continuum from an active nucleus, as

  20. Sensitivity analysis of oxygen absorption lines in the 1.26-1.27 micron spectral band

    NASA Astrophysics Data System (ADS)

    Edwards, W. C.; Prasad, N.; Browell, E. V.

    2009-12-01

    In the Decadal Survey prepared by the National Research Council (Reference: Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond), the ASCENDS mission (Active Sensing of CO2 Emissions over Nights, Days and Seasons), requires simultaneous laser remote sensing of CO2 and O2 in order to convert CO2 atmospheric concentrations to mixing ratios. As the mission is envisioned, the CO2 mixing ratio needs to be measured to a precision of 0.5 percent of background or better (slightly less than 2 ppm) at 100-km horizontal length scale overland and at 200-km scale over open oceans. While the O2 measurement could be made at 0.765 µm (the oxygen A band), the absorption cross section is substantially higher and the scattering is lower in the 1.26-1.27 µm wavelength band, and as such it is anticipated that better accuracies could be accomplished. Hence, NASA Langley Research Center is developing oxygen lidar technology in the 1.26-1.27 micron band for surface pressure measurements. One or more wavelengths for differential absorption lidar operation have to be carefully chosen to eliminate ambient influences on them. The model optical depth calculation is very sensitive to knowledge of the transmitted wavelengths and to the choice of Voigt input parameters. Uncertainties in atmospheric profiles of temperature, pressure and relative humidity can cause ~0.5 % errors in model optical depths. In order to select candidate wavelengths in the 1.26 micron spectral band, wavelength uncertainties due to temperature and pressure have to be determined. Uncertainties at line center and offset wavelengths have to be known precisely to reduce uncertainties in oxygen concentration measurements from airborne and space based platforms. In this paper, based on HITRAN database and absorption line measurements, we evaluate systematic relative errors and their sources of pressure shift and atmospheric temperature influences for selected O2 lines suitable for

  1. Empirical calibrations of optical absorption-line indices based on the stellar library MILES

    NASA Astrophysics Data System (ADS)

    Johansson, Jonas; Thomas, Daniel; Maraston, Claudia

    2010-07-01

    Stellar population models of absorption-line indices are an important tool for the analysis of stellar population spectra. They are most accurately modelled through empirical calibrations of absorption-line indices with the stellar parameters such as effective temperature, metallicity and surface gravity, which are the so-called fitting functions. Here we present new empirical fitting functions for the 25 optical Lick absorption-line indices based on the new stellar library Medium resolution INT Library of Empirical Spectra (MILES). The major improvements with respect to the Lick/IDS library are the better sampling of stellar parameter space, a generally higher signal-to-noise ratio and a careful flux calibration. In fact, we find that errors on individual index measurements in MILES are considerably smaller than in Lick/IDS. Instead, we find the rms of the residuals between the final fitting functions and the data to be dominated by errors in the stellar parameters. We provide fitting functions for both Lick/IDS and MILES spectral resolutions and compare our results with other fitting functions in the literature. A FORTRAN 90 code is available online in order to simplify the implementation in stellar population models. We further calculate the offsets in index measurements between the Lick/IDS system to a flux-calibrated system. For this purpose, we use the three libraries MILES, ELODIE and STELIB. We find that offsets are negligible in some cases, most notably for the widely used indices Hβ, Mgb, Fe5270 and Fe5335. In a number of cases, however, the difference between the flux-calibrated library and Lick/IDS is significant with the offsets depending on index strengths. Interestingly, there is no general agreement between the three libraries for a large number of indices, which hampers the derivation of a universal offset between the Lick/IDS and flux-calibrated systems.

  2. Synthetic Spectra of H Balmer and HE I Absorption Lines. I. Stellar Library

    NASA Astrophysics Data System (ADS)

    González Delgado, Rosa M.; Leitherer, Claus

    1999-12-01

    We present a grid of synthetic profiles of stellar H Balmer and He I lines at optical wavelengths with a sampling of 0.3 Å. The grid spans a range of effective temperature 50,000 K>=Teff>=4000 K, and gravity 0.0<=logg<=5.0 at solar metallicity. For Teff>=25,000 K, non-LTE stellar atmosphere models are computed using the code TLUSTY (Hubeny). For cooler stars, Kurucz LTE models are used to compute the synthetic spectra. The grid includes the profiles of the high-order hydrogen Balmer series and He I lines for effective temperatures and gravities that have not been previously synthesized. The behavior of H8 to H13 and He I λ3819 with effective temperature and gravity is very similar to that of the lower terms of the series (e.g., Hβ) and the other He I lines at longer wavelengths; therefore, they are suited for the determination of the atmospheric parameters of stars. These lines are potentially important to make predictions for these stellar absorption features in galaxies with active star formation. Evolutionary synthesis models of these lines for starburst and poststarburst galaxies are presented in a companion paper. The full set of the synthetic stellar spectra is available for retrieval at our website or on request from the authors.

  3. 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.

  4. Measurements of self-broadening of infrared absorption lines of ozone

    NASA Technical Reports Server (NTRS)

    Smith, M. A. H.; Rinsland, C. P.; Devi, V. M.

    1991-01-01

    Lorentz self-broadening coefficients have been determined for 355 spectral lines belonging to five different infrared vibration-rotation bands of O3 in the spectral region from 4.8 to 17 microns. Six ozone absorption spectra, recorded at room temperature using a Fourier transform spectrometer, were analyzed. The half-width values were obtained through a nonlinear least-squares spectral fitting procedure. The results are compared with previous measurements, and the vibration of the half-widths with vibrational and rotational quantum numbers is examined.

  5. Probing the Inner Structure of Polar Broad Absorption-Line Quasars

    NASA Astrophysics Data System (ADS)

    Ghosh, Kajal

    2008-10-01

    We have discovered a sample of polar broad absorption-line quasars (BALQSOs). We know their inclination angles with reasonable certainty. Thus, these are the ideal objects to probe their inner structure through the X-ray studies. However, to date, we do not have a reasonably good signal-to-noise ratio X-ray spectrum of any of these objects. Here, we propose deep XMM-Newton observations of four polar BALQSOs to study the physical processes responsible for the X-ray emission, distribution of BAL clouds, wind driven mechanism, jet entrainment, etc. Finally, all these results will be used to constrain our time-dependent hydrodynamical simulations.

  6. Shape dependence of transmission, reflection, and absorption eigenvalue densities in disordered waveguides with dissipation

    NASA Astrophysics Data System (ADS)

    Yamilov, A.; Petrenko, S.; Sarma, R.; Cao, H.

    2016-03-01

    The universal bimodal distribution of transmission eigenvalues in lossless diffusive systems underpins such celebrated phenomena as universal conductance fluctuations, quantum shot noise in condensed matter physics, and enhanced transmission in optics and acoustics. Here, we show that in the presence of absorption, the density of the transmission eigenvalues depends on the confinement geometry of the scattering media. Furthermore, in an asymmetric waveguide, the densities of the reflection and absorption eigenvalues also depend on the side from which the waves are incident. With increasing absorption, the density of absorption eigenvalues transforms from a single-peak to a double-peak function. Our findings open an additional avenue for coherent control of wave transmission, reflection, and absorption in random media.

  7. Calibration and instrumental line shape characterization of a set of portable FTIR spectrometers for detecting greenhouse gas emissions

    NASA Astrophysics Data System (ADS)

    Frey, M.; Hase, F.; Blumenstock, T.; Groß, J.; Kiel, M.; Mengistu Tsidu, G.; Schäfer, K.; Sha, M. K.; Orphal, J.

    2015-07-01

    A comprehensive calibration procedure for mobile, low-resolution, solar-absorption FTIR spectrometers, used for greenhouse gases observations, is developed. These instruments commend themselves for campaign use and deployment at remote sites. The instrumental line shape (ILS) of each spectrometer has been thoroughly characterized by analyzing the shape of H2O signatures in open path spectra. A setup for the external source is suggested and the invariance of derived ILS parameters with regard to chosen path length is demonstrated. The instrumental line shape characteristics of all spectrometers were found to be close to nominal. Side-by-side solar observations before and after a campaign, which involved shipping of all spectrometers to a selected target site and back, are applied for verifying the temporal invariability of instrumental characteristics and for deriving intercalibration factors for XCO2 and XCH4, which take into account residual differences of instrumental characteristics. An excellent level of agreement and stability was found between the different spectrometers: the uncorrected biases in XCO2 and XCH4 are smaller than 0.01 and 0.15 %, respectively, and the drifts are smaller than 0.005 and 0.035 %. As an additional sensitive demonstration of the instrumental performance we show the excellent agreement of ground pressure values obtained from the total column measurements of O2 and barometric records. We find a calibration factor of 0.9700 for the spectroscopic measurements in comparison to the barometric records and a very small scatter between the individual spectrometers (0.02 %). As a final calibration step, using a co-located TCCON (Total Carbon Column Observation Network) spectrometer as a reference, a common scaling factor has been derived for the XCO2 and XCH4 products, which ensures that the records are traceable to the WMO in situ scale.

  8. Temperature dependence of 13CH4 line shapes broadened by N2

    NASA Astrophysics Data System (ADS)

    Sung, K.; Mantz, A. M.; Brown, L. R.; Smith, M. H.; Benner, D. C.; Devi, V.; Crawford, T. J.

    2009-12-01

    In order to support remote sensing of Titan’s atmosphere, the temperature dependences for the 13CH4 nitrogen broadening and frequency shift coefficients were measured for several transitions from 1200 to 1400 cm-1 (8.33 to 7.14 μm) using a Fourier transform spectrometer (Bruker IFS-125HR) newly configured with a temperature stabilized cryogenic absorption cell at the Jet Propulsion Laboratory. The cryogenic cell is mounted on the cold finger of a closed cycle helium refrigerator, and the temperatures are monitored with Si diode sensors. The wedged ZnSe cell windows are vacuum sealed with crushed indium gaskets. The cell has an optical path of 24 cm and is suspended from the top cover of the evacuated sample compartment. It has demonstrated a temperature stability of better than ±0.01 K at all temperatures between 300 K and 90 K. To test the system performance, we first recorded 10 spectra of the ν4 band of 13CH4 broadened by nitrogen at 0.0056 cm-1 instrumental resolution (Resolving power = 232000) using a HgCdTe detector. The pressures of 13CH4+N2 mixtures ranged from 140 to 796 torr with the volume mixing ratios of 13CH4 varying between 0.001 and 0.012 at 296, 255, 225 and 180 K. Line shape parameters in the spectral region from 1200 to 1400 cm-1 were retrieved using the nonlinear least squares multispectrum technique1, fitting selected wavenumber intervals of all spectra simultaneously to determine temperature dependence. Preliminary results from the temperature dependence measurements at planetary and astrophysical temperatures are reported along with detailed discussion of the instrumental setup. This new spectroscopic capability at the Jet Propulsion Laboratory will enable future research in studies of planetary science and astrophysics2. 1 Benner DC, Rinsland CP, Devi VM, Smith MAH, Atkins D. A multispectrum nonlinear least squares fitting technique. JQSRT 53, 705 - 721 (1995). 2 The research at the Jet Propulsion Laboratory (JPL), California Institute

  9. QSOs and Absorption-Line Systems surrounding the Hubble Deep Field

    SciTech Connect

    Vanden Berk, Daniel E.; Stoughton, Chris; Crotts, Arlin P. S.; Tytler, David; Kirkman, David

    2000-06-01

    We have imaged a 45' x 45' area centered on the Hubble Deep Field (HDF) in UBVRI passbands, down to the limiting magnitudes of approximately 21.5, 22.5, 22.2, 22.2, and 21.2, respectively. The principal goals of the survey are to identify quasi-stellar objects (QSOs) and to map structure traced by luminous galaxies and QSO absorption line systems in a wide volume containing the HDF. The area surveyed is 400 times as large as that of the HDF, and 40 times as large as that of the HDF Flanking Fields. We have selected QSO candidates from color space and identified four QSOs and two narrow emission line galaxies not yet discovered, bringing the total number of known QSOs in the area to 19. The bright z=1.305 QSO only 12' away from the HDF raises the northern HDF to nearly the same status as the southern Hubble Deep Field, which was selected to be proximate to a bright QSO. About half of the QSO candidates remain for spectroscopic verification. Absorption-line spectroscopy has been obtained for three bright QSOs in the field, using the 10 m Keck, 3.5 m ARC, and 2.4 m MDM telescopes. Five heavy-element absorption line systems have been identified, four of which overlap the well-explored redshift range covered by deep galaxy redshift surveys toward the HDF. The two absorbers at z=0.5565 and z=0.5621 occur at the same redshift as the secondmost populated redshift peak in the galaxy distribution, but each is more than 7 h-1 Mpc (comoving, {omega}{sub m} =1, {omega}{sub {lambda}} =0) away from the HDF line of sight in the transverse dimension. This supports more indirect evidence that the galaxy redshift peaks are contained within large sheetlike structures that traverse the HDF and may be precursors to large-scale ''pancake'' structures seen in the present-day galaxy distribution. (c) 2000 The American Astronomical Society.

  10. MULTIPLE ABSORPTION-LINE SPECTROSCOPY OF THE INTERGALACTIC MEDIUM. I. MODEL

    SciTech Connect

    Yao Yangsen; Michael Shull, J.; Danforth, Charles W.; Keeney, Brian A.; Stocke, John T.

    2011-04-01

    We present a physically based absorption-line model for the spectroscopic study of the intergalactic medium (IGM). This model adopts results from Cloudy simulations and theoretical calculations by Gnat and Sternberg to examine the resulting observational signatures of the absorbing gas with the following ionization scenarios: collisional ionization equilibrium (CIE), photoionization equilibrium, hybrid (photo- plus collisional ionization), and non-equilibrium cooling. As a demonstration, we apply this model to new observations made with the Cosmic Origins Spectrograph aboard the Hubble Space Telescope of the IGM absorbers at z {approx} 0.1877 along the 1ES 1553+113 sight line. We identify Ly{alpha}, C III, O VI, and N V absorption lines with two distinct velocity components (blue at z{sub b} = 0.18757; red at z{sub r} = 0.18772) separated by {Delta}(cz)/(1 + z) {approx} 38 km s{sup -1}. Joint analyses of these lines indicate that none of the examined ionization scenarios can be applied with confidence to the blue velocity component, although photoionization seems to play a dominant role. For the red component, CIE can be ruled out, but pure photoionization and hybrid scenarios (with T < 1.3 x 10{sup 5} K) are more acceptable. The constrained ranges of hydrogen density and metallicity of the absorbing gas are n{sub H} = (1.9-2.3) x 10{sup -5} cm{sup -3} and Z = (0.43-0.67) Z{sub sun}. These constraints indicate O VI and H I ionization fractions, f{sub OVI} = 0.10-0.15 and f{sub HI} = (3.2-5.1) x 10{sup -5}, with total hydrogen column density N{sub H} = (0.7-1.2) x 10{sup 18} cm{sup -2}. This demonstration shows that the joint analysis of multiple absorption lines can constrain the ionization state of an absorber, and results used to estimate the baryonic matter contained in the absorber.

  11. Self- and air-broadened line shapes in the 2ν3 P and R branches of 12CH4

    NASA Astrophysics Data System (ADS)

    Devi, V. Malathy; Benner, D. Chris; Sung, Keeyoon; Crawford, Timothy J.; Yu, Shanshan; Brown, Linda R.; Smith, Mary Ann H.; Mantz, Arlan W.; Boudon, Vincent; Ismail, Syed

    2015-09-01

    In this paper we report line shape parameters of 12CH4 for several hundred 2ν3 transitions in the spectral regions 5891-5996 cm-1 (P branch) and 6015-6115 cm-1 (R branch). Air- and self-broadening coefficients were measured as a function of temperature; line mixing via off-diagonal relaxation matrix element coefficients was also obtained for 47 transition pairs. In total, nearly 1517 positions and intensities were retrieved, but many transitions were too weak for the line shape study. For this analysis, we used 25 high-resolution (0.0056 and 0.0067 cm-1) and high signal-to-noise (S/N) spectra of high-purity 12CH4 and the same high-purity 12CH4 broadened by dry air recorded at different sample temperatures between 130 K and 295 K with the Bruker IFS 125HR Fourier transform spectrometer at JPL. Three different absorption cells were used (1) a White cell set to a path length of 13.09 m for room temperature data, (2) a single-pass 0.2038 m long coolable cell (for self-broadening) and (3) a multipass cell with 20.941 m total path coolable Herriott cell (for air-broadening). In total there were 13 spectra with pure 12CH4 (0.27-599 Torr) and 12 air-broadened spectra with total sample pressures of 80-805 Torr and volume mixing ratios (VMR) of methane between 0.18 and 1.0. An interactive multispectrum nonlinear least-squares technique was employed to fit the individual P10-P1 and R0-R10 manifolds in all the spectra simultaneously. Results obtained from the present analysis are compared to other recent measurements.

  12. Water-vapor absorption line measurements in the 940-nm band by using a Raman-shifted dye laser

    NASA Technical Reports Server (NTRS)

    Chu, Zhiping; Wilkerson, Thomas D.; Singh, Upendra N.

    1993-01-01

    We report water-vapor absorption line measurements that are made by using the first Stokes radiation (930-982 nm) with HWHM 0.015/cm generated by a narrow-linewidth, tunable dye laser. Forty-five absorption line strengths are measured with an uncertainty of 6 percent and among them are fourteen strong lines that are compared with previous measurements for the assessment of spectral purity of the light source. Thirty air-broadened linewidths are measured with 8 percent uncertainty at ambient atmospheric pressure with an average of 0.101/cm. The lines are selected for the purpose of temperature-sensitive or temperature-insensitive lidar measurements. Results for these line strengths and linewidths are corrected for broadband radiation and finite laser linewidth broadening effects and compared with the high-resolution transmission molecular absorption.

  13. Line parameters including temperature dependences of self- and air-broadened line shapes of 12C16O2: 1.6-μm region

    NASA Astrophysics Data System (ADS)

    Devi, V. Malathy; Benner, D. Chris; Sung, Keeyoon; Brown, Linda R.; Crawford, Timothy J.; Miller, Charles E.; Drouin, Brian J.; Payne, Vivienne H.; Yu, Shanshan; Smith, Mary Ann H.; Mantz, Arlan W.; Gamache, Robert R.

    2016-07-01

    Pressure-broadened line shapes in the 30013←00001 (ν1+4 ν20 +ν3) band of 12C16O2 at 6228 cm-1 are reanalyzed using new spectra recorded with sample temperatures down to 170 K. High resolution, high signal-to-noise (S/N) laboratory measurements of line shapes (Lorentz air- and self-broadened half-width coefficients, pressure-shift coefficients and off-diagonal relaxation matrix element coefficients) as a function of gas sample temperatures for various pressures and volume mixing ratios are presented. The spectra were recorded using two different Fourier transform spectrometers (FTS): (1) the McMath-Pierce FTS located at the National Solar Observatory on Kitt Peak, Arizona (and reported in Devi et al., J Mol Spectrosc 2007;245:52-80) and, (2) the Bruker IFS-125HR FTS at the Jet Propulsion Laboratory in Pasadena, California. The 19 spectra taken at Kitt Peak were all recorded near room temperature while the 27 Bruker spectra were acquired both at room temperature and colder temperatures (170-296 K). Various spectral resolutions (0.004-0.011 cm-1), absorption path lengths (2.46-121 m) and CO2 samples (natural and 12C-enriched) were included in the dataset. To maximize the accuracies of the various retrieved line parameters, a multispectrum nonlinear least squares spectrum fitting software program was used to adjust the ro-vibrational constants (G,B,D etc.) and intensity parameters (including Herman-Wallis terms) instead of directly measuring the individual line positions and intensities. To minimize systematic residuals, line mixing (via off-diagonal relaxation matrix elements) and quadratic speed dependence parameters were included in the analysis. Contributions from other weakly absorbing bands: the 30013←00001 and 30012←00001 bands of 13C16O2, the 30013←00001 band of 12C16O18O, hot bands 31113←01101 and 32212←02201 of 12C16O2, as well as the 40013←10001 and the 40014←10002 bands of 12C16O2, present within the fitted interval were also measured

  14. H{sub 2}-He vibrational line-shape parameters: Measurement and semiclassical calculation

    SciTech Connect

    Forsman, J.W.; Bonamy, J.; Robert, D.; Berger, J.P.; Saint-Loup, R.; Berger, H.

    1995-10-01

    High-resolution inverse Raman spectroscopy has been used to obtain the line shifting and line broadening coefficients of H{sub 2} perturbed by He. Measurements have been made for the {ital Q}-branch transitions ({ital J}=0{r_arrow}5) in a density range of 10 to 20 amagat and from 296 to 995 K. Up to 795 K we have directly deduced from the experimental broadening coefficients the inelastic rotational state-to-state and vibrational dephasing rates. At higher temperatures, owing to the larger number of channels of relaxation which occur, the results have been analyzed using a scaling law. The line shift and broadening coefficients exhibit a square root and a linear dependence on temperature, respectively, and a significant {ital J} dependence. Semiclassical calculations based on an accurate {ital ab} {ital initio} potential lead to line-shape parameters consistent with experiment. They allow a clear understanding of their observed temperature dependence.

  15. Raman Q-branch line shapes as a test of the H2-Ar intermolecular potential

    NASA Technical Reports Server (NTRS)

    Green, Sheldon

    1990-01-01

    The line-shape cross sections of vibrational Raman Q-branch spectra are determined theoretically for D2 and H2 in Ar. The calculations are based on accurate close-coupling matrices and the intermolecular potential obtained by Le Roy and Hutson (1987) from spectra of van der Waals complexes. The calculation techniques applied are explained, and the results are presented in tables and graphs and discussed in detail with reference to published experimental data. Agreement to within about 25 percent is obtained for the line widths, but the line shifts are found to be a factor of two smaller than the measured values, and a temperature dependence of line-width cross sections is predicted which is not observed experimentally.

  16. Mode parity-controlled Fano- and Lorentz-like line shapes arising in plasmonic nanorods.

    PubMed

    Verellen, Niels; López-Tejeira, Fernando; Paniagua-Domínguez, Ramón; Vercruysse, Dries; Denkova, Denitza; Lagae, Liesbet; Van Dorpe, Pol; Moshchalkov, Victor V; Sánchez-Gil, José A

    2014-05-14

    We present the experimental observation of spectral lines of distinctly different shapes in the optical extinction cross-section of metallic nanorod antennas under near-normal plane wave illumination. Surface plasmon resonances of odd mode parity present Fano interference in the scattering cross-section, resulting in asymmetric spectral lines. Contrarily, modes with even parity appear as symmetric Lorentzian lines. Finite element simulations are used to verify the experimental results. The emergence of either constructive or destructive mode interference is explained with a semianalytical 1D line current model. This simple model directly explains the mode-parity dependence of the Fano-like interference. Plasmonic nanorods are widely used as half-wave optical dipole antennas. Our findings offer a perspective and theoretical framework for operating these antennas at higher-order modes. PMID:24702521

  17. The JHU-SDSS Metal Absorption Line Catalog: Redshift Evolution and Properties of Mg II Absorbers

    NASA Astrophysics Data System (ADS)

    Zhu, Guangtun; Ménard, Brice

    2013-06-01

    We present a generic and fully automatic method aimed at detecting absorption lines in the spectra of astronomical objects. The algorithm estimates the source continuum flux using a dimensionality reduction technique and nonnegative matrix factorization, and then detects and identifies metal absorption lines. We apply it to a sample of ~105 quasar spectra from the Sloan Digital Sky Survey and compile a sample of ~40,000 Mg II- and Fe II-absorber systems, spanning the redshift range 0.4 < z < 2.3. The corresponding catalog is publicly available. We study the statistical properties of these absorber systems and find that the rest equivalent width distribution of strong Mg II absorbers follows an exponential distribution at all redshifts, confirming previous studies. Combining our results with recent near-infrared observations of Mg II absorbers, we introduce a new parameterization that fully describes the incidence rate of these systems up to z ~ 5. We find the redshift evolution of strong Mg II absorbers to be remarkably similar to the cosmic star formation history over 0.4 < z < 5.5 (the entire redshift range covered by observations), suggesting a physical link between these two quantities.

  18. THE JHU-SDSS METAL ABSORPTION LINE CATALOG: REDSHIFT EVOLUTION AND PROPERTIES OF Mg II ABSORBERS

    SciTech Connect

    Zhu Guangtun; Menard, Brice

    2013-06-20

    We present a generic and fully automatic method aimed at detecting absorption lines in the spectra of astronomical objects. The algorithm estimates the source continuum flux using a dimensionality reduction technique and nonnegative matrix factorization, and then detects and identifies metal absorption lines. We apply it to a sample of {approx}10{sup 5} quasar spectra from the Sloan Digital Sky Survey and compile a sample of {approx}40,000 Mg II- and Fe II-absorber systems, spanning the redshift range 0.4 < z < 2.3. The corresponding catalog is publicly available. We study the statistical properties of these absorber systems and find that the rest equivalent width distribution of strong Mg II absorbers follows an exponential distribution at all redshifts, confirming previous studies. Combining our results with recent near-infrared observations of Mg II absorbers, we introduce a new parameterization that fully describes the incidence rate of these systems up to z {approx} 5. We find the redshift evolution of strong Mg II absorbers to be remarkably similar to the cosmic star formation history over 0.4 < z < 5.5 (the entire redshift range covered by observations), suggesting a physical link between these two quantities.

  19. Star formation history in early-type galaxies - I. The line absorption indices diagnostics

    NASA Astrophysics Data System (ADS)

    Tantalo, Rosaria; Chiosi, Cesare

    2004-09-01

    To unravel the formation mechanism and the evolutionary history of elliptical galaxies (EGs) is one of the goals of modern astrophysics. In a simplified picture of the issue, the question to be answered is whether they have formed by hierarchical merging of pre-existing substructures (maybe disc galaxies) made of stars and gas, with each merging event probably accompanied by strong star formation, or conversely, whether they originated from the early aggregation of lumps of gas turned into stars in the remote past via a burst-like episode ever since followed by quiescence so as to mimic a sort of monolithic process. Even if the two alternatives seem to oppose each other, actually they may both contribute to shaping the final properties of EGs as seen today. Are there distinct signatures of the underlying dominant process in the observational data? To this aim we have examined the line absorption indices on the Lick system of the normal, field EGs of Trager and the interacting EGs (pair- and shell-objects) of Longhetti et al. The data show that both normal, field and interacting galaxies have the same scattered but smooth distribution in the Hβ versus [MgFe] plane even if the interacting ones show a more pronounced tail toward high Hβ values. This may suggest that a common physical cause is at the origin of their distribution. There are two straightforward interpretations of increasing complexity. (i) EGs span true large ranges of ages and metallicities. A young age is the signature of the aggregation mechanism, each event accompanied by metal enrichment. This simple scheme cannot, however, explain other spectro-photometric properties of EGs and has to be discarded. (ii) The bulk population of stars is old but subsequent episodes of star formation scatter the EGs in the diagnostic planes. However, this scheme would predict an outstanding clump at low Hβ values, contrary to what is observed. The model can be cured by supposing that the primary star formation

  20. An immortal cell line to study the role of endogenous CFTR in electrolyte absorption.

    PubMed

    Bell, C L; Quinton, P M

    1995-01-01

    The intact human reabsorptive sweat duct (RD) has been a reliable model for investigations of the functional role of "endogenous" CFTR (cystic fibrosis transmembrane conductance regulator) in normal and abnormal electrolyte absorptive function. But to overcome the limitations imposed by the use of fresh, intact tissue, we transformed cultured RD cells using the chimeric virus Ad5/SV40 1613 ori-. The resultant cell line, RD2(NL), has remained differentiated forming a polarized epithelium that expressed two fundamental components of absorption, a cAMP activated Cl- conductance (GCl) and an amiloride-sensitive Na+ conductance (GNa). In the unstimulated state, there was a low level of transport activity; however, addition of forskolin (10(-5) M) significantly increased the Cl- diffusion potential (Vt) generated by a luminally directed Cl- gradient from -15.3 +/- 0.7 mV to -23.9 +/- 1.1 mV, n = 39; and decreased the transepithelial resistance (Rt) from 814.8 +/- 56.3 omega.cm2 to 750.5 +/- 47.5 omega.cm2, n = 39, (n = number of cultures). cAMP activation, anion selectivity (Cl- > I- > gluconate), and a dependence upon metabolic energy (metabolic poisoning inhibited GCl), all indicate that the GCl expressed in RD2(NL) is in fact CFTR-GCl. The presence of an apical amiloride-sensitive GNa was shown by the amiloride (10(-5) M) inhibition of GNa as indicated by a reduction of Vt and equivalent short circuit current by 78.0 +/- 3.1% and 77.9 +/- 2.6%, respectively, and an increase in Rt by 7.2 +/- 0.8%, n = 36. In conclusion, the RD2(NL) cell line presents the first model system in which CFTR-GCl is expressed in a purely absorptive tissue.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7535636

  1. Transient dispersion and absorption in a V-shaped atomic system

    NASA Astrophysics Data System (ADS)

    Sahrai, M.; Maleki, A.; Hemmati, R.; Mahmoudi, M.

    2010-01-01

    We investigate the dynamical behavior of the dispersion and the absorption in a V-type three level atomic system. It is shown that in the presence of decay-induced interference the probe dispersion and absorption are phase dependent. We find that an incoherent pumping field provides an additional control parameter for switching the group velocity of a light pulse. The required switching times for switching the group velocity of a probe field from subluminal to superluminal pulse propagation is then discussed.

  2. Gain and Raman line-broadening with graphene coated diamond-shape nano-antennas.

    PubMed

    Paraskevaidis, Charilaos; Kuykendall, Tevye; Melli, Mauro; Weber-Bargioni, Alexander; Schuck, P James; Schwartzberg, Adam; Dhuey, Scott; Cabrini, Stefano; Grebel, Haim

    2015-10-01

    Using Surface Enhanced Raman Scattering (SERS), we report on intensity-dependent broadening in graphene-deposited broad-band antennas. The antenna gain curve includes both the incident frequency and some of the scattered mode frequencies. By comparing antennas with various gaps and types (bow-tie vs. diamond-shape antennas) we make the case that the line broadening did not originate from strain, thermal or surface potential. Strain, if present, further shifts and broadens those Raman lines that are included within the antenna gain curve. PMID:26332298

  3. Simulation studies of ion dynamic effects on dense plasma line shapes

    SciTech Connect

    Pollock, E.L.

    1986-12-01

    Computer simulations have been widely used in studying dense plasma properties including the local field properties important in spectral line broadening calculations. We will review here a more recent use of simulation, possibly less familiar to this audience, where the time dependent ionic microfield generated by computer simulation of a plasma is used directly as a time dependent external potential for the evolution of the electronic structure of an ion. This permits calculation of the dipole correlation function and thus line shapes with the inclusion of ion dynamic effects. 12 refs., 7 figs.

  4. Asymmetric line shapes for medium energy H and He ions undergoing a large-angle collision

    NASA Astrophysics Data System (ADS)

    Hazama, M.; Kitsudo, Y.; Nishimura, T.; Hoshino, Y.; Grande, P. L.; Schiwietz, G.; Kido, Y.

    2008-11-01

    Asymmetric line shapes for medium energy H and He ions backscattered from topmost adatoms such as Si(111)-3×3-Sb and Ni(111)-2×2-O are measured by a toroidal electrostatic analyzer with an excellent energy resolution. The spectra exhibit a pronounced asymmetric nature and are well fitted by an exponentially modified Gaussian profile. It is found that the nonperturbative coupled-channel calculations reproduce well the observed asymmetric line shapes for He+ impact on different materials, although slightly overestimate the asymmetry for H+ impact on Au. On the other hand, the CASP 3.2 program (involving additional approximations) gives large underestimates for He ions and overestimates for H ions. This problem has been partially solved by modifying the order of the implementation of the shell corrections and higher-order effects in the CASP model.

  5. Fizeau interferometer system for fast high resolution studies of spectral line shapes

    SciTech Connect

    Novak, O.; Falconer, I. S.; Sangines, R.; Tarrant, R. N.; McKenzie, D. R.; Bilek, M. M. M.; Lattemann, M.

    2011-02-15

    A monochromator/Fizeau interferometer/intensified CCD camera system is described that was developed for the measurement of the shape of spectral lines that are rapidly time varying. The most important operating parameter that determines the performance of the instrument is the size of the entrance aperture as this determines both the light throughput and the effective interferometer wavelength resolution. This paper discusses, both theoretically and experimentally, the effect of the finite source area on the instrumental resolution to assist in optimizing the choice of this parameter. A second effect that often produces a practical limit to the quality of the spectra is drift of the interferometer plates. Measurements of the shapes of spectral lines of ions and atoms ejected from the cathode spot of continuous and pulsed cathodic arcs are presented to demonstrate the utility of this instrument.

  6. An analysis of temperature dependent photoluminescence line shapes in InGaN

    NASA Astrophysics Data System (ADS)

    Teo, K. L.; Colton, J. S.; Yu, P. Y.; Weber, E. R.; Li, M. F.; Liu, W.; Uchida, K.; Tokunaga, H.; Akutsu, N.; Matsumoto, K.

    1998-09-01

    Photoluminescence (PL) line shapes in InGaN multiple quantum well structures have been studied experimentally and theoretically between 10 and 300 K. The higher temperature PL spectra can be fitted quantitatively with a thermalized carrier distribution and a broadened joint-density-of-states. The low temperature PL line shapes suggest that carriers are not thermalized, as a result of localization by band-gap fluctuations. We deduce a localization energy of ˜7 meV as compared with an activation energy of ˜63 meV from thermal quenching of the PL intensity. We thus conclude that this activation energy and the band-gap fluctuation most likely have different origins.

  7. Improved Characterization of Healthy and Malignant Tissue by NMR Line-Shape Relaxation Correlations

    PubMed Central

    Peemoeller, H.; Shenoy, R.K.; Pintar, M.M.; Kydon, D.W.; Inch, W.R.

    1982-01-01

    We performed a relaxation-line-shape correlation NMR experiment on muscle, liver, kidney, and spleen tissues of healthy mice and of mouse tumor tissue. In each tissue studied, five spin groups were resolved and characterized by their relaxation parameters. We report a previously uncharacterized semi-solid spin group and discuss briefly the value of this method for the identification of malignant tissues. PMID:7104438

  8. Photosensor aperture shaping to reduce aliasing in optical-mechanical line-scan imaging systems.

    NASA Technical Reports Server (NTRS)

    Katzberg, S. J.; Huck, F. O.; Wall, S. D.

    1973-01-01

    Review of optical-mechanical scanning techniques that are generally employed in instruments specifically designed to characterize variations in scene brightness spectrally or radiometrically. Special attention is given to the effect of aliasing on the spatial detail of the reconstructed image. Aliasing may be caused by linescan sampling and can, in turn, severely degrade images that emphasize the spatial characterization of a scene. Photosensor aperture shaping and line-scan spacing are investigated as means for reducing this degradation.

  9. Line shapes of the exotic charm-anticharm mesons X(3872) and Z(4430)

    NASA Astrophysics Data System (ADS)

    Lu, Meng

    The B-factory experiments have recently discovered a series of new cc mesons, including the X(3872) and the first manifestly exotic meson Z +/-(4430). The proximity of the mass of the X to the D*0D 0 threshold has motivated its identification as a loosely-bound hadronic molecule whose constituents are a superposition of the charm mesons pairs D*0D 0 and D0D* 0. Factorization formulas for its line shapes are derived by taking advantage of the universality of S-wave resonances near a 2-particle threshold and by including the effects from the nonzero width of D* meson and the inelastic scattering channels of the charm mesons. The best fit to the line shapes of X in the J/psipi +pi- and D0 D0pi0 channels measured by the Belle Collaboration corresponds to the X being a bound state whose mass is just below the D*0 D0 threshold. The differences between the line shapes of X produced in B+ decays and B0 decays as well as in decay channels J/psipi+pi-, J /psipi+pi-pi0 , and D0D 0pi0 are further derived by taking into account the effects from the closeby channel composed of charged charm mesons. A more speculative application of the universality of S-wave resonances near a 2-particle threshold is to the Z+/-(4430), which is interpreted as a charm meson molecule composed of a superposition of D+1D*0 and D*+D01 . The small ratio of the binding energy of the Z + to the width of its constituent D1 is exploited to obtained simple predictions for its line shapes in the channels psi(2S)pi + and D*D*pi.

  10. Study of one-dimensional electron hopping and its effects on ESR line shape

    SciTech Connect

    Tang, Jau; Dikshit, S.N.; Norris, J.R. |

    1997-08-01

    Random hopping processes between discrete sites along a finite open chain or around a closed finite loop are examined. Closed form formulae are prescribed for the dependence of the ESR (electron spin resonance) line shape on the chain length and hopping rate. Significant differences between the closed loop and open chain are demonstrated. Deviation at short time from the results of diffusion in a continuum is presented.

  11. Multi-Sightline Observation of Narrow Absorption Lines in Lensed Quasar SDSS J1029+2623

    NASA Astrophysics Data System (ADS)

    Misawa, Toru; Saez, Cristian; Charlton, Jane C.; Eracleous, Michael; Chartas, George; Bauer, Franz E.; Inada, Naohisa; Uchiyama, Hisakazu

    2016-07-01

    We exploit the widely separated images of the lensed quasar SDSS J1029+2623 ({z}{em} = 2.197, θ = 22.″5) to observe its outflowing wind through two different sightlines. We present an analysis of three observations, including two with the Subaru telescope in 2010 February and 2014 April, separated by four years, and one with the Very Large Telescope, separated from the second Subaru observation by ∼2 months. We detect 66 narrow absorption lines (NALs), of which 24 are classified as intrinsic NALs that are physically associated with the quasar based on partial coverage analysis. The velocities of intrinsic NALs appear to cluster around values of {v}{ej} ∼ 59,000, 43,000, and 29,000 km s‑1, which is reminiscent of filamentary structures obtained by numerical simulations. There are no common intrinsic NALs at the same redshift along the two sightlines, implying that the transverse size of the NAL absorbers should be smaller than the sightline distance between two lensed images. In addition to the NALs with large ejection velocities of {v}{ej} > 1000 km s‑1, we also detect broader proximity absorption lines (PALs) at {z}{abs} ∼ {z}{em}. The PALs are likely to arise in outflowing gas at a distance of r ≤ 620 pc from the central black hole with an electron density of n e ≥8.7 × 103 cm‑3. These limits are based on the assumption that the variability of the lines is due to recombination. We discuss the implications of these results on the three-dimensional structure of the outflow.

  12. Differential surface models for tactile perception of shape and on-line tracking of features

    NASA Technical Reports Server (NTRS)

    Hemami, H.

    1987-01-01

    Tactile perception of shape involves an on-line controller and a shape perceptor. The purpose of the on-line controller is to maintain gliding or rolling contact with the surface, and collect information, or track specific features of the surface such as edges of a certain sharpness. The shape perceptor uses the information to perceive, estimate the parameters of, or recognize the shape. The differential surface model depends on the information collected and on the a priori information known about the robot and its physical parameters. These differential models are certain functionals that are projections of the dynamics of the robot onto the surface gradient or onto the tangent plane. A number of differential properties may be directly measured from present day tactile sensors. Others may have to be indirectly computed from measurements. Others may constitute design objectives for distributed tactile sensors of the future. A parameterization of the surface leads to linear and nonlinear sequential parameter estimation techniques for identification of the surface. Many interesting compromises between measurement and computation are possible.

  13. Interferometric control of contact line, shape, and aberrations of liquid lenses

    NASA Astrophysics Data System (ADS)

    Voitenko, Igor; Storm, Ronald; Westfall, Raymond; Rogers, Stanley

    2007-09-01

    An optical system consisting of an aqueous electrolyte resting on a polymer/gold/indium-tin-oxide (ITO) layer deposited onto a glass substrate is analyzed to acquire contact angle - focal distance data as a function of applied voltage. The shape factor of a liquid lens and its dependence on the perimeter of contact line and contact angle was analyzed in the presence of an electrical field applied between the electrolyte and planar electrode system. The contact angle of a liquid on a thin, transparent film of gold (20 nm thick) - on ITO under electrolyte solution could be varied from 110 +/- 3° when the gold was held at -2.4 V to 41 +/- 3° without voltage. The behavior of a water-based electrolyte and water-soluble polymer blend and its influence on the shape of contact line and profile of the lens were investigated by employing a holographic setup at wavelengths of 632.8 and 543.5 nm. Optical micrographs showing the profile of the lens, aberration-less aperture, deformation of contact line, and shape of the liquid lens, respectively, were analyzed in reflection and transmission. Both the advancing and receding contact angles were measured directly from digitized images of the profile of the lens. The dynamic range of linear beam steering and dependence of the focal length of the liquid lens on the applied voltage are discussed.

  14. Catalog of Narrow C IV Absorption Lines in BOSS. II. For Quasars with Z em > 2.4

    NASA Astrophysics Data System (ADS)

    Chen, Zhi-Fu; Qin, Yi-Ping; Qin, Ming; Pan, Cai-Juan; Pan, Da-Sheng

    2014-11-01

    As the second work in a series of papers aiming to detect absorption systems in the quasar spectra of the Baryon Oscillation Spectroscopic Survey, we continue the analysis of Paper I by expanding the quasar sample to those quasars with z em > 2.4. This yields a sample of 21,963 appropriate quasars to search for narrow C IV λλ1548, 1551 absorptions with Wr >= 0.2 Å for both lines. There are 9708 quasars with at least one appropriate absorption system imprinted on their spectra. From these spectra, we detect 13,919 narrow C IV absorption systems whose absorption redshifts cover a range of z abs = 1.8784-4.3704. In this paper and Paper I, we have selected 37,241 appropriate quasars with median S/N >= 4 and 1.54 <~ z em <~ 5.16 to visually analyze narrow C IV λλ1548, 1551 absorption doublets one by one. A total of 15,999 quasars are found to have at least one appropriate absorption system imprinted on their spectra. From these 15,999 quasar spectra, we have detected 23,336 appropriate C IV λλ1548, 1551 absorption systems with Wr >= 0.2 Å whose absorption redshifts cover a range of z abs = 1.4544-4.3704. The largest values of Wr are 3.19 Å for the λ1548 absorption line and 2.93 Å for the λ1551 absorption line, respectively. We find that only a few absorbers show large values of Wr . About 1.1% of the total absorbers have Wr λ1548 >= 2.0 Å.

  15. Importance of representing optical depth variability for estimates of global line-shaped contrail radiative forcing

    PubMed Central

    Kärcher, Bernd; Burkhardt, Ulrike; Ponater, Michael; Frömming, Christine

    2010-01-01

    Estimates of the global radiative forcing by line-shaped contrails differ mainly due to the large uncertainty in contrail optical depth. Most contrails are optically thin so that their radiative forcing is roughly proportional to their optical depth and increases with contrail coverage. In recent assessments, the best estimate of mean contrail radiative forcing was significantly reduced, because global climate model simulations pointed at lower optical depth values than earlier studies. We revise these estimates by comparing the probability distribution of contrail optical depth diagnosed with a climate model with the distribution derived from a microphysical, cloud-scale model constrained by satellite observations over the United States. By assuming that the optical depth distribution from the cloud model is more realistic than that from the climate model, and by taking the difference between the observed and simulated optical depth over the United States as globally representative, we quantify uncertainties in the climate model’s diagnostic contrail parameterization. Revising the climate model results accordingly increases the global mean radiative forcing estimate for line-shaped contrails by a factor of 3.3, from 3.5 mW/m2 to 11.6 mW/m2 for the year 1992. Furthermore, the satellite observations and the cloud model point at higher global mean optical depth of detectable contrails than often assumed in radiative transfer (off-line) studies. Therefore, we correct estimates of contrail radiative forcing from off-line studies as well. We suggest that the global net radiative forcing of line-shaped persistent contrails is in the range 8–20 mW/m2 for the air traffic in the year 2000. PMID:20974909

  16. Importance of representing optical depth variability for estimates of global line-shaped contrail radiative forcing.

    PubMed

    Kärcher, Bernd; Burkhardt, Ulrike; Ponater, Michael; Frömming, Christine

    2010-11-01

    Estimates of the global radiative forcing by line-shaped contrails differ mainly due to the large uncertainty in contrail optical depth. Most contrails are optically thin so that their radiative forcing is roughly proportional to their optical depth and increases with contrail coverage. In recent assessments, the best estimate of mean contrail radiative forcing was significantly reduced, because global climate model simulations pointed at lower optical depth values than earlier studies. We revise these estimates by comparing the probability distribution of contrail optical depth diagnosed with a climate model with the distribution derived from a microphysical, cloud-scale model constrained by satellite observations over the United States. By assuming that the optical depth distribution from the cloud model is more realistic than that from the climate model, and by taking the difference between the observed and simulated optical depth over the United States as globally representative, we quantify uncertainties in the climate model's diagnostic contrail parameterization. Revising the climate model results accordingly increases the global mean radiative forcing estimate for line-shaped contrails by a factor of 3.3, from 3.5 mW/m(2) to 11.6 mW/m(2) for the year 1992. Furthermore, the satellite observations and the cloud model point at higher global mean optical depth of detectable contrails than often assumed in radiative transfer (off-line) studies. Therefore, we correct estimates of contrail radiative forcing from off-line studies as well. We suggest that the global net radiative forcing of line-shaped persistent contrails is in the range 8-20 mW/m(2) for the air traffic in the year 2000. PMID:20974909

  17. Time-Variable Complex Metal Absorption Lines in the Quasar HS 1603+3820

    NASA Astrophysics Data System (ADS)

    Misawa, Toru; Eracleous, Michael; Charlton, Jane C.; Tajitsu, Akito

    2005-08-01

    We present a new spectrum of the quasar HS 1603+3820 taken 1.28 yr (0.36 yr in the quasar rest frame) after a previous observation with Subaru+HDS. The new spectrum enables us to search for time variability as an identifier of intrinsic narrow absorption lines (NALs). This quasar shows a rich complex of C IV NALs within 60,000 km s-1 of the emission redshift. On the basis of covering factor analysis, Misawa et al. found that the C IV NAL system at zabs=2.42-2.45 (system A, at a shift velocity of vsh=8300-10,600 km s-1 relative to the quasar) was intrinsic to the quasar. With our new spectrum, we perform time variability analysis, as well as covering factor analysis, to separate intrinsic NALs from intervening NALs for eight C IV systems. Only system A, which was identified as an intrinsic system in the earlier paper by Misawa et al., shows a strong variation in line strength (Wobs~10.4-->19.1 Å). We speculate that a broad absorption line (BAL) could be forming in this quasar (i.e., many narrower lines will blend together to make a BAL profile). We illustrate the plausibility of this suggestion with the help of a simulation in which we vary the column densities and covering factors of the NAL complex. Under the assumption that a change of ionization state causes the variability, a lower limit can be placed on the electron density (ne>~3×104cm-3) and an upper limit on the distance from the continuum source (r<=6 kpc). On the other hand, if the motion of clumpy gas causes the variability (a more likely scenario), the crossing velocity and the distance from the continuum source are estimated to be vcross>8000 km s-1 and r<3 pc. In this case, the absorber does not intercept any flux from the broad emission line region, but only flux from the UV continuum source. If we adopt the dynamical model of Murray et al., we can obtain a much more strict constraint on the distance of the gas parcel from the continuum source, r<0.2 pc. Based on data collected at the Subaru

  18. Spectral line-shapes of oxygen B-band transitions measured with cavity ring-down spectroscopy

    NASA Astrophysics Data System (ADS)

    Wójtewicz, S.; Cygan, A.; Masłowski, P.; Domysławska, J.; Wcisło, P.; Zaborowski, M.; Lisak, D.; Trawiński, R. S.; Ciuryło, R.

    2014-11-01

    Results of line-shape measurements of self- and N2-broadened P9 P9 transition of the oxygen B band are presented. Spectra were acquired using the optical frequency comb- assisted Pound-Drever-Hall-locked frequency-stabilized cavity ring-down spectrometer (PDH- locked FS-CRDS). In the line-shape analysis the line narrowing described by Dicke narrowing or/and the speed dependence of collisional broadening were taken into account. The multispectrum fitting technique was used to minimize numerical correlations between line-shape parameters. Collisional broadening and shifting coefficients are reported with sub-percent uncertainties. Influence of the spectral line-shape model used in data analysis on determined line intensities and collisional broadening is discussed.

  19. The velocity distribution of interstellar gas observed in strong UV absorption lines

    NASA Technical Reports Server (NTRS)

    Cowie, L. L.; York, D. G.

    1978-01-01

    Observations of three strong interstellar UV absorption lines of N I (1199 A), N II (1083 A), and Si III (1206 A) in 47 stars of widely varying distance and a variety of spectral types are analyzed to obtain a velocity distribution function for the interstellar gas. A technique based on the maximum and minimum velocities observed along a line of sight is adopted because of heavy line blending, and results are discussed for both power-law and exponential distribution functions. The expected distribution of radiative-phase supernova remnants (SNRs) in the interstellar medium is calculated as a function of SNR birthrate and of the interstellar density in which they evolve. The results are combined with observed distance estimates, and it is shown that an interstellar density in excess of 0.1 per cu cm would be required to keep the SNRs sufficiently confined so that their cross sections are consistent with the observed number of components. The alternative possibility is considered that SNRs do not enter the radiative phase before escaping from the Galaxy or colliding with neighboring remnants.

  20. Rest-frame optical properties of luminous, radio-selected broad absorption line quasars

    NASA Astrophysics Data System (ADS)

    Runnoe, Jessie C.; Ganguly, R.; Brotherton, M. S.; DiPompeo, M. A.

    2013-08-01

    We have obtained Infrared Telescope Facility/SpeX spectra of eight moderate-redshift (z = 0.7-2.4), radio-selected (log R* ≈ 0.4-1.9) broad absorption line (BAL) quasars. The spectra cover the rest-frame optical band. We compare the optical properties of these quasars to those of canonically radio-quiet (log R* ≲ 1) BAL quasars at similar redshifts and to low-redshift quasars from the Palomar-Green catalogue. As with previous studies of BAL quasars, we find that [O III] λ5007 is weak, and optical Fe II emission is strong, a rare combination in canonically radio-loud (log R* ≳ 1) quasars. With our measurements of the optical properties, particularly the Balmer emission-line widths and the continuum luminosity, we have used empirical scaling relations to estimate black hole masses and Eddington ratios. These lie in the range (0.4-2.6) × 109 M⊙ and 0.1-0.9, respectively. Despite their comparatively extreme radio properties relative to most BAL quasars, their optical properties are quite consistent with those of radio-quiet BAL quasars and dissimilar to those of radio-loud non-BAL quasars. While BAL quasars generally appear to have low values of [O III] λ5007/Fe II an extreme of `Eigenvector 1', the Balmer line widths and Eddington ratios do not appear to significantly differ from those of unabsorbed quasars at similar redshifts and luminosities.

  1. Gain and Raman line-broadening with graphene coated diamond-shape nano-antennas

    NASA Astrophysics Data System (ADS)

    Paraskevaidis, Charilaos; Kuykendall, Tevye; Melli, Mauro; Weber-Bargioni, Alexander; Schuck, P. James; Schwartzberg, Adam; Dhuey, Scott; Cabrini, Stefano; Grebel, Haim

    2015-09-01

    Using Surface Enhanced Raman Scattering (SERS), we report on intensity-dependent broadening in graphene-deposited broad-band antennas. The antenna gain curve includes both the incident frequency and some of the scattered mode frequencies. By comparing antennas with various gaps and types (bow-tie vs. diamond-shape antennas) we make the case that the line broadening did not originate from strain, thermal or surface potential. Strain, if present, further shifts and broadens those Raman lines that are included within the antenna gain curve.Using Surface Enhanced Raman Scattering (SERS), we report on intensity-dependent broadening in graphene-deposited broad-band antennas. The antenna gain curve includes both the incident frequency and some of the scattered mode frequencies. By comparing antennas with various gaps and types (bow-tie vs. diamond-shape antennas) we make the case that the line broadening did not originate from strain, thermal or surface potential. Strain, if present, further shifts and broadens those Raman lines that are included within the antenna gain curve. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr03893f

  2. Sensitivity of thin cirrus clouds in the tropical tropopause layer to ice crystal shape and radiative absorption

    NASA Astrophysics Data System (ADS)

    Russotto, R. D.; Ackerman, T. P.; Durran, D. R.

    2016-03-01

    Subvisible cirrus clouds in the tropical tropopause layer (TTL) play potentially important roles in Earth's radiation budget and in the transport of water into the stratosphere. Previous work on these clouds with 2-D cloud-resolving models has assumed that all ice crystals were spherical, producing too few crystals greater than 60 μm in length compared with observations. In this study, the System for Atmospheric Modeling cloud-resolving model is modified in order to calculate the fall speeds, growth rates, and radiative absorption of nonspherical ice crystals. This extended model is used in simulations that aim to provide an upper bound on the effects of ice crystal shape on the time evolution of thin cirrus clouds and to identify the physical processes responsible for any such effects. Model runs assuming spheroidal crystals result in a higher center of cloud ice mass than in the control, spherical case, while the total mass of ice is little affected by the shape. Increasing the radiative heating results in less total cloud ice mass relative to the control case, an effect which is robust with more extreme perturbations to the absorption coefficients. This is due to higher temperatures reducing the relative humidity in the cloud and its environment, and greater entrainment of dry air due to dynamical changes. Comparisons of modeled ice crystal size distributions with recent airborne observations of TTL cirrus show that incorporating nonspherical shape has the potential to bring the model closer to observations.

  3. Spectral line shape of the P(2) transition in CO-Ar: Uncorrelated ab initio calculation

    SciTech Connect

    Wehr, R.; Vitcu, A.; Drummond, J.R.; May, A.D.; Ciurylo, R.

    2002-12-01

    We calculate the spectral line shape of an isolated line from first principles, assuming that the translational motion is not statistically correlated with the evolution of the optical coherence, i.e., with the broadening. We use the known, realistic potentials for the influence of collisions on the translational motion and on the internal motion. We show that the calculated profiles do not agree, particularly at low pressures, with very precise experimental profiles of the P(2) line of CO in a bath of Ar. We establish that the source of the disagreement lies in the assumption of uncorrelated effects of collisions on the translational motion and the optical coherence associated with the internal degrees of freedom.

  4. A new approach to spectral line shapes of the weak oxygen transitions for atmospheric applications

    NASA Astrophysics Data System (ADS)

    Domysławska, Jolanta; Wójtewicz, Szymon; Masłowski, Piotr; Cygan, Agata; Bielska, Katarzyna; Trawiński, Ryszard S.; Ciuryło, Roman; Lisak, Daniel

    2016-01-01

    We propose to construct a new database of O2 molecular spectral lines for atmospheric application, consistent with recent IUPAC recommendation [Tennyson et al. Pure Appl Chem 2014;86:1931] going beyond Voigt profile by incorporation of the speed dependence of collisional broadening and shifting. For this purpose we collected the laboratory data for the self-perturbed oxygen B-band transitions. Line shapes were measured at low pressures by the Pound-Drever-Hall-locked frequency-stabilized cavity ring-down spectrometer linked to the optical frequency comb. Data were analyzed by means of the quadratic speed-dependent Voigt profile. The absolute transition frequencies are determined with accuracy even as good as 150 kHz. Line intensities, pressure width and shift coefficients and the speed-dependent parameters are determined with subpercent accuracy.

  5. The generalization of upper atmospheric wind and temperature based on the Voigt line shape profile.

    PubMed

    Zhang, Chunmin; He, Jian

    2006-12-25

    The principle of probing the upper atmospheric wind field, which is the Voigt profile spectral line shape, is presented for the first time. By the Fourier Transform of Voigt profile, with the Imaging Spectroscope and the Doppler effect of electromagnetic wave, the distribution and calculation formulae of the velocity field, temperature field, and pressure field of the upper atmosphere wind field are given. The probed source is the two major aurora emission lines originated from the metastable O(1S) and O(1D) at 557.7nm and 630.0nm. From computer simulation and error analysis, the Voigt profile, which is the correlation of the Gaussian profile and Lorentzian profile, is closest to the actual airglow emission lines. PMID:19532147

  6. Measurement of the electron density in a subatmospheric dielectric barrier discharge by spectral line shape

    SciTech Connect

    Dong Lifang; Qi Yuyan; Liu Weiyuan; Fan Weili

    2009-07-01

    The electron density in a subatmospheric dielectric barrier discharge by using argon spectral line shape is measured for the first time. With the gas pressure increasing in the range of 1x10{sup 4} Pa-6x10{sup 4} Pa, the line profiles of argon 696.54 nm are measured. An asymmetrical deconvolution procedure is applied to separate the Gaussian and Lorentzian profile from the measured spectral line. The gas temperature is estimated by using rotational temperature of N{sub 2}{sup +}. By subtracting the van der Waals broadening and partial Lorentzian instrumental broadening from the Lorentzian broadening, the Stark broadening is obtained and used to estimate the electron density. It is found that the electron density in dielectric barrier discharge increases with the increase in gas pressure.

  7. Intrinsic Line Shape Measurements of the XRS Instrument on Astro-E2

    NASA Technical Reports Server (NTRS)

    Porter, F. Scott

    2004-01-01

    The XRS instrument on the Astro-E2 observatory contains a substantially improved microcalorimeter array over the Astro-E mission. In addition to roughly a factor of 2 improvement in the detector resolution at 6 keV, the detector response is shown to be almost perfectly gaussian. We have made measurements of the detector response of the flight instrument, using a double crystal monochrometer at 4 and 8 keV, a 55-Fe internal conversion source, and x-ray induced fluorescence from a number of targets including Ti, Cu, and GaAs. The detector response has been measured to be entirely gaussian to at least 2 orders of magnitude down from the peak of the line or line complex. This is in sharp contrast to the results from the XRS on Astro-E where many channels exhibited excess counts on the high energy side of the spectral lines. Here we present details of the line shape measurement as well as the detector response as measured during the XRS ground calibration including details of the line fits and line models.

  8. Multi - Wavelength Analysis of Intermediate Class Absorption Line Galaxies in CFHTLS Field

    NASA Astrophysics Data System (ADS)

    Baburao Pandge, Mahadev

    2015-08-01

    We present optical and X-ray analysis of a sample of some absorption line galaxies (ALGs). These galaxies are lie in the redshift range 0.14 < z < 0.34 and have X-ray luminosities L{0.5-10keV} = 1041-1043 erg s-1. The distribution of log (fX/fO) imply that these objects are intermediate class objects, i.e. lie between normal and classical active galaxies. From X-ray analysis of two of the intermediate class galaxies, namely ALG2 and ALG3, exhibit extended nature, perhaps linked with their cluster environment. Thus, from the X-ray spectral and optical imaging analysis, it is likely that all the targeted ALGs studied here can be the group/cluster candidates. Hardness ratio of these 5 candidates is found to be -0.42 \\pm 0.10, consistent with that reported for galaxies.

  9. X-ray absorption/emission line spectroscopy of the Galactic hot gaseous halo

    NASA Astrophysics Data System (ADS)

    Wang, Daniel

    2016-04-01

    There is an ongoing debate as to whether or not the Milky Way is surrounded by a large-scale, massive corona. Vastly different conclusions as to its extent and mass have been drawn from existing studies based on X-ray absorption and/or emission line spectroscopy. I will discuss my assessment of this issue, focusing on various uncertainties and potential problems in the present data, analyses, results, and interpretations.In particular, I will examine how different assumptions about the temperature distribution of the corona affect the inference of its physical scale. I will also discuss the external perspectives of galactic coronae obtained form observing nearby highly-inclined disk galaxies.

  10. QSO absorption lines: The UV rest frame from 0

    NASA Astrophysics Data System (ADS)

    Churchill, Christopher W.

    1997-05-01

    By charting the kinematic, chemical, and ionization conditions of galactic and intergalactic gas over the redshift range 0-4 with QSO absorption lines, the evolution of chemical abundances, the UV meta-galactic background, and the clustering dynamics of galactic gas can be studied. Keck/HIRES Mg II λ2796 profiles arising in z~1 galaxies are presented and the Mg II kinematic clustering function is given. The intriguing z=0.93 systems toward Q1206+459 are shown and compared to z~2 Keck/HIRES C IV profiles to illustrate how HST/STIS can be exploited for studies of the high ionization conditions in z<=1 Mg II selected systems. The scientific motives and plans for a large IR 2<=z<=4 Mg II survey with the Hobby-Eberly Telescope are presented.

  11. Fine Structure of the R Absorption Lines of Cr3+ in Antiferromagnetic Dysprosium Aluminum Garnet

    NASA Astrophysics Data System (ADS)

    Aoyagi, Kiyoshi; Kajiura, Masako; Sugano, Satoru

    1981-11-01

    The absorption spectrum of a Cr3+ ion in an antiferromagnetic disprosium aluminum garnet with the Néel temperature TN of 2.5 K, is measured in the red region between 1.7 K and 4.2 K. It is shown that the fine structure of the R1 and R2 lines at 1.7 K can be explained by using an effective Hamiltonian for the t2g3 2E excited state of Cr3+ in the surrounding of the ordered Dy3+ spins. The gross feature of the observed temperature dependence of the fine structure is shown to be reproduced by assuming appropriate exchange interactions of Cr3+ with Dy3+.

  12. Determination of molecular line parameters for acrolein (C 3H 4O) using infrared tunable diode laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Harward, Charles N.; Thweatt, W. David; Baren, Randall E.; Parrish, Milton E.

    2006-04-01

    Acrolein (C 3H 4O) molecular line parameters, including infrared (IR) absorption positions, strengths, and nitrogen broadened half-widths, must be determined since they are not included in the high resolution transmission (HITRAN) molecular absorption database of spectral lines. These parameters are required for developing a quantitative analytical method for measuring acrolein in a single puff of cigarette smoke using tunable diode laser absorption spectroscopy (TDLAS). The task is complex since acrolein has many highly overlapping infrared absorption lines in the room temperature spectrum and the cigarette smoke matrix contains thousands of compounds. This work describes the procedure for estimating the molecular line parameters for these overlapping absorption lines in the wavenumber range (958.7-958.9 cm -1) using quantitative reference spectra taken with the infrared lead-salt TDLAS instrument at different pressures and concentrations. The nitrogen broadened half-width for acrolein is 0.0937 cm -1 atm -1 and to our knowledge, is the first time it has been reported in the literature.

  13. Unusual high-redshift radio broad absorption-line quasar 1624+3758

    NASA Astrophysics Data System (ADS)

    Benn, C. R.; Carballo, R.; Holt, J.; Vigotti, M.; González-Serrano, J. I.; Mack, K.-H.; Perley, R. A.

    2005-07-01

    We present observations of the most radio-luminous broad absorption-line (BAL) quasar known, 1624+3758, at redshift z= 3.377. The quasar has several unusual properties. (1) The FeII UV191 1787-Åemission line is very prominent. (2) The BAL trough (BALnicity index 2990 km s-1) is detached by 21000 km s-1 and extends to velocity v=-29000 km s-1. There are additional intrinsic absorbers at -1900 and -2800 km s-1. (3) The radio rotation measure of the quasar, 18350 rad m-2, is the second highest known. The radio luminosity is P1.4GHz= 4.3 × 1027 W Hz-1 (H0= 50 km s-1 Mpc-1, q0= 0.5) and the radio loudness is R*= 260. The radio source is compact and the radio spectrum is GHz-peaked, consistent with it being relatively young. The width of the CIV emission line, in conjunction with the total optical luminosity, implies a black hole mass MBH~ 109Msolar, L/LEddington~ 2. The high Eddington ratio and the radio-loudness place this quasar in one corner of Boroson's two-component scheme for the classification of active galactic nuclei, implying a very high accretion rate, and this may account for some of the unusual observed properties. The v=-1900km s-1 absorber is a possible Lyman-limit system, with N(HI) = 4 × 1018 cm-2, and a covering factor of 0.7. A complex mini-BAL absorber at v=-2200 to -3400 km s-1 is detected in each of CIV, NV and OVI. The blue and red components of the CIV doublet happen to be unblended, allowing both the covering factor and optical depth to be determined as a function of velocity. Variation of the covering factor with velocity dominates the form of the mini-BAL, with the absorption being saturated (e-τ~ 0) over most of the velocity range. The velocity dependence of the covering factor and the large velocity width imply that the mini-BAL is intrinsic to the quasar. There is some evidence of line-locking between velocity components in the CIV mini-BAL, suggesting that radiation pressure plays a role in accelerating the outflow.

  14. Determination of mass loss and mass transfer rates of Algol (Beta Persei) from the analysis of absorption lines in the UV spectra obtained by the IUE satellite

    NASA Astrophysics Data System (ADS)

    Wecht, Kristen

    The International Ultraviolet Explorer (IUE) archive of high-resolution ultraviolet spectra of the eclipsing semi-detached binary star, Algol ([beta] Persei, HD 19356), taken from September 1978 to September 1989, is analyzed in order to characterize the movement of gas within and from this system. Light curves are constructed, using a total of 1647 continuum level measurements. These results support the semidetached status of this interacting binary star. Radial velocities, residual intensities, full width half maxima (FWHM), line asymmetries, and equivalent widths of UV absorption lines for aluminum, magnesium, iron, and silicon in a range of ionization states are determined and analyzed. For selected epochs, we were able to isolate gas stream and photospheric contributions by an examination of the differences between spectral line shapes. We observed variations in line shape and strength, with orbital phase and epoch, indicating the presence of stable gas streams and circumstellar gas, and periods of increased mass-transfer activity associated with transient gas streams. The 1989 data indicates moderate activity. This epoch was examined most closely since it provides the greatest phase coverage. Spectral line profiles in 1978 and 1984 have the strongest gas-flow absorption components, indicating that these are the epochs of the greatest activity. The dense phase coverage in September 1989 allows us to measure the mass loss rate from Algol B into Algol A which is of order ~10 -14 [Special characters omitted.] /yr. Since the highest gas-flow velocities are in the 100 kilometer per second range, well below escape velocity, we conclude that systemic mass loss due to gas flow is small for the Algol system.

  15. THE STELLAR INITIAL MASS FUNCTION IN EARLY-TYPE GALAXIES FROM ABSORPTION LINE SPECTROSCOPY. II. RESULTS

    SciTech Connect

    Conroy, Charlie; Van Dokkum, Pieter G.

    2012-11-20

    The spectral absorption lines in early-type galaxies contain a wealth of information regarding the detailed abundance pattern, star formation history, and stellar initial mass function (IMF) of the underlying stellar population. Using our new population synthesis model that accounts for the effect of variable abundance ratios of 11 elements, we analyze very high quality absorption line spectra of 38 early-type galaxies and the nuclear bulge of M31. These data extend to 1 {mu}m and they therefore include the IMF-sensitive spectral features Na I, Ca II, and FeH at 0.82 {mu}m, 0.86 {mu}m, and 0.99 {mu}m, respectively. The models fit the data well, with typical rms residuals {approx}< 1%. Strong constraints on the IMF and therefore the stellar mass-to-light ratio, (M/L){sub stars}, are derived for individual galaxies. We find that the IMF becomes increasingly bottom-heavy with increasing velocity dispersion and [Mg/Fe]. At the lowest dispersions and [Mg/Fe] values the derived IMF is consistent with the Milky Way (MW) IMF, while at the highest dispersions and [Mg/Fe] values the derived IMF contains more low-mass stars (is more bottom-heavy) than even a Salpeter IMF. Our best-fit (M/L){sub stars} values do not exceed dynamically based M/L values. We also apply our models to stacked spectra of four metal-rich globular clusters in M31 and find an (M/L){sub stars} that implies fewer low-mass stars than a MW IMF, again agreeing with dynamical constraints. We discuss other possible explanations for the observed trends and conclude that variation in the IMF is the simplest and most plausible.

  16. BROAD ABSORPTION LINE VARIABILITY ON MULTI-YEAR TIMESCALES IN A LARGE QUASAR SAMPLE

    SciTech Connect

    Filiz Ak, N.; Brandt, W. N.; Schneider, D. P.; Hall, P. B.; Anderson, S. F.; Hamann, F.; Lundgren, B. F.; Myers, Adam D.; Pâris, I.; Petitjean, P.; Ross, Nicholas P.; Shen, Yue; York, Don

    2013-11-10

    We present a detailed investigation of the variability of 428 C IV and 235 Si IV broad absorption line (BAL) troughs identified in multi-epoch observations of 291 quasars by the Sloan Digital Sky Survey-I/II/III. These observations primarily sample rest-frame timescales of 1-3.7 yr over which significant rearrangement of the BAL wind is expected. We derive a number of observational results on, e.g., the frequency of BAL variability, the velocity range over which BAL variability occurs, the primary observed form of BAL-trough variability, the dependence of BAL variability upon timescale, the frequency of BAL strengthening versus weakening, correlations between BAL variability and BAL-trough profiles, relations between C IV and Si IV BAL variability, coordinated multi-trough variability, and BAL variations as a function of quasar properties. We assess implications of these observational results for quasar winds. Our results support models where most BAL absorption is formed within an order-of-magnitude of the wind-launching radius, although a significant minority of BAL troughs may arise on larger scales. We estimate an average lifetime for a BAL trough along our line-of-sight of a few thousand years. BAL disappearance and emergence events appear to be extremes of general BAL variability, rather than being qualitatively distinct phenomena. We derive the parameters of a random-walk model for BAL EW variability, finding that this model can acceptably describe some key aspects of EW variability. The coordinated trough variability of BAL quasars with multiple troughs suggests that changes in 'shielding gas' may play a significant role in driving general BAL variability.

  17. A variable P v broad absorption line and quasar outflow energetics

    NASA Astrophysics Data System (ADS)

    Capellupo, D. M.; Hamann, F.; Barlow, T. A.

    2014-10-01

    Broad absorption lines (BALs) in quasar spectra identify high-velocity outflows that might exist in all quasars and could play a major role in feedback to galaxy evolution. The viability of BAL outflows as a feedback mechanism depends on their kinetic energies, as derived from the outflow velocities, column densities, and distances from the central quasar. We estimate these quantities for the quasar, Q1413+1143 (redshift ze = 2.56), aided by the first detection of P V λλ1118, 1128 BAL variability in a quasar. In particular, P V absorption at velocities where the C IV trough does not reach zero intensity implies that the C IV BAL is saturated and the absorber only partially covers the background continuum source (with characteristic size <0.01 pc). With the assumption of solar abundances, we estimate that the total column density in the BAL outflow is log NH ≳ 22.3 cm-2. Variability in the P V and saturated C IV BALs strongly disfavours changes in the ionization as the cause of the BAL variability, but supports models with high column density BAL clouds moving across our lines of sight. The observed variability time of 1.6 yr in the quasar rest frame indicates crossing speeds >750 km s-1 and a radial distance from the central black hole of ≲ 3.5 pc, if the crossing speeds are Keplerian. The total outflow mass is ˜4100 M⊙, the kinetic energy ˜4 × 1054 erg, and the ratio of the outflow kinetic energy luminosity to the quasar bolometric luminosity is ˜0.02 (at the minimum column density and maximum distance), which might be sufficient for important feedback to the quasar's host galaxy.

  18. A new perspective on the interstellar cloud surrounding the Sun from UV absorption line results

    NASA Astrophysics Data System (ADS)

    Gry, Cecile; Jenkins, Edward B.

    2015-01-01

    We offer a new, more inclusive, picture of the local interstellar medium, where it is composed of a single, monolithic cloud that surrounds the Sun in all directions. Our study of velocities based on Mg II and Fe II ultraviolet absorption lines indicates that the cloud has an average motion consistent with the velocity vector of gas impacting the heliosphere and does not behave like a rigid body: gas within the cloud is being differentially decelerated in the direction of motion, and the cloud is expanding in directions perpendicular to this flow, much like the squashing of a balloon. The outer boundary of the cloud is in average 10 pc away from us but is highly irregular, being only a few parsecs away in some directions, with possibly a few extensions up to 20 pc. Average H I volume densities vary between 0.03 and 0.1 cm3 over different sight lines. Metals appear to be significantly depleted onto grains, and there is a steady increase in this effect from the rear of the cloud to the apex of motion. There is no evidence that changes in the ionizing radiation influence the apparent abundances. Additional, secondary velocity components are detected in 60% of the sight lines. Almost all of them appear to be interior to the volume holding the gas that we identify with the main cloud. Half of the sight lines exhibit a secondary component moving at about - 7.2 km/s with respect to the main component, which may be the signature of an implosive shock propagating toward the cloud's interior.

  19. Investigating the radio-loud phase of broad absorption line quasars

    NASA Astrophysics Data System (ADS)

    Bruni, G.; González-Serrano, J. I.; Pedani, M.; Benn, C. R.; Mack, K.-H.; Holt, J.; Montenegro-Montes, F. M.; Jiménez-Luján, F.

    2014-09-01

    Context. Broad absorption lines (BALs) are present in the spectra of ~20% of quasars (QSOs); this indicates fast outflows (up to 0.2c) that intercept the observer's line of sight. These QSOs can be distinguished again into radio-loud (RL) BAL QSOs and radio-quiet (RQ) BAL QSOs. The first are very rare, even four times less common than RQ BAL QSOs. The reason for this is still unclear and leaves open questions about the nature of the BAL-producing outflows and their connection with the radio jet. Aims: We explored the spectroscopic characteristics of RL and RQ BAL QSOs with the aim to find a possible explanation for the rarity of RL BAL QSOs. Methods: We identified two samples of genuine BAL QSOs from SDSS optical spectra, one RL and one RQ, in a suitable redshift interval (2.5 < z < 3.5) that allowed us to observe the Mg ii and Hβ emission lines in the adjacent near-infrared (NIR) band. We collected NIR spectra of the two samples using the Telescopio Nazionale Galileo (TNG, Canary Islands). By using relations known in the literature, we estimated the black-hole mass, the broad-line region radius, and the Eddington ratio of our objects and compared the two samples. Results: We found no statistically significant differences from comparing the distributions of the cited physical quantities. This indicates that they have similar geometries, accretion rates, and central black-hole masses, regardless of whether the radio-emitting jet is present or not. Conclusions: These results show that the central engine of BAL QSOs has the same physical properties with and without a radio jet. The reasons for the rarity of RL BAL QSOs must reside in different environmental or evolutionary variables. Figure 3 is available in electronic form at http://www.aanda.org

  20. Quasar broad absorption line variability measurements using reconstructions of unabsorbed spectra

    NASA Astrophysics Data System (ADS)

    Wildy, C.; Goad, M. R.; Allen, J. T.

    2014-01-01

    We present a two-epoch Sloan Digital Sky Survey and Gemini/GMOS+William Herschel Telescope/ISIS variability study of 50 broad absorption line (BAL) quasars of redshift range 1.9 < z < 4.2, containing 38 Si IV and 59 C IV BALs and spanning rest-frame time intervals of ≈10 months to 3.7 years. We find that 35/50 quasars exhibit one or more variable BALs, with 58 per cent of Si IV and 46 per cent of C IV BALs showing variability across the entire sample. On average, Si IV BALs show larger fractional change in BAL pseudo-equivalent width than C IV BALs, as referenced to an unabsorbed continuum+emission line spectrum constructed using non-negative matrix factorization. No correlation is found between BAL variability and quasar luminosity, suggesting that ionizing continuum changes do not play a significant role in BAL variability (assuming the gas is in photoionization equilibrium with the ionizing continuum). A subset of 14 quasars have one variable BAL from each of Si IV and C IV with significant overlap in velocity space and for which variations are in the same sense (strengthening or weakening) and which appear to be correlated (98 per cent confidence). We find examples of both appearing and disappearing BALs in weaker/shallower lines with disappearance rates of 2.3 per cent for C IV and 5.3 per cent for Si IV, suggesting average lifetimes of 142 and 43 years, respectively. We identify five objects in which the BAL is coincident with the broad emission line, but appears to cover only the continuum source. Assuming a clumpy inhomogeneous absorber model and a typical size for the continuum source, we infer a maximum cloud radius of 1013 to 1014 cm, assuming Eddington limited accretion.

  1. Intermediate-field two-photon absorption enhancement by shaped femtosecond pulses: Tolerance to phase deviation from perfect antisymmetry

    SciTech Connect

    Chuntonov, Lev; Rybak, Leonid; Gandman, Andrey; Amitay, Zohar

    2010-04-15

    We study in detail the coherent interference mechanism leading to the intermediate-field two-photon absorption enhancement recently found for shaped femtosecond pulses with spectral phases that are antisymmetric around one-half of the transition frequency. We particularly investigate the tolerance of the phenomenon to the phase deviation from perfect antisymmetry. We theoretically and experimentally find that this tolerance increases as the field strength increases. For the present Na excitation, the enhancement occurs even when {approx}30% of the phase pattern is not antisymmetric. Our findings are of particular importance for multichannel coherent control scenarios.

  2. LINE: a code which simulates spectral line shapes for fusion reaction products generated by various speed distributions

    SciTech Connect

    Slaughter, D.

    1985-03-01

    A computer code is described which estimates the energy spectrum or ''line-shape'' for the charged particles and ..gamma..-rays produced by the fusion of low-z ions in a hot plasma. The simulation has several ''built-in'' ion velocity distributions characteristic of heated plasmas and it also accepts arbitrary speed and angular distributions although they must all be symmetric about the z-axis. An energy spectrum of one of the reaction products (ion, neutron, or ..gamma..-ray) is calculated at one angle with respect to the symmetry axis. The results are shown in tabular form, they are plotted graphically, and the moments of the spectrum to order ten are calculated both with respect to the origin and with respect to the mean.

  3. Spherically shaped micron-size particle-reinforced PMMA and PC composites for improving energy absorption capability

    NASA Astrophysics Data System (ADS)

    Kim, Hyung-ick; Kang, Eung-Chun; Jang, Jae-Soon; Suhr, Jonghwan

    2011-04-01

    The focus of this study was to experimentally investigate spherically shaped micron-size particles reinforced polymethyl methacrylate (PMMA) and polycarbonate (PC) polymer composites for improving energy absorbing capabilities such as toughness and low-velocity impact resistance. In this study, a solution mixing method was developed to fabricate both PMMA and PC polymer composites with spherically shaped micron-size polyamide- nylon 6 (PA6) particles inclusions. The morphology of the fracture surfaces of polymer composites was examined by using optical microscopy and scanning electron microscopy. Strain-rate dependent response of both PMMA and PC polymer composites was investigated by characterizing tensile and flexural properties. Low-velocity penetration testing was performed for both polymer composites and the key results observed for energy absorption capabilities are discussed in this study.

  4. Time-dependent excitation and ionization modelling of absorption-line variability due to GRB 080310

    NASA Astrophysics Data System (ADS)

    Vreeswijk, P. M.; Ledoux, C.; Raassen, A. J. J.; Smette, A.; De Cia, A.; Woźniak, P. R.; Fox, A. J.; Vestrand, W. T.; Jakobsson, P.

    2013-01-01

    We model the time-variable absorption of Fe II, Fe III, Si II, C II and Cr II detected in Ultraviolet and Visual Echelle Spectrograph (UVES) spectra of gamma-ray burst (GRB) 080310, with the afterglow radiation exciting and ionizing the interstellar medium in the host galaxy at a redshift of z = 2.42743. To estimate the rest-frame afterglow brightness as a function of time, we use a combination of the optical VRI photometry obtained by the RAPTOR-T telescope array, which is presented in this paper, and Swift's X-Ray Telescope (XRT) observations. Excitation alone, which has been successfully applied for a handful of other GRBs, fails to describe the observed column density evolution in the case of GRB 080310. Inclusion of ionization is required to explain the column density decrease of all observed Fe II levels (including the ground state 6D9/2) and increase of the Fe III 7S3 level. The large population of ions in this latter level (up to 10% of all Fe III) can only be explained through ionization of Fe II, as a large fraction of the ionized Fe II ions (we calculate 31% using the Flexible Atomic and Cowan codes) initially populate the 7S3 level of Fe III rather than the ground state. This channel for producing a significant Fe III 7S3 level population may be relevant for other objects in which absorption lines from this level, the UV34 triplet, are observed, such as broad absorption line (BAL) quasars and η Carinae. This provides conclusive evidence for time-variable ionization in the circumburst medium, which to date has not been convincingly detected. However, the best-fit distance of the neutral absorbing cloud to the GRB is 200-400 pc, i.e. similar to GRB-absorber distance estimates for GRBs without any evidence for ionization. We find that the presence of time-varying ionization in GRB 080310 is likely due to a combination of the super-solar iron abundance ([Fe/H] = +0.2) and the low H I column density (log N(H i) = 18.7) in the host of GRB 080310. Finally

  5. Catalog of Narrow Mg II Absorption Lines in the Baryon Oscillation Spectroscopic Survey

    NASA Astrophysics Data System (ADS)

    Chen, Zhi-Fu; Gu, Qiu-Sheng; Chen, Yan-Mei

    2015-12-01

    Using the Data Release 9 Quasar spectra from the Baryonic Oscillation Spectroscopic Survey, which does not include quasar spectra from the Sloan Digital Sky Survey Data Release 7, we detect narrow Mg ii λλ2796, 2803 absorption doublets in the spectral data redward of 1250 Å (quasar rest frame) until the red wing of the Mg ii λ2800 emission line. Our survey is limited to quasar spectra with a median signal-to-noise ratio < {{S}}/{{N}}> ≥slant 4 pixel-1 in the surveyed spectral region, resulting in a sample that contains 43,260 quasars. We have detected a total of 18,598 Mg ii absorption doublets with 0.2933 ≤ zabs ≤ 2.6529. About 75% of absorbers have an equivalent width at rest frame of {W}rλ 2796≥slant 1 \\mathringA . About 75% of absorbers have doublet ratios ({DR}={W}rλ 2796/{W}rλ 2803) in the range of 1 ≤ DR ≤ 2, and about 3.2% lie outside the range of 1 - σDR ≤ DR ≤ 2 + σDR. We characterize the detection false positives/negatives by the frequency of detected Mg ii absorption doublets in the limits of the S/N of the spectral data. The S/N = 4.5 limit is assigned a completeness fraction of 53% and tends to be complete when the S/N is greater than 4.5. The redshift number densities of all of the detected Mg ii absorbers moderately increase from z ≈ 0.4 to z ≈ 1.5, which parallels the evolution of the cosmic star formation rate density. Limiting our investigation to those quasars whose emission redshift can be determined from narrow emission lines, the relative velocities (β) of Mg ii absorbers have a complex distribution which probably consists of three classes of Mg ii absorbers: (1) cosmologically intervening absorbers; (2) environmental absorbers that reside within the quasar host galaxies or galaxy clusters; (3) quasar outflow absorbers. After subtracting contributions from cosmologically intervening absorbers and environmental absorbers, the β distribution of the Mg iiabsorbers might mainly be contributed by the quasar outflow

  6. A limit of validity of the straight line hypothesis in shaped charge jet formation modeling

    SciTech Connect

    Curtis, J.P.; Kelly, R.J.

    1997-07-01

    A particular problem in the field of shaped charge jet formation modeling concerns the collision of two fluid streams of different widths and speeds. It is commonly assumed that the flow is incompressible, and that the velocity of the fluid in any of the streams is constant across and normal to its cross section. Then the well-known classically indeterminate mathematical problem arises. In the shaped charge context the indeterminacy of the problem has been addressed by making three assumptions about the flow. Several models have assumed that conservation of kinetic energy holds, and have applied Bernoulli{close_quote}s Law to equate the speeds of the jet and slug in a frame moving with the collision point. One natural choice for the third and final assumption is that the jet and slug lie in a straight line when viewed in this frame, the so-called straight line hypothesis. In this article the inclination of this line relative to the bisector of the two colliding streams is expressed as a function of the parameters of the incoming streams. It is shown that the angle between the jet and the incoming stream supplying momentum at the greater rate increases with the size of the angle between the incoming streams until it reaches a maximum value. It then decreases to zero. It is known that the straight line hypothesis is a good approximation for low values of the angle between the incoming streams, but becomes increasingly inaccurate as this angle increases. The above maximum appears to correspond to the limit of validity of the straight line hypothesis. Recommendations for the utilization of the existing formation models to achieve best accuracy are made, based on this limit.

  7. Metal-line absorption at Z(sub abs) approximately Z(sub em) from associated galaxies

    NASA Technical Reports Server (NTRS)

    Ellingson, E.; Yee, H. K. C.; Bechtold, Jill; Dobrzycki, Adam

    1994-01-01

    For a preliminary study of whether C IV absorption at Z(sub abs) approximately Z(sub em) is related to associated galaxy companions, we have collected data from a sample of 10 quasars with 0.15 less than z less than 0.65 for which high-resolution optical and UV spectroscopy is available from the literature, and for which we have deep optical images and limited spectroscopy. We also present new optical spectra for two of our samples. Four of these quasars have associated C IV absorption systems. In thes four fields, there are eight galaxies with M(sub r) less than -19.0 mag within 35 kpc of the quasar (projected distance, assuming they are at the quasar redshift), which may be candidates for the associated C IV absorption. This observed density of galaxies near quasars with associated C IV absorption is significantly greater than that for a control sample of quasars chosen from the literature. This result suggests that galaxies near the quasar line of sight may be linked with associated C IV absorption. None of these quasars show associated Mg II absorption, despite the presence of galaxies very near the line of sight, suggesting a Mg II 'proximity effect,' where ionizing flux from the quasar destroys the Mg(+) from at least the outer parts of the galaxies. Three quasars are located in rich galaxy clusters, but none of these quasars are found to have associated C IV absorption. This suggests that galaxies in rich clusters associated with quasars are less likely to be metal-line absorbers. It is plausible that the extended galaxy halos which may be responsible for the absorptions are stripped from galaxies in these dense environments. While it seems that at Z approximately 0.6 rich clusters do not cause them, associated C IV absorption systems at higher redshift may be explained by associated clusters if there has been evolution in the properties of galaxy halos in dense environments.

  8. Bubble shape and breakage events in a vertical pipe at the boiler flow line

    NASA Astrophysics Data System (ADS)

    Fsadni, Andrew; Ge, Yunting

    2014-03-01

    The theoretical and experimental aspects concerning the typical bubble shape at the flow line of a standard domestic central heating system are investigated. This is done in support of the on-going research on two-phase flows in domestic central heating systems. Bubble nucleation and detachment at the primary heat exchanger wall of a domestic central heating boiler results in a bubbly two-phase flow in the system pipe work. Bubbly flow results in undesired cold spots at higher points in the system, consequently diminishing system performance. An experimental analysis was done on the bubble shape at the exit of the boiler through the application of photographic techniques. The results are presented in terms of the measured bubble aspect ratios at some principal system operating conditions. The dimensionless Eotvos and bubble Reynolds number were calculated and tabulated with the measured mean diameters. The data was subsequently correlated to the bubble shape regime diagram. Results suggest that most bubbles are quasi-spherical in shape with a noticeable elongation at lower bulk fluid Reynolds numbers.

  9. Gravitationally redshifted absorption lines in the X-ray burst spectra of a neutron star.

    PubMed

    Cottam, J; Paerels, F; Mendez, M

    2002-11-01

    The fundamental properties of neutron stars provide a direct test of the equation of state of cold nuclear matter, a relationship between pressure and density that is determined by the physics of the strong interactions between the particles that constitute the star. The most straightforward method of determining these properties is by measuring the gravitational redshift of spectral lines produced in the neutron star photosphere. The equation of state implies a mass-radius relation, while a measurement of the gravitational redshift at the surface of a neutron star provides a direct constraint on the mass-to-radius ratio. Here we report the discovery of significant absorption lines in the spectra of 28 bursts of the low-mass X-ray binary EXO0748-676. We identify the most significant features with the Fe XXVI and XXV n = 2-3 and O VIII n = 1-2 transitions, all with a redshift of z = 0.35, identical within small uncertainties for the respective transitions. For an astrophysically plausible range of masses (M approximately 1.3-2.0 solar masses; refs 2-5), this value is completely consistent with models of neutron stars composed of normal nuclear matter, while it excludes some models in which the neutron stars are made of more exotic matter. PMID:12422210

  10. AN INFRARED EXCESS IDENTIFIED IN RADIO-LOUD BROAD ABSORPTION LINE QUASARS

    SciTech Connect

    DiPompeo, M. A.; Runnoe, J. C.; Brotherton, M. S.; Myers, A. D.

    2013-01-10

    If broad absorption line (BAL) quasars represent a high-covering-fraction evolutionary state (even if this is not the sole factor governing the presence of BALs), it is expected that they should show an excess of mid-infrared radiation compared to normal quasars. Some previous studies have suggested that this is not the case. We perform the first analysis of the IR properties of radio-loud BAL quasars, using IR data from WISE and optical (rest-frame ultraviolet) data from SDSS, and compare the BAL quasar sample with a well-matched sample of unabsorbed quasars. We find a statistically significant excess in the mid- to near-infrared luminosities of BAL quasars, particularly at rest-frame wavelengths of 1.5 and 4 {mu}m. Our sample was previously used to show that BALs are observed along many lines of sight toward quasars, but with an overabundance of more edge-on sources, suggesting that orientation factors into the appearance of BALs. The evidence here-of a difference in IR luminosities between BAL quasars and unabsorbed quasars-can be ascribed to evolution. This suggests that a merging of the current BAL paradigms is needed to fully describe the class.

  11. Search for infrared absorption lines of atmospheric chlorine monoxide (ClO)

    NASA Technical Reports Server (NTRS)

    Rinsland, Curtis P.; Goldman, Aaron

    1992-01-01

    A search for features of the ClO (1-0) vibration-rotation band has been conducted based on a 5000 signal-to-rms noise ratio IR spectrum derived by coadding 39 high-quality 0.0053/cm resolution solar spectra recorded with the McMath Fourier transform spectrometer on Kitt Peak. Evidence for absorption has been found at the locations of several of the stronger ClO P-branch lines with minimal interference. Detailed results are presented for the P(8.5) and P(7.5) 2Pi3/2-2Pi3/2 lines of Cl-35O at 833.2974 and 834.6249/cm, respectively. If ClO is present in the stratosphere at the concentrations indicated by other methods, our analysis indicates that modest improvements in signal-to-noise ratio and spectral resolution would permit a definitive detection of ClO in IR ground-based spectra.

  12. 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.

  13. C IV Broad Absorption Line Acceleration in Sloan Digital Sky Survey Quasars

    NASA Astrophysics Data System (ADS)

    Grier, C. J.; Brandt, W. N.; Hall, P. B.; Trump, J. R.; Filiz Ak, N.; Anderson, S. F.; Green, Paul J.; Schneider, D. P.; Sun, M.; Vivek, M.; Beatty, T. G.; Brownstein, Joel R.; Roman-Lopes, Alexandre

    2016-06-01

    We present results from the largest systematic investigation of broad absorption line (BAL) acceleration to date. We use spectra of 140 quasars from three Sloan Digital Sky Survey programs to search for global velocity offsets in BALs over timescales of ≈2.5–5.5 years in the quasar rest frame. We carefully select acceleration candidates by requiring monolithic velocity shifts over the entire BAL trough, avoiding BALs with velocity shifts that might be caused by profile variability. The C iv BALs of two quasars show velocity shifts consistent with the expected signatures of BAL acceleration, and the BAL of one quasar shows a velocity-shift signature of deceleration. In our two acceleration candidates, we see evidence that the magnitude of the acceleration is not constant over time; the magnitudes of the change in acceleration for both acceleration candidates are difficult to produce with a standard disk-wind model or via geometric projection effects. We measure upper limits to acceleration and deceleration for 76 additional BAL troughs and find that the majority of BALs are stable to within about 3% of their mean velocities. The lack of widespread acceleration/deceleration could indicate that the gas producing most BALs is located at large radii from the central black hole and/or is not currently strongly interacting with ambient material within the host galaxy along our line of sight.

  14. BROAD ABSORPTION LINE DISAPPEARANCE ON MULTI-YEAR TIMESCALES IN A LARGE QUASAR SAMPLE

    SciTech Connect

    Filiz Ak, N.; Brandt, W. N.; Schneider, D. P.; Hall, P. B.; Anderson, S. F.; Gibson, R. R.; Lundgren, B. F.; Myers, A. D.; Petitjean, P.; Ross, Nicholas P.; Shen Yue; York, D. G.; Bizyaev, D.; Brinkmann, J.; Malanushenko, E.; Oravetz, D. J.; Pan, K.; Simmons, A. E.; Weaver, B. A.

    2012-10-01

    We present 21 examples of C IV broad absorption line (BAL) trough disappearance in 19 quasars selected from systematic multi-epoch observations of 582 bright BAL quasars (1.9 < z < 4.5) by the Sloan Digital Sky Survey-I/II (SDSS-I/II) and SDSS-III. The observations span 1.1-3.9 yr rest-frame timescales, longer than have been sampled in many previous BAL variability studies. On these timescales, Almost-Equal-To 2.3% of C IV BAL troughs disappear and Almost-Equal-To 3.3% of BAL quasars show a disappearing trough. These observed frequencies suggest that many C IV BAL absorbers spend on average at most a century along our line of sight to their quasar. Ten of the 19 BAL quasars showing C IV BAL disappearance have apparently transformed from BAL to non-BAL quasars; these are the first reported examples of such transformations. The BAL troughs that disappear tend to be those with small-to-moderate equivalent widths, relatively shallow depths, and high outflow velocities. Other non-disappearing C IV BALs in those nine objects having multiple troughs tend to weaken when one of them disappears, indicating a connection between the disappearing and non-disappearing troughs, even for velocity separations as large as 10,000-15,000 km s{sup -1}. We discuss possible origins of this connection including disk-wind rotation and changes in shielding gas.

  15. A line scanned light-sheet microscope with phase shaped self-reconstructing beams.

    PubMed

    Fahrbach, Florian O; Rohrbach, Alexander

    2010-11-01

    We recently demonstrated that Microscopy with Self-Reconstructing Beams (MISERB) increases both image quality and penetration depth of illumination beams in strongly scattering media. Based on the concept of line scanned light-sheet microscopy, we present an add-on module to a standard inverted microscope using a scanned beam that is shaped in phase and amplitude by a spatial light modulator. We explain technical details of the setup as well as of the holograms for the creation, positioning and scaling of static light-sheets, Gaussian beams and Bessel beams. The comparison of images from identical sample areas illuminated by different beams allows a precise assessment of the interconnection between beam shape and image quality. The superior propagation ability of Bessel beams through inhomogeneous media is demonstrated by measurements on various scattering media. PMID:21164769

  16. Protein dynamics in the solid state from 2H NMR line shape analysis: a consistent perspective.

    PubMed

    Meirovitch, Eva; Liang, Zhichun; Freed, Jack H

    2015-02-19

    Deuterium line shape analysis of CD3 groups has emerged as a particularly useful tool for studying microsecond-millisecond protein motions in the solid state. The models devised so far consist of several independently conceived simple jump-type motions. They are comprised of physical quantities encoded in their simplest form; improvements are only possible by adding yet another simple motion, thereby changing the model. The various treatments developed are case-specific; hence comparison among the different systems is not possible. Here we develop a new methodology for (2)H NMR line shape analysis free of these limitations. It is based on the microscopic-order-macroscopic-disorder (MOMD) approach. In MOMD motions are described by diffusion tensors, spatial restrictions by potentials/ordering tensors, and geometric features by relative tensor orientations. Jump-type motions are recovered in the limit of large orientational potentials. Model improvement is accomplished by monitoring the magnitude, symmetry, and orientation of the various tensors. The generality of MOMD makes possible comparison among different scenarios. CD3 line shapes from the Chicken Villin Headpiece Subdomain and the Streptomyces Subtilisin Inhibitor are used as experimental examples. All of these spectra are reproduced by using rhombic local potentials constrained for simplicity to be given by the L = 2 spherical harmonics, and by axial diffusion tensors. Potential strength and rhombicity are found to be ca. 2-3 k(B)T. The diffusion tensor is tilted at 120° from the C-CD3 axis. The perpendicular (parallel) correlation times for local motion are 0.1-1.0 ms (3.3-30 μs). Activation energies in the 1.1-8.0 kcal/mol range are estimated. Future prospects include extension to the (2)H relaxation limit, application to the (15)N and (13)C NMR nuclei, and accounting for collective motions and anisotropic media. PMID:25594631

  17. Influence of organic ligands on the line shape of the Kondo resonance

    NASA Astrophysics Data System (ADS)

    Meyer, Jörg; Ohmann, Robin; Nickel, Anja; Toher, Cormac; Gresser, Roland; Leo, Karl; Ryndyk, Dmitry A.; Moresco, Francesca; Cuniberti, Gianaurelio

    2016-04-01

    The Kondo resonance of an organic molecule containing a Co atom is investigated by scanning tunneling spectroscopy and ab initio calculations on a Ag(100) surface. High resolution mapping of the line shape shows evidence of local nonradially symmetric variations of the Fano factor and the Kondo amplitude, revealing a strong influence of the molecular ligand. We show that the decay of the amplitude of the Kondo resonance is determined by the spatial distribution of the ligand's orbital being hybridized with the singly occupied Co dz2 orbital, forming together the singly occupied Kondo-active orbital.

  18. High-resolution spectroscopy of V854 Cen in decline - absorption and emission lines of C2 molecules

    NASA Astrophysics Data System (ADS)

    Kameswara Rao, N.; Lambert, David L.

    2000-04-01

    High-resolution optical spectra of the R Coronae Borealis (RCB) star V854 Centauri in the early stages of a decline show, in addition to the features reported for other RCBs in decline, narrow absorption lines from the C2 Phillips system. The low rotational temperature, Trot=1150K, of the C2 ground electronic state suggests the cold gas is associated with the developing shroud of carbon dust. These absorption lines were not seen at a fainter magnitude on the rise from minimum light, nor at maximum light. This is the first detection of cold gas around an RCB star.

  19. Total Absorption Spectroscopy Study of (92)Rb Decay: A Major Contributor to Reactor Antineutrino Spectrum Shape.

    PubMed

    Zakari-Issoufou, A-A; Fallot, M; Porta, A; Algora, A; Tain, J L; Valencia, E; Rice, S; Bui, V M; Cormon, S; Estienne, M; Agramunt, J; Äystö, J; Bowry, M; Briz, J A; Caballero-Folch, R; Cano-Ott, D; Cucoanes, A; Elomaa, V-V; Eronen, T; Estévez, E; Farrelly, G F; Garcia, A R; Gelletly, W; Gomez-Hornillos, M B; Gorlychev, V; Hakala, J; Jokinen, A; Jordan, M D; Kankainen, A; Karvonen, P; Kolhinen, V S; Kondev, F G; Martinez, T; Mendoza, E; Molina, F; Moore, I; Perez-Cerdán, A B; Podolyák, Zs; Penttilä, H; Regan, P H; Reponen, M; Rissanen, J; Rubio, B; Shiba, T; Sonzogni, A A; Weber, C

    2015-09-01

    The antineutrino spectra measured in recent experiments at reactors are inconsistent with calculations based on the conversion of integral beta spectra recorded at the ILL reactor. (92)Rb makes the dominant contribution to the reactor antineutrino spectrum in the 5-8 MeV range but its decay properties are in question. We have studied (92)Rb decay with total absorption spectroscopy. Previously unobserved beta feeding was seen in the 4.5-5.5 region and the GS to GS feeding was found to be 87.5(25)%. The impact on the reactor antineutrino spectra calculated with the summation method is shown and discussed. PMID:26382674

  20. CO{sub 2} isolated line shapes by classical molecular dynamics simulations: Influence of the intermolecular potential and comparison with new measurements

    SciTech Connect

    Larcher, G.; Tran, H. Schwell, M.; Chelin, P.; Landsheere, X.; Hartmann, J.-M.; Hu, S.-M.

    2014-02-28

    Room temperature absorption spectra of various transitions of pure CO{sub 2} have been measured in a broad pressure range using a tunable diode-laser and a cavity ring-down spectrometer, respectively, in the 1.6 μm and 0.8 μm regions. Their spectral shapes have been calculated by requantized classical molecular dynamics simulations. From the time-dependent auto-correlation function of the molecular dipole, including Doppler and collisional effects, spectral shapes are directly computed without the use of any adjusted parameter. Analysis of the spectra calculated using three different anisotropic intermolecular potentials shows that the shapes of pure CO{sub 2} lines, in terms of both the Lorentz widths and non-Voigt effects, slightly depend on the used potential. Comparisons between these ab initio calculations and the measured spectra show satisfactory agreement for all considered transitions (from J = 6 to J = 46). They also show that non-Voigt effects on the shape of CO{sub 2} transitions are almost independent of the rotational quantum number of the considered lines.

  1. Variable Reddening and Broad Absorption Lines in the Narrow-line Seyfert 1 Galaxy WPVS 007: An Origin in the Torus

    NASA Astrophysics Data System (ADS)

    Leighly, Karen M.; Cooper, Erin; Grupe, Dirk; Terndrup, Donald M.; Komossa, S.

    2015-08-01

    We report the discovery of an occultation event in the low-luminosity narrow-line Seyfert 1 galaxy WPVS 007 in 2015 February and March. In concert with longer timescale variability, these observations place strong constraints on the nature and location of the absorbing material. Swift monitoring has revealed a secular decrease since ∼2010 accompanied by flattening of the optical and UV photometry that suggests variable reddening. Analysis of four Hubble Space Telescope COS observations since 2010, including a Director’s Discretionary time observation during the occultation, shows that the broad-absorption-line velocity offset and the C iv emission-line width both decrease as the reddening increases. The occultation dynamical timescale, the BAL variability dynamical timescale, and the density of the BAL gas show that both the reddening material and the broad-absorption-line gas are consistent with an origin in the torus. These observations can be explained by a scenario in which the torus is clumpy with variable scale height, and the BAL gas is blown from the torus material like spray from the crest of a wave. As the obscuring material passes into our line of sight, we alternately see high-velocity broad absorption lines and a clear view to the central engine, or low-velocity broad absorption lines and strong reddening. WPVS 007 has a small black hole mass, and correspondingly short timescales, and so we may be observing behavior that is common in BALQSOs, but is not typically observable. Based on observations made with the NASA/ESA Hubble Space Telescope, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with programs 11733, 13015, and 14058.

  2. Noodles and stars allow a precise and efficient calculation of the Z-line shape and the polarization asymmetry

    NASA Astrophysics Data System (ADS)

    Jung-Choon Im, Carl

    1990-03-01

    We give a pedagogical introduction to the star functions and the Noodle method. The Z-line shape and the polarization asymmetry at SLC/LEP can be evaluated elegantly and efficiently using the star functions and the Noodle method.

  3. Dependence of the Broad Absorption Line Quasar Fraction on Radio Luminosity

    NASA Astrophysics Data System (ADS)

    Shankar, Francesco; Dai, Xinyu; Sivakoff, Gregory R.

    2008-11-01

    We find that the fraction of classical broad absorption line quasars (BALQSOs) among the FIRST radio sources in the Sloan Data Release 3, is 20.5+ 7.3-5.9% at the faintest radio powers detected (L1.4 GHz ~ 1032 erg s-1), and rapidly drops to lesssim8% at L1.4 GHz ~ 3 × 1033 erg s-1. Similarly, adopting the broader absorption index (AI) definition of Trump et al., we find the fraction of radio BALQSOs to be 44+ 8.1-7.8%, reducing to 23.1+ 7.3-6.1% at high luminosities. While the high fraction at low radio power is consistent with the recent near-IR estimates by Dai et al., the lower fraction at high radio powers is intriguing and confirms previous claims based on smaller samples. The trend is independent of the redshift range, the optical and radio flux selection limits, or the exact definition of a radio match. We also find that at fixed optical magnitude, the highest bins of radio luminosity are preferentially populated by non-BALQSOs, consistent with the overall trend. We do find, however, that those quasars identified as AI-BALQSOs but not under the classical definition do not show a significant drop in their fraction as a function of radio power, further supporting independent claims that these sources, characterized by lower equivalent width, may represent an independent class from the classical BALQSOs. We find the balnicity index, a measure of the absorption trough in BALQSOs, and the mean maximum wind velocity to be roughly constant at all radio powers. We discuss several plausible physical models which may explain the observed fast drop in the fraction of the classical BALQSOs with increasing radio power, although none is entirely satisfactory. A strictly evolutionary model for the BALQSO and radio emission phases requires a strong fine-tuning to work, while a simple geometric model, although still not capable of explaining polar BALQSOs and the paucity of FRII BALQSOs, is statistically successful in matching the data if part of the apparent radio

  4. First detection of ionized helium absorption lines in infrared K band spectra of O-type stars

    NASA Technical Reports Server (NTRS)

    Conti, Peter S.; Block, David L.; Geballe, T. R.; Hanson, Margaret M.

    1993-01-01

    We have obtained high SNR, moderate-resolution K band spectra of two early O-type main sequence stars, HD 46150 O5 V, and HD 46223 O4 V, in the Rosette Nebula. We report the detection, for the first time, of the 2.189 micron He II line in O-type stars. Also detected is the 2.1661 micron Br-gamma line in absorption. The 2.058 micron He I line appears to be present in absorption in both stars, although its appearance at our resolution is complicated by atmospheric features. These three lines can form the basis for a spectral classification system for hot stars in the K band that may be used at infrared wavelengths to elucidate the nature of those luminous stars in otherwise obscured H II and giant H II regions.

  5. Hubble Space Telescope Faint Object Spectrograph and ground-based observations of the broad absorption line quasar 0226-1024

    NASA Technical Reports Server (NTRS)

    Korista, Kirk T.; Weymann, Ray J.; Morris, Simon L.; Kopko, Michael, Jr.; Turnshek, David A.; Hartig, George F.; Foltz, Craig B.; Burbidge, E. M.; Junkkarinen, Vesa T.

    1992-01-01

    Faint Object Spectrograph data from the Hubble Space Telescope of the broad absorption line quasar 0226-1024 have revealed the presence of 8-10 absorbing ions between 680 and 1000 A (restframe): C III, N III, N IV, O III, O IV, O VI, S V, S VI, possibly Ne VIII, and possibly O V* arising from a metastable excited state. We also present ground-based optical observations of the broad line troughs for the following ions: H I, C IV, N V, Si IV, and possibly Fe III, S IV, P V, and C III* (also arising from a metastable excited state). The results of this fit are used to estimate the absorbing ionic column densities. There is evidence that the broad absorption line clouds are optically thick and either do not completely cover the continuum source or narrow unresolved lines are present.

  6. Evidence for two spatially separated UV continuum emitting regions in the Cloverleaf broad absorption line quasar

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    Testing the standard Shakura-Sunyaev model of accretion is a challenging task because the central region of quasars where accretion takes place is unresolved with telescopes. The analysis of microlensing in gravitationally lensed quasars is one of the few techniques that can test this model, yielding to the measurement of the size and of temperature profile of the accretion disc. We present spectroscopic observations of the gravitationally lensed broad absorption line quasar H1413+117, which reveal partial microlensing of the continuum emission that appears to originate from two separated regions: a microlensed region, corresponding the compact accretion disc; and a non-microlensed region, more extended and contributing to at least 30% of the total UV-continuum flux. Because this extended continuum is occulted by the broad absorption line clouds, it is not associated with the host galaxy, but rather with light scattered in the neighbourhood of the central engine. We measure the amplitude of microlensing of the compact continuum over the rest-frame wavelength range 1000-7000 Å. Following a Bayesian scheme, we confront our measurements to microlensing simulations of an accretion disc with a temperature varying as T ∝ R-1/ν. We find a most likely source half-light radius of R1/2 = 0.61 × 1016cm (i.e., 0.002 pc) at 0.18 μm, and a most-likely index of ν = 0.4. The standard disc (ν = 4/3) model is not ruled out by our data, and is found within the 95% confidence interval associated with our measurements. We demonstrate that, for H1413+117, the existence of an extended continuum in addition to the disc emission only has a small impact on the inferred disc parameters, and is unlikely to solve the tension between the microlensing source size and standard disc sizes, as previously reported in the literature. Based on observations made with ESO Telescopes at the Paranal Observatory (Chile). ESO program ID: 386.B-0337.Appendices A and B are available in electronic form

  7. Constraining the geometry, size scale and physical conditions of outflowing broad absorption line regions in quasars

    NASA Astrophysics Data System (ADS)

    Woo, Sui Chi

    Quasars are known for generating luminosities of up to 1047 erg s--1 in volumes of scales smaller than 2 x 10 15 cm. The optical/UV continuum emission is generally believed to arise from a rotating accretion disk (AD) surrounding a supermassive black hole (SMBH) of ˜ 108 M⊙ . Such emission can be calculated by treating the AD as a multi-temperature blackbody. While the continuum emitting region is well defined, the properties, location and kinematics of the broad emission line regions (BELRs) and broad absorption line regions (BALRs) remain unclear. On one hand, the reverberation mapping technique can give constraints on the location of the BELRs, but not the kinematics. On the other hand, the line-of-sight kinematics of the BALRs is directly observable, but their locations are not well constrained, resulting in a large range of inferred distances, from 0.01 pc to tens of kpc. Therefore, I combined observational results to investigate the geometry, size, and physical conditions of the BELRs and BALRs. I verified that the Lyalpha and CIV BELRs are located at a similar distance. Using these findings, I was able to constrain the size of the Lyalpha BELR and place a lower limit on the size of the N V BALR. I built an empirical model with the optical/UV continuum emission from the AD, the BELR from the chromosphere of the AD, and the outflowing BALR. In the continuum region, I found that over 95 percent of the total flux comes from the region at ~ 125rg, where rg is the gravitational radius of the SMBH. For the BELRs, I computed a disk-wind model with relativistic effects to explain the often-observed single-peaked BEL profiles. However, I show that such a model cannot explain the observed blue asymmetries in the high-ionization BELs or their blueshifted peaks relative to low-ionization BELs. Using results on time variability of BALR gas, and assuming the variability is caused by the gas moving perpendicular across the line-of-sight over a time scale of about a year

  8. ac Stark shifts for cesium and their effect on ionization line shapes

    SciTech Connect

    Pindzola, M.S.; Glasser, A.H.; Payne, M.G.

    1984-10-01

    The influence of ac Stark shifts on the three-photon ionization of cesium in a moderate-intensity laser beam is investigated. The ionization process involves a two-photon resonance with the 8d fine-structure levels. The work consists of two related parts. In the first part, atomic parameters, such as the two-photon Rabi rate and the ac Stark shift, are calculated in the nonrelativistic Hartree-Fock approximation. In the second part, the atomic parameters thus obtained are used as coefficients in a system of coupled differential equations representing the time evolution of the density matrix. Ionization line shapes are generated for a transform-limited pulsed laser of moderate intensity with a single-mode transverse structure. As the time history of the intensity profile is varied from square to smooth, the ionization line shape becomes asymmetric due to the time dependence of the ac Stark shift. The effects of varying the spatial intensity distribution of the laser light to

  9. Understanding the symmetric line shape in the 17O MAS spectra for hexagonal ice

    NASA Astrophysics Data System (ADS)

    Yamada, Kazuhiko; Oki, Shinobu; Deguchi, Kenzo; Shimizu, Tadashi

    2016-06-01

    Solid-state 17O Magic-Angle Spinning (MAS) nuclear magnetic resonance (NMR) spectra of 17O-enriched hexagonal ice, [17O]-Ih, between 173 and 253 K were presented. Marked changes in the line shape were clearly observed, indicating water molecular reorientation in the crystal structure. At 173 K, molecular motions were considered to be frozen and analysis of the 1D MAS spectrum yielded the following parameters: quadrupole coupling constant (CQ) = 6.6 ± 0.2 MHz and asymmetry parameter (ηQ) = 0.95 ± 0.05. At 232 K and above, contrary to the conventional explanation, pseudo-symmetric line shapes appeared in the 17O MAS NMR spectra arising from the contribution of second-order quadrupole interactions. As a chemical exchange model to describe these isotropic 17O MAS NMR spectra, a modified Ratcliffe model, which consider the effects of proton disorder, was proposed, and the resulting theoretical spectra could well reproduce the experimental spectra.

  10. On-line measurement of ski-jumper trajectory: combining stereo vision and shape description

    NASA Astrophysics Data System (ADS)

    Nunner, T.; Sidla, O.; Paar, G.; Nauschnegg, B.

    2010-01-01

    Ski jumping has continuously raised major public interest since the early 70s of the last century, mainly in Europe and Japan. The sport undergoes high-level analysis and development, among others, based on biodynamic measurements during the take-off and flight phase of the jumper. We report on a vision-based solution for such measurements that provides a full 3D trajectory of unique points on the jumper's shape. During the jump synchronized stereo images are taken by a calibrated camera system in video rate. Using methods stemming from video surveillance, the jumper is detected and localized in the individual stereo images, and learning-based deformable shape analysis identifies the jumper's silhouette. The 3D reconstruction of the trajectory takes place on standard stereo forward intersection of distinct shape points, such as helmet top or heel. In the reported study, the measurements are being verified by an independent GPS measurement mounted on top of the Jumper's helmet, synchronized to the timing of camera exposures. Preliminary estimations report an accuracy of +/-20 cm in 30 Hz imaging frequency within 40m trajectory. The system is ready for fully-automatic on-line application on ski-jumping sites that allow stereo camera views with an approximate base-distance ratio of 1:3 within the entire area of investigation.

  11. Magnetic resonance imaging of acoustic streaming: absorption coefficient and acoustic field shape estimation.

    PubMed

    Madelin, Guillaume; Grucker, Daniel; Franconi, Jean-Michel; Thiaudiere, Eric

    2006-07-01

    In this study, magnetic resonance imaging (MRI) is used to visualize acoustic streaming in liquids. A single-shot spin echo sequence (HASTE) with a saturation band perpendicular to the acoustic beam permits the acquisition of an instantaneous image of the flow due to the application of ultrasound. An average acoustic streaming velocity can be estimated from the MR images, from which the ultrasonic absorption coefficient and the bulk viscosity of different glycerol-water mixtures can be deduced. In the same way, this MRI method could be used to assess the acoustic field and time-average power of ultrasonic transducers in water (or other liquids with known physical properties), after calibration of a geometrical parameter that is dependent on the experimental setup. PMID:16650447

  12. Detection of harmonics and recovery of the absorption line profile using logarithmic-transformed wavelength modulation spectroscopy

    NASA Astrophysics Data System (ADS)

    Cong, Menglong; Sun, Dandan

    2016-07-01

    A versatile signal processing strategy for eliminating the residual amplitude modulation (RAM) and distortion in tunable diode laser wavelength modulation spectroscopy is theoretically demonstrated and experimentally validated. The strategy involves logarithmic transformation and differential detection, which are achieved using a homemade circuit. Through the logarithmic transformation, the optical intensity modulation of the laser, which performs as the source of RAM and distortion, is separated from the absorption-induced power attenuation and further balanced during the differential detection. The first harmonic, which is proportional to the first-order derivative of the absorption line profile in the case of a small modulation index, is extracted along with the second harmonic and is integrated for the recovery of the absorption line profile. The experiments are carried out for CH4 at its R(3) absorption line of the 2ν3 overtone for validation of the system, and the derived results are found to be in good agreement with the theoretical simulations. These promising results indicate the high potential of the strategy for absorption spectrum-based determination of gas properties.

  13. Illustrating Surface Shape in Volume Data via Principal Direction-Driven 3D Line Integral Convolution

    NASA Technical Reports Server (NTRS)

    Interrante, Victoria

    1997-01-01

    The three-dimensional shape and relative depth of a smoothly curving layered transparent surface may be communicated particularly effectively when the surface is artistically enhanced with sparsely distributed opaque detail. This paper describes how the set of principal directions and principal curvatures specified by local geometric operators can be understood to define a natural 'flow' over the surface of an object, and can be used to guide the placement of the lines of a stroke texture that seeks to represent 3D shape information in a perceptually intuitive way. The driving application for this work is the visualization of layered isovalue surfaces in volume data, where the particular identity of an individual surface is not generally known a priori and observers will typically wish to view a variety of different level surfaces from the same distribution, superimposed over underlying opaque structures. By advecting an evenly distributed set of tiny opaque particles, and the empty space between them, via 3D line integral convolution through the vector field defined by the principal directions and principal curvatures of the level surfaces passing through each gridpoint of a 3D volume, it is possible to generate a single scan-converted solid stroke texture that may intuitively represent the essential shape information of any level surface in the volume. To generate longer strokes over more highly curved areas, where the directional information is both most stable and most relevant, and to simultaneously downplay the visual impact of directional information in the flatter regions, one may dynamically redefine the length of the filter kernel according to the magnitude of the maximum principal curvature of the level surface at the point around which it is applied.

  14. The Density Matrix of H20 - N2 In the Coordinate Representation: A Monte Carlo Calculation of the Far-Wing Line Shape

    NASA Technical Reports Server (NTRS)

    Ma, Q.; Tipping, R. H.

    1999-01-01

    The far-wing line shape theory within the binary collision and quasistatic framework has been developed using the coordinate representation. Within this formalism, the main computational task is the evaluation of multidimensional integrals whose variables are the orientational angles needed to specify the initial and final positions of the system during transition processes. Using standard methods, one is able to evaluate the 7-dimensional integrations required for linear molecular systems, or the 7-dimensional integrations for more complicated asymmetric-top (or symmetric-top) molecular systems whose interaction potential contains cyclic coordinates. In order to obviate this latter restriction on the form of the interaction potential, a Monte Carlo method is used to evaluate the 9-dimensional integrations required for systems consisting of one asymmetric-top (or symmetric-top) and one linear molecule, such as H20-N2. Combined with techniques developed previously to deal with sophisticated potential models, one is able to implement realistic potentials for these systems and derive accurate, converged results for the far-wing line shapes and the corresponding absorption coefficients. Conversely, comparison of the far-wing absorption with experimental data can serve as a sensitive diagnostic tool in order to obtain detailed information on the short-range anisotropic dependence of interaction potentials.

  15. MOSFIRE ABSORPTION LINE SPECTROSCOPY OF z > 2 QUIESCENT GALAXIES: PROBING A PERIOD OF RAPID SIZE GROWTH

    SciTech Connect

    Belli, Sirio; Ellis, Richard S.; Konidaris, Nick P.; Newman, Andrew B.

    2014-06-20

    Using the MOSFIRE near-infrared multi-slit spectrograph on the Keck 1 Telescope, we have secured high signal-to-noise ratio absorption line spectra for six massive galaxies with redshift 2 < z < 2.5. Five of these galaxies lie on the red sequence and show signatures of passive stellar populations in their rest-frame optical spectra. By fitting broadened spectral templates we have determined stellar velocity dispersions and, with broad-band Hubble Space Telescope and Spitzer photometry and imaging, stellar masses and effective radii. Using this enlarged sample of galaxies, we confirm earlier suggestions that quiescent galaxies at z > 2 have small sizes and large velocity dispersions compared to local galaxies of similar stellar mass. The dynamical masses are in very good agreement with stellar masses (log M {sub *}/M {sub dyn} = –0.02 ± 0.03), although the average stellar-to-dynamical mass ratio is larger than that found at lower redshift (–0.23 ± 0.05). By assuming evolution at fixed velocity dispersion, not only do we confirm a surprisingly rapid rate of size growth but we also consider the necessary evolutionary track on the mass-size plane and find a slope α = dlog R{sub e} /dlog M {sub *} ≳ 2 inconsistent with most numerical simulations of minor mergers. Both results suggest an additional mechanism may be required to explain the size growth of early galaxies.

  16. Variability of 188 broad absorption lines QSOs from the Sloan Digital Sky Survey

    NASA Astrophysics Data System (ADS)

    Bian, Weihao

    2015-08-01

    The variability of broad absorption lines is investigated for a sample of 188 BAL QSOs (Z > 1.7) from the SDSS DR7, covering a timescale of about 0.001 - 3 years in the rest frame. 79 variable regions in the C iv BAL troughs are identified in 47 two-epoch different spectra. For 188 BAL QSOs with two-epoch spectra, it is found that there is no significant correlation between ∆L1500 and ∆α, and about half BAL QSOs appear redder during their brighter phases. It is consistent with the result for non-BAL QSOs by Bian et al. For a subsample of BAL QSOs with variable regions in BAL toughs, it is found that there is a mediate correlation between the ∆L1500 and ∆α, about 70% BAL QSOs appear bluer during their brighter phases. A larger proportion of BAL QSOs with variable BAL-trough regions show bluer during their brighter phases, which implies that the origin of variable BAL-trough regions is related to the central accretion processing. There is a weak correlation between ∆EW and ∆L1500. It suggests that the BAL-trough variation is not dominated by photoionization.

  17. THE PITTSBURGH SLOAN DIGITAL SKY SURVEY Mg II QUASAR ABSORPTION-LINE SURVEY CATALOG

    SciTech Connect

    Quider, Anna M.; Nestor, Daniel B.; Turnshek, David A.; Rao, Sandhya M.; Weyant, Anja N.; Monier, Eric M.; Busche, Joseph R.

    2011-04-15

    We present a catalog of intervening Mg II quasar absorption-line systems in the redshift interval 0.36 {<=} z {<=} 2.28. The catalog was built from Sloan Digital Sky Survey Data Release Four (SDSS DR4) quasar spectra. Currently, the catalog contains {approx}17, 000 measured Mg II doublets. We also present data on the {approx}44, 600 quasar spectra which were searched to construct the catalog, including redshift and magnitude information, continuum-normalized spectra, and corresponding arrays of redshift-dependent minimum rest equivalent widths detectable at our confidence threshold. The catalog is available online. A careful second search of 500 random spectra indicated that, for every 100 spectra searched, approximately one significant Mg II system was accidentally rejected. Current plans to expand the catalog beyond DR4 quasars are discussed. Many Mg II absorbers are known to be associated with galaxies. Therefore, the combination of large size and well understood statistics makes this catalog ideal for precision studies of the low-ionization and neutral gas regions associated with galaxies at low to moderate redshift. An analysis of the statistics of Mg II absorbers using this catalog will be presented in a subsequent paper.

  18. The compact structure of radio-loud broad absorption line quasars

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Jiang, D. R.; Wang, T. G.; Xie, F. G.

    2008-11-01

    We present the results of EVN+MERLIN very long baseline interferometry (VLBI) polarization observations of eight broad absorption line (BAL) quasars at 1.6 GHz, including four low-ionization BAL quasars (LoBALs) and four high-ionization BAL quasars (HiBALs) with either steep or flat spectra on Very Large Array (VLA) scales. Only one steep-spectrum source, J1122+3124, shows two-sided structure on the scale of 2 kpc. The other four steep-spectrum sources and three flat-spectrum sources display either an unresolved image or a core-jet structure on scales of less than 300 pc. In all cases, the marginally resolved core is the dominant radio component. Linear polarization in the cores has been detected in the range of a few to 10 per cent. Polarization, together with high brightness temperatures (from 2 × 109 to 5 × 1010K), suggests a synchrotron origin for the radio emission. There is no apparent difference in the radio morphologies or polarization between low-ionization and high-ionization BAL quasi-stellar objects (QSOs) or between flat- and steep-spectrum sources. We discuss the orientation of BAL QSOs with both flat and steep spectra, and consider a possible evolutionary scenario for BAL QSOs. In this scenario, BAL QSOs are probably a young population of radio sources that are compact steep spectrum or GHz peaked radio source analogues at the low end of radio power.

  19. Bounds on the fine structure constant variability from Fe ii absorption lines in QSO spectra

    NASA Astrophysics Data System (ADS)

    Molaro, P.; Reimers, D.; Agafonova, I. I.; Levshakov, S. A.

    2008-10-01

    The Single Ion Differential α Measurement (SIDAM)method for measuring Δα/α and its figures of merit are illustrated together withthe results produced by means of Fe ii absorption linesof QSO intervening systems. The method providesΔα/α = -0.12 ±1.79 ppm (parts-per-million) at zabs = 1.15towards HE 0515-4414 and Δα/α = 5.66±2.67 ppm at zabs = 1.84towards Q 1101-264, which are so far the most accurate measurementsfor single systems. SIDAM analysis for 3 systems from the Chand et al. [1]sample provides inconsistent results which we interpret as due tocalibration errors of the Chand et al. data at the level ≈10 ppm.In one system evidence for photo-ionization Dopplershift between Mg ii and Fe ii lines is found.This evidence has important bearings on the Many Multipletmethod where the signal for Δα/αvariabilityis carried mainly by systems involving Mg ii absorbers.Some correlations are also found in the Murphy et al. [10] sample which suggestlarger errors than previously reported.Thus, we consider unlikely that both the Chand et al.and Murphy et al. datasets could providean estimate of Δα/α with an accuracy at the level of 1 ppm.A new spectrograph like the ESPRESSO projectwill be crucial to make progress in the astronomical determination of Δα/α.

  20. Fast outflows in broad absorption line quasars and their connection with CSS/GPS sources

    NASA Astrophysics Data System (ADS)

    Bruni , G.; Mack, K.-H.; Montenegro-Montes, F. M.; Brienza, M.; González-Serrano, J. I.

    2016-02-01

    Broad absorption line quasars are among the objects presenting the fastest outflows. The launching mechanism itself is not completely understood. Models in which they could be launched from the accretion disk, and then curved and accelerated by the effect of the radiation pressure, have been presented. We conducted an extensive observational campaign, from radio to optical band, to collect information about their nature and test the models present in the literature, the main dichotomy being between a young scenario and an orientation one. We found a variety of possible orientations, morphologies, and radio ages, not converging to a particular explanation for the BAL phenomenon. From our latest observations in the m- and mm-band, we obtained an indication of a lower dust abundance with respect to normal quasars, thus suggesting a possible feedback process on the host galaxy. Also, in the low-frequency regime we confirmed the presence of CSS components, sometime in conjunction with a GPS one already detected at higher frequencies. Following this, about 70 % of our sample turns out to be in a GPS or CSS+GPS phase. We conclude that fast outflows, responsible for the BAL features, can be more easily present among objects going through a restarting or just-started radio phase, where radiation pressure can substantially contribute to their acceleration.

  1. The Pittsburgh Sloan Digital Sky Survey Mg II Quasar Absorption-line Survey Catalog

    NASA Astrophysics Data System (ADS)

    Quider, Anna M.; Nestor, Daniel B.; Turnshek, David A.; Rao, Sandhya M.; Monier, Eric M.; Weyant, Anja N.; Busche, Joseph R.

    2011-04-01

    We present a catalog of intervening Mg II quasar absorption-line systems in the redshift interval 0.36 <= z <= 2.28. The catalog was built from Sloan Digital Sky Survey Data Release Four (SDSS DR4) quasar spectra. Currently, the catalog contains ~17, 000 measured Mg II doublets. We also present data on the ~44, 600 quasar spectra which were searched to construct the catalog, including redshift and magnitude information, continuum-normalized spectra, and corresponding arrays of redshift-dependent minimum rest equivalent widths detectable at our confidence threshold. The catalog is available online. A careful second search of 500 random spectra indicated that, for every 100 spectra searched, approximately one significant Mg II system was accidentally rejected. Current plans to expand the catalog beyond DR4 quasars are discussed. Many Mg II absorbers are known to be associated with galaxies. Therefore, the combination of large size and well understood statistics makes this catalog ideal for precision studies of the low-ionization and neutral gas regions associated with galaxies at low to moderate redshift. An analysis of the statistics of Mg II absorbers using this catalog will be presented in a subsequent paper.

  2. Quasar Absorption Lines in the Extreme Ultraviolet: The Smoking Guns of Cosmic Feedback

    NASA Astrophysics Data System (ADS)

    Tripp, Todd

    2011-01-01

    Three years ago at the winter AAS meeting I presented a talk entitled, perhaps somewhat pretentiously, "Terra Incognita: Probing The IGM-Galaxy Interface With COS." Now that the Cosmic Origins Spectrograph (COS) has been successfully installed on the Hubble Space Telescope, this instrument is delivering data that even exceed my hopes and predictions from three years ago. This talk will demonstrate that COS is enabling investigations of aspects of the Universe that have never been seen before. Specific examples will include the following: (1) Detections of absorption lines of Ne VIII and Mg X, which probe highly-ionized and low-density plasmas that can exist at temperatures in excess of 106 K. Due to the low density of galaxy halos and the IGM, X-ray emission from these plasmas is entirely undetectable with current or future missions. (2) Detections of remarkably strong O VI absorbers spanning velocity ranges in excess of hundreds of km/s, probably arising in galactic winds. While such outflows can be seen from the ground, the extreme ultraviolet provides a much richer suite of physical conditions diagnostics. (3) Detection of molecular hydrogen in unexpected places. An unifying thems of these examples is cosmic feedback and accretion -- these observations provide important new constraints on how galaxies interact with their surroundings.

  3. The far-infrared properties of broad absorption line quasars from the Sloan Digital Sky Survey

    NASA Astrophysics Data System (ADS)

    Pu, Xingting

    2015-05-01

    We present the results of a study which uses a sample of 320 Sloan Digital Sky Survey (SDSS) quasars with 1.68≤ z≤2.28 inside the Herschel Stripe 82 Survey (HerS) region to compare the mid-infrared (MIR) and far-infrared (FIR) properties of broad absorption line (BAL) and non-BAL quasars. The BAL quasar sample comprises 56 high-ionization BAL (HiBAL) quasars and two low-ionization BAL (LoBAL) quasars. The BAL and non-BAL samples have similar intrinsic absolute i magnitude. When combined with Wide-field Infrared Survey Explorer (WISE) MIR photometry, the BAL quasars are found to have MIR luminosities and MIR-to-optical luminosity ratios consistent with those of the non-BALs, in good agreement with the results of Gallagher et al. The FIR detection rates of BAL and non-BAL quasars are found to be consistent with each other. The BAL quasars are found to have FIR fluxes indistinguishable from that of non-BAL quasars using survival analysis methods. No evidence is found for a correlation between FIR flux and BAL strength, consistent with the recent results of Cao Orjales et al. The FIR properties of this sample appear to be at odds with the evolutionary model in which BALs are an early phase in the lives of quasars.

  4. Subaru High-Resolution Spectroscopy of Complex Metal Absorption Lines of the Quasar HS 1603+3820

    NASA Astrophysics Data System (ADS)

    Misawa, Toru; Yamada, Toru; Takada-Hidai, Masahide; Wang, Yiping; Kashikawa, Nobunari; Iye, Masanori; Tanaka, Ichi

    2003-03-01

    We present a high-resolution spectrum of the quasar HS 1603+3820 (zem=2.542), observed with the High Dispersion Spectrograph on the Subaru Telescope. This quasar, first discovered in the Hamburg/CfA Quasar Survey, has 11 C IV lines at 1.96lines at zabs>2.29 and resolves some of them into multiple narrow components with b<25 km s-1 because of the high spectral resolution R=45,000, while other lines show broad profiles (b>65 km s-1). We use three properties of C IV lines, specifically, time variability, covering factor, and absorption-line profile, to classify them into quasar intrinsic absorption lines (QIALs) and spatially intervening absorption lines (SIALs). The C IV lines at 2.42lines at 2.48lines at zabs~2.54 and 2.55, because their velocity shifts, 430 km s-1 blueward and 950 km s-1 redward of the quasar, are very small. The C IV line at zabs~2.48 consists of many narrow components and also has corresponding low-ionization metal lines (Al II, Si II, and Fe II). The velocity distribution of these low-ionization ions is concentrated at the center of the system compared with that of the high-ionization C IV ion. Therefore we ascribe this system of absorption lines to an intervening galaxy. Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

  5. DETECTION OF A TRANSIENT X-RAY ABSORPTION LINE INTRINSIC TO THE BL LACERTAE OBJECT H 2356-309

    SciTech Connect

    Fang Taotao; Buote, David A.; Humphrey, Philip J.; Canizares, Claude R.

    2011-04-10

    Since the launch of the Einstein X-ray Observatory in the 1970s, a number of broad absorption features have been reported in the X-ray spectra of BL Lac objects. These features are often interpreted as arising from high-velocity outflows intrinsic to the BL Lac object, therefore providing important information about the inner environment around the central engine. However, such absorption features have not been observed more recently with high-resolution X-ray telescopes such as Chandra and XMM-Newton. In this paper, we report the detection of a transient X-ray absorption feature intrinsic to the BL Lac object H 2356-309 with the Chandra X-ray Telescope. This BL Lac object was observed during XMM-Newton cycle 7 and Chandra cycles 8 and 10, as part of our campaign to investigate X-ray absorption produced by the warm-hot intergalactic medium residing in the foreground large-scale superstructure. During one of the 80 ks Chandra cycle 10 observations, a transient absorption feature was detected at 3.3{sigma} (or 99.9% confidence level, accounting for the number of 'trials), which we identify as the O VIII K{alpha} line produced by an absorber intrinsic to the BL Lac object. None of the other 11 observations showed this line. We constrain the ionization parameter (25 {approx}< {Xi} {approx}< 40) and temperature (10{sup 5} K absorption line; however, the derived properties of the emission material are very different from those of the absorption material, implying it is unlikely a typical P Cygni-type profile.

  6. Self- and CO2-broadened line shape parameters for infrared bands of HDO

    NASA Astrophysics Data System (ADS)

    Smith, Mary-Ann H.; Malathy Devi, V.; Benner, D. Chris; Sung, Keeyoon; Mantz, Arlan W.; Gamache, Robert R.; Villanueva, Geronimo L.

    2015-11-01

    Knowledge of CO2-broadened HDO line widths and their temperature dependence is required to interpret infrared spectra of the atmospheres of Mars and Venus. However, this information is currently absent in most spectroscopic databases. We have analyzed nine high-resolution, high signal-to-noise spectra of HDO and HDO+CO2 mixtures to obtain broadening coefficients and other line shape parameters for transitions of the ν2 and ν3 vibrational bands located at 7.13 and 2.70 μm, respectively. The gas samples were prepared by mixing equal amounts of high-purity distilled H2O and 99% enriched D2O. The spectra were recorded at different temperatures (255-296 K) using a 20.38 cm long coolable cell [1] installed in the sample compartment of the Bruker IFS125HR Fourier transform spectrometer at the Jet Propulsion Laboratory in Pasadena, CA. The retrieved HDO spectroscopic parameters include line positions, intensities, self- and CO2-broadened half-width and pressure-induced shift coefficients and the temperature dependences for CO2 broadening. These spectroscopic parameters were obtained by simultaneous multispectrum fitting [2] of the same interval in all nine spectra. A non-Voigt line shape with speed dependence was applied. Line mixing was also observed for several transition pairs. Preliminary results compare well with the few other measurements reported in the literature.[1] K. Sung et al., J. Mol. Spectrosc. 162, 124-134 (2010).[2] D. C. Benner et al., J. Quant. Spectrosc. Radiat Transfer 53, 705-721 (1995).The research performed at the College of William and Mary was supported by NASA’s Mars Fundamental Research Program (Grant NNX13AG66G). The research at Jet Propulsion Laboratory, California Institute of Technology, Connecticut College, Langley Research Center, and Goddard Space Flight Center was conducted under contracts and cooperative agreements with the National Aeronautics and Space Administration. RRG is pleased to acknowledge support of this study by the

  7. Application of wavelet transforms to determine peak shape parameters for interference detection in graphite-furnace atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Sadler, D. A.; Littlejohn, D.; Boulo, P. R.; Soraghan, J. S.

    1998-08-01

    A procedure to quantify the shape of the absorbance-time profile, obtained during graphite furnace atomic absorption spectrometry, has been used to detect interference effects caused by the presence of a concomitant salt. The quantification of the absorption profile is achieved through the use of the Lipschitz regularity, α0, obtained from the wavelet transform of the absorbance-time profile. The temporal position of certain features and their associated values of α0 provide a unique description of the shape of the absorbance-time profile. Changes to the position or values of α0 between standard and sample atomizations may be indicative of uncorrected interference effects. A weak, but linear, dependence was found of the value of α0 upon the analyte concentration for Cr and Cu. The ability of the Lipschitz regularity to detect interference effects was illustrated for Pb, Se and Cu. For Pb, the lowest concentration of NaCl added, 0.005% m/v, changed both the values of α0 and the peak height absorbance. For Se, no change in the peak height and peak area absorbance signals was detected up to a NaCl concentration of 0.25% m/v. The values of the associated Lipschitz regularities were found to be invariant to NaCl concentration up to this value. For Cu, a concentration of 0.05% m/v NaCl reduced the peak height and peak area absorbance signals by approximately 25% and significantly altered the values of α0.

  8. The self-broadened, isolated CO2 spectral line shape investigation

    NASA Astrophysics Data System (ADS)

    Osipov, Konstantin Yu.; Kapitanov, Venedikt A.; Protasevich, Alexander E.; Ponurovskiy, Yakov Y.

    2014-11-01

    The measurements of "isolated" CO2 line (6231.6 cm-1) absorption spectra in wide pressure range from 2 to 1000 mbar were performed on 3-channel high-resolution diode laser spectrometer. 4 theoretical models used for the description of lineshape contour: usual Voigt, Hard-collisional (Rautian), Soft-collisional (Galatry), and Speed-dependent Voigt (Boone). LabView based software used for the testing of current lineshape models. This software performed the nonlinear least-squares fit of the model spectrum to the experimental spectra recorded at each pressure individually. The detailed research of weak lines influence to the retrieved parameters of "isolated" CO2 (6231.6 cm-1, R4 band 30013- 00001) is provided. It is shown that the use of Rautian and Galatry lineshape models leads to a significant deviation from linear of the narrowing coefficient pressure dependence while coming to the high pressures range. Most appropriate for the common description of whole experimental spectra in entire range of pressures (up to 1000 mbar) is the Speed- Dependent (Boone) profile.

  9. Outflows in infrared-luminous galaxies: Absorption-line spectroscopy of starbursts and AGN

    NASA Astrophysics Data System (ADS)

    Rupke, David S.

    Large-scale galactic outflows, better known as superwinds, are driven by the powerful energy reservoirs in star forming and active galaxies. They play a significant role in galaxy formation, galaxy evolution, and the evolution of the intergalactic medium. We have performed a survey of over 100 infrared-luminous galaxies in order to address the exact frequency with which they occur in different galaxy types, the dependence of their properties on those of their host galaxies, and their properties in the most luminous starburst and active galaxies. Most of our sample consists of ultraluminous infrared galaxies (ULIRGs), and we use moderate- resolution spectroscopy of the Na I D interstellar absorption feature (which directly probes the neutral gas phase). We find superwinds in the majority of these galaxies at typical maximum, deprojected velocities of 500 700 km s-1. The detection rate increases with star formation rate (SFR) in starbursts, while the mass outflow rate appears constant with SFR, contrary to theoretical expectations. The resulting mass entrainment efficiencies in ULIRGs are quite low, of order a few percent of the star formation rate. There is some dependence of outflow velocity on host galaxy properties; the outflow velocities in LINERs are higher than those in H II galaxies, and the highest column density gas in each galaxy may have an upper envelope in velocity that increases with SFR. Outflows in most galaxies hosting a dominant AGN have very similar properties to those in starbursts, so discerning their power source is difficult. The velocities in Seyfert 2 outflows may be slightly higher than those in starbursts, and the fraction of neutral gas escaping Seyfert 2s is higher than that in starbursts (˜50% vs. ≲ 20%). The outflows in our Seyfert 1 galaxies have extreme velocities of up to ˜104 km s-1, and two of three Seyfert is with outflows possess broad absorption lines. Finally, we find that spectroscopy of a few galaxies at very high

  10. Highly Ionized Iron Absorption Lines from Outflowing Gases in the X-ray Spectrum of NGC 1365

    NASA Technical Reports Server (NTRS)

    Risaliti, G.; Bianchi, S.; Matt, G.; Baldi, A.; Elvis, M.; Fabbiano, G.; Zezas, A.

    2006-01-01

    We present the discovery of four absorption lines in the X-ray spectrum of the Seyfert galaxy NGC 1365, at energies between 6.7 and 8.3 keV. The lines are detected with high statistical confidence (from >20 sigma for the strongest to -4 sigma for the weakest) in two XMM-Newton observations 60 ks long. We also detect the same lines, with a lower signal-to-noise ratio (but still >2 sigma for each line), in two previous shorter (-10 ks) XMM-Newton observations. The spectral analysis identifies these features as Fe XXV and Fe XXVI Kalpha and Kbeta lines, outflowing with velocities varying between -1000 and -5000 km/s among the observations. These are the highest quality detections of such lines so far. The high equivalent widths [EW (Kalpha) approximately 100 eV] and the Kalpha/Kbeta ratios imply that the lines are due to absorption of the AGN continuum by a highly ionized gas with column density NH-5?1023 cm(exp -2) at a distance of -(50-100)RS from the continuum source.

  11. Absorption and emission spectral shapes of a prototype dye in water by combining classical/dynamical and quantum/static approaches.

    PubMed

    Petrone, Alessio; Cerezo, Javier; Ferrer, Francisco J Avila; Donati, Greta; Improta, Roberto; Rega, Nadia; Santoro, Fabrizio

    2015-05-28

    We study the absorption and emission electronic spectra in an aqueous solution of N-methyl-6-oxyquinolinium betaine (MQ), an interesting dye characterized by a large change of polarity and H-bond ability between the ground (S0) and the excited (S1) states. To that end we compare alternative approaches based either on explicit solvent models and density functional theory (DFT)/molecular-mechanics (MM) calculations or on DFT calculations on clusters models embedded in a polarizable continuum (PCM). In the first approach (ClMD), the spectrum is computed according to the classical Franck-Condon principle, from the dispersion of the time-dependent (TD)-DFT vertical transitions at selected snapshots of molecular dynamics (MD) on the initial state. In the cluster model (Qst) the spectrum is simulated by computing the quantum vibronic structure, estimating the inhomogeneous broadening from state-specific TD-DFT/PCM solvent reorganization energies. While both approaches provide absorption and emission spectral shapes in nice agreement with experiment, the Stokes shift is perfectly reproduced by Qst calculations if S0 and S1 clusters are selected on the grounds of the MD trajectory. Furthermore, Qst spectra better fit the experimental line shape, mostly in absorption. Comparison of the predictions of the two approaches is very instructive: the positions of Qst and ClMD spectra are shifted due to the different solvent models and the ClMD spectra are narrower than the Qst ones, because MD underestimates the width of the vibrational density of states of the high-frequency modes coupled to the electronic transition. On the other hand, both Qst and ClMD approaches highlight that the solvent has multiple and potentially opposite effects on the spectral width, so that the broadening due to solute-solvent vibrations and electrostatic interaction with bulk solvent is (partially) counterbalanced by a narrowing of the contribution due to the solute vibrational modes. Qst analysis

  12. Quasars as the formation sites of high-redshift ellipticals: a signature in the `associated' absorption-line systems?

    NASA Astrophysics Data System (ADS)

    Franceschini, A.; Gratton, R.

    1997-03-01

    Published data on the average metallicities and abundance ratios for absorption-line systems in high-redshift quasars suggest that a dichotomy may exist between the chemical composition of damped Lyman alpha (Lyalpha) systems (interpreted as intervening galaxies in the QSO line of sight) and the z_abs~=z_em absorption- line systems associated with the quasar. Intervening systems have smaller than solar metallicities, whereas associated absorbers have solar or greater than solar metallicities and small N/C ratios. While these results have to be confirmed by more precise abundance determinations, we argue that they may be explained by an early phase of efficient metal enrichment occurring only in the close environment of high-z QSOs, and characterized by an excess type-II supernova (SNII) activity. This is reminiscent of the SNII phase required to explain the abundance ratios (favouring alpha- over Fe-group elements) observed in the intracluster (IC) medium of local galaxy clusters. We explore the following scenario, to be tested by forthcoming observations of QSO absorption lines using very large optical telescopes. (a) Well-studied damped- Lyalpha, Lyalpha and metal lines in intervening systems trace only part of the history of metal production in the Universe - the one concerning slowly star-forming discs or dwarf irregulars. (b) The complementary class of early-type and bulge-dominated galaxies formed quickly (at z>~4-5) through a huge episode of star formation favouring high-mass stars. (c) The nucleus of the latter is the site of the subsequent formation of a quasar, which partly hides from view the dimmer host galaxy. (d) The products of a galactic wind, following the violent episode of star formation in the host galaxy and metal pollution of the IC medium in the forming cluster, could be directly observable in the z_abs~=z_em associated absorption systems on the QSO line of sight.

  13. Spectral Line-Shape Model to Replace the Voigt Profile in Spectroscopic Databases

    NASA Astrophysics Data System (ADS)

    Lisak, Daniel; Ngo, Ngoc Hoa; Tran, Ha; Hartmann, Jean-Michel

    2014-06-01

    The standard description of molecular line shapes in spectral databases and radiative transfer codes is based on the Voigt profile. It is well known that its simplified assumptions of absorber free motion and independence of collisional parameters from absorber velocity lead to systematic errors in analysis of experimental spectra, and retrieval of gas concentration. We demonstrate1,2 that the partially correlated quadratic speed-dependent hardcollision profile3. (pCqSDHCP) is a good candidate to replace the Voigt profile in the next generations of spectroscopic databases. This profile takes into account the following physical effects: the Doppler broadening, the pressure broadening and shifting of the line, the velocity-changing collisions, the speed-dependence of pressure broadening and shifting, and correlations between velocity- and phase/state-changing collisions. The speed-dependence of pressure broadening and shifting is incorporated into the pCqSDNGP in the so-called quadratic approximation. The velocity-changing collisions lead to the Dicke narrowing effect; however in many cases correlations between velocityand phase/state-changing collisions may lead to effective reduction of observed Dicke narrowing. The hard-collision model of velocity-changing collisions is also known as the Nelkin-Ghatak model or Rautian model. Applicability of the pCqSDHCP for different molecular systems was tested on calculated and experimental spectra of such molecules as H2, O2, CO2, H2O in a wide span of pressures. For all considered systems, pCqSDHCP is able to describe molecular spectra at least an order of magnitude better than the Voigt profile with all fitted parameters being linear with pressure. In the most cases pCqSDHCP can reproduce the reference spectra down to 0.2% or better, which fulfills the requirements of the most demanding remote-sensing applications. An important advantage of pCqSDHCP is that a fast algorithm for its computation was developedab4,5 and allows

  14. Self- and air-broadened line shape parameters in the ν2+ν3 band of 12CH4: 4500-4630 cm-1

    NASA Astrophysics Data System (ADS)

    Devi, V. Malathy; Benner, D. Chris; Smith, Mary Ann H.; Mantz, Arlan W.; Sung, Keeyoon; Crawford, Timothy J.; Predoi-Cross, Adriana

    2015-02-01

    Accurate knowledge of spectral line shape parameters is important for infrared transmission and radiance calculations in the terrestrial atmosphere. In this paper, we report the self- and air-broadened Lorentz half-widths, pressure-induced shifts and line mixing coefficients (via off-diagonal relaxation matrix elements) along with their temperature dependences for methane ν2+ν3 absorption lines in the 4500-4630 cm-1 region of the Octad. For this, we recorded 14 high-resolution, high signal to noise ratio (S/N) spectra of high-purity (99.95% 12C-enriched) samples of pure methane and its dilute mixtures in dry air between 298 K and 148 K. A Bruker IFS 125HR Fourier transform spectrometer (FTS) at the Jet Propulsion Laboratory, Pasadena, California, was used to obtain the experimental data. The absorption cell used for this study was a specially built 20.38 cm long coolable cell installed in its sample compartment. The sample pressures for the pure 12CH4 spectra were 4.5-385 Torr; for the air-broadened spectra the total pressures ranged between 95 and 300 Torr with the methane volume mixing ratios between 0.04 and 0.097. All 14 spectra were fitted simultaneously using an interactive multispectrum nonlinear least-squares curve fitting technique. The results are compared to values reported in the literature.

  15. Measured Signatures of Low Energy, Physical Sputtering in the Line Shape of Neutral Carbon Emission

    SciTech Connect

    Brooks, N; Isler, R; Whyte, D; Fenstermacher, M; Groebner, R; Stangeby, P; Heidbrink, W; Jackson, G; Mahdavi, M; West, W

    2004-12-01

    The most important mechanisms for introducing carbon into the DIII-D divertors [Nucl. Fusion 42 (2002) 614] are physical and chemical sputtering. Previous investigations have indicated that operating conditions where one or the other of these is dominant can be distinguished by using CD and C{sub 2} emissions to infer C I influxes from dissociation of hydrocarbons and comparing to measured C I influxes. The present work extends these results through detailed analysis of the C I spectral line shapes. In general, it is found that the profiles are actually asymmetric and have shifted peaks. These features are interpreted as originating from a combination of an anisotropic velocity distribution from physical sputtering (the Thompson model) and an isotropic distribution from molecular dissociation. The present study utilizes pure helium plasmas to benchmark C I spectral profiles arising from physical sputtering alone.

  16. Photoemission line-shapes and dispersion relations in the superconducting state of BISCO

    NASA Astrophysics Data System (ADS)

    Fedorov, A. V.; Chuang, Y.-D.; Gromko, A. D.; Sun, Z.; Douglas, J.; Koralek, J. D.; Dessau, D. S.; Aiura, Y.; Yamaguchi, Y.; Oka, K.; Ando, Yoichi

    2003-03-01

    Using high-resolution angle-resolved photoemission on BISCO we have studied the dispersion relations and photoemission line-shapes close to the Fermi level. Results taken near (p,0) points of the Brilloin zone indicate that traditional peak-dip-hump structure is largely due to the presence of bonding and anti-bonding bands. However, a separate much weaker peak and hump structure can be detected if the bilayer splitting is resolved properly. This true peak-dip hump lineshape develops in the superconducting state. At the same time, the dispersion relations show the kink" or mass enhancement with the true quasiparticles occurring within the kink energy. We will argue that "kinks" detected in the vicinity of (p,0) points and along the nodal direction are distinctly different in nature.

  17. Dispersion and line shape of plasmon satellites in one, two, and three dimensions

    NASA Astrophysics Data System (ADS)

    Vigil-Fowler, Derek; Louie, Steven G.; Lischner, Johannes

    2016-06-01

    Using state-of-the-art many-body Green's function calculations based on the GW plus cumulant approach, we analyze the properties of plasmon satellites in the electron spectral function resulting from electron-plasmon interactions in one-, two-, and three-dimensional systems. Specifically, we show how their dispersion relation, line shape, and linewidth are related to the properties of the constituent electrons and plasmons. To gain insight into the many-body processes giving rise to the formation of plasmon satellites, we connect the GW plus cumulant approach to a many-body wave-function picture of electron-plasmon interactions and introduce the coupling-strength-weighted electron-plasmon joint density states as a powerful concept for understanding plasmon satellites.

  18. Electron paramagnetic resonance linewidths and line shapes for the molecular magnets Fe8 and Mn12

    NASA Astrophysics Data System (ADS)

    Park, Kyungwha; Novotny, M. A.; Dalal, N. S.; Hill, S.; Rikvold, P. A.

    2002-05-01

    We study theoretically electron paramagnetic resonance (EPR) linewidths for single crystals of the molecular magnets Fe8 and Mn12 as functions of energy eigenstates Ms, frequency, and temperature when a magnetic field along the easy axis is swept at fixed excitation frequency. This work was motivated by recent EPR experiments. To calculate the linewidths, we use density-matrix equations, including dipolar interactions and distributions of the uniaxial anisotropy parameter D and the Landé g factor. Our calculated linewidths agree well with the experimental data. We also examine the line shapes of the EPR spectra due to local rotations of the magnetic anisotropy axes caused by defects in samples. Our preliminary results predict that this effect leads to asymmetry in the EPR spectra.

  19. Experimental demonstration of an invisible cloak with irregular shape by using tensor transmission line metamaterials

    NASA Astrophysics Data System (ADS)

    Liu, Guo-Chang; Li, Chao; Fang, Guang-You

    2015-01-01

    We present the design and the experimental demonstration of an invisible cloak with irregular shape by using tensor transmission line (TL) metamaterials. The fabricated cloak consists of tensor TL unit cells exhibiting anisotropic effective material parameters, while the background medium consists of isotropic TL unit cells. The simulated and the measured field patterns around the cloak show a fairly good agreement, both demonstrate that the fabricated cloak can shield the cloaked interior area from electromagnetic fields without perturbing the external fields. The scattering of the cloaked perfect electric conductor (PEC) is minimized. Furthermore, the nonresonant property of the TL structure results in a relatively broad bandwidth of the realized cloak, which is clearly observed in our experiment. Project supported by the National Natural Science Foundation of China (Grant Nos.11174280, 60990323, and 60990320) and the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No.YYYJ-1123).

  20. Trapping of Water Drops by Line-Shaped Defects on Superhydrophobic Surfaces.

    PubMed

    Olin, Pontus; Lindström, Stefan B; Wågberg, Lars

    2015-06-16

    We have investigated the effect of line-shaped topographical defects on the motion of water drops across superhydrophobic wax surfaces using a high-speed video camera. The defects are introduced onto the superhydrophobic wax surfaces by a scratching procedure. It is demonstrated that the motion of a drop interacting with the defect can be approximated by a damped harmonic oscillator. Whether a drop passes or gets trapped by the defect is determined by the incident speed and the properties of the oscillator, specifically by the damping ratio and a nondimensional forcing constant representing the effects of gravity and pinning forces. We also show that it is possible to predict a critical trapping speed as well as an exit speed in systems with negligible viscous dissipation using a simple work-energy consideration. PMID:26010934

  1. Vision-based in-line fabric defect detection using yarn-specific shape features

    NASA Astrophysics Data System (ADS)

    Schneider, Dorian; Aach, Til

    2012-01-01

    We develop a methodology for automatic in-line flaw detection in industrial woven fabrics. Where state of the art detection algorithms apply texture analysis methods to operate on low-resolved ({200 ppi) image data, we describe here a process flow to segment single yarns in high-resolved ({1000 ppi) textile images. Four yarn shape features are extracted, allowing a precise detection and measurement of defects. The degree of precision reached allows a classification of detected defects according to their nature, providing an innovation in the field of automatic fabric flaw detection. The design has been carried out to meet real time requirements and face adverse conditions caused by loom vibrations and dirt. The entire process flow is discussed followed by an evaluation using a database with real-life industrial fabric images. This work pertains to the construction of an on-loom defect detection system to be used in manufacturing practice.

  2. Design and application of a fish-shaped lateral line probe for flow measurement.

    PubMed

    Tuhtan, J A; Fuentes-Pérez, J F; Strokina, N; Toming, G; Musall, M; Noack, M; Kämäräinen, J K; Kruusmaa, M

    2016-04-01

    We introduce the lateral line probe (LLP) as a measurement device for natural flows. Hydraulic surveys in rivers and hydraulic structures are currently based on time-averaged velocity measurements using propellers or acoustic Doppler devices. The long-term goal is thus to develop a sensor system, which includes spatial gradients of the flow field along a fish-shaped sensor body. Interpreting the biological relevance of a collection of point velocity measurements is complicated by the fact that fish and other aquatic vertebrates experience the flow field through highly dynamic fluid-body interactions. To collect body-centric flow data, a bioinspired fish-shaped probe is equipped with a lateral line pressure sensing array, which can be applied both in the laboratory and in the field. Our objective is to introduce a new type of measurement device for body-centric data and compare its output to estimates of conventional point-based technologies. We first provide the calibration workflow for laboratory investigations. We then provide a review of two velocity estimation workflows, independent of calibration. Such workflows are required as existing field investigations consist of measurements in environments where calibration is not feasible. The mean difference for uncalibrated LLP velocity estimates from 0 to 50 cm/s under in a closed flow tunnel and open channel flume was within 4 cm/s when compared to conventional measurement techniques. Finally, spatial flow maps in a scale vertical slot fishway are compared for the LLP, direct measurements, and 3D numerical models where it was found that the LLP provided a slight overestimation of the current velocity in the jet and underestimated the velocity in the recirculation zone. PMID:27131710

  3. Design and application of a fish-shaped lateral line probe for flow measurement

    NASA Astrophysics Data System (ADS)

    Tuhtan, J. A.; Fuentes-Pérez, J. F.; Strokina, N.; Toming, G.; Musall, M.; Noack, M.; Kämäräinen, J. K.; Kruusmaa, M.

    2016-04-01

    We introduce the lateral line probe (LLP) as a measurement device for natural flows. Hydraulic surveys in rivers and hydraulic structures are currently based on time-averaged velocity measurements using propellers or acoustic Doppler devices. The long-term goal is thus to develop a sensor system, which includes spatial gradients of the flow field along a fish-shaped sensor body. Interpreting the biological relevance of a collection of point velocity measurements is complicated by the fact that fish and other aquatic vertebrates experience the flow field through highly dynamic fluid-body interactions. To collect body-centric flow data, a bioinspired fish-shaped probe is equipped with a lateral line pressure sensing array, which can be applied both in the laboratory and in the field. Our objective is to introduce a new type of measurement device for body-centric data and compare its output to estimates of conventional point-based technologies. We first provide the calibration workflow for laboratory investigations. We then provide a review of two velocity estimation workflows, independent of calibration. Such workflows are required as existing field investigations consist of measurements in environments where calibration is not feasible. The mean difference for uncalibrated LLP velocity estimates from 0 to 50 cm/s under in a closed flow tunnel and open channel flume was within 4 cm/s when compared to conventional measurement techniques. Finally, spatial flow maps in a scale vertical slot fishway are compared for the LLP, direct measurements, and 3D numerical models where it was found that the LLP provided a slight overestimation of the current velocity in the jet and underestimated the velocity in the recirculation zone.

  4. The parsec-scale structure of radio-loud broad absorption line quasars

    NASA Astrophysics Data System (ADS)

    Bruni, G.; Dallacasa, D.; Mack, K.-H.; Montenegro-Montes, F. M.; González-Serrano, J. I.; Holt, J.; Jiménez-Luján, F.

    2013-06-01

    Context. Broad absorption line quasars (BAL QSOs) belong to a class of objects not well-understood as yet. Their UV spectra show BALs in the blue wings of the UV resonance lines, owing to ionized gas with outflow velocities up to 0.2 c. They can have radio emission that is difficult to characterize and that needs to be studied at various wavelengths and resolutions. Aims: We aim to study the pc-scale properties of their synchrotron emission and, in particular, to determine their core properties. Methods: We performed observations in the Very Long Baseline Interferometry (VLBI) technique, using both the European VLBI Network (EVN) at 5 GHz, and the Very Long Baseline Array (VLBA) at 5 and 8.4 GHz to map the pc-scale structure of the brightest radio-loud objects of our sample, allowing a proper morphological interpretation. Results: A variety of morphologies have been found: 9 BAL QSOs on a total of 11 observed sources have a resolved structure. Core-jet, double, and symmetric objects are present, suggesting different orientations. In some cases the sources can be young GPS or CSS. The projected linear size of the sources, also considering observations from our previous work for the same objects, can vary from tens of pc to hundreds of kpc. In some cases, a diffuse emission can be supposed from the missing flux-density with respect to previous lower resolution observations. Finally, the magnetic field strength does not significantly differ from the values found in the literature for radio sources with similar sizes. Conclusions: These results are not easily interpreted with the youth scenario for BAL QSOs, in which they are generally compact objects still expelling a dust cocoon. The variety of orientations, morphologies, and extensions found are presumably related to different possible angles for the BAL producing outflows, with respect to the jet axis. Moreover, the phenomenon could be present in various phases of the QSO evolution. Table 3 is available in

  5. Classifying broad absorption line quasars: metrics, issues and a new catalogue constructed from SDSS DR5

    NASA Astrophysics Data System (ADS)

    Scaringi, S.; Cottis, C. E.; Knigge, C.; Goad, M. R.

    2009-11-01

    We apply a recently developed method for classifying broad absorption line quasars (BALQSOs) to the latest quasi-stellar object (QSO) catalogue constructed from Data Release 5 of the Sloan Digital Sky Survey. Our new hybrid classification scheme combines the power of simple metrics, supervised neural networks and visual inspection. In our view, the resulting BALQSO catalogue is both more complete and more robust than all previous BALQSO catalogues, containing 3552 sources selected from a parent sample of 28421 QSOs in the redshift range 1.7 < z < 4.2. This equates to a raw BALQSO fraction of 12.5 per cent. In the process of constructing a robust catalogue, we shed light on the main problems encountered when dealing with BALQSO classification, many of which arise due to the lack of a proper physical definition of what constitutes a BAL. This introduces some subjectivity in what is meant by the term BALQSO, and because of this, we also provide all of the meta-data used in constructing our catalogue, for every object in the parent QSO sample. This makes it easy to quickly isolate and explore subsamples constructed with different metrics and techniques. By constructing composite QSO spectra from subsamples classified according to the meta-data, we show that no single existing metric produces clean and robust BALQSO classifications. Rather, we demonstrate that a variety of complementary metrics are required at the moment to accomplish this task. Along the way, we confirm the finding that BALQSOs are redder than non-BALQSOs and that the raw BALQSO fraction displays an apparent trend with signal-to-noise ratio steadily increasing from 9 per cent in low signal-to-noise ratio data up to 15 per cent.

  6. THE LONG-TERM X-RAY VARIABILITY OF BROAD ABSORPTION LINE QUASARS

    SciTech Connect

    Saez, C.; Brandt, W. N.; Garmire, G. P.; Gallagher, S. C.; Bauer, F. E.

    2012-11-01

    We analyze the long-term (rest-frame 3-30 yr) X-ray variability of 11 broad absorption line (BAL) quasars, mainly to constrain the variation properties of the X-ray absorbing shielding gas that is thought to play a critical role in BAL wind launching. Our BAL quasar sample has coverage with multiple X-ray observatories including Chandra, XMM-Newton, BeppoSAX, ASCA, ROSAT, and Einstein; 3-11 observations are available for each source. For seven of the eleven sources we have obtained and analyzed new Chandra observations suitable for searching for any strong X-ray variability. We find highly significant X-ray variability in three sources (PG 1001+054, PG 1004+130, and PG 2112+059). The maximum observed amplitude of the 2-8 keV variability is a factor of 3.8 {+-} 1.3, 1.5 {+-} 0.2, and 9.9 {+-} 2.3 for PG 1001+054, PG 1004+130, and PG 2112+059, respectively, and these sources show detectable variability on rest-frame timescales down to 5.8, 1.4, and 0.5 yr. For PG 1004+130 and PG 2112+059 we also find significant X-ray spectral variability associated with the flux variability. Considering our sample as a whole, we do not find that BAL quasars exhibit exceptional long-term X-ray variability when compared to the quasar population in general. We do not find evidence for common strong changes in the shielding gas owing to physical rearrangement or accretion-disk rotation, although some changes are found; this has implications for modeling observed ultraviolet BAL variability. Finally, we report for the first time an X-ray detection of the highly polarized and well-studied BAL quasar IRAS 14026+4341 in its new Chandra observation.

  7. A strong redshift dependence of the broad absorption line quasar fraction

    NASA Astrophysics Data System (ADS)

    Allen, James T.; Hewett, Paul C.; Maddox, Natasha; Richards, Gordon T.; Belokurov, Vasily

    2011-01-01

    We describe the application of non-negative matrix factorization to generate compact reconstructions of quasar spectra from the Sloan Digital Sky Survey (SDSS), with particular reference to broad absorption line quasars (BALQSOs). BAL properties are measured for Si IVλ1400, C IVλ1550, Al IIIλ1860 and Mg IIλ2800, resulting in a catalogue of 3547 BALQSOs. Two corrections, based on extensive testing of synthetic BALQSO spectra, are applied in order to estimate the intrinsic fraction of C IV BALQSOs. First, the probability of an observed BALQSO spectrum being identified as such by our algorithm is calculated as a function of redshift, signal-to-noise ratio and BAL properties. Secondly, the different completenesses of the SDSS target selection algorithm for BALQSOs and non-BAL quasars are quantified. Combining the detection probabilities with an intrinsic E(B-V) distribution capable of reproducing the observed increase in mean E(B-V) with increasing redshift, the intrinsic C IV BALQSO fraction is 41 ± 5 per cent. Our analysis of the selection effects allows us to measure the dependence of the intrinsic C IV BALQSO fraction on luminosity and redshift. We find a factor of 3.5 ± 0.4 decrease in the intrinsic fraction from the highest redshifts, z≃ 4.0, down to z≃ 2.0. The redshift dependence implies that an orientation effect alone is not sufficient to explain the presence of BAL troughs in some but not all quasar spectra. Our results are consistent with the intrinsic BALQSO fraction having no strong luminosity dependence, although with 3σ limits on the rate of change of the intrinsic fraction with luminosity of -6.9 and 7.0 per cent dex-1 we are unable to rule out such a dependence.

  8. Absorption-line survey of 32 QSOs at red wavelengths - properties of the Mg II absorbers

    SciTech Connect

    Lanzetta, K.M.; Wolfe, A.M.; Turnshek, D.A.

    1987-11-01

    The results of a survey of 32 QSOs for Mg II absorption at red wavelengths are presented, and the properties of the metal absorption systems are investigated. When interpreted in terms of ejection, the Mg II absorption systems are randomly distributed in velocity relative to the QSOs, although the systems may cluster on scales of a few thousand km/s. This is consistent with the absorption systems arising in intervening material not associated with the QSOs. The equivalent width distribution of the Mg II systems is well fitted by either an exponential or a power-law distribution, with the number density of the absorption systems increasing with decreasing rest equivalent width. There is marginally significant evidence for cosmological evolution of the number density of the Mg II absorbers, and no evidence for evolution of the Mg II equivalent width distribution with redshift. 42 references.

  9. Invisible Active Galactic Nuclei. II. Radio Morphologies and Five New H i 21cm Absorption Line Detectors

    NASA Astrophysics Data System (ADS)

    Yan, Ting; Stocke, John T.; Darling, Jeremy; Momjian, Emmanuel; Sharma, Soniya; Kanekar, Nissim

    2016-03-01

    This is the second paper directed toward finding new highly redshifted atomic and molecular absorption lines at radio frequencies. To this end, we selected a sample of 80 candidates for obscured radio-loud active galactic nuclei (AGNs) and presented their basic optical/near-infrared (NIR) properties in Paper I. In this paper, we present both high-resolution radio continuum images for all of these sources and H i 21 cm absorption spectroscopy for a few selected sources in this sample. A-configuration 4.9 and 8.5 GHz Very Large Array continuum observations find that 52 sources are compact or have substantial compact components with size <0.″5 and flux densities >0.1 Jy at 4.9 GHz. The 36 most compact sources were then observed with the Very Long Baseline Array at 1.4 GHz. One definite and 10 candidate Compact Symmetric Objects (CSOs) are newly identified, which is a detection rate of CSOs ∼three times higher than the detection rate previously found in purely flux-limited samples. Based on possessing compact components with high flux densities, 60 of these sources are good candidates for absorption-line searches. Twenty-seven sources were observed for H i 21 cm absorption at their photometric or spectroscopic redshifts with only six detections (five definite and one tentative). However, five of these were from a small subset of six CSOs with pure galaxy optical/NIR spectra (i.e., any AGN emission is obscured) and for which accurate spectroscopic redshifts place the redshifted 21 cm line in a radio frequency intereference (RFI)-free spectral “window” (i.e., the percentage of H i 21 cm absorption-line detections could be as high as ∼90% in this sample). It is likely that the presence of ubiquitous RFI and the absence of accurate spectroscopic redshifts preclude H i detections in similar sources (only 1 detection out of the remaining 22 sources observed, 13 of which have only photometric redshifts); that is, H i absorption may well be present but is masked by

  10. K-H2 line shapes for the spectra of cool brown dwarfs

    NASA Astrophysics Data System (ADS)

    Allard, N. F.; Spiegelman, F.; Kielkopf, J. F.

    2016-05-01

    Observations of cooler and cooler brown dwarfs show that the contribution from broadening at many bars pressure is becoming important. The opacity in the red optical to near-IR region under these conditions is dominated by the extremely pressure-broadened wings of the alkali resonance lines, in particular, the K I resonance doublet at 0.77 μm. Collisions with H2 are preponderant in brown dwarf atmospheres at an effective temperature of about 1000 K; the H2 perturber densities reach several 1019 even in Jupiter-mass planets and exceed 1020 for super-Jupiters and older Y dwarfs. As a consequence, it appears that when the far wing absorption due to alkali atoms in a dense H2 atmosphere is significant, accurate pressure broadened profiles that are valid at high densities of H2 should be incorporated into spectral models. The opacity tables are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/589/A21

  11. K-H2 line shapes for the spectra of cool brown dwarfs

    NASA Astrophysics Data System (ADS)

    Allard, N. F.; Spiegelman, F.; Kielkopf, J. F.

    2016-04-01

    Observations of cooler and cooler brown dwarfs show that the contribution from broadening at many bars pressure is becoming important. The opacity in the red optical to near-IR region under these conditions is dominated by the extremely pressure-broadened wings of the alkali resonance lines, in particular, the K I resonance doublet at 0.77 μm. Collisions with H2 are preponderant in brown dwarf atmospheres at an effective temperature of about 1000 K; the H2 perturber densities reach several 1019 even in Jupiter-mass planets and exceed 1020 for super-Jupiters and older Y dwarfs. As a consequence, it appears that when the far wing absorption due to alkali atoms in a dense H2 atmosphere is significant, accurate pressure broadened profiles that are valid at high densities of H2 should be incorporated into spectral models. The opacity tables are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/589/A21

  12. Reconstruction of combustion temperature and gas concentration distributions using line-of-sight tunable diode laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Zhirong; Sun, Pengshuai; Pang, Tao; Xia, Hua; Cui, Xiaojuan; Li, Zhe; Han, Luo; Wu, Bian; Wang, Yu; Sigrist, Markus W.; Dong, Fengzhong

    2016-07-01

    Spatial temperature and gas concentration distributions are crucial for combustion studies to characterize the combustion position and to evaluate the combustion regime and the released heat quantity. Optical computer tomography (CT) enables the reconstruction of temperature and gas concentration fields in a flame on the basis of line-of-sight tunable diode laser absorption spectroscopy (LOS-TDLAS). A pair of H2O absorption lines at wavelengths 1395.51 and 1395.69 nm is selected. Temperature and H2O concentration distributions for a flat flame furnace are calculated by superimposing two absorption peaks with a discrete algebraic iterative algorithm and a mathematical fitting algorithm. By comparison, direct absorption spectroscopy measurements agree well with the thermocouple measurements and yield a good correlation. The CT reconstruction data of different air-to-fuel ratio combustion conditions (incomplete combustion and full combustion) and three different types of burners (one, two, and three flat flame furnaces) demonstrate that TDLAS has the potential of short response time and enables real-time temperature and gas concentration distribution measurements for combustion diagnosis.

  13. Searching for narrow absorption and emission lines in XMM-Newton spectra of gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Campana, S.; Braito, V.; D'Avanzo, P.; Ghirlanda, G.; Melandri, A.; Pescalli, A.; Salafia, O. S.; Salvaterra, R.; Tagliaferri, G.; Vergani, S. D.

    2016-08-01

    We present the results of a spectroscopic search for narrow emission and absorption features in the X-ray spectra of long gamma-ray burst (GRB) afterglows. Using XMM-Newton data, both EPIC and RGS spectra, of six bright (fluence > 10-7 erg cm-2) and relatively nearby (z = 0.54-1.41) GRBs, we performed a blind search for emission or absorption lines that could be related to a high cloud density or metal-rich gas in the environ close to the GRBs. We detected five emission features in four of the six GRBs with an overall statistical significance, assessed through Monte Carlo simulations, of ≲ 3.0σ. Most of the lines are detected around the observed energy of the oxygen edge at ~ 0.5 keV, suggesting that they are not related to the GRB environment but are most likely of Galactic origin. No significant absorption features were detected. A spectral fitting with a free Galactic column density (NH) testing different models for the Galactic absorption confirms this origin because we found an indication of an excess of Galactic NH in these four GRBs with respect to the tabulated values.

  14. Real-time trace gas sensor using a multimode diode laser and multiple-line integrated cavity enhanced absorption spectroscopy.

    PubMed

    Karpf, Andreas; Rao, Gottipaty N

    2015-07-01

    We describe and demonstrate a highly sensitive trace gas sensor based on a simplified design that is capable of measuring sub-ppb concentrations of NO2 in tens of milliseconds. The sensor makes use of a relatively inexpensive Fabry-Perot diode laser to conduct off-axis cavity enhanced spectroscopy. The broad frequency range of a multimode Fabry-Perot diode laser spans a large number of absorption lines, thereby removing the need for a single-frequency tunable laser source. The use of cavity enhanced absorption spectroscopy enhances the sensitivity of the sensor by providing a pathlength on the order of 1 km in a small volume. Off-axis alignment excites a large number of cavity modes simultaneously, thereby reducing the sensor's susceptibility to vibration. Multiple-line integrated absorption spectroscopy (where one integrates the absorption spectra over a large number of rovibronic transitions of the molecular species) further improves the sensitivity of detection. Relatively high laser power (∼400  mW) is used to compensate for the low coupling efficiency of a broad linewidth laser to the optical cavity. The approach was demonstrated using a 407 nm diode laser to detect trace quantities of NO2 in zero air. Sensitivities of 750 ppt, 110 ppt, and 65 ppt were achieved using integration times of 50 ms, 5 s, and 20 s respectively. PMID:26193156

  15. Higher-order mode absorption measurement of X-band choke-mode cavities in a radial line structure

    NASA Astrophysics Data System (ADS)

    Zha, Hao; Shi, Jiaru; Wu, Xiaowei; Chen, Huaibi

    2016-04-01

    An experiment is presented to study the higher-order mode (HOM) suppression of X-band choke-mode structures with a vector network analyzer (VNA). Specific radial line disks were built to test the reflection from the corresponding damping load and different choke geometries. The mismatch between the radial lines and the VNA was calibrated through a special multi-short-load calibration method. The measured reflections of different choke geometries showed good agreement with the theoretical calculations and verified the HOM absorption feature of each geometric design.

  16. Formation of a Giant Galactic Gaseous Halo: Metal-Absorption Lines and High-Velocity Clouds

    NASA Astrophysics Data System (ADS)

    Li, Fan

    1992-04-01

    A Galactic gaseous halo formed through the interstellar disk-halo connection is simulated by means of a two-dimensional axisymmetric hydrodynamic code based upon the chimney model of the interstellar medium, a new version of the galactic fountain. Galactic rotation, heating processes by diffuse UV flux, and radiative cooling processes are taken into account. The resulting gaseous halo can be divided into three categories, i.e., wind-type halo, bound-type halo, and cooled-type halo. In this way, we try to reproduce the column densities of C IV, N V, O VI, and Si IV in the observed absorption lines of halo stars. Assuming that the radiatively cooled halo gas condenses into clouds due to thermal instabilities, we can calculate their distribution and ballistic motions in the Galactic gravitational field. These correspond to the high- and intermediate-velocity clouds observed at high Galactic latitudes. We find that a cooled-type halo with a gas temperature between 5 X 10^5 and 10^6 K and a density between 10^-3 and 10^-2 cm^-3 at the disk-halo interface can reproduce the observational facts about our Galaxy. Supposing that the metal-absorption-line systems of QSOs arise from the halos of intervening galaxies formed by similar processes, we calculate features of the Ca II, Mg II, C IV, and Si IV absorption lines in various stages of galactic evolution. We conclude that C IV systems which are greater than 50 kpc in size correspond to the wind-type halo. On the other hand, Mg II and Ca II systems can only be detected in a very restricted region ( Metaxa, SMALL FAINT CLUSTERS IN THE LMC This is a short review of the main results of my Ph.D. thesis concerning some important problems on the dynamical properties of the LMC star clusters. The topic of this thesis was to find and study the dynamical paramters (tidal radius r_t core radius r_c concentration parameters log (r_t/r_c), and total mass M) for a large sample of small LMC clusters and to define their location in the

  17. Hydrodynamical simulations of the jet in the symbiotic star MWC 560. I. Structure, emission and synthetic absorption line profiles

    NASA Astrophysics Data System (ADS)

    Stute, M.; Camenzind, M.; Schmid, H. M.

    2005-01-01

    We performed hydrodynamical simulations with and without radiative cooling of jet models with parameters representative of the symbiotic system MWC 560. For symbiotic systems we have to perform jet simulations of a pulsed underdense jet in a high density ambient medium. We present the jet structure resulting from our simulations and calculate emission plots which account for expected radiative processes. In addition, our calculations provide expansion velocities for the jet bow shock, the density and temperature structure in the jet, and the propagation and evolution of the jet pulses. In MWC 560 the jet axis is parallel to the line of sight so that the outflowing jet gas can be seen as blue shifted, variable absorption lines in the continuum of the underlying jet source. Based on our simulations we calculate and discuss synthetic absorption profiles. Based on a detailed comparison between model spectra and observations we discuss our hydrodynamical calculations for a pulsed jet in MWC 560 and suggest improvements for future models. Figures \\ref{skizze}, \\ref{modi_det}, \\ref{slice_cool_p}, \\ref{NV_3.0_synch}, \\ref{modelicool_greyscale}, \\ref{line_rem}-\\ref{line_dv} and \\ref{line_zmax} are only available in electronic form at http://www.edpsciences.org

  18. Broad Balmer Absorption Line Variability: Evidence of Gas Transverse Motion in the QSO SDSS J125942.80+121312.6

    NASA Astrophysics Data System (ADS)

    Shi, Xiheng; Zhou, Hongyan; Shu, Xinwen; Zhang, Shaohua; Ji, Tuo; Pan, Xiang; Sun, Luming; Zhao, Wen; Hao, Lei

    2016-03-01

    We report on the discovery of broad Balmer absorption lines variability in the QSO SDSS J125942.80+121312.6, based on the optical and near-infrared spectra taken from the SDSS-I, SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS), and TripleSpec observations over a timescale of 5.8 years in the QSO's rest-frame. The blueshifted absorption profile of Hβ shows a variation of more than 5σ at a high velocity portion (\\gt 3000 {km} {{{s}}}-1) of the trough. We perform a detailed analysis for the physical conditions of the absorber using Balmer lines as well as metastable He i and optical Fe ii absorptions (λ4233 from b4P5/2 level and λ5169 from a6S5/2) at the same velocity. These Fe ii lines are identified in the QSO spectra for the first time. According to the photoionization simulations, we estimate a gas density of n({{H}})≈ {10}9.1 {{cm}}-3 and a column density of {N}{col}({{H}})≈ {10}23 {{cm}}-2 for the BOSS data, but the model fails to predict the variations of ionic column densities between the SDSS and BOSS observations if changes in ionizing flux are assumed. We thus propose transverse motion of the absorbing gas being the cause of the observed broad Balmer absorption line variability. In fact, we find that the changes in covering factors of the absorber can well-reproduce all of the observed variations. The absorber is estimated ∼0.94 pc away from the central engine, which is where the outflow likely experiences deceleration due to the collision with the surrounding medium. This scheme is consistent with the argument that LoBAL QSOs may represent the transition from obscured star-forming galaxies to classic QSOs.

  19. Absorption lines from magnetically driven winds in X-ray binaries

    NASA Astrophysics Data System (ADS)

    Chakravorty, S.; Petrucci, P.-O.; Ferreira, J.; Henri, G.; Belmont, R.; Clavel, M.; Corbel, S.; Rodriguez, J.; Coriat, M.; Drappeau, S.; Malzac, J.

    2016-05-01

    Context. High resolution X-ray spectra of black hole X-ray binaries (BHBs) show blueshifted absorption lines suggesting the presence of outflowing winds. Furthermore, observations show that the disk winds are equatorial and they occur in the Softer (disk dominated) states of the outburst and are less prominent or absent in the Harder (power-law dominated) states. Aims: We want to test whether the self-similar magneto-hydrodynamic (MHD) accretion-ejection models can explain the observational results for accretion disk winds in BHBs. In our models, the density at the base of the outflow from the accretion disk is not a free parameter. This mass loading is determined by solving the full set of dynamical MHD equations without neglecting any physical term. Thus, the physical properties of the outflow depend on and are controlled by the global structure of the disk. Methods: We studied different MHD solutions characterized by different values of the disk aspect ratio (ɛ) and the ejection efficiency (p). We also generate two kinds of MHD solutions depending on the absence (cold solution) or presence (warm solution) of heating at the disk surface. Such heating could be either from dissipation of energy due to MHD turbulence in the disk or from illumination of the disk surface. Warm solutions can have large (>0.1) values of p, which would imply larger wind mass loading at the base of the outflow. We use each of these MHD solutions to predict the physical parameters (distance, density, velocity, magnetic field, etc.) of an outflow. Motivated by observational results, we have put limits on the ionization parameter (ξ), column density, and timescales. Further constraints were derived for the allowed values of ξ from thermodynamic instability considerations, particularly for the Hard SED. These physical constraints were imposed on each of these outflows to select regions within it, which are consistent with the observed winds. Results: The cold MHD solutions are found to be

  20. Detecting the Warm-Hot Intergalactic Medium through X-Ray Absorption Lines

    NASA Astrophysics Data System (ADS)

    Yao, Yangsen; Shull, J. Michael; Wang, Q. Daniel; Cash, Webster

    2012-02-01

    The warm-hot intergalactic medium (WHIM) at temperatures 105-107 K is believed to contain 30%-50% of the baryons in the local universe. However, all current X-ray detections of the WHIM at redshifts z > 0 are of low statistical significance (lsim 3σ) and/or controversial. In this work, we aim to establish the detection limits of current X-ray observatories and explore requirements for next-generation X-ray telescopes for studying the WHIM through X-ray absorption lines. We analyze all available grating observations of Mrk 421 and obtain spectra with signal-to-noise ratios (S/Ns) of ~90 and 190 per 50 mÅ spectral bin from Chandra and XMM-Newton observations, respectively. Although these spectra are two of the best ever collected with Chandra and XMM-Newton, we cannot confirm the two WHIM systems reported by Nicastro et al. in 2005. Our bootstrap simulations indicate that spectra with such high S/N cannot constrain the WHIM with O VII column densities N_{O VII}≈ 10^{15} cm^{-2} (corresponding to an equivalent width of 2.5 mÅ for a Doppler velocity of 50 km s-1) at >~ 3σ significance level. The simulation results also suggest that it would take >60 Ms for Chandra and 140 Ms for XMM-Newton to measure the N_{OVII} at >=4σ from a spectrum of a background QSO with flux of ~0.2 mCrab (1 Crab = 2 × 10-8 erg s-1 cm-2 at 0.5-2 keV). Future X-ray spectrographs need to be equipped with spectral resolution R ~ 4000 and effective area A >= 100 cm2 to accomplish the similar constraints with an exposure time of ~2 Ms and would require ~11 Ms to survey the 15 QSOs with flux >~ 0.2 mCrab along which clear intergalactic O VI absorbers have been detected.

  1. The hydration dependence of CaCO3 absorption lines in the Far IR

    NASA Astrophysics Data System (ADS)

    Powell, Johnny; Emery, Logan P

    2014-06-01

    The far infrared (FIR) absorption lines of CaCO3 have been measured at a range of relative humidities (RH) between 33 and 92% RH using a Bruker 66v/S spectrometer. Hydration measurements on CaCO3 have been made in the mid-infrared (MIR) by [Al-Hosney, H.A. and Grassian, V.H., 2005, Phys. Chem. Chem. Phys., 7, 1266], and astrophysically-motivated temperature-dependent FIR measurements of CaCO3 in vacuum have also been reported [Posch, T., et al., 2007, Ap. J., 668, 993]. The custom sample cell constructed for these hydrated-FIR spectra is required because the 66v/S bench is under vacuum (3 mbar) during typical measurements. Briefly, the sample cell consists of two Thalium Bromoiodide (KRS-5) windows, four O-rings, a plastic ring for separating the windows and providing a volume for the saturated atmosphere. CaCO3 was deposited on KRS-5 windows using doubly-distilled water as an intermediary. The KRS-5 window with sample and assembled sample cell were placed in a desiccator with the appropriated saturated salt solution [Washburn, E.W. (Ed.), International Critical Tables of Numerical Data, Physics Chemistry and Technology, Vol. 1, (McGraw-Hill, New York, 1926), p. 67-68] and allowed to hydrate for 23 hours. For spectroscopy the desiccator was quickly opened and the second KRS-5 window placed in the cell to seal the chamber. A spectrum was then taken of the sample at the appropriate RH. The spectra taken characterize the adsorption of water vapor and CaCO3 that might occur in circumstellar environments [Melnick, G.J., et al. 2001, Nature, 412, 160].The MIR and FIR reflectance spectra of calcite (CaCO3) have been thoroughly studied by [Hellwege, K.H., et al., 1970, Z. Physik, 232, 61]. Five Lorentzian curves were fit to our data in the range from 378-222 cm-1/SUP> and each was able to be assigned to a known mode of CaCO3. The data does not support the conclusion of a hydration effect on these modes of CaCO3, but it does suggest a possible broadening of three modes

  2. X-ray Weak Broad-line Qquasars: Absorption or Intrinsic X-ray Weakness

    NASA Technical Reports Server (NTRS)

    Mushotzky, Richard (Technical Monitor); Risaliti, Guida

    2005-01-01

    XMM observations of X-ray weak quasars have been performed during 2003 and 2004. The data for all the observations have become available in 2004 (there has been a delay of several months on the initial schedule, due to high background flares which contaminated the observations: as a consequence, most of them had to be rescheduled). We have reduced and analyzed all the data, and obtained interesting scientific results. Out of the eight sources, 4 are confirmed to be extremely X-ray weak, in agreement with the results of previous Chandra observations. 3 sources are confined to be highly variable both in flux (by factor 20-50) and in spectral properties (dramatic changes in spectral index). For both these groups of objects we are completing a publication: 1) For the X-ray weak sources, a paper is submitted with a complete analysis of the X-ray spectra both from Chandra and XMM-Newton, and a comparison with optical and near-IR photometry obtained from all-sky surveys. Possible models for the unusual spectral energy distribution of these sources are also presented. 2) For the variable sources, a paper is being finalized where the X-ray spectra obtained with XMM-Newton are compared with previous X-ray observations and with observations at other wavelengths. It is shown that these sources are high luminosity and extreme cases of the highly variable class of narrow-line Seyfert Is. In order to further understand the nature of these X-ray weak quasars, we submitted proposals for spectroscopy at optical and infrared telescopes. We obtained time at the TNG 4 meter telescope for near-IR observations and at the Hobby-Eberly Telescope for optical high-resolution spectroscopy. These observations have been performed in early 2004. They will complement the XMM data and will lead to understanding of whether the X-ray weakness of these sources is an intrinsic property or is due to absorption by circum-nuclear material. The infrared spectra of the variable sources have been already

  3. Erasing a false dichotomy: The complex nature of broad absorption line quasars

    NASA Astrophysics Data System (ADS)

    DiPompeo, Michael A.

    The main goal of this thesis is to test the various models proposed to explain the important subclass of quasars known as broad absorption line (BAL) quasars. In particular, I focus on whether viewing angle alone can explain why only a fraction of quasars exhibit BALs in their optical/ultraviolet spectra, or if some other model or combination of models is more likely. Much of the work contained here focuses on radio-selected BAL quasars, a relatively poorly studied class to this point, and so a secondary goal is to provide a detailed analysis of their properties. Finally, I provide a large spectropolarimetric atlas of BAL quasars for use by the community. Using new multi-frequency radio observations of a large sample of BAL quasars, and a carefully selected, well-matched sample of unabsorbed quasars, I show that there does appear to be an overabundance of steep-spectrum BAL sources, though they cover a wide range of spectral slopes. Monte-Carlo modeling of these distributions show that BAL quasars are seen from a range of viewing angles, including all of the viewing angles that unabsorbed quasars are seen from. However, at the largest viewing angles, we will generally see BAL quasars. No other spectral features or quasar outflow properties correlate with viewing angle, suggesting that BAL winds in all directions are driven by the same mechanism. BAL quasars are indeed more likely to be polarized than non-BAL sources. However, this is not simply due to orientation or extinction of the direct un-polarized continuum light, as polarization does not correlate with viewing angle or dust extinction. It seems that there is much variation in the polarizing scattering material, both in its location and geometry, between individual sources. This makes it difficult to use polarization studies to constrain BAL quasar models, though it is likely useful for detailed study of individual objects. Simple explanations using only one parameter are clearly no longer sufficient, and we

  4. Multiple Velocity Components of Narrow-lined Absorption Arising from the Ejecta of AG Car, P Cyg, and Eta Car.

    NASA Astrophysics Data System (ADS)

    Vieira Kober, Gladys; Gull, T. R.; Bruhweiler, F.; Nielsen, K. E.; Hill, G.

    2007-12-01

    Luminous Blue Variables (LBVs) are a small group of massive objects, with a past characterized by occasional outbursts. Well known members in our galaxy are Eta Car, AG Car, HR Car and P Cyg. HST/STIS observations of Eta Car show a very complex and rich circumstellar absorption spectrum. Of the 20 distinct absorption systems, the ionized strong absorber at -146 km/s (Little Homunculus) shows lines from transitions originating from mainly singly ionized iron-group elements. Curve-of-growth analysis for Fe II lines plus photo-ionization and statistical equilibrium modeling indicated a temperature Te = 6400 K and density n 5x107 cm-3. AG Car and P Cyg have, like Eta Car, circumstellar nebulae which likely are remnants of typical LBV mass loss events. Spectral analysis of high resolution VLT/UVES data for AG Car and Keck/HIRES data for P Cyg also reveal multiple narrow absorption components with excitation and velocities similar to Eta Car's Little Homunculus. In this poster we present curve-of-growth analysis for Fe II lines for the narrow components around AG Car and P Cyg, and temperature estimates based on level populations for these absorbers. We compare the absorbing features around these three LBVs, providing clues to wind structures and ejections for these massive stars. We thank NASA, STScI, Keck and ESO for providing resources and spectra analyzed in this poster, recorded with HST/STIS, Keck/HIRES and VLT/UVES.

  5. Nature of Asymmetry in the Vibrational Line Shape of Single-Molecule Inelastic Electron Tunneling Spectroscopy with the STM

    NASA Astrophysics Data System (ADS)

    Xu, Chen; Chiang, Chi-lun; Han, Zhumin; Ho, W.

    2016-04-01

    Single molecule vibrational spectroscopy and microscopy was demonstrated in 1998 by inelastic electron tunneling with the scanning tunneling microscope. To date, the discussion of its application has mainly focused on the spatial resolution and the spectral energy and intensity. Here we report on the vibrational line shape for a single carbon monoxide molecule that qualitatively exhibits inversion symmetry when it is transferred from the surface to the tip. The dependence of the line shape on the molecule's asymmetric couplings in the tunnel junction can be understood from theoretical simulation and further validates the mechanisms of inelastic electron tunneling.

  6. Nature of Asymmetry in the Vibrational Line Shape of Single-Molecule Inelastic Electron Tunneling Spectroscopy with the STM.

    PubMed

    Xu, Chen; Chiang, Chi-Lun; Han, Zhumin; Ho, W

    2016-04-22

    Single molecule vibrational spectroscopy and microscopy was demonstrated in 1998 by inelastic electron tunneling with the scanning tunneling microscope. To date, the discussion of its application has mainly focused on the spatial resolution and the spectral energy and intensity. Here we report on the vibrational line shape for a single carbon monoxide molecule that qualitatively exhibits inversion symmetry when it is transferred from the surface to the tip. The dependence of the line shape on the molecule's asymmetric couplings in the tunnel junction can be understood from theoretical simulation and further validates the mechanisms of inelastic electron tunneling. PMID:27152811

  7. Line shape and ray trace calculations in saturated X-ray lasers: Application to Ni-like silver

    NASA Astrophysics Data System (ADS)

    Benredjem, D.; Guilbaud, O.; Möller, C.; Klisnick, A.; Ros, D.; Dubau, J.; Calisti, A.; Talin, B.

    2006-05-01

    Longitudinal coherence length in X-ray lasers depends strongly on the shape of the amplified line. We have modelled an experiment performed at the LULI facility of Ecole Polytechnique. The experiment was devoted to the study of the temporal (longitudinal) coherence of the transient Ni-like silver 4d 4p transition X-ray laser at 13.9 nm. Accurate line shape calculations using PPP, a spectral line shape code, confirm that the Voigt profile is a good approximation for this X-ray laser line. This allows us to extensively use the Voigt shape in conditions where the amplifier, i.e. the plasma produced by the interaction of a high intensity laser with a slab target, is neither stationary nor homogeneous. Our calculations involve a ray trace code which is a post-processor to the hydrodynamic simulation EHYBRID. As the effect of saturation is important for the level populations and gains we include the interaction between the amplified beam and the medium using the Maxwell-Bloch formalism. While the FWHM of the spontaneous emission profile is ˜10 mÅ, the amplified X-ray line exhibits gain narrowing leading to the smaller width ˜3 mÅ. Comparison with experiment is discussed.

  8. A New Infracture Technique for Reduction Malarplasty with an L-Shaped Osteotomy Line

    PubMed Central

    Lin, Li-Xin; Yuan, Ji-Long; Wang, Yu-Ting; Huang, Yong; Wang, Peng; Wang, Xue-Ming

    2015-01-01

    Background Reduction malarplasty is one of the most common surgical procedures performed in the Asian population for aesthetic purposes. Although multiple methods have been developed for reduction malarplasty, including a variety of infracture techniques, most of the current procedures have limitations. In the current study we created a new infracture method to circumvent these shortcomings. Material/Methods Between January 2004 and October 2013, we applied this novel infracture technique in 700 patients. The highest area of the zygomatic body was marked pre-operatively and ground intra-operatively through an intraoral incision. An L-shaped incomplete osteotomy of the zygomatic body was performed with a reciprocating saw, and then a complete perpendicular osteotomy (1 cm anterior to the articular tubercle of the zygomatic arch) was made through a pre-auricular incision. Light pressure on the posterior part of the arch produced a greenstick fracture of the anterior osteotomy site, resulting in posterior-inward repositioning of the malar complex. Internal fixation was not required. Results Satisfactory aesthetic results and good post-operative stability were achieved. Three months post-operatively, the bone around the zygomatic arc osteotomy line was remodeled. The bone posterior to the articular tubercle of the zygomatic arch was partially absorbed, leading to a depression of the root of the arc and a natural transition on both sides of the osteotomy line, making the midface more slender. Instead, the anterior bone presented with new bones, making the malar complex more stable. Conclusions This new method has multiple advantages, including simple manipulation, no need for internal fixation, short operative and recovery times, and few complications. X-ray images showing the bony changes demonstrated that the infracture technique is an effective and ideal method for reduction malarplasty. PMID:26145181

  9. NEW PERSPECTIVE ON GALAXY OUTFLOWS FROM THE FIRST DETECTION OF BOTH INTRINSIC AND TRAVERSE METAL-LINE ABSORPTION

    SciTech Connect

    Kacprzak, Glenn G.; Cooke, Jeff; Martin, Crystal L.; Ho, Stephanie H.; Bouché, Nicolas; LeReun, Audrey; Schroetter, Ilane; Churchill, Christopher W.; Klimek, Elizabeth

    2014-09-01

    We present the first observation of a galaxy (z = 0.2) that exhibits metal-line absorption back-illuminated by the galaxy (down-the-barrel) and transversely by a background quasar at a projected distance of 58 kpc. Both absorption systems, traced by Mg II, are blueshifted relative to the galaxy systemic velocity. The quasar sight line, which resides almost directly along the projected minor axis of the galaxy, probes Mg I and Mg II absorption obtained from the Keck/Low Resolution Imaging Spectrometer as well as Lyα, Si II, and Si III absorption obtained from the Hubble Space Telescope/Cosmic Origins Spectrograph. For the first time, we combine two independent models used to quantify the outflow properties for down-the-barrel and transverse absorption. We find that the modeled down-the-barrel deprojected outflow velocities range between V {sub dtb} = 45-255 km s{sup –1}. The transverse bi-conical outflow model, assuming constant-velocity flows perpendicular to the disk, requires wind velocities V {sub outflow} = 40-80 km s{sup –1} to reproduce the transverse Mg II absorption kinematics, which is consistent with the range of V {sub dtb}. The galaxy has a metallicity, derived from Hα and N II, of [O/H] = –0.21 ± 0.08, whereas the transverse absorption has [X/H] = –1.12 ± 0.02. The galaxy star formation rate is constrained between 4.6-15 M {sub ☉} yr{sup –1} while the estimated outflow rate ranges between 1.6-4.2 M {sub ☉} yr{sup –1} and yields a wind loading factor ranging between 0.1-0.9. The galaxy and gas metallicities, the galaxy-quasar sight-line geometry, and the down-the-barrel and transverse modeled outflow velocities collectively suggest that the transverse gas originates from ongoing outflowing material from the galaxy. The ∼1 dex decrease in metallicity from the base of the outflow to the outer halo suggests metal dilution of the gas by the time it reached 58 kpc.

  10. New Perspective on Galaxy Outflows from the First Detection of Both Intrinsic and Traverse Metal-line Absorption

    NASA Astrophysics Data System (ADS)

    Kacprzak, Glenn G.; Martin, Crystal L.; Bouché, Nicolas; Churchill, Christopher W.; Cooke, Jeff; LeReun, Audrey; Schroetter, Ilane; Ho, Stephanie H.; Klimek, Elizabeth

    2014-09-01

    We present the first observation of a galaxy (z = 0.2) that exhibits metal-line absorption back-illuminated by the galaxy (down-the-barrel) and transversely by a background quasar at a projected distance of 58 kpc. Both absorption systems, traced by Mg II, are blueshifted relative to the galaxy systemic velocity. The quasar sight line, which resides almost directly along the projected minor axis of the galaxy, probes Mg I and Mg II absorption obtained from the Keck/Low Resolution Imaging Spectrometer as well as Lyα, Si II, and Si III absorption obtained from the Hubble Space Telescope/Cosmic Origins Spectrograph. For the first time, we combine two independent models used to quantify the outflow properties for down-the-barrel and transverse absorption. We find that the modeled down-the-barrel deprojected outflow velocities range between V dtb = 45-255 km s-1. The transverse bi-conical outflow model, assuming constant-velocity flows perpendicular to the disk, requires wind velocities V outflow = 40-80 km s-1 to reproduce the transverse Mg II absorption kinematics, which is consistent with the range of V dtb. The galaxy has a metallicity, derived from Hα and N II, of [O/H] = -0.21 ± 0.08, whereas the transverse absorption has [X/H] = -1.12 ± 0.02. The galaxy star formation rate is constrained between 4.6-15 M ⊙ yr-1 while the estimated outflow rate ranges between 1.6-4.2 M ⊙ yr-1 and yields a wind loading factor ranging between 0.1-0.9. The galaxy and gas metallicities, the galaxy-quasar sight-line geometry, and the down-the-barrel and transverse modeled outflow velocities collectively suggest that the transverse gas originates from ongoing outflowing material from the galaxy. The ~1 dex decrease in metallicity from the base of the outflow to the outer halo suggests metal dilution of the gas by the time it reached 58 kpc.

  11. Determination of vibration-rotation lines intensities from absorption Fourier spectra

    NASA Technical Reports Server (NTRS)

    Mandin, J. Y.

    1979-01-01

    The method presented allows the line intensities to be calculated from either their equivalent widths, heights, or quantities deduced from spectra obtained by Fourier spectrometry. This method has proven its effectiveness in measuring intensities of 60 lines of the molecule H2O with a precision of 10%. However, this method cannot be applied to isolated lines.

  12. Metal-line absorption around z ≈ 2.4 star-forming galaxies in the Keck Baryonic Structure Survey

    NASA Astrophysics Data System (ADS)

    Turner, Monica L.; Schaye, Joop; Steidel, Charles C.; Rudie, Gwen C.; Strom, Allison L.

    2014-11-01

    We study metal absorption around 854 z ≈ 2.4 star-forming galaxies taken from the Keck Baryonic Structure Survey. The galaxies examined in this work lie in the fields of 15 hyperluminous background quasi-stellar objects, with galaxy impact parameters ranging from 35 proper kpc (pkpc) to 2 proper Mpc (pMpc). Using the pixel optical depth technique, we present the first galaxy-centred 2D maps of the median absorption by O VI, N V, C IV, C III, and Si IV, as well as updated results for H I. At small galactocentric radii we detect a strong enhancement of the absorption relative to randomly located regions that extend out to at least 180 pkpc in the transverse direction, and ±240 km s-1 along the line of sight (LOS, ˜1 pMpc in the case of pure Hubble flow) for all ions except N V. For C IV (and H I) we detect a significant enhancement of the absorption signal out to 2 pMpc in the transverse direction, corresponding to the maximum impact parameter in our sample. After normalizing the median absorption profiles to account for variations in line strengths and detection limits, in the transverse direction we find no evidence for a sharp drop-off in metals distinct from that of H I. We argue instead that non-detection of some metal-line species in the extended circumgalactic medium is consistent with differences in the detection sensitivity. Along the LOS, the normalized profiles reveal that the enhancement in the absorption is more extended for O VI, C IV, and Si IV than for H I. We also present measurements of the scatter in the pixel optical depths, covering fractions, and equivalent widths as a function of projected galaxy distance. Limiting the sample to the 340 galaxies with redshifts measured from nebular emission lines does not decrease the extent of the enhancement along the LOS compared to that in the transverse direction. This rules out redshift errors as the source of the observed redshift-space anisotropy and thus implies that we have detected the signature

  13. Beyond Zeeman spectroscopy: Magnetic-field diagnostics with Stark-dominated line shapes

    SciTech Connect

    Tessarin, S.; Mikitchuk, D.; Doron, R.; Stambulchik, E.; Kroupp, E.; Maron, Y.; Hammer, D. A.; Jacobs, V. L.; Seely, J. F.; Oliver, B. V.; Fisher, A.

    2011-09-15

    A recently suggested spectroscopic approach for magnetic-field determination in plasma is employed to measure magnetic fields in an expanding laser-produced plasma plume in an externally applied magnetic field. The approach enables the field determination in a diagnostically difficult regime for which the Zeeman-split patterns are not resolvable, as is often encountered under the conditions characteristic of high-energy-density plasmas. Here, such conditions occur in the high-density plasma near the laser target, due to the dominance of Stark broadening. A pulsed-power system is used to generate magnetic fields with a peak magnitude of 25 T at the inner-electrode surface in a coaxial configuration. An aluminum target attached to the inner electrode surface is then irradiated by a laser beam to produce the expanding plasma that interacts with the applied azimuthal magnetic field. A line-shape analysis of the Al III 4s-4p doublet (5696 and 5722 A) enables the simultaneous determination of the magnetic field and the electron density. The measured magnetic fields are generally found to agree with those expected in a vacuum based on the pulsed-power system current. Examples of other transitions that can be used to diagnose a wide range of plasma and magnetic field parameters are presented.

  14. Laboratory investigation on the role of tubular shaped micro resonators phononic crystal insertion on the absorption coefficient of profiled sound absorber

    NASA Astrophysics Data System (ADS)

    Yahya, I.; Kusuma, J. I.; Harjana; Kristiani, R.; Hanina, R.

    2016-02-01

    This paper emphasizes the influence of tubular shaped microresonators phononic crystal insertion on the sound absorption coefficient of profiled sound absorber. A simple cubic and two different bodies centered cubic phononic crystal lattice model were analyzed in a laboratory test procedure. The experiment was conducted by using transfer function based two microphone impedance tube method refer to ASTM E-1050-98. The results show that sound absorption coefficient increase significantly at the mid and high-frequency band (600 - 700 Hz) and (1 - 1.6 kHz) when tubular shaped microresonator phononic crystal inserted into the tested sound absorber element. The increment phenomena related to multi-resonance effect that occurs when sound waves propagate through the phononic crystal lattice model that produce multiple reflections and scattering in mid and high-frequency band which increases the sound absorption coefficient accordingly

  15. 1E 0104.2 + 3153 - A broad absorption-line QSO viewed through a giant elliptical galaxy

    NASA Technical Reports Server (NTRS)

    Stocke, J. T.; Liebert, J.; Schild, R.; Gioia, I. M.; Maccacaro, T.

    1984-01-01

    The optical identification of the X-ray source 1E 0104.2 + 3153 is complicated by the close projection of a broad absorption-line (BAL) QSO (z = 2.027) 10 arcsec from a giant elliptical galaxy (z = 0.111) at the center of a compact group of galaxies. At only 1.2 de Vaucouleur radii (16 kpc for H sub 0 = 100 km/s Mpc) this QSO-galaxy projection is the closest yet discovered. Based upon current observations, the source of the X-ray emission cannot be conclusively determined. Present in the BAL QSO spectrum are extremely strong Ca II H and K absorption lines due to the intervening galaxy, the first optical detection of the cold interstellar medium in an elliptical galaxy. The strength of these lines (EW = 2 and 1 A) requires observation through several interstellar clouds in the line of sight to the QSO. By its proximity to the central regions of the elliptical galaxy and the relative distances of the galaxy and QSO, this QSO is a particularly good candidate for observing dramatic transient gravitational lensing phenomena due to halo stars in the foreground galaxy.

  16. Variability of broad absorption lines in QSO SDSS J022844.09+000217.0 on multiyear time-scales

    NASA Astrophysics Data System (ADS)

    He, Zhi-Cheng; Bian, Wei-Hao; Jiang, Xiao-Lei; Wang, Yue-Feng

    2014-09-01

    The variability of broad absorption lines is investigated for a broad-absorption-line (BAL) quasar (QSO), SDSS J022844.09+000217.0 (z = 2.719), with 18 Sloan Digital Sky Survey (SDSS)/Baryon Oscillation Spectroscopic Survey (BOSS) spectra covering 4128 d in the observed frame. Using the ratio of the root-mean-square (rms) spectrum to the mean spectrum, the relative flux change of the BAL trough is larger than that of the emission lines and the continuum. Fitting a power-law continuum and the emission-line profiles of C IV λ1549 and Si IVλ1399, we calculate the equivalent width (EW) for different epochs, as well as the continuum luminosity and the spectral index. It is found that there is a strong correlation between the BAL-trough EW and the spectral index and a weak negative correlation between the BAL-trough EW and the continuum luminosity. The strong correlation between the BAL-trough EW and the spectral index for this particular QSO suggests that dust is intrinsic to outflows. The weak correlation between the BAL variability and the continuum luminosity for this particular QSO implies that the BAL-trough variation is not dominated by photoionization.

  17. ABSORPTION-LINE PROBES OF THE PREVALENCE AND PROPERTIES OF OUTFLOWS IN PRESENT-DAY STAR-FORMING GALAXIES

    SciTech Connect

    Chen Yanmei; Kauffmann, Guinevere; Wang Jing; Tremonti, Christy A.; Heckman, Timothy M.; Weiner, Benjamin J.; Brinchmann, Jarle

    2010-08-15

    We analyze star-forming galaxies drawn from SDSS DR7 to show how the interstellar medium (ISM) Na I {lambda}{lambda}5890, 5896 (Na D) absorption lines depend on galaxy physical properties, and to look for evidence of galactic winds. We combine the spectra of galaxies with similar geometry/physical parameters to create composite spectra with signal-to-noise {approx}300. The stellar continuum is modeled using stellar population synthesis models, and the continuum-normalized spectrum is fit with two Na I absorption components. We find that (1) ISM Na D absorption lines with equivalent widths EW > 0.8 A are only prevalent in disk galaxies with specific properties-large extinction (A{sub V} ), high star formation rates (SFR), high SFR per unit area ({Sigma}{sub SFR}), or high stellar mass (M{sub *}); (2) the ISM Na D absorption lines can be separated into two components: a quiescent disk-like component at the galaxy systemic velocity and an outflow component; (3) the disk-like component is much stronger in the edge-on systems, and the outflow component covers a wide angle but is stronger within 60{sup 0} of the disk rotation axis; (4) the EW and covering factor of the disk component correlate strongly with dust attenuation, highlighting the importance that dust shielding may play in the survival of Na I; (5) the EW of the outflow component depends primarily on {Sigma}{sub SFR} and secondarily on A{sub V} ; and (6) the outflow velocity varies from {approx}120 to 160 km s{sup -1} but shows little hint of a correlation with galaxy physical properties over the modest dynamic range that our sample probes (1.2 dex in log {Sigma}{sub SFR} and 1 dex in log M{sub *}).

  18. Noodles and stars allow a precise and efficient calculation of the Z-line shape and the polarization asymmetry

    SciTech Connect

    Jung-Choon Im, C. Department of Physics, Stanford University, Stanford, CA 94305 )

    1990-03-05

    We give a pedagogical introduction to the star functions and the Noodle method. The {ital Z}-line shape and the polarization asymmetry at SLC/LEP can be evaluated elegantly and efficiently using the star functions and the Noodle method.

  19. Collision-induced line-shape effects limiting the accuracy in Doppler-limited spectroscopy of H2

    NASA Astrophysics Data System (ADS)

    Wcisło, P.; Gordon, I. E.; Cheng, C.-F.; Hu, S.-M.; Ciuryło, R.

    2016-02-01

    Recent advances in theoretical calculations of H2 dissociation energies and ultra-accurate measurements of H2 transition frequencies give possibilities not only for testing QED and relativistic effects, but also for searching for physics beyond the standard model. In this paper we show that at the level of 10-4cm-1 the uncertainty of the Doppler-limited H2 line position determination is dominated by collisional line-shape effects. We question the paradigm that the unperturbed transition energy can be determined from linear extrapolation of the line shift to zero pressure.

  20. Exoplanets or Dynamic Atmospheres? The Radial Velocity and Line Shape Variations of 51 Pegasi and τ Bootis

    NASA Astrophysics Data System (ADS)

    Brown, Timothy M.; Kotak, Rubina; Horner, Scott D.; J. Kennelly, Edward; Korzennik, Sylvain; Nisenson, P.; Noyes, Robert W.

    1998-07-01

    The stars 51 Pegasi and τ Bootis show radial velocity variations that have been interpreted as resulting from companions with roughly Jovian mass and orbital periods of a few days. Gray and Gray & Hatzes reported that the radial velocity signal of 51 Peg is synchronous with variations in the shape of the line λ6253 Fe I; thus, they argue that the velocity signal arises not from a companion of planetary mass but from dynamic processes in the atmosphere of the star, possibly nonradial pulsations. Here we seek confirming evidence for line shape or strength variations in both 51 Peg and τ Boo, using R = 50,000 observations taken with the Advanced Fiber Optic Echelle. Because of our relatively low spectral resolution, we compare our observations with Gray's line bisector data by fitting observed line profiles to an expansion in terms of orthogonal (Hermite) functions. To obtain an accurate comparison, we model the emergent line profiles from rotating and pulsating stars, taking the instrumental point-spread function into account. We describe this modeling process in detail. We find no evidence for line profile or strength variations at the radial velocity period in either 51 Peg or in τ Boo. For 51 Peg, our upper limit for line shape variations with 4.23 day periodicity is small enough to exclude with 10 σ confidence the bisector curvature signal reported by Gray & Hatzes; the bisector span and relative line depth signals reported by Gray are also not seen, but in this case with marginal (2 σ) confidence. We cannot, however, exclude pulsations as the source of 51 Peg's radial velocity variation because our models imply that line shape variations associated with pulsations should be much smaller than those computed by Gray & Hatzes; these smaller signals are below the detection limits both for Gray & Hatzes's data and for our own. τ Boo's large radial velocity amplitude and v sin i make it easier to test for pulsations in this star. Again we find no evidence for

  1. Scanning electron microscope measurement of width and shape of 10nm patterned lines using a JMONSEL-modeled library.

    PubMed

    Villarrubia, J S; Vladár, A E; Ming, B; Kline, R J; Sunday, D F; Chawla, J S; List, S

    2015-07-01

    The width and shape of 10nm to 12 nm wide lithographically patterned SiO2 lines were measured in the scanning electron microscope by fitting the measured intensity vs. position to a physics-based model in which the lines' widths and shapes are parameters. The approximately 32 nm pitch sample was patterned at Intel using a state-of-the-art pitch quartering process. Their narrow widths and asymmetrical shapes are representative of near-future generation transistor gates. These pose a challenge: the narrowness because electrons landing near one edge may scatter out of the other, so that the intensity profile at each edge becomes width-dependent, and the asymmetry because the shape requires more parameters to describe and measure. Modeling was performed by JMONSEL (Java Monte Carlo Simulation of Secondary Electrons), which produces a predicted yield vs. position for a given sample shape and composition. The simulator produces a library of predicted profiles for varying sample geometry. Shape parameter values are adjusted until interpolation of the library with those values best matches the measured image. Profiles thereby determined agreed with those determined by transmission electron microscopy and critical dimension small-angle x-ray scattering to better than 1 nm. PMID:25747180

  2. The Fundamental Quadrupole Band of (14)N2: Line Positions from High-Resolution Stratospheric Solar Absorption Spectra

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Zander, R.; Goldman, A.; Murcray, F. J.; Murcray, D. G.; Grunson, M. R.; Farmer, C. B.

    1991-01-01

    The purpose of this note is to report accurate measurements of the positions of O- and S-branch lines of the (1-0) vibration-rotation quadrupole band of molecular nitrogen ((14)N2) and improved Dunham coefficients derived from a simultaneous least-squares analysis of these measurements and selected infrared and far infrared data taken from the literature. The new measurements have been derived from stratospheric solar occultation spectra recorded with Fourier transform spectrometer (FTS) instruments operated at unapodized spectral resolutions of 0.002 and 0.01 /cm. The motivation for the present investigation is the need for improved N2 line parameters for use in IR atmospheric remote sensing investigations. The S branch of the N2 (1-0) quadrupole band is ideal for calibrating the line-of-sight airmasses of atmospheric spectra since the strongest lines are well placed in an atmospheric window, their absorption is relatively insensitive to temperature and is moderately strong (typical line center depths of 10 to 50% in high-resolution ground-based solar spectra and in lower stratospheric solar occultation spectra), and the volume mixing ratio of nitrogen is constant in the atmosphere and well known. However, a recent investigation has'shown the need to improve the accuracies of the N2 fine positions, intensities, air-broadened half-widths, and their temperature dependences to fully exploit this calibration capability (1). The present investigation addresses the problem of improving the accuracy of the N2 line positions.

  3. Attosecond transient absorption of argon atoms in the vacuum ultraviolet region: line energy shifts versus coherent population transfer

    NASA Astrophysics Data System (ADS)

    Cao, Wei; Warrick, Erika R.; Neumark, Daniel M.; Leone, Stephen R.

    2016-01-01

    Using attosecond transient absorption, the dipole response of an argon atom in the vacuum ultraviolet (VUV) region is studied when an external electromagnetic field is present. An isolated attosecond VUV pulse populates Rydberg states lying 15 eV above the argon ground state. A synchronized few-cycle near infrared (NIR) pulse modifies the oscillating dipoles of argon impulsively, leading to alterations in the VUV absorption spectra. As the NIR pulse is delayed with respect to the VUV pulse, multiple features in the absorption profile emerge simultaneously including line broadening, sideband structure, sub-cycle fast modulations, and 5-10 fs slow modulations. These features indicate the coexistence of two general processes of the light-matter interaction: the energy shift of individual atomic levels and coherent population transfer between atomic eigenstates, revealing coherent superpositions. An intuitive formula is derived to treat both effects in a unifying framework, allowing one to identify and quantify the two processes in a single absorption spectrogram.

  4. Evolution of linear absorption and nonlinear optical properties in V-shaped ruthenium(II)-based chromophores.

    PubMed

    Coe, Benjamin J; Foxon, Simon P; Harper, Elizabeth C; Helliwell, Madeleine; Raftery, James; Swanson, Catherine A; Brunschwig, Bruce S; Clays, Koen; Franz, Edith; Garín, Javier; Orduna, Jesús; Horton, Peter N; Hursthouse, Michael B

    2010-02-10

    In this article, we describe a series of complexes with electron-rich cis-{Ru(II)(NH(3))(4)}(2+) centers coordinated to two pyridyl ligands bearing N-methyl/arylpyridinium electron-acceptor groups. These V-shaped dipolar species are new, extended members of a class of chromophores first reported by us (Coe, B. J. et al. J. Am. Chem. Soc. 2005, 127, 4845-4859). They have been isolated as their PF(6)(-) salts and characterized by using various techniques including (1)H NMR and electronic absorption spectroscopies and cyclic voltammetry. Reversible Ru(III/II) waves show that the new complexes are potentially redox-switchable chromophores. Single crystal X-ray structures have been obtained for four complex salts; three of these crystallize noncentrosymmetrically, but with the individual molecular dipoles aligned largely antiparallel. Very large molecular first hyperpolarizabilities beta have been determined by using hyper-Rayleigh scattering (HRS) with an 800 nm laser and also via Stark (electroabsorption) spectroscopic studies on the intense, visible d --> pi* metal-to-ligand charge-transfer (MLCT) and pi --> pi* intraligand charge-transfer (ILCT) bands. The latter measurements afford total nonresonant beta(0) responses as high as ca. 600 x 10(-30) esu. These pseudo-C(2v) chromophores show two substantial components of the beta tensor, beta(zzz) and beta(zyy), although the relative significance of these varies with the physical method applied. According to HRS, beta(zzz) dominates in all cases, whereas the Stark analyses indicate that beta(zyy) is dominant in the shorter chromophores, but beta(zzz) and beta(zyy) are similar for the extended species. In contrast, finite field calculations predict that beta(zyy) is always the major component. Time-dependent density functional theory calculations predict increasing ILCT character for the nominally MLCT transitions and accompanying blue-shifts of the visible absorptions, as the ligand pi-systems are extended. Such unusual

  5. Electron spin resonance of interacting spins in n-Ge: II. Change in the width and shape of lines

    SciTech Connect

    Veinger, A. I.; Zabrodskii, A. G.; Tisnek, T. V. Goloshchapov, S. I.

    2008-11-15

    The effect of spin interaction on the width and shape of the electron spin resonance line in compensated and uncompensated n-Ge:As has been studied. It is shown that, in the case of a magnetic field oriented along the [100] axis, the width of the resonance line decreases irrespective of the degree of compensation as the critical concentration of the insulator-metal transition is approached, owing to enhancement of the exchange interaction of spins and to an increase in the spin relaxation time. When the magnetic field is directed along other axes, an additional line broadening appears in compensated samples. This broadening is determined by the influence exerted on the g factor by fluctuations of the internal electrostatic field via the stresses generated by these fluctuations. For well-conducting samples, in which the thickness of the skin layer becomes smaller than that of the sample, the line takes on an asymmetric (Dysonian) shape. In this case, the ratio between the wings of the derivative, characteristic of this line shape, is determined by the ratio between the rates of spin diffusion and spin relaxation.

  6. Identifying the structure of near-threshold states from the line shape

    NASA Astrophysics Data System (ADS)

    Chen, Guo-Ying; Huo, Wen-Sheng; Zhao, Qiang

    2015-09-01

    We revisit the compositeness theorem proposed by Weinberg in an effective field theory (EFT) and explore criteria which are sensitive to the structure of S-wave threshold states. On a general basis, we show that the wave function renormalization constant Z, which is the probability of finding an elementary component in the wave function of a threshold state, can be explicitly introduced in the description of the threshold state. As an application of this EFT method, we describe the near-threshold line shape of the D*0D̅0 invariant mass spectrum in B→D*0D̅0K and determine a nonvanishing value of Z. It suggests that the X(3872) as a candidate of the D*0D̅0 molecule may still contain a small cc¯ core. This elementary component, on the one hand, explains its production in the B meson decay via a short-distance mechanism, and on the other hand, is correlated with the D*0D̅0 threshold enhancement observed in the D*0D̅0 invariant mass distributions. Meanwhile, we also show that if Z is non-zero, the near-threshold enhancement of the D*0D̅0 mass spectrum in the B decay will be driven by the short-distance production mechanism. Supported by National Natural Science Foundation of China (11147022, 11035006, 11305137), Chinese Academy of Sciences (KJCX2-EW-N01), Ministry of Science and Technology of China (2009CB825200), DFG and NSFC (11261130311) through funds provided to the Sino-German CRC 110 “Symmetries and the Emergence of Structure in QCD”, and Doctor Foundation of Xinjiang University (BS110104)

  7. Linking the evolution of body shape and locomotor biomechanics in bird-line archosaurs.

    PubMed

    Allen, Vivian; Bates, Karl T; Li, Zhiheng; Hutchinson, John R

    2013-05-01

    Locomotion in living birds (Neornithes) has two remarkable features: feather-assisted flight, and the use of unusually crouched hindlimbs for bipedal support and movement. When and how these defining functional traits evolved remains controversial. However, the advent of computer modelling approaches and the discoveries of exceptionally preserved key specimens now make it possible to use quantitative data on whole-body morphology to address the biomechanics underlying this issue. Here we use digital body reconstructions to quantify evolutionary trends in locomotor biomechanics (whole-body proportions and centre-of-mass position) across the clade Archosauria. We use three-dimensional digital reconstruction to estimate body shape from skeletal dimensions for 17 archosaurs along the ancestral bird line, including the exceptionally preserved, feathered taxa Microraptor, Archaeopteryx, Pengornis and Yixianornis, which represent key stages in the evolution of the avian body plan. Rather than a discrete transition from more-upright postures in the basal-most birds (Avialae) and their immediate outgroup deinonychosauria, our results support hypotheses of a gradual, stepwise acquisition of more-crouched limb postures across much of theropod evolution, although we find evidence of an accelerated change within the clade Maniraptora (birds and their closest relatives, such as deinonychosaurs). In addition, whereas reduction of the tail is widely accepted to be the primary morphological factor correlated with centre-of-mass position and, hence, evolution of hindlimb posture, we instead find that enlargement of the pectoral limb and several associated trends have a much stronger influence. Intriguingly, our support for the onset of accelerated morpho-functional trends within Maniraptora is closely correlated with the evolution of flight. Because we find that the evolution of enlarged forelimbs is strongly linked, via whole-body centre of mass, to hindlimb function during

  8. Flocculation of deformable emulsion droplets. 1: Droplet shape and line tension effects

    SciTech Connect

    Denkov, N.D.; Petsev, D.N.; Danov, K.D.

    1995-12-01

    A simple theoretical model which allows the study of the configuration and the interaction energy of a doublet of flocculated Brownian droplets was recently proposed (Denkov et al., Phys, Rev. Lett. 71, 3226 (1993)). In this model the equilibrium film radius and thickness are determined by minimizing the total pair interaction energy which is presented as a sum of explicit expressions for the different contributions (van der Waals, electrostatic, steric, depletion, surface extension, etc.). In the present study this simplified model is numerically verified by comparison with the results stemming from the real shape of the interacting droplets. In order to determine the real configuration of two drops in contact the authors solve numerically the augmented Laplace equation of capillarity which accounts for the interaction between the droplets. Then the total interaction energy is alteratively calculated by integrating the energy density along the surfaces of the droplets. The numerical comparison shows that the equilibrium film radius and thickness, as well as the interaction energy calculated by means of the simplified model, are in very good agreement with the results from the more detailed (but more complex) approach. Numerical calculations of the equilibrium line tensions acting at the film periphery, a function of the droplet radius, are performed. The obtained results are relevant also to flocs containing more than two particles since the theory predicts pairwise additivity of the interaction energy in most cases. The results can be useful in gaining a deeper understanding of the processes of stabilization of flocculation in emulsions. Emulsions of great importance in many areas of human activity such as oil recovery.

  9. Oscillator strengths of ultraviolet Ni I lines from hook-method and absorption measurements in a furnace

    NASA Technical Reports Server (NTRS)

    Huber, M. C. E.; Sandeman, R. J.

    1980-01-01

    Measurements of the oscillator strengths of the ultraviolet lines of neutral nickel obtained by the use of the combined hook and absorption technique are reported. A total of 221 transitions in the range 1964-4094 A was measured for nickel atoms from a high-temperature graphite furnace (2000-2500 K) using a continuum background source, a Mach-Zehnder interferometer and a 3-m Czerny-Turner spectrograph. Hook and absorption measurements are presented, and radiative lifetimes are derived from log gf values. Comparison of the present values with previous results indicates only those of Bell et al. (1966) and Lennard et al. (1975) to consistently agree with the data presented, although the reliability laser-excitation technique of lifetime measurement is supported over that of Hanle methods.

  10. Measurement of water vapor line strengths in the 1.4-2.7 μm range by tunable diode laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Pogány, Andrea; Klein, Alexander; Ebert, Volker

    2015-11-01

    Line strengths of nine water vapor absorption lines in the wavelength range between 1.37 and 2.71 μm with line strengths of 10-23-10-20 cm/molecule have been measured using direct tunable diode laser absorption spectroscopy (dTDLAS). Four different light sources were used: three distributed feedback (DFB) diode lasers with wavelengths of 1.37 μm, 2.55 μm and 2.71 μm for measuring one application-specifically selected absorption line with each laser, and a vertical-cavity surface-emitting laser (VCSEL) radiating around 1.39 μm for the measurement of six further absorption lines. Despite the different light sources and line strengths, a uniform measurement and data evaluation method was developed and applied to all lines, and the experimental set-up was kept as similar as possible. This allows a thorough and uniform uncertainty analysis and evaluation of the contributions of the individual experimental parameters to the uncertainty of the derived line strengths. A comprehensive and transparent uncertainty analysis is given for the measurements. Uncertainties of our measured line strengths are in the 1.1-2.5% range (k=2, 95% confidence level). Our measured line strength values agree well with line strengths in the HITRAN 2012 database and other literature sources, we realized lower uncertainties up to a factor of 5-10.

  11. Detection of High Velocity Absorption Components in the He I Lines of Eta Carinae near the Time of Periastron

    NASA Technical Reports Server (NTRS)

    Richardson, Noel D.; St-Jean, Lucas; Gull, Theodore R.; Madura, Thomas; Hillier, D. John; Teodoro, Mairan; Moffat, Anthony; Corcoran, Michael; Damineli, Augusto

    2014-01-01

    We have obtained a total of 58 high spectral resolution (R90,000) spectra of the massive binary star eta Carinae since 2012 in an effort to continue our orbital and long-term echelle monitoring of this extreme binary (Richardson et al. 2010, AJ, 139, 1534) with the CHIRON spectrograph on the CTIO 1.5 m telescope (Tokovinin et al. 2013, PASP, 125, 1336) in the 45507500A region. We have increased our monitoring efforts and observation frequency as the periastron event of 2014 has approached. We note that there were multiple epochs this year where we observe unusual absorption components in the P Cygni troughs of the He I triplet lines. In particular, we note high velocity absorption components related to the following epochs for the following lines: He I 4713: HJD 2456754- 2456795 (velocity -450 to -560 kms) He I 5876: HJD 2456791- 2456819 (velocity -690 to -800 kms) He I 7065: HJD 2456791- 2456810 (velocity -665 to -730 kms) Figures: Note that red indicates a high-velocity component noted above. He I 4713: http:www.astro.umontreal.carichardson4713.png He I 5876: http:www.astro.umontreal.carichardson5876.png He I 7065: http:www.astro.umontreal.carichardson7065.png These absorptions are likely related to the wind-wind collision region and bow shock, as suggested by the high-velocity absorption observed by Groh et al. (2010, AA, 519, 9) in the He I 10830 Atransition. In these cases, we suspect that we look along an arm of the shock cone and that we will see a fast absorption change from the other collision region shortly after periastron. We suspect that this is related to the multiple-components of the He II 4686 line that was noted by Walter (ATel6334), and is confirmed in our data. Further, high spectral resolution data are highly encouraged,especially for resolving powers greater than 50,000.These observations were obtained with the CTIO 1.5 m telescope, operated by the SMARTS Consortium, and were obtained through both SMARTS and NOAO programs 2012A-0216,2012B-0194

  12. THE COS-HALOS SURVEY: AN EMPIRICAL DESCRIPTION OF METAL-LINE ABSORPTION IN THE LOW-REDSHIFT CIRCUMGALACTIC MEDIUM

    SciTech Connect

    Werk, Jessica K.; Prochaska, J. Xavier; Tripp, Todd M.; O'Meara, John M.; Peeples, Molly S.

    2013-02-15

    We present the equivalent width and column density measurements for low and intermediate ionization states of the circumgalactic medium (CGM) surrounding 44 low-z, L Almost-Equal-To L* galaxies drawn from the COS-Halos survey. These measurements are derived from far-UV transitions observed in HST/COS and Keck/HIRES spectra of background quasars within an impact parameter R < 160 kpc to the targeted galaxies. The data show significant metal-line absorption for 33 of the 44 galaxies, including quiescent systems, revealing the common occurrence of a cool (T Almost-Equal-To 10{sup 4}-10{sup 5} K), metal-enriched CGM. The detection rates and column densities derived for these metal lines decrease with increasing impact parameter, a trend we interpret as a declining metal surface density profile for the CGM. A comparison of the relative column densities of adjacent ionization states indicates that the gas is predominantly ionized. The large surface density in metals demands a large reservoir of metals and gas in the cool CGM (very conservatively, M {sup cool} {sub CGM} > 10{sup 9} M {sub Sun }), which likely traces a distinct density and/or temperature regime from the highly ionized CGM traced by O{sup +5} absorption. The large dispersion in absorption strengths (including non-detections) suggests that the cool CGM traces a wide range of densities or a mix of local ionizing conditions. Lastly, the kinematics inferred from the metal-line profiles are consistent with the cool CGM being bound to the dark matter halos hosting the galaxies; this gas may serve as fuel for future star formation. Future work will leverage this data set to provide estimates on the mass, metallicity, dynamics, and origin of the cool CGM in low-z, L* galaxies.

  13. Temperature dependence of the ozone absorption cross section at the 253.7-nm mercury line

    NASA Technical Reports Server (NTRS)

    Barnes, J.; Mauersberger, K.

    1987-01-01

    The temperature dependence of the ozone absorption cross section at 253.7 nm has been measured between 195 and 351 K. The experimental technique employed circumvents the necessity to determine the absolute ozone concentration for each temperature measurement. Below 273 K the cross section increases approximately 0.6 percent, while toward higher temperatures the cross section decreases rapidly. In a comparison, good agreement with other recently made measurements is shown.

  14. X-ray absorption lines - Signature for preheat level in non-explosive laser implosions

    NASA Astrophysics Data System (ADS)

    Yaakobi, B.; McCrory, R. L.; Skupsky, S.; Delettrez, J. A.; Bourke, P.; Soures, J. M.; Hooper, C. F.; Deckman, H.

    1980-08-01

    The measured X-ray spectrum from thick glass shells imploded with two TW six-beam laser pulses displayed absorption by transitions of Si ions. This indicates the existence around the time of peak compression of a cooler (less than approximately 200 eV) layer surrounding the hot innermost glass layer, of density times thickness approximately 0.0006 g/sq cm. This temperature is indicative of the preheat level ealier in the implosion.

  15. Digital signal processor-based high-precision on-line Voigt lineshape fitting for direct absorption spectroscopy.

    PubMed

    Xu, Lijun; Liu, Chang; Zheng, Deyan; Cao, Zhang; Cai, Weiwei

    2014-12-01

    To realize on-line high-accuracy measurement in direct absorption spectroscopy (DAS), a system-on-chip, high-precision digital signal processor-based on-line Voigt lineshape fitting implementation is introduced in this paper. Given that the Voigt lineshape is determined by the Gauss full width at half maximum (FWHM) and Lorentz FWHM, a look-up table, which covers a range of combinations of both, is first built to achieve rapid and accurate calculation of Voigt lineshape. With the look-up table and raw absorbance data in hand, Gauss-Newton nonlinear fitting module is implemented to obtain the parameters including both the Gauss and Lorentz FWHMs, which can be used to calculate the integrated absorbance. To realize the proposed method in hardware, a digital signal processor (DSP) is adopted to fit the Voigt lineshape in a real-time DAS measurement system. In experiment, temperature and H2O concentration of a flat flame are recovered from the transitions of 7444.36 cm(-1) and 7185.6 cm(-1) by the DSP-based on-line Voigt lineshape fitting and on-line integral of the raw absorbance, respectively. The results show that the proposed method can not only fit the Voigt lineshape on-line but also improve the measurement accuracy compared with those obtained from the direct integral of the raw absorbance. PMID:25554273

  16. Digital signal processor-based high-precision on-line Voigt lineshape fitting for direct absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Xu, Lijun; Liu, Chang; Zheng, Deyan; Cao, Zhang; Cai, Weiwei

    2014-12-01

    To realize on-line high-accuracy measurement in direct absorption spectroscopy (DAS), a system-on-chip, high-precision digital signal processor-based on-line Voigt lineshape fitting implementation is introduced in this paper. Given that the Voigt lineshape is determined by the Gauss full width at half maximum (FWHM) and Lorentz FWHM, a look-up table, which covers a range of combinations of both, is first built to achieve rapid and accurate calculation of Voigt lineshape. With the look-up table and raw absorbance data in hand, Gauss-Newton nonlinear fitting module is implemented to obtain the parameters including both the Gauss and Lorentz FWHMs, which can be used to calculate the integrated absorbance. To realize the proposed method in hardware, a digital signal processor (DSP) is adopted to fit the Voigt lineshape in a real-time DAS measurement system. In experiment, temperature and H2O concentration of a flat flame are recovered from the transitions of 7444.36 cm-1 and 7185.6 cm-1 by the DSP-based on-line Voigt lineshape fitting and on-line integral of the raw absorbance, respectively. The results show that the proposed method can not only fit the Voigt lineshape on-line but also improve the measurement accuracy compared with those obtained from the direct integral of the raw absorbance.

  17. Effect of photoions on the line shape of the Foerster resonance lines and microwave transitions in cold rubidium Rydberg atoms

    SciTech Connect

    Tretyakov, D. B.; Beterov, I. I.; Entin, V. M.; Yakshina, E. A.; Ryabtsev, I. I.; Dyubko, S. F.; Alekseev, E. A.; Pogrebnyak, N. L.; Bezuglov, N. N.; Arimondo, E.

    2012-01-15

    Experiments are carried out on the spectroscopy of the Foerster resonance lines Rb(37P) + Rb(37P) {yields} Rb(37S) + Rb(38S) and microwave transitions nP {yields} n Prime S, n Prime D between Rydberg states of cold rubidium atoms in a magneto-optical trap (MOT). Under ordinary conditions, all spectra exhibit a linewidth of 2-3 MHz irrespective of the interaction time between atoms or between atoms and microwave radiation, although the limit resonance width should be determined by the inverse interaction time. The analysis of experimental conditions has shown that the main source of line broadening is the inhomogeneous electric field of cold photoions that are generated under the excitation of initial nP Rydberg states by broadband pulsed laser radiation. The application of an additional electric-field pulse that rapidly extracts photoions produced by a laser pulse leads to a considerable narrowing of lines of microwave resonances and the Foerster resonance. Various sources of line broadening in cold Rydberg atoms are analyzed.

  18. In-line microfluidic refractometer based on C-shaped fiber assisted photonic crystal fiber Sagnac interferometer.

    PubMed

    Wu, Chuang; Tse, Ming-Leung Vincent; Liu, Zhengyong; Guan, Bai-Ou; Lu, Chao; Tam, Hwa-Yaw

    2013-09-01

    We propose and demonstrate a highly sensitive in-line photonic crystal fiber (PCF) microfluidic refractometer. Ultrathin C-shaped fibers are spliced in-between the PCF and standard single-mode fibers. The C-shaped fibers provide openings for liquid to flow in and out of the PCF. Based on a Sagnac interferometer, the refractive index (RI) response of the device is investigated theoretically and experimentally. A high sensitivity of 6621 nm/RIU for liquid RI from 1.330 to 1.333 is achieved in the experiment, which agrees well with the theoretical analysis. PMID:23988935

  19. Line strengths, A-factors and absorption cross-sections for fine structure lines in multiplets and hyperfine structure components in lines in atomic spectrometry—a user's guide

    NASA Astrophysics Data System (ADS)

    Axner, Ove; Gustafsson, Jörgen; Omenetto, Nicolò; Winefordner, James D.

    2004-01-01

    This work summarizes and elucidates a number of fundamental concepts in atomic spectrometry regarding the 'strengths' of transitions between various energy levels and states in atoms. Although several of the expressions and rules for line strengths of transitions reported here can be found, in one way or another, in various books dealing with atomic structure, atomic spectrometry or quantum mechanics, the treatment in such books can be variously complex and difficult to follow for a non-experienced reader. In addition, detailed information about transition-specific 'strengths' of transitions used to be restricted to line strengths, whereas most experiments rather need transition-specific A-factors or transition-specific absorption cross-sections. This work therefore aims at pointing out the most important aspects of the concept of 'strengths' of transitions between various energy levels and states in atoms by presenting explicit expressions for not only relative and absolute line strengths but also oscillator strengths ( f-values), A-factors and absorption cross-sections, for transitions between fine structure levels within a multiplet as well as for hyperfine structure components within a line (i.e. between hyperfine structure levels), including their mutual relations, in a consistent and user-friendly manner. The work also recapitulates the most important summation rules for line strengths, oscillator strengths ( f-values), A-factors and absorption cross-sections for lines within multiplets and hyperfine structure components within lines. Many of the expressions are illustrated with clear and intelligible examples. For the sake of clarity and completeness, the work also comprises a short review of the nomenclature for atomic structure and transitions.

  20. An accelerated line-by-line option for MODTRAN combining on-the-fly generation of line center absorption within 0.1 cm-1 bins and pre-computed line tails

    NASA Astrophysics Data System (ADS)

    Berk, Alexander; Conforti, Patrick; Hawes, Fred

    2015-05-01

    A Line-By-Line (LBL) option is being developed for MODTRAN6. The motivation for this development is two-fold. Firstly, when MODTRAN is validated against an independent LBL model, it is difficult to isolate the source of discrepancies. One must verify consistency between pressure, temperature and density profiles, between column density calculations, between continuum and particulate data, between spectral convolution methods, and more. Introducing a LBL option directly within MODTRAN will insure common elements for all calculations other than those used to compute molecular transmittances. The second motivation for the LBL upgrade is that it will enable users to compute high spectral resolution transmittances and radiances for the full range of current MODTRAN applications. In particular, introducing the LBL feature into MODTRAN will enable first-principle calculations of scattered radiances, an option that is often not readily available with LBL models. MODTRAN will compute LBL transmittances within one 0.1 cm-1 spectral bin at a time, marching through the full requested band pass. The LBL algorithm will use the highly accurate, pressure- and temperature-dependent MODTRAN Padé approximant fits of the contribution from line tails to define the absorption from all molecular transitions centered more than 0.05 cm-1 from each 0.1 cm-1 spectral bin. The beauty of this approach is that the on-the-fly computations for each 0.1 cm-1 bin will only require explicit LBL summing of transitions centered within a 0.2 cm-1 spectral region. That is, the contribution from the more distant lines will be pre-computed via the Padé approximants. The status of the LBL effort will be presented. This will include initial thermal and solar radiance calculations, validation calculations, and self-validations of the MODTRAN band model against its own LBL calculations.

  1. The role of radiative acceleration in outflows from broad absorption line QSOs. 1: Comparison with O star winds

    NASA Technical Reports Server (NTRS)

    Arav, Nahum; Li, Zhi-Yun

    1994-01-01

    We investigate the role of radiation pressure in accelerating the broad absorption line (BAL) outflows in QSOs by comparing their properties with those of radiatively driven O star winds. We find that, owing to their lower column densities and higher velocity spreads, BAL outflows have only a few tens of strong resonance lines that are dynamically important, as compared with 10(exp 3) - 10(exp 4) lines in O star winds. We show that the combined radiative force (the 'force multiplier') declines more rapidly as a function of column density for BAL outflows than for O star winds. This is mainly attributed to the absence of lines from excited states in the BAL region. The absorbing gas in BAL outflows must have a small filling factor in order for radiative acceleration to be important dynamically. This allows the absorbing material to remain at a high enough density to maintain the ion species necessary for efficient radiative acceleration as well (as those responsible for the observed absorption), without the average flow density becoming so large that the absorbing matter cannot be accelerated by an increment larger than its own sound speed. The latter condition is necessary if the outflow is to tap a large portion of the incident photon momentum. Once a small filling factor is assumed, radiative acceleration can be more efficient in BAL outflows than in O stars. We show that terminal velocities of a few times 10(exp 4) km/sec can be expected, provided that the absorbing matter does not have to drag with it a much heavier substrate.

  2. The role of radiative acceleration in outflows from broad absorption line QSOs. 1: Comparison with O star winds

    NASA Astrophysics Data System (ADS)

    Arav, Nahum; Li, Zhi-Yun

    1994-06-01

    We investigate the role of radiation pressure in accelerating the broad absorption line (BAL) outflows in QSOs by comparing their properties with those of radiatively driven O star winds. We find that, owing to their lower column densities and higher velocity spreads, BAL outflows have only a few tens of strong resonance lines that are dynamically important, as compared with 103 - 104 lines in O star winds. We show that the combined radiative force (the 'force multiplier') declines more rapidly as a function of column density for BAL outflows than for O star winds. This is mainly attributed to the absence of lines from excited states in the BAL region. The absorbing gas in BAL outflows must have a small filling factor in order for radiative acceleration to be important dynamically. This allows the absorbing material to remain at a high enough density to maintain the ion species necessary for efficient radiative acceleration as well (as those responsible for the observed absorption), without the average flow density becoming so large that the absorbing matter cannot be accelerated by an increment larger than its own sound speed. The latter condition is necessary if the outflow is to tap a large portion of the incident photon momentum. Once a small filling factor is assumed, radiative acceleration can be more efficient in BAL outflows than in O stars. We show that terminal velocities of a few times 104 km/sec can be expected, provided that the absorbing matter does not have to drag with it a much heavier substrate.

  3. Welcome to the 21st International Conference on Spectral Line Shapes

    NASA Astrophysics Data System (ADS)

    2012-12-01

    organizing committee of the conference has not forgotten about the cultural and tourism significance of the host city, with Hermitage and the Russian Museum, memorial museums of Pushkin and Dostoevsky, Mariinsky and Mikhailovsky Theaters being only a few of the many places to visit. Early June is the time of white nights, the best time to visit the environs of St. Petersburg with its many imperial palaces and parks, and attend multiple music and theater festivals. This is just the right time to take a break from physics overall and spectral line shapes in particular. On behalf of the Rector's Office let me wish the Conference every success, and do not forget to take some time out to enjoy your visit. Welcome! Professor N G Skvortsov Vice-Rector for Research St. Petersburg University

  4. Weak Hard X-Ray Emission from Two Broad Absorption Line Quasars Observed with NuStar: Compton-Thick Absorption or Intrinsic X-Ray Weakness?

    NASA Technical Reports Server (NTRS)

    Luo, B.; Brandt, W. N.; Alexander, D. M.; Harrison, F. A.; Stern, D.; Bauer, F. E.; Boggs, S. E.; Christensen, F. E.; Comastri, A.; Craig, W. W..; Fabian, A. C.; Farrah, D.; Fiore, F.; Fuerst, F.; Grefenstette, B. W.; Hailey, C. J.; Hickox, R.; Madsen, K. K.; Matt, G.; Ogle, P.; Risaliti, G.; Saez, C.; Teng, S. H.; Walton, D. J.; Zhang, W. W.

    2013-01-01

    We present Nuclear Spectroscopic Telescope Array (NuSTAR) hard X-ray observations of two X-ray weak broad absorption line (BAL) quasars, PG 1004+130 (radio loud) and PG 1700+518 (radio quiet). Many BAL quasars appear X-ray weak, probably due to absorption by the shielding gas between the nucleus and the accretion-disk wind. The two targets are among the optically brightest BAL quasars, yet they are known to be significantly X-ray weak at rest-frame 2-10 keV (16-120 times fainter than typical quasars). We would expect to obtain approx. or equal to 400-600 hard X-ray (is greater than or equal to 10 keV) photons with NuSTAR, provided that these photons are not significantly absorbed N(sub H) is less than or equal to 10(exp24) cm(exp-2). However, both BAL quasars are only detected in the softer NuSTAR bands (e.g., 4-20 keV) but not in its harder bands (e.g., 20-30 keV), suggesting that either the shielding gas is highly Compton-thick or the two targets are intrinsically X-ray weak. We constrain the column densities for both to be N(sub H) 7 × 10(exp 24) cm(exp-2) if the weak hard X-ray emission is caused by obscuration from the shielding gas. We discuss a few possibilities for how PG 1004+130 could have Compton-thick shielding gas without strong Fe Ka line emission; dilution from jet-linked X-ray emission is one likely explanation. We also discuss the intrinsic X-ray weakness scenario based on a coronal-quenching model relevant to the shielding gas and disk wind of BAL quasars. Motivated by our NuSTAR results, we perform a Chandra stacking analysis with the Large Bright Quasar Survey BAL quasar sample and place statistical constraints upon the fraction of intrinsically X-ray weak BAL quasars; this fraction is likely 17%-40%.

  5. WEAK HARD X-RAY EMISSION FROM TWO BROAD ABSORPTION LINE QUASARS OBSERVED WITH NuSTAR: COMPTON-THICK ABSORPTION OR INTRINSIC X-RAY WEAKNESS?

    SciTech Connect

    Luo, B.; Brandt, W. N.; Alexander, D. M.; Hickox, R.; Harrison, F. A.; Fuerst, F.; Grefenstette, B. W.; Madsen, K. K.; Stern, D.; Bauer, F. E.; Boggs, S. E.; Craig, W. W.; Christensen, F. E.; Comastri, A.; Fabian, A. C.; Farrah, D.; Fiore, F.; Hailey, C. J.; Matt, G.; Ogle, P.; and others

    2013-08-01

    We present Nuclear Spectroscopic Telescope Array (NuSTAR) hard X-ray observations of two X-ray weak broad absorption line (BAL) quasars, PG 1004+130 (radio loud) and PG 1700+518 (radio quiet). Many BAL quasars appear X-ray weak, probably due to absorption by the shielding gas between the nucleus and the accretion-disk wind. The two targets are among the optically brightest BAL quasars, yet they are known to be significantly X-ray weak at rest-frame 2-10 keV (16-120 times fainter than typical quasars). We would expect to obtain Almost-Equal-To 400-600 hard X-ray ({approx}> 10 keV) photons with NuSTAR, provided that these photons are not significantly absorbed (N{sub H} {approx}< 10{sup 24} cm{sup -2}). However, both BAL quasars are only detected in the softer NuSTAR bands (e.g., 4-20 keV) but not in its harder bands (e.g., 20-30 keV), suggesting that either the shielding gas is highly Compton-thick or the two targets are intrinsically X-ray weak. We constrain the column densities for both to be N{sub H} Almost-Equal-To 7 Multiplication-Sign 10{sup 24} cm{sup -2} if the weak hard X-ray emission is caused by obscuration from the shielding gas. We discuss a few possibilities for how PG 1004+130 could have Compton-thick shielding gas without strong Fe K{alpha} line emission; dilution from jet-linked X-ray emission is one likely explanation. We also discuss the intrinsic X-ray weakness scenario based on a coronal-quenching model relevant to the shielding gas and disk wind of BAL quasars. Motivated by our NuSTAR results, we perform a Chandra stacking analysis with the Large Bright Quasar Survey BAL quasar sample and place statistical constraints upon the fraction of intrinsically X-ray weak BAL quasars; this fraction is likely 17%-40%.

  6. Interstellar absorption along the line of sight to Sigma Scorpii using Copernicus observations

    NASA Technical Reports Server (NTRS)

    Allen, M. M.; Snow, T. P.; Jenkins, E. B.

    1990-01-01

    From Copernicus observations of Sigma Sco, 57 individual lines of 11 elements plus the molecular species H2 and CO were identified. By using a profile-fitting technique, rather than curves of growth, it was possible to obtain column densities and Doppler b values for up to four separate components along this line of sight. Electron density in the major H I component was derived from the photoionization equilibrium of sulfur, obtaining, n(e) of about 0.3/cu cm. The neutral hydrogen density in the same component was also derived using fine-structure excitation of O I. An H II component is also present in which the electron density was n(e) about 20/cu cm. As a by-product of this analysis, previously undetermined oscillator strengths for two Mn II lines were obtained: for 1162.-017 A, f about 0.023 and for 1164.211 A, f about 0.0086.

  7. Practical selection of emission lines of He I to determine the photon absorption rate

    SciTech Connect

    Kajita, Shin; Ohno, Noriyasu

    2011-02-15

    A combination of helium line intensities and a collisional radiative model has been used to measure electron density and temperature. However, radiation trapping of resonance lines may disturb the measurements due to disturbances in the population distribution of helium atoms. In this study, we show that the principal contribution of radiation trapping in helium plasma can be evaluated by additionally measuring one or two specific line intensities from the singlet state. The inclusion of the effects of radiation trapping sufficiently compensates for anomalous increases in the electron density and temperature, and consequently yields proper values. An experiment was performed in the divertor simulator NAGDIS-II, and the method's validity was confirmed by comparing the spectroscopically obtained results and the values from the electrostatic probe method.

  8. Distribution of smile line, gingival angle and tooth shape among the Saudi Arabian subpopulation and their association with gingival biotype

    PubMed Central

    AlQahtani, Nabeeh A.; Haralur, Satheesh B.; AlMaqbol, Mohammad; AlMufarrij, Ali Jubran; Al Dera, Ahmed Ali; Al-Qarni, Mohammed

    2016-01-01

    Objectives: To determine the occurrence of smile line and maxillary tooth shape in the Saudi Arabian subpopulation, and to estimate the association between these parameters with gingival biotype. Materials and Methods: On the fulfillment of selection criteria, total 315 patients belong to Saudi Arabian ethnic group were randomly selected. Two frontal photographs of the patients were acquired. The tooth morphology, gingival angle, and smile line classification were determined with ImageJ image analyzing software. The gingival biotype was assessed by probe transparency method. The obtained data were analyzed with SPSS 19 (IBM Corporation, New York, USA) software to determine the frequency and association between other parameters and gingival biotype. Results: Among the clinical parameters evaluated, the tapering tooth morphology (56.8%), thick gingival biotype (53%), and average smile line (57.5%) was more prevalent. The statistically significant association was found between thick gingival biotype and the square tooth, high smile line. The high gingival angle was associated with thin gingival biotype. Conclusions: The study results indicate the existence of an association between tooth shape, smile line, and gingival angle with gingival biotype. PMID:27195228

  9. Effect of duct shape, Mach number, and lining construction on measured suppressor attenuation and comparison with theory

    NASA Technical Reports Server (NTRS)

    Olsen, W. A.; Krejsa, E. A.; Coats, J. W.

    1972-01-01

    Noise attenuation was measured for several types of cylindrical suppressors that use a duct lining composed of honeycomb cells covered with a perforated plate. The experimental technique used gave attenuation data that were repeatable and free of noise floors and other sources of error. The suppressor length, the effective acoustic diameter, suppressor shape and flow velocity were varied. The agreement among the attenuation data and two widely used analytical models was generally satisfactory. Changes were also made in the construction of the acoustic lining to measure their effect on attenuation. One of these produced a very broadband muffler.

  10. Space Telescope and Optical Reverberation Mapping Project VI. Variations of the Intrinsic Absorption Lines in NGC 5548

    NASA Astrophysics Data System (ADS)

    Kriss, Gerard A.; Agn Storm Team

    2015-01-01

    The AGN STORM collaboration monitored the Seyfert 1 galaxy NGC 5548 over a six-month period, with observations spanning the hard X-ray to mid-infrared wavebands. The core of this campaign was an intensive HST COS program, which obtained 170 far-ultraviolet spectra at approximately daily intervals, with twice-per-day monitoring of the X-ray, near-UV, and optical bands during much of the same period using Swift. The broad UV absorption lines discovered by Kaastra et al. (2014) and associated with the new soft X-ray obscurer are continuously present in the STORM campaign COS spectra. Their strength varies with the degree of soft X-ray obscuration as revealed by the Swift X-ray spectra. The narrow associated absorption lines in the UV spectrum of NGC 5548 remain strong. The lower-ionization transitions that appeared concurrently with the soft X-ray obscuration vary in response to the changing UV flux on a daily basis. Their depths over the longer term, however, also respond to the strength of the soft X-ray obscuration, indicating that the soft X-ray obscurer has a significant influence on the ionizing UV continuum that is not directly tracked by the observable UV continuum itself.

  11. A Two-Line Absorption Instrument for Scramjet Temperature and Water Vapor Concentration Measurement in HYPULSE

    NASA Technical Reports Server (NTRS)

    Tsai, C. Y.

    1998-01-01

    A three beam water vapor sensor system has been modified to provide for near simultaneous temperature measurement. The system employs a tunable diode laser to scan spectral line of water vapor. The application to measurements in a scramjet combustor environment of a shock tunnel facility is discussed. This report presents and discusses die initial calibration of the measurement system.

  12. ON-LINE ZEEMAN ATOMIC ABSORPTION SPECTROSCOPY FOR MERCURY ANALYSIS IN OIL SHALE GASES

    EPA Science Inventory

    This publication describes the development and initial testing of instrumentation for continuous on-line analytical measurement of mercury concentrations in complex gas streams or in ambient air, in the presence of smoke, organic vapors, and oil mist from oil shale processing pla...

  13. Study of semiconductor valence plasmon line shapes via electron energy-loss spectroscopy in the transmission electron microscope

    SciTech Connect

    Kundmann, M.K.

    1988-11-01

    Electron energy-loss spectra of the semiconductors Si, AlAs, GaAs, InAs, InP, and Ge are examined in detail in the regime of outer-shell and plasmon energy losses (0--100eV). Particular emphasis is placed on modeling and analyzing the shapes of the bulk valence plasmon lines. A line shape model based on early work by Froehlich is derived and compared to single-scattering probability distributions extracted from the measured spectra. Model and data are found to be in excellent agreement, thus pointing the way to systematic characterization of the plasmon component of EELS spectra. The model is applied to three separate investigations. 82 refs.

  14. Phenomenological study of the normal state angle resolved photoelectron spectroscopy line shapes of high temperature superconducting cuprates

    NASA Astrophysics Data System (ADS)

    Matsuyama, Kazue; Dilip, Rohit; Gweon, G.-H.

    2015-03-01

    Understanding the normal state properties of high temperature (high-Tc) superconducting cuprates remains a central mystery in the high-Tc problem. Standing out among those mysterious properties are the anomalous angle resolved photoelectron spectroscopy (ARPES) line shapes. The extremely correlated Fermi liquid (ECFL) theory recently introduced by Shastry has renewed interest in quantitatively understanding ARPES line shapes. In this talk, we combine certain phenomenological considerations with the ECFL framework in order to describe the ARPES data. Our phenomenological models have the property of preserving the universal property of the original ECFL theory, while introducing phenomenological changes in a non-universal property. Our models describe, with unprecedented fidelity, the key aspects of the dichotomy between momentum distribution curves (MDCs) and energy distribution curves (EDCs) of high-Tc ARPES data. Therefore, our study goes well beyond the prevailing studies that discuss only MDCs and EDCs.

  15. Quantitative characterization of modulation-doped strained quantum wells through line-shape analysis of room-temperature photoluminescence spectra

    NASA Astrophysics Data System (ADS)

    Brierley, Steven K.

    1993-08-01

    Room-temperature photoluminescence (PL) was presented as a nondestructive characterization method for modulation-doped strained quantum well epitaxial structures suited for pseudomorphic high electron mobility transistors (pHEMTs). Though the spectra showed broad peaks, in contrast to the sharp, well-defined peaks in low-temperature PL spectra, quantitative energy data was obtained through fitting a phenomenological line-shape model to the spectra. This model included the four transitions linking the first two electron subbands and the first two heavy-hole subbands, which can take credit for all of the peaks noted in pHEMT epitaxial configurations at realistic doping levels. The obtained results revealed that by using a simple line-shape model to the room-temperature PL spectrum of a pHEMT, a substantial amount of detailed structural and electronic data can be acquired regarding the quantum well.

  16. Organization of T-shaped facial amphiphiles at the air/water interface studied by infrared reflection absorption spectroscopy.

    PubMed

    Schwieger, Christian; Chen, Bin; Tschierske, Carsten; Kressler, Jörg; Blume, Alfred

    2012-10-11

    We studied the behavior of monolayers at the air/water interface of T-shaped facial amphiphiles which show liquid-crystalline mesophases in the bulk. The compounds are composed of a rigid p-terphenyl core (TP) with two terminal hydrophobic ether linked alkyl chains of equal length and one facial hydrophilic tri(ethylene oxide) chain with a carboxylic acid end group. Due to their amphiphilic nature they form stable Langmuir films at the air/water interface. Depending on the alkyl chain length they show markedly different compression isotherms. We used infrared reflection absorption spectroscopy (IRRAS) to study the changes in molecular organization of the TP films upon compression. We could retrieve information on layer thickness, alkyl chain crystallization, and the orientation of the TP cores within the films. Films of TPs with long (16 carbon atoms: TP 16/3) and short (10 carbon atoms: TP 10/3) alkyl chains were compared. Compression of TP 16/3 leads to crystallization of the terminal alkyl chains, whereas the alkyl chains of TP 10/3 stay fluid over the complete compression range. TP 10/3 shows an extended plateau in the compression isotherm which is due to a layering transition. The mechanism of this layering transition is discussed. Special attention was paid to the question of whether a so-called roll-over collapse occurs during compression. From the beginning to the end of the plateau, the layer thickness is increased from 15 to 38 Å and the orientation of the TP cores changes from parallel to the water surface to isotropic. We conclude that the plateau in the compression isotherm reflects the transition of a TP monolayer to a TP multilayer. The monolayer consists of a sublayer of well-organized TP cores underneath a sublayer of fluid alkyl chains whereas the multilayer consists of a well oriented bottom layer and a disordered top layer. Our findings do not support the model of a roll-over collapse. This study demonstrates how the IRRA band intensity of OH

  17. Absorption by ground-state lead atoms of the 283. 3-nm resonant line from a lead hollow cathode lamp. An absolute number density calibration

    SciTech Connect

    Simons, J.W. ); Oldenborg, R.C.; Baughcum, S.L. )

    1989-10-19

    An accurate absolute number density calibration curve for absorption by gaseous lead atoms of the 283.3-nm resonant line from a typical lead hollow cathode lamp is reported. This calibration shows the usual curvature in the Beer-Lambert plot for atomic absorption at moderate to high absorbances that is commonly attributed to self-absorption leading to line reversal in the source and/or preferential absorption at the line center when the absorber temperature is not much greater than the source Doppler temperature. A theoretical calculation utilizing a Doppler-limited Fourier transform spectrum of the 283.3-nm emission from the lamp and a tabulated value of the absorption cross section and accounting for the isotopic and nuclear hyperfine components in both the emission and absorption due to naturally occurring lead quantitatively reproduces the experimental calibration curve without any parameter adjustments. It is found that the curvature in the Beer-Lambert plot has more to do with the fact that the absorbing and emitting atoms are a mixture of isotopes giving several isotopic and nuclear hyperfine transitions at slightly different frequencies than it does with preferential absorption at line centers.

  18. Simulation of NMR powder line shapes of quadrupolar nuclei with half-integer spin at low-symmetry sites

    SciTech Connect

    Power, W.P.; Wasylishen, R.E. ); Mooibroek, S. Ltd., Milton, Ontario ); Pettitt, B.A.; Danchura, W. )

    1990-01-25

    At crystallographic sites of low symmetry it is possible for the interactions governing the NMR powder line shape of half-integer spin quadrupolar nuclei to have different orientation dependences. In such cases, it is found that the NMR line shape is sensitive to the relative orientation of the quadrupolar (Q) and chemical shielding (CS) tensors. An analysis of the {sup 133}Cs NMR powder pattern of cesium chromate illustrates the importance of considering such orientation effects. For systems where second-order quadrupolar interactions influence the central (m{sub I} = 1/2 {leftrightarrow} 1/2) transition, the line shape arising from this transition also depends critically on the relative orientation of the Q and CS tensors. It is anticipated that such effects will be important for pin n/2 nuclei (n = 3,5,7, or 9) with large chemical shift ranges and quadrupole moments larger than that of {sup 133}Cs (e.g., {sup 17}O, {sup 51}V, {sup 59}Co, and {sup 63}Cu).

  19. Measurement of the ozone absorption cross-section at the 253.7 nm mercury line

    NASA Technical Reports Server (NTRS)

    Mauersberger, K.; Barnes, J.; Hanson, D.; Morton, J.

    1986-01-01

    The absorption cross-section of ozone at 253.7 nm is frequently used as a standard for the entire UV wavelength range. The presently accepted value is 1.147 x 10 to the -17th/sq cm, which is known with an uncertainty of about 2 percent. The cross-section has been recently measured by simultaneously monitoring the ozone pressure, the impurities in the ozone gas, the gas temperature, and the UV beam intensity. The cross-section at room temperature was found to be 1.137 x 10 to the -17th/sq cm having an uncertainty of + or - .7 percent. The improved accuracy will aid a number of ozone experiments including the in situ photometers and Solar Backscatter Ultraviolet instruments.

  20. Detection of carbon monoxide and water absorption lines in an exoplanet atmosphere.

    PubMed

    Konopacky, Quinn M; Barman, Travis S; Macintosh, Bruce A; Marois, Christian

    2013-03-22

    Determining the atmospheric structure and chemical composition of an exoplanet remains a formidable goal. Fortunately, advancements in the study of exoplanets and their atmospheres have come in the form of direct imaging--spatially resolving the planet from its parent star--which enables high-resolution spectroscopy of self-luminous planets in jovian-like orbits. Here, we present a spectrum with numerous, well-resolved molecular lines from both water and carbon monoxide from a massive planet orbiting less than 40 astronomical units from the star HR 8799. These data reveal the planet's chemical composition, atmospheric structure, and surface gravity, confirming that it is indeed a young planet. The spectral lines suggest an atmospheric carbon-to-oxygen ratio that is greater than that of the host star, providing hints about the planet's formation. PMID:23493423

  1. TOWARD DETECTING THE 2175 A DUST FEATURE ASSOCIATED WITH STRONG HIGH-REDSHIFT Mg II ABSORPTION LINES

    SciTech Connect

    Jiang Peng; Zhou Hongyan; Wang Junxian; Wang Tinggui; Ge Jian

    2011-05-10

    We report detections of 39 2175 A dust extinction bump candidates associated with strong Mg II absorption lines at z{approx} 1-1.8 on quasar spectra in Sloan Digital Sky Survey (SDSS) DR3. These strong Mg II absorption line systems are detected among 2951 strong Mg II absorbers with a rest equivalent width W{sub r} {lambda}2796> 1.0 A at 1.0 < z < 1.86, which is part of a full sample of 7421 strong Mg II absorbers compiled by Prochter et al. The redshift range of the absorbers is chosen to allow the 2175 A extinction features to be completely covered within the SDSS spectrograph operation wavelength range. An upper limit of the background quasar emission redshift at z = 2.1 is set to prevent the Ly{alpha} forest lines from contaminating the sensitive spectral region for the 2175 A bump measurements. The FM90 parameterization is applied to model the optical/UV extinction curve in the rest frame of Mg II absorbers of the 2175 A bump candidates. The simulation technique developed by Jiang et al. is used to derive the statistical significance of the candidate 2175 A bumps. A total of 12 absorbers are detected with 2175 A bumps at a 5{sigma} level of statistical significance, 10 are detected at a 4{sigma} level, and 17 are detected at a 3{sigma} level. Most of the candidate bumps in this work are similar to the relatively weak 2175 A bumps observed in the Large Magellanic Cloud LMC2 supershell rather than the strong ones observed in the Milky Way. This sample has greatly increased the total number of 2175 A extinction bumps measured on SDSS quasar spectra. Follow-up observations may rule out some of the possible false detections and reveal the physical and chemical natures of 2175 A quasar absorbers.

  2. X-Raying the Ultraluminous Infrared Starburst Galaxy and Broad Absorption Line QSO Markarian 231 with Chandra

    NASA Technical Reports Server (NTRS)

    Gallagher, S. C.; Brandt, W. N.; Chartas, G.; Garmire, G. P.; Sambruna, R. M.

    2002-01-01

    With 40 ks of Clzandra ACIS-S3 exposure, new information on both the starburst and QSO components of the X-ray emission of Markarian 231, an ultraluminous infrared galaxy and broad absorption line QSO, has been obtained. The bulk of the X-ray luminosity is emitted from an unresolved nuclear point source, and the spectrum is remarkably hard, with the majority of the flux emitted above 2 keV. Most notably, significant nuclear variability (a decrease of -45% in approximately 6 hr) at energies above 2 keV indicates that Chuizdra has probed within light-hours of the central black hole. Although we concur with Maloney & Reynolds that the direct continuum is not observed, this variability coupled with the 188 eV upper limit on the equivalent width of the Fe K o emission line argues against the reflection-dominated model put forth by these authors based on their ASCA data. Instead, we favor a model in which a small, Compton-thick absorber blocks the direct X-rays, and only indirect, scattered X-rays from multiple lines of sight can reach the observer. Extended soft, thermal emission encompasses the optical extent of the galaxy and exhibits resolved structure. An off-nuclear X-ray source with a 0.35-8.0 keV luminosity of Lx = 7 x 10 sup39 ergs s sup -1 , consistent with the ultraluminous X-ray sources in other nearby starbursts, is detected. We also present an unpublished Faint Object Spectrograph spectrum from the Hirhhle Spuce Telescope archive showing the broad C IV absorption.

  3. Reliable infrared line lists for 13 CO2 isotopologues up to E‧=18,000 cm-1 and 1500 K, with line shape parameters

    NASA Astrophysics Data System (ADS)

    Huang (黄新川), Xinchuan; Gamache, Robert R.; Freedman, Richard S.; Schwenke, David W.; Lee, Timothy J.

    2014-11-01

    Reliable infrared (IR) line lists are reported for the 13 isotopologues of carbon dioxide in HITRAN notation: 626, 636, 628, 627, 828, 727, 827, 638, 637, 737, 838, 738, and 646. Three IR lists are available for each istotopologue: a complete list at 296 K, a reduced-size list at 296 K, plus a reduced-size list at 1000 K. They are denoted Ames-296K, Ames-296K.reduced and Ames-1000K.reduced. With J up to 150, and energy up to 18,000 cm-1 above the zero point energy, these lists are expected to cover the temperature range up to 1500 K. Line shape parameters including temperature dependence are calculated and reported for four temperature ranges: Mars, Earth, Venus, and Hotter (700-2000 K). Comparisons are made against the available transition data in the HITRAN2012 models. Line position accuracy for most transitions up to 10,000-13,000 cm-1 is better than 0.03-0.05 cm-1. Computed transition intensities agree well with most HITRAN data but there exist suspicious exceptions for isotopologues. These line lists will expedite CO2 IR experimental data analysis and provide the scientific community with trustworthy alternatives for unknown IR bands. These line lists may be combined with existing experimental databases to facilitate the analysis of future laboratory experiments or astronomical observations.

  4. The Hubble Space Telescope quasar absorption line key project. 6: Properties of the metal-rich systems

    NASA Technical Reports Server (NTRS)

    Bergeron, Jacqueline; Petitjean, Patrick; Sargent, W. L. W.; Bahcall, John N.; Boksenberg, Alec; Hartig, George F.; Jannuzi, Buell T.; Kirhakos, Sofia; Savage, Blair D.; Schneider, Donald P.

    1994-01-01

    We present an analysis of the properties of a sample of 18 metal-rich, low-redshift z(sub abs) much less than z(sub em) absorbers seen in low- and medium-resolution spectra obtained for the Quasar Absorption Line Key Project with the Hubble Space Telescope Faint Object Spectrograph (HST/FOS). For most of the C IV and Lyman-limit systems, observations in the optical wavelength range of the expected associated Mg II absorption are available. As at high redshift (z approximately 2), there are two subclasses of absorbers which are characterized by the presence or absence of MG II absorption. However, some low-redshift Mg II and Fe absorptions originate from regions optically thin to UV ionizing photons and thus, at low redshift, the low-ionization systems do not always trace high opacities, as is the case at high redshift. This implies that the mean ionization state of metal-rich, optically thin absorbing clouds falls with decreasing redshift, which is consistent with the hypothesis that the gas is photoionized by the metagalactic UV background radiation field. Two main constraints are derived from the analysis of the Lyman-limit sample, assuming photoionization models are valid. First, a low opacity to ionizing photons (tau(sub LL) approximately less than 1), as observed for several Mg II-Fe II systems at z approximately 0.5, sets limits on the ionization level of hydrogen, thus on the total hydrogen column density and the heavy element abundances, (Z/H) approximately -0.5 to -0.3. Second, the dimensions of individual Mg II clouds are smaller than at high redshift by a factor 3-10. At z approximately greater than 0.6, the O VI absorption doublet is detected in four of the five z(sub abs) much less than z(sub em) systems for which the O VI wavelength range has been observed, whereas the associated N V doublet is detected in only two cases. This suggests that the presence of a high-ionization O VI phase is a general property of z approximately 0.6-1 absorption systems

  5. XMM-Newton/Reflection Grating Spectrometer detection of the missing interstellar O VII Kα absorption line in the spectrum of Cyg X-2

    NASA Astrophysics Data System (ADS)

    Cabot, Samuel H. C.; Wang, Q. Daniel; Yao, Yangsen

    2013-05-01

    The hot interstellar medium is an important part of the Galactic ecosystem and can be effectively characterized through X-ray absorption line spectroscopy. However, in a study of the hot medium using the accreting neutron star X-ray binary, Cyg X-2, as a background light source, a mystery came about when the putatively strong O VII Kα line was not detected in Chandra grating observations, while other normally weaker lines such as O VII Kβ as well as O VI and O VIII Kα are clearly present. We have investigated the grating spectra of Cyg X-2 from 10 XMM-Newton observations, in search of the missing line. We detect it consistently in nine of these observations, but the line is absent in the remaining one observation or is inconsistent with the detection in others at a ˜4σ confidence level. This absence of the line resembles that seen in the Chandra observations. Similarly, the O VI Kα line is found to disappear occasionally, but not in concert with the variation of the O VII Kα line. All these variations are most likely due to the presence of changing O VII and O VI Kα emission lines of Cyg X-2, which are blurred together with the absorption ones in the X-ray spectra. A re-examination of the Chandra grating data indeed shows evidence for a narrow emission line slightly off the O VI Kα absorption line. We further show that narrow N V emission lines with varying centroids and fluxes are present in far-ultraviolet spectra from the Cosmic Origins Spectrograph aboard the Hubble Space Telescope. These results provide new constraints on the accretion around the neutron star and on the X-ray-heating of the stellar companion. The understanding of these physical processes is also important to the fidelity of using such local X-ray binaries for interstellar absorption line spectroscopy.

  6. Line shape parameters of PH3 transitions in the Pentad near 4-5 μm: Self-broadened widths, shifts, line mixing and speed dependence

    NASA Astrophysics Data System (ADS)

    Malathy Devi, V.; Benner, D. Chris; Kleiner, Isabelle; Sams, Robert L.; Fletcher, Leigh N.

    2014-08-01

    Accurate knowledge of spectroscopic line parameters of PH3 is important for remote sensing of the outer planets, especially Jupiter and Saturn. In a recent study, line positions and intensities for the Pentad bands of PH3 have been reported from analysis of high-resolution, high signal-to noise room-temperature spectra recorded with two Fourier transform spectrometers (2014) [1]. The results presented in this study were obtained during the analysis of positions and intensities, but here we focus on the measurements of spectral line shapes (e.g. widths, shifts, line mixing) for the 2ν4, ν2 + ν4, ν1 and ν3 bands. A multispectrum nonlinear least squares curve fitting technique employing a non-Voigt line shape to include line mixing and speed dependence of the Lorentz width was employed to fit the spectra simultaneously. The least squares fittings were performed on five room-temperature spectra recorded at various PH3 pressures (∼2-50 Torr) with the Bruker IFS-125HR Fourier transform spectrometer (FTS) located at the Pacific Northwest National Laboratory (PNNL), in Richland, Washington. Over 840 Lorentz self-broadened half-width coefficients, 620 self-shift coefficients and 185 speed dependence parameters were measured. Line mixing was detected for transitions in the 2ν4, ν1 and ν3 bands, and their values were quantified for 10 A+A- pairs of transitions via off-diagonal relaxation matrix element formalism. The dependences of the measured half-width coefficients on the J and K rotational quanta of the transitions are discussed. The self-width coefficients for the ν1 and ν3 bands from this study are compared to the self-width coefficients for transitions with the same rotational quanta (J, K) reported for the Dyad (ν2 and ν4) bands. The measurements from present study should be useful for the development of a reliable theoretical modeling of pressure-broadened widths, shifts and line mixing in symmetric top molecules with C3v symmetry in general, and of PH3

  7. Combining the absorptive and radiative loss in metasurfaces for multi-spectral shaping of the electromagnetic scattering

    NASA Astrophysics Data System (ADS)

    Pan, Wenbo; Huang, Cheng; Pu, Mingbo; Ma, Xiaoliang; Cui, Jianhua; Zhao, Bo; Luo, Xiangang

    2016-02-01

    The absorptive and radiative losses are two fundamental aspects of the electromagnetic responses, which are widely occurring in many different systems such as waveguides, solar cells, and antennas. Here we proposed a metasurface to realize the control of the absorptive and radiative loss and to reduce the radar cross section (RCS) in multi-frequency bands. The anti-phase gradient and absorptive metasurfaces were designed that consists of metallic square patch and square loop structure inserted with resistors, acting as an phase gradient material in the X and Ku band, while behaving as an absorber in the S band. The simulation and experiment results verified the double-band, wideband and polarization-independent RCS reduction by the absorptive and anti-phase gradient metasurfaces.

  8. Combining the absorptive and radiative loss in metasurfaces for multi-spectral shaping of the electromagnetic scattering

    PubMed Central

    Pan, Wenbo; Huang, Cheng; Pu, Mingbo; Ma, Xiaoliang; Cui, Jianhua; Zhao, Bo; Luo, Xiangang

    2016-01-01

    The absorptive and radiative losses are two fundamental aspects of the electromagnetic responses, which are widely occurring in many different systems such as waveguides, solar cells, and antennas. Here we proposed a metasurface to realize the control of the absorptive and radiative loss and to reduce the radar cross section (RCS) in multi-frequency bands. The anti-phase gradient and absorptive metasurfaces were designed that consists of metallic square patch and square loop structure inserted with resistors, acting as an phase gradient material in the X and Ku band, while behaving as an absorber in the S band. The simulation and experiment results verified the double-band, wideband and polarization-independent RCS reduction by the absorptive and anti-phase gradient metasurfaces. PMID:26891773

  9. Combining the absorptive and radiative loss in metasurfaces for multi-spectral shaping of the electromagnetic scattering.

    PubMed

    Pan, Wenbo; Huang, Cheng; Pu, Mingbo; Ma, Xiaoliang; Cui, Jianhua; Zhao, Bo; Luo, Xiangang

    2016-01-01

    The absorptive and radiative losses are two fundamental aspects of the electromagnetic responses, which are widely occurring in many different systems such as waveguides, solar cells, and antennas. Here we proposed a metasurface to realize the control of the absorptive and radiative loss and to reduce the radar cross section (RCS) in multi-frequency bands. The anti-phase gradient and absorptive metasurfaces were designed that consists of metallic square patch and square loop structure inserted with resistors, acting as an phase gradient material in the X and Ku band, while behaving as an absorber in the S band. The simulation and experiment results verified the double-band, wideband and polarization-independent RCS reduction by the absorptive and anti-phase gradient metasurfaces. PMID:26891773

  10. Study of the Many Fluorescent Lines and the Absorption Variability in GX 301-2 with XMM-Newton

    NASA Technical Reports Server (NTRS)

    Fuerst, F.; Suchy, S.; Kreykenbohm, I.; Barragan, L.; Wilms, J.; Pottschmidt, K.; Caballero, I.; Kretschmar, P.; Ferrigno, C.; Rothschild, R. E.

    2011-01-01

    We present an in-depth study of the High Mass X-ray Binary (HMXB) GX 301-2 during its pre-periastron flare using data from the XMM-Newton satellite. The energy spectrum shows a power law continuum absorbed by a large equivalent hydrogen column on the order of 10(exp 24)/ sq cm and a prominent Fe K-alpha fluorescent emission line. Besides the Fe K-alpha line, evidence for Fe K-Beta, Ni K-alpha, Ni K-Beta, S K-alpha, Ar K-alpha, Ca K-alpha, and Cr K-alpha fluorescent lines is found. The observed line strengths are consistent with fluorescence in a cold absorber. This is the first time that Cr K-alpha is seen in emission in the X-ray spectrum of a HMXB. In addition to the modulation by the strong pulse period of approx 685 sec the source is highly variable and shows different states of activity. We perform time-resolved as well as pulse-to-pulse resolved spectroscopy to investigate differences between these states of activity. We find that fluorescent line fluxes are strongly variable and generally follow the overall flux. The N-H value is variable by a factor of 2, but not correlated to continuum normalization. We find an interval of low flux in the light curve in which the pulsations cease almost completely, without any indication of an increasing absorption column. We investigate this dip in detail and argue that it is most likely that during the dip the accretion ceased and the afterglow of the fluorescent iron accounted for the main portion of the X-ray flux. A similar dip was found earlier in RXTE data, and we compare our findings to these results.

  11. Thermodynamic derivatives of infrared absorptance

    NASA Technical Reports Server (NTRS)

    Broersma, S.; Walls, W. L.

    1974-01-01

    Calculation of the concentration, pressure, and temperature dependence of the spectral absorptance of a vibrational absorption band. A smooth thermodynamic dependence was found for wavelength intervals where the average absorptance is less than 0.65. Individual rotational lines, whose parameters are often well known, were used as bases in the calculation of medium resolution spectra. Two modes of calculation were combined: well-separated rotational lines plus interaction terms, or strongly overlapping lines that were represented by a compound line of similar shape plus corrections. The 1.9- and 6.3-micron bands of H2O and the 4.3-micron band of CO2 were examined in detail and compared with experiment.

  12. Measurement of pressure broadening of the Kr absorption line at 811.3 nm with a diode laser

    NASA Astrophysics Data System (ADS)

    Mikheyev, Pavel A.; Churnyshov, Alexander K.; Ufimtsev, Nikolay I.; Ghildina, Anna R.; Azyazov, Valery N.; Heaven, Michael C.

    2016-03-01

    Optically pumped all-rare-gas laser (OPRGL) with unique properties was recently proposed. To study this promising laser system it is necessary to have reliable diagnostics for the active medium. A set of pressure broadening coefficients, for self- and foreign- gas collision partners, is needed for measurements of the number density of metastable atoms and temperature in a rare gas discharge plasma by means of spectroscopy. However, literature analysis had shown that pressure broadening coefficients for rare gas lines in mixtures that are of interest for OPRGL's are surprisingly hard to find, or were not yet measured. Diode laser absorption spectroscopy was employed for measurements of pressure broadening coefficients for the Krypton 811.3 nm line in an RF discharge. A multi-quantum well diode laser (L808P030, Thorlabs) with an original short external cavity was used as a source of probe radiation. The natural isotopic distribution of Kr was taken into account, and an appropriate fit function was constructed. This permitted the determination of pressure broadening coefficients using the natural mixture of isotopes. The coefficients for the Kr 811.3 nm line at 300 K, measured for the first time, were ξKr-Ne = (1.50 ± 0.05) ×10-10 s-1cm3 for broadening by Neon, and ξKr-Ar = (3.5 ± 0.3) ×10-10 s-1cm3 for broadening by Argon.

  13. Variable Doppler shifts of the thermal wind absorption lines in low-mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Madej, O. K.; Jonker, P. G.; Díaz Trigo, M.; Miškovičová, I.

    2014-02-01

    In this paper, we address the general applicability of the method pioneered by Zhang, Liao & Yao in which the motion of the compact object can be tracked using wind X-ray absorption lines. We present the velocity measurements of the thermal wind lines observed in the X-ray spectrum of a few low-mass X-ray binaries: GX 13+1, H 1743-322, GRO J1655-40 and GRS 1915+105. We find that the variability in the velocity of the wind lines in about all of the sources is larger than conceivable radial velocity variations of the compact object. GX 13+1 provides a potential exception, although it would require the red giant star to be massive with a mass of ≈5-6 M⊙. We conclude that the variability of the source luminosity occurring on a time-scale of days/months can affect the outflow properties making it difficult to track the orbital motion of the compact object using current observations. Given the intrinsic variability of the outflows we suggest that low-mass X-ray binaries showing stable coronae instead of an outflow (e.g. 4U 1254-69, MXB 1659-29, 4U 1624-49) could be more suitable targets for tracking the orbital motion of the compact object.

  14. Intersstellar absorption lines between 2000 and 3000 A in nearby stars observed with BUSS. [Balloon Borne Ultraviolet Spectrophotometer

    NASA Technical Reports Server (NTRS)

    De Boer, K. S.; Lenhart, H.; Van Der Hucht, K. A.; Kamperman, T. M.; Kondo, Y.

    1986-01-01

    Spectra obtained between 2000 and 3000 A with the Balloon Borne Ultraviolet Spectrophotometer (BUSS) payload were examined for interstellar absorption lines. In bright stars, with spectral types between O9V and F5V, such lines were measured of Mg I, Mg II, Cr II, Mn II, Fe II and Zn II, with Cr II and Zn II data of especially high quality. Column densities were derived and interstellar abundances were determined for the above species. It was found that metal depletion increases with increasing E(B-V); Fe was most affected and Zn showed a small depletion for E(B-V) greater than 0.3 towards Sco-Oph. The metal column densities, derived for Alpha-And, Kappa-Dra, Alpha-Com, Alpha-Aql, and 29 Cyg were used to infer N(H I). It was shown that the ratio of Mg I to Na I is instrumental in determining the ionization structure along each line of sight. The spectra of Aql stars confirms the presence of large gas densities near Alpha-Oph. Moreover, data indicated that the Rho-Oph N(H I) value needs to be altered to 35 x 10 to the 20th/sq cm, based on observed ion ratios and analysis of the Copernicus L-alpha profile.

  15. Atmospheric Profiling Combining the Features of GPS ro & Mls: Satellite to Satellite Occultations Near Water & Ozone Absorption Lines

    NASA Astrophysics Data System (ADS)

    Kursinski, E. R.; Ward, D.; Otarola, A. C.; McGhee, J.; Reed, H.; Erickson, D.

    2015-12-01

    Assessing climate models & their predictions requires observations that determine the state of the real climate system precisely and unambiguously, independently from models. For this purpose, we have been developing a new orbiting remote sensing system called the Active Temperature, Ozone & Moisture Microwave Spectrometer (ATOMMS) which is a cross between GPS RO and the Microwave Limb Sounder. ATOMMS actively probes water vapor, ozone & other absorption lines at cm & mm wavelengths in a satellite to satellite occultation geometry to simultaneously profile temperature, pressure, water vapor and ozone as well as other important constituents. Individual profiles of water vapor, temperature & pressure heights will extend from near the surface into the mesosphere with ~1%, 0.4K and 10 m precision respectively and still better accuracy, with 100 m vertical resolution. Ozone profiles will extend upward from the upper troposphere. Line of sight wind profiles will extend upwards from the mid-stratosphere. ATOMMS is a doubly differential absorption system which eliminates drift and both sees clouds and sees thru them, to deliver performance in clouds within a factor of 2 of the performance in clear skies. This all-weather sampling combined with insensitivity to surface emissivity avoids sampling biases that limit most existing satellite records. ATOMMS will profile slant liquid water in clouds & rain and as well as turbulence via scintillations ("twinkling of a star"). Using prototype ATOMMS instrumentation that we developed with funding from NSF, several ATOMMS ground field campaigns precisely measured water vapor, cloud amount, rainfall, turbulence and absorption line spectroscopy. ATOMMS's dynamic range was demonstrated as water vapor was derived to 1% precision in optical depths up to 17. We are developing high altitude aircraft to aircraft instrumentation to further demonstrate ATOMMS performance, refine spectroscopy & support future field campaigns. Our vision is a

  16. X-Ray Weak Broad-Line Quasars: Absorption or Intrinsic X-Ray Weakness

    NASA Technical Reports Server (NTRS)

    Risaliti, Guido; Mushotzky, Richard F. (Technical Monitor)

    2004-01-01

    XMM observations of X-ray weak quasars have been performed during 2003. The data for all but the last observation are now available (there has been a delay of several months on the initial schedule, due to high background flares which contaminated the observations: as a consequence, most of them had to be rescheduled). We have reduced and analyzed these data, and obtained interesting preliminary scientific results. Out of the eight sources, 4 are confirmed to be extrimely X-ray weak, in agreement with the results of previous Chandra observations. 3 sources are confirmed to be highly variable both in flux (by factors 20-50) and in spectral properties (dramatic changes in spectral index). For both these groups of objects, an article is in preparation. Preliminary results have been presented at an international workshop on AGN surveys in December 2003, in Cozumel (Mexico). In order to further understand the nature of these X-ray weak quasars, we submitted proposals for spectroscopy at optical and infrared telescopes. We obtained time at the TNG 4 meter telescope for near-IR observations, and at the Hobby-Eberly Telescope for optical high-resolution spectroscopy. These observations will be performed in early 2004, and will complement the XMM data, in order to understand whether the X-ray weakness of these sources is an intrinsic property or is due to absorption by circumnuclear material.

  17. Excitation ahead of shock fronts in krypton measured by single line laser absorption

    NASA Astrophysics Data System (ADS)

    Boetticher, W.; Kilpin, D.

    1984-12-01

    The absorption of single-mode radiation (from a dye laser tuned to 587.25 and 557.18 nm) by Kr in front of shock waves with Mach numbers 12-21 in a 50-mm-diameter 4.4-m-long free-position driver shock tube at preshock pressures 0.7-2.7 kPa is measured to determine the number densities of the metastable 5s(1 1/2)2 and 5s(1 1/2)1 precursor states (1s5 and 1s4 in Paschen notation, respectively). The measurement technique and calculations follow those of Ernst (1982). The results are presented in tables and graphs and characterized in comparison with previous findings. The time constant of the exponential rise of the precursor is found to be about 8 microsec, and the concentration of 1s5 + 1s4 for Mach 20 is calculated as about 10 ppm, in agreement (to within a factor of 5) with model predictions for Ar and Xe.

  18. Studying Absorption Line Feature in the Relativistic Jet Source GRS 1915+105

    NASA Technical Reports Server (NTRS)

    Tavani, Marco

    1998-01-01

    The galactic superluminal source GRS 1915+105 is among the most interesting objects in our Galaxy. It is subject to erratic accretion instabilities with energization of relativistic jets producing X-ray, optical and radio emission. This source was observed by ASCA on Sept. 27, 1994, April 20, 1995, October 23, 1996 and April 25, 1997 as part of a long timescale investigation. We detected strong variability of the source, and in particular the existence of burst/dip structure in October 1996 and April 1997. Clear evidence of transient absorption features at 6.7, 7.0 and 8.0 keV was obtained for the first time in September 1994 and April 1995. Given the phenomenology of plasmoid energization and ejection, these transient spectral features might be produced by material entrained in the radio jets or in other high-velocity outflows. Our contribution to the interpretation is to incorporate these observations into a overall theoretical picture for GRS 1915+105 also taking into account other observations by XTE and BSAX. The emerging picture is complex. The central source is subject to (most likely) super-Eddington instabilities mediated by magnetic field build-up, reconnection and dissipation in the form of blobs that eventually leads to the formation of transient spectral features from the surrounding of the plasmoid emitting region. A comprehensive theoretical investigation is in progress.

  19. In-Line Capacitance Sensor for Real-Time Water Absorption Measurements

    NASA Technical Reports Server (NTRS)

    Nurge, Mark A.; Perusich, Stephen A.

    2010-01-01

    A capacitance/dielectric sensor was designed, constructed, and used to measure in real time the in-situ water concentration in a desiccant water bed. Measurements were carried out with two experimental setups: (1) passing nitrogen through a humidity generator and allowing the gas stream to become saturated at a measured temperature and pressure, and (2) injecting water via a syringe pump into a nitrogen stream. Both water vapor generating devices were attached to a downstream vertically-mounted water capture bed filled with 19.5 g of Moisture Gone desiccant. The sensor consisted of two electrodes: (1) a 1/8" dia stainless steel rod placed in the middle of the bed and (2) the outer shell of the stainless steel bed concentric with the rod. All phases of the water capture process (background, heating, absorption, desorption, and cooling) were monitored with capacitance. The measured capacitance was found to vary linearly with the water content in the bed at frequencies above 100 kHz indicating dipolar motion dominated the signal; below this frequency, ionic motion caused nonlinearities in the water concentration/capacitance relationship. The desiccant exhibited a dielectric relaxation whose activation energy was lowered upon addition of water indicating either a less hindered rotational motion or crystal reorientation.