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Articles 7801 - 7830 of 8882

Full-Text Articles in Astrophysics and Astronomy

Metallicity Calibration Of A Ddo Cn Index And Other Low-Resolution Indices For G And K Stars, B. J. Taylor May 1999

Metallicity Calibration Of A Ddo Cn Index And Other Low-Resolution Indices For G And K Stars, B. J. Taylor

Faculty Publications

Metallicity calibrations of low-resolution parameters are potentially useful for (at least) two problems: the properties of moving groups, and the supermetallicity problem in K giants. In this paper, metallicity calibrations are derived for six sets of parameters. One of these parameters is the DDO CN index deltaCN. This parameter and three others are calibrated for use with evolved G and K stars. Two additional sets of low-resolution parameters are calibrated for use with G and K dwarfs. The calibrations are derived by comparing the input data with two catalogs of homogenized high-dispersion results from diverse authors (see Taylor 1995, 1999a). …

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The Peculiar Motions Of Early-Type Galaxies In Two Distant Rregions — Ii. The Spectroscopic Data, Gary Wegner, Matthew Colless, R. P. Saglia, Robert K. Mcmahan May 1999

The Peculiar Motions Of Early-Type Galaxies In Two Distant Rregions — Ii. The Spectroscopic Data, Gary Wegner, Matthew Colless, R. P. Saglia, Robert K. Mcmahan

Dartmouth Scholarship

We present the spectroscopic data for the galaxies studied in the EFAR project, which is designed to measure the properties and peculiar motions of early-type galaxies in two distant regions. We have obtained 1319 spectra of 714 early-type galaxies over 33 observing runs on 10 different telescopes. We describe the observations and data reductions used to measure redshifts, velocity dispersions and the Mgb and Mg2 Lick linestrength indices. Detailed simulations and intercomparison of the large number of repeat observations lead to reliable error estimates for all quantities. The measurements from different observing runs are calibrated to a common …

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The Effects Of Charge Transfer On The Thermal Equilibrium Of Photoionized Nebulae, J. B. Kingdon, Gary J. Ferland May 1999

The Effects Of Charge Transfer On The Thermal Equilibrium Of Photoionized Nebulae, J. B. Kingdon, Gary J. Ferland

Physics and Astronomy Faculty Publications

Charge transfer can affect both the ionization and thermal balance of astrophysical plasmas. Using the most recent rate coefficients and energy defects, we calculate the heating/cooling rates for charge transfer reactions between hydrogen and elements up to Z=30. We incorporate these values into the photoionization code CLOUDY. Results from models approximating a wide range of astrophysical objects and conditions suggest that charge transfer can make a significant contribution to the heating near the H ionization front, particularly in objects with a hard ionizing continuum or enhanced abundances. Charge transfer heating can also be important in regimes in which the usual …

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Modes And Quasi-Modes For M = 1,2 In A Gyrokinetic Model For A Non-Neutral Plasma, S. Neil Rasband, Ross L. Spencer May 1999

Modes And Quasi-Modes For M = 1,2 In A Gyrokinetic Model For A Non-Neutral Plasma, S. Neil Rasband, Ross L. Spencer

Faculty Publications

Modes and quasi-modes for m = 1,2 are studied in a gyro-kinetic model for a pure-electron plasma. Only z-independent perturbations are considered. Numerical methods are used to solve the relevant differential equations for smooth, analytic density profiles. Different temperatures and representative profiles are considered and comparison is made with the familiar cold fluid model from which the results depart but little, except at higher temperatures. A continuum component to the spectrum, present in the cold-fluid model, remains in the gyro-kinetic model to the order considered.

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The I-Band Tully-Fisher Relation For Sc Galaxies: 21 Centimeter H I Line Data, Martha P. Haynes, Riccardo Giovanelli, Pierre Chamaraux, Luiz N. Da Costa, Wolfram Freudling, John J. Salzer, Gary Wegner May 1999

The I-Band Tully-Fisher Relation For Sc Galaxies: 21 Centimeter H I Line Data, Martha P. Haynes, Riccardo Giovanelli, Pierre Chamaraux, Luiz N. Da Costa, Wolfram Freudling, John J. Salzer, Gary Wegner

Dartmouth Scholarship

A compilation of 21 cm line spectral parameters specifically designed for application of the Tully-Fisher (TF) distance method is presented for 1201 spiral galaxies, primarily field Sc galaxies, for which optical I-band photometric imaging is also available. New H I line spectra have been obtained for 881 galaxies. For an additional 320 galaxies, spectra available in a digital archive have been reexamined to allow application of a single algorithm for the derivation of the TF velocity width parameter. A velocity width algorithm is used that provides a robust measurement of rotational velocity and permits an estimate of the error …

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The Pg X-Ray Qso Sample: Links Between The Ultraviolet-X-Ray Continuum And Emission Lines, Beverley J. Wills, A. Laor, M. S. Brotherton, D. Wills, B. J. Wilkes, Gary J. Ferland, Zhaohui Shang Apr 1999

The Pg X-Ray Qso Sample: Links Between The Ultraviolet-X-Ray Continuum And Emission Lines, Beverley J. Wills, A. Laor, M. S. Brotherton, D. Wills, B. J. Wilkes, Gary J. Ferland, Zhaohui Shang

Physics and Astronomy Faculty Publications

Two sets of relationships relate QSO UV to soft X-ray continua with the broad-line region. These are (i) the Baldwin relationships, which are inverse relationships between the broad-line equivalent width and the continuum luminosity, and (ii) Boroson & Green's optical "Principal Component 1'' relationships, linking steeper soft X-ray spectra with narrower Hβ emission, stronger Hβ blue wings, stronger optical Fe II emission, and weaker [O III] λ5007 lines. In order to understand these relationships, we extended the spectra into the UV for 22 QSOs with high-quality soft X-ray spectra. These are from the complete sample of QSOs from the Bright …

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The Molecular Ism In Low Surface Brightness Disk Galaxies, J. Christopher Mihos, Stacy S. Mcgaugh Apr 1999

The Molecular Ism In Low Surface Brightness Disk Galaxies, J. Christopher Mihos, Stacy S. Mcgaugh

Faculty Scholarship

We present models for the interstellar medium in disk galaxies. In particular, we investigate whether the ISM in low surface brightness galaxies can support a significant fraction of molecular gas given their low metallicity and surface density. It is found that the abundance and line brightness of CO in LSB galaxies is small and typically below current observational limits. Still, depending on physical details of the ISM, the fraction of gas in the form of molecular hydrogen can be significant in the inner few kilo-parsecs of a low surface brightness galaxy. This molecular gas would be at temperatures of ∼ …

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Asymptotic Analysis Of The Structure Of A Steady Planar Detonation: Review And Extension, William B. Bush, L. Krishnamurthy Apr 1999

Asymptotic Analysis Of The Structure Of A Steady Planar Detonation: Review And Extension, William B. Bush, L. Krishnamurthy

Aerospace, Physics, and Space Science Faculty Publications

The structure of a steady planar Chapman-Jouguet detonation, which is supported by a direct first-order one-step irreversible exothermic unimolecular reaction, subject to Arrhenius kinetics, is examined. Solutions are studied, by means of a limit-processexpansion analysis, valid for A, proportional to the ratio of the reaction rate to the flow rate, going to zero, and for β, proportional to the ratio of the activation temperature to the maximum flow temperature, going to infinity, with the product Aβ½ going to zero. The results, essentially in agreement with the Zeldovich-von Neumann-Dōring model, show that the detonation consists of (1) a three-region upstream shocklike …

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Pressure Dependence Of The Metal-Insulator Transition In Fesi1-Xa1x, Brian Perone Apr 1999

Pressure Dependence Of The Metal-Insulator Transition In Fesi1-Xa1x, Brian Perone

Honors Capstones

No abstract provided.

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The I-Band Tully-Fisher Relation For Sc Galaxies: Optical Imaging Data, Martha P. Haynes, Riccardo Giovanelli, John J. Salzer, Gary Wegner Apr 1999

The I-Band Tully-Fisher Relation For Sc Galaxies: Optical Imaging Data, Martha P. Haynes, Riccardo Giovanelli, John J. Salzer, Gary Wegner

Dartmouth Scholarship

Properties derived from the analysis of photometric I-band imaging observations are presented for 1727 inclined spiral galaxies, mostly of types Sbc and Sc. The reduction, parameter extraction, and error estimation procedures are discussed in detail. The asymptotic behavior of the magnitude curve of growth and the radial variation in ellipticity and position angle are used in combination with the linearity of the surface brightness falloff to fit the disk portion of the profile. Total I-band magnitudes are calculated by extrapolating the detected surface brightness profile to a radius of eight disk scale lengths. Errors in the magnitudes, typically …

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Temperature Dependence Of Stark Width Of The 463.054 Nm Nii Spectral Line, Vladimir Milosavljevic, Ruzica Konjevic, Stevan Djenize Mar 1999

Temperature Dependence Of Stark Width Of The 463.054 Nm Nii Spectral Line, Vladimir Milosavljevic, Ruzica Konjevic, Stevan Djenize

Articles

Stark width of the 463.054 nm singly ionized nitrogen spectral line, that belong to transition, have been measured in a linear pulsed, low pressure, arc discharge. The working gas was helium-nitrogen-oxygen mixture. Electron densities of 0.751023 to 1.451023 were determined in the electron temperature range between 30000 K - 38000 K. The measured values have been compared with our calculated data, using the modified semiempirical approximation. On the basis of the agreement among experimental and theoretical Stark width data, the isolated 463.054 nm NII spectral line can be recommended as convenient spectral line for plasma diagnostics.

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The Peculiar Motions Of Early-Type Galaxies In Two Distant Regions -- V. The Mg-- Relation, Age And Metallicity, M. Colless, D. Burstein, R. L. Davies, R. K. Mcmahan, R. P. Saglia, G. Wegner Mar 1999

The Peculiar Motions Of Early-Type Galaxies In Two Distant Regions -- V. The Mg-- Relation, Age And Metallicity, M. Colless, D. Burstein, R. L. Davies, R. K. Mcmahan, R. P. Saglia, G. Wegner

Dartmouth Scholarship

We have examined the Mg—σ relation for early-type galaxies in the EFAR sample and its dependence on cluster properties. A comprehensive maximum likelihood treatment of the sample selection and measurement errors gives fits to the global Mg—σ relation of Mg b′=0.131 log σ −0.131 and Mg2=0.257 log σ −0.305. The slope of these relations is 25 per cent steeper than that obtained by most other authors owing to the reduced bias of our fitting method. The intrinsic scatter in the global Mg— σ relation is estimated to be 0.016 mag in Mg b′ and 0.023 …

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Megamaser Disks In Active Galactic Nuclei, John F. Kartje, Arieh Königl, Moshe Elitzur Mar 1999

Megamaser Disks In Active Galactic Nuclei, John F. Kartje, Arieh Königl, Moshe Elitzur

Physics and Astronomy Faculty Publications

Recent spectroscopic and VLBI-imaging observations of bright extragalactic H2O maser sources have revealed that the megamaser emission often originates in thin circumnuclear disks near the centers of active galactic nuclei (AGNs). Using general radiative and kinematic considerations and taking account of the observed flux variability, we argue that the maser emission regions are clumpy, a conclusion that is independent of the detailed mechanism (X-ray heating, shocks, etc.) driving the collisionally pumped masers. We examine scenarios in which the clumps represent discrete gas condensations (i.e., clouds) and do not merely correspond to velocity irregularities in the disk. We show …

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Mid-Infrared Visibility Measurements Of Evolved Stars, Jeffrey J. Sudol, H. M. Dyck, R. E. Stencel, D. I. Klebe, M. J. Creech-Eakman Mar 1999

Mid-Infrared Visibility Measurements Of Evolved Stars, Jeffrey J. Sudol, H. M. Dyck, R. E. Stencel, D. I. Klebe, M. J. Creech-Eakman

Physics & Engineering Faculty Publications

No abstract provided.

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The Post–Common Envelope And Pre–Cataclysmic Binary Pg 1224+309, Jerome A. Orosz, Richard A. Wade, Jason J. B. Harlow, John R. Thorstensen, Cynthia J. Taylor, Michael Eracleous Mar 1999

The Post–Common Envelope And Pre–Cataclysmic Binary Pg 1224+309, Jerome A. Orosz, Richard A. Wade, Jason J. B. Harlow, John R. Thorstensen, Cynthia J. Taylor, Michael Eracleous

Dartmouth Scholarship

We have made extensive spectroscopic and photometric observations of PG 1224+309, a close binary containing a DA white dwarf primary and an M4+ secondary. The Hα line is in emission due to irradiation of the M star by the hot white dwarf and is seen to vary around the orbit. From the radial velocities of the Hα line we derive a period of P = 0.258689 ± 0.000004 days and a semiamplitude of KHα = 160 ± 8 km s-1. We estimate a correction ΔK = 21 ± 2 km s-1, where KM …

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A Dynamical Study Of The Non-Star-Forming Translucent Molecular Cloud Mbm 16: Evidence For Shear-Driven Turbulence In The Interstellar Medium, Ted La Rosa, Steven N. Shore, Loris Magnani Feb 1999

A Dynamical Study Of The Non-Star-Forming Translucent Molecular Cloud Mbm 16: Evidence For Shear-Driven Turbulence In The Interstellar Medium, Ted La Rosa, Steven N. Shore, Loris Magnani

Faculty Articles

We present the results of a velocity correlation study of the high-latitude cloud MBM 16 using a fully sampled 12CO map, supplemented by new 13CO data. We find a correlation length of 0.4 pc. This is similar in size to the formaldehyde clumps described in our previous study. We associate this correlated motion with coherent structures within the turbulent flow. Such structures are generated by free shear flows. Their presence in this non-star-forming cloud indicates that kinetic energy is being supplied to the internal turbulence by an external shear flow. Such large-scale driving over long times is a possible solution …

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He I 2.06 Micron Emission From Nebulae, Gary J. Ferland Feb 1999

He I 2.06 Micron Emission From Nebulae, Gary J. Ferland

Physics and Astronomy Faculty Publications

The spectrum emitted by any astronomical plasma is sensitive to a variety of details, some of which may not be obviously important. This paper describes the sensitivity of the He I 2.06 μm line to the gas opacity at ionizing energies. The intensity of the line relative to a hydrogen line depends on the He+/H+ ratio, but also on the ratio of continuous to He I Lyα line opacity, since this determines whether the Lyα line can scatter often enough to be converted to the 2.06 μm line. The intensity of the infrared line relative to Hβ …

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Stellar Kinematics Of The Double Nucleus Of M31, Thomas S. Statler, Ivan R. King, Philippe Crane, Robert I. Jedrzejewski Feb 1999

Stellar Kinematics Of The Double Nucleus Of M31, Thomas S. Statler, Ivan R. King, Philippe Crane, Robert I. Jedrzejewski

Dartmouth Scholarship

We report observations of the double nucleus of M31 with the f/48 long-slit spectrograph of the Hubble Space Telescope Faint Object Camera. We obtain a total exposure of 19,000 s over seven orbits, with the 0063-wide slit along the line between the two brightness peaks (P.A. 42°). Careful correction of the raw data for detector backgrounds and geometric distortion is essential. A spectrum of Jupiter obtained with the same instrument is used as a spectral template to extract rotation and velocity dispersion profiles by cross-correlation. The rotation curve is resolved and reaches a maximum amplitude of ~250 km s-1 roughly …

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Oh 1720 Megahertz Masers In Supernova Remnants: C-Shock Indicators, Phil Lockett, Eric Gauthier, Moshe Elitzur Jan 1999

Oh 1720 Megahertz Masers In Supernova Remnants: C-Shock Indicators, Phil Lockett, Eric Gauthier, Moshe Elitzur

Physics and Astronomy Faculty Publications

Recent observations show that the OH 1720 MHz maser is a powerful probe of the shocked region where a supernova remnant strikes a molecular cloud. We perform a thorough study of the pumping of this maser and find tight constraints on the physical conditions needed for its production. The presence of the maser implies moderate temperatures (50-125 K) and densities (~105 cm-3) and OH column densities of order 1016 cm-2. We show that these conditions can exist only if the shocks are of C-type. J-shocks fail by such a wide margin that the presence …

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Constraints On H0 From The Central Velocity Dispersions Of Lens Galaxies, Aaron J. Romanowsky, C. S. Kochanek Jan 1999

Constraints On H0 From The Central Velocity Dispersions Of Lens Galaxies, Aaron J. Romanowsky, C. S. Kochanek

Faculty Publications

We employ Schwarzschild's method of the orbit modeling to constrain the mass profiles of the central lens galaxies in Q0957+561 and PG 1115+080. We combine the measured, central projected stellar velocity dispersions of these galaxies with the self-similar radial profiles of the rms velocity and of the Gauss-Hermite moment h4 observed in nearby galaxies for 0 lesssim R lesssim 2Reff. For Q0957+561, we find a 16% uncertainty in the galaxy mass and formal 2 σ limits on the Hubble constant of H0=61$\mathstrut{^{+13}_{-15}}$ km s-1 Mpc-1. For PG 1115+080, we find that none of the viable lens models can be ruled …

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Evolved, Single, Slowly Rotating . . . But Magnetically Active The G8-Giant Hr 1362 = Ek Eridani Revisited, Klaus G. Strassmeier, Kazimierz Stępień, Gregory W. Henry, Douglas S. Hall Jan 1999

Evolved, Single, Slowly Rotating . . . But Magnetically Active The G8-Giant Hr 1362 = Ek Eridani Revisited, Klaus G. Strassmeier, Kazimierz Stępień, Gregory W. Henry, Douglas S. Hall

Information Systems and Engineering Management Research Publications

We rediscuss the unusual case of the slowly rotating late-type giant HR 1362, which exhibits a very unusual high level of magnetic activity. New BVRI photometry from two robotic telescopes from 1991 through 1998 together with previously published photometric data gives a very precise photometric period of 306.9±0.4 days. With the aid of high-resolution (R=120,000) optical spectra and the Hipparcos parallax we redetermine the absolute parameters of HR 1362 and find it to be a single G8IV-III star of 14 L and a mass of 1.85 M with Teff=5125 K, log g=3.25, and solar abundances. Lithium is not significantly different …

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The Visual Orbit Of Ι Pegasi, Andrew F. Boden, Christopher D. Koresko, Gerard T. Van Belle, Mark M. Colavita, Philip J. Dumont, Joseph Gubler, Shrinivas R. Kulkarni, Benjamin F. Lane, Dasia Mobley, Michael Shao, James K. Wallace, The Pti Collaboration, Gregory W. Henry Jan 1999

The Visual Orbit Of Ι Pegasi, Andrew F. Boden, Christopher D. Koresko, Gerard T. Van Belle, Mark M. Colavita, Philip J. Dumont, Joseph Gubler, Shrinivas R. Kulkarni, Benjamin F. Lane, Dasia Mobley, Michael Shao, James K. Wallace, The Pti Collaboration, Gregory W. Henry

Information Systems and Engineering Management Research Publications

We have determined the visual orbit for the spectroscopic binary ι Pegasi with interferometric visibility data obtained by the Palomar Testbed Interferometer in 1997. ι Peg is a double-lined binary system whose minimum masses and spectral typing suggests the possibility of eclipses. Our orbital and component diameter determinations do not favor the eclipse hypothesis: the limb-to-limb separation of the two components is 0.151±0.069 mas at conjunction. Our conclusion that the ι Peg system does not eclipse is supported by high-precision photometric observations. The physical parameters implied by our visual orbit and the spectroscopic orbit of Fekel & Tomkin are in …

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Hd 62454 And Hd 68192: Two New Γ Doradus Variables, Anthony B. Kaye, Gregory W. Henry, Francis C. Fekel, Richard O. Gray, Eloy Rodríguez, Susana Martín, Douglas R. Gies, William G. Bagnuolo, Douglas S. Hall Jan 1999

Hd 62454 And Hd 68192: Two New Γ Doradus Variables, Anthony B. Kaye, Gregory W. Henry, Francis C. Fekel, Richard O. Gray, Eloy Rodríguez, Susana Martín, Douglas R. Gies, William G. Bagnuolo, Douglas S. Hall

Information Systems and Engineering Management Research Publications

We present multilongitude, multicolor photometry and simultaneous high-resolution, high signal-to-noise spectroscopy of the newly discovered γ Doradus variables HD 62454 and HD 68192. From combined Johnson and Strömgren data, we are able to identify five independent periods in HD 62454 and two stable periods in HD 68192. The data presented are sufficient to rule out all physically meaningful types of variations, with the one exception of the high-order, low-degree, nonradial gravity-mode pulsations that are believed to be at work in γ Doradus stars. We also find that HD 62454 is a double-lined spectroscopic binary and we present an orbital solution.

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Neutron Stars And Black Holes As Machos, Aparna Venkatesan, Angela V. Olinto, James W. Truran Jan 1999

Neutron Stars And Black Holes As Machos, Aparna Venkatesan, Angela V. Olinto, James W. Truran

Physics and Astronomy

We consider the contribution of neutron stars and black holes to the dynamical mass of galactic halos. In particular, we show that if these compact objects were produced by an early generation of stars with initial metallicity 10-4 Z☉, they can contribute at most 30%-40% of the Galactic halo mass without creating supersolar levels of enrichment. We show that the case for halo neutron stars and black holes cannot be rejected on metal overproduction arguments alone because of the critical factor of the choice of progenitor metallicity in determining the yields. We show that this scenario satisfies …

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Burnett Description For Plane Poiseuille Flow, Alejandro Garcia, F. Uribe Jan 1999

Burnett Description For Plane Poiseuille Flow, Alejandro Garcia, F. Uribe

Faculty Publications

Two recent works have shown that at small Knudsen number ~K! the pressure and temperature profiles in plane Poiseuille flow exhibit a different qualitative behavior from the profiles obtained by the Navier-Stokes equations. Tij and Santos [J. Stat. Phys. 76, 1399 (1994)] used the Bhatnagar-Gross-Kook model to show that the temperature profile is bimodal and the pressure profile is nonconstant. Malek-Mansour, Baras, and Garcia [Physica A 240, 255 (1997)] qualitatively confirmed these predictions in computer experiments using the direct simulation Monte Carlo method (DSMC). In this paper we compare the DSMC measurements of hydrodynamic variables and non-equilibrium fluxes with numerical …

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Spectroscopy Of Brown Dwarf Candidates In The Ρ Ophiuchi Molecular Core, Bruce Wilking, Thomas Greene, Michael Meyer Jan 1999

Spectroscopy Of Brown Dwarf Candidates In The Ρ Ophiuchi Molecular Core, Bruce Wilking, Thomas Greene, Michael Meyer

Physics Faculty Works

We present an analysis of low-resolution infrared spectra for 20 brown dwarf candidates in the core of the ρ Ophiuchi molecular cloud. Fifteen of the sources display absorption-line spectra characteristic of late-type stars. By comparing the depths of water vapor absorption bands in our candidate objects with a grid of M dwarf standards, we derive spectral types that are independent of reddening. Optical spectroscopy of one brown dwarf candidate confirms the spectral type derived from the water bands. Combining their spectral types with published near-infrared photometry, effective temperatures and bolometric stellar luminosities are derived, enabling us to place our sample …

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Numerical Simulations Of Fe Ii Emission Spectra, E. M. Verner, D. A. Verner, K. T. Korista, Jason W. Ferguson, F. Hamann, Gary J. Ferland Jan 1999

Numerical Simulations Of Fe Ii Emission Spectra, E. M. Verner, D. A. Verner, K. T. Korista, Jason W. Ferguson, F. Hamann, Gary J. Ferland

Physics and Astronomy Faculty Publications

This paper describes the techniques that we have used to incorporate a large-scale model of the Fe+ ion and resulting Fe IIemission into CLOUDY, a spectral synthesis code designed to simulate conditions within a plasma and model the resulting spectrum. We describe the numerical methods we use to determine the level populations, mutual line overlap fluorescence, collisional effects, and the heating-cooling effects of the atom on its environment. As currently implemented, the atom includes the lowest 371 levels (up to 11.6 eV) and predicts intensities of 68,635 lines. We describe our data sources, which include the most recent transition …

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Rapid Single- And Multiple-Scattering Exafs Debye-Waller Factor Calculations On Active Sites Of Metalloproteins, Nicholas Dimakis, M-Ali Al-Akhras, Grant Bunker Jan 1999

Rapid Single- And Multiple-Scattering Exafs Debye-Waller Factor Calculations On Active Sites Of Metalloproteins, Nicholas Dimakis, M-Ali Al-Akhras, Grant Bunker

Physics & Astronomy Faculty Publications

This paper describes recent results using our approach to calculating self-consistently single (SS) and multiple-scattering (MS) Debye- Waller factors (DWF) on active sites of metalloproteins. The calculation of MS DWF, together with the Feff7 program allows us to simulate ab-initio EXAFS spectra for a given temperature systems with no adjustable parameters. In our latest report (Dimakis N., and Bunker G., 1998) we calculate, using density functional and semiempirical approaches, the SS and MS DWF for small molecules and compared them to Raman, infrared and EXAFS spectra. In this report calculation of DWFs is done for tetrahedral Zn imidazole, a complex …

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Observational Limit On Gravitational Waves From Binary Neutron Stars In The Galaxy, B. Allen, J. K. Blackburn, J. D. Creighton, Teviet Creighton Jan 1999

Observational Limit On Gravitational Waves From Binary Neutron Stars In The Galaxy, B. Allen, J. K. Blackburn, J. D. Creighton, Teviet Creighton

Physics & Astronomy Faculty Publications

Using optimal matched filtering, we search 25 hours of data from the LIGO 40-m prototype laser interferometric gravitational-wave detector for gravitational-wave chirps emitted by coalescing binary systems within our Galaxy. This is the first test of this filtering technique on real interferometric data. An upper limit on the rate R of neutron star binary inspirals in our Galaxy is obtained: with 90% confidence, R<0.5h−1. Similar experiments with LIGO interferometers will provide constraints on the population of tight binary neutron star systems in the Universe.

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Detecting An Association Between Gamma Ray And Gravitational Wave Bursts, Lee Samuel Finn, Soumya Mohanty, Joseph D. Romano Jan 1999

Detecting An Association Between Gamma Ray And Gravitational Wave Bursts, Lee Samuel Finn, Soumya Mohanty, Joseph D. Romano

Physics & Astronomy Faculty Publications

If γ-ray bursts (GRBs) are accompanied by gravitational wave bursts (GWBs) the correlated output of two gravitational wave detectors evaluated in the moments just prior to a GRB will differ from that evaluated at other times. We can test for this difference without prior knowledge of either the GWB wave form or the detector noise spectrum. With a model for the GRB source population and GWB spectrum we can put a limit on the in-band rms GWB signal amplitude. Laser-Interferometer Gravitational Wave Observatory I detector observations coincident with 1000 GRB observations could lead us to exclude with 95% confidence associated …

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