Open Access. Powered by Scholars. Published by Universities.®

Astrophysics and Astronomy Commons

Open Access. Powered by Scholars. Published by Universities.®

7,346 Full-Text Articles 18,121 Authors 485,246 Downloads 190 Institutions

All Articles in Astrophysics and Astronomy

Faceted Search

7,346 full-text articles. Page 229 of 229.

The Lisa Gravitational Wave Foreground: A Study Of Double White Dwarfs, Ashley J. Ruiter, Krzysztof Belczynski, Matthew Benacquista, Shane L. Larson, Gabriel Williams 2010 University of Texas Rio Grande Valley

The Lisa Gravitational Wave Foreground: A Study Of Double White Dwarfs, Ashley J. Ruiter, Krzysztof Belczynski, Matthew Benacquista, Shane L. Larson, Gabriel Williams

Physics and Astronomy Faculty Publications and Presentations

Double white dwarfs (WDs) are expected to be a source of confusion-limited noise for the future gravitational wave observatory LISA. In a specific frequency range, this \"foreground noise\" is predicted to rise above the instrumental noise and hinder the detection of other types of signals, e.g., gravitational waves arising from stellar-mass objects inspiraling into massive black holes. In many previous studies, only detached populations of compact object binaries have been considered in estimating the LISA gravitational wave foreground signal. Here, we investigate the influence of compact object detached and Roche-Lobe overflow (RLOF) Galactic binaries on the shape and strength ...


Effects Of α-Element Enhancement And The Thermally Pulsing-Asymptotic Giant Branch On Surface Brightness Fluctuation Magnitudes And Broadband Colors, Hyun Chul Lee, Guy Worthey, John P. Blakeslee 2010 University of Texas Rio Grande Valley

Effects Of α-Element Enhancement And The Thermally Pulsing-Asymptotic Giant Branch On Surface Brightness Fluctuation Magnitudes And Broadband Colors, Hyun Chul Lee, Guy Worthey, John P. Blakeslee

Physics and Astronomy Faculty Publications and Presentations

We investigate the effects of α-element enhancement and the thermally pulsing-asymptotic giant branch (TP-AGB) stars on the surface brightness fluctuation (SBF) magnitudes and broadband colors of simple stellar populations and compare to the empirical calibrations. We consider a broad range of ages and metallicities using the recently updated Teramo BaSTI isochrones. We find that the α-element-enhanced I-band SBF magnitudes are about 0.35mag brighter and their integrated V - I colors are about 0.02mag redder, mostly because of oxygen-enhancement effects on the upper red giant branch and AGB. We also demonstrate, using both the Teramo BaSTI and Padova ...


Unidirectional Nonlinear Pt -Symmetric Optical Structures, H. Ramezani, Tsampikos Kottos 2010 The University of Texas Rio Grande Valley

Unidirectional Nonlinear Pt -Symmetric Optical Structures, H. Ramezani, Tsampikos Kottos

Physics and Astronomy Faculty Publications and Presentations

We show that nonlinear optical structures involving a balanced gain-loss profile can act as unidirectional optical valves. This is made possible by exploiting the interplay between the fundamental symmetries of parity (P) and time (T), with optical nonlinear effects. This unidirectional dynamics is specifically demonstrated for the case of an integrable PT-symmetric nonlinear system.


Search For Gravitational Waves From Compact Binary Coalescence In Ligo And Virgo Data From S5 And Vsr1, J. Abadie, B. P. Abbott, Matthew Benacquista, Teviet Creighton, Mario C. Diaz, R. Grosso, J. Li, Soumya Mohanty, Soma Mukherjee, Volker Quetschke, M. Rakhmanov, Joseph D. Romano, Robert Stone, B. Vaishnav 2010 The University of Texas Rio Grande Valley

Search For Gravitational Waves From Compact Binary Coalescence In Ligo And Virgo Data From S5 And Vsr1, J. Abadie, B. P. Abbott, Matthew Benacquista, Teviet Creighton, Mario C. Diaz, R. Grosso, J. Li, Soumya Mohanty, Soma Mukherjee, Volker Quetschke, M. Rakhmanov, Joseph D. Romano, Robert Stone, B. Vaishnav

Physics and Astronomy Faculty Publications and Presentations

We report the results of the first search for gravitational waves from compact binary coalescence using data from the Laser Interferometer Gravitational-Wave Observatory and Virgo detectors. Five months of data were collected during the Laser Interferometer Gravitational-Wave Observatory’s S5 and Virgo’s VSR1 science runs. The search focused on signals from binary mergers with a total mass between 2 and 35M⊙. No gravitational waves are identified. The cumulative 90%-confidence upper limits on the rate of compact binary coalescence are calculated for nonspinning binary neutron stars, black hole-neutron star systems, and binary black holes to be 8.7×10 ...


Search For Gravitational-Wave Inspiral Signals Associated With Short Gamma-Ray Bursts During Ligo's Fifth And Virgo's First Science Run, J. Abadie, B. P. Abbott, R. Abbott, T. Accadia, F. Acernese, R. Adhikari, P. Ajith, B. Allen, G. Allen, E. Amador Ceron, R. S. Amin, S. B. Anderson, W. G. Anderson, F. Antonucci, S. Aoudia, M. A. Arain, M. Araya, K. G. Arun, Y. Aso, S. Aston, P. Astone, P. Aufmuth, C. Aulbert, S. Babak, P. Baker, G. Ballardin, S. Ballmer, D. Barker, F. Barone, B. Barr 2010 University of Texas Rio Grande Valley

Search For Gravitational-Wave Inspiral Signals Associated With Short Gamma-Ray Bursts During Ligo's Fifth And Virgo's First Science Run, J. Abadie, B. P. Abbott, R. Abbott, T. Accadia, F. Acernese, R. Adhikari, P. Ajith, B. Allen, G. Allen, E. Amador Ceron, R. S. Amin, S. B. Anderson, W. G. Anderson, F. Antonucci, S. Aoudia, M. A. Arain, M. Araya, K. G. Arun, Y. Aso, S. Aston, P. Astone, P. Aufmuth, C. Aulbert, S. Babak, P. Baker, G. Ballardin, S. Ballmer, D. Barker, F. Barone, B. Barr

Physics and Astronomy Faculty Publications and Presentations

Progenitor scenarios for short gamma-ray bursts (short GRBs) include coalescenses of two neutron stars or a neutron star and black hole, which would necessarily be accompanied by the emission of strong gravitational waves. We present a search for these known gravitational-wave signatures in temporal and directional coincidence with 22 GRBs that had sufficient gravitational-wave data available in multiple instruments during LIGO's fifth science run, S5, and Virgo's first science run, VSR1. We find no statistically significant gravitational-wave candidates within a [ - 5, + 1)s window around the trigger time of any GRB. Using the Wilcoxon-Mann-Whitney U-test, we find no ...


Deriving An X-Ray Luminosity Function Of Dwarf Novae Based On Parallax Measurements, K. Byckling, K. Mukai, J. R. Thorstensen, J. P. Osborne 2010 University of Leicester

Deriving An X-Ray Luminosity Function Of Dwarf Novae Based On Parallax Measurements, K. Byckling, K. Mukai, J. R. Thorstensen, J. P. Osborne

Open Dartmouth: Published works by Dartmouth faculty

We have derived an X-ray luminosity function using parallax-based distance measurements of a set of 12 dwarf novae, consisting of Suzaku, XMM-Newton and ASCA observations. The shape of the X-ray luminosity function obtained is the most accurate to date, and the luminosities of our sample are concentrated between ~10^{30}-10^{31} erg s^{-1}, lower than previous measurements of X-ray luminosity functions of dwarf novae. Based on the integrated X-ray luminosity function, the sample becomes more incomplete below ~3 x 10^{30} erg s^{-1} than it is above this luminosity limit, and the sample is dominated by X-ray ...


Relations Relevant To The One Body Reduction Of The Gravitational Two Body Problem, Eric Addison 2009 Utah State University

Relations Relevant To The One Body Reduction Of The Gravitational Two Body Problem, Eric Addison

Eric Addison

The one body reduction of the two body problem is outlined along with several important relations. It is verified that both masses in a binary system orbit around the common center of mass.


The Stellar And Gaseous Contents Of The Orion Dwarf Galaxy, John Cannon, Korey Haynes, Hans Most, John Salzer, Kaitlin Haugland, Jillian Scudder, Arthur Sugden, Jacob Weindling 2009 Macalester College

The Stellar And Gaseous Contents Of The Orion Dwarf Galaxy, John Cannon, Korey Haynes, Hans Most, John Salzer, Kaitlin Haugland, Jillian Scudder, Arthur Sugden, Jacob Weindling

John Cannon

No abstract provided.


Spatially Resolved Polycyclic Aromatic Hydrocarbon Emission Features In Nearby, Low Metallicity, Star-Forming Galaxies, Korey Haynes, John Cannon, Evan Skillman, Dale Jackson, Robert Gehrz 2009 Macalester College

Spatially Resolved Polycyclic Aromatic Hydrocarbon Emission Features In Nearby, Low Metallicity, Star-Forming Galaxies, Korey Haynes, John Cannon, Evan Skillman, Dale Jackson, Robert Gehrz

John Cannon

No abstract provided.


Instantaneous Velocities Of A Two Body Orbit, Eric Addison 2009 Utah State University

Instantaneous Velocities Of A Two Body Orbit, Eric Addison

Eric Addison

This short note will derive expressions for the instantaneous velocity of the components in a two-body elliptical Keplerian orbit.


Derivation Of Initial Velocities For A Two-Body Orbit In The Barycenter Frame, Eric Addison 2009 Utah State University

Derivation Of Initial Velocities For A Two-Body Orbit In The Barycenter Frame, Eric Addison

Eric Addison

The readily available information for two body orbits generally refers to the one dimensional, reduced mass case. Information about initial conditions in the barycenter frame is not easily found. In order to derive the initial velocities required for a two-body orbit in the barycenter frame, the momentum of the reduced mass can be used.


Origins Of The Extragalactic Background At 1mm From A Combined Analysis Of The Aztec And Mambo Data In Goods-N, Kyle Penner, Alexandra Pope, Edward L. Chapin, Thomas R. Greve, Frank Bertoldi, Mark Brodwin, Ranga-Ram Chary, Christopher J, Conselice, Kristen Coppin, Mauro Giavalisco, David H. Hughes, Rob J. Ivison, Thushara Perera, Douglas Scott, Kimberly Scott, Grant Wilson 2009 University of Massachusetts - Amherst

Origins Of The Extragalactic Background At 1mm From A Combined Analysis Of The Aztec And Mambo Data In Goods-N, Kyle Penner, Alexandra Pope, Edward L. Chapin, Thomas R. Greve, Frank Bertoldi, Mark Brodwin, Ranga-Ram Chary, Christopher J, Conselice, Kristen Coppin, Mauro Giavalisco, David H. Hughes, Rob J. Ivison, Thushara Perera, Douglas Scott, Kimberly Scott, Grant Wilson

Thushara A. Perera

We present a study of the cosmic infrared background, which is a measure of the dust obscured activity in all galaxies in the Universe. We venture to isolate the galaxies responsible for the background at 1mm; with spectroscopic and photometric redshifts we constrain the redshift distribution of these galaxies. We create a deep 1.16mm map (sigma ~ 0.5mJy) by combining the AzTEC 1.1mm and MAMBO 1.2mm datasets in GOODS-N. This combined map contains 41 secure detections, 13 of which are new. By averaging the 1.16mm flux densities of individually undetected galaxies with 24um flux densities > 25uJy ...


Binary Tidal Disruption Radius, Eric Addison 2009 Utah State University

Binary Tidal Disruption Radius, Eric Addison

Eric Addison

An expression for the tidal disruption radius of a binary system is calculated.


The Globular Cluster System Of Ngc 1399. V. Dynamics Of The Cluster System Out To 80 Kpc, Y. Schuberth, T. Richtler, M. Hilker, B. Dirsch, L. Bassino, Aaron J. Romanowsky, L. Infante 2009 Universidad Nacional de La Plata

The Globular Cluster System Of Ngc 1399. V. Dynamics Of The Cluster System Out To 80 Kpc, Y. Schuberth, T. Richtler, M. Hilker, B. Dirsch, L. Bassino, Aaron J. Romanowsky, L. Infante

Aaron J. Romanowsky

Globular clusters (GCs) are tracers of the gravitational potential of their host galaxies. Moreover, their kinematic properties may provide clues for understanding the formation of GC systems and their host galaxies. We use the largest set of GC velocities obtained so far of any elliptical galaxy to revise and extend the previous investigations (Richtler et al. 2004) of the dynamics of NGC 1399, the central dominant galaxy of the nearby Fornax cluster of galaxies. The GC velocities are used to study the kinematics, their relation with population properties, and the dark matter halo of NGC 1399. We have obtained 477 ...


Central Dark Matter Content Of Early-Type Galaxies: Scaling Relations And Connections With Star Formation Histories, N. R. Napolitano, Aaron J. Romanowsky, A. J. Tortora 2009 San Jose State University

Central Dark Matter Content Of Early-Type Galaxies: Scaling Relations And Connections With Star Formation Histories, N. R. Napolitano, Aaron J. Romanowsky, A. J. Tortora

Aaron J. Romanowsky

We examine correlations between masses, sizes and star formation histories for a large sample of low-redshift early-type galaxies, using a simple suite of dynamical and stellar population models. We confirm an anticorrelation between the size and stellar age and go on to survey for trends with the central content of dark matter (DM). An average relation between the central DM density and galaxy size of 〈ρDM〉∝R−2eff provides the first clear indication of cuspy DM haloes in these galaxies – akin to standard Λ cold dark matter haloes that have undergone adiabatic contraction. The DM density scales with galaxy mass ...


The Zeeman Effect In The Sobolev Approximation Ii. Radial Split Monopole Fields And The ‘Heartbeat’ Stokes V Profile., K. G. Gayley, R. Ignace 2009 East Tennessee State University

The Zeeman Effect In The Sobolev Approximation Ii. Radial Split Monopole Fields And The ‘Heartbeat’ Stokes V Profile., K. G. Gayley, R. Ignace

Richard Ignace

We calculate the circularly polarized Stokes V(λ) profile for emission lines, formed in hot-star winds threaded with a weak radial magnetic field. For simplicity, the field is treated as a split monopole under the assumptions that it has been radially combed by the wind, and rotation is not playing a central role. Invoking the weak-field approximation, we find that the V(λ) profile has a characteristic “heartbeat” shape exhibiting multiple sign inversions, which might be mistaken for noise in the absence of theoretical guidance. We also conclude that there is a tendency for the V(λ) profile to integrate ...


Digital Commons powered by bepress