Counting papers with at most 25 authors, so collaboration author lists do not stand in for the people here.
- University of California, BerkeleyUS1.3k papers
- Goddard Space Flight CenterUS1.3k papers
- California Institute of TechnologyUS1.3k papers
- The Ohio State UniversityUS1.2k papers
- Centre National de la Recherche ScientifiqueFR1.1k papers
- Massachusetts Institute of TechnologyUS1.1k papers
- University of Maryland, College ParkUS1k papers
- Center for Astrophysics Harvard & SmithsonianUS975 papers
- Lawrence Berkeley National LaboratoryUS898 papers
- University of ChicagoUS889 papers
- University of WashingtonUS868 papers
- Yale UniversityUS848 papers
97 papers · 2 filters
3EG J2016+3657: Confirming an EGRET Blazar Behind the Galactic Plane
J. P. Halpern, M. Eracleous, R. Mukherjee +1
We recently identified the blazar-like radio source G74.87+1.22 (B2013+370) as the counterpart of the high-energy gamma-ray source 3EG J2016+3657 in the Galactic plane. However, si…
Colors of 2625 Quasars at 0<z<5 Measured in the Sloan Digital Sky Survey Photometric System
Gordon T. Richards, Xiaohui Fan, Donald P. Schneider +3
We present an empirical investigation of the colors of quasars in the Sloan Digital Sky Survey (SDSS) photometric system. The sample studied includes 2625 quasars with SDSS photome…
The Quiescent X-Ray Spectrum of the Neutron Star in Cen X-4 Observed with Chandra/ACIS-S
Robert E. Rutledge, Lars Bildsten, Edward F. Brown +2
We report on spectral and intensity variability analysis from a Chandra/ACIS-S observation of the transient, type-I X-ray bursting low-mass X-ray binary Cen X-4. The quiescent X-ra…
ASCA Discovery of Diffuse 6.4 keV Emission Near the Sgr C Complex: A New X-ray Reflection Nebula
H. Murakami, K. Koyama, M. Tsujimoto +2
We present an ASCA discovery of diffuse hard X-ray emission from the Sgr C complex with its peak in the vicinity of the molecular cloud core. The X-ray spectrum is characterized by…
High-Redshift Quasars Found in Sloan Digital Sky Survey Commissioning Data V. Hobby-Eberly Telescope Observations
Donald P. Schneider, Xiaohui Fan, Michael A. Strauss +5
We report the discovery of 27 quasars with redshifts between 3.58 and 4.49. The objects were identified as high-redshift candidates based on their colors in Sloan Digital Sky Surve…
Further Evidence for Cosmological Evolution of the Fine Structure Constant
J. K. Webb, M. T. Murphy, V. V. Flambaum +5
We describe the results of a search for time variability of the fine structure constant, alpha, using absorption systems in the spectra of distant quasars. Three large optical data…
Possible evidence for a variable fine structure constant from QSO absorption lines: systematic errors
M. T. Murphy, J. K. Webb, V. V. Flambaum +2
Comparison of quasar absorption spectra with laboratory spectra allow us to probe possible variations in the fundamental constants over cosmological time-scales. In a companion pap…
Possible evidence for a variable fine structure constant from QSO absorption lines: motivations, analysis and results
M. T. Murphy, J. K. Webb, V. V. Flambaum +5
An experimental search for variation in the fundamental coupling constants is strongly motivated by modern high-energy physics theories. Comparison of quasar absorption line spectr…
The Luminosity Function of Galaxies in SDSS Commissioning Data
SDSS Collaboration, M. R. Blanton
During commissioning observations, the Sloan Digital Sky Survey (SDSS) has produced one of the largest existing galaxy redshift samples selected from CCD images. Using 11,275 galax…
PMN J0525-3343: soft X-ray spectral flattening in a blazar at z=4.4
A. C. Fabian, A. Celotti, K. Iwasawa +5
We report optical, radio and X-ray observations of a new distant blazar, PMN J0525-3343, at a redshift of 4.4. The X-ray spectrum measured from ASCA and BeppoSAX flattens below a f…
Off-Beam Gamma-Ray Pulsars and Unidentified EGRET Sources in the Gould Belt
Alice K. Harding, Bing Zhang
We investigate whether gamma-ray pulsars viewed at a large angle to the neutron star magnetic pole could contribute to the new population of galactic unidentified EGRET sources ass…
Models of Cuspy Triaxial Galaxies
Kelly Holley-Bockelmann, J. Christopher Mihos, Steinn Sigurdsson +1
We construct numerical models of mildly triaxial elliptical galaxies with central density cusps. Using a technique we call ``adiabatic squeezing'', we begin with a spherical gamma=…
Observation of X-ray lines from a Gamma-Ray Burst (GRB991216): Evidence of Moving Ejecta from the Progenitor
L. Piro, G. Garmire, M. Garcia +18
We report on the discovery of two emission features observed in the X-ray spectrum of the afterglow of the gamma-ray burst (GRB) of 16 Dec. 1999 by the Chandra X-Ray Observatory. T…
H-alpha Imaging with HST+NICMOS of An Elusive Damped Ly-alpha Cloud at z=0.6
Nicolas Bouche, James D. Lowenthal, Jane C. Charlton +3
Despite previous intensive ground-based imaging and spectroscopic campaigns and wide-band HST imaging of the z=0.927 QSO 3C336 field, the galaxy that hosts the damped Ly-alpha syst…
Electron-Positron Pair Cascades and Precursors in Gamma-Ray Bursts
P. Meszaros, E. Ramirez-Ruiz, M. J. Rees
Gamma-ray burst sources with a high luminosity can produce electron-positron pair cascades in their environment as a result of back-scattering of a seed fraction of their original…
Gamma-ray Burst Afterglow with Continuous Energy Injection: Signature of a Highly-Magnetized Millisecond Pulsar
Bing Zhang, Peter Meszaros
We investigate the consequences of a continuously injecting central engine on the gamma-ray burst afterglow emission, focusing more specifically on a highly-magnetized millisecond…
BeppoSAX observations of Narrow-Line Seyfert 1 galaxies: II. Ionized iron features in Arakelian 564
A. Comastri, G. M. Stirpe, C. Vignali +8
The BeppoSAX observations of the bright Narrow-Line Seyfert 1 galaxy Ark 564 are presented along with a high quality optical spectrum taken at the 1.5m telescope at La Silla. The 0…
High-resolution X-ray spectroscopy of the Seyfert 2 galaxy Circinus with Chandra
R. M. Sambruna, H. Netzer, S. Kaspi +5
Results from a 60 ks Chandra HETGS observation of the nearby Seyfert 2 Circinus are presented. The spectrum shows a wealth of emission lines at both soft and hard X-rays, including…
X-ray imaging of the Seyfert 2 galaxy Circinus with Chandra
R. M. Sambruna, W. N. Brandt, G. Chartas +5
We present results from the zeroth-order imaging of a Chandra HETGS observation of the nearby Seyfert 2 galaxy Circinus. Twelve X-ray sources were detected in the ACIS-S image of t…
An XMM-Newton detection of the z=5.80 X-ray weak quasar SDSSp J104433.04-012502.2
W. N. Brandt, M. Guainazzi, S. Kaspi +5
We report on an XMM-Newton observation of the most distant known quasar, SDSSp J104433.04-012502.2, at z=5.80. We have detected this quasar with high significance in the rest-frame…
Iron K-alpha Emission from a Decaying Magnetar Model of Gamma-Ray Bursts
M. J. Rees, P. Meszaros
The recent report of X-ray Fe features in the afterglow of the gamma-ray burst GRB 991216 may provide important clues for identifying the nature of its progenitor and constraining…
Nature and Nurture: a model for soft gamma-ray repeaters
Bing Zhang, R. X. Xu, G. J. Qiao
During supernova explosions, strange stars with almost bare quark surfaces may be formed. Under certain conditions, these stars could be rapidly spun down by the torque exerted by…
On the Origin of Intrinsic Narrow Absorption Lines in z<1 QSOs
Rajib Ganguly, Nicholas A. Bond, Jane C. Charlton +3
We present a statistical analysis of the associated, high ionization narrow absorption line (NAL) systems in a sample of 59 QSOs defined from the HST QSO Absorption Line Key Projec…
The Assembly and Evolution of Spiral Disks
Matthew Bershady, David Andersen
We explore how the growth rate of spiral disks can be measured via analyses of the scatter in the Tully-Fisher (TF) relation of local and intermediate redshift galaxies. As an init…