19.6k citations
Counting papers with at most 25 authors, so collaboration author lists do not stand in for the people here.
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169 papers · 1 filter
Simulations and Measurements of the Background Encountered by a High-Altitude Balloon-Borne Experiment for Hard X-ray Astronomy
Kenneth S. K. Lum, Joseph J. Mohr, Didier Barret +2
We have modelled the hard X-ray background expected for a high-altitude balloon flight of the Energetic X-ray Telescope Experiment (EXITE2), an imaging phoswich detector/telescope…
Discovery of >350 GeV Gamma Rays from the BL Lacertae Object 1ES 2344+514
M. Catanese, C. W. Akerlof, H. M. Badran +31
We present the discovery of >350 GeV gamma-ray emission from the BL Lacertae object 1ES 2344+514 with the Whipple Observatory 10m gamma-ray telescope. This is the third BL Lac obje…
BeppoSAX observations of the Seyfert 1 Galaxy NGC 3516
G. M. Stirpe, B. J. Wilkes, A. Comastri +2
We present the results of two observations of the bright Seyfert 1 galaxy NGC 3516, obtained with BeppoSAX in 1996 November and 1997 March. Useful signal is detected between 0.2 an…
A Search for Line Shape and Depth Variations in 51 Pegasi and Tau Bootis
T. M. Brown, R. Kotak, S. D. Horner +4
Spectroscopic observations of 51 Pegasi and tau Bootis show no periodic changes in the shapes of their line profiles; these results for 51 Peg are in significant conflict with thos…
Constraints on Neutron Star Masses and Radii from Kilohertz QPOs
Frederick K. Lamb, M. Coleman Miller, Dimitrios Psaltis
The frequencies of the highest-frequency kilohertz QPOs recently discovered in some sixteen neutron stars in low-mass X-ray binary systems are most likely orbital frequencies. If s…
Illumination in symbiotic binary stars: Non-LTE photoionization models. II. Wind case
Daniel Proga, Scott J. Kenyon, John C. Raymond
We describe a non-LTE photoionization code to calculate the wind structure and emergent spectrum of a red giant wind illuminated by the hot component of a symbiotic binary system.…
Numerical Models of Accretion Disks
Charles F. Gammie
I review recent numerical studies of accretion disks, focusing on measurements of the turbulent shear stress, or , in the shearing box model. I conclude with a list of astronomi…
Low-Luminosity Early-Type Galaxies in the Coma Cluster: Variations in Spectral Properties
Nelson Caldwell, James Rose
We present spectra of nine low-luminosity early-type galaxies (M_B > -17.5) in the Coma cluster. The spectra, which were obtained with the Multiple Mirror Telescope and cover the s…
Gamma Ray Bursts from Baryon Decay in Neutron Stars
Ue-Li Pen, Abraham Loeb, Neil Turok
The standard unbroken electroweak theory is known to erase baryon number. The baryon number symmetry can be restored in the core of a neutron star as its density diverges via gravi…
A varying kHz peak separation in 4U 1608-52
M. Mendez, M. van der Klis, J. van Paradijs +6
Using a new technique to improve the sensitivity to weak Quasi-Periodic Oscillations (QPO) we discovered a new QPO peak at about 1100 Hz in the March 1996 outburst observations of…
Effects of Disks on Gravitational Lensing by Spiral Galaxies
Matthias Bartelmann, Abraham Loeb
Gravitational lensing of a quasar by a spiral galaxy should often be accompanied by damped Lyman-alpha absorption and dust extinction due to the intervening gaseous disk. In nearly…
AXAF in Context: A Revolution
Martin Elvis
The unique power of AXAF (NASA's Advanced X-ray Astrophysics Facility) - due for launch in late 1988 - make it both the culmination of 20 years of X-ray astronomy, and a new starti…
Water maser emission and the parsec-scale jet in NGC 3079
Adam S. Trotter, Lincoln J. Greenhill, James M. Moran +3
We have conducted VLBI observations of water maser and radio continuum emission in the nucleus of NGC 3079. The 22 GHz maser emission arises in compact clumps, distributed along an…
Discovery of a second kHz QPO peak in 4U 1608-52
M. Mendez, M. van der Klis, J. van Paradijs +6
Using a new technique to improve the sensitivity to weak Quasi-Periodic Oscillations (QPO) we discovered a new QPO peak at about 1100 Hz in the March 1996 outburst observations of…
The HST Key Project on the Extragalactic Distance Scale XIII. The Metallicity Dependence of the Cepheid Distance Scale
R. Kennicutt, P. Stetson, A. Saha +22
Uncertainty in the metal abundance dependence of the Cepheid variable period- luminosity (PL) relation remains one of the outstanding sources of systematic error in the extragalact…
DIRECT Distances to Nearby Galaxies Using Detached Eclipsing Binaries and Cepheids. II. Variables in the Field M31A
K. Z. Stanek, J. Kaluzny, M. Krockenberger +3
We undertook a long term project, DIRECT, to obtain the direct distances to two important galaxies in the cosmological distance ladder -- M31 and M33, using detached eclipsing bina…
Identifying the Environment and Redshift of GRB Afterglows from the Time-Dependence of Their Absorption Spectra
Rosalba Perna, Abraham Loeb
The discovery of Gamma-Ray Burst (GRB) afterglows revealed a new class of variable sources at optical and radio wavelengths. At present, the environment and precise redshift of the…
X-Ray Spectral Properties of the Cluster Abell 2029
Craig L. Sarazin, Michael W. Wise, Maxim L. Markevitch
We have analyzed ASCA and ROSAT PSPC spectra and images of the galaxy cluster Abell 2029. The ASCA spectra of the cluster indicate that the gas temperature declines with radius. Th…
Orbital Parameters for the Soft X-ray Transient 4U 1543-47: Evidence for a Black Hole
Jerome A. Orosz, Raj K. Jain, Charles D. Bailyn +2
(shortened) Spectroscopic observations of the soft X-ray transient 4U 1543-47 reveal a radial velocity curve with a period of P=1.123 +/- 0.008 days and a semi-amplitude of K_2 = 1…
Astrophysical Evidence for Black Hole Event Horizons
K. Menou, E. Quataert, R. Narayan
Astronomers have discovered many potential black holes in X-ray binaries and galactic nuclei. These black holes are usually identified by the fact that they are too massive to be n…
Spectra and Light Curves of Gamma-Ray Burst Afterglows
Re'em Sari, Tsvi Piran, Ramesh Narayan
The recently discovered GRB afterglow is believed to be described reasonably well by synchrotron emission from a slowing down relativistic shell that collides with an external medi…
The Lensing Cluster MS0440+0204 Seen by HST, ROSAT and ASCA: I. Cluster Properties
I. M. Gioia, E. J. Shaya, O. Le Fevre +3
We present an analysis of the properties of the lensing cluster MS0440+0204 at z=0.1965. MS0440+0204 has been observed with a variety of telescopes at diverse wavelengths: from the…
Weak Lensing Reconstruction and Power Spectrum Estimation: Minimum Variance Methods
Uros Seljak
Large-scale structure distorts the images of background galaxies, which allows one to measure directly the projected distribution of dark matter in the universe and determine its p…
Discovery of KiloHertz Quasi-Periodic Oscillations in the Z source Cygnus X-2
Rudy Wijnands, Jeroen Homan, Michiel van der Klis +6
During observations with RXTE we discovered two simultaneous kHz QPOs near 500 Hz and 860 Hz in the Z source Cyg X-2. In the X-ray color-color diagram and hardness-intensity diagra…