Search Publications
An Infrared Study of the Large-Scale Jet in Quasar PKS 1136-135
Cheung, C. C.; Takahashi, Tadayuki; Van Duyne, Jeffrey +6 more
We present Spitzer IRAC imaging of the large-scale jet in the quasar PKS 1136-135 at wavelengths of 3.6 and 5.8 µm, combined with previous VLA, HST, and Chandra observations. We clearly detect infrared emission from the jet, resulting in the most detailed multifrequency data among the jets in lobe-dominated quasars. The spectral energy distr…
Smoothed Particle Inference: A Kilo-Parametric Method for X-Ray Galaxy Cluster Modeling
Marshall, P. J.; Peterson, J. R.; Andersson, K.
We propose an ambitious new method that models the intracluster medium in clusters of galaxies as a set of X-ray-emitting smoothed particles of plasma. Each smoothed particle is described by a handful of parameters including temperature, location, size, and elemental abundances. Hundreds to thousands of these particles are used to construct a mode…
The Host Galaxy of the Quasar HE 0450-2958
Ho, Luis C.; Im, Myungshin; Kim, Minjin +1 more
A recent study suggests that the quasar HE 0450-2958 is hosted by a galaxy substantially fainter than that inferred from the correlation between black hole mass and bulge luminosity. As this result has significant bearings on galaxy and black hole evolution, we revisit the issue by performing an independent analysis of the data, using a two-dimens…
The First Detection of Compton Reflection in the Low-Mass X-Ray Binary 4U 1705-44 with INTEGRAL and BeppoSax
Zdziarski, Andrzej A.; Ubertini, Pietro; Bazzano, Angela +1 more
We present data from INTEGRAL and BeppoSAX satellites showing spectral state transitions of the neutron star, atoll-type, low-mass X-ray binary 4U 1705-44. Its energy spectrum can be described as the sum of one or two blackbody components, a 6.4 keV Fe line, and a component due to thermal Comptonization. In addition, and for the first time in this…
The Long-Period, Massive Binaries HD 37366 and HD 54662: Potential Targets for Long-Baseline Optical Interferometry
Bolton, C. T.; Fullerton, A. W.; Gies, D. R. +8 more
We present the results from an optical spectroscopic analysis of the massive stars HD 37366 and HD 54662. We find that HD 37366 is a double-lined spectroscopic binary with a period of 31.8187+/-0.0004 days, and HD 54662 is also a double-lined binary with a much longer period of 557.8+/-0.3 days. The primary of HD 37366 is classified as O9.5 V, and…
NICMOS Observations of Shocked H2 in Orion
Schultz, A. S. B.; Colgan, Sean W. J.; Hollenbach, D. J. +2 more
HST NICMOS narrowband images of the shocked molecular hydrogen emission in OMC-1 are analyzed to reveal new information on the BN/KL outflow. The outstanding morphological feature of this region is the array of molecular hydrogen ``fingers'' emanating from the general vicinity of IRc2 and the presence of several Herbig-Haro objects. The NICMOS ima…
Photometric Selection of QSO Candidates from GALEX Sources
Gould, Andrew; Atlee, David W.
We present a catalog of 36,120 QSO candidates from the Galaxy Evolution Explorer (GALEX) Release Two (GR2) UV catalog and the USNO-A2.0 optical catalog. The selection criteria are established using known quasars from the Sloan Digital Sky Survey (SDSS). The SDSS sample is then used to assign individual probabilities to our GALEX USNO candidates. T…
AEGIS: Infrared Spectroscopy of an Infrared-luminous Lyman Break Galaxy at z=3.01
Le Floc'h, E.; Barmby, P.; Papovich, C. +16 more
We report the detection of rest-frame 6.2 and 7.7 µm emission features arising from polycyclic aromatic hydrocarbons (PAHs) in the Spitzer IRS spectrum of an infrared-luminous Lyman break galaxy at z=3.01. This is currently the highest redshift galaxy where these PAH emission features have been detected. The total IR luminosity inferred from…
The Resolved Stellar Populations of a Dwarf Spheroidal Galaxy in the Virgo Cluster
Ferguson, Henry C.; Williams, Benjamin F.; Gerhard, Ortwin +11 more
We report on the discovery of a faint (MV~-10.6+/-0.2) dwarf spheroidal galaxy on deep F606W and F814W Hubble Space Telescope images of a Virgo intracluster field. The galaxy is easily resolved in our images, as our color magnitude diagram (CMD) extends >~1 magnitude beyond the tip of the red giant branch (RGB). Thus, it is the deepe…
Diagnostics of Suprathermal Electrons in Active-Region Plasmas Using He-like UV Lines
Landi, E.; Doschek, G. A.; Feldman, U.
In the present paper we use UV lines emitted by He-like ions as a tool to test the presence of nonthermal high-energy electrons and to quantify their number and energy. The He-like lines we consider are the He-like 1s2s3S-1s2p3P lines observed in the UV, and their use capitalizes on the high excitation energies for the 1s2p