Search Publications
The Sextet Arcs: A Strongly Lensed Lyman Break Galaxy in the ACS Spectroscopic Galaxy Survey toward Abell 1689
Broadhurst, Tom; Frye, Brenda L.; Bowen, David V. +11 more
We present results of the HST Advanced Camera for Surveys spectroscopic ground-based redshift survey in the field of A1689. We measure 98 redshifts, increasing the number of spectroscopically confirmed objects sixfold. We present two spectra from this catalog of the Sextet Arcs, images that arise from a strongly lensed Lyman break galaxy (LBG) at …
Energy Distribution of Individual Quasars from Far-Ultraviolet to X-Rays. I. Intrinsic Ultraviolet Hardness and Dust Opacities
Nicastro, Fabrizio; Krongold, Yair; Humphrey, Andrew +4 more
Using Chandra and HST archival data, we have studied the individual SED of 11 quasars at redshifts 0.3<z<1.8. All UV spectra show a spectral break around 1100 Å. Five X-ray spectra showed the presence of a ``soft excess,'' and seven spectra showed an intrinsic absorption. We found that for most quasars a simple extrapolation of the far-UV po…
Magnetic Cycles in the Sun: Modeling the Changes in Radius, Luminosity, and p-Mode Frequencies
Mullan, D. J.; Townsend, R. H. D.; MacDonald, J.
We report on the results obtained with a stellar evolution code in which cyclic magnetic fields are imposed in the convection zone of a 1.0 Msolar star. Magnetic effects are incorporated in two ways: (1) the field pressure and energy density are included in the equations of hydrostatic equilibrium and conservation of energy; and (2) the…
Spatially Resolved X-Ray Spectra of NGC 4258
Yang, Y.; Li, B.; Reynolds, C. S. +1 more
We report a spatially resolved, X-ray spectral analysis of NGC 4258 using archival Chandra and XMM-Newton observations. The XMM-Newton spectrum of the nuclear region is well described by two power-law components, a soft (0.57 keV) thermal component and an Fe Kα line with EW=40+/-33 eV. The properties of the second, weaker power-law component are s…
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…