Search Publications
X-Ray/Ultraviolet Observing Campaign of the Markarian 279 Active Galactic Nucleus Outflow: A Global-Fitting Analysis of the Ultraviolet Absorption
Laor, Ari; Scott, Jennifer E.; Kriss, Gerard A. +12 more
We present an analysis of the intrinsic UV absorption in the Seyfert 1 galaxy Mrk 279 based on simultaneous long observations with the Hubble Space Telescope (41 ks) and the Far Ultraviolet Spectroscopic Explorer (91 ks). To extract the line-of-sight covering factors and ionic column densities, we separately fit two groups of absorption lines: the…
The Far-Infrared Emission Line and Continuum Spectrum of the Seyfert Galaxy NGC 1068
Smith, Howard A.; González-Alfonso, Eduardo; Spinoglio, Luigi +2 more
We report on the analysis of the first complete far-infrared spectrum (43-197 µm) of the Seyfert 2 galaxy NGC 1068 as observed with the Long Wavelength Spectrometer (LWS) on board the Infrared Space Observatory (ISO). In addition to the seven expected ionic fine-structure emission lines, the OH rotational lines at 79, 119, and 163 µm w…
INTEGRAL SPI Limits on Electron-Positron Annihilation Radiation from the Galactic Plane
Hornstrup, A.; Parmar, A. N.; Güdel, M. +25 more
The center of our Galaxy is a known strong source of electron-positron 511 keV annihilation radiation. Thus far, however, there have been no reliable detections of annihilation radiation outside of the central radian of our Galaxy. One of the primary objectives of the INTEGRAL (International Gamma-Ray Astrophysics Laboratory) mission, launched in …
The Hot Intergalactic Medium-Galaxy Connection: Two Strong O VI Absorbers in the Sight Line toward PG 1211+143
Shull, J. Michael; Stocke, John T.; Tumlinson, Jason +1 more
We present Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) and Far Ultraviolet Spectroscopic Explorer (FUSE) spectra of the QSO PG 1211+143 (zem=0.081) and a galaxy survey of the surrounding field. This sight line shows two strong intergalactic absorption systems at cz~=15,300 and 19,300 km s-1. This …
First Optical Images of Circumstellar Dust Surrounding the Debris Disk Candidate HD 32297
Kalas, Paul
Near-infrared imaging with the Hubble Space Telescope recently revealed a circumstellar dust disk around the A star HD 32297. Dust-scattered light is detected as far as 400 AU radius, and the linear morphology is consistent with a disk ~10° away from an edge-on orientation. Here we present the first optical images that show the dust-scattered ligh…
Non-LTE Model Atmosphere Analysis of the Large Magellanic Cloud Supersoft X-Ray Source CAL 83
Rasmussen, Andrew P.; Paerels, Frits; Hubeny, Ivan +3 more
We present a non-LTE (NLTE) model atmosphere analysis of Chandra High Resolution Camera (HRC-S) and Low Energy Transmission Grating (LETG) and XMM-Newton Reflection Grating Spectrometer (RGS) spectroscopy of the prototypical supersoft source CAL 83 in the Large Magellanic Cloud. Taken with a 16 month interval, the Chandra and XMM-Newton spectra ar…
Star Cluster Survival in Star Cluster Complexes under Extreme Residual Gas Expulsion
Kroupa, P.; Fellhauer, M.
After the stars of a new, embedded star cluster have formed, they blow the remaining gas out of the cluster. Especially winds of massive stars and definitely the onset of the first supernovae can remove the residual gas from a cluster. This leads to a very violent mass loss and leaves the cluster out of dynamical equilibrium. Standard models predi…
The Spectral Evolution of Transient Anomalous X-Ray Pulsar XTE J1810-197
Gotthelf, E. V.; Halpern, J. P.
We present a multiepoch spectral study of the transient anomalous X-ray pulsar XTE J1810-197 obtained with the X-Ray Multi-Mirror Mission (XMM-Newton). Four observations taken over the course of a year reveal strong spectral evolution as the source fades from outburst. The origin of this is traced to the individual decay rates of the pulsar's spec…
The Core of NGC 6240 from Keck Adaptive Optics and Hubble Space Telescope NICMOS Observations
Antonucci, R.; Schneider, G.; Canalizo, G. +4 more
We present results of near-infrared imaging of the disk-galaxy merger NGC 6240 using adaptive optics on the Keck II telescope and reprocessed archival data from NICMOS on the Hubble Space Telescope. Both the northern and southern nuclei of NGC 6240 are clearly elongated, with considerable substructure within each nucleus. In K' band there are at l…
A Near-Solar Metallicity, Nitrogen-deficient Lyman Limit Absorber Associated with Two S0 Galaxies
Bowen, David V.; Tripp, Todd M.; Jenkins, Edward B. +1 more
The UV spectrum of the bright quasar PHL 1811 at zem=0.192 reveals a foreground gas system at z=0.080923 with logN(HI)=17.98+/-0.05. We have determined the abundances of various atomic species in this system from a spectrum covering the wavelength range 1160-1730 Å recorded at 7 km s-1 resolution by the E140M grating of the S…