Search Publications
Downscattering Due to Wind Outflows in Compact X-Ray Sources: Theory and Interpretation
Titarchuk, Lev; Shrader, Chris
A number of recent lines of evidence point toward the presence of hot, outflowing plasma from the central regions of compact Galactic and extragalactic X-ray sources. In addition, it has long been noted that many of these sources exhibit an ``excess'' continuum component above ~10 keV, usually attributed to Compton reflection from a static medium.…
Submillimeter Imaging of RCS J022434-0002.5: Intense Activity in a High-Redshift Cluster?
Gladders, M. D.; Ivison, R. J.; Hoekstra, H. +4 more
We present deep 850 µm imaging of the z=0.773 strong lensing galaxy cluster RCS J022434-0002.5 from the Red-Sequence Cluster Survey (RCS). These data are part of a larger submillimeter survey of RCS clusters with SCUBA on the JCMT. We find five objects at 850 µm, all of which are also detected at either 1.4 GHz or 450 µm, or both…
The Proto-Planetary Nebula M1-92 and the Symbiotic Star MWC 560: Two Evolutionary Phases of the Same Type of Object?
Torres-Peimbert, S.; Georgiev, L.; Arrieta, A.
Important similarities between the objects M1-92, a proto-planetary nebula of bipolar morphology, and MWC 560, a symbiotic star with a jet, have been found. A brief review of the previous studies for both objects is presented for the purpose of proposing mechanisms that best explain these similarities, since up to now both objects have been studie…
Chandra and XMM-Newton Observations of the Exceptional Pulsar B0628-28
Ögelman, H.; Tepedelenlıoǧlu, E.
PSR B0628-28 is a radio pulsar that was first detected in the X-ray band by ROSAT and then later observed with Chandra and XMM-Newton. The Chandra observation yielded an X-ray luminosity 2 orders of magnitude higher than what is expected for spin-powered pulsars; also, there were no pulsations detected. The XMM-Newton observation, however, reveals…
Modeling Solar Oscillation Power Spectra. I. Adaptive Response Function for Doppler Velocity Measurements
Jefferies, Stuart M.; Vorontsov, Sergei V.
Improving the accuracy and resolution of helioseismic inversions calls for more accurate modeling of the observational p-mode power spectra from which the solar oscillation frequencies are traditionally measured. We present a new technique of calculating the response function (leakage matrix) for Doppler velocity measurements that is based largely…
Host Galaxies of High-Redshift Active Galactic Nuclei in the Great Observatories Origins Deep Surveys Fields
Akiyama, Masayuki
The star formation rates and the stellar masses of the host galaxies of active galactic nuclei (AGNs) at high redshifts are key to understanding the evolution of the relation between the mass of the spheroidal component of a galaxy and the mass of its central black hole (Mbulge-M• relation). We investigate the host galaxies o…
OH Rotational Lines as a Diagnostic of the Warm Neutral Gas in Galaxies
Cernicharo, José; Goicoechea, Javier R.; Martín-Pintado, Jesus
We present Infrared Space Observatory (ISO) observations of several OH, CH, and H2O rotational lines toward the bright infrared galaxies NGC 253 and NGC 1068. As found in the Galactic clouds in Sgr B2 and Orion, the extragalactic far-IR OH lines change from absorption to emission depending on the physical conditions and distribution of …
Detection of Absorption Features in the X-Ray Spectrum of the Narrow-Line Quasar PG 1404+226: Possible Evidence of Accretion Disk Winds
Rao, A. R.; Dewangan, G. C.; Dasgupta, Surajit +1 more
We present the results of an analysis of data from XMM-Newton and Chandra observations of the high-luminosity narrow-line quasar PG 1404+226. We confirm a strong soft X-ray excess in the X-ray spectrum, and we find rapid variability (a factor of 2 in about 5000 s). When the X-ray spectrum is fitted with a two-component model that includes a power-…
Optical Sources near the Bright X-Ray Source in NGC 1073
Kaaret, Philip
New HST observations show that the bright X-ray source in the face-on spiral galaxy NGC 1073 is located near a ring of recent star formation with an age of 8-16 Myr. This strengthens the association of X-ray sources in spiral galaxies emitting near or above the Eddington limit for a 20 Msolar black hole with recent star formation events…
Direct Evidence for a Polar Spot on SV Camelopardalis
Jeffers, S. V.; Collier Cameron, A.; Barnes, J. R. +2 more
We have used spectrophotometric data from the Hubble Space Telescope (HST) to eclipse-map the primary component of the RS CVn binary SV Cam over nine HST orbits. We find from these observations and the Hipparcos parallax that the surface flux in the eclipsed low-latitude region of the primary is about 30% lower than that computed from a PHOENIX mo…