Search Publications
The AGN Outflow in the HDF-S Target QSO J2233-606 from a High-Resolution VLT UVES Spectrum
Arav, Nahum; Kim, Tae-Sun; Gabel, Jack R.
We present a detailed analysis of the intrinsic UV absorption in the central HDF-S target QSO J2233-606, based on a high-resolution, high-S/N (~25-50) spectrum obtained with VLT UVES. This spectrum samples the cluster of intrinsic absorption systems outflowing from the AGN at radial velocities v~-5000 to -3800 km s-1 in the key far-UV d…
An Investigation into the Variability of Heating in a Solar Active Region
Winebarger, Amy R.; Warren, Harry P.; Ugarte-Urra, Ignacio
Previous studies have indicated that both steady and impulsive heating mechanisms play a role in active region heating. In this paper, we present a study of 20 hours of soft X-ray and EUV observations of solar active region NOAA AR 8731. We examine the evolution of six representative loop structures that brighten and fade first from X-ray images a…
The Evolution of the Mass Function Split by Morphology up to Redshift 1 in the FORS Deep and the GOODS-S Fields
Pannella, M.; Salvato, M.; Saglia, R. P. +5 more
We study the evolution of the stellar mass density for the separate families of bulge-dominated and disk-dominated galaxies over the redshift range 0.25<=z<=1.15. We derive quantitative morphology for a statistically significant galaxy sample of 1645 objects selected from the FORS Deep Field and the GOODS-S field. We find that the morphologi…
Identifications of Four INTEGRAL Sources in the Galactic Plane via Chandra Localizations
Kaaret, Philip; Walter, Roland; Tomsick, John A. +3 more
Hard X-ray imaging of the Galactic plane by the INTEGRAL satellite is uncovering large numbers of 20-100 keV ``IGR'' sources. We present results from Chandra, INTEGRAL, optical, and IR observations of four IGR sources: three sources in the Norma region of the Galaxy (IGR J16195-4945, IGR J16207-5129, and IGR J16167-4957) and one that is closer to …
Dense, Fe-rich Ejecta in Supernova Remnants DEM L238 and DEM L249: A New Class of Type Ia Supernova?
Reynolds, Stephen P.; Borkowski, Kazimierz J.; Hendrick, Sean P.
We present observations of two LMC supernova remnants (SNRs), DEM L238 and DEM L249, with the Chandra and XMM-Newton X-ray satellites. Bright central emission, surrounded by a faint shell, is present in both remnants. The central emission has an entirely thermal spectrum dominated by strong Fe L-shell lines, with the deduced Fe abundance in excess…
The First XMM-Newton Observations of the Soft Gamma-Ray Repeater SGR 1900+14
Tiengo, A.; Götz, D.; Mereghetti, S. +6 more
A ~50 ks XMM-Newton observation of SGR 1900+14 has been carried out in 2005 September, after almost 3 yr during which no bursts were detected from this soft gamma-ray repeater. The 0.8-10 keV spectrum was well fit by a power law plus blackbody model with photon index Γ=1.9+/-0.1, temperature kT=0.47+/-0.02 keV, and NH=(2.12+/-0.08)×10
Solar Source Regions for 3He-rich Solar Energetic Particle Events Identified Using Imaging Radio, Optical, and Energetic Particle Observations
Pick, M.; Wang, L.; Mason, G. M. +2 more
We have identified the sources of six impulsive 3He-rich solar energetic particle events using imaging radio, optical, and energetic ion and electron data, together with calculated coronal fields obtained from extrapolating photospheric magnetograms using a potential field source surface (PFSS) model. These events were all studied in 20…
Accretion and Nuclear Activity of Quiescent Supermassive Black Holes. II. Optical Study and Interpretation
Elvis, M.; Graham, Alister W.; Pellegrini, S. +5 more
Our X-ray study of the nuclear activity in a new sample of six quiescent early-type galaxies, as well as in a larger sample from the literature, confirmed (Paper I) that the Bondi accretion rate of diffuse hot gas is not a good indicator of the SMBH X-ray luminosity. Here we suggest that a more reliable estimate of the accretion rate must include …
Near-Infrared and the Inner Regions of Protoplanetary Disks
Ivezić, Željko; Jurkić, Tomislav; Vinković, Dejan +1 more
We examine the ``puffed-up inner disk'' model proposed by Dullemond, Dominik, & Natta for explaining the near-IR excess radiation from Herbig Ae/Be stars. Detailed model computations show that the observed near-IR excess requires more hot dust than is contained in the puffed-up disk rim. The rim can produce the observed near-IR excess only if …
Spitzer Space Telescope IRAC and MIPS Observations of the Interacting Galaxies IC 2163 and NGC 2207: Clumpy Emission
Brinks, Elias; Struck, Curtis; Elmegreen, Bruce G. +4 more
IC 2163 and NGC 2207 are interacting galaxies that have been well studied at optical and radio wavelengths and simulated in numerical models to reproduce the observed kinematics and morphological features. Spitzer IRAC and MIPS observations reported here show over 200 bright clumps from young star complexes. The brightest IR clump is a morphologic…