Search Publications
The Evolution and Eddington Ratio Distribution of Compton Thick Active Galactic Nuclei
Ballantyne, D. R.; Draper, A. R.
Previous studies of the active galactic nuclei (AGNs) contribution to the cosmic X-ray background (CXB) consider only observable parameters such as luminosity and absorbing column. Here, for the first time, we extend the study of the CXB to physical parameters including the Eddington ratio of the sources and the black hole mass. In order to calcul…
Morphologies of Radio-, X-ray-, and Mid-infrared-selected Active Galactic Nuclei
Griffith, Roger L.; Stern, Daniel
We investigate the optical morphologies of candidate active galaxies identified at radio, X-ray, and mid-infrared wavelengths. We use the Advanced Camera for Surveys General Catalog (ACS-GC) to identify 372, 1360, and 1238 active galactic nucleus (AGN) host galaxies from Very Large Array, XMM-Newton, and Spitzer Space Telescope observations of the…
The Morphology of IRC+10420's Circumstellar Ejecta
Humphreys, Roberta M.; Davidson, Kris; Jones, Terry J. +1 more
Images of the circumstellar ejecta associated with the post-red supergiant IRC+10420 show a complex ejecta with visual evidence for episodic mass loss. In this paper, we describe the transverse motions of numerous knots, arcs, and condensations in the inner ejecta measured from second epoch Hubble Space Telescope/WFPC2 images. When combined with t…
X-ray monitoring of classical novae in the central region of M 31. I. June 2006-March 2007
Della Valle, M.; Pietsch, W.; Haberl, F. +9 more
Context. Classical novae (CNe) have recently been reported to represent the major class of supersoft X-ray sources (SSSs) in the central region of our neighbour galaxy M 31.
Aims: We carried out a dedicated monitoring of the M 31 central region with XMM-Newton and Chandra in order to find SSS counterparts of CNe, determine the duration of the…
THEMIS observations of substorms on 26 February 2008 initiated by magnetotail reconnection
Russell, C. T.; Wei, Y.; Glassmeier, K. -H. +25 more
On 26 February 2008, the THEMIS satellites observed two substorms that occurred at about 0405 and 0455 UT. Angelopoulos et al. (2008) made a comprehensive study of the second event. In this paper we display detailed features of the two substorms with emphasis on the first. In both substorms, a distinct auroral intensification occurred during the e…
Self-Reformation of the Quasi-Perpendicular Shock: CLUSTER Observations
Dandouras, I.; Génot, V.; Lembège, B. +5 more
Among several mechanisms issued from simulation and theoretical studies proposed to account for the nonstationarity of quasi-perpendicular supercritical shocks, one process-the so-called self-reformation-driven by the accumulation of reflected ions in the foot has been intensively analyzed with simulations. Present results based on experimental CL…
X-Ray Emission from HESS J1731-347/SNR G353.6-0.7 and Central Compact Source XMMS J173203-344518
Leahy, D. A.; Li, Z.; Tian, W. W. +4 more
We present new results of the HESS J1731-347/SNR G353.6-0.7 system from XMM-Newton and Suzaku X-ray observations and Delinha CO observations. We discover extended hard X-rays coincident with the bright, extended TeV source HESS J1731-347 and the shell of the radio supernova remnant (SNR). We find that spatially resolved X-ray spectra can generally…
Analysis of a Global Moreton Wave Observed on 2003 October 28
Magdalenić, J.; Temmer, M.; Veronig, A. M. +2 more
We study the well-pronounced Moreton wave that occurred in association with the X17.2 flare/CME event of 2003 October 28. This Moreton wave is striking for its global propagation and two separate wave centers, which implies that two waves were launched simultaneously. The mean velocity of the Moreton wave, tracked within different sectors of propa…
Multi-transition Study of M51'S Molecular Gas Spiral Arms
Schinnerer, E.; Scoville, N. Z.; Aalto, S. +1 more
Two selected regions in the molecular gas spiral arms in M51 were mapped with the Owens Valley Radio Observatory (OVRO) mm-interferometer in the 12CO(2-1), 13CO(1-0), C18O(1-0), HCN(1-0), and HCO+(1-0) emission lines. The CO data have been combined with the 12CO(1-0) data from Aalto et al. covering the c…
Threshold of wave generation on Titan’s lakes and seas: Effect of viscosity and implications for Cassini observations
Lorenz, Ralph D.; Lunine, Jonathan I.; Newman, Claire
Motivated by radar and near-infrared data indicating that Titan's polar lakes are extremely smooth, we consider the conditions under which a lake surface will be ruffled by wind to form capillary waves. We evaluate laboratory data on wind generation and derive, without scaling for surface tension effects, a threshold for pure methane/ethane of ∼0.…