Search Publications
XMM-Newton Observations of a Complete Sample of Optically Selected Type 2 Seyfert Galaxies
Heckman, Timothy M.; Hornschemeier, Ann; Tremonti, Christy +4 more
The majority of active galactic nuclei (AGNs) suffer from significant obscuration by surrounding dust and gas. The penetrating power and sensitivity of hard X-ray observations allow obscured AGNs to be probed out to high redshifts. However, X-ray surveys in the 2-10 keV band will miss the most heavily obscured AGNs in which the absorbing column de…
From outburst to quiescence: the decay of the transient AXP XTE J1810-197
Campana, S.; Tiengo, A.; Götz, D. +10 more
Aims: XTE J1810-197 is the first transient anomalous X-ray pulsar ever discovered. Its highly variable X-ray flux allowed us to study the timing and spectral emission properties of a magnetar candidate over a flux range of about two orders of magnitude.
Methods: We analyzed nine XMM-Newton observations of XTE J1810-197 collected over a four ye…
Calculation of the local standard of rest from 20 574 local stars in the New Hipparcos Reduction with known radial velocities
Francis, Charles; Anderson, Erik
ContextAn accurate estimate of the local standard of rest (LSR) is required to determine key parameters used in approximate galactic mass models and to understand Galactic structure and evolution. However, authors are often forced to base dynamical analyses on potentially unreliable figures because recent determinations of the LSR have failed to r…
On the character and distribution of lower-frequency radio emissions at Saturn and their relationship to substorm-like events
Dougherty, M. K.; Jackman, C. M.; Kurth, W. S. +5 more
With the arrival of the Cassini spacecraft at Saturn in July 2004, there have been quasi-continuous observations of Saturn kilometric radiation (SKR) emissions. Exploration of the nightside magnetosphere has revealed evidence of plasmoid-like magnetic structures and other phenomena indicative of the Kronian equivalent of terrestrial substorms. In …
A Suzaku Search for Nonthermal Emission at Hard X-Ray Energies in the Coma Cluster
Sarazin, Craig L.; Nakazawa, Kazuhiro; Wik, Daniel R. +3 more
The brightest cluster radio halo known resides in the Coma cluster of galaxies. The relativistic electrons producing this diffuse synchrotron emission should also produce inverse Compton emission that becomes competitive with thermal emission from the intracluster medium (ICM) at hard X-ray energies. Thus far, claimed detections of this emission i…
Multispacecraft recovery of a magnetic cloud and its origin from magnetic reconnection on the Sun
Luhmann, J. G.; Möstl, C.; Farrugia, C. J. +8 more
Multipoint spacecraft observations of a magnetic cloud on 22 May 2007 have given us the opportunity to apply a multispacecraft technique to infer the structure of this large-scale magnetic flux rope in the solar wind. Combining WIND and STEREO-B magnetic field and plasma measurements, we construct a combined magnetic field map by integrating the G…
X-Ray Jet Dynamics in a Polar Coronal Hole Region
Golub, Leon; Filippov, Boris; Koutchmy, Serge
New X-ray observations of the north polar region taken from the X-ray Telescope (XRT) of the Hinode spacecraft are used to analyze several time sequences showing small loop brightenings with a long ray above. We focus on the formation of the jet and discuss scenarios to explain the main features of the events: the relationship with the expected su…
Distribution of hydrated minerals in the north polar region of Mars
Mustard, J. F.; Noe Dobrea, E. Z.; Bell, J. F. +5 more
The previous discovery of extensive deposits of hydrated minerals in Olympia Planum in the north polar region of Mars by the Mars Express OMEGA instrument raises important questions about the origin and subsequent redistribution of these hydrated minerals. Here we present a new map of the distribution of hydrated minerals within the north polar re…
Transit infrared spectroscopy of the hot Neptune around GJ 436 with the Hubble Space Telescope
Pont, F.; Knutson, H.; Gilliland, R. L. +2 more
The nearby transiting system GJ 436b offers a unique opportunity to probe the structure and atmosphere of an extrasolar `hot Neptune'. In this Letter, we present the main results of observations covering two transit events with the Near Infrared Camera and Multi Object Spectrograph (NICMOS) camera on the Hubble Space Telescope (HST). The data cons…
The Optical Structure of the Starburst Galaxy M82. II. Nebular Properties of the Disk and Inner Wind
Bastian, N.; Gallagher, J. S.; Smith, L. J. +3 more
In this second paper of the series, we present the results from optical Gemini-North GMOS-IFU and WIYN DensePak IFU spectroscopic observations of the starburst and inner wind zones of M82, with a focus on the state of the T ~ 104 K ionized interstellar medium. Our electron density maps show peaks of a few 1000 cm-3 (implying …