Search Publications
X-Ray Properties of an Unbiased Hard X-Ray-detected Sample of Active Galactic Nuclei
Mushotzky, Richard F.; Tueller, Jack; Markwardt, Craig +1 more
The Swift gamma-ray observatory's Burst Alert Telescope (BAT) has detected a sample of AGNs based solely on their hard X-ray flux (14-195 keV). In this paper we present for the first time XMM-Newton X-ray spectra for 22 BAT AGNs with no previously analyzed X-ray spectra. If our sources are a representative sample of the BAT AGNs, as we claim, our …
Deep Advanced Camera for Surveys Imaging in the Globular Cluster NGC 6397: the Cluster Color-Magnitude Diagram and Luminosity Function
Anderson, Jay; Dotter, Aaron; Rich, R. Michael +9 more
We present the color-magnitude diagram (CMD) from deep Hubble Space Telescope imaging in the globular cluster NGC 6397. The Advanced Camera for Surveys (ACS) was used for 126 orbits to image a single field in two colors (F814W, F606W) 5' SE of the cluster center. The field observed overlaps that of archival WFPC2 data from 1994 and 1997 which were…
3C 454.3 Reveals the Structure and Physics of Its "Blazar Zone"
Madejski, Greg M.; Sikora, Marek; Moderski, RafaŁ
Recent multiwavelength observations of 3C 454.3, in particular during its giant outburst in 2005, put severe constraints on the location of the "blazar zone," its dissipative nature, and high-energy radiation mechanisms. As the optical, X-ray, and millimeter light curves indicate, a significant fraction of the jet energy must be released in the vi…
Characteristic size and shape of the mirror mode structures in the solar wind at 0.72 AU
Russell, C. T.; Zhang, T. L.; Glassmeier, K. -H. +10 more
We investigate the structure of mirror modes in the solar wind at 0.72 AU using Venus Express magnetic field measurements. The mirror mode structure is identified as the presence of magnetic depression or magnetic ``holes'' in the solar wind with little or no directional change across them. We determine the characteristic size and shape of these s…
Tropical mountain glaciers on Mars: Altitude-dependence of ice accumulation, accumulation conditions, formation times, glacier dynamics, and implications for planetary spin-axis/orbital history
Head, James W.; Forget, Francois; Fastook, James L. +1 more
Fan-shaped deposits up to ∼166,000 km in area are found on the northwest flanks of the huge Tharsis Montes volcanoes in the tropics of Mars. Recent spacecraft data have confirmed earlier hypotheses that these lobate deposits are glacial in origin. Increased knowledge of polar-latitude terrestrial glacial analogs in the Antarctic Dry Valleys has be…
A comparison of coronal mass ejections identified by manual and automatic methods
Gopalswamy, N.; Michalek, G.; Yashiro, S.
Coronal mass ejections (CMEs) are related to many phenomena (e.g. flares, solar energetic particles, geomagnetic storms), thus compiling of event catalogs is important for a global understanding these phenomena. CMEs have been identified manually for a long time, but in the SOHO era, automatic identification methods are being developed. In order t…
The shape of the dark matter halo in the early-type galaxy NGC 2974
Krajnović, Davor; van de Ven, Glenn; Morganti, Raffaella +3 more
We present HI observations of the elliptical galaxy NGC 2974, obtained with the Very Large Array. These observations reveal that the previously detected HI disc in this galaxy is in fact a ring. By studying the harmonic expansion of the velocity field along the ring, we constrain the elongation of the halo and find that the underlying gravitationa…
First Imaging of Coronal Mass Ejections in the Heliosphere Viewed from Outside the Sun Earth Line
Howard, Russell A.; Bewsher, Danielle; Davis, Christopher J. +13 more
We show for the first time images of solar coronal mass ejections (CMEs) viewed using the Heliospheric Imager (HI) instrument aboard the NASA STEREO spacecraft. The HI instruments are wide-angle imaging systems designed to detect CMEs in the heliosphere, in particular, for the first time, observing the propagation of such events along the Sun - Ea…
Systematic Infrared 2.5-5 µm Spectroscopy of Nearby Ultraluminous Infrared Galaxies with AKARI
Nakagawa, Takao; Shirahata, Mai; Imanishi, Masatoshi +4 more
We report on the results of systematic infrared 2.5-5 µm spectroscopy of 45 nearby ultraluminous infrared galaxies (ULIRGs) at z < 0.3 using AKARI IRC. This paper investigates whether the luminosities of these ULIRGs are dominated by starburst activity, or alternatively, whether optically elusive buried active galactic nuclei (AGNs) are e…
Disks around CQ Tauri and MWC 758: dense PDR or gas dispersal?
Chapillon, E.; Guilloteau, S.; Dutrey, A. +1 more
Context: The overall properties of disks surrounding intermediate PMS stars (HAe) are not yet well constrained by current observations. The disk inclination, which significantly affects spectral energy distribution modeling, is often unknown.
Aims: We attempted to resolve the disks around CQ Tau and MWC 758 to provide accurate constraints on t…