Search Publications
Hubble Space Telescope Space Telescope Imaging Spectrograph Spectroscopy of the Environment in the Starburst Core of M82
O'Connell, R. W.; Smith, L. J.; Gallagher, J. S., III +3 more
We present optical HST STIS observations made with two slits crossing four of the optically brightest starburst clumps near the nucleus of M82. These provide Hα kinematics, extinction, electron density, and emission measures. From the radial velocity curves derived from both slits we confirm the presence of a stellar bar. We derive a new model for…
Dynamics of the Narrow-Line Region in the Seyfert 2 Galaxy NGC 1068
Kraemer, S. B.; Crenshaw, D. M.; Das, V.
We present dynamical models based on a study of high-resolution long-slit spectra of the narrow-line region (NLR) in NGC 1068 obtained with the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope (HST). The dynamical models consider the radiative force due to the active galactic nucleus (AGN), gravitational forces from th…
Chandra and Hubble Space Telescope Observations of Gamma-Ray Blazars: Comparing Jet Emission at Small and Large Scales
Maraschi, L.; Wolter, A.; Cheung, C. C. +3 more
We present new Chandra and HST data for four gamma-ray blazars selected on the basis of radio morphology with the aim of revealing X-ray and optical emission from their jets at large scales. All the sources have been detected. Spectral energy distributions (SEDs) of the large-scale jets are obtained as well as new X-ray spectra for the blazar core…
GRO J1655-40: Early Stages of the 2005 Outburst
Smith, D. A.; Shrader, C. R.; Rupen, M. +4 more
The black hole X-ray binary transient GRO J1655-40 underwent an outburst beginning in early 2005. We present the results of our multiwavelength observational campaign to study the early outburst spectral and temporal evolution, which combines data from X-ray (RXTE and INTEGRAL), radio (VLA), and optical (ROTSE and SMARTS) instruments. During the r…
Progressive Star Formation in the Young SMC Cluster NGC 602
Tosi, M.; Sabbi, E.; Nota, A. +9 more
NGC 602 is a young stellar cluster located in a peripheral region of the Small Magellanic Cloud (SMC) known as the wing. Far from the main body of the galaxy and abutting the Magellanic Bridge, the SMC's wing is characterized by low gas and stellar content. With deep optical imaging from the Advanced Camera for Surveys (ACS) aboard the Hubble Spac…
21 cm Synthesis Observations of VIRGOHI 21-A Possible Dark Galaxy in the Virgo Cluster
Impey, Chris; van Driel, Wim; Davies, Jonathan +10 more
Many observations indicate that dark matter dominates the extragalactic universe, yet no totally dark structure of galactic proportions has ever been convincingly identified. Previously, we have suggested that VIRGOHI 21, a 21 cm source we found in the Virgo Cluster using Jodrell Bank, was a possible dark galaxy because of its broad line width (~2…
Fragmentation Hierarchy of Bright Sungrazing Comets and the Birth and Orbital Evolution of the Kreutz System. II. The Case for Cascading Fragmentation
Sekanina, Zdenek; Chodas, Paul W.
We examine the process of cascading fragmentation for the Kreutz sungrazer system to continue our exploration of its birth, orbital evolution, and temporal clumping. We modify and broaden the two-superfragment model from Paper I to include clusters of ~30 bright comets spanning four centuries and 1000 SOHO sungrazers from 1996 to 2006. The spectac…
A Correlation between Galaxy Morphology and Mg II Halo Absorption Strength
Kacprzak, Glenn G.; Steidel, Charles C.; Churchill, Christopher W. +2 more
We compared the quantified morphological properties of 37 intermediate redshift Mg II absorption selected galaxies to the properties of the absorbing halo gas [0.03 Å<=Wr(2796)<=2.90 Å], observed in the spectra of background quasars. The galaxy morphologies were measured using GIM2D modeling of Hubble Space Telescope WFPC2 images …
Evidence for a z < 8 Origin of the Source-subtracted Near-Infrared Background
Fan, Xiaohui; Kennicutt, Robert C.; Rieke, Marcia +2 more
This paper extends our previous fluctuation analysis of the near-infrared background at 1.6 µm to the 1.1 µm (F110W) image of the Hubble Ultra Deep Field. When all detectable sources are removed, the ratio of fluctuation power in the two images is consistent with the ratio expected for faint, z<8, sources, and is inconsistent with t…
Origin of the X-Ray Quasi-periodic Oscillations and Identification of a Transient Ultraluminous X-Ray Source in M82
Feng, Hua; Kaaret, Philip
The starburst galaxy M82 contains two ultraluminous X-ray sources (ULXs), CXOM82 J095550.2+694047 (=X41.4+60) and CXOM82 J095551.1+694045 (=X42.3+59), which are unresolved by XMM-Newton. We revisited the two XMM-Newton observations of M82 and analyzed the surface brightness profiles using the known Chandra source positions. We show that the quasi-…