Search Publications
The ACS Virgo Cluster Survey. XIV. Analysis of Color-Magnitude Relations in Globular Cluster Systems
Jordán, Andrés; Mieske, Steffen; Tonry, John L. +8 more
We examine the correlation between globular cluster (GC) color and magnitude using HST ACS imaging for a sample of 79 early-type galaxies (-21.7<MB<-15.2 mag) with accurate SBF distances from the ACS Virgo Cluster Survey. Using the KMM mixture modeling algorithm, we find a highly significant correlation, γz≡d(g-z)/dz=-0…
Multiwavelength Observations of GRB 050820A: An Exceptionally Energetic Event Followed from Start to Finish
Cenko, S. B.; Price, P. A.; Harrison, F. A. +24 more
We present observations of the unusually bright and long γ-ray burst GRB 050820A, one of the best sampled broadband data sets in the Swift era. The γ-ray light curve is marked by a soft precursor pulse some 200 s before the main event; the lack of any intervening emission suggests that it is due to a physical mechanism distinct from the GRB itself…
Probing Cosmic Star Formation Using Long Gamma-Ray Bursts: New Constraints from the Spitzer Space Telescope
Armus, Lee; Le Floc'h, Emeric; Mirabel, I. Félix +3 more
We report on IRAC 4.5 µm, IRAC 8.0 µm, and MIPS 24 µm deep observations of 16 gamma-ray burst (GRB) host galaxies performed with the Spitzer Space Telescope, and we investigate in the thermal infrared the presence of evolved stellar populations and dust-enshrouded star-forming activity associated with these objects. Our sample is…
Observational Evidence of Gentle Chromospheric Evaporation during the Impulsive Phase of a Solar Flare
Milligan, Ryan O.; Gallagher, Peter T.; Mathioudakis, Mihalis +1 more
Observational evidence of gentle chromospheric evaporation during the impulsive phase of a C9.1 solar flare is presented using data from the Reuven Ramaty High-Energy Solar Spectroscopic Imager and the Coronal Diagnostic Spectrometer on board the Solar and Heliospheric Observatory. Until now, evidence of gentle evaporation has often been reported …
Evolution of the Color-Magnitude Relation in High-Redshift Clusters: Early-Type Galaxies in the Lynx Supercluster at z ~ 1.26
Franx, Marijn; Illingworth, Garth D.; Postman, Marc +10 more
Color-magnitude relations (CMRs) have been derived in two high-redshift clusters, RX J0849+4452 and RX J0848+4453 (with redshifts of z=1.26 and 1.27, respectively), that lie in the highest redshift cluster superstructure known today, the Lynx Supercluster. The CMR was determined from ACS imaging in the WFC F775W (i775) and F850LP (z
The O VII X-Ray Forest toward Markarian 421: Consistency between XMM-Newton and Chandra
Kaastra, J. S.; de Plaa, J.; de Vries, C. P. +4 more
Recently, the first detections of highly ionized gas associated with two warm-hot intergalactic medium (WHIM) filaments have been reported. The evidence is based on X-ray absorption lines due to O VII and other ions observed by Chandra toward the bright blazar Mrk 421. We investigate the robustness of this detection by a reanalysis of the original…
A Deep Hubble Space Telescope H-Band Imaging Survey of Massive Gas-rich Mergers
Lutz, D.; Genzel, R.; Tacconi, L. J. +6 more
We report the results from a deep HST NICMOS H-band imaging survey of a carefully selected sample of 33 luminous, late-stage galactic mergers at z<0.3. This program is part of QUEST (Quasar/ULIRG Evolutionary Study). Signs of a recent galactic interaction are seen in all of these objects, including all seven IR-excess Palomar-Green (PG) QSOs in…
Fundamental Properties of O-Type Stars
Hubeny, Ivan; Heap, Sara R.; Lanz, Thierry
We present a comprehensive analysis of high-resolution, far-ultraviolet HST STIS, FUSE, and optical spectra of 18 O stars in the Small Magellanic Cloud. Our analysis is based on the OSTAR2002 grid of NLTE metal-line-blanketed model atmospheres calculated with our code TLUSTY. We systematically explore and present the sensitivity of various UV and …
Shedding New Light on the 3C 273 Jet with the Spitzer Space Telescope
Cheung, C. C.; Takahashi, Tadayuki; Van Duyne, Jeffrey +7 more
We have performed infrared imaging of the jet of the quasar 3C 273 at wavelengths of 3.6 and 5.8 µm with the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. When combined with the radio, optical, and X-ray measurements, the IRAC photometry of the X-ray-bright jet knots clearly shows that the optical emission is dominated by the …
The First INTEGRAL AGN Catalog
Gehrels, N.; Shrader, C. R.; Beckmann, V. +1 more
We present the first INTEGRAL AGN catalog, based on observations performed from launch of the mission in 2002 October until 2004 January. The catalog includes 42 AGNs, of which 10 are Seyfert 1, 17 are Seyfert 2, and 9 are intermediate Seyfert 1.5. The fraction of blazars is rather small, with five detected objects, and only one galaxy cluster and…