Search Publications
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…
Rapid Changes of Photospheric Magnetic Fields around Flaring Magnetic Neutral Lines
Wang, Haimin
In this paper we study the short-term evolution of magnetic fields associated with five flares in δ-sunspots. We concentrate on the analysis of the magnetic gradient along the flaring neutral lines (NLs). Obvious changes of the magnetic gradient occurred immediately and rapidly following the onset of each flare. A rapid gradient increase was found…
Measuring the Average Evolution of Luminous Galaxies at z < 3: The Rest-Frame Optical Luminosity Density, Spectral Energy Distribution, and Stellar Mass Density
van Dokkum, Pieter G.; Franx, Marijn; Labbé, Ivo +11 more
We present the evolution of the volume-averaged properties of the rest-frame optically luminous (LV>3×1010 h-270 Lsolar) galaxy population to z~3, determined from four disjoint deep fields. We characterize their rest-frame UV through optical properties via the mean SED. To measure evolution…
Searching for Low Surface Brightness Galaxies in the Hubble Ultra Deep Field: Implications for the Star Formation Efficiency in Neutral Gas at z~3
Chen, Hsiao-Wen; Wolfe, Arthur M.
Applying the Kennicutt-Schmidt law to damped Lyα absorption systems (DLAs), we predict that 3% of the sky should be covered with extended objects brighter than µV~28.4 mag arcsec-2, if DLAs at redshift z=[2.5, 3.5] undergo in situ star formation. We test this hypothesis by searching the Hubble Ultra Deep Field (UDF) F60…