Search Publications
Photometric Selection of QSO Candidates from GALEX Sources
Gould, Andrew; Atlee, David W.
We present a catalog of 36,120 QSO candidates from the Galaxy Evolution Explorer (GALEX) Release Two (GR2) UV catalog and the USNO-A2.0 optical catalog. The selection criteria are established using known quasars from the Sloan Digital Sky Survey (SDSS). The SDSS sample is then used to assign individual probabilities to our GALEX USNO candidates. T…
AEGIS: Infrared Spectroscopy of an Infrared-luminous Lyman Break Galaxy at z=3.01
Le Floc'h, E.; Barmby, P.; Papovich, C. +16 more
We report the detection of rest-frame 6.2 and 7.7 µm emission features arising from polycyclic aromatic hydrocarbons (PAHs) in the Spitzer IRS spectrum of an infrared-luminous Lyman break galaxy at z=3.01. This is currently the highest redshift galaxy where these PAH emission features have been detected. The total IR luminosity inferred from…
The Resolved Stellar Populations of a Dwarf Spheroidal Galaxy in the Virgo Cluster
Ferguson, Henry C.; Williams, Benjamin F.; Gerhard, Ortwin +11 more
We report on the discovery of a faint (MV~-10.6+/-0.2) dwarf spheroidal galaxy on deep F606W and F814W Hubble Space Telescope images of a Virgo intracluster field. The galaxy is easily resolved in our images, as our color magnitude diagram (CMD) extends >~1 magnitude beyond the tip of the red giant branch (RGB). Thus, it is the deepe…
Diagnostics of Suprathermal Electrons in Active-Region Plasmas Using He-like UV Lines
Landi, E.; Doschek, G. A.; Feldman, U.
In the present paper we use UV lines emitted by He-like ions as a tool to test the presence of nonthermal high-energy electrons and to quantify their number and energy. The He-like lines we consider are the He-like 1s2s3S-1s2p3P lines observed in the UV, and their use capitalizes on the high excitation energies for the 1s2p
The Abundance of Deuterium in the Warm Neutral Medium of the Lower Galactic Halo
Savage, Blair D.; Lehner, Nicolas; Fox, Andrew +2 more
We use high-resolution ultraviolet spectra to obtain Milky Way interstellar column densities of H I, D I, O I, S II, Fe II, and P II toward the QSO HE 0226-4110 in the Galactic direction l=253.4deg and b=-65.77deg. We obtain D/H=21+8-6 ppm from an analysis of the strong damped Lyα line of H I and the wea…
A Compact Cluster of Massive Red Galaxies at a Redshift of 1.5
Glazebrook, Karl; McCarthy, Patrick J.; Yan, Haojing +15 more
We describe a compact cluster or group of massive red galaxies at z=1.5 discovered in one of the Gemini Deep Deep Survey (GDDS) fields. Deep H-band imaging from the Hubble Space Telescope (HST) reveals a high density of red galaxies associated with a galaxy with a spectroscopic redshift of 1.51. These galaxies have spectral energy distributions (S…
Black Hole Masses and Eddington Ratios of AGNs at z < 1: Evidence of Retriggering for a Representative Sample of X-Ray-selected AGNs
Danese, L.; Ballo, L.; Tozzi, P. +10 more
We estimated black hole masses and Eddington ratios for a sample of X-ray-selected active galactic nuclei (AGNs) in the fields covered by the Great Observatory Origins Deep Survey (GOODS). The spanned ranges in redshift (0.4<z<1) and hard X-ray luminosity (1042<~LX<~4×1043 ergs s-1) allow us …
Variability of Moderate-Luminosity Active Galactic Nuclei at z = 0.36
Treu, Tommaso; Malkan, Matthew A.; Woo, Jong-Hak +2 more
We monitored 13 moderate-luminosity active galactic nuclei at z=0.36 to measure flux variability, explore feasibility of reverberation mapping, and determine uncertainties on estimating black hole mass from single-epoch data. Spectra and images were obtained with approximately weekly cadence for up to 4 months, using the Kast spectrograph on the 3…
The Variation of Magnesium Depletion with Line-of-Sight Conditions
Snow, Theodore P.; Jensen, Adam G.
In this paper we report on the gas-phase abundance of singly ionized magnesium (Mg II) in 44 lines of sight, using data from the Hubble Space Telescope (HST). We measure Mg II column densities by analyzing medium- and high-resolution archival Space Telescope Imaging Spectrograph (STIS) spectra of the 1240 Å doublet of Mg II. We find that Mg II dep…
X-Ray Localization of the Globular Cluster G1 with XMM-Newton
Kong, Albert K. H.
We present an accurate X-ray position of the massive globular cluster G1 obtained using XMM-Newton and the Hubble Space Telescope (HST). The X-ray emission of G1 has been detected recently with XMM-Newton. There are two possibilities for the origin of the X-ray emission: it could be due to either accretion of the central intermediate-mass black ho…