Search Publications
Missions
Journals
Publication Years
A Hubble Space Telescope lensing survey of X-ray luminous galaxy clusters - IV. Mass, structure and thermodynamics of cluster cores at z= 0.2
Smith, Graham P.; Smail, Ian; Kneib, Jean-Paul +3 more
We present a comprehensive space-based study of 10 X-ray luminous galaxy clusters (LX>= 8 × 1044 erg s-1, 0.1-2.4 keV) at z= 0.2. Hubble Space Telescope (HST) observations reveal numerous gravitationally lensed arcs for which we present four new spectroscopic redshifts, bringing the total to 13 confirmed arcs in…
The Relationship of Hard X-Ray and Optical Line Emission in Low-Redshift Active Galactic Nuclei
Ptak, A.; Heckman, T. M.; Hornschemeier, A. +1 more
In this paper we assess the relationship of the population of active galactic nuclei (AGNs) selected by hard X-rays to the traditional population of AGNs with strong optical emission lines. First, we study the emission-line properties of a new hard-X-ray-selected sample of 47 local AGNs (classified optically as Type 1 and 2 AGNs). We find that the…
The ACS Virgo Cluster Survey. VII. Resolving the Connection between Globular Clusters and Ultracompact Dwarf Galaxies
Djorgovski, S. G.; Jordán, Andrés; Tonry, John L. +10 more
We investigate the connection between globular clusters and ultracompact dwarf galaxies (UCDs) by examining the properties of 10 compact, high-luminosity (-11.8 MV -10.8) objects associated with M87 (NGC 4486, VCC 1316), the cD galaxy in the Virgo Cluster. These objects, most of which were previously classified as M87 globular clusters, were selec…
Soft X-Ray and Ultraviolet Emission Relations in Optically Selected AGN Samples
Brandt, W. N.; Schneider, Donald P.; Vignali, Cristian +2 more
Using a sample of 228 optically selected active galactic nuclei (AGNs) in the 0.01-6.3 redshift range with a high fraction of X-ray detections (81%-86%), we study the relation between rest-frame UV and soft X-ray emission and its evolution with cosmic time. The majority of the AGNs in our sample (155 objects) have been selected from the Sloan Digi…
The ACS Virgo Cluster Survey. X. Half-Light Radii of Globular Clusters in Early-Type Galaxies: Environmental Dependencies and a Standard Ruler for Distance Estimation
Sarazin, Craig L.; Jordán, Andrés; Tonry, John L. +10 more
We have measured half-light radii, rh, for thousands of globular clusters (GCs) belonging to the 100 early-type galaxies observed in the ACS Virgo Cluster Survey and the elliptical galaxy NGC 4697. An analysis of the dependencies of the measured half-light radii on both the properties of the GCs themselves and their host galaxies reveal…
Infrared Spectral Energy Distributions of Nearby Galaxies
Helou, G.; Roussel, H.; Leitherer, C. +25 more
The Spitzer Infrared Nearby Galaxies Survey (SINGS) is carrying out a comprehensive multiwavelength survey on a sample of 75 nearby galaxies. The 1-850 µm spectral energy distributions (SEDs) are presented using broadband imaging data from Spitzer, 2MASS, ISO, IRAS, and SCUBA. The infrared colors derived from the globally integrated Spitzer …
An Intermediate-Mass Black Hole in the Globular Cluster G1: Improved Significance from New Keck and Hubble Space Telescope Observations
Ho, Luis C.; Gebhardt, Karl; Rich, R. M.
We present dynamical models for the massive globular cluster G1. The goal is to measure or place a significant upper limit on the mass of any central black hole. Whether or not globular clusters contain central massive black holes has important consequences for a variety of studies. We use new kinematic data obtained with Keck and new photometry f…
What controls the CIV line profile in active galactic nuclei?
Laor, Ari; Baskin, Alexei
The high-ionization lines in active galactic nuclei (AGN), such as CIV, tend to be blueshifted with respect to the lower-ionization lines, such as Hβ, and often show a strong blue excess asymmetry not seen in the low-ionization lines. There is accumulating evidence that the Hβ profile is dominated by gravity, and thus provides a useful estimate of…
The Assembly History of Field Spheroidals: Evolution of Mass-to-Light Ratios and Signatures of Recent Star Formation
Treu, Tommaso; van Dokkum, Pieter G.; Coil, Alison +6 more
We present a comprehensive catalog of high signal-to-noise ratio spectra obtained with DEIMOS on the Keck II telescope for a sample of F850LP<22.43 (AB) field spheroidal (E+S0 galaxies; 165) and bulge-dominated disk (61) galaxies in the redshift range 0.2<z<1.2, selected on the basis of visual morphology from the northern field of the Gre…
Lower mass loss rates in O-type stars: Spectral signatures of dense clumps in the wind of two Galactic O4 stars
Bouret, J. -C.; Hillier, D. J.; Lanz, T.
We have analyzed the far-ultraviolet spectrum of two Galactic O4 stars, the O4If+ supergiant HD 190429A and the O4V((f)) dwarf HD 96715, using archival FUSE and IUE data. We have conducted a quantitative analysis using the two NLTE model atmosphere and wind codes, tlusty and cmfgen, which incorporate a detailed treatment of NLTE metal line blanket…