Search Publications
UV star-formation rates of GRB host galaxies
Christensen, L.; Gorosabel, J.; Hjorth, J.
We study a magnitude-limited sample of 10 gamma-ray burst (GRB) host galaxies with known spectroscopic redshifts (0.43 < z < 2.04). From an analysis of the spectral energy distributions (SEDs), based on published broad-band optical and near-infrared photometry, we derive photometric redshifts, galaxy types, ages of the dominant stellar popul…
Photoionization Modeling and the K Lines of Iron
Kallman, T. R.; Krolik, J. H.; Bautista, M. A. +2 more
We calculate the efficiency of iron K line emission and iron K absorption in photoionized models using a new set of atomic data. These data are more comprehensive than those previously applied to the modeling of iron K lines from photoionized gases and allow us to systematically examine the behavior of the properties of line emission and absorptio…
Detection of a Neptune-Mass Planet in the ρ1 Cancri System Using the Hobby-Eberly Telescope
Butler, R. Paul; Cochran, William D.; Endl, Michael +9 more
We report the detection of the lowest mass extrasolar planet yet found around a Sun-like star-a planet with an Msini of only 14.21+/-2.91 M⊕ in an extremely short period orbit (P=2.808 days) around ρ1 Cancri, a planetary system that already has three known planets. Velocities taken from late 2003-2004 at McDonald Observatory …
The Fall of Active Galactic Nuclei and the Rise of Star-forming Galaxies: A Close Look at the Chandra Deep Field X-Ray Number Counts
Hornschemeier, A. E.; Alexander, D. M.; Treister, E. +4 more
We investigate the X-ray number counts in the 1-2 Ms Chandra Deep Fields (CDFs) to determine the contributions of faint X-ray source populations to the extragalactic X-ray background (XRB). X-ray sources were separated into active galactic nuclei (AGNs), star-forming galaxies, and Galactic stars primarily on the basis of their X-ray-to-optical flu…
The relation between AGN hard X-ray emission and mid-infrared continuum from ISO spectra: Scatter and unification aspects
Lutz, D.; Maiolino, R.; Moorwood, A. F. M. +1 more
We use mid-infrared spectral decomposition to separate the 6 µm mid-infrared AGN continuum from the host emission in the ISO low resolution spectra of 71 active galaxies and compare the results to observed and intrinsic 2-10 keV hard X-ray fluxes from the literature. We find a correlation between mid-infrared luminosity and absorption correc…
The massive binary companion star to the progenitor of supernova 1993J
Smartt, Stephen J.; Kudritzki, Rolf P.; Podsiadlowski, Philipp +2 more
The massive star that underwent a collapse of its core to produce supernova (SN)1993J was subsequently identified as a non-variable red supergiant star in images of the galaxy M81 taken before explosion. It showed an excess in ultraviolet and B-band colours, suggesting either the presence of a hot, massive companion star or that it was embedded in…
The Hubble Higher z Supernova Search: Supernovae to z ~ 1.6 and Constraints on Type Ia Progenitor Models
Dickinson, Mark; Giavalisco, Mauro; Ravindranath, Swara +33 more
We present results from the Hubble Higher z Supernova Search, the first space-based open field survey for supernovae (SNe). In cooperation with the Great Observatories Origins Deep Survey, we have used the Hubble Space Telescope with the Advanced Camera for Surveys to cover ~300 arcmin2 in the area of the Chandra Deep Field South and th…
The star formation rate of the Universe at z~ 6 from the Hubble Ultra-Deep Field
Bunker, Andrew J.; McMahon, Richard G.; Ellis, Richard S. +1 more
We determine the abundance of i'-band dropouts in the recently released HST/ACS Hubble Ultra-Deep Field (UDF). Because the majority of these sources are likely to be z~ 6 galaxies whose flux decrement between the F775W i'-band and F850LP z'-band arises from Lyman-α absorption, the number of detected candidates provides a valuable upper limit to th…
The ACS Virgo Cluster Survey. I. Introduction to the Survey
Jordán, Andrés; Tonry, John L.; Côté, Patrick +7 more
The Virgo Cluster is the dominant mass concentration in the Local Supercluster and the largest collection of elliptical and lenticular galaxies in the nearby universe. In this paper, we present an introduction to the ACS Virgo Cluster Survey: a program to image, in the F475W and F850LP bandpasses (~Sloan g and z), 100 early-type galaxies in the Vi…
Nearby stars of the Galactic disk and halo. III.
Fuhrmann, K.
High-resolution spectroscopic observations of about 150 nearby stars or star systems are presented and discussed. The study of these and another 100 objects of the previous papers of this series implies that the Galaxy became reality 13 or 14 Gyr ago with the implementation of a massive, rotationally-supported population of thick-disk stars. The v…