Search Publications
Massive Dark Matter Halos and Evolution of Early-Type Galaxies to z ~ 1
Treu, Tommaso; Koopmans, Léon V. E.
The combination of gravitational lensing and stellar dynamics breaks the mass-anisotropy degeneracy and provides stringent constraints on the distribution of luminous and dark matter in early-type (E/S0) galaxies out to z~1. We present new observations and models of three lens systems (CFRS 03.1077, HST 14176+5226, HST 15433+5352) and the combined…
The Size Evolution of High-Redshift Galaxies
Dickinson, Mark; Ferguson, Henry C.; Giavalisco, Mauro +14 more
Hubble Space Telescope images of high-redshift galaxies selected via color and photometric redshifts are used to examine the size and axial ratio distribution of galaxies as a function of redshift at look-back times t>8 Gyr. These parameters are measured at rest-frame UV wavelengths (1200 Å < λ < 2000 Å) on images with a rest-frame resolu…
The Helium Abundances of ω Centauri
Norris, John E.
Recent Hubble Space Telescope color magnitude diagrams (CMDs) of ω Centauri, which clearly show three sequences in the region of the main-sequence turnoff together with a double lower main sequence, are explained in terms of three populations having canonical heavy-element abundances ([Fe/H]=-1.7, -1.2, and -0.6), reasonable proportions and ages, …
Torsional Oscillation, Meridional Flows, and Vorticity Inferred in the Upper Convection Zone of the Sun by Time-Distance Helioseismology
Zhao, Junwei; Kosovichev, Alexander G.
By applying time-distance helioseismology measurements and inversions to Solar and Heliospheric Observatory (SOHO) Michelson Doppler Imager (MDI) dynamics campaign data, we obtain synoptic maps of subsurface plasma-flow fields at a depth of 0-12 Mm for seven solar Carrington rotations, covering the years 1996-2002, from solar-activity minimum to m…
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 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…
Cosmic Variance in the Great Observatories Origins Deep Survey
Ferguson, Henry C.; Giavalisco, Mauro; Somerville, Rachel S. +3 more
Cosmic variance is the uncertainty in observational estimates of the volume density of extragalactic objects such as galaxies or quasars arising from the underlying large-scale density fluctuations. This is often a significant source of uncertainty, especially in deep galaxy surveys, which tend to cover relatively small areas. We present estimates…
Coronal Magnetic Field Measurements
Lin, H.; Kuhn, J. R.; Coulter, R.
A long-standing solar problem has been to measure the coronal magnetic field. We believe it determines the coronal structure and dynamics from the upper chromosphere out into the heliospheric environment. It is only recently that Zeeman splitting observations of infrared coronal emission lines have been successfully used to deduce the coronal magn…
The Dark Matter Distribution in the Central Regions of Galaxy Clusters: Implications for Cold Dark Matter
Smith, Graham P.; Treu, Tommaso; Ellis, Richard S. +1 more
We have undertaken a spectroscopic survey of gravitational arcs in a carefully chosen sample of six clusters, each containing a dominant brightest cluster galaxy. We use these systems to study the relative distributions of dark and baryonic material in the central regions. Three clusters present both radial and tangential arcs and provide particul…
The Rest-Frame Optical Spectra of SCUBA Galaxies
Ivison, R. J.; Smail, Ian; Swinbank, A. M. +3 more
We present near-infrared spectroscopy and narrowband imaging at the wavelength of redshifted Hα for a sample of 30 high-redshift, far-infrared luminous galaxies. This sample is selected from surveys in the submillimeter, millimeter, and radio wave bands and has complete redshift coverage with a median redshift of z~2.4. We use our data to measure …