Search Publications
Discovery of a Ringlike Dark Matter Structure in the Core of the Galaxy Cluster Cl 0024+17
Ford, H. C.; Demarco, R.; van der Wel, A. +13 more
We present a comprehensive mass reconstruction of the rich galaxy cluster Cl 0024+17 at z~=0.4 from ACS data, unifying both strong- and weak-lensing constraints. The weak-lensing signal from a dense distribution of background galaxies (~120 arcmin-2) across the cluster enables the derivation of a high-resolution parameter-free mass map.…
Suzaku Observations of Active Galactic Nuclei Detected in the Swift BAT Survey: Discovery of a ``New Type'' of Buried Supermassive Black Holes
Ueda, Yoshihiro; Terashima, Yuichi; Mushotzky, Richard +6 more
We present the Suzaku broadband observations of two AGNs detected by the Swift BAT hard X-ray (>15 keV) survey that did not have previous X-ray data, SWIFT J0601.9-8636 and SWIFT J0138.6-4001. The Suzaku spectra reveal in both objects a heavily absorbed power-law component with a column density of NH~=1023.5-1024
New Constraints on the Lyman Continuum Escape Fraction at z~1.3
Dickinson, Mark; Ferguson, Henry C.; Giavalisco, Mauro +8 more
We examine deep far-UV (1600 Å) imaging of the HDF-N and the HUDF to search for leaking Lyman continuum radiation from starburst galaxies at z~1.3. There are 21 (primarily sub-L*) galaxies with spectroscopic redshifts between 1.1<z<1.5, and none are detected in the far-UV. We fit stellar population templates to the galaxies' optic…
A Keck Survey for Gravitationally Lensed Lyα Emitters in the Redshift Range 8.5<z<10.4: New Constraints on the Contribution of Low-Luminosity Sources to Cosmic Reionization
Richard, Johan; Smith, Graham P.; Stark, Daniel P. +3 more
We discuss new observational constraints on the abundance of faint high-redshift Lyα emitters secured from a deep Keck near-infrared spectroscopic survey that utilizes the strong magnification provided by lensing galaxy clusters. In each of nine clusters, we have undertaken a systematic ``blind'' search for line emission with NIRSPEC in the J band…
Iron Line and Diffuse Hard X-Ray Emission from the Starburst Galaxy M82
Heckman, Timothy M.; Strickland, David K.
We examine the properties of the diffuse hard X-ray emission in the classic starburst galaxy M82. We use new Chandra ACIS-S observations in combination with reprocessed archival Chandra ACIS-I and XMM-Newton observations. We find that E~6.7 keV Fe Heα emission is present in the central |r|<200 pc, |z|<100 pc of M82 in all data sets, in addit…
X-Ray Thermal Coronae of Galaxies in Hot Clusters: Ubiquity of Embedded Mini-Cooling Cores
Vikhlinin, A.; Forman, W.; Sun, M. +3 more
We present a systematic investigation of X-ray thermal coronae in 157 early-type and 22 late-type galaxies from a survey of 25 hot (kT>3 keV), nearby (z<0.05) clusters, based on Chandra archival data. Cool galactic coronae (kT=0.5-1.1 keV generally) have been found to be common, >60% in LKs>2L* galaxies…
Molecular Hydrogen Emission from Protoplanetary Disks. II. Effects of X-Ray Irradiation and Dust Evolution
Tsujimoto, M.; Nomura, H.; Aikawa, Y. +2 more
Detailed models for the density and temperature profiles of gas and dust in protoplanetary disks are constructed by taking into account X-ray and UV irradiation from a central T Tauri star, as well as dust size growth and settling toward the disk midplane. The spatial and size distributions of dust grains are numerically computed by solving the co…
Cosmic Evolution of Black Holes and Spheroids. II. Scaling Relations at z=0.36
Treu, Tommaso; Malkan, Matthew A.; Blandford, Roger D. +1 more
We use high-resolution images obtained with the Advanced Camera for Surveys on board the Hubble Space Telescope to determine morphology, nuclear luminosity, and structural parameters of the spheroidal component for a sample of 20 Seyfert galaxies at z=0.36. We combine these measurements with spectroscopic information from the Keck Telescope to det…
Quantitative Forecasting of Major Solar Flares
Rust, David M.; Georgoulis, Manolis K.
We define the effective connected magnetic field, Beff, a single metric of the flaring potential in solar active regions. We calculated Beff for 298 active regions (93 X- and M-flaring, 205 nonflaring) as recorded by SOHO/MDI during a 10 yr period covering much of solar cycle 23. We find that Beff is a robust crite…
Optical-to-Mid-Infrared Observations of Lyα Galaxies at z~5 in the Hubble Ultra Deep Field: A Young and Low-Mass Population
Malhotra, S.; Rhoads, J. E.; Xu, C. +1 more
High-redshift galaxies selected on the basis of strong Lyα emission tend to be young and have small physical sizes. We show this by analyzing the spectral energy distribution of nine Lyα-emitting galaxies (LAEs) at 4.0<z<5.7 in the Hubble Ultra Deep Field. Rest-frame UV-to-optical (700 Å < λ < 7500 Å) luminosities, or upper limits, are…