Resolving the Radio Source Background: Deeper Understanding Through Confusion

We used the Karl G. Jansky Very Large Array (VLA) to image one primary beam area at 3 GHz with 8 arcsec FWHM resolution and 1.0 microJy/beam rms noise near the pointing center. The P(D) distribution from the central 10 arcmin of this confusion-limited image constrains the count of discrete sources in the 1 < S(microJy/beam) < 10 range. At this level the brightness-weighted differential count S^2 n(S) is converging rapidly, as predicted by evolutionary models in which the faintest radio sources are star-forming galaxies; and ~96$% of the background originating in galaxies has been resolved into discrete sources. About 63% of the radio background is produced by AGNs, and the remaining 37% comes from star-forming galaxies that obey the far-infrared (FIR) / radio correlation and account for most of the FIR background at lambda = 160 microns. Our new data confirm that radio sources powered by AGNs and star formation evolve at about the same rate, a result consistent with AGN feedback and the rough correlation of black hole and bulge stellar masses. The confusion at centimeter wavelengths is low enough that neither the planned SKA nor its pathfinder ASKAP EMU survey should be confusion limited, and the ultimate source detection limit imposed by "natural" confusion is < 0.01 microJy at 1.4 GHz. If discrete sources dominate the bright extragalactic background reported by ARCADE2 at 3.3 GHz, they cannot be located in or near galaxies and most are < 0.03 microJy at 1.4 GHz.Comment: 28 pages including 16 figures. ApJ accepted for publicatio

SINFONI's take on Star Formation, Molecular Gas, and Black Hole Masses in AGN

We present some preliminary (half-way) results on our adaptive optics spectroscopic survey of AGN at spatial scales down to 0.085arcsec. Most of the data were obtained with SINFONI which provides integral field capability at a spectral resolution of R~4000. The themes on which we focus in this contribution are: star formation around the AGN, the properties of the molecular gas and its relation to the torus, and the mass of the black hole.Comment: 5 pages, 2 figures. To appear in Science Perspectives for 3D Spectroscopy. ESO Astrophysics Symposia. Ed by M. Kissler-Patig, M. Roth and J. Wals

RBSC-NVSS Sample. I. Radio and Optical Identifications of a Complete Sample of 1500 Bright X-ray Sources

We cross-identified the ROSAT Bright Source Catalog (RBSC) and the NRAO VLA Sky Survey (NVSS) to construct the RBSC-NVSS sample of the brightest X-ray sources (>= 0.1 counts/s or ~1E-12 ergs/cm/cm/s in the 0.1-2.4 keV band) that are also radio sources (S >= 2.5 mJy at 1.4 GHz) in the 7.8 sr of extragalactic sky with |b| > 15 degrees. and delta > -40 degrees. The sky density of NVSS sources is low enough that they can be reliably identified with RBSC sources having average rms positional uncertainties = 10 arcsec. We used the more accurate radio positions to make reliable X-ray/radio/optical identifications down to the POSS plate limits. We obtained optical spectra for many of the bright identifications lacking published redshifts. The resulting X-ray/radio sample is unique in its size (N ~ 1500 objects), composition (a mixture of nearly normal galaxies, Seyfert galaxies, quasars, and clusters), and low average redshift ( ~ 0.1).Comment: 35 LaTeX pages including 6 eps figures + 40 LaTeX page table2 (landscape) w/ AASTeX 5.0; accepted to ApJ

Radio continuum and far-infrared emission from the galaxies in the Eridanus group

The Eridanus galaxies follow the well-known radio-FIR correlation. Majority (70%) of these galaxies have their star formation rates below that of the Milky Way. The galaxies having a significant excess of radio emission are identified as low luminosity AGNs based on their radio morphologies obtained from the GMRT observations. There are no powerful AGNs (L{20cm} > 10^{23} W Hz^{-1}) in the group. The two most far-infrared and radio luminous galaxies in the group have optical and HI morphologies suggestive of recent tidal interactions. The Eridanus group also has two far-infrared luminous but radio-deficient galaxies. It is believed that these galaxies are observed within a few Myr of the onset of an intense star formation episode after being quiescent for at least a 100 Myr. The upper end of the radio luminosity distribution of the Eridanus galaxies (L_{20cm} ~ 10^{22} W Hz^{-1}) is consistent with that of the field galaxies, other groups, and late-type galaxies in nearby clusters.Comment: 16 pages; Accepted for publication in Journal of Astroph. & Astron. March, 200

The MPCP Longitudinal Educational Growth Study Third Year Report

This is the third-year report in a five-year evaluation of the Milwaukee Parental Choice Program (MPCP). The MPCP, which began in 1990, provides government-funded vouchers for low-income children to attend private schools in the City of Milwaukee. The maximum voucher amount in 2008-09 was $6,607, and approximately 20,000 children used a voucher to attend either secular or religious private schools. The MPCP is the oldest and largest urban school voucher program in the United States. This evaluation was authorized by Wisconsin Act 125 enacted in 2005

Massive Lyman Break Galaxies at z~3 in the Spitzer Extragalactic First Look Survey

We investigate the properties of 1088 Lyman Break Galaxies (LBGs) at z~3 selected from a ~2.63$deg2 sub-region of the First Look Survey field using the ground-based multi-color data and the Spitzer Space Telescope mid-infrared data at 3--8 and 24 um. With the wide area and the broad wavelength coverage, we sample a large number of ``rare'' u-band dropouts which are massive (M* > 10^11 Msun), allowing us to perform a statistical analysis of these subsets of LBGs that have not been studied in detail. Optically bright (R(AB) < 24.5 mag) LBGs detected in mid-infrared (S_{3.6um} > 6 uJy) reside at the most massive and dusty end of the LBG population, with relatively high and tight$M/L$ in rest-frame near-infrared. Most infrared-luminous LBGs (S_{24um} > 100 uJy) are dusty star-forming galaxies with star formation rates of 100--1000 Msun/yr, total infrared luminosity of > 10^12 Lsun. By constructing the UV luminosity function of massive LBGs, we estimate that the lower limit for the star formation rate density from LBGs more massive than 10^11 Msun at z~3 is > 3.3 x 10^-3 Msun/yr/Mpc^3, showing for the first time that the UV-bright population of massive galaxies alone contributes significantly to the global star formation rate density at z~3. When combined with the star formation rate densities at z < 2, our result reveals a steady increase in the contribution of massive galaxies to the global star formation from z=0 to z=3, providing strong support to the downsizing of galaxy formation.Comment: 15 pages, 13 figures. Accepted for publication in Ap