The Luminosity Function for L>L* Galaxies at z > 3

Through use of multiband (U, B, R, I) photometry we have isolated high redshift (3.0<z<3.5) galaxy candidates in a survey of 1.27 deg^2 to R = 21.25 and a survey of 0.02 deg^2 to R = 23.5. Our pool of candidates constrains the nature of the 3.0 < z < 3.5 luminosity function over the range L* < L < 100 L*, if we grant a similar level of completeness to these data as for very faint samples (to R = 25.5) selected in a similar fashion. Our constraints agree with the high redshift sky density at R = 20.5 estimated from Yee et al.'s (1996) serendipitous discovery of a bright, z = 2.7 galaxy, as well as the density at R ~ 23 by Steidel et al. (1996b). We strongly rule out -- by more than two orders of magnitude at M(R) = -25 -- the L > L* luminosity function for z = 3-5 galaxies obtained by a photometric redshift analysis of the Hubble Deep Field (HDF) by Gwyn & Hartwick (1996). Our results at R ~ 23 are more consistent with the photometric redshift analysis of the faint HDF galaxies by Sawicki & Yee (1996), but our present upper limits at the brightest magnitudes (R < 21.5, M(R) < -24) allow more generous volume densities of these super-L* galaxies.Comment: Accepted for publication in ApJ Letters; 14 pages Latex, including 3 figure

Survey incompleteness and the evolution of the QSO luminosity function

We concentrate on a type of QSO survey which depends on selecting QSO candidates based on combinations of colors. Since QSO's have emission lines and power-law continua, they are expected to yield broadband colors unlike those of stellar photospheres. Previously, the fraction of QSO's expected to be hiding (unselected) within the locus of stellar (U-J, J-F) colors was estimated at about 15 percent. We have now verified that the KK88 survey is at least 11 percent incomplete, but have determined that it may be as much as 34 percent incomplete. The 'missing' QSO's are expected to be predominantly at z less than or = 2.2. We have studied the proper motion and variability properties of all stellar objects with J less than or = 22.5 or F less than or = 21.5 in the SA 57 field which has previously been surveyed with a multicolor QSO search by KK88

A Comparison of Nonverbal and Paraverbal Behaviors in Simulated and Virtual Patient Encounters

The present study assessed whether trainees display similar nonverbal and paraverbal behaviors when interacting with a simulated (SP) and virtual patient (VP). Sixty second slices of time following four interactions were rated for the presence and frequency of three nonverbal and paraverbal behaviors. Results revealed that students exhibited fewer behaviors in the VP interaction, possibly due to differences social inhibition or fidelity between the two formats

The dark energy spectrometer - A potential multi-fiber instrument for the Blanco 4-meter telescope

We describe the preliminary design of the Dark Energy Spectrometer (DESpec), a fiber-fed spectroscopic instrument concept for the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory (CTIO). DESpec would take advantage of the infrastructure recently deployed for the Dark Energy Camera (DECam). DESpec would be mounted in the new DECam prime focus cage, would be interchangeable with DECam, would share the DECam optical corrector, and would feature a focal plane with ∼4000 robotically positioned optical fibers feeding multiple high-throughput spectrometers. The instrument would have a field of view of 3.8 square degrees, a wavelength range of approximately 500<λ<1000 nm, and a spectral resolution of R∼3000. DESpec would provide a powerful spectroscopic follow-up system for sources in the Southern hemisphere discovered by the Dark Energy Survey and LSST

X-Rays from NGC 3256: High-Energy Emission in Starburst Galaxies and Their Contribution to the Cosmic X-Ray Background

The infrared-luminous galaxy NGC3256 is a classic example of a merger induced nuclear starburst system. We find here that it is the most X-ray luminous star-forming galaxy yet detected (~10^42 ergs/s). Long-slit optical spectroscopy and a deep, high-resolution ROSAT X-ray image show that the starburst is driving a "superwind" which accounts for ~20% of the observed soft (kT~0.3 keV) X-ray emission. Our model for the broadband X-ray emission of NGC3256 contains two additional components: a warm thermal plasma (kT~0.8 keV) associated with the central starburst, and a hard power-law component with an energy index of ~0.7. We find that the input of mechanical energy from the starburst is more than sufficient to sustain the observed level of emission. We also examine possible origins for the power-law component, concluding that neither a buried AGN nor the expected population of high-mass X-ray binaries can account for this emission. Inverse-Compton scattering, involving the galaxy's copious flux of infrared photons and the relativistic electrons produced by supernovae, is likely to make a substantial contribution to the hard X-ray flux. Such a model is consistent with the observed radio and IR fluxes and the radio and X-ray spectral indices. We explore the role of X-ray-luminous starbursts in the production of the cosmic X-ray background radiation. The number counts and spectral index distribution of the faint radio source population, thought to be dominated by star-forming galaxies, suggest that a significant fraction of the hard X-ray background could arise from starbursts at moderate redshift.Comment: 31 pages (tex, epsf), 8 figures (postscript files), accepted for publication in Part 1 of The Astrophysical Journa

Near-Infrared Galaxy Counts to J and K ~ 24 as a Function of Image Size

We have used the Keck 10m telescope to count objects as a function of image size in 2 high galactic latitude fields covering 1.5 arcmin^2 and reaching 50% completeness at K=24 and J=24.5 for stellar sources. Counts extend ~1 mag deeper in K than surveys with other telescopes; complement Keck surveys providing counts at comparable or shallower depths but not utilizing image structure; and extend by several magnitudes the J band counts from other surveys. We find the surface-density of objects at K=23 to be higher than previously found (~500,000/mag/deg^2), but at K<22 to be consistent with most other surveys in amplitude and slope (~0.36). J band counts have similar slope. J and K counts are in excess of our empirical no-evolution models for an open universe, and a factor of 2 higher than mild-evolution models at J and K ~ 23. The slope of the model counts is insensitive to geometry even in the near-infrared because the counts are dominated by low-luminosity (<0.1L*) objects at modest redshift (z<1) with small apparent sizes (r05<0.4", i.e. <4 kpc). The observed counts rise most steeply for these smaller objects, which dominate fainter than K=22.3 and J=23.3. However, the greatest excess relative to no-evolution models occurs for the apparently larger objects (median J-K~1.5). The size and colors of such objects correspond equally well to luminous (>0.1L*), galaxies at 1<z<4, or progressively more diffuse, low-luminosity (0.001-0.1L*) galaxies at z<1. We rule out the excess is from very low luminosity (<0.0001L*) red galaxies at z<0.25. There is a deficit of galaxies with red J-K colors corresponding to luminous, early-type galaxies at 1<z<3. Assuming the deficit is due to their appearance as blue galaxies, they account only for 10-30% of the excess of large, blue galaxies. [abridged]Comment: accepted for publication in ApJ; 34 pages text, 9 tables, 10 figures (embedded); full resolution figures available at http://www.astro.wisc.edu/~mab/publications/pub.htm

The Eighth Data Release of the Sloan Digital Sky Survey: First Data from SDSS-III

The Sloan Digital Sky Survey (SDSS) started a new phase in August 2008, with new instrumentation and new surveys focused on Galactic structure and chemical evolution, measurements of the baryon oscillation feature in the clustering of galaxies and the quasar Ly alpha forest, and a radial velocity search for planets around ~8000 stars. This paper describes the first data release of SDSS-III (and the eighth counting from the beginning of the SDSS). The release includes five-band imaging of roughly 5200 deg^2 in the Southern Galactic Cap, bringing the total footprint of the SDSS imaging to 14,555 deg^2, or over a third of the Celestial Sphere. All the imaging data have been reprocessed with an improved sky-subtraction algorithm and a final, self-consistent photometric recalibration and flat-field determination. This release also includes all data from the second phase of the Sloan Extension for Galactic Understanding and Evolution (SEGUE-2), consisting of spectroscopy of approximately 118,000 stars at both high and low Galactic latitudes. All the more than half a million stellar spectra obtained with the SDSS spectrograph have been reprocessed through an improved stellar parameters pipeline, which has better determination of metallicity for high metallicity stars.Comment: Astrophysical Journal Supplements, in press (minor updates from submitted version

Erratum: “The eighth data release of the Sloan Digital Sky Survey: first data from SDSS-III” (2011, ApJS, 193, 29)

Section 3.5 of Aihara et al. (2011) described various sources of systematic error in the astrometry of the imaging data of the Sloan Digital Sky Survey (SDSS). In addition to these sources of error, there is an additional and more serious error, which introduces a large systematic shift in the astrometry over a large area around the north celestial pole. The region has irregular boundaries but in places extends as far south as declination δ ≈ 41◦. The sense of the shift is that the positions of all sources in the affected area are offset by roughly 250 mas in a northwest direction. We have updated the SDSS online documentation to reflect these errors, and to provide detailed quality information for each SDSS field