z~1 Lya Emitters I. The Luminosity Function

We construct a flux-limited sample of 135 candidate z~1 Lya emitters (LAEs) from Galaxy Evolution Explorer (GALEX) grism data using a new data cube search method. These LAEs have luminosities comparable to those at high redshifts and lie within a 7 Gyr gap present in existing LAE samples. We use archival and newly obtained optical spectra to verify the UV redshifts of these LAEs. We use the combination of the GALEX UV spectra, optical spectra, and X-ray imaging data to estimate the active galactic nucleus (AGN) fraction and its dependence on Lya luminosity. We remove the AGNs and compute the luminosity function (LF) from 60 z~1 LAE galaxies. We find that the best fit LF implies a luminosity density increase by a factor of ~1.5 from z~0.3 to z~1 and ~20 from z~1 to z~2. We find a z~1 volumetric Lya escape fraction of 0.7+/-0.4%.

SMA observations on faint Submillimeter Galaxies with S$_{850}$ < 2 mJy: Ultra Dusty Low-Luminosity Galaxies at High Redshift

We obtained SMA observations of eight faint (intrinsic 850 $mu$m fluxes $<$ 2 mJy) submillimeter galaxies (SMGs) discovered in SCUBA images of the massive lensing cluster fields A370, A2390, and A1689 and detected five. In total, we obtain 5 SMA detections, all of which have de-lensed fluxes $<$1 mJy with estimated total infrared luminosities 10$^{10}-10^{12}$ $L_odot$, comparable to luminous infrared galaxies (LIRGs) and normal star-forming galaxies. Based on the latest number counts, these galaxies contribute $sim$70% of the 850 $mu$m extragalactic background light and represent the dominant star-forming galaxy population in the dusty universe. However, only 40$^{+30}_{-16}$% of our faint SMGs would be detected in deep optical or near-infrared surveys, which suggests many of these sources are at high redshifts ($z gtrsim 3$) or extremely dusty, and they are not included in current star formation history estimates.

Resolving the Cosmic Far-Infrared Background at 450 and 850 Microns with SCUBA-2

We use the SCUBA-2 submillimeter camera mounted on the JCMT to obtain extremely deep number counts at 450 and 850um. We combine data on two cluster lensing fields, A1689 and A370, and three blank fields, CDF-N, CDF-S, and COSMOS, to measure the counts over a wide flux range at each wavelength. We use statistical fits to broken power law representations to determine the number counts. This allows us to probe to the deepest possible level in the data. At both wavelengths our results agree well with the literature in the flux range over which they have been measured, with the exception of the 850um counts in CDF-S, where we do not observe the counts deficit found by previous single-dish observations. At 450um, we detect significant counts down to ~1mJy, an unprecedented depth at this wavelength. By integrating the number counts above this flux limit, we measure 113.9^{+49.7}_{-28.4} Jydeg^{-2} of the 450um extragalactic background light (EBL). The majority of this contribution is from sources with S_450um between 1-10mJy, and these sources are likely to be the ones that are analogous to the local luminous infrared galaxies (LIRGs). At 850um, we measure 37.3^{+21.1}_{-12.9} Jydeg^{-2} of the EBL. Because of the large systematic uncertainties on the COBE measurements, the percentage of the EBL we resolve could range from 48%-153% (44%-178%) at 450 (850)um. Based on high-resolution SMA observations of around half of the 4sigma 850um sample in CDF-N, we find that 12.5^{+12.1}_{-6.8}% of the sources are blends of multiple fainter sources. This is a low multiple fraction, and we find no significant difference between our original SCUBA-2 850um counts and the multiplicity corrected counts.

Ultradeep Ks Imaging in the GOODS-N

We present an ultradeep Ks-band image that covers 0.5*0.5 deg^2 centered on the Great Observatories Origins Deep Survey-North (GOODS-N). The image reaches a 5 sigma depth of Ks(AB) = 24.45 in the GOODS-N region, which is as deep as the GOODS-N Spitzer Infrared Array Camera (IRAC) 3.6 mu m image. We present a new method of constructing IRAC catalogs that uses the higher spatial resolution Ks image and catalog as priors and iteratively subtracts fluxes from the IRAC images to estimate the IRAC fluxes. Our iterative method is different from the chi^2 approach adopted by other groups. We verified our results using data taken in two different epochs of observations, as well as by comparing our colors with the colors of stars and with the colors derived from model spectral energy distributions (SEDs) of galaxies at various redshifts. We make available to the community our WIRCam Ks-band image and catalog (94951 objects in 0.25 deg^2), the Interactive Data Language (IDL) pipeline used for reducing the WIRCam images, and our IRAC 3.6 to 8.0 mu m catalog (16950 objects in 0.06 deg^2 at 3.6 mu m). With this improved Ks and IRAC catalog and a large spectroscopic sample from our previous work, we study the color-magnitude and color-color diagrams of galaxies. We compare the effectiveness of using Ks and IRAC colors to select active galactic nuclei (AGNs) and galaxies at various redshifts. We also study a color selection of z = 0.65--1.2 galaxies using the Ks, 3.6 mu m, and 4.5 mu m bands.

GOODS 850-5 -- A z>4 Galaxy Discovered in the Submillimeter?

We report an SMA interferometric identification of a bright submillimeter source, GOODS 850-5. This source is one of the brightest 850 um sources in the GOODS-N but is extremely faint at all other wavelengths. It is not detected in the GOODS HST ACS images and only shows a weak 2 sigma signal at 1.4 GHz. It is detected in the Spitzer IRAC bands and the MIPS 24 um band, however, with very low fluxes. We present evidence in the radio, submillimeter, mid-IR, near-IR, and optical that suggest GOODS 850-5 may be a z>4 galaxy.