G. G. Fazio

The most luminous z ∼ 9-10 galaxy candidates yet found: The luminosity function, cosmic star-formation rate, and the first mass density estimate at 500 Myr

We present the discovery of four surprisingly bright (H160 � 26 27 mag AB) galaxy candidates at z � 9 10 in the complete HST CANDELS WFC3/IR GOODS-N imaging data, doubling the number of z � 10 galaxy candidates that are known, just �500 Myr after the Big Bang. Two similarly bright sources are also detected in a systematic re-analysis of the GOODS-S data set. Three of the four galaxies in GOODS-N are significantly detected at 4.5 6.2� in the very deep Spitzer/IRAC 4.5µm data, as is one of the GOODS-S candidates. Furthermore, the brightest of our candidates (at z = 10.2 ± 0.4) is robustly detected also at 3.6µm (6.9�), revealing a flat UV spectral energy distribution with a slope � = 2.0±0.2, consistent with demonstrated trends with luminosity at high redshift. The abundance of such luminous candidates suggests that the luminosity function evolves more significantly in �∗ than in L∗ at z & 8 with a higher number density of bright sources than previously expected. Despite the discovery of these luminous candidates, the cosmic star formation rate density for galaxies with SFR > 0.7 M⊙ yr −1 shows an order-of-magnitude increase in only 170 Myr from z � 10 to z � 8, consistent with previous results given the dominance of low-luminosity sources to the total SFR density. Based on the IRAC detections, we derive galaxy stellar masses at z � 10, finding that these luminous objects are typically 10 9 M⊙. This allows for a first estimate of the cosmic stellar mass density at z � 10 resulting in log10 �∗ = 4.7 +0.5 −0.8 M⊙ Mpc −3 for galaxies brighter than MUV � 18. The remarkable brightness, and hence luminosity, of these z � 9 10 candidates highlights the opportunity for deep spectroscopy to determine their redshift and nature, demonstrates the value of additional search fields covering a wider area to understand star-formation in the very early universe, and highlights the opportunities for JWST to map the buildup of galaxies at redshifts much earlier than z � 10. Subject headings: galaxies: evolution — galaxies: high-redshift — galaxies: luminosity function

THE SPITZER SPACE TELESCOPE SURVEY OF THE ORION A AND B MOLECULAR CLOUDS. I. A CENSUS OF DUSTY YOUNG STELLAR OBJECTS AND A STUDY OF THEIR MID-INFRARED VARIABILITY

We present a survey of the Orion A and B molecular clouds undertaken with the IRAC and MIPS instruments on board Spitzer. In total, five distinct fields were mapped, covering 9 deg^2 in five mid-IR bands spanning 3-24 μm. The survey includes the Orion Nebula Cluster, the Lynds 1641, 1630, and 1622 dark clouds, and the NGC 2023, 2024, 2068, and 2071 nebulae. These data are merged with the Two Micron All Sky Survey point source catalog to generate a catalog of eight-band photometry. We identify 3479 dusty young stellar objects (YSOs) in the Orion molecular clouds by searching for point sources with mid-IR colors indicative of reprocessed light from dusty disks or infalling envelopes. The YSOs are subsequently classified on the basis of their mid-IR colors and their spatial distributions are presented. We classify 2991 of the YSOs as pre-main-sequence stars with disks and 488 as likely protostars. Most of the sources were observed with IRAC in two to three epochs over six months; we search for variability between the epochs by looking for correlated variability in the 3.6 and 4.5 μm bands. We find that 50% of the dusty YSOs show variability. The variations are typically small (~0.2 mag) with the protostars showing a higher incidence of variability and larger variations. The observed correlations between the 3.6, 4.5, 5.8, and 8 μm variability suggests that we are observing variations in the heating of the inner disk due to changes in the accretion luminosity or rotating accretion hot spots.

SEDS: The Spitzer Extended Deep Survey: survey design, photometry, and deep IRAC source counts

The Spitzer Extended Deep Survey (SEDS) is a very deep infrared survey within five well-known extragalactic science fields: the UKIDSS Ultra-Deep Survey, the Extended Chandra Deep Field South, COSMOS, the Hubble Deep Field North, and the Extended Groth Strip. SEDS covers a total area of 1.46 deg(2) to a depth of 26 AB mag (3s) in both of the warm Infrared Array Camera (IRAC) bands at 3.6 and 4.5 mu m. Because of its uniform depth of coverage in so many widely-separated fields, SEDS is subject to roughly 25% smaller errors due to cosmic variance than a single-field survey of the same size. SEDS was designed to detect and characterize galaxies from intermediate to high redshifts (z = 2-7) with a built-in means of assessing the impact of cosmic variance on the individual fields. Because the full SEDS depth was accumulated in at least three separate visits to each field, typically with six- month intervals between visits, SEDS also furnishes an opportunity to assess the infrared variability of faint objects. This paper describes the SEDS survey design, processing, and publicly-available data products. Deep IRAC counts for the more than 300,000 galaxies detected by SEDS are consistent with models based on known galaxy populations. Discrete IRAC sources contribute 5.6 +/- 1.0 and 4.4 +/- 0.8 nW m(-2) sr(-1) at 3.6 and 4.5 mu m to the diffuse cosmic infrared background (CIB). IRAC sources cannot contribute more than half of the total CIB flux estimated from DIRBE data. Barring an unexpected error in the DIRBE flux estimates, half the CIB flux must therefore come from a diffuse component.

THE INFRARED ARRAY CAMERA (IRAC) SHALLOW SURVEY

The Infrared Array Camera (IRAC) shallow survey covers 8.5 deg2 in the NOAO Deep Wide-Field Survey in Bootes with three or more 30 s exposures per position. An overview of the survey design, reduction, calibration, star-galaxy separation, and initial results is provided. The survey includes ≈370,000, 280,000, 38,000, and 34,000 sources brighter than the 5 σ limits of 6.4, 8.8, 51, and 50 μJy at 3.6, 4.5, 5.8, and 8 μm, respectively, including some with unusual spectral energy distributions.

The galaxy stellar mass function at 3.5 ≤ z ≤ 7.5 in the CANDELS/UDS, GOODS-South, and HUDF fields

Context. The form and evolution of the galaxy stellar mass function (GSMF) at high redshifts provide crucial information on star formation history and mass assembly in the young Universe, close or even prior to the epoch of reionization. Aims. We used the unique combination of deep optical/near-infrared/mid-infrared imaging provided by HST, Spitzer, and the VLT in the CANDELS-UDS, GOODS-South, and HUDF fields to determine the GSMF over the redshift range 3.5 ≤ z ≤ 7.5. Methods. We used the HST WFC3/IR near-infrared imaging from CANDELS and HUDF09, reaching H ≃ 27 − 28.5 over a total area of 369 arcmin^2, in combination with associated deep HST ACS optical data, deep Spitzer IRAC imaging from the SEDS programme, and deep Y and K-band VLT Hawk-I images from the HUGS programme, to select a galaxy sample with high-quality photometric redshifts. These have been calibrated with more than 150 spectroscopic redshifts in the range 3.5 ≤ z ≤ 7.5, resulting in an overall precision of σ_z/ (1 + z) ~ 0.037. With this database we have determined the low-mass end of the high-redshift GSMF with unprecedented precision, reaching down to masses as low as M^∗ ~ 10^9 M_⊙ at z = 4 and ~6 × 10^9 M_⊙ at z = 7. Results. We find that the GSMF at 3.5 ≤ z ≤ 7.5 depends only slightly on the recipes adopted to measure the stellar masses, namely the photometric redshifts, the star formation histories, the nebular contribution, or the presence of AGN in the parent sample. The low-mass end of the GSMF is steeper than has been found at lower redshifts, but appears to be unchanged over the redshift range probed here. Meanwhile the high-mass end of the GSMF appears to evolve primarily in density, although there is also some evidence of evolution in characteristic mass. Our results are very different from previous mass function estimates based on converting UV galaxy luminosity functions into mass functions via tight mass-to-light relations. Integrating our evolving GSMF over mass, we find that the growth of stellar mass density is barely consistent with the time-integral of the star formation rate density over cosmic time at z> 4. Conclusions. These results confirm the unique synergy of the CANDELS+HUDF, HUGS, and SEDS surveys for the discovery and study of moderate/low-mass galaxies at high redshifts, and reaffirm the importance of space-based infrared selection for the unbiased measurement of the evolving GSMF in the young Universe.The galaxy stellar mass function (GSMF) at high-z provides key information on star-formation history and mass assembly in the young Universe. We aimed to use the unique combination of deep optical/NIR/MIR imaging provided by HST, Spitzer and the VLT in the CANDELS-UDS, GOODS-South, and HUDF fields to determine the GSMF over the redshift range 3.5 4. These results confirm the unique synergy of the CANDELS+HUDF, HUGS, and SEDS surveys for the discovery and study of moderate/low-mass galaxies at high redshifts.

XBOOTES: AN X-RAY SURVEY OF THE NDWFS BOOTES FIELD. II. THE X-RAY SOURCE CATALOG

We present results from a Chandra survey of the 9 deg 2 Bootes field of the NOAO Deep Wide-Field Survey (NDWFS). This XBootes survey consists of 126 separate contiguous ACIS-I observations each of approximately 5000 s in duration. These unique Chandra observations allow us to search for large-scale structure and to calculate X-raysource statistics overawide,contiguousfieldofviewwitharcsecondangularresolutionanduniformcoverage. Opticalspectroscopicfollow-upobservationsandtherichNDWFSdatasetwillallowustoidentifyandclassifythese X-ray‐selected sources. Using wavelet decomposition, we detect 4642 point sources with n � 2 counts. In order to keep our detections � 99% reliable, we limit our list to sources with n � 4 counts. For a 5000 s observation and assuming a canonical unabsorbed active galactic nucleus (AGN) type X-ray spectrum, a 4 count on-axis source correspondsto afluxof4:7 ;10 � 15 ergscm � 2 s � 1 inthe soft (0.5‐2keV) band, 1:5 ; 10 � 14 ergscm � 2 s � 1 in thehard (2‐7 keV) band, and 7:8 ; 10 � 15 ergs cm � 2 s � 1 in the full (0.5‐7 keV) band. The full 0.5‐7 keV band n � 4 count list has 3293 point sources. In addition to the point sources, 43 extended sources have been detected, consistent with the depth of these observations and the number counts of clusters. We present here the X-ray catalog for the XBootes survey, including source positions, X-ray fluxes, hardness ratios, and their uncertainties. We calculate and present the differential number of sources per flux density interval, N(S), for the point sources. In the soft (0.5‐2 keV) band, N(S) is well fitted by a broken power law with slope of 2:60 þ0:11 � 0:12 at bright fluxes and 1:74 þ0:28 � 0:22 for faint fluxes. The hard source N(S) is well described by a single power law with an index of � 2:93 þ0:09 � 0:09.

SPT-CL J0546-5345: A Massive z > 1 Galaxy Cluster Selected Via the Sunyaev-Zel'dovich Effect with the South Pole Telescope

United States. National Aeronautics and Space Administration (Jet Propulsion Laboratory (U.S.))

A REMARKABLY LUMINOUS GALAXY at Z =11.1 MEASURED with HUBBLE SPACE TELESCOPE GRISM SPECTROSCOPY

We present Hubble WFC3/IR slitless grism spectra of a remarkably bright

Infrared Spectrograph Spectroscopy and Multi-Wavelength Study of Luminous Star-Forming Galaxies at z ≃ 1.9

z\gtrsim10

[C II] AND 12CO(1-0) EMISSION MAPS IN HLSJ091828.6+514223: A STRONGLY LENSED INTERACTING SYSTEM AT z = 5.24

galaxy candidate, GN-z11, identified initially from CANDELS/GOODS-N imaging data. A significant spectroscopic continuum break is detected at