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- ID:
- ivo://CDS.VizieR/J/ApJ/543/552
- Title:
- z>3 damped Ly{alpha} absorption systems
- Short Name:
- J/ApJ/543/552
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have completed spectroscopic observations using LRIS on the Keck 1 telescope of 30 very high redshift quasars, 11 selected for the presence of damped Ly{alpha} absorption systems and 19 with redshifts z>3.5 not previously surveyed for absorption systems. We have surveyed an additional 10 QSOs with the Lick 120" and the Anglo-Australian Telescope. We have combined these with previous data, resulting in a statistical sample of 646 QSOs and 85 damped Ly{alpha} absorbers with column densities N_HI_>=2 10^20^atoms/cm^2^ covering the redshift range 0.008<=z<=4.694. Four main features of how the neutral gas in the universe evolves with redshift are evident from these data.
1573. ZFIRE v1.0 data release
- ID:
- ivo://CDS.VizieR/J/ApJ/828/21
- Title:
- ZFIRE v1.0 data release
- Short Name:
- J/ApJ/828/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an overview and the first data release of ZFIRE, a spectroscopic redshift survey of star-forming galaxies that utilizes the MOSFIRE instrument on Keck-I to study galaxy properties in rich environments at 1.5<z<2.5. ZFIRE measures accurate spectroscopic redshifts and basic galaxy properties derived from multiple emission lines. The galaxies are selected from a stellar mass limited sample based on deep near infrared imaging (K_AB_<25) and precise photometric redshifts from the ZFOURGE and UKIDSS surveys as well as grism redshifts from 3DHST. Between 2013 and 2015, ZFIRE has observed the COSMOS and UDS legacy fields over 13 nights and has obtained 211 galaxy redshifts over 1.57<z<2.66 from a combination of nebular emission lines (such as H{alpha}, [NII], H{beta}, [OII], [OIII], and [SII]) observed at 1-2{mu}m. Based on our medium-band near infrared photometry, we are able to spectrophotometrically flux calibrate our spectra to ~10% accuracy. ZFIRE reaches 5{sigma} emission line flux limits of ~3x10^-18^erg/s/cm^2^ with a resolving power of R=3500 and reaches masses down to ~10^9^M_{sun}_. We confirm that the primary input survey, ZFOURGE, has produced photometric redshifts for star-forming galaxies (including highly attenuated ones) accurate to {Delta}z/(1+z_spec_)=0.015 with 0.7% outliers. We measure a slight redshift bias of <0.001, and we note that the redshift bias tends to be larger at higher masses. We also examine the role of redshift on the derivation of rest-frame colors and stellar population parameters from SED fitting techniques. The ZFIRE survey extends spectroscopically confirmed z~2 samples across a richer range of environments, here we make available the first public release of the data for use by the community.
- ID:
- ivo://CDS.VizieR/J/ApJ/897/44
- Title:
- 120 3<=z<=5 galaxies candidates in CANDELS fields
- Short Name:
- J/ApJ/897/44
- Date:
- 11 Mar 2022
- Publisher:
- CDS
- Description:
- Using the CANDELS photometric catalogs for the Hubble Space Telescope ACS and WFC3, we identified massive evolved galaxies at 3<z<4.5 employing three different selection methods. We find the comoving number density of these objects to be ~2x10^-5^ and 8x10^-6^/Mpc^3^ after correction for completeness for two redshift bins centered at z=3.4, 4.7. We quantify a measure of how much confidence we should have for each candidate galaxy from different selections and what the conservative error estimates propagated into our selection are. Then we compare the evolution of the corresponding number densities and their stellar mass density with numerical simulations, semianalytical models, and previous observational estimates, which shows slight tension at higher redshifts as the models tend to underestimate the number and mass densities. By estimating the average halo masses of the candidates (M_h_~4.2, 1.9, and 1.3x1012M{sun} for redshift bins centered at z=3.4, 4.1, and 4.7), we find them to be consistent with halos that were efficient in turning baryons to stars, relatively immune to the feedback effects, and on the verge of transition into hot-mode accretion. This can suggest the relative cosmological starvation of the cold gas followed by an overconsumption phase in which the galaxy rapidly consumes the available cold gas as one of the possible drivers for the quenching of the massive evolved population at high redshift.
- ID:
- ivo://CDS.VizieR/J/ApJ/803/34
- Title:
- z~4-10 galaxies from HST legacy fields
- Short Name:
- J/ApJ/803/34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The remarkable Hubble Space Telescope (HST) data sets from the CANDELS, HUDF09, HUDF12, ERS, and BoRG/HIPPIES programs have allowed us to map the evolution of the rest-frame UV luminosity function (LF) from z~10 to z~4. We develop new color criteria that more optimally utilize the full wavelength coverage from the optical, near-IR, and mid-IR observations over our search fields, while simultaneously minimizing the incompleteness and eliminating redshift gaps. We have identified 5859, 3001, 857, 481, 217, and 6 galaxy candidates at z~4, z~5, z~6, z~7, z~8, and z~10, respectively, from the ~1000arcmin^2^ area covered by these data sets. This sample of >10000 galaxy candidates at z>=4 is by far the largest assembled to date with HST. The selection of z~4-8 candidates over the five CANDELS fields allows us to assess the cosmic variance; the largest variations are at z>=7. Our new LF determinations at z~4 and z~5 span a 6 mag baseline and reach to -16 AB mag. These determinations agree well with previous estimates, but the larger samples and volumes probed here result in a more reliable sampling of >L_{star}_ galaxies and allow us to reassess the form of the UV LFs. Our new LF results strengthen our earlier findings to 3.4{sigma} significance for a steeper faint-end slope of the UV LF at z>4, with {alpha} evolving from {alpha}=-1.64+/-0.04 at z~4 to {alpha}=-2.06+/-0.13 at z~7 (and {alpha}=-2.02+/-0.23 at z~8), consistent with that expected from the evolution of the halo mass function. We find less evolution in the characteristic magnitude M^*^ from z~7 to z~4 the observed evolution in the LF is now largely represented by changes in {phi}_{star}_. No evidence for a non-Schechter-like form to the z~4-8 LFs is found. A simple conditional LF model based on halo growth and evolution in the M/L ratio ({alpha}(1+z}^-1.5^) of halos provides a good representation of the observed evolution.
- ID:
- ivo://CDS.VizieR/J/ApJ/684/905
- Title:
- z>1 galaxy clusters from IRAC Shallow Survey
- Short Name:
- J/ApJ/684/905
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have identified 335 galaxy cluster and group candidates, 106 of which are at z>1, using a 4.5um-selected sample of objects from a 7.25deg^2^ region in the Spitzer Infrared Array Camera (IRAC) Shallow Survey. Clusters were identified as three-dimensional overdensities using a wavelet algorithm, based on photometric redshift probability distributions derived from IRAC and NOAO Deep Wide-Field Survey data. We estimate only ~10% of the detections are spurious. To date 12 of the z>1 candidates have been confirmed spectroscopically, at redshifts from 1.06 to 1.41. Velocity dispersions of ~750km/s for two of these argue for total cluster masses well above 10^14^M_{sun}_, as does the mass estimated from the rest-frame near-infrared stellar luminosity. Although not selected to contain a red sequence, some evidence for red sequences is present in the spectroscopically confirmed clusters, and brighter galaxies are systematically redder than the mean galaxy color in clusters at all redshifts.
- ID:
- ivo://CDS.VizieR/J/ApJ/743/9
- Title:
- z=3.1 LAEs morphological properties
- Short Name:
- J/ApJ/743/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a morphological analysis of the rest-frame ultraviolet emission of 78 resolved, high signal-to-noise z~3.1 Ly{alpha} emitters (LAEs) in the Extended Chandra Deep Field-South. Using Hubble Space Telescope/Advanced Camera for Surveys V-band images taken as part of the Galaxy Evolution from Morphology and SEDs, Great Observatories Origins Deep Survey, and Hubble Ultra Deep Field surveys, we investigate both single-component and multi-component LAEs, and derive concentration indices, Sersic indices, ellipticities, and half-light radii for all resolved components and systems with a signal-to-noise >30. We show that, although the LAE population is heterogeneous in nature, most LAEs are highly concentrated, with a distribution of C values similar to that measured for field stars; this suggests that the diagnostic is a poor discriminator near the resolution limit. The LAEs also display a wide range of Sersic indices (0<n<12), similar to that seen for galaxies in the local neighborhood. However, the majority of LAEs have n<2, and a visual inspection of the images suggests that the small-n objects have extended or multimodal luminosity profiles, while the LAEs with n>2 have compact components surrounded by diffuse emission. Moreover, unlike nearby spiral galaxies, whose distribution of ellipticities is flat, the LAE ellipticity distribution peaks near 1-b/a~0.55. Thus, the population has more in common with z~3 Lyman-break galaxies than local star-forming objects.
- ID:
- ivo://CDS.VizieR/J/MNRAS/478/5336
- Title:
- z-low satellite galaxies in COSMOS survey
- Short Name:
- J/MNRAS/478/5336
- Date:
- 10 Dec 2021 14:18:30
- Publisher:
- CDS
- Description:
- Faint dwarf satellite galaxies are important as tracers of small-scale structure, but remain poorly characterized outside the Local Group, due to the difficulty of identifying them consistently at larger distances. We review a recently proposed method for estimating the average satellite population around a given sample of nearby bright galaxies, using a combination of size and magnitude cuts (to select low-redshift dwarf galaxies preferentially) and clustering measurements (to estimate the fraction of true satellites in the cut sample). We test this method using the high-precision photometric redshift catalogue of the COSMOS survey, exploring the effect of specific cuts on the clustering signal. The most effective of the size-magnitude cuts considered recover the clustering signal around low-redshift primaries (z<0.15) with about two-thirds of the signal and 80 per cent of the signal-to-noise ratio obtainable using the full COSMOS photometric redshifts. These cuts are also fairly efficient, with more than one-third of the selected objects being clustered satellites. We conclude that structural selection represents a useful tool in characterizing dwarf populations to fainter magnitudes and/or over larger areas than are feasible with spectroscopic surveys. In reviewing the low-redshift content of the COSMOS field, we also note the existence of several dozen objects that appear resolved or partially resolved in the HST imaging, and are confirmed to be local (at distances of ~250Mpc or less) by their photometric or spectroscopic redshifts. This underlines the potential for future space-based surveys to reveal local populations of intrinsically faint galaxies through imaging alone.
- ID:
- ivo://CDS.VizieR/J/ApJ/783/119
- Title:
- z~1 Ly{alpha} emitters. I. 135 candidates from GALEX
- Short Name:
- J/ApJ/783/119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We construct a flux-limited sample of 135 candidate z~1 Ly{alpha} 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 7Gyr 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 Ly{alpha} 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 Ly{alpha} escape fraction of 0.7%+/-0.4%.
- ID:
- ivo://CDS.VizieR/J/ApJ/759/133
- Title:
- z=2.4 Ly{alpha} emitters in the 53W002 field
- Short Name:
- J/ApJ/759/133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of our wide-field narrowband imaging of the field around the radio galaxy 53W002 at z=2.390 with Subaru/Suprime-Cam. A custom-made filter, NB413, centered at 4140{AA} with a width of 83{AA} is used to observe the 31'x24' area around the radio galaxy. We detected 204 Ly{alpha} emitters (LAEs) at z=2.4 with a rest-frame equivalent width larger than 25{AA} to the depth of 26 AB mag (in NB413). The entire LAE population in the 53W002 field has an average number density and distributions of equivalent width and size that are similar to those of other fields at z~2. We identify a significant high-density region (53W002F-HDR) that spreads over {approx}5'x4' near 53W002, where the LAE number density is nearly four times as large as the average of the entire field. Using the probability distribution function of density fluctuation, we evaluate the rareness probability of 53W002F-HDR to be 0.9^+2.4^_-0.62_%, which corresponds to a moderately rich structure. No notable environmental dependency at the comoving scale of 10Mpc is found for the distributions of the Ly{alpha} equivalent width and luminosity in the field. We also detected four Ly{alpha} blobs, one of which is newly discovered. They are all located in the rims of high-density regions. The biased location and unique morphologies in Ly{alpha} suggest that galaxy interaction plays a key role in their formation.