- ID:
- ivo://CDS.VizieR/J/ApJ/793/115
- Title:
- UV-continuum slopes beta for z~4-8 galaxies
- Short Name:
- J/ApJ/793/115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We measure the UV-continuum slope {beta} for over 4000 high-redshift galaxies over a wide range of redshifts z~4-8 and luminosities from the HST HUDF/XDF, HUDF09-1, HUDF09-2, ERS, CANDELS-N, and CANDELS-S data sets. Our new {beta} results reach very faint levels at z~4 (-15.5 mag: 0.006 L_z=3_^*^), z~5 (-16.5 mag: 0.014 L_z=3_^*^), and z~6 and z~7 (-17 mag: 0.025 L_z=3_^*^). Inconsistencies between previous studies led us to conduct a comprehensive review of systematic errors and develop a new technique for measuring {beta} that is robust against biases that arise from the impact of noise. We demonstrate, by object-by-object comparisons, that all previous studies, including our own and those done on the latest HUDF12 data set, suffered from small systematic errors in {beta}. We find that after correcting for the systematic errors (typically {Delta}{beta}~0.1-0.2) all {beta} results at z~7 from different groups are in excellent agreement. The mean {beta} we measure for faint (-18 mag: 0.1L_z=3_^*^) z~4, z~5, z~6, and z~7 galaxies is -2.03+/-0.03+/-0.06 (random and systematic errors), -2.14+/-0.06+/-0.06, -2.24+/-0.11+/-0.08, and -2.30+/-0.18+/-0.13, respectively. Our new {beta} values are redder than we have reported in the past, but bluer than other recent results. Our previously reported trend of bluer {beta}'s at lower luminosities is confirmed, as is the evolution to bluer {beta}'s at high redshifts. {beta} appears to show only a mild luminosity dependence faintward of M_UV, AB_~-19 mag, suggesting that the mean {beta} asymptotes to ~-2.2 to -2.4 for faint z>=4 galaxies. At z~7, the observed {beta}'s suggest non-zero, but low dust extinction, and they agree well with values predicted in cosmological hydrodynamical simulations.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+AS/111/169
- Title:
- UV-excess quasar candidates
- Short Name:
- J/A+AS/111/169
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have developed a procedure (so called PAPA) for measurement of magnitudes (about 0.1mag accurate) and positions (with accuracy better than 0.5arcsec) of all the objects present on photographic plates digitised with the MAMA machine. This homogeneous procedure was applied to four Schmidt plates - in U, B and twice V - covering the Palomar-Sky-Survey field PS +30deg 13h00m, a 40-square-degree zone at the North Galactic Pole. A general-interest exhaustive tricolour catalogue of 19542 star-like objects down to V=20.0 has been produced and we selected 1681 quasar candidates on the basis of ultraviolet excess and, when possible, absence of any measurable proper motion. The astrometric and photometric catalogue of the candidates is given in electronic form.
- ID:
- ivo://CDS.VizieR/J/MNRAS/420/1115
- Title:
- UV-excess sources from UVEX
- Short Name:
- J/MNRAS/420/1115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first catalogue of point-source ultraviolet (UV)-excess sources selected from the UV-Excess Survey of the Northern Galactic Plane (UVEX). UVEX images the Northern Galactic Plane in the U, g, r and HeI{lambda}5875 bands in the Galactic latitude range -5<b<+5{deg}. Through an automated algorithm, which works on a field-to-field basis, we select blue UV-excess sources in 211 square degrees from the (U-g) versus (g-r) colour-colour diagram and the g versus (U-g) and g versus (g-r) colour-magnitude diagrams. The UV-excess catalogue covers the magnitude range 14<g<22.5, contains 2170 sources and consists of a mix of white dwarfs, post-common-envelope objects, interacting binaries, quasars and active galactic nuclei. Two other samples of outliers were found during the selection: (i) a "subdwarf" sample, consisting of no less than 9872 candidate metal-poor stars or lightly reddened main-sequence stars, and (ii) a "purple" sample consisting of 803 objects, most likely a mix of reddened late M giants, T Tauri stars, planetary nebulae, symbiotic stars and carbon stars. Cross-matching the selected UV-excess catalogue with other catalogues aids with the first classification of the different populations and shows that more than 99 per cent of our selected sources are unidentified sources.
- ID:
- ivo://CDS.VizieR/J/MNRAS/406/420
- Title:
- UV/far-IR data of infrared excess sources
- Short Name:
- J/MNRAS/406/420
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the nature of Infrared Excess sources (IRX), which are proposed as candidates for luminous [LX(2-10keV)>10^43^erg/s] Compton thick (NH>2x10^24^cm^-2^) QSOs at z~~2. Lower redshift, z~~1, analogues of the distant IRX population are identified by first redshifting to z=2 the spectral energy distributions (SEDs) of all sources with secure spectroscopic redshifts in the AEGIS (6488) and the GOODS-North (1784) surveys and then selecting those that qualify as IRX sources at that redshift. A total of 19 galaxies are selected. The mean redshift of the sample is z~~1. We do not find strong evidence for Compton thick QSOs in the sample. For nine sources with X-ray counterparts, the X-ray spectra are consistent with Compton thin active galactic nucleus (AGN). Only three of them show tentative evidence for Compton thick obscuration. The SEDs of the X-ray undetected population are consistent with starburst activity.
- ID:
- ivo://CDS.VizieR/J/A+A/562/A34
- Title:
- UV FeII template from LBQS 2113-4538
- Short Name:
- J/A+A/562/A34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- MgII line is of extreme importance for intermediate quasars since it allows to measure the black hole mass in these sources and to use them as probes of the distribution of dark energy in the Universe, as a complementary tool to SN Ia. Reliable use of MgII requires good understanding of all systematic effects involved in the measurement of the line properties, including the contamination by FeII UV emission.
- ID:
- ivo://CDS.VizieR/J/ApJ/879/131
- Title:
- UV-FIR obs. of post-starburst galaxies & dust masses
- Short Name:
- J/ApJ/879/131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We derive dust masses (M_dust_) from the spectral energy distributions of 58 post-starburst galaxies (PSBs). There is an anticorrelation between specific dust mass (M_dust_/M_*_) and the time elapsed since the starburst ended, indicating that dust was either destroyed, expelled, or rendered undetectable over the ~1Gyr after the burst. The M_dust_/M_*_ depletion timescale, 205_-37_^+58^Myr, is consistent with that of the CO-traced M_H2_/M_*_, suggesting that dust and gas are altered via the same process. Extrapolating these trends leads to the M_dust_/M_*_ and M_H2_/M_*_ values of early-type galaxies (ETGs) within 1-2Gyr, a timescale consistent with the evolution of other PSB properties into ETGs. Comparing Mdust and M_H2_ for PSBs yields a calibration, log M_H2_=0.45logM_dust_+6.02, that allows us to place 33 PSBs on the Kennicutt-Schmidt (KS) plane, {Sigma}SFR-{Sigma}M_H2_. Over the first ~200-300Myr, the PSBs evolve down and off of the KS relation, as their star formation rate (SFR) decreases more rapidly than M_H2_. Afterwards, M_H2_ continues to decline whereas the SFR levels off. These trends suggest that the star formation efficiency bottoms out at 10^-11^/yr and will rise to ETG levels within 0.5-1.1Gyr afterwards. The SFR decline after the burst is likely due to the absence of gas denser than the CO-traced H2. The mechanism of the M_dust_/M_*_ and M_H2_/M_*_ decline, whose timescale suggests active galactic nucleus/low-ionization nuclear emission-line region feedback, may also be preventing the large CO-traced molecular gas reservoirs from collapsing and forming denser star-forming clouds.
- ID:
- ivo://CDS.VizieR/J/ApJ/756/164
- Title:
- UV galaxies in CANDELS from z=8 to z=4
- Short Name:
- J/ApJ/756/164
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the evolution of galaxy rest-frame ultraviolet (UV) colors in the epoch 4<~z<~8. We use new wide-field near-infrared data in the Great Observatories Origins Deep Survey-South field from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey, Hubble Ultra Deep Field (HUDF) 2009, and Early Release Science programs to select galaxies via photometric redshift measurements. Our sample consists of 2812 candidate galaxies at z>~3.5, including 113 at z=~7-8. We fit the observed spectral energy distribution to a suite of synthetic stellar population models and measure the value of the UV spectral slope ({beta}) from the best-fit model spectrum. We run simulations to show that this measurement technique results in a smaller scatter on {beta} than other methods, as well as a reduced number of galaxies with catastrophically incorrect {beta} measurements (i.e., {Delta}{beta}>1).
- ID:
- ivo://CDS.VizieR/J/ApJS/107/215
- Title:
- UV Images of Nearby Galaxies
- Short Name:
- J/ApJS/107/215
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The accompanying tables are part of a pictorial atlas of UV (2300A) images, obtained with the Hubble Space Telescope (HST) Faint Object Camera, of the central 22"x22" of 110 galaxies. The observed galaxies are an unbiased selection constituting about one half of a complete sample of all large (D>6') and nearby (V< 2000 km/s) galaxies. This is the first extensive UV imaging survey of normal galaxies. The data are useful for studying star formation, low-level nuclear activity, and UV emission by evolved stellar populations in galaxies. At the HST resolution (0.05"), the images display an assortment of morphologies and UV brightnesses. These include bright nuclear point sources, compact young star clusters scattered in the field or arranged in circumnuclear rings, centrally-peaked diffuse light distributions, and galaxies with weak or undetected UV emission. We measure the integrated 2300A flux in each image, and classify the UV morphology. The UV and optical parameters are given in the tables.
- ID:
- ivo://CDS.VizieR/J/AJ/162/47
- Title:
- UV luminosity in ~25000 2<z<9 galaxies
- Short Name:
- J/AJ/162/47
- Date:
- 16 Mar 2022 00:17:16
- Publisher:
- CDS
- Description:
- Here we provide the most comprehensive determinations of the rest-frame UV luminosity function (LF) available to date with the Hubble Space Telescope (HST) at z~2-9. Essentially all of the noncluster extragalactic legacy fields are utilized, including the Hubble Ultra Deep Field, the Hubble Frontier Fields parallel fields, and all five CANDELS fields, for a total survey area of 1136arcmin^2^. Our determinations include galaxies at z~2-3 leveraging the deep HDUV, UVUDF, and ERS WFC3/UVIS observations available over an ~150arcmin^2^ area in the GOODS-North and GOODS-South regions. All together, our collective samples include >24000 sources, >2.3x larger than previous selections with HST. We identify 5766, 6332, 7240, 3449, 1066, 601, 246, and 33 sources at z~2, 3, 4, 5, 6, 7, 8, and 9, respectively. Combining our results with an earlier z~10 LF determination by Oesch et al., we quantify the evolution of the UV LF. Our results indicate that there is (1) a smooth flattening of the faint-end slope {alpha} from {alpha}~-2.4 at z~10 to {alpha}~-1.5 at z~2, (2) minimal evolution in the characteristic luminosity M* at z>~2.5, and (3) a monotonic increase in the normalization log_10_\{phi}* from z~10 to 2, which can be well described by a simple second-order polynomial, consistent with an "accelerated" evolution scenario. We find that each of these trends (from z~10 to 2.5 at least) can be readily explained on the basis of the evolution of the halo mass function and a simple constant star formation efficiency model.
- ID:
- ivo://CDS.VizieR/J/ApJS/173/441
- Title:
- UV-Luminous galaxies discovered by GALEX
- Short Name:
- J/ApJS/173/441
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the properties of a sample of ultraviolet-luminous galaxies (UVLGs) selected by matching the Galaxy Evolution Explorer (GALEX) All-Sky Imaging and Medium Imaging Surveys with the Sloan Digital Sky Survey third data release. The overlap between these two surveys is roughly 450deg^2^. Of 25362 galaxies (with SDSS spectroscopy) in the range 0.0<z<0.3 detected by GALEX, there are 215 galaxies with L>2x10^10^L{sun} at 1530{AA} (observed wavelength).