- ID:
- ivo://CDS.VizieR/J/ApJ/810/71
- Title:
- UV mag of candidate galaxies at 3~<z~<8.5
- Short Name:
- J/ApJ/810/71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a robust measurement and analysis of the rest-frame ultraviolet (UV) luminosity functions at z=4-8. We use deep Hubble Space Telescope imaging over the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey/GOODS fields, the Hubble Ultra Deep Field, and the Hubble Frontier Field deep parallel observations near the Abell 2744 and MACS J0416.1-2403 clusters. The combination of these surveys provides an effective volume of 0.6-1.2x10^6^Mpc^3^ over this epoch, allowing us to perform a robust search for faint (M_UV_=-18) and bright (M_UV_<-21) high-redshift galaxies. We select candidate galaxies using a well-tested photometric redshift technique with careful screening of contaminants, finding a sample of 7446 candidate galaxies at 3.5<z<8.5, with >1000 galaxies at z~6-8. We measure both a stepwise luminosity function for candidate galaxies in our redshift samples, and a Schechter function, using a Markov Chain Monte Carlo analysis to measure robust uncertainties. At the faint end, our UV luminosity functions agree with previous studies, yet we find a higher abundance of UV-bright candidate galaxies at z>=6.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/173/293
- Title:
- UV-Optical galaxy color-magnitude diagram I.
- Short Name:
- J/ApJS/173/293
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have analyzed the bivariate distribution of galaxies as a function of ultraviolet-optical colors and absolute magnitudes in the local universe. The sample consists of galaxies with redshifts and optical photometry from the Sloan Digital Sky Survey (SDSS) main galaxy sample matched with detections in the near-ultraviolet (NUV) and far-ultraviolet (FUV) bands in the Medium Imaging Survey being carried out by the Galaxy Evolution Explorer (GALEX) satellite. Finally, we present the distribution of galaxies as a function of specific star formation rate and stellar mass. The specific star formation rates imply that galaxies along the blue sequence progress from low-mass galaxies with star formation rates that increase somewhat with time to more massive galaxies with a more or less constant star formation rate.
- ID:
- ivo://CDS.VizieR/J/A+A/581/A125
- Title:
- UV/Optical/NIR spectroscopy GRB hosts
- Short Name:
- J/A+A/581/A125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present data and initial results from VLT/X-shooter emission-line spectroscopy of 96 galaxies selected by long gamma-ray bursts (GRBs) at 0.1<z<3.6, the largest sample of GRB host spectra available to date. Most of our GRBs were detected by Swift and 76% are at 0.5<z<2.5 with a median z_med_~1.6.
- ID:
- ivo://CDS.VizieR/J/AJ/141/205
- Title:
- UVOT imaging of M81 and Holmberg IX
- Short Name:
- J/AJ/141/205
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Swift UV/Optical Telescope (UVOT) imaging of the galaxies M81 and Holmberg IX. We combine UVOT imaging in three near-ultraviolet (NUV) filters (uvw2: 1928{AA}; uvm2: 2246{AA}; uvw1: 2600{AA}) with ground-based optical imaging from the Sloan Digital Sky Survey to constrain the stellar populations of both galaxies. Our analysis consists of three different methods. First, we use the NUV imaging to identify UV star-forming knots and then perform spectral energy distribution (SED) modeling on the UV/optical photometry of these sources. Second, we measure surface brightness profiles of the disk of M81 in the NUV and optical. Lastly, we use SED fitting of individual pixels to map the properties of the two galaxies.
- ID:
- ivo://CDS.VizieR/J/A+AS/109/341
- Title:
- UV properties of normal galaxies. II.
- Short Name:
- J/A+AS/109/341
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the last decade several satellite and balloon borne experiments have collected a large number of ultraviolet fluxes of normal galaxies measured through apertures of various sizes and shapes. We have homogenized this data set by deriving scale corrections with respect to IUE. In a forthcoming paper, these data will be used to derive standard luminosity profiles and total magnitudes.
- ID:
- ivo://CDS.VizieR/J/A+AS/114/527
- Title:
- UV properties of normal galaxies. III.
- Short Name:
- J/A+AS/114/527
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the previous papers of this series (Longo et al. =1991A&AS...90..375L; Rifatto et al. =1995A&AS..109..341R) we collected and reduced to the same system all the available photometric data obtained in the ultraviolet (UV) range for normal (i.e. non active) galaxies. Here we use these data to derive standard UV luminosity profiles for three morphological bins (E/S0; Sa/Sb; Sc/Sd) and extrapolated total magnitudes for almost 400 galaxies. We find that: 1) the UV growth curves are well matched by the B-band revised standard luminosity profiles, once a proper shift in the effective radius is applied, and 2) the UV light in early-type galaxies is more centrally concentrated than the visible light.
- ID:
- ivo://CDS.VizieR/J/A+A/545/A141
- Title:
- UV selected sources in the GOODS-S field
- Short Name:
- J/A+A/545/A141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Dust attenuation in galaxies is poorly known, especially at high redshift. And yet the amount of dust attenuation is a key parameter to deduce accurate star formation rates from ultraviolet (UV) rest-frame measurements. The wavelength dependence of the dust attenuation is also of fundamental importance to interpret the observed spectral energy distributions (SEDs) and to derive photometric redshifts or physical properties of galaxies. We want to study dust attenuation at UV wavelengths at high redshift, where the UV is redshifted to the observed visible light wavelength range. In particular, we search for a UV bump and related implications for dust attenuation determinations.
- ID:
- ivo://CDS.VizieR/J/ApJ/770/137
- Title:
- UV star clusters in 4 elliptical galaxies
- Short Name:
- J/ApJ/770/137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Small amounts of star formation in elliptical galaxies are suggested by several results: surprisingly young ages from optical line indices, cooling X-ray gas, and mid-infrared dust emission. Such star formation has previously been difficult to directly detect, but using ultraviolet Hubble Space Telescope Wide Field Camera 3 imaging, we have identified individual young stars and star clusters in four nearby ellipticals. Ongoing star formation is detected in all galaxies, including three ellipticals that have previously exhibited potential signposts of star-forming conditions (NGC 4636, NGC 4697, and NGC 4374), as well as the typical "red and dead" NGC 3379. The current star formation in our closest targets, where we are most complete, is between 2.0 and 9.8x10^-5^M_{sun}_/yr. The star formation history was roughly constant from 0.5 to 1.5 Gyr (at (3-5)x10^-4^M_{sun}_/yr), but decreased by a factor of several in the past 0.3Gyr. Most star clusters have a mass between 10^2^ and 10^4^M_{sun}_. The specific star formation rates of ~10^-16^/yr (at the present day) or ~10^-14^/yr (when averaging over the past Gyr) imply that a fraction 10^-8^ of the stellar mass is younger than 100Myr and 10^-5^ is younger than 1Gyr, quantifying the level of frosting of recent star formation over the otherwise passive stellar population. There is no obvious correlation between either the presence or spatial distribution of postulated star formation indicators and the star formation we detect.
- ID:
- ivo://CDS.VizieR/J/ApJ/731/28
- Title:
- UV star-forming association in spiral galaxies
- Short Name:
- J/ApJ/731/28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate recent star formation in the extended ultraviolet (XUV) disks of five nearby galaxies (NGC 0628, NGC 2090, NGC 2841, NGC 3621, and NGC 5055) using a long wavelength baseline comprised of ultraviolet and mid-infrared imaging from the Galaxy Evolution Explorer and the Spitzer Infrared Array Camera. We identify 229 unresolved stellar complexes across targeted portions of their XUV disks and utilize spectral energy distribution fitting to measure their stellar ages and masses through comparison with Starburst99 population synthesis models of instantaneous burst populations. We find that the median age of outer-disk associations in our sample is ~100Myr with a large dispersion that spans the entire range of our models (1Myr to 1Gyr). This relatively evolved state for most associations addresses the observed dearth of H{alpha} emission in some outer disks, as H{alpha} can only be observed in star-forming regions younger than ~10Myr. The large age dispersion is robust against variations in extinction (in the range E(B-V)=0-0.3mag) and variations in the upper end of the stellar initial mass function (IMF). In particular, we demonstrate that the age dispersion is insensitive to steepening of the IMF, up to extreme slopes.
- ID:
- ivo://CDS.VizieR/J/ApJ/703/614
- Title:
- UV star-forming regions in M31
- Short Name:
- J/ApJ/703/614
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a comprehensive study of star-forming (SF) regions in the nearest large spiral galaxy M31. We use Galaxy Evolution Explorer (GALEX) far-UV (1344-1786{AA}, FUV) and near-UV (1771-2831{AA}, NUV) imaging to detect young massive stars and trace the recent star formation across the galaxy. The FUV and NUV flux measurements of the SF regions, combined with ground-based data for estimating the reddening by interstellar dust from the massive stars they contain, are used to derive their ages and masses. The GALEX imaging, combining deep sensitivity and coverage of the entire galaxy, provides a complete picture of the recent star formation in M31 and its variation with environment throughout the galaxy. The FUV and NUV measurements are sensitive to detect stellar populations younger than a few hundred Myr. We detected 894 SF regions, with size >=1600pc^2^ above an average FUV flux limit of ~26ABmag/arcsecond^2^, over the whole 26kpc (radius) galaxy disk. We derive the star formation history of M31 within this time span. The star formation rate (SFR) from the youngest UV sources (age <=10Myr) is comparable to that derived from H{alpha}, as expected.