- ID:
- ivo://CDS.VizieR/J/ApJ/711/284
- Title:
- Galaxy Zoo: AGN host galaxies
- Short Name:
- J/ApJ/711/284
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use data from the Sloan Digital Sky Survey and visual classifications of morphology from the Galaxy Zoo project to study black hole growth in the nearby universe (z<0.05) and to break down the active galactic nucleus (AGN) host galaxy population by color, stellar mass, and morphology. We find that the black hole growth at luminosities L[OIII]>10^40^erg/s in early- and late-type galaxies is fundamentally different. AGN host galaxies as a population have a broad range of stellar masses (10^10^-10^11^M_{sun}_), reside in the green valley of the color-mass diagram and their central black holes have median masses around 10^6.5^M_{sun}_. However, by comparing early- and late-type AGN host galaxies to their non-active counterparts, we find several key differences: in early-type galaxies, it is preferentially the galaxies with the least massive black holes that are growing, while in late-type galaxies, it is preferentially the most massive black holes that are growing. At high-Eddington ratios (L/L_Edd_>0.1), the only population with a substantial fraction of AGNs are the low-mass green valley early-type galaxies.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/461/3663
- Title:
- Galaxy Zoo 2: new classification
- Short Name:
- J/MNRAS/461/3663
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The majority of galaxies in the local Universe exhibit spiral structure with a variety of forms. Many galaxies possess two prominent spiral arms, some have more, while others display a many-armed flocculent appearance. Spiral arms are associated with enhanced gas content and star formation in the discs of low-redshift galaxies, so are important in the understanding of star formation in the local universe. As both the visual appearance of spiral structure, and the mechanisms responsible for it vary from galaxy to galaxy, a reliable method for defining spiral samples with different visual morphologies is required. In this paper, we develop a new debiasing method to reliably correct for redshift-dependent bias in Galaxy Zoo 2, and release the new set of debiased classifications. Using these, a luminosity-limited sample of ~18000 Sloan Digital Sky Survey spiral galaxies is defined, which are then further sub-categorized by spiral arm number. In order to explore how different spiral galaxies form, the demographics of spiral galaxies with different spiral arm numbers are compared. It is found that whilst all spiral galaxies occupy similar ranges of stellar mass and environment, many-armed galaxies display much bluer colours than their two-armed counterparts. We conclude that two-armed structure is ubiquitous in star-forming discs, whereas many-armed spiral structure appears to be a short-lived phase, associated with more recent, stochastic star-formation activity.
- ID:
- ivo://CDS.VizieR/J/MNRAS/455/2440
- Title:
- Gal. 2D phot. decompositions in r, g & i bands
- Short Name:
- J/MNRAS/455/2440
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We extend the catalogue of two-dimensional, Point-Spread-Function-corrected de Vacouleurs, Sersic, de Vacouleurs+Exponential, and Sersic+Exponential fits of ~7x10^5^ galaxies presented in Meert+ (2015, J/MNRAS/446/3943) to include the g and i bands. Fits are analysed using the physically motivated flagging system presented in the original text, making adjustments for the differing signal to noise when necessary. We compare the fits in each of the g, r, and i bands. Fixed aperture magnitudes and colours are also provided for all galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/676/944
- Title:
- GALEX and CFHTLS candidate tidal disruption events
- Short Name:
- J/ApJ/676/944
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present two luminous UV/optical flares from the nuclei of apparently inactive early-type galaxies at z=0.37 and 0.33 that have the radiative properties of a flare from the tidal disruption of a star. In this paper we report the second candidate tidal disruption event discovery in the UV by the GALEX Deep Imaging Survey and present simultaneous optical light curves from the CFHTLS Deep Imaging Survey for both UV flares.
- ID:
- ivo://CDS.VizieR/J/ApJ/872/95
- Title:
- GALEX and Gaia data for APOGEE red clump stars
- Short Name:
- J/ApJ/872/95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Although core helium-burning red clump (RC) stars are faint at ultraviolet wavelengths, their ultraviolet (UV)-optical color is a unique and accessible probe of their physical properties. Using data from the Galaxy Evolution Explorer All Sky Imaging Survey (GALEX AIS), Gaia Data Release 2, and the Sloan Digital Sky Survey Apache Point Observatory Galactic Evolution Experiment (APOGEE) DR14 survey, we find that spectroscopic metallicity is strongly correlated with the location of an RC star in the UV-optical color-magnitude diagram. The RC has a wide spread in (NUV-G)_0_ color of over 4mag compared to a 0.7mag range in (G_BP_-G_RP_)_0_. We propose a photometric, dust-corrected, UV-optical (NUV-G)_0_ color-metallicity [Fe/H] relation using a sample of 5175 RC stars from APOGEE. We show that this relation has a scatter of 0.16dex and is easier to obtain for large, wide-field samples than for spectroscopic metallicities. Importantly, the effect may be comparable to the spread in RC color attributed to extinction in other studies.
- ID:
- ivo://CDS.VizieR/J/ApJS/199/37
- Title:
- GALEX catalog of star clusters in M31
- Short Name:
- J/ApJS/199/37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a comprehensive catalog of 700 confirmed star clusters in the field of M31 compiled from three major existing catalogs. We detect 418 and 257 star clusters in Galaxy Evolution Explorer near-ultraviolet and far-ultraviolet (FUV) imaging, respectively. Our final catalog includes photometry of star clusters in up to 16 passbands ranging from FUV to NIR as well as ancillary information such as reddening, metallicity, and radial velocities. In particular, this is the most extensive and updated catalog of UV-integrated photometry for M31 star clusters. Ages and masses of star clusters are derived by fitting the multi-band photometry with model spectral energy distribution (SED); UV photometry enables more accurate age estimation of young clusters. Our catalog includes 182 young clusters with ages less than 1Gyr. Our estimated ages and masses of young clusters are in good agreement with previously determined values in the literature. The mean age and mass of young clusters are about 300Myr and 10^4^M_{sun}_, respectively.
- ID:
- ivo://CDS.VizieR/J/ApJ/798/41
- Title:
- GALEX NUV observations of bright M-type stars
- Short Name:
- J/ApJ/798/41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Planets orbiting within the close-in habitable zones of M dwarf stars will be exposed to elevated high-energy radiation driven by strong magnetohydrodynamic dynamos during stellar youth. Near-ultraviolet (NUV) irradiation can erode and alter the chemistry of planetary atmospheres, and a quantitative description of the evolution of NUV emission from M dwarfs is needed when modeling these effects. We investigated the NUV luminosity evolution of early M-type dwarfs by cross-correlating the Lepine & Gaidos catalog (2011, J/AJ/142/138) of bright M dwarfs with the Galaxy Evolution Explorer (GALEX) catalog of NUV (1771-2831{AA}) sources. Of the 4805 sources with GALEX counterparts, 797 have NUV emission significantly (>2.5{sigma}) in excess of an empirical basal level. We inspected these candidate active stars using visible-wavelength spectra, high-resolution adaptive optics imaging, time-series photometry, and literature searches to identify cases where the elevated NUV emission is due to unresolved background sources or stellar companions; we estimated the overall occurrence of these "false positives" (FPs) as ~16%. We constructed an NUV luminosity function that accounted for FPs, detection biases of the source catalogs, and GALEX upper limits. We found the NUV luminosity function to be inconsistent with predictions from a constant star-formation rate and simplified age-activity relation defined by a two-parameter power law.
- ID:
- ivo://CDS.VizieR/J/A+A/544/A101
- Title:
- GALEX observations of Herschel Reference Survey
- Short Name:
- J/A+A/544/A101
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present GALEX far-ultraviolet (FUV) and near-ultraviolet (NUV) as well as SDSS g, r, i photometry and structural parameters for the Herschel Reference Survey, a magnitude-, volume-limited sample of nearby galaxies in different environments. We use this unique dataset to investigate the ultraviolet (UV) structural scaling relations of nearby galaxies and to determine how the properties of the UV disk vary with atomic hydrogen content and environment.
- ID:
- ivo://CDS.VizieR/J/ApJ/733/74
- Title:
- GALEX - SDSS properties of local galaxies
- Short Name:
- J/ApJ/733/74
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of the first unbiased search for extended ultraviolet (XUV)-disk galaxies undertaken to determine the space density of such galaxies. Our sample contains 561 local (0.001<z<0.05) galaxies that lie in the intersection of available Galaxy Evolution Explorer (GALEX) deep imaging (exposure time >1.5x10^4^s) and Sloan Digital Sky Survey DR7 footprints. We explore modifications to the standard classification scheme for our sample that includes both disk- and bulge-dominated galaxies. Visual classification of each galaxy in the sample reveals an XUV-disk frequency of up to 20% for the most nearby portion of our sample. On average over the entire sample (out to z=0.05) the frequency ranges from a hard limit of 4%-14%. The GALEX imaging allows us to detect XUV disks beyond 100 Mpc. The XUV regions around XUV-disk galaxies are consistently bluer than the main bodies. We find a surprisingly high frequency of XUV emission around luminous red (NUV-r>5) and green valley (3<NUV-r<5) galaxies. The XUV-disk space density in the local universe is >(1.5-4.2)x10^-3^Mpc^-3^. Using the XUV emission as an indicator of recent gas accretion, we estimate that the cold gas accretion rate onto these galaxies is >(1.7-4.6)x10^-3^M_{sun}_/Mpc^3^/yr. The number of XUV disks in the green valley and the estimated accretion rate onto such galaxies points to the intriguing possibility that 7%-18% of galaxies in this population are transitioning away from the red sequence.
- ID:
- ivo://CDS.VizieR/J/AJ/133/1780
- Title:
- GALEX/SDSS quasar catalog
- Short Name:
- J/AJ/133/1780
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of the broadband UV and optical properties of z~<3.4 quasars matched in the Galaxy Evolution Explorer (GALEX) General Data Release 1 (GR1) and the Sloan Digital Sky Survey (SDSS) Data Release 3 (DR3). Of the 6371 SDSS DR3 quasars covered by 204 GALEX GR1 tiles, 5380 (84%) have near-UV detections, while 3034 (48%) have both near-UV and far-UV detections using a matching radius of 7". Most of the DR3 sample quasars are detected in the near-UV until z~1.7, with the near-UV detection fraction dropping to ~50% by z~2.
