- 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.
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Search Results
- 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/MNRAS/436/34
- Title:
- GALEX Arecibo SDSS survey. Final data release
- Short Name:
- J/MNRAS/436/34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the final data release from the GALEX Arecibo SDSS Survey (GASS), a large Arecibo programme that measured the HI properties for an unbiased sample of ~800 galaxies with stellar masses greater than 10^10^M_{sun}_ and redshifts 0.025<z<0.05. This release includes new Arecibo observations for 250 galaxies. We use the full GASS sample to investigate environmental effects on the cold gas content of massive galaxies at fixed stellar mass. The environment is characterized in terms of dark matter halo mass, obtained by cross-matching our sample with the Sloan Digital Sky Survey (SDSS) group catalogue of Yang et al. Our analysis provides, for the first time, clear statistical evidence that massive galaxies located in haloes with masses of 10^13^-10^14^M_{sun}_ have at least 0.4dex less HI than objects in lower density environments. The process responsible for the suppression of gas in group galaxies most likely drives the observed quenching of the star formation in these systems. Our findings strongly support the importance of the group environment for galaxy evolution, and have profound implications for semi-analytic models of galaxy formation, which currently do not allow for stripping of the cold interstellar medium in galaxy groups.
- ID:
- ivo://CDS.VizieR/J/A+A/611/A42
- Title:
- GALEX BCG galaxies sample properties
- Short Name:
- J/A+A/611/A42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- At low redshift, early-type galaxies often exhibit a rising flux with decreasing wavelength in the 1000-2500{AA} range, called "UV upturn". The origin of this phenomenon is debated, and its evolution with redshift is poorly constrained. The observed GALEX FUV-NUV color can be used to probe the UV upturn up to redshift about 0.5. We aim to provide constraints on the existence of the UV upturn up to redshift ~0.4 in Brightest Cluster Galaxies (BCG) galaxies located behind the Virgo cluster, using data from the GUViCS survey. We estimate the FUV and NUV observed magnitudes for BCGs from the maxBCG catalog in the GUViCS fields. We increase the number of non local galaxies identified as BCGs with GALEX photometry from a few tens of galaxies to 166 (64 when restricting this sample to relatively small error-bars). We also estimate a central color within a 20-arcsec aperture. By using the r band luminosity from the maxBCG catalog, we can separate blue FUV-NUV due to recent star formation and candidate upturn cases. We use Lick indices to verify their similitude to redshift 0 upturn cases. We clearly detect a population of blue FUV-NUV BCGs in the redshift range 0.10-0.35, vastly improving the existing constraints at these epochs by increasing the number of galaxies studied, and by exploring a redshift range with no previous data (beyond 0.2), spanning 1 more Gyr in the past. These galaxies bring new constrains that can help distinguish between assumptions concerning the stellar populations causing the UV upturn phenomenon. The existence of a large number of UV upturns around redshift 0.25 favors the existence of a binary channel among the sources proposed in the literature.
- 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/II/312
- Title:
- GALEX-DR5 (GR5) sources from AIS and MIS
- Short Name:
- II/312
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Galaxy Evolution Explorer (GALEX) is an ultraviolet space telescope launched in 2003. It observes in 2 ultraviolet bands, FUV (far-UV) and NEV (near-UV), which characteristics are: -------------------------------------------------------------------- FUV NUV -------------------------------------------------------------------- Bandwidth 1344-1786 1771-2831 ({AA}) Effective wavelength 1538.6 2315.7 ({AA}) Astrometry (R<0.6deg) 0.59 0.49 (arcsec) Photometry 0.05 0.03 (ABmag) Zero point 18.82 20.08 (ABmag) Image resolution 4.2 5.3 (arcsec/pix) Spectral resolution 200 118 ({delta}{lambda}/{lambda}) -------------------------------------------------------------------- Two catalogs of UV sources from GALEX surveys are provided: * the All-sky Imaging Survey (AIS), containing 65.3million sources over 21435 square degrees, has a 5{sigma} depth in FUV/NUV of 19.9/20.8 (AB magnitudes); * the Medium-depth Imaging Survey (MIS), with 12.6million sources, covers 1579 square degrees and has a 5{sigma} depth in FUV/NUV of 22.6/22.7 (AB magnitudes). See also the description by Bianchi et al. (2011MNRAS.411.2770B)
- ID:
- ivo://CDS.VizieR/J/MNRAS/493/2745
- Title:
- GALEX EUV quasar colours of SDSS QSOs DR14
- Short Name:
- J/MNRAS/493/2745
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The rest-frame far to extreme ultraviolet (UV) colour-redshift relationship has been constructed from data on over 480,000 quasars carefully cross-matched between SDSS Data Release 14 and the final GALEX photometric catalog. UV matching and detection probabilities are given for all the quasars, including dependencies on separation, optical brightness, and redshift. Detection limits in the UV bands are also provided for all objects. The UV colour distributions are skewed redward at virtually all redshifts, especially when detection limits are accounted for. The median GALEX far-UV minus near-UV (FUV-NUV) colour-redshift relation is reliably determined up to z~2.8, corresponding to rest-frame wavelengths as short as 400{AA}. Extreme-UV (EUV) colours are substantially redder than found previously, when detection limits are properly accounted for. Quasar template spectra were forward modeled through the GALEX bandpasses, accounting for intergalactic opacity, intrinsic reddening, and continuum slope variations. Intergalactic absorption by itself cannot account for the very red EUV colours. The colour-redshift relation is consistent with no intrinsic reddening, at least for SMC-like extinction. The best model fit has a far-UV continuum power-law slope of -0.34+/-0.03 consistent with previous results, but an EUV slope of -2.90+/-0.04 that is much redder and inconsistent with any previous composite value (all >-2.0). The EUV slope difference can be attributed in part to the tendency of previous studies to preferentially select UV brighter and bluer objects. The weak EUV flux suggests quasar accretion disc models that include outflows such as disc winds.
- 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.
