- ID:
- ivo://CDS.VizieR/J/ApJ/701/1219
- Title:
- Galaxy survey in 3 QSO fields
- Short Name:
- J/ApJ/701/1219
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an imaging and spectroscopic survey of galaxies in fields around QSOs HE 0226-4110, PKS 0405-123, and PG 1216+069. The fields are selected to have ultraviolet echelle spectra available, which uncover 195 Ly{alpha} absorbers and 13 OVI absorbers along the three sightlines. We obtain robust redshifts for 1104 galaxies of rest-frame absolute magnitude M_R_-5logh<~-16 and at projected physical distances {rho}<~4h^-1^Mpc from the QSOs. Hubble Space Telescope (HST)/WFPC2 images of the fields around PKS 0405-123 and PG 1216+069 are available for studying the optical morphologies of absorbing galaxies. Combining the absorber and galaxy data, we perform a cross-correlation study to understand the physical origin of Ly{alpha} and OVI absorbers and to constrain the properties of extended gas around galaxies.
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- ID:
- ivo://CDS.VizieR/J/A+A/382/513
- Title:
- Galaxy warps in the HDF North and South
- Short Name:
- J/A+A/382/513
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a statistical study of the presence of galaxy warps in the Hubble deep fields. Among a complete sample of 45 edge-on galaxies above a diameter of 1.3", we find 5 galaxies to be certainly warped and 6 galaxies as good candidates. In addition, 4 galaxies reveal a characteristic U-warp. Compared to statistical studies of local warps, and taking into account the strong bias against observing the outer parts of galaxies at high redshift, these numbers point towards a very high frequency of warps at z~1: almost all galaxy discs might be warped. Furthermore, the amplitude of warps are stronger than for local warps. This is easily interpreted in terms of higher galaxy interactions and matter accretion in the past. This result supports these two mechanisms as the best candidates for the origin of early warps. The mean observed axis ratio of our sample of edge-on galaxies is significantly larger in the high-z sample than is found for samples of local spiral galaxies. This might be due to disk thickening due to more frequent galaxy interactions.
- ID:
- ivo://CDS.VizieR/J/PASP/125/2
- Title:
- Galaxy Zoo: A catalog of overlapping galaxy pairs
- Short Name:
- J/PASP/125/2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Analysis of galaxies with overlapping images offers a direct way to probe the distribution of dust extinction and its effects on the background light. We present a catalog of 1990 such galaxy pairs selected from the Sloan Digital Sky Survey (SDSS) by volunteers of the Galaxy Zoo project. We highlight subsamples which are particularly useful for retrieving such properties of the dust distribution as UV extinction, the extent perpendicular to the disk plane, and extinction in the inner parts of disks. The sample spans wide ranges of morphology and surface brightness, opening up the possibility of using this technique to address systematic changes in dust extinction or distribution with galaxy type. This sample will form the basis for forthcoming work on the ranges of dust distributions in local disk galaxies, both for their astrophysical implications and as the low-redshift part of a study of the evolution of dust properties. Separate lists and figures show deep overlaps, where the inner regions of the foreground galaxy are backlit, and the relatively small number of previously-known overlapping pairs outside the SDSS DR7 sky coverage.
- 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.
- 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/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/MNRAS/403/683
- Title:
- GALEX Arecibo SDSS survey (GASS)
- Short Name:
- J/MNRAS/403/683
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We introduce the GALEX Arecibo SDSS Survey (GASS), an on-going large programme that is gathering high quality HI-line spectra using the Arecibo radio telescope for an unbiased sample of ~1000 galaxies with stellar masses greater than 10^10^M_{sun}_ and redshifts 0.025<z<0.05, selected from the Sloan Digital Sky Survey (SDSS) spectroscopic and Galaxy Evolution Explorer (GALEX) imaging surveys. The galaxies are observed until detected or until a low gas mass fraction limit (1.5-5 per cent) is reached. This paper presents the first Data Release, consisting of ~20 per cent of the final GASS sample. We use this data set to explore the main scaling relations of the HI gas fraction with galaxy structure and NUV-r colour.
- ID:
- ivo://CDS.VizieR/J/A+A/544/A65
- Title:
- GALEX Arecibo SDSS survey. VI.
- Short Name:
- J/A+A/544/A65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the second data release from the GALEX Arecibo SDSS Survey (GASS), an ongoing large Arecibo program to measure the HI properties for an unbiased sample of ~1000 galaxies with stellar masses greater than 10^10^M_{sun}_ and redshifts 0.025<z<0.05. GASS targets are selected from the Sloan Digital Sky Survey (SDSS) spectroscopic and Galaxy Evolution Explorer (GALEX) imaging surveys, and are observed until detected or until a gas mass fraction limit of a few per cent is reached. This second data installment includes new Arecibo observations of 240 galaxies, and marks the 50% of the complete survey. We present catalogs of the HI, optical and ultraviolet parameters for these galaxies, and their HI-line profiles. Having more than doubled the size of the sample since the first data release, we also revisit the main scaling relations of the HI mass fraction with galaxy stellar mass, stellar mass surface density, concentration index, and NUV-r color, as well as the gas fraction plane introduced in our earlier work.