- ID:
- ivo://CDS.VizieR/J/ApJ/799/205
- Title:
- [OII] emitting galaxies in the HETDEX survey
- Short Name:
- J/ApJ/799/205
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) pilot survey identified 284 [OII]{lambda}3727 emitting galaxies in a 169arcmin^2^ field of sky in the redshift range 0<z<0.57. This line flux limited sample provides a bridge between studies in the local universe and higher-redshift [OII] surveys. We present an analysis of the star formation rates (SFRs) of these galaxies as a function of stellar mass as determined via spectral energy distribution fitting. The [OII] emitters fall on the "main sequence" of star-forming galaxies with SFR decreasing at lower masses and redshifts. However, the slope of our relation is flatter than that found for most other samples, a result of the metallicity dependence of the [OII] star formation rate indicator. The mass-specific SFR is higher for lower mass objects, supporting the idea that massive galaxies formed more quickly and efficiently than their lower mass counterparts. This is confirmed by the fact that the equivalent widths of the [OII] emission lines trend smaller with larger stellar mass. Examination of the morphologies of the [OII] emitters reveals that their star formation is not a result of mergers, and the galaxies' half-light radii do not indicate evolution of physical sizes.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/575/A40
- Title:
- [OII] luminosity function
- Short Name:
- J/A+A/575/A40
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the [OII] luminosity function measured in the redshift range 0.1<z<1.65 with unprecedented depth and accuracy. Our measurements are based on medium resolution flux-calibrated spectra of emission line galaxies with the FORS2 instrument at VLT and with the SDSS-III/BOSS spectrograph. The FORS2 spectra and the corresponding catalog containing redshifts and line fluxes are released along with this paper. In this work we use a novel method to combine the aforementioned surveys with GAMA, zCOSMOS and VVDS, which have different target selection, producing a consistent weighting scheme to derive the [OII] luminosity function. The measured luminosity function is in good agreement with previous independent estimates. The comparison with two state-of-the-art semi-analytical models is good, which is encouraging for the production of mock catalogs of [OII] flux limited surveys. We observe the bright end evolution over 8.5Gyr: we measure the decrease of logL* from 42.4erg/s at redshift 1.44 to 41.2 at redshift 0.165 and we find that the faint end slope flattens when redshift decreases. This measurement confirms the feasibility of the target selection of future baryonic acoustic oscillation surveys aiming at observing [OII] flux limited samples.
- ID:
- ivo://CDS.VizieR/J/ApJ/634/861
- Title:
- Old passively evolving galaxies at z=1
- Short Name:
- J/ApJ/634/861
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We obtained the number counts and the rest-frame B-band luminosity function of color-selected old passively evolving galaxies (OPEGs) at z=1 with very high statistical accuracy using a large and homogeneous sample of about 4000 such objects with z'<25 detected in an area of 1.03deg^2^ in the Subaru/XMM-Newton Deep Survey (SXDS) field. Our selection criteria are defined on the i'-z' and R-z' color-magnitude plane so that OPEGs at z=0.9-1.1 with formation redshift z_f_=2-10 are properly sampled with minimum contamination by other populations. The limiting magnitude corresponds to the luminosity of galaxies with M*+3 at z=0 (where M* is the characteristic absolute magnitude of the Schechter galaxy luminosity function). We made pilot redshift observations for 99 OPEG candidates with 19<z'<22 and found that at least 78% (73 of 93) of the entire sample, or 95% (73 of 77) of those whose redshifts were obtained, indeed lie between z=0.87 and 1.12, and most of their spectra show a continuum break and strong Ca H and K lines, indicating that these objects are indeed dominated by the old stellar populations.
- ID:
- ivo://CDS.VizieR/J/A+A/599/A81
- Title:
- OmegaWINGS local clusters of galaxies redshifts
- Short Name:
- J/A+A/599/A81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the spectroscopic follow-up of the OmegaWINGS photometric survey, aimed at covering the outskirts of a subset of the original WINGS cluster sample. We observed 33 of the 46 clusters of galaxies observed with VST over 1 square degree. The aim of this spectroscopic survey is to enlarge the number of cluster members and study the galaxy characteristics and the cluster dynamical properties out to large radii, reaching the virial radius and beyond. We used the AAOmega spectrograph at AAT to obtain fiber-integrated spectra covering the wavelength region between 3800 and 9000{AA} with a spectral resolution of 3.5-6{AA} full width at half maximum (FWHM). We present here the redshift measurements for 17985 galaxies, 7497 of which turned out to be cluster members.
- ID:
- ivo://CDS.VizieR/J/ApJS/254/30
- Title:
- One-side head-tail (OHT) galaxies from FIRST & SDSS
- Short Name:
- J/ApJS/254/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- One-side head-tail (OHT) galaxies are radio galaxies with a peculiar shape. They usually appear in galaxy clusters, but they have never been cataloged systematically. We design an automatic procedure to search for them in the Faint Images of the Radio Sky at Twenty-Centimeters source catalog and compile a sample with 115 HT candidates. After cross-checking with the Sloan Digital Sky Survey photometric data and catalogs of galaxy clusters, we find that 69 of them are possible OHT galaxies. Most of them are close to the center of galaxy clusters. The lengths of their tails do not correlate with the projection distance to the center of the nearest galaxy clusters, but show weak anticorrelation with the cluster richness, and are inversely proportional to the radial velocity differences between clusters and host galaxies. Our catalog provides a unique sample to study this special type of radio galaxies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/481/2458
- Title:
- On the nature of small galaxy systems
- Short Name:
- J/MNRAS/481/2458
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim at defining homogeneous selection criteria of small galaxy systems in order to build catalogues suitable to compare main properties of pairs, triplets, and groups with four or more members. To this end we use spectroscopic and photometric Sloan Digital Sky Survey (SDSS) data to identify systems with a low number of members. We study global properties of these systems and the properties of their member galaxies finding that galaxies in groups are systematically redder and with lower star formation activity indicators than galaxies in pairs which have a higher fraction of star-forming galaxies. Triplet galaxies present intermediate trends between pairs and groups. We also find an enhancement of star formation activity for galaxies in small systems with companions closer than 100kpc, irrespective of the number of members. We have tested these analyses on SDSS mock catalogues derived from the Millennium simulation, finding as conservative thresholds 76 per cent completeness and a contamination of 23 per cent in small galaxy systems, when considering an extreme case of incompleteness due to fiber collisions. Nevertheless, we also found that the results obtained are not likely affected by projection effects. Our studies suggest that an extra galaxy in a system modify the properties of the member galaxies. In pairs, galaxy-galaxy interactions increase gas density and trigger starbursts. However, repeated interactions in triplets and groups can generate gas stripping, turbulence, and shocks quenching the star formation in these systems.
- ID:
- ivo://CDS.VizieR/J/A+A/583/A124
- Title:
- Ophiuchus r'g'z' photometry and redshifts
- Short Name:
- J/A+A/583/A124
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Ophiuchus cluster, at a redshift z=0.0296, is known from X-rays to be one of the most massive nearby clusters, but due to its very low Galactic latitude its optical properties have not been investigated in detail. Aims. We discuss the optical properties of the galaxies in the Ophiuchus cluster, in particular with the aim of understanding better its dynamical properties. We have obtained deep optical imaging in several bands with various telescopes, and applied a sophisticated method to model and subtract the contributions of stars in order to measure galaxy magnitudes as accurately as possible. The colour-magnitude relations obtained show that there are hardly any blue galaxies in Ophiuchus (at least brighter than r'<=19.5), and this is confirmed by the fact that we only detect two galaxies in H{alpha}. We also obtained a number of spectra with ESO-FORS2, that we combined with previously available redshifts. Altogether, we have 152 galaxies with spectroscopic redshifts in the 0.02<=z<=0.04 range, and 89 galaxies with both a redshift within the cluster redshift range and a measured r' band magnitude (limited to the Megacam 1x1deg^2^ field).
- ID:
- ivo://CDS.VizieR/J/ApJ/884/L55
- Title:
- Opt. follow-up of galaxies within S190814bv region
- Short Name:
- J/ApJ/884/L55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- On 2019 August 14 the Laser Interferometer Gravitational Wave Observatory (LIGO) and the Virgo gravitational wave interferometer announced the detection of a binary merger, S190814bv, with a low false alarm rate of about 1 in 1.6x10^25^yr, a distance of 267+/-52Mpc, a 90% (50%) localization region of about 23 (5) deg^2^, and a probability of being a neutron star-black hole (NS-BH) merger of >99%. The LIGO/Virgo Collaboration (LVC) defines NS-BH such that the lighter binary member has a mass of <3M_{sun}_ and the more massive one has >5M_{sun}_, and this classification is in principle consistent with a BH-BH merger depending on the actual upper mass cutoff for neutron stars. Additionally, the LVC designated a probability that the merger led to matter outside the final BH remnant of <1%, suggesting that an electromagnetic (EM) counterpart is unlikely. Here we report our optical follow-up observations of S190814bv using the Magellan Baade 6.5m telescope to target all 96 galaxies in the Galaxy List for the Advanced Detector Era catalog within the 50% localization volume (representing about 70% of the integrated luminosity within this region). No counterpart was identified to a median 3{sigma} limiting magnitude of i=22.2 (M_i_~-14.9mag), comparable to the brightness of the optical counterpart of the binary neutron star merger GW170817 at the distance of S190814bv; similarly, we can rule out an on-axis jet typical of short GRBs. However, we cannot rule out other realistic models, such as a kilonova with only ~0.01M_{sun}_ of lanthanide-rich material, or an off-axis jet with a viewing angle of {theta}_obs_>~15{deg}.
- ID:
- ivo://CDS.VizieR/J/AJ/144/16
- Title:
- Optical and HI properties of galaxies in voids
- Short Name:
- J/AJ/144/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have carefully selected a sample of 60 galaxies that reside in the deepest underdensities of geometrically identified voids within the Sloan Digital Sky Survey. HI imaging of 55 galaxies with the Westerbork Synthesis Radio Telescope reveals morphological and kinematic signatures of ongoing interactions and gas accretion. We probe a total volume of 485Mpc^3^ within the voids, with an angular resolution of 8kpc at an average distance of 85Mpc. We reach column density sensitivities of 5x10^19^/cm^-2^, corresponding to an HI mass limit of 3x10^8^M_{sun}_. We detect HI in 41 galaxies, with total masses ranging from 1.7x10^8^ to 5.5x10^9^M_{sun}_. The upper limits on the 14 non-detections are not inconsistent with their luminosities, given their expected HI mass-to-light ratios. We find that the void galaxies are generally gas-rich, low-luminosity, blue disk galaxies, with optical and HI properties that are not unusual for their luminosity and morphology. The sample spans a range of absolute magnitudes (-16.1>M_r_>-20.4) and colors (0.06<g-r<0.87), and includes disk and irregular galaxies. We also identify three as early-type galaxies, all of which are not detected in HI. All galaxies have stellar masses less than 3x10^10^M_{sun}_, and many have kinematic and morphological signs of ongoing gas accretion, suggesting that the void galaxy population is still in the process of assembling. The small-scale clustering in the void, within 600kpc and 200km/s, is similar to that in higher density regions, and we identify 18 HI-rich neighboring galaxies in the voids. Most are within 100kpc and 100km/s of the targeted galaxy, and we find no significant population of HI-rich low-luminosity galaxies filling the voids, contrary to what is predicted by simulations.
- ID:
- ivo://CDS.VizieR/J/AJ/126/119
- Title:
- Optical and radio data for rich Abell clusters
- Short Name:
- J/AJ/126/119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical observations and radio continuum imaging data for a sample of rich, X-ray-bright Abell clusters at intermediate (z~0.2) redshifts. We find that the radio galaxy population varies substantially from cluster to cluster within this homogeneous sample. The spatial distribution of the high-luminosity radio galaxies (HLRGs; L1.4>10^23^W/Hz) is very different from the low-luminosity radio galaxies (LLRGs; L1.4<=10^22.75^W/Hz), with the LLRGs displaying a flat spatial distribution in contrast to the centrally peaked HLRGs. A color-morphology classification shows that the HLRGs are composed primarily of galaxies with old stellar populations, whereas the LLRGs have a much more diverse composition. We do not see a correlation between the cluster radio fraction and cluster blue fraction. However, there is a moderate anticorrelation with richness, suggesting that a rich cluster is less likely to have radio-bright galaxies, whether the radio emission is due to active galactic nuclei or star formation.
