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- ID:
- ivo://CDS.VizieR/J/MNRAS/456/3899
- Title:
- Red galaxies with pseudo-bulges in the SDSS
- Short Name:
- J/MNRAS/456/3899
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Pseudo-bulges are expected to markedly differ from classical quasi-monolithically forming bulges in their star formation history (SFH) and chemical abundance patterns. To test this simple expectation, we carry out a comparative structural and spectral synthesis analysis of 10^6^ red massive galaxies issued from the Sloan Digital Sky Survey (SDSS), sub-divided into bulgeless, pseudo-bulge and classical bulge galaxies according to their photometric characteristics, and further obeying a specific selection to minimize uncertainties in the analysis and ensure an unbiased derivation and comparison of SFHs. Our 2D photometry analysis suggests that discs underlying pseudo-bulges typically have larger exponential scalelengths than bulgeless galaxies, despite similar integral disc luminosities. Spectral synthesis models of the stellar emission within the 3-arcsec SDSS fibre aperture reveal a clear segregation of bulgeless and pseudo-bulge galaxies from classical bulges on the luminosity-weighted planes of age-metallicity and mass-metallicity, though a large dispersion is observed within the two former classes. The secular growth of pseudo-bulges is also reflected upon their cumulative stellar mass as a function of time, which is shallower than that for classical bulges. Such results suggest that the centres of bulgeless and pseudo-bulge galaxies substantially differ from those of bulgy galaxies with respect to their SFH and chemical enrichment history, which likely points to different formation/assembly mechanisms.
- ID:
- ivo://CDS.VizieR/J/A+A/558/A68
- Title:
- Red nuclear spectra of 376 local galaxies
- Short Name:
- J/A+A/558/A68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We obtained long-slit optical spectra of the nuclear regions of 376 galaxies in the local Universe using the 1.5m Cassini telescope of Bologna Observatory. Of these spectra, 164 were either never taken before by the Sloan Digital Sky Survey (SDSS), or given by the Nasa Extragalactic Database (NED). With these new spectra, we contribute investigating the occurrence of active galactic nuclei (AGNs). Nevertheless, we stress that the present sample is by no means complete, thus, it cannot be used to perform any demographic study. Following the method used in a previous work, we classify the nuclear spectra using a six bin scheme: SEY (Seyfert), sAGN (strong AGN), and wAGN (weak AGN) represent active galactic nuclei of different levels of activity; HII accounts for star-forming nuclei; RET (retired) and PAS (passive) refer to nuclei with poor or no star-formation activity. The spectral classification is performed using the ratio of 6584[NII] to H{alpha} lines and the equivalent width (EW) of H{alpha} versus [NII]/H{alpha} (WHAN diagnostic introduced by Cid Fernandes and collaborators) after correcting H{alpha} for underlying absorption.
- ID:
- ivo://CDS.VizieR/J/A+A/617/A53
- Title:
- Red-sequence early-type galaxies. II.
- Short Name:
- J/A+A/617/A53
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This work aims to observationally investigate the history of size growth of early-type galaxies and how the growth depends on cosmic epoch and the mass of the halo in which they are embedded. We carried out a photometric and structural analysis in the rest-frame V band of a mass-selected (logM/M_{sun}_>10.7) sample of red-sequence early-type galaxies with spectroscopic/grism redshift in the general field up to z=2 to complement a previous work presenting an identical analysis but in halos 100 times more massive and 1000 times denser. We homogeneously derived sizes (effective radii) fully accounting for the multi-component nature of galaxies and the common presence of isophote twists and ellipticity gradients. By using these mass-selected samples, composed of 170 red-sequence early-type galaxies in the general field and 224 identically selected and analyzed in clusters, we isolate the effect on galaxy sizes of the halo in which galaxies are embedded and its dependence on epoch. We find that the log of the galaxy size at a fixed stellar mass, log M/M_{sun}_=11, has increased with epoch at a rate twice as fast in the field than in cluster in the last 10Gyr (0.26+/-0.03 versus 0.13+/-0.02dex per unit redshift). Red-sequence early-type galaxies in the general field reached the size of their cousins in denser environment by z=0.25+/-0.13 in spite of being three times smaller at z~2. Data point toward a model where size growth is epoch-independent (i.e., {\partial}logre/{\partial}z=c), but with a rate c depending on environment, {\partial}c/{\partial}logM_halo_~=0.05. Environment determines the growth rate (dlogre/dz) at all redshifts, indicating an external origin for the galaxy growth without any clear epoch where it ceases to have an effect. The larger size of early-type galaxies in massive halos at high redshift indicates that their size grew buildup earlier (at z>2) at an accelerated rate, slowing down at some still unidentified z>2 redshift. Instead, the size growth rate of red-sequence early-type galaxies in low-mass halos is reversed: it proceeds at an increased rate at late epochs after an early period (z>2) of reduced growth, in agreement with the qualitative hierarchical picture of galaxy evolution. We found similar values of scatter around the mass-size relation independently of environment and epoch, indicating that the amount of dissipation in the system forming the observed galaxy does not vary greatly with epoch or environment.
- ID:
- ivo://CDS.VizieR/J/A+A/490/945
- Title:
- Redshifs of galaxies in 23 EIS fields
- Short Name:
- J/A+A/490/945
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have carried out a spectroscopic survey of low-redshift galaxy systems identified by the matched-filter technique in a moderately deep I-band survey. We present new redshifts for 747 galaxies in 23 ESO Imaging Survey (EIS) cluster fields. We use the "gap"-technique to search for significant overdensities in redshift space for identifying groups/clusters of galaxies corresponding to the original EIS matched-filter cluster candidates. In this way we spectroscopically confirm systems in 10 of the 23 cluster candidate fields with a matched-filter estimated redshift z_MF_=0.3-0.4 and with spectroscopic redshifts in the range from z=0.158 to z=0.534, with the observations favouring the confirmation of systems at the lower redshift end. After careful analysis of the redshift distribution, one system was split into two very close clumps in redshift space. We find that the systems identified in the present paper span a broad range of velocity dispersion and richness. The measured one-dimensional velocity dispersion range from 175km/s to 497km/s, consistent with the values obtained in previous papers using much larger samples for systems over the same redshift range. Both undersampling and contamination by substructures contribute to the uncertainty of these measurements. The richness range corresponds to clusters with an estimated total luminosity in the range 12L^*^-65L^*^, but these estimates are very uncertain as are their relation to the velocity dispersion (mass) of the systems. From the analysis of the colours of the galaxy populations we find that ~60% of the spectroscopically confirmed systems have a "significant" red sequence. We find that the colour of the red sequence galaxies matches passive stellar evolution predictions. With this paper we complete our spectroscopic survey of the fields of 58 EIS cluster candidates with estimated redshifts z<=0.4 (see also Hansen et al., 2002, Cat. <J/A+A/388/1>; Olsen et al., 2003, Cat. <J/A+A/409/439>, Olsen et al., 2005, Cat. <J/A+A/435/781>). We have measured a total of 1954 galaxy redshifts in the range z=0.0065 to z=0.6706. Of the 58 systems we confirm 42 (~75%) with redshifts between z=0.095 and z=0.534.
- ID:
- ivo://CDS.VizieR/J/AJ/149/178
- Title:
- Redshift catalog of galaxies in GOODS-South field
- Short Name:
- J/AJ/149/178
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We combine Hubble Space Telescope (HST)/Wide Field Camera3 (WFC3) imaging and G141 grism observations from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) and 3D-HST surveys to produce a catalog of grism spectroscopic redshifts for galaxies in the CANDELS/GOODS-South field. The WFC3/G141 grism spectra cover a wavelength range of 1.1{<=}{lambda}{<=}1.7{mu}m with a resolving power of R~130 for point sources, thus providing rest-frame optical spectra for galaxies out to z~3.5. The catalog is selected in the H-band (F160W) and includes both galaxies with and without previously published spectroscopic redshifts. Grism spectra are extracted for all H-band detected galaxies with H<=24 and a CANDELS photometric redshift z_phot_>=0.6. The resulting spectra are visually inspected to identify emission lines, and redshifts are determined using cross-correlation with empirical spectral templates. To establish the accuracy of our redshifts, we compare our results against high-quality spectroscopic redshifts from the literature. Using a sample of 411 control galaxies, this analysis yields a precision of {sigma}_NMAD_=0.0028 for the grism-derived redshifts, which is consistent with the accuracy reported by the 3D-HST team. Our final catalog covers an area of 153arcmin^2^ and contains 1019 redshifts for galaxies in GOODS-S. Roughly 60% (608/1019) of these redshifts are for galaxies with no previously published spectroscopic redshift. These new redshifts span a range of 0.677{<=}z{<=}3.456 and have a median redshift of z=1.282. The catalog contains a total of 234 new redshifts for galaxies at z>1.5. In addition, we present 20 galaxy pair candidates identified for the first time using the grism redshifts in our catalog, including four new galaxy pairs at z~2, nearly doubling the number of such pairs previously identified.
- ID:
- ivo://CDS.VizieR/J/A+A/465/1099
- Title:
- Redshift catalog of 691 objects in CDFS
- Short Name:
- J/A+A/465/1099
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper prepares a series of papers analysing the Intermediate MAss Galaxy Evolution Sequence (IMAGES) up to a redshift of one. Intermediate mass galaxies (M_J<=-20.3) are selected from the Chandra Deep Field South (CDFS) for which we identify a serious lack of spectroscopically determined redshifts. Our primary aim in this study is therefore to obtain a sample of intermediate-mass galaxies with known spectroscopic redshift to be used for further analysis of their 3D-kinematics. We also intend to test whether this important cosmological field may be significantly affected by cosmic variance. The spectroscopic observations were carried out using VIMOS on the ESO VLT. The data reduction was done using a set of semi-automatic IRAF procedures developed by our team. We have spectroscopically identified 691 objects including 580 galaxies, 7 QSOs, and 104 stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/471/L5
- Title:
- Redshift clustering in the Hubble Deep Field
- Short Name:
- J/ApJ/471/L5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present initial results from a redshift survey carried out with the low-resolution imaging spectrograph on the 10m W. M. Keck Telescope in the Hubble Deep Field. In the redshift distribution of the 140 extragalactic objects in this sample, we find six strong peaks with velocity dispersions of ~400km/s. The areal density of objects within a particular peak, while it may be nonuniform, does not show evidence for strong central concentration. These peaks have characteristics (velocity dispersions, density enhancements, spacing, and spatial extent) similar to those seen in a comparable redshift survey in a different high Galactic latitude field (Cohen and coworkers), confirming that the structures are generic. They are probably the high-redshift counterparts of huge galaxy structures ("walls") observed locally.
- ID:
- ivo://CDS.VizieR/J/A+A/638/A27
- Title:
- Redshift database towards Shapley Supercluster
- Short Name:
- J/A+A/638/A27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a database and velocity catalogue towards the region of the Shapley Supercluster based on 18,129 measured velocities for 10,702 galaxies in the approximately 300 square degree area between 12:42:13.219<RA<14:16:59.210 and -38:29:35.70<Dec<-23:28:34.90. The data catalogue contains velocities from the literature found until 2015. It also includes 5,084 velocities, corresponding to 4617 galaxies, observed by us at Las Campanas and CTIO observatories and not reported individually until now. Of these, 2585 correspond to galaxies with no other previously published velocity measurement before 2015. Every galaxy in the velocity database has been identified with a galaxy extracted from the SuperCOSMOS photometric catalogues. We also provide a combined average velocity catalogue for all 10702 galaxies with measured velocities, adopting the SuperCOSMOS positions as a homogeneous base. A general magnitude cut-off at R2=18.0mag was adopted (with exceptions only for some of the new reported velocities). In general terms, we confirm the overall structure of the Shapley Supercluster, as found on earlier papers. However, the more extensive velocity data show finer structure, to be discussed in a future publication.
- ID:
- ivo://CDS.VizieR/J/AJ/130/2439
- Title:
- Redshift estimates in the SDSS DR2
- Short Name:
- J/AJ/130/2439
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have applied ClassX, an oblique decision tree classifier optimized for astronomical analysis, to the homogeneous multicolor imaging database of the Sloan Digital Sky Survey (SDSS), training the software on subsets of SDSS objects whose nature is precisely known via spectroscopy. We find that the software, using photometric data only, correctly classifies a very large fraction of the objects with existing SDSS spectra, both stellar and extragalactic. ClassX also accurately predicts the redshifts of both normal and active galaxies in SDSS. To illustrate ClassX applications in SDSS research, we (1) derive the object content of the SDSS Data Release 2 photometric catalog and (2) provide a sample catalog of resolved SDSS objects that contains a large number of candidate active galactic nucleus (AGN) galaxies (27,000), along with 63,000 candidate normal galaxies at magnitudes substantially fainter than the typical magnitudes of SDSS spectroscopic objects.
