- ID:
- ivo://CDS.VizieR/J/A+A/557/A62
- Title:
- Spectroscopy in Abell 3921
- Short Name:
- J/A+A/557/A62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectrophotometric analysis of the galaxy population in the area of the merging cluster Abell 3921 at z=0.093. We investigate the impact of the complex cluster environment on galaxy properties such as morphology or star formation rate. We combine multi-object spectroscopy from the Two Degree Field (2dF) spectrograph with optical imaging taken with the ESO Wide Field Imager. We carry out a redshift analysis and determine cluster velocity dispersions using biweight statistics. Applying a Dressler-Shectman test we seek evidence for cluster substructure. Cluster and field galaxies are investigated with respect to [OII] and H{alpha} equivalent width, star formation rate and morphological descriptors such as concentration index and Gini coefficient. We study these cluster galaxy properties as a function of clustercentric distance and investigate the spatial distribution of various galaxy types. Applying the Dressler-Shectman test we find a third component (A3921-C) in addition to the two main subclusters (A3921-A and A3921-B) already known. The re-determined mass ratio between the main components A and B is ~2:1. Similar to previous studies of galaxy clusters, we find that a large fraction of the disk galaxies close to the cluster core show no detectable star formation. These are likely systems that are quenched due to ram pressure stripping. Interestingly, we also find quenched spirals at rather large distances of 3-4Mpc from the cluster core.
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- ID:
- ivo://CDS.VizieR/J/A+A/507/671
- Title:
- Spectroscopy in cluster RDCS J1252.9-2927 (z=1.2)
- Short Name:
- J/A+A/507/671
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent wide-field imaging observations of the X-ray luminous cluster RDCS J1252.9-2927 at z=1.24 uncovered several galaxy groups that appear to be embedded in filamentary structure extending from the cluster core. We make a spectroscopic study of the galaxies in these groups using GMOS on Gemini-South and FORS2 on VLT with the aim of determining if these galaxies are physically associated to the cluster. We find that three groups contain galaxies at the cluster redshift and that they are probably bound to the cluster. This is the first confirmation of filamentary structure as traced by galaxy groups at z>1. We then use several spectral features in the FORS2 spectra to determine the star formation histories of group galaxies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/381/1035
- Title:
- Spectroscopy in Shapley supercluster
- Short Name:
- J/MNRAS/381/1035
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new optical spectroscopy for 342 R<18 galaxies in the Shapley supercluster (and 198 supplementary galaxies), obtained from 8-h integrations with the AAOmega facility at the Anglo-Australian Telescope. We describe the observations and measurements of central velocity dispersion {sigma}, emission-line equivalent widths and absorption-line indices. The distinguishing characteristic of the survey is its coverage of a very wide baseline in velocity dispersion (90 per cent range {sigma}=40-230km/s), while achieving high signal-to-noise ratio throughout (median 60{AA}^-1^ at 5000{AA}). The data quality will enable estimates of Balmer-line ages to better than 20 per cent precision even for the faintest galaxies in the sample. Significant emission at H{alpha} was detected in ~30 per cent of the supercluster galaxies, including ~20 per cent of red-sequence members. Using line-ratio diagnostics, we find that the emission is LINER (low ionization nuclear emission region) like at high luminosity, but driven by star formation in low-luminosity galaxies. To characterize the absorption lines, we use the classical Lick indices in the spectral range 4000-5200{AA}. We introduce a new method for applying resolution corrections to the line-strength indices. We define a subset of galaxies with very low emission contamination, based on the H{alpha} line, and fit the index relations for this subset. The final sample analysed in this paper comprises 232 NFPS-selected galaxies meeting both the emission and the redshift criteria, of which 198 have measured velocity dispersions (i.e. are not unresolved).
- ID:
- ivo://CDS.VizieR/J/ApJ/834/9
- Title:
- Spectroscopy obs. of LeoA, Aqr & Sgr dwarf gal.
- Short Name:
- J/ApJ/834/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Keck/DEIMOS spectroscopy of individual stars in the relatively isolated Local Group dwarf galaxies Leo A, Aquarius, and the Sagittarius dwarf irregular galaxy. The three galaxies-but especially Leo A and Aquarius-share in common delayed star formation histories (SFHs) relative to many other isolated dwarf galaxies. The stars in all three galaxies are supported by dispersion. We found no evidence of stellar velocity structure, even for Aquarius, which has rotating HI gas. The velocity dispersions indicate that all three galaxies are dark-matter-dominated, with dark-to-baryonic mass ratios ranging from 4.4_-0.8_^+1.0^ (SagDIG) to 9.6_-1.8_^+2.5^ (Aquarius). Leo A and SagDIG have lower stellar metallicities than Aquarius, and they also have higher gas fractions, both of which would be expected if Aquarius were further along in its chemical evolution. The metallicity distribution of Leo A is inconsistent with a closed or leaky box model of chemical evolution, suggesting that the galaxy was pre-enriched or acquired external gas during star formation. The metallicities of stars increased steadily for all three galaxies, but possibly at different rates. The [{alpha}/Fe] ratios at a given [Fe/H] are lower than that of the Sculptor dwarf spheroidal galaxy, which indicates more extended SFHs than Sculptor, consistent with photometrically derived SFHs. Overall, the bulk kinematic and chemical properties for the late-forming dwarf galaxies do not diverge significantly from those of less delayed dwarf galaxies, including dwarf spheroidal galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/394/395
- Title:
- Spectroscopy of Abell 222 and Abell 223
- Short Name:
- J/A+A/394/395
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This spectroscopic study of the neighboring massive clusters Abell 222 and Abell 223 is based on MOS using EMMI at the NTT. Photometry was obtained from WFI images taken with the ESO/MPG 2.2m telescope. Data for objects coincident with objects from Proust et al., 2000A&A...355..443P, is listed for comparison.
- ID:
- ivo://CDS.VizieR/J/AJ/124/2453
- Title:
- Spectroscopy of active galaxies in nearby clusters
- Short Name:
- J/AJ/124/2453
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used optical spectroscopy to investigate the active galaxy populations in a sample of 20 nearby Abell clusters. The targets were identified on the basis of 1.4GHz radio emission, which identifies them as either active galactic nuclei (AGNs) or galaxies forming stars at rates comparable to or greater than that of the Milky Way. The spectra were used to characterize the galaxies via their emission and absorption features.
- ID:
- ivo://CDS.VizieR/J/ApJS/175/462
- Title:
- Spectroscopy of Coma early-type galaxies
- Short Name:
- J/ApJS/175/462
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The long-slit spectra obtained along the minor axis, offset major axis, and diagonal axis are presented for 12 E and S0 galaxies of the Coma Cluster drawn from a magnitude-limited sample studied before. The rotation curves, velocity dispersion profiles, and the H_3_ and H_4_ coefficients of the Hermite decomposition of the line-of-sight velocity distribution are derived. The radial profiles of the H{beta}, Mg, and Fe line strength indices are measured too. In addition, the surface photometry of the central regions of a subsample of four galaxies recently obtained with the Hubble Space Telescope is presented. The data will be used to construct dynamical models of the galaxies and study their stellar populations.
- ID:
- ivo://CDS.VizieR/J/MNRAS/276/1341
- Title:
- Spectroscopy of E and S0 galaxies
- Short Name:
- J/MNRAS/276/1341
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Central velocity dispersions, Mg_2_ line indices, and radial velocities for 220 E and S0 galaxies are derived on basis of intermediate resolution spectroscopy. Galaxies in the following clusters have been observed: Abell 194, Abell 539, Abell 3381, Abell 3574, S639, S753, Doradus, HydraI (Abell 1060), and Grm15. The spectra cover 50 or 100nm centered on the magnesium triplet at 517.7nm. In this catalog we give the mean values of the parameters. The central velocity dispersion and the Mg_2_ line indices have been aperture corrected to a circular aperture with a diameter of 1.19h^-1^kpc, equivalent to 3.4arcsec at the distance of the Coma cluster. Values are also given for a circular aperture with radius equal to the effective radius of the galaxy (cf. Jorgensen et al. 1995, Cat. J/MNRAS/273/1097). The Mg_2_ indices are consistent with the Lick system. The typical uncertainty of the central velocity dispersion is 0.036 in log({sigma}), the typical uncertainty of Mg_2_ is 0.013. Further, literature data (velocity dispersions and Mg_2_ indices) for the clusters A194, DC2345-28 and Coma (A1656) have been brought on a homogeneous system and aperture corrected to the aperture sizes given above. The literature data are from Davies et al. (1987ApJS...64..581D), Dressler (1987ApJ...317....1D), Dressler & Shectman 1988 (J/AJ/95/284), Lucey & Carter (1988MNRAS.235.1177L), Lucey et al. (1991MNRAS.253..584L), and Guzman et al. (1992MNRAS.257..187G).
- ID:
- ivo://CDS.VizieR/J/AJ/146/45
- Title:
- Spectroscopy of 6 early-type galaxies
- Short Name:
- J/AJ/146/45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Adaptive optics assisted SINFONI observations of the central regions of 10 early-type galaxies are presented. Based primarily on the SINFONI kinematics, 10 black hole (BH) masses occupying the high-mass regime of the M_BH_-{sigma} relation are derived using three-integral Schwarzschild models. The effect of dark matter (DM) inclusion on the BH mass is explored. The omission of a DM halo in the model results in a higher stellar mass-to-light ratio, especially when extensive kinematic data are used in the model. However, when the diameter of the sphere of influence--computed using the BH mass derived without a dark halo--is at least 10 times the point-spread function FWHM during the observations, it is safe to exclude a DM component in the dynamical modeling, i.e., the change in BH mass is negligible. When the spatial resolution is marginal, restricting the mass-to-light ratio to the right value returns the correct M_BH_ although a dark halo is not present in the model. Compared to the M_BH_-{sigma} and M_BH_-L relations of McConnell et al., the 10 BHs are all more massive than expected from the luminosities and 7 BH masses are higher than expected from the stellar velocity dispersions of the host bulges. Using new fitted relations, which include the 10 galaxies, we find that the space density of the most massive BHs (M_BH_>~10^9^M_{sun}_) estimated from the M_BH_-L relation is higher than the estimate based on the M_BH_-{sigma} relation and the latter is higher than model predictions based on quasar counts, each by about an order of magnitude.
- ID:
- ivo://CDS.VizieR/J/AJ/116/2738
- Title:
- Spectroscopy of early-type galaxies
- Short Name:
- J/AJ/116/2738
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present central velocity dispersion measurements for 325 early-type galaxies in eight clusters and groups of galaxies, including new observations for 212 galaxies. The clusters and groups are the A262, A1367, Coma (A1656), A2634, Cancer, and Pegasus Clusters and the NGC 383 and NGC 507 Groups. The new measurements were derived from medium-dispersion spectra that cover 600{AA} centered on the Mg I b triplet at {lambda}~5175{AA}. Velocity dispersions were measured using the Tonry & Davis (1979AJ.....84.1511T) cross-correlation method, with a typical accuracy of 6%. A detailed comparison with other data sources is made.
