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3381. Spectroscopic analysis of EDisCS clusters
ID:
ivo://CDS.VizieR/J/ApJ/850/181
Title:
Spectroscopic analysis of EDisCS clusters
Short Name:
J/ApJ/850/181
Date:
21 Oct 2021
Publisher:
CDS
Description:
A major question in galaxy formation is how the gas supply that fuels activity in galaxies is modulated by their environment. We use spectroscopy of a set of well-characterized clusters and groups at 0.4<z<0.8 from the ESO Distant Cluster Survey and compare it to identically selected field galaxies. Our spectroscopy allows us to isolate galaxies that are dominated by old stellar populations. Here we study a stellar-mass-limited sample (log(M*/M_{sun}_)>10.4) of these old galaxies with weak [OII] emission. We use line ratios and compare to studies of local early-type galaxies to conclude that this gas is likely excited by post-AGB stars and hence represents a diffuse gas component in the galaxies. For cluster and group galaxies the fraction with EW([OII])>5{AA} is f[OII]=0.08_-0.02_^+0.03^ and f[OII]=0.06_-0.04_^+0.07^, respectively. For field galaxies we find f[OII]=0.27_-0.06_^+0.07^, representing a 2.8{sigma} difference between the [OII] fractions for old galaxies between the different environments. We conclude that a population of old galaxies in all environments has ionized gas that likely stems from stellar mass loss. In the field galaxies also experience gas accretion from the cosmic web, and in groups and clusters these galaxies have had their gas accretion shut off by their environment. Additionally, galaxies with emission preferentially avoid the virialized region of the cluster in position-velocity space. We discuss the implications of our results, among which is that gas accretion shutoff is likely effective at group halo masses (logM/M_{sun}_>12.8) and that there are likely multiple gas removal processes happening in dense environments.
3382. Spectroscopic analysis of Tuc III stream
ID:
ivo://CDS.VizieR/J/ApJ/866/22
Title:
Spectroscopic analysis of Tuc III stream
Short Name:
J/ApJ/866/22
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a spectroscopic study of the tidal tails and core of the Milky Way satellite Tucana III, collectively referred to as the Tucana III stream, using the 2dF+AAOmega spectrograph on the Anglo-Australian Telescope and the IMACS spectrograph on the Magellan Baade Telescope. In addition to recovering the brightest nine previously known member stars in the Tucana III core, we identify 22 members in the tidal tails. We observe strong evidence for a velocity gradient of 8.0+/-0.4km/s/deg over at least 3{deg} on the sky. Based on the continuity in velocity, we confirm that the Tucana III tails are real tidal extensions of Tucana III. The large velocity gradient of the stream implies that Tucana III is likely on a radial orbit. We successfully obtain metallicities for four members in the core and 12 members in the tails. We find that members close to the ends of the stream tend to be more metal-poor than members in the core, indicating a possible metallicity gradient between the center of the progenitor halo and its edge. The spread in metallicity suggests that the progenitor of the Tucana III stream is likely a dwarf galaxy rather than a star cluster. Furthermore, we find that with the precise photometry of the Dark Energy Survey data, there is a discernible color offset between metal-rich disk stars and metal-poor stream members. This metallicity-dependent color offers a more efficient method to recognize metal-poor targets and will increase the selection efficiency of stream members for future spectroscopic follow-up programs on stellar streams.
3383. Spectroscopic and photometric redshifts
ID:
ivo://CDS.VizieR/J/ApJS/135/41
Title:
Spectroscopic and photometric redshifts
Short Name:
J/ApJS/135/41
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a comparison between the catalog of spectroscopic redshifts in the Hubble Deep Field (HDF) recently published by Cohen and collaborators (2000, cat. <J/ApJ/538/29>) and the redshifts that our group (Fernandez-Soto et al., 1999, Cat. <J/ApJ/513/34>) has measured for the same objects using photometric techniques. This comparison is performed in order to fully characterize the errors associated with the photometric redshift technique. The compilation of spectroscopic redshifts incorporates previously published results, corrections to previously published wrong values, and new data, and it includes over 140 objects in the HDF proper. It represents the deepest, cleanest, most complete spectroscopic catalog ever compiled.
3384. Spectroscopic catalog of 10 rich galaxy clusters
ID:
ivo://CDS.VizieR/J/ApJS/122/51
Title:
Spectroscopic catalog of 10 rich galaxy clusters
Short Name:
J/ApJS/122/51
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present spectroscopic observations of galaxies in the fields of 10 distant clusters for which we have previously presented deep imaging with WFPC2 on board the Hubble Space Telescope. The clusters span the redshift range z=0.37-0.56 and are the subject of a detailed ground- and space-based study to investigate the evolution of galaxies as a function of environment and epoch. The data presented here include positions, photometry, redshifts, spectral line strengths, and classifications for 657 galaxies in the fields of the 10 clusters. The catalog is composed of 424 cluster members across the 10 clusters and 233 field galaxies, with detailed morphological information from our WFPC2 images for 204 of the cluster galaxies and 71 in the field. We illustrate some basic properties of the catalog, including correlations between the morphological and spectral properties of our large sample of cluster galaxies. A direct comparison of the spectral properties of the high-redshift cluster and field populations suggests that the phenomenon of strong Balmer lines in otherwise passive galaxies (commonly called E + A but renamed here as the k + a class) shows an order-of-magnitude increase in the rich cluster environment compared with a more modest increase in the field population. This suggests that the process or processes involved in producing k + a galaxies are either substantially more effective in the cluster environment or that this environment prolongs the visibility of this phase. A more detailed analysis and modeling of these data is presented in Poggianti et al. (1999ApJ...518..576P).
3385. Spectroscopic members of COSMOS X-ray systems
ID:
ivo://CDS.VizieR/J/ApJ/880/142
Title:
Spectroscopic members of COSMOS X-ray systems
Short Name:
J/ApJ/880/142
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate spectroscopic properties of galaxy systems identified based on deep X-ray observations in the Cosmic Evolution Survey (COSMOS) field. The COSMOS X-ray system catalog we use includes 180 X-ray systems to a limiting flux of 1.0x10^-15^erg/cm^2^/s, an order of magnitude deeper than the future e-ROSITA survey. We identify spectroscopic members of these X-ray systems based on the spectroscopic catalog constructed by compiling various spectroscopic surveys including 277 new measurements; 146 X-ray systems are spectroscopically identified groups with more than three spectroscopic members. We identify 2196 spectroscopic redshifts of member candidates in these X-ray systems. The X-ray luminosity (L_X_)-velocity dispersion ({sigma}_v_) scaling relation of the COSMOS X-ray systems is consistent with that of massive X-ray clusters. One of the distinctive features of the COSMOS survey is that it covers the X-ray luminosity range where poor groups overlap the range for extended emission associated with individual quiescent galaxies. We assess the challenges posed by the complex morphology of the distribution of systems with low X-ray luminosity, including groups and individual quiescent galaxies, in the L_x_-{sigma}_v_ plane.
3386. Spectroscopic members of Segue 2 galaxy
ID:
ivo://CDS.VizieR/J/ApJ/770/16
Title:
Spectroscopic members of Segue 2 galaxy
Short Name:
J/ApJ/770/16
Date:
21 Oct 2021
Publisher:
CDS
Description:
Segue 2, discovered by Belokurov et al. (2009, Cat. J/MNRAS/397/1748), is a galaxy with a luminosity of only 900L_{sun}_. We present Keck/DEIMOS spectroscopy of 25 members of Segue 2 - a threefold increase in spectroscopic sample size. The velocity dispersion is too small to be measured with our data. The upper limit with 90% (95%) confidence is {sigma}_v_<2.2(2.6)km/s, the most stringent limit for any galaxy. The corresponding limit on the mass within the three-dimensional half-light radius (46pc) is M_1/2_<1.5(2.1)x10^5^M_{sun}_. Segue 2 is the least massive galaxy known. We identify Segue 2 as a galaxy rather than a star cluster based on the wide dispersion in [Fe/H] (from -2.85 to -1.33) among the member stars. The stars' [{alpha}/Fe] ratios decline with increasing [Fe/H], indicating that Segue 2 retained Type Ia supernova ejecta despite its presently small mass and that star formation lasted for at least 100 Myr. The mean metallicity, <[Fe/H]>=-2.22+/-0.13 (about the same as the Ursa Minor galaxy, 330 times more luminous than Segue 2), is higher than expected from the luminosity-metallicity relation defined by more luminous dwarf galaxy satellites of the Milky Way. Segue 2 may be the barest remnant of a tidally stripped, Ursa Minor-sized galaxy. If so, it is the best example of an ultra-faint dwarf galaxy that came to be ultra-faint through tidal stripping. Alternatively, Segue 2 could have been born in a very low mass dark matter subhalo (v_max_<10km/s), below the atomic hydrogen cooling limit.
3387. Spectroscopic observations in VV124 (UGC 4879)
ID:
ivo://CDS.VizieR/J/ApJ/751/46
Title:
Spectroscopic observations in VV124 (UGC 4879)
Short Name:
J/ApJ/751/46
Date:
21 Oct 2021
Publisher:
CDS
Description:
VV124 (UGC 4879) is an isolated, dwarf irregular/dwarf spheroidal (dIrr/dSph) transition-type galaxy at a distance of 1.36 Mpc. Previous low-resolution spectroscopy yielded inconsistent radial velocities for different components of the galaxy, and photometry hinted at the presence of a stellar disk. In order to quantify the stellar dynamics, we observed individual red giants in VV124 with the Keck/Deep Extragalactic Imaging Multi-Object Spectrograph (DEIMOS). We validated members based on their positions in the color-magnitude diagram, radial velocities, and spectral features. Our sample contains 67 members. The average radial velocity is <v_r_>=-29.1+/-1.3km/s in agreement with the previous radio measurements of H I gas. The velocity distribution is Gaussian, indicating that VV124 is supported primarily by velocity dispersion inside a radius of 1.5 kpc. Outside that radius, our measurements provide only an upper limit of 8.6km/s on any rotation in the photometric disk-like feature. The velocity dispersion is {sigma}_v_=9.4+/-1.0km/s, from which we inferred a mass of M_1/2_=(2.1 +/-0.2)x10^7^M_{sun}_ and a mass-to-light ratio of (M/L_V_)_1/2_=5.2+/-1.1M_{sun}_/L_{sun}_, both measured within the half-light radius. Thus, VV124 contains dark matter. We also measured the metallicity distribution from neutral iron lines. The average metallicity, <[Fe/H]>=-1.14+/-0.06, is consistent with the mass-metallicity relation defined by dSph galaxies. The dynamics and metallicity distribution of VV124 appear similar to dSphs of similar stellar mass.
3388. Spectroscopic observations of globular clusters
ID:
ivo://CDS.VizieR/J/MNRAS/405/839
Title:
Spectroscopic observations of globular clusters
Short Name:
J/MNRAS/405/839
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of medium-resolution spectroscopy of 28 globular clusters (GCs) in six nearby galaxies of different luminosities and morphological types, situated in M33 (15 objects), M31 (three), IC10 (four), UGCA86 (four), Holmberg IX (one) and DDO71 (one) obtained at the Special Astrophysical Observatory 6-m telescope. Measurements of Lick absorption line indices and comparison with Simple Stellar Population models enabled us to obtain their spectroscopic ages, metallicities and {alpha}-element to Fe abundance ratios.
3389. Spectroscopic obs & members of ZwCl 2341+0000
ID:
ivo://CDS.VizieR/J/ApJ/841/7
Title:
Spectroscopic obs & members of ZwCl 2341+0000
Short Name:
J/ApJ/841/7
Date:
21 Oct 2021
Publisher:
CDS
Description:
ZwCl 2341.1+0000, a merging galaxy cluster with disturbed X-ray morphology and widely separated (~3Mpc) double radio relics, was thought to be an extremely massive (10-30x10^14^M_{sun}_) and complex system, with little known about its merger history. We present JVLA 2-4GHz observations of the cluster, along with new spectroscopy from our Keck/DEIMOS survey, and apply Gaussian Mixture Modeling to the three-dimensional distribution of 227 confirmed cluster galaxies. After adopting the Bayesian Information Criterion to avoid overfitting, which we discover can bias high the total dynamical mass estimates, we find that a three-substructure model with a total dynamical mass estimate of 9.39+/-0.81x10^14^M_{sun}_ is favored. We also present deep Subaru imaging and perform the first weak lensing analysis on this system, obtaining a weak lensing mass estimate of 5.57+/-2.47x10^14^M_{sun}_. This is a more robust estimate because it does not depend on the dynamical state of the system, which is disturbed due to the merger. Our results indicate that ZwCl2341.1+0000 is a multiple merger system comprised of at least three substructures, with the main merger that produced the radio relics occurring near the plane of the sky, and a younger merger in the north occurring closer to the line of sight. Dynamical modeling of the main merger reproduces observed quantities (relic positions and polarizations, subcluster separation and radial velocity difference), if the merger axis angle of ~10_-6_^+34^ degrees and the collision speed at pericenter is ~1900_-200_^+300^km/s.
3390. Spectroscopic obs. of 3 spiral galaxies
ID:
ivo://CDS.VizieR/J/MNRAS/412/1741
Title:
Spectroscopic obs. of 3 spiral galaxies
Short Name:
J/MNRAS/412/1741
Date:
21 Oct 2021
Publisher:
CDS
Description:
The correlation between the breaks in the metallicity distribution and the corotation radius of spiral galaxies has been already advocated in the past and is predicted by a chemodynamical model of our Galaxy that effectively introduces the role of spiral arms in the star formation rate. In this work, we present photometric and spectroscopic observations made with the Gemini Telescope for three of the best candidates of spiral galaxies to have the corotation inside the optical disc: IC 0167, NGC 1042 and NGC 6907. We observed the most intense and well-distributed HII regions of these galaxies, deriving reliable galactocentric distances and oxygen abundances by applying different statistical methods. From these results, we confirm the presence of variations in the gradients of metallicity of these galaxies that are possibly correlated with the corotation resonance.

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