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3341. Spectroscopic survey of WISE-selected sources
ID:
ivo://CDS.VizieR/J/AJ/143/7
Title:
Spectroscopic survey of WISE-selected sources
Short Name:
J/AJ/143/7
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report on the results of an optical spectroscopic survey at high Galactic latitude (|b|>=30{deg}) of a sample of WISE-selected targets, grouped by WISE W1 ({lambda}_eff_=3.4{mu}m) flux, which we use to characterize the sources WISE detected. We observed 762 targets in 10 disjoint fields centered on ultraluminous infrared galaxy candidates using DEIMOS on Keck II. We find 0.30+/-0.02 galaxies arcmin^-2^ with a median redshift of z=0.33+/-0.01 for the sample with W1>=120{mu}Jy. The foreground stellar densities in our survey range from 0.23+/-0.07arcmin^-2^ to 1.1+/-0.1arcmin^-2^ for the same sample. We obtained spectra that produced science grade redshifts for >=90% of our targets for sources with W1 flux >=120{mu}Jy that also had an i-band flux >=18{mu}Jy. We used this for targeting very preliminary data reductions available to the team in 2010 August. Our results therefore present a conservative estimate of what is possible to achieve using WISE's Preliminary Data Release for the study of field galaxies.
3342. Spectroscopy and abundances of SINGS galaxies
ID:
ivo://CDS.VizieR/J/ApJS/190/233
Title:
Spectroscopy and abundances of SINGS galaxies
Short Name:
J/ApJS/190/233
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present intermediate-resolution optical spectrophotometry of 65 galaxies obtained in support of the Spitzer Infrared Nearby Galaxies Survey (SINGS). For each galaxy we obtain a nuclear, circumnuclear, and semi-integrated optical spectrum designed to coincide spatially with mid- and far-infrared spectroscopy from the Spitzer Space Telescope. We make the reduced, spectrophotometrically calibrated one-dimensional spectra, as well as measurements of the fluxes and equivalent widths of the strong nebular emission lines, publically available. We use optical emission-line ratios measured on all three spatial scales to classify the sample into star-forming, active galactic nuclei (AGNs), and galaxies with a mixture of star formation and nuclear activity. We find that the relative fraction of the sample classified as star forming versus AGN is a strong function of the integrated light enclosed by the spectroscopic aperture. We supplement our observations with a large database of nebular emission-line measurements of individual HII regions in the SINGS galaxies culled from the literature. We use these ancillary data to conduct a detailed analysis of the radial abundance gradients and average HII-region abundances of a large fraction of the sample. We combine these results with our new integrated spectra to estimate the central and characteristic (globally averaged) gas-phase oxygen abundances of all 75 SINGS galaxies. We conclude with an in-depth discussion of the absolute uncertainty in the nebular oxygen abundance scale.
3343. Spectroscopy and photometry of z~=5 galaxies
ID:
ivo://CDS.VizieR/J/ApJ/659/84
Title:
Spectroscopy and photometry of z~=5 galaxies
Short Name:
J/ApJ/659/84
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a new measurement of the integrated stellar mass per comoving volume at redshift 5 determined via spectral energy fitting drawn from a sample of 214 photometrically selected galaxies with z'_850LP_<26.5 in the southern GOODS field. Following recent procedures introduced by Eyles et al. (2007MNRAS.374..910E), we estimate stellar masses for various subsamples for which reliable and unconfused Spitzer IRAC detections are available. A spectroscopic sample of 14 of the most luminous sources with z{bar}=4.92 provides a firm lower limit to the stellar mass density of 1x10^6^M_{sun}_/Mpc^3^. We then consider a larger sample whose photometric redshifts in the publicly available GOODS-MUSIC catalog lie in the range 4.4<z<5.6.
3344. Spectroscopy & HST photometry of galaxy Leo V
ID:
ivo://CDS.VizieR/J/ApJ/885/53
Title:
Spectroscopy & HST photometry of galaxy Leo V
Short Name:
J/ApJ/885/53
Date:
16 Mar 2022 09:00:29
Publisher:
CDS
Description:
The ultra-faint dwarf galaxy Leo V has shown both photometric overdensities and kinematic members at large radii, along with a tentative kinematic gradient, suggesting that it may have undergone a close encounter with the Milky Way. We investigate these signs of disruption through a combination of (I) high precision photometry obtained with the Hubble Space Telescope (HST), (II) two epochs of stellar spectra obtained with the Hectochelle Spectrograph on the MMT, and (III) measurements from the Gaia mission. Using the HST data, we examine one of the reported stream-like overdensities at large radii, and conclude that it is not a true stellar stream, but instead a clump of foreground stars and background galaxies. Our spectroscopic analysis shows that one known member star is likely a binary, and challenges the membership status of three others, including two distant candidates that had formerly provided evidence for overall stellar mass loss. We also find evidence that the proposed kinematic gradient across Leo V might be due to small number statistics. We update the systemic proper motion of Leo V, finding ({mu}_{alpha}_/cos{delta},{mu}_{delta}_)= (0.009{+/-}0.560,-0.777{+/-}0 .314)mas/yr, which is consistent with its reported orbit that did not put Leo V at risk of being disturbed by the Milky Way. These findings remove most of the observational clues that suggested Leo V was disrupting; however, we also find new plausible member stars, two of which are located >5 half-light radii from the main body. These stars require further investigation. Therefore, the nature of Leo V still remains an open question.
3345. Spectroscopy in Abell 3921
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.
3346. Spectroscopy in cluster RDCS J1252.9-2927 (z=1.2)
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.
3347. Spectroscopy in Shapley supercluster
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).
3348. Spectroscopy obs. of LeoA, Aqr & Sgr dwarf gal.
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.
3349. Spectroscopy of Abell 222 and Abell 223
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.
3350. Spectroscopy of active galaxies in nearby clusters
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.