- ID:
- ivo://CDS.VizieR/J/AJ/154/251
- Title:
- Spectroscopy of galaxies in z=0.2-0.9 clusters
- Short Name:
- J/AJ/154/251
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of stellar populations in passive galaxies in seven massive X-ray clusters at z=0.19-0.89. Based on absorption-line strengths measured from our high signal-to-noise spectra, the data support primarily passive evolution of the galaxies. We use the scaling relations between velocity dispersions and the absorption-line strengths to determine representative mean line strengths for the clusters. From the age determinations based on the line strengths (and stellar population models), we find a formation redshift of z_form_=1.96_-0.19_^+0.24^. Based on line strength measurements from high signal-to-noise composite spectra of our data, we establish the relations between velocity dispersions, ages, metallicities [M/H], and abundance ratios [{alpha}/Fe] as a function of redshift. The [M/H]-velocity dispersion and [{alpha}/Fe]-velocity dispersion relations are steep and tight. The age-velocity dispersion relation is flat, with zero-point changes reflecting passive evolution. The scatter in all three parameters is within 0.08-0.15 dex at fixed velocity dispersions, indicating a large degree of synchronization in the evolution of the galaxies. We find an indication of cluster-to-cluster differences in metallicities and abundance ratios. However, variations in stellar populations with the cluster environment can only account for a very small fraction of the intrinsic scatter in the scaling relations. Thus, within these very massive clusters, the main driver of the properties of the stellar populations in passive galaxies appears to be the galaxy velocity dispersion.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/741/98
- Title:
- Spectroscopy of galaxy clusters to find LCBGs
- Short Name:
- J/ApJ/741/98
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used the DEIMOS spectrograph on the Keck II Telescope to obtain spectra of galaxies in the fields of five distant, rich galaxy clusters over the redshift range 0.5<z<0.9 in a search for luminous compact blue galaxies (LCBGs). Unlike traditional studies of galaxy clusters, we preferentially targeted blue cluster members identified via multi-band photometric pre-selection based on imaging data from the WIYN telescope. Of the 1288 sources that we targeted, we determined secure spectroscopic redshifts for 848 sources, yielding a total success rate of 66%. Our redshift measurements are in good agreement with those previously reported in the literature, except for 11 targets which we believe were previously in error. Within our sample, we confirm the presence of 53 LCBGs in the five galaxy clusters.
- ID:
- ivo://CDS.VizieR/J/ApJ/761/140
- Title:
- Spectroscopy of Herschel-SPIRE galaxies
- Short Name:
- J/ApJ/761/140
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Keck spectroscopic observations and redshifts for a sample of 767 Herschel-SPIRE selected galaxies (HSGs) at 250, 350, and 500{mu}m, taken with the Keck I Low Resolution Imaging Spectrometer and the Keck II DEep Imaging Multi-Object Spectrograph. The redshift distribution of these SPIRE sources from the Herschel Multitiered Extragalactic Survey (HerMES) peaks at z=0.85, with 731 sources at z<2 and a tail of sources out to z~5. We measure more significant disagreement between photometric and spectroscopic redshifts (<{Delta}z/(1+z_spec_)>=0.29) than is seen in non-infrared selected samples, likely due to enhanced star formation rates and dust obscuration in infrared-selected galaxies. The infrared data are used to directly measure integrated infrared luminosities and dust temperatures independent of radio or 24{mu}m flux densities. By probing the dust spectral energy distribution (SED) at its peak, we estimate that the vast majority (72%-83%) of z<2 Herschel-selected galaxies would drop out of traditional submillimeter surveys at 0.85-1mm. This work significantly increased the number of spectroscopically confirmed infrared-luminous galaxies at z{Gt}0 and demonstrates the growing importance of dusty starbursts for galaxy evolution studies and the build-up of stellar mass throughout cosmic time.
- ID:
- ivo://CDS.VizieR/J/ApJS/193/8
- Title:
- Spectroscopy of 26 lensing cluster cores
- Short Name:
- J/ApJS/193/8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from a spectroscopic program targeting 26 strong-lensing cluster cores that were visually identified in the Sloan Digital Sky Survey (SDSS; Gladders et al. 2011, in prep) and the Second Red-Sequence Cluster Survey (RCS-2; Bayliss et al. 2011, in prep). The 26 galaxy cluster lenses span a redshift range of 0.2<z<0.65, and our spectroscopy reveals 69 unique background sources with redshifts as high as z=5.200. We also identify redshifts for 262 cluster member galaxies and measure the velocity dispersions and dynamical masses for 18 clusters where we have redshifts for N>=10 cluster member galaxies. We account for the expected biases in dynamical masses of strong-lensing-selected clusters as predicted by results from numerical simulations and discuss possible sources of bias in our observations.
- ID:
- ivo://CDS.VizieR/J/AJ/143/126
- Title:
- Spectroscopy of 462 nearby Type Ia supernovae
- Short Name:
- J/AJ/143/126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 2603 spectra of 462 nearby Type Ia supernovae (SNe Ia), including 2065 previously unpublished spectra, obtained during 1993-2008 through the Center for Astrophysics Supernova Program. There are on average eight spectra for each of the 313 SNe Ia with at least two spectra. Most of the spectra were obtained with the FAST spectrograph at the Fred Lawrence Whipple Observatory 1.5m telescope and reduced in a consistent manner, making this data set well suited for studies of SN Ia spectroscopic diversity. Using additional data from the literature, we study the spectroscopic and photometric properties of SNe Ia as a function of spectroscopic class using the classification schemes of Branch et al. (2006PASP..118..560B) and Wang et al. (2009, Cat. J/ApJ/699/L139). The width-luminosity relation appears to be steeper for SNe Ia with broader lines, although the result is not statistically significant with the present sample. Based on the evolution of the characteristic SiII{lambda}6355 line, we propose improved methods for measuring velocity gradients, revealing a larger range than previously suspected, from ~0 to ~400km/s/day considering the instantaneous velocity decline rate at maximum light.
- ID:
- ivo://CDS.VizieR/J/AJ/136/181
- Title:
- Spectroscopy of PC 1643+4631A,B
- Short Name:
- J/AJ/136/181
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the first measurement and detection of coherence in the intergalactic medium (IGM) at substantially high redshift (z~3.8) and on large physical scales (~2.5h^-1^_70_Mpc). We perform the measurement by presenting new observations of the high-redshift quasar pair PC 1643+4631A, B and their Ly{alpha}-absorber coincidences. With data collected from Keck I Low Resolution Imaging Spectrometer (LRIS) in a 10200s integration, we have full coverage of the Ly{alpha} forest over the redshift range 2.6<z<3.8 at a resolution of 3.6{AA} (~220km/s).
- ID:
- ivo://CDS.VizieR/J/ApJS/175/29
- Title:
- Spectroscopy of QSO pairs
- Short Name:
- J/ApJS/175/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Ly{alpha} forest has opened a new redshift regime for cosmological investigation. At z>2 it provides a unique probe of cosmic geometry and an independent constraint on dark energy that is not subject to standard candle or ruler assumptions. In Paper I of this series on using the Ly{alpha} forest observed in pairs of QSOs for a new application of the Alcock-Paczynski test, we present and discuss the results of a campaign to obtain moderate-resolution spectroscopy (FWHM~2.5{AA}) of the Ly{alpha} forest in pairs of QSOs with small redshift differences ({Delta}z<0.25, z>2.2) and arcminute separations ({Theta}<5'). This data set, composed of seven individual QSOs, 35 pairs, and one triplet, is also well suited for future investigations of the coherence of Ly{alpha} absorbers on ~1Mpc transverse scales and the transverse proximity effect. We note seven revisions for previously published QSO identifications and/or redshifts.
- ID:
- ivo://CDS.VizieR/J/ApJ/678/635
- Title:
- Spectroscopy of quasar binary candidates
- Short Name:
- J/ApJ/678/635
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present spectroscopy of binary quasar candidates, with component separations of 3"<={Delta}{theta}<6", selected from SDSS DR4 using kernel density estimation (KDE). Of our 27 new quasar pair observations, 10 are binary quasars, which doubles the number of known g<21 binaries with 3"<={Delta}{theta}<6" separations. Several of our observed binaries are wide-separation lens candidates that merit additional higher resolution spectroscopy, as well as deep imaging to search for lensing galaxies. Our candidates are initially selected by UV excess (u-g<1), but are otherwise selected irrespective of the relative colors of the quasar pair, and we thus use them to suggest optimal color similarity and photometric redshift approaches for targeting binary quasars or projected quasar pairs. We find that a third or more of all binary quasars have quite dissimilar components on the basis of a typical color similarity criterion ({chi}^2^_color_<~20). From a sample that is complete on proper scales of 23.7h^-1^kpc<R_prop_<29.9h^-1^kpc, we determine the projected quasar correlation function.
- ID:
- ivo://CDS.VizieR/J/ApJ/902/17
- Title:
- Spectroscopy of quiescent gal. in 9 lensing clusters
- Short Name:
- J/ApJ/902/17
- Date:
- 03 Mar 2022 11:35:20
- Publisher:
- CDS
- Description:
- We measure the central stellar velocity dispersion function for quiescent galaxies in a set of nine northern clusters in the redshift range 0.18<z<0.29 and with strong lensing arcs in Hubble Space Telescope images. The velocity dispersion function links galaxies directly to their dark matter halos. From dense SDSS and MMT/Hectospec spectroscopy, we identify 222-463 spectroscopic members in each cluster. We derive physical properties of cluster members including redshift, D_n_4000, and central stellar velocity dispersion and we include a table of these measurements for 3419 cluster members. We construct the velocity dispersion functions for quiescent galaxies with D_n_4000>1.5 and within R200. The cluster velocity dispersion functions all show excesses at {sigma}>~250km/s compared to the field velocity dispersion function. The velocity dispersion function slope at large velocity dispersion ({sigma}>160km/s) is steeper for more massive clusters, consistent with the trend observed for cluster luminosity functions. The spatial distribution of galaxies with large velocity dispersion at radii larger than R200 further underscores the probable major role of dry mergers in the growth of massive cluster galaxies during cluster assembly.
- ID:
- ivo://CDS.VizieR/J/AJ/143/98
- Title:
- Spectroscopy of star-forming regions in NGC 4194
- Short Name:
- J/AJ/143/98
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of long-slit spectroscopy at position angles 68{deg}, 131{deg}, and 164{deg} for the minor-merger NGC 4194, a luminous infrared starburst galaxy. The mass within 1.2kpc of the dynamical center is estimated to be 4.8*109 to 1.7*1010 M{sun}, depending on the assumed inclination to the plane of the sky. The star formation rate (SFR) in the areas sampled is 8 M{sun}/yr. The metallicity, log(O/H)+12, ranges from ~8.8 to >9.0 in regions of significant star formation, suggesting that the metallicity has been enhanced by the current star formation. The star-forming regions range in age from 5 to 9Myr, with the youngest ages occurring in the regions of high SFR. Electron temperatures and the location of the spectra in emission line diagnostic diagrams suggest the presence of shock waves, presumably due to the presence of supernovae, winds from massive stars, and/or collisions of clouds due to the merger. The presence of massive stars and supernovae is consistent with the ages determined for the star-forming regions. The ages of the continua produced by the stellar population are estimated to range from 10Myr to 5Gyr. Much of the stellar population represented in the continua was probably formed before the merger and represents the progenitor galaxies.
