- 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.
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3472. Spectroscopy of Segue 1
- ID:
- ivo://CDS.VizieR/J/ApJ/692/1464
- Title:
- Spectroscopy of Segue 1
- Short Name:
- J/ApJ/692/1464
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Keck/DEIMOS spectroscopy of Segue 1, an ultra-low-luminosity (M_V_=-1.5^+0.6^_-0.8_) Milky Way satellite companion. While the combined size and luminosity of Segue 1 are consistent with either a globular cluster or a dwarf galaxy, we present spectroscopic evidence that this object is a dark matter-dominated dwarf galaxy. We identify 24 stars as members of Segue 1 with a mean heliocentric recession velocity of 206+/-1.3km/s. Although Segue 1 spatially overlaps the leading arm of the Sagittarius stream, its velocity is 100km/s different from that predicted for recent Sagittarius tidal debris at this position. Using spectral synthesis modeling, we derive a metallicity for the single red giant branch star in our sample of [Fe/H]=-3.3+/-0.2dex. We conclude that Segue 1 is the least luminous of the ultra-faint galaxies recently discovered around the Milky Way, and is thus the least-luminous known galaxy.
- ID:
- ivo://CDS.VizieR/J/ApJ/850/94
- Title:
- Spectroscopy of the fields of gravitational lenses
- Short Name:
- J/ApJ/850/94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Strong gravitational lensing provides an independent measurement of the Hubble parameter (H_0_). One remaining systematic is a bias from the additional mass due to a galaxy group at the lens redshift or along the sightline. We quantify this bias for more than 20 strong lenses that have well-sampled sightline mass distributions, focusing on the convergence {kappa} and shear {gamma}. In 23% of these fields, a lens group contributes >=1% convergence bias; in 57%, there is a similarly significant line-of-sight group. For the nine time-delay lens systems, H0 is overestimated by 11_-2_^+3^% on average when groups are ignored. In 67% of fields with total {kappa}>=0.01, line-of-sight groups contribute >~2x more convergence than do lens groups, indicating that the lens group is not the only important mass. Lens environment affects the ratio of four (quad) to two (double) image systems; all seven quads have lens groups while only 3 of 10 doubles do, and the highest convergences due to lens groups are in quads. We calibrate the {gamma}-{kappa} relation: log({kappa}_tot_)=(1.94+/-0.34)log({gamma}_tot_)+(1.31+/-0.49) with an rms scatter of 0.34dex. Although shear can be measured directly from lensed images, unlike convergence, it can be a poor predictor of convergence; for 19% of our fields, {kappa} is >~2{gamma}. Thus, accurate cosmology using strong gravitational lenses requires precise measurement and correction for all significant structures in each lens field.
- ID:
- ivo://CDS.VizieR/J/ApJ/691/1387
- Title:
- Spectroscopy of the Galactic bar. I.
- Short Name:
- J/ApJ/691/1387
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use Fabry-Perot absorption line imaging spectroscopy to measure radial velocities using the CaII line in 3360 stars toward three lines of sight in the Milky Way's bar: Baade's Window and offset position at (l,b)~(+/-5.0,-3.5{deg}). This sample includes 2488 bar red clump giants, 339 bar M/K-giants, and 318 disk main-sequence stars. We measure the first four moments of the stellar velocity distribution of the red clump giants, and find it to be symmetric and flat-topped. We also measure the line-of-sight average velocity and dispersion of the red clump giants as a function of distance in the bar.
- ID:
- ivo://CDS.VizieR/J/ApJ/668/853
- Title:
- Spectroscopy of UltraStrong Emission Line galaxies
- Short Name:
- J/ApJ/668/853
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe the results of a narrowband search for ultrastrong emission line galaxies (USELs) with EW(H{beta})>=30{AA}. A total of 542 candidate galaxies are found in a one-half square degree survey using two ~120{AA} filters centered at 8150 and 9140{AA} with Subaru SuprimeCam. Follow-up spectroscopy for randomly selected objects in the candidate sample with Keck II DEIMOS shows that they consist of [OIII] {lambda}5007-, [OII] {lambda}3727-, and H{alpha}-selected strong emission line galaxies at intermediate redshift (z<1) and Ly{alpha}-emitting galaxies at high redshift (z>>5).
- ID:
- ivo://CDS.VizieR/J/ApJ/693/1713
- Title:
- Spectroscopy of X-ray sources in ECDF-S
- Short Name:
- J/ApJ/693/1713
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results of our optical spectroscopy program aimed to provide redshifts and identifications for the X-ray sources in the Extended Chandra Deep Field South. A total of 339 sources were targeted using the IMACS spectrograph at the Magellan telescopes and the VIMOS spectrograph at the VLT. We measured redshifts for 186 X-ray sources, including archival data and a literature search. We find that the active galactic nucleus (AGN) host galaxies have on average redder rest-frame optical colors than nonactive galaxies, and that they live mostly in the "green valley". The dependence of the fraction of AGNs that are obscured on both luminosity and redshift is confirmed at high significance and the observed AGN spatial density is compared with the expectations from existing luminosity functions. These AGNs show a significant difference in the mid-IR to X-ray flux ratio for obscured and unobscured AGNs, which can be explained by the effects of dust self-absorption on the former. This difference is larger for lower luminosity sources, which is consistent with the dust opening angle depending on AGN luminosity.
- ID:
- ivo://CDS.VizieR/J/ApJ/880/46
- Title:
- Spectroscopy & V-band monitoring of CTS C30.10
- Short Name:
- J/ApJ/880/46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report 6yr monitoring of distant bright quasar CTS C30.10 (z=0.90052) with the Southern African Large Telescope. We measured the rest-frame time lag of 562_-68_^+116^ days between the continuum variations and the response of the MgII emission line, using six different methods. This time delay, combined with other available measurements of MgII line delay, mostly for lower-redshift sources, shows that the MgII line reverberation implies a radius-luminosity relation very similar to the one based on a more frequently studied H{beta} line.
3478. Spectrum of SXP1062
- ID:
- ivo://CDS.VizieR/J/A+A/556/A139
- Title:
- Spectrum of SXP1062
- Short Name:
- J/A+A/556/A139
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Be/X-ray binary SXP 1062 is of especial interest owing to the large spin period of the neutron star, its large spin-down rate, and the association with a supernova remnant constraining its age. This makes the source an important probe for accretion physics. To investigate the long-term evolution of the spin period and associated spectral variations, we performed an XMM-Newton target-of-opportunity observation of SXP 1062 during X-ray outburst. Spectral and timing analysis of the XMM-Newton data was compared with previous studies, as well as complementary Swift/XRT monitoring and optical spectroscopy with the SALT telescope were obtained. The spin period was measured to be Ps=(1071.01+/-0.16)s on 2012 Oct 14. The X-ray spectrum is similar to that of previous observations. No convincing cyclotron absorption features, which could be indicative for a high magnetic field strength, are found. The high-resolution RGS spectra indicate the presence of emission lines, which may not completely be accounted for by the SNR emission. The comparison of multi-epoch optical spectra suggest an increasing size or density of the decretion disc around the Be star. SXP 1062 showed a net spin-down with an average of dPs/dt=(2.27+/-0.44)s/yr over a baseline of 915 days.
- ID:
- ivo://CDS.VizieR/J/A+A/639/A47
- Title:
- SPHERE and NaCo images of HD 19467B
- Short Name:
- J/A+A/639/A47
- Date:
- 23 Mar 2022 16:31:06
- Publisher:
- CDS
- Description:
- HD 19467 observations were performed with the VLT exoplanet imager SPHERE and the VLT adaptive optics camera NaCo to further characterize the spectral and orbital properties of the known T-type brown dwarf companion.
- ID:
- ivo://CDS.VizieR/J/MNRAS/478/4952
- Title:
- SPIDERS BCGs gri photometry
- Short Name:
- J/MNRAS/478/4952
- Date:
- 10 Dec 2021 13:51:48
- Publisher:
- CDS
- Description:
- We present a sample of 329 low-to intermediate-redshift (0.05<z<0.3) brightest cluster galaxies (BCGs) in X-ray-selected clusters from the SPectroscopic IDentification of eRosita Sources survey, a spectroscopic survey within Sloan Digital Sky Survey-IV (SDSS-IV). We define our BCGs by simultaneous consideration of legacy X-ray data from ROSAT, maximum-likelihood outputs from an optical cluster-finder algorithm and visual inspection. Using SDSS imaging data, we fit Sersic profiles to our BCGs in three bands (g, r, i) with SIGMA a GALFIT-based software wrapper. We examine the reliability of our fits by running our pipeline on ~10^4^ point spread function-convolved model profiles injected into eight random cluster fields; we then use the results of this analysis to create a robust subsample of 198 BCGs. We outline three cluster properties of interest: overall cluster X-ray luminosity (L_X_), cluster richness as estimated by REDMAPPER ({lambda}),and cluster halo mass (M_200_), which is estimated via velocity dispersion. In general, there are significant correlations with BCG stellar mass between all three environmental properties, but no significant trends arise with either Sersic index or effective radius. There is no major environmental dependence on the strength of the relation between effective radius and BCG stellar mass. Stellar mass therefore arises as the most important factor governing BCG morphology. Our results indicate that our sample consists of a large number of relaxed, mature clusters containing broadly homogeneous BCGs up to z~0.3, suggesting that there is little evidence for much ongoing structural evolution for BCGs in these systems.
