- ID:
- ivo://CDS.VizieR/J/ApJS/252/27
- Title:
- WWFI g'-band obs. of bright galaxy clusters
- Short Name:
- J/ApJS/252/27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore several ways to dissect brightest cluster galaxies (BCGs) and their surrounding intracluster light (ICL) using a surface brightness (SB) cut, a luminosity cut, excess light above a de Vaucouleurs profile, or a double Sersic decomposition. Assuming that all light above M{<}-21.85g'mag is attributable to the ICL, we find that an average fraction of f_ICL_^MT^=71+/-22% of all diffuse light centered on the BCG belongs to the ICL. Likewise, if we assume that all light fainter than SB>27g'mag/arcsec^2^ belongs to the ICL, the average ICL fraction is f_ICL_^SB27^=34+/-19% . After fitting a de Vaucouleurs profile to the inner parts of the SB profile, we detect excess light at large radii, corresponding to an average ICL fraction of f_ICL_^DV^=48+/-20% . Finally, by decomposing the SB profile into two Sersic functions, we find an average ICL fraction of f_ICL_^Sx^=52+/-21% associated with the outer Sersic component. Our measured ICL and BCG+ICL luminosities agree well with predictions from high-resolution simulations where the outer Sersic component traces the unrelaxed, accreted stellar material. BCG and ICL properties defined in this way are correlated with cluster parameters to study the coevolution of BCGs, ICL, and their host clusters. We find positive correlations between BCG+ICL brightness and cluster mass, cluster velocity dispersion, cluster radius, and integrated satellite brightness, confirming that BCG/ICL growth is indeed coupled with cluster growth. On average, the ICL is better aligned than the BCG with the host cluster in terms of position angle, ellipticity, and centering. That makes it a potential dark-matter tracer.
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- ID:
- ivo://CDS.VizieR/J/ApJ/799/60
- Title:
- X-ray galaxy clusters in the CFHTLS fields
- Short Name:
- J/ApJ/799/60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) presents a unique data set for weak-lensing studies, having high-quality imaging and deep multiband photometry. We have initiated an XMM-CFHTLS project to provide X-ray observations of the brightest X-ray-selected clusters within the wide CFHTLS area. Performance of these observations and the high quality of CFHTLS data allow us to revisit the identification of X-ray sources, introducing automated reproducible algorithms, based on the multicolor red sequence finder. We have also introduced a new optical mass proxy. We provide the calibration of the red sequence observed in the Canada-France-Hawaii filters and compare the results with the traditional single-color red sequence and photo-z. We test the identification algorithm on the subset of highly significant XMM clusters and identify 100% of the sample. We find that the integrated z-band luminosity of the red sequence galaxies correlates well with the X-ray luminosity, with a surprisingly small scatter of 0.20dex. We further use the multicolor red sequence to reduce spurious detections in the full XMM and ROSAT All-Sky Survey (RASS) data sets, resulting in catalogs of 196 and 32 clusters, respectively. We made spectroscopic follow-up observations of some of these systems with HECTOSPEC and in combination with BOSS DR9 data. We also describe the modifications needed to the source detection algorithm in order to maintain high purity of extended sources in the shallow X-ray data. We also present the scaling relation between X-ray luminosity and velocity dispersion.
- ID:
- ivo://CDS.VizieR/J/ApJ/554/L129
- Title:
- X-ray luminosity-velocity dispersion relation
- Short Name:
- J/ApJ/554/L129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We demonstrate that individual elliptical galaxies and clusters of galaxies form a continuous X-ray luminosity-velocity dispersion (L_X_-{sigma}) relation. Our samples of 280 clusters and 57 galaxies have L_X_ {prop.to}{sigma}^4.4^ and L_X_{prop.to}{sigma}^10^, respectively. This unified L_X_-{sigma} relation spans 8 orders of magnitude in L_X_ and is fully consistent with the observed and theoretical luminosity-temperature scaling laws. Our results support the notion that galaxies and clusters of galaxies are the luminous tracers of similar dark matter halos.
- ID:
- ivo://CDS.VizieR/J/AJ/144/173
- Title:
- YSOs from SED fitting in six HII regions
- Short Name:
- J/AJ/144/173
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigated six HII regions with infrared, bright rimmed bubble or cometary morphology, in search of quantitative evidence for triggered star formation, both collect and collapse and radiatively driven implosion (RDI). We identified and classified 458 young stellar objects (YSOs) in and around the HII regions. YSOs were determined by fitting a collection of radiative transfer model spectral energy distributions to infrared photometry for a large sample of point sources. We determined areas where there exist enhanced populations of relatively unevolved YSOs on the bright rims of these regions, suggesting that star formation has been triggered there. We further investigated the physical properties of the regions by using radio continuum emission as a proxy for ionizing flux powering the HII regions, and ^13^CO(1-0) observations to measure masses and gravitational stability of molecular clumps. We used an analytical model of collect and collapse triggered star formation, as well as a simulation of RDI, and thus we compare the observed properties of the molecular gas with those predicted in the triggering scenarios. Notably, those regions in our sample that show evidence of cometary, or "blister", morphology are more likely to show evidence of triggering.
- ID:
- ivo://CDS.VizieR/J/ApJ/858/60
- Title:
- z~0.8 quiescent galaxy kinematics from LEGA-C
- Short Name:
- J/ApJ/858/60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present stellar rotation curves and velocity dispersion profiles for 104 quiescent galaxies at z=0.6-1 from the Large Early Galaxy Astrophysics Census (LEGA-C) spectroscopic survey. Rotation is typically probed across 10-20kpc, or to an average of 2.7Re. Combined with central stellar velocity dispersions ({sigma}0) this provides the first determination of the dynamical state of a sample selected by a lack of star formation activity at large lookback time. The most massive galaxies (M_*_>2x10^11^M_{sun}_) generally show no or little rotation measured at 5 kpc (|V_5_|/{sigma}_0_<0.2 in eight of ten cases), while ~64% of less massive galaxies show significant rotation. This is reminiscent of local fast- and slow- rotating ellipticals and implies that low- and high-redshift quiescent galaxies have qualitatively similar dynamical structures. We compare |V_5_|/{sigma}_0_ distributions at z~0.8 and the present day by re-binning and smoothing the kinematic maps of 91 low-redshift quiescent galaxies from the Calar Alto Legacy Integral Field Area (CALIFA) survey and find evidence for a decrease in rotational support since z~1. This result is especially strong when galaxies are compared at fixed velocity dispersion; if velocity dispersion does not evolve for individual galaxies then the rotational velocity at 5kpc was an average of 94+/-22% higher in z~0.8 quiescent galaxies than today. Considering that the number of quiescent galaxies grows with time and that new additions to the population descend from rotationally supported star-forming galaxies, our results imply that quiescent galaxies must lose angular momentum between z~1 and the present, presumably through dissipationless merging, and/or that the mechanism that transforms star-forming galaxies also reduces their rotational support.
