- ID:
- ivo://CDS.VizieR/J/ApJ/792/76
- Title:
- Lensed z~6-8 galaxies behind CLASH clusters
- Short Name:
- J/ApJ/792/76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We utilize 16 band Hubble Space Telescope (HST) observations of 18 lensing clusters obtained as part of the Cluster Lensing And Supernova survey with Hubble (CLASH) Multi-Cycle Treasury program to search for z ~ 6-8 galaxies. We report the discovery of 204, 45, and 13 Lyman-break galaxy candidates at z ~ 6, z ~ 7, and z ~ 8, respectively, identified from purely photometric redshift selections. This large sample, representing nearly an order of magnitude increase in the number of magnified star-forming galaxies at z ~ 6-8 presented to date, is unique in that we have observations in four WFC3/UVIS UV, seven ACS/WFC optical, and all five WFC3/IR broadband filters, which enable very accurate photometric redshift selections. We construct detailed lensing models for 17 of the 18 clusters to estimate object magnifications and to identify two new multiply lensed z >~ 6 candidates. The median magnifications over the 17 clusters are 4, 4, and 5 for the z ~ 6, z ~ 7, and z ~ 8 samples, respectively, over an average area of 4.5 arcmin^2^ per cluster. We compare our observed number counts with expectations based on convolving "blank" field UV luminosity functions through our cluster lens models and find rough agreement down to ~27 mag, where we begin to suffer significant incompleteness. In all three redshift bins, we find a higher number density at brighter observed magnitudes than the field predictions, empirically demonstrating for the first time the enhanced efficiency of lensing clusters over field surveys. Our number counts also are in general agreement with the lensed expectations from the cluster models, especially at z ~ 6, where we have the best statistics.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/868/129
- Title:
- Lensing analysis in Abell 370
- Short Name:
- J/ApJ/868/129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new gravitational lens model of the Hubble Frontier Fields cluster Abell 370 (z=0.375) using imaging and spectroscopy from Hubble Space Telescope and ground-based spectroscopy. We combine constraints from a catalog of 909 weakly lensed galaxies and 39 multiply imaged sources comprised of 114 multiple images, including a system of multiply imaged candidates at z=7.84+/-0.02, to obtain a best-fit mass distribution using the cluster lens modeling code strong and weak lensing united. As the only analysis of A370 using strong and weak lensing constraints from Hubble Frontier Fields (HFF) data, our method provides an independent check of assumptions on the mass distribution used in other methods. Convergence, shear, and magnification maps are made publicly available through the HFF website (http://www.stsci.edu/hst/campaigns/frontier-fields). We find that the model we produce is similar to models produced by other groups, with some exceptions due to the differences in lensing code methodology. In an effort to study how our total projected mass distribution traces light, we measure the stellar mass density distribution using Spitzer/Infrared array camera imaging. Comparing our total mass density to our stellar mass density in a radius of 0.3Mpc, we find a mean projected stellar to total mass ratio of <f*>=0.011+/-0.003 (stat.) using the diet Salpeter initial mass function. This value is in general agreement with independent measurements of <f*> in clusters of similar total mass and redshift.
- ID:
- ivo://CDS.VizieR/J/ApJ/703/2217
- Title:
- Lensing measurement of SDSS galaxy clusters. I.
- Short Name:
- J/ApJ/703/2217
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the first in a series of papers on the weak lensing effect caused by clusters of galaxies in Sloan Digital Sky Survey. The photometrically selected cluster sample, known as MaxBCG, includes ~130000 objects between redshift 0.1 and 0.3, ranging in size from small groups to massive clusters. We split the clusters into bins of richness and luminosity and stack the surface density contrast to produce mean radial profiles. The mean profiles are detected over a range of scales, from the inner halo (25kpc/h) well into the surrounding large-scale structure (30Mpc/h), with a significance of 15 to 20 in each bin. The signal over this large range of scales is best interpreted in terms of the cluster-mass cross-correlation function. We pay careful attention to sources of systematic error, correcting for them where possible. The resulting signals are calibrated to the ~10% level, with the dominant remaining uncertainty being the redshift distribution of the background sources.
- ID:
- ivo://CDS.VizieR/J/ApJ/723/1678
- Title:
- LensPerfect A1689 analysis
- Short Name:
- J/ApJ/723/1678
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a strong lensing (SL) mass model of A1689 which resolves substructures an estimated 25kpc across within the central ~400kpc diameter. We achieve this resolution by perfectly reproducing the observed (strongly lensed) input positions of 168 multiple images of 55 knots residing within 135 images of 42 galaxies. Our model makes no assumptions about light tracing mass, yet we reproduce the brightest visible structures with some slight deviations. A1689 remains one of the strongest known lenses on the sky, with an Einstein radius of R_E_=47.0+/-1.2" (143^+3^_-4_kpc) for a lensed source at z_s_=2. We find that a single Navarro-Frenk-White (NFW) or Sersic profile yields a good fit simultaneously (with only slight tension) to both our SL mass model and published weak lensing (WL) measurements at larger radius (out to the virial radius). Our SL model prefers slightly higher concentrations than previous SL models, bringing our SL+WL constraints in line with other recent derivations. Our results support those of previous studies which find A1689 has either an anomalously large concentration or significant extra mass along the line of sight (perhaps in part due to triaxiality).
- ID:
- ivo://CDS.VizieR/J/A+A/499/47
- Title:
- Lick indices of EDCSN galaxies
- Short Name:
- J/A+A/499/47
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a comprehensive analysis of the stellar population properties (age, metallicity and the alpha-element enhancement [E/Fe]) and morphologies of red-sequence galaxies in 24 clusters and groups from z~0.75 to z~0.45. The dataset, consisting of 215 spectra drawn from the ESO Distant Cluster Survey, constitutes the largest spectroscopic sample at these redshifts for which such an analysis has been conducted. Analysis reveals that the evolution of the stellar population properties of red-sequence galaxies depend on their mass: while the properties of most massive are well described by passive evolution and high-redshift formation, the less massive galaxies require a more extended star formation history. We show that these scenarios reproduce the index-sigma relations as well as the galaxy colours. The two main results of this work are (1) the evolution of the line-strength indices for the red-sequence galaxies can be reproduced if 40% of the galaxies with sigma<175km/s entered the red-sequence between z=0.75 to z=0.45, in agreement with the fraction derived in studies of the luminosity functions, and (2) the percentage of galaxies in the red-sequence with early-type morphologies (E/S0) decreases by 20% from z=0.75 to z=0.45. This can be understood if the red-sequence gets populated at later times with disc galaxies with quenched star formation. We conclude that the processes quenching star formation do not necessarily produce a simultaneous morphological transformation of the galaxies entering the red-sequence.
- ID:
- ivo://CDS.VizieR/J/ApJ/795/L21
- Title:
- Limits on gamma-ray emission from galaxy clusters
- Short Name:
- J/ApJ/795/L21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Galaxy clusters are predicted to produce {gamma}-rays through cosmic ray interactions and/or dark matter annihilation, potentially detectable by the Fermi Large Area Telescope (Fermi-LAT). We present a new, independent stacking analysis of Fermi-LAT photon count maps using the 78 richest nearby clusters (z<0.12) from the Two Micron All Sky Survey cluster catalog. We obtain the lowest limit on the photon flux to date, 2.3x10^-11^ photons/cm2/s (95% confidence) per cluster in the 0.8-100 GeV band, which corresponds to a luminosity limit of 3.5x10^44^ photons/s. We also constrain the emission limits in a range of narrower energy bands. Scaling to recent cosmic ray acceleration and {gamma}-ray emission models, we find that cosmic rays represent a negligible contribution to the intra-cluster energy density and gas pressure.
- ID:
- ivo://CDS.VizieR/J/ApJ/714/1441
- Title:
- Linearity of the cosmic expansion field
- Short Name:
- J/ApJ/714/1441
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Particularly accurate relative distances are compiled and homogenized for (1) 246 Type Ia supernovae and 35 clusters with v<30000km/s, and (2) relatively nearby galaxies with 176 tip of the red-giant branch and 30 Cepheid distances. The 487 objects define a tight Hubble diagram from 300-30000km/s implying individual distance errors of <~7.5%. Here the velocities are corrected for Virgocentric steaming (locally 220km/s) and -if v_220_>3500km/s- for a 495km/s motion of the Local Supercluster toward the warm cosmic microwave background (CMB) pole at l=275, b=12; local peculiar motions are averaged out by large numbers.
- ID:
- ivo://CDS.VizieR/J/ApJ/691/1862
- Title:
- Line-strength indices for 74 early-type galaxies
- Short Name:
- J/ApJ/691/1862
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present line-strength measurements for 74 early-type galaxies in the core of the Coma cluster reaching down to velocity dispersions, {sigma}, of 30km/s. The index-{sigma} relations for our sample, including galaxies with {sigma}<100km/s (low-{sigma}), differ in shape depending on which index is used. We note two types of relations for the metallic indices: one showing a break in the slope around ~100km/s and another group with strong linear relations between an index and log {sigma}. We find no connection between the behavior of index-{sigma} relations with either {alpha}- or Fe-peak elements. However, we find indications that the relations are tighter for indices which do not depend on the microturbulent velocities of stellar atmospheres.
- ID:
- ivo://CDS.VizieR/J/A+A/653/A106
- Title:
- List of candidate clusters
- Short Name:
- J/A+A/653/A106
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present the first combination of a thermal Sunyaev-Zel'dovich (tSZ) map with a multi-frequency quality assessment of the sky pixels based on artificial neural networks (ANNs) with the aim being to detect tSZ sources from submillimeter observations of the sky by Planck.We present the construction of the resulting filtered and cleaned tSZ map, MILCANN.We show that this combination leads to a significant reduction of noise fluctuations and foreground residuals compared to standard reconstructions of tSZ maps. From the MILCANN map, we constructed a tSZ source catalog of about 4000 sources with a purity of 90%. Finally, we compare this catalog with ancillary catalogs and show that the galaxy-cluster candidates in our catalog are essentially low-mass (down to M_500_=10^14^M+{sun}_) high-redshift (up to z<=1) galaxy cluster candidates.
- ID:
- ivo://CDS.VizieR/J/A+A/343/93
- Title:
- Local radio luminosity function of galaxies. II.
- Short Name:
- J/A+A/343/93
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using new extensive radio continuum surveys at 1.4GHz (FIRST and NVSS), we derive the distribution of the radio/optical and radio/NIR luminosity (RLF) of late-type (Sa-Irr) galaxies (m_p_<15.7) in 5 nearby clusters of galaxies: A262, Cancer, A1367, Coma and Virgo. With the aim of discussing possible environmental dependences of the radio properties, we compare these results with those obtained for relatively isolated objects in the Coma supercluster. We find that the RLF of Cancer, A262 and Virgo are consistent with that of isolated galaxies. Conversely we confirm earlier claims that galaxies in A1367 and Coma have their radio emissivity enhanced by a factor ~5 with respect to isolated objects. We discuss this result in the framework of the dynamical pressure suffered by galaxies in motion through the intra-cluster gas (ram-pressure). We find that the radio excess is statistically larger for galaxies in fast transit motion. This is coherent with the idea that enhanced radio continuum activity is associated with magnetic field compression. The X-ray luminosities and temperatures of Coma and A1367 imply that these two clusters have significantly larger intracluster gas density than the remaining three studied ones, providing a clue for explaining the higher radio continuum luminosities of their galaxies. Multiple systems in the Coma supercluster bridge (with projected separations smaller than 300kpc) have radio luminosities significantly larger than isolated galaxies.
