- 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.
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Search Results
- 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.
- ID:
- ivo://CDS.VizieR/J/A+A/511/A12
- Title:
- Low-luminosity galaxies in NGC 5846 group
- Short Name:
- J/A+A/511/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Low-luminosity galaxies are known to outnumber the bright galaxy population in poor groups and clusters of galaxies. Yet, the investigation of low-luminosity galaxy populations outside the Local Group remains rare and the dependence on different group environments is still poorly understood. Previous investigations have uncovered the photometric scaling relations of early-type dwarfs and a strong dependence of morphology with environment. The present study aims to analyse the photometric and spectroscopic properties of the low-luminosity galaxy population in the nearby, well-evolved and early-type dominated NGC 5846 group of galaxies. It is the third most massive aggregate of early-type galaxies after the Virgo and Fornax clusters in the local universe. Photometric scaling relations and the distribution of morphological types as well as the characteristics of emission-line galaxies are investigated.
- ID:
- ivo://CDS.VizieR/J/MNRAS/451/2723
- Title:
- Low-redshift clusters in the SAMI Pilot Survey
- Short Name:
- J/MNRAS/451/2723
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using new integral field observations of 106 galaxies in three nearby clusters, we investigate how the intrinsic scatter of the Fundamental Plane depends on the way in which the velocity dispersion and effective radius are measured. Our spatially resolved spectroscopy, combined with a cluster sample with negligible relative distance errors, allows us to derive a Fundamental Plane with minimal systematic uncertainties. From the apertures we tested, we find that velocity dispersions measured within a circular aperture with radius equal to one effective radius minimizes the intrinsic scatter of the Fundamental Plane. Using simple yet powerful Jeans dynamical models, we determine dynamical masses for our galaxies. Replacing luminosity in the Fundamental Plane with dynamical mass, we demonstrate that the resulting Mass Plane has further reduced scatter, consistent with zero intrinsic scatter. Using these dynamical models, we also find evidence for a possibly non-linear relationship between dynamical mass-to-light ratio and velocity dispersion.
- ID:
- ivo://CDS.VizieR/J/MNRAS/437/2607
- Title:
- Low X-ray luminosity galaxy clusters
- Short Name:
- J/MNRAS/437/2607
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the second of a series of papers on low X-ray luminosity galaxy clusters, in which we present the r', g' and i' photometry obtained with Gemini Multi-Object Spectrograph IMAGE at Gemini North and South telescopes for seven systems in the redshift range of 0.18 to 0.70. Optical magnitudes, colours and morphological parameters, namely, concentration index, ellipticity and visual morphological classification, are also given. At lower redshifts, the presence of a well-defined red cluster sequence extending by more than 4mag showed that these intermediate-mass clusters had reached a relaxed stage. This was confirmed by the small fraction of blue galaxy members observed in the central regions of ~0.75Mpc. In contrast, galaxy clusters at higher redshifts had a less important red cluster sequence. We also found that the galaxy radial density profiles in these clusters were well fitted by a single power law. At 0.18<z<0.70, we observed an increasing fraction of blue galaxies and a decreasing fraction of lenticulars, with the early-type fraction remaining almost constant. Overall, the results of these intermediate-mass clusters are in agreement with those for high-mass clusters.
559. LRG catalog
- ID:
- ivo://CDS.VizieR/J/MNRAS/380/1608
- Title:
- LRG catalog
- Short Name:
- J/MNRAS/380/1608
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this work I discuss the necessary steps for deriving photometric redshifts for luminous red galaxies (LRGs) and galaxy clusters through simple empirical methods. The data used are from the Sloan Digital Sky Survey (SDSS). I show that with three bands only (gri) it is possible to achieve results as accurate as the ones obtained by other techniques, generally based on more filters. In particular, the use of the (g-i) colour helps improving the final redshifts (especially for clusters), as this colour monotonically increases up to z~0.8. For the LRGs I generate a catalogue of ~1.5 million objects at z<0.70. The accuracy of this catalogue is sigma=0.027 for z<=0.55 and sigma=0.049 for 0.55<z<=0.70. The photometric redshift technique employed for clusters is independent of a cluster selection algorithm. Thus, it can be applied to systems selected by any method or wavelength, as long as the proper optical photometry is available. When comparing the redshift listed in literature to the photometric estimate, the accuracy achieved for clusters is sigma=0.024 for z<=0.30 and sigma=0.037 for 0.30<z<=0.55. However, when considering the spectroscopic redshift as the mean value of SDSS galaxies on each cluster region, the accuracy is at the same level as found by other authors: sigma=0.011 for z<=0.30 and sigma=0.016 for 0.30<z<=0.55. The photometric redshift relation derived here is applied to thousands of cluster candidates selected elsewhere. I have also used galaxy photometric redshifts available in SDSS to identify groups in redshift space and then compare the redshift peak of the nearest group to each cluster redshift. This procedure provides an alternative approach for cluster selection, especially at high redshifts, as the cluster red sequence may be poorly defined.
560. LSBVCC galaxy sample
- ID:
- ivo://CDS.VizieR/J/MNRAS/456/1607
- Title:
- LSBVCC galaxy sample
- Short Name:
- J/MNRAS/456/1607
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used data from the Next Generation Virgo Survey to investigate the dwarf galaxy population of the Virgo cluster. We mask and smooth the data, and then use the object detection algorithm SExtractor to make our initial dwarf galaxy selection. All candidates are then visually inspected to remove artefacts and duplicates. We derive parameters to best select low surface brightness galaxies using central surface brightness values of 22.5<={mu}^g^_0_<=26.0{mu}g and exponential scale lengths of 3.0<=h<=10.0-arcsec to identify 443 cluster dwarf galaxies - 303 of which are new detections, with a surface density that decreases with radius from the cluster centre. We also apply our selection algorithm to 'background', non-cluster, fields and find zero detections. In combination, this leads us to believe that we have isolated a cluster dwarf galaxy population. The range of objects we detect is limited because smaller scale sized galaxies are confused with the background, while larger galaxies are split into numerous smaller objects by the detection algorithm. Combining our data with that from other surveys, we find a faint-end slope to the luminosity function of -1.35+/-0.03, which is not significantly different to what has previously been found, but is a little steeper than the slope for field galaxies. There is no evidence for a faint-end slope steep enough to correspond with galaxy formation models, unless those models invoke either strong feedback processes or use warm dark matter.
