- ID:
- ivo://CDS.VizieR/J/MNRAS/426/296
- Title:
- Compact Groups of galaxies from 2MASX
- Short Name:
- J/MNRAS/426/296
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a photometric catalogue of compact groups of galaxies (p2MCGs) automatically extracted from the Two-Micron All Sky Survey (2MASS) extended source catalogue. A total of 262 p2MCGs are identified, following the criteria defined by Hickson, of which 230 survive visual inspection (given occasional galaxy fragmentation and blends in the 2MASS parent catalogue). Only one quarter of these 230 groups were previously known compact groups (CGs). Among the 144 p2MCGs that have all their galaxies with known redshifts, 85 (59%) have four or more accordant galaxies. This v2MCG sample of velocity-filtered p2MCGs constitutes the largest sample of CGs (with N>=4) catalogued to date, with both well-defined selection criteria and velocity filtering, and is the first CG sample selected by stellar mass. It is fairly complete up to K_group_~9 and radial velocity of ~6000km/s.
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- ID:
- ivo://CDS.VizieR/J/ApJS/225/23
- Title:
- Compact groups of galaxies from SDSS-DR12 (MLCG)
- Short Name:
- J/ApJS/225/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We apply a friends-of-friends algorithm to an enhanced SDSS DR12 spectroscopic catalog, including redshift from the literature to construct a catalog of 1588 N>=3 compact groups of galaxies containing 5178 member galaxies and covering the redshift range 0.01<z<0.19. This catalog contains 18 times as many systems and reaches 3 times the depth of the similar catalog of Barton et al. (1996AJ....112..871B). We construct catalogs from both magnitude-limited and volume-limited galaxy samples. Like Barton et al. we omit the frequently applied isolation criterion in the compact group selection algorithm. Thus the groups selected by fixed projected spatial and rest-frame line-of-sight velocity separation produce a catalog of groups with a redshift-independent median size. In contrast to previous catalogs, the enhanced SDSS DR12 catalog (including galaxies with r<14.5) includes many systems with z<~0.05. The volume-limited samples are unique to this study. The compact group candidates in these samples have a median stellar mass independent of redshift. Groups with velocity dispersion <~100km/s show abundant evidence for ongoing dynamical interactions among the members. The number density of the volume-limited catalogs agrees with previous catalogs at the lowest redshifts but decreases as the redshift increases. The SDSS fiber placement constraints limit the catalog's completeness. In spite of this issue, the volume-limited catalogs provide a promising basis for detailed spatially resolved probes of the impact of galaxy-galaxy interactions within similar dense systems over a broad redshift range.
- ID:
- ivo://CDS.VizieR/J/AN/321/101
- Title:
- Compact groups of galaxies in LCRS
- Short Name:
- J/AN/321/101
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have recently extracted a catalog of compact groups of galaxies (CGs) from the Las Campanas Redshift Survey. This catalog of Las Campanas Compact Groups (LCCGs) contains 76 CGs with a median redshift of z_med_~0.08. The physical properties of these CGs are similar to those form Hickson (1982, Cat. <VII/213>) and the Barton et al. (1996AJ....112..871B) catalogs. Here, we present an atlas of our catalog and briefly describe its general properties.
- ID:
- ivo://CDS.VizieR/J/ApJS/246/12
- Title:
- Compact groups of galaxies in SDSS & LAMOST. I.
- Short Name:
- J/ApJS/246/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A compact group (CG) is a kind of special galaxy system where the galaxy members are separated at distances of the order of galaxy size. The strong interaction between the galaxy members makes CGs ideal labs for studying the environmental effects on galaxy evolution. The traditional photometric selection algorithm biases against the CG candidates at low redshifts, while the spectroscopic identification technique is affected by the spectroscopic incompleteness of sample galaxies and typically biases against the high redshift candidates. In this study, we combine these two methods and select CGs in the main galaxy sample of the Sloan Digital Sky Survey, where we also have taken the advantages of the complementary redshift measurements from the LAMOST spectral and GAMA surveys. We have obtained the largest and most complete CG samples to date. Our samples include 6144 CGs and 8022 CG candidates, which are unique in the studies of the nature of the CGs and the evolution of the galaxies inside.
- ID:
- ivo://CDS.VizieR/J/MNRAS/268/602
- Title:
- Compact radio cores in radio galaxies.
- Short Name:
- J/MNRAS/268/602
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog contains compact core fluxes for a list of 175 southern radio galaxies, measured with the Parkes-Tidbinbilla Interferometer (PTI, Norris et al. 1988ApJS...67...85N) on a single 275 km baseline at 2.3 GHz and 8.4 GHz. The sample consists of large angular size ( > 0.5 arcmin) steep spectrum sources from Jones & McAdam (1992ApJS...80..137J) observed to determine the fraction of flux contained in compact (VLBI-scale) cores. Of the 172 sources observed at 2.3 GHz (100 milliarcsec fringe spacing), 63 had cores detected and upper limits were determined for the remaining 109. Of the 88 sources observed at 8.4 GHz (30 milliarcsec fringe spacing), 38 had cores detected and 50 have upper limits. A comparison of the detections and upper limits at the two frequencies shows that the cores have flat or inverted spectra. The core fluxes quoted here may vary by around 20 % if there is structure on the scale of the fringe spacing and the cores are probably intrinsically variable.
- ID:
- ivo://CDS.VizieR/J/AJ/133/2559
- Title:
- Compact radio sources in spiral galaxies. II.
- Short Name:
- J/AJ/133/2559
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the analysis of deep radio observations of the interacting galaxy system M51 from the Very Large Array, with the goal of understanding the nature of the population of compact radio sources in nearby spiral galaxies. We detect 107 compact radio sources, 64% of which have optical counterparts in a deep H{alpha} Hubble Space Telescope image. Thirteen of the radio sources have X-ray counterparts from a Chandra observation of M51. We find that six of the associated H{alpha} sources are young supernova remnants (SNRs) with resolved shells. Most of the SNRs exhibit steep radio continuum spectral indices consistent with synchrotron emission. We detect emission from the Type Ic SN 1994I nearly a decade after explosion: the emission (160+/-22uJy/beam at 20cm, 46+/-11uJy/beam at 6cm, {alpha}=-1.02+/-0.28) is consistent with light-curve models for Type Ib/Ic supernovae. We detect X-ray emission from the supernova; however, no optical counterpart is present. We report on the analysis of the Seyfert 2 nucleus in this galaxy, including the evidence for bipolar outflows from the central black hole.
- ID:
- ivo://CDS.VizieR/J/MNRAS/405/1293
- Title:
- Compact star clusters in M81
- Short Name:
- J/MNRAS/405/1293
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the population of compact star clusters (CSCs) in M81, using the Hubble Space Telescope/Advanced Camera for Surveys (ACS) images in the filters F435W, F606W and F814W covering, for the first time, the entire optical extent of the galaxy. Our sample contains 435 clusters of full width at half-maximum less than 10 ACS pixels (9pc). The sample shows the presence of two cluster populations, a blue group of 263 objects brighter than B=22mag, and a red group of 172 objects, brighter than B=24mag. On the basis of analysis of colour-magnitude diagrams and making use of simple stellar population models,
- ID:
- ivo://CDS.VizieR/J/ApJ/824/71
- Title:
- Compact star clusters in M51 with HST
- Short Name:
- J/ApJ/824/71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new catalog of 3816 compact star clusters in the grand design spiral galaxy M51 based on observations taken with the Hubble Space Telescope (HST). The age distribution of the clusters declines starting at very young ages, and can be represented by a power law, dN/d{tau}{propto}{tau}^gamma^, with {gamma}=-0.65+/-0.15. No significant changes in the shape of the age distribution at different masses is observed. The mass function of the clusters younger than {tau}~400Myr can also be described by a power law, dN/dM{propto}M^{beta}^, with {beta}~-2.1+/-0.2. We compare these distributions with the predictions from various cluster disruption models, and find that they are consistent with models where clusters disrupt approximately independent of their initial mass, but not with models where lower mass clusters are disrupted earlier than their higher mass counterparts. We find that the half-light radii of clusters more massive than M~3x10^4^M_{sun}_ and with ages between 100 and 400Myr are larger by a factor of ~3-4 than their counterparts that are younger than 10^7^ years old, suggesting that the clusters physically expand during their early life.
- ID:
- ivo://CDS.VizieR/J/ApJ/703/1872
- Title:
- Compact star clusters in the M31 disk
- Short Name:
- J/ApJ/703/1872
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have carried out a survey of compact star clusters (apparent size <~3") in the southwest part of the M31 galaxy, based on the high-resolution Suprime-Cam images (17.5'x28.5'), covering ~15% of the deprojected galaxy disk area. The UBVRI photometry of 285 cluster candidates (V<~20.5mag) was performed using frames of the Local Group Galaxies Survey. The final sample, containing 238 high probability star cluster candidates (typical half-light radius r_h_~1.5pc), was selected by specifying a lower limit of r_h_>~0.15" (>~0.6pc). We derived cluster parameters based on the photometric data and multiband images by employing simple stellar population models. The clusters have a wide range of ages from ~5Myr (young objects associated with 24um and/or H{alpha} emission) to ~10Gyr (globular cluster candidates), and possess mass in a range of 3.0<~log(m/m_{sun}_)<~4.3 peaking at m~4000m_{sun}_. Typical age of these intermediate-mass clusters is in the range of 30Myr<~t<~3Gyr, with a prominent peak at ~70Myr. These findings suggest a rich intermediate-mass star cluster population in M31, which appears to be scarce in the Milky Way galaxy.
- ID:
- ivo://CDS.VizieR/J/MNRAS/315/839
- Title:
- Compact variable radio sources at 151MHz. I.
- Short Name:
- J/MNRAS/315/839
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Cambridge Low-Frequency Synthesis Telescope has been used to produce a representative sample of low-frequency variable sources. 20 fields, each covering an area of approximately 9{deg}x9{deg}cosecDE, have been observed at 151MHz at between 2 and 10 epochs over the period from 1984 to 1996. At each epoch, maps were made with rms noise levels of typically 10^-15^mJy/beam. From a total of ~6000 sources detected on these maps, 207 are found for which the flux density variations between at least two epochs appear significant at greater than the 3{sigma} level. A numerical model is used to assess the true significance of the variability, given the analysis method adopted. This shows that for about half of the sources which appear to vary by >3{sigma} the variability is genuine. For the other half it is caused by random statistical fluctuations; most of the spurious variables vary by <=3.5{sigma} between a single pair of epochs. A catalogue of the variable sources is presented, which includes an estimate of the probability that a given source is a genuine variable. Fractional flux density variations of between 5 and 100% (typically 15-25%) have been detected on a range of time-scales from 1 to 12 years.
