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- ID:
- ivo://CDS.VizieR/J/AJ/141/189
- Title:
- Classifiers for star/galaxy separation
- Short Name:
- J/AJ/141/189
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the star/galaxy classification efficiency of 13 different decision tree algorithms applied to photometric objects in the Sloan Digital Sky Survey Data Release Seven (SDSS-DR7). Each algorithm is defined by a set of parameters which, when varied, produce different final classification trees. We extensively explore the parameter space of each algorithm, using the set of 884,126 SDSS objects with spectroscopic data as the training set. The efficiency of star-galaxy separation is measured using the completeness function.
- ID:
- ivo://CDS.VizieR/J/A+A/597/A122
- Title:
- Cluster and field elliptical galaxies at z~1.3
- Short Name:
- J/A+A/597/A122
- Date:
- 04 Feb 2022 00:04:27
- Publisher:
- CDS
- Description:
- The aim of this work is twofold: first, to assess whether the population of elliptical galaxies in cluster at z~1.3 differs from the population in the field and whether their intrinsic structure depends on the environment where they belong; second, to constrain their properties 9Gyr back in time through the study of their scaling relations. We compared a sample of 56 cluster elliptical galaxies selected from three clusters at 1.2<z<1.4 with elliptical galaxies selected at comparable redshift in the GOODS-South field (~30), in the COSMOS area (~180), and in the CANDELS fields (~220). To single out the environmental effects, we selected cluster and field elliptical galaxies according to their morphology. We compared physical and structural parameters of galaxies in the two environments and we derived the relationships between effective radius, surface brightness, stellar mass, and stellar mass density {Sigma}_R_e__ within the effective radius and central mass density {Sigma}_1kpc_, within 1kpc radius. We find that the structure and the properties of cluster elliptical galaxies do not differ from those in the field: they are characterized by the same structural parameters at fixed mass and they follow the same scaling relations. On the other hand, the population of field elliptical galaxies at z~1.3 shows a significant lack of massive (M_*_>2x10^11^M_{sun}_) and large (R_e_>4-5kpc) elliptical galaxies with respect to the cluster. Nonetheless, at M_*_<2x10^11^M_{sun}_, the two populations are similar. The size-mass relation of cluster and field ellipticals at z~1.3 clearly defines two different regimes, above and below a transition mass m_t_~=2-3x10^10^M_{sun}_ at lower masses the relation is nearly flat (R_e_{prop}M*^-0.1+/-0.2^), the mean radius is nearly constant at ~1kpc and, consequently, {Sigma}_Re_~={Sigma}_1kpc_ while, at larger masses, the relation is R_e_{prop}M*^0.64+/-0.09^. The transition mass marks the mass at which galaxies reach the maximum stellar mass density. Also the {Sigma}_1kpc_-mass relation follows two different regimes, above and below the transition mass ({Sigma}_1kpc_{prop}M*_1.07<mt_^0.64>mt^) defining a transition mass density {Sigma}_1kpc_~=2-3x10^3^M_{sun}_/pc^2^. The effective stellar mass density {Sigma}_Re_ does not correlate with mass; dense/compact galaxies can be assembled over a wide mass regime, independently of the environment. The central stellar mass density, {Sigma}_1kpc_, besides being correlated with the mass, is correlated to the age of the stellar population: the higher the central stellar mass density, the higher the mass, the older the age of the stellar population. While we found some evidence of environmental effects on the elliptical galaxies as a population, we did not find differences between the intrinsic properties of cluster and field elliptical galaxies at comparable redshift. The structure and the shaping of elliptical galaxies at z~1.3 do not depend on the environment. However, a dense environment seems to be more efficient in assembling high-mass large ellipticals, much rarer in the field at this redshift. The correlation found between the central stellar mass density and the age of the galaxies beside the mass shows the close connection of the central regions to the main phases of mass growth.
- ID:
- ivo://CDS.VizieR/J/MNRAS/403/996
- Title:
- Clusters and associations in SMC and LMC
- Short Name:
- J/MNRAS/403/996
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the degree of spatial correlation among extended structures in the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC). To this purpose, we work with subsamples characterized by different properties such as age and size, taken from the updated catalogue of Bica et al. (2008, Cat. J/MNRAS/389/678), or gathered in the present work. The structures are classified as star clusters or non-clusters (basically, nebular complexes and their stellar associations).
- ID:
- ivo://CDS.VizieR/J/A+A/517/A54
- Title:
- 20cm survey of the AKARI NEP
- Short Name:
- J/A+A/517/A54
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Westerbork Radio Synthesis Telescope, WSRT, has been used to make a deep radio survey of an ~1.7degree^2^ field coinciding with the AKARI north ecliptic pole deep field. The observations, data reduction and source count analysis are presented, along with a description of the overall scientific objectives. The survey consisted of 10 pointings, mosaiced with enough overlap to maintain a similar sensitivity across the central region that reached as low as 21uJy/beam at 1.4GHz.
- ID:
- ivo://CDS.VizieR/J/PASJ/73/487
- Title:
- C18O cores in Orion A
- Short Name:
- J/PASJ/73/487
- Date:
- 19 Jan 2022 00:24:20
- Publisher:
- CDS
- Description:
- We have performed an unbiased dense core survey toward the Orion A Giant Molecular Cloud in the C^18^O (J=1-0) emission line taken with the Nobeyama Radio Observatory (NRO) 45 m telescope. The effective angular resolution of the map is 26", which corresponds to ~0.05pc at a distance of 414pc. By using the Herschel-Planck H_2_ column density map, we calculate the C^18^O fractional abundance and find that it is roughly constant over the column density range of <~5x10^22^cm^-3^, although a trend of C^18^O depletion is determined toward higher column density. Therefore, C^18^O intensity can follow the cloud structure reasonably well. The mean C^18^O abundance in Orion A is estimated to be 5.7x10^-7^, which is about three times larger than the fiducial value. We identified 746 C^18^O cores with astrodendro and classified 709 cores as starless cores. We compute the core masses by decomposing the Herschel-Planck dust column density using the relative proportions of the C^18^O integrated intensities of line-of-sight components. Applying this procedure, we attempt to remove the contribution of the background emission, i.e., the ambient gas outside the cores. Then, we derived mass function for starless cores and found that it resembles the stellar initial mass function (IMF). The CMF for starless cores, dN/dM, is fitted with a power-law relation of M^{alpha}^ with a power index of {alpha}=-2.25+/-0.16 at the high-mass slope (>~0.44M_{sun}_). We also found that the ratio of each core mass to the total mass integrated along the line of sight is significantly large. Therefore, in the previous studies, the core masses derived from the dust image are likely to be overestimated by at least a factor of a few. Accordingly, such previous studies may underestimate the star formation efficiency of individual cores.
- ID:
- ivo://CDS.VizieR/J/ApJ/720/555
- Title:
- COLA. III. AGN in compact IR galaxies
- Short Name:
- J/ApJ/720/555
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from 4.8GHz Very Large Array (VLA) and global very long baseline interferometry (VLBI) observations of the northern half of the moderate FIR luminosity (median L_IR_=10^11.01^L_{sun}_) COLA (Compact Objects in Low-power AGNs) sample of star-forming galaxies. VLBI sources are detected in a high fraction (20/90) of the galaxies observed. The radio luminosities of these cores (~10^21^W/Hz) are too large to be explained by radio supernovae or supernova remnants and we argue that they are instead powered by active galactic nuclei (AGNs). These sub-parsec scale radio cores are preferentially detected toward galaxies whose VLA maps show bright 100-500 parsec scale nuclear radio components. Since these latter structures tightly follow the FIR to radio-continuum correlation for star formation, we conclude that the AGN-powered VLBI sources are associated with compact nuclear starburst environments. The implications for possible starburst-AGN connections are discussed. The detected VLBI sources have a relatively narrow range of radio luminosity consistent with models in which intense compact Eddington-limited starbursts regulate the gas supply onto a central supermassive black hole. The high incidence of AGN radio cores in compact starbursts suggests little or no delay between the starburst phase and the onset of AGN activity.
118. COLD GASS survey
- ID:
- ivo://CDS.VizieR/J/MNRAS/415/32
- Title:
- COLD GASS survey
- Short Name:
- J/MNRAS/415/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We are conducting COLD GASS, a legacy survey for molecular gas in nearby galaxies. Using the IRAM 30-m telescope, we measure the CO(1-0) line in a sample of ~350 nearby (D_I_~=100-200Mpc), massive galaxies (log(M*/M_{sun}_)>10.0). The sample is selected purely according to stellar mass, and therefore provides an unbiased view of molecular gas in these systems. By combining the IRAM data with Sloan Digital Sky Survey (SDSS) photometry and spectroscopy, GALEX imaging and high-quality Arecibo HI data, we investigate the partition of condensed baryons between stars, atomic gas and molecular gas in 0.1-10L* galaxies. In this paper, we present CO luminosities and molecular hydrogen masses for the first 222 galaxies. Description: To overcome this issue, the GALEX Arecibo SDSS Survey (GASS; Catinella et al. 2010, Cat. J/MNRAS/403/683) was designed to measure the neutral hydrogen content for a large, unbiased sample of ~1000 massive galaxies (M*>10^10^M_{sun}_), via longer pointed observations. GASS is a large programme currently under way at the Arecibo 305-m telescope, and is producing some of the first unbiased atomic gas scaling relations in the nearby Universe (Catinella et al. 2010, Cat. J/MNRAS/403/683; Schiminovich et al., 2010MNRAS.408..919S; Fabello et al., 2011MNRAS.411..993F). We are in the process of constructing a CO Legacy Data base for the GASS survey (COLD GASS), measuring the molecular gas content of a significant subsample of the GASS galaxies. We will then be able to quantify the link between atomic gas, molecular gas and stars in these systems.
- ID:
- ivo://CDS.VizieR/J/MNRAS/411/2439
- Title:
- Coma Treasury Survey. Structural parameters
- Short Name:
- J/MNRAS/411/2439
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalogue of structural parameters for 8814 galaxies in the 25 fields of the Hubble Space Telescope/ACS Coma Treasury Survey. Parameters from Sersic fits to the two-dimensional surface brightness distributions are given for all galaxies from our published Coma photometric catalogue with mean effective surface brightness brighter than 26.0mag/arcsec^2^ and brighter than 24.5mag (equivalent to absolute magnitude -10.5), as given by the fits, all in F814W(AB). The sample comprises a mixture of Coma members and background objects; 424 galaxies have redshifts and of these 163 are confirmed members. The fits were carried out using both the GIM2D and GALFIT codes.
- ID:
- ivo://CDS.VizieR/J/MNRAS/390/819
- Title:
- Combined NVSS-FIRST Galaxies (CoNFIG) sample
- Short Name:
- J/MNRAS/390/819
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The CoNFIG (Combined NVSS-FIRST Galaxies) sample is a new sample of 274 bright radio sources at 1.4GHz. It was defined by selecting all sources with S1.4GHz-1.3Jy from the NRAO Very Large Array (VLA) Sky Survey (NVSS) in the north field of the Faint Images of the Radio Sky at Twenty centimetres (FIRST) survey. New radio observations obtained with the VLA for 31 of the sources are presented. The sample has complete Fanaroff-Riley (FRI)/FRII morphology identification; optical identifications and redshifts are available for 80 and 89 per cent of the sample, respectively, yielding a mean redshift of ~0.71. One of the goals of this survey is to get better definitions of luminosity distributions and source counts of FRI/FRII sources separately, in order to determine the evolution of the luminosity function for each type of source. We present a preliminary analysis, showing that these data are an important step towards examining various evolutionary schemes for these objects and to confirm or correct the dual population unified scheme for radio active galactic nuclei (AGN). Improving our understanding of radio galaxy evolution will give better insight into the role of AGN feedback in galaxy formation.
