- ID:
- ivo://CDS.VizieR/J/ApJ/744/84
- Title:
- Combined sample of radio-loud AGNs at 408MHz
- Short Name:
- J/ApJ/744/84
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The work in this paper aims at determining the evolution and possible co-evolution of radio-loud active galactic nuclei (AGNs) and their cores via their radio luminosity functions (i.e., total and core RLFs, respectively). Using a large combined sample of 1063 radio-loud AGNs selected at low radio frequency, we investigate the RLF (radio luminosity function) at 408MHz of steep-spectrum radio sources. Our results support a luminosity-dependent evolution. Using core flux density data of the complete sample 3CRR (Laing et al., 1983, Cat. J/MNRAS/204/151; see also Cat. VIII/1), we investigate the core RLF at 5.0GHz. Based on the combined sample with incomplete core flux data, we also estimate the core RLF using a modified factor of completeness. Both results are consistent and show that the comoving number density of radio cores displays a persistent decline with redshift, implying a negative density evolution. We find that the core RLF is obviously different from the total RLF at the 408 MHz band which is mainly contributed by extended lobes, implying that the cores and extended lobes could not be co-evolving at radio emission.
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- ID:
- ivo://CDS.VizieR/J/A+A/618/A157
- Title:
- Compact Groups in SDSSDR12
- Short Name:
- J/A+A/618/A157
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A catalogue of compact groups identified on the SDSS DR12 is provided. Compact Groups were identified in redshift space with a modified Hickson-like algorithm. The catalogue comprises 462 compact groups of which 406 clearly fulfil all the compact group requirements: compactness, isolation and velocity concordance of all of their members. The remaining 56 groups need further redshift information of potentially contaminating sources.
- 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/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/ApJS/81/83
- Title:
- Compendium of Radio Spectra and Luminosities
- Short Name:
- J/ApJS/81/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog is a complete sample of 256 powerful extragalactic radio sources. The catalog includes source identification, redshift, luminosities and spectral indices at standard rest frequencies as well as bolometric luminosities between emitted frequencies of 10 MHz and 100 GHz. The paper also includes fits to the measured radio spectra which have not been included in this catalog.
- ID:
- ivo://CDS.VizieR/J/ApJ/755/31
- Title:
- Compilation of 122 strong gravitational lenses
- Short Name:
- J/ApJ/755/31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the redshift distribution of two samples of early-type gravitational lenses, extracted from a larger collection of 122 systems, to constrain the cosmological constant in the {Lambda}CDM model and the parameters of a set of alternative dark energy models (XCDM, Dvali-Gabadadze-Porrati, and Ricci dark energy models), in a spatially flat universe. The likelihood is maximized for {Omega}_{Lambda}_=0.70+/-0.09 when considering the sample excluding the Sloan Lens ACS systems (known to be biased toward large image-separation lenses) and no-evolution, and {Omega}_{Lambda}_=0.81+/-0.05 when limiting to gravitational lenses with image separation {Delta}{theta}>2" and no-evolution. In both cases, results accounting for galaxy evolution are consistent within 1{sigma}. The present test supports the accelerated expansion, by excluding the null hypothesis (i.e., {Omega}_{Lambda}_=0) at more than 4{sigma}, regardless of the chosen sample and assumptions on the galaxy evolution. A comparison between competitive world models is performed by means of the Bayesian information criterion. This shows that the simplest cosmological constant model--that has only one free parameter--is still preferred by the available data on the redshift distribution of gravitational lenses. We perform an analysis of the possible systematic effects, finding that the systematic errors due to sample incompleteness, galaxy evolution, and model uncertainties approximately equal the statistical errors, with present-day data. We find that the largest sources of systemic errors are the dynamical normalization and the high-velocity cutoff factor, followed by the faint-end slope of the velocity dispersion function.
- ID:
- ivo://CDS.VizieR/J/ApJ/886/124
- Title:
- Completed KMOS^3D^ survey NIR obs.
- Short Name:
- J/ApJ/886/124
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the completed KMOS^3D^ survey, an integral field spectroscopic survey of 739 log(M_*_/M_{sun}_)>9 galaxies at 0.6<z<2.7 using the K-band Multi Object Spectrograph (KMOS) at the Very Large Telescope. The KMOS3D survey provides a population-wide census of kinematics, star formation, outflows, and nebular gas conditions both on and off the star-forming galaxy main sequence through the spatially resolved and integrated properties of H{alpha}, [NII], and [SII] emission lines. We detect H{alpha} emission for 91% of galaxies on the main sequence of star formation and 79% overall. The depth of the survey has allowed us to detect galaxies with star formation rates below 1M_{sun}_/yr, as well as to resolve 81% of detected galaxies with >=3 resolution elements along the kinematic major axis. The detection fraction of H{alpha} is a strong function of both color and offset from the main sequence, with the detected and nondetected samples exhibiting different spectral energy distribution shapes. Comparison of H{alpha} and UV+IR star formation rates reveal that dust attenuation corrections may be underestimated by 0.5dex at the highest masses (log(M_*_/M_{sun}_)>10.5). We confirm our first year results of a high rotation-dominated fraction (monotonic velocity gradient and v_rot_/{sigma}_0_>3.36^0.5^) of 77% for the full KMOS^3D^ sample. The rotation-dominated fraction is a function of both stellar mass and redshift, with the strongest evolution measured over the redshift range of the survey for galaxies with log(M_*_/M_{sun}_)<10.5.
- ID:
- ivo://CDS.VizieR/J/ApJ/475/469
- Title:
- Composite HST Spectrum of Quasars
- Short Name:
- J/ApJ/475/469
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We construct a composite quasar spectrum from 284 HST FOS spectra of 101 quasars with redshifts z>0.33. The spectrum covers the wavelengths between 350 and 3000A in the rest frame, with a peak S/N level of ~130 per A at ~1200A. Since ~90% of the sample quasars have redshift z<1.5, the spectrum is suitable for studying the wavelength region shortward of Ly{alpha} without large effects from intervening Ly{alpha} forest absorption. Data in the waveband between 350 and 600A are mainly from the spectra of z>1.5 quasars, for which significant corrections for the accumulated Lyman-series line and continuum absorption have been applied. There is a significant steepening of the continuum slope around 1050A. The continuum between 1050 and 2200A can be modeled as a power law f_{nu} proportional to {nu}_{alpha}_ with {alpha}=-0.99+/-0.05. For the full sample the power-law index in the extreme ultraviolet (EUV) between 350 and 1050A is {alpha}=-1.96+/-0.15. For the radio-loud subsample (60 objects), the EUV spectral index is {alpha}~=-2.2, while for the radio-quiet subsample (41 objects) it is {alpha}~=-1.8. The continuum flux in the wavelengths near the Lyman limit shows a depression of ~10%. The break in the power-law index and the slight depression of the continuum near the Lyman limit are features expected in Comptonized accretion-disk spectra. Comptonization produces a power-law tail in the wavelength band shortward of 1000A and smears out the Lyman-limit edge of the intrinsic accretion-disk spectrum. In the EUV waveband, we detect several possible emission features, including one around 690A that may be O III + N III produced by the Bowen fluorescence effect. Comparing our composite spectrum with one made at higher redshifts by Francis et al. (1991ApJ...373..465F), we find that the equivalent widths of Ly{alpha} and high-ionization emission lines are larger in our sample, reflecting a known luminosity dependence. The equivalent widths of low-ionization lines do not exhibit such a dependence, suggesting that the quasar EUV continuum above ~50eV is steeper at higher luminosity. Radio-quiet quasars appear to show a slightly harder continuum and lower ionization levels in their emission lines.
- ID:
- ivo://CDS.VizieR/J/ApJ/815/L13
- Title:
- Compton-thick AGNs from the 70-month Swift/BAT cat.
- Short Name:
- J/ApJ/815/L13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Heavily obscured accretion is believed to represent an important stage in the growth of supermassive black holes and to play an important role in shaping the observed spectrum of the cosmic X-ray background. Hard X-ray (E>10keV) selected samples are less affected by absorption than samples selected at lower energies, and are therefore one of the best ways to detect and identify Compton-thick (CT, logN_H_>=24) active galactic nuclei (AGNs). In this letter we present the first results of the largest broadband (0.3-150keV) X-ray spectral study of hard X-ray selected AGNs to date, focusing on the properties of heavily obscured sources. Our sample includes the 834 AGNs (728 non-blazar, average redshift z~0.055) reported in the 70-month catalog of the all-sky hard X-ray Swift/Burst Alert Monitor survey. We find 55 CT AGNs, which represent 7.6_-2.1_^+1.1^% of our non-blazar sample. Of these, 26 are reported as candidate CT AGNs for the first time. We correct for selection bias and derive the intrinsic column density distribution of AGNs in the local universe in two different luminosity ranges. We find a significant decrease in the fraction of obscured Compton-thin AGNs for increasing luminosity, from 46+/-3% (for logL_14-195_=40-43.7) to 39+/-3% (for logL_14-195_=43.7-46). A similar trend is also found for CT AGNs. The intrinsic fraction of CT AGNs with logN_H_=24-25 normalized to unity in the logN_H_=20-25 range is 27+/-4%, and is consistent with the observed value obtained for AGNs located within 20Mpc.
- ID:
- ivo://CDS.VizieR/J/ApJ/890/148
- Title:
- Concentration-mass relation for XXL clusters
- Short Name:
- J/ApJ/890/148
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a weak-lensing analysis of X-ray galaxy groups and clusters selected from the XMM-XXL survey using the first-year data from the Hyper Suprime-Cam (HSC) Subaru Strategic Program. Our joint weak-lensing and X-ray analysis focuses on 136 spectroscopically confirmed X-ray-selected systems at 0.031<=z<=1.033 detected in the 25deg^2^ XXL-N region, which largely overlaps with the HSC-XMM field. With high-quality HSC weak-lensing data, we characterize the mass distributions of individual clusters and establish the concentration-mass (c-M) relation for the XXL sample, by accounting for selection bias and statistical effects and marginalizing over the remaining mass calibration uncertainty. We find the mass-trend parameter of the c-M relation to be {beta}=-0.07+/-0.28 and the normalization to be c_200_=4.8+/-1.0(stat)+/-0.8(syst) at M_200_=10^14^h^-1^M_{sun}_ and z=0.3. We find no statistical evidence for redshift evolution. Our weak-lensing results are in excellent agreement with dark-matter-only c-M relations calibrated for recent {Lambda}CDM cosmologies. The level of intrinsic scatter in c200 is constrained as {sigma}(lnc_200_)<24% (99.7% CL), which is smaller than predicted for the full population of {Lambda}CDM halos. This is likely caused in part by the X-ray selection bias in terms of the cool-core or relaxation state. We determine the temperature-mass (T_X_-M_500_) relation for a subset of 105 XXL clusters that have both measured HSC lensing masses and X-ray temperatures. The resulting TX-M500 relation is consistent with the self-similar prediction. Our TX-M500 relation agrees with the XXL DR1 results at group scales but has a slightly steeper mass trend, implying a smaller mass scale in the cluster regime. The overall offset in the TX-M500 relation is at the ~1.5{sigma} level, corresponding to a mean mass offset of 34%+/-20%. We also provide bias-corrected, weak-lensing-calibrated M200 and M500 mass estimates of individual XXL clusters based on their measured X-ray temperatures.
