- 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.
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- ID:
- ivo://CDS.VizieR/J/AJ/126/2152
- Title:
- Cluster And Infall Region Nearby Survey. I
- Short Name:
- J/AJ/126/2152
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The CAIRNS (Cluster and Infall Region Nearby Survey) project is a spectroscopic survey of the infall regions surrounding eight nearby, rich, X-ray-luminous clusters of galaxies. We have collected 15654 redshifts (3471 new or remeasured) within ~5-10h^-1^Mpc of the centers of the clusters, making it the largest study of the infall regions of clusters. We determine cluster membership and the mass profiles of the clusters based on the phase-space distribution of the galaxies. All of the clusters display decreasing velocity dispersion profiles. The mass profiles are fitted well by functional forms based on numerical simulations but exclude an isothermal sphere. Specifically, Navarro et al. (1997ApJ...490..493N) and Hernquist (1990ApJ...356..359H) models provide good descriptions of cluster mass profiles to their turnaround radii. Our sample shows that the predicted infall pattern is ubiquitous in rich, X-ray-luminous clusters over a large mass range. The caustic mass estimates are in excellent agreement with independent X-ray estimates at small radii and with virial estimates at intermediate radii. The mean ratio of the caustic mass to the X-ray mass is 1.03+/-0.11, and the mean ratio of the caustic mass to the virial mass (when corrected for the surface pressure term) is 0.93+/-0.07. We further demonstrate that the caustic technique provides reasonable mass estimates even in merging clusters.
- ID:
- ivo://CDS.VizieR/J/AJ/128/1078
- Title:
- Cluster and Infall Region Nearby Survey. II
- Short Name:
- J/AJ/128/1078
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CAIRNS (Cluster and Infall Region Nearby Survey) is a spectroscopic survey of the infall regions surrounding nine nearby rich clusters of galaxies. In our previous paper (Cat. <J/AJ/126/2152>), we used redshifts within ~10h_-1_ Mpc of the centers of the clusters to determine the mass profiles of the clusters based on the phase-space distribution of the galaxies. Here, we use Two Micron All Sky Survey (Cat. <II/246>) photometry and an additional 515 redshifts to investigate the environmental dependence of near-infrared mass-to-light ratios.
- ID:
- ivo://CDS.VizieR/J/A+A/614/A82
- Title:
- Cluster candidates for joint X-rays and SZ surveys
- Short Name:
- J/A+A/614/A82
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The combination of X-ray and Sunyaev-Zeldovich (SZ) observations can potentially improve the cluster detection efficiency, when compared to using only one of these probes, since both probe the same medium, the hot ionized gas of the intra-cluster medium. We present a method based on matched multifrequency filters (MMF) for detecting galaxy clusters from SZ and X-ray surveys. This method builds on a previously proposed joint X-ray-SZ extraction method and allows the blind detection of clusters, that is finding new clusters without knowing their position, size, or redshift, by searching on SZ and X-ray maps simultaneously. The proposed method is tested using data from the ROSAT all-sky survey and from the Planck survey. The evaluation is done by comparison with existing cluster catalogues in the area of the sky covered by the deep SPT survey. Thanks to the addition of the X-ray information, the joint detection method is able to achieve simultaneously better purity, better detection efficiency, and better position accuracy than its predecessor Planck MMF, which is based on SZ maps alone. For a purity of 85%, the X-ray-SZ method detects 141 confirmed clusters in the SPT region; to detect the same number of confirmed clusters with Planck MMF, we would need to decrease its purity to 70%. We provide a catalogue of 225 sources selected by the proposed method in the SPT footprint, with masses ranging between 0.7 and 14.5x10^14^M_{sun}_ and redshifts between 0.01 and 1.2.
- ID:
- ivo://CDS.VizieR/J/AJ/160/239
- Title:
- Cluster difference imaging photometric survey. II.
- Short Name:
- J/AJ/160/239
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of TOI837b and its validation as a transiting planet. We characterize the system using data from the NASA Transiting Exoplanet Survey Satellite mission, the ESA Gaia mission, ground-based photometry from El Sauce and ASTEP400, and spectroscopy from CHIRON, FEROS, and Veloce. We find that TOI837 is a T=9.9mag G0/F9 dwarf in the southern open cluster IC2602. The star and planet are therefore 35_-5_^+11^ million years old. Combining the transit photometry with a prior on the stellar parameters derived from the cluster color-magnitude diagram, we find that the planet has an orbital period of 8.3days and is slightly smaller than Jupiter (R_p_=0.77_-0.07_^+0.09^R_Jup_). From radial velocity monitoring, we limit M_p_sin(i) to less than 1.20M_Jup_(3{sigma}). The transits either graze or nearly graze the stellar limb. Grazing transits are a cause for concern, as they are often indicative of astrophysical false-positive scenarios. Our follow-up data show that such scenarios are unlikely. Our combined multicolor photometry, high-resolution imaging, and radial velocities rule out hierarchical eclipsing binary scenarios. Background eclipsing binary scenarios, though limited by speckle imaging, remain a 0.2% possibility. TOI837b is therefore a validated adolescent exoplanet. The planetary nature of the system can be confirmed or refuted through observations of the stellar obliquity and the planetary mass. Such observations may also improve our understanding of how the physical and orbital properties of exoplanets change in time.
- ID:
- ivo://CDS.VizieR/J/A+A/650/A156
- Title:
- Cluster formation toward Be87/ON2. I.
- Short Name:
- J/A+A/650/A156
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Disentangling line-of-sight alignments of young stellar populations is crucial for observational studies of star-forming complexes. This task is particularly problematic in a Cygnus-X subregion where several components, located at different distances, overlap: the Berkeley 87 young massive cluster, the poorly known [DB2001] Cl05 embedded cluster, and the ON2 star-forming complex, which in turn is composed of several HII regions. We provide a methodology for building an exhaustive census of young objects that can consistently treat large differences in extinction and distance. OMEGA2000 near-infrared observations of the Berkeley 87 / ON2 field were merged with archival data from Gaia, Chandra, Spitzer, and Herschel, and with cross-identifications from the literature. To address the incompleteness effects and selection biases that arise from the line-of-sight overlap, we adapted existing methods for extinction estimation and young object classification. We also defined the intrinsic reddening index, R_int_, a new tool for separating intrinsically red sources from those whose infrared color excess is caused by extinction. Finally, we introduce a new method for finding young stellar objects based on R_int_. We find 571 objects whose classification is related to recent or ongoing star formation. Together with other point sources with individual estimates of distance or extinction, we compile a catalog of 3005 objects to be used for further membership work. A new distance for Berkeley 87, (1673+/-17)pc, is estimated as a median of 13 spectroscopic members with accurate Gaia EDR3 parallaxes. The flexibility of our approach, especially regarding the R_int_ definition, allows overcoming photometric biases caused by large variations in extinction and distance, in order to obtain homogeneous catalogs of young sources. The multiwavelength census that results from applying our methods to the Berkeley 87 / ON2 field will serve as a basis for disentangling the overlapped populations.
- ID:
- ivo://CDS.VizieR/J/MNRAS/351/265
- Title:
- Cluster galaxy circular velocity function
- Short Name:
- J/MNRAS/351/265
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present galaxy circular velocity functions (GCVFs) for 34 low-redshift (z<~0.15) clusters identified in the Sloan Digital Sky Survey (SDSS, Cat. <J/AJ/123/567>), for 15 clusters drawn from dark matter simulations of hierarchical structure growth in a {LAMBDA}CDM cosmology, and for ~22000 SDSS field galaxies. We find that the simulations successfully reproduce the shape, amplitude and scatter in the observed distribution of cluster galaxy circular velocities. The power-law slope of the observed cluster GCVF is ~-2.4, independent of cluster velocity dispersion. The average slope of the simulated GCVFs is somewhat steeper, although formally consistent given the errors. We find that the effects of baryons on galaxy rotation curves is to flatten the simulated cluster GCVF into better agreement with observations. The cumulative GCVFs of the simulated clusters are very similar across a wide range of cluster masses, provided individual subhalo circular velocities are scaled by the circular velocities of the parent cluster. The scatter is consistent with that measured in the cumulative, scaled observed cluster GCVF. Finally, the observed field GCVF deviates significantly from a power law, being flatter than the cluster GCVF at circular velocities less than 200km/s.
- ID:
- ivo://CDS.VizieR/J/AJ/133/2222
- Title:
- Clustering of high-redshift QSOs from SDSS
- Short Name:
- J/AJ/133/2222
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the two-point correlation function of a uniformly selected sample of 4426 luminous optical quasars with redshift 2.9<=z<=5.4 selected over 4041deg^2^ from the Fifth Data Release of the Sloan Digital Sky Survey. We fit a power-law to the projected correlation function w_p_(r_p_) to marginalize over redshift-space distortions and redshift errors.
- ID:
- ivo://CDS.VizieR/J/MNRAS/449/835
- Title:
- Clustering of the SDSS DR7 main galaxy sample. I.
- Short Name:
- J/MNRAS/449/835
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We create a sample of spectroscopically identified galaxies with z<0.2 from the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7, Cat. II/294), covering 6813 deg^2^. Galaxies are chosen to sample the highest mass haloes, with an effective bias of 1.5, allowing us to construct 1000 mock galaxy catalogues (described in Howlett et al. 2015MNRAS.449..848H), which we use to estimate statistical errors and test our methods. We use an estimate of the gravitational potential to "reconstruct" the linear density fluctuations, enhancing the baryon acoustic oscillation (BAO) signal in the measured correlation function and power spectrum. Fitting to these measurements, we determine D_V_(z_eff_=0.15)=(664+/-25)(r_d_/r_d_, _fid_) Mpc; this is a better than 4 per cent distance measurement. This "fills the gap" in BAO distance ladder between previously measured local and higher redshift measurements, and affords significant improvement in constraining the properties of dark energy. Combining our measurement with other BAO measurements from Baryon Oscillation Spectroscopic Survey and 6-degree Field Galaxy Redshift Survey galaxy samples provides a 15 per cent improvement in the determination of the equation of state of dark energy and the value of the Hubble parameter at z=0(H_0_). Our measurement is fully consistent with the Planck results and the {Lambda} cold dark matter concordance cosmology, but increases the tension between Planck+BAO H_0_ determinations and direct H_0_ measurements.
- ID:
- ivo://CDS.VizieR/J/A+A/610/A12
- Title:
- Clustering the Orion B giant molecular cloud
- Short Name:
- J/A+A/610/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Previous attempts at segmenting molecular line maps of molecular clouds have focused on using position-position-velocity data cubes of a single molecular line to separate the spatial components of the cloud. In contrast, wide field spectral imaging over a large spectral bandwidth in the (sub)mm domain now allows one to combine multiple molecular tracers to understand the different physical and chemical phases that constitute giant molecular clouds (GMCs). We aim at using multiple tracers (sensitive to different physical processes and conditions) to segment a molecular cloud into physically/ chemically similar regions (rather than spatially connected components), thus disentangling the different physical/chemical phases present in the cloud. We use a machine learning clustering method, namely the Meanshift algorithm, to cluster pixels with similar molecular emission, ignoring spatial information. Clusters are defined around each maximum of the multidimensional probability density function (PDF) of the line integrated intensities. Simple radiative transfer models were used to interpret the astrophysical information uncovered by the clustering analysis. A clustering analysis based only on the J=1-0 lines of three isotopologues of CO proves sufficient to reveal distinct density/column density regimes (n_H_~100cm^-3^, ~500cm^-3^, and >1000cm^-3^), closely related to the usual definitions of diffuse, translucent and high-column-density regions. Adding two UV-sensitive tracers, the J=1-0 line of HCO^+^ and the N=1-0 line of CN, allows us to distinguish two clearly distinct chemical regimes, characteristic of UV-illuminated and UV-shielded gas. The UV-illuminated regime shows overbright HCO^+^ and CN emission, which we relate to a photochemical enrichment effect. We also find a tail of high CN/HCO^+^ intensity ratio in UV-illuminated regions. Finer distinctions in density classes (n_H_~710^3^cm^-3^, ~410^4^cm^-3^) for the densest regions are also identified, likely related to the higher critical density of the CN and HCO^+^ (1-0) lines. These distinctions are only possible because the high-density regions are spatially resolved. Molecules are versatile tracers of GMCs because their line intensities bear the signature of the physics and chemistry at play in the gas. The association of simultaneous multi-line, wide-field mapping and powerful machine learning methods such as the Meanshift clustering algorithm reveals how to decode the complex information available in these molecular tracers.