- ID:
- ivo://CDS.VizieR/J/other/BSAO/40.5
- Title:
- RATAN-600 RC radio sources
- Short Name:
- J/other/BSAO/40.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use the RATAN-600 radio telescope for picking up the most distant objects in the Universe. As a first step, about 100 steep spectrum FRII radio galaxies (SS FRII RG) from the RATAN-600 RC catalog (Parijskij et al., 1991, Cat. <J/A+AS/87/1>; 1992A&AS...96..583P) were mapped by the VLA and identified with optical objects down to 24-25 R mag. All the VLA images and all the deep CCD images of the RC SS fields, collected up to now, are given. An updated list of calibrators with the known redshifts of the same SS FRII class RGs was compiled to estimate photometric redshifts, redshifts from angular size - redshift relations and by the radio "standard candle" method. The mean redshift of the RC SS FRII RG list happened to be greater than 2. BVRI photometry was made, and by standard model fittings we estimated "color" redshifts and the ages of stellar systems of the parent gE galaxies in 14 cases. Several objects were found in which active star formation began in the first billion years after the Big Bang. We believe that more than 10000 of such old active galaxies are available on the sky and all of them are in the range of present day optical and radio facilities.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/616/L10
- Title:
- RCW120 fragmentation at 0.01pc scale
- Short Name:
- J/A+A/616/L10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Little is known about how high-mass stars form. Around 30% of the young high-mass stars in the Galaxy are observed at the edges of ionized (HII) regions. Therefore these are places of choice to study the earliest stages of high-mass star formation, especially towards the most massive condensations. High-spatial resolution observations in the millimeter range might reveal how these stars form and how they assemble their mass. We want to study the fragmentation process down to the 0.01pc scale in the most massive condensation (1700M_{sun}_) observed at the south-western edge of the HII region RCW 120 where the most massive Herschel cores (~124M_{sun}_ in average) could form high-mass stars. Using ALMA 3mm continuum observations towards the densest and most massive millimetric condensation (Condensation 1) of RCW 120, we used the getimages and getsources algorithms to extract the sources detected with ALMA and obtained their physical parameters. The fragmentation of the Herschel cores is discussed through their Jeans mass to understand the properties of the future stars. We extracted 18 fragments from the ALMA continuum observation at 3mm towards 8 cores detected with Herschel, whose mass and deconvolved size range from 2M_{sun}_ to 32M_{sun}_ and from 1.6mpc to 28.8mpc, respectively. The low degree of fragmentation observed, regarding to the thermal Jeans fragmentation, suggests that the observed fragmentation is inconsistent with ideal gravitational fragmentation and other ingredients such as turbulence or magnetic fields should be added in order to explain it. Finally, the range of fragments' mass indicates that the densest condensation of RCW 120 is a favourable place for the formation of high-mass stars with the presence of a probable UCHII region associated with the 27M_{sun}_ Fragment 1 of Core 2.
- ID:
- ivo://CDS.VizieR/J/MNRAS/442/533
- Title:
- Recently quenched elliptical galaxies in SDSS
- Short Name:
- J/MNRAS/442/533
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use the Sloan Digital Sky Survey to investigate the properties of massive elliptical galaxies in the local Universe (z<=0.08) that have unusually blue optical colours. Through careful inspection, we distinguish elliptical from non-elliptical morphologies among a large sample of similarly blue galaxies with high central light concentrations (c_r_>=2.6). These blue ellipticals comprise 3.7 per cent of all c_r>=2.6 galaxies with stellar masses between 10^10^ and 10^11^h^-2^M_{sun}_. Using published fibre spectrum diagnostics, we identify a unique subset of 172 non-star-forming ellipticals with distinctly blue urz colours and young (<3Gyr) light-weighted stellar ages. These recently quenched ellipticals (RQEs) have a number density of 2.7-4.7x10^-5^h^3^/Mpc^3^ and sufficient numbers above 2.5x10^10^h^-2^M_{sun}_ to account for more than half of the expected quiescent growth at late cosmic time assuming that this phase lasts 0.5Gyr. RQEs have properties that are consistent with a recent merger origin (i.e. they are strong 'first-generation' elliptical candidates), yet few involved a starburst strong enough to produce an E+A signature. The preferred environment of RQEs (90 per cent reside at the centres of <3x10^12^h^-1^M_{sun}_ groups) agrees well with the 'small group scale' predicted for maximally efficient spiral merging on to their halo centre and rules out satellite-specific quenching processes. The high incidence of Seyfert and LINER activity in RQEs and their plausible descendants may heat the atmospheres of small host haloes sufficiently to maintain quenching.
- ID:
- ivo://CDS.VizieR/J/MNRAS/456/3899
- Title:
- Red galaxies with pseudo-bulges in the SDSS
- Short Name:
- J/MNRAS/456/3899
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Pseudo-bulges are expected to markedly differ from classical quasi-monolithically forming bulges in their star formation history (SFH) and chemical abundance patterns. To test this simple expectation, we carry out a comparative structural and spectral synthesis analysis of 10^6^ red massive galaxies issued from the Sloan Digital Sky Survey (SDSS), sub-divided into bulgeless, pseudo-bulge and classical bulge galaxies according to their photometric characteristics, and further obeying a specific selection to minimize uncertainties in the analysis and ensure an unbiased derivation and comparison of SFHs. Our 2D photometry analysis suggests that discs underlying pseudo-bulges typically have larger exponential scalelengths than bulgeless galaxies, despite similar integral disc luminosities. Spectral synthesis models of the stellar emission within the 3-arcsec SDSS fibre aperture reveal a clear segregation of bulgeless and pseudo-bulge galaxies from classical bulges on the luminosity-weighted planes of age-metallicity and mass-metallicity, though a large dispersion is observed within the two former classes. The secular growth of pseudo-bulges is also reflected upon their cumulative stellar mass as a function of time, which is shallower than that for classical bulges. Such results suggest that the centres of bulgeless and pseudo-bulge galaxies substantially differ from those of bulgy galaxies with respect to their SFH and chemical enrichment history, which likely points to different formation/assembly mechanisms.
- ID:
- ivo://CDS.VizieR/J/ApJS/157/1
- Title:
- Red-Sequence Cluster Survey
- Short Name:
- J/ApJS/157/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Red-Sequence Cluster Survey (RCS) is a ~100{deg}^2^, two-filter imaging survey in the R_C_ and z' filters, designed primarily to locate and characterize galaxy clusters to redshifts as high as z=1.4. This paper provides a detailed description of the survey strategy and execution, including a thorough discussion of the photometric and astrometric calibration of the survey data. These catalogs, representing about 10% of the total survey and comprising a total of 429 candidate clusters and groups, contain a total of 67 cluster candidates at a photometric redshift of 0.9<z<1.4, down to the chosen significance threshold of 3.29{sigma}.
- ID:
- ivo://CDS.VizieR/J/A+A/391/887
- Title:
- Redshifts in the Hydra/Antlia Extension
- Short Name:
- J/A+A/391/887
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As part of our program to map the large-scale distribution of galaxies behind the Milky Way, we used the Parkes 210 ft (64m) radio telescope for pointed HI observations of a sample of low surface-brightness (due to heavy obscuration) spiral galaxies selected from the deep optical Zone of Avoidance (ZOA) galaxy catalog in the Hydra/Antlia region (Kraan-Korteweg, 2000, Cat. <J/A+AS/141/123>). Searching a simultaneous velocity range of either 300 to 5500km/s or 300 to 10500km/s to an rms level of typically 2-4mJy resulted in detections in 61 of the 139 pointings, leading to a total of 66 detections (an additional detection was made in a reference position, and two other pointings revealed two and four independent signals respectively). Except for 2 strong HI emitters identified in the shallow Zone of Avoidance HI survey (Henning et al., 2000AJ....119.2686H), all HI detections are new.
- ID:
- ivo://CDS.VizieR/J/AJ/148/13
- Title:
- Redshifts of 65 CANDELS supernovae
- Short Name:
- J/AJ/148/13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) was a multi-cycle treasury program on the Hubble Space Telescope (HST) that surveyed a total area of ~0.25deg^2^ with ~900 HST orbits spread across five fields over three years. Within these survey images we discovered 65 supernovae (SNe) of all types, out to z~2.5. We classify ~24 of these as Type Ia SNe (SNe Ia) based on host galaxy redshifts and SN photometry (supplemented by grism spectroscopy of six SNe). Here we present a measurement of the volumetric SN Ia rate as a function of redshift, reaching for the first time beyond z=2 and putting new constraints on SN Ia progenitor models. Our highest redshift bin includes detections of SNe that exploded when the universe was only ~3Gyr old and near the peak of the cosmic star formation history. This gives the CANDELS high redshift sample unique leverage for evaluating the fraction of SNe Ia that explode promptly after formation (<500Myr). Combining the CANDELS rates with all available SN Ia rate measurements in the literature we find that this prompt SN Ia fraction is f_p_=0.53_stat0.10sys0.26_^+/-0.09 +/-0.10^, consistent with a delay time distribution that follows a simple t^-1^ power law for all times t>40Myr. However, mild tension is apparent between ground-based low-z surveys and space-based high-z surveys. In both CANDELS and the sister HST program CLASH (Cluster Lensing And Supernova Survey with Hubble), we find a low rate of SNe Ia at z>1. This could be a hint that prompt progenitors are in fact relatively rare, accounting for only 20% of all SN Ia explosions--though further analysis and larger samples will be needed to examine that suggestion.
- ID:
- ivo://CDS.VizieR/J/other/Sci/338.1445
- Title:
- Relativistic jets from black hole systems
- Short Name:
- J/other/Sci/338.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Black holes generate collimated, relativistic jets, which have been observed in {gamma}-ray bursts (GRBs), microquasars, and at the center of some galaxies [active galactic nuclei (AGN)]. How jet physics scales from stellar black holes in GRBs to the supermassive ones in AGN is still unknown. Here, we show that jets produced by AGN and GRBs exhibit the same correlation between the kinetic power carried by accelerated particles and the {gamma}-ray luminosity, with AGN and GRBs lying at the low- and high-luminosity ends, respectively, of the correlation. This result implies that the efficiency of energy dissipation in jets produced in black hole systems is similar over 10 orders of magnitude in jet power, establishing a physical analogy between AGN and GRBs.
- ID:
- ivo://CDS.VizieR/J/AJ/133/2357
- Title:
- Relativistic jets in the RRFID database
- Short Name:
- J/AJ/133/2357
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of an analysis of relativistic jet apparent speeds from VLBI images in the Radio Reference Frame Image Database (RRFID). The images are snapshot VLBI images at 8 and 2GHz using the VLBA, plus up to 10 additional antennas that provide global VLBI coverage. We have analyzed the 8GHz images from the first 5 years of the database (1994-1998), for all sources observed at three or more epochs during this time range. This subset comprises 966 images of 87 sources. The sources in this subset have an average of 11 epochs of observation over the years 1994-1998, with the best-observed sources having 19 epochs. About half of the sources in this RRFID kinematic survey have not been previously studied with multi-epoch VLBI observations. We have measured apparent speeds for a total of 184 jet components in 77 sources, of which the best-measured 94 component speeds in 54 sources are used in the final analysis.
- ID:
- ivo://CDS.VizieR/J/MNRAS/436/275
- Title:
- Relaxation parameter of 2092 rich galaxy clusters
- Short Name:
- J/MNRAS/436/275
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Dynamical state of galaxy clusters is closely related to their observational properties in X-ray, optical and radio wavelengths. We develop a method to diagnose the substructure and dynamical state of galaxy clusters by using photometric data of Sloan Digital Sky Survey (SDSS). To trace mass distribution, the brightness distribution of member galaxies is smoothed by using a Gaussian kernel with a weight of their optical luminosities. After deriving the asymmetry, the ridge flatness and the normalized deviation of the smoothed optical map, we define a relaxation parameter, {Gamma}, to quantify dynamical state of clusters. This method is applied to a test sample of 98 clusters of 0.05<z<~0.42 collected from literature with known dynamical states and can recognize dynamical state for relaxed ({Gamma}>=0) and unrelaxed ({Gamma}<0) clusters with a success rate of 94 percent. We then calculate relaxation parameters of 2092 rich clusters previously identified from the SDSS, of which 28 percent clusters are dynamically relaxed with {Gamma}>=0. We find that the dominance and absolute magnitude of the brightest cluster galaxies closely correlate with dynamical states of clusters. The emission power of radio haloes is quantitatively related to cluster dynamical state, beside the known dependence on the X-ray luminosity.
