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- ID:
- ivo://CDS.VizieR/I/325
- Title:
- Radio-optical reference frame link
- Short Name:
- I/325
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Between 1997 and 2004 several observing runs were conducted mainly with the CTIO 0.9m to image ICRF counterparts (mostly QSOs) in order to determine accurate optical positions. Contemporary to these deep CCD images the same fields were observed with the USNO astrograph in the same bandpass. These provide accurate positions on the Hipparcos/Tycho-2 system for stars in the 10 to 16 magnitude range used as reference stars for the deep CCD imaging data. Here we present final optical position results of 413 sources based on astrograph data reductions using UCAC2 and UCAC4 type reference stars. These optical positions are compared to radio VLBI positions. The current optical system is not perfectly aligned to the ICRF radio system with rigid body rotation angles of 3 to 5 mas (3{sigma}) found between them for all 3 axes. Furthermore, statistically, the optical-radio position differences are found to exceed the total, combined, known errors in the observations. Systematic errors in the optical reference stars as well as physical offsets between the centers of optical and radio emissions are both identified as likely causes. A detrimental, astrophysical, random noise (DARN) component is postulated to be on about the 10mas level. If confirmed by future observations, this could severely limit the Gaia to ICRF reference frame alignment accuracy to an error of about 0.5mas per coordinate axis with the current number of sources envisioned to provide the link. A list of 36 ICRF sources without the detection of an optical counterpart to a limiting magnitude of about R=22 is provided as well.
- ID:
- ivo://CDS.VizieR/J/A+A/493/317
- Title:
- Radio source selection for the ICRF
- Short Name:
- J/A+A/493/317
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The most accurate realization of a quasi inertial reference frame, the International Celestial Reference Frame (ICRF), is made of 212 defining extragalactic radio sources whose coordinates are determined using VLBI observations. Recent studies demonstrated however that using other sets of sources could improve the frame stability. This study examines a simple radio source selection scheme to define celestial reference frame axes more stable than the ones as currently defined by the ICRF. After having derived source coordinate time series from 26 years of VLBI observations, we select the most suitable sources on the basis of their positional variability (rms and slope), and observational history. We determine the axis stability of the frame defined by the selection, as well as its suitability for global geodetic VLBI analyses, i.e., determination of Earth orientation parameters and source and station coordinates.
- ID:
- ivo://CDS.VizieR/J/ApJS/140/239
- Title:
- RASS: clusters of galaxies around SGP
- Short Name:
- J/ApJS/140/239
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A field of 1.013sr in the ROSAT All-Sky Survey (RASS), centered on the south Galactic pole (SGP), has been searched in a systematic, objective manner for clusters of galaxies. The procedure relied on a correlation of the X-ray positions and properties of ROSAT sources in the field with the distribution of galaxies in the COSMOS digitized database, which was obtained from scanning the plates of the UK Schmidt IIIa-J optical survey of the southern sky. The study used the second ROSAT survey database (RASS-2) and included several optical observing campaigns to measure cluster redshifts. The search, which is a precursor to the larger REFLEX survey encompassing the whole southern sky, reached the detection limits of both the RASS and the COSMOS data and yielded a catalog of 186 clusters in which the lowest flux is 1.5x10-12ergs/cm^2^/s in the 0.1-2.4keV band. Of these 157 have measured redshifts. Using a flux limit of 3.0x10-12ergs/cm^2^/s a complete subset of 112 clusters was obtained, of which 110 have measured redshifts. The spatial distribution of the X-ray clusters out to a redshift of 0.15 shows an extension of the Local Supercluster to the Pisces-Cetus supercluster (z<0.07), and an orthogonal structure at higher redshift (0.07<z<0.15). This result is consistent with large-scale structure suggested by optical surveys.
585. RC2 Catalogue
- ID:
- ivo://CDS.VizieR/VII/112
- Title:
- RC2 Catalogue
- Short Name:
- VII/112
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This standardized documentation file does not contain a complete description of the electronic version of the RC2 catalogue; please refer to the "doc.tex" file prepared by Theresa A. Nagy and Robert S. Hill.
- ID:
- ivo://CDS.VizieR/J/AJ/108/2128
- Title:
- RC3 corrections and additions
- Short Name:
- J/AJ/108/2128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Lists of corrections and additions to the Third Reference Catalogue of Bright Galaxies (RC3, Cat. <VII/155>) are given. The corrected version of the catalogue (RC3.9b), dated April 1994, is currently available through the national data centers.
- 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/A+A/617/A53
- Title:
- Red-sequence early-type galaxies. II.
- Short Name:
- J/A+A/617/A53
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This work aims to observationally investigate the history of size growth of early-type galaxies and how the growth depends on cosmic epoch and the mass of the halo in which they are embedded. We carried out a photometric and structural analysis in the rest-frame V band of a mass-selected (logM/M_{sun}_>10.7) sample of red-sequence early-type galaxies with spectroscopic/grism redshift in the general field up to z=2 to complement a previous work presenting an identical analysis but in halos 100 times more massive and 1000 times denser. We homogeneously derived sizes (effective radii) fully accounting for the multi-component nature of galaxies and the common presence of isophote twists and ellipticity gradients. By using these mass-selected samples, composed of 170 red-sequence early-type galaxies in the general field and 224 identically selected and analyzed in clusters, we isolate the effect on galaxy sizes of the halo in which galaxies are embedded and its dependence on epoch. We find that the log of the galaxy size at a fixed stellar mass, log M/M_{sun}_=11, has increased with epoch at a rate twice as fast in the field than in cluster in the last 10Gyr (0.26+/-0.03 versus 0.13+/-0.02dex per unit redshift). Red-sequence early-type galaxies in the general field reached the size of their cousins in denser environment by z=0.25+/-0.13 in spite of being three times smaller at z~2. Data point toward a model where size growth is epoch-independent (i.e., {\partial}logre/{\partial}z=c), but with a rate c depending on environment, {\partial}c/{\partial}logM_halo_~=0.05. Environment determines the growth rate (dlogre/dz) at all redshifts, indicating an external origin for the galaxy growth without any clear epoch where it ceases to have an effect. The larger size of early-type galaxies in massive halos at high redshift indicates that their size grew buildup earlier (at z>2) at an accelerated rate, slowing down at some still unidentified z>2 redshift. Instead, the size growth rate of red-sequence early-type galaxies in low-mass halos is reversed: it proceeds at an increased rate at late epochs after an early period (z>2) of reduced growth, in agreement with the qualitative hierarchical picture of galaxy evolution. We found similar values of scatter around the mass-size relation independently of environment and epoch, indicating that the amount of dissipation in the system forming the observed galaxy does not vary greatly with epoch or environment.
- ID:
- ivo://CDS.VizieR/J/AJ/149/178
- Title:
- Redshift catalog of galaxies in GOODS-South field
- Short Name:
- J/AJ/149/178
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We combine Hubble Space Telescope (HST)/Wide Field Camera3 (WFC3) imaging and G141 grism observations from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) and 3D-HST surveys to produce a catalog of grism spectroscopic redshifts for galaxies in the CANDELS/GOODS-South field. The WFC3/G141 grism spectra cover a wavelength range of 1.1{<=}{lambda}{<=}1.7{mu}m with a resolving power of R~130 for point sources, thus providing rest-frame optical spectra for galaxies out to z~3.5. The catalog is selected in the H-band (F160W) and includes both galaxies with and without previously published spectroscopic redshifts. Grism spectra are extracted for all H-band detected galaxies with H<=24 and a CANDELS photometric redshift z_phot_>=0.6. The resulting spectra are visually inspected to identify emission lines, and redshifts are determined using cross-correlation with empirical spectral templates. To establish the accuracy of our redshifts, we compare our results against high-quality spectroscopic redshifts from the literature. Using a sample of 411 control galaxies, this analysis yields a precision of {sigma}_NMAD_=0.0028 for the grism-derived redshifts, which is consistent with the accuracy reported by the 3D-HST team. Our final catalog covers an area of 153arcmin^2^ and contains 1019 redshifts for galaxies in GOODS-S. Roughly 60% (608/1019) of these redshifts are for galaxies with no previously published spectroscopic redshift. These new redshifts span a range of 0.677{<=}z{<=}3.456 and have a median redshift of z=1.282. The catalog contains a total of 234 new redshifts for galaxies at z>1.5. In addition, we present 20 galaxy pair candidates identified for the first time using the grism redshifts in our catalog, including four new galaxy pairs at z~2, nearly doubling the number of such pairs previously identified.
- ID:
- ivo://CDS.VizieR/J/ApJ/471/L5
- Title:
- Redshift clustering in the Hubble Deep Field
- Short Name:
- J/ApJ/471/L5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present initial results from a redshift survey carried out with the low-resolution imaging spectrograph on the 10m W. M. Keck Telescope in the Hubble Deep Field. In the redshift distribution of the 140 extragalactic objects in this sample, we find six strong peaks with velocity dispersions of ~400km/s. The areal density of objects within a particular peak, while it may be nonuniform, does not show evidence for strong central concentration. These peaks have characteristics (velocity dispersions, density enhancements, spacing, and spatial extent) similar to those seen in a comparable redshift survey in a different high Galactic latitude field (Cohen and coworkers), confirming that the structures are generic. They are probably the high-redshift counterparts of huge galaxy structures ("walls") observed locally.
