Possible surface brightness selection effects in the redshift catalogs of the Canada-France Redshift Survey are investigated through comparisons of subsamples of the data. Our analyses demonstrate that the securing of redshifts is independent of possible biases arising from surface brightness effects and/or differing galaxy morphologies and orientations. The unusual geometry of the mask designs for our spectroscopic observations also do not produce any significant bias. There is, however, a bias at the highest and lowest redshifts, especially for absorption-line galaxies at z>1 and z<0.2, due to the adopted spectral range (4250-8500A). Apart from the latter, we conclude that our sample of identified galaxies is an unbiased subsample of the original photometric catalog and is essentially limited by I-band flux density (17.5<I_AB_<22.5). Finally, spectroscopic data for the remaining CFRS field is presented. Data for 272 objects in the 0300+0000 field are given.
The 143 galaxies with secure redshifts (Z_median_=0.62) from the 1415+52 field of the Canada-France Redshift Survey have been imaged with median seeing of 0.67" (FWHM). Structural parameters have been derived by fitting multicomponent models and the results confirm two phenomena seen in a smaller sample of galaxies imaged with the Hubble Space Telescope. First, 11+/-3% of the galaxies lie off the normal locus of color versus bulge fraction B/T. This class of objects ("blue nucleated galaxies," or BNGs) was identified using HST observations (Schade et al. 1995ApJ...451L...1S, hereafter CFRS IX), and it was shown that they are associated with peculiar/asymmetric structure and merger/interactions. The observed frequency of BNGs in this sample is 14+/-4% 0.5<z<1.2 and 6^+6^_-3_% at 0.2<z<0.5, but the true frequency is likely to be a factor ~2 higher after corrections are made for the effect of asymmetric/peculiar structures. Galaxy disks at 0.5<z<1.1 are found to have a mean rest-frame, inclination-corrected central surface brightness of {mu}_AB_(B)=19.8+/-0.1mag/arcsec^2^, ~1.6mag brighter than the Freeman (1970ApJ...160..811F) value. At low redshift (0.2<z<0.5) the mean surface brightness [{mu}_AB_(B)=21.3+/-0.25] is consistent with the Freeman value. These results are consistent with the HST observations. With larger numbers of galaxies and therefore more statistical weight they demonstrate the capabilities, and limits, of ground-based work in the study of galaxy morphology at high redshift.
The spectral properties of more than 400 Canada-France Redshift Survey (CFRS) galaxies and their changes over the redshift interval 0<=z<=1.3 are investigated. Emission-line intensities and equivalent widths for accessible lines have been measured, as well as continuum color indices based on 200{AA} wide spectral regions.
We report new photometry of CG Cyg from 1998-2002. We also analyze published photometry collected since 1965. ************************************************************************** * * * Sorry, but the author(s) never supplied the tabular material * * announced in the paper * * * **************************************************************************
Results form a survey of the northern Galactic plane (at declination >=30{deg} at 151MHz made with the Cambridge Low Frequency Synthesis Telescope are presented. This survey is designated 7C(G) - i.e. the Galactic portion of the ongoing 7C surveys. This covers the regions 80{deg}<l<104{deg} and 126{deg}<l<180{deg}, for |b|<=5.5{deg}, and has some coverage to |b|~9{deg}, with a resolution of ~70x70cosec{delta}arcsec^2^ (RAxDec). The observations, data reduction and calibration of this survey are described, and a catalogue of 6262 compact sources, with a completeness limit of ~0.25Jy over most of the survey region, is presented. The catalogue has an rms positional accuracy of better than 10arcsec, and the flux densities are tied to the scale of Roger, Bridle & Costain (1973AJ.....78.1030R) with an accuracy of better than 10 per cent.
We present the analysis of the XMM-Newton data of the Circum-Galactic Medium of MASsive Spirals (CGM-MASS) sample of six extremely massive spiral galaxies in the local universe. All the CGM-MASS galaxies have diffuse X-ray emission from hot gas detected above the background extending ~(30-100)kpc from the galactic center. This doubles the existing detection of such extended hot CGM around massive spiral galaxies. The radial soft X-ray intensity profile of hot gas can be fitted with a {beta}-function, with the slope typically in the range of {beta}=0.35-0.55. This range, as well as those {beta} values measured for other massive spiral galaxies, including the Milky Way (MW), are in general consistent with X-ray luminous elliptical galaxies of similar hot gas luminosity and temperature, and with those predicted from a hydrostatic- isothermal gaseous halo. Hot gas in such a massive spiral galaxy tends to have temperature comparable to its virial value, indicating the importance of gravitational heating. This is in contrast to lower mass galaxies, where hot gas temperature tends to be systematically higher than the virial one. The ratio of the radiative cooling to free fall timescales of hot gas is much larger than the critical value of ~10 throughout the entire halos of all the CGM-MASS galaxies, indicating the inefficiency of gas cooling and precipitation in the CGM. The hot CGM in these massive spiral galaxies is thus most likely in a hydrostatic state, with the feedback material mixed with the CGM, instead of escaping out of the halo or falling back to the disk. We also homogenize and compare the halo X-ray luminosity measured for the CGM-MASS galaxies and other galaxy samples and discuss the "missing" galactic feedback detected in these massive spiral galaxies.
We describe a uniform all-sky survey of bright blazars, selected primarily by their flat radio spectra, that is designed to provide a large catalog of likely {gamma}-ray active galactic nuclei (AGNs). The defined sample has 1625 targets with radio and X-ray properties similar to those of the EGRET blazars, spread uniformly across the |^b^|>10{deg} sky. We also report progress toward optical characterization of the sample; of objects with known R<23, 85% have been classified and 81% have measured redshifts. One goal of this program is to focus attention on the most interesting (e.g., high-redshift, high-luminosity, ...) sources for intensive multiwavelength study during the observations by the Large Area Telescope (LAT) on GLAST.
CGS. V. Statistical study of bars and buckled bars
Short Name:
J/ApJ/845/87
Date:
21 Oct 2021
Publisher:
CDS
Description:
Simulations have shown that bars are subject to a vertical buckling instability that transforms thin bars into boxy or peanut-shaped structures, but the physical conditions necessary for buckling to occur are not fully understood. We use the large sample of local disk galaxies in the Carnegie-Irvine Galaxy Survey to examine the incidence of bars and buckled bars across the Hubble sequence. Depending on the disk inclination angle (i), a buckled bar reveals itself as either a boxy/peanut-shaped bulge (at high i) or as a barlens structure (at low i). We visually identify bars, boxy/peanut-shaped bulges, and barlenses, and examine the dependence of bar and buckled bar fractions on host galaxy properties, including Hubble type, stellar mass, color, and gas mass fraction. We find that the barred and unbarred disks show similar distributions in these physical parameters. The bar fraction is higher (70%-80%) in late-type disks with low stellar mass (M*<10^10.5^M_{sun}_) and high gas mass ratio. In contrast, the buckled bar fraction increases to 80% toward massive and early-type disks (M*>10^10.5^M_{sun}_), and decreases with higher gas mass ratio. These results suggest that bars are more difficult to grow in massive disks that are dynamically hotter than low-mass disks. However, once a bar forms, it can easily buckle in the massive disks, where a deeper potential can sustain the vertical resonant orbits. We also find a probable buckling bar candidate (ESO506-G004) that could provide further clues to understand the timescale of the buckling process.
Chamaeleon DANCe. Stellar population with Gaia-DR2
Short Name:
J/A+A/646/A46
Date:
21 Oct 2021
Publisher:
CDS
Description:
Kinematic properties and stellar parameters of the Chamaeleon stars selected in our membership analysis using Gaia-DR2 data. We provide for each star its identifier, position, proper motion, parallax, radial velocity, distance, spatial velocity, SED classification, age and membership probability. We also provide the membership probabilities for all sources in the fields surveyed by our study and the empirical isochrone of the Cha I and Cha II subgroups.
The nearby Chamaeleon molecular cloud complex is a good laboratory for studying the process of low-mass star formation because it consists of three clouds with very different properties. Chamaeleon III does not show any sign of star formation, while star formation has been very active in Chamaeleon I and may already be finishing. Our goal is to determine whether star formation can proceed in Cha III by searching for prestellar cores, and to compare the results to our recent survey of Cha I.