Contents
Images
Upload your image
DSS Images Other Images
Related articles
The 2dF Galaxy Redshift Survey: the population of nearby radio galaxies at the 1-mJy level
We use redshift determinations and spectral analysis of galaxies in the2dF Galaxy Redshift Survey to study the properties of local radiosources with S>=1mJy. 557 objects (hereafter called the spectroscopicsample) drawn from the FIRST survey, corresponding to 2.3 per cent ofthe total radio sample, are found in the 2dFGRS catalogue within thearea9h48m<~RA(2000)<~14h32m and -2.77°<~Dec.(2000)<~2.25°, down to a magnitudelimit bJ=19.45. The excellent quality of 2dF spectra allowsus to divide these sources into classes, according to their opticalspectra. Absorption-line systems make up 63 per cent of thespectroscopic sample. These may or may not show emission lines due toAGN activity, and correspond to `classical' radio galaxies belongingmainly to the FRI class. They are characterized by relatively highradio-to-optical ratios, red colours, and high radio luminosities(1021<~P1.4GHz/WHz-1sr-1<~1024). Actively star-forming galaxies contributeabout 32 per cent of the sample. These objects are mainly found at lowredshifts (z<~0.1) and show low radio-to-optical ratios, blue coloursand low radio luminosities. We also found 18 Seyfert 2 galaxies (3 percent) and four Seyfert 1s (1 per cent). Analysis of the local radioluminosity function (LF) shows that radio galaxies are well described bymodels that assume pure luminosity evolution, at least down to radiopowersP1.4GHz<~1020.5WHz-1sr-1.Late-type galaxies, whose relative contribution to the radio LF is foundto be lower than was predicted by previous works, present an LF which iscomparable with the IRAS galaxy LF. This class of sources thereforeplausibly constitutes the radio counterpart of the dusty spirals andstarbursts that dominate the counts at 60μm.
| Radio sources in the 2dF Galaxy Redshift Survey - II. Local radio luminosity functions for AGN and star-forming galaxies at 1.4 GHz
We have cross-matched the 1.4-GHz NRAO VLA Sky Survey (NVSS) with thefirst 210 fields observed in the 2dF Galaxy Redshift Survey (2dFGRS),covering an effective area of 325deg2 (about 20 per cent ofthe final 2dFGRS area). This yields a set of optical spectra of 912candidate NVSS counterparts, of which we identify 757 as genuine radioidentifications - the largest and most homogeneous set of radio sourcespectra ever obtained. The 2dFGRS radio sources span the redshift rangez=0.005 to 0.438, and are a mixture of active galaxies (60 per cent) andstar-forming galaxies (40 per cent). About 25 per cent of the 2dFGRSradio sources are spatially resolved by NVSS, and the sample includesthree giant radio galaxies with projected linear size greater than 1Mpc.The high quality of the 2dF spectra means we can usually distinguishunambiguously between AGN and star-forming galaxies. We make a newdetermination of the local radio luminosity function at 1.4GHz for bothactive and star-forming galaxies, and derive a local star formationdensity of 0.022+/-0.004Msolaryr-1Mpc-3(H0=50kms-1Mpc-1).
| The Southern Sky Redshift Survey
We report redshifts, magnitudes, and morphological classifications for5369 galaxies with m_B <= 15.5 and for 57 galaxies fainter than thislimit, in two regions covering a total of 1.70 sr in the southerncelestial hemisphere. The galaxy catalog is drawn primarily from thelist of nonstellar objects identified in the Hubble Space TelescopeGuide Star Catalog (GSC). The galaxies have positions accurate to ~1"and magnitudes with an rms scatter of ~0.3 mag. We compute magnitudes(m_SSRS2) from the relation between instrumental GSC magnitudes and thephotometry by Lauberts & Valentijn. From a comparison with CCDphotometry, we find that our system is homogeneous across the sky andcorresponds to magnitudes measured at the isophotal level ~26 magarcsec^-2. The precision of the radial velocities is ~40 km s^-1, andthe redshift survey is more than 99% complete to the m_SSRS2 = 15.5 maglimit. This sample is in the direction opposite that of the CfA2; incombination the two surveys provide an important database for studies ofthe properties of galaxies and their large-scale distribution in thenearby universe. Based on observations obtained at Cerro TololoInter-American Observatory, National Optical Astronomy Observatories,operated by the Association of Universities for Research in Astronomy,Inc., under cooperative agreement with the National Science Foundation;Complejo Astronomico El Leoncito, operated under agreement between theConsejo Nacional de Investigaciones Científicas de laRepública Argentina and the National Universities of La Plata,Córdoba, and San Juan; the European Southern Observatory, LaSilla, Chile, partially under the bilateral ESO-ObservatórioNacional agreement; Fred Lawrence Whipple Observatory;Laboratório Nacional de Astrofísica, Brazil; and the SouthAfrican Astronomical Observatory.
| An image database. II. Catalogue between δ=-30deg and δ=70deg.
A preliminary list of 68.040 galaxies was built from extraction of35.841 digitized images of the Palomar Sky Survey (Paper I). For eachgalaxy, the basic parameters are obtained: coordinates, diameter, axisratio, total magnitude, position angle. On this preliminary list, weapply severe selection rules to get a catalog of 28.000 galaxies, wellidentified and well documented. For each parameter, a comparison is madewith standard measurements. The accuracy of the raw photometricparameters is quite good despite of the simplicity of the method.Without any local correction, the standard error on the total magnitudeis about 0.5 magnitude up to a total magnitude of B_T_=17. Significantsecondary effects are detected concerning the magnitudes: distance toplate center effect and air-mass effect.
| An extragalactic database. I - The Catalogue of Principal Galaxies
The Catalogue of Principal Galaxies is described, which lists equatorialcoordinates (for the equinoxes 1950 and 2000) and cross-identificationsfor 73,197 galaxies. The 40,932 coordinates have standard deviationssmaller than 10 arcsec. A total of 131,601 names from the 38 most commonsources are listed. In addition, mean data for each object are givenwhen available: 49,102 morphological descriptions, 52,954 apparent majorand minor axes, 67,116 apparent magnitudes, 20,046 radial velocities and24,361 position angles. This information was used for facilitatingproper identification. Finally, distribution options are explained.
|
Submit a new article
Related links
Submit a new link
Member of following groups:
|
Observation and Astrometry data
Catalogs and designations:
|
