目录
图像
上传图像
DSS Images Other Images
相关文章
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).
| Radio Emission from Galaxies in the Las Campanas Redshift Survey
To increase the redshift range and look-back time over which the radioluminosity function can be measured directly, we identified 1157galaxies in the Las Campanas Redshift Survey (LCRS) having isophotal(red) magnitudes m_iso<=18.0 with radio sources brighter than 2.5 mJybeam^-1 in the 1.4 GHz NRAO VLA Sky Survey (NVSS). Since the NVSS has45" FWHM angular resolution, these radio and optical limits includenearly all LCRS galaxies with 1.4 GHz luminosities L>=10^22.4 W Hz^-1at z~0.05 to L>=10^23.6 W Hz^-1 at z~0.2. The mean redshift~0.14 of the radio-detected galaxies is higher than the meanredshift ~0.10 of the optical sample. This indicates that,statistically, the radio emission was detected from galaxies with thehighest optical luminosities. Of the 1157 galaxies, 261 were alsoidentified with far-infrared (FIR) sources in the IRAS Point SourceCatalog and Faint Source Catalog. The principal radio energy sources inall identified galaxies were classified as either ``starburst'' or``AGN'' on the basis of their FIR-radio flux ratios, FIR spectralindices, and radio-optical flux ratios. We show that the radio-opticalflux ratio can be effectively used to classify the dominant energysource for the radio emission even if FIR fluxes and radio morphologicaldata are not available.
| 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.
|
提交文章
相关链接
提交链接
下列团体成员
|
观测天体数据
目录:
|
INHABITED SKY
