J/MNRAS/449/2818ivo://CDS.VizieR/J/MNRAS/449/2818doi:10.26093/cds/vizier.74492818CDSTuccillo D.Gonzalez-Serrano J.I.Benn C.R.2024-08-14T20:21:07Z2016-01-13T10:00:54ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frsurveysquasarsradio-sourcesredshiftedWe obtain a sample of 87 radio-loud quasi-stellar objects (QSOs) in the redshift range 3.6<=z<=4.4 by cross-correlating sources in the Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) radio survey (S_1.4GHz_>1mJy) with star-like objects having r<20.2 in Sloan Digital Sky Survey (SDSS) Data Release 7. Of these 87 QSOs, 80 are spectroscopically classified in previous work (mainly SDSS), and form the training set for a search for additional such sources. We apply our selection to 2916 FIRST-DR7 pairs and find 15 likely candidates. Seven of these are confirmed as high-redshift quasars, bringing the total to 87. The candidates were selected using a neural-network, which yields 97 percent completeness (fraction of actual high-z QSOs selected as such) and an efficiency (fraction of candidates which are high-z QSOs) in the range of 47-60 percent. We use this sample to estimate the binned optical luminosity function (LF) of radio-loud QSOs at z~4, and also the LF of the total QSO population and its comoving density. Our results suggest that the radio-loud fraction at high z is similar to that at low z and that other authors may be underestimating the fraction at high z. Finally, we determine the slope of the optical LF and obtain results consistent with previous studies of radio-loud QSOs and of the whole population of QSOs. The evolution of the LF with redshift was for many years interpreted as a flattening of the bright-end slope, but has recently been re-interpreted as strong evolution of the break luminosity for high-z QSOs, and our results, for the radio-loud population, are consistent with this.2015MNRAS.449.2818Thttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/449/2818CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVII/260 : The SDSS-DR7 quasar catalog (Schneider+, 2010)VIII/92 : The FIRST Survey Catalog, Version 2014Dec17 (Helfand+ 2015)J/MNRAS/391/369 : New z>=3.6 QSOs from FIRST-SDSS DR5 (Carballo+, 2008)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/449/2818https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/449/2818http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/449/2818https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/449/2818https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/449/2818http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/449/2818GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/449/2818/table4 (Final sample of 87 RLQ with 3.6<=z<=4.4)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/449/2818/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/449/2818/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/449/2818/table4?GETtext/xml+votable180.050000true28.4150417-0.18472220.0055555555555555566/0 4168 4177 4263 4290 4504 4638 4641 4692 4867 4902 5053 5346 5443 5448 5468 5533 5546 5563 5578 5802 5890 6085 6219 6258 6386 6457 6582 7193 7199 7237 7301 7320 7488 8218 8590 8777 8841 8988 9260 9372 9635 9988 10549 10677 10707 10802 10885 11056 11161 11303 11308 11368 11418 11494 11805 17302 17818 18624 18859 22484 25565 25990 26056 26213 26355 26520 26568 27033 27100 27270 27559 27588 27899 27910 27931 27968 28173 28177 28308 28322 28397 28482 28579 28615 31468 31592https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/449/2818?format=asciiOpticalRadiodefaultJ/MNRAS/449/2818/table4Final sample of 87 RLQ with 3.6<=z<=4.4recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSDSSSDSS object-ID, JHHMMSS.ss+DDMMSS.smeta.id;meta.maincharRAJ2000SDSS right ascension (J2000)pos.eq.ra;meta.mainDEJ2000SDSS declination (J2000)pos.eq.dec;meta.mainrmagSDSS dereddened PSF r magnitude (AB)magphot.mag;em.opt.Rfloate_rmagError in PSF r magnitude as given in SDSSmagstat.error;phot.mag;em.opt.RfloatzQSO redshift determined in this work or from SDSSsrc.redshiftfloatS1.4GHzFIRST peak radio flux densitymJyphot.flux.density;em.radio.750-1500MHzfloatrMAGAbsolute r magnitudemagphys.magAbsfloatlogP1.4GHzRadio luminosity at 1.4 GHzlog(W.Hz**-1)phys.luminosity;em.radio.750-1500MHzfloatr_zIndicates the source of the data from which the redshift was first obtained (1)meta.ref;pos.framecharSloanDisplay the SDSS data for this quasarmeta.ref.urlcharJ/MNRAS/449/2818/table5K-correction in the SDSS r bandzemEmission redshiftsrc.redshiftfloatKcorrK correctionarith.factor;phot.magdoublerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint