J/A+A/702/A232ivo://CDS.VizieR/J/A+A/702/A232doi:10.26093/cds/vizier/bc-ny/lcdcCDSBettoni D.Falomo R.Paiano S.2026-08-31T14:31:31Z2025-10-24T10:46:07ZCDS support team

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

cds-question@unistra.frgalaxiesquasarsredshiftedphotometryvisible-astronomyWe investigate the relationship between quasars and close companion galaxies using photometry and spectroscopy from the large data set of the SDSS DR16 survey. From the SDSS-QSO catalog of quasars, we selected objects with 0.1<z<=0.35 and absolute magnitude M(r) <-21.3. For all these targets, we searched for candidate companion galaxies that have a projected distance from the target <700kpc and a radial velocity difference from the QSO {Delta}V<1000km/s. We find that in 447 QSO at least one companion galaxy is associated. A total of 691 associated galaxies are found in these QSO fields. In the majority of them there is just one associated galaxy but in few cases, many companions are also discovered and in two cases the QSO is found in rich galaxy environments. The possible contamination due to a chance projection of the companion galaxies is found less than 5%. Based on the available data we expect on average to find ~2 associated companion galaxies for each QSO. A small fraction (13%) of the companion galaxies exhibits [OII] emission lines as signature of recent star formation. However a similar fraction (16%) of unassociated galaxies in the same QSO fields show [OII] emission. This study suggests that there is no significant link between the presence of these close companion galaxies or the signature of recent star formation and the QSO nuclear activity.2025A&A...702A.232Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/702/A232CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/702/A232https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/702/A232http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/702/A232https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/702/A232https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/702/A232http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/702/A232GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/702/A232/qso (List of position and magnitudes of QSO)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/702/A232/qso?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/702/A232/qso?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/702/A232/qso?GETtext/xml+votable180.050000true22.562926940.432553060.005555555555555556Cone search capability for table J/A+A/702/A232/comp (Position magnitude redshift and projected distance for 650 companion objects)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/702/A232/comp?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/702/A232/comp?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/702/A232/comp?GETtext/xml+votable180.050000true22.601113060.423693060.0055555555555555565/4544 6/2 678 2165 2171 2188 2242 2256 2567 4181 4187 4233 4267 4365 4424 4432 4463 4508 4550 4555 4568 4574 4648 4748-4749 4760 4766-4767 4813 4938 4954 4961 4996 5002 5006 5015 5034 5061 5071 5158 5292 5347 5384 5397 5403 5418 5421 5427 5437 5469 5475 5485-5486 5498 5530-5531 5572 5576 5628 5682 5725 5749 5776 5778 5817-5818 5850 5855 5929 5941 5947 5955 5962 5971 6005 6044 6052 6054 6061 6101 6109 6112 6167 6218 6227 6244 6270-6271 6340 6391 6462 6473 6476 6505 6515 6521 6557 6573 6613 6640 7173 7194 7224-7225 7231 7253 7277 7296 7300 7310 7317 7332 7368 7374 7384-7385 7460 7493-7494 7526 8199 8208 8227 8290 8312 8324 8341 8568 8589 8610 8638 8641 8733 8803 8812 8846 8859 8913 8930 8939 8942 8993 9016 9074 9120 9188 9200 9208 9213 9237 9239 9250 9279 9303 9323 9337 9385 9460 9484 9528-9529 9532-9533 9627 9650 9653 9662 9729 9739 9770 9790 9821 9885 9911-9912 9926 9950 9980 9988 10006 10041 10155 10162 10168 10259 10336 10343 10428 10472 10477 10506 10522 10563 10571 10588 10662 10682 10692 10694 10724 10772 10792-10793 10824 10830 10836 10839 10877-10879 10894 10939 10949-10950 10976 10984 10986 11020 11027 11061 11098 11124 11160 11172 11202 11208 11263 11282 11297 11300 11326 11328 11409 11417 11421 11427 11451 11470 11475-11476 11478 11502 11520 11783 11818 11825 11830 11854 11875 11882 11913 11918 11929 11946 12544 12546-12547 12631 13383 13401 13405 13445 17214 17236 17240 17251 17260 17368 17500 17514 17647 17673 17681 17766 17782 17798 17805 17819 17822 17826 17840 17896 17969 17998 18006-18007 18010-18012 18020 18034 18051 18073 18090 18094 18182 18210 18407 18519 18599 18683 18743 18747 18751 18769 18772 18798 18850 18866 19028 19037 19052-19053 19083 19144 19146 19155 19159 19227 19327 19486 19513 19516 19531 19657 19660 19663 19686 19927 19932 19991 20074 20117 20157 20167 20185 20200 20353 20375 20389 20416 20433 21843 21970 22355 22367 23150 23187 23190 23193 23216 25964-25965 26024 26103 26237 26256 26285 26297 26309 26319 26356 26462 26468 26498 26507 26509 26520 26572 26582-26583 26590 26623 26879 26979 26995 27046 27082 27105 27225 27287 27290 27343 27378 27391 27458 27484 27501-27502 27530 27543 27561-27562 27633 27697 27699 27715 27732 27825 27851 27894 27924 28002 28053 28101 28143 28187 28252 28270 28438 28467-28468 28512 28520 28527 28534 28538 28564 28576 28611 28620 28630 28661 28670 30039 31374-31375 31389 31392-31393 31398 31405 31408 31435 31450 31635 31670 32441 32480 32683 36763 49009https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/702/A232?format=asciiOpticaldefaultJ/A+A/702/A232/qsoList of position and magnitudes of QSOrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintQSOQSO designation (QSO_NNN)meta.id;meta.maincharSDSSSDSS designation (HHMMSS.ss+DDMMSS.s)meta.idcharRAJ2000Right ascension (J2000.0)degpos.eq.ra;meta.mainDEJ2000Declination (J2000.0)degpos.eq.dec;meta.mainzRedshift of the QSOsrc.redshiftdoublermagr magnitude of the QSOmagphot.mag;em.opt.RfloatSimbadSimbad column added by the CDSmeta.ref.urlcharJ/A+A/702/A232/compPosition magnitude redshift and projected distance for 650 companion objectsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameDesignation for the companion, AN_QSO_NNNmeta.id;meta.maincharRAJ2000Right Ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainzcompRedshift of companion galaxysrc.redshift;pos.heliocentricfloatrmagcompr band magnitude of companion galaxymagphot.mag;em.opt.RfloatPDistProjected distance from the QSOkpcpos.distancefloatSimbadNameSimbad column added by the CDSmeta.idcharnullable