J/MNRAS/464/553ivo://CDS.VizieR/J/MNRAS/464/553doi:10.26093/cds/vizier.74640553CDSRochais T.Singh V.Chick W.Maithil J.Sutter J.Brotherton M.S.,Shang Z.2024-08-16T20:19:38Z2018-08-29T12:19:08ZCDS support team

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

cds-question@unistra.frquasarsspectroscopyThe spectrum of a quasar contains important information about its properties. Thus, it can be expected that two quasars with similar spectra will have similar properties, but just how similar has not before been quantified. Here we compare the ultraviolet spectra of a sample of 5553 quasars from Data Release 7 of the Sloan Digital Sky Survey, focusing on the 1350{AA}<={lambda}<=2900{AA} rest-frame region which contains prominent emission lines from SiIV, OIV], CIV, CIII], and MgII species. We use principal component analysis to determine the dominant components of spectral variation, as well as to quantitatively measure spectral similarity. As suggested by both the Baldwin effect and modified Baldwin effect, quasars with similar spectra have similar properties: bolometric luminosity, Eddington fraction, and black hole mass. The latter two quantities are calculated from the luminosity in conjunction with spectral features, and the variation between quasars with virtually identical spectra (which we call doppelgangers) is driven by the variance in the luminosity plus measurement uncertainties. In the doppelgangers the luminosity differences show 1{sigma} uncertainties of 57 per cent (or 0.63mag) and ~70 per cent 1{sigma} uncertainties for mass and Eddington fraction. Much of the difference in luminosities may be attributable to time lags between the spectral lines and the continuum. Furthermore, we find that suggestions that the mostly highly accreting quasars should be better standard candles than other quasars are not borne out for doppelgangers. Finally, we discuss the implications for using quasars as cosmological probes and the nature of the first two spectral principal components.2017MNRAS.464..553Rhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/464/553CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJS/194/45 : QSO properties from SDSS-DR7 (Shen+, 2011)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/464/553https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/464/553http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/464/553https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/464/553https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/464/553http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/464/553GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/464/553/table2 (The best SDSS DR7 spectral doppelgangers)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/464/553/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/464/553/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/464/553/table2?GETtext/xml+votable180.050000true194.52212551.36861110.0055555555555555566/1 546 4108-4109 4133 4156 4167 4182 4186 4196 4206 4210 4231 4256 4264 4313 4325 4362-4363 4400 4414 4445 4524 4534 4572 4580 4605 4608 4640 4644 4749 4758 4762 4792 4827 4889 4896 4907 4957 4959 4965-4966 4994 5014 5035 5050 5053-5054 5080 5084 5098-5099 5112 5114 5158 5190 5199 5231 5294 5299 5344 5353 5420 5426 5490 5492 5500 5510 5516 5520 5530 5544 5550 5553 5565 5580 5582 5587 5590 5615 5617 5659 5673 5675 5706 5727 5751 5757 5770 5777 5780 5813 5826 5833 5846 5853 5871 5876-5877 5908 5922 5926 5930 5939 5950 5962 5980 6007-6008 6025 6027 6031 6038 6047 6060 6072 6076 6099 6131 6142 6173 6210 6224-6225 6231 6267-6268 6340 6353 6400 6421 6475 6478 6489 6496 6518 6533 6542 6546-6547 6561 6569 6572 6580 6584 6594 6603 6605 6608 6612 6615 6618 6622-6623 6641 6741 7181-7182 7215-7216 7218 7228 7243-7244 7258 7264 7273 7284 7289 7299 7310 7312 7317 7336 7351 7360 7369 7379 7428 7432 7476 7480 7522 7527-7528 7536 7568 8192 8197 8203 8229 8233 8236 8240 8300 8304 8334 8350 8353-8354 8366 8374 8379 8384 8386 8398 8416 8469 8520 8523 8542 8603 8619-8620 8627 8671 8692 8705 8715 8719 8721 8736 8742 8745 8772 8774 8867 8927 8933 8990 8997 9012 9047 9052 9058 9096 9098 9102 9132 9149 9151 9155 9157 9160 9169 9179 9196-9198 9202 9219 9225 9228 9230 9244 9264 9279 9284 9286 9309-9310 9325 9342 9365 9374 9386 9395 9452 9475 9512 9624 9626 9643 9656 9743 9747 9749 9752 9800 9804 9810 9821 9824 9832 9838 9861 9882 9889 9898 9900 9908 9910 9935 9940 9942 9953 9978 9999 10017 10025 10027 10085 10096 10107 10112 10219 10308 10358 10363 10385 10412-10413 10416 10426 10446 10458 10472 10477 10495 10521 10526 10543 10552 10565 10567 10613 10624 10647 10660 10662 10692 10697 10731-10732 10735-10736 10770 10780 10790 10797 10813 10842 10890 10921 10939 10941 10963 10985 11006 11011 11016 11025 11031 11040 11064 11066 11093 11119 11125 11129 11147 11156-11157 11160 11191 11215 11217 11230 11253 11259 11262 11268 11279-11280 11308 11331-11332 11348 11382 11428 11438 11444 11475 11480-11481 11483 11488 11491 11498 11500 11600 11784 11816-11817 11843 11846 11848 11853 11910 11916-11917 11931 11938 11949-11950 12401 12406 12550 12552 12554 17149 17231 17233 17237 17251 17264 17295 17298 17322 17496-17497 17501 17512 17573 17581 17666 17756 17767 17771-17772 17777 17815 17831-17832 17856 18009 18024 18026 18028 18032 18065 18091 18410 18522 18534 18537 18544 18546 18613 18616 18624 18786 18788 18830 18841 18853 18952-18954 19026 19044 19089 19095 19387 19417 19456 19458 19693 19733 19742 19757 20004 21852 21967-21968 21973 21976 21982 22002 23049 23072 23183 23193 23206 25596 25837 25849-25850 25855 25934-25935 25938 25943 25948 25954 25967 25977 25980 25986 25992 25995 26002 26008 26016 26034 26040 26055 26057 26066 26082 26086 26157 26170 26187 26205-26206 26211 26227 26231 26234 26259 26261 26268 26314 26317 26321 26325 26371-26372 26375 26377 26391 26399 26413 26479 26503 26506 26516 26522 26556 26558 26563 26573 26586-26587 26606 26877 26952 26961 26966 26972 26974-26975 26985 26989 27004-27005 27021 27023 27032 27035 27079 27083 27114 27128 27131 27236 27253 27257 27260 27262-27263 27283 27315 27318 27320-27321 27333 27335-27336 27356 27364 27379-27380 27396 27398 27421 27434 27445 27448-27450 27479 27490 27502 27511 27519 27523 27529 27546 27566 27576 27595 27602 27608 27630 27651 27685 27692 27696 27702 27706-27707 27711 27716 27725 27737 27743 27753 27772 27778 27785 27788 27806 27844 27861 27872 27912 27952 27956 28126 28136 28141 28149 28162 28184-28185 28196 28225 28307 28348 28354 28417 28431 28449 28470 28472 28480 28492 28495 28502 28504 28508 28515 28543 28556 28581 28583 28594 28602 28645 28666 30034-30035 31144 31324 31345 31392 31422 31454 31468 31490 31547 31550 31652 31667 32403 32414 32443 32458 32501 32511 36765 36774 36787 36790 36817 49122 49128 49151https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/464/553?format=asciidefaultJ/MNRAS/464/553/table2The best SDSS DR7 spectral doppelgangersSDSS2SDSS name (HHMMSS.ss+DDMMSS.s) for second QSOmeta.id.part;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSDSS1SDSS name (HHMMSS.ss+DDMMSS.s) for first QSOmeta.id.part;meta.maincharPlate1SDSS plate number for first source of the pairmeta.idintFiber1SDSS fiber number for first source of the pairmeta.idintMJD1SDSS MJD number for first source of the pairdmeta.idintPlate2SDSS plate number for second source of the pairmeta.idintFiber2SDSS fiber number for second source of the pairmeta.idintMJD2SDSS MJD number for second source of the pairdmeta.idintdHyperspace distance between the two spectra (1)stat.fit.paramdoubleDMBHDifference in black hole mass (2)%phys.mass;arith.ratiofloatDLcont-CIVDifference in continuum luminosity at CIV (2)%phys.luminosity;arith.ratiofloatDL/DLeddDifference in the Eddington fraction (2)%phys.luminosity;arith.ratiofloatSp1Interactive spectrum from SDSS for QSO1meta.ref.urlcharSp2Interactive spectrum from SDSS for QSO2meta.ref.urlchar_RAPosition from first QSO name (right ascension part)degpos.eq.ra;meta.main_DEPosition from first QSO name (declination part)degpos.eq.dec;meta.main