J/ApJ/696/580ivo://CDS.VizieR/J/ApJ/696/580doi:10.26093/cds/vizier.16960580CDSShemmer O.Brandt W.N.Anderson S.F.Diamond-Stanic A.M.Fan X.,Richards G.T.Schneider D.P.Strauss M.A.2017-06-27T06:38:46Z2011-05-16T15:21:22ZCDS support team

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

cds-question@unistra.frquasarsx-ray-sourcesactive-galactic-nucleiredshiftedbl-lacertae-objectsWe present Chandra observations of nine high-redshift quasars (z=2.7-5.9) discovered by the Sloan Digital Sky Survey with weak or undetectable high-ionization emission lines in their UV spectra (WLQs). Adding archival X-ray observations of six additional sources of this class has enabled us to place the strongest constraints yet on the X-ray properties of this remarkable class of active galactic nuclei (AGNs). Although our data cannot rule out the possibility that the emission lines are overwhelmed by a relativistically boosted continuum, as manifested by BL Lac objects, we find that WLQs are considerably weaker in the X-ray and radio bands than the majority of BL Lacs found at much lower redshifts. If WLQs are high-redshift BL Lacs, then it is difficult to explain the lack of a large parent population of X-ray and radio bright weak-lined sources at high redshift. We also consider the possibility that WLQs are quasars with extreme properties, and in particular that the emission lines are suppressed by high accretion rates. Using joint spectral fitting of the X-ray spectra of 11 WLQs, we find that the mean photon index in the hard X-ray band is consistent with those observed in typical radio-quiet AGNs with no hint of an unusually steep hard-X-ray spectrum. This result poses a challenge to the hypothesis that WLQs have extremely high accretion rates, and we discuss additional observations required to test this idea.2009ApJ...696..580Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/696/580CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/chandra : The Chandra Archive Log (CXC, 1999-)VII/260 : The SDSS-DR7 quasar catalog (Schneider+, 2010)J/AJ/135/2453 : Sample of BL Lac objects from SDSS and FIRST (Plotkin+, 2008)J/PASJ/60/161 : Multi-wave band emission from blazars (Yi+, 2008)J/AJ/129/2542 : BL Lac from SDSS (Collinge+, 2005)J/MNRAS/323/757 : Deep X-Ray Radio Blazar Survey (DXRBS). II. (Landt+, 2001)J/AJ/121/31 : High-redshift quasars in SDSS (Fan+, 2001)J/ApJ/525/127 : RGB sample of BL Lacertae objects (Laurent-Muehleisen+, 1999)J/AJ/115/1253 : Deep X-Ray Radio Blazar Survey (DXRBS). I. (Perlman+ 1998)J/A+AS/109/267 : Radio to X-Ray distribution of BL Lac Objects (Giommi+, 1995)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/696/580https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/696/580http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/696/580https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/696/580https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/696/580http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/696/580GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/696/580/table5 (X-ray, optical, and radio properties of the BL Lac sample)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/696/580/table5?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/696/580/table5?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/696/580/table5?GETtext/xml+votable180.050000true0.4885-10.521480.005555555555555556Cone search capability for table J/ApJ/696/580/wlqs (X-ray, optical and radio properties of Weak emission-Line Quasars (WLQs))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/696/580/wlqs?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/696/580/wlqs?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/696/580/wlqs?GETtext/xml+votable180.050000true49.3009583-7.98063890.0055555555555555566/158 342 398 579 615 790 975 2273 2414 2549 2650 2792 3710 4098 4104 4108 4146 4190 4210 4353 4472 4475 4504 4604 4606 4695 4741 4824 4861 4862 4892 4902 4974 5037 5072 5091 5233 5361 5423 5510 5536 5546 5553 5676 5698 5703 5723 5800 5844 5881 5918 5939 6021 6025 6027 6051 6088 6096 6116 6212 6242 6255 6409 6413 6436 6464 6502 6534 6554 6574 6629 6647 6764 7038 7233 7265 7285 7343 7475 7518 7548 7553 7570 7871 7989 8067 8374 8487 8556 8945 8972 9049 9060 9143 9223 9264 9445 9455 9464 9554 9612 9618 9637 9684 9711 9773 9811 9855 9960 9985 9991 9996 10061 10154 10220 10262 10422 10456 10510 10520 10526 10540 10605 10627 10656 10669 10748 10749 10810 10912 10938 10949 10980 11030 11038 11100 11101 11124 11143 11160 11168 11174 11176 11178 11242 11246 11253 11321 11327 11415 11429 11430 11449 11450 11467 11476 11493 11514 11585 11639 11795 11798 11838 11876 11936 13586 13705 13820 13927 15260 15286 15311 15969 16027 16059 16478 16652 16952 17193 17213 17553 17574 17749 17755 17820 17843 18096 18324 18687 18772 18840 18852 19034 19190 19324 19327 19671 19778 20054 20550 20624 20764 21879 21972 23134 23181 23222 25542 25582 25832 25855 25934 26207 26215 26228 26242 26247 26270 26305 26322 26335 26406 26571 26964 26998 27036 27056 27063 27076 27251 27321 27366 27405 27420 27428 27442 27500 27560 27573 27603 27622 27698 27722 27845 27846 27945 28138 28225 28492 28517 28595 28599 28664 30039 31358 31389 31663 32261 32345 32621 33823 34209 34514 34531 34572 35720 36342 36728 43603 43883 46442 46545 47014 47319 47375 49007 49019 49124 491511.369959761869892e-18 1.369959761869892e-18https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/696/580?format=asciiX-rayOpticaldefaultJ/ApJ/696/580/table5X-ray, optical, and radio properties of the BL Lac sampleSimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameSource namemeta.id;meta.maincharRAJ2000Right Ascension in decimal degrees (J2000)degpos.eq.ra;meta.mainDEJ2000Declination in decimal degrees (J2000)degpos.eq.dec;meta.mainzRedshiftsrc.redshiftfloatlog2keVLog monochromatic luminosity at 2keV in erg/slog(1e-07W)phys.luminosity;em.X-ray.softfloatf_log2keV[0/1] 0 = upper limit in log2keV (1)meta.codeintlog5500Log monochromatic luminosity at 5500{AA}log(1e-07W)phys.luminosityfloatf_log5500[0/1] 0 = upper limit on log5500 (1)meta.codeintlog5GHzLog monochromatic luminosity at 5GHz in erg/slog(1e-07W)phys.luminosity;em.radio.3-6GHzfloatf_log5GHz[0/1] 0 = upper limit on log5GHz (1)meta.codeintaoxOptical/X-ray spectral indexspect.indexfloatf_aox[0/1] 0 = upper limit on aox (1)meta.codeintaroRadio/Optical spectral indexspect.indexfloatf_aro[0/1] 0 = upper limit on aro (1)meta.codeintRefReference for multiwavelength data (2)meta.ref;pos.frameintP08BL Lac objects from SDSS and FIRST data (Plotkin et al. 2008, Cat. J/135/AJ/2453)meta.ref.urlcharSloanDisplay the SDSS data for this objectmeta.ref.urlcharJ/ApJ/696/580/wlqsX-ray, optical and radio properties of Weak emission-Line Quasars (WLQs)SimbadNameSimbad column added by the CDSmeta.idcharl_aroLimit flag on arometa.code.errorcharzRedshiftsrc.redshiftfloatl_logLLimit flag on logLmeta.code.errorcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSDSSSDSS identification (HHMMSS.ss+DDMMSS.s)meta.id;meta.maincharf_SDSS[hi] Note about the X-ray data (G1)meta.codecharrOX? Angular distance between the optical and X-ray position (2)arcsecpos.angDistancefloatnullablef_ObsDate[d] Merged image (G1)meta.codecharObsDateDate of observationtime.epochnullableObsID? Chandra observation identification numbermeta.idintnullableExpTChandra exposure time (corrected for detector dead time)kstime.duration;obs.exposurefloatRef? Reference number in which the source were first identified as WLQ (Weak emission-Line quasar) or BL Lac candidate (5)meta.bibintnullableNHNeutral galactic absorption column density from Dickey & Lockman (1990ARA&A..28..215D)1e+20cm**-2physfloatAB1450Monochromatic AB magnitude at a rest-frame wavelength of 1450{AA}magphot.mag;em.UV.100-200nmfloatf_AB1450[j] Spectrum from Keck (G1)meta.codecharBMAGAbsolute B-band magnitudemagphot.mag;em.opt.BfloatF2500Flux density at rest-frame 2500{AA} in units of 10^-28^erg/cm^2^/s/Hz (10^-5^Jy)10uJyphot.flux;em.UVfloatL2500Log monochromatic luminosity at a rest-frame wavelength of 2500{AA}log(1e-07W)phys.luminosityfloatl_CRateLimit flag on CRatemeta.code.errorcharCRateObserved count rate in the 0.5-2keV bandct/ksphot.count;em.X-rayfloatE_CRate? Positive error on CRatect/ksstat.error;stat.maxfloatnullablee_CRate? Negative error on CRatect/ksstat.errorfloatnullablef_CRate[k] corrected for exposure map (G1)meta.codecharl_FxLimit flag on Fxmeta.code.errorcharFxGalactic absorption-corrected flux in the 0.5-2keV band (in 10^-15^erg/cm^2^/s)aW.m**-2phot.flux;em.X-ray.soft;pos.galacticfloatE_Fx? Positive error on FxaW.m**-2stat.error;stat.maxfloatnullablee_Fx? Negative error on FxaW.m**-2stat.errorfloatnullablel_F2keVLimit flag on F2keVmeta.code.errorcharF2keVFlux density at rest-frame 2keV in units of 10^-32^erg/cm^2^/s/Hz (10^-9^Jy)nJyphot.flux;em.X-rayfloatl_L2keVLimit flag on log2keVmeta.code.errorcharL2keVLog monochromatic luminosity at rest-frame 2keV (log({nu}L_{nu}_))log(1e-07W)phys.luminosityfloatlogLLog luminosity in the rest-frame 2-10keV bandlog(1e-07W)phys.luminosityfloatl_aoxLimit flag on aoxmeta.code.errorcharaoxOptical-to-X-ray power-law slope (4)spect.indexfloatl_DaoxLimit flag on Daoxmeta.code.errorcharDaoxDifference between measured and predicted {alpha}_ox_ (5)stat.fit.residualfloatl_SigoxLimit flag on Sigoxmeta.code.errorcharSigoxSignificance of the difference between measured and predicted {alpha}_ox_ (6)stat.fit.residualfloataroRadio-to-optical power-law slope (7)spect.indexfloatf_aro[l] Radio flux density from NVSS (G1)meta.codecharqso7SDSS-DR7 quasar catalog data (Schneider et al. 2010, Cat. VII/260)meta.ref.urlcharSloanDisplay the SDSS data for this objectmeta.ref.urlchar_RAPositions from SDSS name (right ascension part)degpos.eq.ra;meta.main_DEPositions from SDSS name (declination part)degpos.eq.dec;meta.main