J/MNRAS/383/581ivo://CDS.VizieR/J/MNRAS/383/581doi:10.26093/cds/vizier.73830581CDSDong X.Wang T.Wang J.Yuan W.Zhou H.Dai H.Zhang K.2024-07-05T20:16:09Z2009-03-08T14:57:11ZCDS support team

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

cds-question@unistra.frquasarsactive-galactic-nucleiredshiftedspectroscopyultraviolet-astronomyWe have investigated the broad-line Balmer decrements (H{alpha/H{beta}) for a large, homogeneous sample of Seyfert 1 galaxies and quasi-stellar objects (QSOs) using spectroscopic data obtained in the Sloan Digital Sky Survey. The sample, drawn from the Fourth Data Release, comprises 446 low-redshift (z<=0.35) active galactic nuclei (AGN) that have blue optical continua as indicated by the spectral slopes in order to minimize the effect of dust extinction. We find that (i) the distribution of the intrinsic broad-line H{alpha}/H{beta} ratio can be well described by log-Gaussian, with a peak at H{alpha}/H{beta}=3.06 and a standard deviation of about 0.03dex only; (ii) the Balmer decrement does not correlate with AGN properties such as luminosity, accretion rate and continuum slope, etc.; (iii) on average, the Balmer decrements are found to be only slightly larger in radio-loud sources (3.37) and sources having double-peaked emission-line profiles (3.27) compared to the rest of the sample. We therefore suggest that the broad-line H{alpha}/H{beta} ratio can be used as a good indicator for dust extinction in the AGN broad-line region; this is especially true for radio-quiet AGN with regular emission-line profiles, which constitute the vast majority of the AGN population.2008MNRAS.383..581Dhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/383/581CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/282 : The SDSS Photometric Catalog, Release 6 (Adelman-McCarthy+, 2007)http://www.sdss.org : SDSS Home Pagehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/383/581https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/383/581http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/383/581https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/383/581https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/383/581http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/383/581GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/383/581/AGNs (Properties of blue AGNs, and their H{alpha} and H{beta} broad-line profiles)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/383/581/AGNs?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/383/581/AGNs?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/383/581/AGNs?GETtext/xml+votable180.050000true1.79170830.89138890.0055555555555555566/4098 4101 4105-4107 4118-4119 4187 4189 4201 4226 4229 4256 4258 4289 4352 4784 4826 4845 5008 5025 5043 5068 5070 5072 5111 5113 5437 5466-5467 5481 5483 5489 5494 5498 5511 5570 5576 5580 5584 5599 5602 5619 5623 5659 5682 5685 5687-5688 5723 5733 5746 5748 5756-5757 5820-5821 5825 5831 5855 5860 5876 5913 5929 5947 5957 5985 5988 6015 6018 6028 6034 6045 6097 6106 6121 6124 6208 6211 6223 6235 6244-6245 6260 6264 6267 6270 6387 6400 6423 6458 6466 6468 6473 6505 6515 6520 6555 6574 6577 6582 6593 6595 6598 6600 6605 6613 6628 6632-6633 6644 7172-7173 7176 7193 7209 7214 7218 7220 7222 7225 7231 7242 7277 7280 7296 7303 7305 7324 7326 7381 7426 7445-7446 7448 7461 7469 7488 7526-7527 8742 9063 9068 9074 9167 9198 9200 9208 9212-9213 9333 9368 9377 9393 9422 9458 9470-9471 9473 9483 9504 9606 9635 9765 9790 9795 9844 9891 9923 9948 9967-9968 9982 9998 10017 10022 10104 10188 10190-10191 10219 10234 10495 10518 10522 10551 10563 10571 10577-10578 10584 10604 10612 10653 10657 10665 10670 10678 10694 10703 10724 10751 10836 10846 10871 10873 10910 10939 10956 10959 10967 10975 10993 11003 11013-11014 11112-11113 11118 11154 11157 11160 11213 11233 11275-11276 11286 11300 11311-11312 11342 11352 11370 11394 11399 11419 11435 11454-11455 11459 11467 11475 11502 11520 11593 11610 11781 11783 11804 11807 11816 11830 11848 11872 11878 11881 11909 11918 11922 11930 11932 11942 17240 17251 17260 17300 17317 17497 17499 17665 17822 17825 17827 18011 18020 18089 18094 18114 18393 18404 18407 18413 18532 18582 18599 18769 18771 18775 18794 18837 19048 19052 19101 19111 19200 19327 19387 19407 19413 19416 19698 19740 19991 20033 21887 21976 21983 22005 23047-23048 23076 23150 23190 23196 23216 25850 25950 25968 25977 25980 26014 26017 26022 26064 26070 26209 26223 26228 26233 26287 26295 26297 26305 26308 26310 26338 26376 26379 26381 26396 26401 26486 26552 26606 26951-26952 26958 26965 26975-26976 26988 26995 26998 27033 27048 27072 27075 27079-27080 27092-27093 27110 27116 27119 27124 27129 27198 27224 27249 27252 27255 27293 27300 27324 27326 27343 27349-27350 27367 27379 27384 27440 27475 27501 27505 27513 27530 27537 27544 27565 27580 27591 27654 27682 27686 27697 27699 27708 27737 27742 27784 27788 27824-27825 27848 27938 30040 30043 31291 31314-31315 31321 31353 31372 31381 31384-31385 31657 32403 32406 32683 36777 36782 36804 49009 49019 491042.381800341673347e-19 2.821731604724377e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/383/581?format=asciiUVOpticaldefaultJ/MNRAS/383/581/AGNsProperties of blue AGNs, and their H{alpha} and H{beta} broad-line profilesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSDSSObject J2000.0 name (HHMMSS.ss+DDMMSS.s)meta.id;meta.maincharzSDSS spectroscopic redshiftsrc.redshiftdoubleL5100Monochromatic luminosity at 5100{AA}1e-07Wphys.luminosityfloatF(Hbn)H{beta} narrow component flux (1)1e-20W.m**-2phot.flux;em.line.HbetafloatF(Hbb)H{beta} broad component flux (2)1e-20W.m**-2phot.flux;em.line.HbetafloatF(Han)H{alpha} narrow component flux (3)1e-20W.m**-2phot.flux;em.line.HalphafloatF(Hab)H{alpha} broad component flux (3)1e-20W.m**-2phot.flux;em.line.Halphafloatalpha1Continuum slope blueward of 5600{AA}, F({lambda}){prop.to}{lambda}^-{alpha}1^ (2)spect.indexfloatalpha2Continuum slope redward of 5600{AA}, F({lambda}){prop.to}{lambda}^-{alpha}2^ (2)spect.indexfloatFUV? GALEX calibrated magnitude (AB) in FUV band (135-175nm) (4)(5)magphot.mag;em.UVfloatnullableNUV? GALEX calibrated magnitude (AB) in NUV band (175-280nm) (4)(5)magphot.mag;em.UVfloatnullableimagSDSS i-band magnitude (AB) (4)magphot.mag;em.opt.IfloatE(B-V)Galactic colour excess derived from Schlegel et al. (1998ApJ...500..525S)magphot.color.excessfloatl_SintLimit flag on Sintmeta.code.errorcharSint? Integrated flux density at 20cm detected by FIRST (6)mJyphot.flux.density;em.radio.750-1500MHzfloatnullableFWHMbBroad H{beta} FWHMkm/sphys.angSizefloatsigmabBroad H{beta} line dispersionkm/sphys.veloc.dispersionfloatAIbBroad H{beta} asymmetry index (1)spect.index;em.line.HbetafloatSIbBroad H{beta} shape index (2)spect.index;em.line.HbetafloatKI1bBroad H{beta} Kurtosis index (3)spect.index;em.line.HbetafloatFWHMaBroad H{alpha} FWHMkm/sphys.angSizefloatsigmaaBroad H{alpha} line dispersionkm/sphys.veloc.dispersionfloatAIaBroad H{alpha} asymmetry index (1)spect.index;em.line.HalphafloatSIaBroad H{alpha} shape index (2)spect.index;em.line.HalphafloatKI1aBroad H{alpha} Kurtosis index (3)spect.index;em.line.HalphafloatSloanDisplay the SDSS data for this quasarmeta.ref.urlchar_RARight ascension (derived from SDSS) for Eq=J2000.0degpos.eq.ra;meta.main_DEDeclination (derived from SDSS) for Eq=J2000.0degpos.eq.dec;meta.main