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dc.contributor.authorLewis, K.T.pt_BR
dc.contributor.authorEracleous, Michaelpt_BR
dc.contributor.authorStorchi-Bergmann, Thaisapt_BR
dc.date.accessioned2015-01-20T02:15:15Zpt_BR
dc.date.issued2010pt_BR
dc.identifier.issn0067-0049pt_BR
dc.identifier.urihttp://hdl.handle.net/10183/109054pt_BR
dc.description.abstractAn increasing number of active galactic nuclei (AGNs) exhibit broad, double-peaked Balmer emission lines, which represent some of the best evidence for the existence of relatively large-scale accretion disks in AGNs. A set of 20 double-peaked emitters have been monitored for nearly a decade in order to observe long-term variations in the profiles of the double-peaked Balmer lines. Variations generally occur on timescales of years, and are attributed to physical changes in the accretion disk. Here we characterize the variability of a subset of seven double-peaked emitters in a model independent way. We find that variability is caused primarily by the presence of one or more discrete “lumps” of excess emission; over a timescale of a year (and sometimes less) these lumps change in amplitude and shape, but the projected velocity of these lumps changes over much longer timescales (several years). We also find that all of the objects exhibit red peaks that are stronger than the blue peak at some epochs and/or blueshifts in the overall profile, contrary to the expectations for a simple, circular accretion disk model, thus emphasizing the need for asymmetries in the accretion disk. Comparisons with two simple models, an elliptical accretion disk and a circular disk with a spiral arm, are unable to reproduce all aspects of the observed variability, although both account for some of the observed behaviors. Three of the seven objects have robust estimates of the black hole masses. For these objects the observed variability timescale is consistent with the expected precession timescale for a spiral arm, but incompatible with that of an elliptical accretion disk.We suggest that with the simple modification of allowing the spiral arm to be fragmented, many of the observed variability patterns could be reproduced.en
dc.format.mimetypeapplication/pdf
dc.language.isoengpt_BR
dc.relation.ispartofThe astrophysical journal. Supplement series. Chicago. Vol. 187, no. 2 (Apr. 2010), p. 416-446pt_BR
dc.rightsOpen Accessen
dc.subjectAccretion, accretion disksen
dc.subjectDiscos de acrecaopt_BR
dc.subjectNucleo galaticopt_BR
dc.subjectGalaxies: activeen
dc.subjectLine: profilesen
dc.subjectGaláxias ativaspt_BR
dc.subjectBuracos negrospt_BR
dc.titleLong-term profile variability in active galactic nucleus with double-peaked Balmer emission linespt_BR
dc.typeArtigo de periódicopt_BR
dc.identifier.nrb000766507pt_BR
dc.type.originEstrangeiropt_BR


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