Show simple item record

Files in this item


Item metadata

dc.contributor.authorDenney, K. D.
dc.contributor.authorHorne, Keith
dc.contributor.authorBrandt, W. N.
dc.contributor.authorGrier, C. J.
dc.contributor.authorHo, Luis C.
dc.contributor.authorPeterson, B. M.
dc.contributor.authorTrump, J. R.
dc.contributor.authorGe, J.
dc.identifier.citationDenney , K D , Horne , K , Brandt , W N , Grier , C J , Ho , L C , Peterson , B M , Trump , J R & Ge , J 2016 , ' The Sloan Digital Sky Survey Reverberation Mapping Project : biases in z > 1.46 redshifts due to quasar diversity ' , Astrophysical Journal , vol. 833 , no. 1 , 33 .
dc.identifier.otherPURE: 248699734
dc.identifier.otherPURE UUID: 0227ca42-95b6-41b3-8b1c-336ba24f2f3e
dc.identifier.otherScopus: 85006701088
dc.identifier.otherWOS: 000390556900006
dc.description.abstractWe use the coadded spectra of 32 epochs of Sloan Digital Sky Survey (SDSS) Reverberation Mapping Project observations of 482 quasars with z > 1.46 to highlight systematic biases in the SDSS- and Baryon Oscillation Spectroscopic Survey (BOSS)-pipeline redshifts due to the natural diversity of quasar properties. We investigate the characteristics of this bias by comparing the BOSS-pipeline redshifts to an estimate from the centroid of He ii λ1640. He ii has a low equivalent width but is often well-defined in high-S/N spectra, does not suffer from self-absorption, and has a narrow component which, when present (the case for about half of our sources), produces a redshift estimate that, on average, is consistent with that determined from [O ii] to within the He ii and [O ii] centroid measurement uncertainties. The large redshift differences of ∼1000 km s-1, on average, between the BOSS-pipeline and He ii-centroid redshifts, suggest there are significant biases in a portion of BOSS quasar redshift measurements. Adopting the He ii-based redshifts shows that C iv does not exhibit a ubiquitous blueshift for all quasars, given the precision probed by our measurements. Instead, we find a distribution of C iv-centroid blueshifts across our sample, with a dynamic range that (i) is wider than that previously reported for this line, and (ii) spans C iv centroids from those consistent with the systemic redshift to those with significant blueshifts of thousands of kilometers per second. These results have significant implications for measurement and use of high-redshift quasar properties and redshifts, and studies based thereon.
dc.relation.ispartofAstrophysical Journalen
dc.rights© 2016. The American Astronomical Society. All rights reserved. This work is made available online in accordance with the publisher’s policies. This is the final published version of the work, which was originally published at:
dc.subjectGalaxies: activeen
dc.subjectGalaxies: distances and redshiftsen
dc.subjectGalaxies: nucleien
dc.subjectQuasars: emission linesen
dc.subjectQuasars: generalen
dc.subjectQuasars: supermassive black holesen
dc.subjectQB Astronomyen
dc.subjectQC Physicsen
dc.subjectAstronomy and Astrophysicsen
dc.subjectSpace and Planetary Scienceen
dc.titleThe Sloan Digital Sky Survey Reverberation Mapping Project : biases in z > 1.46 redshifts due to quasar diversityen
dc.typeJournal articleen
dc.contributor.sponsorScience & Technology Facilities Councilen
dc.description.versionPublisher PDFen
dc.contributor.institutionUniversity of St Andrews. School of Physics and Astronomyen
dc.contributor.institutionUniversity of St Andrews. St Andrews Centre for Exoplanet Scienceen
dc.description.statusPeer revieweden

This item appears in the following Collection(s)

Show simple item record