The Sloan Digital Sky Survey reverberation mapping project : first broad-line Hβ and Mg II lags at z ≳ 0.3 from six-month spectroscopy
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Reverberation mapping (RM) measurements of broad-line region (BLR) lags in z > 0.3 quasars are important for directly measuring black hole masses in these distant objects, but so far there have been limited attempts and success given the practical difficulties of RM in this regime. Here we report preliminary results of 15 BLR lag measurements from the Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) project, a dedicated RM program with multi-object spectroscopy designed for RM over a wide redshift range. The lags are based on the 2014 spectroscopic light curves alone (32 epochs over six months) and focus on the Hβ and Mg II broad lines in the 100 lowest-redshift (z <0.8) quasars included in SDSS-RM; they represent a small subset of the lags that SDSSRM (including 849 quasars to z ∼ 4.5) is expected to deliver. The reported preliminary lag measurements are for intermediate-luminosity quasars at 0.3 ≲ z <0.8, including nine Hβ lags and six Mg II lags, for the first time extending RM results to this redshift-luminosity regime and providing direct quasar black hole mass estimates over approximately half of cosmic time. The Mg II lags also increase the number of known Mg II lags by several fold and start to explore the utility of Mg II for RM at high redshift. The location of these new lags at higher redshifts on the observed BLR size-luminosity relationship is statistically consistent with previous Hβ results at z <0.3. However, an independent constraint on the relationship slope at z > 0.3 is not yet possible owing to the limitations in our current sample. Our results demonstrate the general feasibility and potential of multi-object RM for z > 0.3 quasars.
Shen , Y , Horne , K , Grier , C J , Peterson , B M , Denney , K D , Trump , J R , Sun , M , Brandt , W N , Kochanek , C S , Dawson , K S , Green , P J , Greene , J E , Hall , P B , Ho , L C , Jiang , L , Kinemuchi , K , McGreer , I D , Petitjean , P , Richards , G T , Schneider , D P , Strauss , M A , Tao , C , Wood-Vasey , W M , Zu , Y , Pan , K , Bizyaev , D , Ge , J , Oravetz , D & Simmons , A 2016 , ' The Sloan Digital Sky Survey reverberation mapping project : first broad-line H β and Mg II lags at z ≳ 0.3 from six-month spectroscopy ' Astrophysical Journal , vol 818 , no. 1 , 30 , pp. 1-17 . DOI: 10.3847/0004-637X/818/1/30
© 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 https://dx.doi.org/10.3847/0004-637X/818/1/30
Support for the work of Y.S. was provided by NASA through Hubble Fellowship grant number HST-HF-51314, awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. K.H. acknowledges support from UK Science and Technology Facilities Council (STFC) grant ST/M001296/1. C.J.G. and W.N.B. acknowledge support from NSF grant AST-1517113 and the V.M. Willaman Endowment. B.M.P. is grateful for support from the National Science Foundation through grant AST-1008882. K.D.D. is supported by an NSF AAPF fellowship awarded under NSF grant AST-1302093. J.R.T. acknowledges support from NASA through Hubble Fellowship grant HST-HF-51330 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA under contract NAS 5-26555. M.S. acknowledges support from the China Scholarship Council (No. 3009). L.C.H. is supported by the Chinese Academy of Science through grant No. XDB09030102 (Emergence of Cosmological Structures) from the strategic Priority Research Program, and from the National Natural Science Foundation of China through grant No. 11473002. L.J. acknowledges the support from a 985 project at Peking University. Funding for SDSS-III has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, and the U.S. Department of Energy Office of Science.