REVERBERATION MAPPING with INTERMEDIATE-BAND PHOTOMETRY: DETECTION of BROAD-LINE Hα TIME LAGS for QUASARS at 0.2 < z < 0.4

Linhua Jiang, Yue Shen, Ian D. McGreer, Xiaohui Fan, Eric Morganson, Rogier Windhorst

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

We present a reverberation mapping (RM) experiment that combines broad- and intermediate-band photometry; it is the first such attempt targeting 13 quasars at 0.2 < z < 0.9. The quasars were selected to have strong Hα or Hβ emission lines that are located in one of three intermediate bands (with FWHM around 200) centered at 8045, 8505, and 9171. The imaging observations were carried out in the intermediate bands and the broad i and z bands using the prime-focus imager 90Prime on the 2.3 m Bok telescope. Because of the large (∼1 deg2) field of view (FOV) of 90Prime, we included the 13 quasars within only five telescope pointings or fields. The five fields were repeatedly observed over 20-30 epochs that were unevenly distributed over a duration of 5-6 months. The combination of the broad- and intermediate-band photometry allows us to derive accurate light curves for both optical continuum emission (from the accretion disk) and line emission (from the broad-line region, or BLR). We detect Hα time lags between the continuum and line emission in six quasars. These quasars are at relatively low redshifts 0.2 < z < 0.4. The measured lags are consistent with the current BLR size-luminosity relation for Hβ at z < 0.3. While this experiment appears successful in detecting lags of the bright Hα line, further investigation is required to see if it can also be applied to the fainter Hβ line for quasars at higher redshifts. Finally we demonstrate that, by using a small telescope with a large FOV, intermediate-band photometric RM can be efficiently executed for a large sample of quasars at z > 0.2.

Original languageEnglish (US)
Article number137
JournalAstrophysical Journal
Volume818
Issue number2
DOIs
StatePublished - Feb 20 2016

Keywords

  • galaxies: active
  • quasars: emission lines
  • quasars: general
  • quasars: supermassive black holes Supporting material: data behind figures

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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