research
Reverberation Mapping of the Kepler-Field AGN KA1858+4850
- Publication date
- Publisher
Abstract
KA1858+4850 is a narrow-line Seyfert 1 galaxy at redshift 0.078 and is among the brightest active galaxies monitored by the Kepler mission. We have carried out a reverberation mapping campaign designed to measure the broad-line region size and estimate the mass of the black hole in this galaxy. We obtained 74 epochs of spectroscopic data using the Kast Spectrograph at the Lick 3-m telescope from February to November of 2012, and obtained complementary V-band images from five other ground-based telescopes. We measured the Hbeta light curve lag with respect to the V-band continuum light curve using both cross-correlation techniques (CCF) and continuum light curve variability modeling with the JAVELIN method, and found rest-frame lags of CCF = 13.53+2.03 2.32 days and JAVELIN = 13.15+1.08 1.00 days. The Hbeta root-mean-square line profile has a width of sigma line = 770 +/- 49 km s(exp -1). Combining these two results and assuming a virial scale factor of f = 5.13, we obtained a virial estimate of M(sub BH) = 8.06+1.59 1.72 10(exp 6) solar mass for the mass of the central black hole and an Eddington ratio of L/L(sub Edd) (is) approx. 0.2. We also obtained consistent but slightly shorter emission-line lags with respect to the Kepler light curve. Thanks to the Kepler mission, the light curve of KA1858+4850 has among the highest cadences and signal-to-noise ratios ever measured for an active galactic nucleus; thus, our black hole mass measurement will serve as a reference point for relations between black hole mass and continuum variability characteristics in active galactic nuclei