Monthly Notices of the Royal Astronomical Society | 2021
Changing look AGN Mrk 590: Broad line region and black hole mass from photometric reverberation mapping
Abstract
\n We present the results of photometric reverberation mapping observations on the changing look active galactic nucleus Mrk 590 at z = 0.026. The observations were carried out from July to December, 2018 using broad-band B, R and narrow band Hα and S II filters. B-band traces the continuum emission from the accretion disk, R-band encompasses both the continuum emission from the accretion disk and the redshifted Hα line from the broad line region (BLR), S II band contains the redshifted Hα emission and the Hα band traces the continuum emission underneath the S II band. All the light curves showed strong variation with a fractional root-mean-square variation of 0.132 ± 0.001 in B-band and 0.321 ± 0.001 in Hα line. From cross-correlation function analysis, we obtained a delayed response of Hα line emission to the optical B-band continuum emission of $21.44^{+1.49}_{-2.11}$ days in the rest-frame of the source, corresponding to a linear size of the BLR of 0.018\xa0pc. This is consistent with previous estimates using Hβ. By combining the BLR size with the Hα line full width at half maximum of 6478 ± 240\xa0km s−1 measured from a single-epoch spectrum obtained with the Subaru telescope, we derived a black hole mass of $1.96^{+0.15}_{-0.21}\\times 10^8 M_{\\odot }$.