Reverberation Mapping of PG 0934+013 with the Southern African Large Telescope

TL;DR

This study uses reverberation mapping with the Southern African Large Telescope to measure the black hole mass in PG 0934+013 by analyzing emission line variability and time lags over a two-year period.

Contribution

First detailed reverberation mapping of PG 0934+013 using the SALT telescope, providing new black hole mass estimates through combined photometric and spectroscopic data.

Findings

Hβ lag of approximately 8.5 days in Year 2 data

Black hole mass estimated at about 3.1 million solar masses

Measured Hβ line dispersion of 668 km/s

Abstract

We present the variability and time lag measurements of PG 0934+013 based on a photometric and spectroscopic monitoring campaign over a two year period. We obtained 46 epochs of data from the spectroscopic campaign, which was carried out using the Southern African Large Telescope with $\sim$1 week cadence over two sets of 4 month-long observing period, while we obtained 80 epochs of \textit{B}-band imaging data using a few 1-m class telescopes. Due to the seven month gap between the two observing periods, we separately measured the time lags of broad emission lines including H$\beta$, by comparing the emission line light curve with the \textit{B}-band continuum light curve using the cross-correlation function techniques. We determined the H$\beta$ lag, $\tau_{\rm cent} = 8.46^{+2.08}_{-2.14}$ days in the observed-frame based on Year 2 data, while the time lag from Year 1 data was not reliably determined. Using the rms spectrum of Year 2 data, we measured the \Hb\ line dispersion \sigmaline = 668 $\pm$ 44 \kms\ after correcting for the spectral resolution. Adopting a virial factor f = 4.47 from Woo et al. 2015, we determined the black hole mass M$_{BH}$ = $3.13 ^{+0.91} _{-0.93} \times 10^{6}$ \msun based on the \Hb\ time lag and velocity.