TNT photometric reverberation mapping analysis of high-redshift quasars

Supermassive black hole (SMBH) mass determination is essential for understanding the galaxy-SMBH co-evolution. Photometric reverberation mapping (PRM) has been proposed as an alternative to the traditional method, spectroscopic reverberation mapping (SRM), which has limitation to only relatively low redshift, z, and bright objects. However, the most common and important sample of high-z active galaxies known as quasar or QSO have its populations peak at around z ≈ 2-3 thus out of reach for the SRM. We carried out a proof-of-concept campaign of quasar PRM using the 2.4-m Thai National Telescope (TNT) between 2015-2018. Such a study is important to inform a future wide-field high-cadence survey such as the Large Synoptic Survey Telescope (LSST). Our main sample contains 10 quasars at redshift z ≈ 0.7-1.2 with r_SDSS = 19.7-20.7 mag, selected from the SDSS data release 10. The processed data and light curves were analysed using the discrete cross-correlation function (DCF). We used Monte Carlo (MC) simulations to model the noise characteristics and non-uniform coverage of our data as well as to verify robustness of the DCF results. Our analyses show a significant detection of lag time between continuum and broad-line emission bands of the quasar SDSS J081506.93+254124.7 (z = 1.18, r_SDSS = 20.5 mag). The estimated broad line region (BLR) distance is 125±20 light-day which equate to the estimated SMBH mass of (4.3±2.0)×10⁸ M _#x2299;. (paper)