Reverberation mapping of Active Galactic Nuclei

Hlabathe, Michael

Reverberation mapping of Active Galactic Nuclei

Doctoral Thesis

2023

Abstract

Recent times have seen an increase in observational campaigns aimed at contributing to the overall sample of active galactic nuclei (AGNs) with central super-massive black hole (SMBH) mass estimates using reverberation mapping (RM) technique. RM makes use of the time variability of the broad emission lines from the nearby broad-line region (BLR) to measure their time response or delay (τ) relative to the incident ionizing continuum from the accretion disc. This delay is a consequence of light-travel time effects and directly enables the size of the BLR to be determined as RBLR = cτ (c is speed of light). Assuming virialized motions of the gas clouds in the BLR, and combining the velocity width (∆V ) of a Doppler broadened emission line with RBLR leads to the estimation of the black hole mass M. RM can also be used to measure the accretion-disc size in which the X-ray variability source is assumed to drive UV/optical variations in the accretion disc leading to wavelength-dependent delays that scale as τ ∝ λ 4/3 . Here, both aspects of RM are explored using photometric and spectroscopic observations of 3C 120, PG 2304+043 and SDSS J132447.65+032432.6, with observations emanating from the Southern African Large Telescope (SALT) and Las Cumbres Observatory (LCO) robotic telescopes. The broad emission-line and inter-band continuum delays in these AGNs are measured using the Interpolated Cross-Correlation Function (ICCF) and Continuum REverberation AGN Markov Chain Monte Carlo (CREAM).

Keywords

Galactic Nuclei

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PhD / Doctoral

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