# The Sloan Digital Sky Survey Reverberation Mapping Project: Accretion and Broad Emission Line Physics from a Hypervariable Quasar

## TL;DR

This study investigates a highly variable quasar, revealing that its luminosity changes are driven by intrinsic accretion processes affecting broad emission lines, challenging standard thin disk models and suggesting a thick disk or reprocessing scenario.

## Contribution

It provides detailed observational evidence linking quasar variability to accretion physics and challenges existing thin disk models, proposing alternative geometries or reprocessing mechanisms.

## Key findings

- Broad emission lines respond to continuum changes as expected for photoionization.
- Luminosity variations are intrinsic, not due to obscuration.
- Standard thin disk models cannot explain the observed variability.

## Abstract

We analyze extensive spectroscopic and photometric data of the hypervariable quasar SDSS J131424+530527 (RMID 017) at z=0.456, an optical "changing look" quasar from the Sloan Digital Sky Survey Reverberation Mapping project that increased in optical luminosity by a factor of 10 between 2014 and 2017. The observed broad emission lines all respond in luminosity and width to the changing optical continuum, as expected for photoionization in a stratified, virialized broad emission line region. The luminosity changes therefore result from intrinsic changes in accretion power rather than variable obscuration. The variability is continuous and apparently stochastic, disfavoring an origin as a discrete event such as a tidal disruption flare or microlensing event. It is coordinated on day timescales with blue leading red, consistent with reprocessing powering the entire optical SED. We show that this process cannot work in a standard thin disk geometry on energetic grounds, and would instead require a large covering factor reprocessor. Disk instability models could potentially also explain the data, provided that the instability sets in near the inner radius of a geometrically thick accretion disk.