A Quasar microlensing event towards J1249+3449?

TL;DR

This paper investigates an optical flare in a quasar, suggesting it is likely caused by microlensing from a star, while acknowledging alternative explanations like a binary black hole merger. The analysis supports microlensing as a plausible cause.

Contribution

The study provides evidence that the observed flare is consistent with a quasar microlensing event, offering insights into the nature of such transient phenomena.

Findings

Optical flare matches microlensing by a 0.1 solar mass star.

Alternative explanation as a binary black hole merger remains plausible.

Supports microlensing as a significant factor in quasar variability.

Abstract

We show that the optical flare event discovered by Graham et al. (2020) towards the active galactic nucleus J1249+3449 is fully consistent with being a quasar microlensing event due to a $\simeq 0.1 M_{\odot}$ star, although other explanations, such as that, mainly supported by Graham et al. (2020), of being the electromagnetic counterpart associated to a binary black hole merger, cannot be completely excluded at present.