Unveiling the Origin of Fast Radio Bursts by Optical Follow Up Observations

TL;DR

This paper explores the potential of optical follow-up observations to identify kilonovae as counterparts of fast radio bursts, focusing on detection strategies, distinguishing features, and implications for understanding FRB origins.

Contribution

It proposes methods to detect and differentiate kilonovae from supernovae in optical follow-ups, providing insights into the possible origins of FRBs from neutron star mergers or white dwarf binaries.

Findings

Kilonovae can be detected up to z ~ 0.3 with current models.

Rapid decay and color evolution distinguish kilonovae from supernovae.

Chance of misidentifying SNe Ia as FRB counterparts is very low.

Abstract

We discuss how we can detect and identify counterparts of fast radio bursts (FRBs) in future optical follow up observations of FRBs if real-time alert of FRBs becomes available. We consider kilonovae as candidates of FRB optical counterparts, as expected in the case that FRBs originate from mergers of double neutron star binaries. Although theoretical predictions on luminosities of kilonovae are still highly uncertain, recent models suggest that kilonovae can be detected at redshifts up to z $\sim$ 0.3 within the range of the uncertainties. We expect $\sim$ 1--5 unrelated supernovae (SNe) down to a similar variability magnitude in 5 days interval within the typical error radius of a FRB. We show that, however, a kilonova can be distinguished from these SNe by its rapid decay and/or color evolution, making it possible to verify the existence of a kilonova associated with a FRB. We also discuss the case that SNe Ia are FRB optical counterparts, as it might be if FRBs originate from double white dwarf binaries. Verification of this scenario is also possible, since the chance probability of finding a SNe Ia having consistent explosion time with that of a FRB within the FRB error region is small (typically $\lesssim$ 0.01).