Fast Luminous Blue Transients in the Reionization Era and Beyond

TL;DR

Fast luminous blue transients (FLBTs) could serve as a new observational tool to probe the epoch of reionization, with upcoming surveys capable of detecting dozens of these events at high redshifts.

Contribution

This paper proposes using FLBTs as a novel method to study reionization, analyzing their detectability with future infrared surveys and estimating their potential event rates.

Findings

WFIRST can detect about 20 FLBTs during reionization.

FLBT detection rate is estimated at 2 per year per deg$^2$ at z>6.

Detection is feasible with a limiting magnitude of 26.5 mag and 10-day cadence.

Abstract

To determine the epoch of reionization precisely and to reveal the property of inhomogeneous reionization are some of the most important topics of modern cosmology. Existing methods to investigate reionization which use cosmic microwave background, Ly$\alpha$ emitters, quasars, or gamma ray bursts, have difficulties in terms of accuracy or event rate. We propose that recently discovered fast luminous blue transients (FLBTs) have a potential as a novel probe of reionization. We study the detectability of FLBTs at the epoch of reionization with upcoming WFIRST Wide-Field Instruments (WFI), using a star formation rate derived from galaxy observations and an event rate of FLBTs proportional to the star formation rate. We find that if FLBTs occur at a rate of 1\% of the core-collapse supernova rate, 2 (0.3) FLBTs per year per deg$^2$ at $z>6$ ($z>8$) can be detected by a survey with a limiting magnitude of 26.5 mag in the near-infrared band and a cadence of 10 days. We conclude that the WFIRST supernova deep survey can detect $\sim20$ FLBTs at the epoch of reionization in the near future.