Observational properties of a general relativistic instability supernova from a primordial supermassive star

TL;DR

This paper models the observational signatures of a supernova from a primordial supermassive star, suggesting it could be detected at high redshifts with upcoming infrared telescopes, providing insights into early Universe stellar explosions.

Contribution

It presents the first radiation hydrodynamics simulation of a general relativistic instability supernova from a primordial supermassive star, predicting its observable properties and detection prospects.

Findings

GRSN exhibits a 550-day luminous plateau phase.

It can be observed up to redshift z ~ 15 with JWST and G-REX.

Deep infrared imaging can identify GRSNe without time domain data.

Abstract

We present the expected observational properties of a general relativistic instability supernova (GRSN) from the 55,500 Msun primordial (Population III) star. Supermassive stars exceeding 1e4 Msun may exist in the early Universe. They are generally considered to collapse through the general relativistic instability to be seed black holes to form supermassive (~ 1e9 Msun) black holes observed as high-redshift quasars. Some of them, however, may explode as GRSNe if the explosive helium burning unbinds the supermassive stars following the collapse triggered by the general relativistic instability. We perform the radiation hydrodynamics simulation of the GRSN starting shortly before the shock breakout. We find that the GRSN is characterized by a long-lasting (550 d) luminous (1.5e44 erg/s) plateau phase with the photospheric temperature of around 5000 K in the rest frame. The plateau phase lasts for decades when it appears at high redshifts and it will likely be observed as a persistent source in the future deep near-infrared imaging surveys. Especially, the near-infrared images reaching 29 AB magnitude that can be obtained by Galaxy and Reionization EXplorer (G-REX) and James Webb Space Telescope (JWST) allow us to identify GRSNe up to z ~ 15. Deeper images enable us to discover GRSNe at even higher redshifts. Having extremely red color, they can be distinguished from other persistent sources such as high-redshift galaxies by using color information. We conclude that the deep near-infrared images are able to constrain the existence of GRSNe from the primordial supermassive stars in the Universe even without the time domain information.