Evidence for a proto-black hole and a double astrophysical component in GRB 101023

TL;DR

This paper presents evidence for a proto-black hole phase and a double-component structure in GRB 101023, suggesting a new GRB family linked to core-collapse, with implications for distance measurement and black hole formation understanding.

Contribution

It introduces a new GRB family with a proto-black hole component and provides a method to estimate redshift based on spectral and afterglow features.

Findings

First episode fits a black-body plus power-law model with evolving temperature.

Second episode is consistent with a canonical GRB.

Redshift estimated at approximately 0.9.

Abstract

[Shortened] Context: [...] we point out a striking similarity between GRB 101023 and GRB 090618. We explore the possibility that these sources are members of a new GRB family related to a single core-collapse. We use this understanding of the source in order to infer the unobserved redshift of GRB 101023. [...]. Aims: In precise analogy with GRB 090618 we aim to analyze the 89s of emission of GRB 101023 to see if we are in presence of two different episodes: the first one presenting a characteristic Black-body temperature evolution, evolving in time with a broken power-law, and the second one consistent with a canonical GRB. [...] Results: We confirm that the first episode can be well fit by a Black body plus a power-law model. The temperature changes with time following a broken power law, and the photon index of the power-law component presents a soft to hard evolution. We estimate the radius of this source, increasing with time with a velocity of 1.5x10^4 km/s. The second episode appears to be a canonical GRB. By using the Amati relation and the Atteia relation, we determine the cosmological redshift, z ~ 0.9 +- 0.084 (stat.) +- 0.2 (sys.). [...]. Particularly striking is the scaling law of the soft X-ray component of the afterglow. Conclusions: We identify GRB 090618 and GRB 101023 with a new family of GRBs presenting a double astrophysical component. A first one, related to the proto-black hole, prior to the process of gravitational collapse (episode 1) and a second one which is the canonical GRB (episode 2) emitted during the formation of the black-hole. [...] This analysis indicates progress towards developing a GRB distance indicator based on the understanding of the P-GRB and the prompt radiation as well as the soft X-Ray behavior of the late afterglow.