Could the GRB-Supernovae GRB 031203 and XRF 060218 be Cosmic Twins?

TL;DR

This paper investigates whether the gamma-ray burst GRB 031203 and the X-ray flash XRF 060218 are fundamentally similar cosmic explosions, analyzing their high-energy properties and associated X-ray halos to understand their nature.

Contribution

The study provides detailed modeling of X-ray halos to constrain the properties of the X-ray blast from GRB 031203 and compares it with XRF 060218, proposing they may be cosmic twins.

Findings

GRB 031203 had an associated X-ray blast with fluence comparable to the gamma-ray event.

XRF 060218 likely involved a shock breakout or bright X-ray flare.

GRB 031203 and XRF 060218 may be nearly identical explosions, differing mainly in observed high-energy features.

Abstract

The gamma-ray burst (GRB) / X-ray flash (XRF) events GRB 031203, discovered by INTEGRAL, and XRF 060218, discovered by Swift, represent two of only five GRB-SNe with optical spectroscopic confirmation of their SN components. Yet their observed high-energy properties offer a sharp contrast: While GRB 031203 was detected as a short 40-s burst with a spectrum peaking at E_peak > 190 keV, XRF 060218 was a T_90 ~ 2100-s long, smoothly-evolving burst with peak energy E_peak = 4.9 keV. At the same time, the properties of the two expanding dust-scattered X-ray halos observed in a fast-response XMM-Newton observation of GRB 031203 reveal that this event was accompanied by an "X-ray blast" with fluence comparable to or greater than that of the prompt gamma-ray event. Taking this observation as our starting point, we investigate the likely properties of the X-ray blast from GRB 031203 via detailed modeling of the XMM data, discovering a third halo due to scattering off a more distant dust sheet at d_3 = 9.94 +/- 0.39 kpc, and constraining the timing of the X-ray blast relative to the GRB trigger time to be t_0 = 11 +/- 417 s. Using our constraints, we compare the properties of GRB 031203 to those of other GRB-SNe in order to understand the likely nature of its X-ray blast, concluding that a bright X-ray flare, as in GRB 050502B, or shock breakout event, as in XRF 060218, provide the most likely explanations. In the latter case, we consider the added possibility that XRF 060218 may have manifested an episode of bright gamma-ray emission prior to the burst observed by Swift, in which case GRB 031203 and XRF 060218 would be "cosmic twin" explosions with nearly identical high-energy properties.