2006/06/22 by En‐Wei Liang, Liang, Enwei, Bing Zhang +5
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics (astro-ph) #FOS: Physical sciences #Gamma-ray bursts and supernovae #Pulsars and Gravitational Waves Research
paper · pdf · doi:10.48550/arxiv.astro-ph/0606565
openalex publication_date 2006/06/22 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
It is long speculated that long duration gamma-ray bursts (GRBs) originate froma relativistic jet emerging from a collapsing massive star progenitor. Although associations of core-collapsing supernovae with long GRB afterglows have been identified in a number of systems, including the latest X-ray flash (XRF) 060218/SN 2006aj connection detected by Swift, direct evidence of a relativistic jet emerging from a collapsing star is still lacking. Here we report the detection of a thermal emission component (high-T component) accompanying the prompt X-ray emission of XRF 060218, with temperature kTH=1.21+0.22/-0.24 keV and effective blackbody radius RH~ 5× 109 cm. This high-T component co-exists with another low-T thermal component as reported by Campana et al. 2006 for at least 2700 seconds, but evolves independently with respect to the low-T component by tracing the lightcurve of the non-thermal component. We identify this high-T thermal component as the emission of a hot cocoon surrounding the relativistic jet, as expected from the theoretical models.