Dust properties in afterglow of GRB 071025 at z~5

TL;DR

This study confirms that the dust observed in the high-redshift GRB 071025 afterglow likely originated from supernovae, especially those with intermediate progenitor masses, and suggests minimal dust destruction effects.

Contribution

Re-examined the extinction properties of GRB 071025 with new data and tested various supernova dust models, identifying the most plausible progenitor masses and dust formation mechanisms.

Findings

Dust in GRB 071025 is likely from SNe, especially 13 or 25 solar mass models.

Pair-instability SNe models poorly fit the observed data.

Dust destruction by reverse shocks appears negligible in this case.

Abstract

At high redshift, the universe was so young that core-collapse supernovae (SNe) are suspected to be the dominant source of dust production. However, some observations indicate that the dust production by SNe is an inefficient process, casting doubts on the existence of abundant SNe-dust in the early universe. Recently, Perley et al. (2010) reported that the afterglow of GRB 071025 - an unusually red GRB at z ~ 5 - shows evidence for the SNe-produced dust. Since this is perhaps the only high redshift GRB exhibiting compelling evidence for SNe-dust but the result could easily be affected by small systematics in photometry, we re-examined the extinction properties of GRB 071025 using our own optical/near-infrared data at a different epoch. In addition, we tested SNe-dust models with different progenitor masses and dust destruction efficiencies to constrain the dust formation mechanisms. By searching for the best-fit model of the afterglow spectral energy distribution, we confirm the previous claim that the dust in GRB 071025 is most likely to originate from SNe. We also find that the SNe-dust model of 13 or 25M_{\odot} without dust destruction fits the extinction property of GRB 071025 best, while pair-instability SNe (PISNe) models with a 170M_{\odot} progenitor poorly fit the data. Our results indicate that, at least in some systems at high redshift, SNe with intermediate masses within 10 - 30M_{\odot} were the main contributors for the dust enrichment, and the dust destruction effect due to reverse shock was negligible.