The afterglows of swift-era gamma-ray bursts. II. Type I GRB versus type II GRB optical afterglows

D. A. Kann, S. Klose, B. Zhang, S. Covino, N. R. Butler, D. Malesani, E. Nakar, A. C. Wilson, L. A. Antonelli, G. Chincarini, B. E. Cobb, P. D'Avanzo, V. D'Elia, M. Della Valle, P. Ferrero, D. Fugazza, J. Gorosabel, G. L. Israel, F. Mannucci, S. PiranomonteS. Schulze, L. Stella, G. Tagliaferri, K. Wiersema

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Abstract

Gamma-ray bursts (GRBs) have been separated into two classes, originally along the lines of duration and spectral properties, called "short/ hard" and "long/soft." The latter have been conclusively linked to the explosive deaths of massive stars, while the former are thought to result from the merger or collapse of compact objects. In recent years, indications have been accumulating that the short/hard versus long/soft division does not map directly onto what would be expected from the two classes of progenitors, leading to a new classification scheme called TypeI and TypeII which is based on multiple observational criteria. We use a large sample of GRB afterglow and prompt-emission data (adding further GRB afterglow observations in this work) to compare the optical afterglows (or the lack thereof) of TypeI GRBs with those of TypeII GRBs. In comparison to the afterglows of TypeII GRBs, we find that those of TypeI GRBs have a lower average luminosity and show an intrinsic spread of luminosities at least as wide. From late and deep upper limits on the optical transients, we establish limits on the maximum optical luminosity of any associated supernova (SN), confirming older works and adding new results. We use deep upper limits on TypeI GRB optical afterglows to constrain the parameter space of possible mini-SN emission associated with a compact-object merger. Using the prompt-emission data, we search for correlations between the parameters of the prompt emission and the late optical afterglow luminosities. We find tentative correlations between the bolometric isotropic energy release and the optical afterglow luminosity at a fixed time after the trigger (positive), and between the host offset and the luminosity (negative), but no significant correlation between the isotropic energy release and the duration of the GRBs. We also discuss three anomalous GRBs, GRB 060505, GRB 060614, and GRB 060121, in light of their optical afterglow luminosities.

Original languageEnglish (US)
Article number96
JournalAstrophysical Journal
Volume734
Issue number2
DOIs
StatePublished - Jun 10 2011

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Keywords

  • gamma-ray burst: general
  • gamma-ray burst: individual (GRB 060121, GRB 060505, GRB 060614)
  • stars: neutron

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Kann, D. A., Klose, S., Zhang, B., Covino, S., Butler, N. R., Malesani, D., Nakar, E., Wilson, A. C., Antonelli, L. A., Chincarini, G., Cobb, B. E., D'Avanzo, P., D'Elia, V., Della Valle, M., Ferrero, P., Fugazza, D., Gorosabel, J., Israel, G. L., Mannucci, F., ... Wiersema, K. (2011). The afterglows of swift-era gamma-ray bursts. II. Type I GRB versus type II GRB optical afterglows. Astrophysical Journal, 734(2), [96]. https://doi.org/10.1088/0004-637X/734/2/96