A link between prompt optical and prompt γ-ray emission in γ-ray bursts

Los Alamos National Laboratory, Space Science and Applications Group, ISR-1, MS-D466, Los Alamos, New Mexico 87545, USA.
Nature (Impact Factor: 41.46). 06/2005; 435(7039):178-80. DOI: 10.1038/nature03515
Source: PubMed


The prompt optical emission that arrives with the gamma-rays from a cosmic gamma-ray burst (GRB) is a signature of the engine powering the burst, the properties of the ultra-relativistic ejecta of the explosion, and the ejecta's interactions with the surroundings. Until now, only GRB 990123 had been detected at optical wavelengths during the burst phase. Its prompt optical emission was variable and uncorrelated with the prompt gamma-ray emission, suggesting that the optical emission was generated by a reverse shock arising from the ejecta's collision with surrounding material. Here we report prompt optical emission from GRB 041219a. It is variable and correlated with the prompt gamma-rays, indicating a common origin for the optical light and the gamma-rays. Within the context of the standard fireball model of GRBs, we attribute this new optical component to internal shocks driven into the burst ejecta by variations of the inner engine. The correlated optical emission is a direct probe of the jet isolated from the medium. The timing of the uncorrelated optical emission is strongly dependent on the nature of the medium.

Download full-text


Available from: Derek Hullinger
  • Source
    • "That said, a few persuasive observations of reverse-shock optical emission have been made in the Swift era, so it can finally be said that GRB 990123 does not stand alone. The early optical/IR emission from GRB 041219 would have rivalled that seen from GRB 990123 if not for the large Galactic extinction along the line of sight [36] "
    [Show abstract] [Hide abstract]
    ABSTRACT: We review the fireball shock model of gamma-ray burst prompt and early afterglow emission in light of rapid follow-up measurements made and enabled by the multi-wavelength Swift satellite. These observations are leading to a reappraisal and expansion of the previous standard view of the GRB and its fireball. New information on the behavior of the burst and afterglow on minutes to hour timescales has led, among other results, to the discovery and follow-up of short GRB afterglows, the opening up of the z>6 redshift range, and the first prompt multi-wavelength observations of a long GRB-supernova. We discuss the salient observational results and some associated theoretical issues.
    Full-text · Article · Oct 2006 · New Journal of Physics
  • [Show abstract] [Hide abstract]
    ABSTRACT: This work aims at providing dynamic estimates of a soil wetness index in the Mackenzie River Basin, in northwest Canada. The method used in this study is based on the Basin Wetness Index (BWI), which is computed using the brightness temperature remotely sensed by SSM/I in the 19, 37 and 85 GHz channels and the soil surface temperature. In its basic formulation, the BWI uses two empirical parameters that are constant in both time and space. The basin heterogeneity and the temporal evolution of the vegetation state suggest that these parameters could vary. An alternative approach is proposed that allows for a reassessment of the empirical constants at the reception of each new image. The index was computed on a daily basis for the summer season of 1999, pixel wise (625 km<sub>2</sub>) over the entire surface of the Mackenzie Rive Basin (1.8×10<sup>6</sup> km<sup>2</sup>), which roughly comprises 20% of Canada. The BWI estimates reliability was assessed with a combination including in-situ measurements and hydrological modeling.
    No preview · Conference Paper · Aug 2003
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Gamma-ray burst (GRB) dust echoes were first proposed as an alternative explanation for the supernova-like (SN-like) components to the afterglows of GRB 980326 and GRB 970228. However, the spectroscopic identification of Type Ic SN 2003dh associated with GRB 030329, as well as the identification of SN-like components to the afterglows of other GRBs, appears to have confirmed the GRB/SN paradigm. However, the likely progenitors of Type Ic SNe are Wolf-Rayet WC stars, and late-type WC stars have been observed to be surrounded by dust, at a distance of 10^14 -- 10^15 cm from the star. Consequently, we revisit the possibility of GRB dust echoes, not on a timescale of weeks after the burst but on a timescale of minutes to hours. We find that if the optical flash is sufficiently bright and the jet sufficiently wide, GRB afterglows may be accompanied by chromatic variations on this timescale. From these signatures, such model parameters as the inner radius of the dust distribution, the initial opening angle of the jet, etc., may be deduced. With rapid and regular localizations of GRBs by HETE-2, Integral, and now Swift, and new and improved robotic telescope systems, these early-time GRB dust echoes may soon be detected. We describe one such robotic telescope system, called PROMPT, that the University of North Carolina at Chapel Hill is building at the Cerro Tololo Inter-American Observatory in greater detail. Comment: Accepted to The Astrophysical Journal, 15 pages, 5 figures, LaTeX
    Full-text · Article · Sep 2004 · The Astrophysical Journal
Show more