Gamma-Ray Burst Environments and Progenitors
Gamma-Ray Burst Environments and Progenitors
复制标题
DOI：
10.1086/312147
复制
发表时间：
1999-04
期刊：
影响因子：
--
通讯作者：
R. Chevalier;Zhi-Yun Li
中科院分区：
文献类型：
--
作者：
R. Chevalier;Zhi-Yun Li
伽马射线暴（GRB）的可能起源是致密天体的合并或大质量恒星的爆炸。这两种情况具有独特的GRB余辉环境：致密天体爆炸发生在星际介质（ISM）中，大质量恒星爆炸发生在爆发前的星风中。我们计算了沃尔夫-拉叶星风爆发的预期余辉，并将结果与恒定星际密度的结果进行比较。通常预计风情况下的光学余辉比恒定密度情况下下降得更急剧，但这种效应可能会被电子光谱指数的变化所掩盖，并且两种情况在冷却状态方面具有相同的演变。对无线电和光学/X 射线同时演化的观察对于区分这两种情况特别有用。 GRB 990123 的光学和 X 射线余辉衰减率不同，表明这种情况下存在恒定的密度相互作用。我们之前在 SN 1998bw/GRB 980425 中发现了风相互作用的有力证据，在此提出了 GRB 980519 的风模型。因此，我们认为存在带有大质量恒星祖星的风型伽马射线暴余辉和带有致密双星祖星的 ISM 型余辉。风型爆发很可能伴随着超新星爆发，但不是ISM型爆发。
Likely progenitors for gamma-ray bursts (GRBs) are the mergers of compact objects or the explosions of massive stars. These two cases have distinctive environments for the GRB afterglow: the compact object explosions occur in the interstellar medium (ISM) and those of massive stars occur in the preburst stellar wind. We calculate the expected afterglow for a burst in a Wolf-Rayet star wind and compare the results with those for constant, interstellar density. The optical afterglow for the wind case is generally expected to decline more steeply than in the constant density case, but this effect may be masked by variations in electron spectral index, and the two cases have the same evolution in the cooling regime. Observations of the concurrent radio and optical/X-ray evolution are especially useful for distinguishing between the two cases. The different rates of decline of the optical and X-ray afterglows of GRB 990123 suggest constant density interaction for this case. We have previously found strong evidence for wind interaction in SN 1998bw/GRB 980425 and here present a wind model for GRB 980519. We thus suggest that there are both wind-type GRB afterglows with massive star progenitors and ISM-type afterglows with compact binary star progenitors. The wind-type bursts are likely to be accompanied by a supernova, but not the ISM type.