【摘要】：很多伽瑪射線暴應當是產生于極端相對論性的噴流.關于噴流,絕大多數(shù)的討論都是圍繞錐狀噴流展開.然而有觀測發(fā)現(xiàn),一些天體中的噴流在很長距離上始終保持著幾乎不變的截面積,即表現(xiàn)為柱狀噴流.研究致密介質環(huán)境中有側向膨脹的柱狀噴流的余輝,描述其動力學演化和輻射過程,分別得到解析解和數(shù)值解,并對兩者進行了對比.研究的暴周星際介質是光學厚的,在初始的主暴階段,噴流輻射出高度準直的高能射線,升華了暴周介質,形成一個在光學波段光學薄的柱狀通道.余輝階段,由于噴流是有側向膨脹的,觀測者只能收集到視覺面積占比例越來越小的光學輻射,理論上可得到衰減極為快速的光變曲線,流量隨時間的衰減約為S_ναt~(-p-1)(p為電子冪律分布的譜指數(shù)).如此迅速的衰減使得光學余輝將難以被觀測到,提供了一種對暗伽瑪射線暴的解釋.
[Abstract]:Many gamma-ray bursts should be caused by extremely relativistic jets. Most of the discussions on jet flow revolve around conical jets. However, some observations show that the jet flow in some celestial bodies remains almost unchanged at a long distance, that is, the jet is a columnar jet. The afterglow of a cylindrical jet with lateral expansion in a dense medium is studied, its dynamic evolution and radiation process are described, and the analytical and numerical solutions are obtained, respectively, and compared with each other. The studied interstellar medium is optically thick. In the initial main burst phase, the jet radiates highly collimated high-energy rays, sublimates the burst circumference medium, and forms a cylindrical channel with optical thin in the optical band. In the afterglow stage, due to the lateral expansion of the jet, the observer can only collect the optical radiation which accounts for a smaller and smaller proportion of the visual area. The decay of flow rate with time is about S _ v 偽 t ~ (-p ~ (-1) (p is the spectral exponent of the distribution of electron power law). Such rapid decay makes it difficult to observe optical afterglow, providing an explanation for dark gamma ray bursts.
【作者單位】： 南京大學天文與空間科學學院;
【基金】：國家自然科學基金項目(11033002) 973計劃(2009CB824800)資助
【分類號】：P172.3

【參考文獻】

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1 黃永鋒,譚長宜,戴子高,陸W，

本文編號：2394340