共查询到18条相似文献，搜索用时 390 毫秒
1.
最近的研究表明：短γ射线暴（γ暴）的辐射特性和长γ暴的前两秒的辐射特征相似，这引发了对以前争论的问题，即：这两类暴是否是本质上相同的暴？本文主要对和γ暴谱形和光变曲线有关的两个量的分布进行了K—S检验。分析表明：这两类暴的分布是不同的，这和广为接受的两类γ暴事件产生于不同机制的观点是一致的。 相似文献
2.
研究亮暴和暗暴的X射线余辉,发现它们的X射线和γ流量的分布基本上相同。即:从统计学的角度上讲,亮暴和暗暴没有本质不同,它们的中心机制应该是相同的,暗暴的形成应该是由环境原因引起的。 相似文献
3.
本研究了ＣＧＲＯ卫星上ＢＡＴＳＥ探测器对硬Ｘ天空监测过程中触发和记录到的１０００多个γ暴和４０００多个太阳硬Ｘ射线暴的强度和时间性质，发现它们的强度分布相似，这也许意味着硬Ｘ射线天空中两种主要的爆发现象机制相似，同时对将γ暴的强度分布作为其宇宙学起源的证据提出了疑问。 相似文献
4.
本文研究了CGRO卫星上BATSE探测器对硬X天空监测过程中触发和记录到的1 0 0 0多个γ暴和 40 0 0多个太阳硬X射线暴的强度和时间性质 ,发现它们的强度分布相似 ,这也许意味着硬X射线天空中两种主要的爆发现象机制相似 ,同时对将γ暴的强度分布作为其宇宙学起源的证据提出了疑问 .对太阳暴的持续时间分析表明 ,其强度和持续时间呈正相关 ,而γ暴是弱负相关 .太阳暴的强度和持续时间在BATSE运行过程中有长时标变化 ,最近对γ暴的研究也发现了这种现象 相似文献
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伽玛射线暴源的新分布“BATSE的观测结果 总被引：1，自引：0，他引：1
介绍了康普顿γ射线天文台上ＢＡＴＳＥ有关暴源分布观测的新发展。这一发现对８０年代以前所普遍接受的γ射线暴起源于银盘内中子星的模型提出了严重挑战，并阐明了几种以ＢＡＳＥ结果基础的暴源分布模型。 相似文献
7.
李惕碚 《中国天文和天体物理学报》1997,(3)
分析第三个ＢＡＴＳＥγ射线暴表所列γ暴数据，发现γ射线暴参量间的相关性质随时间存在系统的变化．从１９９１年４月至１９９４年９月，γ射线暴能流与暴宽间的相关系数随时间上升．短暴的能谱硬度与暴宽间的相关系数随时间显著上升，而对于长暴未发现类似的变化． 相似文献
8.
分析第三个ＢＡＴＳＥγ射线暴表所列γ暴数据，发现γ射线暴参量间的相关性质随时间存在系统的变化。从１９９１年４月至１９９４年９月，γ射线暴能流与暴宽间的相关系数随时间上升。短暴的能谱硬度与暴宽间的相关系数随时间显上升，而对于长暴未发现类似的变化。 相似文献
9.
Swift卫星的X射线望远镜观测揭示部分伽玛暴的早期余辉光变曲线有一个缓慢衰减的成分,而相当一部分却没有这样的成分.研究比较这两种暴的观测性质发现两类暴的持续时间、伽玛辐射总流量、谱指数、谱硬度比峰值能量等物理量均没有显著差异.然而有该成分的那些伽玛暴谱比较软、早期X射线余辉比较弱、伽玛射线辐射效率显著高于没有这个成分的那些暴.结果表明两类暴的前身星和中心机制一致,是否呈现这个缓慢衰减成分可能取决于外部介质. 相似文献
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《New Astronomy》2020
GRB 170817A was confirmed to be associated with GW170817, which was produced by a neutron star - neutron star merger. It indicates that at least some short gamma-ray bursts come from binary neutron star mergers. Theoretically, it is widely accepted that short gamma-ray bursts can be produced by two distinctly different mechanisms, binary neutron star mergers and neutron star - black hole mergers. These two kinds of bursts should be different observationally due to their different trigger mechanisms. Motivated by this idea, we collect a universal data set constituted of 51 short gamma-ray bursts observed by Swift/BAT, among which 14 events have extended emission component. We study the observational features of these 51 events statistically. It is found that our samples consist of two distinct groups. They clearly show a bimodal distribution when their peak photon fluxes at 15–150 keV band are plotted against the corresponding fluences. Most interestingly, all the 14 short bursts with extended emission lie in a particular region of this plot. When the fluences are plotted against the burst durations, short bursts with extended emission again tend to concentrate in the long duration segment. These features strongly indicate that short gamma-ray bursts really may come from two distinct types of progenitors. We argue that those short gamma-ray bursts with extended emission come from the coalescence of neutron stars, while the short gamma-ray bursts without extended emission come from neutron star - black hole mergers. 相似文献
12.
A. W. Hotan M. Bailes S. M. Ord 《Monthly notices of the Royal Astronomical Society》2005,362(4):1267-1272
In the present paper, we investigate the distribution of the hardness ratio (HR) for short and long gamma-ray bursts (GRBs) in different time-scales for the first two seconds. After including and subtracting the background count, we performed a Kolmogorov–Smirnov (K–S) test on the HR distributions of the two classes of GRBs in each time interval. Our analysis shows that the probabilities of the K–S test to the distributions are very small, suggesting that the two classes of bursts are unlikely to arise from the same HR distributions. The result indicates that the two kinds of bursts probably originate from different mechanisms or have different central engines. In addition, we found that the HR of short bursts within the time interval 0–0.96 s changes from hard to soft; the HR of long bursts does not. The two kinds of bursts have different characteristics in the first two seconds, which might be associated with different physical mechanisms. 相似文献
13.
Wei Wang 《Astrophysics and Space Science》2005,297(1-4):415-422
X-ray emission and absorption features are of great importance in our understanding the nature and environment of gamma-ray
bursts (GRBs). So far, iron emission lines have been detected in at least four GRB afterglows. In this paper, the observational
properties and physical constraints on materials surrounding GRB sources are reviewed, and several classes of theoretical
models are also discussed. We will specially concentrate on the Cerenkov line mechanism, in which the broad iron lines are
expected, and a small mass of Fe is required to produce the large line luminosity. In addition, our interpretation can favor
the recent jet unified model for different classes of gamma-ray bursts with a standard energy reservoir. 相似文献
14.
Simon F. Portegies Zwart † Tomonori Totani 《Monthly notices of the Royal Astronomical Society》2001,328(3):951-957
We present an internal shock model with external characteristics for explaining the complicated light curves of gamma-ray bursts. Shocks produce gamma-rays in the interaction between a precessing beam of relativistic particles and the interstellar medium. Each time the particle beam passes the same line of sight with the observer the interstellar medium is pushed outward. Subsequent interactions between the medium and the beam are delayed by the extra distance to be travelled for the particles before the shock can form. This results in a natural retardation and leads to an intrinsic asymmetry in the light curves produced for gamma-ray bursts. In addition, we account for the cooling of the electron–proton plasma in the shocked region, which gives rise to an exponential decay in the gamma-ray flux. The combination of these effects and the precessing jet of ultrarelativistic particles produces light curves that can be directly compared with observed gamma-ray burst light curves. We illustrate the model by fitting a number of observed gamma-ray bursts that are difficult to explain with only a precessing jet. We develop a genetic algorithm to fit several observed gamma-ray bursts with remarkable accuracy. We find that for different bursts the observed fluence, assuming isotropic emission, easily varies over four orders of magnitude from the energy generated intrinsically. 相似文献
15.
C. Barat G. Chambon K. Hurley M. Niel G. Vedrenne I. V. Estulin A. V. Kuznetsov V. M. Zenchenko 《Astrophysics and Space Science》1981,75(1):83-91
The three-satellite SIGNE network has observed 26 confirmed gamma-ray bursts in the period September 1978–June 1979. Burst time histories may be used to define several classes of events, with a strong resemblance between events in a given class, but different arrival directions. The spectra of two gamma-ray bursts have been found to evolve from shapes which turn over at low energy during the start of the event, to near power law spectra at the end of the event.Paper presented at the Symposium on Cosmic Gamma-Ray Bursts held at Toulouse, France, 26–29 November, 1979. 相似文献
16.
介绍了ＣｏｍｐｔｏｎＧＲＯ卫星对Ⅱ暴的最新观测结果。观测表明，γ暴源的空间分布是各向同性但不均匀的。这种分布基本上排除了γ暴起源于银盘内中子星的模型，表明γ暴要么位于展延的银晕里，要么位于宇宙学距离上。 相似文献
17.
We analyze short-duration gamma-ray bursts (T
90<2 s) recorded in the SPI-ACS experiment of the INTEGRAL observatory. We found an extended emission in the averaged light
curve of both short-duration gamma-ray bursts and unidentified short-duration events. We show that the fraction of short-duration
gamma-ray bursts among all the gamma-ray bursts recorded in the SPI-ACS experiment may be as high as 30 to 45%. We find the
fraction of short gamma-ray bursts to augment while increasing the lower energy threshold. We report evidence for the absence
of the class of very short gamma-ray bursts. 相似文献
18.
《天文和天体物理学研究(英文版)》2015,(7)
We study the electromagnetic radiation from a newborn magnetar whose magnetic tilt angle decreases rapidly. We calculate the evolution of the angular spin frequency, the perpendicular component of the surface magnetic field strength, and the energy loss rate through magnetic dipole radiation. We show that the spin-down of the magnetar experiences two stages characterized by two different timescales. The apparent magnetic field decreases with the decrease of the tilt angle. We further show that the energy loss rate of the magnetar is very different from that in the case of a fixed tilt angle. The evolution of the energy loss rate is consistent with the overall light curves of gamma-ray bursts which show a plateau structure in their afterglow stage. Our model supports the idea that some gamma-ray bursts with a plateau phase in their afterglow stage may originate from newborn millisecond magnetars. 相似文献