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1.
Nir J. Shaviv 《Astrophysics and Space Science》1995,231(1-2):445-448
The temporal behavior of GRBs is quantified using a power spectrum analysis. The power spectrum of great variety of GRBs is well represented by the simple
–2 behavior. We then study a cosmological GRB model in which relativistic flows interact with dense radiation fields. This mechanism in the densest stellar regions known to exist, surprisingly yields the correct temporal behavior. Other characteristics are also reproduced, including the duration bimodality and the hardness-duration distribution. 相似文献
2.
伴随着引力波事件GW170817的短暴GRB (Gamma-Ray Burst) 170817A首次提供了双中子星并合与短暴相联系的直接证据.但是短暴GRB 170817A具有非常弱的光度,意味着观测的视线方向可能偏离喷流轴方向.根据短暴静止系的峰值能量E_(p,i)和各向同性光度L_(iso)。之间的关系以及洛伦兹因子Γ和L_(iso)。之间的关系估算了短暴GRB 170817A以及长短暴GRB 060614观测角与喷流边缘的夹角θ'_(obs)和洛伦兹因子Γ,结果表明GRB 170817A的Γ=45±27,θ'_(obs)=2.2±0.5°,而GRB 060614的Γ=214±93,θ'_(obs)=0.5±0.1°.这个结果相当于GRB 170817A的正轴各向同性光度L_(iso,on)=(2.1±0.7)×10~(49) erg·s~(-1),比典型的短暴少2-3个数量级.GRB 060614的L_(iso,on)=(5.12±1.91)×10~(51) erg·s~(-1)与典型短暴相当.这意味着GRB 060614可能属于短暴类型,而GRB 170817A可能本质上就是一个弱暴. 相似文献
3.
"嫦娥"一号、二号绕月飞行经历地球磁尾边界层区域时,分别在2007年11月26日—2008年2月5日和2010年10月3日—2011年2月28日,发现了15次月球轨道0.1~2 MeV电子急剧增加(Bursts of 0.1~2 MeV Energetic Electrons,BEE),卫星周围等离子体离子加速的现象.统计研究表明,这类现象发生在稳定太阳风和弱行星际磁场条件下,且无显著空间环境扰动事件发生时,离子的加速滞后于高能电子爆发,离子能量的变化与高能电子通量的时间演化正相关,地球磁鞘内侧或边界层过渡区域是该类现象的高发区,离子能量增加时卫星表面电位大幅下降可达负几千伏.为了研究高能电子爆发与绕月卫星表面电位变化的关系及其对月球表面电位的影响,本文用电流平衡法建立绕月卫星和月球表面充电模型,并假设能量电子(2eV~2 MeV)满足幂律谱的分布,模拟急剧增加的能量电子对卫星和月球表面电位的影响.模拟结果表明,能量电子急剧增加使得绕月卫星和月球表面电位大幅下降;能量电子总流量1011 cm-2时,绕月卫星和月球表面充电电位可达负上千伏;月球充电到大的负电位的时间仅为卫星充电时间的1/10.鉴于高能电子急剧增加事件的高发生率(~125次/年),能量电子急剧增加使得绕月卫星表面电位大幅下降的发生率应大于实测等离子体离子加速现象的发生率(~25次/年). 相似文献
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5.
J -P. Dezalay C. Barat R. Talon O. Terekhov R. Sunyaev A. Kuznetsov 《Astrophysics and Space Science》1995,231(1-2):115-118
Statistical studies of Gamma-Ray Burst (GRB) properties have recently led to the discovery of a subclass within the population of classical events (Dezalayet al. 1992, Kouveliotouet al. 1993). Bursts belonging to this subclass are characterized by short durations, typically less than 2 seconds, and harder spectra on average. Using the PHEBUS GRB data set, we analyse the distributions of peak intensity, hardness ratio, and duration of the two subclasses. We also compare the sum spectra obtained with the brightest events to determine the ratio of total energies observed for each population. 相似文献
6.
Roland Vanderspek Alia Atlas Tye M. Brady Geoffrey B. Crew John P. Doty Steven E. Kissel George R. Ricker Peter C. Tappan Francois Martel M. Tim Jones 《Astrophysics and Space Science》1995,231(1-2):479-482
The High Energy Transient Experiment (HETE), scheduled for launch this year, is a small satellite dedicated to multiwavelength observations of -ray and X-ray bursts. The HETE spacecraft will be equipped with gamma-ray detectors, X-ray detectors with a coded mask, and ultraviolet-sensitive CCD cameras. The UV cameras on HETE are wide-field imagers which will a) provide UV images of the regions in which -ray or X-ray bursts are detected, before, duringand after the burst, b) detect UV transients, whether associated with a high-energy transient or not, c) monitor the brightnesses of field stars for variability over a wide range of timescales, and d) serve as star trackers for HETE. In this poster, we describe the HETE UV instrumentation, control software, and data products. 相似文献
7.
The power required to eject relativistic plasma clouds in the hard X-ray transient GRS 1915+105 is at least 100 times the luminosity of the soft-ray bursts (SGRs) that were observed by BATSE from the same region of the sky in the year 1992. We show that there are spatial, time, and spectral coincidences between GRS 1915+105 and the SGRs observed by BATSE which suggest that they are one and the same source. However, the position of the SGRs is rather uncertain and until better positions are obtained, the question on the association of GRS 1915+105 with the SGRs must remain open. 相似文献
8.
We have used the data from the COBE satellite to search for delayed microwave emission (31 - 90 GHz) from Gamma Ray Bursts (GRBs). The large 7° beam of COBE is well matched to the large positional uncertainties in the GRB locations, although it also means that fluxes from (point source) GRB objects will be diluted. In view of this we are doing a statistical search of the GRBs which occurred during the currently released COBE DMR data (years 1990 and 1991), which overlap 200 GRBs recorded by GRO. Here we concentrate on just the top 10 GRBs (in peak counts/second). We obtain the limits on the emission by comparing the COBE fluxes before and after the GRB at the GRB location. Since it is thought that the microwave emission should lag the GRB event, we have searched the GRB position for emission in the few months following the GRB occurrence. 相似文献
9.
J -L. Atteia M. Niel M. Cassignol F. Cotin J. Couteret M. Ehanno J. Evrard D. Lagrange A. Lamy J. Mainguene J -F. Olive G. Rouaix P. Souleille G. Vedrenne 《Astrophysics and Space Science》1995,231(1-2):471-474
The FREnch GAmma-ray TElescope (FREGATE) on board HETE, is aimed to provide accurate spectral information on-ray bursts at low energies. Four cleaved NaI crystals provide a good sensitivity between 5 keV and 400 keV. In this paper we describe the main characteristics of this instrument: its geometry, energy resolution, and sensitivity, as well as the modes of operation and the data recorded. 相似文献
10.
The GRB monitor (GRBM) on board the Indian SROSS C-2 satellite has detected 53 classical gamma ray bursts since its launch
in May, 1994 till its re-entry in July, 2001. For a subset of 26 events, locations were obtained from simultaneous observations
by other gammaray detectors in space. The sky distribution of these 26 SROSS C-2 bursts is consistent with isotropy. The distribution
of event durations shows evidence for bimodality. There is an evidence for a moderate hardness ratio-intensity (HIC) correlation
in the data. The SROSS C-2 GRBM has also detected three episodes of emission from the SGR 1627-41. 相似文献