On the detection of high‐frequency oscillations in short gamma‐ray bursts     

B.E. Zhilyaev  D. Dubinovska 《Astronomische Nachrichten》2009,330(4):404-410

In this work we present the results of an investigation aimed at a search for an oscillatory phenomenon during short gamma‐ray bursts. The wavelet technique, used for this analysis, is applied to the data from the BATSE 3B catalogue. We have detected oscillations, which periods are found to be in the milliseconds range and their amplitudes up to dozens of percents. A possible scenario for such a phenomenon is the coalescence of stellar‐mass black holes and neutron stars. During the coalescence process the matter orbiting the black hole produces rapid, periodic phenomena. Such system will also emit gravitational waves which cause the orbital radius to decrease and leads to the emission of a chirp of radiation. Estimates lead to a timescale of milliseconds for the coalescence process and oscillation frequencies of hundreds of Hz. The gamma‐ray bursts considered in this paper, show both frequencies and survival times of oscillations close to the mentioned values. A chirp phenomenon is also present. We therefore argue in favor of the black hole – neutron star coalescence as a scenario for the production of short gamma‐ray bursts (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

利用卫星微波观测亮温与云辐射模拟亮温的台风定位分析北大核心          下载免费PDF全文

毕明明  邹晓蕾 《气象科学》2022,42(4):457-466

极轨气象卫星S-NPP、MetOp-A和FY-3B上搭载的微波湿度计观测资料可以反映出台风周围水汽和云雨结构。本文使用权重函数峰值在800 hPa附近的微波湿度计通道观测资料和ERA5再分析资料全天空模拟亮温,以飓风Sandy和Isaac为例,对用方位谱台风中心位置定位方法得到的观测和模拟中心位置进行了比较。利用下午星S-NPP搭载的先进技术微波探测仪(Advanced Technology Microwave Sounder,ATMS)和上午星MetOp-A搭载的微波湿度计(Microwave Humidity Sounder,MHS)观测亮温得到的飓风Sandy(Isaac)中心位置与最佳路径平均相差35.8 km(32.9 km),但用ERA5全天空模拟亮温得到的飓风Sandy(Isaac)中心位置与最佳路径平均相差73.3 km(82.1 km)。若按照热带风暴和台风等级来划分,ATMS和MHS观测和模拟亮温得到的台风中心位置与最佳路径的平均距离对热带风暴分别是36.5 km和105.9 km,对台风分别是25.8 km和56.4 km。若用FY-3B搭载的微波湿度计(以MWHS表示)替换ATMS,所得结果类似。ERA5作为全球大气再分析资料的典型代表,用方位谱台风中心位置定位方法得到的台风中心位置误差较大的原因是ERA5再分析资料全天空模拟亮温在台风中的分布结构与观测亮温相差较大,而模拟亮温与冰水路径分布结构极为相似。研究对台风数值预报中的全天空模拟亮温资料同化具有一定的参考意义。  相似文献   

Γ分布函数与S（t）曲线通用算法的研究   总被引：1，自引：1，他引：1  

李世才 《水文》1995,(1)

瞬时单位线中Ｓ（ｔ）曲线的计算方法，是工程水文计算研究的难点之一，目前在实际工作中应用的方法都有一定的缺陷。为此对其数学表达式进行了变换，把它归纳为求解Γ分布函数的值，并给出了其通用算法的解析表达式和截断误差估计式。通过实践证明，通用算法的数学模型具有实现算法简便、求解灵活、计算精度高、节省存贮空间、通用性强、收敛速度快、数值稳定性好等优点。  相似文献   

On the correlation between the solar gamma–ray line emission,radio bursts and proton fluxes in the interplanetary space     

I. M. Chertok 《Astronomische Nachrichten》1990,311(6):379-381

It is shown that the correlation takes place between the 4–7 MeV gamma–ray line flare fluence F_4–7 and the intensity of the > 10 MeV proton flux in the interplanetary space as well as between F_4–7 and the peak flux density of microwave bursts. Besides, the energy spectral index of protons displays the definite dependence from parameters of the radio burst frequency spectrum. These testify that: a) there is a close physical association between the acceleration of electrons and protons in flares; b) protons, giving gamma–ray lines, and ones, registered in the interplanetary space, belong to the same population.  相似文献