Analysis of the spatial distribution of gamma-ray bursts in their host galaxies     

S. I. Blinnikov  K. A. Postnov  D. I. Kosenko  O. S. Bartunov 《Astronomy Letters》2005,31(6):365-374

We compare the radial distributions of known localized gamma-ray bursts (GRBs) relative to the centers of their host galaxies with the distributions of known objects in nearby galaxies (supernovae of various types, X-ray binaries), the hypothetical dark-matter profiles, and the distribution of luminous matter in galaxies in the model of an exponential disk. By comparing the moments of empirical distributions, we show that the radial distribution of GRBs in galaxies differs significantly from that of other sources. We suggest a new statistical method for comparing empirical samples that is based on estimating the number of objects within a given radius. The exponential disk profile was found to be in best agreement with the radial distribution of GRBs. The distribution of GRBs relative to the centers of their host galaxies also agrees with the dark matter profile at certain model parameters.  相似文献   

The universal luminosity function of binary X-ray sources in galaxies     

K. A. Postnov 《Astronomy Letters》2003,29(6):372-373

The empirically found universal power-law form of the X-ray luminosity function for a population of high-mass X-ray binaries in galaxies can be explained by the fundamental mass-luminosity and mass-radius relations for massive stars.  相似文献   

Search for short cosmic gamma-ray bursts using data from the APEX and LILAS experiments onboard the Phobos-2 interplanetary spacecraft     

A. S. Kozyrev  I. G. Mitrofanov  A. B. Sanin  C. Barat 《Astronomy Letters》2004,30(7):435-443

A statistical analysis of the spectral and temporal parameters for 546 triggering events on the APEX gamma-ray detector onboard the Phobos-2 spacecraft has revealed a group of 28 events that are probably short cosmic gamma-ray bursts (GRBs). The distribution of the full group of 74 events of the APEX experiment in duration parameter is bimodal in shape, which is in good agreement with the bimodal shape of the BATSE GRB distribution. A search for the detected group of short events using data from the LILAS X-ray and soft gamma-ray detector onboard the same spacecraft has yielded no positive result. A comparison of the APEX and LILAS data has led us to conclude that the short GRBs have a significantly reduced soft gamma-ray flux at energies <100 keV relative to the power law dN/dE=CE^?α with the average index α=2.62.  相似文献   

Spatial correlation of unidentified gamma-ray sources with flaring and Wolf-Rayet stars     

A. M. Galper  B. I. Luchkov 《Astronomy Letters》2004,30(6):390-392

The spatial positions of unidentified gamma-ray sources ( E>100 MeV) were analyzed. This analysis shows that gamma-ray sources with fluxes >5×10^?7 cm^?2 s^?1 correlate with Wolf-Rayet stars, while gamma-ray sources with fluxes <5×10^?7 cm^?2 s^?1 may be associated with flaring stars.  相似文献   

Observations of radio emission from the cosmic gamma-ray burst GRB 030329     

A. M. Finkelstein  A. V. Ipatov  Yu. N. Gnedin  D. V. Ivanov  M. A. Kharinov  I. A. Rakhimov 《Astronomy Letters》2004,30(6):368-375

We present the radio observations of the afterglow from the intense cosmic gamma-ray burst GRB 030329 performed with the radio telescopes of the Institute of Applied Astronomy, Russian Academy of Sciences, at the Svetloe (λ=3.5 cm) and Zelenchuk (λ=6 cm) Observatories. The difference between the fluxes measured in two different polarization modes suggests the existence of a circular polarization in the radio afterglow from GRB 030329. However, since the measurement errors of the fluxes with different circular polarizations are large, we cannot draw a firm conclusion about its detection; we can only set an upper limit on its value. An analysis of the possible generation mechanisms for the circular polarization of the relativistic jet suggests that there is a helical magnetic field in the jet. The existence of significant flux densities at various wavelengths during a long (≥10 days) period leads us to conclude that the hydrodynamic evolution of the relativistic bow shock takes place in the stellar wind, not in the interstellar medium. We have estimated the total GRB energy (E=10⁵¹ erg) (under the assumption of isotropic radiation) and the plasma density of the stellar wind from the presupernova (n=3 cm^?3). The magnetic-field strength in the relativistic jet can be estimated as B≈100 G.  相似文献   

Gamma-ray bursts and their links with supernovae and cosmology     

Peter Meszairos  Neil Gehrels 《天体物理学报》2012,(8):1139-1161

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固定铝log(Q/K)图解在温泉中的应用     

张展适  孙占学  李满根  王素娟 《地球科学》2004,29(3):352-356

为探讨常规和固定铝log(Q/K)图解法对温泉系统是否有效 ,采用WATCH程序 ,对江西 3个温度较高的温泉 ,即庐山温泉、汤湖温泉和横泾温泉 ,进行了探测性的研究 .采用常规log(Q/K)图解法计算时 ,由于参加计算的 4个水样的铝含量均未检出 ,计算结果显示只有不含铝的矿物玉髓和方解石相交于温度 1 0 0℃附近 ,热储总体上没有达到平衡 .在采用了固定铝log(Q/K)图解法并同时考虑冷水的稀释作用计算后 ,中低温地热系统中常见的蚀变矿物如浊沸石、纤蛇纹石、萤石和玉髓均显示了较好的收敛性 ,收敛的温度大致在 1 0 0～ 1 4 0℃ .并且上述矿物组合可见于某些温泉的深部钻孔中 ,计算结果与实际地质情况相吻合 .结果表明固定铝log(Q/K)图解法可以恢复温泉系统的热平衡状态  相似文献   

Swift时代伽马暴的观测及研究进展   总被引：1，自引：0，他引：1  

董云明  陆埮 《天文学进展》2008,26(1):41-61

Swift卫星从2004年11月20日升空开始运转到现在已有2年多时间.到目前为止,它-共观测到了200多个伽马暴及其余辉现象.由于Swift观测到了早期X射线余辉、短暴余辉和高红移伽马暴等新的重要现象,伽马暴研究进入了新的时代.该文首先对伽马暴的研究历史做简短回顾,然后简要介绍伽马暴的物理图像和Swift卫星的构成及特点,最后全面评述Swift的观测成就及由此引起的理论挑战.  相似文献   

New active galactic nuclei among the INTEGRAL and SWIFT X-ray sources     

R. A. Burenin  A. V. Mescheryakov  M. G. Revnivtsev  S. Yu. Sazonov  I. F. Bikmaev  M. N. Pavlinsky  R. A. Sunyaev 《Astronomy Letters》2008,34(6):367-374

We present the results of our optical identifications of a set of X-ray sources from the INTEGRAL and SWIFT all-sky surveys. The optical data have been obtained with the 1.5-m Russian-Turkish Telescope (RTT-150). Nine X-ray sources have been identified with active galactic nuclei (AGNs). Two of them are located in the nearby spiral galaxies MCG-01-05-047 and NGC 973 seen almost edge-on. One source, IGR J16562-3301, is probably a BL Lac object (blazar). The remaining AGNs are observed as the starlike nuclei of spiral galaxies whose spectra exhibit broad emission lines. The relation between the hard X-ray (17–60 keV) luminosity and the [O III] 5007 line luminosity, log L _x/L _{[O III]} ≈ 2.1, holds good for most of the AGNs detected in hard X rays. However, the luminosities of some AGNs deviate from this relation. The fraction of such objects can reach ～20%. In particular, the [O III] line flux is lower for two nearby edge-on spiral galaxies. This can be explained by the effect of absorption in the galactic disks.  相似文献   

Optical identifications of five INTEGRAL hard X-ray sources in the Galactic plane     

I. F. Bikmaev  R. A. Burenin  M. G. Revnivtsev  S. Yu. Sazonov  R. A. Sunyaev  M. N. Pavlinsky  N. A. Sakhibullin 《Astronomy Letters》2008,34(10):653-663

The results of optical identifications of five hard X-ray sources in the Galactic plane from the INTEGRAL all-sky survey are presented. The X-ray data on one source (IGR J20216+4359) are published for the first time. The optical observations were performed with the 1.5-m RTT-150 telescope (Turkish National Observatory, Antalya, Turkey) and the 6-m BTA telescope (Special Astrophysical Observatory, Nizhny Arkhyz, Russia). A blazar, three Seyfert galaxies, and a high-mass X-ray binary are among the identified sources.  相似文献