排序方式: 共有10条查询结果,搜索用时 31 毫秒
1
1.
2.
Soderberg AM Kulkarni SR Nakar E Berger E Cameron PB Fox DB Frail D Gal-Yam A Sari R Cenko SB Kasliwal M Chevalier RA Piran T Price PA Schmidt BP Pooley G Moon DS Penprase BE Ofek E Rau A Gehrels N Nousek JA Burrows DN Persson SE McCarthy PJ 《Nature》2006,442(7106):1014-1017
Over the past decade, long-duration gamma-ray bursts (GRBs)--including the subclass of X-ray flashes (XRFs)--have been revealed to be a rare variety of type Ibc supernova. Although all these events result from the death of massive stars, the electromagnetic luminosities of GRBs and XRFs exceed those of ordinary type Ibc supernovae by many orders of magnitude. The essential physical process that causes a dying star to produce a GRB or XRF, and not just a supernova, is still unknown. Here we report radio and X-ray observations of XRF 060218 (associated with supernova SN 2006aj), the second-nearest GRB identified until now. We show that this event is a hundred times less energetic but ten times more common than cosmological GRBs. Moreover, it is distinguished from ordinary type Ibc supernovae by the presence of 10(48) erg coupled to mildly relativistic ejecta, along with a central engine (an accretion-fed, rapidly rotating compact source) that produces X-rays for weeks after the explosion. This suggests that the production of relativistic ejecta is the key physical distinction between GRBs or XRFs and ordinary supernovae, while the nature of the central engine (black hole or magnetar) may distinguish typical bursts from low-luminosity, spherical events like XRF 060218. 相似文献
3.
Fox DB Frail DA Price PA Kulkarni SR Berger E Piran T Soderberg AM Cenko SB Cameron PB Gal-Yam A Kasliwal MM Moon DS Harrison FA Nakar E Schmidt BP Penprase B Chevalier RA Kumar P Roth K Watson D Lee BL Shectman S Phillips MM Roth M McCarthy PJ Rauch M Cowie L Peterson BA Rich J Kawai N Aoki K Kosugi G Totani T Park HS MacFadyen A Hurley KC 《Nature》2005,437(7060):845-850
The final chapter in the long-standing mystery of the gamma-ray bursts (GRBs) centres on the origin of the short-hard class of bursts, which are suspected on theoretical grounds to result from the coalescence of neutron-star or black-hole binary systems. Numerous searches for the afterglows of short-hard bursts have been made, galvanized by the revolution in our understanding of long-duration GRBs that followed the discovery in 1997 of their broadband (X-ray, optical and radio) afterglow emission. Here we present the discovery of the X-ray afterglow of a short-hard burst, GRB 050709, whose accurate position allows us to associate it unambiguously with a star-forming galaxy at redshift z = 0.160, and whose optical lightcurve definitively excludes a supernova association. Together with results from three other recent short-hard bursts, this suggests that short-hard bursts release much less energy than the long-duration GRBs. Models requiring young stellar populations, such as magnetars and collapsars, are ruled out, while coalescing degenerate binaries remain the most promising progenitor candidates. 相似文献
4.
本书的第一版是汇集1987年12月28日至1988年1月6日在耶路撒冷举行的第5届“薄膜和表面的统计力学”讲学会的所有演讲,于1989年出版。这次出版第2版更新了一些章的内容,并增加了最后三章。此书应用聚合物物理、微分几何、场论和临界现象等领域的工具来探讨几何和统计力学在一些材料中的微弱的相互作用。这些材料包括微乳状液、湿润的与生长的表面、易溶的液晶块、硫族化合物的眼镜和片状聚合物。 相似文献
5.
宇宙由什么组成?目前为止,我们还不知道。但是如果标准的引力理论成立,那么宇宙中的大部分物质是由一种无法被发现的形式存在,这些物质发出的光,当今的所有望远镜还不能观测到,这些看不见的物质就是暗物质。 相似文献
6.
Mergers of neutron-star/neutron-star binaries are strong sources of gravitational waves. They can also launch subrelativistic and mildly relativistic outflows and are often assumed to be the sources of short γ-ray bursts. An electromagnetic signature that persisted for weeks to months after the event would strengthen any future claim of a detection of gravitational waves. Here we present results of calculations showing that the interaction of mildly relativistic outflows with the surrounding medium produces radio flares with peak emission at 1.4 gigahertz that persist at detectable (submillijansky) levels for weeks, out to a redshift of 0.1. Slower subrelativistic outflows produce flares detectable for years at 150 megahertz, as well as at 1.4 gigahertz, from slightly shorter distances. The radio transient RT 19870422 (ref. 11) has the properties predicted by our model, and its most probable origin is the merger of a compact neutron-star/neutron-star binary. The lack of radio detections usually associated with short γ-ray bursts does not constrain the radio transients that we discuss here (from mildly relativistic and subrelativistic outflows) because short γ-ray burst redshifts are typically >0.1 and the appropriate timescales (longer than weeks) have not been sampled. 相似文献
7.
Gal-Yam A Fox DB Price PA Ofek EO Davis MR Leonard DC Soderberg AM Schmidt BP Lewis KM Peterson BA Kulkarni SR Berger E Cenko SB Sari R Sharon K Frail D Moon DS Brown PJ Cucchiara A Harrison F Piran T Persson SE McCarthy PJ Penprase BE Chevalier RA MacFadyen AI 《Nature》2006,444(7122):1053-1055
Over the past decade, our physical understanding of gamma-ray bursts (GRBs) has progressed rapidly, thanks to the discovery and observation of their long-lived afterglow emission. Long-duration (> 2 s) GRBs are associated with the explosive deaths of massive stars ('collapsars', ref. 1), which produce accompanying supernovae; the short-duration (< or = 2 s) GRBs have a different origin, which has been argued to be the merger of two compact objects. Here we report optical observations of GRB 060614 (duration approximately 100 s, ref. 10) that rule out the presence of an associated supernova. This would seem to require a new explosive process: either a massive collapsar that powers a GRB without any associated supernova, or a new type of 'engine', as long-lived as the collapsar but without a massive star. We also show that the properties of the host galaxy (redshift z = 0.125) distinguish it from other long-duration GRB hosts and suggest that an entirely new type of GRB progenitor may be required. 相似文献
8.
9.
Berger E Price PA Cenko SB Gal-Yam A Soderberg AM Kasliwal M Leonard DC Cameron PB Frail DA Kulkarni SR Murphy DC Krzeminski W Piran T Lee BL Roth KC Moon DS Fox DB Harrison FA Persson SE Schmidt BP Penprase BE Rich J Peterson BA Cowie LL 《Nature》2005,438(7070):988-990
Despite a rich phenomenology, gamma-ray bursts (GRBs) are divided into two classes based on their duration and spectral hardness--the long-soft and the short-hard bursts. The discovery of afterglow emission from long GRBs was a watershed event, pinpointing their origin to star-forming galaxies, and hence the death of massive stars, and indicating an energy release of about 10(51) erg. While theoretical arguments suggest that short GRBs are produced in the coalescence of binary compact objects (neutron stars or black holes), the progenitors, energetics and environments of these events remain elusive despite recent localizations. Here we report the discovery of the first radio afterglow from the short burst GRB 050724, which unambiguously associates it with an elliptical galaxy at a redshift z = 0.257. We show that the burst is powered by the same relativistic fireball mechanism as long GRBs, with the ejecta possibly collimated in jets, but that the total energy release is 10-1,000 times smaller. More importantly, the nature of the host galaxy demonstrates that short GRBs arise from an old (> 1 Gyr) stellar population, strengthening earlier suggestions and providing support for coalescing compact object binaries as the progenitors. 相似文献
10.
Racusin JL Karpov SV Sokolowski M Granot J Wu XF Pal'shin V Covino S van der Horst AJ Oates SR Schady P Smith RJ Cummings J Starling RL Piotrowski LW Zhang B Evans PA Holland ST Malek K Page MT Vetere L Margutti R Guidorzi C Kamble AP Curran PA Beardmore A Kouveliotou C Mankiewicz L Melandri A O'Brien PT Page KL Piran T Tanvir NR Wrochna G Aptekar RL Barthelmy S Bartolini C Beskin GM Bondar S Bremer M Campana S Castro-Tirado A Cucchiara A Cwiok M D'Avanzo P D'Elia V Valle MD de Ugarte Postigo A 《Nature》2008,455(7210):183-188
Long-duration gamma-ray bursts (GRBs) release copious amounts of energy across the entire electromagnetic spectrum, and so provide a window into the process of black hole formation from the collapse of massive stars. Previous early optical observations of even the most exceptional GRBs (990123 and 030329) lacked both the temporal resolution to probe the optical flash in detail and the accuracy needed to trace the transition from the prompt emission within the outflow to external shocks caused by interaction with the progenitor environment. Here we report observations of the extraordinarily bright prompt optical and gamma-ray emission of GRB 080319B that provide diagnostics within seconds of its formation, followed by broadband observations of the afterglow decay that continued for weeks. We show that the prompt emission stems from a single physical region, implying an extremely relativistic outflow that propagates within the narrow inner core of a two-component jet. 相似文献
1