由对FRⅡ射电星系的X射线观测试预言射电噪活动星系核的X射线喷流     

白金明 《天文研究与技术》2003,(1):19-25

在早期的文章中,基于耀变体(Blazar)的知识,我们预言了在射电噪活动星系核(AGN)中心10 kpc范围内X射线喷流的存在.钱得拉(Chandra)卫星最近对低功率射电星系的X射线观测与我们的预言相一致.在本文中我们研究了kpc尺度喷流中的电子加速,并建议通过对强的FR Ⅱ射电星系中所预言的X射线喷流的钱得拉卫星的X射线的观测,来研究红的耀变体中的康普顿冷却以及在内部致密喷流和大尺度延伸喷流间环境的不同.以上的研究可以进一步检验我们的关于射电噪活动星系核中kpc尺度X射线喷流的模型.  相似文献   

Gamma-ray bursts: optical afterglows in the deep Newtonian phase     

Y. F. Huang  K. S. Cheng 《Monthly notices of the Royal Astronomical Society》2003,341(1):263-269

Gamma-ray burst remnants become trans-relativistic typically in days to tens of days, and they enter the deep Newtonian phase in tens of days to months, during which the majority of shock-accelerated electrons will no longer be highly relativistic. However, a small portion of electrons are still accelerated to ultra-relativistic speeds and are capable of emitting synchrotron radiation. The distribution function for electrons is re-derived here so that synchrotron emission from these relativistic electrons can be calculated. Based on the revised model, optical afterglows from both isotropic fireballs and highly collimated jets are studied numerically, and compared to analytical results. In the beamed cases, it is found that, in addition to the steepening due to the edge effect and the lateral expansion effect, the light curves are universally characterized by a flattening during the deep Newtonian phase.  相似文献   

The young cluster in the CB34 globule: the clumps and the outflows     

C. Codella  F. Scappini 《Monthly notices of the Royal Astronomical Society》2003,344(4):1257-1263

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Double–double radio galaxies: remnants of merged supermassive binary black holes     

F. K. Liu  Xue-Bing Wu  S. L. Cao 《Monthly notices of the Royal Astronomical Society》2003,340(2):411-416

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Gamma—Ray Bursts：Afterglows and Central Engines   总被引：5，自引：0，他引：5  

K.S.Cheng T.Lu 《中国天文和天体物理学报》2001,1(1):1-20

Gamma-ray bursts (GRBs) are the most intense transient gamma-ray events in the sky; this, together with the strong evidence (the isotropic and inhomogeneous distribution of GRBs detected by BASTE) that they are located at cosmological distances, makes them the most energetic events ever known. For example, the observed radiation energies of some GRBs are equivalent to the total convertion into radiation of the mass energy of more than one solar mass. This is thousand times stronger than the energy of a supernova explosion. Some unconventional energy mechanism and extremely high conversion efficiency for these mysterious events are required. The discovery of host galaxies and association with supernovae at cosmoligical distances by the recently launched satellite of BeppoSAX and ground based radio and optical telescopes in GRB afterglow provides further support to the cosmological origin of GRBs and put strong constraints on their central engine. It is the aim of this article to review the possible central engines, energy mechanisms, dynamical and spectral evolution of GRBs, especially focusing on the afterglows in multi-wavebands.  相似文献   

Relativistic models and the jet velocity field in the radio galaxy 3C 31   总被引：1，自引：0，他引：1  

R. A. Laing  A. H. Bridle 《Monthly notices of the Royal Astronomical Society》2002,336(1):328-352

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Emission line widths of an asymmetric bowshock inside a cloud of dust     

W. J. Henney 《Astrophysics and Space Science》1995,224(1-2):481-482

A model is presented that explains the anomalous emission line widths in the Herbig-Haro object HH 1 in terms of emission from a lop-sided bowshock and scattering by surrounding dust.  相似文献   

Gaseous Jets in Comet Hale-Bopp (1995 O1)     

Lederer  Susan M.  Campins  Humberto  Osip  David J.  Schleicher  David G. 《Earth, Moon, and Planets》1997,78(1-3):131-136

We report the identification of gas jets in comet Hale-Bopp in OH, NH, CN, C₂ and C₃. This is the first time OH and NH jets without an obvious optical dust jet counterpart have been identified in narrowband comet images. We also confirm the existence of CN jets as reported by Larson et al. (1997) and Mueller et al. (1998). Jet features can be seen in the March and April 1997 datasets, approximately a month before and after perihelion. Our results contribute to the understanding of both the chemical properties of the comet as well as the physical mechanisms necessary to produce these features. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Search for VHE gamma rays from SS433/W50 with the CANGAROO-II telescope     

《Astroparticle Physics》2009,32(2):112-119

SS433, located at the center of the supernova remnant W50, is a close proximity binary system consisting of a compact star and a normal star. Jets of material are directed outwards from the vicinity of the compact star symmetrically to the east and west. Non-thermal hard X-ray emission is detected from lobes lying on both sides. Shock accelerated electrons are expected to generate VHE gamma rays through the inverse-Compton process in the lobes. Observations of the western X-ray lobe region of SS433/W50 system have been performed to detect VHE gamma rays using the 10 m CANGAROO-II telescope in August and September, 2001, and July and September, 2002. The total observation times are 85.2 h for ON source, and 80.8 h for OFF source data. No significant excess of VHE gamma rays has been found at three regions of the western X-ray lobe of SS433/W50 system. We have derived 99% confidence level upper limits to the fluxes of gamma rays and have set constraints on the strengths of the magnetic fields assuming the synchrotron/inverse-Compton model for the wide energy range of photon spectrum from radio to TeV. The derived lower limits are G for the center of the brightest X-ray emission region and G for the far end from SS433 in the western X-ray lobe. In addition, we suggest that the spot-like X-ray emission may provide a major contribution to the hardest X-ray spectrum in the lobe.  相似文献   

High-mass star forming regions: An ALMA view     

R. Cesaroni 《Astrophysics and Space Science》2008,313(1-3):23-28

The advent of ALMA is bound to improve our knowledge of OB star formation dramatically. Here, we present an overview of this topic outlining how high angular resolution and sensitivity may contribute to shed light on the structure of high-mass star forming regions and hence on the process itself of massive star formation. The impact of this new generation instrument will range from establishing the mass function of pre-stellar cores inside IR-dark clouds, to investigating the kinematics of the gas from which OB stars are built up, to assessing or ruling out the existence of circumstellar accretion disks in these objects.  相似文献