高能天体物理前沿鸟瞰 (上)

 很容易确定天体物理诞生的日子,也很容易确定现代宇宙学诞生的日子.前者由基尔霍夫的太阳光谱观测确定,后者由爱因斯坦发表第一个宇宙解确定。但是,很难确定高能天体物理诞生的日子.也许可以作为高能天体物理诞生标志的是巴德和兹威基于1934年发表的一篇论文,题目为《超新星和宇宙线》.     

黑洞的吸积过程

 黑洞是由一个被称为视界的闭合边界所规定的时空区域.这个区域内的引力场是如此之强,以至于没有任何物质能从中逃逸,连光也不例外.也就是说,外部观测者不可能获得视界以内的任何信息.这使得黑洞成为宇宙中最神秘的天体.     

Energy Extraction from a Black Hole and Its Influence on X-Ray Spectra

The famous jet production mechanism, i.e. the Blandford and Znajek （BZ） process, has realized the idea proposed by Penrose that the rotational en- ergy of a black hole （BH） could be extracted from the ergosphere. In the BZ process, large-scale magnetic fields connecting the BH horizon and the remote as- trophysical load can extract the energy and angular momentum of the rotating BH in the form of electro- magnetic energy. The BZ mechanism was successful in explaining astrophysical jets and was widely used in high energy astrophysics. As a variation of the BZ process, the magnetic connection （MC） between the BH horizon and the accretion disk, namely, the MC process, was later discussed by researchers. Li discovered that the extractable energy of an extreme Kerr BH in the MC process can reach ～0.15Mc2, which is higher than that in the BZ process, where M is the BH mass and c is the light speed. In recent years, some astrophysical phenomena observed in BH systems, such as broad iron emission lines and high frequency quasi-periodic oscillations （QPOs）, re- veal the importance of the MC process. How- ever, we are still interested in how the extracted en- ergy is dissipated in the inner accretion disk and how it affects the accretion flow and the x-ray spectrum remains unclear.     

星系中心的巨大黑洞

 1924年,年轻的美国天文学家哈勃(ＥｄｗｉｎＨｕｂｂｌｅ,1889～1953)利用造父变星的周光关系测定出我们银河系的近邻仙女座大星云Ｍ31、Ｍ33及ＮＧＣ6822的距离,确认三者是银河系以外的星系以后,从此开始了人们研究河外星系的新纪元。第二次世界大战后期,射电天文的兴起和应用了新的测光技术以后,天文学家又相继发现了一系列有激烈活动的河外天体,如赛弗特星系(Ｓｅｙｆｅｒｔｇａｌａｘｙ)、Ｎ星系、类星体(一些观测事实表明类星体可能是遥远的Ｉ型赛弗特星系的核心)、蝎虎座ＢＬ型天体和射电星系等。