首张黑洞照片诞生——谈黑洞的前生今世

1905年和1916年爱因斯坦分别提出了狭义相对论和广义相对论,这不仅改变了人类对宇宙的认识而且还深深地影响了我们的日常生活,其中广义相对论一个著名的预言就是黑洞。目前,天文学家发现几乎每个星系中心都存在一个百万到百亿个太阳质量的巨型黑洞,而且每个星系中可能还存在上亿个恒星级黑洞。中等质量黑洞是否存在目前还不确定。黑洞存在的间接证据已经有很多,但人类更渴望直接看到黑洞的面目。黑洞虽然本身并不发光,但可以将吸积物质的引力能通过吸积盘变成辐射,从而被我们看到。北京时间2019年4月10日21时,事件视界望远镜项目在比利时布鲁塞尔、智利圣地亚哥、中国上海和台北、日本东京和美国华盛顿全球六大城市同步举行新闻发布会,公布人类获得的首张黑洞照片。这张照片摄自梅西耶87(M87)星系中心的黑洞,重约60亿太阳质量,距离地球5 600万光年,由全世界横跨几大洲近10台毫米波望远镜(或阵列)进行联网观测,项目团队包括来自中国科学院上海天文台等单位的10余名中国成员。可以说"人类首张黑洞照片"是继2016年发现引力波之后人们寻找到的爱因斯坦广义相对论最后一块缺失的拼图。本文还对未来中国在黑洞研究方面的重大项目做了简单介绍和展望。

The first black hole image: An introduction to black hole

Einstein discovered the special relativity and general relativity at 1905 and 1915 respectively. The most fundamental prediction of the general relativity is the existence of black hole. Now, we believe that there is a supermassive black hole and possibly billion of stellar-mass black holes in each galaxy. It is still unclear whether the intermediate mass of black hole exist or not. There are many indirect evidences for the existence of black holes at different scales by measuring the effects of an object surrounding the blackholes. The international collaboration group for the event horizon telescope try to achieve the high resolution that can resolve thehorizon of the two nearby supermassive black holes (in Milky Way and M87 at the center of Virgo cluster) by adopting a techniqueknown as very-long-baseline interferometry. For about 10 days in April of 2017, the scientists observed the Sgr A* and M87 by networking eight telescopes around the globe. In April 10 of 2019, the group of the event horizon telescope announced the first photo of the black hole at the center of M87, which is the most direct evidence for the existence of the black hole. This results further support the theory of the general relativity. In last part, I also simply review the possible future Chinese projects that will focus on the black hole physics.