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目前宇宙已知的最大黑洞 M87

eliu

joined: 2007-08-09
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新竹, 台灣
1subject: 目前宇宙已知的最大黑洞 M87Promote 0 Bookmark 02011-01-20quote  

由德州大學 Austin 分校 Karl Gebhardt 領導的天文學家,測量了宇宙已知的最大黑洞,有 66億個太陽的質量,位於巨大的橢圓星系 M87。由於M87的黑洞很大,未來有可能可以真的看到黑洞,而不是用間接的方法。

M87中心的質量的測量的方法是測量中心的恆星環繞黑洞的速度。由於目前沒有直接的證據證明黑洞的存在,未來的天文學或許可以看見事件水平線(event horizon),過了此事件水平線,沒有什麼東西可以逃脫(光線?)。M87的事件水平線大約是冥王星軌道的3倍,可以吞下整個太陽系,還好 M87 在5千萬光年的遠處。未來的天文學家或許可以用全世界連線的望遠鏡尋找M87的事件水平線。

edited: 1
ychao
joined: 2007-10-25
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2subject: Promote 0 Bookmark 02011-01-21quote  

維基百科: 黑洞質量是如此之大,它產生的引力場是如此之強,以至於任何物質和輻射都無法逃逸,就連光也逃逸不出來,故名為黑洞。在黑洞的周圍,是一個無法偵測的事象地平面,標誌著無法返回的臨界點。

這裡指的應該是古典的黑洞,而且沒有角動量。基本上天文觀測應該是無法直接看到的。目前有另一派說法,旋轉的黑洞會在兩極射出噴流(jet),來維持角動量守恆。所以人們可能可以從觀測到噴流,X光與可見光波段的差異,還有附近天體運動的速度,來「推測」黑洞的存在。

至於LHC可能可以觀測到的微黑洞,在CMS經過一年的實驗數據分析,目前還沒有看到證據...

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eliu

joined: 2007-08-09
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3subject: Promote 0 Bookmark 02011-01-22quote  

有觀察到類似 jet 的情形

據說是磁場造成的噴出,就像地球的地磁可以把太陽風的帶電粒子推到南北極,形成極光的原理?

jet 是在 event horizon 裏面 or 外面被噴出?理論上是星系的物質被黑洞的重力吸引加速分解後,一部份進入黑洞,一部份在 event horizon 外被磁場噴出?

black hole jet 黑洞噴射

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ychao
joined: 2007-10-25
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4subject: Promote 0 Bookmark 02011-01-22quote  

wikipedia en:

Due to conservation of angular momentum, gas falling into the gravitational well created by a massive object will typically form a disc-like structure around the object. Friction within the disc causes angular momentum to be transported outward allowing matter to fall further inward releasing potential energy and increasing the temperature of the gas. In the case of compact objects such as white dwarfs, neutron stars, and black holes, the gas in the inner regions becomes so hot that it will emit vast amounts of radiation (mainly X-rays), which may be detected by telescopes.

eliu

joined: 2007-08-09
posted: 11419
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新竹, 台灣
5subject: Promote 0 Bookmark 02011-01-23quote  

你說的是 X ray,我說的是粒子。我的 black hole jet 資料來源是

These data support the suggestion that twisted magnetic field lines are creating the jet plumes. Material in the center of the galaxy, such as nearby stars and gas, gets pulled in by the black hole's overwhelming gravity and forms a disk orbiting around the core (the material's inertia keeps it spiraling in a disk rather than falling straight into the black hole). The distorted magnetic field lines seem to pull charged particles off the disk and cause them to gush outward at nearly the speed of light.

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ychao
joined: 2007-10-25
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6subject: Promote 0 Bookmark 02011-01-28quote  

我想說的是,因為角動量守恆才有旋轉的天體(黑洞),有旋轉的帶電粒子才會有形成磁場。至於噴出來的東西 could be anything,只是人能觀測到的也只有會發光的。(看不到的,就叫做 dark matter / dark energy)

不過別忘了,光也是粒子喔!尤其是高能量的光子-- X-ray。

關於這個兩極噴流的現象,另有一說:某些中子星跟黑洞,其實分不太出來的。

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