黑洞和磁场的一些翻译文章

本文缘起于我在论坛上的一个发问，本来只是想不通黑洞明明引力连光都跑不出来，为何还有磁场作用？因为显然黑洞周围的喷流是磁场加速效应的体现。现在我个人观点是应该理解为磁场是吸积盘本身的，详细的数理论证大大超过我的能力，我做不了（否则就该发表论文混点名号了吧，虽然我是有职称的）。不过现在貌似学术界观点并不统一，我这里发的2篇文章都是来自http://chandra.harvard.edu/ 的，当然这些文章本身应该是科普类的，不是学术论文（论文在网上很难免费下载到的，大量的公式也头痛得很）。

原先的问题链接
天文知识 » 关于黑洞的一个疑问

第一篇来源、图片都是同一的

http://chandra.harvard.edu/photo/2006/j1655/

GRO J1655-40:
NASA's Chandra Answers Black Hole Paradox

                               
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Credit: Illustration: NASA/CXC/M.Weiss; X-ray Spectrum: NASA/CXC/U.Michigan/J.Miller et al.

The X-ray spectrum (see inset) of a binary star system consisting of a black hole and a normal star indicates that turbulent winds of multimillion degree gas are swirling around the black hole. As the illustration shows, much of the hot gas is spiraling inward toward the black hole, but about 30% is blowing away.
The temperature and intensity of the winds imply that powerful magnetic fields must be present. These magnetic fields, likely carried by the gas flowing from the companion star, create magnetic turbulence that generates friction in the gaseous disk and drive winds from the disk that carry momentum outward as the gas falls inward. Magnetic friction also heats the gas in the inner part of the disk to X-ray emitting temperatures.
The analysis of the disk wind of GRO J1655-40, or J1655 for short, confirmed what astronomers had long suspected, namely that magnetic friction is central to understanding how black holes accrete matter rapidly. Without a process to take away some of the angular momentum of the gas, it could remain in orbit around a black hole for a very long time.
J1655 is a binary system that harbors a black hole with a mass seven times that of the sun, which is pulling matter from a normal star about twice as massive as the sun. The Chandra observation revealed a bright X-ray source whose spectrum showed dips produced by absorption from a wide variety of atoms ranging from oxygen to nickel. A detailed study of these absorption features shows that the atoms are highly ionized and are moving away from the black hole in a high-speed wind.
Understanding the importance of magnetic forces in the disk of gas around J1655 could have far-reaching implications, from the supermassive black holes associated with powerful quasars, to planet-forming disks around young sun-like stars.

Fast Facts for GRO J1655-40: Credit Illustration: NASA/CXC/M.Weiss; X-ray Spectrum: NASA/CXC/U.Michigan/J.Miller et al. Category Black Holes, Neutron Stars/X-ray Binaries Coordinates (J2000) RA 16h 54m 00.14s | Dec -39º 50' 44.90 Constellation Scorpius Observation Dates April 1, 2005 Observation Time 18 hours Obs. IDs 5461 Instrument ACIS/HETG Distance Estimate About 11,000 light years Release Date June 21, 2006

我算是严格的copy了网站原文，这里还有一个视频链接可下载

http://chandra.harvard.edu/photo/2006/j1655/j1655_sm.mov

The X-ray spectrum (see inset) of a binary star system consisting ofa black hole and a normal star indicates that turbulent winds ofmultimillion degree gas are swirling around the black hole. As the illustration shows, much of the hot gas is spiraling inward toward the black hole, but about 30% is blowing away.
上图中的X线光谱揭示了一个包含黑洞的双星系统中，黑洞附近吸积盘中的气体漩涡，这些气体的温度高达数百万度（应该写成等离子体才是）。在想象图中，大部分热气体成螺旋状落下黑洞，但大概30%的气体被吹离了吸积盘。
The temperature and intensity of the winds imply that powerful magnetic fields must be present. These magnetic fields, likely carried by the gas flowing from the companion star, create magnetic turbulence that generates friction in the gaseous disk and drive winds from the disk that carry momentum outward as the gas falls inward. Magnetic friction also heats the gas in the inner part of the disk to X-ray emitting temperatures.
高温等离子体和强烈的粒子风暗示着这里存在超强磁场。由伴星气体（旋转）带来的磁场，在气体旋转中产生磁场湍流，并在气体气体落入黑洞的过程中驱动粒子风的产生（那30%部分——译注），粒子风带走了气体盘的动量（真是有病的老外，这么长句、包含数层意思的关键句怎么不分句来说。貌似天文语法常常长得有病，说些什么大概就他们自己懂——译注）。磁场同时加热吸积盘中的气体发出X线辐射（像这样的语句多好理解！）
The analysis of the disk wind of GRO J1655-40, or J1655 for short,confirmed what astronomers had long suspected, namely that magnetic friction is central to understanding how black holes accrete matter rapidly. With out a process to take away some of the angular momentum of the gas, it could remain in orbit around a black hole for a very longtime.
天文学家长期困惑于黑洞是怎样迅速增加质量的，现在对GRO J1655-40或J1655的磁场风研究分析给出了一个短期答案，也就是说，电磁摩擦损耗是一个主要的原因（这点倒比较好理解，我们都学过物理，知道电磁阻尼。问题是为什么不是加速呢？——译注）。如果没有一个机理带走气体的角动量，它们能在围绕黑洞旋转的轨道上呆上极长的时间。
J1655 is a binary system that harbors a black hole with a mass seven times that of the sun, which is pulling matter from a normal star about twice as massive as the sun. The Chandra observation revealed a bright X-ray source whose spectrum showed dips produced by absorption from a wide variety of atoms ranging from oxygen to nickel. A detailed study of these absorption features shows that the atoms are highly ionized and are moving away from the black hole in a high-speed wind.
J1655是一个包含7倍太阳质量黑洞的双星系统，黑洞正从2倍太阳质量的正常伴星处吸引物质。钱德拉卫星显示它是个明亮的X源，光谱中有从氧O到镍Ni的各种原子的吸收线（没搞错？X线光谱中包含atom原子吸收线？应该说是element元素的离子谱线吧，貌似很不规范的说法——译注）对这些吸收谱线的详细分析表明这些原子已经高度电离并以很高的速度离开黑洞（喷流速度都很高——译注）。
Understanding the importance of magnetic forces in the disk of gas around J1655 could have far-reaching implications, from the supermassive black holes associated with powerful quasars, to planet-forming disks around young sun-like stars.
透彻了解磁力在J1655周围气体盘的作用有着深远的意义，从研究超级黑洞与类星体的关联，到行星尘埃盘与其年轻中型恒星的关系，都会有帮助。

——by gohomeman1

在网上见过，好像大概是这样的，，旋转的黑洞视界外有一个区域，那里的空间是不可避免地被黑洞的旋转所拖曳着一同旋转，外界磁场经过此处时也被扭曲，黑洞旋转的越快，这种对外来磁场的扭曲越强烈，当磁场被强烈扭曲很多圈之后就形成了非常密集的磁力线的形象，也就是磁场变得非常强了，带电粒子很难横穿磁力线运动，于是随着扭曲的磁力线一同旋转着，最终只能从黑洞两极方向上，也就是磁力线螺旋的两头被喷射出，，，

不过为什么黑洞的电荷可以对外界作用还没弄明白，，，

在网上见过，好像大概是这样的，，旋转的黑洞视界外有一个区域，那里的空间是不可避免地被黑洞的旋转所拖曳着一同旋转，外界磁场经过此处时也被扭曲，黑洞旋转的越快，这种对外来磁场的扭曲越强烈，当磁场被强烈扭曲 ...
feng1734 发表于 2009-3-26 14:00

                               
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这样比较倒是好理解。刚才去看忙其他事情了，等会儿再翻译。不过黑洞虽然扭曲了空间，但是如果说黑洞旋转后整个空间跟着转，这貌似有问题了吧？质量对空间的扭曲是各向同性的啊，并没有两极方向扭曲得少的说法。我们平时看见的图大部分是画了一个漏斗，实际上应该是各个方向看处处都是漏斗。至于我们观察到的最后图像，那是整个星系或者双星系统的运行方向早就决定了的。由于吸积盘本身是等离子体，而黑洞附近明显存在超强磁场，这样它们在一定范围内转是必然的。
这样想下去貌似又绕回来了？一开始吸积盘为何在黑洞的赤道平面呢？还是黑洞原先磁场的缘故啊！

PS：版主还是把此贴转到天文知识去吧，发在这里好像发错版了。

虽然我也不大清楚，不过我觉得可以这样理解，，，
爱因斯坦的广义相对论说的应该是能量（不仅仅是质量）可以弯曲时空，对于旋转的黑洞,与静止的黑洞相比它有额外的角动量，也就是有了额外的能量，也就会对时空产生额外的影响，这个额外的影响就与角动量的取向有关，也就是不同方向上时空的扭曲不同，，，，
虽然不大懂，不过还是查了一下，出现在爱因斯坦场方程中的是能量－动量－应力张量，，描述空间弯曲的也是一个张量，，

貌似过头思考黑洞没什么意义，这好像也算一种妄想呢，毕竟与我们自己的生活离得太远了。废话不说了，下面这篇文章我都怀疑已经发过了，因为论坛中搜索“黑洞”有几百条呢，我们人类就喜欢对摸不着的东西感兴趣，是否与中世纪的一个针尖上能站多少个天使一样呢？

PS：下面这篇与黑洞磁场无关，说的是黑洞的强大引力的。先看图没细看文章。现在已经翻了，知道不是要的内容。

感觉飘忽不定应该只是因为了解不够，，，如果能从数学上掌握的话就不会这么怀疑了吧，，，

RX J1242-11:
Giant Black Hole Rips Star Apart

                               
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Credit: Illustration: NASA/CXC/M.Weiss; X-ray: NASA/CXC/MPE/S.Komossa et al.; Optical: ESO/MPE/S.Komossa

X-ray data from Chandra, the European Space Agency's XMM-Newton, and the German Roengtensatellite (ROSAT) X-ray observatories provide direct evidence for the catastrophic destruction of a star that wandered too close to a supermassive black hole.
由钱德拉卫星、欧洲牛顿天文台和德国ROSAT卫星获得的X线观察图像揭示了一个悲惨现场：一个恒星由于游荡到离大质量黑洞太近的距离而被引力撕裂。
The accompanying illustration (top) depicts how such an event may have occurred. A close encounter with another star put the doomed star (orange circle) on a path that took it near a supermassive black hole. The enormous gravity of the giant black hole stretched the star until it was torn apart. Because of the momentum and energy of the accretion process, only a few percent of the disrupted star's mass (indicated by the white stream) was swallowed by the black hole, while the rest of was flung away into the surrounding galaxy.
上图：本事件发生时的艺术效果图。一颗倒霉的恒星（橙色）在轨道上偶尔与大质量黑洞“近距离接触（我意译的——译注）”。黑洞的巨大起潮力把恒星拉长并分裂为碎片。根据动量、能量守恒定律，只有很小部分的恒星质量（白色碎片）落入黑洞，大部分散入周围的银河星空。（我们太阳系这类起潮力事件不是常有嘛！）
Observations with Chandra (lower left image) and XMM-Newton, combined with earlier images from ROSAT, confirmed that a powerful X-ray outburst had occurred in the center of the galaxy RX J1242-11, which appears normal in a ground-based optical image (lower right, with the white circle defining the location of the Chandra image). This X-ray outburst, one of the most powerful ever detected in a galaxy, was caused when gas from the disrupted star was heated to multimillion degree temperatures as it fell toward the black hole.
左下图：根据钱德拉、牛顿天文台和ROSAT（罗萨塔？）卫星的联合观察图像，确认星系RX J1242-11中心有一个强X源。这个星系的可见光图像很正常。
右下图：是地面望远镜拍的，使用的是ESO南方天文台图片（在智利），图中的白圈相当于左下图中蓝色部分范围，可见X卫星图像分辨率更差。这个X图揭示：星系中发生的一次强X辐射被我们探测到了，这个事件就是当恒星碎片气体落入黑洞时，它们被加热到数百万度的高温。（说到现在都还不是正题）
The force that disrupted the star in RX J1242-11 is an extreme example of the tidal force caused by differences in gravity acting on the front and back of an object. The tidal force from the Moon causes tides in the oceans on Earth, and tidal force from Jupiter pulled Comet Shoemaker-Levy apart before it plunged into the giant planet.
RX J1242-11 被引力撕裂是起潮力在星球近端和远端作用力不同的极端例子（由于距离不同，引力是有差别的）。月球的起潮力使大海产生潮汐，也使苏梅克——列维彗星还没落入木星就已经被撕为多块碎片。（PS:此文是2004年的）
The tidal disruption of a star is estimated to occur about once every ten thousand years in a typical galaxy. As astronomers accumulate observations of thousands of galaxies, many more of these events should be detected
此类星系内恒星被撕裂的事件大概每隔1万年就有一例。随着天文学家积累数以千计的星系观测资料，我们会发现更多的此类事件。
不妥之处欢迎指正——gohomeman1

                               
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一个Mpeg动画演示下载
http://chandra.harvard.edu/photo/2004/rxj1242/rxj1242_tidal_disruption_lg.mpg

LZ辛苦了~~~这些文章挺有用的，有时间仔细研究下~

11# gohomeman1

The tidal disruption of a star is estimated to occur about once every ten thousand years in a typical galaxy.

另外：
"Understanding the importance of magnetic forces in the disk of gas around J1655 could have far-reaching implications, from the supermassive black holes associated with powerful quasars, to planet-forming disks around young sun-like stars."
4L这段话感觉译的有点别扭。

11# gohomeman1  

The tidal disruption of a star is estimated to occur about once every ten thousand years in a typical galaxy.

另外：
"Understanding the importance of magnetic forces in the disk of ...
positron 发表于 2009-4-27 20:47

                               
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谢谢指正，那时翻译没多少，许多没细看。