考过galaxy cluster的筒子帮忙确认下相关度~谢谢~

Bale

这篇abstract提到了某位筒子回忆出的这篇RC的关键词，请考过的同学帮确认一下相关程度~

The activities of a supermassive black holeor active galactic nucleus in the central galaxy of a cluster of galaxies havebeen promising candidates for the heating sources of cool cluster cores. Weestimate the masses of black holes using known correlations between the mass ofa black hole and the velocity dispersion or the luminosity of the host galaxy.We ?nd that the masses are 10^8 – 10^9M and the central X-ray luminosities of the host clusters(‘‘the strength of the cooling ?ow’’) are well below the Eddingtonluminosities. However, we do not ?nd a correlation between the mass and thecentral X-ray luminosity of the host cluster. If the heating is stable,
this seems to contradict a simpleexpectation if a supermassive black hole is the main heating source of acluster core. Moreover, if we assume a canonical energy conversion rate (10%),black holes alone would be unable to suf?ciently heat the clusters with strongcentrally peaked X-ray emission (‘‘massive cooling ?ows’’) over the lifetime ofcluster cores. These results may indicate that massive cooling ?ows are atransient phenomenon, perhaps because the black holes are activatedperiodically. Alternatively, in the massive cooling ?ow clusters, the energyconversion rate may be larger than 10%, that is, the black holes may be Kerrblack holes.

cgzjessieli

挺像的，但是文章没提到具体数据。文章好像是先说了一个现象（或者是一个旧的观点），然后说实际观察好像不一样，就是有了矛盾。第二段就是开始解释（还有第三段不过具体内容实在是想不起来了）那篇文章没太怎么看懂，是我的第三篇阅读，外加理科机制又挺多的，不过，感觉LZ这篇挺像的~~~

Bale

挺像的，但是文章没提到具体数据。文章好像是先说了一个现象（或者是一个旧的观点），然后说实际观察好像不一样，就是有了矛盾。第二段就是开始解释（还有第三段不过具体内容实在是想不起来了）那篇文章没太怎么看懂，是我的第三篇阅读，外加理科机制又挺多的，不过，感觉LZ这篇挺像的~~~

-- by 会员 cgzjessieli (2011/6/10 17:44:00)

出题时GMAC肯定要把数字省掉的。还有we啥的都换成scientists之类。
意思是那篇RC是长文章吗？我找到的PDF里有还有比较细的introduction部分

cgzjessieli

也不是特别长，但我觉得好像不属于难文章

cgzjessieli

我又仔细看了看，原文好像不是主要讲source的，好像提到了收缩和膨胀什么的

Bale

我又仔细看了看，原文好像不是主要讲source的，好像提到了收缩和膨胀什么的

-- by 会员 cgzjessieli (2011/6/10 17:54:53)

要不同学再回忆些关键词呗……

藜芦

LZ和狗主都好强大！！

forevercoco

麻烦lz帮忙看看是不是这篇啊~~~天文的文章真是坑爹~中文的都看不懂~
Dark energy expands and contracts universe
Thursday, 18 December 2008
Agence France-Presse

Mysterious energy: We may not know what it is, but dark energy is busy expanding and contracting our universe, researchers say.
Credit: NASA/CXC/SAO/A.Vikhlinin et al.
WASHINGTON: Mysterious dark energy works simultaneously to expand the universe and shrink objects inside it, astronomers have found.

"This result could be described as 'arrested development of the universe'... Whatever is forcing the expansion of the universe to speed up is also forcing its development to slow down," said Alexey Vikhlinin of the Smithsonian Astrophysical Observatory in Massachusetts.

Vikhlinin was the lead researcher of the study, to be published next year in the Astrophysical Journal.

A galaxy torn apart?

By studying how gravity competes with the expansion of galaxy clusters, using NASA's Chandra X-ray Observatory, "a crucial independent test of dark energy" has been found, said the researchers.

After years of research, scientists now believe that dark energy makes up about 70 per cent of the universe, and is "a form of repulsive gravity that dominates the universe," the researchers wrote, "although [we] have no clear picture of what it actually is."

The discovery of dark energy's dual effects of expansion and contraction sheds light on changes in the universe to come: "What this means for the future of this universe is that accelerated expansion will proceed forever but will probably not result in a Big Rip," said Vikhlinin.

"That is, nearby galaxies will eventually disappear from our sight, but the structures already formed by clusters of galaxies and our own galaxy will not be torn apart, not in the near future anyway."

"Nothing weighs something"

The new research provides the "strongest evidence yet that dark energy is the cosmological constant," Vikhlinin said, being similar to the energy of empty space. "Or in other words, that 'nothing weighs something."

The discovery of dark energy in 1998 sparked renewed interest in Albert Einstein's theory of cosmological constants, a modification of his theory of relativity which suggests a possible repulsive force in the universe.

Einstein hypothesised that a repulsive force in space could explain the universe's equilibrium with the force of gravity.

Without such a contrary force, gravity would cause the universe to implode, Einstein suggested.

Bale

麻烦lz帮忙看看是不是这篇啊~~~天文的文章真是坑爹~中文的都看不懂~
Dark energy expands and contracts universe
Thursday, 18 December 2008
Agence France-Presse

Mysterious energy: We may not know what it is, but dark energy is busy expanding and contracting our universe, researchers say.
Credit: NASA/CXC/SAO/A.Vikhlinin et al.
WASHINGTON: Mysterious dark energy works simultaneously to expand the universe and shrink objects inside it, astronomers have found.

"This result could be described as 'arrested development of the universe'... Whatever is forcing the expansion of the universe to speed up is also forcing its development to slow down," said Alexey Vikhlinin of the Smithsonian Astrophysical Observatory in Massachusetts.

Vikhlinin was the lead researcher of the study, to be published next year in the Astrophysical Journal.

A galaxy torn apart?

By studying how gravity competes with the expansion of galaxy clusters, using NASA's Chandra X-ray Observatory, "a crucial independent test of dark energy" has been found, said the researchers.

After years of research, scientists now believe that dark energy makes up about 70 per cent of the universe, and is "a form of repulsive gravity that dominates the universe," the researchers wrote, "although [we] have no clear picture of what it actually is."

The discovery of dark energy's dual effects of expansion and contraction sheds light on changes in the universe to come: "What this means for the future of this universe is that accelerated expansion will proceed forever but will probably not result in a Big Rip," said Vikhlinin.

"That is, nearby galaxies will eventually disappear from our sight, but the structures already formed by clusters of galaxies and our own galaxy will not be torn apart, not in the near future anyway."

"Nothing weighs something"

The new research provides the "strongest evidence yet that dark energy is the cosmological constant," Vikhlinin said, being similar to the energy of empty space. "Or in other words, that 'nothing weighs something."

The discovery of dark energy in 1998 sparked renewed interest in Albert Einstein's theory of cosmological constants, a modification of his theory of relativity which suggests a possible repulsive force in the universe.

Einstein hypothesised that a repulsive force in space could explain the universe's equilibrium with the force of gravity.

Without such a contrary force, gravity would cause the universe to implode, Einstein suggested.

-- by 会员 forevercoco (2011/6/10 22:19:01)

这篇有收缩和扩张了，又少了黑洞。纠结了，就没别人考到吗……

camelo777

求狗主确认~