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.

tiansam1990

什么galaxy cluster啊 完全看不懂。。。。

Bale

bale 有没有伽利略pump那篇详细的JJ啊

-- by 会员 danielzjd (2011/6/11 16:30:22)

我没有，要是RC稿里有我就有，但我自己没考古过

danielzjd

bale 有没有伽利略pump那篇详细的JJ啊

Bale

机经2.2.5 galaxy cluster的原文（我猜的，应该挺像的，希望狗主人能确认）

GWD27-Q10 to Q12:
     Astronomers theorize that a black hole forms when a massive object shrinks catastrophically under its own gravity, leaving only a gravitational field so strong that nothing escapes it. Astronomers must infer the existence of black holes, which are invisible, from their gravitational influence on the visible bodies surrounding them. For example, observations indicate that gas clouds in galaxy M87 are whirling unusually fast about the galaxy’s center. Most astronomers believe that the large concentration of mass at the galaxy’s center is a black hole whose gravity is causing the gas to whirl. A few skeptics have argued that the concentration of mass necessary to explain the speed of the whirling gas is not necessarily a black hole: the concentration in M87 might be a cluster of a billion or so dim stars.
   The same hypothesis might have been applied to the galaxy NGC 4258, but the notion of such a cluster’s existing in NGC 4258 was severely undermined when astronomers measured the speed of a ring of dust and gas rotating close to the galaxy’s center. From its speed, they calculated that the core’s density is more than 40 times the density estimated for any other galaxy.  If the center of NGC 4258 were a star cluster, the stars would be so closely spaced that collisions between individual stars would have long ago torn the cluster apart.
我觉得这篇更像，我在做的时候一直有这种感觉的说...

-- by 会员 hemingsun (2011/6/11 15:24:17)

这个我已经想到了……但它没有出现heating和cooling这俩关键词

hemingsun

机经2.2.5 galaxy cluster的原文（我猜的，应该挺像的，希望狗主人能确认）

GWD27-Q10 to Q12:
     Astronomers theorize that a black hole forms when a massive object shrinks catastrophically under its own gravity, leaving only a gravitational field so strong that nothing escapes it. Astronomers must infer the existence of black holes, which are invisible, from their gravitational influence on the visible bodies surrounding them. For example, observations indicate that gas clouds in galaxy M87 are whirling unusually fast about the galaxy’s center. Most astronomers believe that the large concentration of mass at the galaxy’s center is a black hole whose gravity is causing the gas to whirl. A few skeptics have argued that the concentration of mass necessary to explain the speed of the whirling gas is not necessarily a black hole: the concentration in M87 might be a cluster of a billion or so dim stars.
   The same hypothesis might have been applied to the galaxy NGC 4258, but the notion of such a cluster’s existing in NGC 4258 was severely undermined when astronomers measured the speed of a ring of dust and gas rotating close to the galaxy’s center. From its speed, they calculated that the core’s density is more than 40 times the density estimated for any other galaxy.  If the center of NGC 4258 were a star cluster, the stars would be so closely spaced that collisions between individual stars would have long ago torn the cluster apart.
我觉得这篇更像，我在做的时候一直有这种感觉的说...

cgzjessieli

呜呜，就我一人考到这个~~我真的憋不出来关键词了~~~我在google一下~~

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

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

要不同学再回忆些关键词呗……

-- by 会员 Bale (2011/6/10 17:56:17)

expand， heating， cooling， two black holes，

寂寞倚残霞

发自肺腑地感慨：bale和coco你们都是神人呐！

camelo777

求狗主确认~