星系演化

z = 1000
How do galaxies interact with their environment?

What are the global histories of SF, metal enrichment, and gas consumption?

What is the relationship between active galactic nuclei and their host galaxies?
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Baidu Nhomakorabea
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How did galaxies form?
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Our best models for galaxy formation assume:
• Matter originally filled all of space almost uniformly
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观测证据: Hubble空间望远镜的深场观测发现位于
2000 Mpc距离之外存在大量的不规则的小星系（超过 同类星系在近距离星系中的比例）。
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由上而下 模型（top-down）

(Old light from young galaxies)
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Kong et al. 2006, 2007
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whereas stars almost never collide with one another, galaxies may suffer many collisions and mergers during their lives, making it much harder to decipher their pasts.

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z= 0
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How did the Hubble sequence of galaxy morphologies form?
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How do galaxies interact with their environment?
• Gravity of denser regions pulled in surrounding matter
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Denser regions contracted, forming protogalactic clouds
H and He gases in these clouds formed the first stars
原始气体的坍 缩首先产生巨 大的 (~1014M⊙)、 薄饼状的云块( 超星系团)。

云块分裂成星 系团和星系。
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Deep observations show us very distant galaxies as they were much earlier in time
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BzK-15504 VLT-SINFONI 自适应光学
BzK-15504 is a gaint spiral galaxy, with a size and mass similar to that of the Milky Way, but z~2.4!
第六章 河外星系
研究历史 星系分类 星系测量 特殊星系 星 系 团 星系演化
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星系的形成和演化

How then did those different galaxies come into being?
Do we understand galaxy formation as well as star formation?
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NGC 4414
M87
But why do some galaxies end up looking so different?
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Formation of galaxies?
How did the Hubble sequence of galaxy morphologies form?
10^5 galaxies with redshift
10^7 In 2008
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自下而上（bottom-up）模型

较小的(~106 M⊙)、不规则 星系首先形成 星系合并形成 较大的(~1091011 M⊙)星系 在引力的作用 下聚集成星系 团和超星系团， 产生星系团间 的巨洞

The answer is no!
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星系的形成和演化

Why?


galaxies are much more complex than stars
they are harder to observe (z~6.93)


the observations are harder to interpret.
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Supernova explosions from first stars kept much of the gas from forming stars Leftover gas settled into spinning disk
Conservation of angular momentum
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在座各位！
路漫漫其修远兮， 吾将上下而求索!
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