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arXiv 1111.2059astro-ph.CO
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宇宙中重子分布演化的宇宙学模拟

The Evolution of the Baryon Distribution in the Universe from Cosmological Simulations

Fabrice Durier, Jose Antonio de Freitas Pacheco

摘要:

本文报道了由宇宙学模拟得到的不同相态的重子分布演化。计算结果表明,目前大部分重子处于温暖的星系际(WHIM)介质中(约占43%),而在z = 2.5时,大部分重子构成弥散介质(约占74%)。恒星和星系中的冷气体只占z = 0的重子的14%。当z < 4时,大约一半的金属被锁定在恒星中,而WHIM和扩散介质中的金属则随着红移的减小而增加。在0 < z < 2.5的红移范围内,WHIM中的金属量从4%增加到22%,而在扩散介质中,金属量从0.6%增加到4%。这种富集过程主要是由于与超新星爆炸驱动的质量运动相关的湍流扩散机制。在z = 0时,模拟的蓝色(晚型)星系显示出与来自HII区域的数据相当吻合的所考虑的星系的光度与冷气中存在的氧丰度的相关性。

英文摘要:

The evolution of the baryon distribution in different phases, derived from cosmological simulations, are here reported. These computations indicate that presently most of baryons are in a warm-hot intergalactic (WHIM) medium (about 43%) while at z = 2.5 most of baryons constitute the diffuse medium (about 74%). Stars and the cold gas in galaxies represent only 14% of the baryons at z = 0. For z < 4 about a half of the metals are locked into stars while the fraction present in the WHIM and in the diffuse medium increases with a decreasing redshift. In the redshift range 0 < z < 2.5, the amount of metals in the WHIM increases from 4% to 22% while in the diffuse medium it increases from 0.6% to 4%. This enrichment process is due essentially to a turbulent diffusion mechanism associated to mass motions driven by supernova explosions. At z = 0, simulated blue (late type) galaxies show a correlation of the oxygen abundance present in the cold gas with the luminosity of the considered galaxy that agrees quite well with data derived from HII regions.

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