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arXiv 0904.0448astro-ph.CO
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自红移1以来星系团和星系团中的恒星和总重子质量分数

Stellar and total baryon mass fractions in groups and clusters since redshift 1

S. Giodini, D. Pierini, A. Finoguenov, G. W. Pratt, H. Boehringer, A. Leauthaud, L. Guzzo, H. Aussel, M. Bolzonella, P. Capak, M. Elvis, G. Hasinger, O. Ilbert,… 展开作者

S. Giodini, D. Pierini, A. Finoguenov, G. W. Pratt, H. Boehringer, A. Leauthaud, L. Guzzo, H. Aussel, M. Bolzonella, P. Capak, M. Elvis, G. Hasinger, O. Ilbert, J. S. Kartaltepe, A. M. Koekemoer, S. J. Lilly, R. Massey, H. J. McCracken, J. Rhodes, M. Salvato, D. B. Sanders, N. Z. Scoville, S. Sasaki, V. Smolcic, Y. Taniguchi, D. Thompson, the COSMOS collaboration

摘要:

我们调查,如果从观测的宇宙微波背景(CMB)和星系群/星系团的总重子质量分数的估计之间的差异仍然存在时,被认为是一个大样本的群体。为此,我们从COSMOS 2 deg^2巡天中选出了91个红移为0.1 < z < 1的候选X射线群/贫星系团,仅根据它们的X射线光度和范围。这个样本是由27个附近的集群与一个强大的,类似的总质量和恒星内部R_500的测定补充。118个z < 1的星系群和星系团的总样本跨越了M500中~10^13- 10^15太阳质量的范围。我们发现,在R_500处与星系相关的恒星质量分数随总质量的增加而减小,为(M_500)^-0.37 \pm 0.04,与红移无关。根据最近导出的高质量标度关系估算总气体质量分数,发现当M_500从=5 × 10^13 M_sun增加到= 7 × 10^14 M_sun时,总重子质量分数(f_500 ^stars +gas= f_500 ^stars + f_500 ^gas)增加了~ 25%<M><M>。在考虑了星系团内光(占恒星总质量的11--22%)和通过分级组装过程产生的气体损耗(占气体质量的10%)的合理贡献之后,重子总质量分数的估计值仍然低于最新的宇宙微波背景辐射测量的相同质量(WMAP 5),对于=5 × 10^13~M_sun的星系团,其显著性水平为3.3σ<M>。总质量越大,这种差异越小,在<M>= 7 × 10 ^14 ~M_sun时,这种差异为1σ。我们讨论这个结果的非引力过程,如反馈和间接加热。

英文摘要:

We investigate if the discrepancy between estimates of the total baryon mass fraction obtained from observations of the cosmic microwave background (CMB) and of galaxy groups/clusters persists when a large sample of groups is considered. To this purpose, 91 candidate X-ray groups/poor clusters at redshift 0.1 < z < 1 are selected from the COSMOS 2 deg^2 survey, based only on their X-ray luminosity and extent. This sample is complemented by 27 nearby clusters with a robust, analogous determination of the total and stellar mass inside R_500. The total sample of 118 groups and clusters with z < 1 spans a range in M_500 of ~10^13--10^15 M_sun. We find that the stellar mass fraction associated with galaxies at R_500 decreases with increasing total mass as (M_500)^-0.37 \pm 0.04, independent of redshift. Estimating the total gas mass fraction from a recently derived, high quality scaling relation, the total baryon mass fraction (f_500^stars+gas=f_500^stars+f_500^gas) is found to increase by ~ 25% when M_500 increases from <M>=5 X 10^13 M_sun to <M> = 7 X 10^14 M_sun. After consideration of a plausible contribution due to intra--cluster light (11--22% of the total stellar mass), and gas depletion through the hierarchical assembly process (10% of the gas mass), the estimated values of the total baryon mass fraction are still lower than the latest CMB measure of the same quantity (WMAP5), at a significance level of 3.3σfor groups of <M>=5 X 10^13~M_sun. The discrepancy decreases towards higher total masses, such that it is 1σat <M>= 7 X 10^14~M_sun. We discuss this result in terms of non--gravitational processes such as feedback and filamentary heating.

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