arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 1507.01583astro-ph.COastro-ph.GA
收藏

利用宇宙微波背景的光谱畸变测量宇宙温度

Taking the Universe's Temperature with Spectral Distortions of the Cosmic Microwave Background

J. Colin Hill, Nick Battaglia, Jens Chluba, Simone Ferraro, Emmanuel Schaan, David N. Spergel

摘要:

宇宙微波背景(CMB)能谱是一个接近完美的黑体。宇宙学的标准模型预测这种形式的光谱会有微小的扭曲,但天空平均CMB光谱的这种扭曲还没有被测量到。我们计算了最大的预期失真,这是由热的,自由电子,称为热Sunyaev-Zel'dovich(tSZ)效应的CMB光子的逆康普顿散射引起的。我们表明,预测的信号是大约一个数量级低于目前的约束从COBE-FIRAS实验,但可以检测到在巨大的意义($\gtrsim 1000σ$)的建议原始通货膨胀探测器(PIXIE)。虽然宇宙方差将有效信噪比降低到$230σ$,但这种测量仍然会对可观测宇宙中电子的总热能产生低于百分比的约束。此外,我们表明,PIXIE可以检测到微妙的相对论效应的天空平均tSZ信号在$30σ$,直接探测的光学深度加权的集群内介质电子温度分布的时刻。这些效应打破了平均tSZ信号中电子密度和温度之间的简并性,允许直接推断低红移下的平均重子密度。因此,未来的光谱畸变探测器将以前所未有的精度确定宇宙中电离气体的全球热力学性质。这些测量将对星系形成和宇宙时间内反馈能量注入的模型施加基本的“积分约束”。

英文摘要:

The cosmic microwave background (CMB) energy spectrum is a near-perfect blackbody. The standard model of cosmology predicts small spectral distortions to this form, but no such distortion of the sky-averaged CMB spectrum has yet been measured. We calculate the largest expected distortion, which arises from the inverse Compton scattering of CMB photons off hot, free electrons, known as the thermal Sunyaev-Zel'dovich (tSZ) effect. We show that the predicted signal is roughly one order of magnitude below the current bound from the COBE-FIRAS experiment, but can be detected at enormous significance ($\gtrsim 1000σ$) by the proposed Primordial Inflation Explorer (PIXIE). Although cosmic variance reduces the effective signal-to-noise to $230σ$, this measurement will still yield a sub-percent constraint on the total thermal energy of electrons in the observable universe. Furthermore, we show that PIXIE can detect subtle relativistic effects in the sky-averaged tSZ signal at $30σ$, which directly probe moments of the optical depth-weighted intracluster medium electron temperature distribution. These effects break the degeneracy between the electron density and temperature in the mean tSZ signal, allowing a direct inference of the mean baryon density at low redshift. Future spectral distortion probes will thus determine the global thermodynamic properties of ionized gas in the universe with unprecedented precision. These measurements will impose a fundamental "integral constraint" on models of galaxy formation and the injection of feedback energy over cosmic time.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑