宇宙微波背景下的甲醛轮廓：星系演化时代恒星形成的质量有限、与距离无关、无灭绝的示踪剂
Formaldehyde Silhouettes Against the Cosmic Microwave Background: A Mass-Limited, Distance-Independent, Extinction-Free Tracer of Star Formation Across the Epoch of Galaxy Evolution
摘要：
我们研究了甲醛（H2 CO）对宇宙微波背景（CMB）光子的吸收随宇宙时间的变化。H2 CO的K-二重态转动跃迁通过分子氢（H2）的碰撞泵浦而变得“冷藏”--它们的激发温度被驱动到低于CMB温度。因此，“反反转”H2 CO谱线比率提供了分子云中H2密度的精确测量。利用辐射转移模型，我们证明了H_2CO厘米波长线的激发和探测能力几乎与红移或气体动力学温度无关。由于H2 CO的K双线吸收CMB光，并且CMB位于每个星系的后面，提供了一个非常均匀的扩展照明源，因此H2 CO是一种与距离无关的、无散射的分子气体，是星系中致密气体的质量限制示踪剂。甲醛深场可以以一种独特的无偏见的方式绘制宇宙恒星形成的历史，并且可能与大带宽宽场射电干涉仪一起使用，从而在星系演化的整个时期检测到恒星形成星系的轮廓。我们还研究了H2 CO线可能提供一个类似于星系团中的Sunyaev-Zel'dovich效应的宇宙学可解释的星系统治者的可能性，但适用于更高的红移和更大的样本。最后，我们探讨如何反倒置米波H2 CO线在星系的宇宙恒星形成的高峰期可能会污染HI 21厘米层析再电离时代。
英文摘要：
We examine the absorption of cosmic microwave background (CMB) photons by formaldehyde (H2CO) over cosmic time. The K-doublet rotational transitions of H2CO become "refrigerated" - their excitation temperatures are driven below the CMB temperature - via collisional pumping by molecular hydrogen (H2). "Anti-inverted" H2CO line ratios thus provide an accurate measurement of the H2 density in molecular clouds. Using a radiative transfer model, we demonstrate that H2CO centimeter wavelength line excitation and detectability are nearly independent of redshift or gas kinetic temperature. Since the H2CO K-doublet lines absorb CMB light, and since the CMB lies behind every galaxy and provides an exceptionally uniform extended illumination source, H2CO is a distance-independent, extinction-free molecular gas mass-limited tracer of dense gas in galaxies. A Formaldehyde Deep Field could map the history of cosmic star formation in a uniquely unbiased fashion and may be possible with large bandwidth wide-field radio interferometers whereby the silhouettes of star-forming galaxies would be detected across the epoch of galaxy evolution. We also examine the possibility that H2CO lines may provide a standardizable galaxy ruler for cosmology similar to the Sunyaev-Zel'dovich effect in galaxy clusters but applicable to much higher redshifts and larger samples. Finally, we explore how anti-inverted meterwave H2CO lines in galaxies during the peak of cosmic star formation may contaminate HI 21 cm tomography of the Epoch of Reionization.
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。
