Dust Obscuration towards the Epoch of Reionization

哈勃太空望远镜拍摄的深空图像揭示了宇宙中最遥远的星系。这些天体是由像太阳一样的数千到数百万颗恒星组成的群体。它们是如此遥远，以至于它们的恒星发出的光需要数十亿年才能到达我们这里。在哈勃望远镜拍摄的最深处的图像中，大多数如此遥远的星系都是可见的，但并非全部。一些星系含有大量的尘埃，这使得它们很难被观测到，因为尘埃会遮挡星光。星光加热尘埃，然后将能量以毫米波长重新辐射出去。这些尘埃星系形成恒星的速度非常快，对我们了解恒星的形成方式非常重要。在宇宙大爆炸后的最初几十亿年里，尘埃星系有多普遍，我们知之甚少。该项目将使用所有可用的毫米波数据来估计它们在早期的普遍程度。这对我们理解第一个星系是如何形成的至关重要。该项目还将通过德克萨斯大学奥斯汀分校为代表性不足的学生提供的德克萨斯天文学本科生研究（TAURUS）项目，接待来自代表性不足的少数民族背景的天文学研究学生。该研究项目的目标是留住这些优秀的学生从事STEM职业。对恒星形成的宇宙历史进行普查是星系演化调查的一个关键目标。然而，迄今为止的测量，特别是在最高红移的测量，几乎完全是由静止框架UV/光学中未遮挡的恒星形成示踪剂确定的。然而，在恒星质量（10^10 Msun）和恒星形成速率（50 Msun/年）较高的星系中，越来越多的星系被尘埃辐射所掩盖，因此紫外线/光学推断的SFRs可以被低估10-100倍。本提案的目标是在新开发的反向演化模型中使用所有通过毫米数据的集合FIR来：(1)统计约束总积分红外星系亮度函数到高红移，(2)测量AGN对总宇宙红外背景的贡献，(3)提供亚毫米源多样性的非聚类预测，(4)使用模拟来激励未来大型（亚）毫米巡天以优化高红移。该项目将吸引来自代表性不足背景的本科生研究学者到德州大学奥斯汀分校，在夏季通过TAURUS项目对这一主题进行研究。TAURUS专注于长期留住那些在STEM职业中积极性高、代表性不足的学生。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Deep-space images from the Hubble Space Telescope reveal the most distant galaxies in the Universe. These objects are groups of thousands to millions of stars like our sun. They are so distant that light from their stars has taken billions of years to reach us. Most galaxies this distant are visible in the deepest images from Hubble, but not all. Some galaxies contain a lot of dust, making them more difficult to see because the dust obscures starlight. Starlight heats the dust, which then re-radiates that energy at millimeter wavelengths. These dusty galaxies form stars very rapidly, and are important to our understanding of how stars form. Little is known about how common dusty galaxies were in the first few billion years after the Big Bang. This project will use all available data at millimeter wavelengths to estimate how common they were during those early times. This is important to our fundamental understanding of how the first galaxies formed. This project will also host students from under-represented minority backgrounds in astronomy research through the Texas Astronomy Undergraduate Research for Under- represented Students (TAURUS) program at UT Austin. The goal of the research program is to retain these excellent students in STEM careers.Taking census of the cosmic history of star-formation is a key goal of galaxy evolution surveys. However, measurements to date, particularly at the highest redshifts, are almost exclusively determined from unobscured star-formation tracers in the rest-frame UV/optical. However, galaxies are increasingly obscured by dust emission at higher stellar masses ( 10^10 Msun) and star-formation rates ( 50 Msun/year), such that UV/optical-inferred SFRs can be underestimated by factors of 10-100x. The goal of this proposal is to use all of the collective FIR through millimeter data in a newly developed backward evolution model to: (1) statistically constrain the total integrated IR galaxy luminosity function out to high-redshifts, (2) measure the AGN contribution to the total cosmic infrared background, (3) provide non-clustered predictions for submm source multiplicity, and (4) use simulations to motivate future large (sub)mm surveys for optimization at high-redshifts. This project will draw in undergraduate research scholars from under-represented backgrounds to UT Austin for the summer to conduct research on this topic through the TAURUS program. TAURUS focuses on the long-term retention of highly-motivated under-represented students in STEM careers.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.