Dust Obscuration towards the Epoch of Reionization

来自哈勃太空望远镜的深空图像揭示了宇宙中最遥远的星系。这些天体是由数千到数百万颗恒星组成的群体，就像我们的太阳一样。它们的距离如此之远，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。大多数如此遥远的星系在哈勃望远镜拍摄的最深处的图像中都能看到，但不是全部。一些星系含有大量的尘埃，因为尘埃遮挡了星光，所以更难看到它们。星光加热尘埃，然后尘埃以毫米波长重新辐射能量。这些尘埃星系形成恒星的速度非常快，对我们理解恒星是如何形成的很重要。大爆炸后最初的几十亿年里，尘埃星系有多常见，我们知之甚少。该项目将使用所有可用的毫米波长数据来估计它们在早期有多常见。这对于我们从根本上理解第一批星系是如何形成的很重要。该项目还将通过德克萨斯大学奥斯汀分校的德克萨斯天文学本科生代表不足学生研究计划(Taurus)，接待来自代表不足的少数族裔背景的学生进行天文学研究。该研究计划的目标是将这些优秀的学生留在STEM职业生涯中。普查恒星形成的宇宙历史是星系演化调查的关键目标。然而，迄今为止的测量，特别是最高红移的测量，几乎完全是由静止帧UV/光学中未被遮挡的恒星形成示踪物确定的。然而，更高恒星质量(10^10毫升/年)和更高恒星形成速率(50毫升/年)的尘埃发射越来越遮蔽星系，因此UV/光学推断的SFR可能被低估10-100倍。这项提议的目标是在新开发的反向演化模型中使用所有集合的FIR到毫米数据，以：(1)从统计上约束总的综合红外星系光度函数至高红移，(2)测量活动星系核对总宇宙红外背景的贡献，(3)提供对亚毫米源多重性的非集群预测，以及(4)利用模拟来激励未来在高红移时进行大型(亚)毫米调查以进行优化。这个项目将吸引来自代表性不足背景的本科生研究学者到德克萨斯大学奥斯汀大学度过夏天，通过金牛座计划进行这一主题的研究。金牛座关注的是在STEM职业生涯中长期留住高积极性的代表不足的学生。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.