Using Polarization to Reveal the Nature of Lyman-alpha Nebulae

天文学家试图了解恒星和星系是如何形成的。早期的宇宙被认为是弥漫的气体。所有这些气体现在都应该在引力的影响下坍塌成恒星。然而，它的大部分是弥漫的。现在只有一小部分存在于星系中。扎布卢多夫和他的合作者研究神秘的、发光的这种气体云，这些气体可能是星系的祖先。为了了解它们的发光，这些研究人员将研究它们的光的偏振。极化可以揭示其潜在能量来源的性质。这项研究是由6.5米MMT望远镜上的一台特殊仪器实现的，该仪器在记录图像的同时对偏振很敏感。该项目将揭示星系如何与其环境相互作用。除了这项开创性的研究外，国际和平协会还将开展外联活动。这些活动将包括参加为少女举办的天文讲习班，以及向美洲原住民社区进行研究和职业介绍。这些努力支持在代表性不足的群体中扩大对科学的参与。这个项目是对莱曼-阿尔法团的研究，莱曼-阿尔法团是巨大的(约100kpc)发光气体云，与丰富的星系团相关。他们的莱曼-阿尔法辐射的来源尚不清楚。两种可能性包括就地产生的光致电离辐射或来自中心源的辐射的共振散射。偏振测量可以区分这些机制，因为共振散射会导致很大的偏振梯度，而原位光电离则不会产生偏振。扎布卢多夫和他的合作者将使用6.5米MMT望远镜上的SPOL成像光谱偏振仪研究数十个这样的星系的统计样本。对这些数据的分析将与辐射传输模型进行比较，以揭示气泡是如何发光的，以及在什么情况下不同的机制起作用。这项研究将导致大质量星系与它们所在的环星系介质之间更详细的联系。

Astronomers seek to understand how stars and galaxies formed. The early universe was believed to be pervaded by diffuse gas. All this gas should have collapsed into stars by now under the influence of gravity. However, most of it is diffuse. Only a small fraction now resides in galaxies. Zabludoff and collaborators study mysterious, glowing clouds of such gas that may be the progenitors of galaxies. To understand their glowing emission, these investigators will study polarization of their light. Polarization can reveal the nature of their underlying power sources. This study is enabled by a special instrument at the 6.5m MMT telescope that is sensitive to polarization while also recording images. The project will reveal how galaxies interact with their environments. In addition to this ground-breaking research, the PI will engage in outreach activities. Such activities will include participating in an astronomy workshop for teenage girls and research and career presentations to a native American community. Such efforts support broadening participation in science among underrepresented groups.This project is a study of Lyman-alpha blobs, which are giant (~100 kpc) glowing clouds of gas that are associated with rich clusters of galaxies. The source of their Lyman-alpha emission is not known. Two possibilities include photo-ionizing radiation produced in situ or resonant scattering of radiation from a central source. Polarization measurements can differentiate between these mechanisms because resonant scattering leads to large polarization gradients while in situ photoionization produces no polarization. Zabludoff and collaborators will study a statistical sample of dozens of such galaxies with the SPOL imaging spectro-polarimeter on the 6.5 m MMT telescope. Analysis of such data will be compared with radiative transfer models to reveal how blobs glow and under what circumstances different mechanisms are responsible. This research will lead to a more detailed connection between massive galaxies and the circumgalactic medium in which they live.