Mapping Galactic Magnetic Fields with SPARO

该项目将在未来三个冬季继续在南极运行用于南极远程观测的亚毫米偏振计（SPARO）。SPARO仪器在毒蛇2米望远镜上运行，最近在第一年的观测后进行了升级。在南极高原上异常透射和稳定的冬季天空中，SPARO为星际区域的磁场提供了一个强大的探测器。亚毫米波长的测量提供了一种方法，通过测量磁性排列星际尘埃颗粒的热辐射的线性极化，来绘制银河系致密星际区域的磁场。星际磁场通常很难观察到，但它们可以帮助我们理解星际气体（因此也可能是磁场）扮演重要角色的两个一般问题：星系中心的研究和恒星形成。银河系中心是一个辐射高度活跃的区域。在一些被称为“活动星系核”（AGN）的中心，核心或中心核心产生的辐射比整个星系的其余部分还要多。AGN的大小可能比我们的太阳系还小，目前的理论表明，AGN的中心有一个超大质量黑洞。这里提出的观测旨在(a)证实SPARO最近在银河系中心发现的大规模环形磁场，(b)测试“银河系中心叶”的磁流出模型——一个可能追踪从星系核喷出的气体的无线电结构，以及(c)在恒星形成云样本中绘制大规模磁场，以研究这些云的细长形状与其磁场之间的关系。

This project will continue the operation of the Submillimeter Polarimeter for Antarctic Remote Observations (SPARO) at the South Pole for the next three winter seasons. The SPARO instrument is operated on the Viper 2-meter telescope, and has recently been upgraded following its first year of observations. In the exceptionally transmissive and stable winter-time skies over the Antarctic plateau, SPARO provides a powerful probe of magnetic fields in interstellar regions. Measurements at submillimeter wavelengths provide a method for mapping magnetic fields in the denser interstellar regions of the galaxy by measuring the linear polarization of thermal emission from magnetically aligned interstellar dust grains. Interstellar magnetic fields are generally difficult to observe, but they can contribute to our understanding of two general problems in which interstellar gas (and thus probably also magnetic fields) play important roles: the study of the galactic center, and star formation. The galactic center is a highly radiationally active region. In some centers, known as "active galactic nuclei" (AGN), the nucleus or central core produces more radiation than the entire rest of the galaxy. The size of an AGN can be smaller than the size of our solar system, and current theory suggests that there is a supermassive black hole at the center of an AGN. Observations proposed here are aimed at (a) confirming SPARO's recent discovery of a large-scale toroidal magnetic field at the galactic center, (b) testing a magnetic outflow model for the "Galactic Center Lobe" - a radio structure possibly tracing gas that has been ejected from the galactic nucleus, and (c) mapping large-scale magnetic fields in a sample of star forming clouds in order to study the relationship between the elongated shapes of these clouds and their magnetic fields.