Tracing Gas from Bars to Nuclear Outflows: The Fermi Bubbles & Tilted Disk

Dhanesh Krishnarao被授予美国国家科学基金会天文学和天体物理学博士后奖学金，在约翰霍普金斯大学开展一个研究和教育项目。Krishnarao将利用光谱线在银河系中心附近以高分辨率跟踪和研究星际物质的流动。他将观察到从MW核发出的被称为费米气泡的大型等离子体流出，沿着MW棒的电离气体结构被称为“倾斜盘”，以及银河低电离（核）发射区或LI(N) er的模拟。这项研究的结果将使天文学家了解从一个棒状星系中心出现的气体和辐射是如何影响它的形成和演化的，它们将阐明LI(N) er的起源。对于该项目的教育部分，Krishnarao将开发基于播客的音频课程，以促进中小学生的科学探究，包括当地服务不足社区的学生。利用威斯康星H-Alpha绘图仪，这个研究项目将绘制出费米气泡和银河系中电离气体的第一张连续运动图。结合第五次斯隆数字巡天中现有的发射线和即将到来的吸收线观测结果，该项目将开发一种新的统计方法，在棒状和费米气泡的背景下绘制盘晕界面的气体分布。最后，该项目将使用具有光学和紫外光谱的3D光电离模型来开发对MW棒内LI(N) er的新理解。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。

Dhanesh Krishnarao is awarded an NSF Astronomy and Astrophysics Postdoctoral Fellowship to conduct a program of research and education at Johns Hopkins University. Krishnarao will track and study the flow of interstellar matter at high resolution near the center of the Milky Way (MW) galaxy using optical spectral lines. He will observe large plasma outflows called Fermi Bubbles emanating from the MW nucleus, a structure of ionized gas called the “Tilted Disk” along the MW bar, and the Galactic analog of Low Ionization (Nuclear) Emission Regions or LI(N)ERs. Results from this study will allow astronomers to understand how gas and radiation emerging from the center of a barred galaxy influence its formation and evolution, and they will shed light on the origin of LI(N)ERs. For the education component of this project, Krishnarao will develop podcast-based audio courses to promote scientific inquiry in elementary and middle school students, including ones in local underserved communities.Using the Wisconsin H-Alpha Mapper, this research project will produce the first ever continuous kinematic map of ionized gas in the Fermi Bubbles and the bar of the Milky Way. Combining existing emission-line and upcoming absorption-line observations in the fifth Sloan Digital Sky Survey, the project will develop a new statistical method to map the gas distribution at the disk-halo interface within the context of the bar and Fermi Bubbles. Lastly, the project will use 3D photoionization modeling with optical and UV spectra to develop a new understanding of LI(N)ERs within the MW bar.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.