A UV survey of hot, coronal gas in the halos of low-redshift galaxies

对低红移星系晕中热日冕气体的紫外线调查

• 批准号: 498377446
• 负责人: Professor Dr. Philipp Richter
• 金额: --
• 依托单位: Institut für Physik und Astronomie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/498377446?language=en
• 关键词: UV; survey; hot; coronal; gas

Galaxies are surrounded by huge amounts of diffuse gas that resides in their extended dark-matter halos. This so-called circumgalactic medium (CGM) plays an important role for galaxy evolution. The shock-heated, hot CGM phase (the “Corona”) contains the dominant mass fraction of the CGM, but is very difficult to be observed directly because of the very low gas densities and a very high degree of ionization. In this PhD project, we will use a new method to study the hot coronal gas around galaxies in the local Universe by way of so-called Coronal Broad Lyman Alpha Absorbers (CBLAs). These are broad and shallow HI absorption features seen in the ultraviolet (UV) spectra of background point sources. CBLAs arise from the tiny neutral gas fraction in the hot gas halos of foreground galaxies. We will use archival ultraviolet spectral data from the HST/COS spectrograph to systematically study the properties of ~50 CBLAs at redshifts z<0.5 and constrain the extent and physical properties of the coronal gas in the associated foreground galaxies. The observational approach will be supplemented with the systematic study of CBLAs in synthetic spectra generated from numerical magneto-hydrodynamic simulations of the CGM. The combination of a large CBLA sample from HST/COS spectral data and simulations will enable us to better understand the nature of the broad Lyman Alpha features that arise from the hot gas halos of galaxies and explore their importance for observationally constraining galaxy-evolution models.

星系被大量弥漫性气体包围，它们驻留在其延伸的深色晕孔中。这种所谓的循环培养基（CGM）对于星系进化起着重要作用。冲击热的CGM相（“电晕”）包含CGM的主要质量分数，但由于气体密度非常低和高度电离，很难直接观察到很难直接观察到。在这个博士学位项目中，我们将使用一种新方法来研究当地宇宙中星系周围的热冠气，以所谓的冠状lyman alpha吸收器（CBLA）。这些是背景点源的紫外线（UV）光谱中看到的宽阔而浅的HI抽象特征。 CBLA是由前景星系热气晕的微小中性气体分数引起的。我们将使用从HST/COS光谱仪的档案紫外光谱数据系统地研究红移z <0.5处〜50 cblas的性质，并限制相关前景星系中冠状气体的冠状气体的程度和物理特性。观察方法将补充CBLA在CGM的数值 - 流动力模拟中产生的合成光谱中的系统研究。来自HST/COS频谱数据和模拟的大型CBLA样品的组合将使我们能够更好地理解由星系的热气晕引起的广泛的Lyman Alpha特征的性质，并探索它们对于观察到限制星系进化模型的重要性。