We quantify the contribution of Ly$α$ fluorescence to observed spatially extended Ly$α$ halos around Ly$α$ emitters (LAE) at redshift ${\rm z=3.1}$. The key physical quantities that describe the fluorescent signal include (${\it i}$) the distribution of cold gas in the circum-galactic medium (CGM); we explore simple analytical models and fitting functions to recent hydrodynamical simulations; (${\it ii}$) local variations in the ionizing background due to ionizing sources that cluster around the central galaxy. We account for clustering by boosting the observationally inferred volumetric production rate of ionizing photons, $ε_{\rm LyC}$, by a factor of $1+ξ_{\rm LyC}(r)$, in which $ξ_{\rm LyC}(r)$ quantifies the clustering of ionizing sources around the central galaxy. We compute $ξ_{\rm LyC}(r)$ by assigning an 'effective' bias parameter to the ionizing sources. This novel approach allows us to quantify our ignorance of the population of ionizing sources in a simple parametrized form. We find a maximum enhancement in the local ionizing background in the range $50-200$ at $r \sim 10$ physical kpc. For spatially uncorrelated ionizing sources and fluorescing clouds we find that fluorescence can contribute up to $\sim 50-60\%$ of the observed spatially extended Ly$α$ emission. We briefly discuss how future observations can shed light on the nature of Ly$α$ halos around star forming galaxies.
The Lyman-alpha and Continuum Origins Survey II: the connection between the escape of ionizing radiation and Lyman-alpha halos in star-forming galaxies
Stockholm University（斯德哥尔摩大学）；University of Minnesota（明尼苏达大学）；Johns Hopkins University（约翰斯·霍普金斯大学）；Space Telescope Science Institute（太空望远镜科学研究所）；CNRS, Centre de Recherche Astrophysique de Lyon UMR5574, Univ Lyon, Ens de Lyon（法国国家科学研究中心，里昂天体物理研究中心UMR5574，里昂大学，里昂高等师范学校）；Observatoire de Genève, Université de Genève（日内瓦天文台，日内瓦大学）
The AURORA Survey: Determining the Production Mechanism for OI $\mathbf{λ8449}$ Emission in Star-forming Galaxies at Cosmic Noon
University of California, Los Angeles（加州大学洛杉矶分校）；Shanghai Jiao Tong University（上海交通大学）；University of Kentucky（肯塔基大学）；University of California, Riverside（加州大学河滨分校）；University of California, Davis（加州大学戴维斯分校）；University of Chicago（芝加哥大学）；Kavli Institute for Cosmological Physics, University of Chicago（卡弗里宇宙物理学研究所，芝加哥大学）
