Neutral ISM, Lyman-Alpha and Lyman-continuum in the nearby starburst Haro 11

Abstract

Star forming galaxies are believed to be a major source of Lyman Continuum (LyC) radiation responsible for reionizing the early Universe. Direct observations of escaping ionizing radiation have however been few and with low escape fractions. In the local Universe, only ~10 emitters have been observed, with typical escape fractions of a few percent. The mechanisms regulating this escape need to be strongly evolving with redshift in order to account for the Epoch of Reionization. Gas content and star formation feedback are among the main suspects, known to both regulate neutral gas coverage and evolve with cosmic time. In this paper, we reanalyze HST-COS spectrocopy of the first detected local LyC leaker, Haro 11. We examine the connection between LyC leakage and Lyman-$\alpha$ line shape, and feedback-influenced neutral ISM properties like kinematics and gas distribution. We discuss the two extremes of an optically thin, density bounded ISM and a riddled, optically thick, ionization bounded ISM, and how Haro 11 fits into their theoretical predictions. We find that the most likely ISM model is a clumpy neutral medium embedded in a highly ionized medium with a combined covering fraction of unity and a residual neutral gas column density in the ionized medium high enough to be optically thick to Lyman-$\alpha$, but low enough to be at least partly transparent to Lyman continuum and undetected in Si II. This suggests that SF feedback and galaxy-scale interaction events play a major role in opening passageways for ionizing radiation through the neutral medium.

11 pages, 9 figures, 1 table. Accepted for publication in The Astrophysical Journal

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• Detection of the Missing Baryons toward the Sightline of H1821+643
• Lyman-alpha spectroscopy of extreme [OIII] emitting galaxies at $z\simeq 2-3$: Implications for Ly$\alpha$ visibility and LyC leakage at $z>6$
• Spectral shapes of the Lyman-alpha emission from galaxies: I. blueshifted emission and intrinsic invariance with redshift
• The impact of Stellar feedback from velocity-dependent ionised gas maps. -- A MUSE view of Haro 11
• Catastrophic Cooling in Superwinds: Line Emission and Non-equilibrium Ionization
• Mapping the Escape Fraction of Ionizing Photons Using Resolved Stars: A Much Higher Escape Fraction for NGC 4214
• Early Results from GLASS-JWST XXII: Rest frame UV-optical spectral properties of Lyman-alpha emitting galaxies at 3 $<$ z $<$ 6
• The source of leaking ionizing photons from Haro11 -- Clues from HST/COS spectroscopy of knots A, B and C
• Haro 11 -- Untying the knots of the nuclear starburst
• Ionized gas properties of the extreme starburst galaxy Haro 11. Temperature and metal abundance discrepancies
• Resolving the Ultra-Luminous X-ray Sources in the Ly$\alpha$ Emitting Galaxy Haro 11
• Spatially resolved CIII]$\lambda$1909 emission in Haro 11
• Ionizing Radiation Escape from Low-Redshift Galaxies and Its Connection to Cosmic Reionization
• Disentangling the X-ray variability in the Lyman continuum emitter Haro 11
• Forming the local starburst galaxy Haro 11 through hydrodynamical merger simulations