Power-law Emission-line Wings and Radiation-Driven Superwinds in Local Lyman Continuum Emitters

Abstract

We investigate broad emission-line wings, reaching $\le 800\mathrm{km}{\mathrm{s}}^{-1}$, observed in 26 galaxies with Lyman continuum (LyC) observations, primarily from the Low-redshift Lyman Continuum Survey (LzLCS). Using Magellan/MIKE, VLT/X-shooter, and WHT/ISIS high-resolution spectroscopy, we show that this fast gas appears to probe the dominant feedback mechanisms linked to LyC escape. We find that in 14 galaxies, the wings are best fit with power laws of slope $\alpha \sim -3.5\text{ to }-1.6$, with four others best fit by Gaussians of width ${\sigma }_{\mathrm{BW}}\sim 300\mathrm{km}{\mathrm{s}}^{-1}$; the remaining eight show ambiguous wing morphologies. Gaussian wings are found only at low $O_{32}$ = $[\mathrm{O}\mathrm{III}]\lambda 5007/[\mathrm{O}\mathrm{II}]\lambda 3726,3729$ and high metallicity, while power-law wings span the full range of these parameters. The general evidence suggests a dual-mode paradigm for LyC escape: radiation-driven superwinds traced by power-law wings and supernova-driven feedback traced by Gaussian wings. For the former, the $<3$ Myr-old, pre-supernova stellar population correlates with more luminous, faster winds. The data also show that radiation-driven wind parameters like wind luminosity and power-law slope $\alpha$ depend on the UV luminosity more than the optically thick covering fraction, consistent with ``picket-fence" radiative transfer. Observed $\alpha$ values flatten with both escaping LyC luminosity and higher extinction, while still preserving the anticorrelation between these two quantities. Additionally, the differential between red and blue slopes implies that extinction and dense gas are centrally concentrated relative to the wind emission. Overall, our results show that power-law emission-line wings probe LyC-driven winds and LyC escape in metal-poor starbursts.

39 pages, 21 figures. Accepted for publication in ApJ

References in corpus (53)

• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• Cosmic Reionization and Early Star-Forming Galaxies: A Joint Analysis of New Constraints from Planck and Hubble Space Telescope
• The Effects of Stellar Rotation. II. A Comprehensive Set of Starburst99 Models
• Escape fraction of ionizing photons during reionization: effects due to supernova feedback and runaway OB stars
• Conditions for Reionizing the Universe with A Low Galaxy Ionizing Photon Escape Fraction
• Efficient Formation of Massive Galaxies at Cosmic Dawn by Feedback-Free Starbursts
• The chemical enrichment in the early Universe as probed by JWST via direct metallicity measurements at z~8
• Fallback and Black Hole Production in Massive Stars
• On the stunning abundance of super-early, massive galaxies revealed by JWST
• Dynamics of Dusty Radiation Pressure Driven Shells and Clouds: Fast Outflows from Galaxies, Star Clusters, Massive Stars, and AGN
• The Low-Redshift Lyman Continuum Survey I: New, Diverse Local Lyman-Continuum Emitters
• First look with JWST spectroscopy: $z\sim 8$ galaxies resemble local analogues
• The Low-Redshift Lyman Continuum Survey II: New Insights into LyC Diagnostics
• EIGER II. first spectroscopic characterisation of the young stars and ionised gas associated with strong H$\beta$ and [OIII] line-emission in galaxies at z=5-7 with JWST
• Most of the photons that reionized the Universe came from dwarf galaxies
• A First Look at the Abundance Pattern -- O/H, C/O, and Ne/O -- in $z>7$ Galaxies with JWST/NIRSpec
• Testing massive star evolution, star-formation history and feedback at low metallicity : Spectroscopic analysis of OB stars in the SMC Wing
• The origin of the escape of Lyman alpha and ionizing photons in Lyman Continuum Emitters
• The Low-Redshift Lyman Continuum Survey. Unveiling the ISM properties of low-$z$ Lyman continuum emitters
• Feedback-Free Starbursts at Cosmic Dawn: Observable Predictions for JWST
• Finding Peas in the Early Universe with JWST
• Closing in on the sources of cosmic reionization: first results from the GLASS-JWST program
• JADES: The incidence rate and properties of galactic outflows in low-mass galaxies across 3 < z < 9
• The THESAN project: ionizing escape fractions of reionization-era galaxies
• Blue Monsters. Why are JWST super-early, massive galaxies so blue?
• (Re)Solving Reionization with Lyα: How Bright Lyα Emitters account for the $z\approx 2-8$ Cosmic Ionizing Background
• Kinematics and Optical Depth in the Green Peas: Suppressed Superwinds in Candidate LyC Emitters
• Nitrogen-enriched, highly-pressurized nebular clouds surrounding a super star cluster at cosmic noon
• The Lyman Continuum Escape Survey: Connecting Time-Dependent [OIII] and [OII] Line Emission with Lyman Continuum Escape Fraction in Simulations of Galaxy Formation
• The HII Galaxy Hubble Diagram Strongly Favors $R_{\mathrm{h}}=ct$ over $\Lambda$CDM
• Dense CO in Mrk 71-A: Superwind Suppressed in a Young Super Star Cluster
• Chemodynamics of Green Pea galaxies -- I. Outflows and turbulence driving the escape of ionising photons and chemical enrichment
• Ubiquitous broad-line emission and the relation between ionized gas outflows and Lyman continuum escape in Green Pea galaxies
• Catastrophic Cooling in Superwinds: Line Emission and Non-equilibrium Ionization
• The connection between galactic outflows and the escape of ionizing photons
• A Preview of JWST Metallicity Studies at Cosmic Noon: The First Detection of Auroral [O II] Emission at High Redshift
• Stellar wind properties of the nearly complete sample of O stars in the low metallicity young star cluster NGC346 in the SMC galaxy
• The Extreme Low-mass End of the Mass-Metallicity Relation at $z\sim 7$
• Properties of five z~0.3-0.4 confirmed LyC leakers: VLT/XShooter observations
• Feedback and ionized gas outflows in four low-radio power AGN at z $\sim$0.15
• The source of leaking ionizing photons from Haro11 -- Clues from HST/COS spectroscopy of knots A, B and C
• Physical properties of extreme emission-line galaxies at $z\sim 4-9$ from the JWST CEERS survey
• The Effect of Bi-conical Outflows on Ly$\alpha$ Escape From Green Peas
• The density-bounded twilight of starbursts in the early Universe
• New insights on the nebular emission, ionizing radiation and low metallicity of Green Peas from advanced modelling
• Early results from GLASS-JWST. XXVII. The mass-metallicity relation in lensed field galaxies at cosmic noon with NIRISS
• No correlation of the Lyman continuum escape fraction with spectral hardness
• Lyman-alpha radiation pressure: an analytical exploration
• Witnessing an extreme, highly efficient galaxy formation mode with resolved Ly$\alpha$ and LyC emission
• Low-redshift Lyman Continuum Survey: Radio continuum properties of low-$z$ Lyman continuum emitters
• Feedback and dynamical masses in high-$z$ galaxies: the advent of high-resolution NIRSpec spectroscopy
• Nebular C IV 1550 Imaging of the Metal-Poor Starburst Mrk 71: Direct Evidence of Catastrophic Cooling
• The Lyman-alpha and Continuum Origins Survey. I. Survey description and Ly$\alpha$ imaging