The Importance Of Star Formation Intensity In LYα Escape From Green Pea Galaxies And Lyman Break Galaxy Analogs

Abstract

We have studied ultraviolet images of 40 Green Pea galaxies and 15 local Lyman Break Galaxy Analogs to understand the relation between Ly$\alpha$ photon escape and central UV photometric properties. We measured star formation intensity (SFI, star formation rate per unit area) from the central 250 pc region ($S_{250pc}$) using COS/NUV images from the \textit{Hubble Space Telescope}. The measured $S_{250pc}$ of our sample Green Peas ranges from 2.3--46 $M_{\odot }{\mathrm{year}}^{-1}\mathrm{kp}{\mathrm{c}}^{-2}$, with a geometric mean of $15M_{\odot }{\mathrm{year}}^{-1}\mathrm{kp}{\mathrm{c}}^{-2}$ and a standard deviation of 0.266 dex, forming a relatively narrow distribution. The Lyman Break Galaxy Analogs show a similarly narrow distribution of $S_{250pc}$ (0.271 dex), though with a larger mean of 28 $M_{\odot }{\mathrm{year}}^{-1}\mathrm{kp}{\mathrm{c}}^{-2}$. We show that while the Ly$\alpha$ equivalent width (EW(Ly$\alpha$)) and the Ly$\alpha$ escape fraction ($f_{esc}^{Ly\alpha }$) are not significantly correlated with the central SFI ($S_{250pc}$), both are positively correlated with the ratio of surface brightness to galaxy stellar mass ($S_{250pc}/M_{\mathrm{star}}$), with correlation coefficients ($p$-values) of 0.702 ($1\times 10^{-8}$) and 0.529 ($5\times 10^{-4}$) with EW(Ly$\alpha$) and $f_{esc}^{Ly\alpha }$, respectively. These correlations suggest a scenario where intense central star formation can drive a galactic wind in galaxies with relatively shallow gravitational potential wells, thus clearing channels for the escape of Ly$\alpha$ photons.

8 pages, 3 figures, 2 tables. Accepted for publication in ApJ

References in corpus (4)

• 3D Lyman-alpha radiation transfer. I. Understanding Lyman-alpha line profile morphologies
• Using Lyman-alpha to detect galaxies that leak Lyman continuum
• Lyman-alpha spectral properties of five newly discovered Lyman continuum emitters
• The HETDEX Pilot Survey V: The Physical Origin of Lyman-alpha Emitters Probed by Near-infrared Spectroscopy

Cited by in corpus (15)

• Lyman continuum leakage from low-mass galaxies with Mstar < 1.E8 Msun
• Finding Peas in the Early Universe with JWST
• The Effects of Stellar Population and Gas Covering Fraction on the Emergent Lyman Alpha Emission of High-Redshift Galaxies
• The Low-redshift Lyman-continuum Survey: [S II]-deficiency and the leakage of ionizing radiation
• Ubiquitous broad-line emission and the relation between ionized gas outflows and Lyman continuum escape in Green Pea galaxies
• The connection between galactic outflows and the escape of ionizing photons
• The Compact UV Size of Green Pea Galaxies As Local Analogs of High-redshift Ly$\alpha$-Emitters
• Physical Properties of Massive Compact Starburst Galaxies with Extreme Outflows
• Lyman-Alpha Escape from Low-Mass, Compact, High-Redshift Galaxies
• X-ray emission from star cluster winds in starburst galaxies
• Resolving the Ultra-Luminous X-ray Sources in the Ly$\alpha$ Emitting Galaxy Haro 11
• A MUSE/VLT spatially resolved study of the emission structure of Green Pea galaxies
• Ionizing Radiation Escape from Low-Redshift Galaxies and Its Connection to Cosmic Reionization
• The Role of Dust, UV Luminosity and Large-scale Environment on the Escape of Lya Photons: A Case Study of a Protocluster field at z = 3.1
• Lyman Continuum escaping from in-situ formed stars in a tidal bridge at z = 3