Witnessing an extreme, highly efficient galaxy formation mode with resolved Ly$\alpha$ and LyC emission
Abstract
J1316+2614 at z=3.613 is the UV-brightest ( = -24.7) and strongest Lyman continuum (LyC, 90%) emitting star-forming galaxy known, showing also signatures of inflowing gas from its blue-dominated Ly profile. Here, we present high-resolution imaging with the HST and VLT of the LyC, Ly, rest-UV, and optical emission of J1316+2614. Detailed analysis of the LyC and UV light distributions reveals compact yet resolved profiles, with LyC and UV morphologies showing identical half-light radii of 220 pc. The continuum-subtracted Ly emission reveals an extended filamentary structure of 6.0 kpc oriented south-north with only weak/residual flux within the stellar core, suggesting a Ly "hole". J1316+2614 presents remarkably high SFR and stellar mass surface densities of log( [/yr/kpc^2]) = 3.470.11 and log( [/pc^2]) = 4.200.06, respectively, which are among the highest observed in star-forming galaxies. Our findings indicate that J1316+2614 is a powerful, young, and compact starburst, leaking significant LyC photons due to the lack of gas and dust within the starburst. We explore the conditions for gas expulsion using a simple energetic balance and find that, given the strong binding force in J1316+2614, a high star formation efficiency () is necessary to remove the gas and explain its exposed nature. Our results thus suggest a close link between high and high . This high efficiency can also naturally explain the remarkably high SFR, UV-luminosity, and efficient mass growth of J1316+2614, where at least 62% of its mass formed in the last 6 Myr. J1316+2614 may exemplify an intense, feedback-free starburst with a high , similar to those proposed for UV-bright galaxies at high redshifts. (ABRIDGED)
Keywords
Cite
@article{arxiv.2407.18804,
title = {Witnessing an extreme, highly efficient galaxy formation mode with resolved Ly$\alpha$ and LyC emission},
author = {R. Marques-Chaves and D. Schaerer and E. Vanzella and A. Verhamme and M. Dessauges-Zavadsky and J. Chisholm and F. Leclercq and A. Upadhyaya and J. Alvarez-Marquez and L. Colina and T. Garel and M. Messa},
journal= {arXiv preprint arXiv:2407.18804},
year = {2024}
}
Comments
15 pages and 9 figures. Accepted for publication in A&A