English

Connecting Lyman-$\alpha$ and ionizing photon escape in the Sunburst Arc

Astrophysics of Galaxies 2024-10-07 v1

Abstract

We investigate the Lyman-α\alpha (Lyα\alpha) and Lyman continuum (LyC) properties of the Sunburst Arc, a z=2.37z=2.37 gravitationally lensed galaxy with a multiply-imaged, compact region leaking LyC and a triple-peaked Lyα\alpha profile indicating direct Lyα\alpha escape. Non-LyC-leaking regions show a redshifted Lyα\alpha peak, a redshifted and central Lyα\alpha peak, or a triple-peaked Lyα\alpha profile. We measure the properties of the Lyα\alpha profile from different regions of the galaxy using R5000R\sim5000 Magellan/MagE spectra. We compare the Lyα\alpha spectral properties to LyC and narrowband Lyα\alpha maps from Hubble Space Telescope (HST) imaging to explore the subgalactic Lyα\alpha-LyC connection. We find strong correlations (Pearson correlation coefficient r>0.6r>0.6) between the LyC escape fraction (fescLyCf_{\rm esc}^{\rm LyC}) and Lyα\alpha (1) peak separation vsepv_{\rm{sep}}, (2) ratio of the minimum flux density between the redshifted and blueshifted Lyα\alpha peaks to continuum flux density fmin/fcontf_{\rm{min}}/f_{\rm{cont}}, and (3) equivalent width. We favor a complex \ion{H}{1} geometry to explain the Lyα\alpha profiles from non-LyC-leaking regions and suggest two \ion{H}{1} geometries that could diffuse and/or rescatter the central Lyα\alpha peak from the LyC-leaking region into our sightline across transverse distances of several hundred parsecs. Our results emphasize the complexity of Lyα\alpha radiative transfer and its sensitivity to the anisotropies of \ion{H}{1} gas on subgalactic scales. Large differences in the physical scales on which we observe spatially variable direct escape Lyα\alpha, blueshifted Lyα\alpha, and escaping LyC photons in the Sunburst Arc underscore the importance of resolving the physical scales that govern Lyα\alpha and LyC escape.

Keywords

Cite

@article{arxiv.2410.03660,
  title  = {Connecting Lyman-$\alpha$ and ionizing photon escape in the Sunburst Arc},
  author = {M. Riley Owens and Keunho J. Kim and Matthew B. Bayliss and T. Emil Rivera-Thorsen and Keren Sharon and Jane R. Rigby and Alexander Navarre and Michael Florian and Michael D. Gladders and Jessica G. Burns and Gourav Khullar and John Chisholm and Guillaume Mahler and Hakon Dahle and Christopher M. Malhas and Brian Welch and Taylor A. Hutchison and Raven Gassis and Suhyeon Choe and Prasanna Adhikari},
  journal= {arXiv preprint arXiv:2410.03660},
  year   = {2024}
}

Comments

Submitted to The Astrophysical Journal with revisions from the first referee report. Comments welcome