2024/10/04 by M. Riley Owens, Keunho Kim, Owens, M. Riley +37
Engineering · Medicine · #Astrophysics of Galaxies (astro-ph.GA) #CCD and CMOS Imaging Sensors #FOS: Physical sciences #Ocular and Laser Science Research #Radiation Therapy and Dosimetry
paper · pdf · doi:10.48550/arxiv.2410.03660
openalex publication_date 2024/10/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We investigate the Lyman-α (Lyα) and Lyman continuum (LyC) properties of the Sunburst Arc, a z=2.37 gravitationally lensed galaxy with a multiply-imaged, compact region leaking LyC and a triple-peaked Lyα profile indicating direct Lyα escape. Non-LyC-leaking regions show a redshifted Lyα peak, a redshifted and central Lyα peak, or a triple-peaked Lyα profile. We measure the properties of the Lyα profile from different regions of the galaxy using R∼5000 Magellan/MagE spectra. We compare the Lyα spectral properties to LyC and narrowband Lyα maps from Hubble Space Telescope (HST) imaging to explore the subgalactic Lyα-LyC connection. We find strong correlations (Pearson correlation coefficient r>0.6) between the LyC escape fraction (f\rm esc\rm LyC) and Lyα (1) peak separation v_\rmsep, (2) ratio of the minimum flux density between the redshifted and blueshifted Lyα peaks to continuum flux density f_\rmmin/f_\rmcont, and (3) equivalent width. We favor a complex \ionH1 geometry to explain the Lyα profiles from non-LyC-leaking regions and suggest two \ionH1 geometries that could diffuse and/or rescatter the central Lyα peak from the LyC-leaking region into our sightline across transverse distances of several hundred parsecs. Our results emphasize the complexity of Lyα radiative transfer and its sensitivity to the anisotropies of \ionH1 gas on subgalactic scales. Large differences in the physical scales on which we observe spatially variable direct escape Lyα, blueshifted Lyα, and escaping LyC photons in the Sunburst Arc underscore the importance of resolving the physical scales that govern Lyα and LyC escape.