Connecting Lyα and Ionizing Photon Escape in the Sunburst Arc
Abstract We investigate the Ly α 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 Ly α profile indicating direct Ly α escape. Non-LyC-leaking regions show a redshifted Ly α peak, a redshifted and central Ly α peak, or a triple-peaked Ly α profile. We measure the properties of the Ly α profile from different regions of the galaxy using R ∼ 5000 Magellan/Magellan Echellette spectra. We compare the Ly α spectral properties to LyC and narrowband Ly α maps from Hubble Space Telescope imaging to explore the subgalactic Ly α −LyC connection. We find strong correlations (Pearson correlation coefficient r > 0.6) between the LyC escape fraction ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi>f</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>esc</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>LyC</mml:mi> </mml:mrow> </mml:msubsup> </mml:math> ) and Ly α (1) peak separation v sep , (2) ratio of the minimum flux density between the redshifted and blueshifted Ly α peaks to continuum flux density <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>f</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>min</mml:mi> </mml:mrow> </mml:msub> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:msub> <mml:mrow> <mml:mi>f</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>cont</mml:mi> </mml:mrow> </mml:msub> </mml:math> , and (3) equivalent width. We favor a complex H i geometry to explain the Ly α profiles from non-LyC-leaking regions and suggest two H i geometries that could diffuse and/or rescatter the central Ly α peak from the LyC-leaking region into our sight line across transverse distances of several hundred parsecs. Our results emphasize the complexity of Ly α radiative transfer and its sensitivity to the anisotropies of H i gas on subgalactic scales. Large differences in the physical scales on which we observe spatially variable direct-escape Ly α , blueshifted Ly α , and escaping LyC photons in the Sunburst Arc underscore the importance of resolving the physical scales that govern Ly α and LyC escape.
Authors
- Alexander Navarre (ORCID: https://orcid.org/0000-0001-7548-0473)
- Guillaume Mahler (ORCID: https://orcid.org/0000-0003-3266-2001)
- Keren Sharon (ORCID: https://orcid.org/0000-0002-7559-0864)
- Gourav Khullar (ORCID: https://orcid.org/0000-0002-3475-7648)
- Matthew Bayliss (ORCID: https://orcid.org/0000-0003-1074-4807)
- Michael D. Gladders (ORCID: https://orcid.org/0000-0003-1370-5010)
- Keunho Kim (ORCID: https://orcid.org/0000-0001-6505-0293)
- J. Burns (ORCID: https://orcid.org/0000-0002-4519-7738)
- Håkon Dahle (ORCID: https://orcid.org/0000-0003-2200-5606)
- Brian Welch (ORCID: https://orcid.org/0000-0003-1815-0114)
- T. Emil Rivera-Thorsen (ORCID: https://orcid.org/0000-0002-9204-3256)
- Jane R. Rigby (ORCID: https://orcid.org/0000-0002-7627-6551)
- Taylor A. Hutchison (ORCID: https://orcid.org/0000-0001-6251-4988)
- John Chisholm (ORCID: https://orcid.org/0000-0002-0302-2577)
- M. Riley Owens (ORCID: https://orcid.org/0000-0002-2862-307X)
- Michael Florian (ORCID: https://orcid.org/0000-0001-5097-6755)
- Raven Gassis (ORCID: https://orcid.org/0009-0004-7337-7674)
- P. Adhikari (ORCID: https://orcid.org/0009-0003-3123-4897)
- Christopher M. Malhas (ORCID: https://orcid.org/0009-0000-6300-6184)
- S. Choe (ORCID: https://orcid.org/0000-0003-1343-197X)
Publication Details
- Journal
- The Astrophysical Journal
- Published
- 2024-12-01
- DOI
- https://doi.org/10.3847/1538-4357/ad9247
- Citations
- 4
- Primary Topic
- Gamma-ray bursts and supernovae
- Type
- article
- Field-Weighted Citation Impact
- 1.33
Funders
- Smithsonian Institution
- National Aeronautics and Space Administration
- Space Telescope Science Institute
- Vetenskapsrådet
- Smithsonian Astrophysical Observatory
- Astrophysics Division