Two modes of LyC escape from bursty star formation: implications for [C II] deficits and the sources of reionization
<p>We use the SPHINX<sup>20</sup> cosmological radiation hydrodynamics simulation to study how Lyman continuum (LyC) photons escape from galaxies and the observational signatures of this escape. We define two classes of LyC leaker: Bursty Leakers and Remnant Leakers, based on their...
| Main Authors: | , , , , , , , , , , , |
|---|---|
| Format: | Journal article |
| Language: | English |
| Published: |
Oxford University Press
2022
|
| _version_ | 1797109397070020608 |
|---|---|
| author | Katz, H Saxena, A Rosdahl, J Kimm, T Blaizot, J Garel, T Michel-Dansac, L Haehnelt, M Ellis, RS Penterrici, L Devriendt, J Slyz, A |
| author_facet | Katz, H Saxena, A Rosdahl, J Kimm, T Blaizot, J Garel, T Michel-Dansac, L Haehnelt, M Ellis, RS Penterrici, L Devriendt, J Slyz, A |
| author_sort | Katz, H |
| collection | OXFORD |
| description | <p>We use the SPHINX<sup>20</sup> cosmological radiation hydrodynamics simulation to study how Lyman continuum (LyC) photons escape from galaxies and the observational signatures of this escape. We define two classes of LyC leaker: Bursty Leakers and Remnant Leakers, based on their star formation rates (SFRs) that are averaged over 10 Myr (SFR<sub>10</sub>) or 100 Myr (SFR<sub>100</sub>). Both have <em>f</em><sub>esc</sub>>20 per cent and experienced an extreme burst of star formation, but Bursty Leakers have SFR<sub>10</sub> > SFR<sub>100</sub>, while Remnant Leakers have SFR<sub>10</sub> < SFR<sub>100</sub>. The maximum SFRs in these bursts were typically ∼100 times greater than the SFR of the galaxy prior to the burst, a rare 2σ outlier among the general high-redshift galaxy population. Bursty Leakers are qualitatively similar to ionization-bounded nebulae with holes, exhibiting high ionization parameters and typical H II region gas densities. Remnant Leakers show properties of density-bounded nebulae, having normal ionization parameters but much lower H II region densities. Both types of leaker exhibit [C II]<sub>158μm</sub> deficits on the [C II]–SFR<sub>100</sub> relation, while only Bursty Leakers show deficits when <sub>10</sub> is used. We predict that [C II] luminosity and SFR indicators such as Hα and M<sub>1500Å</sub> can be combined to identify both types of LyC leaker and the mode by which photons are escaping. These predictions can be tested with [C II] observations of known z = 3–4 LyC leakers. Finally, we show that leakers with <em>f</em><sub>esc</sub>>20 per cent dominate the ionizing photon budget at z ≳ 7.5 but the contribution from galaxies with <em>f</em><sub>esc</sub><5 per cent becomes significant at the tail-end of reionization.</p> |
| first_indexed | 2024-03-07T07:41:21Z |
| format | Journal article |
| id | oxford-uuid:b08909dc-e24f-4959-bd12-b494b52f14a4 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T07:41:21Z |
| publishDate | 2022 |
| publisher | Oxford University Press |
| record_format | dspace |
| spelling | oxford-uuid:b08909dc-e24f-4959-bd12-b494b52f14a42023-04-20T10:04:03ZTwo modes of LyC escape from bursty star formation: implications for [C II] deficits and the sources of reionization Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:b08909dc-e24f-4959-bd12-b494b52f14a4EnglishSymplectic ElementsOxford University Press2022Katz, HSaxena, ARosdahl, JKimm, TBlaizot, JGarel, TMichel-Dansac, LHaehnelt, MEllis, RSPenterrici, LDevriendt, JSlyz, A<p>We use the SPHINX<sup>20</sup> cosmological radiation hydrodynamics simulation to study how Lyman continuum (LyC) photons escape from galaxies and the observational signatures of this escape. We define two classes of LyC leaker: Bursty Leakers and Remnant Leakers, based on their star formation rates (SFRs) that are averaged over 10 Myr (SFR<sub>10</sub>) or 100 Myr (SFR<sub>100</sub>). Both have <em>f</em><sub>esc</sub>>20 per cent and experienced an extreme burst of star formation, but Bursty Leakers have SFR<sub>10</sub> > SFR<sub>100</sub>, while Remnant Leakers have SFR<sub>10</sub> < SFR<sub>100</sub>. The maximum SFRs in these bursts were typically ∼100 times greater than the SFR of the galaxy prior to the burst, a rare 2σ outlier among the general high-redshift galaxy population. Bursty Leakers are qualitatively similar to ionization-bounded nebulae with holes, exhibiting high ionization parameters and typical H II region gas densities. Remnant Leakers show properties of density-bounded nebulae, having normal ionization parameters but much lower H II region densities. Both types of leaker exhibit [C II]<sub>158μm</sub> deficits on the [C II]–SFR<sub>100</sub> relation, while only Bursty Leakers show deficits when <sub>10</sub> is used. We predict that [C II] luminosity and SFR indicators such as Hα and M<sub>1500Å</sub> can be combined to identify both types of LyC leaker and the mode by which photons are escaping. These predictions can be tested with [C II] observations of known z = 3–4 LyC leakers. Finally, we show that leakers with <em>f</em><sub>esc</sub>>20 per cent dominate the ionizing photon budget at z ≳ 7.5 but the contribution from galaxies with <em>f</em><sub>esc</sub><5 per cent becomes significant at the tail-end of reionization.</p> |
| spellingShingle | Katz, H Saxena, A Rosdahl, J Kimm, T Blaizot, J Garel, T Michel-Dansac, L Haehnelt, M Ellis, RS Penterrici, L Devriendt, J Slyz, A Two modes of LyC escape from bursty star formation: implications for [C II] deficits and the sources of reionization |
| title | Two modes of LyC escape from bursty star formation: implications for [C II] deficits and the sources of reionization |
| title_full | Two modes of LyC escape from bursty star formation: implications for [C II] deficits and the sources of reionization |
| title_fullStr | Two modes of LyC escape from bursty star formation: implications for [C II] deficits and the sources of reionization |
| title_full_unstemmed | Two modes of LyC escape from bursty star formation: implications for [C II] deficits and the sources of reionization |
| title_short | Two modes of LyC escape from bursty star formation: implications for [C II] deficits and the sources of reionization |
| title_sort | two modes of lyc escape from bursty star formation implications for c ii deficits and the sources of reionization |
| work_keys_str_mv | AT katzh twomodesoflycescapefromburstystarformationimplicationsforciideficitsandthesourcesofreionization AT saxenaa twomodesoflycescapefromburstystarformationimplicationsforciideficitsandthesourcesofreionization AT rosdahlj twomodesoflycescapefromburstystarformationimplicationsforciideficitsandthesourcesofreionization AT kimmt twomodesoflycescapefromburstystarformationimplicationsforciideficitsandthesourcesofreionization AT blaizotj twomodesoflycescapefromburstystarformationimplicationsforciideficitsandthesourcesofreionization AT garelt twomodesoflycescapefromburstystarformationimplicationsforciideficitsandthesourcesofreionization AT micheldansacl twomodesoflycescapefromburstystarformationimplicationsforciideficitsandthesourcesofreionization AT haehneltm twomodesoflycescapefromburstystarformationimplicationsforciideficitsandthesourcesofreionization AT ellisrs twomodesoflycescapefromburstystarformationimplicationsforciideficitsandthesourcesofreionization AT penterricil twomodesoflycescapefromburstystarformationimplicationsforciideficitsandthesourcesofreionization AT devriendtj twomodesoflycescapefromburstystarformationimplicationsforciideficitsandthesourcesofreionization AT slyza twomodesoflycescapefromburstystarformationimplicationsforciideficitsandthesourcesofreionization |