Toward a Statistical Sample of Sunburst Arcs: Revealing the smallest and most extreme star-forming clumps in the 2<z<4 universe with Roman and gravitational lensing
| Program ID | 19070 |
|---|---|
| Science Category | Galaxies |
| Program Type | Analysis |
| Category | Medium |
| Principal Investigator | Michael Florian |
| PI Institution | Eureka Scientific |
| Co-Investigators |
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| Abstract | One of the major questions of astronomy over the last decade has been what kinds of objects reionized the neutral hydrogen in the intergalactic medium at z~6-14. Recent work has pointed toward low mass star-forming galaxies (SFGs) as the culprits, but there is no smoking gun as the mechanisms of ionizing photon production in and escape from those galaxies are still unclear. For several physical and technological reasons, ionizing photon (or Lyman continuum, LyC) emission cannot be directly observed and localized at subgalactic scales except in gravitationally lensed galaxies at 2<z<4. Only one highly magnified arc with LyC emission has been published to date: the Sunburst Arc. Extensive studies of it show its LyC leakage is dominated by a single clump ≤32pc in size. Knowing whether this is typical of LyC leakers requires a statistical sample of lensed leakers. Both lensed arcs and LyC leakers are rare, so finding such objects requires a large survey, and since LyC leakage is known to occur at such small scales, that survey must have high angular resolution. Only the Roman High Latitude Wide Area Survey can provide both. We will use photometric and spectroscopic indicators of LyC escape at the clump level to identify the highest likelihood lensed LyC leaker candidates. Only Hubble can directly confirm and localize LyC escape, but it requires 20-30 orbits for a single target, necessitating a systematic pre-screening using Roman data, and also adding a sense of urgency as HST is approaching its end of life. As part of our search for lensed LyC leakers, we will more than double the number of lensed arcs with spectroscopic redshifts, identify the most extreme clumps in the 2<z<4 universe in UV slope and the ionization-sensitive spectroscopic diagnostic O32, measure the sizes of these extreme regions, and provide cluster masses of all lensing clusters and detailed lens models of those lensing the highest likelihood LyC leaker candidates. |