17515( 3) - 28-Feb-2025 21:37:06 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17515 Version: 3 Check-in Time: 28-Feb-2025 21:37:06 STScI Edit Number: 0 Title Chasing Lyman Continuum Leakers in the Local Universe ------------------------------------------------------------------------------------ Type Cycle GO 31 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Svea S Hernandez Space Telescope Science Institute - ESA - Y JWST CoI: Dr. Alessandra Aloisi Space Telescope Science Institute N CoI: Dr. Alec S. Hirschauer Morgan State University N CoI: Dr. Matilde Mingozzi Space Telescope Science Institute - ESA - N JWST CoI: Timothy M. Heckman The Johns Hopkins University N CoI: Dr. Bethan Lesley James Space Telescope Science Institute - ESA - N JWST CoI: Dr. Linda J. Smith Space Telescope Science Institute N CoI: Dr. Logan H Jones Space Telescope Science Institute N ------------------------------------------------------------------------------------ Abstract When and how did reionization occur? This will be one of the questions JWST will seek to address in the coming years. The main challenge, however, is the fact that direct measures of the leaking Lyman continuum (LyC) radiation from the same galaxies that reionized the Universe are not possible due to the high opacity of the intergalactic medium (IGM). To fully understand the mechanisms enabling the escape of LyC photons into the IGM, and to uncover the main contributors to the cosmic reionization, it is imperative that we: (1) Test and develop tools to indirectly infer the LyC escape fraction, and (2) compile a sample of nearby LyC leakers allowing us to exploit the ease of fully resolving these objects in the context of LyC escape. We propose a pioneering program to do exactly that. Building on archival observations of eleven local star-forming galaxies (SFGs), we request COS/FUV G130M/1291 spectroscopic data of five additional targets, all of which are expected to have f_esc(LyC)>10% based on cosmological radiation hydrodynamics simulations. Our study will test a much-needed indirect signpost of LyC leakers based primarily on the saturated CII 1334.5A line, allowing us to understand the physical process making LyC leakage possible, and probing the contribution of low-mass SFGs to the epoch of reionization. ------------------------------------------------------------------------------------ Observations Description ------------------------ This HST/COS program observes 5 young star clusters in nearby star-forming galaxies in 5 separate visits with the G130M/1291 COS configuration. Each individual visit acquires the target using the ACQ/IMAGE mode with either MIRROR or MIRRORB. The spectroscopic observations are collected using FP-POS = 3 and 4. These new observations will be complemented by an archival sample of eleven local star-forming galaxies. This sample of 16 nearby star-forming galaxies will allow us to test the much-needed indirect signpost of LyC leakers based primarily on the saturated CII 1334.5A line, allowing us to understand 17515( 3) - 28-Feb-2025 21:37:06 - [ 2] the physical process making LyC leakage possible, and probing the contribution of low-mass SFGs to the epoch of reionization. Target Selection: The new COS sub-sample of star-forming galaxies covers a broad parameter space both in star formation rates, stellar masses, and metallicity. This new COS targets are needed to span the broadest parameter space possible for candidates with the highest probability, P(fesc(LyC)>=10%)> 0.6, to leak Lyman Continuum radiation. The exposure times were calculated assuming the spectrum of a simple stellar population of age 5 or 25 Myr (based on literature values) renormalized to either their WFC3/F275W, or WFC3/F336W magnitudes to reach S/N~10 at 1335 A. The only exception to this approach was VIIZw403. For this target we instead used archival IUE observations to estimate the appropriate exposure times. ------------------------------------------------------------------------------------ 17515( 3) - 28-Feb-2025 21:37:06 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 MRK-209 GALAXY, STAR FORMING RA=12H26M15.7262S +/- 0.1", J2000 V = 14.15 REGION DEC=+48D29'38.41" +/- 0.1" Reference Frame: ICRS Extended: NO Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2015.5 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC-2366 GALAXY, STAR FORMING RA=07H28M42.6702S +/- 0.1", J2000 V = 11.39 REGION DEC=+69D11'21.90" +/- 0.1" Reference Frame: ICRS Extended: NO Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2015.5 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 3 UGC-4483 GALAXY, STAR FORMING RA=08H37M2.9192S +/- 0.1", J2000 V = 14.98 REGION DEC=+69D46'51.03" +/- 0.1" Reference Frame: ICRS Extended: NO Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2015.5 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 4 LEDA-37102 GALAXY, STAR FORMING RA=11H51M33.3575S +/- 0.1", J2000 V = 15.71 REGION DEC=-02D22'22.08" +/- 0.1" Reference Frame: ICRS Extended: NO Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2015.5 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 5 VIIZW403 GALAXY, STAR FORMING RA=11H28M1.3187S +/- 0.1", J2000 V = 13.58 REGION DEC=+78D59'27.92" +/- 0.1" Reference Frame: ICRS Extended: NO ------------------------------------------------------------------------------------------------------------------------------------ 17515( 3) - 28-Feb-2025 21:37:06 - [ 4] Visit: 01 (Mrk-209) Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 MRK-209 COS/NUV ACQ/IMA PSA MIRRORB 1 30 S (30 GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 MRK-209 COS/FUV TIME-TA PSA G130M 1291 FP-POS=3, BUFFER-TIME=3335 1 2600 S G see below (2447 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 MRK-209 COS/FUV TIME-TA PSA G130M 1291 FP-POS=4, BUFFER-TIME=3335 1 618 S G see below (2807 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ MRK-209 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A GE MRK-209 2 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 2447.0 S G MRK-209 3 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 2807.0 S G 17515( 3) - 28-Feb-2025 21:37:06 - [ 5] Visit: 02 (NGC-2366-A) Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC-2366 COS/NUV ACQ/IMA PSA MIRRORA 1 1.4 S (1.4 GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC-2366 COS/FUV TIME-TA PSA G130M 1291 FP-POS=3, BUFFER-TIME=3065 1 618 S G see below (2717 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC-2366 COS/FUV TIME-TA PSA G130M 1291 FP-POS=4, BUFFER-TIME=3065 1 618 S G see below (3021 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NGC-2366 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE NGC-2366 2 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 2717.0 S G NGC-2366 3 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 3021.0 S G 17515( 3) - 28-Feb-2025 21:37:06 - [ 6] Visit: 03 (UGC-4483) Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 UGC-4483 COS/NUV ACQ/IMA PSA MIRRORA 1 2 S (2 S) GE ------------------------------------------------------------------------------------------------------------------------------------ 2 UGC-4483 COS/FUV TIME-TA PSA G130M 1291 FP-POS=3, BUFFER-TIME=3610 1 618 S G see below (2717 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 UGC-4483 COS/FUV TIME-TA PSA G130M 1291 FP-POS=4, BUFFER-TIME=3610 1 618 S G see below (3021 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ UGC-4483 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE UGC-4483 2 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 2717.0 S G UGC-4483 3 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 3021.0 S G 17515( 3) - 28-Feb-2025 21:37:06 - [ 7] Visit: 04 (UM461) Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 LEDA-37102 COS/NUV ACQ/IMA PSA MIRRORB 1 7 S (7 S) GE ------------------------------------------------------------------------------------------------------------------------------------ 2 LEDA-37102 COS/FUV TIME-TA PSA G130M 1291 FP-POS=3, BUFFER-TIME=3468 1 618 S G see below (2298 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 LEDA-37102 COS/FUV TIME-TA PSA G130M 1291 FP-POS=4, BUFFER-TIME=3468 1 618 S G see below (2561 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ LEDA-37102 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A GE LEDA-37102 2 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 2298.0 S G LEDA-37102 3 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 2561.0 S G 17515( 3) - 28-Feb-2025 21:37:06 - [ 8] Visit: 05 (VIIZw403) Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 VIIZW403 COS/NUV ACQ/IMA PSA MIRRORA 1 1.8 S (1.8 GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 VIIZW403 COS/FUV TIME-TA PSA G130M 1291 FP-POS=3, BUFFER-TIME=1294 1 618 S G see below (2744 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 VIIZW403 COS/FUV TIME-TA PSA G130M 1291 FP-POS=4, BUFFER-TIME=1294 1 618 S G see below (3048 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ VIIZW403 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE VIIZW403 2 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 2744.0 S G VIIZW403 3 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 3048.0 S G 17515( 3) - 28-Feb-2025 21:37:06 - [ 9] Summary Form for Proposal 17515 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, COS/NUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/IMAGE, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=1294, BUFFER-TIME=3065, BUFFER-TIME=3335, BUFFER-TIME=3468, BUFFER-TIME=3610, FP-POS=3, FP-POS=4 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G130M, MIRRORA, MIRRORB ------------------------------------------------------------------------------------------------------------------------------------ Target Names LEDA-37102, MRK-209, NGC-2366, UGC-4483, VIIZW403 ------------------------------------------------------------------------------------------------------------------------------------