17452( 3) - 01-Jul-2024 19:51:40 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17452 Version: 3 Check-in Time: 01-Jul-2024 19:51:40 STScI Edit Number: 1 Title Lyman-alpha emission in low-mass compact galaxies with most extreme [OIII]5007/[OII]3727 ratios of above 30 ------------------------------------------------------------------------------------ Type Cycle GO 31 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Yuri I. Izotov Ukrainian National Academy of Sciences, Y BITP CoI: Dr. Natalia G. Guseva Ukrainian National Academy of Sciences, N BITP CoI: Prof. Daniel Schaerer University of Geneva, Department of N Astronomy CoI: Dr. Gabor Worseck Private Company N CoI: Prof. Trinh Xuan Thuan The University of Virginia N CoI: Prof. Anne Verhamme University of Geneva, Department of N Astronomy ------------------------------------------------------------------------------------ Abstract Compact and low-mass star-forming galaxies (SFGs) at low redshifts are considered to be the likely nearby counterparts of the high-z star-forming dwarf galaxies thought to be responsible for the reionization of the Universe. We propose to observe with the HST/COS a sample of the five compact SFGs with the highest O32 = [OIII] 5007/[OII] 3727 ratio of 30 - 69 known in the local universe, to obtain medium-resolution spectra of the Ly-alpha emission line. These SFGs were selected from the Data Release 16 of the Sloan Digital Sky Survey to be very compact and to have very young starbursts (EW(Hbeta)>250A). Two SFGs are characterized by the extremely high [OIII]5007/[OII]3727 emission-line ratios of 57 and 69, indicating extreme ionization conditions in their HII regions. The Ly-alpha profiles in those medium resolution spectra will be used to indirectly estimate the escape fraction of the Lyman continuum and will provide important insight on the ISM and radiation field of the star-forming regions. Obtaining the rest-UV spectra of these five SFGs which will serve as templates for the analysis of spectra of high-z dwarf galaxies with active star formation, is thus both urgent and crucial for studies with the JWST and the largest ground-based facilities. ------------------------------------------------------------------------------------ Observations Description ------------------------ The galaxies are faint and satisfy safety conditions for observing with the COS. Furthermore, there are no sources brighter than the COS safety limits in circular regions with the diameter of 43 arcsec centered on the selected galaxies. NUV acquisition images of the targets will be obtained with thestandard Mirror A and the ACQ/IMAGE mode to reach a S/N20 inside a 9x9 pixel box centered on the brightest part of the galaxy. The adopted GALEX NUV magnitudes were used to estimate exposure times. The angular galaxy radius is chosen to be 0.2", inside which most of the galaxy light is concentrated. The total time for acquisition is up to 120s+2x400s=920s per object (HST Primer manual), or third of orbit. As a bonus, the UV morphology of the selected 17452( 3) - 01-Jul-2024 19:51:40 - [ 2] objects will be studied with these images including the low-brightness component of the galaxy. For medium-resolution spectroscopy, the COS in combination with the G130M grating will be used to observe the Ly-alpha line. This resolution is required to resolve the Ly-alpha line profile and to measure features such as the velocity separations between different emission peaks which give the best estimate of the LyC escape fraction. The Ly-alpha emission-line profiles in the spectra of the proposed galaxies will be compared to those in LyC leaking galaxies and in Green Pea galaxies. The GALEX FUV magnitude is used to calculate for each object the required number of orbits to obtain a S/N > 5 for the continuum near Ly-alpha line, in the case of a 100-pixel binned spectrum. This S/N would be enough to obtain the Ly-alpha profile with a sufficient accuracy for radiative transfer modeling and for deriving velocity separations between the peaks. For each target, 0.3 orbit for acquisition, and 3.7 or 4.7 orbits for the spectrum with the medium-resolution G130M grating are needed, totalling 4 or 5 orbits per object. A total of 22 orbits for 5 objects is requested. We do not expect the large impact of reduced-gyro operations on our program because we do not request special orientation requirement for observing of our targets. ------------------------------------------------------------------------------------ 17452( 3) - 01-Jul-2024 19:51:40 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 J0827+3429 GALAXY, DWARF COMPACT, RA=08H27M1.9700S +/- 0.2", J2000 Z = V = 21.52 +/- 0.05 FUV=22.30+/-0.30, EMISSION LINE NEBULA, DEC=+34D29'51.80" +/- 0.2" 0.0856 NUV=22.59+/-0.43 STARBURST Reference Frame: ICRS Extended: NO ------------------------------------------------------------------------------------------------------------------------------------ 2 J1046+4047 GALAXY, DWARF COMPACT, RA=10H46M9.2300S +/- 0.2", J2000 Z = V = 20.18 +/- 0.02 FUV=20.27+/-0.24, EMISSION LINE NEBULA, DEC=+40D47'7.07" +/- 0.2" 0.0487 NUV=21.19+/-0.28 STARBURST Reference Frame: ICRS Extended: NO ------------------------------------------------------------------------------------------------------------------------------------ 3 J1300+3625 GALAXY, DWARF COMPACT, RA=13H00M37.7900S +/- 0.2", J2000 Z = V = 19.68 +/- 0.01 FUV=20.50+/-0.10, EMISSION LINE NEBULA, DEC=+36D25'51.27" +/- 0.2" 0.0232 NUV=20.69+/-0.06 STARBURST Reference Frame: ICRS Extended: NO ------------------------------------------------------------------------------------------------------------------------------------ 4 J1416+4645 GALAXY, DWARF COMPACT, RA=14H16M8.3500S +/- 0.2", J2000 Z = V = 19.17 +/- 0.01 FUV=20.49+/-0.10, EMISSION LINE NEBULA, DEC=+46D45'13.36" +/- 0.2" 0.0382 NUV=20.61+/-0.15 (No data in Galex STARBURST database. FUV and NUV magnitudes are estimated from the modeled spectral energy distribution) Reference Frame: ICRS Extended: NO ------------------------------------------------------------------------------------------------------------------------------------ 5 J1444+4840 GALAXY, DWARF COMPACT, RA=14H44M59.0100S +/- 0.2", J2000 Z = V = 20.71 +/- 0.03 FUV=22.01+/-0.41, EMISSION LINE NEBULA, DEC=+48D40'6.83" +/- 0.2" 0.0647 NUV=22.18+/-0.43 STARBURST Reference Frame: ICRS Extended: NO ------------------------------------------------------------------------------------------------------------------------------------ 17452( 3) - 01-Jul-2024 19:51:40 - [ 4] Visit: 01 (J0827+3429) 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 J0827+3429 COS/NUV ACQ/IMA PSA MIRRORA 1 500 S (500 GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 J0827+3429 COS/FUV TIME-TA PSA G130M 1222 BUFFER-TIME=9000., FLASH=YES, 1 1200 S G FP-POS=1 see below (1327 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 J0827+3429 COS/FUV TIME-TA PSA G130M 1222 BUFFER-TIME=9000., FLASH=YES, 1 2200. S G FP-POS=ALL, SEGMENT=BOTH see below (10360 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 | ------------------------------------------------------------------------------------------------------------------------------------ J0827+3429 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE J0827+3429 2 COS/FUV TIME-TA PSA G130M 1222 none none none none 1 1327.0 S G J0827+3429 3 COS/FUV TIME-TA PSA G130M 1222 none none none 1 2 2590.0 S G J0827+3429 3 COS/FUV TIME-TA PSA G130M 1222 none none none 2 3 2590.0 S G J0827+3429 3 COS/FUV TIME-TA PSA G130M 1222 none none none 3 4 2590.0 S G J0827+3429 3 COS/FUV TIME-TA PSA G130M 1222 none none none 4 5 2590.0 S G 17452( 3) - 01-Jul-2024 19:51:40 - [ 5] Visit: 02 (J1046+4047) 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 J1046+4047 COS/NUV ACQ/IMA PSA MIRRORA 1 300 S (300 GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 J1046+4047 COS/FUV TIME-TA PSA G130M 1222 BUFFER-TIME=9000., FLASH=YES, 1 2200 S G FP-POS=ALL, SEGMENT=BOTH see below (9557 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 | ------------------------------------------------------------------------------------------------------------------------------------ J1046+4047 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE J1046+4047 2 COS/FUV TIME-TA PSA G130M 1222 none none none 1 1 1742.0 S G J1046+4047 2 COS/FUV TIME-TA PSA G130M 1222 none none none 2 2 2605.0 S G J1046+4047 2 COS/FUV TIME-TA PSA G130M 1222 none none none 3 3 2605.0 S G J1046+4047 2 COS/FUV TIME-TA PSA G130M 1222 none none none 4 4 2605.0 S G 17452( 3) - 01-Jul-2024 19:51:40 - [ 6] Visit: 03 (J1300+3625) 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 J1300+3625 COS/NUV ACQ/IMA PSA MIRRORA 1 400 S (400 GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 J1300+3625 COS/FUV TIME-TA PSA G130M 1222 BUFFER-TIME=9000., FLASH=YES, 1 2200 S G FP-POS=ALL, SEGMENT=BOTH see below (9317 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 | ------------------------------------------------------------------------------------------------------------------------------------ J1300+3625 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE J1300+3625 2 COS/FUV TIME-TA PSA G130M 1222 none none none 1 1 1532.0 S G J1300+3625 2 COS/FUV TIME-TA PSA G130M 1222 none none none 2 2 2595.0 S G J1300+3625 2 COS/FUV TIME-TA PSA G130M 1222 none none none 3 3 2595.0 S G J1300+3625 2 COS/FUV TIME-TA PSA G130M 1222 none none none 4 4 2595.0 S G 17452( 3) - 01-Jul-2024 19:51:40 - [ 7] Visit: 04 (J1416+4645) 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 J1416+4645 COS/NUV ACQ/IMA PSA MIRRORA 1 400 S (400 GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 J1416+4645 COS/FUV TIME-TA PSA G130M 1222 BUFFER-TIME=9000., FLASH=YES, 1 2200 S G FP-POS=ALL, SEGMENT=BOTH see below (9409 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 | ------------------------------------------------------------------------------------------------------------------------------------ J1416+4645 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE J1416+4645 2 COS/FUV TIME-TA PSA G130M 1222 none none none 1 1 1555.0 S G J1416+4645 2 COS/FUV TIME-TA PSA G130M 1222 none none none 2 2 2618.0 S G J1416+4645 2 COS/FUV TIME-TA PSA G130M 1222 none none none 3 3 2618.0 S G J1416+4645 2 COS/FUV TIME-TA PSA G130M 1222 none none none 4 4 2618.0 S G 17452( 3) - 01-Jul-2024 19:51:40 - [ 8] Visit: 05 (J1444+4840) 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 J1444+4840 COS/NUV ACQ/IMA PSA MIRRORA 1 500 S (500 GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 J1444+4840 COS/FUV TIME-TA PSA G130M 1222 BUFFER-TIME=9000., FLASH=YES, 1 1200 S G FP-POS=1, SEGMENT=BOTH see below (1355 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 J1444+4840 COS/FUV TIME-TA PSA G130M 1222 BUFFER-TIME=9000., FLASH=YES, 1 2200 S G FP-POS=ALL, SEGMENT=BOTH see below (10472 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 | ------------------------------------------------------------------------------------------------------------------------------------ J1444+4840 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE J1444+4840 2 COS/FUV TIME-TA PSA G130M 1222 none none none none 1 1355.0 S G J1444+4840 3 COS/FUV TIME-TA PSA G130M 1222 none none none 1 2 2618.0 S G J1444+4840 3 COS/FUV TIME-TA PSA G130M 1222 none none none 2 3 2618.0 S G J1444+4840 3 COS/FUV TIME-TA PSA G130M 1222 none none none 3 4 2618.0 S G J1444+4840 3 COS/FUV TIME-TA PSA G130M 1222 none none none 4 5 2618.0 S G 17452( 3) - 01-Jul-2024 19:51:40 - [ 9] Summary Form for Proposal 17452 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, COS/NUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/IMAGE, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=9000., FLASH=YES, FP-POS=1, FP-POS=ALL, SEGMENT=BOTH ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G130M, MIRRORA ------------------------------------------------------------------------------------------------------------------------------------ Target Names J0827+3429, J1046+4047, J1300+3625, J1416+4645, J1444+4840 ------------------------------------------------------------------------------------------------------------------------------------