12886( 3) - 26-Nov-2012 12:38:14 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 12886 Version: 3 Check-in Time: 26-Nov-2012 12:38:14 STScI Edit Number: 0 Title Direct Detection of Escaping Lyman Continuum Emission from Local Lyman-Break Analog Galaxy ------------------------------------------------------------------------------------ Type Cycle GO 20 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Sanchayeeta Borthakur The Johns Hopkins University Y CoI: Dr. Timothy M. Heckman The Johns Hopkins University N CoI: Dr. Claus Leitherer Space Telescope Science Institute N CoI: Dr. Roderik Overzier University of Texas at Austin N ------------------------------------------------------------------------------------ Abstract Lyman continuum photons leaking out of massive star forming systems are believed to be the source of ionizing photons that led to reionization of the universe at z>6. However, our understanding of how these photons leaked from their parent galaxies is limited at best. Part of the problem is that the high-redshift galaxies are hard to study. Therefore, we have complied a sample of local galaxies that mimic star-forming Lyman-Break galaxies in every measurable way. We found that a class of these galaxies with Dominant Central Object (DCO) has much higher star-formation rates per unit volume and much faster outflows that can blow away and ionize interstellar medium, thus allowing a significant fraction of their Lyman continuum to escape. We request 9 orbits of HST to observe one such extremely rare galaxy with estimated escape fraction as high as 0.3. This value was estimated from three independent but indirect lines of evidence. These observations will provide the first direct evidence of leaking Lyman continuum emission in these systems. This will be a major step forward in understanding massive star forming systems and how ionizing radiation might have escaped at the epoch of reionization. ------------------------------------------------------------------------------------ Observations Description ------------------------ J092159 is a unique Lyman Break Analog (LBA) galaxy that has a compact massive star forming region (~100 pc with 109Mo) known as a Dominant Compact Object (DCO). In our recent study of eight LBJ092159 is a unique Lyman Break Analog (LBA) galaxy that has a compact massive star forming region (~100 pc with 109Mo) known as a Dominant Compact Object (DCO). In our recent study of eight LBAs including this target with COS (Heckman et al. 2011), we found that galaxies with a DCO drive outflows with velocities much higher than the LBAs without a DCO. These powerful (~1000 km/s) outflows can blow holes through the interstellar medium (ISM) that may allow ionizing photon to escape. We also found indirect evidence of holes in the ISM of this galaxy. The COS spectrum show strong saturated metal absorption-lines (e.g. C II and Si II) in the neutral ISM that are not black suggesting optically thick could partially covering the starburst. They also show blue shifted Lyman alpha in emission further suggesting holes in the ISM of this galaxy. Furthermore, the star formation rate implied by the far-IR plus far-UV continuum luminosity is over three times higher than that implied by the extinction-corrected H alpha 12886( 3) - 26-Nov-2012 12:38:14 - [ 2] emission-line luminosity. Our primary goals of this project is to understand if ionizing radiation is escaping from Lyman Break Galaxy Analogs (LBAs) and if so the physical conditions responsible for it. The project uses COS FUV grating G140L for 9 orbits in order to achieve the above-mentioned goals. The 25500 s observations for the target galaxy with FUV of 19.41 +/- 0.15 mags at 1126 A (Lyman continuum edge of the target galaxy) will result in a S/N >19.2 per resolution element (COS.sp.413287). As a safety check, a magnitude higher source (i.e FUV = 18.4 mag) when observed for 25500 s will yield 213 cts/s for the entire detector (COS.sp.413288). For the target acquisition we use NUV MIRROR A imaging setting for 45 secs (COS.ta.413264). The target galaxy has a NUV magnitude =18.98 +/- 0.07 mags or 18.9 mags in the worst-case scenario based on error estimate. This exposure will have a count rate for the entire detector of 1042 cts/s and for the brightest pixel 15 cts/s. To check the safety of the acquisition exposures, we estimate the counts for an exposure of 45 s for a source 1 mag brighter, i.e. NUV=17.98 mags including the error margin, to 38 cts/s for the brightest pixel (i.e. less than 50 cts/s) and 1205 cts/s for the entire detector (COS.ta.413263). We will observe for another 600 s with MIRRORA after target acquisition for a deeper image. (COS.im.413289) Hence, we conclude that both the exposures are within safe limits for the detectors. As including this target with COS (Heckman et al. 2011), we found that galaxies with a DCO drive outflows with velocities much higher than the LBAs without a DCO. These powerful (~1000 km/s) outflows can blow holes through the interstellar medium (ISM) that may allow ionizing photon to escape. We also found indirect evidence of holes in the ISM of this galaxy. The COS spectrum show strong saturated metal absorption-lines (e.g. C II and Si II) in the neutral ISM that are not black suggesting optically thick could partially covering the starburst. They also show blue shifted Lyman alpha in emission further suggesting holes in the ISM of this galaxy. Furthermore, the star formation rate implied by the far-IR plus far-UV continuum luminosity is over three times higher than that implied by the extinction-corrected H alpha emission-line luminosity. Our primary goals of this project is to understand if ionizing radiation is escaping from Lyman Break Galaxy Analogs (LBAs) and if so the physical conditions responsible for it. The project uses COS FUV grating G140L for 9 orbits in order to achieve the above-mentioned goals. The 25500 s observations for the target galaxy with FUV of 19.41 +/- 0.15 mags at 1126 A (Lyman continuum edge of the target galaxy) will result in a S/N >19.2 per resolution element (COS.sp.413287). As a safety check, a magnitude higher source (i.e FUV = 18.4 mag) when observed for 25500 s will yield 213 cts/s for the entire detector (COS.sp.413288). For the target acquisition we use NUV MIRROR A imaging setting for 45 secs (COS.ta.413264). The target galaxy has a NUV magnitude =18.98 +/- 0.07 mags or 12886( 3) - 26-Nov-2012 12:38:14 - [ 3] 18.9 mags in the worst-case scenario based on error estimate. This exposure will have a count rate for the entire detector of 1042 cts/s and for the brightest pixel 15 cts/s. To check the safety of the acquisition exposures, we estimate the counts for an exposure of 45 s for a source 1 mag brighter, i.e. NUV=17.98 mags including the error margin, to 38 cts/s for the brightest pixel (i.e. less than 50 cts/s) and 1205 cts/s for the entire detector (COS.ta.413263). We will observe for another 600 s with MIRRORA after target acquisition for a deeper image. (COS.im.413289) Hence, we conclude that both the exposures are within safe limits for the detectors. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 12886( 3) - 26-Nov-2012 12:38:14 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 2MASS-J09215 GALAXY, STARBURST RA=09H21M59.3900S +/- 0.1", J2000 Z = V = 18.441 GALEX FUV= 19.41 +/- 0.15 ; 939+4509126 DEC=+45D09'12.40" +/- 0.1" 0.23499 NUV = 18.91 =/- 0.07 Reference Frame: ICRS Comments: This object is a LBA galaxy from the sample presented by Heckman et al. 2011 (ApJ, 730, 5) ------------------------------------------------------------------------------------------------------------------------------------ 12886( 3) - 26-Nov-2012 12:38:14 - [ 5] Visit: 01 Visit Requirements: On Hold Comments: Additional Comments: 5/9 orbits of G140L at the rest frame Lyman limit of the target at wave_obs=1126 corresponding to z=0.2 to detect escaping Lyman continuum photons from this galaxy. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 2MASS-J0921 COS/NUV ACQ/IMA PSA MIRRORA 1 645 S 5939+450912 GE 6 ------------------------------------------------------------------------------------------------------------------------------------ 2 2MASS-J0921 COS/FUV TIME-TA PSA G140L 1280 FP-POS=3, SEGMENT=BOTH, 1 1421 S 5939+450912 G BUFFER-TIME=1311 6 ------------------------------------------------------------------------------------------------------------------------------------ 3 2MASS-J0921 COS/FUV TIME-TA PSA G140L 1280 FP-POS=3, SEGMENT=BOTH, 1 3091 S 5939+450912 G BUFFER-TIME=2981 6 ------------------------------------------------------------------------------------------------------------------------------------ 4 2MASS-J0921 COS/FUV TIME-TA PSA G140L 1280 FP-POS=3, SEGMENT=BOTH, 1 3091 S 5939+450912 G BUFFER-TIME=2981 6 ------------------------------------------------------------------------------------------------------------------------------------ 5 2MASS-J0921 COS/FUV TIME-TA PSA G140L 1280 FP-POS=3, SEGMENT=BOTH, 1 3091 S 5939+450912 G BUFFER-TIME=2981 6 ------------------------------------------------------------------------------------------------------------------------------------ 6 2MASS-J0921 COS/FUV TIME-TA PSA G140L 1280 FP-POS=3, SEGMENT=BOTH, 1 3091 S 5939+450912 G BUFFER-TIME=2981 6 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ 2MASS-J09215939+450 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A 9126 GE 2MASS-J09215939+450 2 COS/FUV TIME-TA PSA G140L 1280 none none none none 1 N/A 9126 G 2MASS-J09215939+450 3 COS/FUV TIME-TA PSA G140L 1280 none none none none 2 N/A 9126 G 2MASS-J09215939+450 4 COS/FUV TIME-TA PSA G140L 1280 none none none none 3 N/A 9126 G 2MASS-J09215939+450 5 COS/FUV TIME-TA PSA G140L 1280 none none none none 4 N/A 9126 G 12886( 3) - 26-Nov-2012 12:38:14 - [ 6] 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 | ------------------------------------------------------------------------------------------------------------------------------------ 2MASS-J09215939+450 6 COS/FUV TIME-TA PSA G140L 1280 none none none none 5 N/A 9126 G 12886( 3) - 26-Nov-2012 12:38:14 - [ 7] Visit: 02 Visit Requirements: On Hold Comments: Additional Comments: 4/9 orbits of G140L at the rest frame Lyman limit of the target at wave_obs=1126 corresponding to z=0.2 to detect escaping Lyman continuum photons from this galaxy. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 2MASS-J0921 COS/NUV ACQ/IMA PSA MIRRORA 1 45 S 5939+450912 GE 6 ------------------------------------------------------------------------------------------------------------------------------------ 2 2MASS-J0921 COS/FUV TIME-TA PSA G140L 1280 FP-POS=3, SEGMENT=BOTH, 1 2621 S 5939+450912 G BUFFER-TIME=2571 6 ------------------------------------------------------------------------------------------------------------------------------------ 3 2MASS-J0921 COS/FUV TIME-TA PSA G140L 1280 FP-POS=3, SEGMENT=BOTH, 1 3091 S 5939+450912 G BUFFER-TIME=2981 6 ------------------------------------------------------------------------------------------------------------------------------------ 4 2MASS-J0921 COS/FUV TIME-TA PSA G140L 1280 FP-POS=3, SEGMENT=BOTH, 1 3091 S 5939+450912 G BUFFER-TIME=2981 6 ------------------------------------------------------------------------------------------------------------------------------------ 5 2MASS-J0921 COS/FUV TIME-TA PSA G140L 1280 FP-POS=3, SEGMENT=BOTH, 1 3091 S 5939+450912 G BUFFER-TIME=2981 6 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ 2MASS-J09215939+450 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A 9126 GE 2MASS-J09215939+450 2 COS/FUV TIME-TA PSA G140L 1280 none none none none 1 N/A 9126 G 2MASS-J09215939+450 3 COS/FUV TIME-TA PSA G140L 1280 none none none none 2 N/A 9126 G 2MASS-J09215939+450 4 COS/FUV TIME-TA PSA G140L 1280 none none none none 3 N/A 9126 G 2MASS-J09215939+450 5 COS/FUV TIME-TA PSA G140L 1280 none none none none 4 N/A 9126 G 12886( 3) - 26-Nov-2012 12:38:14 - [ 8] Summary Form for Proposal 12886 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, COS/NUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/IMAGE, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=1311, BUFFER-TIME=2571, BUFFER-TIME=2981, FP-POS=3, SEGMENT=BOTH ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G140L, MIRRORA ------------------------------------------------------------------------------------------------------------------------------------ Target Names 2MASS-J09215939+4509126 ------------------------------------------------------------------------------------------------------------------------------------