16303( 7) - 18-Nov-2021 20:07:04 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 16303 Version: 7 Check-in Time: 18-Nov-2021 20:07:04 STScI Edit Number: 0 Title Fine-Tuned Search for Kilonova Emission in a Short Gamma-Ray Burst: Implications for the Progenitors, GW Sources, and r-Process Nucleosynthesis ------------------------------------------------------------------------------------ Type Cycle GO 28 ------------------------------------------------------------------------------------ Investigators Contact? PI: Prof. Edo Berger Harvard University Y CoI: Dr. Philip Cowperthwaite Carnegie Institution of Washington N CoI: Dr. Wen-fai Fong Northwestern University N CoI: Prof. Ryan Chornock University of California - Berkeley N CoI: Dr. Chris Fryer Los Alamos National Laboratory N CoI: Dr. Daniel Kasen University of California - Berkeley N CoI: Prof. Brian Metzger Columbia University in the City of New N York CoI: Dr. Raffaella Margutti University of California - Berkeley N CoI: Dr. Matt Nicholl University of Birmingham N CoI: Dr. Peter Blanchard Northwestern University N CoI: Sebastian Gomez Harvard University N CoI: Dr. Ashley Villar Columbia University in the City of New N York CoI: Griffin Hosseinzadeh University of Arizona N CoI: Ms. Tarraneh Eftekhari Smithsonian Institution Astrophysical N Observatory CoI: Locke Patton Smithsonian Institution Astrophysical N Observatory ------------------------------------------------------------------------------------ Abstract The joint gravitational wave and electromagnetic detections of the binary neutron star (BNS) merger GW170817 ushered in a new era of astrophysics. In the UV/optical/NIR the emission (a "kilonova") was powered by radioactive decay of nuclei produced via r-process nucleosynthesis. In the gamma-ray, X-ray, and radio the emission was instead powered by an off-axis jet typical of short gamma-ray bursts (SGRBs); this connection was previously supported by the HST detection of a kilonova in the short GRB130603B. With only a single joint GW-EM detection and a single kilonova detection in an SGRB, the key frontier is to begin to map the distribution of merger outcomes: ejecta mass, velocity, geometry, and nucleosynthetic yields. Here we propose to achieve this goal with HST observations of a kilonova associated with an SGRBs; observations of kilonovae in SGRBs are essential because the orientation is well known (face-on, along the binary's angular momentum axis) and the LIGO/Virgo Observing Run 3 has not yielded joint GW-EM detections. Such a study can only be achieved with the sensitivity and resolution of HST, and it matches one of the "special initiatives", namely deep NIR monitoring that is essential for informing future JWST follow-ups ("JWST Preparatory Observations"). We request 10 orbits for 1 SGRB event. The HST observations will be supported by approved programs at Chandra, VLA, ALMA, Gemini, Keck, Magellan, MMT that will provide the targets, cover optical and early NIR follow-up to establish the baseline behavior, and complete the multi-wavelength picture of the event. Given the broad interest in this topic we waive the proprietary period. 16303( 7) - 18-Nov-2021 20:07:04 - [ 2] ------------------------------------------------------------------------------------ Observations Description ------------------------ Triggered target is GRB211106A at z=0.1, with observations for this redshift range as described below. To determine the expected apparent brightness of the kilonova for the expected range of ejecta masses (0.01-0.1 Msun), and to inform the choice of filters, we convolve the kilonova models of Barnes & Kasen (2013) as a function of redshift with the ACS/F814W, WFC3/F110W, and WFC3/F160W filter response functions. We calculate the resulting apparent brightness in two rest-frame times of 4 days (peak) and 10 days (post-maximum). The actual observer-frame times for the two HST epochs will therefore be 4x(1+z) days and 10x(1+z) days, where the redshift will be known prior to triggering the HST observations from rapid ground-based follow-up. The choice of filters is designed to straddle the break at 1 micron in the rest-frame, in order to capture the unusually red color of a kilonova. We base our HST trigger criteria and time request on the model with 0.01 Msun so that we can probe the wide range of ejecta masses predicted by numerical simulations (rather than just the bright upper bound of 0.1sun); this will allow any non-detections to place meaningful constraints on the r-process yield. Epoch 1 (4x(1+z) days): We find that at z<=0.2 it is advantageous to use the ACS/F814W and WFC3/F110W filters, which give the best combination of sensitivity (5sigma=27.7 and 27.5 AB mag in 2 orbits each, respectively, using the ACS and WFC3 ETCs) and color contrast (F814W-F110W=1.6-2 AB mag). The afterglow color in these filters will be much bluer, F814W-F110W=0.3 AB mag, so a kilonova origin can be robustly demonstrated. At z=0.2-0.4 we will instead use the WFC3/F110W and F160W filters to capture the spectral break (5sigma=26.3 AB mag for F160W in 2 orbits). The resulting color is F110W-F160W=0.6-1.2 AB mag, compared to a bluer color for the afterglow, F110W-F160W=0.3 AB mag. The kilonova emission for 0.1 Msun can be detected to z=0.7, but we truncate our trigger criteria at z=0.4 to be able to detect the emission in the case of 0.01 Msun. Epoch 2 (10x(1 + z) days): In the second epoch we will only observe in a single filter redward of the 1 micron break since we are only concerned with demonstrating a rapid decline that will help to robustly determine the ejecta mass (i.e., the unusually red color will already be established with the first epoch near peak). This will require 2 orbits in F110W (z<=0.2) or F160W (z=0.2-0.4). In this case, if the ejecta mass is 0.01 Msun we will obtain a deep upper limit that will establish the expected rapid fading, while in the case of 0.1 Msun we will have a second detection. Templates (>1 month): We will acquire template images after the kilonova emission has faded away that match the exposure time and filters of the earlier epochs. This will therefore require a total of 4 orbits (2 orbits in each filter). We note, however, that in the case of 0.01 Msun a non-detection in the second epoch could be used as a template in one of the two filters (F110W or F160W depending on the redshift), meaning that the final observation will require only 2 orbits. Since we do not know the ejecta mass in advance we 16303( 7) - 18-Nov-2021 20:07:04 - [ 3] request 4 orbits for the final epoch, but may use only 2 orbits. This will be known following epoch 2. ------------------------------------------------------------------------------------ 16303( 7) - 18-Nov-2021 20:07:04 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SGRB211106A UNIDENTIFIED, GAMMA RAY RA=22H54M20.5000S +/- 0.5", J2000 Z = 0.1 V = 26 EMITTER DEC=-53D13'50.90" +/- 0.5" Reference Frame: ICRS Extended: NO Comments: Short GRB at z~0.1; observations in ACS/F814W and WFC3/F110W as planned in the original proposal. ------------------------------------------------------------------------------------------------------------------------------------ 16303( 7) - 18-Nov-2021 20:07:04 - [ 5] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type ACS-WFC-DITHER-BOX Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.262 Line_Spacing 0.192 Coordinate_Frame POS-TARG Pattern_Orient 18.39 Angle_Between_Sides 68.14 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-IR-DITHER-BOX-MIN Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.572 Line_Spacing 0.365 Coordinate_Frame POS-TARG Pattern_Orient 18.528 Angle_Between_Sides 74.653 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 16303( 7) - 18-Nov-2021 20:07:04 - [ 6] Visit: 01 (SRGB211106A-EP1) Visit Requirements: ON HOLD ; TOO RESPONSE TIME 3.0D On Hold Comments: This visit is a target of opportunity triggered on a Short GRB of z < 0.2. This is our first epoch and should be triggered at 4 x (1+z) days after the GRB detection. 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 SGRB211106A ACS/WFC ACCUM WFC F814W 1 500 S PATTERN 1 1-2 see below (2132 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SGRB211106A ACS/WFC ACCUM WFC F814W 1 500 S see below (2132 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 SGRB211106A WFC3/IR MULTIAC IR F110W NSAMP=13, SAMP-SEQ=SPARS50 1 DEF PATTERN 2 3-4 CUM (2411.751 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 SGRB211106A WFC3/IR MULTIAC IR F110W NSAMP=14, SAMP-SEQ=SPARS50 1 DEF CUM (2611.753 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 | ------------------------------------------------------------------------------------------------------------------------------------ SGRB211106A 1 ACS/WFC ACCUM WFC F814W 1 none none none 1 526.0 S SGRB211106A 1 ACS/WFC ACCUM WFC F814W 2 none none none 1 526.0 S SGRB211106A 1 ACS/WFC ACCUM WFC F814W 3 none none none 2 540.0 S SGRB211106A 1 ACS/WFC ACCUM WFC F814W 4 none none none 2 540.0 S SGRB211106A 2 ACS/WFC ACCUM WFC F814W 1 none none none 1 526.0 S SGRB211106A 2 ACS/WFC ACCUM WFC F814W 2 none none none 1 526.0 S SGRB211106A 2 ACS/WFC ACCUM WFC F814W 3 none none none 2 540.0 S SGRB211106A 2 ACS/WFC ACCUM WFC F814W 4 none none none 2 540.0 S SGRB211106A 3 WFC3/IR MULTIAC IR F110W 1 none none none 3 N/A CUM SGRB211106A 3 WFC3/IR MULTIAC IR F110W 2 none none none 3 N/A CUM SGRB211106A 3 WFC3/IR MULTIAC IR F110W 3 none none none 4 N/A CUM SGRB211106A 3 WFC3/IR MULTIAC IR F110W 4 none none none 4 N/A CUM SGRB211106A 4 WFC3/IR MULTIAC IR F110W 1 none none none 3 N/A CUM 16303( 7) - 18-Nov-2021 20:07:04 - [ 7] 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 | ------------------------------------------------------------------------------------------------------------------------------------ SGRB211106A 4 WFC3/IR MULTIAC IR F110W 2 none none none 3 N/A CUM SGRB211106A 4 WFC3/IR MULTIAC IR F110W 3 none none none 4 N/A CUM SGRB211106A 4 WFC3/IR MULTIAC IR F110W 4 none none none 4 N/A CUM 16303( 7) - 18-Nov-2021 20:07:04 - [ 8] Visit: 02 (SRGB211106A-EP2) Visit Requirements: AFTER 01 BY 6 D TO 9 D; ON HOLD On Hold Comments: This visit is a target of opportunity triggered on a Short GRB of z < 0.2. This is our second epoch and should be triggered at 10 x (1+z) days after the GRB detection. 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 SGRB211106A WFC3/IR MULTIAC IR F110W NSAMP=13, SAMP-SEQ=SPARS50 1 DEF PATTERN 2 1-2 CUM (2411.751 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SGRB211106A WFC3/IR MULTIAC IR F110W NSAMP=14, SAMP-SEQ=SPARS50 1 DEF CUM (2611.753 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 | ------------------------------------------------------------------------------------------------------------------------------------ SGRB211106A 1 WFC3/IR MULTIAC IR F110W 1 none none none 1 N/A CUM SGRB211106A 1 WFC3/IR MULTIAC IR F110W 2 none none none 1 N/A CUM SGRB211106A 1 WFC3/IR MULTIAC IR F110W 3 none none none 2 N/A CUM SGRB211106A 1 WFC3/IR MULTIAC IR F110W 4 none none none 2 N/A CUM SGRB211106A 2 WFC3/IR MULTIAC IR F110W 1 none none none 1 N/A CUM SGRB211106A 2 WFC3/IR MULTIAC IR F110W 2 none none none 1 N/A CUM SGRB211106A 2 WFC3/IR MULTIAC IR F110W 3 none none none 2 N/A CUM SGRB211106A 2 WFC3/IR MULTIAC IR F110W 4 none none none 2 N/A CUM 16303( 7) - 18-Nov-2021 20:07:04 - [ 9] Visit: 03 (SRGB211106A-TEMPLATE) Visit Requirements: AFTER 02 BY 20 D TO 30 D; ON HOLD On Hold Comments: This visit is a target of opportunity triggered on a Short GRB of z < 0.2. This is our template epoch and should be triggered at >1 month after the GRB detection. 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 SGRB211106A ACS/WFC ACCUM WFC F814W 1 500 S PATTERN 1 1-2 see below (2132 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SGRB211106A ACS/WFC ACCUM WFC F814W 1 500 S see below (2132 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 SGRB211106A WFC3/IR MULTIAC IR F110W NSAMP=13, SAMP-SEQ=SPARS50 1 DEF PATTERN 2 3-4 CUM (2411.751 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 SGRB211106A WFC3/IR MULTIAC IR F110W NSAMP=14, SAMP-SEQ=SPARS50 1 DEF CUM (2611.753 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 | ------------------------------------------------------------------------------------------------------------------------------------ SGRB211106A 1 ACS/WFC ACCUM WFC F814W 1 none none none 1 526 S SGRB211106A 1 ACS/WFC ACCUM WFC F814W 2 none none none 1 526 S SGRB211106A 1 ACS/WFC ACCUM WFC F814W 3 none none none 2 540 S SGRB211106A 1 ACS/WFC ACCUM WFC F814W 4 none none none 2 540 S SGRB211106A 2 ACS/WFC ACCUM WFC F814W 1 none none none 1 526 S SGRB211106A 2 ACS/WFC ACCUM WFC F814W 2 none none none 1 526 S SGRB211106A 2 ACS/WFC ACCUM WFC F814W 3 none none none 2 540 S SGRB211106A 2 ACS/WFC ACCUM WFC F814W 4 none none none 2 540 S SGRB211106A 3 WFC3/IR MULTIAC IR F110W 1 none none none 3 N/A CUM SGRB211106A 3 WFC3/IR MULTIAC IR F110W 2 none none none 3 N/A CUM SGRB211106A 3 WFC3/IR MULTIAC IR F110W 3 none none none 4 N/A CUM SGRB211106A 3 WFC3/IR MULTIAC IR F110W 4 none none none 4 N/A CUM SGRB211106A 4 WFC3/IR MULTIAC IR F110W 1 none none none 3 N/A CUM 16303( 7) - 18-Nov-2021 20:07:04 - [ 10] 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 | ------------------------------------------------------------------------------------------------------------------------------------ SGRB211106A 4 WFC3/IR MULTIAC IR F110W 2 none none none 3 N/A CUM SGRB211106A 4 WFC3/IR MULTIAC IR F110W 3 none none none 4 N/A CUM SGRB211106A 4 WFC3/IR MULTIAC IR F110W 4 none none none 4 N/A CUM 16303( 7) - 18-Nov-2021 20:07:04 - [ 11] Summary Form for Proposal 16303 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IR, WFC ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC, WFC3/IR ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=13, NSAMP=14, SAMP-SEQ=SPARS50 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements AFTER 01 BY 6 D TO 9 D, AFTER 02 BY 20 D TO 30 D, ON HOLD , PATTERN 1 1-2, PATTERN 2 1-2, PATTERN 2 3-4, TOO RESPONSE TIME 3.0D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F110W, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names SGRB211106A ------------------------------------------------------------------------------------------------------------------------------------