17236( 3) - 07-Feb-2023 15:14:39 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17236 Version: 3 Check-in Time: 07-Feb-2023 15:14:39 STScI Edit Number: 0 Title Tidal disruption events unveiled: understanding their long-term accretion with Chandra and HST ------------------------------------------------------------------------------------ Type Cycle GO 30 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Matt Nicholl University of Birmingham Y CoI: Prof. Edo Berger Harvard University N CoI: Dr. Bradford Snios Smithsonian Institution Astrophysical N Observatory CoI: Dr. Katie Auchettl University of Melbourne N CoI: Dr. Andy Lawrence University of Edinburgh, Institute for N Astronomy CoI: Phil Short University of Edinburgh, Institute for N Astronomy CoI: Dr. Tanmoy Laskar University of Utah N CoI: Dr. Kate Denham Alexander University of Arizona N CoI: Aprajita Hajela Northwestern University N CoI: Dr. Benjamin Paul Gompertz University of Birmingham N CoI: Dr. Yvette Cendes Harvard University N CoI: Dr. Wen-fai Fong Northwestern University N CoI: Dr. Samantha Oates University of Birmingham N CoI: Dr. Sean L. McGee University of Birmingham N CoI: Dr. Peter Blanchard Northwestern University N CoI: Mr. Evan Ridley University of Birmingham N CoI: Dr. Sebastian Gomez Space Telescope Science Institute N CoI: Dr. Raffaella Margutti University of California - Berkeley N CoI: Tarraneh Eftekhari Northwestern University N CoI: Prof. Ryan Chornock University of California - Berkeley N CoI: Aysha Aamer University of Birmingham N CoI: Xinyue Sheng University of Birmingham N ------------------------------------------------------------------------------------ Abstract Tidal disruption events (TDEs) provide a unique laboratory for studying supermassive black holes. Shortly after disruption, most TDEs are 'veiled': emitting mainly UV/optical while X-ray signs of accretion are obscured. However by >~3 years, the stellar debris should settle into a thin, unobscured disk, brightest in X-rays and UV. We propose to observe 3 very nearby and well-studied TDEs at late phases using Chandra and HST. Only previous 1 TDE (and no veiled TDEs) have high S/N X-ray data at late times. Covering the SED peak with X-ray+UV reveals (1) the evolution of the accretion rate, and whether embedded accretion powered the optical flare; (2) the dominant energy release mechanism in the disk; and (3) fundamental disk parameters such as masses and possibly spin. ------------------------------------------------------------------------------------ Observations Description ------------------------ We will obtain WFC3/UVIS imaging in F225W of the three closest TDEs to date at 17236( 3) - 07-Feb-2023 15:14:39 - [ 2] phases of >~4 years post-disruption. This is achievable at an SNR~10-30 with one orbit per target. We will simultaneously obtain X-ray observations to measure the UV-X-ray spectral slope. ------------------------------------------------------------------------------------ 17236( 3) - 07-Feb-2023 15:14:39 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 AT2019QIZ EXT-STAR, X-RAY RA=04H46M37.8800S, J2000 V = 20 F225W ~ 23.6 TRANSIENT DEC=-10D13'34.92" Reference Frame: Other: SIMBAD Extended: NO Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. ------------------------------------------------------------------------------------------------------------------------------------ 2 AT2018DYB EXT-STAR, X-RAY RA=16H10M58.7740S, J2000 V = 17 F225W ~ 24 TRANSIENT DEC=-60D55'23.16" Reference Frame: Other: SIMBAD Extended: NO Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. ------------------------------------------------------------------------------------------------------------------------------------ 3 AT2019AHK EXT-STAR, X-RAY RA=07H00M11.4100S, J2000 V = 16 F225W ~ 24.9 TRANSIENT DEC=-66D02'25.16" Reference Frame: Other: SIMBAD 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 ------------------------------------------------------------------------------------------------------------------------------------ 17236( 3) - 07-Feb-2023 15:14:39 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-UVIS-DITHER-BOX Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.173 Line_Spacing 0.112 Coordinate_Frame POS-TARG Pattern_Orient 23.884 Angle_Between_Sides 81.785 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 17236( 3) - 07-Feb-2023 15:14:39 - [ 5] Visit: 01 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 AT2019QIZ WFC3/UVI ACCUM UVIS2 F225W FLASH=20 1 500 S PATTERN 1 1 S see below (2340 S) Comments: Questions: 1. Is this the optimal FLASH to use? 2. Targets are at the centers of galaxies ~1 arcmin across. We want to include the whole galaxy in each image as this enables additional science. Is UVIS1 the best location to put the galaxy on the chip? ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ AT2019QIZ 1 WFC3/UVI ACCUM UVIS2 F225W 1 none none none 1 585.0 S S AT2019QIZ 1 WFC3/UVI ACCUM UVIS2 F225W 2 none none none 1 585.0 S S AT2019QIZ 1 WFC3/UVI ACCUM UVIS2 F225W 3 none none none 1 585.0 S S AT2019QIZ 1 WFC3/UVI ACCUM UVIS2 F225W 4 none none none 1 585.0 S S 17236( 3) - 07-Feb-2023 15:14:39 - [ 6] Visit: 02 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 AT2018DYB WFC3/UVI ACCUM UVIS2 F225W FLASH=20 1 500 S PATTERN 1 1 S see below (2600 S) Comments: Questions: 1. Is this the optimal FLASH to use? 2. Targets are at the centers of galaxies ~1 arcmin across. We want to include the whole galaxy in each image as this enables additional science. Is UVIS1 the best location to put the galaxy on the chip? ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ AT2018DYB 1 WFC3/UVI ACCUM UVIS2 F225W 1 none none none 1 650.0 S S AT2018DYB 1 WFC3/UVI ACCUM UVIS2 F225W 2 none none none 1 650.0 S S AT2018DYB 1 WFC3/UVI ACCUM UVIS2 F225W 3 none none none 1 650.0 S S AT2018DYB 1 WFC3/UVI ACCUM UVIS2 F225W 4 none none none 1 650.0 S S 17236( 3) - 07-Feb-2023 15:14:39 - [ 7] Visit: 03 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 AT2019AHK WFC3/UVI ACCUM UVIS2 F225W FLASH=20 1 500 S PATTERN 1 1 S see below (2676 S) Comments: Questions: 1. Is this the optimal FLASH to use? 2. Targets are at the centers of galaxies ~1 arcmin across. We want to include the whole galaxy in each image as this enables additional science. Is UVIS1 the best location to put the galaxy on the chip? ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ AT2019AHK 1 WFC3/UVI ACCUM UVIS2 F225W 1 none none none 1 669.0 S S AT2019AHK 1 WFC3/UVI ACCUM UVIS2 F225W 2 none none none 1 669.0 S S AT2019AHK 1 WFC3/UVI ACCUM UVIS2 F225W 3 none none none 1 669.0 S S AT2019AHK 1 WFC3/UVI ACCUM UVIS2 F225W 4 none none none 1 669.0 S S 17236( 3) - 07-Feb-2023 15:14:39 - [ 8] Summary Form for Proposal 17236 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters FLASH=20 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 1 1 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F225W ------------------------------------------------------------------------------------------------------------------------------------ Target Names AT2018DYB, AT2019AHK, AT2019QIZ ------------------------------------------------------------------------------------------------------------------------------------