Community Discovery Program: CXO/VLA/HST observations of GW-detected compact mergers in O4b

This is the HST extension of a Chandra proposal. 1510298864 Assigned ID: 5908 ----- Attempting Submission 1 (Fri Apr 12 09:01:08 GMT 2024) ----- HST Phase I Proposal 5908 successfully submitted. Receipt: # 5908-1 0 ----- Attempting Submission 1 (Wed Oct 23 16:24:09 GMT 2024) ----- HST Phase II Proposal 17878 successfully submitted. Receipt: # 17878-1 ----- Attempting Submission 2 (Thu Oct 24 08:24:46 GMT 2024) ----- Community Discovery Program: CXO/VLA/HST observations of GW-detected compact mergers in O4b Chandra was the first facility to detect X-ray light from a watershed neutron star (NS) merger. In this ToO program we propose to continue Chandra's legacy in the nascent and revolutionary field of gravitational wave astronomy to identify, monitor, and characterize X-ray emission from compact-object mergers. Our goals are three-fold: (i) to characterize the diversity of emission from NS-NS mergers; (ii) to enable breakthroughs, such as the discovery of emission from a neutron star-black hole (NS-BH) merger and (iii) to model panchromatic jetemission to constrain system parameters, particularly inclination and jet structure. We will support these Chandra observations via coordinated multi-wavelength follow-up, including with VLA (radio) and HST (optical). We have gathered a large, international team to maximize our scientific output during the second half of LIGO/Virgo/KAGRA's 4th Observing Run (O4b), expected to run from Apr 2024 to early 2025. To enhance the scientific impact of these data, their value to the community, and to fully engage junior scientists in this frontier scientific pursuit we also waive any proprietary rights. Chandra Cyle 26: We request a companion HST observation for 3 Chandra/VLA epochs at 15-30 d, 100-150 d, and 200-300 d to constrain the spectral index and location of the cooling break. We select the F606W filter on the WFC3 due to its broadband sensitivity and continuity with ground-based r-band, which will enable a complete light curve out to late times. Based on Fig. 5, to probe jets with more optimistic densities (n~0.1 cm-3), we request our first HST observation to reach a 3sigma limiting mag of mF606W = 28 AB, coordinated with the 15-30 d epoch. We forgo the first Chandra observation as the kilonova emission will still be expected to dominate at < 1 week. Using the WFC3 ETC, this requires 3 orbits, assuming 40 min of usable time per orbit. To probe GW170817-like events which are fainter and peak on longer timescales, we request two deeper epochs to reach mF606W = 28.5 AB mag roughly coordinated with our 100-150 d and 200-300 d epochs. This requires 2x6 = 12 orbits. Chandra Cycle 25 follow-up: We request HST/WFC3 F606W observations aligned with two of the final three Chandra epochs, for a total of 2x6= 12 orbits to achieve detections or reasonable limits on this target. Galaxy Template: Finally, we note that the host galaxy of GW170817 had severe contamination which impacted the reliability of the counterpart photometry in the absence of a template. It is possible that the last epoch will serve as this template if a source is no longer detected. However, if the final epoch yields a detected source with S/N > 3, we request one additional 6-orbit epoch at t-t0 > 300 days to serve as a deep template and mitigate contamination, assuming only one of the events will need a template. Thus our total HST request is 33 orbits. Our collaboration is broad and includes scientists based in Canada, Europe and the US. A shared PI-ship testifies to the collaboration among the teams. Specifically, this proposal combines the efforts from Co-PIs: S. Campana, W. Fong, D. Haggard, and R. Margutti. A complete, alphabetized list of co-investigators is appended at the end of this document. The four Co-PI's are committed to the management of this large team to make timely decisions, informed by a wide range of expertise. Each of the Co-PI's also have experience as PI's of their own Chandra programs and collectively have two decades of experience in this arena. Our collective expertise includes X-ray (Chandra, Swift, etc.), optical/UV (including HST), and radio (including VLA) data analysis and interpretation, transient discovery and follow-up searches, and theoretical modelling of explosions and outflows associated with compact object mergers (e.g., GRBs and kilonovae). Resources and Survey Access: Our team has a strong track record of triggering, analyzing, and rapidly publishing transient X-ray, radio, and multi-wavelength studies. Our prompt publications featuring Chandra, HST, and VLA observations of GW170817 provide a proof-of-concept. To identify optical and near-IR counterparts, the Co-PI's are collectively involved in or leading efforts using the Dark Energy Camera and BlackGEM in Chile, the Canada-France-Hawaii Telescope, a network of telescopes in Southern Arizona (SAGUARO), the 2.6m VLT Survey Telescope (VST) in Paranal, the 60cm robotic REM telescope in La Silla (one of the telescopes which promptly observed GW170817), the Gravitational-wave Optical Transient Observer (GOTO) on La Palma, the La Silla Schmidt Southern Survey (LS4) along with the JWST, Swift, NuSTAR, and XMM-Newton observatories. We have full access to optical telescopes to spectroscopically follow up any counterpart, including the TNG (3.6m in Canary Islands), and the LBT (binocular 8m) telescope in the US, in addition to Gemini, Keck, MMT, Lick and Magellan. GRAvitational Wave Inaf TeAm (GRAWITA) is also part of the ENGRAVE collaboration (Co-I Levan is chair of the ENGRAVE Executive Committee, Co-I Tanvir is chair of the ENGRAVE Governing Council), as well as European Co-Is of this proposal, and have access to ESO-VLT telescopes through a Large Program. O4b will overlap with the start of scientific operations of the LSST carried out by the Rubin Observatory. Co-PI Margutti chairs the GW follow-up group within the LSST Science Collaborations and many Co-Is of this proposal are members of this group. Our teams also belong to the rapid-response networks that report transients from other observatories (e.g., via OpenLVEM, GCNs, and ATels). Our involvement in these efforts ensures that Chandra observations will be used efficiently. Additionally, we have gathered a premier team of theorists to help interpret our program's incoming observations, which will likely offer new challenges to existing paradigms. Multi-messenger astrophysics is entering a new era and the observations proposed here will ensure that Chandra continues its important legacy in this exciting domain. Stellar Physics and Stellar Types 0 false false false false false false false true PRIMARY 200 13 true SUPPORTED STAR GAMMA RAY BURSTER NEUTRON STAR Electromagnetic counterpart of a GW trigger GW trigger STAR GAMMA RAY BURSTER NEUTRON STAR Electromagnetic counterpart of a GW trigger GW trigger WFC3/UVIS Imaging No No F606W WFC3/UVIS Imaging No No F606W WFC3/UVIS Imaging No No F606W WFC3/UVIS Imaging No No F606W WFC3/UVIS Imaging No No F606W WFC3/UVIS Imaging No No F606W 1729758261880 /private/var/folders/4y/tqmc3__x7dn662ldcqdfdpsh0000gn/T/OPVisit592790998321280365.xml The scheduling data was generated by CASM 32.1.3. CASM was run in Phase II mode. (Tic-Visit :proposal-id 17878 :visit-id "01" :proposal-version -1 :trans-version "20240604" :date "24-Oct-2024 10:24:21.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 866240 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17878 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17878 :visit-id "01" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17878 :visit-id "01" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17878 :visit-id "01" :orbit-number 3 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 352 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) true 3 0 TOO observation /private/var/folders/4y/tqmc3__x7dn662ldcqdfdpsh0000gn/T/OPVisit9317264071063217257.xml 1729758263395 The scheduling data was generated by CASM 32.1.3. CASM was run in Phase II mode. (Tic-Visit :proposal-id 17878 :visit-id "02" :proposal-version -1 :trans-version "20240604" :date "24-Oct-2024 10:24:23.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 6 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1732464 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17878 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17878 :visit-id "02" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17878 :visit-id "02" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17878 :visit-id "02" :orbit-number 3 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17878 :visit-id "02" :orbit-number 4 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17878 :visit-id "02" :orbit-number 5 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17878 :visit-id "02" :orbit-number 6 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) true 6 0 /private/var/folders/4y/tqmc3__x7dn662ldcqdfdpsh0000gn/T/OPVisit4875547668676932550.xml 1729758264182 The scheduling data was generated by CASM 32.1.3. CASM was run in Phase II mode. (Tic-Visit :proposal-id 17878 :visit-id "03" :proposal-version -1 :trans-version "20240604" :date "24-Oct-2024 10:24:24.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 6 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1732464 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17878 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17878 :visit-id "03" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17878 :visit-id "03" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17878 :visit-id "03" :orbit-number 3 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17878 :visit-id "03" :orbit-number 4 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17878 :visit-id "03" :orbit-number 5 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17878 :visit-id "03" :orbit-number 6 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) true 6 0 /private/var/folders/4y/tqmc3__x7dn662ldcqdfdpsh0000gn/T/OPVisit8798261271577535855.xml 1729758265499 The scheduling data was generated by CASM 32.1.3. CASM was run in Phase II mode. (Tic-Visit :proposal-id 17878 :visit-id "04" :proposal-version -1 :trans-version "20240604" :date "24-Oct-2024 10:24:25.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 6 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1732464 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17878 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17878 :visit-id "04" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17878 :visit-id "04" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17878 :visit-id "04" :orbit-number 3 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17878 :visit-id "04" :orbit-number 4 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17878 :visit-id "04" :orbit-number 5 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17878 :visit-id "04" :orbit-number 6 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) true 6 0 /private/var/folders/4y/tqmc3__x7dn662ldcqdfdpsh0000gn/T/OPVisit2264074807928313082.xml 1729758266832 The scheduling data was generated by CASM 32.1.3. CASM was run in Phase II mode. (Tic-Visit :proposal-id 17878 :visit-id "05" :proposal-version -1 :trans-version "20240604" :date "24-Oct-2024 10:24:26.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 6 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1732464 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17878 :visit-id "05" :obset-id "05" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17878 :visit-id "05" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17878 :visit-id "05" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17878 :visit-id "05" :orbit-number 3 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17878 :visit-id "05" :orbit-number 4 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17878 :visit-id "05" :orbit-number 5 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17878 :visit-id "05" :orbit-number 6 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) true 6 0 /private/var/folders/4y/tqmc3__x7dn662ldcqdfdpsh0000gn/T/OPVisit12619610867985453438.xml 1729758267502 The scheduling data was generated by CASM 32.1.3. CASM was run in Phase II mode. (Tic-Visit :proposal-id 17878 :visit-id "06" :proposal-version -1 :trans-version "20240604" :date "24-Oct-2024 10:24:27.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 6 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1732464 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17878 :visit-id "06" :obset-id "06" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17878 :visit-id "06" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17878 :visit-id "06" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17878 :visit-id "06" :orbit-number 3 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17878 :visit-id "06" :orbit-number 4 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17878 :visit-id "06" :orbit-number 5 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17878 :visit-id "06" :orbit-number 6 :pcs-time 380 :si-vis-utilization 2625 :al-overhead-at-end 116 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) true 6 0