| NSF Org: |
PHY Division Of Physics |
| Recipient: |
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| Initial Amendment Date: | July 28, 2018 |
| Latest Amendment Date: | July 28, 2018 |
| Award Number: | 1806625 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Pedro Marronetti
pmarrone@nsf.gov (703)292-7372 PHY Division Of Physics MPS Directorate for Mathematical and Physical Sciences |
| Start Date: | August 1, 2018 |
| End Date: | July 31, 2019 (Estimated) |
| Total Intended Award Amount: | $40,000.00 |
| Total Awarded Amount to Date: | $40,000.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
104 AIRPORT DR STE 2200 CHAPEL HILL NC US 27599-5023 (919)966-3411 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
120 E. Cameron Ave., Physics and Chapel Hill NC US 27599-3255 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | LIGO RESEARCH SUPPORT |
| Primary Program Source: |
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| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.049 |
ABSTRACT
The recent gravitational wave (GW) detection of the first binary neutron star (BNS) merger by the LIGO/Virgo gravitational wave observatories and its associated electromagnetic (EM) counterparts has ushered in a new era of multi-messenger astrophysics. The GW170817 event has inspired a new GW search strategy using simultaneous all-sky optical imaging measurements to provide improved detection confidence as well as source identification/localization. This grant will fund the development and testing of this improved GW search in Advanced LIGO/Virgo (aLIGO/Virgo) operation run 3 (O3), with the potential to substantially increase the number of confirmed GW detections. This will significantly improve the progress of science in the national interest by leveraging the existing investments in gravitational wave and optical observatories to provide an estimated ~25% enhancement in the number of detected systems during O3, and pave the way for future multi-messenger investigations that could potentially quadruple the number of detected sources. The proposed research is at the intersection of the multi-messenger astrophysics, general relativity, digital signal processing and computing, which require young researchers to develop a deep knowledge of modern astrophysical theories, and understanding of gravitational wave instrumentation, and gives them opportunity to get firsthand experience with sophisticated signal/image-processing algorithms, computational methods, manipulation of large data sets and high performance computing.
The novel GW search proposed here is based on combining aLIGO/Virgo sub-threshold triggers with simultaneous optical imaging using the Evryscope technique. Evryscope images the entire observable night-time sky simultaneously with 2-minute cadence. Scientists can then select only those optical transient events in the aLIGO/Virgo error region which appear within the same 2-minute window as the GW candidate - reducing the GW-only false alarm probability by factors larger than 20,000. for any night-time GW events. This enables improved detection confidence for marginal GW events and thus enhanced GW detection volume. GW1708187's optical counterpart could be detected by the current Evryscope out to D ~260 Mpc, and future Evryscope-style systems to distances further than 350 Mpc. Analyses show that a future network of Evryscope-style detectors would enhance the number of GW events detected by a factor of ~2-4 compared to GW-only observations. Such a future network would particularly benefit GW source population studies and cosmological applications of GW events. This approach will also provide coverage of the brightest portion of the optical lightcurve, and arcsecond-level localization for all of these events, which will dramatically improve the EM followup response from the community as a whole, leading to improved astrophysical context for interpreting the implications of the GW event. The proposed work here is to carry out a sub-threshold GW search in aLIGO/Virgo O3, using the Evryscope North and South facilities for simultaneous optical coverage. Based on the properties of GW170817's GW properties, optical counterpart, and analyses presented here, such a search could add an additional ~25% more detections to the number of confirmed BNS mergers in O3.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
The recent gravitational wave detection of the first binary neutron star merger by LIGO/Virgo and its associated electromagnetic counterparts has ushered in a new era of multi-messenger astrophysics. The GW170817 event has inspired a new GW search strategy using simultaneous all-sky optical imaging measurements to provide improved detection confidence as well as source identification/localization. Under this NSF grant, we developed and implemented the pipeline for this LIGO-Virgo-Evryscope Optically-Assisted Koalescence Search (LIVEOAKS). This search is currently underway during the LIGO/Virgo O3 observing campaign in 2019-2020.
Intellectual Merit: The novel LIVEOAKS search we developed is based on combining aLIGO/Virgo sub-threshold triggers with simultaneous optical imaging using the Evryscope telescopes (Law et al., 2015). Evryscope images the entire observable night-time sky simultaneously with 2-minute cadence. We can then select only those optical transient events in the aLIGO/Virgo error region which appear within the same 2-minute window as the GW candidate - reducing the GW-only false alarm probability by a factor of more than 20,000 for any night-time GW events. This enables improved detection confidence for marginal gravitational wave events, and thus enhanced detection volume. GW1708187's optical counterpart could be detected by the current Evryscope out to D ~260 Mpc, and future Evryscope-style systems to D>350 Mpc. Our analyses show that a future network of Evryscope-style detectors would enhance the number of GW events detected by a factor of ~2-4 compared to GW-only observations. This approach will also provide coverage of the brightest portion of the optical lightcurve, and arcsecond-level localization for all of these events, which will dramatically improve the followup response from the community as a whole, leading to improved astrophysical context for interpreting the implications of the gravitational wave event. The operational LIVEOAKS program consists of: 1) realtime-image subtraction on both the Northern and Southern Evryscope systems, with a neural-network-based false-positive rejection system, filling a realtime transients database at UNC-CH; 2) a process running on aLIGO servers which triggers on sub-threshold events and queries the Evryscope transients database for new events; 3) a human interface which flags up the most interesting events and allows the triggering of immediate follow-up. All components are operational, and we have published a GCN alert for a (above-threshold) event as a demonstration of the system’s capabilities (Corbett et al. 2019).
Broader Impacts: This research is at the intersection of the multi-messenger astrophysics, general relativity, digital signal processing and computing, which require young researchers to develop a deep knowledge of modern astrophysical theories, understanding of gravitational wave instrumentation, and gives them opportunity to get firsthand experience with sophisticated signal/image-processing algorithms, computational methods, manipulation of large data sets and high performance computing. We continued the strong tradition of the University of Florida LIGO group of mentoring students and postdoctoral scientists, to prepare them for a wide spectrum of career opportunities.
Last Modified: 01/03/2020
Modified by: Nicholas Law
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