Hanna GWave
Hanna Gravitational Wave
Physics and Astronomy Group
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Hanna Gravitational Wave Physics and Astronomy Group

Name: CAREER: Enabling multimessenger astrophysics with real-time gravitational wave detection
Source: National Science Foundation (PHY-1454389)
Dates: 6/1/2015 - 5/30/2020
Roles: Chad Hanna (PI)
Sponsored Personnel: Becca Ewing, Ryan Magee, Cody Messick, Debnandini Mukherjee, Duncan Meacher, Sydney Chamberlain, Phoebe McClincy


In the last decades, astrophysicists and astronomers have studied the Universe for clues about what causes some of the most energetic transient events. It has long been thought that truly extreme objects such as black holes and neutron stars are responsible. Advanced instruments spanning the electromagnetic spectrum have provided a wealth of information regarding the transient Universe; however, many observations are unable to directly probe the dynamics of the systems in question. General relativity provides a way to map out the dynamics of massive, dense objects from a distance by encoding the motion as ripples in space-time known as gravitational waves. The personnel on this project led efforts within the LIGO Scientific Collaboration to detect transient gravitational waves from the merger of black holes and neutron stars in real-time, enabling prompt multi-wavelength follow-up observations shed new light onto the origin of transients. Discoveries were relayed to a network of follow-up observatories so that scientists were able to learn as much as possible about these events before they fade away. This research increased understanding of the fundamental nature of space, time and the properties of exotic states of matter and energy that are not accessible to Earth-based laboratories.


Research Highlights

First direct observation of gravitational waves from a binar black hole: GW150914 (Phys. Rev. Lett. 116, 061102)

PHY-1454389 funded in part the development and deployment of a real-time search for compact binary mergers known as GstLAL. The primary goal of this award was to discover compact binary mergers within seconds of the gravitational waves arriving at Earth in order to alert a broader astronomical community for prompt follow-up observations. The hope was to enable the identification of prompt electromagnetic and/or other astroparticle counterparts. The real-time gravitational wave search ran throughout advanced LIGO's first observing run from September 2015 to January 2016. From September to November the analysis targeted sources that have historically been thought to have the most likely electromagnetic counterparts, namely, sources containing at least one neutron star. Starting in November the real-time analysis parameter space was extended to include binary black holes with total mass up to 100 solar masses. The analysis identified candidates within approximately 1 minute of the signals arriving at Earth. Candidates were reported to the gravitational wave candidate database where rapid sky localization, parameter estimation and other follow-up task were started immediately. Once a candidate was identified, the rapid response team assembled at each LIGO observatory and analysts funded by this project joined by teleconference to help vet candidate events. Events that passed were circulated to the observing partners through a private gamma ray coordinates (GCN) circular.


The gravitational wave signal dubbed GW151226 was successfully detected by the gstlal inspiral pipeline and team members on Christmas day within 70s of the signal arriving at Earth. The online analysis was able to confidently establish that the system was likely to be a binary black hole and that its false alarm rate was less than 1 / 1000 years. This event firmly established gravitational wave astronomy by helping to refine the rate of binary black hole mergers as one that should yield regular detections over advanced LIGO's lifetime. GW151226 was the first gravitational wave event to be identified by a modeled search for compact binary mergers. The first event, GW150914, in part due to its high amplitude and in part due to its short duration, was first identified by a generic transient gravitational wave search and did not require matched filtering for detection. GW151226 on the other hand had a signal amplitude that was considerably lower than the noise and a duration in LIGO's band that was significantly longer. The generic transient gravitational wave algorithms did not detect GW151226. Thus real-time matched filtering was necessary for its identification, which is the major objective of this project. Throughout O1, the GstLAL analysis was also operated in an 'offline' mode to search the entire parameter space of compact binaries from 1-600 solar masses. Members of the team funded by PHY-1454389 helped to develop and run a search for binary black holes that detected the first ever gravitational wave event, GW150914, with a significance in excess of 5 sigma. Additionally, large simulation campaigns conducted in part by the team supported by PHY-1454389 helped to establish the first directly measured coalescence rate of binary black holes in the Universe.

Observation of the first ever binary neutron star meger in gravitational waves and across the electromagnetic spectrum (The Astrophysical Journal Letters, Volume 848, Number 2).

Personnel supported by this award conducted a real-time search for neutron star and black hole mergers in advanced LIGO's second observing run (O2). Furthermore, personnel have conducted and are continuing to conduct an offline reanalysis of O2 data. Personnel conducted research and development efforts associated with these activities through co-developing the GstLAL software infrastructure. Our work was in collaboration with a team of other members of the LIGO and Virgo collaborations including University of Tokyo, University of Wisconsin-Milwaukee and Caltech. We aimed to enable a few novel features in O2 searches. Namely, we developed and depolyed a real-time single detector gravitational wave search. We also worked on and deployed some additional zero-latency signal processing algorithms, which should help us to meet our eventual goal of ~seconds of detection latency. Our team provided the promptest and most significant result for the first ever three detector gravitational wave detection involving advanced LIGO and advanced Virgo known as GW170814 with a 30 second detection time and a false alarm rate estimate of 1 / 80,000 years. Three days later our team provided the only detection of the first gravitational waves from a binary neutron star merger known as GW170817 within 7 minutes of arriving at earth with an estimated 1 / 10,000 years false alarm rate. It was detected in a single gravitational wave detector, which justified the effort put forward to enable this. GW170817 was the first multimessenger source including gravitational waves since it was also observed in gamma rays, x-rays, UV, optical, infra-red, and radio wavelengths. Additionally, our team provided offline significance estimates of GW170104 and GW170608.

After the end of O2, personnel on this project refined analysis techniques and worked to increase the reach of the compact binary search in preparation for advanced LIGO's third observing run (O3). In the interim between O2 and O3, personnel on this project conducted a search for sub-solar mass compact binaries and constrained such objects as a component of dark matter assuming that they were primordial black holes. Personnel on this project conducted offline analysis for Advanced LIGO's third observing run. This run marked the most sensitive gravitational wave data ever taken with an average of six gravitational wave detections per month. These results will appear soon as an update to the Gravitational Wave Transient Catalog (GWTC).

Outreach Highlights

Penn State Gravitational Wave Summer Camp: Abby Drey Centre Daily Times

The PI is committed as a teacher / scholar to engage in the education of students through participating in K-12 curriculum writing and hosting summer school education events as part of this award. During 2016, we developed curriculum on gravitational wave astronomy for high school students and provided hands on training at the first ever gravitational wave summer school at Penn State. This targeted local high school students, some from rural areas. Thanks to the support of this award as well as support from the Institute for Gravitation and the Cosmos and the Institute for CyberScience, we were able to offer the camp free of charge. Students learned about gravitational waves from compact binary signals, data analysis and high throughput computing. We assembed a small high throughput computing cluster to demonstrate how real-time gravitational wave searches work. On Halloween 2017 we celebrated dark matter day by hosting a booth in Penn State's HUB center in collaboration with the experimental dark matter faculty at PSU. The HUB center has tens of thousands of students, faculty and staff pass through daily. Among other things, our booth described how gravitational waves might help us to understand dark matter Personnel on this project developed a 'Carrilon of Black Holes' which explored how constructing a musical instrument from a set of black holes was possible (in theory by analogy between gravitational waves and sound) and had a timbre quite distinct from other musical instruments.


1. "Multi-messenger astrophysics." M{\'e}sz{\'a}ros, P{\'e}ter, et al. Nature Reviews Physics. 1 10 585--599 (2019)
2. "Search for intermediate mass black hole binaries in the first and second observing runs of the Advanced LIGO and Virgo network." Abbott, BP, et al. Physical Review D. 100 6 064064 (2019)
3. "Search for subsolar mass ultracompact binaries in Advanced LIGO’s second observing run." Abbott, Benjamin P, et al. Physical review letters. 123 16 161102 (2019)
4. "Search for gravitational waves from a long-lived remnant of the binary neutron star merger GW170817." Abbott, Benjamin P, et al. The Astrophysical Journal. 875 2 160 (2019)
5. "GWTC-1: a gravitational-wave transient catalog of compact binary mergers observed by LIGO and Virgo during the first and second observing runs." Abbott, BP, et al. Physical Review X. 9 3 031040 (2019)
6. "Binary black hole population properties inferred from the first and second observing runs of Advanced LIGO and Advanced Virgo." Abbott, BP, et al. The Astrophysical Journal Letters. 882 2 L24 (2019)
7. "The GstLAL template bank for spinning compact binary mergers in the second observation run of Advanced LIGO and Virgo." Mukherjee, Debnandini, et al. arXiv e-prints. arXiv--1812 (2018)
8. "A Carillon of Black Holes." George, Daniel, et al. arXiv preprint arXiv:1803.08090. (2018)
9. "The electromagnetic counterpart of the binary neutron star merger LIGO/Virgo GW170817. I. Discovery of the optical counterpart using the dark energy camera." Soares-Santos, Marcelle, et al. The Astrophysical Journal Letters. 848 2 L16 (2017)
10. "GW170104: observation of a 50-solar-mass binary black hole coalescence at redshift 0.2." Scientific, LIGO, et al. Physical review letters. 118 22 221101 (2017)
11. "Multi-messenger observations of a binary neutron star merger." Monitor, Fermi Gamma-ray Burst, et al. Astrophysical Journal Letters. 848 2 (2017)
12. "Analysis framework for the prompt discovery of compact binary mergers in gravitational-wave data." Messick, Cody, et al. Physical Review D. 95 4 042001 (2017)
13. "Search for intermediate mass black hole binaries in the first observing run of Advanced LIGO." Abbott, Benjamin P, et al. Physical Review D. 96 2 022001 (2017)
14. "Search for continuous gravitational waves from neutron stars in globular cluster NGC 6544." Abbott, Benjamin P, et al. Physical Review D. 95 8 082005 (2017)
15. "GW170608: observation of a 19 solar-mass binary black hole coalescence." Abbott, Benjamin P, et al. The Astrophysical Journal Letters. 851 2 L35 (2017)
16. "Gravitational waves and gamma-rays from a binary neutron star merger: GW170817 and GRB 170817A." Abbott, Benjamin P, et al. The Astrophysical Journal Letters. 848 2 L13 (2017)
17. "Upper limits on the rates of binary neutron star and neutron star--black hole mergers from advanced LIGO’s first observing run." Abbott, Benjamin P, et al. The Astrophysical Journal Letters. 832 2 L21 (2016)
18. "The rate of binary black hole mergers inferred from Advanced LIGO observations surrounding GW150914." Abbott, Benjamin P, et al. The Astrophysical journal letters. 833 1 L1 (2016)
19. "Observation of gravitational waves from a binary black hole merger." Abbott, Benjamin P, et al. Physical review letters. 116 6 061102 (2016)
20. "GW151226: observation of gravitational waves from a 22-solar-mass binary black hole coalescence." Abbott, Benjamin P, et al. Physical review letters. 116 24 241103 (2016)
21. "GW150914: First results from the search for binary black hole coalescence with Advanced LIGO." Abbott, Benjamin P, et al. Physical Review D. 93 12 122003 (2016)
22. "GW150914: The Advanced LIGO detectors in the era of first discoveries." Abbott, Benjamin P, et al. Physical review letters. 116 13 131103 (2016)
23. "Binary black hole mergers in the first advanced LIGO observing run." Abbott, Benjamin P, et al. Physical Review X. 6 4 041015 (2016)
24. "Likelihood-ratio ranking statistic for compact binary coalescence candidates with rate estimation." Cannon, Kipp, Hanna, Chad, Peoples, Jacob. arXiv preprint arXiv:1504.04632. (2015)

1. Chad Hanna "Gravitational Waves: the New Window to the Universe" Pheno 2018, University of Pittsburgh, Pittsburgh, PA May 8, 2018 (Invited)
2. Chad Hanna "Enabling multi-messenger astrophysics with LIGO" Canadian Institute for Theoretical Astrophysics Seminar, Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, ON, Canada November 20, 2017 (Invited)
3. Chad Hanna "Figuring out the prompt emission physics of binary neutron star mergers: Challenges in data analysis and coordinated searches" Lights Sound Action, Perimeter Institute for Theoretical Physics, Waterloo, Ontario, Canada November 6, 2017 (Invited)
4. Chad Hanna "The next frontier of gravitational wave physics and astronomy" NASA-Goddard Astrophysics, NASA-Goddard, Greenbelt, MD October 31, 2017 (Invited)
5. Chad Hanna "The next frontier of gravitational wave physics and astronomy" Physics Colloquium, Penn State, University Park, PA October 19, 2017 (Invited)
6. Chad Hanna "Results from LIGO Event GW170104" Eastern Gravity Meeting, Penn State, University Park, PA June 9, 2017 (Contributed)
7. Chad Hanna "Binary black hole observations with Advanced LIGO" Gravitational Wave Physics and Astronomy Workshop, Laboratoire d’Annecy-le-Vieux de Physique des Particules, Annecy, France May 31, 2017 (Invited)
8. Chad Hanna "Future Prospects for LIGO Data Analysis for Compact Binaries" LIGO-LSST workshop, Columbia University, New York, New York May 13, 2017 (Invited)
9. Chad Hanna "Panel: the future of gravitational wave instruments and analyses" LIGO-LSST workshop, Columbia University, New York, New York May 13, 2017 (Invited)
10. Chad Hanna "The one-hundred year quest to discover gravitational waves" Millersville University, Millersville, Pennsylvania March 8, 2017 (Invited)
11. Chad Hanna "GW151226: Observation of Gravitational Waves from a 22-Solar-Mass Binary" Miami 2016, University of Miami, Ft. Lauderdale, FL, USA December 19, 2016 (Invited)
12. Chad Hanna "Compact Binary Searches in the Second Advanced LIGO Observing Run" RESCEU Symposium, University of Tokyo, Tokyo, Japan December 7, 2016 (Invited)
13. Chad Hanna "Challenges in measurement and interpretation" Physics at the extreme, Institute for Gravitation and the Cosmos, State College, PA, USA December 2, 2016 (Invited)
14. Chad Hanna "The Dawn of Gravitational Wave Astronomy" Perimeter Institute for Theoretical Physics Colloquium, Waterloo, Ontario, Canada May 18, 2016 (Invited)
15. Chad Hanna "The Dawn of Gravitational Wave Astronomy" Friedman Lecture in Astronomy, Penn State, Penn State, University Park, PA, USA April 28, 2016 (Invited)
16. Chad Hanna "Invited" Physics and Astronomy Colloquium, West Virginia University, Morgantown, WV, USA April 27, 2016 ()
17. Chad Hanna, Duncan Meacher, Cody Messick "Advanced LIGO Low-latency Search For Compact Binary Coalescence" April APS, APS, Salt Lake City, UT, USA April 17, 2016 (Contributed)
18. Chad Hanna "Searches for GW transients in Advanced LIGO" April APS, APS, Salt Lake City, UT, USA April 16, 2016 (Invited)
19. Chad Hanna "Advanced LIGO's first observing run" Astronomy & Astrophysics Colloquium, Penn State, University Park, PA, USA February 17, 2016 (Invited)
20. Chad Hanna "Gravitational wave astronomy with advanced LIGO" Kavli Institute for Astrophysics Colloquium, MIT, Cambridge, MA, USA December 1, 2015 (Invited)
21. Chad Hanna "Gstlal Inspiral Search" LIGO Laboratory, MIT, Cambridge, MA, USA November 30, 2015 (Invited)
22. Chad Hanna "Advanced LIGO" The Dark Side of Gravity, Perimeter Institute, Waterloo, ON, Canada June 24, 2015 (Invited)
1. Sydney Chamberlain "Listening to the Universe with Dead Stars and Lasers." State College Area High School, State College, Pennsylvania, USA February 2016 (Invited)
2. Sydney Chamberlain "Listening to the Universe with Dead Stars and Lasers." Pacific University, Portland, Oregon, USA. February 2017 (Invited)
3. Sydney Chamberlain "Dancing with the Stars: the Unheard Symphonies of Dead Stars." Science Unwrapped Lecture Series, Utah State University, Logan, Utah, USA October 2016 (Invited)
4. Sydney Chamberlain "Matched Filtering: One Secret to Extracting Tiny Signals from Loud Noise" Primordial Universe and Gravity Discussion, Penn State University, State College, PA, USA December 2016 (Contributed)
5. Sydney Chamberlain "Listening to the Universe with Dead Stars and Lasers." Salt Lake Astronomical Society, Salt Lake City, Utah, USA April 2016 (Invited)
6. Sydney Chamberlain "Coffeeshop Astrophysics: An Adventure in Public Outreach" American Physical Society Meeting, Salt Lake City, UT, USA. April 2016 (Contributed)
1. Becca Ewing "LIGO Sub-threshold Alerts for the Swift Observatory" April APS meeting, American Physical Society, Washington DC (held virtually) April 18, 2020 (Contributed)
2. Becca Ewing "LIGO sub-threshold gravitational wave alerts for the Swift Observatory" Primordial Universe and Gravity Seminar, Institute for Gravitation and the Cosmos, Pennsylvania State University October 28, 2020 (Contributed)
1. Duncan Meacher "Open challenges and future directions for LIGO searches: Low-latency analysis" Massachusetts Institute of Technology November 2017 (Invited)
2. Duncan Meacher "Open challenges and future directions for LIGO searches: Low-latency analysis" The Dawning Era of Gravitational-Wave Astrophysics, Aspen, CO, USA February 2017 (Contributed)
1. Ryan Magee "Subsolar mass black holes as a probe of the dark matter" Nikhef Gravity Seminar, Amsterdam, Netherlands November 15, 2019 (Invited)
2. Ryan Magee "Panelist for discussion on primordial black holes" Gravitational Wave Probes of Fundamental Physics, Amsterdam, Netherlands November 11, 2019 (Invited)

1. "How Fast Can Gravitational Wave Detection Get?" Wired 3/9/2018 (Chad Hanna)
2. "LIGO announcement vaults astronomy out of its silent movie era into the talkies." The Conversation 10/16/2017 (Chad Hanna)
3. "Penn State participates in Nobel-winning physics project" Centre Daily Times 10/3/2017 (Chad Hanna)
4. "Gravitational Waves From Novelty to Science (Cover Story)" Astronomy Magazine 11/1/2017 (Chad Hanna)
5. "3rd Gravitational Wave Detection Is About Much More Than Black Holes" Discover Magazine 6/1/2017 (Chad Hanna)
6. "Colliding stars spark rush to solve cosmic mysteries" Nature 10/16/2017 (Chad Hanna)
7. "Gravitational waves + new clues from space reveal new way to make a black hole" Penn State Science News 10/16/2017 (Chad Hanna)
8. "Institute for CyberScience lecture to explore gravitational wave astronomy" Penn State News 6/1/2017 (Chad Hanna)
9. "New gravity waves hit Earth after record-breaking trip through space" Penn State Science News 6/1/2017 (Chad Hanna)
10. "Surfing the Gravity Waves, Smart Talk" WITF Public Radio 10/19/2017 (Chad Hanna)
11. "LIGO Detects a Second Set of Gravitational Waves" Astronomy Magazine 6/15/2016 (Chad Hanna)
12. "LIGO Has Detected Gravitational Waves (Again)" The Atlantic 6/15/2016 (Chad Hanna)
13. "What happens when LIGO texts you to say it's detected one of Einstein's predicted gravitational waves" The Conversation; reprinted by Popular Science 2/11/2016 (Chad Hanna)
14. "Gravitational waves detected from more colliding black holes" Canadian Broadcasting Corporation 6/15/2016 (Chad Hanna)
15. "Summer camp takes students out of this world (Centre Daily Times)" Centre Daily times 7/22/2016 (Chad Hanna)
16. "Prepare for an Explosion of Gravitational Wave Detections " Discover Magazine 4/11/2016 (Chad Hanna)
17. "LIGOs Second Gravitational Wave Detection Refines Black Hole Theories" Discover Magazine 6/15/2016 (Chad Hanna)
18. "LIGO’s Second Black Hole Merger Leaves No Doubt" Forbes 6/15/2016 (Chad Hanna)
19. "The black-hole collision that reshaped physics" Nature 3/23/2016 (Chad Hanna)
20. "LIGO detects whispers of another black-hole merger" Nature 6/15/2016 (Chad Hanna)
21. "LIGO sees second gravitational waves created by colliding black holes" Nesweek 6/15/2016 (Chad Hanna)
22. "Penn State researcher sees physics work come full circle" Penn State News 2/11/2016 (Chad Hanna)
23. "Chad Hanna appointed as the Norman and Trygve Freed Early Career Professor in Physics" Penn State Science News 7/29/2016 (Chad Hanna)
24. "New gravitational-wave finder scores again" Penn State News 6/15/2016 (Chad Hanna)
25. "Gravitational Wave Detection Heralds New Era." Sky and Telescope 2/11/2016 (Chad Hanna)
26. "Gravitational waves detected for second time" USA Today 6/15/2016 (Chad Hanna)
27. "Albert Einstein Was Right" US News and World Report 2/11/2016 (Chad Hanna)
28. "Einstein predicted gravitational waves 100 years ago. Here's what it took to prove him right" The Washington Post 2/12/2016 (Chad Hanna)
29. "Has giant LIGO experiment seen gravitational waves?" Nature 9/29/2015 (Chad Hanna)