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Sciences and Exploration Directorate

Bernard Joseph Kelly

(RESEARCH SCIENTIST)

Bernard Joseph Kelly's Contact Card & Information.
Email: bernard.j.kelly@nasa.gov
Phone: 301.286.7243
Org Code: 663
Address:
NASA/GSFC
 Mail Code 663
 Greenbelt, MD 20771
Employer: UMBC Univ. of MD, Baltimore County

Brief Bio

Bernard studied Experimental and Mathematcal Physics at University College, Dublin. After a two-year break as a financial mathematician, he attended graduate school in Penn State University, studying numerical relativity under Dr Pablo Laguna (now in Georgia Tech), graduating with a Ph.D. in 2004.

From 2004 to 2006, Bernard was a postdoctoral scholar in the University of Texas, Brownsville, working with Manuela Campanelli, Carlos Lousto, and Yosef Zlochower (now at the Rochester Institiute of Technology). Bernard's research centered on the Lazarus Project, an effort to extend then-short-lived black-hole-binary merger simulations by mapping their later stages to a more stable perturbative code.

In late 2006, Bernard came to NASA Goddard as an NPP with the Gravitational Astrophysics Laboratory, working with Joan Centrella, John Baker, and the numerical relativity group there. He continues to work at GSFC, as a CRESST Assistant Research Scientist affiliated with the Center for Space Sciences and Technology at the University of Maryland, Baltimore County.

Research Interests

Mergers of black-hole binaries in astrophysical environments.

Astrophysics: Theory & Modeling

Black holes produce no electromagnetic radiation, by definition. However, astrophysical black holes will typically live in the vicinity of considerable amounts of free baryonic matter threaded by magnetic fields, often in the form of accretion disks. The interaction of black holes with this matter can potentially lead to observable electromagnetic signals, with characteristic changes around the time of merger.

I simulate the merger of black holes in plasma environments to try to establish robust predictions for these signals, which can be seen by different ground-based and space-based telescopes, at the same time that gravitational-wave observatories (such as LIGO, or the planned ESA-led LISA mission) "hear" the black-hole merger itself.

These simulations require solving the complete set of Einstein's equations of general relativity in 3D, along with the equations of ideal magnetohydrodynamics (MHD).

Implicit-Rotating Source Gravitational-Wave Templates

Astrophysics: Gravitational Waves

The late-merger and ringdown portion of black-hole-binary coalescence is brief, but extremely powerful. It also yields the hardest-to-model segment of the continuous gravitational-wave emission, where post-Newtonian theory breaks down and the linear ringdown regime is not yet applicable. Accurate modeling of this regime requires the solution of the full nonlinear Einstein Equations of General Relativity using supercomputers. As such simulations are expensive, and the binary configuration space so large, we must synthesize the results of intelligently chosen configurations to form template banks.

Existing template banks concentrate mostly on the long-lasting inspiral segment of BH coalescences, either neglecting the merger, or treating it in an approximate way that may neglect important nonlinear processes. Using the observed link between the dominant (quadrupole) and leading sub-dominant angular modes from BH mergers, we have proposed a simple "implicit rotating source" (IRS) picture of the binary that holds through late inspiral and merger, and suggests a simple but powerful way to encode important nonlinear features of the merger waveform modes.

Characterizing Strong-Gravity Regions of Spacetime

Astrophysics: Black Holes

As the leading classical theory of gravity, general relativity is used for precision measurements of planetary, stellar, and galactic motion, and has given rise to extraordinary predictions of now-observed phenomena such as black holes and gravitational waves. Most cutting-edge computational treatments of the "strong gravity" regions of spacetimes -- e.g. the remnant after the merger of two neutron stars or smaller black holes -- require a multi-code, multi-platform approach to capture the important physics of the event, passing off data from one code to another. Very often, the simulation codes on each side of this data exchange model the black-hole spacetime very differently (e.g. the horizon might be a simple coordinate sphere r = M in one code, but a distorted spheroid in the other). It is vital that we develop more robust ways of mapping one spacetime to another to ensure that all field quantities are correctly interpreted, so that self-consistent predictions can be made for potential observable signals.

I've been working to solve this problem with Weyl curvature invariants based on the Newman-Penrose formalism. These are scalar fields with well-understood values in Kerr spacetimes, with simple dependencies on Kerrr-Boyer-Lindquist (KBL) coordinates. By calculating them for numerically evolved spacetimes, we can develop a dictionary between numerical coordinates and KBL, allowing the correct mapping of other fields from one code to the other.

Current Projects

Physics of the Cosmos science support

Technology & Missions

Coordination between NASA HQ and scientists for the Physics of the Cosmos (PhysCOS) program, organization and oversight of activities for scientific meetings (e.g., American Astronomical Society, American Physical Society, etc.), and coordinating and managing outreach related to PhysCOS (i.e., preparing publications, brochures, maintaining and updating the website).

Gravitational-Wave Signatures of Massive Black Hole Formation

Theory & Modeling

Direct-collapse black holes (DCBHs) are an important component of the massive black hole population of the early universe, and their formation and early mergers will be prominent in the data stream of the Laser Interferometer Space Antenna (LISA). However, the population and binary properties of these early black holes are poorly understood, with masses, mass ratios, spins, and orbital eccentricities strongly dependent on the details of their formation, and the properties of the remaining exterior material (baryonic and non-baryonic), which may be substantial to the point of merger.


We propose to simulate the formation, collapse, and/or merger of such DCBH regions in order to extract the resulting gravitational-wave signals, and to assess the ability of LISA to detect and identify them.


Our approach for this work will involve cosmological simulation data produced with the Enzo code. We will identify regions of likely DCBH formation in this data, and use Newtonian methods to follow these regions to the point of strong-field collapse. We will then employ fully dynamical general relativistic hydrodynamics (GRHD) to simulate the collapse of these DCBHs, and the merger of any resulting DCBH binaries, using standard techniques to extract the resulting gravitational radiation, and assess its observational potential for LISA.


This work will help prepare for the overall analysis and interpretation of the LISA data stream by investigating a less-understood LISA source class, and help deepen our understanding of the early gravitational Universe.

Positions/Employment

CRESST Assistant Research Scientist

University of Maryland Baltimore County - 1000 Hilltop Circle, Baltimore, MD 21250

October 2015 - Present

CRESST Research Associate

University of Maryland Baltimore County - NASA Goddard Space Flight Center

September 2009 - October 2015

NASA Postdoctoral Fellow

Oak Ridge Associated Universities - NASA Goddard Space Flight Center

September 2006 - August 2009

Postdoctoral Researcher

Dept of Physics and Astronomy, University of Texas at Brownsville - 80 Fort Brown, Brownsville TX 78520

September 2004 - August 2006

Education

  • B. Sc. in Experimental Physics and Mathematical Physics (1995) University College, Dublin
  • M. Sc. in Mathematical Physics (1996) University College, Dublin
  • Ph. D. in Physics (2004) Pennsylvania State University

Professional Service

Refereeing

  • Referee for Physical Review D, Physical Review Letters, Classical and Quantum Gravity
  • 2016 Reviewer of the Year, Classical and Quantum Gravity
  • Member of Classical and Quantum Gravity Advisory Panel (Jan 2018 - Jan 2020)

Grants

Gravitational-Wave Signatures of Massive Black Hole Formation

LISA Preparatory Science - NASA - Awarded: 2023-08-08


Dates:  - 

Amount $644,836

Publications

Refereed

2025. "Gravitational-Wave Signatures of Massive Black Hole Formation.", Classical and Quantum Gravity, [10.1088/1361-6382/ae2413] [Journal Article/Letter]

2025. "Waveform modelling for the Laser Interferometer Space Antenna.", Living Reviews in Relativity, 28 (1): 9 [10.1007/s41114-025-00056-1] [Journal Article/Letter]

2025. "A Parameter Study of the Electromagnetic Signatures of an Analytical Mini-disk Model for Supermassive Black Hole Binary Systems.", The Astrophysical Journal, 979 (2): 155 [10.3847/1538-4357/ad9c74] [Journal Article/Letter]

2025. "Toward 2D dynamo models calibrated by global 3D relativistic accretion disk simulations.", Physical Review D, 111 (2): 023040 [10.1103/physrevd.111.023040] [Journal Article/Letter]

2023. "Addition of tabulated equation of state and neutrino leakage support to illinoisgrmhd.", Physical Review D, 107 (4): 044037 [10.1103/physrevd.107.044037] [Journal Article/Letter]

2022. "Handing off the outcome of binary neutron star mergers for accurate and long-term postmerger simulations.", Physical Review D, 106 (8): 083015 [10.1103/physrevd.106.083015] [Journal Article/Letter]

2021. "HARM3D+NUC: A new method for simulating the post-merger phase of binary neutron star mergers with GRMHD, tabulated EOS and neutrino leakage.", Astrophysical Journal, 919 (2): 95-110 [10.3847/1538-4357/ac1119] [Journal Article/Letter]

2021. "Electromagnetic emission from a binary black hole merger remnant in plasma: Field alignment and plasma temperature.", Physical Review D, 103 (6): 063039 [10.1103/physrevd.103.063039] [Journal Article/Letter]

2019. "The Event Horizon General Relativistic Magnetohydrodynamic Code Comparison Project.", The Astrophysical Journal Supplement Series, 243 (2): 26 [10.3847/1538-4365/ab29fd] [Journal Article/Letter]

2018. "Electromagnetic Chirps from Neutron Star-Black Hole Mergers.", The Astrophysical Journal, 853 123 [10.3847/1538-4357/aaa08b] [Journal Article/Letter]

2017. "Prompt electromagnetic transients from binary black hole mergers .", Physical Review D, 96 123003 [10.1103/PhysRevD.96.123003] [Journal Article/Letter]

2017. "Prompt Electromagnetic Transients from Binary Black Hole Mergers.", Physical Review D, 96 123003 [Journal Article/Letter]

2014. "Improved moving puncture gauge conditions for compact binary evolutions.", Physical Review D, 90 064032 [Full Text] [10.1103/PhysRevD.90.064032] [Journal Article/Letter]

2013. "Systematic biases in parameter estimation of binary black-hole mergers.", Physical Review D, 87 104003 [10.1103/PhysRevD.87.104003] [Journal Article/Letter]

2013. "Decoding mode mixing in black-hole merger ringdown.", Physical Review D, 87 084004 [10.1103/PhysRevD.87.084004] [Journal Article/Letter]

2011. "Mergers of black-hole binaries with aligned spins: Waveform characteristics.", Physical Review D, 84 084009 [10.1103/PhysRevD.84.084009] [Journal Article/Letter]

2011. "Hybrid black-hole binary initial data.", Classical and Quantum Gravity, 28 134003 [doi:10.1088/0264-9381/28/13/134003] [Journal Article/Letter]

2011. "Merging Black Holes.", Contemporary Physics, 52 1 [10.1080/00107514.2010.520908] [Journal Article/Letter]

2010. "The final merger of black-hole binaries.", Annual Reviews of Nuclear and Particle Science, 60 75 [10.1146/annurev.nucl.010909.083246] [Journal Article/Letter]

2010. "Post-Newtonian Initial Data with Waves: Progress in Evolution.", Classical and Quantum Gravity, 27 114005 [doi:10.1088/0264-9381/27/11/114005] [Journal Article/Letter]

2010. "Impact of mergers on LISA parameter estimation for nonspinning black hole binaries.", Physical Review D, 81 064014 [10.1103/PhysRevD.81.064014] [Journal Article/Letter]

2010. "Black-hole binaries, gravitational waves, and numerical relativity.", Reviews of Modern Physics, 82 3069-3119 [Full Text] [10.1103/RevModPhys.82.3069] [Journal Article/Letter]

2010. "Test of a General Formula for Black Hole Gravitational Wave Kicks.", The Astrophysical Journal, 719 1427 [Full Text] [10.1088/0004-637X/719/2/1427] [Journal Article/Letter]

2010. "Observing mergers of nonspinning black-hole binaries.", Physical Review D, 82 024014 [Full Text] [10.1103/PhysRevD.82.024014] [Journal Article/Letter]

2010. "Modeling Flows around Merging Black Hole Binaries.", The Astrophysical Journal Letters, 711 L89 [Full Text] [10.1088/2041-8205/711/2/L89] [Journal Article/Letter]

2009. "Samurai project: Verifying the consistency of black-hole-binary waveforms for gravitational-wave detection.", Physical Review D, 79 084025 [Full Text] [10.1103/PhysRevD.79.084025] [Journal Article/Letter]

2009. "LISA parameter estimation using numerical merger waveforms.", Classical and Quantum Gravity, 26 094026 [Full Text] [10.1088/0264-9381/26/9/094026] [Journal Article/Letter]

2009. "Status of NINJA: the Numerical INJection Analysis project.", Classical and Quantum Gravity, 26 4008 [Full Text] [10.1088/0264-9381/26/11/114008] [Journal Article/Letter]

2009. "Testing gravitational-wave searches with numerical relativity waveforms: results from the first Numerical INJection Analysis (NINJA) project.", Classical and Quantum Gravity, 26 5008 [Full Text] [10.1088/0264-9381/26/16/165008] [Journal Article/Letter]

2008. "Anatomy of the binary black hole recoil: A multipolar analysis.", Physical Review D, 77 044031 [10.1103/PhysRevD.77.044031] [Journal Article/Letter]

2008. "Data-analysis driven comparison of analytic and numerical coalescing binary waveforms: Nonspinning case.", Physical Review D, 77 024014 [10.1103/PhysRevD.77.024014] [Journal Article/Letter]

2008. "Mergers of nonspinning black-hole binaries: Gravitational radiation characteristics.", Physical Review D, 78 044046 [Full Text] [10.1103/PhysRevD.78.044046] [Journal Article/Letter]

2008. "Modeling Kicks from the Merger of Generic Black Hole Binaries.", The Astrophysical Journal, 682 L29 [Full Text] [10.1086/590927] [Journal Article/Letter]

2007. "Approaching faithful templates for non-spinning binary black holes using the effective-one-body approach.", Physical Review D, 76 104049 [10.1103/PhysRevD.76.104049] [Journal Article/Letter]

2007. "Consistency of post-Newtonian waveforms with numerical relativity.", Physical Review Letters, 99 181101 [10.1103/PhysRevLett.99.181101] [Journal Article/Letter]

2007. "Black hole puncture initial data with realistic gravitational wave content.", Physical Review D, 76 024008 [10.1103/PhysRevD.76.024008] [Journal Article/Letter]

2007. "Recoiling from a kick in the head-on collision of spinning black holes.", Physical Review D, 76 104026 [Full Text] [10.1103/PhysRevD.76.104026] [Journal Article/Letter]

2007. "Binary black hole late inspiral: Simulations for gravitational wave observations.", Physical Review D, 75 124024 [Full Text] [10.1103/PhysRevD.75.124024] [Journal Article/Letter]

2007. "Modeling Kicks from the Merger of Nonprecessing Black Hole Binaries.", The Astrophysical Journal, 668 1140 [Full Text] [10.1086/521330] [Journal Article/Letter]

2006. "The Lazarus Project. II. Spacelike extraction with the quasi-Kinnersley tetrad.", Physical Review D, 73 064005 [10.1103/PhysRevD.73.064005] [Journal Article/Letter]

2005. "Black hole head-on collisions and gravitational waves with fixed mesh-refinement and dynamic singularity excision.", Physical Review D, 71 124042 [10.1103/PhysRevD.71.124042] [Journal Article/Letter]

2004. "Impact of densitized lapse slicings on evolutions of a wobbling black hole.", Physical Review D, 69 024012 [10.1103/PhysRevD.69.024012] [Journal Article/Letter]

2004. "Black-hole spectroscopy: testing general relativity through gravitational-wave observations.", Classical and Quantum Gravity, 21 787 [10.1088/0264-9381/21/4/003] [Journal Article/Letter]

2001. "Cure for unstable numerical evolutions of single black holes: Adjusting the standard ADM equations in the spherically symmetric case.", Physical Review D, 64 084013 [10.1103/PhysRevD.64.084013] [Journal Article/Letter]

Non-Refereed

2025. "Numerical relativity and gravitational waveforms.", Encyclopedia of Astrophysics, 3 485-498 [10.1016/b978-0-443-21439-4.00124-3] [Article in Book]

Selected Public Outreach

Ask an Astrophysicist

November 2011 - December Present

Volunteer for one-week shifts as part of two-person team answering questions on astronomy & astrophysics, collected through the Ask an Astrophysicist web page.

NASA Science Live: Black Holes 101

November 2019 - November 2019

Participated in an episode of NASA's Science Live program, discussing what black holes are, and how we deterct them.

Professional Societies

American Physical Society

1999 - Present

International Society on General Relativity and Gravitation

2007 - Present

Institute of Physics (U.K.)

2008 - Present

American Astronomical Society

2013 - Present

Contact Us

For general inquiries about the Sciences and Exploration Directorate.

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301-286-6066 jocelyn.m.lynch@nasa.gov
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Project Support Specialist

301-286-6066 ellie.jeffries@nasa.gov
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