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Electromagnetic Chirps from Neutron Star-Black Hole Mergers.
Jeremy D Schnittman1, Tito Dal Canton2, Jordan Camp3
1NASA Goddard Space Flight Center, Greenbelt, MD 20771, Joint Space-Science Institute, College Park, MD 20742, jeremy.schnittman@nasa.gov.
The Astrophysical Journal
|November 12, 2019
Summary
Researchers simulated the electromagnetic signal from a neutron star merging with a black hole. This "electromagnetic chirp" signal, influenced by relativistic effects, could be detected using methods similar to gravitational wave analysis.
Area of Science:
- Astrophysics
- General Relativity
- Computational Physics
Background:
- Neutron star-black hole mergers are key astrophysical events.
- Electromagnetic counterparts to gravitational waves provide crucial multi-messenger information.
- Relativistic effects significantly influence radiation propagation near compact objects.
Purpose of the Study:
- To calculate the electromagnetic signal emitted from a neutron star surface preceding its merger with a black hole.
- To investigate the impact of dynamic spacetimes and relativistic effects on this signal.
- To propose a method for detecting these electromagnetic signals.
Main Methods:
- Utilized a new version of the Monte Carlo radiation transport code, Pandurata, with dynamic spacetimes.
- Integrated photon geodesics from the neutron star surface to a distant observer or black hole capture.
- Modeled relativistic effects such as Doppler beaming and gravitational lensing.
Main Results:
- The calculated gamma-ray light curve exhibits a chirp signal, mirroring the gravitational waveform.
- Signal characteristics include a steadily increasing frequency and amplitude due to relativistic effects.
- The electromagnetic signal originates from the inspiraling neutron star's surface.
Conclusions:
- Electromagnetic chirps from neutron star-black hole mergers are theoretically predictable.
- These signals can be searched for using matched filtering algorithms, similar to gravitational wave detection.
- This provides a potential new avenue for multi-messenger astronomy.
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