A New Approach To Rapidly Localize Gravitational Waves To Coordinate Prompt Follow-Up Observations

Black Hole and Neutron Star

Artist’s illustration of a black hole and neutron star orbiting each other and about to merge. Credit: Carl Knox, OzGrav-Swinburne University

Multimessenger astronomy is an emerging field that aims to study astronomical objects using different ‘messengers’ or sources, like electromagnetic radiation (light), neutrinos, and gravitational waves. This field gained enormous recognition after the joint detection of gravitational waves and gamma-ray bursts in 2017. Gravitational waves can be used to identify the sky direction of an event in space and alert conventional telescopes to follow-up for other sources of radiation. However, following up on prompt emissions would require a rapid and accurate localization of such events, which will be key for joint observations in the future.

The conventional method to accurately estimate the sky direction of gravitational waves is tedious—taking a few hours to days—while a faster online version needs only seconds. There is an emerging capacity from the LIGO-Virgo collaboration to detect gravitational waves from electromagnetic-bright binary coalescences, tens of seconds before their final merger, and provide alerts across the world.

The goal is to coordinate prompt follow-up observations with other telescopes around the globe to capture potential electromagnetic flashes within minutes from the mergers of two neutron stars, or a neutron star with a black hole—this was not possible before.

The University of Western Australia’s SPIIR team is one of the world leaders in this area of research. Determining sky directions within seconds of a merger event is crucial, as most telescopes need to know where to point in the sky. In our recently accepted paper,[1] led by three visiting students (undergraduate and Masters by research) at the OzGrav-UWA node, we applied analytical approximations to greatly reduce the computational time of the conventional localization method while maintaining its accuracy. A similar semi-analytical approach has also been published in another recent study.[2]

The results from this work show great potential and will be integrated into the SPIIR online pipeline going forward in the next observing run. We hope that this work complements other methods from the LIGO-Virgo collaboration and that it will be part of some exciting discoveries.

Written by OzGrav PhD student Manoj Kovalam, University of Western Australia.


“Semianalytical approach for sky localization of gravitational waves” by Qian Hu, Cong Zhou, Jhao-Hong Peng, Linqing Wen, Qi Chu and Manoj Kovalam, 3 November 2021, Physical Review D.
DOI: 10.1103/PhysRevD.104.104008

“High speed source localization in searches for gravitational waves from compact object collisions” by Takuya Tsutsui, Kipp Cannon and Leo Tsukada, 22 February 2021, Physical Review D.
DOI: 10.1103/PhysRevD.103.043011

3 Comments on "A New Approach To Rapidly Localize Gravitational Waves To Coordinate Prompt Follow-Up Observations"

  1. BibhutibhusanPatel | December 24, 2021 at 12:30 am | Reply

    This is good to have a rational approch to locate the soùrce of Gravitational wave following the electromagnetic wave that emits as a result of metge of two neutron stars or one newtron star and a black hole.To get direction of such source in sky with its distance from the earth is too important is associated with ejection of neutrinos.Congratulation and thanks to the Authors for Observational Skills with techniques.

  2. BibhutibhusanPatel | December 24, 2021 at 12:47 am | Reply

    The merger source of two neutron stars or one neutron star and one black hole is associated with emission of electromagnetic wave & gravitational wave.These two waves are proportionsl while can be detected through application of Einstein’s General Relativity.However ejection of neutrinos confirms the measured values of direction and distance of this merger source from the earth as unique secondary phenomena.

  3. As far as I can check, the one and only GW event which has been fully corroborated by non-gravitational measurement is still GW 170817.

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