Second Detection of Gravitational Waves

he LIGO team at CITA. From left to right: summer undergraduate student Aliya Babul, associate professor Harald Pfeiffer, PhD graduate student Heather Fong, and postdoctoral fellow Prayush Kumar. Credit: Diana Tyszko/University of Toronto

The LIGO team at CITA. From left to right: summer undergraduate student Aliya Babul, associate professor Harald Pfeiffer, PhD graduate student Heather Fong, and postdoctoral fellow Prayush Kumar.
Credit: Diana Tyszko/University of Toronto

On December 26, 2015 at 03:38:53 UTC, the twin detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) observed gravitational waves produced by the collision of two stellar-mass black holes. The black holes that emitted these waves are inferred to have masses of 14 and 8 solar masses, and the final black hole has a mass of 21 solar masses. This event, named GW151226, is the second direct detection of gravitational waves, the first detection being GW150914 on September 14, 2015.

Compared to the first gravitational wave detection, this new detection is from a binary of much lower total mass (22 solar masses compared to 65 solar masses), indicating that the cosmic population of merging black hole binaries is very diverse. This new system allowed also for the very first time to measure black hole spins: at least one of the black holes must be spinning.

The data release and tools to analyze data from LIGO’s first observation run can be downloaded at the LIGO Open Science Center.

CITA researchers have been actively involved in the data analysis of the event, contributing to the search pipelines that identified GW151226 and GW150914. In addition, they have contributed to estimating the rate of observable binary black hole mergers in the Universe. They have also helped develop the theoretical waveforms that are used for to determine the masses and spins of the identified events and performed cross-checks with supercomputer calculations of merging black holes. For details on CITA’s research in this rapidly evolving field of physics, please visit our research page.

Video here.

Published on: June 15, 2016

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