# Observation of Gravitational Waves from a Binary Black Hole Merger

**Authors:**  The LIGO Scientific Collaboration,  the Virgo Collaboration  
**arXiv:** [1602.03837](https://arxiv.org/abs/1602.03837)  
**Date:** 2016-02-11  
**Summary page:** https://www.summarizepaper.com/en/paper/1602.03837v1/

## Key points

- On September 14, 2015 at 09:50:45 UTC, LIGO detected a transient gravitational-wave signal from the merger of two black holes.
- The observed signal had a matched-filter signal-to-noise ratio of 24 and swept upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of $1.0 \times 10^{-21}$.
- The merging black holes had initial masses of $36^{+5}_{-4} M_\odot$ and $29^{+4}_{-4} M_\odot$, resulting in a final black hole mass of $62^{+4}_{-4} M_\odot.
- Approximately $3.0^{+0.5}_{-0.5} M_\odot c^2$ worth of energy was radiated in gravitational waves during the event.
- This discovery marked the first direct detection of gravitational waves and confirmed the existence of binary stellar-mass black hole systems, published in Physical Review Letters (PRL) under reference number PRL 116, 061102 (2016).

## Summary

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On September 14, 2015 at 09:50:45 UTC, the Laser Interferometer Gravitational-Wave Observatory (LIGO) made a groundbreaking discovery. It simultaneously detected a transient gravitational-wave signal from the merger of two black holes. The observed signal had a matched-filter signal-to-noise ratio of 24 and swept upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of $1.0 \times 10^{-21}$. This waveform aligned perfectly with the predictions of general relativity for the inspiral and merger of the black hole pair, followed by the ringdown of the resulting single black hole. The source of this remarkable signal was located at a luminosity distance of $410^{+160}_{-180}$ Mpc, corresponding to a redshift $z = 0.09^{+0.03}_{-0.04}$. In the source frame, it was estimated that the merging black holes had initial masses of $36^{+5}_{-4} M_\odot$ and $29^{+4}_{-4} M_\odot$, resulting in a final black hole mass of $62^{+4}_{-4} M_\odot$. During this cataclysmic event, approximately $3.0^{+0.5}_{-0.5} M_\odot c^2$ worth of energy was radiated in gravitational waves. These observations not only confirmed the existence of binary stellar-mass black hole systems but also marked the first direct detection of gravitational waves and the inaugural observation of a binary black hole merger in history. The significance level exceeded 5.1 {\sigma}, with a false alarm rate estimated to be less than one event per 203,000 years. This monumental discovery was published in Physical Review Letters (PRL) under reference number PRL 116, 061102 (2016), authored by members of both LIGO Scientific Collaboration and Virgo Collaboration teams. This groundbreaking discovery has been recognized as an important milestone in astrophysics and general relativity research, shedding new light on the mysteries of our universe.