Dark Matter Identified?

The missing 3 suns worth of mass in this one event was converted to energy (light).

Actually, according to the article, 3 suns worth of mass was converted to gravitational waves 1.3 billion years ago last September 14th.

https://en.wikipedia.org/wiki/Gravitational_wave:

"LIGO observations[edit]

LIGO measurement of the gravitational waves at the Hanford (left) and Livingston (right) detectors, compared to the theoretical predicted values. Main article: First observation of gravitational waves

On 11 February 2016, the LIGOcollaboration announced thedetection of gravitational waves, from a signal detected at 09:50:45 GMT on 14 September 2015^[65] of two black holes with masses of 29 and 36 solar masses merging about 1.3 billion light years away. During the final fraction of a second of the merger, it released more than 50 times the power of all the stars in the observable universe combined.^[66] The signal increased in frequency from 35 to 250 Hz over 10 cycles (5 orbits) as it rose in strength for a period of 0.2 second.^[9] The mass of the new merged black hole was 62 solar masses. Energy equivalent to three solar masses was emitted as gravitational waves.^[67] The signal was seen by both LIGO detectors in Livingston and Hanford, with a time difference of 7 milliseconds due to the angle between the two detectors and the source. The signal came from the Southern Celestial Hemisphere, in the rough direction of (but much further away than) the Magellanic Clouds.^[8] The confidence level of this being an observation of gravitational waves was 99.99994%.^[67]

On 15 June 2016, the LIGO group announced the detection of a second set of gravitational waves, which was observed at 03:38:53 GMT on 26 December 2015. The signal was seen by the Hanford LIGO detector 1.1 milliseconds after the Livingston detector. The signal rose from 35 to 450 Hz over the course of 55 cycles (27 orbits) during the period of observation of about a second. Analysis of the signal indicates that this event represented the merger of two black holes about 1.4 billion light years distant, with masses of about 14.2 and 7.5 solar masses, yielding a combined black hole of approximately of 20.8 solar masses, with one solar mass radiated away. The estimated spin parameter (ratio of angular momentum to theoretical limit) of the final black hole is 0.74, slightly higher than for the first detection (0.67); it was also found that at least one of the premerger black holes had a spin of greater than 0.2. This measurement provided additional support for general relativity.^[11][12]"