In 2015, researchers at the Laser Interferometer Gravitational-Wave Observatory (LIGO) captured the first direct evidence of gravitational waves, more than a century after the phenomenon was first proposed.
Like the wake of a ship, gravitational waves ripple out from massive objects, bending spacetime as they move.
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In the few years since the first recorded gravitational wave, instruments have quickly improved to let scientists observe the waves more often and more accurately.
Now, the largest catalog of gravitational waves ever examines 35 gravitational wave events between November 2019 and March 2020.
Most are thought to come from black hole mergers, but two come from much rarer mergers of black holes with neutron stars.
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One of the two black hole-neutron star mergers in the catalog shows a massive black hole colliding with a neutron star just 1.17 times the mass of the Sun — that’s one of the least massive neutron stars ever recorded.
To detect gravitational waves, scientists measure how long it takes a high-powered laser to bounce between huge mirrors — LIGO’s detector has four 88-pound mirrors spaced about 2.5 miles apart from each other.
The ripples caused by gravitational waves warp spacetime slightly, which changes the time it takes for the laser to travel a set distance. Better instruments make it possible to record smaller fluctuations.
Researchers found an object with a stellar mass of 2.8, meaning it’s either a very small black hole or a very large neutron star — an interesting discovery either way.
The collaboration’s next observation period is set for late 2022. Upgrades underway on the gravitational-wave detectors could make signals from billions of years ago visible, offering insight to the dynamics of early-universe black holes and stars.