All across the Universe, massive stars collapse and die.
From core-collapse supernovae, neutron stars and black holes form.
Stars and gas directly collapse, forming black holes.
Finally, neutron star mergers create black holes, too.
These black holes roam the Universe, devouring whatever matter contacts their event horizons.
Inspiraling, merging objects emit gravitational waves, allowing black hole detections terrestrially.
We also detect the X-rays emitted by black holes feeding off of binary companions.
These X-ray binaries, traditionally, have revealed the closest black holes: several thousands of light-years distant.
However, two other methods hold promise: microlensing and black hole-star binaries with detached orbits.
Microlensing occurs whenever a mass intervenes between a luminous object and ourselves.
The characteristic brightening pattern reveals the interloper’s mass and other properties.
Meanwhile, black holes orbiting normal stars will influence the star’s observed motion and position.
By tracking a star’s redshift-and-blueshift over time, a candidate companion’s mass can be uncovered.
Observing its changing position over time should match the companion candidate’s predictions, confirming its partner.
The ESA’s Gaia mission leveraged this method, discovering today’s nearest black hole: Gaia BH1.
Just 1560 light-years away, this record is temporary.
Upcoming missions, like Nancy Roman, should reveal even closer black holes.
Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words. Talk less; smile more.