This fleeting flash could be a window into the universe’s first seconds, useful context for a colleague or friend following dark matter research.
One-Hour Flash Hints at Ancient Black Hole Story flow and key facts
Astronomers have detected a rare, one-hour brightening of a star 50,000 light-years away, caused by gravitational microlensing from an unseen object. Named Phoebe, the event was observed in 2019 using the DECam on Chile’s Blanco telescope. The object’s mass — about three times that of the Moon — and its location suggest it is not a rogue planet or star, but possibly a primordial black hole formed in the universe’s first moments.
Primordial black holes are theoretical objects that could explain dark matter, the invisible mass shaping galaxies. Unlike stellar black holes, they form from extreme density fluctuations during cosmic inflation. Phoebe’s lensing signature is 100,000 times more likely to come from dark matter than from ordinary galactic objects.
Follow-up observations from the Subaru telescope in Hawaii have found similar events, hinting at a population of lunar-mass black holes. While microlensing can’t confirm the object’s nature directly, future surveys with the Nancy Grace Roman and Vera C. Rubin telescopes may gather enough data to test whether such objects make up dark matter.
Facts
- The microlensing event Phoebe lasted about 60 minutes in December 2019, observed toward the Large Magellanic Cloud.
- Phoebe’s mass is estimated at 0.026 Earth masses (about three lunar masses), with the highest probability of being in the Milky Way’s dark matter halo.
- The chance that Phoebe is dark matter is five orders of magnitude higher than it being a rogue planet or star.
- Researchers ruled out flaring stars, binary systems, and stellar clusters as explanations using TESS and Kepler data.
- If confirmed, Phoebe would be a primordial black hole formed during cosmic inflation, before Big Bang nucleosynthesis.
- Similar events detected by Subaru telescope suggest a possible population of lunar-mass compact objects linked to dark matter.
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