Is Dark Matter Hiding Near the Center of the Milky Way?

Rare things happen often in crowded corners of the universe.
Brad Bergan
NASA's James Webb Space Telescope.David Higgenbotham / NASA / MSFC

The universe is an uncertain place to live. Roughly 85% of all matter in it continues to elude astrophysicists — called dark matter, it is exotic, unconfirmed, yet still very necessary. Our galaxy — the Milky Way — appears as a bright flat disk in a clear night sky, but what we don't see is the colossal sphere of dark matter surrounding and pervading it. Actually, it's a halo whose density grows as we near the center of our galaxy.

However, dark matter's pervasiveness in the universe is matched only by the way it eludes our scientific best — as it doesn't interact with light and other electromagnetic forces. This means in the search for cataclysmic clashes between matter and dark matter, findings are scarce. But a recent study published in the journal Physical Review Letters suggests the use of large sets of gas giants — planets similar to Jupiter, in the gravity of which dark matter becomes "stuck", like cosmic quicksand. This causes particles to collide and mutually annihilate one another, creating a heat signature that astrophysicists could, in theory, detect.

An idea of this scope would measure a vast array of exoplanet temperatures closer to the center of our Milky Way, substantially increasing the likelihood of detecting these telltale heat signatures of dark matter particles' annihilation.

The James Webb Space Telescope could accelerate the search for dark matter

Physicists have already designed detectors on Earth made out of silicon chips or using liquid argon baths to capture these heat signatures directly, and even the Large Hadron Collider has played a role in the search for exotic particles hinting at the existence of dark matter. But they also think dark matter might affect neutron stars — which means observing them as they move by other cosmic bodies could lead to a major discovery. "We know we have stars and planets, and they're just peppered throughout the halo," said the Astroparticle Physicist Rebecca Leane of the SLAC National Accelerator Laboratory, in a Wired report. "Just moving through the halo, they can interact with dark matter."

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Gas giants like Jupiter are abundant in the center of the galaxy, which means — based on calculations — the temperature spikes we're likely to see will be noticeable and big, according to Leane and her co-author of the paper — Juri Smirnov of Ohio State University. And NASA is about to launch one of the most advanced cosmic thermometers ever — called the James Webb Space Telescope (JWST) — this fall. The JWST is an infrared telescope, and will become the most powerful one ever to be launched into outer space.

Scaling up the search for elusive dark matter

"It's a very surprising and inventive approach to detecting dark matter," said the Particle Physicist Joseph Bramante of Queen's University, who is also associated with the McDonald Institute in Ontario, in the Wired report. While Bramante wasn't involved in the new study, he's researched the possibility of detecting dark matter on other planets — and suggested that if we detect unusually hot planets directed toward the center of the galaxy, we'd have "a very compelling smoking gun signature of dark matter."

An earlier iteration of Leane's study initially shared on a preprint server first proposed that gas giants like Jupiter could hide the secrets of dark matter — collecting enough dark matter in its monstrous gravity that collision and subsequent annihilation would become statistically much more likely. But scaling up the idea to direct the James Webb Space Telescope's infrared array toward the densest pocket of planetary bodies in the center of the Milky Way will bring us tremendously close to detecting the telltale sign of the elusive dark matter.