Extremely Powerful Cosmic “Dark Matter Detector” Probed by Astrophysicist

Extremely Powerful Cosmic “Dark Matter Detector” Probed by Astrophysicist

Artist’s depiction of a magnetar. Credit: ESO/L. Calçada

A University of Colorado at Boulder astrophysicist is looking out the sunshine coming from a distant, and intensely highly effective celestial object, for what would be the most elusive substance within the universe: darkish matter.

In two latest research, Jeremy Darling, a professor within the Department of Astrophysical and Planetary Sciences, has taken a deep take a look at PSR J1745-2900. This physique is a magnetar, or a kind of collapsed star that generates an extremely robust magnetic subject. 

“It’s the best natural dark matter detector we know about,” stated Darling, additionally of the Center for Astrophysics and Space Astronomy (CASA) at CU Boulder.

He defined that darkish matter is a type of cosmic glue—an as-of-yet unidentified particle that makes up roughly 27% of the mass of the universe and helps to bind collectively galaxies like our personal Milky Way. To date, scientists have principally led the hunt for this invisible matter utilizing laboratory gear.

Darling has taken a special strategy in his newest analysis: Drawing on telescope knowledge, he’s peering at PSR J1745-2900 to see if he can detect the faint indicators of 1 candidate for darkish matter—a particle known as the axion—remodeling into gentle. So far, the scientist’s search has come up empty. But his outcomes may assist physicists working in labs all over the world to slender down their very own hunts for the axion.

The new research are additionally a reminder that researchers can nonetheless look to the skies to resolve a few of the hardest questions in science, Darling stated. He revealed his first spherical of outcomes this month in The Astrophysical Journal Letters and Physical Review Letters.

“In astrophysics, we find all of these interesting problems like dark matter and dark energy, then we step back and let physicists solve them,” he stated. “It’s a shame.”

Natural experiment

Darling needs to alter that—on this case, with slightly assist from PSR J1745-2900. 

This magnetar orbits the supermassive black gap on the middle of the Milky Way Galaxy from a distance of lower than a light-year away. And it’s a pressure of nature: PSR J1745-2900 generates a magnetic subject that’s roughly a billion occasions extra highly effective than probably the most highly effective magnet on Earth.

Sagittarius A* and Magnetar PSR J1745-2900

An picture of the center of the Milky Way Galaxy exhibiting the placement of the supermassive black gap at its middle, known as Sagittarius A*, and the close by magnetar PSR J1745-2900. Credit: NASA/CXC/FIT/E

“Magnetars have all of the magnetic field that a star has, but it’s been crunched down into an area about 20 kilometers across,” Darling stated.

And it’s the place Darling has gone fishing for darkish matter.

He defined that scientists have but to find a single axion, a theoretical particle first proposed within the 1970s. Physicists, nevertheless, predict that these ephemeral bits of matter might have been created in monumental numbers through the early lifetime of the universe—and in massive sufficient portions to elucidate the cosmos’ additional mass from darkish matter. According to concept, axions are billions and even trillions of occasions lighter than electrons and would work together solely not often with their environment.

That makes them virtually unimaginable to look at, with one huge exception: If an axion passes by way of a robust magnetic subject, it will possibly remodel into gentle that researchers may, theoretically, detect.

Scientists, together with a group at JILA on the CU Boulder campus, have used lab-generated magnetic fields to attempt to seize that transition in motion. Darling and different scientists had a special concept: Why not strive the identical search however on a a lot greater scale?

“Magnetars are the most magnetic objects we know of in the universe,” he stated. “There’s no way we could get close to that strength in the lab.”

Narrowing in

To make use of that pure magnetic subject, Darling drew on observations of PSR J1745-2900 taken by the Karl G. Jansky Very Large Array, an observatory in New Mexico. If the magnetar was, certainly, remodeling axions into gentle, that metamorphosis may present up within the radiation rising from the collapsed star.

The effort is a bit like on the lookout for a single needle in a very, actually huge haystack. Darling stated that whereas theorists have put limits on how heavy axions could be, these particles may nonetheless have a variety of potential plenty. Each of these plenty, in flip, would produce gentle with a selected wavelength, virtually like a fingerprint left behind by darkish matter.

Very Large Array

Several of the 28 dish antennae that make up the Very Large Array, positioned in Socorro, New Mexico, USA. Credit: CGP Grey, CC BY 2.0

Darling hasn’t but noticed any of these distinct wavelengths within the gentle coming from the magnetar. But he has been ready to make use of the observations to probe the potential existence of axions throughout the widest vary of plenty but—not unhealthy for his first try. He added that such surveys can complement the work taking place in Earth-based experiments. 

Konrad Lehnert agreed. He’s a part of an experiment led by Yale University—known as, not surprisingly, HAYSTAC—that’s looking for out axions utilizing magnetic fields created in labs throughout the nation. 

Lehnert defined that astrophysical research like Darling’s may act as a type of scout within the hunt for axions—figuring out fascinating indicators within the gentle of magnetars, which laboratory researchers may then dig into with a lot higher precision.

“These well-controlled experiments would be able to sort out which of the astrophysical signals might have a dark matter origin,” stated Lehnert, a fellow at JILA, a joint analysis institute between CU Boulder and the National Institute of Standards and Technology (NIST).

Darling plans to proceed his personal search, which suggests wanting even nearer on the magnetar on the middle of our galaxy: “We need to fill in those gaps and go even deeper.”


“New Limits on Axionic Dark Matter from the Magnetar PSR J1745-2900” by Jeremy Darling, 7 September 2020, The Astrophysical Journal Letters.
DOI: 10.3847/2041-8213/abb23f

“Search for Axionic Dark Matter Using the Magnetar PSR J1745-2900” by Jeremy Darling, 17 September 2020, Physical Review Letters.
DOI: 10.1103/PhysRevLett.125.121103

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