controversial X-ray glow not shown in Milky Way’s dark matter halo

Written by Lisa Grossman

Milky Way dark matter glow illustration

Scientists have suggested that an odd X-ray glow that emanates from some galaxies comes from decaying dark matter. But a search for this glow in the dark matter around the Milky Way came up empty. If that glow did exist, it might look like the colorful halo in this artist’s illustration.

If the light were from the mysterious matter, the region around the galaxy should shine with it.

Glowing X-rays around distant galaxies can’t come from dark matter particles, new research shows. The mysterious glow failed to show up in the dark matter halo around the Milky Way, astrophysicists report in the March 27 Science.

“It seems to be the final nail in the coffin of the dark matter interpretation,” says astroparticle physicist Ben Safdi of the University of Michigan in Ann Arbor.

The tantalizing glows were first detected in 2014 as an excess of X-rays with an energy of 3.5 kiloelectron volts, or keV, coming from faraway galaxy clusters. Some astronomers argued that the X-rays could come from decaying particles of dark matter — the ubiquitous, inert material that makes up more than 80 percent of the universe’s matter. The X-rays’ energy, in particular, suggested that the light could be coming from hypothetical dark matter particles called sterile neutrinos (SN: 6/1/18).

But searches for a similar X-ray glows came up empty in the dwarf galaxy Draco in 2015 (SN: 12/11/15) and the Perseus galaxy cluster in 2016 (SN: 8/12/16). So Safdi and his colleagues looked closer to home. The Milky Way’s starry spiral disk is surrounded by a halo of dark matter (SN: 3/23/20). If the X-rays come from decaying dark matter, our galaxy’s halo should sparkle with the light.

All images of the sky look through some portion of the Milky Way’s dark matter halo, even if that’s not what a telescope is aiming at. So the researchers sifted through every observation that the European Space Agency’s XMM-Newton space telescope ever made, about 347 days of total exposure time, in search of X-rays at the right energy. The team saw none.

“The jury is still out on what is producing the 3.5 keV” signal, Safdi says. “What’s clear, though, is it’s not dark matter.”


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Comments (4)

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    Robert Beatty


    Back to the drawing boards with the dark matter theory.
    It seems to me we cannot ignore the high gravitational forces evident near black holes. The big question then is, how far does the influence of that gravity field extend? There is no reason to question the application of the Inverse Square Law in this instance. This has led me to conclude that the universe is populated with Gravispheres. See GRAVISPHERES: What’s the matter with Dark Matter?by Robert A. Beatty

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    Tom O


    Realistically, IF there were black holes, there would be no matter near them, no particles energetic enough to escape them since the theory gives them an infinite strength field. There is no more likelihood that they exist than does “dark matter” exist. There is only room in theory for them, not actuality. That applies to both.

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    Brian James


    Mar 17, 2020 Disaster Petroglyph, Mantle Mystery, Bad Day 4 Dark Matter | S0 News

    Daily Sun, Earth and Science News

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    The theory of dark matter came about as a means of solving an equation. When someone was trying to determine if the gravity is enough they found that it isn’t, according to the current theories on gravity. So they solved the equation and came to a conclusion as to how much of this stuff that must be out there. The problem is that no one has ever seen it, so how do they know how much gravity will come from this dark matter? Different materials all have different gravitational pulls. The truth is that we do not understand how gravity works.

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