Distorted starlight may contain signposts pointing to dark matter in the Milky Way


When we exit into inter-space, evidence of dark matter is found everywhere. This is in the rotation of galaxies, which cannot be followed only by observable matter. It is in the path of a cluster of galaxies together, and as the path of light travels through the universe. We cannot directly see Dark Matter, but its effect on other objects has allowed us to map it on a larger scale.

Closer to home, however – actually within the Milky Way galaxy – and at sub-galactic scales, the dark matter effect is much smaller, and therefore much more difficult to map. But a new technology can finally reveal where the Dark Matter of the Milky Way is hiding, when the Dark Matter passes through them in front of the stars.

Dark Matter is one of the worst events in the universe. We cannot directly detect it, so we do not know what it is, but we do know that the amount of gravity in the universe can have nothing to do with the general observable case – which we call baryonic matter. They say – alone.

In the 1930s, astronomer Fritz Zwicky found that, if galaxies in a coma cluster were held together by normal matter alone, their rotational speed would exceed the velocity for the objects inside them. If these galaxies contain only baryonic matter, they dissociate.

Was creating some extra gravity. We don’t know what that thing is, so we call it dark matter. The effect of dark matter has been observed in other ways, and cosmologists calculate that it makes up about 85 percent of cases in the universe.

One of those effects is gravitational lensing. According to the theory of general relativity, mass is spread around it. For small objects, this observable effect is negligible, but in fact for large-scale objects – say, a cluster of galaxies – the curvature of spacetime is much more pronounced, resulting in a curved path of light as it moves through that region. passes by.

Gravity lensing. (NASA, ESA and L. Calcada)

In their new paper, a team of researchers led by theoretical physicist Siddharth Mishra-Sharma of New York University introduced an outline for the detection of gravitational lenses in individual stars in the Milky Way to detect local dark matter .

When dark matter passes in front of a star, it must – theoretically – change the brightness of the star in such a way that the star appears to move. This has been predicted for decades, and is called astrometric weak gravitational lensing (astrometry is the study of the motion of stars), but the effect is so small, it is an inversely proportional proportionality challenge.

Mishra-Sharma and his colleagues propose that astrological weak gravitational lensing can be detected not in individual stars, but in groups.

“In this paper, we propose a new technique to characterize the population properties of galactic substructures through its collective lensing effect on distant sources,” he writes in his paper.

“We show that, with astrological observations of the near future, it may be possible that cold dark matter subhaloes can detect populations of compact objects, as well as condensation fluctuations by scalar field dark matter.”

With very accurate astrological observations, the team’s framework will allow astronomers to estimate the presence of dark matter by analyzing the distribution of velocity and acceleration of stars and galaxies. He also applied his technique to many simulated scenarios, and found that these distributions vary by type of dark matter – so the framework can also help validate the dark matter model.

And they found that the Sun’s orbit around the galactic center would introduce an asymmetry in the distribution, which could help distinguish the astronomically weak gravitational lensing signal from noise.

We currently have the most comprehensive astrometric catalog from the European Space Agency’s Gaia satellite, an ongoing project to map the Milky Way in three dimensions with the highest precision. The team attempted to apply its framework to Gaia data, and found that the dataset had too high a noise level to detect decent signal.

But they also note that future Gaia data releases, as well as upcoming telescopes, may produce better results.

“Astrometric datasets distributed by near-future surveys such as the Square Kilometer Array and The Nancy Grace Roman Space Telescope disturb the impression of a substructure characteristic of a series of well-motivated new physics such as the existence of cold dark matter, compacts. Can. Dark Objects and Scalar Field Dark Matter, “he wrote in his paper.

“Although current instrumental noise levels are not compatible with realistic discoveries for new physics, our proof-of-theory analysis can be carried over and applied to future astrological datasets, including upcoming Gaia data releases. Are, in a simple way. “

The research has been published in Physical Review D.

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