by The IS Hubble Space Telescope It has been shown that dark dark are concentrated within the core of a nearby dwarf galaxy, a result that comes to the rescue of the Irish Standard Model cosmology. This model basically predicts that dark matter will be “cold,” but recent results have begun to suggest that the substance is “hot.” These new views, however, are on the side of the Standard Model.
Dark matter is the invisible substance that purports to make up 85% of the mass of the universe, but no one knows what dark matter actually is, or exactly how it behaves. Our best guess is that it’s “cold,” which means, in other words, that it’s predicted to consist of low-energy particles that aren’t drifting around here and there, but are rather slow and able to meet together to form. giant haloes inside which grow galaxies. The concept of cold dark matter (CDM) and its influence on structure formation i the universe It is a vital part of our current Standard Model of cosmology. That part is called Lambda–CDM (the lambda refers to it dark energy).
In a cold dark matter paradigm, dark matter should thrive especially in the dark matter core of a Halo, so dark matter should be dense in the dark matter core. galaxy that grows inside that halo. Astronomers call this the dark matter “cusp” because of the shape it makes on a graph of dark matter density relative to its radius from the center of a galaxy.
However, astronomers have been puzzled by some recent observations of dwarf galaxies that have suggested that dark matter may behave differently than they thought. Instead of acting as cold dark matter and clumping more densely in the core of the dark matter halo, these observations suggest that dark matter may be distributed more evenly throughout a galaxy instead. This would be a sign that dark matter is “hot,” or has a lot of energy no meet so many. If true, this would have significant implications for our cosmological models that rely on dark matter being able to clump in certain ways.
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Now, astronomers led by Eduardo Vitral from the Space Telescope Science Institute (STScI) in Baltimore, Maryland, have tested this.
Dwarf galaxies are the best place to study dark matter because, proportionally, they have the highest amount of dark matter of any type of galaxy. The dwarf galaxy Draco, chosen for this study, orbits our galaxy The Milky Way Galaxy a distance of 250,000 light years from World. In the Hubble archive, there is data describing the movements of the stars in the Draco dwarf spanning 18 years, between 2004 and 2022. The Vitral team was able to use these resolutions to accurately measure the gravitational field of the Draco dwarf, and therefore the distribution of its mass, including the part dedicated to dark matter.
Through the “proper motions” of the stars — that is, their motion across the sky — with their radial motion towards or away from us which is observable as blueshift or redshift in light, the Vitral team was able to move the stars in the Draco dwarf i 3d.
“When measuring proper motions, you note the position of a star at one epoch and then many years later you measure the position of that same star. You measure the displacement to find out how much it has moved,” a said Sangmo team member Tony Sohn of STScI i statement. “On this type of observation, the longer you wait, the better you can move the stars.”
Certainly, the longevity of Hubble i space advantage here, as is its powerful resolution from the vantage point high above Earth’s turbulent atmosphere. The proper motion of the stars of the Draco dwarf over a period of 18 years is a tiny quarter of a million light-years, equivalent to less than the width of a golf ball. the moon as seen from Earth. Hubble’s results are therefore the most detailed measurements of stellar motion in another galaxy ever made.
By using these stellar motions, the Vitral team was able to conclude that the total mass of the dark matter halo of the Draco dwarf, at a radius of nearly 3,000 light years, is 120 million times that size. the mass of our sun. In addition, the results strongly suggest that the dark matter density profile of the Draco dwarf has a cusp in the core and thus the presence of dark matter. yes probably cold. As the researchers wrote in their research paper, “The results reduce the tension surrounding the ‘cusp-core’ problem and lend further credence to standard lambda-CDM cosmology.”
“Our models tend to agree more with a cusp-like structure, which aligns with cosmological models,” Vitral said in the statement. “While we can’t say with certainty that every galaxy has a dark matter distribution, it’s exciting to have such well-measured data that surpasses anything we’ve had before.”
The next step, then, is to repeat the analysis on other dwarf galaxies, and the Vitral team is currently working on studies of the Sculptor and Ursa Minor dwarf galaxies, which also orbit the Milky Way galaxies.
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If the results can be replicated in these and other galaxies, it would effectively rule out some dark matter candidates such as sterile neutronosis and gravitinosthe latter is a hypothetical particle predicted by the theory of supersymmetry as a huge partner with the same hypothesis (but Probably true) graviton. The results thus strengthen the possible models of cold dark matter, especially weakly interacting massive particles (WIMPs), primordial black holes and facilities.
The results from the Draco dwarf were published on July 11 i The Astrophysical Journal.
