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The mysterious galaxy NGC 1052-DF4, located 44 million light-years away, revealed last year that it contains a surprisingly low amount of dark matter and represents a great challenge for models of galaxy formation.
And new research finds that NGC 1052-DF4 actually lacks dark matter due to another nearby galaxy.
“The dark matter is not there because it has already been removed,” said astrophysicist Miriya Montes, of the University of New South Wales in Australia and the Space Telescope Science Institute. We discovered that the gravity of the nearby massive galaxy NGC1035 washes away its stars and dark matter. “
The discovery of NGC 1052-DF4 was announced last year, and it was the second of its kind, a faint and highly diffuse galaxy, to be found due to depleted dark matter.
The problem was, dark matter was necessary for galaxies to form in the first place.
And we know that most galaxies have a gravitational pull much greater than normal matter can create, which can be detected. A hidden mass in the universe creates these additional clouds, and without it, according to our understanding of galaxy formation, there would not be enough gravity for matter to collapse into small galaxies.
And it seemed to be getting closer to a solution when a team of astrophysicists discovered that DF2 was much closer to us than initially thought. This means that the mass is much less than suggested by the initial calculations, and the proportion of ordinary matter was much less. Once the revised distance-based calculations were completed, DF2 had a very normal amount of dark matter.
And the speeds of star clusters within the galaxy still indicated the presence of dark matter far less than it should have been.
Using the IAC80, the Gran Telescopio Canarias and the Hubble Space Telescope, the researchers discovered stars drawn from DF4, consistent with an interaction with the much larger spiral galaxy NGC 1035.
“Preliminary research work showed that the galaxy has a very ‘comfortable’ symmetrical shape, indicating that there are no external forces bothering it, Montes said. But our deeper images show that this galaxy is actually affected by the neighboring galaxy, discovered at the beginning of the interaction The inner part of the galaxy maintains its shape, but the fainter outer parts are where you see these “tidal tails” – the stars that have already separated from the galaxy.
And since dark matter surrounds galaxies in a large aura, this tidal abstraction will remove most of the dark matter in the smaller galaxy before affecting stars, Montes said. And the stars begin to break away once the dark matter content falls below 10-15% of the galaxy’s total mass.
In the case of DF4, the team estimated that dark matter makes up only one percent of the total mass.
“With the passage of time, NGC1052-DF4 will be dismantled by the great system around NGC1035, with at least some of its stars floating freely in deep space,” said astrophysicist Ignacio Trujillo, from the Instituto de Astrofísica de Canarias. But at least we don’t have to go back to the drawing board for galaxy formation. “
The research has been published in Astrophysical.
Source: Science Walt
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