Observations of galaxies without dark matter … Paradoxical proof of existence


Yale University Research Team, First Dog Journal Published in a Year

Dark matter does not interact with light and is not visible, but its presence is known indirectly through gravitational effects on other materials, including stars. It accounts for about a quarter of the total energy mass of the universe and constitutes 85% of the universe's material.

However, the academy has been hotly debated by researchers led by Yale professor of astronomy, Peter Dochum, and researchers who reported that NGC 1052-DF2, a galaxy about 60 million light-years away, showed little dark matter in March last year.

One year later. Professor Dochum's research team elaborates the results of the previous research, and it is noteworthy whether the controversy over dark matter will be summed up by presenting two works that have uncovered a second galaxy with little dark matter.

According to the WM Keck Observatory in Hawaii, Professor Dochum and his colleagues observed the galaxy DF2 with the Cosmic Web Imager (KCWI), a state-of-the-art spectrograph of the Keck II telescope, which showed that 10 globular clumps, same speed.

It was interpreted as meaning that it is not really dark matter, moving three times slower than expected. If dark matter is present in the galaxy DF2, the globular clusters must move faster, but not so.

KCWI is able to accurately measure mass using high resolution spectral resolution while observing the entire galaxy at once, and KCWI is the only device capable of performing these two functions.

The researchers also discovered a galaxy, NGC 1052-DF4, with almost no dark matter like DF2.

Like DF2, DF4 belongs to the so-called "super-dispersed galaxy (UDG)". The UDG is as large as our galaxy, but the stars are only a hundredth to a thousandth, so it is not easy to observe.

DF2 and DF4 are part of a galaxy captured by NGC 1052, a giant elliptical galaxy without arms of galaxy, and are similar in size, brightness, distance and shape.

Researchers have found that a second galaxy with little dark matter means that the galaxy is not a peculiar case and that the likelihood of finding more is greater than before, I hope that happens.

The researchers published two articles in the International Journal of Astrophysical Journal Letters on June 20 and 28, respectively.

There are two examples in the academics that are still early enough to draw conclusions about dark matter, but this observation, which found galaxies practically without dark matter, suggests that dark matter rather than ordinary matter, and that it is possible to become a member.

"There was a time when we got stressed after the article was published," Dochum said. "Most of the criticism of the article was constructive and polite, but not all, and every time new criticism was raised, I remember.

Shannon Daniel Lee, who first discovered DF2 and participated as the first author of the article, said in a press release: "Nobody knew if there was such a galaxy, and that was the best thing astronomers have discovered," he said.

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