Photo: Maksim Blinov / RIA Novosti
MSU scientists have discovered a supermassive black hole in the center of the galaxy Fornax UCD3, which belongs to the rare class of ultra-compact dwarfs. The results were published in the journal Monthly Notices of the Royal Astronomical Society. About it reported in a press release, which is at the disposal of edition”.ru”.
Galaxy Fornax UCD3 belongs to the cluster of galaxies in the constellation of the Furnace. It refers to a very rare and unusual class of ultra-compact dwarfs (UCD). The mass of these dwarf galaxies is a few tens of millions of solar masses and their radius usually does not exceed three hundred light-years.
Image: NASA / STScI / ESO / Afanasiev et al.
The study of the galaxy, the scientists used data from the infrared spectrograph SINFONI, which is mounted on one of the VLT telescopes in Chile. The authors found a dependence of the velocity dispersion of the stars of the radius in the galaxy Fornax UCD3. The velocity dispersion shows how the apparent velocities of the stars differ from the average. In the presence of a massive object such as a black hole, the stars begin to move faster and in random directions. As a result, their average speed is not increased, but the dispersion increases strongly. It turned out that the velocity dispersion of stars in the center of the galaxy is so large that can only be explained by the presence of a massive black hole.
To estimate the mass of the black hole, the researchers compared the obtained dependence of the rate and dispersion of the dynamic models. it turned out that the best observation is consistent with a model that assumes a black hole mass of 3.5 million solar masses. Scientists also considered the possibility of the absence of a black hole, but it was excluded with a statistical significance of three Sigma (99.7 percent).
This is the fourth hole found in ultra-compact dwarfs, and its mass is four percent of the total mass of the galaxy. In normal galaxies this ratio is significantly less (about 0.3 percent).
The presence of massive black holes in ultra-compact dwarfs considered svidetelstvom in favor of a tidal origin of these galaxies. Normal galaxy normal size at some period of its evolution took place too close to other, larger and more massive galaxy. Due to the impact of tidal forces UCD3 lost most of the stars who were on the periphery, and it was only a compact core.
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