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In today's video, I will talk about Messier 60 and M60. This huge elliptical galaxy visible here belongs to the Virgo Cluster, and right next to it is a huge spiral galaxy called NGC 4647 . There is a great deal of debate as to whether these two galaxies, the unusual pair known as Arp 116,. Outwardly, the two galaxies appear to overlap, but if they interact, interactions such as tidal forces or gravity must occur . However, today I'm not going to talk about this interaction, but rather about the small galaxy located down here. This galaxy is called M60 UCD1, and the paper I have prepared today is the 'densest galaxy' published in 2013. M60-UCD1 is a very small dwarf
galaxy. This means that an enormous number of stars are densely packed within this very small structure At the time this paper was published in 2013, it was is a very interesting phenomenon because it is not clear how such a dense galaxy formed. Could it have formed directly from a dark matter halo, or is it a structure that was originally a normal galaxy that was stripped of its gas and stars, leaving only this dense structure behind? The research team of this paper brightest of the micro-dwarf galaxies discovered so far. In the first figure of the paper, you And
there is an M60-UCD1 in the bottom corner. For comparison, a typical ultra-small dwarf galaxy is also shown at the top. You can see that this dwarf galaxy appears much brighter and larger than a regular galaxy contains all the light coming from the galaxy Therefore, if you know the radius, you can determine the area occupied by the galaxy. And luminous intensity can be represented graphically against luminous density. Luminous density is luminosity normalized by the area occupied by the galaxy. There . The large dots are galaxies. Galaxies are much brighter but less dense. M60 UCD1 is located up here, and from this graph, you can see that M60 UCD1 is not the densest celestial object we know of. There are many
globular clusters with a higher star density than this object. However, compared to other galaxies, this galaxy can see a very bright X-ray source. This is evidence that a supermassive black hole exists at the center of this galaxy mass of this galaxy can be measured through the dispersion of the stars' velocities. Velocity dispersion means that tremendous gravity is required to hold all the stars together. In other words, it means that this galaxy has more mass. Therefore, considering the mass of this ultra-small dwarf galaxy, it can be seen that the supermassive black hole at the center accounts for 10 to 15 percent of the galaxy's total mass. This is a huge size. Therefore, there is absolutely no possibility that a
supermassive black hole could form at the center of such a small dwarf galaxy Therefore, considering its immense mass, the existence of a supermassive black hole, and structural characteristics , it is highly likely that M60 was formed by tidal-gravitational interactions. The M60 is very close to the UCD1 and is huge. The originally a normal galaxy composed of 10 billion stars. Then, at some point, UCD1 got too close to M60 and was stripped of and absorbed all the surrounding gas and stars, resulting in it becoming M60, a much larger elliptical galaxy In that case, could from stars stolen from UCD1 Yes, that is correct. It is highly likely that UCD1 has stolen
stars and material from many surrounding celestial bodies One of the scenarios I find interesting is ' cannibalism'. There are cases where a really huge galaxy and a much smaller galaxy collide, and in this case, the smaller galaxy completely swallows all the stars and matter inside it and merges into one. I think it is really interesting to look at the galaxies in the sky and think about how long ago these things happened. Because when we look at the sky, we are going back in time But I feel a bit sorry for the M60. When you look at him, he seems like a gangster, and also like a thief. Do I look like a fool?
No, I agree. Thief Galaxy, Gangster Galaxy? I think I should give it a good name. Usually, people name their galaxies, right? The densest galaxy. The It is no longer the densest galaxy. Since the 2013 paper, two galaxies have lost that spot. I'm sorry, but it is no longer the densest galaxy. Because as science advances, we discover more and more things. It would be more interesting to title it 'The Third Most Dense Galaxy' record of the early era of galaxy formation. These are really very old galaxies. It's probably over 10 billion years old, roughly the same age as the universe. It records the earliest moments of galaxy formation
Ultimately, that is exactly the reason for doing astronomy. It doesn't let me make a lot of money, it doesn't let me become famous, and it doesn't let me get a girlfriend. That kind of thing didn't work on me
