The discussion revolves around the rotation curves of galaxies, particularly focusing on the role of neutral hydrogen and dark matter. Participants explore how the presence of dark matter influences the rotation curve profile, especially in galaxies with varying amounts of dark matter, and whether the flat rotation curve can be attributed solely to dark matter or if other factors are involved.
Participants express multiple competing views regarding the necessity of dark matter for explaining galactic rotation, and the discussion remains unresolved with no consensus reached.
There are limitations regarding assumptions about the distribution of dark matter and its effects on rotation curves, as well as the dependence on definitions of small-scale versus large-scale phenomena.
Through 21-centimetre radio emission arising out of collision between neutral hydrogen atoms.mathman said:How is neutral hydrogen observed?
So is the flat rotation curve only due to the presence of more matter in the form of dark matter, or is it also due to some unexplained property of dark matter.stefan r said:Keplerian.
The disc structure is very common at all scales of rotating groups of objects in space. From what I understand, dark matter is not needed to explain small scale phenomena (Solar System). Is it needed for galactic rotation explanation?Ranku said:So is the flat rotation curve only due to the presence of more matter in the form of dark matter, or is it also due to some unexplained property of dark matter.
Velocity dispersion in outer regions of galaxies are higher than expected, indicating presence of more matter than the visible matter, which are mostly concentrated toward the centre.sophiecentaur said:The disc structure is very common at all scales of rotating groups of objects in space. From what I understand, dark matter is not needed to explain small scale phenomena (Solar System). Is it needed for galactic rotation explanation?
The solar system as a whole has a much higher density than the galactic disk in terms of baryonic matter. So even though the density ofsophiecentaur said:The disc structure is very common at all scales of rotating groups of objects in space. From what I understand, dark matter is not needed to explain small scale phenomena (Solar System). Is it needed for galactic rotation explanation?