The discussion focuses on the relationship between flat rotation curves in galaxies and the presence of neutral hydrogen and dark matter. Observations of neutral hydrogen are conducted through 21-centimetre radio emission, which reveals the rotation curve profile. The conversation highlights that while dark matter is essential for explaining galactic rotation, it is not necessary for small-scale phenomena such as those observed in the Solar System. Additionally, the higher velocity dispersion in the outer regions of galaxies suggests the presence of more matter than what is visible, indicating the significant role of dark matter in galactic dynamics.
PREREQUISITESAstronomers, astrophysicists, and students studying galactic dynamics, particularly those interested in the roles of dark matter and neutral hydrogen in the structure and behavior of galaxies.
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?