All Questions
28
questions
1
vote
1
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125
views
What if gravitation was the only force? [closed]
This is a follow up of Interactions within constituents of dark matter .
I wonder about dark matter, and, naturally, compare it with our observable world.
If gravitation would be the only force acting ...
- 1,028
1
vote
0
answers
84
views
The 'core-cusp' problem for dark matter halos in larger galaxies
TLDR: Do observations of larger galaxies favour 'cuspy' dark matter halo distributions, as predicted by N-body simulations?
I've been trying to understand the 'core-cusp' problem for dark matter halos ...
- 11
3
votes
1
answer
106
views
What happens to objects along spiral galaxy arms over long periods of time?
Observations of spiral galaxies reveal that objects within the same arm of a spiral galaxy move at around the same speeds, regardless of their distance from the center of the galaxy. Conversely, the ...
0
votes
0
answers
24
views
How much gravitational lensing do we see from the Milky Way?
I assume that the Milky Way has a dark matter halo just like any other. If that is the case, if we look at a huge part of our own galaxy, do we actually see the gravitational lensing effect? How ...
- 495
1
vote
1
answer
40
views
Could the energy emitted by galaxies contribute to the dark matter phenomenon?
I'm pondering a concept regarding the energy-mass conversion in the context of cosmology, specifically related to the light emitted by galaxies over billions of years.
Einstein's famous equation E=mc^...
- 11
2
votes
3
answers
662
views
Why is the ratio of dark matter to normal matter larger in galaxies than the cosmic average?
There seems to be a discrepancy between the ratio of dark matter to normal matter in the Universe (about 5 to 1 according to $\Lambda$-CDM) and the ratio of the average dark matter halo mass to the ...
- 185
5
votes
2
answers
387
views
Gravitational binding energy as alternative to dark matter?
Pondering this question: Casimir effect and negative mass
and, in particular, the response of John Rennie "as the mass of any bound system is slightly less than the mass of its parts" I ...
- 113
14
votes
3
answers
3k
views
Is Dark Matter in Motion?
What is known about the motion of dark matter, especially in galaxies?
It seems as though a particular distribution of dark matter might be required to cause the very flat galactic rotation curves ...
- 13.7k
0
votes
1
answer
99
views
Why is the distribution of Dark Matter in the Universe inhomogeneous?
As far as I know, there exist galaxies containing lots of DM and other galaxies with almost no DM at all.
This implies that the distribution of DM in the Universe is inhomogeneous. Do we have any idea ...
- 123
1
vote
1
answer
225
views
How to calculate the strength ("space force") of dark matter within galaxies?
Let's first have a look at the observed speed within galaxies (source):
On the left side we can see the speed of celestial bodies within galaxies derived by gravity only (gravity is usually created ...
- 282
14
votes
3
answers
2k
views
Why is dark energy dominant between galaxies but not inside galaxies?
The ideas of dark matter and dark energy are mind blowing.
Why is it said that dark matter overcomes dark energy in galaxies but it loses the battle in intergalactic space? In other words, why is dark ...
- 1,148
12
votes
3
answers
1k
views
Is dark matter inside galaxies different from dark matter in intergalactic space?
I just read a text about astronomy and when talking about dark matter the author says:
[...], the dark matter responsible for the orbits of the stars in the Milky Way is probably different from the ...
- 1,171
2
votes
1
answer
214
views
Formula for the bias of galaxies
From the article "Large-Scale Galaxy Bias", I try to deduce the equation that my teacher told me which links 2 quantities:
the global number density of galaxies
the local number density of galaxies
...
user87745
-3
votes
1
answer
62
views
Could dark matter be normal matter that is beyond the observational horizon?
As I understand it, matter that is too distant for its light to reach us would not be observable, and the CMB is the limit of what is observable from our location within the universe. Could what is ...
0
votes
1
answer
186
views
Why can't the Higgs vacuum energy clump to galaxies and act as dark matter (instead of dark energy)? [closed]
The Higgs field has a nonzero vacuum expectation value which contributes to the energy density of the Universe. Energies contribute to the curvature of spacetime and affected by gravitational ...
- 26.8k