All Questions
26
questions
2
votes
0
answers
90
views
Gravitational halos made of neutrinos...?
I have been recently interested in how halos made of standard model particles could be formed and behave.
After asking some questions in this site, I was told about how neutrinos could form such halos....
- 2,462
1
vote
1
answer
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
0
votes
1
answer
134
views
Theoretically, is it feasible for the dark matter density to be constant and homogeneous, as dark energy is, and the two to be related?
I know that currently dark matter and dark energy are separate things, not related and one not deriving from the other. But if both are included in a generalized gravitation theory, the picture can ...
- 1
1
vote
1
answer
121
views
Dark matter, MOND or flattened gravitational fields? [closed]
Could there not be a third variant to explain why e.g. long-distance multistar systems rotate faster than Newton's law of gravity suggests?
In addition to the Dark matter hypothesis and MOND then, ...
- 521
0
votes
0
answers
50
views
Is the $σ8$ tension in the ΛCDM cosmology evidence that the amount of Dark Matter (DM) in the universe is increasing?
Strong evidence is provided by recent cosmological studies that “clumpiness” in the large scale structure (LSS), as measured by $σ8$, is decreasing (for example, “Hyper Suprime-Cam Year 3 Results…”, X....
- 11
2
votes
0
answers
42
views
Did galaxies spin differently 4, 5, 6 billion years ago?
Today I read that the Matter-dominated era ended 4 billion years ago, and now we're in the Dark Energy dominated era.
Obviously, light from galaxies far enough away would be from earlier in the ...
- 121
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
1
vote
1
answer
167
views
Could dark energy be explained via the use of a "gravitational charge"?
Could gravity be explained as the existence of a "gravitational charge", acting similarly to an electromagnetic charge but where like charges attract and opposite charges repel? A graviton ...
0
votes
1
answer
101
views
Dark Matter/Energy & Space-Time [closed]
After searching for quite a while for a minimalist approach to explaining Dark Matter as well as Dark Energy, unfortunately without much good, I decided I may as well help fill the explored paths, or ...
- 11
2
votes
1
answer
207
views
Can Integrating out Dark Matter give Modified Gravity?
I'm sure I misunderstood something obvious, but reading this question, I wondered what philosophically is the difference between modified gravity (like TeVeS, f(R), etc.) and dark matter, if/since we ...
- 232
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
1
vote
1
answer
888
views
Why is the heat death, rather than a Big Crunch, the most accepted theory of the ultimate fate of the Universe?
The Heat Death is accepted by most as the end of the Universe, but how can that be? Wouldn't the Big Crunch make a lot more sense? I mean, even if everything in the Universe is spread out uniformly ...
- 41
2
votes
0
answers
140
views
How does dark matter distribution help to identify it's composition
A question regarding this recently released data,
and the paper https://arxiv.org/abs/1708.01538 that details it's distribution:
Abstract:
We use 26 million galaxies from the Dark Energy Survey (...
user163104
6
votes
1
answer
171
views
Do galaxies have a halo of neutrinos and cosmic microwave background?
If virial arguments as in "How can dark matter collapse without collisions or radiation?" allow concluding that dark matter could collapse to galactic halos purely gravitationally, then is this true ...
- 1,289
5
votes
3
answers
244
views
Current constraints on Dark Matter self-interaction from galactic profiles
The self-interaction of dark matter may be small but it cannot be negligible if it is able to dissipate energy to relax into galactic clumps (necessary to explain galaxy rotation curves).
According ...
- 1,289