All Questions
35
questions
4
votes
1
answer
110
views
Is the amount of dark matter per galaxy the same as you look back through time (further away from earth)?
In the hope that it may inform us about the development/evolution (if any) of dark matter over time, are there any differences (eg. in structure or concentration) in the dark matter at large radial ...
- 351
0
votes
1
answer
48
views
Galactic Rotation Curves
While researching rotation curves, I've noticed a variety of velocity behaviors in different galaxies. In some, the velocity decreases, in others, it remains relatively constant, and in some cases, it ...
- 19
0
votes
1
answer
151
views
What if dark matter/energy did not exist?
What if dark matter and dark energy did not exist and were only due to a misinterpretation of the red shift of light or a measurement bias?
What would be the implications/consequences?
2
votes
2
answers
205
views
Likelihood of MACHOs being the best candidate for dark matter
Massive compact halo objects ("MACHOs") include a wide variety of hardly detectable bodies such as brown / white / black dwarfs and black holes, to name a few. If we take into account the ...
- 1,616
0
votes
1
answer
237
views
Can gravitational effects from past matter that you're looking at lightyears away produce an incorrect image of it? [closed]
Can gravitational effects from past matter that you're looking at lightyears away produce an incorrect image of it?
During the period that light from distant matter is travelling back to earth, can ...
- 21
0
votes
1
answer
114
views
How to test for possible negative mass of dark matter?
What is the phenomenology of how to test if dark matter has possibly a negative mass (WP negative mass) in particle physics experiments, cosmology or astrophysics?
I lately came across this ...
- 4,170
4
votes
1
answer
190
views
How do BAOs provide evidence for dark matter?
So far my understanding of BAOs is that they are a relic of the old universe formed by the freezing of acoustic density waves in baryonic matter as the universe entered the recombination epoch. These ...
- 51
1
vote
0
answers
39
views
About the spatial distribution of vacuum energy around strongly gravitating objects in the galaxy
We know that the distribution of vacuum energy is spatially uniform. But we also know that it couples to gravity.
Anything with energy, such as a beam of light is affected by the gravitational field ...
- 26.8k
3
votes
1
answer
93
views
Are there examples of dark matter at intra-galactic scales?
In articles I've read, evidence of dark matter (rotation of galaxies / gravitational lensing / galaxy collisions etc) is presented at galactic scales.
Are there examples of dark matter at smaller ...
- 481
0
votes
2
answers
259
views
Why is dark matter and dark energy needed to explain why there's more and less gravity respectively than there should be? [closed]
Why is dark matter needed to account for that there's more gravity than there should be, and dark energy for that there's less gravity than there should be?
Obviously that can't be correct, but I'm ...
- 11
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
3
votes
2
answers
203
views
Why physical / cosmological models that have been falsified weren't abandoned? [closed]
Before anything, I'd like to say that I'm a layman (non physicist) and english is not my main language; I apologize if my choice of words make me sound rude / arrogant, that is not my intent.
I often ...
- 163
0
votes
1
answer
201
views
Are pressureless, collisionless and self-interacting dark matter all synonymous?
Is there any distinction between pressureless, collisionless and self-interacting dark matter or does being one imply the other?
- 26.8k
2
votes
1
answer
206
views
Why doesn't the centrifugal force cause rotating dark halos to flatten?
Consider a spherical cloud of dark matter like the spherical halo around our galaxy. Please see the diagram below
Assuming that the halo is purely made up of dark matter which has only gravitational ...
- 26.8k
4
votes
1
answer
114
views
Why are cosmological contents often modeled as fluids?
Why is it that in cosmology, everything is treated as a "fluid"? What justifies modelling radiation, matter, etc. as "fluids" (even dark energy??)?
When does it break down -- surely at small scales ...
- 359