All Questions
48
questions
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33
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Turnaround radius being increased in fast collapsing regions?
In the context of formation of large-scale structures, there would be a turnaround radius where expanding matter would detach from the Hubble flow and start to collapse (https://www.aanda.org/articles/...
- 2,462
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0
answers
13
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CMB anisotropies due to moving clusters/voids?
Apparently, there is an effect where a moving overdensity/underdensity (or an object, e.g. a galaxy, moving in an overdensity/underdensity) that is going through an evolution of its gravitational ...
- 2,462
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0
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32
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Can the integrated Sachs-Wolfe and the Rees-Sciama effects have any influence on matter?
CMB photons can be affected by the expansion of the universe through the linear integrated Sachs-Wolfe effect (ISW) 1 and the non-linear ISW effect or also called Rees-Sciama effect 1.
In particular, ...
- 2,462
1
vote
2
answers
129
views
Is cosmological redshift associated with recession velocity when the light left or when it arrived?
Is the cosmological redshift $z$ associated with the recession velocity when the light left, when it arrived, or something in-between?
user300520
1
vote
1
answer
103
views
Measured Value of Hubble's Constant [duplicate]
As we know, Hubble's Constant is not exactly a constant, but its value varies with time. However, we also speak of measuring its present-day value. The measurements by cosmic distance ladder would ...
- 442
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46
views
Ejected bodies, dynamical friction and dark energy?
I have a question after reading a couple of papers (https://arxiv.org/abs/1707.06220 and https://www.arxiv-vanity.com/papers/1102.0007/).
Here, the authors seem to indicate that when bodies like stars ...
- 2,462
0
votes
1
answer
32
views
Can a receding body due to the accelerated spacetime expansion be "rescued"?
Once a body "crosses" the limit where dark energy wins over gravitational forces (Is there a distance from a gravitational source where the influence of gravity and dark energy are balanced ...
- 2,462
1
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0
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35
views
Does Dark Energy contribute to increase the isothermal temperature of plasma in galaxy clusters?
I have a question about this work called "Dark energy and key physical parameters of clusters of galaxies"
There, towards the end, the authors talk about the isothermal velocities and ...
- 2,462
2
votes
2
answers
181
views
How does dark energy affect the dynamics of galaxy clusters?
Galaxies interact with each other gravitationally (just as every other celestial object) and in many cases they form groups or clusters.
Does the expansion of the universe (or dark energy) affect the ...
- 2,462
1
vote
0
answers
57
views
Brans-Dicke formalism: Validity for curve of scale factor vs cosmic time
Within the framework of the Brans-Dicke formalism, after having run a MCMC sampler and, once the best-fits have been found, I inject them into an ODE system resulting from the modified Friedmann ...
0
votes
2
answers
44
views
Age of the universe due to expansion
"If gravity working on matter is the only force at work on large scales, then the attactive force of gravity will act to slow the expansion. In this case, the universe was expanding more rapidly ...
4
votes
2
answers
947
views
Could it be possible that the Universe is expanding in some areas while contracting in other areas?
I am wondering if could it be possible that the Universe is expanding in some areas while contracting in other areas.
I have wondered if perhaps as one area of the Universe is squeezed inward by some ...
- 478
2
votes
1
answer
82
views
Question on the relation between the Hubble constant and the absolute magnitude of Type Ia supernovae
I would like to ask a question about the relation between the Hubble constant and the absolute magnitude of supernovae
I have read that supernovae alone cannot fix $H_0$ and that there is a ...
- 299
1
vote
1
answer
24
views
Kinetic energy and collisions in cosmology? [duplicate]
Objects in space time can move due to the expansion of spacetime itself (where objects that are sufficiently far apart would recede from each other due to the Hubble flow) and peculiar motions (which ...
- 2,462
2
votes
2
answers
106
views
Does the rate of expansion of the universe depend on the mass or size of the galaxies?
Does the rate of expansion of the universe depend on the mass or size of the galaxies? How constant dark energy density affect the massive/lighter galaxies?
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