All Questions
15
questions
1
vote
1
answer
183
views
Does NFW profile work for any galaxy?
We use Navarro–Frenk–White (NFW) to calculate Dark Matter (DM) density. Can we use it for DM halo in any galaxy or is it used only for Milky Way (MW)?
- 11
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?
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 ...
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
2
answers
109
views
Why a decaying dark matter?
I'm reading some papers (model, exp and model) that are dealing with decaying models of DM, why is it interesting? What are the signatures that this type of model can give to observe DM?
I am ...
- 900
-4
votes
1
answer
101
views
What does. DM- nu, sigma = 10^-33 m_DM GeV^-1 cm^2. mean?
I tried posting a screenshot above......
On Ethan Siegel's blog over at Forbes, he has repeatedly posted a graphic showing possible 'new physics' that could explain why the Planck satellite ...
- 4,509
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
-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 ...
4
votes
2
answers
812
views
How do we know that the dark matter is cold or non-relativistic? [duplicate]
According to the $\Lambda$CDM parametrization of the Standard Model of Big Bang cosmology, the universe contains a cosmological constant $\Lambda$ associated with $73\%$ dark energy, $23\%$cold dark ...
- 26.8k
4
votes
1
answer
244
views
New observation of a Galaxy without dark matter: what is(are) the implication(s)?
This recent paper in Nature (also see here$^1$) claimed to have discovered a galaxy without dark matter. However, in the Standard paradigm of cosmology dark matter played a crucial role in the ...
- 26.8k
1
vote
1
answer
602
views
physical meaning of dark matter virial radius
As I have read in the literature, the virial radius of a dark matter halo is the radius of a sphere such that the density $\frac{M_{\text{virial}}}{\frac{4\pi}{3}R_{\text{virial}}^{3}}=97.2\rho_{\text{...
3
votes
1
answer
229
views
Do satellite galaxies have the same proportion of dark matter as "ordinary" galaxies
My question is relatively straightforward: Do we know if satellite/ dwarf galaxies contain the same proportion of dark matter to ordinary matter as "regular" sized galaxies?
The Milky Way, for ...
user108787
1
vote
1
answer
147
views
What size of object does the peak of the cosmological power spectrum correspond to?
The title almost says it all, but to flesh it out more, what is the size a sphere corresponding to the peak in the cosmological power spectrum (Figure 2: https://ned.ipac.caltech.edu/level5/Sept11/...
- 531
7
votes
1
answer
2k
views
What fraction of baryonic matter is in stars?
We know from big bang nucleosynthesis that baryonic matter accounts for about 5% of the universe's total mass-energy density. What is the current best estimate of how much of this is in the form of ...
user4552
5
votes
1
answer
111
views
What's the evidence, if any, for some local concentration(s) of dark matter in some region(s) smaller than a galaxy?
What's the evidence, if any, for some local concentration(s) of dark matter in some region(s) smaller than a galaxy?
Galactic-sized - or larger - gravitating halos seem to get all the attention. I'm ...
- 101