- #1
fhenryco
- 63
- 5
Hello,
I often read that hot dark matter is constrained by structure formation issues. But I'm now wondering why it is not constrained by the CMB data itself because such hot dark matter should belong to radiation (with density evolving as 1/a^4 rather than 1/a^3) so for instance when we replace cold dark matter by hot dark matter we should also shift the redshift of matter(baryons+CDM: 1/a^3)--radiation(photons and HDM : 1/a^4) equatlity ... so shouldn't this disturb the expansion rate history H(z) and then many observables in the CMB but also at Big-Bang nucleosynthesis ?
thanks in advance
I often read that hot dark matter is constrained by structure formation issues. But I'm now wondering why it is not constrained by the CMB data itself because such hot dark matter should belong to radiation (with density evolving as 1/a^4 rather than 1/a^3) so for instance when we replace cold dark matter by hot dark matter we should also shift the redshift of matter(baryons+CDM: 1/a^3)--radiation(photons and HDM : 1/a^4) equatlity ... so shouldn't this disturb the expansion rate history H(z) and then many observables in the CMB but also at Big-Bang nucleosynthesis ?
thanks in advance
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