Dark matter and the anthropic principle

@article{Hellerman2005DarkMA,
  title={Dark matter and the anthropic principle},
  author={Simeon Hellerman and Johannes Walcher},
  journal={Physical Review D},
  year={2005},
  volume={72},
  pages={123520}
}
We evaluate the problem of galaxy formation in the landscape approach to phenomenology of the axion sector. With other parameters of standard $\ensuremath{\Lambda}$CDM cosmology held fixed, the density of cold dark matter is bounded below relative to the density of baryonic matter by the requirement that structure should form before the era of cosmological constant domination of the universe. Galaxies comparable to the Milky Way can only form if the ratio also satisfies an upper bound. The… 

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References

SHOWING 1-10 OF 35 REFERENCES
A Model of Anthropic Reasoning, Addressing the Dark to Ordinary Matter Coincidence
If inflation occurs after the breaking of Peccei-Quinn symmetry then large values of the breaking scale $F$, which are forbidden in conventional axion cosmology, are permitted, provided that we
Anthropic bound on the cosmological constant.
  • Weinberg
  • Physics
    Physical review letters
  • 1987
TLDR
It is argued here that in universes that do not recollapse, the only bound on the cosmological constantlambda is that it should not be so large as to prevent the formation of gravitationally bound states, and it turns out that the bound is quite large.
Why Is the Cosmic Microwave Background Fluctuation Level 10?5?
We explore the qualitative changes that would occur if the amplitude Q ~ 10-5 of cosmological density fluctuations were different. If Q ≲ 10-6, the cosmological objects that form would have such low
Formation of the First Supermassive Black Holes
We consider the physical conditions under which supermassive black holes could have formed inside the first galaxies. Our smoothed particle hydrodynamics simulations indicate that metal-free galaxies
Why is the CMB fluctuation level 10^{-5}?
We explore the qualitative changes that would occur if the amplitude Q ∼ 10 of cosmological density fluctuations were different. If Q ∼< 10 , the cosmological objects that form would have so low
Likely Values of the Cosmological Constant
In theories in which the cosmological constant takes a variety of values in different "subuniverses," the probability distribution of its observed values is conditioned by the requirement that there
Inflationary axion cosmology.
TLDR
Consideration of fluctuations induced during inflation severely constrains the latter alternative to Peccei-Quinn symmetry breaking, and it is shown that the former can be evaded.
A Dark Hydrogen Cloud in the Virgo Cluster
VIRGOHI 21 is an H I source detected in the Virgo Cluster survey of Davies et al. that has a neutral hydrogen mass of 108 M☉ and a velocity width of ΔV20 = 220 km s-1. From the Tully-Fisher relation,
...
...