Abstract
We present new fast numerical simulations of cosmic microwave background and large scale structure in the case in which the cosmological dark matter is made entirely or partly made of mirror matter. We consider scalar adiabatic primordial perturbations at linear scales in a flat Universe. The speed of the simulations allows us for the first time to use Markov Chain Monte Carlo analyses to constrain the mirror parameters. A Universe with pure mirror matter can fit very well the observations, equivalently to the case of an admixture with cold dark matter. In both cases, the cosmological models estimate the presence of a consistent amount of mirror dark matter, 0.06≲Ωmirrorh2≲0.12.
Highlights
The existence of dark matter in the Universe seems to be an unavoidable evidence, as confirmed by all the currently available astrophysical observations at scales ranging from cosmological to galactic
That the matter-radiation decouplings (MRD) in the mirror sector occurs earlier than in the ordinary one. It has been shown [2, 12] that, comparing Eqs. (3) and (4), for x smaller than a typical value xeq the mirror photons would decouple yet during the radiation dominated period, and the evolution of primordial perturbations in the linear regime is practically identical to the standard cold dark matter (CDM) case
1 + zbγ Previous analytical and numerical studies on cosmic microwave background (CMB) and large scale structure (LSS) power spectra [1,2,3,4,5,6, 22] have only shown, using a qualitative comparison with observations, that: (i) for low values of mirror temperatures (x 0.3) all the dark matter can be made of mirror baryons; (ii) for high values (x 0.3) mirror baryons can be present as an admixture with CDM
Summary
The existence of dark matter in the Universe seems to be an unavoidable evidence, as confirmed by all the currently available astrophysical observations at scales ranging from cosmological to galactic. Previous analytical and numerical studies on CMB and LSS power spectra [1,2,3,4,5,6] have only limited the parameter space of mirror dark matter, without providing a definitive cosmological answer to its existence.
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