Abstract
We compare the observed galaxy stellar mass distributions in the redshift range with expectations of the cold ΛCDM and warm ΛWDM dark matter models, and obtain the warm dark matter cut-off wavenumber: . This result is in agreement with the independent measurements with spiral galaxy rotation curves, confirms that kfs is due to warm dark matter free-streaming, and is consistent with the scenario of dark matter with no freeze-in and no freeze-out. Detailed properties of warm dark matter can be derived from kfs. The data disfavors the ΛCDM model.
Highlights
Most current cosmological observations are well described by the cold dark matter ΛCDM model with only six independent parameters, and a few assumptions that are consistent with present observations: flat space, a cosmological constant, and scale invariant adiabatic primordial density perturbations [1]
This result is in agreement with the independent measurements with spiral galaxy rotation curves, confirms that kfs is due to warm dark matter free-streaming, and is consistent with the scenario of dark matter with no freeze-in and no freeze-out
Detailed properties of warm dark matter can be derived from kfs
Summary
Most current cosmological observations are well described by the cold dark matter ΛCDM model with only six independent parameters, and a few assumptions that are consistent with present observations: flat space, a cosmological constant, and scale invariant adiabatic primordial density perturbations [1]. This economical description of the universe is apparently in agreement with all observations on large scales, but seems to have tensions with some small scale phenomena: the “cusp vs core” problem of spiral galaxies, i.e. simulations obtain a cusp while observations find a core, and the “missing satellite” problem [2]. Fits to spiral galaxy rotation curves obtain a non-negligible dark matter free-streaming length [3] This free-streaming cuts off the power spectrum of linear density perturbations at a comoving wavenumber kfs. Adding this parameter to the ΛCDM model obtains the warm dark matter model (ΛWDM)
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