5,736 research outputs found
Measuring dark matter-neutrino relative velocity on cosmological scales
We present a new method to measure neutrino masses using the dark
matter-neutrino relative velocity. The relative motion between dark matter and
neutrinos results in a parity-odd bispectrum which can be measured from
cross-correlation of different cosmic fields. This new method is not affected
by most systematics which are parity even and not limited by the knowledge of
optical depth to the cosmic microwave background. We estimate the detectability
of the relative velocity effect and find that the minimal sum of neutrino
masses could be detected at high significance with upcoming surveys.Comment: 6 pages, 2 figures, 1 table, published versio
Testing cosmic opacity from SNe Ia and Hubble parameter through three cosmological-model-independent methods
We use the newly published 28 observational Hubble parameter data ()
and current largest SNe Ia samples (Union2.1) to test whether the universe is
transparent. Three cosmological-model-independent methods (nearby SNe Ia
method, interpolation method and smoothing method) are proposed through
comparing opacity-free distance modulus from Hubble parameter data and
opacity-dependent distance modulus from SNe Ia . Two parameterizations,
and are adopted for the
optical depth associated to the cosmic absorption. We find that the results are
not sensitive to the methods and parameterizations. Our results support a
transparent universe.Comment: 11 pages, 8 figures, 1 table, PLB(in press
Probing Neutrino Hierarchy and Chirality via Wakes
The relic neutrinos are expected to acquire a bulk relative velocity with
respect to the dark matter at low redshifts, and neutrino wakes are expected to
develop downstream of the dark matter halos. We propose a method of measuring
the neutrino mass based on this mechanism. This neutrino wake will cause a
dipole distortion of the galaxy-galaxy lensing pattern. This effect could be
detected by combining upcoming lensing surveys with a low redshift galaxy
survey or a 21 cm intensity mapping survey, which can map the neutrino flow
field. The data obtained with LSST and Euclid should enable us to make a
positive detection if the three neutrino masses are quasidegenerate with each
neutrino mass of 0.1 eV, and a future high precision 21 cm lensing survey
would allow the normal hierarchy and inverted hierarchy cases to be
distinguished, and even the right-handed Dirac neutrinos may be detectable.Comment: 5 pages, 4 figures, v2 matches the published versio
- …