Search results for " Cosmology"
showing 10 items of 1486 documents
Evaporation of Near-Extremal Reissner-Nordström Black Holes
2000
The formation of near-extremal Reissner-Nordstrom black holes in the S-wave approximation can be described, near the event horizon, by an effective solvable model. The corresponding one-loop quantum theory remains solvable and allows to follow analytically the evaporation process which is shown to require an infinite amount of time.
Critical energy flux and mass in solvable theories of 2D dilaton gravity
1998
In this paper we address the issue of determining the semiclassical threshold for black hole formation in the context of a one-parameter family of theories which continuously interpolates between the RST and BPP models. We find that the results depend significantly on the initial static configuration of the spacetime geometry before the influx of matter is turned on. In some cases there is a critical energy density, given by the Hawking rate of evaporation, as well as a critical mass $m_{cr}$ (eventually vanishing). In others there is neither $m_{cr}$ nor a critical flux.
Integrable models and degenerate horizons in two-dimensional gravity
1999
We analyse an integrable model of two-dimensional gravity which can be reduced to a pair of Liouville fields in conformal gauge. Its general solution represents a pair of ``mirror'' black holes with the same temperature. The ground state is a degenerate constant dilaton configuration similar to the Nariai solution of the Schwarzschild-de Sitter case. The existence of $\phi=const.$ solutions and their relation with the solution given by the 2D Birkhoff's theorem is then investigated in a more general context. We also point out some interesting features of the semiclassical theory of our model and the similarity with the behaviour of AdS$_2$ black holes.
Testing standard and nonstandard neutrino physics with cosmological data
2012
Cosmological constraints on the sum of neutrino masses and on the effective number of neutrino species in standard and nonstandard scenarios are computed using the most recent available cosmological data. Our cosmological data sets include the measurement of the baryonic acoustic oscillation (BAO) feature in the data release 9 CMASS sample of the baryon oscillation spectroscopic survey. We study in detail the different degeneracies among the parameters, as well as the impact of the different data sets used in the analyses. When considering bounds on the sum of the three active neutrino masses, the information in the BAO signal from galaxy clustering measurements is approximately equally pow…
New horizons for fundamental physics with LISA
2022
K. G. Arun et al.
Halo-independent methods for inelastic dark matter scattering
2013
We present halo-independent methods to analyze the results of dark matter direct detection experiments assuming inelastic scattering. We focus on the annual modulation signal reported by DAMA/LIBRA and present three different halo-independent tests. First, we compare it to the upper limit on the unmodulated rate from XENON100 using (a) the trivial requirement that the amplitude of the annual modulation has to be smaller than the bound on the unmodulated rate, and (b) a bound on the annual modulation amplitude based on an expansion in the Earth's velocity. The third test uses the special predictions of the signal shape for inelastic scattering and allows for an internal consistency check of …
Spritz: General relativistic magnetohydrodynamics with neutrinos
2020
We here present a new version of the publicly available general relativistic magnetohydrodynamic (GRMHD) code $\texttt{Spritz}$, which now includes an approximate neutrino leakage scheme able to handle neutrino cooling and heating. The leakage scheme is based on the publicly available $\texttt{ZelmaniLeak}$ code, with a few modifications in order to properly work with $\texttt{Spritz}$. We discuss the involved equations, physical assumptions, and implemented numerical methods, along with a large battery of general relativistic tests performed with and without magnetic fields. Our tests demonstrate the correct implementation of the neutrino leakage scheme, paving the way for further improvem…
Discovery potential of xenon-based neutrinoless double beta decay experiments in light of small angular scale CMB observations
2013
The South Pole Telescope (SPT) has probed an expanded angular range of the CMB temperature power spectrum. Their recent analysis of the latest cosmological data prefers nonzero neutrino masses, with Sigma m(nu) = (0.32 +/- 0.11) eV. This result, if con firmed by the upcoming Planck data, has deep implications on the discovery of the nature of neutrinos. In particular, the values of the effective neutrino mass m(beta beta) involved in neutrinoless double beta decay (beta beta 0 nu) are severely constrained for both the direct and inverse hierarchy, making a discovery much more likely. In this paper, we focus in xenon-based beta beta 0 nu experiments, on the double grounds of their good perfo…
Multiple expansions for energy and momenta carried by gravitational waves
2007
We present expressions for the energy, linear momentum and angular momentum carried away from an isolated system by gravitational radiation based on spin-weighted spherical harmonics decomposition of the Weyl scalar $\Psi_4$. We also show that the expressions derived are equivalent to the common expressions obtained when using a framework based on perturbations of a Schwazschild background. The main idea is to collect together all the different expressions in a uniform and consistent way. The formulae presented here are directly applicable to the calculation of the radiated energy, linear momentum and angular momentum starting from the gravitational waveforms which are typically extracted f…
Dark coupling
2009
30 pages, 10 figures, 3 tables.-- Pre-print archive.