46,950 research outputs found
Stars and Fundamental Physics
Stars are powerful sources for weakly interacting particles that are produced
by nuclear or plasma processes in their hot interior. These fluxes can be used
for direct measurements (e.g. solar or supernova neutrinos) or the
back-reaction on the star can be used to derive limits on new particles. We
discuss two examples of current interest, the search for solar axions by the
CAST experiment at CERN and stellar-evolution limits on the size of putative
large extra dimensions.Comment: Contribution to ESO-CERN-ESA Symposium on Astronomy, Cosmology and
Fundamental Physics (4-7 March 2002, Garching, Germany), additional
references in revised versio
GRBs and fundamental physics
Gamma-ray bursts (GRBs) are short and intense flashes at the cosmological
distances, which are the most luminous explosions in the Universe. The high
luminosities of GRBs make them detectable out to the edge of the visible
universe. So, they are unique tools to probe the properties of high-redshift
universe: including the cosmic expansion and dark energy, star formation rate,
the reionization epoch and the metal evolution of the Universe. First, they can
be used to constrain the history of cosmic acceleration and the evolution of
dark energy in a redshift range hardly achievable by other cosmological probes.
Second, long GRBs are believed to be formed by collapse of massive stars. So
they can be used to derive the high-redshift star formation rate, which can not
be probed by current observations. Moreover, the use of GRBs as cosmological
tools could unveil the reionization history and metal evolution of the
Universe, the intergalactic medium (IGM) properties and the nature of first
stars in the early universe. But beyond that, the GRB high-energy photons can
be applied to constrain Lorentz invariance violation (LIV) and to test
Einstein's Equivalence Principle (EEP). In this paper, we review the progress
on the GRB cosmology and fundamental physics probed by GRBs.Comment: 38 pages, 18 figures, Review based on ISSI workshop "Gamma-Ray
Bursts: a Tool to Explore the Young Universe" (2015, Beijing, China),
accepted for publication in Space Science Review
Black holes and fundamental physics
We give a review of classical, thermodynamic and quantum properties of black
holes relevant to fundamental physics.Comment: Invited talk at the Fifth International Workshop on New Worlds in
Astroparticle Physics, University of the Algarve, Faro, Portugal, January
8-10, 2005, published in the Proceedings of the Fifth International Workshop
on New Worlds in Astroparticle Physics, World Scientific (2006), eds. Ana M.
Mour\~ao et al., p. 71-9
Cosmological Term and Fundamental Physics
A nonvanishing cosmological term in Einstein's equations implies a
nonvanishing spacetime curvature even in absence of any kind of matter. It
would, in consequence, affect many of the underlying kinematic tenets of
physical theory. The usual commutative spacetime translations of the Poincare'
group would be replaced by the mixed conformal translations of the de Sitter
group, leading to obvious alterations in elementary concepts such as time,
energy and momentum. Although negligible at small scales, such modifications
may come to have important consequences both in the large and for the
inflationary picture of the early Universe. A qualitative discussion is
presented which suggests deep changes in Hamiltonian, Quantum and Statistical
Mechanics. In the primeval universe as described by the standard cosmological
model, in particular, the equations of state of the matter sources could be
quite different from those usually introduced.Comment: RevTeX, 4 pages. Selected for Honorable Mention in the Annual Essay
Competition of the Gravity Research Foundation for the year 200
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