PROJECTS
of the
Relativistic
Astrophysics Group
Magneto-thermal evolution and thermal radiation of neutron stars.
The thermal
emission from isolated neutron stars is not well understood. The
X-ray spectrum
is very close to a blackb
ody but there is a systematic optical excess flux with respect
to the extrapolation to low energy of the best blackbody
fit. This fact, in combination with the observed pulsations in the
X-ray flux, can be explained by anisotropies
in the surface temperature distribution. To explain the origin of
this anisotropy we study the thermal emission
from neutron star
s with strong crustl magnetic fields, which causes a
non-spherically symmetric temperature distribution. On the other ha
nd, the strong temperature dependence of the magnetic
diffusivity and thermal conductivity, together with the heat generated
by magnetic dissipation, couple the magnetic and thermal evolution of
NSs, that cannot be formulated as separated one--dimensional
problems. We are interested in the mutual influence of
thermal and magnetic evolution in a neutron star's crust, and its
observational effects.
Relativistic Magneto-Hydrodynamics
Simulations.
We are engaged in numerical simulations of different astrophysical scenarios involving MHD processes (core collapse Supernovae, gravitational collapse of neutron stars). The possibility of metastable PNS (those that become unstable to collapse during the early evolution) has been suggested in the context of SN 1987A, for which no neutron star remnant has been observed. We are also interested in the study of the deleptonization driven collapse of metastable PNS. Modelling will be done with a general relativistic hydrodynamics code, including neutrino transport.
According to General Relativity, the
emission of gravitational waves is
associated to a variety of
physical processes that range from astrophysical phenomena - such as
the evolution and
coalescence of binary systems, gravitational collapse, stellar
oscillations
and instabilities - to
cosmological processes that developed in the very early universe.
Signals
produced in these processes have different intensities, shapes and
characteristic frequencies;
some of them are emitted
in short bursts, some are continuous, some superimpose to form
stochastic
backgrounds with
spectral properties that depend on the generating phenomenon. The Rome
group is concerned
primarily with the study of the characteristic features of
gravitational
signals emitted by
astrophysical sources, and of the spectral properties of stochastic
backgrounds they generate.
