Issue |
A&A
Volume 439, Number 2, August IV 2005
|
|
---|---|---|
Page(s) | 427 - 432 | |
Section | Astrophysical processes | |
DOI | https://doi.org/10.1051/0004-6361:20042263 | |
Published online | 29 July 2005 |
Neutrino emission rates in highly magnetized neutron stars revisited
1
Departamento de Astronomía y Astrofísica, Pontificia Universidad Católica de Chile, Casilla 306, Santiago 22, Chile e-mail: areisene@astro.puc.cl
2
Departamento de Física, Universidad Técnica Federico Santa María, Casilla 110-V, Valparaíso, Chile
Received:
27
October
2004
Accepted:
2
April
2005
Magnetars are a subclass of neutron stars whose intense
soft-gamma-ray bursts and quiescent X-ray emission are believed to
be powered by the decay of a strong internal magnetic field.
We reanalyze neutrino emission in such stars in the plausibly
relevant regime in which the Landau band spacing of both protons and electrons is much larger than kT
(where k is the Boltzmann constant and T is the temperature),
but still much smaller than the Fermi energies. Focusing on the
direct Urca process, we find that the emissivity oscillates as a function of density or
magnetic field, peaking when the Fermi level of the protons or
electrons lies about ~
above the bottom of any of their
Landau bands. The oscillation amplitude is comparable to the
average emissivity when
is roughly the geometric mean
of kT and the Fermi energy (excluding mass), i.e., at fields
much weaker than required to confine all particles to the lowest
Landau band. Since the density and magnetic field strength vary
continuously inside the neutron star, there will be alternating
surfaces of high and low emissivity. Globally, these oscillations
tend to average out, making it unclear whether there will be any
observable effects.
Key words: dense matter / neutrinos / stars: magnetic fields / stars: neutron
© ESO, 2005
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