Manuel Malheiro, Jorge A. Rueda, Remo Ruffini
The recent observations of SGR 0418+5729 offer an authentic Rosetta Stone for
deciphering the energy source of Soft Gamma Ray Repeaters (SGRs) and Anomalous
X-ray Pulsars (AXPs). The main contention is to determine if SGRs and AXPs are
strongly magnetized neutron stars originating their energy from the decay of
overcritical magnetic fields in the magnetar model or if instead their
energetics can be explained by using the rotational energy loss of a white
dwarf. We show how a consistent model for SGRs and AXPs can be expressed in
terms of canonical physics and astrophysics within rotation powered white
dwarfs in total analogy with the case of pulsars originating their energy from
the rotational energy of the neutron stars. The pioneering works of M. Morini
et al. (1988) and of B. Paczynski (1990) on 1E 2259+586 are extended and
further developed to describe the observed properties of SGRs and AXPs assuming
spin-down powered massive, fast rotating, and highly magnetized white dwarfs.
We show that SGR 0418+5729 is well described by white dwarf and, within such a
model, we obtain the theoretical prediction for the lower limit of its
spin-down rate, $\dot{P} \geq = 1.18\times 10^{-16}$. We analyze the energetics
of SGRs and AXPs including their outburst activities and show that they can be
explained through the change of rotational energy of the white dwarf associated
to the observed glitches. All SGRs and AXPs can be interpreted as rotating
white dwarfs that generate their energetics from the rotational energy and
therefore there is no need to invoke the magnetic field decay of the magnetar
model. The observational campaigns carried out by the X-ray Japanese satellite
Suzaku on AE Aquarii as well as the corresponding theoretical work by Japanese
groups and recent results of the Hubble Space Telescope, give crucial
information for our theoretical model.
View original:
http://arxiv.org/abs/1102.0653
No comments:
Post a Comment