Title: Are Magnetars really Magnetars?
Abstract: Anomalous X-ray Pulsars (AXPs) and Soft Gamma-ray Repeaters (SGRs) are young neutron stars with X-ray luminosities much larger than their spin-down power
and long periods in the range 2 - 12 s. They are widely believed to be magnetars
deriving their X-ray emission from the decay of super-strong magnetic fields (~
10^15 G). The magnetar model was developed to explain the giant and the large
bursts of SGRs, which exceed the Eddington limit of neutron-star luminosities by a
very large factor. Furthermore, in the magnetar picture, the steady-state X-ray
emission is thought to be caused by a twist of the magnetosphere leading to the
amplification of the magnetic field and the acceleration of particles, which
produce the X-ray emission.
An alternative picture will be presented which explains many of the existing
observations. The transient and steady-state X-ray emission is explained by
accretion of matter from a fallback disk onto a neutron star with normal magnetic
field (10^12 - 10^13 G). This picture explains in a natural way not only the
observed soft and hard X-ray spectra, but also the energy-dependent purse profiles
and the change in pulse profile observed during a burst in SGR 1900+14. Evidence
will be presented for accretional power and normal magnetic-field strength.