Long term variations in RXJ 0720
De
Vries et al., 2004
Vink,
et al, 2004
A gradual, long
term change in the shape of the
X-ray spectrum AND in
the pulse profile
From rev. 78 (13
May 2000) to rev.711
(27-10-2003) the pulse profile become narrower and the pulsed fraction increases from ~20% to ~ 35%
Pulse profile of 0720 in the 0.1-1.2 keV band and
hardness ratio. The best sinusoidal fit to rev. 0078 (solid line)
is overplotted on the light curve of
rev. 0711 for comparison.