A 'patchwork' of INTEGRAL data for the recent outburst of the transient Be/X-ray pulsar 1A0535+262
This 'patchwork' demonstrates the variety of data INTEGRAL
provides for the recent outburst of the transient Be/X-ray
pulsar 1A0535+262.
The panel at the top compares the long term optical lightcurve,
measured serendipitously by the OMC in red with the RXTE ASM
lightcurve in light blue. A dimming of the system before and through
the X-ray outbursts is clearly visible. The inset shows the optical
lightcurve during the INTEGRAL TOO observations with variability
typical for Be stars and the ISGRI lightcurve.
The lower left panel displays results of fitting combined JEM-X,
ISGRI and SPI spectra with models including no lines (residuals a),
one broad cyclotron line at ~45 keV (residuals b) and two lines
(residuals c). This determines the magnetic field to be about
4*10^12 Gauss. In previous observations with other missions only
the line above 100 keV was clearly seen and assumed to be the
fundamental, leading to a wrong determination of the pulsar's
magnetic field strength at more than twice the correct value.
Finally, the high energy pulse profile at the right shows the
known two pulses with evidently different spectral hardness.
The profile resembles older observations from 1994 and 1989 but
with some distinct differences indicating possible changes in
the accretion and emission geometry.
