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| Paper: |
A Study of the Long Term Variability of RX J1856.5–3754 with XMM-Newton |
| Volume: |
466, Electromagnetic Radiation from Pulsars and Magnetars |
| Page: |
33 |
| Authors: |
Mereghetti, S.; Sartore, N.; Tiengo, A.; De Luca, A.; Turolla, R.; Haberl, F. |
| Abstract: |
We report on a detailed spectral analysis of all the available XMM-Newton data of RX J1856.5–3754 , the
brightest and most extensively observed nearby, thermally emitting neutron star. Very small
variations (∼1-2%) in the single-blackbody temperature are detected, but are probably due to
an instrumental effect, since they correlate with the position of the source on the detector.
Restricting the analysis to a homogeneous subset of observations, with the source at the same
detector position, we place strong limits on possible spectral or flux variations from March 2005
to present-day. A slightly higher temperature (kT∼61.5 eV, compared to the average value
kT∼61 eV) was instead measured in April 2002. If this difference is not of instrumental
origin, it implies a rate of variation of about 0.15 eV yr-1 between April 2002 and March
2005. The high-statistics spectrum from the selected observations is well fit by the sum of two
blackbody models, which extrapolate to an optical flux level in agreement with the observed value. |
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