The continued spectral and temporal evolution of RX J0720.4−3125
RX J0720.4−3125 is the most peculiar object among a group of seven isolated X-ray pulsars (the so-called Magnificent Seven), since it shows long-term variations of its spectral and temporal properties on time-scales of years. This behaviour was explained by different authors either by free precessio...
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Published in | Monthly notices of the Royal Astronomical Society Vol. 423; no. 2; pp. 1194 - 1199 |
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Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
Oxford, UK
Blackwell Publishing Ltd
01.06.2012
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Subjects | |
Online Access | Get full text |
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Summary: | RX J0720.4−3125 is the most peculiar object among a group of seven isolated X-ray pulsars (the so-called Magnificent Seven), since it shows long-term variations of its spectral and temporal properties on time-scales of years. This behaviour was explained by different authors either by free precession (with a 7 or 14 yr period) or possibly a glitch that occurred around MJD = 528 66 ± 73 d.
We analysed our most recent XMM-Newton and Chandra observations in order to further monitor the behaviour of this neutron star. With the new data sets, the timing behaviour of RX J0720.4−3125 suggests a single (sudden) event (e.g. a glitch) rather than a cyclic pattern as expected by free precession. The spectral parameters changed significantly around the proposed glitch time, but more gradual variations occurred already before the (putative) event. Since MJD ≈ 530 00 d the spectra indicate a very slow cooling by ∼2 eV over 7 yr. |
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ISSN: | 0035-8711 1365-2966 |
DOI: | 10.1111/j.1365-2966.2012.20946.x |