Within seven radio-quiet, thermally-emitting isolated NSs, RXJ 0720 is unique inthat it shows long-term (virgulyrs) variations in its spectral parameters. Applying aphase-coherent timing solution with constant spin down leaves large residualswhich may follow a cyclic pattern. The reasons for this behaviour is a matter ofdebate. Both a glitch and precession have been invoked, but present data do notallow to reach a firm conclusion. Most recent XMM observations show that the re-siduals probably reached a minimum of the cycle, while the spectral parametersevolution slowed down. The proposed observations will prove if the timing re-siduals follow a cyclic pattern and weather the spectral and timing variationsare related. The outcome will rule out one of the two proposed scenarios
Instrument
EMOS1, EMOS2, EPN, OM, RGS1, RGS2
Temporal Coverage
2011-04-10T23:59:26Z/2011-04-11T06:04:39Z
Version
17.56_20190403_1200
Mission Description
The European Space Agencys (ESA) X-ray Multi-Mirror Mission (XMM-Newton) was launched by an Ariane 504 on December 10th 1999. XMM-Newton is ESAs second cornerstone of the Horizon 2000 Science Programme. It carries 3 high throughput X-ray telescopes with an unprecedented effective area, and an optical monitor, the first flown on a X-ray observatory. The large collecting area and ability to make long uninterrupted exposures provide highly sensitive observations. Since Earths atmosphere blocks out all X-rays, only a telescope in space can detect and study celestial X-ray sources. The XMM-Newton mission is helping scientists to solve a number of cosmic mysteries, ranging from the enigmatic black holes to the origins of the Universe itself. Observing time on XMM-Newton is being made available to the scientific community, applying for observational periods on a competitive basis.
European Space Agency, Mr Markus Hohle, 2012, 'RX J0720.4-3125 - a free precessing X-ray pulsarquestionMark', 17.56_20190403_1200, European Space Agency, https://doi.org/10.5270/esa-i6icd00
