Aql X-1 is a transient source hosting a fastly spinning weakly magnetic neutron star, showing recurrent outbursts at a rate of 1-2 per year. During one of these, BeppoSAX allowed to monitoring the return to quiescence: the X-ray luminosity decreased very rapidly with an e-folding time of about 1 day. This rapid decay was accompanied by a steep increase in the hardness ratio, interpreted as the onset of the propeller regime. Moreover, the neutron star parameters suggests that the quiescent luminosity is powered by shock emission from an underlying (enshrouded) radio pulsar. We propose to observe these transitions with XMM in order to gain crutial insight in the propeller physics as well as in the transition to quiescence of Aql X-1.
Instrument
EMOS1, EMOS2, EPN, OM, RGS1, RGS2
Temporal Coverage
2010-10-12T21:39:30Z/2010-11-02T09:08:36Z
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, Dr Sergio Campana, 2011, 'Observing Aql X-1 during the transition to quiescence', 17.56_20190403_1200, European Space Agency, https://doi.org/10.5270/esa-5xb4qu0
