The longest AMXP outburst: looking for pulsation in MAXI J0911-655 after 450 days
Abstract
MAXI J0911-655 (J0911) is a new rare accreting millisecond X-ray pulsar (AMXPs), spinning at 340 Hz in NGC 2808. Since the latest XMM observation, the source has been monitored by Swift and INTEGRAL (ATel #10425). Astonishingly, the source proved to be still in outburst after more than 450 days. This is by far a record for an AMXP, whose outburst usually last 2-3 weeks. Standing the current flux of the source, we propose a 30 ks Chandra HRC-S timing mode DDT ToO aiming to i) detect the pulsation, ii) obtain a precise spin frequency value to obtain, for the first time, a direct measurement of the spin frequency variation (expected to be 1e-5Hz) during the same outburst, iii) improve orbital parameters. Those information have strong scientific return, because the presence of the pulsation will settle the still debated model of the magnetic field burial under accretion, and the measurement of nudot will permit to test the accretion mechanism and the role in it of the magnetic field.
- Publication:
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Chandra Proposal
- Pub Date:
- September 2016
- Bibcode:
- 2016cxo..prop.5061R