The Reflares and Outburst Evolution in the Accreting Millisecond Pulsar SAX J1808.4-3658: a Disk Truncated Near Co-rotation?

Understand

The accreting millisecond X-ray pulsar SAX J1808.4--3658 shows peculiar low luminosity states known as "reflares" after the end of the main outburst.

• During this phase the X-ray luminosity of the source varies by up to three orders of magnitude in less than 1-2 days.
• The lowest X-ray luminosity observed reaches a value of ~1e32 erg/s, only a factor of a few brighter than its typical quiescent level.
• We investigate the 2008 and 2005 reflaring state of SAX J1808.4-3658 to determine whether there is any evidence for a change in the accretion flow with respect to the main outburst.