Timing analysis of the 2022 outburst of the accreting millisecond X-ray pulsar SAX J1808.4-3658: hints of an orbital shrinking

We present a pulse timing analysis of NICER observations of the accreting millisecond X-ray pulsar SAX J1808.4-3658 during the outburst that started on 2022 August 19. Similar to previous outbursts, after decaying from a peak luminosity of \simeq 1\times10^{36} \, \mathrm{erg \, s^{-1}} in about a week, the pulsar entered... Show more