AX J1910.7+0917: the slowest X-ray pulsar

Abstract

Pulsations from the high mass X-ray binary AX J1910.7+0917 were discovered during Chandra observations performed in 2011 (Israel et al. 2016). We report here more details on this discovery and discuss the source nature. The period of the X-ray signal is P = 36200 ± 110 s, with a pulsed fraction, P F , of 63±4%. Given the association with a massive B-type companion star, we ascribe this long periodicity to the rotation of the neutron star, making AX J1910.7+0917 the slowest known X-ray pulsar. We report also on the spectroscopy of XMM-Newton observations that serendipitously covered the source field, resulting in an highly absorbed (column density almost reaching 10 23 cm −2 ), power law X-ray spectrum. The Xray flux is variable on a timescale of years, spanning a dynamic range 60. The very long neutron star spin period can be explained within a quasi-spherical settling accretion model, that applies to low luminosity, wind-fed, X-ray pulsars.

Accreting magnetars: linking ultraluminous X-ray pulsars and the slow pulsation X-ray pulsars

“…The X-ray source AX J1910.7+0917 has pulsation period of 36.2 ks ∼ 10 h (Sidoli et al 2017). Its X-ray luminosity ranges from 1.7 × 10 34 erg s −1 -10 36 erg s −1 .…”

“…It may be the slowest pulsation X-ray pulsar at present. The nature of AX J1910.7+0917 may be a wind accreting neutron star with normal magnetic field about 10 12 G (Sidoli et al 2017 and references therein). According to the equilibrium period of disk accretion (equation (8)), if AX J1910.7+0917 has a dipole magnetic field of 4 × 10 15 G (corresponds to µ30 = 2 × 10 3 ) and accretion rate ofṀ17 ∼ 10 −3 , then its pulsation period can also be understood in the accreting magnetar scenario.…”

Identification of two new HMXBs in the LMC: an ∼2013 s pulsar and a probable SFXT

“…The torques acting on the quasi-static plasma shell above the magnetosphere can either spin-up or spin-down the NS. Because of the short relaxation time (∼10 4 yr -see also Sidoli et al 2017a), it is reasonable to assume that the NS is at an equilibrium state, where its spin period remains constant with time and is given by (Shakura et al 2012;Shakura & Postnov 2017):…”

Do the periodic activities of repeating fast radio bursts represent the spins of neutron stars?

“…None of disk wind phenomenon was detected in isolated NS-systems, 4. The slowest isolated pulsar and accreting X-ray binary pulsar are 1E 161348+ 5055 with P spin ≈ 24000s (De Luca et al 2006) and AX J1910.7+0917 with P spin ≈ 36200s (Sidoli et al 2017), respectively. But they are all detected in X-ray and no radio observation reported, which maybe indicate that they are in the "grave yard" of radio pulsars.…”