Discovery of a glitch in the accretion-powered pulsar SXP 1062

Abstract

We present timing analysis of the accretion powered pulsar SXP 1062, based on the observations of Swift, XMM-Newton and Chandra satellites covering a time span of about 2 years. We obtain a phase coherent timing solution which shows that SXP 1062 has been steadily spinning down with a rate − 4.29(7) × 10 −14 Hz s −1 leading to a surface magnetic field estimate of about 1.5 × 10 14 G. We also resolve the binary orbital motion of the system from X-ray data which confirms an orbital period of 656(2) days. On MJD 56834.5, a sudden change in pulse frequency occurs with ∆ν = 1.28(5) × 10 −6 Hz, which indicates a glitch event. The fractional size of the glitch is ∆ν/ν ∼ 1.37(6) ×10 −3 and SXP 1062 continues to spin-down with a steady rate after the glitch. A short X-ray outburst 25 days prior to the glitch does not alter the spin-down of the source; therefore the glitch should be associated with the internal structure of the neutron star. While glitch events are common for isolated pulsars, the glitch of SXP 1062 is the first confirmation of the observability of this type of events among accretion powered pulsars. Furthermore, the value of the fractional change of pulse frequency ensures that we discover the largest glitch reported up to now.

On the Geometry of the X-ray emission from pulsars a consistent inclination and beaming solution for the Be/X-ray pulsar SXP 1062

“…This figure covers one revolution of the NS. reported by Serim et al (2017). The folded pulse profile still exhibits a double-peaked structure as it did before, however the peaks are now separated by nearly a full half-phase ( Fig.…”

“…Incorporating the orbital inclination angle calculated by Serim et al (2017) along with the orientation of the circumstellar disk (Gonzales-Galan et al 2017) and the inclincation of the NS spin axis derived in this work, a picture of the SXP 1062 system as a whole begins to emerge (see Fig. 11).…”

“…There have been three Type I outbursts observed which, along with optical data, have constrained the orbital period (P orb ) for this system to 668 ± 10 days (Gonzales-Galan et al 2017). The orbital eccentricity is low for a NS BeXRB, given as e ≤ 0.2, with the orbital inclination angle calculated to be 73 Serim et al (2017), utilizing a pulse-arrival timing technique from multiple SWIFT observations.…”

Anti-glitches in the Ultraluminous Accreting Pulsar NGC 300 ULX-1 Observed with NICER

“…For pulsars that accrete matter from a binary companion, the torque due to accretion can cause the neutron star to spin-up or spindown and is usually much stronger than the dipole radiation torque. There are only a few reported glitches in accreting pulsars: two spin-up glitches with ∆ν ≈ 1 µHz, each occurring during an accretion outburst episode (Galloway et al 2004;Serim et al 2017), and possibly two spin-down glitches (Klochkov et al 2009).…”

Not an oxymoron: some X-ray binary pulsars with enormous spin-up rates reveal weak magnetic fields

“…It will have to be confronted by denser data 2 We suspect that the magnetosphere expanded prior to d = 586 and then it was pushed back during d = 586-621 ( Fig. 1) because a strong spinup glitch was reported by Serim et al (2017) (Table 4) that we also suspect that future glitches in HMXBs will be indicative of jerking of their magnetospheres.…”