Discovery of 3 s pulsations from the Brightest Hard X-ray Source in M31

Abstract

We report the discovery with XMM-Newton of 3-s X-ray pulsations from 3XMM J004232.1+411314, a dipping source that dominates the hard X-ray emission of M31. This finding unambiguously assesses the neutron star (NS) nature of the compact object. We also measured an orbital modulation of 4.15 h and a projected semi-axis at $a_{\mathrm{X}}\sin i=0.6$ lt-s, which implies a low-mass companion of about 0.2$-$0.3$M_{\odot }$ assuming a NS of 1.5 $M_{\odot }$ and an orbital inclination $i=70^{\circ }-80^{\circ }$. The barycentric orbit-corrected pulse period decreased by $\sim$28 ms in about 16 yr, corresponding to an average spin-up rate of $\dot{P}\sim -6\times 10^{-11}$ s s${}^{-1}$ ; pulse period variations, probably caused to by X-ray luminosity changes, were observed on shorter time scales. We identify two possible scenarios for the source: a mildly magnetic NS with $B_{\mathrm{p}}\simeq$ few $\times 10^{10}$ G if the pulsar is far from its equilibrium period $P_{\mathrm{eq}}$, and a relatively young highly magnetic NS with $B_{\mathrm{eq}}\simeq 10^{13}$ G if spinning close to $P_{\mathrm{eq}}$.

arXiv comment5 pages, 3 figures, 2 tables, Submitted to the Astrophysical Journal Letters

References in corpus (19)

• The European Photon Imaging Camera on XMM-Newton: The MOS Cameras
• The 70 Month Swift-BAT All-Sky Hard X-Ray Survey
• An accreting pulsar with extreme properties drives an ultraluminous x-ray source in NGC 5907
• Formation of millisecond pulsars with CO white dwarf companions - II. Accretion, spin-up, true ages and comparison to MSPs with He white dwarf companions
• The Distance to the M31 Globular Cluster System
• A new technique for the detection of periodic signals in ``coloured'' power spectra
• On the evolution of anomalous X-ray pulsars and soft gamma ray repeaters with fallback disks
• New Torque Reversal and Spin-Up of 4u 1626- 67 Observed by Fermi/GBM and Swift/BAT
• The spin and orbit of the newly discovered pulsar IGR J17480-2446
• Can disk-magnetosphere interaction models and beat frequency models for quasi-periodic oscillation in accreting X-ray pulsars be reconciled?
• A universal relation for the propeller mechanisms in magnetic rotating stars at different scales
• Implications of burst oscillations from the slowly rotating accreting pulsar IGR 17480-2446 in the globular cluster Terzan 5
• EXTraS discovery of an 1.2-s X-ray pulsar in M 31
• The slowest spinning X-ray pulsar in an extragalactic globular cluster
• Science with the EXTraS Project: Exploring the X-ray Transient and variable Sky
• The pulse profile and spin evolution of the accreting pulsar in Terzan 5, IGR J17480-2446, during its 2010 outburst
• X-Rays Beware: The Deepest Chandra Catalogue of Point Sources in M31
• Identification of the Hard X-ray Source Dominating the E > 25 keV Emission of the Nearby Galaxy M31
• Discovery of periodic dips in the brightest hard X-ray source of M31 with EXTraS

Cited by in corpus (3)

• The EXTraS Project: Exploring the X-ray transient and variable sky
• The EXOD search for faint transients in XMM-Newton observations: Method and discovery of four extragalactic Type I X-ray Bursters
• A LOFAR radio search for single and periodic pulses from M31