On the peculiar long-term orbital evolution of the eclipsing accreting millisecond X-ray pulsar SWIFT J1749.4-2807

Abstract

We present the pulsar timing analysis of the accreting millisecond X-ray pulsar SWIFT J1749.4-2807 monitored by NICER and XMM-Newton during its latest outburst after almost eleven years of quiescence. From the coherent timing analysis of the pulse profiles, we updated the orbital ephemerides of the system. Large phase jumps of the fundamental frequency phase of the signal are visible during the outburst, consistent with what was observed during the previous outburst. Moreover, we report on the marginally significant evidence for non-zero eccentricity ($e\simeq 4\times 10^{-5}$) obtained independently from the analysis of both the 2021 and 2010 outbursts and we discuss possible compatible scenarios. Long-term orbital evolution of SWIFT J1749.4-2807 suggests a fast expansion of both the NS projected semi-major axis $(x)$, and the orbital period $(P_{\mathrm{orb}})$, at a rate of $\dot{x}\simeq 2.6\times 10^{-13}\text{lt-s}{\text{s}}^{-1}$ and ${\dot{P}}_{\mathrm{orb}}\simeq 4\times 10^{-10}\text{s}{\text{s}}^{-1}$, respectively. SWIFT J1749.4-2807 is the only accreting millisecond X-ray pulsar, so far, from which the orbital period derivative has been directly measured from appreciable changes on the observed orbital period. Finally, no significant secular deceleration of the spin frequency of the compact object is detected, which allowed us to set a constraint on the magnetic field strength at the polar caps of $B_{PC}<1.3\times 10^8\text{G}$, in line with typical values reported for AMXPs.

13 pages, 3 figures, 1 table. Accepted for publication in MNRAS

References in corpus (16)

• Orbital Evolution of an Accreting Millisecond Pulsar: Witnessing the Banquet of a Hidden Black Widow?
• The mass-radius relationship from solar-type stars to terrestrial planets: a review
• Three-dimensional Simulations of Accretion to Stars with Complex Magnetic Fields
• Timing of the Accreting Millisecond Pulsar XTE J1814-338
• Order in the Chaos: Spin-up and Spin-down during the 2002 Outburst of SAX J1808.4-3658
• Gamma-ray Timing of Redback PSR J2339-0533: Hints for Gravitational Quadrupole Moment Changes
• New ephemeris of the ADC source 2A 1822-371: a stable orbital-period derivative over 30 years
• Timing of the 2008 Outburst of SAX J1808.4-3658 with XMM-Newton: A Stable Orbital Period Derivative over Ten Years
• Timing an Accreting Millisecond Pulsar: Measuring the Accretion Torque in IGR J00291+5934
• On the timing properties of SAX J1808.4-3658 during its 2015 outburst
• Spin up and phase fluctuations in the timing of the accreting millisecond pulsar XTE J1807-294
• Spectral and timing properties of IGR J00291+5934 during its 2015 outburst
• Indications of non-conservative mass-transfer in AMXPs
• A possible cyclotron resonance scattering feature near 0.7 keV in X1822-371
• Long-term coherent timing of the accreting millisecond pulsar IGR J17062-6143
• Updated orbital ephemeris of the ADC source X 1822-371: a stable orbital expansion over 40 years

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• Outflows and spectral evolution in the eclipsing AMXP SWIFT J1749.4-2807 with NICER, XMM-Newton and NuSTAR
• MAXI J1957+032: a new accreting millisecond X-ray pulsar in an ultra-compact binary
• Timing analysis of the 2022 outburst of the accreting millisecond X-ray pulsar SAX J1808.4$-$3658: hints of an orbital shrinking
• The AstroSat observation of accreting millisecond X-ray pulsar SAX J1808.4-3658 during its 2019 outburst
• Updated Orbital Ephemeris and Detection of Superhump Modulation in X-ray Band for the Ultra-Compact Low Mass X-ray Binary 4U 1820-30
• Detection of low-luminosity X-ray pulsations from the accreting millisecond pulsar IGR J17511-3057: An ever-thinning thread between bright accretion and sub-luminous states
• Thermonuclear Type-I X-ray Bursts and Burst Oscillations from the Eclipsing AMXP Swift J1749.4-2807
• The 2025 outburst of IGR J17511-3057: timing and spectral insights from NICER and NuSTAR