Speaker
Description
Transitional millisecond pulsars (tMSPs) are a unique class of neutron star binaries that switch between an accretion-powered low-mass X-ray binary (LMXB) state and a rotation-powered radio millisecond pulsar (MSP) state. The first confirmed tMSP system, PSR J1023+0038, is currently in an LMXB state, exhibiting rapid mode switching between distinct high, low, and flaring states at X-ray, optical, and other wavelengths. Understanding the physical processes governing these mode transitions is critical for unveiling the accretion mechanisms in tMSPs and their evolutionary link to classical MSPs.
We present an analysis of J1023’s mode transitions using multiwavelength data from Kepler K2, XMM-Newton, and ground-based observations, providing new insights into the accretion flow behavior in transitional systems. Special attention is given to the high-low mode transitions, their ‘recurrence timescales’, and anti-correlation between X-ray and optical variability. By characterizing the mode-dependent flux distributions and error propagation, we provided new evidence to the mechanism driving these transitions. We further explored general changes in optical light curves before and after J1023 state transition. Optical emission was dominated by the irradiated companion star alone during radio MSP state. When the system is in LMXB state, an additional accretion disk effect should be considered. We compared the orbital modulation and concluded that the accretion disk provided more than an offset change to the optical light curves.
Our findings provide new insights into the underlying physics of tMSP state transition and moding behaviours during LMXB state, which contribute to the broader understanding of tMSP evolution dynamics.
