长周期射电瞬变源中的白矮星+M型矮星不接双星：观测到的双星参数、演化及种群限制

本文研究了长周期射电瞬变源（LPTs）中与白矮星和M型矮星组成的双星系统相关的特性。通过对ILT J1101+5521进行光波分光观测，确认了其轨道周期与射电周期相匹配，并发现这些系统具有大质量、低温且接近正向的特征。研究结果表明，相干射电脉冲的产生可能与系统的轨道倾角密切相关。

arXiv:2604.18688v2 Announce Type: replace Abstract: Long period radio transients (LPTs) are the slowest radio-pulsing sources ever found, with the current population spanning periods of seven minutes to over six hours. Two of the thirteen published LPTs, ILT J1101+5521 and GLEAM-X J0704--37, have been associated with an M dwarf closely orbiting a white dwarf (WD) through optical spectroscopy. Here, we present new Keck I/LRIS optical spectroscopy of ILT J1101+5521, which reveals H$\alpha$ emission from the M dwarf and confirms an orbital period nearly matching the radio period (2.092 hr). Radio pulses in both systems arrive just after maximum M dwarf redshift, assuming the radio period matches the orbital period. Based on Gaia proper motions and systemic velocities, we find that these systems are kinematically hotter and less concentrated in the Galactic plane than other LPTs. Both systems harbor unusually massive and cool WDs, with $M_\mathrm{WD} \approx 0.84-1.0 M_\odot$ and $T_\mathrm{eff} \approx 5200-7300$ K, implying that their carbon-oxygen cores are nearly entirely crystallized. Both systems are unusually close to being face-on binaries ($i=13^\circ-28^\circ$), signaling that the production of coherent radio pulses may be a strongly inclination-dependent phenomenon. We present MESA models that show that the M dwarf in each system will fill