Timing, Polarization, and Single-Pulse Properties of Long-Period FAST Pulsars

Abstract

We present phase-connected timing and polarization measurements for two long-period FAST-CRAFTS pulsars, PSRs J0000+6252 and J2131+3642, and extend single-pulse emission-state analysis to a five-source sample including PSRs J1903+1407, J1502+4653, and J2112+4058. FAST L-band timing baselines span 414 to 511 days; the two pulsars have spin periods of 1.11 to 1.55 s, period derivatives of $(3.99$ to $4.06)\times 10^{-15}\mathrm{s}{\mathrm{s}}^{-1}$, characteristic ages of 4.34 to 6.16 Myr, surface magnetic fields of $(2.15$ to $2.52)\times 10^{12}$ G, and spin-down luminosities of $(4.21\times 10^{31}$ to $1.16\times 10^{32})\mathrm{erg}{\mathrm{s}}^{-1}$. Their rotation measures are $70.2\pm 26.7$ and $-44.6\pm 7.6\mathrm{rad}{\mathrm{m}}^{-2}$, with linear polarization fractions of 17.6\% to 27.2\%. PSR J2131+3642 shows a short monotonic PA segment permitting a formal rotating-vector-model fit, though limited longitude coverage leaves the geometric parameters poorly constrained; PSR J0000+6252 has too few PA points for such a fit. Gaussian mixture modeling (GMM) of single-pulse energy distributions identifies null, weak, and burst components in PSRs J0000+6252, J1903+1407, J1502+4653, and J2112+4058, while J2131+3642 shows only weak and burst states. We also identify bright single pulses (peak intensity $\ge 10\times$ the integrated average profile): 42 in J0000+6252, four each in J1903+1407 and J2112+4058, and none in J2131+3642 or J1502+4653. These bright pulses occur within the main emission window with no evidence of periodic recurrence, consistent with sporadic enhancements of the normal radio-emission beam. For J2112+4058, we measure a scattering timescale ${\tau }_{\mathrm{sc}}=5.84\pm 0.18$ ms at ${\nu }_{\mathrm{ref}}=1.25$ GHz. Together, these results highlight the diversity of magnetospheric variability among slowly rotating neutron stars.

26 pages and 15 figures, submitted to Astrophysical Journal (ApJ)