Timing and Spectral Studies of PSR J2022+3842 with NICER and NuSTAR

Abstract

We report on the long-term timing analysis of PSR J2022+3842 using observations from the Neutron Star Interior Composition Explorer (NICER), along with spectral properties derived from joint observations with NICER and the Nuclear Spectroscopic Telescope Array (NuSTAR). Two large glitches are identified around MJD 58335 with $Δν=25.35(2)\times10^{-6}$ Hz and MJD 58875 with $Δν=52.078(6)\times10^{-6}$ Hz. Furthermore, phase-resolved spectroscopy reveals that the X-ray emission is well described by a power-law model across different phase intervals. The phase-integrated X-ray spectrum (1-79 keV) has a photon index of $Γ=1.22(7)$, yielding an unabsorbed 0.5-10 keV flux of $8.9(6)\times10^{-13}$ erg cm$^{-2}$ s$^{-1}$. The main pulse spectrum (1.2-79 keV) and the inter-pulse spectrum (1-70 keV) are harder with $Γ=1.17(4)$ and $Γ=1.03^{+0.07}_{-0.06}$ separately, producing an unabsorbed 0.5-10 keV flux of $33.2(2)\times10^{-13}$ erg cm$^{-2}$ s$^{-1}$ and $29(3)\times10^{-13}$ erg cm$^{-2}$ s$^{-1}$. Investigation of the pulse profile evolution with time shows that no significant variations were observed.