We report on the energy-resolved timing and phase-resolved spectral analysis of X-ray emission from PSR J0659+1414 observed with XMM-Newton and NuSTAR. We find that the new data rule out the previously suggested model of the phase-dependent spectrum as a three-component (2 blackbodies + power-law) continuum, which shows large residuals between 0.3 − 0.7 keV. Fitting neutron star atmosphere models or several blackbodies to the spectrum does not provide a better description of the spectrum, and requires spectral model components with unrealistically large emission region sizes. The fits improve significantly if we add a phase-dependent absorption feature with central energy 0.5 − 0.6 keV and equivalent width up to ≈ 50 eV. We detected the feature for about half of the pulse cycle. Energy-resolved pulse profiles support the description of the spectrum with a three-component continuum and an absorption component. The absorption feature could be interpreted as an electron cyclotron line originating in the pulsar magnetosphere and broadened by the non-uniformity of magnetic field along the line of sight. The significant phase-variability in the thermal emission from the entire stellar surface may indicate multi-polar magnetic fields and a nonuniform temperature distribution. The strongly pulsed non-thermal spectral component detected with NuSTAR in the 3-20 keV range is well fit by a power-law model with a photon index Γ = 1.5 ± 0.2.

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PSR J0108-1431 is an old pulsar where the X-ray emission is expected to have a thermal component from the polar cap and a non-thermal component from the magnetosphere. Although the phase-integrated spectra are fit best with a single non-thermal component modeled with a power-law (PL) of photon index Γ = 2.9, the X-ray pulse profiles do show the presence of phase-separated thermal and non-thermal components. The spectrum extracted from half the rotational phase away from the X-ray peak fits well with either a single blackbody (BB) or a neutron star atmosphere (NA) model, whereas, the spectrum from the rest of the phase range is dominated by a PL. From Bayesian analysis, the estimated BB area is smaller than the expected polar cap area for a dipolar magnetic field with a probability of 86% whereas the area estimate from the NA model is larger with a probability of 80%. Due to the ambiguity in the thermal emission model, the polar cap area cannot be reliably estimated and hence cannot be used to understand the nature of the surface magnetic field. Instead, we can infer the presence of multipolar magnetic field from the misalignment between the pulsar's thermal X-ray peak and the radio emission peak. For J0108-1431, we estimated a phase-offset ∆φ > 0.1 between the thermal polar cap emission peak and the radio emission peak and argue that this is best explained by the presence of a multipolar surface magnetic field.

We report on XMM-Newton EPIC observations of the young pulsar J2022+3842, with a characteristic age of 8.9 kyr. We detected X-ray pulsations and found the pulsation period P ≈ 48.6 ms, and its derivativeṖ ≈ 8.6 × 10 −14 , twice larger than the previously reported values. The pulsar exhibits two very narrow (FWHM ∼ 1.2 ms) X-ray pulses each rotation, separated by ≈ 0.48 of the period, with a pulsed fraction of ≈ 0.8. Using the correct values of P andṖ , we calculate the pulsar's spin-down powerĖ = 3.0 × 10 37 erg s −1 and magnetic field B = 2.1 × 10 12 G. The pulsar spectrum is well modeled with a hard power-law (PL) model (photon index Γ = 0.9 ± 0.1, hydrogen column density n H = (2.3±0.3)×10 22 cm −2 ). We detect a weak off-pulse emission which can be modeled with a softer PL (Γ ≈ 1.7 ± 0.7), poorly constrained because of contamination in the EPIC-pn timing mode data. The pulsar's X-ray efficiency in the 0.5-8 keV energy band, η PSR = L PSR /Ė = 2 × 10 −4 (D/10 kpc) 2 , is similar to those of other pulsars. The XMM-Newton observation did not detect extended emission around the pulsar. Our re-analysis of Chandra X-ray observatory archival data shows a hard, Γ ≈ 0.9 ± 0.5, spectrum and a low efficiency, η PWN ∼ 2 × 10 −5 (D/10 kpc) 2 , for the compact pulsar wind nebula, unresolved in the XMM-Newton images.