XMM-Newton Observation of the nearby Pulsar B1133+16.

Abstract

We constrain the X-ray properties of the nearby (360 {pc}), old (5 {Myr}) pulsar B1133+16 with ∼ 100 {ks} effective exposure time by XMM-Newton. The observed pulsar flux in the 0.2-3 keV energy range is ∼ {10}^-14 {erg} {cm}}^-2 {{{s}}}^-1, which results in the recording of ∼600 source counts with the EPIC pn and MOS detectors. The X-ray radiation is dominated by nonthermal radiation and is well described by both a single power-law model (PL) and a sum of blackbody and power-law emission (BB+PL). The BB+PL model results in a spectral photon index {{Γ }}={2.4}_-0.3^+0.4 and a nonthermal flux in the 0.2-3 keV energy range of (7+/- 2)× {10}^-15 {erg} {cm}}^-2 {{{s}}}^-1. The thermal emission is consistent with the blackbody emission from a small hot spot with a radius of {R}_pc}≈ {14}_-5⁺⁷ {{m}} and a temperature of {T}_{{s}}={2.9}_-0.4^+0.6 {MK}. Assuming that the hot spot corresponds to the polar cap of the pulsar, we can use the magnetic flux conservation law to estimate the magnetic field at the surface {B}_{{s}}≈ 3.9× {10}¹⁴ {{G}}. The observations are in good agreement with the predictions of the partially screened gap model, which assumes the existence of small-scale surface magnetic field structures in the polar cap region.