XMM-Newton Observations of Radio Pulsars B0834+06 and B0826-34 and Implications for Pulsar Inner Accelerator

TL;DR

This study uses X-ray observations of two drifting subpulse pulsars to analyze their thermal emission and test the Partially Screened Gap model of the pulsar inner accelerator.

Contribution

It provides the first X-ray detection of PSR B0834+06 and sets upper limits for PSR B0826-34, offering insights into their magnetic field structures and inner acceleration regions.

Findings

PSR B0834+06 exhibits a thermal blackbody spectrum with a small hot spot.

PSR B0826-34 was not detected, setting an upper limit on its luminosity.

Results support the non-dipolar magnetic field and the PSG model in pulsar inner accelerators.

Abstract

We report the X-ray observations of two radio pulsars with drifting subpulses: B0834 + 06 and B0826 - 34 using \xmm\. PSR B0834 + 06 was detected with a total of 70 counts from the three EPIC instruments over 50 ks exposure time. Its spectrum was best described as that of a blackbody (BB) with temperature $T_s=(2.0^{+2.0}_{-0.9}) \times 10^6$ K and bolometric luminosity of $L_b=(8.6^{+14.2}_{-4.4}) \times 10^{28}$ erg s$^{-1}$. As it is typical in pulsars with BB thermal components in their X-ray spectra, the hot spot surface area is much smaller than that of the canonical polar cap, implying a non-dipolar surface magnetic field much stronger than the dipolar component derived from the pulsar spin-down (in this case about 50 times smaller and stronger, respectively). The second pulsar PSR B0826 - 34 was not detected over 50 ks exposure time, giving an upper limit for the bolometric luminosity $L_b \leq 1.4 \times 10^{29}$ erg s$^{-1}$. We use these data as well as the radio emission data concerned with drifting subpulses to test the Partially Screened Gap (PSG) model of the inner accelerator in pulsars.