X-ray properties of the mode-switching pulsar PSR B0943+10

S Mereghetti,P Esposito,M Serylak,W Hermsen,J-M Griessmeier,L Kuiper,A Possenti,M Rigoselli,J Hessels,A Horneffer,D Mitra,R Turolla,A Tiengo,G Wright,S Oslowski,J Rankin,B Stappers,K Stovall

doi:10.1088/1742-6596/932/1/012009

Abstract

The mode-switching pulsar PSR B0943+10 has been extensively studied in the radio band for many years and, more recently, it has been found to vary also in X-rays, with a flux anticorrelated with the radio emission. Here we review the results of long observations of PSR B0943+10 carried out with XMM-Newton and the LOFAR, LWA and Arecibo radio telescopes in 2014. These results support a scenario in which both unpulsed non-thermal emission, likely of magnetospheric origin, and pulsed thermal emission from a small polar cap (∼1500 m2) with a strong non-dipolar magnetic field (∼ 1014 G), are present during both radio modes and vary in intensity in a correlated way.

Highlights

PSR B0943+10 can be considered the prototypical mode-switching radio pulsar
The faint X-ray emission of PSR B0943+10 was first detected in 2003 [6], and studied in much more detail thanks to a set of XMM-Newton observations carried out in 2011. These observations, providing a useful exposure of about 100 ks, were complemented by simultaneous radio monitoring with Low-Frequency Array (LOFAR) and the GMRT. This made it possible to analyse separately the X-ray data corresponding to the two radio modes, leading to the discovery of X-ray flux variations anticorrelated with the radio modes [7]
By comparing the folded light curves obtained before and after TQB+ 3 hr, we found some evidence ï that the pulsed fraction increases along the B-mode. This possible variation, only at the ∼< 2σ level, is potentially interesting and might be related to the fact that several properties of the PSR B0943+10 radio emission show an evolution along the B-mode [2, 12, 13, 3]

Summary

Introduction

PSR B0943+10 can be considered the prototypical mode-switching radio pulsar. It was soon discovered that its radio emission alternates between two different states: when the pulsar is in B (bursting or bright) mode, its radio emission displays a regular pattern of drifting subpulses, while it is chaotic, and on average fainter, when the pulsar is in the Q (quiescent) mode [1, 2].Its spin period P =1.1 s and period derivative P =3.5×10−15 s s−1 imply a characteristic age τ =5 Myr, a dipolar surface magnetic field B=4×1012 G, and a spin-down power Erot=1032 erg s−1. The faint (a few 10−15 erg cm−2 s−1) X-ray emission of PSR B0943+10 was first detected in 2003 [6], and studied in much more detail thanks to a set of XMM-Newton observations carried out in 2011. These observations, providing a useful exposure of about 100 ks, were complemented by simultaneous radio monitoring with LOFAR and the GMRT. This made it possible to analyse separately the X-ray data corresponding to the two radio modes, leading to the discovery of X-ray flux variations anticorrelated with the radio modes [7]. It was found that in the Q-mode, when the radio emission is fainter, the X-ray flux is larger by more than a factor two than in the B-mode

Results

Discussion

Conclusion