Radio-quiet and radio-loud pulsars: similar in Gamma-rays but different in X-rays

TL;DR

This study compares radio-quiet and radio-loud gamma-ray pulsars, revealing they are similar in gamma-ray emissions but differ significantly in X-ray properties, with implications for pulsar emission models.

Contribution

The paper provides new X-ray observations of eight gamma-ray pulsars and analyzes their flux ratios, highlighting differences between radio-quiet and radio-loud pulsars in X-ray behavior.

Findings

Radio-quiet pulsars have higher gamma-ray to X-ray flux ratios.

Distribution of flux ratios peaks differently for radio-quiet and radio-loud pulsars.

Evidence of a pulsar wind nebula around PSR J2030+4415.

Abstract

We present new Chandra and XMM-Newton observations of a sample of eight radio-quiet Gamma-ray pulsars detected by the Fermi Large Area Telescope. For all eight pulsars we identify the X-ray counterpart, based on the X-ray source localization and the best position obtained from Gamma-ray pulsar timing. For PSR J2030+4415 we found evidence for an about 10 arcsec-long pulsar wind nebula. Our new results consolidate the work from Marelli et al. 2011 and confirm that, on average, the Gamma-ray--to--X-ray flux ratios (Fgamma/Fx) of radio-quiet pulsars are higher than for the radio-loud ones. Furthermore, while the Fgamma/Fx distribution features a single peak for the radio-quiet pulsars, the distribution is more dispersed for the radio-loud ones, possibly showing two peaks. We discuss possible implications of these different distributions based on current models for pulsar X-ray emission.