Prospect of detecting X-ray haloes around middle-aged pulsars with eROSITA. Issue 2 (21st March 2022)

• Record Type: Journal Article
• Authors: Li, Ben; Zhang, Yi; Liu, Teng; Liu, Ruo-Yu; Wang, Xiang-Yu
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 513:Issue 2(2022)
• Page Start: 2884
• Page End: 2892
• Publication Date: 2022-03-21
• Subjects: pulsars: general -- ISM: magnetic fields -- X-rays: ISM; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stac711
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: The detection of extended TeV γ-ray emission (dubbed 'TeV haloes') around Geminga and Monogem pulsars by High Altitude Water Cherenkov collaboration implies that the halo-like morphologies around middle-aged pulsars may be common. The γ-ray emission above 10 TeV is thought to arise from inverse Compton scattering of relativistic electrons/positrons in the pulsar haloes off cosmic microwave background photons. In the meanwhile, these electrons and positrons can produce X-ray synchrotron emission in the interstellar magnetic field, resulting in a diffuse emission in the X-ray band (namely X-ray haloes). Here, we study the prospect of detecting X-ray haloes with extended Roentgen Survey with an Imaging Telescope Array (eROSITA) from 10 middle-aged pulsars with characteristic age τc larger than tens of thousands of years in the Australia Telescope National Facility pulsar catalogue. Assuming a benchmark value (i.e. B = 3 $\mu$ G) for the magnetic field, most of the X-ray haloes are found to be bright enough to be detected by eROSITA in the energy range of 0.5–2 keV with a 20 ks targeted survey. Among these pulsar haloes, four are detectable in the ongoing 4-yr eROSITA all-sky survey. Thanks to the large grasp in the soft X-ray band, eROSITA is expected to be able to measure the surface brightness profiles of the X-ray haloes from sub-pc up to tens of pc scales, which can be used to constrain the magnetic field and the diffusion coefficient in the pulsar haloes.