Diagnosing the particle transport mechanism in the pulsar halo via X-ray observations

Fuente: arXiv
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Autores principales: Wu, Qi-Zuo, Li, Chao-Ming, Liang, Xuan-Han, Ge, Chong, Liu, Ruo-Yu
Formato: Preprint
Publicado: 2024
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author Wu, Qi-Zuo
Li, Chao-Ming
Liang, Xuan-Han
Ge, Chong
Liu, Ruo-Yu
author_facet Wu, Qi-Zuo
Li, Chao-Ming
Liang, Xuan-Han
Ge, Chong
Liu, Ruo-Yu
contents Pulsar halos (also termed 'TeV halo') are a new class of $γ$-ray sources in Galaxy, which manifest as extended $γ$-ray emission around middle-age pulsars, as discovered around the Geminga pulsar, the Monogem pulsar and PSR~J0622+3749 by HAWC and LHAASO. A consensus has been reached that the TeV emission comes from the inverse Compton scattering of escaping electrons/positrons from the PWN off soft background radiation field, while the particle transport mechanism in the halo is still in dispute. Currently, there are mainly three interpretations, namely, the isotropic, suppressed diffusion model; the isotropic, unsuppressed diffusion model with considering ballistic propagation of newly injected particles; the anisotropic diffusion model. While the predicted gamma-ray surface brightness profiles by all three models can be more or less consistent with the observation, the implication of the three models for cosmic-ray transport mechanisms and the properties of interstellar magnetic field are quite different. In this study, we calculate the anticipated X-ray emission of pulsar halos under the three models. We show that the synchrotron radiation of these escaping electrons can produce a corresponding X-ray halo around the pulsar, and the expected surface brightness profiles are distinct in three models. We suggest that sensitive X-ray detectors of a large field of view (such as eROSITA and Einstein Probe) with a reasonably long exposure time are crucial to understand the formation mechanism of pulsar halos and serve as a probe to the properties of the interstellar turbulence.
format Preprint
id arxiv_https___arxiv_org_abs_2401_17982
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Diagnosing the particle transport mechanism in the pulsar halo via X-ray observations
Wu, Qi-Zuo
Li, Chao-Ming
Liang, Xuan-Han
Ge, Chong
Liu, Ruo-Yu
High Energy Astrophysical Phenomena
Pulsar halos (also termed 'TeV halo') are a new class of $γ$-ray sources in Galaxy, which manifest as extended $γ$-ray emission around middle-age pulsars, as discovered around the Geminga pulsar, the Monogem pulsar and PSR~J0622+3749 by HAWC and LHAASO. A consensus has been reached that the TeV emission comes from the inverse Compton scattering of escaping electrons/positrons from the PWN off soft background radiation field, while the particle transport mechanism in the halo is still in dispute. Currently, there are mainly three interpretations, namely, the isotropic, suppressed diffusion model; the isotropic, unsuppressed diffusion model with considering ballistic propagation of newly injected particles; the anisotropic diffusion model. While the predicted gamma-ray surface brightness profiles by all three models can be more or less consistent with the observation, the implication of the three models for cosmic-ray transport mechanisms and the properties of interstellar magnetic field are quite different. In this study, we calculate the anticipated X-ray emission of pulsar halos under the three models. We show that the synchrotron radiation of these escaping electrons can produce a corresponding X-ray halo around the pulsar, and the expected surface brightness profiles are distinct in three models. We suggest that sensitive X-ray detectors of a large field of view (such as eROSITA and Einstein Probe) with a reasonably long exposure time are crucial to understand the formation mechanism of pulsar halos and serve as a probe to the properties of the interstellar turbulence.
title Diagnosing the particle transport mechanism in the pulsar halo via X-ray observations
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2401.17982