Observational constraint of electron/positron pair halos in X-ray waveband

Abstract: Very high energy gamma-rays (E > 10 TeV) from Active Galactic Nuclei (AGN) could start electromagnetic cascades because of the absorption of the extragalactic background light (EBL). With sufficiently strong extragalactic magnetic field strengths (1 nG < B < 1 μG), the cascades could develop isotropically and produce electron/positron pairs around the AGN, which is called an electron/positron pair halo. Although, the haloes are originally predicted that they might be observed in gamma-ray waveband, however there has been no evidence of the detection in this waveband yet. Theoretically, they should be observable in X-ray waveband due to the Synchrotron radiation of the electron/positron pairs as well; in fact, this might provide a new window for detecting the haloes. In this work, we aim to test whether the X-ray emission from the haloes would be detectable by the current generation and next-generation X-ray telescopes. We simulated the intrinsic X-ray emissions of the haloes under different conditions of gamma-ray energy and magnetic field. Accounting for the contamination from the central AGN and X-ray background photons, we then analyzed the detectability of the halo emission created from these conditions. In the presentation, we will show whether the haloes would be observable by X-ray observatories; the possible ranges of the parameters which might allow the haloes to be detectable will be discussed. Moreover, we will also present how much the halo emission signal to noise would be gained by Athena, comparing to that of XMM-Newton.This poster is supported by grants from Graduate School, Srinakharinwirot University