HAWC J2227+610: a potential PeVatron candidate for the CTA in the northern hemisphere

TL;DR

This paper evaluates CTA's potential to study the morphology and spectrum of the gamma-ray source HAWC J2227+610, a candidate galactic PeVatron emitting up to 500 TeV, through simulations based on current models and observations.

Contribution

It demonstrates how CTA can improve morphological characterization and spectral analysis of HAWC J2227+610, aiding in understanding its particle acceleration mechanisms.

Findings

CTA can significantly detect source extension.

CTA can better constrain the molecular cloud association.

CTA can reproduce the proton spectrum with a 500 TeV cutoff.

Abstract

Recent observations of the gamma-ray source HAWC J2227+610 by Tibet AS+MD and LHAASO confirm the special interest of this source as a galactic PeVatron candidate in the northern hemisphere. HAWC J2227+610 emits Very High Energy (VHE) gamma-rays up to 500 TeV, from a region coincident with molecular clouds and significantly displaced from the nearby pulsar J2229+6114. Even if this morphology favours an hadronic origin, both leptonic or hadronic models can describe the current VHE gamma-ray emission. The morphology of the source is not well constrained by the present measurements and a better characterisation would greatly help the understanding of the underlying particle acceleration mechanisms. The Cherenkov Telescope Array (CTA) will be the future most sensitive Imaging Atmospheric Cherenkov Telescope and, thanks to its unprecedented angular resolution, could contribute to better constrain the nature of this source. The present work investigates the potentiality of CTA to study the morphology and the spectrum of HAWC J2227+610. For this aim, the source is simulated assuming the hadronic model proposed by the Tibet AS+MD collaboration, recently fitted on multi-wavelength data, and two spatial templates associated to the source nearby molecular clouds. Different CTA layouts and observation times are considered. A 3D map based analysis shows that CTA is able to significantly detect the extension of the source and to attribute higher detection significance to the simulated molecular cloud template compared to the alternative one. CTA data does not allow to disentangle the hadronic and the leptonic emission models. However, it permits to correctly reproduce the simulated parent proton spectrum characterized by a $\sim$ 500 TeV cutoff.