Multiwavelength investigation of the candidate Galactic PeVatron MGRO J1908+06

Abstract

The candidate PeVatron MGRO J1908+06, which shows a hard spectrum beyond 100 TeV, is one of the most peculiar $\gamma$-ray sources in the Galactic plane. Its complex morphology and some possible counterparts spatially related with the VHE emission region, preclude to distinguish between a hadronic or leptonic nature of the $\gamma$-ray emission. In this paper we illustrate a new multiwavelength analysis of MGRO J1908+06, with the aim to shed light on its nature and the origin of its ultra high-energy emission. We performed an analysis of the ${}^{12}$CO and ${}^{13}$CO molecular line emission demonstrating the presence of dense molecular clouds spatially correlated with the source region. We also analyzed 12-years of Fermi-LAT data between 10 GeV and 1 TeV finding a counterpart with a hard spectrum ($\Gamma \sim 1.6$). Our reanalysis of XMM-Newton data allowed us to put a more stringent constraint on the X-ray flux from this source. We demonstrate that a single accelerator cannot explain the whole set of multiwavelength data, regardless of whether it accelerates protons or electrons, but a 2-zone model is needed to explain the emission from MGRO J1908+06. The VHE emission seems most likely the superposition of a TeV PWN powered by PSR J1907+0602, in the southern part, and of the interaction between the supernova remnant G40.5-0.5 and the molecular clouds towards the northern region.

arXiv comment7 pages, 7 figures

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• ASTRI Mini-Array Core Science at the Observatorio del Teide
• A pulsar wind nebula origin of the LHAASO-detected UHE gamma-ray sources
• The LHAASO PeVatron bright sky: what we learned
• Exploring the hadronic origin of LHAASO J1908+0621
• LHAASO J2226+6057 as a pulsar wind nebula
• Study of maximum electron energy of sub-PeV pulsar wind nebulae by multiwavelength modelling
• Multiwavelength Investigation of $\gamma$-ray Source MGRO J1908+06 Emission Using Fermi-LAT, VERITAS, and HAWC
• Radio study of HESS J1857+026. Gamma-rays from a superbubble?
• Dark photon constraints using the UHE gamma-ray emission from galactic sources. A Phenomenological Study
• HAWC Study of the Ultra-High-Energy Spectrum of MGRO J1908+06