Constraints on a hadronic model for unidentified off-plane galactic gamma-ray sources

TL;DR

This paper investigates the constraints on hadronic models for off-plane gamma-ray sources like HESS J1507-622, considering the ISM density profile and source energetics, and finds difficulties in linking such sources to stellar remnants.

Contribution

It provides distance-dependent constraints on hadronic gamma-ray emission models for off-plane sources, highlighting challenges in associating them with stellar explosion remnants.

Findings

No simple link to stellar explosion remnants for HESS J1507-622

Density profile limits hadronic gamma-ray production at large distances

Constraints depend on source distance and ISM density

Abstract

Recently the H.E.S.S. collaboration announced the detection of an unidentified gamma-ray source with an off-set from the galactic plane of 3.5 degrees: HESS J1507-622. If the distance of the object is larger than about one kpc it would be physically located outside the galactic disk. The density profile of the ISM perpendicular to the galactic plane, which acts as target material for hadronic gamma-ray production, drops quite fast with increasing distance. This fact places distance dependent constraints on the energetics and properties of off-plane gamma-ray sources like HESS J1507-622 if a hadronic origin of the gamma-ray emission is assumed. For the case of this source it is found that there seems to be no simple way to link this object to the remnant of a stellar explosions.