# New composite supernova remnant toward HESS J1844-030?

## TL;DR

This study investigates the possible association between a supernova remnant, a pulsar wind nebula, and a TeV gamma-ray source, suggesting they form a composite SNR with the TeV emission likely originating from the PWN.

## Contribution

The paper provides the first detailed analysis linking G29.4+0.1, its associated SNR, and HESS J1844-030, proposing HESS J1844-030 as the TeV counterpart of the PWN G29.4+0.1 within a composite SNR.

## Key findings

- G29.4+0.1 is confirmed as a PWN with an embedded pulsar.
- The SNR associated with G29.37+0.1 is at 6.5 kpc and expanding in a nonuniform medium.
- HESS J1844-030 is likely the TeV counterpart of the PWN G29.4+0.1.

## Abstract

AIMS: HESS J1844-030 is a newly confirmed TeV source in the direction of the X-ray pulsar wind nebula (PWN) candidate G29.4+0.1 and the complex radio source G29.37+0.1, which is likely formed by the superposition of a background radio galaxy and a Galactic supernova remnant (SNR). We investigate the possible connection between the SNR, the PWN G29.4+0.1, and HESS J1844-030 to shed light on the astrophysical origin of the TeV emission. METHODS: We performed an imaging and spectral study of the X-ray emission from the PWN G29.4+0.1 using archival observations obtained with the Chandra and XMM-Newton telescopes. Public radio continuum and HI data were used to derive distance constraints for the SNR that is linked to G29.37+0.1 and to investigate the interstellar medium where it is expanding. We applied a simple model of the evolution of a PWN inside an SNR to analyze the association between G29.4+0.1 and the radio emission from G29.37+0.1. We compared the spectral properties of the system with the population of TeV PWNe to investigate if HESS J1844-030 is the very high energy counterpart of the X-ray PWN G29.4+0.1. RESULTS: We conclude that G29.4+0.1 is a PWN and that a point source embedded on it is the powering pulsar. The HI data revealed that the SNR linked to G29.37+0.1 is a Galactic source at 6.5 kpc and expanding in a nonuniform medium. From the analysis of the pulsar motion and the pressure balance at the boundary of X-ray emission, we conclude that G29.4+0.1 could be a PWN that is located inside its host remnant, forming a new composite SNR. Based on the magnetic field of the PWN obtained from the X-ray luminosity, we found that the population of electrons producing synchrotron radiation in the keV band can also produce IC photons in the TeV band. This suggests that HESS J1844-030 could be the very high energy counterpart of G29.4+0.1.