GeV Emission in the Region of the Supernova Remnant G51.26+0.11

Abstract

The supernova remnant (SNR) G51.26+0.11 was recently discovered and little is known about its properties and environment. Using data from the Fermi Large Area Telescope we study the GeV emission seen in the direction of G51.26+0.11 to constrain the origin of the gamma rays and their possible relation to this SNR or to a star-forming region. We also search for emission from molecular gas in the region that could provide dense material for the production of gamma rays. By modeling the multi-wavelength spectrum of G51.26+0.11 from radio to gamma rays we derive the properties of the particle populations that could produce the emission in several possible scenarios. We rule out the star-forming regions (such as G051.010+00.060) seen nearby as the origin of the GeV emission.The correspondence seen between the gamma-ray and radio morphologies support a scenario where G51.26+0.11 is the cause of the gamma rays. The flat spectral energy distribution observed at GeV energies is best fit by hadronic or inverse Compton emission, while a bremsstrahlung model cannot properly account for the radio fluxes under a simple one-zone scenario. A pulsar wind nebula origin of the high-energy photons cannot be ruled out or confirmed.

A Study of GeV Gamma-ray Emission toward Supernova Remnant G51.26+0.11 and Its Molecular Environment

“…In the hadronic scenario, by adopting a distance of 6.2 kpc to the SNR, the proton index 𝛼 p ≈ 2.25 and the lower limit of the proton cutoff energy 𝐸 p,cut ≈ 5 TeV are obtained with the GeV data alone (see the left panel of Figure 8). The proton index (𝛼 p ) we obtain is slightly larger than that (2.11 +0.08 −0.12 ) reported by Araya (2021) and hence more consistent with the known gamma-ray-bright interacting SNRs (Acero et al 2016), and a PWN contribution is not necessary to explain the hard spectrum given 1Disk+1PS as the best template. The cutoff energy can not be well constrained and is fixed as 1 PeV in the calculation.…”

“…• , respectively, which are consistent with those reported by Araya (2021). For comparison, we replace the spatial parameters of the 1Gauss model with Araya's results in the following analysis.…”

“…Using the best-fitting PL spectral parameters for 'Src A', the obtained flux in 0.2-500 GeV is 2.86 × 10 −11 erg cm −2 s −1 (with Γ = 2.19 ± 0.04), giving a luminosity of 7.3 × 10 34 erg s −1 in 1-100 GeV at a distance of 6.2 kpc (see §4.2 below for the distance estimate). Since we include 4FGL J1924.3+1628 in the background model, the flux of 'Src A' is a bit lower than that reported in Araya (2021). The flux of 4FGL J1924.3+1628 in 0.2-500 GeV, also assumed with a PL spectrum, is 5.14 × 10 −12 erg cm −2 s −1 (with Γ = 1.70 ± 0.17).…”

“…Considering the association with the molecular clouds seen at +43.4 -+52.2 and +53 -+58.8 km s −1 , SNR G51.26+0.11 was placed at a distance between 3.7 and 6.6 kpc (Araya 2021). The distance was also estimated to be 6.6 ± 1.7 kpc from the H I absorption spectra that were constructed with the THOR data (Ranasinghe & Leahy 2022).…”

“…𝑎 The fitted positions with 1𝜎 statistical uncertainty.𝑏 The respective 68%-containment radii.𝑐 𝑘 and AIC values are provided as differences with respect to the 1Gauss model.𝑑 The values of position and extension are fromAraya (2021) 𝑒 Lande et al 2012). to select the best-fitting spatial model.…”