HESS J1640-465: A Gamma-Ray Emitting Pulsar Wind Nebula?

Abstract

HESS J1640-465 is an extended TeV γ-ray source and its γ-ray emission whether from the shell of a supernova remnant (SNR) or a pulsar wind nebula (PWN) is still under debate. We reanalyze the GeV γ-ray data in the field of HESS J1640-465 using eight years of Pass 8 data recorded by the Fermi Large Area Telescope. An extended GeV γ-ray source positionally coincident with HESS J1640-465 is found. Its photon spectrum can be described by a power-law with an index of 1.42 ± 0.19 in the energy range of 10-500 GeV, and smoothly connects with the TeV spectrum of HESS J1640-465. The broadband spectrum of HESS J1640-465 can be well fit by a leptonic model with a broken power-law spectrum of electrons with an exponential cut-off at ∼ 300 TeV. The spectral properties of HESS J1640-465 are broadly consistent with the characteristics of other sources identified as PWNe, such as the correlations between high-energy luminosity ratios and the physical parameters of pulsar, including spin-down luminosityĖ and characteristic age τ c . All these pieces of evidence support that the γ-ray emission of HESS J1640-465 may originate from the PWN powered by PSR J1640-4631 rather than the shell of the SNR G338.3-0.0.

VER J2227+608: A Hadronic PeVatron Pulsar Wind Nebula?

“…However, we still lack direct observational evidence for CRs in SNRs up to the spectral knee. Pulsar wind nebulae (PWNe) driven by the central pulsars are also important particle accelerators and a large amount of PWNe have been detected in the γ-ray band (Abramowski et al 2012;Xin et al 2018). High-energy particles can be accelerated at the termination shocks of PWNe.…”

The gamma-ray emission in the region of W49A with Fermi-LAT

“…The resulting spectral energy distribution (SED) is shown in the right panel of Figure 1, and there is an obvious spectral upturn at an energy of about 20 GeV. Following the analysis procedure in Xin et al [14], the energy range was divided into two parts: 1 GeV -20 GeV and 20 GeV -1 TeV. For each energy range, we refit the position of 4FGL J1910.2+0904c with fermipy, a PYTHON package that automates analyses with the Fermi Science Tools [15].…”

Fermi-LAT Detection of GeV Gamma-Ray Emission from The Highly Asymmetric Shell Supernova Remnant: SNR G317.3-0.2

“…Moreover, the systematic uncertainties from the effective area were calculated using the bracketing Aeff method 10 . The systematic uncertainties of the galactic diffuse emission were estimated by artificially fixing the best-fit value of normalization of the galactic diffuse model from each energy bin to a ±6% deviation (e.g., Abdo et al 2009Abdo et al , 2010aXing et al 2015;Xin et al 2018). The best-fit data are presented in Table 2.…”