Speaker
Description
G032.8-00.1 (or Kes 78) and G032.4+00.1 are two adjacent (in projection) supernova remnants (SNRs), apart by 0.4 deg. Both remnants have been investigated in the radio and X-ray bands. Both were previously considered to be related with the 2FGL J1850.7-0014c gamma-ray source. However, such an association was abandoned in the latest Fermi-LAT catalogs. The current view supports the detection of a GeV gamma-ray excess from this location, but its origin is uncertain.
In this work, we employ 16.2 yr of Fermi-LAT data to investigate the gamma-ray emission from this region. As such, we provide the first comprehensive morphological and spectral analysis of the gamma-ray emission from the location of the two remnants from which we infer that they are the best candidates among the sources known to date for explaining the detected excess, which exhibits two distinct maxima. We detect gamma-ray emission from both SNRs >1 GeV at a 9 sigma significance level. The spectral shapes obtained, best described by a LogParabola, together with the apparent interaction of the remnants with nearby molecular gas, supports a hadronically induced gamma-ray emission scenario for both remnants. This finding is further corroborated by the results of the multiwavelength spectral energy distribution (SED) modeling conducted in this study. This discovery adds G032.4+00.1, which is also one of the most distant Galactic SNRs ever detected, to the closed group of Galactic SNRs; only a handful of such objects have been detected, which are established gamma-ray emitters with a non-thermal spectral component in the X-ray band.
In addition, this work reports the first statistically significant detection at the 4.5 sigma level in the GeV energy band with Fermi-LAT for the nearby PeV candidate pulsar wind nebula PWN G32.64+0.53 associated with pulsar PSR J1849-0001.
| Collaboration(s) | Fermi-LAT collaboration |
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