Detection of the Extended Gamma-Ray Emission around PSR J1627-4706 with Fermi-LAT

Abstract Based on nearly 16 yr of Fermi Large Area Telescope observations we have detected an extended GeV gamma-ray source with a significance of ∼7.6 σ , spatially coincident with the old pulsar PSR J1627-4706. The gamma-ray morphology is well characterized by a two-dimensional Gaussian spatial template, exhibiting a 68% containment radius of ∼0 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover> <mml:mrow> <mml:mo>.</mml:mo> </mml:mrow> <mml:mrow> <mml:mtext>°</mml:mtext> </mml:mrow> </mml:mover> </mml:math> 35. The observed gamma-ray emission exhibits a single power-law spectral distribution with an index of 1.97 ± 0.06 in the energy range of 500 MeV–1 TeV. We have investigated several potential origins for this emission, including a supernova remnant (SNR), pulsar wind nebula (PWN), and pulsar halo scenario. The relatively low spin-down luminosity and high characteristic age of PSR J1627-4706 make both the PWN and pulsar halo interpretations unlikely. While a putative SNR could potentially account for the gamma-ray spectrum through either leptonic or hadronic processes, the lack of corresponding shell-type structure in other wavelengths presents a significant challenge to this explanation.