ﻻ يوجد ملخص باللغة العربية
We report a study of extended $gamma$-ray emission with the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope, which is likely to be the second case of a $gamma$-ray detection from a star-forming region (SFR) in our Galaxy. The LAT source is located in the G25 region, $1.7^{circ} times 2.1^{circ}$ around $(l, b) = (25.0^{circ}, 0.0^{circ})$. The $gamma$-ray emission is found to be composed of two extended sources and one point-like source. The extended sources have a similar sizes of about $1.4^{circ} times 0.6^{circ}$. An $sim 0.4^{circ}$ diameter sub-region of one has a photon index of $Gamma = 1.53 pm 0.15$; and is spatially coincident with HESS J1837$-$069, likely a pulsar wind nebula. The other parts of the extended sources have a photon index of $Gamma = 2.1 pm 0.2$ without significant spectral curvature. Given their spatial and spectral properties, they have no clear associations with sources at other wavelengths. Their $gamma$-ray properties are similar to those of the Cygnus cocoon SFR, the only firmly established $gamma$-ray detection of an SFR in the Galaxy. Indeed, we find bubble-like structures of atomic and molecular gas in G25, which may be created by a putative OB association/cluster. The $gamma$-ray emitting regions appear confined in the bubble-like structure; similar properties are also found in the Cygnus cocoon. In addition, using observations with the the XMM-Newton we find a candidate young massive OB association/cluster G25.18+0.26 in the G25 region. We propose that the extended $gamma$-ray emission in G25 is associated with an SFR driven by G25.18+0.26. Based on this scenario, we discuss possible acceleration processes in the SFR and compare them with the Cygnus cocoon.
We report the detection of high-energy gamma-ray signal towards the young star-forming region, W40. Using 10-year Pass 8 data from the Fermi Large Area Telescope (Fermi-LAT), we extracted an extended gamma-ray excess region with a significance of abo
Context. After the release of the gamma-ray source catalog produced by the Fermi satellite during its first two years of operation, a significant fraction of sources still remain unassociated at lower energies. In addition to well-known high-energy e
Westerlund 1 (Wd 1) is the most massive stellar cluster in the Galaxy and associated with an extended region of TeV emission. Here we report the results of a search for GeV gamma-ray emission in this region. The analysis is based on ~4.5 years of Fer
We present the results of extensive observations by the gamma-ray AGILE satellite of the Galactic region hosting the Carina nebula and the remarkable colliding wind binary Eta Carinae (Eta Car) during the period 2007 July to 2009 January. We detect a
The Cygnus arm of our galaxy is a source-rich and complex region hosting multiple gamma-ray source types such as pulsar wind nebulae (PWN), supernova remnants, binary systems, and star clusters. The High Altitude Water Cherenkov (HAWC) observatory ha