学术报告第128期：源于宇宙线作用的河内伽马射线背景（GALACTIC GAMMA RAY BACKGROUND FROM INTERACTIONS OF COSMIC RAYS）

主讲人 (Speaker): 

Sayan Biswas

主讲人单位 (Speaker's Institute): 

Raman Research Institute

邀请人 (Invited by): 

杨莉莉

时间 (Time): 

星期三, 2019/08/28 - 16:00 to 17:00

地点 (Location): 

珠海校区海滨红楼17栋107 (Rm 107, Red House 17)

摘要 (Abstract): 

       Various studies firmly establish the fact that gamma-ray observations can act as a unique probe to detect the possible cosmic ray (CR) sources, study the CR density distribution and explore the average properties of interstellar medium (ISM) such as the gas density profile of ISM. We use the DRAGON code to study different propagation models by incorporating realistic source distribution, Galactic magnetic field (GMF) and gas density profile, and finally obtain the proton distribution (both spatial and energy) in the Galaxy by fitting the locally observed CR spectra. This distribution of protons is used to calculate the diffuse gamma-ray flux produced by proton-proton interactions in the Galactic halo. Our calculated diffuse gamma-ray flux is compared with the isotropic gamma-ray background (IGRB) at sub-TeV energy regime measured by Fermi-LAT. It is found to be much less than IGRB, which suggests IGRB is mostly of extragalactic origin.

主讲人简介 (Speaker's CV): 

Sayan Biswas obtained his Bachelor of Science (B.Sc.) (Physics) and Master of Science (M.Sc.) (Specialization in Astrophysics) at St. Xavier’s College in University of Calcutta. He then moved to Centre for Astroparticle Physics & Space Science. During which time, he finished his Ph.D. Degree in University of Calcutta. Now he works as Post Doctoral Fellow in Astronomy & Astrophysics Group (Raman Research Institute, Bangalore, India). Research Expertise Non-thermal radiation processes and their connections to the spectral energy distributions (photon flux vs. energy) of astrophysical sources. Theoretical modeling, numerical calculations and multi-wavelength studies are being carried on to understand the spectral energy distributions of astrophysical sources. Experience of using DRAGON code to study cosmic ray propagation. Experience of using GAMERA code - a package for gamma-ray astronomy. Experience of analysis of gamma ray data of point sources using Fermi Science Tools, a software package provided by NASA to analyze the gamma ray data collected by Fermi Large Area Telescope. etc.