A Possible Link Between the Galactic Center HESS Source and Sgr A*

@misc{citeulike:1144494, abstract = {Recently, HESS and other air Cerenkov telescopes have detected a source of TeV gamma-rays coincident with the Galactic center. It is not yet clear whether the gamma-rays are produced via leptonic or hadronic processes, so it is important to consider possible acceleration sites for the charged particles which produce the gamma-rays. One exciting possibility for the origin of these particles is the central black hole, Sgr A*, where the turbulent magnetic fields close to the event horizon can accelerate protons to TeV energies. Using a realistic model of the density distribution in a 6 pc x 6 pc x 6pc cube at the Galactic center, we here calculate the trajectories followed by these TeV protons as they gyrate through the turbulent medium surrounding Sgr A*. Diffusing out from the black hole, the protons produce TeV gamma-rays via pi^0 decay following a collision with a proton in the surrounding medium. After following over 222,000 such trajectories, we find that the circumnuclear ring around Sgr A* can reproduce the observed 0.1-100 TeV HESS spectrum and flux if the protons are injected into this medium with an effective power-law index of 0.75, significantly harder than the observed photon index of 2.25. The total energy in the steady-state 1-40 TeV proton population surrounding Sgr A* is inferred to be approx 5x10^{45} ergs. Only 31\% of the emitted 1-100 TeV protons encounter the circumnuclear torus, leaving a large flux of protons that diffuse outward to contribute to the Galactic ridge emission observed by HESS on scales of \>\~{} 1 degree.}, author = {Ballantyne, D. R. and Melia, Fulvio and Liu, Siming and Crocker, Roland M. }, citeulike-article-id = {1144494}, comment = {http://arxiv.org/abs/astro-ph/0701709}, eprint = {astro-ph/0701709}, keywords = {blackholes, gamma\_rays}, month = {Feb}, posted-at = {2007-03-06 22:39:25}, priority = {3}, title = {A Possible Link Between the Galactic Center HESS Source and Sgr A*}, url = {http://arxiv.org/abs/astro-ph/0701709}, year = {2007} }

TY - ELEC ID - citeulike:1144494 L3 - citeulike-article-id:1144494 TI - A Possible Link Between the Galactic Center HESS Source and Sgr A* N2 - Recently, HESS and other air Cerenkov telescopes have detected a source of TeV gamma-rays coincident with the Galactic center. It is not yet clear whether the gamma-rays are produced via leptonic or hadronic processes, so it is important to consider possible acceleration sites for the charged particles which produce the gamma-rays. One exciting possibility for the origin of these particles is the central black hole, Sgr A*, where the turbulent magnetic fields close to the event horizon can accelerate protons to TeV energies. Using a realistic model of the density distribution in a 6 pc x 6 pc x 6pc cube at the Galactic center, we here calculate the trajectories followed by these TeV protons as they gyrate through the turbulent medium surrounding Sgr A*. Diffusing out from the black hole, the protons produce TeV gamma-rays via pi^0 decay following a collision with a proton in the surrounding medium. After following over 222,000 such trajectories, we find that the circumnuclear ring around Sgr A* can reproduce the observed 0.1-100 TeV HESS spectrum and flux if the protons are injected into this medium with an effective power-law index of 0.75, significantly harder than the observed photon index of 2.25. The total energy in the steady-state 1-40 TeV proton population surrounding Sgr A* is inferred to be approx 5x10^{45} ergs. Only 31% of the emitted 1-100 TeV protons encounter the circumnuclear torus, leaving a large flux of protons that diffuse outward to contribute to the Galactic ridge emission observed by HESS on scales of >~ 1 degree. KW - blackholes KW - gamma_rays N1 - http://arxiv.org/abs/astro-ph/0701709 AU - Ballantyne, DR AU - Melia, Fulvio AU - Liu, Siming AU - Crocker, Roland PY - 2007/Feb/13/ UR - http://arxiv.org/abs/astro-ph/0701709 ER -