The Galactic Center region at very-high energies

Data: 
29/08/2018 - 14:00 - 15:00
Local: 
Auditório "Prof. Dr. Paulo Benevides Soares", Bloco G

The Galactic Center region at very-high energies

 

Aion Viana

IFSC/USP

 

Gamma-rays are the most energetic form of light, and the gamma-ray sky is extraordinarily different from the one we perceive with our own eyes. Their study allow scientists to answer persistent questions across a broad range of topics, including supermassive black-hole systems, pulsars, the origin of cosmic rays, and searches for signals of new physics. Hence, they are an essential probe to understand the most extreme phenomena in the Universe. Among all the high-energy environments of our Galaxy, the Galactic Center (GC) region is definitely the richest. It harbours a large amount of non-thermal emitters, including the closest supermassive black hole (SMBH), a cosmic Pevatron, dense molecular clouds, strong star-forming activity, multiple supernova remnants and pulsar wind nebulae, arc-like radio structures, as well as the base of what may be large-scale galactic outflows. This very rich region has been observed by the High Energy Stereoscopic System (H.E.S.S.) I array of ground-based Cherenkov telescopes since 2004 leading to the detection of the very-high-energy (VHE, E > 100 GeV) gamma-ray source HESS J1745−290 spatially coincident with the SMBH Sgr A*. Diffuse TeV gamma-ray emission has been detected along the Galactic ridge, most likely due to cosmic-ray interactions with the dense gas of the Central Molecular Zone. Here I will review the very-high energy observations of the GC region, and present the recent results of a detailed spectral and morphological study, based on the full data set of 2004-2013 observations, which finally reveals the presence of a cosmic PeVatron with a likely link to the central SMBH. I will discuss possible implications of the observed emission, in particular, in the context of the origin of Galactic cosmic rays and large-scale emissions (Fermi bubbles, extraterrestrial neutrinos and others).