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Unveiling how black hole jets are born and sustained

Grant number: 22/10460-8
Support Opportunities:Scholarships abroad - Research
Effective date (Start): December 09, 2022
Effective date (End): June 08, 2023
Field of knowledge:Physical Sciences and Mathematics - Astronomy - Extragalactic Astrophysics
Principal Investigator:Rodrigo Nemmen da Silva
Grantee:Rodrigo Nemmen da Silva
Host Investigator: Roger Blandford
Host Institution: Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG). Universidade de São Paulo (USP). São Paulo , SP, Brazil
Research place: Stanford University, United States  


Accreting black holes (BHs) produce relativistic jets which are behind a wide variety of astronomical phenomena and provide fascinating sources of electromagnetic radiation from radio to gamma-rays, cosmic rays and neutrinos. Despite the importance of jets for multimessenger astronomy, our understanding of how they are born from a black hole magnetosphere and subsequently sustained is still uncertain. This is one of the fundamental problems in black hole physics and high-energy astrophysics. Jets are thought to be powered mainly by the spin energy of Kerr BHs and require a minimal amount of plasma in the magnetosphere to activate, otherwise the spin energy cannot be extracted. The most likely source of this plasma are electron-positron pairs. Here, we will build the jet activation function by calculating the number density of pairs due to photon-photon and pair cascade processes near event horizons of supermassive and stellar-mass BHs, incorporating the effects of the surrounding accretion flow. Our goal with these calculations is to answer the question: are there critical values of the BH mass and mass accretion rate for which the jet turns on or off? With this work, we will shed light on the nature of relativistic jets from BH systems across the mass scale and the radio-loud/radio-quiet dichotomy observed in active galaxies. (AU)

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