Cosmic Ray Feedback in the Universe: Fermi Bubbles and Odd Radio Circles

Hsiang-Yi Karen Yang^1*, Mateusz Ruszkowski³, Ellen Zweibel⁴, Po-Hsun Tseng², Hsi-Yu Schive², Tzihong Chiueh², Yen-Hsing Lin¹

¹Institute of Astronomy, National Tsing Hua University, Hsinchu, Taiwan
²Department of Physics, National Taiwan University, Taipei, Taiwan
³Department of Astronomy, University of Michigan, Ann Arbor, USA
⁴Department of Astronomy, University of Wisconsin-Madison, Madison, USA

* Presenter:Hsiang-Yi Karen Yang, email:hyang@phys.nthu.edu.tw

Relativistic jets emanating from active galactic nuclei (AGNs) play a pivotal role as a feedback mechanism in the Universe, and the cosmic rays (CRs) carried by AGN jets can have profound influence on galaxy properties and the circumgalactic medium. Consequently, self-consistent modeling of CR propagation, spectral evolution, and emission mechanisms is imperative for understanding the thermal and non-thermal emissions of galaxies. We employ advanced 3D CR-magnetohydrodynamic simulations to elucidate that the multi-wavelength observations of the Fermi and eRosita bubbles within the Milky Way can be accounted for by past activity of Sgr A*. We investigate the feasibility of generating symmetric bubbles through the interaction of oblique AGN jets with the dense Galactic disk. Furthermore, we examine the potential for detecting Fermi bubble analogs in nearby galaxies, considering both hadronic and leptonic scenarios. We posit that, when viewed head-on, AGN jet-inflated bubbles may provide a plausible explanation for the recently identified enigmatic odd radio circles (ORCs). These works advance our understanding of CR jet feedback and their influence on various astrophysical phenomena within our cosmic neighborhood.

Keywords: active galactic nuclei, cosmic rays, numerical simulations