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The evolutionary behavior and multi-wavelength emission properties of bubbles around galaxies, such as the \textit{Fermi} bubbles of the Milky Way, is unsettled. We perform 3D magnetohydrodynamical simulations to investigate the evolution…

High Energy Astrophysical Phenomena · Physics 2022-01-26 Ellis R. Owen , H. -Y. Karen Yang

We investigate non-thermal emission from the Fermi bubbles on a hadronic model. Cosmic-ray (CR) protons are accelerated at the forward shock of the bubbles. They interact with the background gas in the Galactic halo and create $\pi^0$-decay…

High Energy Astrophysical Phenomena · Physics 2015-06-19 Yutaka Fujita , Yutaka Ohira , Ryo Yamazaki

The Fermi Bubbles are enigmatic \gamma-ray features of the Galactic bulge. Both putative activity (within $\sim$ few $\times$ Myr) connected to the Galactic center super-massive black hole and, alternatively, nuclear star formation have…

High Energy Astrophysical Phenomena · Physics 2015-06-18 Roland M. Crocker , Geoffrey V. Bicknell , Ettore Carretti , Alex S. Hill , Ralph S. Sutherland

Motivated by the discovery of the non-thermal Fermi bubble features both below and above the Galactic plane, we investigate a scenario in which these bubbles are formed through Galacto-centric outflow. Cosmic rays (CR) both diffusing and…

High Energy Astrophysical Phenomena · Physics 2017-01-11 Andrew M. Taylor , Gwenael Giacinti

We study a scenario in which the Fermi bubbles are formed through a Galactocentric outflow of gas and pre-accelerated cosmic-rays (CR). We take into account CR energy losses due to proton-proton interactions with the gas present in the…

High Energy Astrophysical Phenomena · Physics 2018-10-29 Gwenael Giacinti , Andrew M. Taylor

The diffuse gamma-ray sky revealed 'Bubbles' of emission above and below the Galactic Plane symmetric around the centre of the Milky Way with a height of 10 kpc in both directions. At present there is no convincing explanation for the…

High Energy Astrophysical Phenomena · Physics 2015-06-22 Wim de Boer , Markus Weber

The Fermi-LAT data revealed giant bubbles of emission above and below the Galactic plane with an energy spectrum significantly harder than seen from other directions. How the bubbles connect to the Galactic plane is unclear. We find that…

High Energy Astrophysical Phenomena · Physics 2015-09-18 Wim de Boer , Iris Gebauer , Simon Kunz , Alexander Neumann

Star forming galaxies emit GeV- and TeV-gamma rays that are thought to originate from hadronic interactions of cosmic-ray (CR) nuclei with the interstellar medium. To understand the emission, we have used the moving mesh code Arepo to…

Astrophysics of Galaxies · Physics 2017-10-04 C. Pfrommer , R. Pakmor , C. M. Simpson , V. Springel

The origin of sub-TeV gamma rays detected by Fermi-LAT from the Fermi bubbles at the Galactic center is still unknown. In a hadronic model, acceleration of protons and/or nuclei and their subsequent interactions with gas in the bubble…

High Energy Astrophysical Phenomena · Physics 2018-04-11 Soebur Razzaque , Lili Yang

Cosmic rays (CRs) interact with the gas, the radiation field and the magnetic field in the Milky Way, producing diffuse emission from radio to gamma rays. Observations of this diffuse emission and comparison with detailed predictions are…

The Magellanic Clouds, two dwarf galaxy companions to the Milky Way, are among the Fermi Large Area Telescope (LAT) brightest gamma-ray sources. Aiming at a comprehensive modeling of the non-thermal electromagnetic and neutrino emission in…

High Energy Astrophysical Phenomena · Physics 2023-03-15 Massimo Persic , Yoel Rephaeli

The $\gamma$-ray emission of star-forming (SF) galaxies is attributed to hadronic interactions of cosmic ray (CR) protons with the interstellar gas and contributions from CR electrons via bremsstrahlung and inverse Compton (IC) scattering.…

High Energy Astrophysical Phenomena · Physics 2021-05-26 Maria Werhahn , Christoph Pfrommer , Philipp Girichidis , Georg Winner

For the first time, we show in MHD simulations with cosmological initial conditions that bi-lobed gamma-ray outflows similar to the Fermi bubbles can form from star formation and supernova feedback, without involvement from active galactic…

High Energy Astrophysical Phenomena · Physics 2025-10-17 Isabel S. Sands , Philip F. Hopkins , Sam B. Ponnada

The origin of Galactic Cosmic Rays (CRs) and the possibility of Supernova Remnants (SNRs) being potential CR accelerators is still an open debate. The charged CRs can be detected indirectly by the {\gamma}-ray observatories through the…

High Energy Astrophysical Phenomena · Physics 2023-04-21 Pooja Sharma , Ziwei Ou , Charles Henry-Cadrot , Coline Dubos , Tiina Suomijärvi

The Fermi Bubbles, which comprise two large and homogeneous regions of spectrally hard gamma-ray emission extending up to $55^{o}$ above and below the Galactic Center, were first noticed in GeV gamma-ray data from the Fermi Telescope in…

High Energy Astrophysical Phenomena · Physics 2019-08-13 H. A. Ayala Solares , C. M. Hui , P. Hüntemeyer

We analyse the origin of the gamma-ray flux from the Fermi Bubbles (FBs) in the framework of the hadronic model in which gamma-rays are produced by collisions of relativistic protons with the protons of background plasma in the Galactic…

Astrophysics of Galaxies · Physics 2015-06-23 K. -S. Cheng , D. O. Chernyshov , V. A. Dogiel , C. -M. Ko

Cosmic rays (CRs) generate diffuse emission while interacting with the Galactic magnetic field (B-field), the interstellar gas and the radiation field. This diffuse emission extends from radio, microwaves, through X-rays, to high-energy…

High Energy Astrophysical Phenomena · Physics 2016-06-22 Elena Orlando

The Fermi Bubbles are giant Galactic structures observed in both gamma-rays and microwaves. Recent studies have found support for the hypothesis that the gamma-ray and microwave emission can both be understood as arising from a hard…

High Energy Astrophysical Phenomena · Physics 2017-05-03 Sruthi A. Narayanan , Tracy R. Slatyer

Current-day cosmic ray (CR) propagation studies use static Milky-Way models and fit parametrized source distributions to data. Instead, we use three-dimensional magneto-hydrodynamical (MHD) simulations of isolated galaxies with the…

High Energy Astrophysical Phenomena · Physics 2021-05-25 Maria Werhahn , Christoph Pfrommer , Philipp Girichidis , Ewald Puchwein , Rüdiger Pakmor

The origin of the Fermi bubbles, which constitute two gamma-ray emitting lobes above and below the Galactic plane, remains unclear. The possibility that this Fermi bubbles gamma-ray emission originates from hadronic cosmic rays advected by…

High Energy Astrophysical Phenomena · Physics 2022-12-07 Olivier Tourmente , Donna Rodgers-Lee , Andrew M. Taylor
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