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One of the most exciting discoveries of recent years is a pair of gigantic gamma-ray emission regions, the so-called Fermi bubbles, above and below the Galactic center. The bubbles, discovered by the Fermi space telescope, extend up to…

High Energy Astrophysical Phenomena · Physics 2015-06-23 Satyendra Thoudam

Fermi bubbles are giant gamma-ray structures extended north and south of the Galactic center with characteristic sizes of order of 10 kpc recently discovered by Fermi Large Area Telescope. Good correlation between radio and gamma-ray…

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

The {\it Fermi} Large Area Telescope has recently discovered two giant gamma-ray bubbles which extend north and south of the Galactic center with diameters and heights of the order of $H\sim 10$ kpc. We suggest that the periodic star…

High Energy Astrophysical Phenomena · Physics 2015-06-03 K. S. Cheng , D. O. Chernyshov , V. A. Dogiel , C. M. Ko , W. H. Ip , Y. Wang

We analyse the model of stochastic re-acceleration of electrons, which are emitted by supernova remnants (SNRs) in the Galactic Disk and propagate then into the Galactic halo, in order to explain the origin on nonthermal (radio and…

High Energy Astrophysical Phenomena · Physics 2015-05-27 K. S. Cheng , D. O. Chernyshov , V. A. Dogiel , C. M. Ko

The Galactic Center's giant outflows are manifest in three different, non-thermal phenomena: i) the hard-spectrum, \gamma-ray `Fermi Bubbles' emanating from the nucleus and extending to |b| ~ 50 degrees; ii) the hard-spectrum,…

High Energy Astrophysical Phenomena · Physics 2015-07-30 Roland M. Crocker , Geoffrey V. Bicknell , Andrew M. Taylor , Ettore Carretti

Fermi has discovered two giant gamma-ray-emitting bubbles that extend nearly 10 kpc in diameter. We propose that periodic star capture processes by the galactic supermassive black hole, Sgr A*, with a capture rate $<10^{-5}$ yr$^{-1}$ and…

High Energy Astrophysical Phenomena · Physics 2011-09-29 V. A. Dogiel , D. O. Chernyshov , K. -S. Cheng , Y. Wang , C. -M. Ko , W. -H. Ip

The Fermi bubbles are two giant bubbles in gamma rays lying above and below the Galactic center (GC). Despite numerous studies on the bubbles, their origin and emission mechanism remain elusive. Here we use a suite of hydrodynamic…

High Energy Astrophysical Phenomena · Physics 2020-05-20 Ruiyu Zhang , Fulai Guo

The microwave "haze" was first discovered with the initial release of the full sky data from the Wilkinson Microwave Anisotropy Probe. It is diffuse emission towards the center of our Galaxy with spectral behavior that makes it difficult to…

Astrophysics of Galaxies · Physics 2015-05-30 Gregory Dobler

Two enigmatic gamma-ray features in the Galactic central region, known as Fermi Bubbles (FBs), were found from Fermi-LAT data. An energy release (e.g., by tidal disruption events in the Galactic center, GC), generates a cavity with a shock…

High Energy Astrophysical Phenomena · Physics 2024-11-25 Vladimir A. Dogiel , Chung-Ming Ko

Fermi bubbles, the recently observed giant (~10 kpc high) gamma-ray emitting lobes on either side of our Galaxy (Su et al. 2010), appear morphologically connected to the Galactic center, and thus offer a chance to test several models of…

Astrophysics of Galaxies · Physics 2012-01-18 Kastytis Zubovas , Sergei Nayakshin , Andrew King

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

We study the variation of the spectrum of the Fermi Bubbles with Galactic latitude. Far from the Galactic plane (|b| > 30 degrees), the observed gamma-ray emission is nearly invariant with latitude, and is consistent with arising from…

High Energy Astrophysical Phenomena · Physics 2013-02-28 Dan Hooper , Tracy R. Slatyer

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

A pair of giant gamma-ray bubbles have been revealed by the {\it Fermi} LAT. In this paper we investigate their formation mechanism. Observations have indicated that the activity of the supermassive black hole located at the Galactic…

High Energy Astrophysical Phenomena · Physics 2015-06-19 Guobin Mou , Feng Yuan , Defu Bu , Mouyuan Sun , Meng Su

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

Relativistic sources, e.g. gamma-ray bursts, pulsar wind nebulae and powerful active galactic nuclei produce relativistic outflows that lead to the formation of collisionless shock waves, where particle acceleration is thought to take…

High Energy Astrophysical Phenomena · Physics 2015-06-03 Martin Lemoine , Guy Pelletier

We analyse processes of particle acceleration in the Fermi Bubbles. The goal of our investigations is to obtain restrictions for acceleration mechanisms. Our analysis of the three processes: acceleration from background plasma,…

High Energy Astrophysical Phenomena · Physics 2015-06-18 V. A. Dogiel , K. -S. Cheng , D. O. Chernyshov , C. -M. Ko

The enhanced star formation in the inner 100 pc of the Galaxy launches a superwind at ~1600 km s$^{-1}$ for M82-like parameters. The ram pressure of the wind is very low compared to more powerful starburst winds. I show that halo gas stops…

High Energy Astrophysical Phenomena · Physics 2014-08-13 Brian C. Lacki

The Fermi Gamma-ray Space Telescope reveals two large bubbles in the Galaxy, which extend nearly symmetrically ~50 degrees above and below the Galactic center (GC). Using three-dimensional (3D) magnetohydrodynamic (MHD) simulations that…

Astrophysics of Galaxies · Physics 2015-06-05 H. -Y. K. Yang , M. Ruszkowski , P. M. Ricker , E. Zweibel , D. Lee

The Fermi bubbles are large gamma-ray-emitting structures. They are symmetric about the Galactic Centre (GC), and their creation is therefore attributed to intensive energy injection at the GC. In this study, we focus on the non-equilibrium…

High Energy Astrophysical Phenomena · Physics 2022-12-16 Yutaka Fujita