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Title: Fermi bubbles from stochastic acceleration of electrons in a Galactic outflow

Abstract

The discovery of the Fermi bubbles – a huge bilobular structure seen in GeV gamma-rays above and below the Galactic centre – implies the presence of a large reservoir of high energy particles at ~10 kpc from the disk. The absence of evidence for a strong shock coinciding with the edge of the bubbles, and constraints from multi-wavelength observations point towards stochastic acceleration by turbulence as a likely mechanism of acceleration. We have studied the time-dependent acceleration of electrons in a large-scale outflow from the Galactic centre. For the first time, we propose a detailed numerical solution of the particle kinetic equation that includes the acceleration, transport and relevant energy loss processes. We also take into account the addition of shock acceleration of electrons at the bubble’s blast wave. Fitting to the observed spectrum and surface brightness distribution of the bubbles allows determining the transport coefficients, thereby shedding light on the origin of the Fermi bubbles.

Authors:
 [1];  [2]
  1. RWTH Aachen Univ., Aachen (Germany); The Niels Bohr Inst., Copenhagen (Denmark); Kavli Inst. for Particle Astrophysics & Cosmology, Menlo Park, CA (United States)
  2. Kavli Inst. for Particle Astrophysics & Cosmology, Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States)
Publication Date:
Research Org.:
SLAC National Accelerator Lab. (SLAC), Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1506231
Grant/Contract Number:  
AC02-76SF00515
Resource Type:
Accepted Manuscript
Journal Name:
Astronomy and Astrophysics
Additional Journal Information:
Journal Volume: 622; Journal ID: ISSN 0004-6361
Publisher:
EDP Sciences
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; acceleration of particles; shock waves; turbulence; cosmic rays; ISM jets and outflows; ISM gamma rays

Citation Formats

Mertsch, P., and Petrosian, V.. Fermi bubbles from stochastic acceleration of electrons in a Galactic outflow. United States: N. p., 2019. Web. doi:10.1051/0004-6361/201833999.
Mertsch, P., & Petrosian, V.. Fermi bubbles from stochastic acceleration of electrons in a Galactic outflow. United States. doi:10.1051/0004-6361/201833999.
Mertsch, P., and Petrosian, V.. Thu . "Fermi bubbles from stochastic acceleration of electrons in a Galactic outflow". United States. doi:10.1051/0004-6361/201833999.
@article{osti_1506231,
title = {Fermi bubbles from stochastic acceleration of electrons in a Galactic outflow},
author = {Mertsch, P. and Petrosian, V.},
abstractNote = {The discovery of the Fermi bubbles – a huge bilobular structure seen in GeV gamma-rays above and below the Galactic centre – implies the presence of a large reservoir of high energy particles at ~10 kpc from the disk. The absence of evidence for a strong shock coinciding with the edge of the bubbles, and constraints from multi-wavelength observations point towards stochastic acceleration by turbulence as a likely mechanism of acceleration. We have studied the time-dependent acceleration of electrons in a large-scale outflow from the Galactic centre. For the first time, we propose a detailed numerical solution of the particle kinetic equation that includes the acceleration, transport and relevant energy loss processes. We also take into account the addition of shock acceleration of electrons at the bubble’s blast wave. Fitting to the observed spectrum and surface brightness distribution of the bubbles allows determining the transport coefficients, thereby shedding light on the origin of the Fermi bubbles.},
doi = {10.1051/0004-6361/201833999},
journal = {Astronomy and Astrophysics},
number = ,
volume = 622,
place = {United States},
year = {2019},
month = {2}
}

Journal Article:
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This content will become publicly available on February 21, 2020
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