Cosmic rays in a galactic breeze

Andrew M. Taylor and Gwenael Giacinti
Phys. Rev. D 95, 023001 – Published 6 January 2017

Abstract

Motivated by the discovery of the nonthermal 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 advecting within a galactic breeze outflow, interacting with the ambient gas present, give rise to γ-ray emission, providing an approximately flat surface brightness profile of this emission, as observed. Applying the same outflow profile further out within the disk, the resultant effects on the observable CR spectral properties are determined. A hardening in the spectra due to the competition of advective and diffusive propagation within a particular energy range is noted, even in the limiting case of equal CR diffusion coefficients in the disk and halo. It is postulated that this hardening effect may relate to the observed hardening feature in the CR spectrum at a rigidity of 200GV.

  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Received 29 July 2016

DOI:https://doi.org/10.1103/PhysRevD.95.023001

© 2017 American Physical Society

Physics Subject Headings (PhySH)

Gravitation, Cosmology & Astrophysics

Authors & Affiliations

Andrew M. Taylor1,* and Gwenael Giacinti2,†

  • 1Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2, Ireland
  • 2Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg, Germany

  • *taylora@cp.dias.ie
  • giacinti@mpi-hd.mpg.de

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 95, Iss. 2 — 15 January 2017

Reuse & Permissions
Access Options
Author publication services for translation and copyediting assistance advertisement

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review D

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×