23-28 June 2014
Amsterdam
Europe/Zurich timezone

The Spectrum and Morphology of the Fermi Bubbles

27 Jun 2014, 15:00
20m
Amsterdam

Amsterdam

Tuschinski Theatre Reguliersbreestraat 26 1017 CN Amsterdam
Presentation Gamma-Ray Astrophysics Gamma-Ray Astrophysics

Speaker

Anna Franckowiak (SLAC/KIPAC)

Description

The Fermi bubbles are two large structures in the gamma-ray sky extending up to 55 deg above and below the Galactic center. We present our analysis of 50 months of Fermi-LAT pass7 reprocessed data from 100 MeV to 500 GeV above 10 deg in Galactic latitude to derive the spectrum and morphology of the Fermi bubbles. We perform a detailed study of the systematic uncertainties due to the modeling of the Galactic diffuse emission. We find a cutoff in the energy spectrum around 110 GeV with more than 7 sigma significance, an excess of the emission in the south-east side of the bubbles, but no evidence for the existence of a jet and no spectral variations as a function of latitude within the systematic uncertainties. The width of the bubble boundary is estimated to be around 3 deg. Both inverse Compton (IC) models and hadronic models including IC emission from secondary leptons fit the gamma-ray data well. In the IC scenario, the synchrotron emission from the same population of electrons can also explain the WMAP and Planck microwave haze with a magnetic field between 5 and $20\mu$G.

Primary authors

Anna Franckowiak (SLAC/KIPAC) Dmitry Malyshev (SLAC/KIPAC) Vahe' Petrosian (Stanford/KIPAC)

Presentation Materials