Galactic Foreground cleaning in Galactic Foreground cleaning in gamma-rays gamma-rays

Alessandro Cuoco,Oskar Klein Center,

Stockholm University

Anisotropy Workshop,

June 23th 2010

The Microwave skyThe Microwave sky•In addition to CMB photons, WMAP data is “contaminated” by a number of galactic foregrounds that must be accurately subtracted

•The WMAP frequency range is well suited to minimize the impact of foregrounds

•Substantial challenges are involved in identifying and removing foregrounds

Template fittingTemplate fitting

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Synchrotron: Synchrotron: Template: C.G.T. Haslam et al., A&A Template: C.G.T. Haslam et al., A&A 100 (1981) 100 (1981) 209.209.

CMB: CMB: Gold et al., Gold et al., arXiV:1001.4555arXiV:1001.4555..

Freefree: Freefree: Template: D.P. Finkbeiner, ApJS Template: D.P. Finkbeiner, ApJS 146 (2003) 146 (2003) 407.407.

Dust:Dust: Template: D.P. Finkbeineret al., ApJ Template: D.P. Finkbeineret al., ApJ 524 (1999) 524 (1999) 867.867.

TOTATOTALL

The “WMAP Haze”The “WMAP Haze”

After known foregrounds are subtracted, an excess appears in the residual maps within the inner ~20 around the Galactic

Center

D. P. Finkbeiner, Astrophys. J. 614 (2004) 186

G. Dobler and D. P. Finkbeiner, arXiv:0712.1038 [astro-ph].

WMAP Team foreground analysis and WMAP Team foreground analysis and the Hazethe Haze

WMAP Collaboration (B. Gold et al.) 2008[arXiv:astro-ph/0803.0715].

D.T. Cumberbatch,, arXiv:0902.0039 [astro-ph].

Map of the synchrotron spectral indexes in a pixel by pixel fit procedure by WMAP

Synchrotron spectral indexes averaged along constant longitudes stripes by WMAP

The fit procedure used for the haze extraction is quite important, and using more degrees of freedom to model the foregrounds as performed by the WMAP team fails in finding the feature. They still find an hardening of the synchrotron emission in the Haze region, though.

The Gamma SkyThe Gamma Sky

Galprop Galprop Foregrounds Model:Foregrounds Model:

Galactic Contribution from: 1. Pion Decay 2. Inverse Compton 3. Electron Bremsstrahlung

Moskalenko et al.Moskalenko et al.

Morphology of the gamma-sky Morphology of the gamma-sky componentscomponents

Dobler, Finkbeiner et al. 2009Dobler, Finkbeiner et al. 2009

A Fermi Haze?

Further directions:Further directions:

Multi-template fitting using gas rings?Multi-template fitting using gas rings?

More directions:More directions:

Planck dust map(s) as gas templatesPlanck dust map(s) as gas templates

Lot of work to do…Lot of work to do…