galactic foreground cleaning in gamma-rays
DESCRIPTION
Galactic Foreground cleaning in gamma-rays. Anisotropy Workshop, June 23 th 2010. Alessandro Cuoco, Oskar Klein Center, Stockholm University. The Microwave sky. In addition to CMB photons, WMAP data is “contaminated” by a number of galactic foregrounds that must be accurately subtracted - PowerPoint PPT PresentationTRANSCRIPT
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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Syn
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WMAP
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…