Looking for ...
an excess in the gamma-ray data from the Galactic center peaked at 1-4 GeV
Method, Strategy and Results
Test-statistic, residuals and
full-ROI spectrum
We introduce a steady-state source - located at the Galactic center - with a narrow (~ 100 pc) spatial extension, the "spike"
Test-statistic, residuals,
and full-roi spectrum
Longitude, latitude and
radial profiles
The Inverse Compton (IC) emission of the spike
is correlated with the conventional IC template
We implement the modified IC template in the template-fitting algorithm
Spike vs. DM, sub-regions
Conclusions and prospects...
SFR in the Galactic center as an important source of gamma rays
Star formation rate ~1% of the rate in the Galaxy
Infrared
Far away from a comprehensive control of the astrophysical background at the GC
(two order of magnitude higher if compared with
the average in the Galaxy)
Connection with local observables
Figer et al., Astrophys. J. 581 (2002) 258
Gaggero, Urbano, Valli, Ullio, Phys.Rev. D91 (2015) 8, 083012
(need for a data-driven approach,
instead of a DM template-driven one?)
X-rays
The Galactic center is a large reservoir of molecular gas (Central Molecular Zone, extending up to 200/300 pc)
[2 x 0.8] deg. around the GC
For a review, see C. van Eldik,
arXiv:1505.06055
Ferriere, Gillard, Jean,
Astron. Astrophys. 467 (2007) 611
Tracers for warm dust and stellar activity
Solid black: SNRs (Case & Bhattacharya)
Dashed blue: Pulsars (Lorimer et al.)
Dotted red: Pulsars (Yusifov & Kucuk)
Dash-dotted green: OB stars (Bronfman et al.)
ISRF from Porter et al.,
Astrophys. J. 682, 400 (2008)
From Calore, Cholis, Weniger,
JCAP 1503 (2015) 038
See also Zhou, Liang, Huang, Li, Fan, Feng, Chang, Phys. Rev. D91 (2015) 12, 123010
An excess relative to what ?
Standard astrophysical background models
The Galactic center excess brought down-to-earth:
towards a realistic astrophysical interpretation.
Alfredo Urbano (SISSA)
In collaboration with:
Daniele Gaggero,
Mauro Valli,
Piero Ullio (SISSA)
and
Marco Taoso (CEA - Saclay)
arXiv:1507.06129
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