2012/06/07 by Su, Meng, Finkbeiner, Douglas P. · 1 citation
#FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE) #High Energy Physics - Phenomenology (hep-ph)
paper · doi:10.48550/arxiv.1206.1616
Using 3.7 years of \Fermi-LAT data, we examine the diffuse 80-200 GeV emission in the inner Galaxy and find a resolved gamma-ray feature at ∼ 110-140 GeV. We model the spatial distribution of this emission with a ∼3° FWHM Gaussian, finding a best fit position 1.5° West of the Galactic Center. Even better fits are obtained for off-center Einasto and power-law profiles, which are preferred over the null (no line) hypothesis by 6.5σ (5.0σ/5.4σ after trials factor correction for one/two line case) assuming an NFW density profile centered at (ℓ, b)=(-1.5°,0°) with a power index α=1.2 . The energy spectrum of this structure is consistent with a single spectral line (at energy 127.0± 2.0 GeV with χ2=4.48 for 4 d.o.f.). A pair of lines at 110.8± 4.4 GeV and 128.8± 2.7 GeV provides a marginally better fit (with χ2=1.25 for 2 d.o.f.). The total luminosity of the structure is (3.2±0.6)× 1035 erg/s, or (1.7±0.4)× 1036 photons/sec. The energies in the two-line case are compatible with a 127.3 ± 2.7 GeV WIMP annihilating through γγ and γZ (with χ2=1.67 for 3 d.o.f.). We describe a possible change to the \Fermi scan strategy that would accumulate S/N on spectral lines in the Galactic center 4 times as fast as the current survey strategy.