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New Multi-TeV Gamma-Ray Sources MGRO J0632+17 and MGRO J2228+61

ATEL # 2172; Jordan Goodman (U Maryland College Park) and Gus Sinnis (Los Alamos National Lab) for the Milagro Collaboration
on 24 Aug 2009; 23:28 UT
Password Certification: David A. Williams (

Subjects: Gamma Ray, >GeV, Pulsars, Supernova Remnants

In the recent paper "Milagro Observations of Multi-TeV Emission from Galactic Sources in the Fermi Bright Source List" (Abdo et al. 2009, ApJ 700:L127 and erratum, in press), we report detection of multi-TeV gamma-ray emission positionally coincident with two Fermi sources. For purposes of identifying these very-high-energy Milagro counterparts, we report now source names for the Milagro objects. MGRO J0632+17 is an extended region of gamma-ray emission containing the Fermi source 0FGL J0634.0+1745 (the Geminga pulsar). The local maximum of the Milagro excess is at right ascension 6h 32m 28s and declination 17d 22m (J2000), and is consistent with the candidate first reported by Milagro as C3 in Abdo et al. 2007 (ApJ 664:L91). MGRO J2228+61 coincides with the Fermi source 0FGL J2229.0+6114, the Boomerang pulsar. The position of the peak of the Milagro excess is right ascension 22h 28m 44s and declination 61d 10m (J2000), with a statistical error of 0.165 degrees, consistent with candidate C4 of Abdo et al. 2007. The position of MGRO J2228+61 reported here has been corrected and will appear in an accepted erratum to Abdo et al. 2009. The fit that yielded the original result is only suitable for isolated sources because it includes data from an extended region, +-3 deg. around the candidate position. Therefore, the presence of multi-TeV emission from the Fermi pulsar at RA=339.561, Dec=59.080 -- noted in footnote 20 of the published paper -- skewed the fit. Restricting the fit to the peak region gives the corrected position.

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