Sky map of TeV gamma-ray emission from G106.3+2.7, as measured by VERITAS. For more details, see Figure 1 below.

Detection of extended VHE gamma-ray emission from G106.3+2.7 with VERITAS

Reference:  V. A. Acciari et al. (The VERITAS Collaboration), The Astrophysical Journal, 703: L6-L9, 2009

Full text version

ArXiv version: ArXiV:0911.4695

Contact person: Scott Wakely

G106.3+2.7 is the remnant of a galactic supernova which exploded approximately 10,000 years ago. Contained within the body of the remnant is one of the most energetic pulsars in the northern sky, PSR J2229+6114.  VERITAS observations of the region have resolved TeV gamma-ray emission coming from an extended portion of the radio remnant.  Notably, the centroid of the TeV flux is centered near the center of a coincident molecular cloud, some 0.4 degrees away from the pulsar position. This may suggest that the emission is due to hadronic interactions between cosmic rays accelerated in the remnant and the material of the cloud.  At other energies, the Fermi LAT team reports GeV emission at the location of the pulsar and the Milagro collaboration reports unresolved ~35 TeV emission from the general area.  The Milagro flux point lies along the extrapolated spectrum measured by VERITAS.  If there is, in fact, a single mechanism at work in producing the emission seen by both instruments, then this could strengthen the case for the hadronic scenario, given that the combined spectrum would lack the curvature expected from a typical inverse Compton (leptonic) model at these energies.

Figures from paper (click to get full size image): 

Figure 1 (shown above): Sky map of TeV gamma-ray emission from G106.3+2.7, as measured by VERITAS. The color scale indicates the number of excess gamma-ray events from the region, using a squared integration radius of 0.08 deg2. The centroid of the TeV emission is indicated with a thin black cross. Overlaid are 1420 MHz radio contours from the DRAO Synthesis Telescope (thin black lines; Landecker et al. 2000) and 12CO emission (J = 1 ? 0) from the high-resolution FCRAO Survey (magenta lines;Heyer et al. 1998). TheCOvelocity selection is discussed in the text. The open yellow cross shows the location of pulsar PSR J2229+6114 and the yellow star at the left is the AGILE bright source 1AGL J2231+6109. The yellow circle indicates the 95% error contour for the Fermi source 0FGL J2229.0+6114. The circle labeled PSF represents theVERITAS gamma-ray PSF for this analysis (68% containment).

Figure 2. Differential energy spectrum of G106.3+2.7 as measured by VERITAS. The error bars represent 1-sigma statistical errors only. The solid line shows the results of a pure power-law fit and the dotted line shows the flux of the Crab Nebula for comparison. Also shown (triangle) is the Milagro flux point from Abdo et al. (2009a), plotted with summed systematic and statistical errors. The lower panel shows the residuals of the VERITAS data to the power-law fit. The details of the analysis and the fit are discussed in the text.