Detection of Tev Gamma Ray Emission from Tycho's Supernova Remnant PDF Print


VERITAS TeV gamma-ray count map of the region around Tycho's SNR. The color scale indicates the number of excess gamma-ray events from a region, See Figure 1 below for more details.



Reference: V. A. Acciari et al. (The VERITAS Collaboration), accepted by the Astrophysical Journal 730: L20, 2011

Full text version here

ArXiv version: ArXiV:1102.3871

Contact persons: Scott Wakely, Dana Saxon


VERITAS has discovered TeV gamma-ray emission from the Type Ia supernova remnant (SNR) G120.1+1.4. The supernova explosion that created this remnant occurred in 1572 and was recorded by Tycho Brahe; hence, the remnant is known as Tycho's supernova remnant. Observations performed in the period 2008-2010 with VERITAS reveal weak emission coming from the direction of the remnant, compatible with a point source located at 00h 25m 27.0s, +64° 10' 50'' (J2000). The centroid position of the emission is slightly offset from the center of the remnant, in the direction of a molecular cloud which may be interacting with the remnant, but the offset is not statistically significant. If the cloud is interacting with the remnant, we would expect to see gamma rays resulting from a population of hadronic particles interacting with the cloud. Our paper presents both leptonic and hadronic models which can describe the existing data, so more observations will be needed to distinguish between the models and determine whether the cloud is interacting with the remnant.

One interesting point about our modeling is that the lowest magnetic field allowed by these models is ~80 μG, which may be interpreted as evidence for magnetic field amplification. This is intriguing because enhanced magnetic fields are a signature of accelerated cosmic rays, which produce very high energy gamma rays. SNRs are currently thought to be the best candidates for the source of the galactic cosmic ray population, so evidence of an enhanced cosmic ray population in the vicinity of SNRs is additional support for this idea. The TeV photon spectrum measured by VERITAS can be described by a power-law dN/dE = C(E/3.42 TeV), with Γ = 1.95 ± 0.51 stat ± 0.30 sys and C = (1.55 ± 0.43 stat ± 0.47 sys) x 10-14 cm-2 s-1 TeV-1. The integral flux above 1 TeV corresponds to ~0.9% of the steady Crab Nebula emission above the same energy, making it one of the weakest sources yet detected in TeV gamma rays.


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





Last Updated on Saturday, 26 October 2013 14:54

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