2 research outputs found
Observation of the TeV gamma-ray source MGRO J1908+06 with ARGO-YBJ
The extended gamma ray source MGRO J1908+06, discovered by the Milagro air
shower detector in 2007, has been observed for about 4 years by the ARGO-YBJ
experiment at TeV energies, with a statistical significance of 6.2 standard
deviations. The peak of the signal is found at a position consistent with the
pulsar PSR J1907+0602. Parametrizing the source shape with a two-dimensional
Gauss function we estimate an extension \sigma = 0.49 \pm 0.22 degrees,
consistent with a previous measurement by the Cherenkov Array H.E.S.S.. The
observed energy spectrum is dN/dE = 6.1 \pm 1.4 \times 10^-13 (E/4 TeV)^{-2.54
\pm 0.36} photons cm^-2 s^-1 TeV^-1, in the energy range 1-20 TeV. The measured
gamma ray flux is consistent with the results of the Milagro detector, but is
2-3 times larger than the flux previously derived by H.E.S.S. at energies of a
few TeV. The continuity of the Milagro and ARGO-YBJ observations and the stable
excess rate observed by ARGO-YBJ along 4 years of data taking support the
identification of MGRO J1908+06 as the steady powerful TeV pulsar wind nebula
of PSR J1907+0602, with an integrated luminosity above 1 TeV about 1.8 times
the Crab Nebula luminosity.Comment: 6 pages, accepted for pubblication by ApJ. Replaced to correct the
author lis
OBSERVATION OF TeV GAMMA RAYS FROM THE UNIDENTIFIED SOURCE HESS J1841â055 WITH THE ARGO-YBJ EXPERIMENT
We report the observation of a very high energy Îł -ray source whose position is coincident with HESS J1841â055.
This source has been observed for 4.5 years by the ARGO-YBJ experiment from 2007 November to 2012 July.
Its emission is detected with a statistical significance of 5.3 standard deviations. Parameterizing the source shape
with a two-dimensional Gaussian function, we estimate an extension Ï = (0.40+0.32
â0.22)âŠ, which is consistent with
the HESS measurement. The observed energy spectrum is dN/dE = (9.0 ± 1.6) Ă 10â13(E/5 TeV)â2.32±0.23
photons cmâ2 sâ1 TeVâ1, in the energy range 0.9â50 TeV. The integral Îł -ray flux above 1 TeV is 1.3 ± 0.4 Crab,
which is 3.2 ± 1.0 times the flux derived by HESS. The differences in the flux determination between HESS and
ARGO-YBJ and possible counterparts at other wavelengths are discussed