An Updated Search of Steady TeV γ−Ray Point Sources in Northern Hemisphere Using the Tibet Air Shower Array
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چکیده
Using the data taken from Tibet II High Density (HD) Array (1997 February1999 September) and Tibet-III array (1999 November-2005 November), our previous northern sky survey for TeV γ−ray point sources has now been updated by a factor of 2.8 improved statistics. From 0.0 to 60.0 in declination (Dec) range, no new TeV γ−ray point sources with sufficiently high significance were identified while the well-known Crab Nebula and Mrk421 remain to be the brightest TeV γ−ray sources within the field of view of the Tibet air shower array. Based on the currently available data and at the 90% confidence level (C.L.), the flux upper limits for different power law index assumption are re-derived, which are approximately improved by 1.7 times as compared with our previous reported limits. Subject headings: ASγ experiment, γ−ray point sources, 90% C.L., flux upper limits
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