Observations of Crab Nebula and pulsar with VERITAS. Özlem Çelik

ISBN: 9781109119220

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NOOKstudy eTextbook

274 pages


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Observations of Crab Nebula and pulsar with VERITAS.  by  Özlem Çelik

Observations of Crab Nebula and pulsar with VERITAS. by Özlem Çelik
| NOOKstudy eTextbook | PDF, EPUB, FB2, DjVu, AUDIO, mp3, RTF | 274 pages | ISBN: 9781109119220 | 3.18 Mb

The Crab Nebula, the standard candle in very-high-energy (VHE) astronomy, is one of the most studied sources in all of astronomy. It is scientifically important to measure the energy spectrum of the Crab Nebula close to the inverse Compton peak orMoreThe Crab Nebula, the standard candle in very-high-energy (VHE) astronomy, is one of the most studied sources in all of astronomy.

It is scientifically important to measure the energy spectrum of the Crab Nebula close to the inverse Compton peak or above 10 TeV where a deviation from the power law, seen at energies between 300 GeV and ∼5 TeV, may occur. Additionally, it is important to search for pulsed emission from the Crab Pulsar at energies beyond 10 GeV which is the upper limit of the EGRET detection of pulsed emission.

Since current models predict a cut-off in the pulsed emission between 10 and 100 GeV, measurements at energies close to this range may help to discriminate between them. With these motivations, the Crab has been observed during the 2-, 3-, and 4-telescope phases of the commissioning of the Very Energetic Radiation Imaging Telescope Array System (VERITAS). The energy spectrum of the Crab Nebula between 350 GeV and 6 TeV is constructed from these data sets. A simple power law, dNdE = (3.19 +/- 0.07stat +/- 0.70 sys) x 10-7 E1TeV 2.40+/-0.03 stat+/-0.17sys TeV-1m-2s-1 , is found to give the best fit to the data obtained with the full 4-telescope array of VERITAS.

Furthermore, a periodic modulation is searched for in the gamma-ray emission above 100 GeV at the Crab Pulsar period of 33 ms. The Crab data set from the 2006--2008 VERITAS observations did not show any significant pulsed excess, so an upper limit on the pulsed emission from the Crab Pulsar is obtained. This upper limit constrains the cutoff energy of the spectrum to be less than 50 GeV, assuming that the differential energy spectrum of the pulsed emission has an exponential cutoff.



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