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000316967 005__ 20211110140544.0
000316967 0247_ $$2datacite_doi$$a10.3204/PUBDB-2017-00337
000316967 037__ $$aPUBDB-2017-00337
000316967 041__ $$aEnglish
000316967 1001_ $$0P:(DE-H253)PIP1012571$$aSkole, Christian$$b0$$eCorresponding author$$gmale$$udesy
000316967 245__ $$aSearch for extremely short transientgamma-ray sources with the VERITAS observatory$$f2013-01-01 - 2016-09-05
000316967 260__ $$c2016
000316967 300__ $$a165 p.
000316967 3367_ $$2DataCite$$aOutput Types/Dissertation
000316967 3367_ $$2ORCID$$aDISSERTATION
000316967 3367_ $$2BibTeX$$aPHDTHESIS
000316967 3367_ $$02$$2EndNote$$aThesis
000316967 3367_ $$0PUB:(DE-HGF)11$$2PUB:(DE-HGF)$$aDissertation / PhD Thesis$$bphd$$mphd$$s1484066101_3252
000316967 3367_ $$2DRIVER$$adoctoralThesis
000316967 502__ $$aHumboldt-Universität zu Berlin, Diss., 2016$$bDr.$$cHumboldt-Universität zu Berlin$$d2016
000316967 520__ $$aIn astronomy, many of the observed sources show a transient behavior. Examples aregamma-ray bursts (GRBs) and active galactic nuclei (AGN). For those source typesthe  variability  can  be  very  short,  in  the  order  of  seconds  to  minutes.   Measuringthe  flux  variations  is  necessary  to  understand  the  underlying  physical  processesresponsible  for  the  emission.   However,  the  detection  of  very  short  flares  can  bedifficult  in  the  very  high-energy  range,  in  which  imaging  atmospheric  Cherenkovtelescopes like VERITAS are operating.  This is due to the large background andthe comparable low signal rates.This thesis discusses the implementation of advanced statistical methods (exp-test and Bayesian-Blocks) into the VERITAS analysis framework, that are optimized forthe detection of significant variations in the event rate.  The performance of thesemethods is evaluated and compared by using Monte Carlo simulations of minute-scale flares for two different VERITAS states, pre- and post-hardware-upgrade.  Itis shown that the advanced methods can improve the detection sensitivity for shortflares with high fluxes of more than the Crab flux (Crab unit = C.U.).  For example,flares at 2 C.U. with short durations down to 100 sec are now detectable, which isnot possible with the standard method. In the next step of this thesis, 6 GRB afterglows and 450 runs of AGN data, observedby VERITAS, are analyzed with the advanced methods.  In none of the AGN runsa significant detection of short time variability is made, which is in consistence withthe  canonical  AGN  models.   The  investigation  of  the  6  GRB  afterglows  also  didnot reveal any short flares in the GeV-TeV range.  However, for two of them it waspossible  to  estimate  an  upper  flux  limit  of  1.25  C.U.  (≈3,7·10$^{−10}$ erg  cm$^{−1}$s$^{−1}$[0,1;10 TeV]).
000316967 536__ $$0G:(DE-HGF)POF3-613$$a613 - Matter and Radiation from the Universe (POF3-613)$$cPOF3-613$$fPOF III$$x0
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000316967 693__ $$0EXP:(DE-H253)VERITAS-20170101$$5EXP:(DE-H253)VERITAS-20170101$$eVery Energetic Radiation Imaging Telescope Array System$$x0
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000316967 9141_ $$y2016
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000316967 9201_ $$0I:(DE-H253)ZEU-EXP_AT-20120731$$kZEU-EXP/AT$$lAstroteilchenphysik$$x0
000316967 9201_ $$0I:(DE-H253)ZEU-CTA-20120731$$kZEU-CTA$$lCherenkov Telescope Array$$x1
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