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5423. A search for Galactic transients disguised as gamma-ray burstsAurora Clerici, Cristiano Guidorzi, Valentina La Parola, 2015, izvirni znanstveni članek Opis: A significant fraction of cosmological gamma-ray bursts (GRBs) are characterised by a fast rise and exponential decay (FRED) temporal structure. This is not a distinctive feature of this class, since it is observed in many Galactic transients and is likely descriptive of a sudden release of energy followed by a diffusion process. Possible evidence has recently been reported by Tello et al. (2012) for a Galactic contamination in the sample of FRED GRBs discovered with Swift. We searched for possible Galactic intruders disguised as FRED GRBs in the Swift catalogue up to September 2014. We selected 181 FRED GRBs (2/3 with unknown redshift) and considered different subsamples. We tested the degree of isotropy through the dipole and the quadrupole moment distributions, both with reference to the Galaxy and in a coordinate-system-independent way, as well as with the two-point angular autocovariance function. In addition, we searched for possible indicators of a Galactic origin among the spectral and temporal properties of individual GRBs. We found marginal (~3 sigma) evidence for an excess of FREDs with unknown redshift towards the Galactic plane compared with what is expected for an isotropic distribution corrected for the non-uniform sky exposure. However, when we account for the observational bias against optical follow-up observations of low-Galactic latitude GRBs, the evidence for anisotropy decreases to ~2 sigma. In addition, we found no statistical evidence for different spectral or temporal properties from the bulk of cosmological GRBs. We found marginal evidence for the presence of a disguised Galactic population among Swift GRBs with unknown redshift. The estimated fraction is f=(19 +- 11)%, with an upper limit of 34% (90% confidence).
Ključne besede: gamma-ray burst, statistical, Galactic transient
Objavljeno v RUNG: 03.02.2016; Ogledov: 4841; Prenosov: 0
Gradivo ima več datotek! Več... |
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5428. Študij atmosferskih procesov v Vipavski dolini na podlagi razširjanja aerosolovMaruška Mole, Longlong Wang, Asta Gregorič, Klemen Bergant, Luka Drinovec, Griša Močnik, Samo Stanič, Janja Vaupotič, Marko Vučković, 2016, objavljeni znanstveni prispevek na konferenci Opis: Vipavska dolina je geomorfološko dokaj zaprta, kar po eni strani omogoča pojav močne burje, po drugi strani pa ob stabilnih meteoroloških razmererah ugodne pogoje za kopičenje aerosolov znotraj prizemne mejne plasti. Poznavanje dinamike višinske porazdelitve aerosolov s sočasno uporabo prizemnih meritev omogoča raziskave lokalnih emisij aerosolov, transporta aerosolov na daljše razdalje ter značilnih atmosferskih struktur, ki se pojavijo v različnih vremenskih pogojih. Pri meritvah smo uporabili metode daljinskega zaznavanja z lidarjem, ki omogočajo opazovanje časovnega in prostorskega spreminjanja koncentracij aerosolov, ter točkovne meritve, ki omogočajo njihovo prepoznavanje in določanje njihovih lastnosti. Ugotovili smo, da je mogoče lidarske meritve uporabiti za študij vrste atmosferskih procesov in struktur v zelo različnih vremenskih pogojih. Opazili smo manjše konvekcijske strukture znotraj prizemne mejne plasti in gravitacijske valove nad njo. Meritve vsebnosti in lastnosti aerosolov pri tleh kažejo, da se lahko ob stabilnih atmosferskih pogojih v primerih povečanja lokalnih emisij njihove koncentracije hitro povečajo. Dinamiko in strukturo razširjanja aerosolov znotraj Vipavske doline bomo v prihodnje podrobneje raziskali s sočasnim prostorskim pregledovanjem z metodami daljinskega zaznavanja.
Ključne besede: aerosoli, atmosferski procesi, daljinsko zaznavanje, Vipavska dolina
Objavljeno v RUNG: 25.01.2016; Ogledov: 6760; Prenosov: 9
Gradivo ima več datotek! Več... |
5429. Hydroxyl radical scavenging-based method for evaluation of TiO[sub]2 photocatalytic activityUrška Lavrenčič Štangar, Matija Strlič, Romana Cerc Korošec, Danijela Pucko, 2013, izvirni znanstveni članek Opis: Hydroxyl radical scavenging-based method for evaluation of TiO[sub]2 photocatalytic activity
Ključne besede: titanium dioxide, photocatalysis, N, N-(5-nitro-1, 3-phenylene)bisglutaramide, radical scavenger, HPLC
Objavljeno v RUNG: 05.01.2016; Ogledov: 5302; Prenosov: 33
 Povezava na celotno besedilo |
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