Source models and theory challanges of UHECRs
- Paul Sommers (Penn State University)
Contributed talks 6x15+5 min
Sergey Troitsky (Russian Academy of Sciences (RU))
2/15/12, 2:00 PM
I discuss possible sites of acceleration of UHECRs by regular electromagnetic fields in astrophysical sources. A plausible mechanism of acceleration works in the vicinity of supermassive black holes in active galactic nuclei. It is motivated by relatively high density of UHECR sources as suggested by both statistics of clustering and the shape of the GZK cutoff. However, I demonstrate that the...
Gwenael Giacinti (NTNU Trondheim, Norway)
2/15/12, 2:20 PM
In this work, we investigate the impacts a potential shift towards a heavy composition at the end of the spectrum would have on the future data. We present detailed simulations for the propagation of ultra-high energy heavy nuclei, with E > 60 EeV, within recent Galactic Magnetic Field (GMF) models. We both consider the regular and turbulent components of the GMF. We show that with UHE heavy...
Prof. Daniele Fargion (Rome University 1 Sapienza and INFN)
2/15/12, 2:40 PM
Since last decades UHECR models teach us that at EeV energy UHECR are mostly of extragalactic origin. Moreover earliest (2007) AUGER at 55 EeV energy events were suggesting an UHECR GZK cut off and arrival map correlated with super-galactic plane, SGP,inside the expected GZK volume traced by protons. However the same AUGER composition imprint favoured nuclei (heavy or light) and not...
Alexander Kusenko (UCLA)
2/15/12, 3:00 PM
First, I will present new evidence, from gamma-ray observations of blazars, that cosmic rays are, indeed, accelerated in AGNs. Second, I will discuss the plausibility of a substantial contribution of transient galactic sources, such as past GRBs and hypernovae, to the observed flux of cosmic-ray nuclei. The likely contamination of UHECR data by the nuclei from past galactic stellar...
Dr Andrew Taylor (ISDC, University of Geneva)
2/15/12, 3:20 PM
Using the recent Auger energy spectrum and composition analysis results, an investigation is carried out into the requirements placed on the UHECR sources. The spatial distribution of these sources is investigated along with the energy distribution of UHECR they output. These investigations reveal the need for local UHECR sources which output a hard spectrum of intermediate/heavy...
Hajime Takami (M)
2/15/12, 3:40 PM
The origin of ultra-high-energy (UHE) cosmic rays (CRs) is still unknown and one of the biggest mysteries in modern astrophysics. The uncertainty of their composition makes this problem more complicated. If protons are dominant in UHECRs and are produced by phenomena related to astrophysical jets or outflows, there are few steady source candidates in local Universe which have luminosities...