Events Daily

Tuesday, February 27, 2024

News from the search for the sources of ultra-high energy cosmic rays: Insights from the maximum rigidity distribution and a possible new source class
Foteini Oikonomou, NTNU (Trondheim, Norway)
Event Type: Astro Seminar
Time: 2:00 PM - 3:15 PM
Location: 726 Broadway, 940, CCPP Seminar
Abstract: An open question in the search for ultra-high-energy cosmic-ray sources is whether they are few and prominent or if a large population of sources collectively contributes to the diffuse flux. Motivated by this question, we investigated whether the latest UHECR data are consistent with originating from a population of sources that exhibit substantial diversity in terms of the cosmic ray spectra they produce. We found that the fit to the cosmic ray data requires sources that are intrinsically very similar in terms of the maximum rigidity reached. This is surprising, considering the sizeable astrophysical diversity exhibited by the candidate astrophysical source populations. One source class that may satisfy the constraints imposed by the fit to the UHECR data is non-jetted AGN. An increasing number of observations of ultra-fast outflows have emerged in the last few years, which provide an environment potentially conducive to UHECR acceleration. In this talk, I will present the insights we have gained from studying the maximum rigidity distribution and the case for UFOs as sites of UHECR acceleration.