Séminaire / Seminar GReCO |
| « Where do AMS-02 anti helium events come from? » |
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Vivian Poulin |
| The origin of matter, i.e., baryogenesis is one of the many conundrum that the Alpha-Magnetic Spectrometer 02 (AMS-02) is trying to tackle. By collecting billions of cosmic rays, AMS-02 is able to measure tiny fluxes of high-energy *anti*-matter particles. Measurements of positrons and anti-protons have for instance led to strong constraints on Dark Matter properties. In this talk, I will discuss consequences of the (tentative) detection of heavier anti-nuclei by AMS-02; namely anti-helium-3 and -4 events. I will first show that the standard astrophysical scenario, i.e., spallation from primary hydrogen and helium nuclei onto the ISM cannot account for the measured fluxes. I will then argue that Dark Matter face similar strong difficulties to explain these events. Finally, I will entertain the possibility that these events originate from anti-matter-dominated regions in the form of anti-clouds or anti-stars that exist in our Galaxy. I will discuss the strong contraints limiting (but not excluding) the abundance of such objects, and discuss potential consequences of these scenarios for our (non-)understanding of the early universe and the era of baryogenesis. |
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lundi 27 janvier 2020 - 11:00 Salle des séminaires Évry Schatzman Institut d'Astrophysique de Paris |
| Pages web du séminaire / Seminar's webpage |