Galactic halo size in the light of recent AMS-02 data
Nathanael Weinrich, Mathieu Boudaud, L. Derome, Yoann Génolini, Julien Lavalle, D. Maurin, Pierre Salati, Pasquale Dario Serpico, G. Weymann-Despres
Abstract
Context. The vertical diffusive halo size of the Galaxy, L, is a key parameter for dark matter indirect searches. It can be better determined thanks to recent AMS-02 data. Aims. We set constraints on L from Be/B and 10Be/Be data, and we performed a consistency check with positron data. We detail the dependence of Be/B and 10Be/Be on L and forecast on which energy range better data would be helpful for future L improvements. Methods. We used <ns0:sc>USINE V3.5</ns0:sc> for the propagation of nuclei, and e+ were calculated with the pinching method. Results. The current AMS-02 Be/B (∼3% precision) and ACE-CRIS 10Be/Be (∼10% precision) data bring similar and consistent constraints on L. The AMS-02 Be/B data alone constrain $ L=5^{+3}_{-2} $ kpc at a 68% confidence level (spanning different benchmark transport configurations), a range for which most models do not overproduce positrons. Future experiments need to deliver percent-level accuracy on 10Be/9Be anywhere below 10 GV to further constrain L. Conclusions. Forthcoming AMS-02, HELIX, and PAMELA 10Be/9Be results will further test and possibly tighten the limits derived here. Elemental ratios involving radioactive species with different lifetimes (e.g. Al/Mg and Cl/Ar) are also awaited to provide complementary and robuster constraints.