Constraints on the antistar fraction in the Solar System neighborhood

Discussion timeslot (ZOOM-Meeting): 16. July 2021 - 18:00
ZOOM-Meeting URL: https://icrc2021.desy.de/pf_access_abstracts
Corresponding Session: https://icrc2021-venue.desy.de/channel/Presenter-Forum-1-Evening-All-Categories/48
Abstract:
'It is generally taken for granted that the observable Universe does not contain anti-matter objects or domains. Recently, the possible detection of anti-helium nuclei in cosmic rays by AMS-02 challenged this idea and reopened the debate on the existence of nearby reservoirs of antimatter, most plausibly in antistars. As antimatter domains surrounded by normal matter would produce a gamma-ray signal from baryon-antibaryon annihilation, we use the 10-years *Fermi* Large Area Telescope (LAT) gamma-ray source catalog to set constraints on the abundance of antistars in our local Galactic environment. We identify 14 antistar candidates not associated with any object belonging to established gamma-ray source classes and featuring spectra compatible with baryon-antibaryon annihilation. We evaluate the sensitivity of the LAT to antistars and set upper limits on the local antistar fraction with respect to normal stars using both a parametric and a Monte Carlo method. For antistars with properties similar to those of disk-population stars we derive constraints that are 20 times stronger than those previously available. For a primordial population of antistars in the Galactic halo, gamma-ray data combined with microlensing observations constrain the density of antistars to lower than $O$($10^{-5}$ pc$^{−3}$) to $O$($10^{−2}$ pc$^{−3}$) depending on their masses. Our limits can constrain models for the origin and propagation of anti-nuclei in cosmic rays.'

Authors: Simon Dupourqué | Luigi Tibaldo | Peter von Ballmoos
Indico-ID: 401
Proceeding URL: https://pos.sissa.it/395/613