Speaker
Description
Axion-like particles (ALPS), radiated from a network of cosmic strings, may be a large part of Dark Matter (DM). In the era of precision cosmology, it is possible to characterize the effect of such particles - which almost scale invariant distribution function spans many orders of magnitudes in momentum - on the observables. In this work, we employ the CLASS code and Planck 2018 data to place bounds on the abundance and on other distinctive parameters of ALPS from strings. We focus on the mass range $10^{-20} -10^{-15} $ eV, and we find the strongest constraint on the ALP decay constant $f_a$ if the ALP mass is between $10^{-20}-10^{-18}$ eV, where we are able to improve the overabundance of DM bound on $f_a$ by more than a factor of 3. As a result, ALPS from strings cannot account for more than one-tenth of DM at three sigma if $m_a $ is between $10^{-20}- 10^{-18}$ eV.
