Measurements of the top quark processes in association with additional particles with the ATLAS detector

The high centre-of-mass energy of proton-proton collisions and the high integrated luminosities at the CERN Large Hadron Collider make it possible to study rare processes of the Standard Model (SM) with unprecedented precision. These measurements provide new tests of the SM predictions with the potential to unveil discrepancies with the SM predictions or provide important input for the improvement of theoretical calculations. Here, total and differential measurements of top quark production in association with additional bosons are shown using data taken with the ATLAS experiment at a centre-of-mass energy of 13 TeV, as well as a recent result on the evidence for the very rare process of four-top-quark production, combining several channels.