Measurements of ttbar+X using the ATLAS detector

The large integrated luminosity provided by the LHC enables the production significant numbers of top quark pairs in association with additional jets or additional gauge bosons. The production of top quark pairs in association with $W$ and $Z$ bosons is presented. The measurement uses events with multiple leptons and in particular probes the coupling between the top quark and the $Z$ boson. A significance of five standard deviations is found for the production of a top quark pair with a $W$ boson. The cross section measurement of photons produced in association with top quark pairs is presented. The measurement uses a data driven technique to extract the signal from the background and achieves a significance of greater than 5 standard deviations. In addition, the production cross section of top quark pairs in association with jets is presented. This process allows better understanding of QCD effects and is an important background to many searches for physics beyond the Standard Model.