Black hole accretion and star formation as drivers of gas excitation and chemistry in Markarian 231 - Van der Werf, PP; Isaak, KG; Meijerink, R; Spaans, M; Rykala, A; Fulton, T; Loenen, AF; Walter, F; Weiß, A; Armus, L; others (Astronomy & Astrophysics, 2010)