Left: f_bursty as a function of z for three different AGN luminosity bins: 44 < log L_X/erg s^-1 < 44.5, 44.5 < log L_X/erg s^-1 < 45, and log L_X/erg s^-1 > 45 from bottom to top. Right: the starburstiness R_SB as a function of z of QSOs with L_bol > 10⁴⁶ erg/s. Triangles: stellar masses from SED fitting (Polletta et al. 2008; Lacy et al. 2011); circles: stellar masses from dynamical masses within the CO emitting region (Wang et al. 2010; Solomon & Vanden Bout 2005; Coppin et al. 2008; Shields et al. 2006; Maiolino et al. 2007; Gallerani 2012) and the [CII] emitting region (crossed circles, Wang et al. 2013). For the sources with [CII] measurements M_dyn are calculated assuming the disk inclination angle estimated from the [CII] minor and major axes ratio (see Wang et al. 2013). Open circles indicate dynamical masses derived assuming a disk radius of 2–2.5 kpc, while filled circles indicate dynamical masses obtained from spatially resolved measurements of the molecular gas emitting region. Squared circles denote sources in which R is measured as half the component separation in merger model (see Shields et al. 2006). Starred circles denote gravitationally lensed QSOs for which the CO and FIR luminosities have been corrected for magnification (Riechers 2011).