No signs of star formation being regulated in the most luminous quasars
  at z~2 with ALMA
  We present ALMA Band~7 observations at $850\mu$m of 20 luminous ($\log\,
L_{\rm bol}>46.9$ [erg s$^{-1}$]) unobscured quasars at $z\sim2$. We detect
continuum emission for 19/20 quasars. After subtracting an AGN contribution, we
measure the total far-IR luminosity for 18 quasars, assuming a modified
blackbody model, and attribute the emission as indicative of the star formation
rate (SFR). Our sample can be characterized with a log-normal SFR distribution
having a mean of 140 $M_\odot$ yr$^{-1}$ and a dispersion of 0.5 dex. Based on
an inference of their stellar masses, the SFRs are similar, in both the mean
and dispersion, with star-forming main-sequence galaxies at the equivalent
epoch. Thus, there is no evidence for a systematic enhancement or suppression
(i.e., regulation or quenching) of star formation in the hosts of the most
luminous quasars at $z\sim2$. These results are consistent with the Magneticum
cosmological simulation, while in disagreement with a widely recognized
phenomenological model that predicts higher SFRs than observed here based on
the high bolometric luminosities of this sample. Furthermore, there is only a
weak relation between SFR and accretion rate onto their supermassive black
holes both for average and individual measurements. We interpret these results
as indicative of star formation and quasar accretion being fed from the
available gas reservoir(s) in their host with a disconnect due to their
different physical sizes, temporal scales, and means of gas processing.
