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We constrain the ratio of black hole (BH) mass to total stellar mass oftype-1 AGN in the COSMOS survey at 1<z<2. For 10 AGN at mean redshift z~1.4with both HST/ACS and HST/NICMOS imaging data we are able to compute totalstellar mass M_(*,total), based on restframe UV-to-optical host galaxy colorswhich constrain mass-to-light ratios. All objects have virial BH mass-estimatesavailable from the COSMOS Magellan/IMACS and zCOSMOS surveys. We find zerodifference between the M_BH--M_(*,total)-relation at z~1.4 and theM_BH--M_(*,bulge)-relation in the local Universe.  Our interpretation is: (a) If our objects were purely bulge-dominated, theM_BH--M_(*,bulge)-relation has not evolved since z~1.4. However, (b) since wehave evidence for substantial disk components, the bulges of massive galaxies(logM_(*,total)=11.1+-0.25 or logM_BH~8.3+-0.2) must have grown over the last 9Gyrs predominantly by redistribution of disk- into bulge-mass. Since allnecessary stellar mass exists in the galaxy at z=1.4, no star-formation oraddition of external stellar material is required, only a redistribution e.g.induced by minor and major merging or through disk instabilities. Merging, inaddition to redistributing mass in the galaxy, will add both BH andstellar/bulge mass, but does not change the overall final M_BH/M_(*,bulge)ratio.  Since the overall cosmic stellar and BH mass buildup trace each other tightlyover time, our scenario of bulge-formation in massive galaxies is independentof any strong BH-feedback and means that the mechanism coupling BH and bulgemass until the present is very indirect.

Massive Galaxies in COSMOS: Evolution of Black hole versus bulge mass but not versus total stellar mass over the last 9 Gyrs?