Resolving the dynamical mass of a z~1.3 QSO host galaxy using SINFONI and Laser Guide Star assisted Adaptive Optics

摘要

Recent studies of the tight scaling relations between the masses ofsupermassive black holes and their host galaxies have suggested that in thepast black holes constituted a larger fraction of their host galaxies' mass.However, these arguments are limited by selection effects and difficulties indetermining robust host galaxy masses at high redshifts. Here we report thefirst results of a new, complementary diagnostic route: we directly determine adynamical host galaxy mass for the z=1.3 luminous quasar J090543.56+043347.3through high-spatial-resolution (0.47", 4kpc FWHM) observations of the hostgalaxy gas kinematics over 30x40 kpc using ESO/VLT/SINFONI with LGS/AO.Combining our result of M_dyn = 2.05+1.68_0.74 x 10^11 M_sun (within a radius5.25 +- 1.05 kpc) with M_BH,MgII = 9.02 \pm 1.43 x 10^8 M_sun, M_BH,Halpha =2.83 +1.93-1.13 x 10^8 M_sun, we find that the ratio of black hole mass to hostgalaxy dynamical mass for J090543.56+043347.3 matches the present-day relationfor M_BH vs. M_Bulge,Dyn, well within the IR scatter, deviating at most afactor of two from the mean. J090543.56+043347.3 displays clear signs of anongoing tidal interaction and of spatially extended star formation at a rate of50-100 M_sun/yr, above the cosmic average for a galaxy of this mass andredshift. We argue that its subsequent evolution may move J090543.56+043347.3even closer to the z=0 relation for M_BH vs. M_Bulge,Dyn. Our results supportthe picture where any substantive evolution in these relations must occur priorto z~1.3. Having demonstrated the power of this modelling approach we arecurrently analyzing similar data on seven further objects to better constrainsuch evolution.