We report results of the first reverberation mapping campaign of I Zwicky 1 during 2014 - 2016 , which showed unambiguous reverberations of the broad H \beta line emission to the varying optical continuum .
From analysis using several methods , we obtain a reverberation lag of \tau _ { H \beta } = 37.2 ^ { +4.5 } _ { -4.9 } days .
Taking a virial factor of f _ { { } _ { BLR } } = 1 , we find a black hole mass of M _ { \bullet } = 9.30 _ { -1.38 } ^ { +1.26 } \times 10 ^ { 6 } M _ { \odot } from the mean spectra .
The accretion rate is estimated to be 203.9 _ { -65.8 } ^ { +61.0 } L _ { Edd } c ^ { -2 } , suggesting a super-Eddington accretor , where L _ { Edd } is the Eddington luminosity and c is the speed of light .
By decomposing Hubble Space Telescope images , we find that the stellar mass of the bulge of its host galaxy is \log ( M _ { bulge } / M _ { \odot } ) = 10.92 \pm 0.07 .
This leads to a black hole to bulge mass ratio of \sim 10 ^ { -4 } , which is significantly smaller than that of classical bulges and elliptical galaxies .
After subtracting the host contamination from the observed luminosity , we find that I Zw 1 follows the empirical R _ { BLR } \propto L _ { 5100 } ^ { 1 / 2 } relation .