Broad-line Region of the Quasar PG 2130+099 from a Two-Year
  Reverberation Mapping Campaign with High Cadence
  As one of the most interesting Seyfert 1 galaxies, PG 2130+099 has been the
target of several reverberation mapping (RM) campaigns over the years. However,
its measured broad H$\beta$ line responses have been inconsistent, with time
lags of $\sim$200 days, $\sim$25 days, and $\sim$10 days being reported for
different epochs while its optical luminosity changed no more than 40%. To
investigate this issue, we conducted a new RM-campaign with homogenous and high
cadence (about $\sim$3 days) for two years during 2017--2019 to measure the
kinematics and structure of the ionized gas. We successfully detected time lags
of broad H$\beta$, He II, He I, and Fe II lines with respect to the varying
5100\AA continuum, revealing a stratified structure that is likely virialized
with Keplerian kinematics in the first year of observations, but an inflow
kinematics of the broad-line region from the second year. With a central black
hole mass of $0.97_{-0.18}^{+0.15}\times 10^7~M_{\odot}$, PG 2130+099 has an
accretion rate of $10^{2.1\pm0.5}L_{\rm Edd}c^{-2}$, where $L_{\rm Edd}$ is the
Eddington luminosity and $c$ is speed of light, implying that it is a
super-Eddington accretor and likely possesses a slim, rather than thin,
accretion disk. The fast changes of the ionization structures of the three
broad lines remain puzzling.
