Radial stellar populations of AGN-host dwarf galaxies in SDSS-IV MaNGA
  survey
  Based on MaNGA integral field unit (IFU) spectroscopy we search 60 AGN
candidates, which have stellar masses
$M_{\star}\leqslant5\times10^{9}$$M_{\odot}$ and show AGN ionization signatures
in the BPT diagram. For these AGN candidates, we derive the spatially resolved
stellar population with the stellar population synthesis code STARLIGHT and
measure the gradients of the mean stellar age and metallicity. We find that the
gradients of mean stellar age (metallicity) of individual AGN-host dwarfs are
diverse in 0-0.5 Re, 0.5-1 Re and 0-1 Re. However, the overall behavior of the
mean stellar age (metallicity) profiles tend to be flat, as the median values
of the gradients are close to zero. We further study the overall behavior of
the mean stellar age (metallicity) by plotting the co-added radial profiles for
the AGN sample and compare with a control sample with similar stellar mass. We
find that the median values of light-weighted mean stellar ages of AGN sample
are as old as 2-3 ~Gyr within 2 Re,which are about 4-7 times older than those
of the control sample. Meanwhile, most of the AGN candidates are low-level
AGNs, as only eight sources have L[OIII]>$10^{39.5}$~erg~s$^{-1}$. Hence, the
AGNs in dwarf galaxies might accelerate the evolution of galaxies by
accelerating the consumption of the gas, resulting in an overall quenching of
the dwarf galaxies, and the AGNs also become weak due to the lack of gas. The
median values of mass-weighted mean stellar age of both samples within 2 $Re$
are similar and as old as about 10~Gyr, indicating that the stellar mass is
mainly contributed by old stellar populations.The gradients of co-added mean
stellar metallicity for both samples tend to be negative but close to zero, and
the similar mean stellar metallicity profiles for both samples indicate that
the chemical evolution of the host galaxy is not strongly influenced by the
AGN.
