Low-mass Active Galactic Nuclei on the Fundamental Plane of Black Hole
  Activity
  It is widely known that in active galactic nuclei (AGNs) and black hole X-ray
binaries (BHXBs), there is a tight correlation among their radio luminosity
($L_R$), X-ray luminosity ($L_X$) and BH mass ($\mbh$), the so-called
`fundamental plane' (FP) of BH activity. Yet the supporting data are very
limited in the $\mbh$ regime between stellar mass (i.e., BHXBs) and
10$^{6.5}$\,\msun\ (namely, the lower bound of supermassive BHs in common
AGNs). In this work, we developed a new method to measure the 1.4 GHz flux
directly from the images of the VLA FIRST survey, and apply it to the type-1
low-mass AGNs in the \cite{2012ApJ...755..167D} sample. As a result, we
obtained 19 new low-mass AGNs for FP research with both \mbh\ estimates ($\mbh
\approx 10^{5.5-6.5}$\,\msun), reliable X-ray measurements, and (candidate)
radio detections, tripling the number of such candidate sources in the
literature.Most (if not all) of the low-mass AGNs follow the standard
radio/X-ray correlation and the universal FP relation fitted with the combined
dataset of BHXBs and supermassive AGNs by \citet{2009ApJ...706..404G}; the
consistency in the radio/X-ray correlation slope among those accretion systems
supports the picture that the accretion and ejection (jet) processes are quite
similar in all accretion systems of different \mbh. In view of the FP relation,
we speculate that the radio loudness $\mathcal{R}$ (i.e., the luminosity ratio
of the jet to the accretion disk) of AGNs depends not only on Eddington ratio,
but probably also on \mbh.
