Search of Intermediate Mass Black Holes at Low Redshift with Intra-night
  Variability
  We present a sample of intermediate-mass black hole (IMBH) candidates based
on the detection of a broad H$\alpha$ emission line and variability, which are
selected from the Sloan Digital Sky Survey Data Release 7. By performing
spectral decomposition of emission lines as well as visual inspection, we
initially identified 131 targets with a broad H$\alpha$ line among a large
sample of emission-line galaxies. We further selected 25 IMBH candidates, whose
estimated black hole mass (M$_{\rm BH}$) is less than $10^6 \rm M_{\odot}$. To
constrain the nature of these candidates, we analyzed X-ray properties and
performed an intra-night variability monitoring with optical telescopes. Based
on the optical variability analysis, we report a sample of 11 targets with
detected intra-night variability as the best IMBH candidates, which are
suitable for follow-up observations for accurate M$_{\rm BH}$ determination
such as reverberation mapping campaigns.
