New approach to broad line region radius in Mrk142 after considering
  potential short-term optical transient quasi-periodic oscillations
  Mrk142 has been known as the only outlier in R-L space (correlation between
BLRs (broad line regions) radii and continuum luminosity) among the low
redshift local reverberation mapped broad line AGNs (BLAGNs) with moderate
accretion rates, due to its BLRs radius smaller than R-L expected value. Here,
considering probable optical transient quasi-periodic oscillations (QPOs), a
new approach to assessing the BLRs radius can be considered. Reliable transient
QPOs in high-energy emissions from black hole vicinity have been reported in
several normal AGNs, however there are so-far few short-term low-energy optical
transient QPOs in normal BLAGNs (not the QPOs reported in blazars nor in AGNs
harbouring binary BH systems). Through the photometric optical light curves
well directly described by sinusoidal functions, we report probable short-term
optical transient QPOs with periodicities around 14days and 43days in BLAGN
Mrk142, indicating similar but scaled optical QPOs as those in high-energy
bands. Considering the 14days QPOs related to reprocessing procedure, new
approach to the BLRs radius can be estimated in Mrk142 through the
reverberation mapping technique. The new BLRs radius of Mrk142 well follows the
R-L relation, demonstrating the R-L relation is fundamental in local normal
BLAGNs without ultra-high accretion rates.
