The sign of active galactic nucleus quenching in a merger remnant with
  radio jets
  We investigate optical, infrared, and radio active galactic nucleus (AGN)
signs in the merger remnant Arp 187, which hosts luminous jets launched in the
order of $10^5$ yr ago but whose present-day AGN activity is still unknown. We
find AGN signs from the optical BPT diagram and infrared [OIV]25.89 $\mu$m
line, originating from the narrow line regions of AGN. On the other hand,
Spitzer/IRS show the host galaxy dominated spectra, suggesting that the thermal
emission from the AGN torus is considerably small or already diminished.
Combining the black hole mass, the upper limit of radio luminosity of the core,
and the fundamental plane of the black hole enable us to estimate X-ray
luminosity, which gives $<10^{40}$ erg s$^{-1}$. Those results suggest that the
AGN activity of Arp 187 has already been quenched, but the narrow line region
is still alive owing to the time delay of emission from the past AGN activity.
