https://ui.adsabs.harvard.edu/abs/2019ApJ...883L..13I/abstract, is the NASA ADS Abstract and arXiv paper. Just ended is discussed. "...Given the expected size of the narrow-line region, this luminosity decrease by a factor of ≳10^3 must have occurred within ≲10^4 yr. This extremely rapid luminosity/accretion shutdown is puzzling, and it requires one burst-like accretion mechanism producing a clear outer boundary for an accretion disk. We raise two possible scenarios realizing such an accretion mechanism: a mass accretion (1) by the tidal disruption of a molecular cloud and/or (2) by the gas depletion as a result of vigorous nuclear star formation after rapid mass inflow to the central engine."
The redshift reported for Arp 187, "Out of those ∼ 20 sources, Arp 187, a merger remnant infrared galaxy located at z = 0.04" Using the cosmology calculators, look back or light-time distance about 546 million light-years from Earth or 566 million light-years depending upon the calculator and values used for H0. 3,000 light-year size object has an angular size about 1.2 arcsecond.
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