Arp 187

Arp 187 is a radio galaxy and merger remnant located in the constellation Eridanus. It is an interacting galaxy pair (MCG-02-13-040).^[2] It is included in the Atlas of Peculiar Galaxies in the category galaxies with narrow filaments.

Arp 187
Arp 187 by legacy surveys. The small galaxy to the right is LEDA 980468
Observation data (J2000 epoch)
Constellation	Eridanus
Right ascension	5h 03m 53s [1]
Declination	−10° 14′ 51″ [1]
Redshift	12095 ± 45 km/s [1]
Apparent magnitude (V)	15.3 [1]
Characteristics
Type	Radio Galaxy [1]
Apparent size (V)	0.8 x 0.6 [1]
Other designations
PGC 16691 [1]

The galaxy has two prominent radio lobes, however the emission of its AGN in X-ray is low, and so is the thermal output of the AGN torus as observed in infrared, suggesting that it has been quenched. The detection of a narrow line region (with dimensions up to 10 kpc) with still active emission mean that the AGN was still active up to at least 10^4-5 years ago. In the nucleus of Arp 187 is predicted to lie a supermassive black hole (SMBH) with estimated mass around 6.7 × 10⁸ M_☉.^[3] Further observations of such a SMBH with a quenched AGN were published in 2019.^[4][5][6]