Abell 3744

Lore & Background

NGC 7016 is an elliptical galaxy located about 480 million light-years from Earth in the constellation Capricornus. It was discovered by American astronomer Francis Preserved Leavenworth on July 8, 1885. The galaxy has a calculated velocity of 11,046 km/s and an estimated diameter of about 160 thousand light-years. It hosts a supermassive black hole with an estimated mass of 1.4 billion M☉.

NGC 7016 is one of two prominent radio galaxies in Abell 3744, along with the double galaxy system NGC 7018. These two galaxies form a pair in the central region of the cluster. NGC 7016 is a Fanaroff-Riley type I radio galaxy with bent asymmetric jets. Lower-resolution radio data from the VLA show a very long, bent extension of the jet on the left side of the galaxy, forming a tendril structure. On the counterjet side there is extreme looping, forming a feature referred to as the 'swirl.'

It is thought that this swirl, which runs into an X-ray cavity produced by NGC 7018, is the result of the jet colliding with the radio plasma from NGC 7018 and as a result of an interaction with a wake of gas left by the motion of NGC 7018 and its companion galaxy through the cluster.

Reader's Guide

Abell 3744 is significant as the host cluster of two interacting radio galaxies, NGC 7016 and NGC 7018, whose jets and radio plasma produce distinctive structures. The swirl feature in NGC 7016's counterjet is interpreted as a result of collision with NGC 7018's radio plasma and interaction with a gas wake left by the motion of NGC 7018 and its companion. This provides a natural laboratory for studying jet–plasma interactions and the dynamics of radio galaxies within a cluster environment. The presence of a supermassive black hole of 1.4 billion solar masses in NGC 7016 further underscores the energetic processes at work. The cluster's legacy lies in its illustration of how galaxy motions and radio emissions shape the intracluster medium, as seen in the tendril and swirl structures observed with the VLA.