Hubble Glimpses Galactic Gas Making a Getaway

A sideways spiral galaxy shines in this image from the NASA/ESA Hubble Space Telescope. Located approximately 60 million light years away in the constellation Virgo (Maid), NGC 4388 resides in the Virgo galaxy cluster. This enormous galaxy cluster contains more than a thousand members and is the closest large galaxy cluster to the Milky Way.

NGC 4388 appears to tilt at an extreme angle to our view, giving us an almost edge-on perspective of the galaxy. This perspective reveals a curious feature that was not visible in a previous Hubble image of this galaxy published in 2016: a plume of gas from the galaxy’s core, seen here escaping from the galaxy’s disk toward the lower right corner of the image. But where does this output come from and why does it glow?

The answer likely lies in the vast expanses of space that separate the Virgo Cluster galaxies. Although the space between galaxies appears empty, this space is occupied by hot swirls of gas called intracluster media. As NGC 4388 moves within the Virgo Cluster, it dives through the intra-cluster medium. Pressure from hot intra-cluster gas pushes gas away from NGC 4388’s disk, causing it to trail behind as NGC 4388 moves.

The source of the ionizing energy that makes this gas cloud glow is more uncertain. Researchers suspect that some of the energy comes from the center of the galaxy, where a supermassive black hole is spinning gas around itself to form a superheated disk. Blazing radiation from this disk could ionize the gas closest to the galaxy, while shock waves could be responsible for ionizing more distant gas filaments.

This image incorporates new data, including several additional wavelengths of light, which highlight the cloud of ionized gas. The image contains data from several observational programs aimed at illuminating galaxies with active black holes at their centers.

Media contact:

Claire Andreoli (claire.andreoli@nasa.gov)
from NASA Goddard Space Flight Center, Greenbelt, Maryland