A sideways spiral galaxy shines in this NASA/ESA Hubble Space Telescope image. NGC 4388 is located about 60 million light-years away in the constellation Virgo (the Virgin), and is a resident of the Virgo galaxy group. This massive group of galaxies has more than a thousand members and is the closest large galaxy group to the Milky Way.
NGC 4388 appears to be tilted at an extreme angle relative to our view, giving us a close-up view of the galaxy. This perspective reveals a strange feature that was not visible in the previous Hubble image of this galaxy released in 2016: a plume of gas from the galactic core, seen here rising from the galactic disk toward the lower right corner of the image. But where did this flow 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 wisps of gas called the intracluster medium. As NGC 4388 moves into the Virgo Cluster, it dives through the intracluster’s medium. The pressure from the gas within the hot cluster pushes gas away from within NGC 4388’s disk, causing it to fall behind as NGC 4388 moves.
The source of the ionizing energy causing this gas cloud to glow is uncertain. Researchers suspect that some of the energy comes from the galactic center, where a supermassive black hole spins gas around it into an extremely hot disk. The blazing radiation from this disk may ionize the gas closest to the galaxy, while shock waves may be responsible for ionizing the more distant filaments of gas.
This image includes new data, including several additional wavelengths of light, which shows the cloud of ionized gas. The image contains data from several observing programs aimed at shedding light on galaxies that contain active black holes at their centers.
Media communication:
Claire Andreoli (claire.andreoli@nasa.gov)
NASA Goddard Space Flight Center, Greenbelt, Maryland