New Delhi: The Hubble Space Telescope has captured a spiral galaxy designated as NG 4388 at a distance of about 60 million lightyears in the constellation
of Virgo. The galaxy is a resident of the Virgo galaxy cluster that contains more than a thousand members, and is the closest large galaxy cluster to the Milky Way. NGC 4388 is edge-on and appears to tilt at an extreme angle from the point of view of the Earth. The perspective reveals a curious feature, a plume of gas being stripped away from the nucleus of the galaxy. The plume was not visible in a previous image of the same galaxy captured by Hubble in 2016.
The gas is being stripped away because of a process known as ram pressure stripping. The intracluster medium consists of hot gas heated to millions of degrees, that strips away the gas from the galaxies as they move through them. There is an entire category of galaxies with multiple trailing strands of gas rich in star formation known as jellyfish galaxies. Pressure from the hot intracluster gas strips away the material from the galaxy, leaving behind a trail. The source of the ionising energy itself is unknown.
Why is the intracluster medium super hot?
Researchers suspect that some of the energy comes from the cores of galaxies, that are usually occupied by supermassive black holes. The infalling material is tortured, resulting in a superheated disk. The energetic radiation from the accretion disks of black holes may ionise the gas closest to the galaxy, while shock waves might be responsible for ionising filaments of gas at farther distances from the galaxy. The plume was visible in the new image that incorporated new data and additional wavelengths of light. The same image is being used by several observing programmes that aim to illuminate galaxies using the supermassive black holes at their cores.
