A research team at the University of Alabama in Huntsville (UAH) has discovered a lonely cloud bigger than the Milky Way in a “no man’s land” for galaxies. This scientifically mysterious cloud in Abell 1367 is full of hot gas with 10,000-10,000,000 degrees Kelvin (K).
Abell 1367 is also known as Leo Cluster, which contains around 70 galaxies and is located around 300 million light-years from Earth.
The team discovered the cloud in a cluster of galaxies where thousands of galaxies are bound together with tenuous hot gas. Despite being discovered in a cluster of galaxies, this lonely cloud is not associated with any galaxy. Hence, scientists say it is in a no-man’s land.
The discovery was made using the European Space Agency (ESA) X-ray Multi-Mirror Mission (XMM-Newton), Europe’s flagship X-ray telescope. The cloud was also observed with the European Southern Observatory Very Large Telescope/Multi-Unit Spectroscopic Explorer (VLT/MUSE) and Japan’s flagship optical telescope, Subaru.
Dr. Ming Sun, an associate professor of physics at UAH, said, “This is an exciting and also a surprising discovery. It demonstrates that new surprises are always out there in astronomy, as the oldest of the natural sciences. ESA agrees as our discovery was selected as an ESA image release, which has been very selective.”
According to scientists, the origin of the cloud must be a large, unknown galaxy in the cluster. They think that the gas in the cloud must be removed by the ram pressure of the hot gas in the cluster when the host galaxy is soaring in the hot gas with a velocity of 1,000-2,000 kilometers per second.
Dr. Sun said, “That’s about 50 times faster than the orbital speed of Earth around the sun. That level of force at work can rip the interstellar medium out of a galaxy. In this case, we found that the temperature of the cloud is consistent with having originated from a galaxy.”
“Once removed from the host galaxy, the cloud is initially cold and is evaporating in the hot intracluster medium, like ice melting in the summer.”
“It is estimated that this massive, mysterious cloud has survived for hundreds of millions of years after removal from its host galaxy.”
“This surprising longevity is poorly understood but may have something to do with the magnetic field in the cloud.”
- Chong Ge et al., An H α/X-ray orphan cloud as a signpost of intracluster medium clumping, Monthly Notices of the Royal Astronomical Society (2021). DOI: 10.1093/mnras/stab1569