The Absolute Cosmos: Scientists say Milky Way galaxy has a clumpy halo

Our home galaxy- Milky Way is enveloped by a clumpy halo of hot gases, which could be hiding mysterious missing matter. This halo is continuously getting supply of material ejected from the birth and death of the stars.

This heated halo of gases is known as circumgalactic medium or CGM and it nourished the Milky Way during its formation about ten billion years ago.

According to scientists this halo could be holding the basic matter inside it, which has gone missing since the birth of the universe.

The new research is based on observations conducted by HaloSat — a NASA (Astrophysics Division) funded minisatellite, built and designed by the University of Iowa.

The minisatellite was launched in May 2018 from the International Space Station (ISS).

HaloSat primarily observes the X-rays emitted by the circumgalactic medium. Based on the intensity of these X-rays, scientists say that CGM is disk like in shape.

Every galaxy has its own circumgalactic medium. Examining these regions is critical as they hold the key to understanding the formation and evolution of galaxies and universe.

According to Philip Kaaret (professor in the Iowa Department of Physics and Astronomy)- the regions of CGM where Milky Way is forming stars more aggressively have more X-ray emissions.

This indicates that CGM is related to star formation and we are likely observing the gas that fell into the Milky Way earlier. The gas helped in making of stars and now it is getting recycled into the CGM.

HaloSat was launched to hunt for atomic remnants known as baryonic matter. It is suspected that baryonic matter is missing since the birth of the universe-almost fourteen billion years ago.

Since its launch in 2018, HaloSat is continuously monitoring Milky Way’s circumgalactic medium for possible evidence of baryonic matter.

In order to look for this possible evidence, scientists wanted to determine if the halo is huge and extended, possibly many times the size of Milky Way- in such case there would be sufficient atoms to contain the missing baryonic matter. But in case if halo is mostly made up of recycled material, it would be thin and puffy, and probably it is not the home for the missing matter.

This new research is uncertain as HaloSat alone is not capable of establishing whether the halo is extended or not.

Further, scientists plan to combine the data from HaloSat with other X-ray observatories. This could solve the mystery behind the missing baryonic matter.

The Cosmos is all that is or ever was or ever will be…