Daily Mail: Than 800 ‘ultra dark’ galaxies found

At this level, 1,000 galaxies in the Coma Cluster have been recognized.

Koda adds that more fainter galaxies can also be detected which are also embedded in significant huge amounts of this dark matter where these mysterious dark galaxies are obtained from observations from the 27 foot Subaru Telescope in Hawaii.

Following on a surprising find reported previous year, astronomers have now discovered nearly 1,000 dark matter-rich galaxies in the Coma Cluster.

“The findings suggests that these galaxies appear very diffuse and are very likely enveloped by something very massive, “said Jin Koda, PhD, principal investigator of the study and Associate Professor in the Department of Physics and Astronomy at Stony Brook University””.

Dark matter should have ripped apart these sparse galaxies due to extreme gravitational forces however scientists are baffled about their survival and longevity.

Last year, astronomers were surprised to detect 47 galaxies in the Coma Cluster that were made nearly entirely of dark matter. Yet despite their lack of stars, they still each span roughly the size of the Milky Way.

‘This discovery of dark galaxies may be the tip of the iceberg, ‘ said Dr Koda. These dim galaxies are arranged in a pattern similar to their brighter cousins in the Coma Cluster, and many of them are similar in size to our own Milky Way – but they have only a thousandth as many stars.

The component of visible matter, such as stars, is calculated to contribute only one per cent or less to the total mass of each galaxy.

This image shows a small region of the Coma Cluster that was surveyed by the Subaru Telescope.

Visible matter or stars in the case of the ultra dark galaxies is estimated at one percent of the mass of each of 854 galaxies. This, together with the Leo Cluster form the Coma Supercluster.

“These galaxies are dark because they lost the gas needed to create new stars during or after their largely unknown formation process, billions of years ago”, the researchers said.

Astronomers say it’s likely that the cluster environment played a key role in the loss of gas, which affects star formation within the galaxy.

The galaxies are more than 300 million light-years away from Earth. So the glue that holds seen matter collectively in a galaxy is one thing unseen. The construction of Thirty Meter Telescope (TMT) by an worldwide partnership of institutions, including the National Astronomical Observatory of Japan may well reveal the mystery of the dark galaxies in near future.

The National Astronomical Observatory of Japan has maintained all the info obtained with the Subaru Telescope since its very first mild observations sixteen years in the past in 1999. This new discovery is made possible thanks to the availability of abundant archival Subaru data. The preprint is available here.


p style=”text-align: center;”>Dark galaxies in the Coma Cluster


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