Galaxy Clusters:

The most massive objects in the Universe

Such objects have been known since the late 18^th century [at the time, however, NOT for what they were], first observed by the royal astronomer to the court of Louis the fourteenth Charles Messier. These objects, later to be known as galaxies clusters, are the largest objects to be held together by their own gravity.

These objects are formed in much the same manner, as are star formations within individual galaxies; they are in fact, the first order below the very universe itself.

Because a cluster is a collection of galaxies of varying ages as well as types, it is a true representation of the universe as a whole. Notwithstanding, the very immense scales at which gravity interacts with such objects demonstrate a direct tie into the evolution of the universe itself.

It is through the study of these objects that astronomers and cosmologists hope to uncover the three most fundamental issues in their disciplines today: The composition, organization, and ultimate fate of the universe.

Thus, for more than 200 years, the search for the answers to these questions [as well as just what keeps these massive objects together] have added to the mystery. 1) Of why there is such uneven distribution of galaxies throughout the universe and, 2) The unknown nature of ‘dark matter’, believed to be the ‘force’ that holds these massive objects together.

Compelled by these mysteries, the number of ‘known’ clusters has increased to more than ten thousand. Observations made of the Virgo and Coma clusters had discovered huge amounts of gas threading through the galaxies themselves. Measured at more than 2.5 million degrees Celsius, they had found the first evidence of the existence of dark matter.

But the term ‘Cluster’ of galaxies itself is not entirely correct; what these objects are [i.e. their composition] is truly a ball of gas in which galaxies have become embedded, much like an insect in amber.

In order to better understand the SIZE of such objects, consider that a typical group of galaxies [which, by their definition is smaller] is fifty million times as massive as earth’s sun, and has a temperature on the order of ten million degree Celsius. Now a ‘cluster’ of galaxies weighs some one thousand trillion times the mass of earth's sun and registers at a temperature of seventy five million degrees Celsius. And the heaviest known cluster to exist is five times as massive and more than three times as hot!

This office will continue to investigate such phenomenon in our on going search for the origins of the universe.