A project of the Dark Energy Survey collaboration

Posts tagged “structure formation

A Dark and Lonely Universe


It is early in the life of the universe. Cold clumps of inanimate matter are randomly distributed throughout the cosmos. In this randomness, some places have more matter, more stuff, than other places: some regions are denser than others.  Over time – millions and billions of years – the force of gravity causes these dense clumps to accumulate more and more matter, often taking from the already-emptier places. Essentially, when it comes to the growth of structure (from planets to galaxies and all the way up to the largest scales of the universe), the rich get richer, and the poor get poorer.

Fast forward to the present and we can see the results of this evolution.

Some galaxies were born in very rich environments; and while they started blue, today they are red.  These  galaxies, like some we’ve seen in earlier posts, become red because of all the massive stuff running around nearby them, disrupting the formation of their stars.  These red galaxies have come to live in clusters.

Other galaxies that don’t live near a lot of stuff don’t have that problem. They live in the field, and they can still give birth to stars, because other galaxies aren’t whizzing by them. These galaxies will remain blue for a long, long time as they drift along in their lonely, relatively empty piece of the universe.

NGC 1090 is one such field galaxy that lives 135 million light-years from Earth – equivalent to about 1.5 million billion round trips between Earth and the Moon.  It resides in the Cetus constellation and lies near a group of galaxies, M77.  However, NGC 1090 is not gravitationally bound to M77: it is completely unassociated; it is alone.

In the far, far, far future, dark energy may continue to pull objects farther and farther away from each other, and it may do so faster and faster – despite gravity’s attractive force.  Eventually, all galaxies could live in their own lonely regions of the universe.

If you’d like to track down the lonely NGC 1090 yourself, it sits on the celestial sphere at RA (02h 46m 33.9s) and DEC (-00° 14′ 49″)

Written by: Det. B. Nord [FNAL]

Image credit: Det. M. Murphy [FNAL],  Det. N. Kuropatkin [FNAL]