"Red nugget" galaxies were hiding in plain sight

Sep 13, 2013
These images highlight the most massive of the newly discovered compact galaxies known as "red nuggets." The photo at left from the Sloan Digital Sky Survey shows that the galaxy is so small it appears starlike. The higher resolution photo at right from the Hubble Space Telescope reveals the object's true, extended shape. Credit: SDSS (left), NASA (right)

In 2005 the Hubble Space Telescope spotted unusually small galaxies densely packed with red stars in the distant, young universe. They were nicknamed "red nuggets," not only because they are small and red but also their existence challenged current theories of galaxy formation, making them precious in astronomers' eyes.

Since no "red nuggets" were seen nearby, astronomers wondered why they had disappeared over time. New research shows that they didn't disappear completely. In fact, they were simply hidden within the data of previous surveys.

Astronomers now realize these newfound compact could represent a missing link between distant "red nuggets" and nearby elliptical galaxies. They may light the evolutionary path to show how compact galaxies age over time and reveal whether they become the "seeds" for the monster ellipticals we see today.

To find them, Ivana Damjanov (Harvard-Smithsonian Center for Astrophysics) and her colleagues searched databases from the Sloan Digital Sky Survey. The "red nugget" galaxies are so small that they appear like stars in photographs from ground-based telescopes. However, their spectra give away their true nature.

"Looking for 'red nuggets' in the Sloan Digital Sky Survey was like panning a riverbed, washing away silt and mud to uncover bits of gold," says Damjanov.

By sifting through the Sloan data, the team dug up more than 600 "red nugget" candidates. They are located at distances of 2.5 to 5.7 billion light-years from Earth.

Damjanov then investigated the Hubble Space Telescope database to find photos of the patches of sky where those objects were located. Serendipitous images of nine targets confirmed that they are as compact as more distant "red nugget" galaxies. The most massive weigh up to 10 times more than the Milky Way, but are up to 10 times smaller than our galaxy. As a result, they're called compact, .

"We think there are more of these red nuggets, or compact galaxies, hidden in the universe, waiting to be discovered," says co-author Ho Seong Hwang (Smithsonian Astrophysical Observatory).

The team's future plans include using the Hubble Space Telescope to investigate more of these compact, massive galaxies to answer questions like: Where do they live, near other galaxies or in the intergalactic void? What is their internal structure?

Damjanov, a Menzel Fellow at the Harvard College Observatory, is lead author on the paper, which has been accepted for publication in The Astrophysical Journal Letters. Her co-authors are Igor Chilingarian, Ho Seong Hwang, and Margaret Geller (Smithsonian Astrophysical Observatory).

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

Explore further: The entropy of black holes

More information: arxiv.org/abs/1309.2948

Related Stories

Strange new 'species' of ultra-red galaxy discovered

Dec 01, 2011

In the distant reaches of the universe, almost 13 billion light-years from Earth, a strange species of galaxy lay hidden. Cloaked in dust and dimmed by the intervening distance, even the Hubble Space Telescope ...

Hubble catches the moment the lights went out

Feb 06, 2013

(Phys.org)—The further away you look, the further back in time you see. Astronomers use this fact to study the evolution of the Universe by looking at nearby and more distant galaxies and comparing their ...

Galaxies the way they were

Apr 03, 2013

(Phys.org) —Galaxies today come very roughly in two types: reddish, elliptically shaped collections of older stars, and bluer, spiral shaped objects dominated by young stars. The conventional wisdom is ...

Hubble sees stars fleeing a cosmic crash

Aug 19, 2013

(Phys.org) —Astronomical pictures sometimes deceive us with tricks of perspective. Right in the center of this image, two spiral galaxies appear to be suffering a spectacular collision, with a host of stars ...

Recommended for you

The entropy of black holes

Sep 12, 2014

Yesterday I talked about black hole thermodynamics, specifically how you can write the laws of thermodynamics as laws about black holes. Central to the idea of thermodynamics is the property of entropy, which c ...

Modified theory of dark matter

Sep 12, 2014

Dark matter is an aspect of the universe we still don't fully understand. We have lots of evidence pointing to its existence (as I outlined in a series of posts a while back), and the best evidence we have point ...

Gaia discovers its first supernova

Sep 12, 2014

(Phys.org) —While scanning the sky to measure the positions and movements of stars in our Galaxy, Gaia has discovered its first stellar explosion in another galaxy far, far away.

Astronomers unveil secrets of giant elliptical galaxies

Sep 12, 2014

New findings of how giant elliptical galaxies move have been discovered by an international team of astronomers using the newly installed Multi Unit Spectroscopic Explorer (MUSE) at the European Southern Observatory's (ESO) ...

Exploring the cosmic X-ray background

Sep 12, 2014

You are likely familiar with the cosmic microwave background. This background is a thermal remnant of the big bang. Because of the expansion of the universe, this remnant energy has a temperature of about ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

vidyunmaya
1 / 5 (6) Sep 13, 2013
Sub: useful data for cosmic Pot Energy Universe
I do expect 240 Cosmic pots around this zone- see Space cosmology vedas Interlinks-Books and Cosmic Vision of the Universe part 1, Dec 1999- scribd.
This preads around in multiplier- 2 and 2x5 .as Reflectors
http://www.scribd...Dec-1999
Urgelt
2.3 / 5 (3) Sep 14, 2013
Does this discovery affect estimates of visible matter in the universe, I wonder? Will Dark Matter estimates be constrained downward?