Hidden star power revealed: Astronomers find ancient galaxy cluster still producing stars

Aug 18, 2010
This sensitive exposure captures galaxies that are relatively local along side some that date back almost 10 billion years, soon after the Big Bang. The most distant galaxies stand out clearly in the infrared, rendered here in green and red. Image credit: NASA/JPL-Caltech/Texas A&M

(PhysOrg.com) -- Much like quiet, middle-aged baby boomers peacefully residing in some of the world's largest cities, families of some galaxies also have a hidden wild youth that they only now are revealing for the first time, according to research by astronomers at Texas A&M University.

In ongoing observations of one of the universe's earliest, most distant cluster of galaxies using NASA's Spitzer Space Telescope, an international team of researchers led by Texas A&M's Dr. Kim-Vy Tran has discovered that a significant fraction of those ancient galaxies are still actively forming stars.

Tran, an assistant professor in the Texas A&M Department of Physics and Astronomy and member of the George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, and her team have spent the past four months analyzing images taken from the Multiband Imaging Photometer for Spitzer (MIPS), essentially looking back in time nearly 10 billion years at a high red-shift cluster known as CLG J02182-05102. Mere months after first discovering the cluster and the fact that it is shockingly "modern" in its appearance and size despite being observed just 4 billion years after the Big Bang, the Texas A&M-led team was able to determine that the galaxy cluster produces hundreds to thousands of new stars every year — a far higher birthrate than what is present in nearby galaxies.

What is particularly striking, according to Tran, is the fact that the stellar birthrate is higher in the cluster's center than at the cluster's edges — the exact opposite of what happens in our local portion of the universe, where the cores of are known to be galactic graveyards full of massive elliptical galaxies composed of old stars.

"A well-established hallmark of galaxy evolution in action is how the fraction of star-forming galaxies decreases with increasing galaxy density," explains Tran, lead author of the team's study which appears in The Astrophysical Journal Letters . "In other words, there are more star-forming galaxies in the field than in the crowded cores of galaxy clusters. However, in our cluster, we find many galaxies with star-formation rates comparable to their cousins in the lower-density field environment."

Exactly why this star power increases as galaxies become more crowded remains a mystery. Tran thinks the densely-populated surroundings could lead to galaxies triggering activity in one another, or that all galaxies were extremely active when the universe was young.

The group's discovery holds potentially compelling implications that could ultimately reveal more about how such massive galaxies form. Observations of nearby galaxy clusters confirm that they are made of stars that are at least 8 to 10 billion years old, which means that CLG J02182-05102 is nearing the end of its hyperactive star-building period.

Now that they have pinpointed the epoch when galaxy clusters are making the last of their stars, can focus on understanding why massive assemblies of galaxies transition from very active to passive. Identifying how long it takes for galaxies in clusters to build up their stellar mass as well as the time at which they stop provides strong constraints for how these massive galaxies form.

"Our study shows that by looking farther into the distant universe, we have revealed the missing link between the active galaxies and the quiescent behemoths that live in the local universe," Tran adds. "Our discovery indicates that future studies of galaxy clusters in this red-shift range should be particularly fruitful for understanding how these massive galaxies form as a function of their environment."

Tran's team includes fellow Texas A&M astronomer Dr. Casey Papovich, who first identified the galaxy cluster CLG J02182-05102 in May. The collection of roughly 60 galaxies is observed just 4 billion years after the Big Bang, making it the earliest cluster of galaxies ever detected. However, the team was struck not by its age, but by its astoundingly modern appearance — a huge, red collection of galaxies typical in only local clusters.

The fact that Tran's team was able to see these active galaxies so far back in time (Tran likens their find to discovering that her mild-mannered grandparent had lived a fast and furious youth) is only the preface to what they expect eventually to learn about these clusters. Tran will continue to lead an international collaboration with Papovich and their postdoctoral researchers to examine these clusters more thoroughly and hopefully to understand why they are still so energetic.

"We will analyze new observations scheduled to be taken with the Hubble Space Telescope and Herschel Space Telescope to study these galaxies more carefully to understand why they are so active," Tran adds. "We will also start looking at several more distant galaxy clusters to see if we find similar behavior."

Explore further: Quest for extraterrestrial life not over, experts say

More information: The team's findings are detailed in their paper, "Reversal of Fortune: Confirmation of an Increasing Star Formation-Density Relation in a Cluster at z=1.62," available online at iopscience.iop.org/2041-8205/719/2/L126/

Provided by Texas A&M University

4.7 /5 (15 votes)

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TegiriNenashi
1 / 5 (1) Aug 18, 2010
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HarshMistress
3 / 5 (2) Aug 18, 2010
Kim-Vy Tran has discovered that a significant fraction of those ancient galaxies are still actively forming stars.

Pardon my stupidity, but I don't understand how can the scientists know that galaxies are *still* active (at this time and day) when the observation data is 10 bill. years old. My understanding is that the observed galaxies were active 10 bill. years ago, not today.
MrPressure
1 / 5 (5) Aug 19, 2010
Let´s think with a thought!

Let´s think about the giant energy concentarions of our galaxies centres(they are also called as huge black holes) and how they once flaped from one size larger energy concentarions that locate really far outside the visible universe!

This way they were already far away from each other and the space did not have to expand “inflantionally”.

With time the stars were born out of the energy waves that the giant energy concentrations of the galaxy centres radiate and which have the nature of the atoms. At the same time as the substance and the time of this new substance were born, this energy moved in a space that already excisted and which does not expand or curve!

Our time is extremely slow in relation to the speed of movement in which the substance / energy of the visible universe move in a space that already excists.

And when the stars began to radiate their energy, the energy started to move as particules in an area between the galaxies ect.

Now let´s
MrPressure
1 / 5 (5) Aug 19, 2010
Now let´s think that energy of the visible universe would begin to meet corresponding galaxies
in a 90 degree angle.

Naturally towards those galaxies would hit energy coming from the stars of the visible universe.
So this energy did not once move in an area between the galaxy “seeds”.

In an area between the particules radiating from the stars does not move energy which could hit the particules passing the star!

In an area whre the particules come towards the star this energy moves and it hits towards the photons passing the star and this is how the light bends!

Energy concentarions orbit of movement changes, accelerates or slows down only when the energy of an energy concentration alters faster than normally in the other side than in the other into a less dense energy .
MrPressure
1.2 / 5 (5) Aug 19, 2010
Let´s think about a ship that is one light second long and moves throuhg the whole visible universe nearly in a speed of light. The time of the ship is so slow that during that time only one second of the ships time passes by!

How many journeys of the ships length does the ship move in one ships second?

The oldest light of the visible universe has moved from the farest destination of the visible universe
towards us and at the same time all the material / energy of the visible universe (also that oldest light) has been able to move during one of our seconds in a similar way as the ship that moved in one ships second truly many times the same journey as its own length is!

Our time is simply so unthinkably slow in relation to that velocity in which all the material / energy of the visible universe moves in a space that allready excists.

.
MrPressure
1 / 5 (5) Aug 19, 2010
And of course the light that moves into a direction in which all the energy / material of the visible universe pushes itself, moves with a fastest speed into that same direction, may it be a hunch faster!

So, you never can move faster that light, you know.

Google: Etimespace videos

Thanks
frajo
5 / 5 (2) Aug 19, 2010
Kim-Vy Tran has discovered that a significant fraction of those ancient galaxies are still actively forming stars.

Pardon my stupidity, but I don't understand how can the scientists know that galaxies are *still* active (at this time and day) when the observation data is 10 bill. years old. My understanding is that the observed galaxies were active 10 bill. years ago, not today.
Your understanding is correct.
Sometimes articles about science are not as precise as scientific articles.
HarshMistress
not rated yet Aug 19, 2010
Thanks, frajo.

I don't know if you read "Solaris". To prove (or disprove) his own sanity, Chris did some astronomic calculations and then compaired the results against those done by the space station's computer. That's what I needed this time.
frajo
not rated yet Aug 19, 2010
"Solaris". To prove (or disprove) his own sanity, Chris did some astronomic calculations and then compaired the results against those done by the space station's computer.
Thanks for the reminder; I should read the book again.
In a certain way, Lem's 1961 novel was naive, however, because it didn't anticipate the fallibility of computers. As was demonstrated in the 1968 milestone movie "2001: A Space Odyssey".

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