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New Discoveries About the Early Galaxies of the Universe

050310102001 "If you could visit a planet in one of these galaxies, the sky would be a crazy place, with tons of bright stars, and fairly frequent supernova explosions."

Ranga-Ram Chary --NASA's Spitzer Science Center

Astronomers have discovered that galaxies in the distant, early universe continuously ingested their star-making fuel over long periods of time. This goes against previous theories that the galaxies devoured their fuel in quick bursts after run-ins with other galaxies.

"Our study shows the merging of massive galaxies was not the dominant method of galaxy growth in the distant universe," said Ranga-Ram Chary of NASA's Spitzer Science Center at the California Institute of Technology in Pasadena, Calif. "We're finding this type of galactic cannibalism was rare. Instead, we are seeing evidence for a mechanism of galaxy growth in which a typical galaxy fed itself through a steady stream of gas, making stars at a much faster rate than previously thought."

Chary is the principal investigator of the research, appearing in the Aug. 1 issue of the Astrophysical Journal. According to his findings, these grazing galaxies fed steadily over periods of hundreds of millions of years and created an unusual amount of plump stars, up to 100 times the mass of our sun.

"This is the first time that we have identified galaxies that supersized themselves by grazing," said Hyunjin Shim, also of the Spitzer Science Center and lead author of the paper. "They have many more massive stars than our Milky Way galaxy."

Galaxies like our Milky Way are giant collections of stars, gas and dust. They grow in size by feeding off gas and converting it to new stars. A long-standing question in astronomy is: Where did distant galaxies that formed billions of years ago acquire this stellar fuel? The most favored theory was that galaxies grew by merging with other galaxies, feeding off gas stirred up in the collisions.

Chary and his team addressed this question by using Spitzer to survey more than 70 remote galaxies that existed 1 to 2 billion years after the Big Bang (our universe is approximately 13.7 billion years old). To their surprise, these galaxies were blazing with what is called H alpha, which is radiation from hydrogen gas that has been hit with ultraviolet light from stars. High levels of H alpha indicate stars are forming vigorously. Seventy percent of the surveyed galaxies show strong signs of H alpha. By contrast, only 0.1 percent of galaxies in our local universe possess this signature.

Previous studies using ultraviolet-light telescopes found about six times less star formation than Spitzer, which sees infrared light. Scientists think this may be due to large amounts of obscuring dust, through which infrared light can sneak. Spitzer opened a new window onto the galaxies by taking very long-exposure infrared images of a patch of sky called the GOODS fields, for Great Observatories Origins Deep Survey.

Further analyses showed that these galaxies furiously formed stars up to 100 times faster than the current star-formation rate of our Milky Way. What's more, the star formation took place over a long period of time, hundreds of millions of years. This tells astronomers that the galaxies did not grow due to mergers, or collisions, which happen on shorter timescales. While such smash-ups are common in the universe -- for example, our Milky Way will merge with the Andromeda galaxy in about 5 billion years -- the new study shows that large mergers were not the main cause of galaxy growth. Instead, the results show that distant, giant galaxies bulked up by feeding off a steady supply of gas that probably streamed in from filaments of dark matter.


The Daily Galaxy via NASA/Spitzer

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Comments

Why anyone with a sound mind still believe that SMBH at the center of every galaxy is its engine? It looks more like white hole or Central Star is far more accurate concept. I see the Sun every day and black hole doesn't power it. So why the galaxy's center should be different?

@Roman

It has been proved beyond doubt that almost all Galaxies harbour SMBHs at their centres. A "Central Star" as you have pointed out would not be able to support its own weight - since it would be too massive to do so - the result would be a black hole.

The super-sized growth means that the black holes in the CDFS are less extreme versions of quasars -- very luminous, rare objects powered by material falling onto supermassive black holes.

Looks like a pretty cool place to go chill
www.anon-web-toolz.tk

2GodParticle:

Wrong! It has not been proven that a black hole exist at all anywhere in the Universe let alone the super massive ones!
Why stuff is being thrown out from the center of a galaxy, not the other way around as the theory says? Do a little homework about what the raw data shows us.

Hey dumbass, simple, if there was a supermassive sun, rather than a supermassive black hole, DON'T YOU THINK WE WOULD SEE IT? Our own sun is bright as shit, and we see suns from systems millions of light years away, you honestly think that we wouldn't notice a Sun bigger than a galaxy at the core of the milky way? SMBH's have DEFINITELY been found at the center's of nearly EVERY galaxy we are aware of, way to be current bud.

@Roman,
Get a text book, you seem to have a weak grasp of physics. Simply said, stars have a size limit. Over that limit, they burn the fuel around them fast, resulting in supergiants. Supergiants are prelude to black holes via supernova. SMBH does have strong evidence, you need to do your homework. And, stars/planets/smaller celestial objects get flung into and out of galaxies.

Don't you know black hole are physically impossible, because they involve infinities which are purely mathematical concepts? OK, whatever it is, it's not black hole of "Sun" of some sort. We don't have enough data yet.

@ roman. its as simple as this. if you believe in gravity, and you believe in light, then you have to believe black holes are real. whats that old equation... E=MC squared... if you can get nothing else out of it, get this part, that light can go really really really fast, and matter can get really really dense. gravitational lensing is a very nice demonstration. also take a gander at the stars motion in the center of our galaxy. these are zipping around in their orbits so fast its not even funny. and what is it, that little thing...oh yeah, we orbit our star, not the other way around. something that cant be seen, is massive enough for stars to be in orbit of it, i don't know what else you would call other than a black hole. im drunk so excuse me if i screwed this one up, im off to find a naked singularity :D

*Looks down at comments.*
My goodness...what has Digg become?

Wow, no kidding.
Eventually all the human users will have gone over to reddit, and all that will be left are articles automatically submitted and commented on by machines, kind of like if they kept the matrix going after the last human had died.

World leaders gathering in Italy for a summit this week will be able to don parkas designed by Belstaff, the maker of the movie star's jackets if things get stormy.

HEY DREAD!! Couldn't have put it better myself. Pop a cold one for me, too, will ya?

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