The Unseen Universe --"Billions of Undetected Galaxies" (Today's Most Popular)
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October 31, 2012

The Unseen Universe --"Billions of Undetected Galaxies" (Today's Most Popular)

 

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The European Space Agency’s Herschel space telescope discovered that previously unseen distant galaxies are responsible for a cosmic fog of infrared radiation. The galaxies are some of the faintest and furthest objects seen by Herschel, and opened a new window on the birth of stars in the early Universe. 

Astronomers estimate that their are billions and billions of galaxies in the observable universe (as well as some seven trillion dwarf galaxies) . Here's how astronomers breakout  the visible universe within 14 billion light years:

Superclusters in the visible universe = 10 million

Galaxy groups in the visible universe = 25 billion

Large galaxies in the visible universe = 350 billion

Dwarf galaxies in the visible universe = 7 trillion

Stars in the visible universe = 30 billion trillion  (3x10²²)

Astronomers realized this past year that they may have underestimated the number of galaxies in some parts of the universe by as much as 90 percent, according to a study in 2011 by Matthew Hayes of the University of Geneva's observatory, who led the investigation using the world's most advanced optical instrument -- Europe's Very Large Telescope (VLT) in Chile, which has four 8.2-meter (26.65-feet) behemoths. They turned two of the giants towards a well-studied area of deep space called the GOODS-South field.

In the case of very distant, old galaxies, the telltale light may not reach Earth as it is blocked by interstellar clouds of dust and gas -- and, as a result, these galaxies are missed by the map-makers.

"Astronomers always knew they were missing some fraction of the galaxies... but for the first time we now have a measurement. The number of missed galaxies is substantial," said Matthew Hayes of the University of Geneva's observatory, who led the investigation.

The team carried out two sets of observations in the same region, hunting for light emitted by galaxies born 10 billion years ago.The first looked for so-called Lyman-alpha light, the classic telltale used to compile cosmic maps, named after its U.S. discoverer, Theodore Lyman. Lyman-alpha is energy released by excited hydrogen atoms. The second observation used a special camera called HAWK-1 to look for a signature emitted at a different wavelength, also by glowing hydrogen, which is known as the hydrogen-alpha (or H-alpha) line.

The second sweep yielded a whole bagful of light sources that had not been spotted using the Lyman-alpha technique. They include some of the faintest galaxies ever found, forged at a time when the universe was just a child.

The astronomers conclude that Lyman-alpha surveys may only spot just a tiny number of the total light emitted from far galaxies. Astonishingly, as many as 90 percent of such distant galaxies may go unseen in these exercises.

"If there are 10 galaxies seen, there could be a hundred there, unseen" said Hayes.

The image at the top of the page shows A dwarf galaxy found by MIT's Dr. Simona Vegetti and colleagues --a satellite of an elliptical galaxy almost 10 billion light-years away from Earth. The team detected it by studying how the massive elliptical galaxy, called JVAS B1938+666, serves as a gravitational lens for light from an even more distant galaxy directly behind it. Their discovery was published in the Jan. 18 online edition of the journal Nature.

The Daily Galaxy via ESA and discovery.com

Credits: ESA/PEP Consortium and 

Comments

Really? No doubt this was quite the obvious conclusion. Sometimes i think these "scientists" are quite narrow focused and cannot see the bigger picture.

"It's amazing, the bigger telescope we build, the farther we can see...." Unbelievable... (shakes head)

Wow! What else is to be said?

I wonder what kind of physics is at work in a higher dimension?
Not quantum or Newtonian, but what would you call it?

Dimensional physics? Definitely, higher math.

These "scientist" as you so woefully try to denigrate have pushed our knowledge of the unverse to never before acheived levels of clarity and yes more and deeper questions. but perhaps you don't enjoy a challenge for the human mind towards deeper understanding...i see the beauty of the universe on a deeper level due to these "scientist" and their dedication to their work, which by the benifits all of humnaity.

Ted Z: I think your denigration of the scientists as "scientists" is quite insulting. What are you trying to say or prove here?

Better to argue your point of view rather than this sort of sarcasm- more heat than light!

I wonder how this will change the total estimates of the mass
of the universe. i.e. Do we still need dark matter or dark energy to explain things. I think the universe is far older and
much larger than ever dreamed. Wonderful science....expanding
our knowledge of the size and mass of the universe is paramount.

And all of this popped out of a singularity?
When will the Astrophysical community give the Steady State concept another look?

If they can get something like the mass of the universe wrong by a factor of 10 ................ then what other surprises are we in store for?

And all these billion trillion stars and galaxies were compressed to a table-tennis-ball entity when Big Bang happend, really amazing!

Ted Z,

Just because scientists may have underestimated the total number of galaxies by some 90% doesn't mean they are narrow focused. Astronomers can only count what they can observe with the technology on hand. Before the invention of the microscope no one really knew the existence of microorganisms right?

Wow! With that many stars out there, how many planets could there be? 300 billion trillion or more? Among those there must be a few which harbor advanced civilizations. After that, the diversity of lower life forms is probably close to endless. Things we couldn't even imagine in our wildest and strangest science fiction stories. God knows what we'll find if we ever learn to travel to distant stars and then, perhaps someday, on to distant galaxies.


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