The Visible Universe: "Seven Trillion Dwarfs and Billions of Undetected Galaxies" (Weekend Feature)
The European Space Agency’s Herschel space telescope has 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.
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 discovery added powerfully to knowledge about the timeline by which stars and then galaxies formed.
The Daily Galaxy via ESA and discovery.com
Credits: ESA/PEP Consortium and 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.
Comments
« Mars' Milestone: Most Advanced Planetary Robot Ever Designed Now Fully Operational | Main | "Biological Intelligence is a Fleeting Phase in the Evolution of the Universe" (Weekend Feature) »
p=hk sub 1,2,3,4,5,6....
Posted by: dr burke | February 09, 2013 at 02:33 PM
Once again I have to ask what this does to the total mass of the Universe!
Closed?
Posted by: Allan W Janssen | February 09, 2013 at 04:12 PM
So this mysterious cosmic fog just turned out to be distant, blurry galaxies. This is not surprising. Perhaps next we will find that the microwave background radiation is just more blurred and distant galaxies. It either goes on forever and ever, or there is eventually a Truman Show-wall at some point.
Posted by: Darth Vader's 3rd Cousin | February 09, 2013 at 05:29 PM
This seems to be an eye opener. We know so little , but increasingly the universe is seen to be much more vast than our knowledge from previous years.
Does this perhaps indicate that the statistical chances of intelligent *out there* are also greater ?
How to contact ** THEM** should be challenge for our technology.
Posted by: ahmed41 | February 10, 2013 at 12:19 AM
I am stunned! On the one side we learn that most of the universe consist of Dark Matter because the mass could not otherwise be accounted for. Now we learn that the universe seems to be 90% larger than thought at first. Is the dark matter mow still required in order to keep things together?
Posted by: Papix | February 10, 2013 at 12:47 PM
Now I really need to know where all of the matter came from.
Posted by: nervousjuice | February 10, 2013 at 05:57 PM
"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."
"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."
The birth of stars keeps going on until today. The galaxies actions & performances look the same between early Universe and current Universe. For that large number of galaxies, this is a strong indication that there is no early Universe at all. This situation gives sign that the Universe model is closer to "Cloud & rain model" rather than "The Big Bang theory."
Posted by: yash | February 11, 2013 at 05:17 AM
I understand that there are other ways of detecting dark matter, like it's contribution to the outer stars in a galaxy traveling faster that the inner ones and other methods also. However does this reduce the amount of dark matter, being that there is so much more matter discovered?
This also makes me ponder the theory of the multiverse. The theory states that if there are an infinite number of universes then statistically speaking there would have to be a world out there identical to ours with another me and another you. If we can now indirectly see 90% more of the universe than we could before, what if it doesn't stop there, which it most likely won't. Could the statistics be brought to encompass only this universe? Just in our own galaxy, we have found many worlds close to ours and we are so much still in the infancy of our search. There becomes a growing possibility that just in our own universe, we may yet discover ourselves. (Sorry, I just couldn't hold back from using an ironic metaphor.) I mean finding our doppelgangers. With the number of galaxies far exceeding trillions upon trillions, and even this number may be amazingly short, the question must remain open for debate.
Posted by: John Hannan | February 12, 2013 at 08:45 AM
And let's not forget about the universe beyond that is "visible".
Posted by: Kyuu | February 13, 2013 at 12:08 AM
How might this discovery affects measurements of cosmic age, I wonder? Does it mean the universe is older than believed?
Posted by: John Schneider | February 13, 2013 at 05:16 AM