This is very cool: astronomers have spotted extremely distant, extremely bright galaxies. The newly released observations are amazing for many reasons; let me walk you through this.
The top of the three images is from a telescope that looks at light that has a wavelength in the millimeter range, so you can think of it as very far-infrared. That huge blob is a bright source of this light, but what is it? That’s a problem– it’s hard to identify what type of object it is from such a low-resolution image.
So then you look at in in the mid-infrared using the Spitzer Space Telescope Smithsonian’s Submillimeter Array, and you get the middle image. Better! Although still a little blobby, the position of the source can be nailed down with much higher precision. But still, what is it?
Well, why not take a Hubble image? That’s the bottom one. The only source at the position of the other two images is a faint little dot. By examining the way the object emits light at different wavelengths (basically thinking of these images as very low resolution spectra), the distance to the object is determined to be at least 11.5 billion light years. There is a small chance it is much closer and a different kind of object, but given its characteristics this seems unlikely.
This object is one of six found in this way. These objects are very young galaxies experiencing heavy starbirth pangs. The young stars crank out dust, which blocks the visible light, but makes them very bright in the infrared. In fact, most of the objects found this way have no visible emission detected; the one shown here is one that happens to be visible… barely. It’s at a (red) magnitude of about 26, meaning that the faintest star you can see with your unaided eye is still 100,000,000 times brighter than that galaxy! That’s faint.
These galaxies are called ULIRGs, for Ultra Luminous InfraRed Galaxies. They are so far away that we are seeing them as they were just 2 billion years after the Universe itself formed, which is pretty young. Models of how stars and galaxies form have a hard time getting them to be so dusty so early, which means that somewhere in these models there is something missing that the Universe is doing. What is different about the young Universe that we’re not seeing? How do we improve the models so that we can fit what we see, and then test them using further observations?
One idea is that the galaxies are undergoing collisions with other galaxies. This generally triggers vast amounts of star formation, so that could explain why these guys are so madly cranking out stars. It also means that a lot of gas and dust from the collision will be funneled into these galaxies’ central black holes, which in turn means that in a few million or billion years, these galaxies will turn into quasars: objects with incredibly bright central regions as the supermassive black holes there gobble down all that material.
So keep your eyes on these guys. If you can wait an eon or two, they’ll get even more interesting.
Here is the scientific journal paper on these objects for those who are interested.
August 9th, 2007 at 12:47 pm
WOW, 11.5 billion light years. Not only is that the very edge of the observable universe but that thing dates back a few billion years after the big bang. Talk about red shift, the fact that they can detect stuff like this is very cool.
August 9th, 2007 at 12:51 pm
*Sorry for the double post.
Stuff like this makes the biblical god seem so small and petty by comparison. The absolute majesty of the universe is so much more beautiful than any of the tiny mythologies of man.
August 9th, 2007 at 12:54 pm
I hate to go low brow, but it looks like a breast close up.
OK, I lied.
I don’t hate to go low brow.
>>> The absolute majesty of the universe is so
>>> much more beautiful than any of the tiny
>>> mythologies of man.
Hey, don’t hog the bong, man! Pass that over!
August 9th, 2007 at 1:03 pm
If the farther you look out into the universe, the farther back you are looking in time, aren’t you also looking at a universe that was much smaller too? If so, would objects and distances between objects at that time be more compacted together? How would they apear to us now; compacted, or stretched out due to the subsequent expansion?
August 9th, 2007 at 1:23 pm
I was wondering if you (or someone else) could illuminate something for me… for something so distant (I doubt they have any candles out that far), how do you tell how far away it is by looking at the wavelengths?
August 9th, 2007 at 1:40 pm
Speaking of galaxies, have you caught this week’s episode of the History Channel show “The Universe”? It is on galaxies, but it goes over so many different subjects that at best each one gets maybe 30 seconds to 2 minutes, so nothing can really get covered.
I’ve noticed the same pattern with other shows in the series.
How ’bout the rest of you?
August 9th, 2007 at 2:28 pm
Slavdude, agreed I wish they had an entire channel dedicated to documentaries about space, physics, and (pardone me for repeating myself) the majesty of the universe.
August 9th, 2007 at 2:42 pm
With better optics or dishes, could we conceivably
go back to the “bang”? Then what? What is beyond
the big bang?
Possibly a mega-universe where every star is
relatively close together? Similar to the early Earth
that was one huge continent?
August 9th, 2007 at 2:43 pm
1>the distance to the object is determined to be at least 11.5 billion light years.
2>They are so far away that we are seeing them as they were just 2 billion years after the Universe itself formed,
I am confused with the above inference of 2 from 1 and the following write-up. Please clarify:
From wikipedia: (http://en.wikipedia.org/wiki/Observable_universe)
“The age of the universe is about 13.7 billion years. While it is commonly understood that nothing travels faster than light, it is a common misconception that the radius of the observable universe must therefore amount to only 13.7 billion light-years. This reasoning might make sense if we lived in the flat spacetime of special relativity, but in the real universe spacetime (not space!) is highly curved at cosmological scales, and light does not move rectilinearly. Distances obtained as the speed of light times a cosmological time interval have no direct physical significance.”
August 9th, 2007 at 3:20 pm
Oh Phil! Why didn’t you mention the name of the “telescope that looks at light that has a wavelength in the millimeter range” but give the names of the other two telescopes? The Submillimeter Array feels left out!
(I only say this because I know two of the people on the paper who work [well, one of them doesn't anymore] at the SMA…)
August 9th, 2007 at 5:50 pm
Wonderful article. Small nitpick: the press release says that the top picture was taken by the azTEC, the middle one by the Submillimeter Array (not by Spitzer), and the bottom one by the Hubble. This is a beautiful example of the value of viewing the same object in different parts of the spectrum.
August 10th, 2007 at 9:51 am
I’m glad to see your blog readers are quick on the uptake. Indeed, the top image was taken by AzTEC, a submillimeter/millimeter instrument, while the middle image was taken by the Submillimeter Array. Spitzer images were taken as well and are shown in the journal paper, but were not used for this press release.
The Submillimeter Array is anxious for all the recognition they can get, so we’d appreciate a correction!
August 10th, 2007 at 10:26 am
“…could we conceivably go back to the “bangâ€? Then what? What is beyond the big bang?”
Don’t you read Green Lantern? It’s…A GIANT HAND!!
But seriously, I like this post so much I’m going to name my next infant daughter “Ulirg”.
August 10th, 2007 at 12:35 pm
D’oh! I fixed the middle caption. Sorry ’bout that.
August 10th, 2007 at 12:41 pm
Abhay,
Disclaimer: I am not an “expert”. I trust that any misstatement I make will be corrected by someone more knowledgeable. Here is my understanding of the point you raise.
Your thinking is correct – the common astronomcal parlance can mislead. When they say an object is 11.5 billion light years away, they don’t mean that the distance from the Earth’s current location to the object’s current location is 11.5 billion light years or that the distance from Earth to the object at the time the light left the object was 11.5 billion light years. They mean that the light left the object 11.5 billion years before it arrived at our telescope.
When the light left the object, the distance between the Earth and the object was a lot less than 11.5 billion light years. To get here, however, the light had to travel through an expanding universe, so it took a long time (11.5 billion years), since the longer the light travelled, the further it had to go. Again, because of the rapid expansion of the universe, the object is now a lot farther than 11.5 billion light years away from us.
August 10th, 2007 at 1:12 pm
Edward Cohenon asks, “With better optics or dishes, could we conceivably go back to the ‘bang’?” No, the furthest back that anything can be seen is about 400,000 years after the Big Bang. Before that the Universe was opaque to any kind of electromagnetic radiation. Look up “cosmic microwave background radiation” for details.