Images of the early Universe - How?

[rowan999]

Hi, I often see references to images captured from observatories which are 'looking back in time' billions of years, or even to the beginnings of the universe itself.<br />I am just wondering how these images are obtained. I assume the light, X-rays, etc are still travelling through the universe from those events and finally reach our shores at this, much later, point in time. Is this correct? If so, it doesn't seem to completely explain it for me.<br />Here is an aticle describing how the Chandra Observatory has revealed 12 billion year old images from when the universe was very young ::<br /><br />http://www.abc.net.au/science/news/stories/s259759.htm<br /><br />It describes using a 500,000 second long exposure and including imagery from the Hubble as well.<br /><br />What is being captured in a general sense?<br />How is any sort of data emmission from the beginning of the universe still traveling around inside of it?<br />Or is it from the other side of the universe coming back across? Or is that completely ridiculous? <img src="/images/icons/smile.gif" /><br />How can any sort of meaningful view be put together, wouldn't vast amounts of the information have been blocked by various instersteller bodies over the course of the journey?<br />Are there special regions of the 'sky' where these images can only be collected?<br />Is the massive receiving power of these telescopes and methods required to sift out the information because it is so weak?<br />How can this information be explicitly extracted from the spectrum of other information that must also be falling to earth from the same areas (ie: 5 billion year old signals, 1 billion, 1 million, yesterdays...)?<br /><br />Is there some kind of simple idea behind this science, or is it actually very complicated?<br /><br /><br />Your input is appreciated, or if there is a good site somewhere with the info I'm after, please let me know.<br />(I did some sea

 

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<font color="yellow">I am just wondering how these images are obtained. I assume the light, X-rays, etc are still travelling through the universe from those events and finally reach our shores at this, much later, point in time. Is this correct?</font><br /><br />Yes. The point is that farther away = farther back in time. If you look at something that is 12 billion light years away, then you're looking at what it was like 12 billion years ago since it took like 12 billion years to reach us.<br /><br /><font color="yellow">What is being captured in a general sense? </font><br />Chandra observes the number and energy of x-rays coming from the direction it's pointed at when imaging. Figuring out what is producing these x-rays requires inference and modeling. If you correlate the x-rays with a hubble image (which measures the amount of light (uv, visible and near-ir depending on the filter)) you can see if the x-rays are coming from individual galaxies, clusters of galaxies, or active foreground stars. If you see copious amounts of x-rays coming from an individual galaxy people usually attribute it to active galactic nuclei (big black holes in the center of the galaxy eating a lot of gas that gets super-heated as it falls into the black hole and releases x-rays). If the x-rays come from the region between galaxies in clusters then it's usually attributed to hot gas in the cluster. Again though, it's good to keep in mind that these conclusions about what is producing the x-rays are based on inference, all that is actually observed are the x-rays, their energies, and the direction on the sky that they're coming from.<br /><br /><font color="yellow">How is any sort of data emmission from the beginning of the universe still traveling around inside of it? </font><br /><br />Basically, the universe really is rather empty and transparent. This applies to your other questions as well. You can see galaxies that we infer from their redshifts to be <div class="Discussion_UserSignature"> </div>

 

[rowan999]

Thanks for your reply. You're responses pretty much cleared up most of the issues I had.<br />I guess the thing was how that early information is still around, but the universe is so big and the speed of light so comparably 'slow', that the conclusions aren't immediately very intutive.<br /><br />Cheers