by Chris Peterson » Sat Mar 09, 2013 2:39 pm
MargaritaMc wrote:I've been reading about the research relating to this image and I'd be grateful if someone could tell me what
z means in the following quotation
Spectroscopic measurements are obtained for 26 lensed images, including a distant galaxy at z = 5.4.
http://m.iopscience.iop.org/0004-637X/6 ... .text.html
It is the relativistic redshift, defined as the ratio of the observed wavelength to the emitted wavelength, minus 1. In this case, the researchers were looking at the emitted lyman-alpha line, which is at 121.6 nm (deep ultraviolet). This line was observed as being at 778.2 nm (near infrared), which is how the redshift was calculated.
This redshift can be plugged into equations based on the Hubble relationship to derive additional information: the light was emitted when the Universe was 1.1 billion years old, it took 12.6 billion years for the light to reach us, the object is now 26.6 billion light years away.
[quote="MargaritaMc"]I've been reading about the research relating to this image and I'd be grateful if someone could tell me what [size=150][b]z[/b][/size] means in the following quotation
[quote] Spectroscopic measurements are obtained for 26 lensed images, including a distant galaxy at [b]z = 5.4. [/b][/quote]
http://m.iopscience.iop.org/0004-637X/662/2/781/fulltext/?providedHtml=71146.text.html[/quote]
It is the relativistic redshift, defined as the ratio of the observed wavelength to the emitted wavelength, minus 1. In this case, the researchers were looking at the emitted lyman-alpha line, which is at 121.6 nm (deep ultraviolet). This line was observed as being at 778.2 nm (near infrared), which is how the redshift was calculated.
This redshift can be plugged into equations based on the Hubble relationship to derive additional information: the light was emitted when the Universe was 1.1 billion years old, it took 12.6 billion years for the light to reach us, the object is now 26.6 billion light years away.