Water from a long, long time ago

Earliest radio fingerprint of water in a distant galaxy
Earliest radio fingerprint of water in a distant galaxy

Using a giant radio telescope in Germany, water molecules have been detected in a galaxy about 11 billion light-years away. This means that there was already detectable amounts of water in our universe when it was only less than four billion years old, which also means that there must have already been enough supernovas by then to create plenty of oxygen.

Like many other cosmological objects from the far past, the detection was aided thanks to the gravitational lensing provided by a foreground galaxy. Detection was also aided by the fact that the water effectively acted as a gigantic laser powered by the supermassive black hole in the center of the galaxy, except that radio waves are emitted instead of visible light.

6 Replies to “Water from a long, long time ago”

    1. You probably already know about certain frequencies of microwaves resonating with water molecules and heating them (although microwave ovens don't actually work by resonance), and this is just the converse. The water molecules are excited to a specific energy level and emit coherent radio waves, through a process whose details are hazy to me but it's pretty much a laser (albeit a mind-boggingly gigantic one).

      The radio waves are redshifted to about four times their original wavelength by the time they reach us, but they're still quite high a frequency at about 6GHz. So yes, the water molecules were detected with radio waves, at a range also called microwaves. (I'm always confused about the boundary between plain radio waves and microwaves. :)

  1. OK - (smacking my head) - I just noticed the word "fingerprint" on the visual aid. DUH!! It's all clear now. Sorry for all the trouble. You are very kind to put up with me! :-)

    1. Now that I think about it, maybe I should have mentioned something about a spectrograph in the radio wavelength range. ^_^;;

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