Astronomers know that many surveys of the universe miss a large proportion of their targets, but a new survey has found that 90 per cent of galaxies have gone undetected.
Traditional surveys use light emitted by hydrogen, known as the Lyman-alpha line, to probe the number of stars in the distant universe.
But the new survey found that Lyman-alpha light gets trapped within the galaxy that emits it and that 90 per cent of galaxies do not show up in Lyman-alpha surveys, according to Universe Today.
Astronomers always knew they were missing some fraction of the galaxies in Lyman-alpha surveys,’ explains Matthew Hayes, the lead author of the paper, published this week in Nature.
‘But for the first time we now have a measurement. The number of missed galaxies is substantial.’
Using the new HAWK-I camera attached to a telescope, Mr Hayes and his team surveyed an area of space previously measured in terms of Lyman-alpha light.
The new survey recorded light emitted at a different wavelength also by glowing hydrogen and known as the H-alpha line.
They specifically looked at galaxies whose light has been travelling for 10 billion years.
‘This is the first time we have observed a patch of the sky so deeply in light coming from hydrogen at these two very specific wavelengths, and this proved crucial,’ said team member Goran Ostlin.
The astronomers concluded that traditional surveys carried out using Lyman-alpha only see a tiny part of the total light that is produced, since most of the Lyman-alpha photons are destroyed by interaction with the interstellar clouds of gas and dust.
As a result, as much as 90 per cent of galaxies go unseen in these surveys.
‘If there are ten galaxies seen, there could be a hundred there,’ Mr Hayes said.
‘Now that we know how much light we’ve been missing, we can start to create far more accurate representations of the cosmos, understanding better how quickly stars have formed at different times in the life of the universe,’ said co-author Miguel Mas-Hesse.
They may not realize that they are seeing space time warps which cause some galaxies to be duplicated.