A tiny signal, dating back to the birth of the first stars in our universe, has been detected by astronomers for the first time.

They have picked up a radio signature produced just 180 million years after the Big Bang using a simple antenna in the West Australian outback.

The ground breaking discovery, reported today in the journal Nature, sheds light on a period of time known as the “cosmic dawn”, when radiation from the first stars started to alter the primordial gas soup surrounding them.

It could also completely revolutionise our understanding about dark matter, the invisible structure that makes up the bulk of our universe today.

“The signal confirms our expectations for when stars show up in the universe,” said the study’s lead author Judd Bowman of Arizona State University.

“But it’s also telling us that there’s something mysterious happening at this time beyond our previous expectations”, he said.

http://www.abc.net.au/news/science/2018-03-01/signal-from-universes-first-stars-deepens-dark-matter-mystery/9479940

Interesting, ta.

After stars formed in the early Universe, their ultraviolet light is expected, eventually, to have penetrated the primordial hydrogen gas and altered the excitation state of its 21-centimetre hyperfine line. This alteration would cause the gas to absorb photons from the cosmic microwave background, producing a spectral distortion that should be observable today at radio frequencies of less than 200 megahertz. Here we report the detection of a flattened absorption profile in the sky-averaged radio spectrum, which is centred at a frequency of 78 megahertz and has a best-fitting full-width at half-maximum of 19 megahertz and an amplitude of 0.5 kelvin. The profile is largely consistent with expectations for the 21-centimetre signal induced by early stars; however, the best-fitting amplitude of the profile is more than a factor of two greater than the largest predictions. This discrepancy suggests that either the primordial gas was much colder than expected or the background radiation temperature was hotter than expected.

Astrophysical phenomena (such as radiation from stars and stellar remnants) are unlikely to account for this discrepancy; of the proposed extensions to the standard model of cosmology and particle physics, only cooling of the gas as a result of interactions between dark matter and baryons seems to explain the observed amplitude.

The low-frequency edge of the observed profile indicates that stars existed and had produced a background of Lyman-α photons by 180 million years after the Big Bang. The high-frequency edge indicates that the gas was heated to above the radiation temperature less than 100 million years later.

Nature

To me, the important part is this:

Going to Western Australia and working at the Murchison Radio-astronomy Observatory was an absolutely critical first step. There they built a small table-sized radio spectrometer with a radio receiver attached to two metal panels that act as an antenna. Akin to a set-up from the 60s or 70s, the EDGES instrument is much simpler in design than bigger array telescopes around the world.
Murchison Radio Astronomy Observatory

After years of complex calibrations to the detector, Professor Bowman and colleagues finally found what they were looking for.
They detected a signal with a frequency of 78 megahertz, which was in the range predicted for a star formation by 180 million years.
But, to their surprise, the signal was twice as strong as it should be.

mollwollfumble said:

After years of complex calibrations to the detector, Professor Bowman and colleagues finally found what they were looking for.
They detected a signal with a frequency of 78 megahertz, which was in the range predicted for a star formation by 180 million years.
But, to their surprise, the signal was twice as strong as it should be.

Being within a factor of 2 of the estimated signal strength strikes me as being a bloody good guess, I mean scientific estimate.

The Rev Dodgson said:

mollwollfumble said:

After years of complex calibrations to the detector, Professor Bowman and colleagues finally found what they were looking for.
They detected a signal with a frequency of 78 megahertz, which was in the range predicted for a star formation by 180 million years.
But, to their surprise, the signal was twice as strong as it should be.

Being within a factor of 2 of the estimated signal strength strikes me as being a bloody good guess, I mean scientific estimate.

Might be near enough for a civil engineer but not for a cosmologist.

>Astrophysical phenomena (such as radiation from stars and stellar remnants) are unlikely to account for this discrepancy; of the proposed extensions to the standard model of cosmology and particle physics, only cooling of the gas as a result of interactions between dark matter and baryons seems to explain the observed amplitude.

Ian said:

The Rev Dodgson said:

mollwollfumble said:

After years of complex calibrations to the detector, Professor Bowman and colleagues finally found what they were looking for.
They detected a signal with a frequency of 78 megahertz, which was in the range predicted for a star formation by 180 million years.
But, to their surprise, the signal was twice as strong as it should be.

Being within a factor of 2 of the estimated signal strength strikes me as being a bloody good guess, I mean scientific estimate.

Might be near enough for a civil engineer but not for a cosmologist.

>Astrophysical phenomena (such as radiation from stars and stellar remnants) are unlikely to account for this discrepancy; of the proposed extensions to the standard model of cosmology and particle physics, only cooling of the gas as a result of interactions between dark matter and baryons seems to explain the observed amplitude.

I really think that reflects an over-confidence in their models.

The Rev Dodgson said:

Ian said:

The Rev Dodgson said:

Being within a factor of 2 of the estimated signal strength strikes me as being a bloody good guess, I mean scientific estimate.

Might be near enough for a civil engineer but not for a cosmologist.

>Astrophysical phenomena (such as radiation from stars and stellar remnants) are unlikely to account for this discrepancy; of the proposed extensions to the standard model of cosmology and particle physics, only cooling of the gas as a result of interactions between dark matter and baryons seems to explain the observed amplitude.

I really think that reflects an over-confidence in their models.

Maybe. They are keen for someone else to replicate this experiment.

Perhaps something boosted the signal between its place of origin and here

Cymek said:

Perhaps something boosted the signal between its place of origin and here

I think they are saying that the signal was attenuated less than predicted.