Arguably the biggest science story of the week was the discovery of material evidence of dark matter. In this two-part article, two lead researchers on the report explain their findings and the significance of the work. Their accounts are full of–besides beautiful explanations of cutting-edge physics research in layman’s terms–potent philosophy and enthralling sentiment about what these scientists are doing and what will come.
Never-before detected elements have been found by a group of European physicists looking for anomalies in signals emanating from several galaxies. The findings–pieces of “missing Lego” in the words of researcher Dr. Oleksii Boiarskyi–will validate some of the approaches currently being undertaken to understand the universe while invalidating others, and will bring us one step closer to the complete picture of physics.
“If this signal is confirmed, we will have a completely new tool to study the structure of our Universe, it’s ‘dark side’ and also its history, how did it form,” Dr. Oleksii Boiarskyi of the Instituut-Lorentz for Theoretical Physics and and Leiden University told The Speaker.
“On the particle physics level, we will know more about the missing Lego elements that where used to build this Universe–and that we did not detect so far. This will support some approaches extending our knowledge and will disfavour the others.
“We would make one more step towards the complete picture of physics.”
Read more: Dark matter signals, part one: Ruchayskiy explains
The team detected anomalies in signals–photon emissions in X-ray spectra–using the European Space Agency’s (ESA) XMM-Newton telescope (feature image). The anomalies were something the the team had been seeking–they were acting on a hypothesis that dark matter occasionally decayed, and that they could pick up signals that represented that decaying dark matter. They found just that.
The findings, if confirmed, would be the first ever evidence of the heretofore undetectable material that accounts for an estimated 80 percent of our universe.
Boiarskyi explained to us what the signal was that they had detected, and what it was like reading the data.
“We study the spectra of galaxies and clusters of galaxies,” said Boiarskyi. “This is a function, a number of photons detected for each energy.
“It has a smooth–continuous–part and narrow lines. The lines come from various atomic transitions and continuum from just emission of accelerated charged particles.
“We can find a model that describes all these emissions and find a good fit for the data. If a statistically significant residual to this model exists, this means that there is another line, that is coming from some additional quantum transition.
“In our case the position and normalisation of this lines are not like you expect from atomic transition. Moreover, it changes over the sky as DM density–projected along the line of sight.
“That is why there is a conjecture that this could come from decay of DM particles. You can check this conjecture by comparing signals from various DM dominating objects. So far it is consistent.”
It is not certain whether the type of dark matter found by the team accounts for the full 80 percent of currently unknown matter expected to exist, or whether there were a variety of dark matters.
“Nobody knows,” said Boiarskyi, “both are possible. But of course one first tries a minimal model with one sort of DM.”
Confirmation could be a year away, Boiarskyi told us.
“[W]e still need to wait about a year, once new data are available, to check if this hypothesis is correct or not. If DM will be discovered once, most likely it will be a story similar to the one we are having now…”
The report, “An unidentified line in X-ray spectra of the Andromeda galaxy and Perseus galaxy cluster,” was completed by A. Boyarsky, O. Ruchayskiy, D. Iakubovskyi, and J. Franse, and was published on the Cornell University website.
Read the thoughts of another physicist on this study, Dr. Dr. Oleg Ruchayskiy: Dark matter signals, part one: Ruchayskiy explains