Studying the Nature of Dark Matter using Radio Waves:
News links
In recent decades, the biggest discoveries in physics have come from astronomy (dark matter, dark energy, gravitational waves, and black holes). In March 2018 I announced an exciting potential discovery that could represent another example of deriving fundamental physics from astronomical observations.
Astronomers have been searching for a radio-wave signal that had been predicted to be a sign of the formation of the first stars in the early Universe. Bowman and colleagues reported the first such detection, obtained with their EDGES radio telescope. The signal had a much larger amplitude than expected, presenting a puzzle. I realized that this surprising signal can be explained by combining two factors: the first stars, and dark matter. The first stars in the universe turned on the radio signal as expected, while the dark matter collided with the ordinary matter and cooled it down. Extra-cold material naturally explains the strong radio signal.
If true, this would have enormous implications in answering one of the most basic questions: What is the Universe made of? Indeed, this would be the first direct clue about the nature of the mysterious dark matter that makes up most of the matter in the Universe. For example, physicists expected that dark matter would be made up of heavy particles, but the discovery indicates low-mass particles.
Caution is needed, since the EDGES measurement is the first of its kind. Independent confirmation is now being attempted, and the first experiment that reached comparable sensitivity (SARAS3) disfavored the EDGES result (at a 2 sigma statistical significance). Much more information is expected within a few years. I predicted that the dark matter may have produced a specific pattern of radio waves on the sky (the colorful image above or to the left of this text is an example), which can be detected with a large array of radio antennas. One such array is the SKA, the largest radio telescope in the world, now under construction (the second image shows me next to an SKA antenna prototype, at Cambridge University). Such an observation with the SKA would confirm that the first stars have indeed revealed the dark matter.
More info, audio/video, and links available here.
This shows my academic
tree (based on Ph.D. supervision), including my academic
ancestors (going back 4 generations), and my academic
descendants (16 total, going forward 2 generations). Also
included are some of my academic brothers as well as some of my
academic uncles, and a great-great-uncle. Based
on The
Astronomy Genealogy Project. Going further back,
Ph.D. degrees were less common. Main research advisors and
approximate year of supervision go back from Fowler with
Archibald Hill (1915), Walter Morley Fletcher (1907), John
Newport Langley (1894), Michael Foster (1871), and then Thomas
Henry Huxley and William Sharpey (1859), with the former known
as Darwin's Bulldog (and also my academic ancestor, going back 9
generations).
1. Early 2020 TED-style talk (12.5 min) about "Mankind, the Universe, and Dark Matter"
2. Early 2018 explanation (4 min) on The First Stars (Hebrew with English subtitles)
Dark Matter Revealed by the First Stars, (2.5 min, 2018): English version, Hebrew version
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