Bingo radio telescope to investigate dark energy in Brazil’s Paraíba outback

RIO DE JANEIRO, BRAZIL – To be a thing, in short, is something rare in the universe. The bulk of the mass-energy content in the darkness around us consists of two mysterious entities: 27% dark matter (which we know exists because of its gravitational influence, but is undetectable) and 68% dark energy – a force that expands the cosmos, dragging galaxies away from each other.

Brazil is about to become an important hub for research on dark matter and many other key topics in contemporary astronomy, such as pulsars and fast radio bursts.

The Bingo radio telescope is scheduled to begin operating in the second half of 2022 in the municipality of Aguiar, with a population of 5,500, in Paraíba state, some 400 km west of the coastal capital João Pessoa. The portal went online Tuesday, July 6.

This contraption, whose infrastructure occupies an area equivalent to that of Maracanã stadium, is the result of a partnership between the University of São Paulo (USP), the National Institute for Space Research (INPE), the Federal University of Campina Grande (UFCG) located in Paraíba, and institutions from China, the UK, and 7 other countries.

The pandemic disrupted the project’s progress and prevented a range of on-site activities. For example: parts called “horns” (and which in fact look like a Cornetto ice cream) are still under construction, and smaller auxiliary telescopes called outriggers are being tested by researchers.

The basics: what is the difference between a radio telescope and an ordinary telescope? What does the acronym Bingo stand for? Why was it installed in such an isolated place?

Bingo for dummies

Electromagnetic waves – what we broadly call “light” – come in various lengths. The shorter ones are more energetic; the longer ones are lazier. Human vision can only perceive waves located within a very specific range of lengths. These are the colors we know; the colors of the rainbow. Nature’s pencil box is much larger: there are radio waves, microwaves, infrared radiation, ultraviolet radiation, X-rays, gamma rays…

Although these colors are invisible to our biology, they are part of our everyday life: they heat up our food, tan our skin on the beach, see inside our bodies, and of course are the secret behind telecommunications: radio, TV, mobile telephony, wi-fi, etc.

The Universe doesn’t care what use we humans give to each type of wave. Out there, light is light. Astronomical phenomena release radiation in all colors, the ones we see and the ones we don’t see too. This is why there are telescopes designed to see colors invisible to us – and detect things that we could not see with lenses and eyes alone.

This is the case with Bingo, a telescope designed to pick up radio waves. Therefore, a radio telescope.

When you turn on analog TV, you see a gray, grainy interference. A portion of this interference is generated by residual radiation from the Big Bang that reaches the Earth’s antennas. This light, which dates from the origin of the cosmos, is very faint after traveling for 13.8 billion years. It permeates the entire universe and is called cosmic background radiation.

Remember that hydrogen is the most common element in the universe? Well, it is so basically black that astronomers simply call it “neutral gas.” When cosmic background radiation interacts with hydrogen, the atoms in this neutral gas oscillate and release a little radiation of radio-like length. It is this radiation that the Bingo telescope will capture in Paraíba.

Why will it capture it?

Bingo stands for Baryon Acoustic Oscillations In Neutral Gas Observations. “Baryons” are just a fancy name for particles like protons and neutrons, which make up atoms. That’s where the name “baryonic matter” comes from – used at the beginning of the article to refer to humans and the rest of the palpable and detectable matter in the universe.

The purpose of capturing this radiation is to map the distribution of hydrogen throughout the universe. By knowing where there are larger or smaller amounts of neutral gas, scientists are able to infer important data about the expansion of the universe, and thus take an important step in the investigation of dark energy, which is responsible for the expansion.

The problem with picking up radio from space is that radio is already a common thing on Earth. According to Elcio Abdalla, professor at the Physics Institute (IF) at USP and the project’s coordinator, “the main problem for installing the radio telescope is that you don’t have wave interference in the band we are observing, between 960 and 1260 MHz.”

“This is a widely used band that can suffer interference from human emissions – cell phones, radio and TV transmissions… Aircraft routes and wind power generation also get in the way.”

Elcio explains that the town of Aguiar, in the Paraíba semi-arid outback (sertão) and far from any major population center, was the cleanest place [from the electromagnetic standpoint] found in research in Brazil and Uruguay – with the advantage of being close to UFCG, which is part of the partnership.

Bingo will have two round satellite dishes, one 40m and the other 34m in diameter. They are complemented by 50 horns 1.9 meters in diameter and 4.3 meters long. Because it is a telescope designed to pick up radio waves, it is a far cry from the clichéd appearance of a tube with lenses – the idea of a telescope in popular imagination.

Fast radio bursts

In addition to studying the distribution of hydrogen in the cosmos, the Bingo will contribute to the observation and study of Fast Radio Bursts (FRB). These are high-energy electromagnetic pulses that last for milliseconds. The first detection of a FRB occurred in 2007, and to this day the cause and origin of these disturbances are unknown.

“If we can observe a little more of the structure of this phenomenon and describe it from a dynamical point of view, it would be fantastically important,” Abdalla says. “Observing is very important in itself. Providing a theoretical explanation – at least an indication of its origin – would be even more so.”

Bingo will also enable the study of another phenomenon: pulsars. A pulsar is a neutron star that spins very fast and emits beams of radio waves from its poles thanks to an extremely strong magnetic field.

Pulsars subject the matter around them to unusual conditions, and their study broadens our understanding of gravity, the composition of the universe, and the behavior of electric and magnetic fields in extreme situations.

The project also aims to obtain information about objects closer to us. The outriggers (auxiliary telescopes) spread over other regions in Brazil will make it possible to identify the presence of satellites, for example.

Finally, the scientists involved with Bingo are planning lectures and presentations in schools and museums – among other projects to explain the science behind it to the public. After all, in times of terraplanetism, the antivaccine movement, and so much more obscurantism, fighting to do science in Brazil in the present is not enough.

A generation that will grow up aware of the central role of research for the country – and that will not need to fight so hard to do it in the future – is also needed.

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