by As our universe expands in all directions like an indestructible balloon – thanks to dark energy, a force completely hidden from the human eye – Dillon Brout is an astrophysicist trying to make sense of it all.
Brout wishes to reveal the strange correlation between the invisible and visible universe, understand how the fabric of space-time flows and perhaps finally reveal the truth that causes the cosmos to bubble up faster and faster in during the day.
To do this, he collects supernovas.
When it comes to picking which top notes to add to the shelf, however, Brout isn’t interested in them all. These starbursts are usually divided into two main streets categories: Type 2 and Type 1a. Brout wants the Types 1a, and his reasoning is quite simple:
“They are not all exactly the same, but they are very similar,” he told Space.com.
Related: How fast is the universe expanding? New supernova data could help nail it down
Basically, to solve all the above-mentioned space mysteries, you need to measure some distances on cosmological scales. Only then will you know, for example, how long and how fast dark energy seems to be forced space to expand. Do a reverse calculation from there, and you might learn something about the nature of dark energy itself, too. However, to measure such great distances and invisible concepts, to know how far back we can see and how far back that point travels, you need something as basic as a ruler.
Fortunately, because they are so standardized in brightness and general behavior, Type 1a supernovae are like the ticks on light year-long rulers going through space. In fact, astronomers like to call them “standard candles” for this reason. They are perfect lighthouses that guide us as we calibrate our equations and search for some answers. The more we have, the better.
Looking for efficiency and accuracy, Brout fills up his supernova collected using machine learning algorithms that actively find as many Type 1a types as possible. (Another reason Type 1a standardization is helpful. Consistent algorithms love consistency.)
It is part of the Dark Energy Survey collaboration, and earlier this month, the team announced that their algorithms had successfully detected 1,500 of these natural luminous markers – in five years. That’s a pretty big deal. For context, Brout says it took scientists 30 years of regular Type 1a searches (for example, using a reliable spectrograph) to find the full 1,500 previous objects. ROS obtained the same result within about a sixth of that time frame.
“One of the biggest things that made DES so special was that it covered so many areas of the sky,” said Brout, adding that he has enough confidence in its algorithms to say that cross-checking of the same parameters.
But things are about to escalate.
Although the Department of Education and Skills produced a significant number of Type 1a, its associated instrument, the Dark Energy Camera, only covered 30 square degrees of sky. That’s a relatively small fraction, says Brout. Admission: Rubin Observatory.
Or, more specifically, the Space and Time Legacy Survey which will be created in part using the state-of-the-art LSST Camera starting next year.
“LSST is going to look all the way south the night sky,” said Brout. “You’re going to go from DES discovering 1,500 to LSST discovering a million alerts, and we’re going to filter that, hopefully, using machine learning and other algorithms to a few 100,000 Type supernovae 1a to get. “
One specific question waiting to be answered
Fortunately, the Rubin Observatory is on track for full construction later this year and the LSST will soon begin its journey from the top of the Chilean summit, said Victor Krabbendam, the observatory’s construction project manager during the 243rd meeting of the American Astronomical Society in January 2024. “We are about 10 years into the actual construction phase,” he said. “The sun is going down and we’re getting close.”
And in fact, Brout already has a separate answer waiting to be resolved with the LSST.
With their massive haul of 1,500 Type 1a supernovae announced this month, Brout and fellow researchers confirmed what we currently know about what’s called “the cosmological constant,” which you can think of as a value that represents dark energy in expansion equations of the universe. It’s the bit of acceleration that normal physics can’t fully explain. This “confirmation” may seem disappointing at first, but in a way, it is good progress. It means that one of the most accurate calculations of the expansion of the universe is telling us that we are probably right about everything we know about dark energy so far.
Perhaps more interestingly, however, the team’s work also revealed a curious pattern. “We have a section in the paper that combines all the available probes of dark energy, not just supernovae, and what we see is that many of them are pointing to a slightly larger value of the dark energy ‘equation of state’ . , which would suggest that it is not a cosmological constant.”
In other words, that would mean that there is no absolute value that represents dark energy. Maybe it’s flexible.
“One of the big benefits we get from this new LSST analysis is that we find a lot more supernovae in the nearby universe, and that’s because we’re covering so much area of the sky,” said Brout. “If you think about it, the universes are nearby the universe that, because of the speed of light, we are seeing the galaxies much closer than they are today. If you are looking at the universe from afar you see the universe as much younger.”
This is important, he explains, because the effect of dark energy is believed to be the strongest in the universe recently. Why? This is where it gets really weird.
“We think dark energy is a property of space,” said Brout. “That’s the kind that includes the cosmological constant, which is like the energy of empty space.”
So, if dark energy is a property of empty space, that would mean that there is more dark energy in the universe today than in the past. This is because the universe is expanding, which creates more “space.”
“We think it doesn’t thin out as the universe expands,” Brout said, “so that means, relative to the amount of matter in the universe and dark dark in the Universe, you’re getting more and more dark energy.”
At this point, as I was, you may be thinking: I’m sorry, what? I thought that the universe is? Where does the new dark energy come from? Can’t just pop it in there, right?
“That’s the million dollar question,” said Brout. “Is it a property of space? Is this a fundamental property of the universe? That you would naturally get more dark energy as space itself expands?”
And to achieve this, we will soon have a multi-million dollar camera.
golden observatory 2025
There are four big steps left before Brout can start counting the days before the first LSST light. First, Rubin’s team needs to have some key mirrors ready to go. Next, the team must obtain the glass necessary for the Simonyi telescope – which is said to have flown through tests without even the correct glass component – and then install the commissioning camera. Finally, the approximately $200 million LSST camera, which is currently being assembled on the West Coast, will receive its location.
“You still have to get that from California to the summit. It’s a very sensitive instrument. It’s special in the sense that it’s a $200 million camera — irreplaceable,” Krabbendam told Space.com.
“It’s a huge camera,” he said. “It’s 3.2 gigapixels for a focal plane.”
Related Stories:
— The Rubin Observatory could solve the mysteries of the dark universe
— We still don’t know what dark matter is, but here’s what it isn’t
— Hypothetical ‘dark photons’ could shed light on mysterious dark matter
One gigapixel, for context, is equal to one billion pixels; A standard DSLR camera works on megapixel scales, or millions of pixels. To really drive this home, consider how a million seconds are 12 days; One billion seconds equals 31 years. So… picture that resolution of camera power scanning the entire observable southern sky.
That’s why the observatory, built with about $500 million in funding from the National Science Foundation and a few $100 million in funding from the Department of Energy — the latter of which has a particular interest in studies of dark energy like Brout’s.
So looking forward to it.
Update 2/1: 1 million seconds equals 12 days, this article has been updated to reflect that.
