Checking out the Fornax cluster
Mastering the universe
Photo by Aniello Grado and Luca Limatola, European Southern Observatory (ESO)
A pale aubergine is sitting in the centre of my screen. It’s mostly black, with some small orange-y spots in the corners. Next to the aubergine are some more dots, but they’re not as orange. Maybe a little more yellow.
I lean towards the screen, pondering what I see. The aubergine… can I call it ‘fluffy’? Or is it bright? To be honest, I think it’s both. But I have to make a choice.
‘Why don’t you check the help section?’ says a voice in my ear.
I do as instructed and find more pictures there, more dots. Some are labelled as ‘fluffy’. Some are said to be ‘bright’. ‘I think it is fluffily bright’, I say finally, even though that’s not an option at all.
Obviously, the aubergine is not actually an aubergine. It’s a dwarf galaxy in the Fornax cluster, located 65 million light-years from Earth and visible in the Southern Sky when using a large telescope. It is invisible to the naked eye. The picture I’m looking at is from the Fornax Deep Survey dwarf galaxy catalogue, which contains photos of 14,095 galaxies, 590 of which are probably part of the Fornax cluster.
Computing has yet to catch up with the complexity of the human eye
The guy talking in my ear is Teymoor Saifollahi, who is using volunteers in his quest to unravel the secrets of the universe.
Astronomy PhD student Saifollahi studies dark matter, the mysterious substance that we know must be around in abundance, but that nobody has ever actually seen. The only reason scientists believe it exists is that the standard model which explains the way particles interact in our world would otherwise collapse.
All galaxies are made up of both stars and dark matter, says Saifollahi. But dwarf galaxies have dark matter in abundance: they’re a hundred to a thousand times heavier than regular ones. ‘Whatever happens in a small galaxy usually comes from dark matter, so you can trace its physics with less complexity’, he says. If you want to know more about that mysterious substance, it’s a good idea to focus your studies on them. Bonus: there are many more faint and dwarf galaxies than there are bright galaxies, so you have plenty objects to study.
However, to figure out which of the thousands of dwarf galaxies in the universe to study, you have to find out which of the many dots on your space pictures are in fact dwarf galaxies, or, as some astronomers call them, ‘fluffy faints’.
That’s where I come in. And, after I’ve taken my baby steps in classifying an aubergine as ‘fluffy’ or ‘bright’, hopefully many, many other volunteers will follow.
Laypeople can do a lot to help astronomers like Saifollahi with their work. That simple choice between ‘bright’ or ‘fluffy’ actually takes a lot of time to make. Just imagine how long it would take to classify tens of thousands of galaxies on tens of thousands of pictures.
The work is too expensive and too complex for computers to take on. ‘Computing has yet to catch up with the complexity of the human eye. So you can sit and develop something for years, or you can ask people to do it,’ says Saifollahi. Even though it’s sometimes less accurate – especially when people aren’t trained – it is ‘cheap and fast’, he says.
There’s another reason to ask the public to help out, he says. Until recently, astronomers simply didn’t have access to much data on fluffy galaxies. ‘However, the better our telescopes get, the more we are able to see fainter galaxies and the more data on dwarf objects we need to analyse’, Saifollahi says. ‘We need to prepare for the data explosion that will define astronomy in the next decade.’
The better our telescopes get, the more data we need to analyse
Saifollahi also needs information about the properties of the galaxies once they’ve been classified. He wants to know their shape, their colour, texture, and anything unusual that might catch your eye. ‘So we need volunteers.’
Why not use Zooniverse, the largest platform for people-powered research in the world, he thought. This platform was created thirteen years ago to connect researchers to volunteers wanting to help with anything from marking penguins to studying ancient letters. Saifollahi himself even offered his services when he was a teenager and dabbled in amateur astronomy. ‘People are crazy about it.’
Saifollahi and his colleagues from SUNDIAL (SUrvey Network for Deep Imaging Analysis & Learning) brought in Anna Lanteri, a project builder and junior researcher from Italy who wrote her thesis on machine learning algorithms applied to cosmological data. She built a framework that volunteers would actually be able to work with and came up with the questions they need to answer to help astronomers classify galaxies. Whether an object is fluffy or bright will help them determine whether it’s a dwarf galaxy or not. Is it red and yellow or white and blue? ‘Older stars are always red, younger ones are blue’, Saifollahi explains.
There are questions about shape, which has to do with movement. ‘If a galaxy looks like a disc, like our Milky Way, then its objects are rotating: that’s called a spiral galaxy. Elliptical galaxies are not supported by rotation, so the stars move randomly.’
Now, only seven months after they first came up with the idea, they are launching Space Fluff. For now, the project is focused on the Fornax cluster, a veritable zoo for galaxies of all shapes and sizes. But it won’t stop there. The researchers hope to expand the project in one month’s time. ‘If we get to three thousand volunteers, it is great; but five thousand is my dream number to reach by mid-November’, Lanteri says.
Dwarf galaxies should outnumber galaxies like the Milky Way
Hopefully, it will help Lanteri to come up with an explanation for one of the big questions in astronomy: the missing satellite problem. ‘Computer simulations on the distribution of matter in the universe indicate that dwarf galaxies should outnumber galaxies like the Milky Way. For every galaxy like the Milky Way, there should be at least a hundred dwarf galaxies’, she says. Yet nobody has found these missing galaxies, or ‘satellites’. Is it because the cosmological models are wrong? Or because the galaxies simply haven’t been discovered yet?
When astronomers found a number of these dwarf galaxies in the Fornax cluster, it seemed to tilt the balance in favour of the second option. But they’re still looking for more of them in various corners of the universe.
The astronomers won’t always need volunteers to help them. Every answer that every volunteer provides is being fed into a machine learning system, so at some point, an AI system will be able to do the work. But until that day, Saifollahi depends on volunteers answering his questions. So… is the aubergine fluffy or bright?
Fluffy. Definitely fluffy.
Want to participate? You can find more information here.