Black Hole Fingerprints: Help Radio Galaxy Zoo Reach Its 1 Millionth Classification

The long winter nights are upon us — what better way to pass the evening than by doing your bit for science? Best part is, you can still watch that favorite holiday movie.

Last week we featured a podcast all about the power of citizen scientists helping to analyze very large datasets.

This week, I want to highlight one such citizen science project that just celebrated its one year anniversary! This project is known as Radio Galaxy Zoo, a title that you might recognize from the very successful Galaxy Zoo.

If you're not familiar with them, radio galaxies are awesome! Their main features are two enormous lobes of plasma that give off radio waves. These lobes are fueled by relativistic jets which are in turn powered from a supermassive black hole. Radio galaxies are the largest objects in the Universe, completely dwarfing the host galaxy from which they emerge.

Hercules A radio galaxy. Radio light is shown in blue highlighting the massive double jets. White visible light shows the central host galaxy and other background galaxies. The surrounding gas emits X-rays, shown in pink. Image from the NASA Chandra Archive Collection. Credit: X-ray: NASA/CXC/SAO, Optical: NASA/STScI, Radio: NSF/NRAO/VLA

In the same way that our genetic features, our wrinkles, and our scars can help trace our individual histories, astronomers can learn a lot about a galaxy's history and composition from its shape, color, and weird features. For radio galaxies, finding the location of the black hole that powers its jets is particularly important. By knowing where the jets start, astronomers can start to piece together the history of the radio galaxy.

The premise behind Radio Galaxy Zoo is to have many volunteers classify radio galaxies by what they look like and where their host galaxy is located. The human eye is essential because humans are much better at recognizing shapes, colors, and unusual features than computers are.

"Manual inspection is still the best method to determine the host galaxy for radio sources with extreme morphologies," said Ivy Wong, astronomer at the University of Western Australia and project scientist for Radio Galaxy Zoo. Computer algorithms can only correctly classify about 10 percent of radio galaxies, she said.

The other problem is that there is far too much data for one lonely researcher to classify alone. There are databases containing millions upon millions radio galaxies, and powerful new telescopes are now being built which will dramatically increase this count.

This is where the power of citizen science comes into its own. In the first year of Radio Galaxy Zoo, 931,029 radio galaxies were classified. The team leaders estimate that if each classification took 5 minutes, then it would take one person working 40 hours a week 37 years to complete the same amount!

1 Millionth Classification Prize

With 931,029 classifications and counting, Radio Galaxy Zoo is nearing its 1 millionth classification, and to celebrate the team is offering prizes to the first few citizen scientists that help reach this target. The prizes include various astronomy-themed T-shirts, mugs, water bottles, and a grand prize of a signed copy of "Bang! — the complete history of the Universe" by Brian May, Patrick Moore, and Chris Lintott.

"Given the upcoming holiday period, I think that we may reach that number in a few weeks. So lots of excitement ahead," said Wong. But she also feels the number of classifications from the first year is "already quite phenomenal". The project will continue for at least another two years.

So while you're relaxing in that glorious week between Christmas and New Year's, perhaps watching a bit of festive TV, you can also do your part for science and classify some radio galaxies (or as I like to think of them, the fingerprints of black holes). Maybe you'll even classify lucky number 1 million.

Compilation of screen shots from the Radio Galaxy Zoo tutorial.

A short tutorial shows you what to look for in both radio and infrared light and from there, most classifications are fairly straightforward. For the unexpected finds (which is really what this sort of citizen science is all about), a forum allows volunteers to discuss things with radio galaxy experts.

Radio Galaxy Zoo is part of the large Zooniverse collection of citizen science projects, so even if radio galaxies are not your thing, you can still answer the call of research by listening to whales, tagging penguins, or even studying the lives of ancient Greeks.

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By Tamela Maciel, also known as "pendulum"