Scientists publish new research based on citizen science data

Galaxy Zoo is the granddaddy of crowdsourced astronomy. Scientists use its catalog of almost 900,000 galaxies to conduct large-scale studies of galaxies that were never possible before. Here's an overview of several new papers based on Zooniverse citizen science astronomy projects that have been published or posted to preprint archives in the past month.

Crowdsourcing Galactic Candels 

In this illustration of the evolution of galaxies, the Hubble team shows how even the earliest visible galaxies captured by the Candels survey share similar structures to more recent nearby galaxies. You can see the barred spiral galaxies in the bottom row of each "tuning fork" diagram. (Click the image to see it larger or follow the link for more details)  Credit: Nasa, Esa, and M. Kornmesser (ESO)

The fourth version of Galaxy Zoo asks its worldwide volunteers to classify galaxies in images from the Hubble Space Telescope’s Cosmic Assembly Near-infrared Deep Extragalactic Survey (Candels). When they finish, these amateur galaxy-spotters will have created a catalog of galaxies as they existed only 3 billion years after the Big Bang. 

The scientists behind Galaxy Zoo: Candels published a paper that provides insights into the project's early results. You can find the open access article at the Monthly Notices of the Royal Astronomical Society (doi: 10.1093/mnras/stu1817, arXiv preprint: 1409.1214). About 10% of spiral galaxies, including the Milky Way, have a bar structure. Astronomers see this in galactic populations as far back as 8 billion years ago, but they believed that galaxies in the Candles epoch wouldn’t have enough time to form spiral bars. Imagine the surprise when the Galaxy Zoo volunteers identified bars in 10% of spiral galaxies in the Candels images! Lead author Brooke Simmons said in the MNRAS press release:

We had predictions from galaxy simulations that we shouldn’t find any of the barred features that we see in nearby, evolved galaxies, because very young galaxies might be too agitated for them to form. But we now know that isn’t the case. With the public helping us search through many thousands of images of distant galaxies, we discovered that some galaxies settle very early on in the Universe.

Even though the paper is written for a scientific audience, the introductory sections are still readable for the non-scientist. The press release provides a higher level summary, but you should also check out the explanation from co-author Karen Masters on the Galaxy Zoo blog

Spiral Dragons - Galaxies That Shouldn’t Exist

This composite image shows the spiral galaxy J1649+2635 in the visible spectrum along with radio telescope observations of jets (in blue) streaming from its core.  (Click the image to see it larger or follow the link for more details) Credit: Mao et al., NRAO/AUI/NSF, Sloan Digital Sky Survey

A project led by the National Radio Astronomy Observatory used the Galaxy Zoo catalog to find a spiral galaxy with radio-emitting jets of subatomic particles streaming from its core. These Spiral “Dragns” - a tortured acronym for spiral double-lobed radio sources associated with galactic nuclei - shouldn’t exist under astrophysicists’ current understanding of galaxy formation. In a paper to be published in the Monthly Notices of the Royal Astronomical Society (arXiv preprint: 1410.8520) lead author Minnie Mao and her co-investigators matched the crowdsourced Galaxy Zoo catalog with the Unified Radio Catalog, which contains nearly 3,000,000 radio sources. From a subset of over 65,000 “superclean” GalaxyZoo classifications, they found one galaxy, J1649+2635, that was both a spiral and had the tell-tale two-lobed structure of jets emitting in the radio spectrum. The researchers believe that crowdsourced projects like Galaxy Zoo - and its sister Radio Galaxy Zoo - could let astronomers find more of these strange Spiral Dragns. As Mao said in the National Radio Astronomy Observatory’s press release:

The conventional wisdom is that such jets come only from elliptical galaxies that formed through the merger of spirals. We don’t know how spirals can have these large jets.

Crowdsourcing Solar Weather

This 2012 image from Nasa's Stereo-A observatory shows a one-two punch of dual solar storms that accelerated particles to almost 2,900 kilometers per second - 1% the speed of light. The 16,000 citizen scientists contributing to Solar Stormwatch have analyzed storms through 2010 - so there's still time to make a difference. (Click the image to see it larger or follow the link for more details)  Credit: Nasa/Stereo

The scientists behind Galaxy Zoo’s sister project Solar Stormwatch published a paper in the journal Space Weather (doi: 10.1002/2014SW001119). Previous efforts to study solar storms by individual scientists have focused on individual events or small catalogs due to the labor-intensive analysis. At the same time automated software struggles to identify the fuzzy, inconsistent images of coronal mass ejections. The project’s 16,000 volunteers analysed 110 and 77 coronal mass ejections observed by Nasa’s Stereo-A and Stereo-B solar observatories respectively. These Solar Stormwatchers have only analysed Stereo data from 2007 through early 2010 - spanning the solar minimum between cycles 23 and 24 - so there are a lot of solar storms yet to be cataloged. 

This kind of large-scale analysis wouldn't be possible without the combined contributions from thousands of amateurs around the world. As the paper’s authors say, crowdsourcing the analysis...

…has several advantages over manual detection by a single observer, as, with a large number of manual identifications of single events, we are able to derive an average profile for each event and also estimate an uncertainty of this average profile, which helps mitigate the subjective biases of manual identification and is much less of a time burden on individuals.

But Wait There’s More

The catalogs created by citizen scientists around the world aren’t just valuable to the projects’ internal science teams. Other scientists published results that relied on Galaxy Zoo’s catalog.

A team of European and Australian scientists analysed active galactic nuclei - the supermassive black holes in galactic cores. They wanted to understand how galactic mergers triggered these AGN’s and how the AGN regulates the rate of star formation. The Galaxy Zoo catalog let the scientists create a control sample to compare against their analysis. The paper has been accepted by MNRAS (arXiv preprint: 1411.2028).

Scientists at Sweden’s Uppsala University used the Galaxy Zoo catalog to test the conventional wisdom regarding AGN’s. Even though AGN’s appear to take many forms, astrophysicists assume that they are simply seeing the objects from different angles and that all AGN’s are the same kind of object. The new research, published in Nature Physics (doi: 10.1038/nphys2951, arXiv preprint: 1411.6735) created a sample of 65,000 galaxies from the Galaxy Zoo catalog to conduct one of the first large-scale analyses of AGN’s. Their research indicates that a galaxy’s neighboring galaxies influence the nature of its AGN.