Twenty thousand high quality images from the Hawaii Two-0 (H20)/Cosmic Dawn survey have been released to the public on the most popular citizen science project: Galaxy Zoo. Anyone in the world can become a citizen scientist and help astronomers classify images taken with one of the most advanced instruments installed on one of world's leading telescopes: the camera Hyper-Suprime Cam on the Subaru telescope.

The project has been implemented for several years, currently in international cooperation between Galaxy Zoo, The Open University (UK), University of Hawaii (USA) and University of Copenhagen (Denmark), including National Centre for Nuclear Research (Poland). In December, new images of the most distant galaxies ever seen in the Galactic Zoo were released to the public. This unique data set will provide the public with the opportunity to make exciting new discoveries of previously unseen and unclassified, cosmic objects. These discoveries may well result in more detailed follow up observations using other world-class telescopes.

And what are we looking for?

The invaluable contribution from citizen scientists will help astronomers improve their understanding of the evolution of galaxies over a significant fraction of the age of the Universe. The classifications of the H20/Cosmic Dawn data will help to identify previously unseen strong gravitational lenses, when a foreground galaxy bends the light of a background galaxy. Finding these gravitational lenses will help astronomers refine their understanding of how the Universe works and how fast it is expanding. The classifications will also help to better understand the role galaxy mergers play in the evolution of galaxies. Galaxy mergers are known to influence the star-formation rates of galaxies but exactly how and when this enhancement happens is still uncertain. With the classifications from this project these changes can be narrowed down. Both gravitational lenses and galaxy mergers are rare and important phenomena for which having human eyes on the data can really make a difference.

But this is not all. The classifications of the H20/Cosmic Dawn images will pave the way for science with future telescopes. The ESA Euclid mission, scheduled to launch next year, will make deep observations of the area in the sky containing the H20/Cosmic Dawn images. The classifications made by the citizen scientists will be indispensable to help learn about the universe and guide the Euclid science teams.

The information gained from this study will also be applicable to upcoming ground-based surveys. The Vera C. Rubin observatory will image billions of galaxies over the next ten years. The understanding gained from the high redshift galaxies - how to present them in citizen science projects, the knowledge we can gain from them - will be extremely useful for the millions of high redshift galaxies that will need to be examined from the Vera C. Rubin data.

The H20/Cosmic Dawn survey is ongoing. New images will be added to Galaxy Zoo as the survey progresses, providing the opportunity for the public to engage at the leading edge of scientific research, in lock step with the scientists. "Thanks to the data from the Galactic Zoo, many scientific papers have already been written" - explains Prof. dr hab. Agnieszka Pollo, Head of the NCBJ Astrophysics Department, who has been personally involved in the project for over ten years. "We hope that we will also use the new classified data in our research. But interestingly, there are also completely unexpected, but at the same time scientifically significant discoveries made by participants. An unusual image that does not match the pattern may contain some impurities, but there may also be a new unknown object or phenomenon on it. That's why on the Galactic Zoo website there is also an option to tag particularly interesting photos and discuss them."

To help write the next chapter of astronomy, head over to Galaxy Zoo and start classifying today: https://www.galaxyzoo.org/

Illustrations:
Photos from the H20/Cosmic Dawn survey selected by Galaxy Zoo Talk users
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