How Stargazing Live Viewers Found a Key Galaxy to the Early Universe

How Stargazing Live Viewers Found a Key Galaxy to the Early Universe

For years I worked on Live Stargazingallowing the large audience brought together by Brian Cox and Dara O’Briain to contribute to science through their web browsers.

Working with the fabulous team at Zooniverse, over the years we’ve searched for exoplanets, strange “spider” features on Mars, and even measured the age of the Universe by finding supernovae.

But the most fun I had was looking for gravitational lenses in 2014.

Supernova spotted in the Cartwheel galaxy between 2014 (left) and late 2021 (right) VERY LARGE TELESCOPE, NEW TECHNOLOGY TELESCOPE, MARCH 7, 2022 IMAGE CREDIT: ESO/Inserra et al., Amram et al.

Supernova spotted in the Cartwheel galaxy between 2014 (left) and late 2021 (right), Very Large Telescope, New Technology Telescope, March 7, 2022. Credit: ESO/Inserra et al., Amram et al.

The goal was to find the images of distant galaxies that have been distorted, and most likely magnified, as their light passes through nearby massive systems such as other galaxies and clusters.

The gravity of these closer systems bends the incoming light and, if things line up correctly, the images end up looking like little blue rings or arcs that we can use to get information about the distant Universe.

A gravitational lens view of SPT0418-47, the most distant Milky Way-like galaxy ever observed.  Credit: ALMA (ESO/NAOJ/NRAO), Rizzo et al.

A gravitational lens view of SPT0418-47, the most distant Milky Way-like galaxy ever observed. Credit: ALMA (ESO/NAOJ/NRAO), Rizzo et al.

For three consecutive nights, Live Stargazing asked its viewers to sift through millions of images taken by the Dark Energy Survey to identify potential lenses.

At lunchtime the day after the first show, we thought we had a good contender in ring form. It wasn’t blue, it was red, but it definitely looked like a bonafide goal: the catchy-named 9io9.

“Maybe” wasn’t good enough for Brian or his producers, however.

We needed a radio telescope to confirm the discovery, so viewers on the show’s second night saw the Lowell Telescope in Arizona pick up data confirming that the 9io9 galaxy was a distant system.

The light reaching us today was triggered 11 billion years ago, when the Universe was only 2.5 billion years old.

Since the discovery, a team led by Jim Geach of the University of Hertfordshire has observed the galaxy, finding it to be a remarkably efficient star factory.

But how do galaxies undergoing extreme star formation behave in the early Universe?

Recently, they used ALMA, a sub-millimeter array located on the high dry Atacama Desert in Chile, capable of detecting weak radiation from molecules such as carbon dioxide and ammonia.

ALMA (Atacama Large Millimeter/Submillimeter Array) antennas in the Chilean Andes.  Credit: ESO/C.  clever

ALMA (Atacama Large Millimeter/Submillimeter Array) antennas in the Chilean Andes. Credit: ESO/C. clever

These typically exist in the dense gas associated with star forming regions, where they are excited and glow in the wavelengths that ALMA looks at.

It appears from observations that ammonia and hence star formation is distributed throughout the galaxy’s disk, rather than concentrated in any particular region.

If 9io9 is typical, that settles a long-standing argument about such extreme star-forming galaxies.

Some thought such prodigious feats of star formation would only be possible if concentrated in a single massive complex, perhaps at the center of the galaxy – but instead the whole galaxy seems alive with stars. newly formed.

Its properties, and in particular the strength of ammonia and carbon dioxide emissions, rather resemble those of our own local stellar nursery, the Orion Nebula.

The sharpest view ever taken of the Orion Nebula, 1,500 light-years away, reveals more than 3,000 stars of varying sizes nestled in the vast cavern of rolling dust and gas.  Credit: NASA, ESA, M. Robberto (Space Telescope Science Institute/ESA) and the Hubble Space Telescope Orion Treasury project team

The Orion Nebula. Credit: NASA, ESA, M. Robberto (Space Telescope Science Institute/ESA) and the Hubble Space Telescope Orion Treasury project team

It turns out what Live Stargazing what viewers found was what Matus Rybak, a doctoral student in Garching, Germany, described as a galaxy “full of Orions.”

Each of them, the authors say, might be individually mundane, but they add up to a galaxy whose likes have transformed the appearance of the Universe.

Almost as remarkable, a discovery made collectively by thousands of television viewers on a cold January night eight years ago continues to expand our knowledge of this distant and ancient cosmos.

Chris Lintott was reading Ammonia in the interstellar medium of a star burst disk at z=2.6by MJ Doherty et al. Read it online at arxiv.org/abs/2209.09268.

This article originally appeared in the November 2022 issue of BBC Sky at Night Magazine.

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