Astrophysicists map the infant universe in 3-D and discover 4,000 early galaxies

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Credit: ESO/UltraVISTA team. Acknowledgement: TERAPIX/CNRS/INSU/CASU

Astronomers today announce one of the largest 3D maps of the infant Universe, in a presentation at the European Week of Astronomy and Space Science in Liverpool. A team led by Dr David Sobral of Lancaster University made the chart using the Subaru telescope in Hawaii and the Isaac Newton telescope in the Canary Islands. Looking back in time to 16 different epochs between 11 and 13 billion years ago, the researchers discovered almost 4000 early galaxies, many of which will have evolved into galaxies like our own Milky Way.

Light from the most distant galaxies takes billions of years to reach us. This means that telescopes act as time machines, allowing astronomers to see galaxies in the distant past. The light from these galaxies is also stretched by the expansion of the Universe, increasing its wavelength to make it redder. This so-called redshift is related to the distance of the galaxy. By measuring the redshift of a galaxy, astronomers can thus deduce its distance, how long its light has taken to reach us and hence how far back in time we are seeing it.

In the new work the team used filters to sample particular wavelengths of light, and hence specific epochs in the history of the Universe.

Sergio Santos, a Lancaster PhD student and team member, comments: "We used large amounts of data taken with 16 special filters on wide field cameras and processed them here in Lancaster to literally slice the Universe in cosmic time and time-travel to the distant past with 16 well defined cosmic time destinations."

Dr Sobral adds: "These early galaxies seem to have gone through many more "bursts" when they formed stars, instead of forming them at a relatively steady rate like our own galaxy. Additionally, they seem to have a population of young stars that is hotter, bluer and more metal-poor than those we see today."

Sobral and his team found galaxies that existed when the Universe was only 20 to 7% of its current age, and hence provide crucial information about the early phases of galaxy formation.

The researchers also found that these early galaxies are incredibly compact. "The bulk of the distant galaxies we found are only about 3 thousand light years across in size, while our Milky Way is about 30 times larger. Their compactness likely explains many of their exciting physical properties that were common in the early Universe", comments Ana Paulino-Afonso, a PhD student in Lancaster and Lisbon. "Some of these galaxies should have evolved to become like our own and thus we are seeing what our galaxy may have looked like 11 to 13 billion years ago."

The team searched for distant galaxies emitting Lyman-alpha radiation, using 16 different narrow and medium band filters over the COSMOS field, which is one of the most widely studied regions of sky outside our Milky Way, located in the direction of the constellation of Sextans. The Lancaster-led team includes young researchers from Leiden, Lisbon and California. The team also publish their findings in two papers in the journal Monthly Notices of the Royal Astronomical Society and the data are now publicly available for other astronomers to make further discoveries.

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Ms Anita Heward
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Dr Morgan Hollis
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Dr Helen Klus
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Dr Marieke Baan
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Science contacts

Dr David Sobral
Lancaster University
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Images and captions

https://www.ras.org.uk/images/stories/EWASS2018/Sobral/SC4K_billion_lightyears_DS.jpg

A map of the cube of spacetime covered in the new survey, showing the distance to the galaxies in billions of light years. The positions of the 4,000 galaxies appear as circles. The colours represent the degree of redshift seen, with the bluer circles indicating galaxies nearer to the Earth, and so less redshifted. Green, yellow, orange and red circles indicate successively higher redshifts, and galaxies that are progressively further away from the Earth. Credit: D. Sobral

https://www.ras.org.uk/images/stories/EWASS2018/Sobral/SC4K_lookbacktime_DS.jpg

A map of the cube of spacetime covered in the new survey, showing the 'lookback time' to the galaxies in billions of years. The positions of the 4,000 galaxies appear as circles. The colours represent the degree of redshift seen, with the bluer circles indicating galaxies seen in the more recent past, and so less redshifted. Green, yellow, orange and red circles indicate successively higher redshifts, and galaxies that are progressively seen further back in time. Credit: D. Sobral

https://www.ras.org.uk/images/stories/EWASS2018/Sobral/heic1313b_large.jpg

A view of the COSMOS field in the constellation of Sextans, seen in infrared light. This corresponds closely to the region of the sky studied in the new work. Credit: ESO/UltraVISTA team. Acknowledgement: TERAPIX/CNRS/INSU/CASU

Further information

This work appears in "Slicing COSMOS with SC4K: the evolution of typical Lyα emitters and the Lyα escape fraction from z~2to z~6", David Sobral, Sérgio Santos, Jorryt Matthee, Ana Paulino-Afonso, Bruno Ribeiro, João Calhau, Ali Khostovan, Monthly Notices of the Royal Astronomical Society, in press.

and

"On the UV compactness and morphologies of typical Lyman-α emitters from z ? 2 to z ? 6", Ana Paulino-Afonso, David Sobral, Bruno Ribeiro, Jorryt Matthee, Sérgio Santos, João Calhau, Alex Forshaw, Andrea Johnson, Joanna Merrick, Sara Pérez and Oliver Sheldon, Monthly Notices of the Royal Astronomical Society, in press.

Notes for editors

The European Week of Astronomy and Space Science (EWASS 2018) will take place at the Arena and Conference Centre (ACC) in Liverpool from 3 – 6 April 2018. Bringing together around 1500 astronomers and space scientists, the conference is the largest professional astronomy and space science event in the UK for a decade and will see leading researchers from around the world presenting their latest work.

EWASS 2018 is a joint meeting of the European Astronomical Society and the Royal Astronomical Society. It incorporates the RAS National Astronomy Meeting (NAM), and includes the annual meeting of the UK Solar Physics (UKSP) group. The conference is principally sponsored by the Royal Astronomical Society (RAS), the Science and Technology Facilities Council (STFC) and Liverpool John Moores University (LJMU).

Liverpool John Moores University (LJMU) is one of the largest, most dynamic and forward-thinking universities in the UK, with a vibrant community of 25,000 students from over 100 countries world-wide, 2,500 staff and 250 degree courses. LJMU celebrated its 25th anniversary of becoming a university in 2017 and has launched a new five-year vision built around four key 'pillars' to deliver excellence in education; impactful research and scholarship; enhanced civic and global engagement; and an outstanding student experience.

The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organizes scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 4000 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.

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STFC's Astronomy and Space Science programme provides support for a wide range of facilities, research groups and individuals in order to investigate some of the highest priority questions in astrophysics, cosmology and solar system science. STFC's astronomy and space science programme is delivered through grant funding for research activities, and also through support of technical activities at STFC's UK Astronomy Technology Centre and RAL Space at the Rutherford Appleton Laboratory. STFC also supports UK astronomy through the international European Southern Observatory.

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