Nav: Home

A universe aglow

October 01, 2018

An unexpected abundance of Lyman-alpha emission in the Hubble Ultra Deep Field (HUDF) region was discovered by an international team of astronomers using the MUSE instrument on ESO's Very Large Telescope (VLT. The discovered emission covers nearly the entire field of view -- leading the team to extrapolate that almost all of the sky is invisibly glowing with Lyman-alpha emission from the early Universe [1].

Astronomers have long been accustomed to the sky looking wildly different at different wavelengths, but the extent of the observed Lyman-alpha emission was still surprising. "Realising that the whole sky glows in optical when observing the Lyman-alpha emission from distant clouds of hydrogen was a literally eye-opening surprise," explained Kasper Borello Schmidt, a member of the team of astronomers behind this result.

"This is a great discovery!" added team member Themiya Nanayakkara. "Next time you look at the moonless night sky and see the stars, imagine the unseen glow of hydrogen: the first building block of the universe, illuminating the whole night sky."

The HUDF region the team observed is an otherwise unremarkable area in the constellation of Fornax (the Furnace), which was famously mapped by the NASA/ESA Hubble Space Telescope in 2004, when Hubble spent more than 270 hours of precious observing time looking deeper than ever before into this region of space.

The HUDF observations revealed thousands of galaxies scattered across what appeared to be a dark patch of sky, giving us a humbling view of the scale of the Universe. Now, the outstanding capabilities of MUSE have allowed us to peer even deeper. The detection of Lyman-alpha emission in the HUDF is the first time astronomers have been able to see this faint emission from the gaseous envelopes of the earliest galaxies. This composite image shows the Lyman-alpha radiation in blue superimposed on the iconic HUDF image.

MUSE, the instrument behind these latest observations, is a state-of-the-art integral field spectrograph installed on Unit Telescope 4 of the VLT at ESO's Paranal Observatory [2]. When MUSE observes the sky, it sees the distribution of wavelengths in the light striking every pixel in its detector. Looking at the full spectrum of light from astronomical objects provides us with deep insights into the astrophysical processes occurring in the Universe [3].

"With these MUSE observations, we get a completely new view on the diffuse gas 'cocoons' that surround galaxies in the early Universe," commented Philipp Richter, another member of the team.

The international team of astronomers who made these observations have tentatively identified what is causing these distant clouds of hydrogen to emit Lyman-alpha, but the precise cause remains a mystery. However, as this faint omnipresent glow is thought to be ubiquitous in the night sky, future research is expected to shed light on its origin.

"In the future, we plan to make even more sensitive measurements," concluded Lutz Wisotzki, leader of the team. "We want to find out the details of how these vast cosmic reservoirs of atomic hydrogen are distributed in space."

[1] Light travels astonishingly quickly, but at a finite speed, meaning that the light reaching Earth from extremely distant galaxies took a long time to travel, giving us a window to the past, when the Universe was much younger.

[2] Unit Telescope 4 of the VLT, Yepun, hosts a suite of exceptional scientific instruments and technologically advanced systems, including the Adaptive Optics Facility , which was recently awarded the 2018 Paul F. Forman Team Engineering Excellence Award by the American Optical Society.

[3] The Lyman-alpha radiation that MUSE observed originates from atomic electron transitions - in hydrogen atoms which radiate light with a wavelength of around 122 nanometres. As such, this radiation is fully absorbed by the Earth's atmosphere. Only red-shifted Lyman-alpha emission from extremely distant galaxies has a long enough wavelength to pass through Earth's atmosphere unimpeded and be detected using ESO's ground-based telescopes.

More information

This research was presented in a paper titled "Nearly 100% of the sky is covered by Lyman-α emission around high redshift galaxies" which was published today in the journal Nature.

The team is composed of Lutz Wisotzki (Leibniz-Institut für Astrophysik Potsdam, Germany), Roland Bacon (CRAL - CNRS, Université Claude Bernard Lyon 1, ENS de Lyon, Université de Lyon, France), Jarle Brinchmann (Universiteit Leiden, the Netherlands; Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, Portugal), Sebastiano Cantalupo (ETH Zürich, Switzerland), Philipp Richter (Universität Potsdam, Germany), Joop Schaye (Universiteit Leiden, the Netherlands), Kasper B. Schmidt (Leibniz-Institut für Astrophysik Potsdam, Germany), Tanya Urrutia (Leibniz-Institut für Astrophysik Potsdam, Germany), Peter M. Weilbacher (Leibniz-Institut für Astrophysik Potsdam, Germany), Mohammad Akhlaghi (CRAL - CNRS, Université Claude Bernard Lyon 1, ENS de Lyon, Université de Lyon, France), Nicolas Bouché (Université de Toulouse, France), Thierry Contini (Université de Toulouse, France), Bruno Guiderdoni (CRAL - CNRS, Université Claude Bernard Lyon 1, ENS de Lyon, L'Université de Lyon, France), Edmund C. Herenz (Stockholms universitet, Sweden), Hanae Inami (L'Université de Lyon, France), Josephine Kerutt (Leibniz-Institut für Astrophysik Potsdam, Germany), Floriane Leclercq (CRAL - CNRS, Université Claude Bernard Lyon 1, ENS de Lyon,L'Université de Lyon, France), Raffaella A. Marino (ETH Zürich, Switzerland), Michael Maseda (Universiteit Leiden, the Netherlands), Ana Monreal-Ibero (Instituto Astrofísica de Canarias, Spain; Universidad de La Laguna, Spain), Themiya Nanayakkara (Universiteit Leiden, the Netherlands), Johan Richard (CRAL - CNRS, Université Claude Bernard Lyon 1, ENS de Lyon,L'Université de Lyon, France), Rikke Saust (Leibniz-Institut für Astrophysik Potsdam, Germany), Matthias Steinmetz (Leibniz-Institut für Astrophysik Potsdam, Germany), and Martin Wendt (Universität Potsdam, Germany).

ESO is the foremost intergovernmental astronomy organisation in Europe and the world's most productive ground-based astronomical observatory by far. It has 16 Member States: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Ireland, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile and with Australia as a strategic partner. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its world-leading Very Large Telescope Interferometer as well as two survey telescopes, VISTA working in the infrared and the visible-light VLT Survey Telescope. ESO is also a major partner in two facilities on Chajnantor, APEX and ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre Extremely Large Telescope, the ELT, which will become "the world's biggest eye on the sky".


* Photos of MUSE -

* Photos of the VLT -


Lutz Wisotzki
Leibniz-Institut für Astrophysik Potsdam
Potsdam, Germany
Tel: +49 331 7499 532

Roland Bacon
MUSE Principal Investigator / Lyon Centre for Astrophysics Research (CRAL)
Lyon, France
Cell: +33 6 08 09 14 27

Calum Turner
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6670


Related Hydrogen Articles:

Hydrogen energy at the root of life
A team of international researchers in Germany, France and Japan is making progress on answering the question of the origin of life.
Hydrogen alarm for remote hydrogen leak detection
Tomsk Polytechnic University jointly with the University of Chemistry and Technology of Prague proposed new sensors based on widely available optical fiber to ensure accurate detection of hydrogen molecules in the air.
Preparing for the hydrogen economy
In a world first, University of Sydney researchers have found evidence of how hydrogen causes embrittlement of steels.
Hydrogen boride nanosheets: A promising material for hydrogen carrier
Researchers at Tokyo Institute of Technology, University of Tsukuba, and colleagues in Japan report a promising hydrogen carrier in the form of hydrogen boride nanosheets.
World's fastest hydrogen sensor could pave the way for clean hydrogen energy
Hydrogen is a clean and renewable energy carrier that can power vehicles, with water as the only emission.
Chemical hydrogen storage system
Hydrogen is a highly attractive, but also highly explosive energy carrier, which requires safe, lightweight and cheap storage as well as transportation systems.
Observing hydrogen's effects in metal
Microscopy technique could help researchers design safer reactor vessels or hydrogen storage tanks.
The 'Batman' in hydrogen fuel cells
In a study published in Nature on Jan. 31, researchers at the University of Science and Technology of China (USTC) report advances in the development of hydrogen fuel cells that could increase its application in vehicles, especially in extreme temperatures like cold winters.
Paving the way for more efficient hydrogen cars
Hydrogen-powered vehicles emit only water vapor from their tailpipes, offering a cleaner alternative to fossil-fuel-based transportation.
New catalyst produces cheap hydrogen
QUT chemistry researchers have discovered cheaper and more efficient materials for producing hydrogen for the storage of renewable energy that could replace current water-splitting catalysts.
More Hydrogen News and Hydrogen Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Climate Mindset
In the past few months, human beings have come together to fight a global threat. This hour, TED speakers explore how our response can be the catalyst to fight another global crisis: climate change. Guests include political strategist Tom Rivett-Carnac, diplomat Christiana Figueres, climate justice activist Xiye Bastida, and writer, illustrator, and artist Oliver Jeffers.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Speedy Beet
There are few musical moments more well-worn than the first four notes of Beethoven's Fifth Symphony. But in this short, we find out that Beethoven might have made a last-ditch effort to keep his music from ever feeling familiar, to keep pushing his listeners to a kind of psychological limit. Big thanks to our Brooklyn Philharmonic musicians: Deborah Buck and Suzy Perelman on violin, Arash Amini on cello, and Ah Ling Neu on viola. And check out The First Four Notes, Matthew Guerrieri's book on Beethoven's Fifth. Support Radiolab today at