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Astronomers witness assembly of galaxies in the early Universe for the first time

Astronomy News - 23 July 2015 - 9:29am

When the first galaxies started to form a few hundred million years after the Big Bang, the Universe was full of a fog of hydrogen gas. But as more and more brilliant sources — both stars and quasars powered by huge black holes — started to shine they cleared away the mist and made the Universe transparent to ultraviolet light. Astronomers call this the epoch of reionisation, but little is known about these first galaxies, and up to now they have just been seen as very faint blobs. But now new observations using the Atacama Large Millimetre/submillimetre Array (ALMA) are starting to change this.

A team of astronomers led by Roberto Maiolino from the University’s Cavendish Laboratory and Kavli Institute for Cosmology trained ALMA on galaxies that were known to be seen only about 800 million years after the Big Bang. The astronomers were not looking for the light from stars, but instead for the faint glow of ionised carbon coming from the clouds of gas from which the stars were forming. They wanted to study the interaction between a young generation of stars and the cold clumps that were assembling into these first galaxies.

They were also not looking for the extremely brilliant rare objects — such as quasars and galaxies with very high rates of star formation — that had been seen up to now. Instead they concentrated on rather less dramatic, but much more common, galaxies that reionised the Universe and went on to turn into the bulk of the galaxies that we see around us now.

From one of the galaxies — given the label BDF 3299 — ALMA could pick up a faint but clear signal from the glowing carbon. However, this glow wasn’t coming from the centre of the galaxy, but rather from one side.

“These observations enable an unprecedented understanding of the assembly process of the first galaxies formed in the Universe – for the first time we can observe and disentangle the different components contributing to the earliest phases of galaxy formation,” said Maiolino. “These observations have enabled us to test with unprecedented detail theories of galaxy formation in the early Universe.”

The astronomers think that the off-centre location of the glow is because the central clouds are being disrupted by the harsh environment created by the newly formed stars — both their intense radiation and the effects of supernova explosions — while the carbon glow is tracing fresh cold gas that is being accreted from the intergalactic medium.

By combining the new ALMA observations with computer simulations, it has been possible to understand in detail key processes occurring within the first galaxies. The effects of the radiation from stars, the survival of molecular clouds, the escape of ionising radiation and the complex structure of the interstellar medium can now be calculated and compared with observation. BDF 3299 is likely to be a typical example of the galaxies responsible for reionisation.

“We have been trying to understand the interstellar medium and the formation of the reionisation sources for many years. Finally to be able to test predictions and hypotheses on real data from ALMA is an exciting moment and opens up a new set of questions. This type of observation will clarify many of the thorny problems we have with the formation of the first stars and galaxies in the Universe,” said co-author Andrea Ferrara, from the Scuola Normale Superiore in Pisa, Italy.

“This study would have simply been impossible without ALMA, as no other instrument could reach the sensitivity and spatial resolution required,” said Maiolino. “Although this is one of the deepest ALMA observations so far it is still far from achieving its ultimate capabilities. In future ALMA will image the fine structure of primordial galaxies and trace in detail the build-up of the very first galaxies.”

The results are reported in the journal Monthly Notices of the Royal Astronomical Society

Reference:
R. Maiolino et al., “The assembly of “normal” galaxies at z∼7 probed by ALMA,” Monthly Notices of the Royal Astronomical Society (2015). 

Adapted from an ESO press release

An international team of astronomers led by the University of Cambridge have detected the most distant clouds of star-forming gas yet found in normal galaxies in the early Universe – less than one billion years after the Big Bang. The new observations will allow astronomers to start to see how the first galaxies were built up and how they cleared the cosmic fog during the era of reionisation. This is the first time that such galaxies have been seen as more than just faint blobs.

For the first time we can observe and disentangle the different components contributing to the earliest phases of galaxy formationRoberto MaiolinoESO/R. MaiolinoThe central object is a very distant galaxy, labelled BDF 3299. The bright red cloud just to the lower left is the ALMA detection of a vast cloud of material that is in the process of assembling the very young galaxy


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YesRelated Links: Atacama Large Millimeter/submillimeter Array (ALMA)

Quantum of solace – information can be rescued from a black hole

Astronomy News - 23 July 2015 - 9:28am

The weirdness of quantum teleportation offers a solution for getting information out of a black hole, should you have dropped something in there









$100m project uses world’s best radio telescopes to find aliens

Astronomy News - 23 July 2015 - 9:26am

A Russian billionaire has teamed up with a host of famous names, including Stephen Hawking, to listen for aliens in the million nearest star systems









Vibrating stars could reveal elusive ripples in space-time

Astronomy News - 23 July 2015 - 9:26am
Stars vibrate like musical instruments, a property that tells us about their insides – and that could reveal gigantic gravitational waves









Search for extraterrestrial intelligence gets a $100-million boost

Astronomy News - 23 July 2015 - 9:24am

Search for extraterrestrial intelligence gets a $100-million boost

Nature 523, 7561 (2015). http://www.nature.com/doifinder/10.1038/nature.2015.18016

Author: Zeeya Merali

Russian billionaire Yuri Milner announces most comprehensive hunt for alien life.

Vibrant Pluto stuns scientists

Astronomy News - 23 July 2015 - 9:24am

Vibrant Pluto stuns scientists

Nature 523, 7561 (2015). http://www.nature.com/doifinder/10.1038/523389a

Author: Alexandra Witze

Mission seeking clues to early Solar System finds a world made anew.

Astronomy: Total eclipse of rare twin stars

Astronomy News - 23 July 2015 - 9:22am

Astronomy: Total eclipse of rare twin stars

Nature 523, 7561 (2015). doi:10.1038/523384d

Amateur and professional astronomers have spotted a rare pair of stars in which one completely eclipses the other as they orbit each other.A team led by Heather Campbell at the University of Cambridge, UK, analysed data from the European Space Agency's Gaia satellite and

More mountains found in Pluto heart

Astronomy News - 23 July 2015 - 9:21am

The latest images from Nasa's New Horizons probe reveal another mountain range on Pluto.

Philae may have moved – and Rosetta will start to look south

Astronomy News - 22 July 2015 - 9:09am

Philae has stopped phoning home and its parents are worried. Meanwhile, communication is getting more complicated as the Rosetta orbiter moves on to the comet's south









Philae Comet lander falls silent

Astronomy News - 21 July 2015 - 9:05am

The Philae comet lander has fallen silent, according to scientists working on the European Rosetta mission.

Preparing to build ESA's Jupiter mission

Astronomy News - 20 July 2015 - 3:31pm

Airbus Defence & Space in France has been selected as the prime industrial contractor for ESA's JUICE mission to Jupiter and its icy moons.

NASA’s New Horizons Discovers Frozen Plains in the Heart of Pluto’s ‘Heart’

Astronomy News - 20 July 2015 - 3:30pm
In the latest data from NASA’s New Horizons spacecraft, a new close-up image of Pluto reveals a vast, craterless plain that appears to be no more than 100 million years old, and is possibly still being shaped by geologic processes.

Gaia satellite and amateur astronomers spot one in a billion star

Astronomy News - 20 July 2015 - 3:28pm

An international team of researchers, with the assistance of amateur astronomers, have discovered a unique binary star system: the first known such system where one star completely eclipses the other. It is a type of two-star system known as a Cataclysmic Variable, where one super dense white dwarf star is stealing gas from its companion star, effectively ‘cannibalising’ it.

The system could also be an important laboratory for studying ultra-bright supernova explosions, which are a vital tool for measuring the expansion of the Universe. Details of the new research will be published in the journal Monthly Notices of the Royal Astronomical Society.

The system, named Gaia14aae, is located about 730 light years away in the Draco constellation. It was discovered by the European Space Agency’s Gaia satellite in August 2014 when it suddenly became five times brighter over the course of a single day.

Astronomers led by the University of Cambridge analysed the information from Gaia and determined that the sudden outburst was due to the fact that the white dwarf – which is so dense that a teaspoonful of material from it would weigh as much as an elephant – is devouring its larger companion.

Additional observations of the system made by the Center for Backyard Astrophysics (CBA), a collaboration of amateur and professional astronomers, found that the system is a rare eclipsing binary, where one star passes directly in front of the other, completely blocking it out when viewed from Earth. The two stars are tightly orbiting each other, so a total eclipse occurs roughly every 50 minutes.

“It’s rare to see a binary system so well-aligned” said Dr Heather Campbell of Cambridge’s Institute of Astronomy, who led the follow-up campaign for Gaia14aae. “Because of this, we can measure the system with great precision in order to figure out what these systems are made of and how they evolved. It’s a fascinating system – there’s a lot to be learned from it.”

Using spectroscopy from the William Herschel Telescope in the Canary Islands, Campbell and her colleagues found that Gaia14aae contains large amounts of helium, but no hydrogen, which is highly unusual as hydrogen is the most common element in the Universe. The lack of hydrogen allowed them to classify Gaia14aae as a very rare type of system known as an AM Canum Venaticorum (AM CVn), a type of Cataclysmic Variable system where both stars have lost all of their hydrogen. This is the first known AM CVn system where one star totally eclipses the other.

“It’s really cool that the first time that one of these systems was discovered to have one star completely eclipsing the other, that it was amateur astronomers who made the discovery and alerted us,” said Campbell. “This really highlights the vital contribution that amateur astronomers make to cutting edge scientific research.”

AM CVn systems consist of a small and hot white dwarf star which is devouring its larger companion. The gravitational effects from the hot and superdense white dwarf are so strong that it has forced the companion star to swell up like a massive balloon and move towards it.

The companion star is about 125 times the volume of our sun, and towers over the tiny white dwarf, which is about the size of the Earth – this is similar to comparing a hot air balloon and a marble. However, the companion star is lightweight, weighing in at only one percent of the white dwarf’s mass.

AM CVn systems are prized by astronomers, as they could hold the key to one of the greatest mysteries in modern astrophysics: what causes Ia supernova explosions? This type of supernova, which occurs in binary systems, is important in astrophysics as their extreme brightness makes them an important tool to measure the expansion of the Universe.

In the case of Gaia14aae, it’s not known whether the two stars will collide and cause a supernova explosion, or whether the white dwarf will completely devour its companion first.

“Every now and then, these sorts of binary systems may explode as supernovae, so studying Gaia14aae helps us understand the brightest explosions in the Universe,” said Dr Morgan Fraser of the Institute of Astronomy.

“This is an exquisite system: a very rare type of binary system in which the component stars complete orbits faster than the minute hand of a clock, oriented so that one eclipses the other,” said Professor Tom Marsh of the University of Warwick. “We will be able to measure their sizes and masses to a higher accuracy than any similar system; it whets the appetite for the many new discoveries I expect from the Gaia satellite.”

“This is an awesome first catch for Gaia, but we want it to be the first of many,” said the Institute of Astronomy’s Dr Simon Hodgkin, who is leading the search for more transients in Gaia data. “Gaia has already found hundreds of transients in its first few months of operation, and we know there are many more out there for us to find.”

Gaia’s mission, funded by the European Space Agency and involving scientists from across Europe, is to make the largest, most precise, three-dimensional map of the Milky Way ever attempted. During its five-year mission, which began in late 2013, Gaia’s billion-pixel camera will detect and very accurately measure the motion of stars in their orbit around the centre of the galaxy. It will observe each of the billion stars about a hundred times, helping us to understand the origin and evolution of the Milky Way.

The research was supported by ESA Gaia, DPAC, and the DPAC Photometric Science Alerts Team. The DPAC is funded by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.

The follow-up campaign used several professional telescopes, including those located in the Canary Islands, where observing time was made available through the International Time Program.


Reference 
Campbell, HC et al, Total eclipse of the heart: The AM CVn Gaia14aae / ASSASN-14cn, Monthly Notices of the Royal Astronomical Society (2015). 

The Gaia satellite has discovered a unique binary system where one star is ‘eating’ the other, but neither star has any hydrogen, the most common element in the Universe. The system could be an important tool for understanding how binary stars might explode at the end of their lives.

It’s a fascinating system – there’s a lot to be learned from itHeather CampbellMarisa Grove/Institute of AstronomyArtist’s impression of Gaia14aae


The text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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Cambridge scientists receive Royal Society awards

Astronomy News - 20 July 2015 - 3:26pm

The Royal Society, the UK’s independent academy for science, has announced the recipients of its 2015 Awards, Medals and Prize Lectures. The scientists receive the awards in recognition of their achievements in a wide variety of fields of research. The recipients from the University of Cambridge are:

Professor George Efstathiou FRS (Institute of Astronomy) receives the Hughes Medal for many outstanding contributions to our understanding of the early Universe, in particular his pioneering computer simulations, observations of galaxy clustering and studies of the fluctuations in the cosmic microwave background.

Professor Benjamin Simons (Wellcome Trust/Cancer Research UK Gurdon Institute, Cavendish Laboratory) receives the Gabor Medal for his work analysing stem cell lineages in development, tissue homeostasis and cancer, revolutionising our understanding of stem cell behaviour in vivo.

Professor Russell Cowburn FRS (Department of Physics) receives the Clifford Paterson Medal and Lecture for his remarkable academic, technical and commercial achievements in nano-magnetics.

Dr Madan Babu Mohan (MRC Laboratory of Molecular Biology) receives the Francis Crick Medal and Lecture for his major and widespread contributions to computational biology.

View the full list of recipients.

Four Cambridge scientists have been recognised by the Royal Society for their achievements in research.


The text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

Vibrating stars could reveal elusive ripples in space-time

Astronomy News - 20 July 2015 - 3:25pm
Stars vibrate like musical instruments, a property that tells us about their insides – and that could reveal gigantic gravitational waves









New Horizons team baffled by discovery of icy plains on Pluto

Astronomy News - 20 July 2015 - 3:25pm
Data downloaded from NASA's New Horizons spacecraft in the past few days has revealed strange terrain, a large atmosphere and yet more mysteries on Pluto









Probe zooms into Pluto's plains

Astronomy News - 20 July 2015 - 3:07pm

The American space agency's New Horizons probe returns further images of Pluto that include a view of the dwarf planet's strange icy plains.

Hawking backs new search for aliens

Astronomy News - 20 July 2015 - 3:06pm

Prof Stephen Hawking launches a new effort to answer the question of whether there is life elsewhere in space.

Rosetta preparing for perihelion

Astronomy News - 16 July 2015 - 9:23am

Rosetta's investigations of its comet are continuing as the mission teams count down the last month to perihelion – the closest point to the Sun along the comet's orbit – when the comet's activity is expected to be at its highest.

Jupiter Twin Discovered Around Solar Twin

Astronomy News - 16 July 2015 - 9:21am
An international group of astronomers has used the ESO 3.6-metre telescope to identify a planet just like Jupiter orbiting at the same distance from a Sun-like star, HIP 11915. According to current theories, the formation of Jupiter-mass planets plays an important role in shaping the architecture of planetary systems. The existence of a Jupiter-mass planet in a Jupiter-like orbit around a Sun-like star opens the possibility that the system of planets around this star may be similar to our own Solar System. HIP 11915 is about the same age as the Sun and, furthermore, its Sun-like composition suggests that there may also be rocky planets orbiting closer to the star.