Space

Herschel Space Observatory’s far infrared detection — makes previously unseen distant galaxies visible — and gives us a better picture of the Universe as it was 10 billion years ago

© 2016 Peter Free

Citation — to press release

Robert Massey and Anita Heward, Space Team Discovers Universe is Self-Cleaning, Royal Astronomical Society (29 June 2016)

The press release’s composite image contains 6000 dusty galaxies

According to the Royal Astronomical Society, the entire Herschel Space Observatory survey — of which the press release picture is only a fraction — contains roughly 500,000 dusty galaxies, some as they were 10 billion plus years ago.

From the press release:

An international team of astronomers today (29 June) released a gazetteer of the hidden universe, which reveals the unseen sources of energy found over the last 12 billion years of cosmic history.

About half of the light emitted by stars and galaxies is absorbed by interstellar grains, tiny solid particles that are found everywhere in the space between the stars. The missing fifty per cent has been a huge obstacle for astronomers trying to understand the births and lives of galaxies.

When the European Space Agency (ESA) Herschel Space Observatory launched in 2009 it meant that, for the first time, it was possible to track down this hidden energy. The missing light is re-emitted by the dust grains into far-infrared radiation, detected by the Herschel telescope.

For the last seven years, an international team of over 100 astronomers has been analysing the images from the largest Herschel survey, named the Herschel Astrophysical Terahertz Large Area Survey (the Herschel ATLAS). Today sees the release of their first catalogues of the hidden universe.

The most distant galaxies in the survey are being seen as they were 12 billion years ago, only shortly after the Big Bang. They are so dusty that they are virtually impossible to detect with standard telescopes and are often gravitationally magnified by intervening galaxies. These early systems are the distant ancestors of galaxies like our own.

The team has shown that even only one billion years in the past, a small fraction of the age of the universe, galaxies were forming stars faster and contained more dust than galaxies today.

According to Dr Nathan Bourne . . . “We were surprised to find that we didn’t need to look far in the past to see signs of galaxy evolution. Our results show that the reason for this evolution is that galaxies used to contain more dust and gas in the past, and the universe is gradually becoming cleaner as the dust is used up.”

Dr Loretta Dunne . . . adds:

“Before Herschel we only knew of a few hundred such dusty sources in the distant universe and we could only effectively ‘see’ them in black and white.

“Herschel, with its five filters, has given us the equivalent of technicolour, and the colours of the galaxies tell us about their distances and temperatures. So now we have half a million galaxies we can use to map out the hidden star formation in the universe.”

© 2016 Robert Massey and Anita Heward, Space Team Discovers Universe is Self-Cleaning, Royal Astronomical Society (29 June 2016) (extracts)

The moral? — Sometimes we need to see something to be adequately impressed

Adult or not.