The first area of sky viewed as part of the Herschel-ATLAS survey. Credit: ESA / SPIRE / Herschel-ATLAS / SJ MaddoxImage A shows the first area of sky viewed as part of the Herschel-ATLAS survey. It is around 4 degrees across – 8 times the width of the Full Moon – and located in the constellation of Hydra the water snake. There are over 6000 galaxies present in this image, some seen as they were billions of years ago, and almost all so far away that they are seen by Herschel as a single point of light. Also visible as wispy structures draped across the image are diffuse clouds of dust in our own Galaxy. This image makes up around 1/30th of the total area which will be observed by Herschel-ATLAS, in which astronomers should eventually find around 250,000 galaxies. The five inset show enlarged views of the five distant galaxies whose images are being gravitationally lensed by foreground galaxies (unseen by Herschel). The distant galaxies are not only very bright, but also very red in colour in this image, showing that they are brighter at the longer wavelengths measured by the SPIRE instrument.
The effect of gravitational lensing as seen by Herschel and ground-based telescopes. Credit: ESA/NASA/JPL-Caltech/Keck/SMAImage B shows the effect of gravitational lensing as seen by Herschel and ground-based telescopes. The light from a distant galaxy (red), is warped and magnified by the presence of a foreground galaxy (blue). This makes the distant galaxy appear much brighter, seen by Herschel as the orange dot in the upper-most panels. The lensing also distorts the image observed by the Submillimeter Array (SMA), shown here in pink. The foreground galaxy is not seen by Herschel, but is observed by optical telescopes such as the W. M. Keck Observatory on Hawaii, shown in blue. The light from the distant galaxy has been travelling for 11 billion years, allowing astronomers to observe the precursors to galaxies like our own in the very early Universe. The effect of the gravitational lensing can be used to work out the structure of both galaxies, probing the formation of stars and galaxies billions of years ago and the role of mysterious Dark Matter in the relatively nearby Universe.
The light from a distant galaxy is bent and magnified by the presence of a foreground galaxy, in a process called gravitational lensing. Credit: NASA/JPL-CaltechImage C (B_LensingDiagram_DiagramOnly.jpg) shows how the light from a distant galaxy is bent and magnified by the presence of a foreground galaxy, in a process called gravitational lensing. The foreground galaxy (blue) is seen by optical telescopes, while the light from the background galaxy (red) is observed as a distorted image (pink) at far-infrared and sub-millimetre telescopes. The light from the distant galaxy has taken 11 billion years to reach us, compared with just 3 billion years for the much closer foreground galaxy.
The distant galaxy was identified as being peculiar by the Herschel Space Observatory (left) as a particularly bright object seen at far-infrared wavelengths.Credit: ESA/NASA/JPL-Caltech/Keck/SMAImage D shows how the distant galaxy was identified as being peculiar by the Herschel Space Observatory (left) as a particularly bright object seen at far-infrared wavelengths. Closer observation at higher resolution using ground-based telescopes (right) revealed that Herschel had found a gravitational lens. The foreground galaxy (blue) is seen at optical wavelengths by the W. M. Keck Observatory in Hawaii. The much longer wavelength light from the background galaxy, which is actually directly behind as seen from Earth, is magnified and distorted, as shown using the sub-millimetre observations of the Smithsonian Astrophysical Observatory's Submillimeter Array, also in Hawaii. This is just one of five gravitational lenses found in the first set of data released from the Herschel-ATLAS surve
A UK-led team using the world's largest space telescope, ESA’s Herschel Space Observatory, have discovered a new way of locating a natural phenomenon that acts like a zoom lens, allowing astronomers to peer at galaxies in the distant and early Universe. The magnification created by this phenomenon allows astronomers to see galaxies otherwise hidden from us, providing key insights into how galaxies have changed over the history of the cosmos.
Herschel - in operation for over a year in its special orbit 1.5 million km from Earth - looks at far-infrared light, which is emitted not by stars, but by the cool gas and dust from which they form.
Dr David Parker, Director of Space Science and Exploration at the UK Space Agency, which provides the UK funding for Herschel, said, “Once again, the Herschel team have pushed the boundaries and brought us another step closer to understanding the complex birth of stars and galaxies in the early Universe. As always, we’re immensely proud of the outstanding work of our UK scientists who are playing key roles in this world-leading space project. Herschel is a jewel in the UK's space programme.”
Every schoolchild is taught that light travels in straight lines – but a century ago Albert Einstein showed that gravity can cause light to bend. The effect is normally extremely small, and it is only when light passes close to a very massive object such as a galaxy containing hundreds of billions of stars that the results become easily noticeable. When light from a very distant object passes a galaxy much closer to us, its path can be bent in such a way that the image of the distant galaxy is magnified and distorted. These alignment events are called “gravitational lenses” and many have been discovered over recent decades, mainly at visible and radio wavelengths.
As with a normal glass lens the alignment is crucial, requiring the position of the lens – in this case a galaxy – to be just right. This is very rare and astronomers have to rely on chance alignments, often involving sifting through large amounts of data from telescopes. Most methods of searching for gravitational lenses have a very poor success rate with fewer than one in ten candidates typically being found to be real. Herschel’s panoramic imaging cameras have allowed astronomers to find examples of these lenses by scanning large areas of the sky in far-infrared and sub-millimetre light. These results are from the very first data taken as part of the “Herschel-ATLAS” project, the largest imaging survey conducted so far with Herschel, and are published in the prestigious scientific journal Science.
Dr Mattia Negrello, of the Open University and lead researcher of the study, explained, “Our survey of the sky looks for sources of sub-millimetre light. The big breakthrough is that we have discovered that many of the brightest sources are being magnified by lenses, which means that we no longer have to rely on the rather inefficient methods of finding lenses used at visible and radio wavelengths.”
The Herschel-ATLAS images contain thousands of galaxies, most so far away that the light has taken billions of years to reach us. Dr Negrello and his team investigated five surprisingly bright objects in this small patch of sky. Looking at the positions of these bright objects with optical telescopes on the Earth, they found galaxies that would not normally be bright at the far-infrared wavelengths observed by Herschel. This led them to suspect that the galaxies seen in visible light might be gravitational lenses magnifying much more distant galaxies seen by Herschel.
To find the true distances to the Herschel sources, Negrello and his team looked for a tell-tale signature of molecular gas. Using radio and sub-millimetre telescopes on the ground, they showed that this signature implies the galaxies are being seen as they were when the Universe was just 2–4 billion years old – less than a third of its current age. The galaxies seen by the optical telescopes are much closer, each ideally positioned to create a gravitational lens. Dr Negrello commented that “previous searches for magnified galaxies have targeted clusters of galaxies where the huge mass of the cluster makes gravitational lensing effect unavoidable. Our results show that gravitational lensing is at work in not just a few, but in all of the distant and bright galaxies seen by Herschel.”
The magnification provided by these cosmic zoom lenses allows astronomers to study much fainter galaxies, and in more detail than would otherwise be possible. They are the key to understanding how the building blocks of the Universe have changed since they were in their infancy. Professor Rob Ivison of the Royal Observatory, Edinburgh, part of the team that created the images, said “This relatively simple technique promises to unlock the secrets of how galaxies like our Milky Way formed and evolved. Not only does the lensing allow us to find them very efficiently, but it helps us peer within them to figure out how the individual pieces of the jigsaw came together, back in the mists of time”.
Dr Loretta Dunne of Nottingham University and joint-leader of the Herschel-ATLAS survey said, “What we’ve seen so far is just the tip of the iceberg. Wide area surveys are essential for finding these rare events and since Herschel has only covered one thirtieth of the entire Herschel-ATLAS area so far, we expect to discover hundreds of lenses once we have all the data. Once found, we can probe the early Universe on the same physical scales as we can in galaxies next door."
Professor Steve Eales from Cardiff University and the other leader of the survey added: “We can also use this technique to study the lenses themselves. This is exciting because 80% of the matter in the Universe is thought to be dark matter, which does not absorb, reflect or emit light and so can’t be seen directly with our telescopes. With the large number of gravitational lenses that we’ll get from our full survey, we’ll really be able to get to grips with this hidden Universe.”
Herschel - in operation for over a year in its special orbit 1.5 million km from Earth - looks at far-infrared light, which is emitted not by stars, but by the cool gas and dust from which they form.
Dr David Parker, Director of Space Science and Exploration at the UK Space Agency, which provides the UK funding for Herschel, said, “Once again, the Herschel team have pushed the boundaries and brought us another step closer to understanding the complex birth of stars and galaxies in the early Universe. As always, we’re immensely proud of the outstanding work of our UK scientists who are playing key roles in this world-leading space project. Herschel is a jewel in the UK's space programme.”
Every schoolchild is taught that light travels in straight lines – but a century ago Albert Einstein showed that gravity can cause light to bend. The effect is normally extremely small, and it is only when light passes close to a very massive object such as a galaxy containing hundreds of billions of stars that the results become easily noticeable. When light from a very distant object passes a galaxy much closer to us, its path can be bent in such a way that the image of the distant galaxy is magnified and distorted. These alignment events are called “gravitational lenses” and many have been discovered over recent decades, mainly at visible and radio wavelengths.
As with a normal glass lens the alignment is crucial, requiring the position of the lens – in this case a galaxy – to be just right. This is very rare and astronomers have to rely on chance alignments, often involving sifting through large amounts of data from telescopes. Most methods of searching for gravitational lenses have a very poor success rate with fewer than one in ten candidates typically being found to be real. Herschel’s panoramic imaging cameras have allowed astronomers to find examples of these lenses by scanning large areas of the sky in far-infrared and sub-millimetre light. These results are from the very first data taken as part of the “Herschel-ATLAS” project, the largest imaging survey conducted so far with Herschel, and are published in the prestigious scientific journal Science.
Dr Mattia Negrello, of the Open University and lead researcher of the study, explained, “Our survey of the sky looks for sources of sub-millimetre light. The big breakthrough is that we have discovered that many of the brightest sources are being magnified by lenses, which means that we no longer have to rely on the rather inefficient methods of finding lenses used at visible and radio wavelengths.”
The Herschel-ATLAS images contain thousands of galaxies, most so far away that the light has taken billions of years to reach us. Dr Negrello and his team investigated five surprisingly bright objects in this small patch of sky. Looking at the positions of these bright objects with optical telescopes on the Earth, they found galaxies that would not normally be bright at the far-infrared wavelengths observed by Herschel. This led them to suspect that the galaxies seen in visible light might be gravitational lenses magnifying much more distant galaxies seen by Herschel.
To find the true distances to the Herschel sources, Negrello and his team looked for a tell-tale signature of molecular gas. Using radio and sub-millimetre telescopes on the ground, they showed that this signature implies the galaxies are being seen as they were when the Universe was just 2–4 billion years old – less than a third of its current age. The galaxies seen by the optical telescopes are much closer, each ideally positioned to create a gravitational lens. Dr Negrello commented that “previous searches for magnified galaxies have targeted clusters of galaxies where the huge mass of the cluster makes gravitational lensing effect unavoidable. Our results show that gravitational lensing is at work in not just a few, but in all of the distant and bright galaxies seen by Herschel.”
The magnification provided by these cosmic zoom lenses allows astronomers to study much fainter galaxies, and in more detail than would otherwise be possible. They are the key to understanding how the building blocks of the Universe have changed since they were in their infancy. Professor Rob Ivison of the Royal Observatory, Edinburgh, part of the team that created the images, said “This relatively simple technique promises to unlock the secrets of how galaxies like our Milky Way formed and evolved. Not only does the lensing allow us to find them very efficiently, but it helps us peer within them to figure out how the individual pieces of the jigsaw came together, back in the mists of time”.
Dr Loretta Dunne of Nottingham University and joint-leader of the Herschel-ATLAS survey said, “What we’ve seen so far is just the tip of the iceberg. Wide area surveys are essential for finding these rare events and since Herschel has only covered one thirtieth of the entire Herschel-ATLAS area so far, we expect to discover hundreds of lenses once we have all the data. Once found, we can probe the early Universe on the same physical scales as we can in galaxies next door."
Professor Steve Eales from Cardiff University and the other leader of the survey added: “We can also use this technique to study the lenses themselves. This is exciting because 80% of the matter in the Universe is thought to be dark matter, which does not absorb, reflect or emit light and so can’t be seen directly with our telescopes. With the large number of gravitational lenses that we’ll get from our full survey, we’ll really be able to get to grips with this hidden Universe.”
For more information, please visit: Herschel-ATLAS website,(link opens in a new window)UK Herschel Website, (link opens in a new window)
2 ESA websites ESA 1(link opens in a new window), ESA 2 (link opens in a new window) and the ESA Herschel Science Centre (HSC)
2 ESA websites ESA 1(link opens in a new window), ESA 2 (link opens in a new window) and the ESA Herschel Science Centre (HSC)
Contacts:
Gemma Bessant
Media Contact
Open University
Tel: +44 (0)1908 655 596
Dr Loretta Dunne
PI of Herschel-ATLAS
The School of Physics & Astronomy
Nottingham University
Tel: +44(0)115 951 5132
Prof. Steve Eales
PI of Herschel-ATLAS
School of Physics and Astronomy
Cardiff University
Tel: +44 (0)2920 876168
Prof. Rob Ivison
UK Astronomy Technology Centre
Science and Technology Facilities Council
Royal Observatory Edinburgh
Tel: +44 (0)7970 778691
Dr Chris North
UK Herschel Outreach Officer
School of Physics and Astronomy
Cardiff University
Tel: +44 (0)2920 870 537
Notes for editors
Herschel-ATLAS:
The Herschel ATLAS (Astrophysical Terahertz Large Area Survey) is the largest Herschel open-time key project. It was awarded 600 hours of Herschel observation time to survey 550 square degrees of sky in 5 bands (110um, 170um, 250um, 350um, & 500um). It is expected to detect approximately 250,000 galaxies, from the nearby Universe out to redshifts of 3 to 4, when the Universe was only around 2 billion years old. The data used in this work, taken during the Science Demonstration Phase of the Herschel mission, covers a single 4x4 degree patch of sky, which represents about 1/30th of the total target area. The Herschel-ATLAS survey is lead by Dr Loretta Dunne, University of Nottingham, and Professor Steve Eales, Cardiff University.
Herschel:
Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. Since launch on 14th May 2009, Herschel spent several months undergoing careful tests on the performance of the instruments and calibration. This was followed by the Science Demonstration Phase: the period when the instruments were tested to their full capabilities.
To date, the mission has gone almost perfectly. The performance of the spacecraft has been shown to be well within pre-launch expectations, all three instruments (SPIRE, PACS and HIFI) are working extremely reliably, and the data from the Science Demonstration Phase is exceedingly promising. Herschel is now in a routine science phase, and will continue observing until its liquid helium coolant runs out in around two and half years. In 2009, Time Magazine voted Herschel the 7th best invention of 2009.
SPIRE:
The SPIRE instrument contains an imaging photometer (camera) and an imaging spectrometer. The camera operates in three wavelength bands centred on 250, 350 and 500 μm, and so can make images of the sky simultaneously in three sub-millimetre “colours”. SPIRE was designed and built by an international collaboration, led by Professor Matt Griffin of Cardiff University.
PACS:
PACS is an imaging camera and spectrometer covering wavelengths between 57 and 210 µm. PACS was built by a consortium of institutes and university departments from across Europe, and is led by Albrecht Poglitsch of the Max-Planck-Institute for Extraterrestrial Physics, Garching, Germany.
Other datasets:
The distances to the foreground galaxies in each case were measured using the W.M. Keck Observatory, the William Herschel Telescope, the Sloan Digital Sky Survey, and Apache Point Observatory. The distances to the more distant background galaxies was measured with the Herschel Space Observatory, combined with the Submillimeter Array, the Max-Planck Millimeter Bolometer, the Caltech Submillimeter Observatory, the Green Bank Telescope, and the Plateau de Bure Interferometer.
Herschel-ATLAS:
The Herschel ATLAS (Astrophysical Terahertz Large Area Survey) is the largest Herschel open-time key project. It was awarded 600 hours of Herschel observation time to survey 550 square degrees of sky in 5 bands (110um, 170um, 250um, 350um, & 500um). It is expected to detect approximately 250,000 galaxies, from the nearby Universe out to redshifts of 3 to 4, when the Universe was only around 2 billion years old. The data used in this work, taken during the Science Demonstration Phase of the Herschel mission, covers a single 4x4 degree patch of sky, which represents about 1/30th of the total target area. The Herschel-ATLAS survey is lead by Dr Loretta Dunne, University of Nottingham, and Professor Steve Eales, Cardiff University.
Herschel:
Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. Since launch on 14th May 2009, Herschel spent several months undergoing careful tests on the performance of the instruments and calibration. This was followed by the Science Demonstration Phase: the period when the instruments were tested to their full capabilities.
To date, the mission has gone almost perfectly. The performance of the spacecraft has been shown to be well within pre-launch expectations, all three instruments (SPIRE, PACS and HIFI) are working extremely reliably, and the data from the Science Demonstration Phase is exceedingly promising. Herschel is now in a routine science phase, and will continue observing until its liquid helium coolant runs out in around two and half years. In 2009, Time Magazine voted Herschel the 7th best invention of 2009.
SPIRE:
The SPIRE instrument contains an imaging photometer (camera) and an imaging spectrometer. The camera operates in three wavelength bands centred on 250, 350 and 500 μm, and so can make images of the sky simultaneously in three sub-millimetre “colours”. SPIRE was designed and built by an international collaboration, led by Professor Matt Griffin of Cardiff University.
PACS:
PACS is an imaging camera and spectrometer covering wavelengths between 57 and 210 µm. PACS was built by a consortium of institutes and university departments from across Europe, and is led by Albrecht Poglitsch of the Max-Planck-Institute for Extraterrestrial Physics, Garching, Germany.
Other datasets:
The distances to the foreground galaxies in each case were measured using the W.M. Keck Observatory, the William Herschel Telescope, the Sloan Digital Sky Survey, and Apache Point Observatory. The distances to the more distant background galaxies was measured with the Herschel Space Observatory, combined with the Submillimeter Array, the Max-Planck Millimeter Bolometer, the Caltech Submillimeter Observatory, the Green Bank Telescope, and the Plateau de Bure Interferometer.
UK Space Agency
The UK Space Agency is at the heart of UK efforts to explore and benefit from space. It is responsible for all strategic decisions on the UK civil space programme and provides a clear, single voice for UK space ambitions. The UK civil space programme budget is currently in the order of £312m per year – about 77% of which is the UK’s contribution to European Space Agency (ESA) projects.
Second only to the USA in space science, the UK's thriving space sector contributes £6.5bn a year to the UK economy and supports 68,000 jobs.
The UK Space Agency:
- Co-ordinates UK civil space activity
- Encourages academic research
- Supports the UK space industry
- Raises the profile of UK space activities at home and abroad
- Increases understanding of space science and its practical benefits
- Inspires our next generation of UK scientists and engineers
- Licences the launch and operation of UK spacecraft
- Promotes co-operation and participation in the European Space programme
