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First Light for Band 5 at ALMA – New receivers improve ALMA’s ability to search for water in the Universe

Cover Photo : The merging galaxy system Arp 220 from ALMA and Hubble. The ALMA image includes data recording emission from water, CS and HCN in the galaxies. Credit: ALMA(ESO/NAOJ/NRAO)/NASA/ESA and The Hubble Heritage Team (STScI/AURA).

The Atacama Large Millimeter/submillimeter Array (ALMA) in Chile has begun observing in a new range of the electromagnetic spectrum. This has been made possible thanks to new receivers installed at the telescope’s antennas, which can detect radio waves with wavelengths from 1.4 to 1.8 millimetres — a range previously untapped by ALMA. This upgrade allows astronomers to detect faint signals of water in the nearby Universe.


Sulutpos.com, Munchen – ALMA observes radio waves from the Universe, at the low-energy end of the electromagnetic spectrum. With the newly installed Band 5 receivers, ALMA has now opened its eyes to a whole new section of this radio spectrum, creating exciting new observational possibilities.

The European ALMA Programme Scientist, Leonardo Testi, explains the significance: “The new receivers will make it much easier to detect water, a prerequisite for life as we know it, in our Solar System and in more distant regions of our galaxy and beyond. They will also allow ALMA to search for ionised carbon in the primordial Universe.”

Band 5 ALMA receiver. Band 5 receiver integrated with receivers for all the other current ALMA Bands (3 to 10). Credit: ALMA ESO/NAOJ/NRAO), N. Tabilo
Band 5 ALMA receiver. Band 5 receiver integrated with receivers for all the other current ALMA Bands (3 to 10).
Credit: ALMA ESO/NAOJ/NRAO), N. Tabilo

It is ALMA’s unique location, 5000 metres up on the barren Chajnantor plateau in Chile, that makes such an observation possible in the first place. As water is also present in Earth’s atmosphere, observatories in less elevated and less arid environments have much more difficulty identifying the origin of the emission coming from space. ALMA’s great sensitivity and high angular resolution mean that even faint signals of water in the local Universe can now be imaged at this wavelength [1].

The Band 5 receiver, which was developed by the Group for Advanced Receiver Development (GARD) at Onsala Space Observatory, Chalmers University of Technology, Sweden, has already been tested at the APEX telescope in the SEPIA instrument. These observations were also vital to help select suitable targets for the first receiver tests with ALMA.

One of the Band 5 receivers for ALMA. This picture shows one of the Band 5 receiver cartridges built for the Atacama Large Millimeter/submillimeter Array (ALMA). Extremely weak signals from space are collected by the ALMA antennas and focussed onto the receivers, which transform the faint radiation into an electrical signal. The Band 5 receivers detect electromagnetic radiation with wavelengths between about 1.4 and 1.8 millimetres (211 and 163 gigahertz). The receivers were originally designed, developed, and prototyped by Onsala Space Observatory’s Advanced Receiver Development group, based at Chalmers University of Technology in Gothenburg, Sweden, in collaboration with the Rutherford Appleton Laboratory, UK, and ESO, under the European Commission (EC) supported Framework Programme FP6 (ALMA Enhancement). Band 5 of ALMA achieved first fringes in July 2015 and first science observations were made in late 2016. Credit: Onsala Space Observatory/Alexey Pavolotsky
One of the Band 5 receivers for ALMA. This picture shows one of the Band 5 receiver cartridges built for the Atacama Large Millimeter/submillimeter Array (ALMA). Extremely weak signals from space are collected by the ALMA antennas and focussed onto the receivers, which transform the faint radiation into an electrical signal. The Band 5 receivers detect electromagnetic radiation with wavelengths between about 1.4 and 1.8 millimetres (211 and 163 gigahertz). The receivers were originally designed, developed, and prototyped by Onsala Space Observatory’s Advanced Receiver Development group, based at Chalmers University of Technology in Gothenburg, Sweden, in collaboration with the Rutherford Appleton Laboratory, UK, and ESO, under the European Commission (EC) supported Framework Programme FP6 (ALMA Enhancement). Band 5 of ALMA achieved first fringes in July 2015 and first science observations were made in late 2016. Credit: Onsala Space Observatory/Alexey Pavolotsky

The first production receivers were built and delivered to ALMA in the first half of 2015 by a consortium consisting of theNetherlands Research School for Astronomy (NOVA) and GARD in partnership with the National Radio Astronomy Observatory (NRAO), which contributed the local oscillator to the project. The receivers are now installed and being prepared for use by the community of astronomers.

One of the Band 5 receivers for ALMA. This picture shows one of the Band 5 receiver cartridges built for the Atacama Large Millimeter/submillimeter Array (ALMA). Extremely weak signals from space are collected by the ALMA antennas and focussed onto the receivers, which transform the faint radiation into an electrical signal. The Band 5 receivers detect electromagnetic radiation with wavelengths between about 1.4 and 1.8 millimetres (211 and 163 gigahertz). The receivers were originally designed, developed, and prototyped by Onsala Space Observatory’s Advanced Receiver Development group, based at Chalmers University of Technology in Gothenburg, Sweden, in collaboration with the Rutherford Appleton Laboratory, UK, and ESO, under the European Commission (EC) supported Framework Programme FP6 (ALMA Enhancement). Band 5 of ALMA achieved first fringes in July 2015 and the first science observations were made in late 2016. Credit: Onsala Space Observatory/B. Billade
One of the Band 5 receivers for ALMA. This picture shows one of the Band 5 receiver cartridges built for the Atacama Large Millimeter/submillimeter Array (ALMA). Extremely weak signals from space are collected by the ALMA antennas and focussed onto the receivers, which transform the faint radiation into an electrical signal. The Band 5 receivers detect electromagnetic radiation with wavelengths between about 1.4 and 1.8 millimetres (211 and 163 gigahertz). The receivers were originally designed, developed, and prototyped by Onsala Space Observatory’s Advanced Receiver Development group, based at Chalmers University of Technology in Gothenburg, Sweden, in collaboration with the Rutherford Appleton Laboratory, UK, and ESO, under the European Commission (EC) supported Framework Programme FP6 (ALMA Enhancement). Band 5 of ALMA achieved first fringes in July 2015 and the first science observations were made in late 2016. Credit: Onsala Space Observatory/B. Billade

To test the newly installed receivers observations were made of several objects including the colliding galaxies Arp 220, a massive region of star formation close to the centre of the Milky Way, and also a dusty red supergiant star approaching the supernova explosion that will end its life [2].

To process the data and check its quality, astronomers, along with technical specialists from ESO and the European ALMA Regional Centre (ARC) network, gathered at the Onsala Space Observatory in Sweden, for a “Band 5 Busy Week” hosted by the Nordic ARC node [3]. The final results have just been made freely available to the astronomical community worldwide.

Team member Robert Laing at ESO is optimistic about the prospects for ALMA Band 5 observations: “It’s very exciting to see these first results from ALMA Band 5 using a limited set of antennas. In the future, the high sensitivity and angular resolution of the full ALMA array will allow us to make detailed studies of water in a wide range of objects including forming and evolved stars, the interstellar medium and regions close to supermassive black holes.

Notes

[1] A key spectral signature of water lies in this expanded range — at a wavelength of 1.64 millimetres.

[2] The observations were performed and made possible by the ALMA Extension of Capabilities team in Chile.

[3] The ESO Band 5 Science Verification team includes: Elizabeth Humphreys, Tony Mroczkowski, Robert Laing, Katharina Immer, Hau-Yu (Baobab) Liu, Andy Biggs, Gianni Marconi and Leonardo Testi. The team working on processing the data included: Tobia Carozzi, Simon Casey, Sabine König, Ana Lopez-Sepulcre, Matthias Maercker, Iván Martí-Vidal, Lydia Moser, Sebastien Muller, Anita Richards, Daniel Tafoya and Wouter Vlemmings.

The merging galaxy system Arp 220 from ALMA and Hubble. The compound view shows a new ALMA Band 5 image of the colliding galaxy system Arp 220 (in red) on top of an image from the NASA/ESA Hubble Space Telescope (blue/green). With the newly installed Band 5 receivers, ALMA has now opened its eyes to a whole new section of this radio spectrum, creating exciting new observational possibilities and improving the telescope’s ability to search for water in the Universe. In the Hubble image, most of the light from this dramatic merging galaxy pair is hidden behind dark clouds of dust. ALMA's observations in Band 5 show a completely different view. Here, Arp 220's famous double nucleus, invisible for Hubble, is by far the brightest feature in the whole galaxy complex. In this dense, double centre, the bright emission from water and other molecules revealed by the new Band 5 receivers will give astronomers new insights into star formation and other processes in this extreme environment. This image is one of the first taken using Band 5 and was intended to verify the scientific capability of the new receivers. The ALMA image includes data recording emission from water, CS and HCN in the galaxies. Credit: ALMA(ESO/NAOJ/NRAO)/NASA/ESA and The Hubble Heritage Team (STScI/AURA)
The merging galaxy system Arp 220 from ALMA and Hubble. The compound view shows a new ALMA Band 5 image of the colliding galaxy system Arp 220 (in red) on top of an image from the NASA/ESA Hubble Space Telescope (blue/green). With the newly installed Band 5 receivers, ALMA has now opened its eyes to a whole new section of this radio spectrum, creating exciting new observational possibilities and improving the telescope’s ability to search for water in the Universe. In the Hubble image, most of the light from this dramatic merging galaxy pair is hidden behind dark clouds of dust. ALMA’s observations in Band 5 show a completely different view. Here, Arp 220’s famous double nucleus, invisible for Hubble, is by far the brightest feature in the whole galaxy complex. In this dense, double centre, the bright emission from water and other molecules revealed by the new Band 5 receivers will give astronomers new insights into star formation and other processes in this extreme environment. This image is one of the first taken using Band 5 and was intended to verify the scientific capability of the new receivers. The ALMA image includes data recording emission from water, CS and HCN in the galaxies. Credit: ALMA(ESO/NAOJ/NRAO)/NASA/ESA and The Hubble Heritage Team (STScI/AURA)

More information

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of ESO, the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).

ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile.

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, the world’s most advanced visible-light astronomical observatory and two survey telescopes.

VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

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