From ESO and ALMA: “Ancient Galaxy Megamergers”

ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

ALMA

ESO 50 Large

European Southern Observatory

25 April 2018
Axel Weiss
Max-Planck-Institut für Radioastronomie
Bonn, Germany
Tel: +49 228 525 273
Email: aweiss@mpifr-bonn.mpg.de

Carlos de Breuck
ESO
Garching, Germany
Tel: +49 89 3200 6613
Email: cdebreuc@eso.org

Richard Hook
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org

Masaaki Hiramatsu
Education and Public Outreach Officer, NAOJ Chile
Observatory
, Tokyo – Japan
Phone: +81 422 34 3630
Email: hiramatsu.masaaki@nao.ac.jp

Charles E. Blue
Public Information Officer
National Radio Astronomy Observatory Charlottesville, Virginia – USA
Phone: +1 434 296 0314
Cell phone: +1 202 236 6324
Email: cblue@nrao.edu

Valeria Foncea
Education and Public Outreach Officer
Joint ALMA Observatory Santiago – Chile
Phone: +56 2 2467 6258
Cell phone: +56 9 7587 1963
Email: valeria.foncea@alma.cl

1
The ALMA and APEX telescopes have peered deep into space — back to the time when the Universe was one tenth of its current age — and witnessed the beginnings of gargantuan cosmic pileups: the impending collisions of young, starburst galaxies. Astronomers thought that these events occurred around three billion years after the Big Bang, so they were surprised when the new observations revealed them happening when the Universe was only half that age! These ancient systems of galaxies are thought to be building the most massive structures in the known Universe: galaxy clusters.

2
This montage shows three views of the distant group of interacting and merging galaxies called SPT2349-56. The left image is a wide view from the South Pole Telescope that reveals just a bright spot.

South Pole Telescope SPTPOL. The SPT collaboration is made up of over a dozen (mostly North American) institutions, including the University of Chicago, the University of California, Berkeley, Case Western Reserve University, Harvard/Smithsonian Astrophysical Observatory, the University of Colorado Boulder, McGill University, The University of Illinois at Urbana-Champaign, University of California, Davis, Ludwig Maximilian University of Munich, Argonne National Laboratory, and the National Institute for Standards and Technology. It is funded by the National Science Foundation.

The central view is from Atacama Pathfinder Experiment (APEX) that reveals more details. The right picture is from the Atacama Large Millimeter/submillimeter Array (ALMA) and reveals that the object is actually a group of 14 merging galaxies in the process of forming a galaxy cluster. Credit: ESO/ALMA (ESO/NAOJ/NRAO)/Miller et al.

Using the Atacama Large Millimeter/submillimeter Array (ALMA) and the Atacama Pathfinder Experiment (APEX), two international teams of scientists led by Tim Miller from Dalhousie University in Canada and Yale University in the US and Iván Oteo from the University of Edinburgh, United Kingdom, have uncovered startlingly dense concentrations of galaxies that are poised to merge, forming the cores of what will eventually become colossal galaxy clusters.

Peering 90% of the way across the observable Universe, the Miller team observed a galaxy protocluster named SPT2349-56. The light from this object began travelling to us when the Universe was about a tenth of its current age.

The individual galaxies in this dense cosmic pileup are starburst galaxies and the concentration of vigorous star formation in such a compact region makes this by far the most active region ever observed in the young Universe. Thousands of stars are born there every year, compared to just one in our own Milky Way.

The Oteo team discovered a similar megamerger formed by ten dusty star-forming galaxies, nicknamed a “dusty red core” because of its very red colour, by combining observations from ALMA and the APEX.

Iván Oteo explains why these objects are unexpected: “The lifetime of dusty starbursts is thought to be relatively short, because they consume their gas at an extraordinary rate. At any time, in any corner of the Universe, these galaxies are usually in the minority. So, finding numerous dusty starbursts shining at the same time like this is very puzzling, and something that we still need to understand.”

These forming galaxy clusters were first spotted as faint smudges of light, using the South Pole Telescope and the Herschel Space Observatory.

ESA/Herschel spacecraft

Subsequent ALMA and APEX observations showed that they had unusual structure and confirmed that their light originated much earlier than expected — only 1.5 billion years after the Big Bang.

The new high-resolution ALMA observations finally revealed that the two faint glows are not single objects, but are actually composed of fourteen and ten individual massive galaxies respectively, each within a radius comparable to the distance between the Milky Way and the neighbouring Magellanic Clouds.

“These discoveries by ALMA are only the tip of the iceberg. Additional observations with the APEX telescope show that the real number of star-forming galaxies is likely even three times higher. Ongoing observations with the MUSE instrument on ESO’s VLT are also identifying additional galaxies,” comments Carlos De Breuck, ESO astronomer.

ESO MUSE on the VLT

Current theoretical and computer models suggest that protoclusters as massive as these should have taken much longer to evolve. By using data from ALMA, with its superior resolution and sensitivity, as input to sophisticated computer simulations, the researchers are able to study cluster formation less than 1.5 billion years after the Big Bang.

“How this assembly of galaxies got so big so fast is a mystery. It wasn’t built up gradually over billions of years, as astronomers might expect. This discovery provides a great opportunity to study how massive galaxies came together to build enormous galaxy clusters,” says Tim Miller, a PhD candidate at Yale University and lead author of one of the papers.

More information

This research was presented in two papers, The Formation of a Massive Galaxy Cluster Core at z = 4.3, by T. Miller et al., to appear in the journal Nature, and An Extreme Proto-cluster of Luminous Dusty Starbursts in the Early Universe, by I. Oteo et al., which appeared in the Astrophysical Journal.

The Miller team is composed of: T. B. Miller (Dalhousie University, Halifax, Canada; Yale University, New Haven, Connecticut, USA), S. C. Chapman (Dalhousie University, Halifax, Canada; Institute of Astronomy, Cambridge, UK), M. Aravena (Universidad Diego Portales, Santiago, Chile), M. L. N. Ashby (Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts, USA), C. C. Hayward (Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts, USA; Center for Computational Astrophysics, Flatiron Institute, New York, New York, USA), J. D. Vieira (University of Illinois, Urbana, Illinois, USA), A. Weiß (Max-Planck-Institut für Radioastronomie, Bonn, Germany), A. Babul (University of Victoria, Victoria, Canada) , M. Béthermin (Aix-Marseille Université, CNRS, LAM, Laboratoire d’Astrophysique de Marseille, Marseille, France), C. M. Bradford (California Institute of Technology, Pasadena, California, USA; Jet Propulsion Laboratory, Pasadena, California, USA), M. Brodwin (University of Missouri, Kansas City, Missouri, USA), J. E. Carlstrom (University of Chicago, Chicago, Illinois USA), Chian-Chou Chen (ESO, Garching, Germany), D. J. M. Cunningham (Dalhousie University, Halifax, Canada; Saint Mary’s University, Halifax, Nova Scotia, Canada), C. De Breuck (ESO, Garching, Germany), A. H. Gonzalez (University of Florida, Gainesville, Florida, USA), T. R. Greve (University College London, Gower Street, London, UK), Y. Hezaveh (Stanford University, Stanford, California, USA), K. Lacaille (Dalhousie University, Halifax, Canada; McMaster University, Hamilton, Canada), K. C. Litke (Steward Observatory, University of Arizona, Tucson, Arizona, USA), J. Ma (University of Florida, Gainesville, Florida, USA), M. Malkan (University of California, Los Angeles, California, USA) , D. P. Marrone (Steward Observatory, University of Arizona, Tucson, Arizona, USA), W. Morningstar (Stanford University, Stanford, California, USA), E. J. Murphy (National Radio Astronomy Observatory, Charlottesville, Virginia, USA), D. Narayanan (University of Florida, Gainesville, Florida, USA), E. Pass (Dalhousie University, Halifax, Canada), University of Waterloo, Waterloo, Canada), R. Perry (Dalhousie University, Halifax, Canada), K. A. Phadke (University of Illinois, Urbana, Illinois, USA), K. M. Rotermund (Dalhousie University, Halifax, Canada), J. Simpson (University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh; Durham University, Durham, UK), J. S. Spilker (Steward Observatory, University of Arizona, Tucson, Arizona, USA), J. Sreevani (University of Illinois, Urbana, Illinois, USA), A. A. Stark (Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts, USA), M. L. Strandet (Max-Planck-Institut für Radioastronomie, Bonn, Germany) and A. L. Strom (Observatories of The Carnegie Institution for Science, Pasadena, California, USA).

The Oteo team is composed of: I. Oteo (Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh, UK; ESO, Garching, Germany), R. J. Ivison (ESO, Garching, Germany; Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh, UK), L. Dunne (Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh, UK; Cardiff University, Cardiff, UK), A. Manilla-Robles (ESO, Garching, Germany; University of Canterbury, Christchurch, New Zealand), S. Maddox (Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh, UK; Cardiff University, Cardiff, UK), A. J. R. Lewis (Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh, UK), G. de Zotti (INAF-Osservatorio Astronomico di Padova, Padova, Italy), M. Bremer (University of Bristol, Tyndall Avenue, Bristol, UK), D. L. Clements (Imperial College, London, UK), A. Cooray (University of California, Irvine, California, USA), H. Dannerbauer (Instituto de Astrofíısica de Canarias, La Laguna, Tenerife, Spain; Universidad de La Laguna, Dpto. Astrofísica, La Laguna, Tenerife, Spain), S. Eales (Cardiff University, Cardiff, UK), J. Greenslade (Imperial College, London, UK), A. Omont (CNRS, Institut d’Astrophysique de Paris, Paris, France; UPMC Univ. Paris 06, Paris, France), I. Perez–Fournón (University of California, Irvine, California, USA; Instituto de Astrofísica de Canarias, La Laguna, Tenerife, Spain), D. Riechers (Cornell University, Space Sciences Building, Ithaca, New York, USA), D. Scott (University of British Columbia, Vancouver, Canada), P. van der Werf (Leiden Observatory, Leiden University, Leiden, The Netherlands), A. Weiß (Max-Planck-Institut für Radioastronomie, Bonn, Germany) and Z-Y. Zhang (Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh, UK; ESO, Garching, Germany).

See the full article here .

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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”.

ESO LaSilla
ESO/Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres.

ESO VLT
VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level.
ESO Vista Telescope

Glistening against the awesome backdrop of the night sky above ESO_s Paranal Observatory, four laser beams project out into the darkness from Unit Telescope 4 UT4 of the VLT.

ESO/Vista Telescope at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level.

ESO NTT
ESO/NTT at Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres.

ESO VLT Survey telescope
VLT Survey Telescope at Cerro Paranal with an elevation of 2,635 metres (8,645 ft) above sea level.

ALMA Array
ALMA on the Chajnantor plateau at 5,000 metres.

ESO E-ELT
ESO/E-ELT to be built at Cerro Armazones at 3,060 m.

ESO APEX
APEX Atacama Pathfinder 5,100 meters above sea level, at the Llano de Chajnantor Observatory in the Atacama desert.

Leiden MASCARA instrument, La Silla, located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)

Leiden MASCARA cabinet at ESO Cerro la Silla located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)

ESO Next Generation Transit Survey at Cerro Paranel, 2,635 metres (8,645 ft) above sea level

SPECULOOS four 1m-diameter robotic telescopes 2016 in the ESO Paranal Observatory, 2,635 metres (8,645 ft) above sea level

ESO TAROT telescope at Paranal, 2,635 metres (8,645 ft) above sea level

ESO ExTrA telescopes at Cerro LaSilla at an altitude of 2400 metres

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan.

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

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