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  • richardmitnick 9:05 am on May 31, 2021 Permalink | Reply
    Tags: "Looking deep into the universe", , , , , , HIRAX telescope in the Karoo semidesert in South Africa, , , , South Africa Radio Astronomy Observatory,   

    From Swiss Federal Institute of Technology in Zürich [ETH Zürich] [Eidgenössische Technische Hochschule Zürich](CH): “Looking deep into the universe” 

    From Swiss Federal Institute of Technology in Zürich [ETH Zürich] [Eidgenössische Technische Hochschule Zürich](CH)

    31.05.2021
    Felix Würsten

    How is matter distributed within our universe? And what is the mysterious substance known as dark energy made of? HIRAX, a new large telescope array comprising hundreds of small radio telescopes, should provide some answers. Among those instrumental in developing the system are physicists from ETH Zürich.

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    Hartebeesthoek Radio Astronomy Observatory, located west of Johannesburg South Africa.
    How the final expansion of the HIRAX telescope in the Karoo semidesert in South Africa should look once completed. (Image: Cynthia Chiang / HIRAX.)

    “It’s an exciting project,” says Alexandre Refregier, Professor of Physics at ETH Zürich, as he considers the futuristic-​looking visualisation from South Africa. The image shows a scene in the middle of the Karoo semidesert, far away from larger settlements, with rows upon rows of more than 1,000 parabolic reflectors all directed towards the same point. At first glance, one might assume this is a solar power station, but it’s actually a large radio telescope that over the coming years should provide cosmologists with new insights into the makeup and history of our universe.

    Key element: hydrogen

    HIRAX stands for Hydrogen Intensity and Real-​time Analysis eXperiment and marks the start of a new chapter in the exploration of the universe. The new large telescope will collect radio signals within a frequency range of 400 to 800 MHz. These signals will make it possible to measure the distribution of hydrogen in the universe on a large scale. “If we can use hydrogen, the most common element in the universe, to discover how matter is distributed in space, we could then draw conclusions about what dark matter and dark energy are made of,” Refregier explains.

    Dark Energy and Dark Matter are two mysterious components that together make up the vast majority of the universe. They play a major role in the formation of structures and in the universe’s accelerated expansion. But experts remain puzzled about exactly what dark energy and dark matter are made of. HIRAX should help home in on the precise nature of these two components. The researchers also hope that the new system will deliver insights into fast radio bursts and pulsars.

    Combining hundreds of individual signals

    Not only will Refregier and his team be involved in the scientific analysis of the data, the professor is also helping to develop the new system together with his postdoc Devin Crichton and engineer Thierry Viant. “HIRAX is a remarkable undertaking, not just from a scientific point of view, but also because it represents a significant technological challenge,” Refregier says. As part of their subproject in collaboration with scientists from the University of Geneva [Université de Genève](CH), the ETH researchers are developing what’s known as a digital correlator, which will combine the signals recorded by each of the approximately six-​metre telescopes. “Rather than consisting of a single large telescope, the HIRAX array is made up of numerous smaller radio telescopes that are correlated with each other,” Refregier says. “This enables us to build a telescope with a collection surface and resolution much greater than a measuring device with only one parabolic reflector.”

    Tested in Switzerland

    The physicists first tested the technology for the digital corrector in Switzerland using a pilot system. To do so, they used the two historic radio telescopes housed at the Bleien facility in the Swiss canton of Aargau. They will now use the results of these tests to develop a digital corrector capable of linking 256 reflectors. “The HIRAX telescope is being set up in stages, which allows us to develop and refine the technology we need as we go along,” Refregier says. The funding required for this subproject was recently secured.

    For their digital correlator, the ETH Zurich physicists are using high-​performance graphics processing units that were originally developed for video and gaming applications. The researchers are also breaking new ground when it comes to calibration. To synchronise the measurement signals received by the individual antennas, they use a radio signal transmitted by a drone. It is crucial to pinpoint the position of these signals so that the telescope can then provide the required precision.

    An ideal location

    It’s no accident that the HIRAX telescope is being installed in the Karoo semidesert. As a protected area, it is still largely free of disruptive signals from mobile communications antennas. “It’s actually quite ironic,” Refregier says. “On the one hand, mobile communications technology is a massive help in developing telescopes. On the other, that same technology makes life difficult for radio astronomers because mobile communications antennas transmit within similar frequency ranges.

    Another reason why the Karoo region is an ideal location is that this is also where part of the planned Square Kilometre Array will be erected.


    Once completed, this will be the world’s largest radio telescope, connecting systems in South Africa and Australia and representing yet another giant leap forward in radio astronomy. “Despite its remote position, the Karoo location is well connected by power and data lines,” Refregier says. In this respect, the undertaking presents a challenge because the new telescope will generate 6.5 terabytes of data every second. “This is why we’re going to install the digital corrector directly on site, so that the amount of data can first be reduced before it is sent somewhere else for further processing,” Refregier says.

    Opening the door for the next large-​scale project

    A collaboration among numerous other universities from different countries, the HIRAX project is also important with respect to research policy. First, it strengthens the collaboration between South Africa and Switzerland, enabling young scientists from the former to conduct research in the latter. Second, Refregier says he is grateful that the work we are doing on the development of HIRAX is opening the door to Switzerland’s participation in the Square Kilometre Array: “This means that we can do our part to ensure that Swiss universities are involved in this pioneering project and can keep pace with the latest developments in radio astronomy.”

    _____________________________________________________________________________________
    Dark Energy Survey

    ]

    The Dark Energy Survey (DES) is an international, collaborative effort to map hundreds of millions of galaxies, detect thousands of supernovae, and find patterns of cosmic structure that will reveal the nature of the mysterious dark energy that is accelerating the expansion of our Universe. DES began searching the Southern skies on August 31, 2013.

    According to Einstein’s theory of General Relativity, gravity should lead to a slowing of the cosmic expansion. Yet, in 1998, two teams of astronomers studying distant supernovae made the remarkable discovery that the expansion of the universe is speeding up. To explain cosmic acceleration, cosmologists are faced with two possibilities: either 70% of the universe exists in an exotic form, now called dark energy, that exhibits a gravitational force opposite to the attractive gravity of ordinary matter, or General Relativity must be replaced by a new theory of gravity on cosmic scales.

    DES is designed to probe the origin of the accelerating universe and help uncover the nature of dark energy by measuring the 14-billion-year history of cosmic expansion with high precision. More than 400 scientists from over 25 institutions in the United States, Spain, the United Kingdom, Brazil, Germany, Switzerland, and Australia are working on the project. The collaboration built and is using an extremely sensitive 570-Megapixel digital camera, DECam, mounted on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory, high in the Chilean Andes, to carry out the project.

    Over six years (2013-2019), the DES collaboration used 758 nights of observation to carry out a deep, wide-area survey to record information from 300 million galaxies that are billions of light-years from Earth. The survey imaged 5000 square degrees of the southern sky in five optical filters to obtain detailed information about each galaxy. A fraction of the survey time is used to observe smaller patches of sky roughly once a week to discover and study thousands of supernovae and other astrophysical transients.
    _____________________________________________________________________________________

    Dark Matter Background
    Fritz Zwicky discovered Dark Matter in the 1930s when observing the movement of the Coma Cluster., Vera Rubin a Woman in STEM denied the Nobel, some 30 years later, did most of the work on Dark Matter.

    Fritz Zwicky from http:// palomarskies.blogspot.com.


    Coma cluster via NASA/ESA Hubble.


    In modern times, it was astronomer Fritz Zwicky, in the 1930s, who made the first observations of what we now call dark matter. His 1933 observations of the Coma Cluster of galaxies seemed to indicated it has a mass 500 times more than that previously calculated by Edwin Hubble. Furthermore, this extra mass seemed to be completely invisible. Although Zwicky’s observations were initially met with much skepticism, they were later confirmed by other groups of astronomers.
    Thirty years later, astronomer Vera Rubin provided a huge piece of evidence for the existence of dark matter. She discovered that the centers of galaxies rotate at the same speed as their extremities, whereas, of course, they should rotate faster. Think of a vinyl LP on a record deck: its center rotates faster than its edge. That’s what logic dictates we should see in galaxies too. But we do not. The only way to explain this is if the whole galaxy is only the center of some much larger structure, as if it is only the label on the LP so to speak, causing the galaxy to have a consistent rotation speed from center to edge.
    Vera Rubin, following Zwicky, postulated that the missing structure in galaxies is dark matter. Her ideas were met with much resistance from the astronomical community, but her observations have been confirmed and are seen today as pivotal proof of the existence of dark matter.

    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science).


    Vera Rubin measuring spectra, worked on Dark Matter (Emilio Segre Visual Archives AIP SPL).


    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970. https://home.dtm.ciw.edu.


    _____________________________________________________________________________________

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    ETH Zurich campus
    Swiss Federal Institute of Technology in Zürich [ETH Zürich] [Eidgenössische Technische Hochschule Zürich](CH) is a public research university in the city of Zürich, Switzerland. Founded by the Swiss Federal Government in 1854 with the stated mission to educate engineers and scientists, the school focuses exclusively on science, technology, engineering and mathematics. Like its sister institution Swiss Federal Institute of Technology in Lausanne [EPFL-École Polytechnique Fédérale de Lausanne](CH) , it is part of the Swiss Federal Institutes of Technology Domain (ETH Domain)) , part of the Swiss Federal Department of Economic Affairs, Education and Research.

    The university is an attractive destination for international students thanks to low tuition fees of 809 CHF per semester, PhD and graduate salaries that are amongst the world’s highest, and a world-class reputation in academia and industry. There are currently 22,200 students from over 120 countries, of which 4,180 are pursuing doctoral degrees. In the 2021 edition of the QS World University Rankings ETH Zürich is ranked 6th in the world and 8th by the Times Higher Education World Rankings 2020. In the 2020 QS World University Rankings by subject it is ranked 4th in the world for engineering and technology (2nd in Europe) and 1st for earth & marine science.

    As of November 2019, 21 Nobel laureates, 2 Fields Medalists, 2 Pritzker Prize winners, and 1 Turing Award winner have been affiliated with the Institute, including Albert Einstein. Other notable alumni include John von Neumann and Santiago Calatrava. It is a founding member of the IDEA League and the International Alliance of Research Universities (IARU) and a member of the CESAER network.

    ETH Zürich was founded on 7 February 1854 by the Swiss Confederation and began giving its first lectures on 16 October 1855 as a polytechnic institute (eidgenössische polytechnische Schule) at various sites throughout the city of Zurich. It was initially composed of six faculties: architecture, civil engineering, mechanical engineering, chemistry, forestry, and an integrated department for the fields of mathematics, natural sciences, literature, and social and political sciences.

    It is locally still known as Polytechnikum, or simply as Poly, derived from the original name eidgenössische polytechnische Schule, which translates to “federal polytechnic school”.

    ETH Zürich is a federal institute (i.e., under direct administration by the Swiss government), whereas the University of Zürich is a cantonal institution. The decision for a new federal university was heavily disputed at the time; the liberals pressed for a “federal university”, while the conservative forces wanted all universities to remain under cantonal control, worried that the liberals would gain more political power than they already had. In the beginning, both universities were co-located in the buildings of the University of Zürich.

    From 1905 to 1908, under the presidency of Jérôme Franel, the course program of ETH Zürich was restructured to that of a real university and ETH Zürich was granted the right to award doctorates. In 1909 the first doctorates were awarded. In 1911, it was given its current name, Eidgenössische Technische Hochschule. In 1924, another reorganization structured the university in 12 departments. However, it now has 16 departments.

    ETH Zürich, EPFL (Swiss Federal Institute of Technology in Lausanne) [École polytechnique fédérale de Lausanne](CH), and four associated research institutes form the “ETH Domain” with the aim of collaborating on scientific projects.

    Reputation and ranking

    ETH Zürich is ranked among the top universities in the world. Typically, popular rankings place the institution as the best university in continental Europe and ETH Zürich is consistently ranked among the top 1-5 universities in Europe, and among the top 3-10 best universities of the world.

    Historically, ETH Zürich has achieved its reputation particularly in the fields of chemistry, mathematics and physics. There are 32 Nobel laureates who are associated with ETH Zürich, the most recent of whom is Richard F. Heck, awarded the Nobel Prize in chemistry in 2010. Albert Einstein is perhaps its most famous alumnus.

    In 2018, the QS World University Rankings placed ETH Zürich at 7th overall in the world. In 2015, ETH Zürich was ranked 5th in the world in Engineering, Science and Technology, just behind the Massachusetts Institute of Technology(US), Stanford University(US) and University of Cambridge(UK). In 2015, ETH Zürich also ranked 6th in the world in Natural Sciences, and in 2016 ranked 1st in the world for Earth & Marine Sciences for the second consecutive year.

    In 2016, Times Higher Education WorldUniversity Rankings ranked ETH Zürich 9th overall in the world and 8th in the world in the field of Engineering & Technology, just behind the Massachusetts Institute of Technology(US), Stanford University(US), California Institute of Technology(US), Princeton University(US), University of Cambridge(UK), Imperial College London(UK) and

     
  • richardmitnick 1:26 pm on July 24, 2019 Permalink | Reply
    Tags: , , , , NGC 1316, , , South Africa Radio Astronomy Observatory   

    South Africa Radio Astronomy Observatory: “South Africa’s MeerKAT discovers missing gas in distant galaxy” 

    From South Africa Radio Astronomy Observatory

    Media release

    July 22, 2019
    Kim de Boer
    SARAO Acting Head of Communications and Stakeholder Relations
    Email: kdeboer@ska.ac.za
    Tel: +27 11 442-2434
    +27 (0) 83 276 3282

    An international team of astronomers today announced the resolution of a long-standing mystery related to the formation and evolution of galaxies, by discovering vast amounts of hydrogen gas in a galaxy 60 million light years from Earth. Their work, just published in the journal Astronomy & Astrophysics, is based on observations carried out last year with the South African Radio Astronomy Observatory’s new MeerKAT telescope in the Northern Cape.

    SKA Meerkat telescope(s), 90 km outside the small Northern Cape town of Carnarvon, SA

    3
    Hydrogen gas (represented by green blobs) detected with SARAO’s MeerKAT radio telescope within and around the galaxy NGC 1316, visible at the centre of the image. The two hydrogen tails newly discovered with MeerKAT are visible in the upper and lower parts of the image (the curved arcs are added to guide the eye). Additional hydrogen clouds near NGC 1316 are also visible. The visible light image in the background is from the Fornax Deep Survey – a Dutch-Italian collaboration led by the University of Groningen and INAF – Naples – and was obtained with the VST telescope at the European Southern Observatory. (Adapted from results presented in Serra et al. 2019.)

    ESO VST telescope, at ESO’s Cerro Paranal Observatory, with an elevation of 2,635 metres (8,645 ft) above sea level

    NGC 1316, the subject of the new research (funded in part by the European Research Council) is the brightest galaxy at visible wavelengths in a nearby cluster of galaxies located in the direction of the Fornax constellation. It is also known as the radio galaxy “Fornax A”, and is the fourth brightest source of astronomical radio waves in the entire sky.

    It is clear from its irregular shape in visible light images that this peculiar galaxy formed through a collision and merger of two major galaxies a few billion years ago, followed by subsequent merging with smaller satellite galaxies. Galaxy merging is one of the cornerstones of modern cosmological theories, and examples such as NGC 1316 are of great importance because they allow astronomers to study in detail the physical processes at work during mergers, and their effect on galaxy evolution.

    A decades-long mystery is why NGC 1316 seemed to have so little hydrogen gas, the raw fuel that, present in many galaxies alongside heavier dust grains, ultimately makes up stars throughout the Universe.

    “NGC 1316 contains a very large amount of dust in its interstellar medium,” says Paolo Serra of the Italian National Institute for Astrophysics (INAF) – Observatory of Cagliari, and lead author of the new study. It has been generally understood by astronomers that this is due to the nature of the two merging galaxies: one was gargantuan and devoid of much gas or dust, while the other, ten times smaller, was similar to the Milky Way and could bring into NGC 1316 enough dust to explain the observed amount. However, it should also have brought along an even larger amount of hydrogen gas. The problem: so far the vast majority of this hydrogen had never been detected!

    “In this article,” continues Serra, “we show new radio images obtained with MeerKAT, which reveal where all that hydrogen was hiding – it’s distributed in two long, faint, gaseous tails, stretching to a large distance from the galaxy”. The radio tails were found at the same location as tails made up of stars discernible in sensitive visible light images. According to Serra, “the tails were generated by tidal forces in action during the merger. The amount of gas found is consistent with that expected based on merger theory, and on the fact that the smallest progenitor galaxy was alike the Milky Way. Thus, thanks to these observations all pieces of the puzzle are now in place, and we finally have a more precise and coherent understanding of the formation of this famous galaxy.”

    “With this beautiful piece of work, Paolo and his colleagues, among whom are several young South Africans, have significantly advanced our knowledge of the formation and evolution of galaxies,” says Dr Fernando Camilo, SARAO’s Chief Scientist. “This provides a wonderful taste of what MeerKAT will do in years to come.”

    MeerKAT, the South African precursor to the international Square Kilometre Array (SKA), consists of 64 dishes extremely sensitive to radio waves spread over a diameter of eight (8) kilometres in the Karoo. But the configuration of those 64 dishes appears peculiar at first: three quarters are located within a diameter of one (1) kilometre, with the remainder more sparsely spread farther out.

    “This was done on purpose,” explains Camilo, “to provide extra sensitivity for detecting the very faint radio signals that hydrogen atoms emit from across the Universe, at a frequency of 1420 megahertz.” “What is also remarkable is that these observations were done with the telescope in its initial commissioning phase, using only 40 of the dishes, before the inauguration in July of last year.” “Results like these,” concludes Camilo, “show that MeerKAT has begun addressing some of the key open questions in modern astrophysics, and we look forward to researchers in South Africa and from around the world joining us on a journey of scientific discovery.”

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    SKA-MPG telescope

    The South African Radio Astronomy Observatory

    The South African Radio Astronomy Observatory (SARAO), a facility of the National Research Foundation, is responsible for managing all radio astronomy initiatives and facilities in South Africa, including the MeerKAT Radio Telescope in the Karoo, and the Geodesy and VLBI activities at the HartRAO facility. SARAO also coordinates the African Very Long Baseline Interferometry Network (AVN) for the eight SKA partner countries in Africa, as well as South Africa’s contribution to the infrastructure and engineering planning for the Square Kilometre Array Radio Telescope. To maximise the return on South Africa’s investment in radio astronomy, SARAO is managing programmes to create capacity in radio astronomy science and engineering research, and the technical capacity required to support site operations.

    http://www.sarao.ac.za

     
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