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  • richardmitnick 9:48 pm on November 28, 2022 Permalink | Reply
    Tags: "Astronomers develop novel way to ‘see’ first stars through fog of early Universe", "REACH": Radio Experiment for the Analysis of Cosmic Hydrogen, "Seeing" through the fog of the early Universe and detect light from the first stars and galaxies., , , , Because of gravity the elements eventually came together and the conditions were right for nuclear fusion which is what formed the first stars., , , Observing the birth of the first stars and galaxies has been a goal of astronomers for decades., The signal that astronomers aim to detect is expected to be approximately one hundred thousand times weaker than other radio signals coming also from the sky., The Square Kilometre Array (SKA),   

    From The University of Cambridge (UK) Cavendish Laboratory – Department of Physics : “Astronomers develop novel way to ‘see’ first stars through fog of early Universe” 

    From The University of Cambridge (UK) Cavendish Laboratory – Department of Physics

    U Cambridge bloc

    7.21.22 [Just found this.]
    Jacqueline Garget
    External Affairs and Communications team
    The University of Cambridge (UK)
    jg533@cam.ac.uk

    1
    Artist’s impression of stars springing up out of the darkness. Credit: NASA/JPL-Caltech.

    A team of astronomers has developed a method that will allow them to ‘see’ through the fog of the early Universe and detect light from the first stars and galaxies.

    The researchers, led by the University of Cambridge, have developed a methodology that will allow them to observe and study the first stars through the clouds of hydrogen that filled the Universe about 378,000 years after the Big Bang.

    Observing the birth of the first stars and galaxies has been a goal of astronomers for decades, as it will help explain how the Universe evolved from the emptiness after the Big Bang to the complex realm of celestial objects we observe today, 13.8 billion years later.

    The Square Kilometre Array (SKA) – a next-generation telescope due to be completed by the end of the decade – will likely be able to make images of the earliest light in the Universe, but for current telescopes the challenge is to detect the cosmological signal of the stars through the thick hydrogen clouds.







    The signal that astronomers aim to detect is expected to be approximately one hundred thousand times weaker than other radio signals coming also from the sky – for example, radio signals originating in our own galaxy.

    Using a radio telescope itself introduces distortions to the signal received, which can completely obscure the cosmological signal of interest. This is considered an extreme observational challenge in modern radio cosmology. Such instrument-related distortions are commonly blamed as the major bottleneck in this type of observation.

    Now the Cambridge-led team has developed a methodology to see through the primordial clouds and other sky noise signals, avoiding the detrimental effect of the distortions introduced by the radio telescope. Their methodology, part of the REACH (Radio Experiment for the Analysis of Cosmic Hydrogen) experiment, will allow astronomers to observe the earliest stars through their interaction with the hydrogen clouds, in the same way we would infer a landscape by looking at shadows in the fog.

    Their method will improve the quality and reliability of observations from radio telescopes looking at this unexplored key time in the development of the Universe. The first observations from REACH are expected later this year.

    The results are reported today in the journal Nature Astronomy [below].

    “At the time when the first stars formed, the Universe was mostly empty and composed mostly of hydrogen and helium,” said Dr Eloy de Lera Acedo from Cambridge’s Cavendish Laboratory, the paper’s lead author.

    He added: “Because of gravity, the elements eventually came together and the conditions were right for nuclear fusion, which is what formed the first stars. But they were surrounded by clouds of so-called neutral hydrogen, which absorb light really well, so it’s hard to detect or observe the light behind the clouds directly.”

    In 2018, another research group (running the ‘Experiment to Detect the Global Epoch of Reionization Signature’ – or EDGES) published a result that hinted at a possible detection of this earliest light, but astronomers have been unable to repeat the result – leading them to believe that the original result may have been due to interference from the telescope being used.

    “The original result would require new physics to explain it, due to the temperature of the hydrogen gas, which should be much cooler than our current understanding of the Universe would allow. Alternatively, an unexplained higher temperature of the background radiation – typically assumed to be the well-known Cosmic Microwave Background – could be the cause” said de Lera Acedo.

    He added: “If we can confirm that the signal found in that earlier experiment really was from the first stars, the implications would be huge.”

    In order to study this period in the Universe’s development, often referred to as the Cosmic Dawn, astronomers study the 21-centimetre line – an electromagnetic radiation signature from hydrogen in the early Universe.

    Dark Energy Camera Enables Astronomers a Glimpse at the Cosmic Dawn. Credit: The National Astronomical Observatory of Japan (国立天文台](JP).

    They look for a radio signal that measures the contrast between the radiation from the hydrogen and the radiation behind the hydrogen fog.

    The methodology developed by de Lera Acedo and his colleagues uses Bayesian statistics to detect a cosmological signal in the presence of interference from the telescope and general noise from the sky, so that the signals can be separated.

    To do this, state-of-the-art techniques and technologies from different fields have been required.

    The researchers used simulations to mimic a real observation using multiple antennas, which improves the reliability of the data – earlier observations have relied on a single antenna.

    “Our method jointly analyses data from multiple antennas and across a wider frequency band than equivalent current instruments. This approach will give us the necessary information for our Bayesian data analysis,” said de Lera Acedo.

    He added: “In essence, we forgot about traditional design strategies and instead focused on designing a telescope suited to the way we plan to analyze the data – something like an inverse design. This could help us measure things from the Cosmic Dawn and into the epoch of reionization, when hydrogen in the Universe was reionized.”

    Epoch of Reionization and first stars. Credit: California Institute of Technology.

    The telescope’s construction is currently being finalized at the Karoo radio reserve in South Africa, a location chosen for its excellent conditions for radio observations of the sky. It is far away from human-made radio frequency interference, for example television and FM radio signals.

    The REACH team of over 30 researchers is multidisciplinary and distributed worldwide, with experts in fields such as theoretical and observational cosmology, antenna design, radio frequency instrumentation, numerical modelling, digital processing, big data and Bayesian statistics. REACH is co-led by the University of Stellenbosch in South Africa.

    Professor de Villiers, co-lead of the project at the University of Stellenbosch in South Africa said: “Although the antenna technology used for this instrument is rather simple, the harsh and remote deployment environment, and the strict tolerances required in the manufacturing, make this a very challenging project to work on.”

    He added: “We are extremely excited to see how well the system will perform, and have full confidence we’ll make that elusive detection.”

    The Big Bang and very early times of the Universe are well understood epochs, thanks to studies of the Cosmic Microwave Background (CMB) radiation.

    Even better understood is the late and widespread evolution of stars and other celestial objects. But the time of formation of the first light in the Cosmos is a fundamental missing piece in the puzzle of the history of the Universe.

    The research was supported by the Kavli Institute for Cosmology in Cambridge (UK), the National Research Foundation (South Africa), the Cambridge-Africa ALBORADA trust (UK) and the Science and Technology Facilities Council (STFC), part of UK Research and Innovation (UKRI).

    Science paper:
    Nature Astronomy

    See the full article here .

    Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”.

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    2

    The Cavendish Laboratory is the Department of Physics at the University of Cambridge, and is part of the School of Physical Sciences. The laboratory was opened in 1874 on the New Museums Site as a laboratory for experimental physics and is named after the British chemist and physicist Henry Cavendish. The laboratory has had a huge influence on research in the disciplines of physics and biology.

    As of 2019, 30 Cavendish researchers have won Nobel Prizes. Notable discoveries to have occurred at the Cavendish Laboratory include the discovery of the electron, neutron, and structure of DNA.

    The Cavendish Laboratory was initially located on the New Museums Site, Free School Lane, in the centre of Cambridge. It is named after British chemist and physicist Henry Cavendish for contributions to science and his relative William Cavendish, 7th Duke of Devonshire, who served as chancellor of the university and donated funds for the construction of the laboratory.

    Professor James Clerk Maxwell, the developer of electromagnetic theory, was a founder of the laboratory and the first Cavendish Professor of Physics. The Duke of Devonshire had given to Maxwell, as head of the laboratory, the manuscripts of Henry Cavendish’s unpublished Electrical Works. The editing and publishing of these was Maxwell’s main scientific work while he was at the laboratory. Cavendish’s work aroused Maxwell’s intense admiration and he decided to call the Laboratory (formerly known as the Devonshire Laboratory) the Cavendish Laboratory and thus to commemorate both the Duke and Henry Cavendish.

    Physics

    Several important early physics discoveries were made here, including the discovery of the electron by J.J. Thomson (1897); the Townsend discharge by John Sealy Townsend and the development of the cloud chamber by C.T.R. Wilson.

    Ernest Rutherford became Director of the Cavendish Laboratory in 1919. Under his leadership the neutron was discovered by James Chadwick in 1932, and in the same year the first experiment to split the nucleus in a fully controlled manner was performed by students working under his direction; John Cockcroft and Ernest Walton.

    Physical chemistry

    Physical Chemistry (originally the department of Colloid Science led by Eric Rideal) had left the old Cavendish site, subsequently locating as the Department of Physical Chemistry (under RG Norrish) in the then new chemistry building with the Department of Chemistry (led by Lord Todd) in Lensfield Road: both chemistry departments merged in the 1980s.

    Nuclear physics

    In World War II the laboratory carried out research for the MAUD Committee, part of the British Tube Alloys project of research into the atomic bomb. Researchers included Nicholas Kemmer, Alan Nunn May, Anthony French, Samuel Curran and the French scientists including Lew Kowarski and Hans von Halban. Several transferred to Canada in 1943; the Montreal Laboratory and some later to the Chalk River Laboratories. The production of plutonium and neptunium by bombarding uranium-238 with neutrons was predicted in 1940 by two teams working independently: Egon Bretscher and Norman Feather at the Cavendish and Edwin M. McMillan and Philip Abelson at Berkeley Radiation Laboratory at The University of California-Berkeley.

    Biology

    The Cavendish Laboratory has had an important influence on biology, mainly through the application of X-ray crystallography to the study of structures of biological molecules. Francis Crick already worked in the Medical Research Council Unit, headed by Max Perutz and housed in the Cavendish Laboratory, when James Watson came from the United States and they made a breakthrough in discovering the structure of DNA. For their work while in the Cavendish Laboratory, they were jointly awarded the Nobel Prize in Physiology or Medicine in 1962, together with Maurice Wilkins of King’s College London (UK), himself a graduate of St. John’s College, Cambridge.

    The discovery was made on 28 February 1953; the first Watson/Crick paper appeared in Nature on 25 April 1953. Sir Lawrence Bragg, the director of the Cavendish Laboratory, where Watson and Crick worked, gave a talk at Guy’s Hospital Medical School in London on Thursday 14 May 1953 which resulted in an article by Ritchie Calder in The News Chronicle of London, on Friday 15 May 1953, entitled Why You Are You. Nearer Secret of Life. The news reached readers of The New York Times the next day; Victor K. McElheny, in researching his biography, Watson and DNA: Making a Scientific Revolution, found a clipping of a six-paragraph New York Times article written from London and dated 16 May 1953 with the headline Form of `Life Unit’ in Cell Is Scanned. The article ran in an early edition and was then pulled to make space for news deemed more important. (The New York Times subsequently ran a longer article on 12 June 1953). The Cambridge University undergraduate newspaper Varsity also ran its own short article on the discovery on Saturday 30 May 1953. Bragg’s original announcement of the discovery at a Solvay Conference on proteins in Belgium on 8 April 1953 went unreported by the British press.

    Sydney Brenner, Jack Dunitz, Dorothy Hodgkin, Leslie Orgel, and Beryl M. Oughton, were some of the first people in April 1953 to see the model of the structure of DNA, constructed by Crick and Watson; at the time they were working at The University of Oxford (UK)’s Chemistry Department. All were impressed by the new DNA model, especially Brenner who subsequently worked with Crick at Cambridge in the Cavendish Laboratory and the new Laboratory of Molecular Biology. According to the late Dr. Beryl Oughton, later Rimmer, they all travelled together in two cars once Dorothy Hodgkin announced to them that they were off to Cambridge to see the model of the structure of DNA. Orgel also later worked with Crick at The Salk Institute for Biological Studies.

    U Cambridge Campus

    The University of Cambridge (UK) [legally The Chancellor, Masters, and Scholars of the University of Cambridge] is a collegiate public research university in Cambridge, England. Founded in 1209 Cambridge is the second-oldest university in the English-speaking world and the world’s fourth-oldest surviving university. It grew out of an association of scholars who left the University of Oxford (UK) after a dispute with townsfolk. The two ancient universities share many common features and are often jointly referred to as “Oxbridge”.

    Cambridge is formed from a variety of institutions which include 31 semi-autonomous constituent colleges and over 150 academic departments, faculties and other institutions organized into six schools. All the colleges are self-governing institutions within the university, each controlling its own membership and with its own internal structure and activities. All students are members of a college. Cambridge does not have a main campus and its colleges and central facilities are scattered throughout the city. Undergraduate teaching at Cambridge is organized around weekly small-group supervisions in the colleges – a feature unique to the Oxbridge system. These are complemented by classes, lectures, seminars, laboratory work and occasionally further supervisions provided by the central university faculties and departments. Postgraduate teaching is provided predominantly centrally.

    Cambridge University Press a department of the university is the oldest university press in the world and currently the second largest university press in the world. Cambridge Assessment also a department of the university is one of the world’s leading examining bodies and provides assessment to over eight million learners globally every year. The university also operates eight cultural and scientific museums, including the Fitzwilliam Museum, as well as a botanic garden. Cambridge’s libraries – of which there are 116 – hold a total of around 16 million books, around nine million of which are in Cambridge University Library, a legal deposit library. The university is home to – but independent of – the Cambridge Union – the world’s oldest debating society. The university is closely linked to the development of the high-tech business cluster known as “Silicon Fe”. It is the central member of Cambridge University Health Partners, an academic health science centre based around the Cambridge Biomedical Campus.

    By both endowment size and consolidated assets Cambridge is the wealthiest university in the United Kingdom. In the fiscal year ending 31 July 2019, the central university – excluding colleges – had a total income of £2.192 billion of which £592.4 million was from research grants and contracts. At the end of the same financial year the central university and colleges together possessed a combined endowment of over £7.1 billion and overall consolidated net assets (excluding “immaterial” historical assets) of over £12.5 billion. It is a member of numerous associations and forms part of the ‘golden triangle’ of English universities.

    Cambridge has educated many notable alumni including eminent mathematicians; scientists; politicians; lawyers; philosophers; writers; actors; monarchs and other heads of state. As of October 2020, 121 Nobel laureates; 11 Fields Medalists; 7 Turing Award winners; and 14 British prime ministers have been affiliated with Cambridge as students; alumni; faculty or research staff. University alumni have won 194 Olympic medals.

    History

    By the late 12th century, the Cambridge area already had a scholarly and ecclesiastical reputation due to monks from the nearby bishopric church of Ely. However, it was an incident at Oxford which is most likely to have led to the establishment of the university: three Oxford scholars were hanged by the town authorities for the death of a woman without consulting the ecclesiastical authorities who would normally take precedence (and pardon the scholars) in such a case; but were at that time in conflict with King John. Fearing more violence from the townsfolk scholars from the University of Oxford started to move away to cities such as Paris; Reading; and Cambridge. Subsequently enough scholars remained in Cambridge to form the nucleus of a new university when it had become safe enough for academia to resume at Oxford. In order to claim precedence, it is common for Cambridge to trace its founding to the 1231 charter from Henry III granting it the right to discipline its own members (ius non-trahi extra) and an exemption from some taxes; Oxford was not granted similar rights until 1248.

    A bull in 1233 from Pope Gregory IX gave graduates from Cambridge the right to teach “everywhere in Christendom”. After Cambridge was described as a studium generale in a letter from Pope Nicholas IV in 1290 and confirmed as such in a bull by Pope John XXII in 1318 it became common for researchers from other European medieval universities to visit Cambridge to study or to give lecture courses.

    Foundation of the colleges

    The colleges at the University of Cambridge were originally an incidental feature of the system. No college is as old as the university itself. The colleges were endowed fellowships of scholars. There were also institutions without endowments called hostels. The hostels were gradually absorbed by the colleges over the centuries; but they have left some traces, such as the name of Garret Hostel Lane.

    Hugh Balsham, Bishop of Ely, founded Peterhouse – Cambridge’s first college in 1284. Many colleges were founded during the 14th and 15th centuries but colleges continued to be established until modern times. There was a gap of 204 years between the founding of Sidney Sussex in 1596 and that of Downing in 1800. The most recently established college is Robinson built in the late 1970s. However, Homerton College only achieved full university college status in March 2010 making it the newest full college (it was previously an “Approved Society” affiliated with the university).

    In medieval times many colleges were founded so that their members would pray for the souls of the founders and were often associated with chapels or abbeys. The colleges’ focus changed in 1536 with the Dissolution of the Monasteries. Henry VIII ordered the university to disband its Faculty of Canon Law and to stop teaching “scholastic philosophy”. In response, colleges changed their curricula away from canon law and towards the classics; the Bible; and mathematics.

    Nearly a century later the university was at the centre of a Protestant schism. Many nobles, intellectuals and even commoners saw the ways of the Church of England as too similar to the Catholic Church and felt that it was used by the Crown to usurp the rightful powers of the counties. East Anglia was the centre of what became the Puritan movement. In Cambridge the movement was particularly strong at Emmanuel; St Catharine’s Hall; Sidney Sussex; and Christ’s College. They produced many “non-conformist” graduates who, greatly influenced by social position or preaching left for New England and especially the Massachusetts Bay Colony during the Great Migration decade of the 1630s. Oliver Cromwell, Parliamentary commander during the English Civil War and head of the English Commonwealth (1649–1660), attended Sidney Sussex.

    Modern period

    After the Cambridge University Act formalized the organizational structure of the university the study of many new subjects was introduced e.g. theology, history and modern languages. Resources necessary for new courses in the arts architecture and archaeology were donated by Viscount Fitzwilliam of Trinity College who also founded the Fitzwilliam Museum. In 1847 Prince Albert was elected Chancellor of the University of Cambridge after a close contest with the Earl of Powis. Albert used his position as Chancellor to campaign successfully for reformed and more modern university curricula, expanding the subjects taught beyond the traditional mathematics and classics to include modern history and the natural sciences. Between 1896 and 1902 Downing College sold part of its land to build the Downing Site with new scientific laboratories for anatomy, genetics, and Earth sciences. During the same period the New Museums Site was erected including the Cavendish Laboratory which has since moved to the West Cambridge Site and other departments for chemistry and medicine.

    The University of Cambridge began to award PhD degrees in the first third of the 20th century. The first Cambridge PhD in mathematics was awarded in 1924.

    In the First World War 13,878 members of the university served and 2,470 were killed. Teaching and the fees it earned came almost to a stop and severe financial difficulties followed. As a consequence, the university first received systematic state support in 1919 and a Royal Commission appointed in 1920 recommended that the university (but not the colleges) should receive an annual grant. Following the Second World War the university saw a rapid expansion of student numbers and available places; this was partly due to the success and popularity gained by many Cambridge scientists.

     
  • richardmitnick 8:11 pm on August 8, 2022 Permalink | Reply
    Tags: "Australia’s newest Cray supercomputer is online in Perth", , , , Murchison Wide Field Radio Astronomy Observatory, , , The CSIRO-Commonwealth Scientific and Industrial Research Organisation (AU), The Square Kilometre Array (SKA)   

    From “COSMOS (AU)” : “Australia’s newest Cray supercomputer is online in Perth” 

    Cosmos Magazine bloc

    From “COSMOS (AU)”

    9 August 2022

    Australia’s newest supercomputer is already providing science with exciting new opportunities.

    Named Setonix after Setonix brachyurus (commonly known as the Quokka) the supercomputer has produced a detailed image of a supernova remnant.

    1
    The explosion remnants of a Supernova / Credit: ASKAP-Setonix

    Data used to create the image were collected with CSIRO’s ASKAP (Australian Square Kilometre Array Pathfinder radio telescope) at the Murchison Radio-astronomy Observatory in Western Australia, about 800 km north of Perth.

    ______________________________________________
    The Square Kilometre Array (SKA)– a next-generation telescope due to be completed by the end of the decade – will likely be able to make images of the earliest light in the Universe, but for current telescopes the challenge is to detect the cosmological signal of the stars through the thick hydrogen clouds.


    ______________________________________________

    1
    Murchison Wide Field Radio Astronomy Observatory radio-quiet area in Western Australia on the traditional lands of the Wajarri peoples,about 800 km north of Perth.

    That data was then transferred to the Pawsey Supercomputing Research Centre in Perth via high-speed optical fibre.
    ___________________________________________________


    ___________________________________________________

    Within 24 hours of accessing the first stage of Pawsey’s new Setonix system, CSIRO’s ASKAP science data processing team began integrating their processing pipeline into the new system and created the image of the supernova remnant, which is the structure resulting from the explosion of a star in supernova.

    The supernova remnant is bounded by an expanding shock wave, and consists of ejected material expanding from the explosion, and the interstellar material it sweeps up and shocks along the way.

    The new supercomputer is being installed in two stages. The first stage is underway, and will deliver 2.5 petaFLOPS of Raw computer power; 134 terabytes of Memory and consumes 194kW/power per petaFLOP, which compares to 587 kW/petaflop of the earlier 2014 Magnus+Galaxy supercomputer.

    However when fully installed later this year Setonix will include 50 petaFLOPS of raw compute power, 548 terabytes of Memory and consume 46 kW per petaflop.

    Dr Pascal Elahi, Pawsey’s supercomputing applications specialist, said deploying this first phase of Setonix has increased the computing power of the Pawsey Centre by 45 per cent.

    “Processing data from ASKAP’s astronomy surveys is a great way to stress-test the Setonix system and see what is possible.”

    While Setonix is ramping up to full operations so is ASKAP, which is currently wrapping up a series of pilot surveys and will soon undertake even larger and deeper surveys of the sky. Setonix will be used to process the data collected by ASKAP.

    Dr Wasim Raja, a researcher on CSIRO’s ASKAP team, said the supernova remnant’s dataset was selected to test the processing software on Setonix, given the challenges involved in imaging such a complex object.

    “Setonix’s large, shared memory will allow us to use more of our software features and further enhance the quality of our images. This means we will be able to unearth more from the ASKAP data.”

    When fully operational, Setonix will be up to 30 times more powerful than Pawsey’s earlier Galaxy and Magnus systems combined.

    The supercomputer is an AU$48 million Hewlett Packard Enterprise (HPE) Cray EX supercomputer

    Setonix is made from eight cabinets although stage one comprises of only two computational cabinets and one cooling cabinet.

    Pawsey is part of the National Research Infrastructure (NCRIS) funded by the Government. Historically the scientific fields that primarily use the systems have been engineering, astronomy, physics, chemistry and health science.

    Setonix is built on the same architecture used in exascale supercomputer projects including Frontier at Oak Ridge National Laboratory, El Capitan at Lawrence Livermore National Laboratory and LUMI at CSC – IT CENTER FOR SCIENCE LTD data centre in Kajaani, Finland. By working with the same computing architecture, Pawsey ensures the researchers’ workflows are exascale-ready for future requirements.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

     
  • richardmitnick 3:43 pm on July 22, 2022 Permalink | Reply
    Tags: "Astronomers develop novel way to ‘see’ the first stars through the fog of the early Universe", A team of astronomers has developed a method that will allow them to "see" through the fog of the early Universe and detect light from the first stars and galaxies., , , , , The Square Kilometre Array (SKA), The University of Cambridge - Institute of Astronomy (UK)   

    From The University of Cambridge – Institute of Astronomy (UK): “Astronomers develop novel way to ‘see’ the first stars through the fog of the early Universe” 

    From The University of Cambridge (UK) – Institute of Astronomy

    At

    U Cambridge bloc

    The University of Cambridge (UK)

    21 July 2022
    Jacqueline Garget
    External Affairs and Communications team
    jg533@cam.ac.uk

    1
    Artist’s impression of stars springing up out of the darkness. Credit: NASA/JPL-Caltech.

    A team of astronomers has developed a method that will allow them to “see” through the fog of the early Universe and detect light from the first stars and galaxies.

    The researchers, led by the University of Cambridge, have developed a methodology that will allow them to observe and study the first stars through the clouds of hydrogen that filled the Universe about 378,000 years after the Big Bang.

    Observing the birth of the first stars and galaxies has been a goal of astronomers for decades, as it will help explain how the Universe evolved from the emptiness after the Big Bang to the complex realm of celestial objects we observe today, 13.8 billion years later.

    ______________________________________________

    The Square Kilometre Array (SKA) – a next-generation telescope due to be completed by the end of the decade – will likely be able to make images of the earliest light in the Universe, but for current telescopes the challenge is to detect the cosmological signal of the stars through the thick hydrogen clouds.

    The signal that astronomers aim to detect is expected to be approximately one hundred thousand times weaker than other radio signals coming also from the sky – for example, radio signals originating in our own galaxy.

    Using a radio telescope itself introduces distortions to the signal received, which can completely obscure the cosmological signal of interest. This is considered an extreme observational challenge in modern radio cosmology. Such instrument-related distortions are commonly blamed as the major bottleneck in this type of observation.

    Now the Cambridge-led team has developed a methodology to see through the primordial clouds and other sky noise signals, avoiding the detrimental effect of the distortions introduced by the radio telescope. Their methodology, part of the REACH (Radio Experiment for the Analysis of Cosmic Hydrogen) experiment, will allow astronomers to observe the earliest stars through their interaction with the hydrogen clouds, in the same way we would infer a landscape by looking at shadows in the fog.

    Their method will improve the quality and reliability of observations from radio telescopes looking at this unexplored key time in the development of the Universe. The first observations from REACH are expected later this year.

    The results are reported today in the journal Nature Astronomy [below].

    “At the time when the first stars formed, the Universe was mostly empty and composed mostly of hydrogen and helium,” said Dr Eloy de Lera Acedo from Cambridge’s Cavendish Laboratory, the paper’s lead author.

    He added: “Because of gravity, the elements eventually came together and the conditions were right for nuclear fusion, which is what formed the first stars.

    _______________________________________________
    Evolution of the Universe


    _______________________________________________

    But they were surrounded by clouds of so-called neutral hydrogen, which absorb light really well, so it’s hard to detect or observe the light behind the clouds directly.”

    In 2018, another research group (running the ‘Experiment to Detect the Global Epoch of Reioniozation Signature’ – or EDGES) published a result [below] that hinted at a possible detection of this earliest light, but astronomers have been unable to repeat the result – leading them to believe that the original result may have been due to interference from the telescope being used.

    “The original result would require new physics to explain it, due to the temperature of the hydrogen gas, which should be much cooler than our current understanding of the Universe would allow. Alternatively, an unexplained higher temperature of the background radiation – typically assumed to be the well-known Cosmic Microwave Background – could be the cause” said de Lera Acedo.

    He added: “If we can confirm that the signal found in that earlier experiment really was from the first stars, the implications would be huge.”

    In order to study this period in the Universe’s development, often referred to as the Cosmic Dawn, astronomers study the 21-centimetre line – an electromagnetic radiation signature from hydrogen in the early Universe. They look for a radio signal that measures the contrast between the radiation from the hydrogen and the radiation behind the hydrogen fog.

    The methodology developed by de Lera Acedo and his colleagues uses Bayesian statistics to detect a cosmological signal in the presence of interference from the telescope and general noise from the sky, so that the signals can be separated.

    To do this, state-of-the-art techniques and technologies from different fields have been required.

    The researchers used simulations to mimic a real observation using multiple antennas, which improves the reliability of the data – earlier observations have relied on a single antenna.

    “Our method jointly analyses data from multiple antennas and across a wider frequency band than equivalent current instruments. This approach will give us the necessary information for our Bayesian data analysis,” said de Lera Acedo.

    He added: “In essence, we forgot about traditional design strategies and instead focused on designing a telescope suited to the way we plan to analyse the data – something like an inverse design. This could help us measure things from the Cosmic Dawn and into the epoch of reionisation, when hydrogen in the Universe was reionised.”

    The telescope’s construction is currently being finalised at the Karoo radio reserve in South Africa, a location chosen for its excellent conditions for radio observations of the sky. It is far away from human-made radio frequency interference, for example television and FM radio signals.

    The REACH team of over 30 researchers is multidisciplinary and distributed worldwide, with experts in fields such as theoretical and observational cosmology, antenna design, radio frequency instrumentation, numerical modelling, digital processing, big data and Bayesian statistics. REACH is co-led by the University of Stellenbosch in South Africa.

    Professor de Villiers, co-lead of the project at the University of Stellenbosch in South Africa said: “Although the antenna technology used for this instrument is rather simple, the harsh and remote deployment environment, and the strict tolerances required in the manufacturing, make this a very challenging project to work on.”

    He added: “We are extremely excited to see how well the system will perform, and have full confidence we’ll make that elusive detection.”

    The Big Bang and very early times of the Universe are well understood epochs, thanks to studies of the Cosmic Microwave Background (CMB) radiation. Even better understood is the late and widespread evolution of stars and other celestial objects. But the time of formation of the first light in the Cosmos is a fundamental missing piece in the puzzle of the history of the Universe.

    The research was supported by the Kavli Institute for Cosmology in Cambridge (UK), the National Research Foundation (South Africa), the Cambridge-Africa ALBORADA trust (UK) and the Science and Technology Facilities Council (STFC), part of UK Research and Innovation (UKRI).

    Science papers:
    Nature Astronomy

    Nature

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Cambridge Campus

    The IoA is part of the Faculty of Physics and Chemistry within the School of the Physical Sciences of The University of Cambridge (UK).

    Cambridge Institute of Astronomy

    The Institute of Astronomy came into being in 1972 by the amalgamation of three institutions which had developed on the site. These were the Cambridge University Observatory which was established in 1823, the Solar Physics Observatory (1912) and the Institute of Theoretical Astronomy (1967).

    The Institute of Astronomy is a department of the University of Cambridge and is engaged in teaching and research in the fields of theoretical and observational Astronomy. A wide class of theoretical problems are studied, ranging from models of quasars and of the evolution of the universe, through theories of the formation and evolution of galaxies and stars, X-ray sources and black holes.

    Much observational work centres around the use by staff of large telescopes abroad and in space to study quasars, galaxies and the chemical constitution of stars. A programme on the velocities of stars is conducted using the 36-inch telescope in Cambridge. Instrumentation development is also an important area of activity, involving charge coupled devices and detector arrays for rapid recording of very faint light and the design and construction of novel spectrographs.

    The Institute comprises about 88 postdoctoral staff, 45 graduate students and 26 support staff. There are close links with the Cavendish Astrophysics Group (formerly the Mullard Radio Astronomy Observatory) as well as with the Department of Applied Mathematics and Theoretical Physics, all of which are conducting complementary research programmes here in Cambridge.

    The University of Cambridge is a collegiate public research university in Cambridge, England. Founded in 1209, Cambridge is the second-oldest university in the English-speaking world and the world’s fourth-oldest surviving university. It grew out of an association of scholars who left The University of Oxford after a dispute with townsfolk. The two ancient universities share many common features and are often jointly referred to as “Oxbridge”.

    Cambridge is formed from a variety of institutions which include 31 constituent colleges and over 100 academic departments organised into six schools. The university occupies buildings throughout the town, many of which are of historical importance. The colleges are self-governing institutions founded as integral parts of the university. In the year ended 31 July 2014, the university had a total income of £1.51 billion, of which £371 million was from research grants and contracts. The central university and colleges have a combined endowment of around £4.9 billion, the largest of any university outside the United States. Cambridge is a member of many associations and forms part of the “golden triangle” of leading English universities and Cambridge University Health Partners, an academic health science centre. The university is closely linked with the development of the high-tech business cluster known as “Silicon Fen”.

     
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