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  • richardmitnick 12:02 pm on April 8, 2018 Permalink | Reply
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    Liverpool John Moores University via The Conversation: “Our study suggests the elusive ‘neutrino’ could make up a significant part of dark matter” 


    Liverpool John Moores University

    The Conversation

    April 5, 2018
    Ian G. McCarthy*

    Physicists trying to understand the fundamental structure of nature rely on consistent theoretical frameworks that can explain what we see and simultaneously make predictions that we can test. On the smallest scale of elementary particles, the standard model of particle physics provides the basis of our understanding.

    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.


    Standard Model of Particle Physics from Symmetry Magazine

    On the scale of the cosmos, much of our understanding is based on “standard model of cosmology”. Informed by Einstein’s theory of general relativity, it posits that the most of the mass and energy in the universe is made up of mysterious, invisible substances known as dark matter (making up 80% of the matter in the universe) and dark energy.
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    James Childs, CC BY

    Lambda-Cold Dark Matter, Accelerated Expansion of the Universe, Big Bang-Inflation (timeline of the universe) Date 2010 Credit: Alex Mittelmann Cold creation

    Over the past few decades, this model has been remarkably successful at explaining a wide range of observations of our universe. Yet we still don’t know what makes up dark matter – we only know it exists because of the gravitational pull it has on galaxy clusters and other structures. A number of particles have been proposed as candidates, but we can’t say for sure which one or several particles make up dark matter.

    Now our new study [MNRAS] – which hints that extremely light particles called neutrinos are likely to make up some of the dark matter – challenges our current understanding of its composition.

    Hot versus cold

    The standard model holds that dark matter is “cold”. That means it consists of relatively heavy particles that initially had sluggish motions. As a consequence, it is very easy for neighbouring particles to get together to form objects bound by gravity. The model therefore predicts that the universe should be filled with small dark matter “haloes”, some of which will merge and form progressively more massive systems – making the cosmos “lumpy”.

    However, it is not impossible that at least some dark matter is “hot”. This would comprise relatively light particles that have quite high velocities – meaning the particles could easily escape from dense regions such as galaxies. This would slow the accumulation of new matter and lead to a universe where the formation of structure is suppressed (less lumpy).

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    Neutrinos, which whizz around at extremely high velocities, are a good candidate for hot dark matter. In particular, they do not emit or absorb light – making them appear “dark”. It was long assumed that neutrinos, which come in three different species, don’t have mass. But experiments have demonstrated that they can change (oscillate) from one species to another. Importantly, scientists have shown that this changing requires them to have mass – making them a legitimate candidate for hot dark matter.

    Over the past few decades, however, both particle physics experiments and various astrophysical lines of argument have ruled out neutrinos as making up most of the dark matter in the universe. What’s more, the standard model assumes that neutrinos (and hot dark matter in general) have so little mass that their contribution to dark matter can be ignored completely (in most cases assumed to be 0%). And, until very recently, this model has reproduced a wide variety of cosmological observations quite well.

    Changing picture

    In the past few years, the quantity and quality of cosmological observations has shot up enormously. One of the most prominent examples of this has been the emergence of “gravitational lensing observations”. General relativity tells us that matter curves spacetime so that light from distant galaxies can be deflected by massive objects that lie between us and the galaxies. Astronomers can measure such deflection to estimate the growth of structure (the “lumpiness”) in the universe over cosmic time.

    These new data sets have presented cosmologists with a number of ways to test in detail the predictions of the standard model. A picture that is beginning to emerge from these comparisons is that the mass distribution in the universe appears to be less lumpy than it ought to be if the dark matter is entirely cold.

    However, making comparisons between the standard model and the new data sets may not be as straightforward as first thought. In particular, researchers have shown that the apparent lumpiness of the universe is not just affected by dark matter, but also by complex processes that affect normal matter (protons and neutrons). Previous comparisons assumed that normal matter, which “feels” both gravity and pressure forces, is distributed like dark matter, which only feels gravity.

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    Now our new study has produced the largest suite of cosmological computer simulations of normal and dark matter to date (called BAHAMAS). We have also made careful comparisons with a wide range of recent observations. We conclude that the discrepancy between the new observational data sets and the standard cold dark matter model is even larger than previously claimed.

    We looked at the effects of neutrinos and their motions in great detail. As expected, when neutrinos were included in the model, the structure formation in the cosmos was washed out, making the universe less lumpy. Our results suggest that neutrinos make up between 3% and 5% of the total dark matter mass. This is sufficient to consistently reproduce a wide variety of observations – including the new gravitational lensing measurements. If a larger fraction of the dark matter is “hot”, the growth of structure in the universe is suppressed too much.

    The research may also help us solve the mystery of what the mass of an individual neutrino is. From various experiments, particle physicists have calculated that the the sum of the three neutrino species should be at least 0.06 electron Volts (a unit of energy, similar to joules). You can convert this into an estimate of the total neutrino contribution to dark matter, and it works out to be 0.5%. Given that we have found it is actually six to ten times larger than this, we can deduce that the neutrino mass should be about 0.3-0.5 eV instead.

    This is tantalisingly close to values that can actually be measured by upcoming particle physics experiments. If these measurements corroborate the masses we found in our simulations, this would be very reassuring – giving us a consistent picture of the role of neutrinos as dark matter from the largest cosmological scales to the tiniest particle physics realm.

    *Disclosure statement

    Ian G. McCarthy works for Liverpool John Moores University. He receives funding from the Science and Technology Facilities Council (STFC) and the European Research Council (ERC).

    See the full article here .

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    Liverpool John Moores University is a public research university[6] in the city of Liverpool, England. It has 21,875 students, of which 18,375 are undergraduate students and 3,500 are postgraduate, making it the 33rd largest university in the UK by total student population.

    The university can trace its origins to the Liverpool Mechanics’ School of Arts, established in 1823 making it a contestant as the third-oldest university in England; this later merged to become Liverpool Polytechnic. In 1992, following an Act of Parliament the Liverpool Polytechnic became what is now Liverpool John Moores University.

    It is a member of the University Alliance, a mission group of British universities which was established in 2007.[9] and the European University Association.

     
  • richardmitnick 12:53 pm on February 19, 2018 Permalink | Reply
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    From Liverpool John Moores University: Dance of galaxies challenges current thinking on cosmology 


    Liverpool John Moores University

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    Centaurus A. Image: X-ray: NASA/CXC/SAO; Optical: Rolf Olsen; Infrared: NASA/JPL-Caltech

    Scientists have a pretty good picture of how the universe formed and evolved – and how it is structured today. This knowledge all fits together nicely as a “standard cosmological model”, which has been able to successfully predict and describe many observational data in the universe. But now and then scientists discover something that threatens to tear down this valuable framework.

    New research, published in Science, has done just that. The paper reports that a number of “satellite dwarf galaxies” – small galaxies orbiting around the much larger galaxy, Centaurus A – are rotating in synchrony in a single plane around their host, which is not at all what was expected.

    This is a problem because the standard cosmological model predicts that galaxies form hierarchically, meaning they grow gradually larger by attracting smaller galaxies and tearing some of them apart. This happens as the force of gravity sucks them in, irrespective of which direction they are captured from. You would therefore expect these galaxies to be moving in all sorts of random positions and directions corresponding to however they were moving before being caught in orbit.

    Despite being challenged at times, the hierarchical model still stands strong. It supports one of the most fundamental aspects of modern cosmology: isotropy. This is the expectation that the universe is uniform, looking the same in whatever direction you are viewing it. The same expectation for uniform behaviour holds true on the small scales of satellite galaxies. The new study challenges the hierarchical model and thereby also isotropy – it doesn’t make sense for some galaxies in some corner to behave in synchrony and others at random.

    What’s more, we see plenty of evidence for the hierarchical model in the wreck caused by past satellite disruptions, also smaller galaxies in the process of being accumulated gradually and others still surviving.

    Estimating strangeness

    But just how surprising is the new finding? A few other satellite galaxies moving in a single plane have been found before. Two such cases were discovered right in our cosmological backyard, one around our own Milky Way and one around the Andromeda galaxy. Three is not a big number, but we have not looked for these features much farther away yet. However there is tantalising evidence that about half of galaxies like the Milky Way may have satellites on ordered orbits.

    So far, cosmologists have been writing off these planes as rare events, odd occurrences that don’t represent the wider universe. Using computer simulations of galaxy formation and sifting through all possible orientations of satellite galaxies in these models, scientists can estimate the number of such “outlier” galaxies we can expect to find in the universe. This shows that such planar distribution should not be freakishly rare [MNRAS] – there is in fact a 10% chance of it happening.

    However, the chance of seeing a large number of satellite galaxies rotating in the same direction, such as those around Centaurus A, is less than 0.5%. This means it is not impossible, but if we find too many such cases, the standard model would have to be rethought. In addition to the new study, we know of two other cases where that happens (also in Milky Way and Andromeda). So by now there are already three such examples in a sample of observations that is not yet very large.

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    The Milky Way Taken from Australia. Roanish/wikipedia/CC BY-SA

    But then there is the “look-elsewhere effect”. This is an effect well known to statisticians, which corrects for our propensity to reach all sorts of bizarre conclusions when a rare event happens in a small sample of observations. By looking elsewhere, that is, by increasing the number of observations and counting all the times when the event does not occur, the statistical significance of that event can be drastically reduced.

    Alternative explanations

    But what if we can’t find enough cases to show that these galaxies are an exception rather than a rule? Can the findings be explained at all by our current cosmological model? Possibly, but unusual observations call for unusual explanations. Potentially these dwarf galaxies could have been created in a single event – giving them coherent movement – rather than having been captured one at a time. A massive merger of two galaxies could potentially create this effect. As Centaurus A certainly shows signs of a violent past, this isn’t impossible.

    Such a scenario has been proposed for explaining the plane of satellite galaxies in Andromeda [MNRAS], but it seems unlikely this would explain all such cases. The problem with this scenario is that the dwarf galaxies born in a single tidal event would have to share similar star formation histories. However, many of these dwarf galaxies don’t.

    The environment of galaxies clearly plays a role. The distribution of galaxies on much larger scale can also have subtle effects on the motion of satellite galaxies. For example, an expanding empty region of space known as the Local Void is thought to “shepherd” galaxies near Centaurus A, steering them along preferred directions.

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    A local void

    This explanation is also fully compatible with the standard cosmological model. However, cosmological simulations cannot yet show exactly how this would match what’s actually seen.

    A more drastic re-evaluation of the whole problem is to tweak the laws of gravity, for example by using something called modified newtonian dynamics. Computer simulations using such dynamics have been able to produce similar planes of satellite galaxies as seen in the Milky Way and Andromeda. However, this theory, although successful in many respects, is still some way from passing the same consistency checks as the standard model.

    So it looks like our cherished cosmological model may just be able to survive, at least for a while.

    See the full article here .

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    Liverpool John Moores University is a public research university[6] in the city of Liverpool, England. It has 21,875 students, of which 18,375 are undergraduate students and 3,500 are postgraduate, making it the 33rd largest university in the UK by total student population.

    The university can trace its origins to the Liverpool Mechanics’ School of Arts, established in 1823 making it a contestant as the third-oldest university in England; this later merged to become Liverpool Polytechnic. In 1992, following an Act of Parliament the Liverpool Polytechnic became what is now Liverpool John Moores University.

    It is a member of the University Alliance, a mission group of British universities which was established in 2007.[9] and the European University Association.

     
  • richardmitnick 7:03 am on May 25, 2017 Permalink | Reply
    Tags: , , , Liverpool John Moores University, , Liverpool Telescope group begins collaboration with National Astronomical Research Institute of Thailand   

    From Liverpool: “Liverpool Telescope group begins collaboration with National Astronomical Research Institute of Thailand” 

    Liverpool Telescope

    Liverpool Telescope

    24 May 2017
    No writer credit found

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    LJMU staff with collaborators from NARIT and the Thai-German Institute.

    Earlier this month, a deputation of Liverpool Telescope (LT) staff visited the National Astromical Research Institute of Thailand (NARIT) in the city of Chiang Mai. The purpose of the visit was to begin a programme of collaborative software development, funded by STFC through the Newton Fund. The purpose of the Newton Fund is to use science and innovation partnerships to promote economic development and social welfare in partner countries.

    The collaborative programme between the LT and NARIT is based around two projects: the development of a new, modern data archiving framework and a new telescope control system. At the end of the three-year programme, these products will replace the existing systems on LT and NARIT facilities, and will also be a component in the new software which will be required for the Large Robotic Telescope (Liverpool Telescope 2).

    See the full article here .

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    The Liverpool Telescope (LT) is a 2-metre (6.6 ft) fully robotic Ritchey–Chrétien telescope that observes autonomously; i.e., it operates without human intervention. Professional astronomers and other registered users submit observation specifications to be considered by the telescope’s robotic control system (RCS) at any time of the day or night using an online GUI. Each night the RCS decides for itself what to observe next based on target visibility and weather conditions.

    The RCS additionally has a rapid-response capability where it can automatically interrupt regular observations to slew to observe transient phenomena with higher priority, such as gamma-ray bursts.

    The LT is one of the largest robotic telescopes in the world and was built by Telescope Technologies Ltd, a subsidiary company set up by Liverpool John Moores University. The telescope is owned by Liverpool John Moores University, and operated by the Astrophysics Research Institute with operational funding partly from STFC. It is sited at the Roque de los Muchachos Observatory on La Palma.

    Along with the Faulkes Telescope North and the Faulkes Telescope South, the Liverpool Telescope is also available for use by school children around the world over the internet. The registration and time allocation for the LT is organised by the National Schools Observatory.

    The Liverpool Telescope is one of the primary players in the Heterogeneous Telescope Networks Consortium, a global collaboration between major research groups in the field of robotic telescopes which seeks a standard for communication between remote telescopes, telescope users, and other scientific resources.

    Plans for an improved version of the telescope, the Liverpool Telescope 2, are underway.

     
  • richardmitnick 4:03 pm on April 24, 2017 Permalink | Reply
    Tags: , , , , , Liverpool John Moores University   

    From Liverpool: “Shooting for the stars: capturing the beauty of science through astrophotography” 

    Liverpool John Moores University

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    Thor’s Helmet is a planetary nebula. Nothing to do with planets, it is actually a shell of gas being thrown off from an old star towards the end of its life cycle. Planetary nebulae are wonderfully varied in shape and colour. This image was originally obtained with the Liverpool Telescope for BBC Sky At Night.

    2-metre Liverpool Telescope at La Palma in the Canary Islands

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    Castell Alun High School captured the Messier 27 through the NSO.

    National Solar Observatory at Kitt Peak in Arizona

    One of the best planetary nebulae to observe on the NSO, it almost fills the field of view, providing a spectacular image with vast detail. The image was produced by combining observations in the blue, visual and red filters using NSO’s 3-colour image tool.

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    The Crab Nebula is a supernova remnant, the expanding cloud of gas and dust from a catastrophically exploding star. Chinese astronomers witnessed this explosion in 1054 and we still see the remnant cloud now. To the human eye, it would be faint pink. Scientific instruments do not necessarily ‘see’ colours the same way as our eyes and allow astronomers to bring out details that a true colour image might not reveal.

    When thinking about the types of photographs that capture the beauty of science, a stunning landscape or an animal in its natural habitat might come to mind. But when it comes to images from telescopes, we might not immediately consider these as anything more than the collection of scientific data. Beyond their significance in helping us to discover more about our universe, the images of galaxies, planets and stars are also appreciated purely for aesthetic reasons. For many amateur and professional astrophotographers capturing the shapes and colours of the universe is just as important as capturing scientific data. In fact, most astronomical images for general viewing have been modified from their original form. An astrophotographer’s goal in this case is to bring out the best of the image – to find the art within the science.

    Robert Smith, creator of the “Iridis” image which won the Robotic Scope Special Prize at the Insight Astronomy Photographer of the Year competition, sums up the concept of science as art/art as science:

    “We often hear about the idea of representing scientific data in an appealing way as an expression of art, but why not look at it the other way around; ‘art as science’? Astrophotography is not just a matter of making science look pretty, it shows us that beauty actually is science. The winners of this competition were obviously selected because they were beautiful, striking or interesting, but each and every one is also an expression of astrophysical processes and could be the basis of a science seminar in their own right. It is physics that creates that beauty. Looking at the swirling gas in a nebula or the aurorae, you are literally seeing maths and physics.”

    Robert is an astronomer at the Astrophysics Research Institute (ARI) at LJMU and captured the award-winning image from ARI’s very own Liverpool Telescope. As the world’s largest fully robotic telescope, the Liverpool Telescope is responsible for a wide range of images which, in addition to their obvious importance scientifically, are also interesting and beautiful as pieces of art in their own right.

    Astronomers were among the first to embrace photography, with the first images of the sun captured on daguerreotypes, an early photographic imaging process, in the 1840s.

    Users of the Liverpool Telescope not only include researchers at LJMU but because it is remotely operated, it is available to astronomers from around the world. Schools and colleges across the UK and Ireland also get involved in capturing astronomical images. As a part of ARI’s educational outreach programmes, the National Schools’ Observatory (NSO) makes it possible for schoolchildren to study the night sky for themselves via the Telescope. Almost 4,000 schools have already participated with students making well over 100,000 astronomical observations from the classroom. A couple examples of the photos from NSO can be found on this page, but feel free to take a look at more on the NSO website.

    ______________________________________________________________________

    How do you photograph a night sky?

    Make sure it’s a clear night and find a place as far away from light pollution as you can. With a manual camera, try setting 25 second exposure, f/2.8, ISO 1600 (you can experiment with these settings). You’ll need a tripod to keep your camera stable during the exposure. Modern smartphones can produce impressive results as well. There are free apps available to download that automatically take a series of short exposures for you and add them together to create a long night-time photo.

    If you have access to a telescope, you can hold your smartphone up to the eyepiece of the telescope and take your shot, this is known as afocal photography – where the lens takes the place of the human eye.

    There are plenty of tips for getting started in astrophotography, just do a search online and you’ll be exposed to a wealth of information.
    ______________________________________________________________________

    See the full article here .

    Please help promote STEM in your local schools.

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    3

    Liverpool John Moores University is a public research university[6] in the city of Liverpool, England. It has 21,875 students, of which 18,375 are undergraduate students and 3,500 are postgraduate, making it the 33rd largest university in the UK by total student population.

    The university can trace its origins to the Liverpool Mechanics’ School of Arts, established in 1823 making it a contestant as the third-oldest university in England; this later merged to become Liverpool Polytechnic. In 1992, following an Act of Parliament the Liverpool Polytechnic became what is now Liverpool John Moores University.

    It is a member of the University Alliance, a mission group of British universities which was established in 2007.[9] and the European University Association.

     
  • richardmitnick 11:15 am on April 5, 2017 Permalink | Reply
    Tags: , , , , Liverpool John Moores University, ,   

    From Liverpool John Moores University: “New research opportunities with GROWTH for the Astrophysics Research Institute” 

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    Liverpool John Moores University

    The Astrophysics Research Institute (ARI) has been named as an official partner in the GROWTH (Global Relay of Observatories Watching Transients Happen) scientific collaboration, setting up exciting research opportunities in a range of areas to tell us more about the Universe, from time domain astrophysics to fast-changing events in the cosmos like supernovae, neutron stars, black hole mergers, and near-earth asteroids.

    GROWTH is led by the California Institute of Technology (Caltech) and works through the coordinated efforts of international teams and facilities to continuously gather data of cosmic transient events in the first 24 hours after detection to build a more complete picture and better understand the physical processes of their evolution. This includes discovery engines such as the Laser Interferometer Gravitational-Wave Observatory (LIGO).

    The Liverpool Telescope (LT), operated by the ARI will also join the GROWTH global network of observatories providing additional follow-up resources for the search of electromagnetic counterpart to gravitational wave sources.

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    2-metre Liverpool Telescope at La Palma in the Canary Islands

    Students and young researchers can also benefit from being part of the GROWTH Graduate/Postdoc Exchange Program and the Summer Research Program, designed for undergraduates. Last year, Caltech student Kit Chinetti spent her summer at the ARI working with Dr Matt Darnley and Professor Paolo Mazzali on discovery and classification of novae in the Andromeda Galaxy. During the summer project, she discovered a nova in the outskirts of Andromeda galaxy and wrote her first post to the Astronomer’s Telegram (ATel) – an online platform for announcements of discoveries of transient events to the global astronomical community.

    Professor Chris Collins, Head of the Astrophysics Research Institute, commented: “The signing of the GROWTH MoU with the Caltech is fantastic news for future research in time-domain astrophysics at the ARI. The new partnership will help provide the electromagnetic identification of gravitational wave sources and determine the properties of the most powerful stellar explosions in astrophysics, in addition to other projects.”

    “It is also our priority to work closely with our US colleagues at GROWTH to enhance the student experience of research. Under the new agreement LJMU and Caltech students will spend time at the partner university, where they will benefit from access to new facilities and expertise, and have the opportunity to engage with science research that has fundamental implications for our understanding of gravity and dark energy.”

    Professor Mansi Kasliwal, GROWTH principal investigator and an assistant professor at Caltech, said: “We are very excited that LJMU has joined the GROWTH team. Finding the cosmic mines of heavy elements is especially tough as the flash of light may fade away in a few hours. Located in the Canary Islands, Spain, the LT is perfectly positioned to follow-up fading transients initially found in California.”

    The ARI is currently in the process of designing the New Robotic Telescope, a facility which will take the Liverpool Telescope’s crown as the world’s largest robotic telescope dedicated to science, and which will be a powerful tool in the search for other-Earths, liquid water and life over the coming decades.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    3

    Liverpool John Moores University is a public research university[6] in the city of Liverpool, England. It has 21,875 students, of which 18,375 are undergraduate students and 3,500 are postgraduate, making it the 33rd largest university in the UK by total student population.

    The university can trace its origins to the Liverpool Mechanics’ School of Arts, established in 1823 making it a contestant as the third-oldest university in England; this later merged to become Liverpool Polytechnic. In 1992, following an Act of Parliament the Liverpool Polytechnic became what is now Liverpool John Moores University.

    It is a member of the University Alliance, a mission group of British universities which was established in 2007.[9] and the European University Association.

     
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