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  • richardmitnick 9:16 am on May 8, 2021 Permalink | Reply
    Tags: "Massive flare seen on the closest star to the solar system- What it means for chances of alien neighbors", , , , , , The Conversation (AU)   

    From The Conversation : “Massive flare seen on the closest star to the solar system- What it means for chances of alien neighbors” 

    From The Conversation

    May 3, 2021

    R. O. Parke Loyd
    Post-Doctoral Researcher in Astrophysics
    Arizona State University

    The Sun isn’t the only star to produce stellar flares. On April 21, 2021, a team of astronomers published new research [The Astrophysical Journal Letters] describing the brightest flare ever measured from Proxima Centauri in ultraviolet light.

    Centauris Alpha Beta Proxima, 27 February 2012. Skatebiker.

    To learn about this extraordinary event – and what it might mean for any life on the planets orbiting Earth’s closest neighboring star – The Conversation spoke with Parke Loyd, an astrophysicist at Arizona State University and co-author of the paper. Excerpts from our conversation are below and have been edited for length and clarity.

    Why were you looking at Proxima Centauri?

    Proxima Centauri is the closest star to this solar system. A couple of years ago, a team discovered that there is a planet – called Proxima b – orbiting the star. It’s just a little bit bigger than Earth, it’s probably rocky and it is in what is called the habitable zone, or the Goldilocks zone. This means that Proxima b is about the right distance from the star so that it could have liquid water on its surface.

    But this star system differs from the Sun in a pretty key way. Proxima Centauri is a small star called a red dwarf – it’s around 15% of the radius of our Sun, and it’s substantially cooler. So Proxima b, in order for it to be in that Goldilocks zone, actually is a lot closer to Proxima Centauri than Earth is to the Sun.

    You might think that a smaller star would be a tamer star, but that’s actually not the case at all – red dwarfs produce stellar flares a lot more frequently than the Sun does. So Proxima b, the closest planet in another solar system with a chance for having life, is subject to space weather that is a lot more violent than the space weather in Earth’s solar system.

    What did you find?

    In 2018, my colleague Meredith MacGregor discovered flashes of light coming from Proxima Centauri that looked very different from solar flares. She was using a telescope that detects light at millimeter wavelengths to monitor Proxima Centauri and saw a big of flash of light in this wavelength. Astronomers had never seen a stellar flare in millimeter wavelengths of light.

    My colleagues and I wanted to learn more about these unusual brightenings in the millimeter light coming from the star and see whether they were actually flares or some other phenomenon. We used nine telescopes on Earth, as well as a satellite observatory, to get the longest set of observations – about two days’ worth – of Proxima Centauri with the most wavelength coverage that had ever been obtained.

    Immediately we discovered a really strong flare. The ultraviolet light of the star increased by over 10,000 times in just a fraction of a second. If humans could see ultraviolet light, it would be like being blinded by the flash of a camera. Proxima Centauri got bright really fast. This increase lasted for only a couple of seconds, and then there was a gradual decline.

    This discovery confirmed that indeed, these weird millimeter emissions are flares.

    What does that mean for chances of life on the planet?

    Astronomers are actively exploring this question at the moment because it can kind of go in either direction. When you hear ultraviolet radiation, you’re probably thinking about the fact that people wear sunscreen to try to protect ourselves from ultraviolet radiation here on Earth. Ultraviolet radiation can damage proteins and DNA in human cells, and this results in sunburns and can cause cancer. That would potentially be true for life on another planet as well.

    On the flip side, messing with the chemistry of biological molecules can have its advantages – it could help spark life on another planet. Even though it might be a more challenging environment for life to sustain itself, it might be a better environment for life to be generated to begin with.

    But the thing that astronomers and astrobiologists are most concerned about is that every time one of these huge flares occurs, it basically erodes away a bit of the atmosphere of any planets orbiting that star – including this potentially Earth-like planet. And if you don’t have an atmosphere left on your planet, then you definitely have a pretty hostile environment to life – there would be huge amounts of radiation, massive temperature fluctuations and little or no air to breathe. It’s not that life would be impossible, but having the surface of a planet basically directly exposed to space would be an environment totally different than anything on Earth.

    Is there any atmosphere left on Proxima b?

    That’s anybody’s guess at the moment. The fact that these flares are happening doesn’t bode well for that atmosphere being intact – especially if they’re associated with explosions of plasma like what happens on the Sun. But that’s why we’re doing this work. We hope the folks who build models of planetary atmospheres can take what our team has learned about these flares and try to figure out the odds for an atmosphere being sustained on this planet.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    The Conversation launched as a pilot project in October 2014. It is an independent source of news and views from the academic and research community, delivered direct to the public.
    Our team of professional editors work with university and research institute experts to unlock their knowledge for use by the wider public.
    Access to independent, high quality, authenticated, explanatory journalism underpins a functioning democracy. Our aim is to promote better understanding of current affairs and complex issues. And hopefully allow for a better quality of public discourse and conversation.

     
  • richardmitnick 12:17 pm on February 11, 2021 Permalink | Reply
    Tags: "A brief history: what we know so far about fast radio bursts across the universe", Arecibo Radio Observatory, , , , , Caltech STARE2 Radio telescope at Owens Valley Radio Observatory, , Fast radio bursts are one of the great mysteries of the universe., , , The Conversation (AU), The first FRB was discovered in 2007 by a team led by British-American astronomer Duncan Lorimer using Murriyang-the traditional Indigenous name for the iconic Parkes Radio Telescope., The Lorimer burst had travelled through far too much gas to have originated in our galaxy., The NASA Neil Gehrels Swift Observatory captured X-rays from a very magnetic and erratic neutron star in our own Milky Way., We need to detect an FRB with a radio interferometer-an array of antennas spread out over at least a few kilometres.   

    From The Conversation (AU): “A brief history: what we know so far about fast radio bursts across the universe” 

    From The Conversation (AU)

    February 10, 2021
    Ryan Shannon
    Associate Professor, Swinburne University of Technology (AU)

    Keith Bannister
    Astronomer, CSIRO (AU)

    1
    CSIRO/Parkes Observatory [ Murriyang, the traditional Indigenous name] , located 20 kilometres north of the town of Parkes, New South Wales, Australia, 414.80m above sea level.

    Fast radio bursts are one of the great mysteries of the universe. Since their discovery, we have learned a great deal about these intense millisecond-duration pulses.

    But we still have much to learn, such as what causes them.

    We know the intense bursts originate in galaxies billions of light years away. We have also used these bursts (called FRBs) to find missing matter that couldn’t be found otherwise.

    With teams of astronomers around the world racing to understand their enigma, how did we get to where we are now?

    The first burst

    The first FRB was discovered in 2007 by a team led by British-American astronomer Duncan Lorimer using Murriyang, the traditional Indigenous name for the iconic Parkes radio telescope.

    The team found an incredibly bright pulse — so bright that many astronomers did not believe it to be real. But there was yet more intrigue.

    Radio pulses provide a tremendous gift to astronomers. By measuring when a burst arrives at the telescope at different frequencies, astronomers can tell the total amount of gas that it passed through on its journey to Earth.

    2
    A typical Fast Radio Burst. The burst arrives first at high frequencies and is delayed by as much as several seconds at the lower frequencies. This tell-tale curve is what astronomers are looking for. Credit:Ryan Shannon and Vikram Ravi.

    The Lorimer burst had travelled through far too much gas to have originated in our galaxy, the Milky Way. The team concluded it came from a galaxy billions of light years away.

    To be visible from so far away, whatever produced it must have released an enormous amount of energy. In just a millisecond it released as much energy as our Sun would in 80 years.

    Lorimer’s team could only guess which galaxy their FRB had come from. Murriyang can’t pinpoint FRB locations very accurately. It would take several years for another team to make the breakthrough.

    Locating FRBs

    To pinpoint a burst location, we need to detect an FRB with a radio interferometer — an array of antennas spread out over at least a few kilometres.

    When signals from the telescopes are combined, they produce an image of an FRB with enough detail not only to see in which galaxy the burst originated, but in some cases to tell where within the galaxy it was produced.

    The first FRB localised was from a source that emitted many bursts. The first burst was discovered in 2012 with the giant Arecibo telescope in Puerto Rico.


    NAIC Arecibo Observatory operated by University of Central Florida, Yang Enterprises and UMET, Altitude 497 m (1,631 ft), which has now collapsed.

    Subsequent bursts were detected by the Very Large Array, in New Mexico, and found to be coming from a tiny galaxy about 3 billion light years away.

    NRAO Karl G Jansky Very Large Array, located in central New Mexico on the Plains of San Agustin, between the towns of Magdalena and Datil, ~50 miles (80 km) west of Socorro. The VLA comprises twenty-eight 25-meter radio telescopes.

    In 2018, using the Australian Square Kilometre Array Pathfinder Telescope (ASKAP) in Western Australia, our team identified the second FRB host galaxy.

    Australian Square Kilometre Array Pathfinder (ASKAP) is a radio telescope array located at Murchison Radio-astronomy Observatory (MRO) in the Australian Mid West on the traditional lands of the Wajarri peoples. ASKAP consists of 36 identical parabolic antennas, each 12 metres in diameter, working together as a single instrument with a total collecting area of approximately 4,000 square metres.

    In stark contrast to the previous galaxy, this galaxy was very ordinary. But our published discovery was this month awarded the 2020 AAAS Newcomb Cleveland Prize by the American Association for the Advancement of Science.

    Teams including ours have now localised roughly a dozen more bursts from a wide range of galaxies, large and small, young and old. The fact FRBs can come from such a wide range of galaxies remains a puzzle.

    A burst from close to home

    On April 28, 2020, a flurry of X-rays suddenly bashed into the Swift telescope orbiting Earth.

    NASA Neil Gehrels Swift Observatory.

    The satellite telescope dutifully noted the rays had come from a very magnetic and erratic neutron star in our own Milky Way. This star has form: it goes into fits every few years.

    Two telescopes, CHIME in Canada and the STARE2 array in the United States, detected a very bright radio burst within milliseconds of the X-rays and in the direction of that star.

    CHIME Canadian Hydrogen Intensity Mapping Experiment -A partnership between the University of British Columbia (CA), the University of Toronto (CA), McGill University (CA), Yale and the National Research Council in British Columbia (CA), at the Dominion Radio Astrophysical Observatory in Penticton, British Columbia, (CA) Altitude 545 m (1,788 ft).

    Caltech STARE2 Radio telescope at Owens Valley Radio Observatory, located near Big Pine, California (US) in Owens Valley. It lies east of the Sierra Nevada, approximately 350 kilometers (220 mi) north of Los Angeles and 20 kilometers (12 mi) southeast of Bishop. It was established in 1956, and is owned and operated by the California Institute of Technology (Caltech), Altitude 1,222 m (4,009 ft).

    Caltech Owens Valley Radio Observatory, Owens Valley, California, Altitude 1,222 m (4,009 ft).

    This demonstrated such neutron stars could be a source of the FRBs we see in galaxies far away.

    The simultaneous release of X-rays and radio waves gave astrophysicists important clues to how nature can produce such bright bursts. But we still don’t know for certain if this is the cause of FRBs.

    So what’s next?

    While 2020 was the year of the local FRB, we expect 2021 will be the year of the the far-flung FRB, even further than already observed.

    The CHIME telescope has collected by far the largest sample of bursts and is compiling a meticulous catalogue that should be available to other astronomers soon.

    A team at Caltech is building an array specifically dedicated to finding FRBs.

    Caltech Deep Synoptic Array being built at Owens Valley Radio Observatory Owens Valley, California, Altitude 1,222 m (4,009 ft)

    There’s plenty of action in Australia too. We are developing a new burst-detection supercomputer for ASKAP that will find FRBs at a faster rate and find more distant sources.

    It will effectively turn ASKAP into a high-speed, high-definition video camera, and make a movie of the universe at 40 trillion pixels per second.

    By finding more bursts, and more distant bursts, we will be able to better study and understand what causes these mysteriously intense bursts of energy.


    Fast Radio Burst Research Earns AAAS Newcomb Cleveland Prize

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    The Conversation (AU) launched as a pilot project in October 2014. It is an independent source of news and views from the academic and research community, delivered direct to the public.
    Our team of professional editors work with university and research institute experts to unlock their knowledge for use by the wider public.
    Access to independent, high quality, authenticated, explanatory journalism underpins a functioning democracy. Our aim is to promote better understanding of current affairs and complex issues. And hopefully allow for a better quality of public discourse and conversation.

     
  • richardmitnick 2:03 pm on February 10, 2021 Permalink | Reply
    Tags: "The search for dark matter gets a speed boost from quantum technology", Axion detectors measure two quantities called electromagnetic field quadratures., , Dark Matter can be inferred from an assortment of physical clues in the universe., Despite decades of experimental effort scientists have yet to identify the dark matter particle., I helped design and operate one of these detectors aptly named HAYSTAC., Nearly a century after dark matter was first proposed to explain the motion of galaxy clusters physicists still have no idea what it’s made of., Nobody knows if axions exist or if they will resolve the mystery of dark matter; thanks to this unexpected application of quantum technology we’re one step closer to answering these questions., One prominent theory proposes that dark matter is made of as-yet hypothetical particles called axions., , , Researchers around the world have built dozens of detectors in hopes of discovering dark matter., The Conversation (AU), The main challenge in the search for axions is that nobody knows the frequency of the hypothetical axion wave.   

    From The Conversation (AU): “The search for dark matter gets a speed boost from quantum technology” 

    From The Conversation (AU)

    February 10, 2021
    Benjamin Brubaker

    1
    Dark Matter can be inferred from an assortment of physical clues in the universe. Credit: NASA.

    “Nearly a century after dark matter was first proposed to explain the motion of galaxy clusters, physicists still have no idea what it’s made of.

    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.

    Researchers around the world have built dozens of detectors in hopes of discovering dark matter. As a graduate student, I helped design and operate one of these detectors, aptly named HAYSTAC.

    Yale HAYSTAC axion dark matter experiment at Yale’s Wright Lab.

    But despite decades of experimental effort, scientists have yet to identify the dark matter particle.

    Now, the search for dark matter has received an unlikely assist from technology used in quantum computing research. In a new paper published in the journal Nature, my colleagues on the HAYSTAC team and I describe how we used a bit of quantum trickery to double the rate at which our detector can search for dark matter. Our result adds a much-needed speed boost to the hunt for this mysterious particle.

    Scanning for a dark matter signal

    There is compelling evidence from astrophysics and cosmology that an unknown substance called dark matter constitutes more than 80% of the matter in the universe. Theoretical physicists have proposed dozens of new fundamental particles that could explain dark matter. But to determine which – if any – of these theories is correct, researchers need to build different detectors to test each one.

    One prominent theory proposes that dark matter is made of as-yet hypothetical particles called axions that collectively behave like an invisible wave oscillating at a very specific frequency through the cosmos. Axion detectors – including HAYSTAC – work something like radio receivers, but instead of converting radio waves to sound waves, they aim to convert axion waves into electromagnetic waves.

    Inside the ADMX experiment hall at the University of Washington Credit: Mark Stone U. of Washington. Axion Dark Matter Experiment.

    Specifically, axion detectors measure two quantities called electromagnetic field quadratures. These quadratures are two distinct kinds of oscillation in the electromagnetic wave that would be produced if axions exist.

    The main challenge in the search for axions is that nobody knows the frequency of the hypothetical axion wave. Imagine you’re in an unfamiliar city searching for a particular radio station by working your way through the FM band one frequency at a time. Axion hunters do much the same thing: They tune their detectors over a wide range of frequencies in discrete steps. Each step can cover only a very small range of possible axion frequencies. This small range is the bandwidth of the detector.

    Tuning a radio typically involves pausing for a few seconds at each step to see if you’ve found the station you’re looking for. That’s harder if the signal is weak and there’s a lot of static. An axion signal – in even the most sensitive detectors – would be extraordinarily faint compared with static from random electromagnetic fluctuations, which physicists call noise. The more noise there is, the longer the detector must sit at each tuning step to listen for an axion signal.

    Unfortunately, researchers can’t count on picking up the axion broadcast after a few dozen turns of the radio dial. An FM radio tunes from only 88 to 108 megahertz (one megahertz is one million hertz). The axion frequency, by contrast, may be anywhere between 300 hertz and 300 billion hertz. At the rate today’s [Physical Review Letters]detectors [Physical Review Letters] are going, finding the axion or proving that it doesn’t exist could take more than 10,000 years.

    5
    Special superconducting circuits used for quantum computing can help detectors sift through noise that might be hiding an axion signal. Credit: Kelly Backes, CC BY-ND.

    Squeezing the quantum noise

    On the HAYSTAC team, we don’t have that kind of patience. So in 2012 we set out to speed up the axion search by doing everything possible to reduce noise. But by 2017 we found ourselves running up against a fundamental minimum noise limit [Physical Review Letters above] because of a law of quantum physics known as the uncertainty principle.

    The uncertainty principle states that it is impossible to know the exact values of certain physical quantities simultaneously – for instance, you can’t know both the position and the momentum of a particle at the same time. Recall that axion detectors search for the axion by measuring two quadratures – those specific kinds of electromagnetic field oscillations. The uncertainty principle prohibits precise knowledge of both quadratures by adding a minimum amount of noise to the quadrature oscillations.

    In conventional axion detectors, the quantum noise from the uncertainty principle obscures both quadratures equally. This noise can’t be eliminated, but with the right tools it can be controlled. Our team worked out a way to shuffle around the quantum noise in the HAYSTAC detector, reducing its effect on one quadrature while increasing its effect on the other. This noise manipulation technique is called quantum squeezing [Physics Today].

    In an effort led by graduate students Kelly Backes and Dan Palken, the HAYSTAC team took on the challenge of implementing squeezing in our detector, using superconducting circuit technology borrowed from quantum computing research. General-purpose quantum computers remain a long way off, but our new paper shows that this squeezing technology can immediately speed up the search for dark matter.

    5
    Cryogenic cooling helps reduce noise, but by squeezing quantum noise, the HAYSTAC detector can search for an axion signal even faster. Credit: Kelly Backes, CC BY-ND.

    Bigger bandwidth, faster search

    Our team succeeded in squeezing the noise in the HAYSTAC detector. But how did we use this to speed up the axion search?

    Quantum squeezing doesn’t reduce the noise uniformly across the axion detector bandwidth. Instead, it has the largest effect at the edges. Imagine you tune your radio to 88.3 megahertz, but the station you want is actually at 88.1. With quantum squeezing, you would be able to hear your favorite song playing one station away.

    In the world of radio broadcasting this would be a recipe for disaster, because different stations would interfere with one another. But with only one dark matter signal to look for, a wider bandwidth allows physicists to search faster by covering more frequencies at once. In our latest result we used squeezing to double the bandwidth of HAYSTAC, allowing us to search for axions twice as fast as we could before.

    Quantum squeezing alone isn’t enough to scan through every possible axion frequency in a reasonable time. But doubling the scan rate is a big step in the right direction, and we believe further improvements to our quantum squeezing system may enable us to scan 10 times faster.

    Nobody knows whether axions exist or whether they will resolve the mystery of dark matter; but thanks to this unexpected application of quantum technology, we’re one step closer to answering these questions.”

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    The Conversation (AU) launched as a pilot project in October 2014. It is an independent source of news and views from the academic and research community, delivered direct to the public.
    Our team of professional editors work with university and research institute experts to unlock their knowledge for use by the wider public.
    Access to independent, high quality, authenticated, explanatory journalism underpins a functioning democracy. Our aim is to promote better understanding of current affairs and complex issues. And hopefully allow for a better quality of public discourse and conversation.

     
  • richardmitnick 10:52 pm on February 4, 2021 Permalink | Reply
    Tags: "Scintillating discovery: these distant ‘baby’ black holes seem to be misbehaving-and experts are perplexed", , , , , , , , , The Conversation (AU), What is a radio galaxy?   

    From Curtin University (AU) via The Conversation (AU): “Scintillating discovery: these distant ‘baby’ black holes seem to be misbehaving — and experts are perplexed” 

    From Curtin University (AU)

    via

    The Conversation (AU)

    February 4, 2021

    Kathryn Ross
    PhD Student, Curtin University

    Natasha Hurley-Walker
    Radio Astronomer, Curtin University

    1
    Credit: Dr Natasha Hurley-Walker (Curtin / ICRAR) and The GLEAM Team, CC BY-NC.

    Radio images of the sky have revealed hundreds of “baby” and supermassive black holes in distant galaxies, with the galaxies’ light bouncing around in unexpected ways.

    Galaxies are vast cosmic bodies, tens of thousands of light years in size, made up of gas, dust, and stars (like our Sun).

    Given their size, you’d expect the amount of light emitted from galaxies would change slowly and steadily, over timescales far beyond a person’s lifetime.

    But our research, published in MNRAS, found a surprising population of galaxies whose light changes much more quickly, in just a matter of years.

    What is a radio galaxy?

    Astronomers think there’s a supermassive black hole at the centre of most galaxies. Some of these are “active”, which means they emit a lot of radiation.

    Their powerful gravitational fields pull in matter from their surroundings and rip it apart into an orbiting donut of hot plasma called an “accretion disk”.

    This disk orbits the black hole at nearly the speed of light. Magnetic fields accelerate high-energy particles from the disk in long, thin streams or “jets” along the rotational axes of the black hole. As they get further from the black hole, these jets blossom into large mushroom-shaped clouds or “lobes”.

    2
    The radio galaxy Hercules A has an active supermassive black hole at its centre. Here it is pictured emitting high energy particles in jets expanding out into radio lobes. NASA/ESA/NRAO.

    This entire structure is what makes up a radio galaxy, so called because it gives off a lot of radio-frequency radiation. It can be hundreds, thousands or even millions of light years across and therefore can take aeons to show any dramatic changes.

    Astronomers have long questioned why some radio galaxies host enormous lobes, while others remain small and confined. Two theories exist. One is that the jets are held back by dense material around the black hole, often referred to as frustrated lobes.

    However, the details around this phenomenon remain unknown. It’s still unclear whether the lobes are only temporarily confined by a small, extremely dense surrounding environment — or if they’re slowly pushing through a larger but less dense environment.

    The second theory to explain smaller lobes is the jets are young and have not yet extended to great distances.

    Old ones are red, babies are blue

    Both young and old radio galaxies can be identified by a clever use of modern radio astronomy: looking at their “radio colour”.

    We looked at data from the GaLactic and Extragalactic All Sky MWA (GLEAM) survey, which sees the sky at 20 different radio frequencies, giving astronomers an unparalleled “radio colour” view of the sky.

    From the data, baby radio galaxies appear blue, which means they’re brighter at higher radio frequencies. Meanwhile the old and dying radio galaxies appear red and are brighter in the lower radio frequencies.

    We identified 554 baby radio galaxies. When we looked at identical data taken a year later, we were surprised to see 123 of these were bouncing around in their brightness, appearing to flicker. This left us with a puzzle.

    Something more than one light year in size can’t vary so much in brightness over less than one year without breaking the laws of physics. So, either our galaxies were far smaller than expected, or something else was happening.

    Luckily, we had the data we needed to find out.

    Past research on the variability of radio galaxies has used either a small number of galaxies, archival data collected from many different telescopes, or was conducted using only a single frequency.

    For our research, we surveyed more than 21,000 galaxies over one year across multiple radio frequencies. This makes it the first “spectral variability” survey, enabling us to see how galaxies change brightness at different frequencies.

    Some of our bouncing baby radio galaxies changed so much over the year we doubt they are babies at all. There’s a chance these compact radio galaxies are actually angsty teens rapidly growing into adults much faster than we expected.

    While most of our variable galaxies increased or decreased in brightness by roughly the same amount across all radio colours, some didn’t. Also, 51 galaxies changed in both brightness and colour, which may be a clue as to what causes the variability.

    3 possibilities for what is happening

    1) Twinkling galaxies

    As light from stars travels through Earth’s atmosphere, it is distorted. This creates the twinkling effect of stars we see in the night sky, called “scintillation”. The light from the radio galaxies in this survey passed through our Milky Way galaxy to reach our telescopes on Earth.

    Thus, the gas and dust within our galaxy could have distorted it the same way, resulting in a twinkling effect.

    2) Looking down the barrel

    In our three-dimensional Universe, sometimes black holes shoot high energy particles directly towards us on Earth. These radio galaxies are called “blazars”.

    Instead of seeing long thin jets and large mushroom-shaped lobes, we see blazars as a very tiny bright dot. They can show extreme variability in short timescales, since any little ejection of matter from the supermassive black hole itself is directed straight towards us.

    3) Black hole burps

    When the central supermassive black hole “burps” some extra particles they form a clump slowly travelling along the jets. As the clump propagates outwards, we can detect it first in the “radio blue” and then later in the “radio red”.

    So we may be detecting giant black hole burps slowly travelling through space.

    Where to now?

    This is the first time we’ve had the technological ability to conduct a large-scale variability survey over multiple radio colours. The results suggest our understanding of the radio sky is lacking and perhaps radio galaxies are more dynamic than we expected.

    SKA-Mid. Square KIlometer Array, Australia.

    SKA -low frequency at Murchison Widefield Array, Boolardy station in outback Western Australia, at the Murchison Radio-astronomy Observatory (MRO).

    As the next generation of telescopes come online, in particular the Square Kilometre Array (SKA), astronomers will build up a dynamic picture of the sky over many years.

    In the meantime, it’s worth watching these weirdly behaving radio galaxies and keeping a particularly close eye on the bouncing babies, too.

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    The Conversation launched as a pilot project in October 2014. It is an independent source of news and views from the academic and research community, delivered direct to the public.
    Our team of professional editors work with university and research institute experts to unlock their knowledge for use by the wider public.
    Access to independent, high quality, authenticated, explanatory journalism underpins a functioning democracy. Our aim is to promote better understanding of current affairs and complex issues. And hopefully allow for a better quality of public discourse and conversation.

    Curtin University (AU) (formerly known as Curtin University of Technology and Western Australian Institute of Technology) is an Australian public research university based in Bentley and Perth, Western Australia. The university is named after the 14th Prime Minister of Australia, John Curtin, and is the largest university in Western Australia, with over 58,000 students (as of 2016).

    Curtin would like to pay respect to the indigenous members of our community by acknowledging the traditional owners of the land on which the Perth campus is located, the Wadjuk people of the Nyungar Nation; and on our Kalgoorlie campus, the Wongutha people of the North-Eastern Goldfields.

    Curtin was conferred university status after legislation was passed by the Parliament of Western Australia in 1986. Since then, the university has been expanding its presence and has campuses in Singapore, Malaysia, Dubai and Mauritius. It has ties with 90 exchange universities in 20 countries. The University comprises five main faculties with over 95 specialists centres. The University formerly had a Sydney campus between 2005 & 2016. On 17 September 2015, Curtin University Council made a decision to close its Sydney campus by early 2017.

    Curtin University is a member of Australian Technology Network (ATN), and is active in research in a range of academic and practical fields, including Resources and Energy (e.g., petroleum gas), Information and Communication, Health, Ageing and Well-being (Public Health), Communities and Changing Environments, Growth and Prosperity and Creative Writing.

    It is the only Western Australian university to produce a PhD recipient of the AINSE gold medal, which is the highest recognition for PhD-level research excellence in Australia and New Zealand.

    Curtin has become active in research and partnerships overseas, particularly in mainland China. It is involved in a number of business, management, and research projects, particularly in supercomputing, where the university participates in a tri-continental array with nodes in Perth, Beijing, and Edinburgh. Western Australia has become an important exporter of minerals, petroleum and natural gas. The Chinese Premier Wen Jiabao visited the Woodside-funded hydrocarbon research facility during his visit to Australia in 2005.

     
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