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  • richardmitnick 8:08 am on March 2, 2018 Permalink | Reply
    Tags: , , , , , , Neutron stars,   

    From Caltech: “A Better Way to Model Stellar Explosions” 

    Caltech Logo

    Caltech

    03/01/2018

    Whitney Clavin
    (626) 395-1856
    wclavin@caltech.edu

    1
    Artist’s concept of two neutron stars colliding. Credit: NSF/LIGO/Sonoma State University/A. Simonnet

    Caltech scientists create new computer code for calculating neutron stars’ “equation of state”.

    Neutron stars consist of the densest form of matter known: a neutron star the size of Los Angeles can weigh twice as much as our sun.

    Astrophysicists don’t fully understand how matter behaves under these crushing densities, let alone what happens when two neutron stars smash into each other or when a massive star explodes, creating a neutron star.

    One tool scientists use to model these powerful phenomena is the “equation of state.” Loosely, the equation of state describes how matter behaves under different densities and temperatures. The temperatures and densities that occur during these extreme events can vary greatly, and strange behaviors can emerge; for example, protons and neutrons can arrange themselves into complex shapes known as nuclear “pasta.”

    But, until now, there were only about 20 equations of state readily available for simulations of astrophysical phenomena. Caltech postdoctoral scholar in theoretical astrophysics Andre da Silva Schneider decided to tackle this problem using computer codes. Over the past three years, he has been developing open-source software that allows astrophysicists to generate their own equations of state. In a new paper in the journal Physical Review C, he and his colleagues describe the code and demonstrate how it works by simulating supernovas of stars 15 and 40 times the mass of the sun.

    The research has immediate applications for researchers studying neutron stars, including those analyzing data from the National Science Foundation’s Laser Interferometer Gravitational-wave Observatory, or LIGO, which made the first detection of ripples in space and time, known as gravitational waves, from a neutron star collision, in 2017. That event was also witnessed by a cadre of telescopes around the world, which captured light waves from the same event.

    UC Santa Cruz

    UC Santa Cruz

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    A UC Santa Cruz special report

    Tim Stephens

    Astronomer Ryan Foley says “observing the explosion of two colliding neutron stars” [see https://sciencesprings.wordpress.com/2017/10/17/from-ucsc-first-observations-of-merging-neutron-stars-mark-a-new-era-in-astronomy ]–the first visible event ever linked to gravitational waves–is probably the biggest discovery he’ll make in his lifetime. That’s saying a lot for a young assistant professor who presumably has a long career still ahead of him.

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    The first optical image of a gravitational wave source was taken by a team led by Ryan Foley of UC Santa Cruz using the Swope Telescope at the Carnegie Institution’s Las Campanas Observatory in Chile. This image of Swope Supernova Survey 2017a (SSS17a, indicated by arrow) shows the light emitted from the cataclysmic merger of two neutron stars. (Image credit: 1M2H Team/UC Santa Cruz & Carnegie Observatories/Ryan Foley)

    Carnegie Institution Swope telescope at Las Campanas, Chile, 100 kilometres (62 mi) northeast of the city of La Serena. near the north end of a 7 km (4.3 mi) long mountain ridge. Cerro Las Campanas, near the southern end and over 2,500 m (8,200 ft) high, at Las Campanas, Chile

    A neutron star forms when a massive star runs out of fuel and explodes as a supernova, throwing off its outer layers and leaving behind a collapsed core composed almost entirely of neutrons. Neutrons are the uncharged particles in the nucleus of an atom, where they are bound together with positively charged protons. In a neutron star, they are packed together just as densely as in the nucleus of an atom, resulting in an object with one to three times the mass of our sun but only about 12 miles wide.

    “Basically, a neutron star is a gigantic atom with the mass of the sun and the size of a city like San Francisco or Manhattan,” said Foley, an assistant professor of astronomy and astrophysics at UC Santa Cruz.

    These objects are so dense, a cup of neutron star material would weigh as much as Mount Everest, and a teaspoon would weigh a billion tons. It’s as dense as matter can get without collapsing into a black hole.

    THE MERGER

    Like other stars, neutron stars sometimes occur in pairs, orbiting each other and gradually spiraling inward. Eventually, they come together in a catastrophic merger that distorts space and time (creating gravitational waves) and emits a brilliant flare of electromagnetic radiation, including visible, infrared, and ultraviolet light, x-rays, gamma rays, and radio waves. Merging black holes also create gravitational waves, but there’s nothing to be seen because no light can escape from a black hole.

    Foley’s team was the first to observe the light from a neutron star merger that took place on August 17, 2017, and was detected by the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO).


    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

    ESA/eLISA the future of gravitational wave research

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    Skymap showing how adding Virgo to LIGO helps in reducing the size of the source-likely region in the sky. (Credit: Giuseppe Greco (Virgo Urbino group)

    Now, for the first time, scientists can study both the gravitational waves (ripples in the fabric of space-time), and the radiation emitted from the violent merger of the densest objects in the universe.

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    The UC Santa Cruz team found SSS17a by comparing a new image of the galaxy N4993 (right) with images taken four months earlier by the Hubble Space Telescope (left). The arrows indicate where SSS17a was absent from the Hubble image and visible in the new image from the Swope Telescope. (Image credits: Left, Hubble/STScI; Right, 1M2H Team/UC Santa Cruz & Carnegie Observatories/Ryan Foley)

    It’s that combination of data, and all that can be learned from it, that has astronomers and physicists so excited. The observations of this one event are keeping hundreds of scientists busy exploring its implications for everything from fundamental physics and cosmology to the origins of gold and other heavy elements.


    A small team of UC Santa Cruz astronomers were the first team to observe light from two neutron stars merging in August. The implications are huge.

    ALL THE GOLD IN THE UNIVERSE

    It turns out that the origins of the heaviest elements, such as gold, platinum, uranium—pretty much everything heavier than iron—has been an enduring conundrum. All the lighter elements have well-explained origins in the nuclear fusion reactions that make stars shine or in the explosions of stars (supernovae). Initially, astrophysicists thought supernovae could account for the heavy elements, too, but there have always been problems with that theory, says Enrico Ramirez-Ruiz, professor and chair of astronomy and astrophysics at UC Santa Cruz.

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    The violent merger of two neutron stars is thought to involve three main energy-transfer processes, shown in this diagram, that give rise to the different types of radiation seen by astronomers, including a gamma-ray burst and a kilonova explosion seen in visible light. (Image credit: Murguia-Berthier et al., Science)

    A theoretical astrophysicist, Ramirez-Ruiz has been a leading proponent of the idea that neutron star mergers are the source of the heavy elements. Building a heavy atomic nucleus means adding a lot of neutrons to it. This process is called rapid neutron capture, or the r-process, and it requires some of the most extreme conditions in the universe: extreme temperatures, extreme densities, and a massive flow of neutrons. A neutron star merger fits the bill.

    Ramirez-Ruiz and other theoretical astrophysicists use supercomputers to simulate the physics of extreme events like supernovae and neutron star mergers. This work always goes hand in hand with observational astronomy. Theoretical predictions tell observers what signatures to look for to identify these events, and observations tell theorists if they got the physics right or if they need to tweak their models. The observations by Foley and others of the neutron star merger now known as SSS17a are giving theorists, for the first time, a full set of observational data to compare with their theoretical models.

    According to Ramirez-Ruiz, the observations support the theory that neutron star mergers can account for all the gold in the universe, as well as about half of all the other elements heavier than iron.

    RIPPLES IN THE FABRIC OF SPACE-TIME

    Einstein predicted the existence of gravitational waves in 1916 in his general theory of relativity, but until recently they were impossible to observe. LIGO’s extraordinarily sensitive detectors achieved the first direct detection of gravitational waves, from the collision of two black holes, in 2015. Gravitational waves are created by any massive accelerating object, but the strongest waves (and the only ones we have any chance of detecting) are produced by the most extreme phenomena.

    Two massive compact objects—such as black holes, neutron stars, or white dwarfs—orbiting around each other faster and faster as they draw closer together are just the kind of system that should radiate strong gravitational waves. Like ripples spreading in a pond, the waves get smaller as they spread outward from the source. By the time they reached Earth, the ripples detected by LIGO caused distortions of space-time thousands of times smaller than the nucleus of an atom.

    The rarefied signals recorded by LIGO’s detectors not only prove the existence of gravitational waves, they also provide crucial information about the events that produced them. Combined with the telescope observations of the neutron star merger, it’s an incredibly rich set of data.

    LIGO can tell scientists the masses of the merging objects and the mass of the new object created in the merger, which reveals whether the merger produced another neutron star or a more massive object that collapsed into a black hole. To calculate how much mass was ejected in the explosion, and how much mass was converted to energy, scientists also need the optical observations from telescopes. That’s especially important for quantifying the nucleosynthesis of heavy elements during the merger.

    LIGO can also provide a measure of the distance to the merging neutron stars, which can now be compared with the distance measurement based on the light from the merger. That’s important to cosmologists studying the expansion of the universe, because the two measurements are based on different fundamental forces (gravity and electromagnetism), giving completely independent results.

    “This is a huge step forward in astronomy,” Foley said. “Having done it once, we now know we can do it again, and it opens up a whole new world of what we call ‘multi-messenger’ astronomy, viewing the universe through different fundamental forces.”

    IN THIS REPORT

    Neutron stars
    A team from UC Santa Cruz was the first to observe the light from a neutron star merger that took place on August 17, 2017 and was detected by the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO)

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    Graduate students and post-doctoral scholars at UC Santa Cruz played key roles in the dramatic discovery and analysis of colliding neutron stars.Astronomer Ryan Foley leads a team of young graduate students and postdoctoral scholars who have pulled off an extraordinary coup. Following up on the detection of gravitational waves from the violent merger of two neutron stars, Foley’s team was the first to find the source with a telescope and take images of the light from this cataclysmic event. In so doing, they beat much larger and more senior teams with much more powerful telescopes at their disposal.

    “We’re sort of the scrappy young upstarts who worked hard and got the job done,” said Foley, an untenured assistant professor of astronomy and astrophysics at UC Santa Cruz.

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    David Coulter, graduate student

    The discovery on August 17, 2017, has been a scientific bonanza, yielding over 100 scientific papers from numerous teams investigating the new observations. Foley’s team is publishing seven papers, each of which has a graduate student or postdoc as the first author.

    “I think it speaks to Ryan’s generosity and how seriously he takes his role as a mentor that he is not putting himself front and center, but has gone out of his way to highlight the roles played by his students and postdocs,” said Enrico Ramirez-Ruiz, professor and chair of astronomy and astrophysics at UC Santa Cruz and the most senior member of Foley’s team.

    “Our team is by far the youngest and most diverse of all of the teams involved in the follow-up observations of this neutron star merger,” Ramirez-Ruiz added.

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    Charles Kilpatrick, postdoctoral scholar

    Charles Kilpatrick, a 29-year-old postdoctoral scholar, was the first person in the world to see an image of the light from colliding neutron stars. He was sitting in an office at UC Santa Cruz, working with first-year graduate student Cesar Rojas-Bravo to process image data as it came in from the Swope Telescope in Chile. To see if the Swope images showed anything new, he had also downloaded “template” images taken in the past of the same galaxies the team was searching.

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    Ariadna Murguia-Berthier, graduate student

    “In one image I saw something there that was not in the template image,” Kilpatrick said. “It took me a while to realize the ramifications of what I was seeing. This opens up so much new science, it really marks the beginning of something that will continue to be studied for years down the road.”

    At the time, Foley and most of the others in his team were at a meeting in Copenhagen. When they found out about the gravitational wave detection, they quickly got together to plan their search strategy. From Copenhagen, the team sent instructions to the telescope operators in Chile telling them where to point the telescope. Graduate student David Coulter played a key role in prioritizing the galaxies they would search to find the source, and he is the first author of the discovery paper published in Science.

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    Matthew Siebert, graduate student

    “It’s still a little unreal when I think about what we’ve accomplished,” Coulter said. “For me, despite the euphoria of recognizing what we were seeing at the moment, we were all incredibly focused on the task at hand. Only afterward did the significance really sink in.”

    Just as Coulter finished writing his paper about the discovery, his wife went into labor, giving birth to a baby girl on September 30. “I was doing revisions to the paper at the hospital,” he said.

    It’s been a wild ride for the whole team, first in the rush to find the source, and then under pressure to quickly analyze the data and write up their findings for publication. “It was really an all-hands-on-deck moment when we all had to pull together and work quickly to exploit this opportunity,” said Kilpatrick, who is first author of a paper comparing the observations with theoretical models.

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    César Rojas Bravo, graduate student

    Graduate student Matthew Siebert led a paper analyzing the unusual properties of the light emitted by the merger. Astronomers have observed thousands of supernovae (exploding stars) and other “transients” that appear suddenly in the sky and then fade away, but never before have they observed anything that looks like this neutron star merger. Siebert’s paper concluded that there is only a one in 100,000 chance that the transient they observed is not related to the gravitational waves.

    Ariadna Murguia-Berthier, a graduate student working with Ramirez-Ruiz, is first author of a paper synthesizing data from a range of sources to provide a coherent theoretical framework for understanding the observations.

    Another aspect of the discovery of great interest to astronomers is the nature of the galaxy and the galactic environment in which the merger occurred. Postdoctoral scholar Yen-Chen Pan led a paper analyzing the properties of the host galaxy. Enia Xhakaj, a new graduate student who had just joined the group in August, got the opportunity to help with the analysis and be a coauthor on the paper.

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    Yen-Chen Pan, postdoctoral scholar

    “There are so many interesting things to learn from this,” Foley said. “It’s a great experience for all of us to be part of such an important discovery.”

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    Enia Xhakaj, graduate student

    IN THIS REPORT

    Scientific Papers from the 1M2H Collaboration

    Coulter et al., Science, Swope Supernova Survey 2017a (SSS17a), the Optical Counterpart to a Gravitational Wave Source

    Drout et al., Science, Light Curves of the Neutron Star Merger GW170817/SSS17a: Implications for R-Process Nucleosynthesis

    Shappee et al., Science, Early Spectra of the Gravitational Wave Source GW170817: Evolution of a Neutron Star Merger

    Kilpatrick et al., Science, Electromagnetic Evidence that SSS17a is the Result of a Binary Neutron Star Merger

    Siebert et al., ApJL, The Unprecedented Properties of the First Electromagnetic Counterpart to a Gravitational-wave Source

    Pan et al., ApJL, The Old Host-galaxy Environment of SSS17a, the First Electromagnetic Counterpart to a Gravitational-wave Source

    Murguia-Berthier et al., ApJL, A Neutron Star Binary Merger Model for GW170817/GRB170817a/SSS17a

    Kasen et al., Nature, Origin of the heavy elements in binary neutron star mergers from a gravitational wave event

    Abbott et al., Nature, A gravitational-wave standard siren measurement of the Hubble constant (The LIGO Scientific Collaboration and The Virgo Collaboration, The 1M2H Collaboration, The Dark Energy Camera GW-EM Collaboration and the DES Collaboration, The DLT40 Collaboration, The Las Cumbres Observatory Collaboration, The VINROUGE Collaboration & The MASTER Collaboration)

    Abbott et al., ApJL, Multi-messenger Observations of a Binary Neutron Star Merger

    PRESS RELEASES AND MEDIA COVERAGE


    Watch Ryan Foley tell the story of how his team found the neutron star merger in the video below. 2.5 HOURS.

    Press releases:

    UC Santa Cruz Press Release

    UC Berkeley Press Release

    Carnegie Institution of Science Press Release

    LIGO Collaboration Press Release

    National Science Foundation Press Release

    Media coverage:

    The Atlantic – The Slack Chat That Changed Astronomy

    Washington Post – Scientists detect gravitational waves from a new kind of nova, sparking a new era in astronomy

    New York Times – LIGO Detects Fierce Collision of Neutron Stars for the First Time

    Science – Merging neutron stars generate gravitational waves and a celestial light show

    CBS News – Gravitational waves – and light – seen in neutron star collision

    CBC News – Astronomers see source of gravitational waves for 1st time

    San Jose Mercury News – A bright light seen across the universe, proving Einstein right

    Popular Science – Gravitational waves just showed us something even cooler than black holes

    Scientific American – Gravitational Wave Astronomers Hit Mother Lode

    Nature – Colliding stars spark rush to solve cosmic mysteries

    National Geographic – In a First, Gravitational Waves Linked to Neutron Star Crash

    Associated Press – Astronomers witness huge cosmic crash, find origins of gold

    Science News – Neutron star collision showers the universe with a wealth of discoveries

    UCSC press release
    First observations of merging neutron stars mark a new era in astronomy

    Credits

    Writing: Tim Stephens
    Video: Nick Gonzales
    Photos: Carolyn Lagattuta
    Header image: Illustration by Robin Dienel courtesy of the Carnegie Institution for Science
    Design and development: Rob Knight
    Project managers: Sherry Main, Scott Hernandez-Jason, Tim Stephens

    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


    NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam at an altitude of 7200 feet

    Gemini South telescope, Cerro Tololo Inter-American Observatory (CTIO) campus near La Serena, Chile, at an altitude of 7200 feet

    Noted in the vdeo but not in te article:

    NASA/Chandra Telescope

    NASA/SWIFT Telescope

    NRAO/Karl V Jansky VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA

    Prompt telescope CTIO Chile

    NASA NuSTAR X-ray telescope

    “The equations of state help astrophysicists study the outcome of neutron star mergers—they indicate whether a neutron star is ‘soft’ or ‘stiff,’ which in turn determines whether a more massive neutron star or a black hole forms out of the collision,” says da Silva Schneider. “The more observations we have from LIGO and other light-based telescopes, the more we can refine the equation of state—and update our software so that astrophysicists can generate new and more realistic equations for future studies.”

    See the full article here

    That event was also witnessed by a cadre of telescopes around the world, which captured light waves from the same event.

    See the full article here .

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    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

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  • richardmitnick 10:32 am on February 16, 2018 Permalink | Reply
    Tags: , , , , , Neutron stars,   

    From Science Magazine: “Gravitational waves help reveal the weight limit for neutron stars, the densest objects in the cosmos” 

    AAAS
    Science Magazine

    Feb. 15, 2018
    Adrian Cho

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    To derive the new mass limit, astrophysicists teased out the evolution of the famed merger of two neutron stars, spotted on 17 August 2017 and shown in this artist’s conception. University of Warwick/Mark Garlick/Wikimedia Commons (CC BY 4.0)

    How heavy can neutron stars get? Astrophysicists have long wondered how massive these stellar corpses could be without collapsing under their own gravity to form a black hole. Last year’s blockbuster observations of two neutron stars merging revealed a collapse as it happened, enabling four different groups to converge on the maximum mass—about 2.2 times that of the sun.


    “I’m encouraged that they all agree,” says James Lattimer, a nuclear astrophysicist at the State University of New York in Stony Brook. A solid mass limit for neutron stars will help theorists understand these mysterious objects. “Of all the characteristics of a neutron star, the two most important are the maximum mass and the radius,” Lattimer says.

    A dying star can have one of three afterlives. A lightweight star shrinks into a white dwarf, an Earth-size sphere of carbon. A heavy star explodes when its massive core collapses to an infinitesimal point: a black hole. A star in the middle range—8 to 25 solar masses—also explodes, but leaves behind a fantastically dense sphere of nearly pure neutrons measuring a couple of dozen kilometers across: a neutron star.

    As the neutron stars spiraled into each other, gravitational-wave detectors in the United States and Italy sensed ripples in space generated by the whirling bodies. The waves allowed physicists to peg their combined mass at 2.73 solar masses. Two seconds after the gravitational waves, orbiting telescopes detected a powerful, short gamma ray burst. Telescopes on Earth spotted the event’s afterglow, which faded over several days from bright blue to dimmer red.

    Together, the clues suggest the merger first produced a spinning, overweight neutron star momentarily propped up by centrifugal force. The afterglow shows that the merger spewed between 0.1 and 0.2 solar masses of newly formed radioactive elements into space, more than could have escaped from a black hole. The ejected material’s initial blue tint shows that at first, it lacked heavy elements called lanthanides. A flux of particles called neutrinos presumably slowed those elements’ formation, and a neutron star radiates copious neutrinos. The short gamma ray burst, the supposed birth cry of a black hole, indicates that the merged neutron star collapsed in seconds.

    To derive their mass limits, the teams dove into the details of the spinning neutron star. They generally argue that at first the outer layers of the merged neutron star likely spun faster than its center. Then it flung off material and slowed to form a rigid spinning body whose mass researchers could calculate from the masses of the original neutron stars minus the ejected material. The fact that this spinning neutron star survived only momentarily suggests that its mass was close to the limit for such a spinner.

    That last inference is essential, Rezzolla says. Theory suggests that the mass of a rigidly spinning neutron star can exceed that of a stationary one by up to 18%, he says. That scaling allows researchers to infer the maximum mass of a stationary, stable neutron star. The whole argument works because the initial neutron stars weren’t so massive that they immediately produced a black hole or so light that they produced a spinning neutron star that lingered longer, Shibata says. “This was a very lucky event,” he says.

    The analyses are persuasive, Lattimer says, although he quibbles with the precision implied in numbers such as 2.17 solar masses. “If you say 2.2 plus or minus a 10th, I would think it gets the same message across.”

    See the full article here .

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  • richardmitnick 5:09 pm on December 26, 2017 Permalink | Reply
    Tags: 'Direct Collapse' Black Holes May Explain Our Universe's Mysterious Quasars, , , , , , , , Neutron stars, , , Star formation is a violent process, ,   

    From Ethan Siegel: “‘Direct Collapse’ Black Holes May Explain Our Universe’s Mysterious Quasars” 

    From Ethan Siegel
    Dec 26, 2017

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    The most distant X-ray jet in the Universe, from quasar GB 1428, is approximately the same distance and age, as viewed from Earth, as quasar S5 0014+81; both are over 12 billion light years away. X-ray: NASA/CXC/NRC/C.Cheung et al; Optical: NASA/STScI; Radio: NSF/NRAO/VLA

    NASA/Chandra Telescope


    NASA/ESA Hubble Telescope


    NRAO/Karl V Jansky VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA, at an elevation of 6970 ft (2124 m)

    There’s a big problem when we look at the brightest, most energetic objects we can see in the early stages of the Universe. Shortly after the first stars and galaxies form, we find the first quasars: extremely luminous sources of radiation that span the electromagnetic spectrum, from radio up through the X-ray. Only a supermassive black hole could possibly serve as the engine for one of these cosmic behemoths, and the study of active objects like quasars, blazars, and AGNs all support this idea. But there’s a problem: it may not be possible to make a black hole so large, so quickly, to explain these young quasars that we see. Unless, that is, there’s a new way to make black holes beyond what we previously thought. This year, we found the first evidence for a direct collapse black hole, and it may lead to the solution we’ve sought for so long.

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    While distant host galaxies for quasars and active galactic nuclei can often be imaged in visible/infrared light, the jets themselves and the surrounding emission is best viewed in both the X-ray and the radio, as illustrated here for the galaxy Hercules A. It takes a black hole to power an engine such as this. NASA, ESA, S. Baum and C. O’Dea (RIT), R. Perley and W. Cotton (NRAO/AUI/NSF), and the Hubble Heritage Team (STScI/AURA).

    Generically known as ‘active galaxies,’ almost all galaxies posses supermassive black holes at their center, but only a few emit the intense radiation associated with quasars or AGNs. The leading idea is that supermassive black holes will feed on matter, accelerating and heating it, which causes it to ionize and give off light. Based on the light we observe, we can successfully infer the mass of the central black hole, which often reaches billions of times the mass of our Sun. Even for the earliest quasars, such as J1342+0928, we can get up to a mass of 800 million solar masses just 690 million years after the Big Bang: when the Universe was just 5% of its current age.

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    This artist’s concept shows the most distant supermassive black hole ever discovered. It is part of a quasar from just 690 million years after the Big Bang. Robin Dienel/Carnegie Institution for Science.

    If you try to build a black hole in the conventional way, by having massive stars go supernova, form small black holes, and have them merge together, you run into problems. Star formation is a violent process, as when nuclear fusion ignites, the intense radiation burns off the remaining gas that would otherwise go into forming progressively more and more massive stars. From nearby star-forming regions to the most distant ones we’ve ever observed, this same process seems to be in place, preventing stars (and, hence, black holes) beyond a certain mass from ever forming.

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    An artist’s conception of what the Universe might look like as it forms stars for the first time. While stars might reach many hundreds or even a thousand solar masses, it’s very difficult to see how you could get a black hole of the mass the earliest quasars are known to possess. NASA/JPL-Caltech/R. Hurt (SSC).

    We have a standard scenario that’s very powerful and compelling: of supernova explosions, gravitational interactions, and then growth by mergers and accretion. But the early quasars we see are too massive too quickly to be explained by this. Our other known pathway to create black holes, from merging neutron stars, provides no further help. Instead, a third scenario of direct collapse may be responsible. This idea has been helped along by three pieces of evidence in the past year:

    1.The discovery of ultra-young quasars like J1342+0928, in possession of black holes many hundred of millions of solar masses.
    2.Theoretical advances that show how, if the direct collapse scenario is true, we could form early “seed” black holes a thousand times as massive as the ones formed by supernova.
    3.And the discovery of the first stars that become black holes via direct collapse, validating the process.

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    In addition to formation by supernovae and neutron star mergers, it should be possible for black holes to form via direct collapse. Simulations such as the one shown here demonstrate that, under the right condition, seed black holes of 100,000 to 1,000,000 solar masses could form in the very early stages of the Universe. Aaron Smith/TACC/UT-Austin.

    Normally, it’s the hottest, youngest, most massive, and newest stars in the Universe that will lead to a black hole. There are plenty of galaxies like this in the early stages of the Universe, but there are also plenty of proto-galaxies that are all gas, dust, and dark matter, with no stars in them yet. Out in the great cosmic abyss, we’ve even found an example of a pair of galaxies just like this: where one has furiously formed stars and the other one may not have formed any yet. The ultra-distant galaxy, known as CR7, has a massive population of young stars, and a nearby patch of light-emitting gas that may not have yet formed a single star in it.

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    Illustration of the distant galaxy CR7, which last year was discovered to house a pristine population of stars formed from the material direct from the Big Bang. One of these galaxies definitely houses stars; the other may not have formed any yet. M. Kornmesser / ESO.

    In a theoretical study published in March [Nature Astronomy] of this year, a fascinating mechanism for producing direct collapse black holes from a mechanism like this was introduced. A young, luminous galaxy could irradiate a nearby partner, which prevents the gas within it from fragmenting to form tiny clumps. Normally, it’s the tiny clumps that collapse into individual stars, but if you fail to form those clumps, you instead can just get a monolithic collapse of a huge amount of gas into a single bound structure. Gravitation then does its thing, and your net result could be a black hole over 100,000 times as massive as our Sun, perhaps even all the way up to 1,000,000 solar masses.

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    Distant, massive quasars show ultramassive black holes in their cores. It’s very difficult to form them without a large seed, but a direct collapse black hole could solve that puzzle quite elegantly. J. Wise/Georgia Institute of Technology and J. Regan/Dublin City University.

    There are many theoretical mechanisms that turn out to be intriguing, however, that aren’t borne out when it comes to real, physical environments. Is direct collapse possible? We can now definitively answer that question with a “yes,” as the first star that was massive enough to go supernova was seen to simply wink out of existence. No fireworks; no explosion; no increase in luminosity. Just a star that was there one moment, and replaces with a black hole the next. As spotted before-and-after with Hubble, there is no doubt that the direct collapse of matter to a black hole occurs in our Universe.

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    The visible/near-IR photos from Hubble show a massive star, about 25 times the mass of the Sun, that has winked out of existence, with no supernova or other explanation. Direct collapse is the only reasonable candidate explanation. NASA/ESA/C. Kochanek (OSU).

    Put all three of these pieces of information together, and you arrive at the following picture for how these supermassive black holes form so early.

    A region of space collapses to form stars, while a nearby region of space has also undergone gravitational collapse but hasn’t formed stars yet.
    The region with stars emits an intense amount of radiation, where the photon pressure keeps the gas in the other cloud from fragmenting into potential stars.
    The cloud itself continues to collapse, doing so in a monolithic fashion. It expels energy (radiation) as it does so, but without any stars inside.
    When a critical threshold is crossed, that huge amount of mass, perhaps hundreds of thousands or even millions of times the mass of our Sun, directly collapses to form a black hole.
    From this massive, early seed, it’s easy to get supermassive black holes simply by the physics of gravitation, merger, accretion, and time.

    It might not only be possible, but with the new array of radio telescopes coming online, as well as the James Webb Space Telescope, we may be able to witness the process in action.

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

    SKA Square Kilometer Array


    SKA/ASKAP radio telescope at the Murchison Radio-astronomy Observatory (MRO) in Mid West region of Western Australia


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

    The galaxy CR7 is likely one example of many similar objects likely to be out there. As Volker Bromm, the theorist behind the direct collapse mechanism first said [RAS], a nearby, luminous galaxy could cause a nearby cloud of gas to directly collapse. All you need to do is begin with a

    “primordial cloud of hydrogen and helium, suffused in a sea of ultraviolet radiation. You crunch this cloud in the gravitational field of a dark-matter halo. Normally, the cloud would be able to cool, and fragment to form stars. However, the ultraviolet photons keep the gas hot, thus suppressing any star formation. These are the desired, near-miraculous conditions: collapse without fragmentation! As the gas gets more and more compact, eventually you have the conditions for a massive black hole.”

    8
    The directly collapsing star we observed exhibited a brief brightening before having its luminosity drop to zero, an example of a failed supernova. For a large cloud of gas, the luminous emission of light is expected, but no stars are necessary to form a black hole this way.
    NASA/ESA/P. Jeffries (STScI)

    With a little luck, by time 2020 rolls around, this is one longstanding mystery that might finally be solved.

    See the full article here .

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    “Starts With A Bang! is a blog/video blog about cosmology, physics, astronomy, and anything else I find interesting enough to write about. I am a firm believer that the highest good in life is learning, and the greatest evil is willful ignorance. The goal of everything on this site is to help inform you about our world, how we came to be here, and to understand how it all works. As I write these pages for you, I hope to not only explain to you what we know, think, and believe, but how we know it, and why we draw the conclusions we do. It is my hope that you find this interesting, informative, and accessible,” says Ethan

     
  • richardmitnick 1:13 pm on December 20, 2017 Permalink | Reply
    Tags: , , , , , Habitable planets could exist around pulsars, Neutron stars, , The first exoplanets ever discovered were around the pulsar PSR B1257+12,   

    From U Cambridge: “Habitable planets could exist around pulsars” 

    U Cambridge bloc

    University of Cambridge

    19 Dec 2017
    Sarah Collins
    sarah.collins@admin.cam.ac.uk

    1
    It is theoretically possible that habitable planets exist around pulsars – spinning neutron stars that emit short, quick pulses of radiation. According to new research, such planets must have an enormous atmosphere that converts the deadly x-rays and high energy particles of the pulsar into heat. The results, from astronomers at the University of Cambridge and Leiden University, are reported in the journal Astronomy & Astrophysics.

    Pulsars are known for their extreme conditions. Each is a fast-spinning neutron star – the collapsed core of a massive star that has gone supernova at the end of its life. Only 10 to 30 kilometres across, a pulsar possesses enormous magnetic fields, accretes matter, and regularly gives out large bursts of X-rays and highly energetic particles.

    Surprisingly, despite this hostile environment, neutron stars are known to host exoplanets. The first exoplanets ever discovered were around the pulsar PSR B1257+12 – but whether these planets were originally in orbit around the precursor massive star and survived the supernova explosion, or formed in the system later remains an open question. Such planets would receive little visible light but would be continually blasted by the energetic radiation and stellar wind from the host. Could such planets ever host life?

    For the first time, astronomers have tried to calculate the ‘habitable’ zones near neutron stars – the range of orbits around a star where a planetary surface could possibly support water in a liquid form. Their calculations show that the habitable zone around a neutron star can be as large as the distance from our Earth to our Sun. An important premise is that the planet must be a super-Earth, with a mass between one and ten times our Earth. A smaller planet will lose its atmosphere within a few thousand years under the onslaught of the pulsar winds. To survive this barrage, a planet’s atmosphere must be a million times thicker than ours – the conditions on a pulsar planet surface might resemble those of the deep ocean floor on Earth.

    The astronomers studied the pulsar PSR B1257+12 about 2300 light-years away as a test case, using the X-ray Chandra space telescope.

    NASA/Chandra Telescope

    Of the three planets in orbit around the pulsar, two are super-Earths with a mass of four to five times our Earth, and orbit close enough to the pulsar to warm up. According to co-author Alessandro Patruno from Leiden University, “The temperature of the planets might be suitable for the presence of liquid water on their surface. Though, we don’t know yet if the two super-Earths have the right, extremely dense atmosphere.”

    In the future, Patruno and his co-author Mihkel Kama from Cambridge’s Institute of Astronomy would like to observe the pulsar in more detail and compare it with other pulsars. The European Southern Observatory’s ALMA Telescope would be able to show dust discs around neutron stars, which are good predictors of planets. The Milky Way contains about one billion neutron stars, of which about 200,000 are pulsars. So far, 3000 pulsars have been studied and only five pulsar planets have been found.

    See the full article here .

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    U Cambridge Campus

    The University of Cambridge (abbreviated as Cantab in post-nominal letters) 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”.

     
  • richardmitnick 5:34 pm on December 10, 2017 Permalink | Reply
    Tags: , , , , , , , , NASA's SuperTIGER Balloon Flies Again to Study Heavy Cosmic Particles, Neutron stars,   

    From Goddard: “NASA’s SuperTIGER Balloon Flies Again to Study Heavy Cosmic Particles” 

    NASA Goddard Banner
    NASA Goddard Space Flight Center

    Dec. 6, 2017
    Francis Reddy
    francis.j.reddy@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    A science team in Antarctica is preparing to loft a balloon-borne instrument to collect information on cosmic rays, high-energy particles from beyond the solar system that enter Earth’s atmosphere every moment of every day. The instrument, called the Super Trans-Iron Galactic Element Recorder (SuperTIGER), is designed to study rare heavy nuclei, which hold clues about where and how cosmic rays attain speeds up to nearly the speed of light.

    1
    NASA’s Super-TIGER balloon

    The launch is expected by Dec. 10, weather permitting.

    1
    Explore this infographic [on the full article] to learn more about SuperTIGER, cosmic rays and scientific ballooning.
    Credits: NASA’s Goddard Space Flight Center

    Download infographic as PDF

    “The previous flight of SuperTIGER lasted 55 days, setting a record for the longest flight of any heavy-lift scientific balloon,” said Robert Binns, the principal investigator at Washington University in St. Louis, which leads the mission. “The time aloft translated into a long exposure, which is important because the particles we’re after make up only a tiny fraction of cosmic rays.”

    The most common cosmic ray particles are protons or hydrogen nuclei, making up roughly 90 percent, followed by helium nuclei (8 percent) and electrons (1 percent). The remainder contains the nuclei of other elements, with dwindling numbers of heavy nuclei as their mass rises. With SuperTIGER, researchers are looking for the rarest of the rare — so-called ultra-heavy cosmic ray nuclei beyond iron, from cobalt to barium.

    “Heavy elements, like the gold in your jewelry, are produced through special processes in stars, and SuperTIGER aims to help us understand how and where this happens,” said lead co-investigator John Mitchell at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “We’re all stardust, but figuring out where and how this stardust is made helps us better understand our galaxy and our place in it.”

    When a cosmic ray strikes the nucleus of a molecule of atmospheric gas, both explode in a shower of subatomic shrapnel that triggers a cascade of particle collisions. Some of these secondary particles reach detectors on the ground, providing information scientists can use to infer the properties of the original cosmic ray. But they also produce an interfering background that is greatly reduced by flying instruments on scientific balloons, which reach altitudes of nearly 130,000 feet (40,000 meters) and float above 99.5 percent of the atmosphere.

    The most massive stars forge elements up to iron in their cores and then explode as supernovas, dispersing the material into space. The explosions also create conditions that result in a brief, intense flood of subatomic particles called neutrons. Many of these neutrons can “stick” to iron nuclei. Some of them subsequently decay into protons, producing new elements heavier than iron.

    Supernova blast waves provide the boost that turns these particles into high-energy cosmic rays.

    4
    NASA’s Fermi Proves Supernova Remnants Produce Cosmic Rays. February 14, 2013.

    NASA/Fermi Telescope


    NASA/Fermi LAT


    As a shock wave expands into space, it entraps and accelerates particles until they reach energies so extreme they can no longer be contained.

    4
    On Dec. 1, SuperTIGER was brought onto the deck of Payload Building 2 at McMurdo Station, Antarctica, to test communications in preparation for its second flight. Mount Erebus, the southernmost active volcano on Earth, appears in the background.
    Credits: NASA/Jason Link

    Over the past two decades, evidence accumulated from detectors on NASA’s Advanced Composition Explorer satellite and SuperTIGER’s predecessor, the balloon-borne TIGER instrument, has allowed scientists to work out a general picture of cosmic ray sources. Roughly 20 percent of cosmic rays were thought to arise from massive stars and supernova debris, while 80 percent came from interstellar dust and gas with chemical quantities similar to what’s found in the solar system.

    “Within the last few years, it has become apparent that some or all of the very neutron-rich elements heavier than iron may be produced by neutron star mergers instead of supernovas,” said co-investigator Jason Link at Goddard.

    Neutron stars are the densest objects scientists can study directly, the crushed cores of massive stars that exploded as supernovas. Neutron stars orbiting each other in binary systems emit gravitational waves, which are ripples in space-time predicted by Einstein’s general theory of relativity. These waves remove orbital energy, causing the stars to draw ever closer until they eventually crash together and merge.

    Theorists calculated that these events would be so thick with neutrons they could be responsible for most of the very neutron-rich cosmic rays heavier than nickel. On Aug. 17, NASA’s Fermi Gamma-ray Space Telescope and the National Science Foundation’s Laser Interferometer Gravitational-wave Observatory detected the first light and gravitational waves from crashing neutron stars. Later observations by the Hubble and Spitzer space telescopes indicate that large amounts of heavy elements were formed in the event.

    “It’s possible neutron star mergers are the dominant source of heavy, neutron-rich cosmic rays, but different theoretical models produce different quantities of elements and their isotopes,” Binns said. “The only way to choose between them is to measure what’s really out there, and that’s what we’ll be doing with SuperTIGER.”

    SuperTIGER is funded by the NASA Headquarters Science Mission Directorate Astrophysics Division.

    The National Science Foundation (NSF) Office of Polar Programs manages the U.S. Antarctic Program and provides logistic support for all U.S. scientific operations in Antarctica. NSF’s Antarctic support contractor supports the launch and recovery operations for NASA’s Balloon Program in Antarctica. Mission data were downloaded using NASA’s Tracking and Data Relay Satellite System.

    For more information about NASA’s Balloon Program, visit:

    http://www.nasa.gov/balloons

    See the full article here.

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    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.


    NASA/Goddard Campus

     
  • richardmitnick 4:55 am on October 17, 2017 Permalink | Reply
    Tags: , Australia Telescope Compact Array, , , , , , Neutron stars   

    From CSIRO blog: “Global collaboration is making waves in space” 

    CSIRO bloc

    CSIRO blog

    17 October 2017
    Tanya Griffiths

    CSIRO ATCA at the Paul Wild Observatory, about 25 km west of the town of Narrabri in rural NSW about 500 km north-west of Sydney, AU

    Gravitational waves – ripples in space-time produced by massive, accelerating bodies like orbiting black holes or neutron stars – were predicted by Albert Einstein a century ago and first observed in 2015. That detection, of a pair of merging black holes, recently netted the 2017 Nobel Prize in Physics.

    Today’s news that a fifth gravitational wave event has been detected by the international LIGO-Virgo team adds crucial new details to our understanding of the Universe.


    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

    ESA/eLISA the future of gravitational wave research

    1
    Skymap showing how adding Virgo to LIGO helps in reducing the size of the source-likely region in the sky. (Credit: Giuseppe Greco (Virgo Urbino group)

    Telescopes around the world made follow-up observations of this latest event and, for the first time, detected electromagnetic radiation – gamma-rays, light, radio waves and more – along with the gravitational waves.

    An Australian group led by Associate Professor Tara Murphy from the University of Sydney and the ARC Centre of Excellence for All-sky Astrophysics used our Australia Telescope Compact Array near Narrabri in NSW to confirm radio-wave emission from a gravitational wave event discovered on 17 August this year. Their research is published today in the journal Science.

    This is significant because it allows astronomers to determine where the gravitational-wave event took place. Professor Murphy’s team has used more than 40 hours of observing time on the Compact Array over several weeks. Thanks to the telescope’s ‘Target of Opportunity’ system, once alerted to the gravitational-wave event the team was able to quickly gain permission to override scheduled observations and begin using the telescope as soon as the source had risen in the sky above Australia.

    2
    Aerial image of one of the unique L-shaped LIGO Observatories in the US – the Livingston Detector Site. Image: altech MIT LIGO Lab [?].

    The observations suggest that the event that created the gravitational waves was the merger of two neutron stars on the outskirts of the galaxy NGC 4993, about 130 million light-years away. Douglas Bock, Director of our Astronomy and Space Science, said this extraordinary detection by an Australian team, using Australian facilities, made a significant contribution to the global discovery.

    “Running a national facility involves providing researchers with access – fast – so they can monitor unexpected astronomical events of extraordinary scientific interest,” Douglas said.

    The radio source has remained and will continue to be monitored. How much it strengthens and when it reaches peak strength will allow astronomers to better understand the physics of the event. The LIGO team’s detection of gravitational waves – now totalling five separate events – was made possible by thousands of international researchers who’ve contributed to the project, including our own.

    4
    LIGO technician inspecting one of LIGO’s core optics (mirrors) by illuminating its surface with light at a glancing angle. Image: Matt Heintze Caltech MIT LIGO Lab

    Our Manufacturing team was responsible for coating many of the optics used in the ‘Advanced LIGO’ instrumentation including ultra-high performance optical mirrors to give the required reflective properties and thermal shielding. We continue to be one of the only research groups in the world able to deliver to this level of precision.

    Of these latest achievements, our Chief Executive Larry Marshall said “This landmark discovery is an excellent example of the breakthroughs that can be achieved when great minds and organisations unite.

    “As Australia’s national science agency we are proud to have delivered the unique optics that helped enable the original discovery, and are excited to continue supporting the global community through the delivery of excellent science and world-class facilities like the Compact Array whose applications are as unlimited as space itself.”

    See the full article here .

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    CSIRO campus

    CSIRO, the Commonwealth Scientific and Industrial Research Organisation, is Australia’s national science agency and one of the largest and most diverse research agencies in the world.

    The CSIRO blog is designed to entertain, inform and inspire by generally digging around in the work being done by our terrific scientists, and leaving the techie speak and jargon for the experts.

    We aim to bring you stories from across the vast breadth and depth of our organisation: from the wild sea voyages of our Research Vessel Investigator to the mind-blowing astronomy of our Space teams, right through all the different ways our scientists solve national challenges in areas as diverse as Health, Farming, Tech, Manufacturing, Energy, Oceans, and our Environment.

    If you have any questions about anything you find on our blog, we’d love to hear from you. You can reach us at socialmedia@csiro.au.

    And if you’d like to find out more about us, our science, or how to work with us, head over to CSIRO.au

     
  • richardmitnick 7:51 pm on October 16, 2017 Permalink | Reply
    Tags: Astronomers proposed the existence of neutron stars in 1934, , , , , , , , , Neutron stars, Neutron stars have some of the strongest gravity you’ll find – black holes have the strongest, ,   

    From Stanford: “Stanford experts on LIGO’s binary neutron star milestone” 

    Stanford University Name
    Stanford University

    October 16, 2017
    Taylor Kubota
    (650) 724-7707
    tkubota@stanford.edu

    On August 17, 2017, the two detectors of Advanced LIGO, along with VIRGO, zeroed in on what appeared to be gravitational waves emanating from a pair of neutron stars spinning together – a long-held goal for the LIGO team.


    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

    ESA/eLISA the future of gravitational wave research

    1
    Skymap showing how adding Virgo to LIGO helps in reducing the size of the source-likely region in the sky. (Credit: Giuseppe Greco (Virgo Urbino group)

    An alert went out to collaborators worldwide and within hours some 70 instruments turned their sites on the location a mere 310 million light-years away.

    2
    Artist’s rendering of two merging neutron stars. The rippling space-time grid represents gravitational waves that travel out from the collision, while the narrow beams show the bursts of gamma rays that are shot out just seconds after the gravitational waves. Swirling clouds of material ejected from the merging stars glow with visible and other wavelengths of light. (Image credit: NSF/LIGO/Sonoma State University/A. Simonnet)

    Their combined observations, spanning the electromagnetic spectrum, confirm some of what physicists had theorized about this type of event and also open up new areas of research. Thousands of scientists contributed to this accomplishment, including many at Stanford University, and published the initial findings Oct. 16 in Physical Review Letters and The Astrophysical Journal Letters.

    [For science papers, see https://sciencesprings.wordpress.com/2017/10/16/from-hubble-nasa-missions-catch-first-light-from-a-gravitational-wave-event/ ]

    “It’s a frighteningly disordered, energetic place out there in the universe and gravitational waves added a new dimension to looking at it,” said Robert Byer, professor of applied physics at Stanford and member of LIGO who provided the laser for the initial detector. “For this event, that new dimension was complemented by the signals from the other electromagnetic wavelengths and all those together gave us a completely different view of what’s going on inside the neutron stars as they merged.”

    This observation and the others that are likely to follow could help further the understanding of General Relativity, the origins of elements heavier than iron, the evolution of stars and black holes, relativistic jets that squirt from black holes and neutron stars, and the Hubble constant, which is the cosmological parameter which determines the expansion rate of the universe.

    Stanford and LIGO

    LIGO is led by the Massachusetts Institute of Technology and the California Institute of Technology, but Stanford was brought into the collaboration in 1988, largely due to the ultra-clean, stable lasers developed by Byer. The Byer lab developed the chip for the laser in the initial LIGO detector, which they installed in the early 2000s and lasted the lifetime of the initial LIGO project, which concluded in 2010. Lasers for the Advanced LIGO built upon Byer’s earlier work, an effort led by Benno Wilkie of the Albert Einstein Institute Hannover, a former postdoctoral scholar in Stanford’s Ginzton lab.

    “We were looking for the problems that LIGO couldn’t actually worry about yet. We wanted to find those and solve them before they became roadblocks,” said Byer. “One thing that allowed Stanford to contribute to LIGO in these extraordinary ways is we have this long tradition of engineering and science working together – and that’s not common. Great credit also goes to our extraordinary graduate students who are the glue that hold it all together.”

    Daniel DeBra, professor emeritus of aeronautics and astronautics, designed the original platform for LIGO, a nested system so stable that, in the LIGO detection band, it moves no more than an atom relative to the movement of Earth’s surface. Another crucial element of the vibration isolation system is the silicate bonding technique used to suspend LIGO’s mirrors. As a visiting scholar at Stanford, Sheila Rowan of the University of Glasgow adapted this technique from previous work at Stanford on the Gravity Probe B telescope.

    The Dark Energy Camera (DECam), the instrument used by the Dark Energy Survey, was among the first cameras to see in optical light what the LIGO-VIRGO detectors observed in gravitational waves earlier that morning.

    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


    NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam at an altitude of 7200 feet

    DECam imaged the entire area within which the object was expected to be and helped confirm that the event was a unique object – and very likely the event LIGO had seen earlier that day.

    Many people at Stanford and the SLAC National Accelerator Laboratory are part of the Dark Energy Survey team. Aaron Roodman, professor and chair of particle physics and astrophysics at SLAC, developed, commissioned and continues to optimize the Active Optics System of DECam.

    Looking to the future, DeBra and colleagues including Brian Lantz, a senior research scientist who leads the Engineering Test Facility for LIGO at Stanford, are improving signal detection of Advanced LIGO by damping the effects of vibrations on the optics.

    Other faculty are improving the sensitivity of the Fermi Large Area Telescope (LAT), a instrument helmed by Peter Michelson, a professor of physics, that can both confirm the existence of a binary neutron star system and rule out other possible sources. Its sister instrument on Fermi, the Gamma-Ray Burst Monitor, detected a gamma ray burst coming from the location given by LIGO and VIRGO 14 seconds after the gravitational wave signal.

    LIGO is offline for scheduled upgrades for the next year, but many of the researchers are already working on LIGO Voyager, the third-generation of LIGO, which is anticipated to increase the sensitivity by a factor of 2 and would lead to an estimated 800 percent increase in event rate.

    “This is only a beginning. There are many innovations to come and I don’t know where we’re going to be in 10 years, 20 years, 30 years,” said Michelson. “The window is open and there are going to be mind-blowing surprises. That, to me, is the most exciting.”

    What’s so special about neutron stars

    A neutron star results when the core of a large star collapses and the atoms get crushed. The protons and electrons squeeze together and the remaining star is about 95 percent neutrons. A tablespoon full of neutron stars weighs as much as Mt. Everest.

    “Neutron stars have some of the strongest gravity you’ll find – black holes have the strongest – and thus they give us handles on studying strong-field gravity around them to see if it deviates at all from General Relativity,” said Mandeep Gill, the outreach coordinator at KIPAC at SLAC and Stanford, and a member of the Dark Energy Survey collaboration.

    Astronomers proposed the existence of neutron stars in 1934. They were first found in 1967, and then in 1975 a radio telescope observed the first instance of a binary neutron star system. From that discovery, Roger Blandford, professor of physics at Stanford, and colleagues confirmed predictions of the General Theory of Relativity.

    Blandford said the calculations related to the system Advanced LIGO saw are even more complicated because the stars are much closer together and could only be completed by a computer. This observation continues to support the General Theory of Relativity but Gill is hopeful that additional binary neutron star systems may begin to inform extension to the theory that could reveal how it fits with quantum theory, dark energy and dark matter.

    “One of the things I find terribly exciting about these observations is that not only do they confirm aspects of astronomical and relativistic precepts but they actually teach us things about nuclear physics that we don’t properly understand,” said Blandford. “We certainly have many things that we’ve speculated about and thought about – and I have to believe that some of that will be right – but some of it will be much more interesting than what we could anticipate.”

    As we observe more of these systems, which scientists anticipate, we may finally understand long-standing mysteries of neutron stars, like whether they have earthquakes on their crust or if, as suspected, they have small mountains that send out their own gravitational wave signal.

    “Even though we’ve been doing astronomy since the dawn of civilization, every time we turn on new instruments, we learn new things about what’s going on in the universe,” said Lantz. “If the elements heavier than iron are actually made in events like this, that stuff is here on Earth and it’s likely that was generated by events like this. It gives you sort of a way to reach out and touch the stars.”

    Blandford is also KIPAC Division Director in the Particle Physics and Astrophysics Directorate and professor of particle physics and astrophysics at SLAC; Byer is also a professor in SLAC’s Photon Science Directorate.

    Additional Stanford contributors to the LIGO multi-messenger observation include Edgard Bonilla, Riccardo Bassiri, Elliot Bloom, David Burke, Robert Cameron, James Chiang, Carissa Cirelli, C.E. Cunha, Christopher Davis, Seth Digel, Mattia Di Mauro, Richard Dubois, Martin Fejer, Warren Focke, Thomas Glanzman, Daniel Gruen, Ashot Markosyan, Manuel Meyer, Igor Moskalenko, Nicola Omedai, Elena Orlando, Troy Porter, Anita Reimer, Olaf Reimer, Leon Rochester, Aaron Roodman, Eli Rykoff, Brett Shapiro, Rafe Schindler, Jana B. Thayer, John Gregg Thayer, Giacomo Vianello and Risa Wechsler.

    See the full article here .

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    Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

    Stanford University Seal

     
  • richardmitnick 11:57 am on July 18, 2017 Permalink | Reply
    Tags: , , , , , Neutron stars, NICER-Neutron star Interior Composition Explorer   

    From Goddard: “NASA Neutron Star Mission Begins Science Operations” 

    NASA Goddard Banner
    NASA Goddard Space Flight Center

    7.17.17
    Clare Skelly
    NASA’s Goddard Space Flight Center, Greenbelt, Md.
    301-286-4994
    clare.a.skelly@nasa.gov

    1
    This time-lapse animation shows NICER being extracted from the SpaceX Dragon trunk on June 11, 2017. Credits: NASA.

    NASA’s new Neutron star Interior Composition Explorer (NICER) mission to study the densest observable objects in the universe has begun science operations.

    Launched June 3 on an 18-month baseline mission, NICER will help scientists understand the nature of the densest stable form of matter located deep in the cores of neutron stars using X-ray measurements.

    NICER operates around the clock on the International Space Station (ISS). In the two weeks following launch, NICER underwent extraction from the SpaceX Dragon spacecraft, robotic installation on ExPRESS Logistics Carrier 2 on board ISS and initial deployment. Commissioning efforts began June 14, as NICER deployed from its stowed launch configuration. All systems are functioning as expected.

    “No instrument like this has ever been built for the space station,” said Keith Gendreau, the principal investigator for NICER at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “As we transition from an instrument development project to a science investigation, it is important to recognize the fantastic engineering and instrument team who built a payload that delivers on all the promises made.”

    To date, NICER has observed over 40 celestial targets. These objects were used to calibrate the X-ray Timing Instrument and supporting star-tracker camera. The observations also validated the payload’s performance that will enable its key science measurements.


    Several cameras on the International Space Station have eyes on NICER. Since arriving to the space station on June 5 – aboard SpaceX’s eleventh cargo resupply mission – NICER underwent robotic installation on ExPRESS Logistics Carrier 2, initial deployment, precise point tests and more. This video shows segments of NICER’s time in space. Scientists and engineers will continue to watch NICER using these cameras throughout the mission’s science operations. Credits: NASA’s Goddard Space Flight Center.

    Along with the instrument’s transition to full science operations, the embedded Station Explorer for X-ray Timing and Navigation Technology (SEXTANT) demonstration will begin using NICER data to tune the built-in flight software for its first experiment.

    “Our initial timing models use data collected by terrestrial radio telescopes,” said Jason Mitchell, the SEXTANT project manager at Goddard. “Because NICER observes in X-rays, we will account for the difference between the pulses we recover in X-rays compared to our radio models.”

    2
    During NICER commissioning, an observation of low-mass X-ray binary 4U 1608–522 revealed a serendipitous Type I X-ray burst, a flare resulting from a thermonuclear explosion on the surface of a neutron star. 4U 1608 consists of a neutron star in a close orbit with a low-mass star from which it is drawing gas. As this matter accretes and piles up on the neutron star surface, its density in the strong-gravity environment increases until an explosive nuclear fusion reaction is ignited. The heated neutron star surface and atmosphere glow in X-rays, cooling and dimming over the span of about one minute. The hot-spot on the star swings in and out of NICER’s view as the star spins, approximately 619 times each second; these fluctuations in X-ray brightness, and their evolution during the burst, are indicated by the purple contours in the lower panel. NICER provides a unique such bursts, tracing flame propagation and other phenomena through the burst’s temperature and brightness changes over time, with simultaneous fast-timing and spectroscopy capability not previously available.
    Credits: NASA.

    Once NICER collects data on each of SEXTANT’s target pulsars, the software will exploit timing models developed using NICER-only data.

    NICER-SEXTANT is a two-in-one mission. NICER will study the strange, ultra-dense astrophysics objects known as neutron stars to determine how matter behaves in their interiors. SEXTANT will use NICER’s observations of rapidly rotating neutron stars, or pulsars, to demonstrate autonomous X-ray navigation in space.

    3
    GX 301–2, a high mass X-ray binary, is a system in which a massive, aging star’s dense wind is drawn toward the strong gravity of a neutron star. The column of falling material emits X-rays, dominated at certain times by the fluorescent glow of atoms of heavy metals such as iron and nickel. NICER’s X-ray detectors measure the energies (or colors) of X-ray photons – the technique of spectroscopy – to determine the chemical makeup and density of the accreting material in this 1,200-second exposure. Credits: NASA.

    NICER is an Astrophysics Mission of Opportunity within NASA’s Explorer program, which provides frequent flight opportunities for world-class scientific investigations from space utilizing innovative, streamlined, and efficient management approaches within the heliophysics and astrophysics science areas. NASA’s Space Technology Mission Directorate supports the SEXTANT component of the mission, demonstrating pulsar-based spacecraft navigation.

    For more information about NICER, visit:

    https://www.nasa.gov/nicer/

    To download NICER Multimedia:

    https://svs.gsfc.nasa.gov/Gallery/NICER.html

    For more information about SEXTANT, visit:

    https://gameon.nasa.gov/projects/deep-space-x-ray-navigation-and-communication/

    For more information about research and technology on the International Space Station, visit:

    https://www.nasa.gov/mission_pages/station/research/index.html

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.


    NASA/Goddard Campus

     
  • richardmitnick 1:49 pm on June 13, 2017 Permalink | Reply
    Tags: , , , , Dr Wynn Ho, , Neutron stars,   

    From Southampton: “Scientist works with NASA on world’s first neutron star mission” 

    U Southampton bloc

    University of Southampton

    9 June 2017
    No writer credit found

    A University of Southampton scientist will analyse data from the world’s first space mission devoted to the study of neutron stars – collapsed stars containing the densest matter in the Universe.

    1
    NICER is readied for its journey to the ISS. Credit: NASA

    NASA’s Neutron Star Interior Composition Explorer (NICER) mission arrived at the International Space Station this week, and will begin observing neutron stars after its installation as an external payload.

    The refrigerator-sized piece of equipment features 56 X-ray telescopes and silicon detectors to provide high-precision measurements of neutron stars.

    It will also test technology that relies on pulsars – spinning neutron stars that appear to wink on and off like lighthouses – as navigation beacons, a technique which could eventually be used to guide human exploration to the distant reaches of the solar system and beyond.

    Associate Professor Wynn Ho, of the University of Southampton, is an expert in neutron star interior composition, and part of a large team of scientists collaborating on the mission.

    1
    Dr Wynn Ho

    He will compute theoretical models that will be used to compare with the observational data obtained during the 18-month mission.

    He said: “I feel very privileged to be one of the few non-US-based scientists to have a major role in analyses of NICER’s science data. Neutron stars are unique tools for studying fundamental physics in environments that are inaccessible in laboratories on Earth.

    “With NICER, we hope to obtain valuable insights into nuclear and dense matter physics in a way that is complementary to results that will come out of gravitational wave detection of neutron stars, which our group here also works on.”

    Neutron stars are the remnants of massive stars that, after exhausting their nuclear fuel, went supernova and collapsed into super-dense spheres about 15 miles wide. Their intense gravity crushes an astonishing amount of matter — often more than 1.4 times the mass of the Sun, or at least 460,000 Earths — into these city-sized orbs, creating stable but incredibly dense matter not seen anywhere else in the universe. Just one teaspoonful of neutron star matter would weigh a billion tons on Earth.

    Although neutron stars emit radiation across the spectrum, observing them in the X-ray band offers unique insights into their structure and phenomena that can arise from these stars, including starquakes, thermonuclear explosions, and the most powerful magnetic fields in the Universe. NICER will collect X-rays generated from the stars’ tremendously strong magnetic fields and from hotspots located at their two magnetic poles.

    At these locations, the objects’ intense magnetic fields emerge from their interior and particles trapped within these fields rain down and generate X-rays when they strike the stars’ surfaces. In pulsars, these flowing particles emit powerful beams of radiation from the vicinity of the magnetic poles. On Earth these beams of radiation are observed as flashes of radiation ranging from milliseconds to seconds depending on how fast the pulsar rotates.

    Because these pulsations are predictable, they can be used as celestial clocks, providing high-precision timing, like the atomic-clock signals supplied through the Global Positioning System (GPS).

    Although ubiquitous on Earth, GPS signals weaken the farther one travels beyond Earth orbit. Pulsars, however, are accessible virtually everywhere in space, making them a valuable navigational solution for deep-space exploration.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    U Southampton campus

    The University of Southampton is a world-class university built on the quality and diversity of our community. Our staff place a high value on excellence and creativity, supporting independence of thought, and the freedom to challenge existing knowledge and beliefs through critical research and scholarship. Through our education and research we transform people’s lives and change the world for the better.

    Vision 2020 is the basis of our strategy.

    Since publication of the previous University Strategy in 2010 we have achieved much of what we set out to do against a backdrop of a major economic downturn and radical change in higher education in the UK.

    Vision 2020 builds on these foundations, describing our future ambition and priorities. It presents a vision of the University as a confident, growing, outwardly-focused institution that has global impact. It describes a connected institution equally committed to education and research, providing a distinctive educational experience for its students, and confident in its place as a leading international research university, achieving world-wide impact.

     
  • richardmitnick 1:27 pm on May 27, 2017 Permalink | Reply
    Tags: , , , , , , Neutron stars, New NASA Mission to Study Mysterious Neutron Stars and Aid in Deep Space Navigation   

    From Goddard: “New NASA Mission to Study Mysterious Neutron Stars, Aid in Deep Space Navigation” 

    NASA Goddard Banner
    NASA Goddard Space Flight Center

    May 26, 2017
    Claire Saravia
    claire.g.desaravia@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    A new NASA mission is headed for the International Space Station next month to observe one of the strangest observable objects in the universe.

    Launching June 1, the Neutron Star Interior Composition Explorer (NICER) will be installed aboard the space station as the first mission dedicated to studying neutron stars, a type of collapsed star that is so dense scientists are unsure how matter behaves deep inside it.

    NASA/NICER

    NASA NICER

    A neutron star begins its life as a star between about seven and 20 times the mass of our sun. When this type of star runs out of fuel, it collapses under its own weight, crushing its core and triggering a supernova explosion. What remains is an ultra-dense sphere only about 12 miles (20 kilometers) across, the size of a city, but with up to twice the mass of our sun squeezed inside. On Earth, one teaspoon of neutron star matter would weigh a billion tons.

    “If you took Mount Everest and squeezed it into something like a sugar cube, that’s the kind of density we’re talking about,” said Keith Gendreau, the principal investigator for NICER at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.


    Though we know neutron stars are small and extremely dense, there are still many aspects of these remnants of explosive deaths of other stars that we have yet to understand. NICER, a facility to be mounted on the outside of the International Space Station, seeks to find the answers to some of the questions still being asked about neutron stars. By capturing the arrival time and energy of the X-ray photons produced by pulsars emitted by neutron stars, NICER seeks to answer decades-old questions about extreme forms of matter and energy. Data from NICER will also be used in SEXTANT, an on-board demonstration of pulsar-based navigation. Credits: NASA’s Johnson Space Center

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.


    NASA/Goddard Campus

     
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