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  • richardmitnick 8:14 pm on September 13, 2018 Permalink | Reply
    Tags: , Previously it was thought that the orbits of both light and massive stellar objects are distributed [uniformly] around the supermassive black hole, Supermassive Black Holes, Thousands of Black Holes Form Disks in the Center of the Galaxy, Vector resonant relaxation, While black holes orbit in a disk less massive objects like stars form a more spherical distribution   

    From Discover Magazine: “Thousands of Black Holes Form Disks in the Center of the Galaxy” 

    DiscoverMag

    From Discover Magazine

    September 13, 2018
    Chelsea Gohd

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    In this artistic visualization, a supermassive black hole at a galaxy’s center shoots out radiation and high-speed winds. According to a new study, supermassive black holes at a galaxy’s center are surrounded by a disk of black holes and massive stars. (Credit: NASA/JPL-Caltech)

    At the center of most galaxies lie supermassive black holes. Their exceptional gravity pulls in thousands of stars and stellar mass black holes, or black holes formed when a massive star collapses due to gravity.

    By simulating how objects interact near the supermassive black holes in the center of galaxies, astrophysicists from Eötvös University in Hungary have shown, in a new study, that these black holes form a thick disk around a galaxy’s supermassive black hole.

    “Previously it was thought that the orbits of both light and massive stellar objects are distributed [uniformly] around the supermassive black hole,” Ákos Szölgyén, a researcher at Eötvös University who led the study, said in a statement, “we now understand that massive stars and black holes typically segregate into a disk.”

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    Eötvös University

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    An artist’s [now iconic] illustration of the black hole Cygnus X-1. New research shows that thick disks of black holes and massive stars likely form at the center of all galaxies, surrounding supermassive black holes. (Credit: NASA/CXC/M.Weiss)

    Swarm of Black Holes

    In their simulation, Szölgyén and his Ph.D. advisor, Bence Kocsis, incorporated something called vector resonant relaxation. It’s an effect that gravity has on objects orbiting a supermassive black hole. This effect grows over millions of years, making the orbital planes of these objects turn.

    Kocsis compared the effect and the behavior of the objects to the movement of bees, “Unlike a swarm of bees around a beehive, stars fly around in the galactic center in a more ordered way: along precessing elliptical trajectories, each confined to a plane, respectively,” he said in the statement. Kocsis continued, describing how the objects shift their orbits slowly over millions of years.

    This effect helped the astronomers see that while black holes orbit in a disk, less massive objects like stars form a more spherical distribution, Kocsis added in an email.

    Stars usually form in one of two ways at the centers of galaxies. Gas can condense into stars around the supermassive black hole. Or, alternatively, groups of stars called globular clusters can spin into the galaxy’s center, where they’re ripped into the building blocks of new stars by the supermassive black hole. “In both cases, we find a disk of black holes,” Kocsis noted.

    That means these black hole disks probably form in all galaxies.

    Black Hole Disks and Gravitational Waves

    According to Kocsis, this study could also help scientists better understand gravitational waves. As scientists have detected gravitational waves using LIGO and VIRGO, they’ve been surprised to see the rate of black hole mergers is much higher than they expected. “The big question, known as the ‘final AU problem’,” Kocsis explained, is how black holes might get to an AU (or astronomical unit, roughly the distance from the Earth to the sun) that drives them to merge.

    According to Kocsis, better understanding black hole disks could help answer this question because these dense environments “may lead to mergers more often.”

    This study was published in the journal Physical Review Letters.

    See the full article here .

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  • richardmitnick 5:15 pm on September 8, 2018 Permalink | Reply
    Tags: , , QUEST-La Silla AGN Variability Survey, , Supermassive Black Holes   

    From Discover Magazine: “Black Holes Flicker as They Stop Gorging Themselves on Matter” 

    DiscoverMag

    From Discover Magazine

    September 7, 2018
    Alison Klesman

    1
    This artistically enhanced image shows a Hubble Space Telescope view of the active galaxy Arp 220, which houses a feeding supermassive black hole at its center. (Credit: NASA/JPL-Caltech)

    NASA/ESA Hubble Telescope

    Black holes are by nature difficult to study directly. Because even light cannot escape these massive objects, astronomers must turn to other methods to spot and study them. While information is lost once it crosses a black hole’s event horizon, outside that boundary, it can still escape. A recent study, led by a graduate student in the Department of Astronomy of the Universidad de Chile, has now found that the amount of light emitted from around a black hole is determined by one thing, and one thing only: the rate at which matter is falling into the black hole.

    The research, published September 4 in The Astrophysical Journal, was aimed at determining the physical mechanism behind the variability observed from the active black holes at the centers of galaxies (known as active galactic nuclei, or AGN), which are supermassive black holes currently sucking in matter.

    In astronomy, this process is known as accretion. Such black holes have accretion disks, which are disks of matter swirling around them as it is funneled inward, like water going down a drain. Outside the event horizon, these disks shine brightly as the material inside is heated by friction, giving off visible light and even more energetic light, such as X-rays. These disks are also variable — astronomers aren’t exactly sure why, but the current understanding is that as clumps of matter interact in the disk or fall into the black hole, it causes changes in the light the disk emits.

    The team combined data from the Sloan Digital Sky Survey and the QUEST-La Silla AGN Variability Survey to combine physical properties —the mass and the accretion rate, or the speed at which a black hole is eating — of about 2,000 AGN with information about their variability.

    SDSS Telescope at Apache Point Observatory, near Sunspot NM, USA, Altitude 2,788 meters (9,147 ft)

    ESO/Cerro LaSilla, 600 km north of Santiago de Chile at an altitude of 2400 metres.

    What they found was surprising: “Contrary to what was believed, the only important physical property to explain the amplitude of the variability is the AGN accretion rate,” said Paula Sánchez-Sáez, the student who led the study and first author of the paper, in a press release.

    Out With The Old

    Why is this surprising? “The results obtained in this study challenge the old paradigm that the amplitude of the AGN variability depended mainly on the luminosity of the AGN,” Sánchez-Sáez said. What this means is that previously, astronomers assumed that more luminous (brighter) AGN varied more, while less luminous (dimmer) AGN varied less. This study instead discovered that the rate at which a black hole is eating is the only thing that affects the amount its light varies, regardless of whether it is bright or dim.

    But the challenge to previous thinking makes sense, Sánchez-Sáez said, because in the past, it’s been difficult to accurately measure a black hole’s mass, and thus its accretion rate. Only with newer data provided by large surveys can astronomers begin to build up the numbers they need to test their assumptions.

    With Black Holes, Less is More

    Furthermore, the study revealed a relationship that may seem backwards: “What we detect is that the less they [black holes] swallow, the more they vary,” said Paulina Lira of the Universidad de Chile and the CATA Center for Excellence in Astrophysics, and a co-author on the paper. In scientific terms, the amplitude (amount) of variability is inversely proportional to the accretion rate, or the amount of food a black hole is consuming at any given time.

    This initial study was based on variability information from the QUEST-La Silla AGN Variability Survey spanning about five years. Now, the researchers are looking to study the variability of these objects in greater detail, for which they’ll need more data. That means staring at these AGN for longer periods of time — at least 10 years or more. For that, they’ll need to wait for future surveys, such as those proposed with the Large Synoptic Survey Telescope, which is expected to reach full science operations by 2023. This will “extend our light curves to an order of 20 years,” said Lira, providing an even more accurate picture of the black hole’s behavior over longer periods of time.

    See the full article here .

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  • richardmitnick 10:04 am on August 22, 2018 Permalink | Reply
    Tags: , , , , , , , Supermassive Black Holes   

    From Instituto de Astrofísica de Canarias – IAC via Manu Garcia: “Discover the causes of the apparent displacement of a supermassive black hole” 


    From Manu Garcia, a friend from IAC.

    The universe around us.
    Astronomy, everything you wanted to know about our local universe and never dared to ask.

    IAC

    From Instituto de Astrofísica de Canarias – IAC

    Observing the core of Messier 87, HST-1 galaxy.

    1
    Messier 87 image with WFC3 HST (2016) with F814W filter. different knots are seen along the jet, including the first node HST-1. Credit: NASA/ESA Hubble.

    NASA/ESA Hubble Telescope

    NASA/ESA Hubble WFC3

    The study by two researchers from Instituto de Astrofísica reveals that the shift observed in the nucleus of the galaxy Messier 87 is not due to a shift of its massive black hole, but variations in light production in the center of the galaxy caused by bursts from a jet, a flow of material relativistic beam as the hole itself emits.

    Today it is assumed that all massive galaxies contain a supermassive black hole (SMBH, for its acronym in English) at its core. In recent years galaxies are looking for candidates to present a SMBHs displaced from its equilibrium position. Among the scenarios that can cause this displacement are merging two SMBHs or the existence of a binary system SMBHs, which gives information about galactic evolution and formation frequency and fusion of such objects.

    One of the galaxies candidates to present a displaced SMBHs is the giant elliptical Messier 87, containing one of the closest and best-studied active galaxy nuclei (AGN, for its acronym in English). Previous research SMBHs displacement of Messier 87 gave very different results, which was confusing. However, a new study by the student of the University of La Laguna (ULL), Elena López Navas has provided new data suggesting that the SMBHs of this galaxy is in its equilibrium position and shifts found must be variations in the production center or photocentric light caused by bursts from the relativistic jet, a flow of matter that the hole itself expelled outside at speeds near that of light.

    Research has been necessary to analyze a large number of high-resolution images of Messier 87 taken at different times and with different instruments installed on the Hubble Space Telescope (HST) and the Very Large Telescope (VLT).

    ESO VLT at Cerro Paranal in the Atacama Desert, •ANTU (UT1; The Sun ),
    •KUEYEN (UT2; The Moon ),
    •MELIPAL (UT3; The Southern Cross ), and
    •YEPUN (UT4; Venus – as evening star).
    elevation 2,635 m (8,645 ft) from above Credit J.L. Dauvergne & G. Hüdepohl atacama photo

    “Given these results, we realized that the images showed a shift in the center of the galaxy were taken at a time when M87 was a huge explosion that could be measured in all ranges of the electromagnetic spectrum,” adds Almudena Prieto , co-author and researcher at the Institute of Astrophysics of the Canary Islands (IAC). This outbreak took place between 2003 and 2007 at the node nearest the nucleus known as Messier 87 HST-1 jet. During the duration of the phenomenon, this knot increased its flow coming to shine even more than the core itself. “Temporal analysis of displacement of center of the galaxy shows that indeed the burst is related to the change of the position of photocentric – clarifies the astrophysics, however, after this phenomenon, and the core photocentric meet occupying the same place, so we deduce that the core and the black hole are always in the same location coinciding with the minimum of galactic potential. ”

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    Displacements found (in milli – arcseconds) against the date of
    observation of each analyzed image. An increase of displacement is observed
    around 2005, when the maximum emission occurred in the first
    knot jet, HST-1. Credit: Elena Lopez.

    “In our work we have found that the SMBHs is in a stable over the last 20 years position; On the contrary, what changes is the production center of light or Fotocentro “says Lopez, author of this study, as work Master’s Research in Astrophysics, which has just been published in the journal <em>Monthly Notices of the Royal Astronomical Society</em> (MNRAS).

    The new data have caused great interest among the astrophysics community, as the study SMBHs position of M87 is crucial to understanding the evolution of this galaxy and analysis of other AGN jets. “In addition, this research reminds us that we must be cautious when considering variables sources with irregularities such as, in this case, a huge jet,” says Lopez, who is currently conducting a training grant in astrophysical research at the IAC.

    Work Master Thesis: E. Lopez Navas (2018 ULL), “Measurement and analysis of the displacement between the Fotocentro and the supermassive black hole in M87“.

    Contact:
    Elena Lopez Navas, ULL student / IAC: eln_ext@iac.es
    Almudena Prieto Escudero, a researcher at the IAC: aprieto@iac.es

    See the full article here.


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    The Instituto de Astrofísica de Canarias(IAC) is an international research centre in Spain which comprises:

    The Instituto de Astrofísica, the headquarters, which is in La Laguna (Tenerife).
    The Centro de Astrofísica en La Palma (CALP)
    The Observatorio del Teide (OT), in Izaña (Tenerife).
    The Observatorio del Roque de los Muchachos (ORM), in Garafía (La Palma).

    Roque de los Muchachos Observatory is an astronomical observatory located in the municipality of Garafía on the island of La Palma in the Canary Islands, at an altitude of 2,396 m (7,861 ft)

    These centres, with all the facilities they bring together, make up the European Northern Observatory(ENO).

    The IAC is constituted administratively as a Public Consortium, created by statute in 1982, with involvement from the Spanish Government, the Government of the Canary Islands, the University of La Laguna and Spain’s Science Research Council (CSIC).

    The International Scientific Committee (CCI) manages participation in the observatories by institutions from other countries. A Time Allocation Committee (CAT) allocates the observing time reserved for Spain at the telescopes in the IAC’s observatories.

    The exceptional quality of the sky over the Canaries for astronomical observations is protected by law. The IAC’s Sky Quality Protection Office (OTPC) regulates the application of the law and its Sky Quality Group continuously monitors the parameters that define observing quality at the IAC Observatories.

    The IAC’s research programme includes astrophysical research and technological development projects.

    The IAC is also involved in researcher training, university teaching and outreachactivities.

    The IAC has devoted much energy to developing technology for the design and construction of a large 10.4 metre diameter telescope, the ( Gran Telescopio CANARIAS, GTC), which is sited at the Observatorio del Roque de los Muchachos.



    Gran Telescopio Canarias at the Roque de los Muchachos Observatory on the island of La Palma, in the Canaries, SpainGran Telescopio CANARIAS, GTC

     
  • richardmitnick 2:44 pm on August 10, 2018 Permalink | Reply
    Tags: , , , , , Reinhard Genzel from Max Planck Institute for Extraterrestrial Physics (MPE), Supermassive Black Holes, What’s Next for the Heart of the Milky Way   

    From ESOblog: “What’s Next for the Heart of the Milky Way” 

    ESO 50 Large

    From ESOblog


    This artist´s impression shows the path of the star S2 as it passes very close to the supermassive black hole at the centre of the Milky Way. As it gets close to the black hole the very strong gravitational field causes the colour of the star to shift slightly to the red, an effect of Einstein´s general theory of relativity.
    Credit: ESO/M. Kornmesser

    Reinhard Genzel on the significance and future of galactic centre research.

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    10 August 2018

    Reinhard Genzel’s team at the Max Planck Institute for Extraterrestrial Physics (MPE) recently found general relativistic effects during the closest approach of the star S2 to the Sagittarius A*, a supermassive black hole at the centre of the Milky Way.

    Star S2 Keck/UCLA Galactic Center Group

    SgrA* NASA/Chandra


    SGR A* , the supermassive black hole at the center of the Milky Way. NASA’s Chandra X-Ray Observatory

    Sgr A* from ESO VLT

    This discovery is not only a step forward in the research of the galactic centre, but it’s also a great leap in our understanding of physics. In the last of three blog posts, Reinhard Genzel discusses this recent discovery and what future research might look like.

    Q: Firstly can you tell us about the observations your team have just completed?

    A: The star S2 passed very close to the black hole in the centre of our galaxy, the Milky Way, just a few weeks ago. With our long-term preparations for this event, we were able to gather a lot of high-quality data, not only on the position of the star along its orbit, but also on its velocity. Indeed, over the past decade, we developed a completely novel instrument, GRAVITY, which allows us to study the galactic centre in unprecedented detail and ultra-high precision.

    ESO GRAVITY in the VLTI

    Q: Some members of team have worked over 16 years to prepare for these observations, since the last time S2 made a close approach to SgrA*. What have we learned in this time and what have you discovered now?

    A: The first close approach in 2002 and the first full orbit, were dedicated to proving that there is indeed a supermassive black hole at the centre of our Milky Way. Actually, we now believe that all large galaxies harbour a black hole at their core. With the current observing campaign, we focused on studying the black hole in more detail to find out more about general relativistic effects and the properties of the black hole itself — and we have now found evidence of these effects.

    3

    This artist´s impression shows the path of the star S2 as it passes very close to the supermassive black hole at the centre of the Milky Way. As it gets close to the black hole the very strong gravitational field causes the colour of the star to shift slightly to the red, an effect of Einstein´s general theory of relativity. Credit: ESO/M. Kornmesser

    Q: Why are your team’s observations of S2 important?

    A: The black hole in our Milky Way is close enough that we are able to study individual stars near it — we can do that in no other galaxy. The star S2 is special in that it comes very close to the black hole and it completes its orbit in only 16 years. For the other stars, we can only observe part of their orbits — which also gives us some very interesting information — but in the coming years, only S2 dips so deeply into the gravitational well of the black hole.

    Q: What can these observations tell us about general relativity?

    A: We are observing an object in a very strong gravitational field, much stronger than anything that can be observed on Earth. We saw general relativistic effects indicated by the orbital precession, an effect we already know from the orbit of Mercury around the Sun, and the gravitational redshift, wherein the starlight changes frequency due to the strong pull of gravity. While other observations have seen general relativistic effects in a few other astronomical systems, our observations of the heart of the Milky Way, for the first time, tested Einstein’s theory in the extreme gravitational field around a massive black hole.


    Learn more about the first successful test of Einstein´s General Theory of Relativity near a supermassive black hole in ESOcast 173.

    Q: What can these observations tell us about black holes?

    A: First of all, it can tell us that black holes really do exist, and that they are not just a theoretical construct. All our observations show that there is a supermassive black hole at the centre of the Milky Way, if Einstein’s general theory of relativity holds. With this new data we can make a strong case that Einstein is right — and with general relativity in place, the only possible explanation is a black hole.

    Q: What is it about these observations that make them different from the last time S2 made its closest approach to the galactic centre?

    A: To observe the effects that I have mentioned above, we need very accurate data on the orbit of S2 and on its velocity. With the GRAVITY instrument, we now have a hundred-fold improvement in our astrometry, our tracking of stars, compared to the 1990s and about 20 times better data than during the last close flyby. Now, we can even follow the star’s motion from day to day.


    This time-lapse view shows images from the GRAVITY instrument on ESO´s Very Large Telescope as it tracks the progress of the star S2 as it made a close passage past the black hole at the centre of the Milky Way in May 2018. Credit: ESO/GRAVITY Collaboration

    Q: What are you looking forward to learning about the galactic centre in the future? What do you realistically expect to find out in the next few years?

    A: Our first step was to look for one particular post-Newtonian effect, namely, that clocks tick more slowly in a gravitational field. But predictions from the theory of general relativity are far more astonishing. If the black hole has a spin, spacetime itself will rotate, pulling the stars along with it. The unprecedented resolution and sensitivity of our GRAVITY instrument — we hope — will allow us to measure this effect using faint stars at an even closer orbit. Such measurements might also allow us to determine if there are additional massive objects, such as stellar-mass or intermediate-mass black holes, close to the galactic centre as predicted by many theorists. Furthermore, we also hope to see gas orbiting at distances very close to the black hole. We do see gas emission shining up regularly, and we hope to push our instrument a bit further, such that we can see how the emission runs around the black hole – within less than half an hour or so! This would be the full relativistic regime, and correspondingly exciting!

    Q: Why should we continue studying the galactic centre? What mysteries are still unsolved?

    A: The black hole in the galactic centre is the ideal laboratory to study these extreme objects. Ultimately we want to bring together the theories of quantum mechanics and gravitation, which could lead to new physics. Theorists predict that this should happen close to the event horizon, the point from which leaving a black hole becomes impossible.

    See the full article here .


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    ESO ExTrA telescopes at Cerro LaSilla at an altitude of 2400 metres

     
  • richardmitnick 2:35 pm on August 9, 2018 Permalink | Reply
    Tags: , , , , IMBHs-Intermediate Black Holes, , Supermassive Black Holes   

    From Chandra: “Finding the Happy Medium of Black Holes” 

    NASA Chandra Banner

    NASA/Chandra Telescope


    From NASA Chandra

    August 9, 2018
    Press Release
    Megan Watzke
    Chandra X-ray Center, Cambridge, Mass.
    617-496-7998
    mwatzke@cfa.harvard.edu

    1.
    Credit: X-ray: NASA/CXC/ICE/M.Mezcua et al.; Infrared: NASA/JPL-Caltech; Illustration: NASA/CXC/A.Hobart
    Press Image, Caption, and Videos

    Important evidence for populations of intermediate-mass black holes (IMBHs) has been found.

    Using data from Chandra and other telescopes, two teams independently discovered IMBHs relatively nearby and billions of light years away.

    The detection of X-ray emission by Chandra provides critical evidence that IMBHs have been discovered.

    IMBHs may play a significant role in the formation of the very biggest black holes in the early Universe.

    This image shows data from a massive observing campaign that includes NASA’s Chandra X-ray Observatory. These Chandra data have provided strong evidence for the existence of so-called intermediate-mass black holes (IMBHs). Combined with a separate study also using Chandra data, these results may allow astronomers to better understand how the very largest black holes in the early Universe formed, as described in our latest press release.

    The COSMOS (“cosmic evolution survey”) Legacy Survey has assembled data from some of the world’s most powerful telescopes spanning the electromagnetic spectrum. This image contains Chandra data from this survey, equivalent to about 4.6 million seconds of observing time. The colors in this image represent different levels of X-ray energy detected by Chandra. Here the lowest-energy X-rays are red, the medium band is green, and the highest-energy X-rays observed by Chandra are blue. Most of the colored dots in this image are black holes. Data from the Spitzer Space Telescope are shown in grey.

    NASA/Spitzer Infrared Telescope

    The inset shows an artist’s impression of a growing black hole in the center of a galaxy. A disk of material surrounding the black hole and a jet of outflowing material are also depicted.

    Two new separate studies using the Chandra COSMOS-Legacy survey data and other Chandra data have independently collected samples of IMBHs, an elusive category of black holes in between stellar mass black holes and the supermassive black holes found in the central regions of massive galaxies.

    One team of researchers identified 40 growing black holes in dwarf galaxies. Twelve of them are located at distances more than five billion light years from Earth and the most distant is 10.9 billion light years away, the most distant growing black hole in a dwarf galaxy ever seen. Most of these sources are likely IMBHs with masses that are about 10,000 to 100,000 times that of the Sun.

    A second team found a separate, important sample of possible IMBHs in galaxies that are closer to Earth. In this sample, the most distant IMBH candidate is about 2.8 billion light years from Earth and about 90% of the IMBH candidates they discovered are no more than 1.3 billion light years away.

    They detected 305 galaxies in their survey with black hole masses less than 300,000 solar masses. Observations with Chandra and with ESA’s XMM-Newton of a small part of this sample show that about half of the 305 IMBH candidates are likely to be valid IMBHs.

    ESA/XMM Newton

    The masses for the ten sources detected with X-ray observations were determined to be between 40,000 and 300,000 times the mass of the Sun.

    IMBHs may be able to explain how the very biggest black holes, the supermassive ones, were able to form so quickly after the Big Bang. One leading explanation is that supermassive black holes grow over time from smaller black holes “seeds” containing about a hundred times the Sun’s mass. Some of these seeds should merge to form IMBHs. Another explanation is that they form very quickly from the collapse of a giant cloud of gas with a mass equal to hundreds of thousands of times that of the Sun. There is yet to be a consensus among astronomers on the role IMBHs may play.

    A paper describing the COSMOS-Legacy result by Mar Mezcua (Institute for Space Sciences, Spain) and colleagues was published in the August issue of the Monthly Notices of the Royal Astronomical Society and is available online. The paper by Igor Chilingarian (Harvard-Smithsonian Center for Astrophysics) on the closer IMBH sample is being published in the August 10th issue of The Astrophysical Journal and is available online.

    See the full article here .


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    NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra’s science and flight operations from Cambridge, Mass.

     
  • richardmitnick 1:10 pm on July 22, 2018 Permalink | Reply
    Tags: AGN-Active Galatic Nucleus, , , , , , Stellar Mass Black Hole, Supermassive Black Holes   

    From Discover Magazine: “Why Some Black Holes Look Different From Others” 

    DiscoverMag

    From Discover Magazine

    July 16, 2018
    Summer Ash

    1
    Despite having a standard model of an AGN—a supermassive black hole surrounded by an accretion disk with jets streaming out in opposite directions, all encompassed by a dusty torus—making sense of our observations is still a challenge. (Credit: NASA/CXC/CfA/R.Kraft et al.; MPIfR/ESO/APEX/A.Weiss et al.; ESO/WFI)

    NASA/Chandra X-ray Telescope

    ESO/APEX high on the Chajnantor plateau in Chile’s Atacama region, at an altitude of over 4,800 m (15,700 ft)

    ESO WFI LaSilla 2.2-m MPG/ESO telescope at La Silla


    ESO 2.2 meter telescope 600 km north of Santiago de Chile at Cerro LaSilla, at an altitude of 2400 metres

    Astronomers can sometimes be literal to a fault. We like to call things as we see them. For example, if it’s red and it’s huge: “Red Giant.” White and small: “White Dwarf.” Massive explosion: “Big Bang.” Dark and sucks everything in: “Black Hole.” Most of the time, classifying objects this way works fine—either it’s new, or it’s something we already know of. But sometimes, as with Pluto, we make new observations that force us to question the name, reassess the object, and identify it differently. You might think this never happens with something as clearly defined as a black hole, but you’d be wrong.

    Though we can’t observe them directly, we can see how the two types of black holes — stellar mass and supermassive [depicted above] — affect their surroundings. Stellar mass black holes, the product of a dying star going supernova and collapsing on itself, are the more familiar, predicted nearly a century ago by Einstein’s theory of general relativity; they usually only affect the behavior of the nearest star or two. Supermassive black holes, on the other hand, are over a million times more massive. We still don’t know how these form, but we believe they exist at the center of almost every galaxy, sometimes having the power to alter the appearance of their entire galaxy.

    Stellar mass black hole depiction Image Credit NASA /CXC /M. Weiss

    This capacity for mass distortion makes characterizing supermassive black holes particularly tricky. As the stars, gas, and dust in the center of a galaxy get closer and closer to a supermassive black hole, they get packed tighter and tighter into a smaller and smaller space, heating up until, at a critical distance, everything is ripped apart, reduced to atomic particles. When we spot supermassive black holes, it’s this heat radiating away from the orbiting debris—known as an accretion disk — that we actually see, not the black hole itself.

    Some supermassive black holes “eat” more than others and, in the process, give off significantly more light than their less active brethren. These “active galactic nuclei,” or AGN for short, are some of the most powerful, most energetic forces in the Universe.

    2
    AGN-Active Galactic Nucleus depiction from NASA

    Not only do they give off heat, they also often eject material in the form of collimated (beamed) jets, perpendicular to the plane of the disk, which blast their way out of the galaxy’s core — dwarfing in size not just the accretion disk, but also the galaxy itself. What’s more, some AGN have a dusty torus, the geometric equivalent of a donut, in the same plane as their accretion disk, but much, much bigger and thicker. So thick, in fact, that if you looked at them from the side, you wouldn’t see the disk at all, much less the black hole in the center (as seen in the image above).

    Despite having this standard model of an AGN—a supermassive black hole surrounded by an accretion disk with jets streaming out in opposite directions, all encompassed by a dusty torus — making sense of our observations is still a challenge: The light we see doesn’t always paint the same picture. Sometimes we see jets, sometimes we don’t. Sometimes we see the torus, sometimes we don’t. Sometimes we see light so concentrated and bright that we can’t even tell if there’s a galaxy there at all. We label these sightings accordingly: AGN at great distances with cores so bright, they outshine all their stars in optical light, are called quasars (for “quasi-stellar”), like the one pictured above; AGN that glow strongly in the infrared are called Seyferts, after the astronomer Carl Seyfert, who first identified them in 1943; And AGN, with cores and jets whose emitted light dominates in the radio spectrum, are called radio galaxies.

    If they are all fueled by supermassive black holes, why don’t all AGN look the same? One reason could be our point of view. The theory of AGN unification posits that all AGN have the same basic building blocks (accretion disk, jets, torus); The striking differences we observe, according to this theory, are all due to their orientation in space.

    Here on Earth, we only have one vantage point from which to observe the cosmos. We see galaxies randomly distributed around us, some of them edge-on, some of them face-on, and the rest at all the angles in-between. We cannot fly around to look at these galaxies from any other angle than the one they present to us. But with the advent of supercomputers, we can now simulate these galaxies better than ever before and virtually fly around them as much as we like, enjoying the sights from any angle. We can take an AGN and turn it so we’re looking straight down one of the jets, towards the galactic core, making it resemble a blazar, sort of a blazing quasar. Start tilting the AGN until the jet is rotated ninety degrees away from us, and it appears to morph from a blazar to a quasar to, finally, a Seyfert.

    Yet AGN unification is far from a settled problem in astrophysics. There could be other factors at play than just our point of view, like physical processes in and around black holes we don’t fully understand or measurements we haven’t thought to take. As we build better telescopes and amass new data, we can only hope that we’ll see these active galactic nuclei for what they really are. Otherwise, we might need a lot more names.

    See the full article here .

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  • richardmitnick 1:37 pm on July 13, 2018 Permalink | Reply
    Tags: , , , Biggest neutrino event ever from IceCube, , , IceCube-170922A, , Supermassive Black Holes,   

    The Great Neutrino Catch: A Bunch of Articles 

    IceCube

    U Wisconsin ICECUBE neutrino detector at the South Pole

    IceCube employs more than 5000 detectors lowered on 86 strings into almost 100 holes in the Antarctic ice NSF B. Gudbjartsson, IceCube Collaboration

    Lunar Icecube

    IceCube DeepCore annotated

    IceCube PINGU annotated


    DM-Ice II at IceCube annotated

    ARTICLES

    From Nature Magazine Single subatomic particle illuminates mysterious origins of cosmic rays

    When a subatomic particle from space streaked through Antarctica last September, astrophysicists raced to find the source.

    13 July 2018
    Davide Castelvecchi

    A single subatomic particle detected at the South Pole last September is helping to solve a major cosmic mystery: what creates electrically charged cosmic rays, the most energetic particles in nature.

    Follow-up studies by more than a dozen observatories suggest that researchers have, for the first time, identified a distant galaxy as a source of high-energy neutrinos

    This discovery could, in turn, help scientists pin down the still mysterious source of protons and atomic nuclei that arrive to Earth from outer space, collectively called cosmic rays. The same mechanisms that produce cosmic rays should also make high-energy neutrinos.

    Multiple teams of researchers from around the world describe the neutrino’s source in at least seven papers released on 12 July.

    “Everything points to this as the ultra-bright, energetic source — a gorgeous source,” says Elisa Resconi, an astroparticle physicist at the Technical University of Munich in Germany.

    Astrophysicists have proposed a number of scenarios for astrophysical phenomena that could produce both high-energy neutrinos and their electrically charged counterparts: protons and atomic nuclei collectively called cosmic rays. But until now, they had not managed to unambiguously trace any of these particles back to their source. This is especially difficult with cosmic rays, whose electric charges make their paths curve on their way to Earth, whereas neutrinos travel in straight lines.

    The finding also underscores the promise of ‘multi-messenger’ astronomy, a nascent field that combines signals from different types of observatory to pin down details of celestial events.

    Muon alert

    The story began on 22 September 2017, when an electrically charged particle called a muon streaked through the Antarctic ice cap at close to the speed of light. IceCube — an array of more than 5,000 sensors buried in a cubic kilometre’s worth of ice — detected flashes of light that the muon produced in its wake. The particle appeared to emerge from below the detector — an orientation that indicated that it was the decay product of a neutrino that had come from below the horizon. Muons can only travel so far inside matter, whereas neutrinos often pass through the entire planet unimpeded; most of the ones that IceCube detects have crashed with a particle inside Earth to produce a muon (see ‘Neutrino observatory’).

    Within seconds, a computer cluster at the US National Science Foundation’s Amundsen–Scott South Pole Station, which sits atop Earth’s southernmost point, had reconstructed the precise path of the particle and recognized that the muon had come from a highly energetic neutrino; 43 seconds after the event, the station sent an automated alert to a network of astronomers via a satellite link. It tagged the neutrino as IceCube-170922A.

    After receiving the alert, Derek Fox, an astrophysicist at Pennsylvania State University in University Park, quickly secured observing time on the X-ray observatory Swift, which orbits Earth.

    NASA Neil Gehrels Swift Observatory

    Fox had created the automated alert system two years before, precisely in the hope that researchers could follow up on events such as this one.

    He and his team found nine sources of high-energy X-rays close to where the neutrino had come from. Among them was an object called TXS 0506+056. This was a blazar, a galaxy with a supermassive black hole at the centre and a known source of γ-rays. In a blazar, the black hole stirs gas up to temperatures of millions of degrees and shoots it out of its poles in two highly collimated jets, one of which points in the direction of the Solar System. Fox’s team announced its findings to the astronomical community the next day after.

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    Flare up

    In the following days, another team inspected data from the Large Area Telescope (LAT) aboard NASA’s Fermi Gamma-ray Space Telescope.

    NASA/Fermi LAT


    NASA/Fermi Gamma Ray Space Telescope

    LAT constantly sweeps the sky, and among other things monitors about 2,000 blazars. These objects go through periods of increased activity that can last weeks or months, during which they become unusually bright. “When we looked at the region that IceCube said the neutrino came from, we noticed that this blazar had been flaring more than ever before,” says Regina Caputo, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who is Fermi-LAT’s analysis coordinator.

    On 28 September, the Fermi-LAT team sent out an alert to reveal this finding. It was at that point that other astronomers got very excited. IceCube has detected about a dozen such high-energy neutrinos each year since it started operating in 2010, but none had been associated with a particular source in the sky. “That’s what made the hair stand at the back of the neck,” Fox says.

    Still, the association between the neutrino and the TXS blazar flare could have been a coincidence. To make the case stronger, researchers from both IceCube and Fermi-LAT calculated the odds that the flare and the neutrino were related, rather than coming from the same direction in the sky by chance.

    “We had to calculate the chance that random neutrinos in the sky come from one of the known gamma-ray sources, and the likelihood that it was flaring at that time,” says Anna Franckowiak, an astroparticle physicist at the German Electron Synchrotron (DESY) in Zeuthen who is a member of both IceCube and Fermi-LAT. She and her collaborators found that likelihood to be good, though not at the level of statistical significance required for claiming a discovery in physics.

    Evidence hunt

    Finding more neutrinos and gamma rays detected during a previous flare from the same blazar would boost the evidence for TXS 0506+056 being the source. In November, IceCube researchers found that the observatory had recorded an excess of neutrinos coming from the same direction in the sky between late 2014 and 2015.

    Resconi, who is a senior member of IceCube, got so excited by the discovery that she got lost while driving to a Nick Cave concert after work. “I ended up in the open countryside. My colleagues now tease me that next time we see a neutrino source, who knows where I will end up.”

    Soon though, the researchers realized that this apparent flare did not seem to show up in Fermi-LAT data. “That news came as a wet blanket,” Resconi says. But in a separate study, she and her collaborators found hints of a TXS flare during that period, but with gamma rays of energies that were mostly too high for Fermi-LAT to detect.

    A major missing piece of information was the blazar’s distance from Earth, says Simona Paiano of the Astronomical Observatory of Padua in Italy. To measure it, she and her team booked 15 hours of observing time on the world’s largest optical telescope, the 10.4-metre Gran Telescopio Canarias on La Palma, one of Spain’s Canary Islands.

    Gran Telescopio Canarias at the Roque de los Muchachos Observatory on the island of La Palma, in the Canaries, Spain, sited on a volcanic peak 2,267 metres (7,438 ft) above sea level

    They found it to be around 1.15 billion parsecs (3.78 billion light years) away.

    Together, the data pinpoint the likely source, says Kyle Cranmer, a particle physics and data-analysis expert at New York University, but “the observation isn’t unambiguous”, he says. “More follow-up is needed to conclusively establish blazars as a source of high-energy neutrinos.

    Researchers hope that this is only the first of many multi-messenger events of this kind.They are especially looking forward to detecting neutrinos together with gravitational waves. The celebrated collision of two neutron stars that was discovered using gravitational waves in August 2017 should have produced neutrinos as well, but IceCube did not detect any. But if the TXS blazar flares up again, it might be possible to detect more high-energy neutrinos and other kinds of radiation coming from it.

    From Astronomy Magazine

    July 12, 2018
    Michelle Hampson

    The rare detection of a high-energy neutrino hints at how these strange particles are created.

    Four billion years ago, an immense galaxy with a black hole at its heart spewed forth a jet of particles at nearly the speed of light. One of those particles, a neutrino that is just a fraction of the size of a regular atom, traversed across the universe on a collision course for Earth, finally striking the ice sheet of Antarctica last September. Coincidentally, a neutrino detector planted by scientists within the ice recorded the neutrino’s charged interaction with the ice, which resulted in a blue flash of light lasting just a moment. The results are published today in the journal Science.

    This detection marks the second time in history that scientists have pinpointed the origins of a neutrino from outside of our solar system. And it’s the first time they’ve confirmed that neutrinos are created in the supermassive black holes at the centers of galaxies — a somewhat unexpected source.

    Neutrinos are highly energetic particles that rarely ever interact with matter, passing through it as though it weren’t even there. Determining the type of cosmological events that create these particles is critical for understanding the nature of the universe. But the only confirmed source of neutrinos, other than our Sun, is a supernova that was recorded in 1987.

    Physicists have a number of theories about what sort of astronomical events may create neutrinos, with some suggesting that blazars could be a source. Blazars are massive galaxies with black holes at their center, trying to suck in too much matter at once, causing jets of particles to be ejected outward at incredible speeds. Acting like the giant counterparts to terrestrial particle accelerators, blazar jets are believed to produce cosmic rays that can in turn create neutrinos.

    “This [detection] in particular is a chance of nature,” says Darren Grant, a lead scientist of the team that first discovered the high-energy neutrino, as part of the neutrino detection project IceCube. “There’s a blazar there that just happened to turn on at the right time and we happened to capture it. It’s one of those eureka moments. You hope to experience those a few times in your career and this was one of them, where everything aligned.”

    4
    Blazars are active supermassive black holes sucking in immense amounts of material, which form swirling accretion disks and generate high-powered particle jets that churn out particles that astronomers have believed eventually result in neutrinos. DESY, Science Communication Lab

    A cosmic messenger

    On September 22, 2017, the neutrino reached the Antarctica ice sheet, passing by an ice crystal at just the right angle to cause a subatomic particle (called a muon) to be created from the interaction. The resulting blue flash was recorded by one of IceCube’s 5,160 detectors, embedded within the ice. Grant was in the office when the detection occurred. This neutrino was about 300 million times more energetic than those that are emitted by the Sun.

    Grant and his colleague briefly admired the excellent image depicting the trajectory of the muon, which provides basic information necessary to begin tracing back the neutrino’s origin. However, they weren’t overly excited quite yet. His team observes about 10 to 20 high-energy neutrinos each year, but the right combination of events — in space, time and energy, for example — is required to precisely pinpoint the source of the neutrino. Such an alignment had eluded scientists so far. As Grant’s team began their analysis, though, they began to narrow in on a region: an exceptionally bright blazar called TXS 0506+056.

    Upon the detection, an automatic alert was sent to other astronomy teams around the world, which monitor various incoming cosmic signals, such as radio and gamma rays. A few days later a team of scientists using the MAGIC telescope in the Canary Islands responded with some exciting news: the arrival of the neutrino had coincided with a burst of gamma rays – which are extremely energetic photons – also coming from the direction of TXS 0506+056.

    MAGIC Cherenkov telescope array at the Roque de los Muchachos Observatory on the island of La Palma, in the Canaries, Spain, sited on a volcanic peak 2,267 metres (7,438 ft) above sea level

    Other teams analyzing the region following the initial detection observed changes in X-ray emissions and radio signals too. Collectively, the data is a huge step forward for physicists in understanding blazars, and high-energy cosmological events in general.

    John Learned of University of Hawaii, Manoa, who was not involved in the study, says that the data linking the blazar as the source is “overwhelmingly convincing” and he emphasizes the importance of this finding. “This is the realization of many long-standing scientific dreams. Neutrinos at high energies can tell us about the guts of these extremely luminous objects … The implications of the finding are that we are now finally … [able] to see inside the most dense and luminous objects, and to further our grasp of the ‘deus ex machina’ which drives them and powers these awesome phenomena.”

    For example, this detection also provides the first evidence that a blazar can produce the high-energy protons needed to generate neutrinos such as the one IceCube saw. Sources of high-energy protons also remain largely a mystery, so the identification of one such source is another big step forward for astronomers. “It’s really quite convincing that we’ve unlocked one piece of that puzzle,” says Grant.

    Gems from the past

    And it gets even better. “We looked back at [archival] data [that had been collected since 2010], in the direction of this particular blazar source, and what we discovered was really quite remarkable,” Grant says. A barrage of high-energy neutrinos and gamma rays from TXS 0506+056 reached Earth in late 2014 and early 2015. At the time, IceCube’s real-time alert system was not fully functioning, so other scientific teams were not aware of the detection. But now these previous neutrinos are on scientists’ radar, providing a more long-term glimpse into the life of a blazar.

    “That was really icing on the cake, because what [the archived data indicated] was that the source had been active in neutrinos in the past, and then again, with this very high-energy neutrino in September — those are the pieces that really start to come together, to make a picture of what’s happening there,” explains Grant.

    6
    The alert IceCube sent once the neutrino’s interaction with the ice was detected resulted in follow-up observations from about 20 Earth- and space-based observatories. This immense effort resulted in the clear identification of a distant blazar as the source of the neutrino — as well as gamma rays, X-rays, radio emission, and optical light.
    Nicolle R. Fuller/NSF/IceCube

    Previous coverage https://sciencesprings.wordpress.com/2018/07/12/from-nrao-via-newswise-vla-gives-tantalizing-clues-about-source-of-energetic-cosmic-neutrino/

    The data also reveal that radio emissions from TXS 0506+056 gradually increased in the 18 months leading up to the September neutrino detection. Greg Sivakoff, an associate professor at the University of Alberta who helped analyze the data, says one possibility is that the black hole began to consume surrounding matter much faster during this time, causing the jet of particles being emitted to speed up. He says, “If the jet gets too fast too quickly, it might run into some of its own material, creating what astronomers call a shock. Shocks have long been used in astronomy to explain how particles are accelerated to high energies. We are not sure that this is the answer yet, but this may be part of the story.”

    Scientists are continuing to monitor TXS 0506+056, hoping to learn more about this colossal event. One team conducted a detailed analysis to determine how far away the blazar is from us, astounded to discover that it is a whopping four billion light years away. While TXS 0506+056 was always considered a bright object in the sky, this luminosity at such a distance makes it one of the brightest objects in the universe. No doubt future studies of this powerful blazar will yield valuable insights into the most energetic events to occur in our universe.

    Learned says, “We are just opening a new door and I would love to be able to say what we shall find beyond. But I guarantee that initiating this new means of observing the universe will bring surprises and new insights. In an extreme analogy it is like asking Galileo what his new astronomical telescope will reveal.”

    From UCSC: VERITAS supplies critical piece to neutrino discovery puzzle

    July 12, 2018
    Megan Watzke, CfA

    Potential connection between blazar and neutrino detection by IceCube observatory marks a new advance in multi-messenger astrophysics

    CfA/VERITAS, a major ground-based gamma-ray observatory with an array of four 12m optical reflectors for gamma-ray astronomy in the GeV – TeV energy range. Located at Fred Lawrence Whipple Observatory, Mount Hopkins, Arizona, US in AZ, USA, Altitude 2,606 m (8,550 ft)

    7
    One of the telescopes in the Very Energetic Radiation Imaging Telescope Array System (VERITAS), Located at Fred Lawrence Whipple Observatory, Mount Hopkins, Arizona, US in AZ, USA. VERITAS is operated and managed by the Smithsonian Astrophysical Observatory. (Photo by Wystan Benbow)

    The VERITAS array has confirmed the detection of gamma rays from the vicinity of a supermassive black hole. While these detections are relatively common for VERITAS, this black hole is potentially the first known astrophysical source of high-energy cosmic neutrinos, a type of ghostly subatomic particle.

    On September 22, 2017, the IceCube Neutrino Observatory, a cubic-kilometer neutrino telescope located at the South Pole, detected a high-energy neutrino of potential astrophysical origin. However, the observation of a single neutrino by itself is not enough for IceCube to claim the detection of a source. For that, scientists needed more information.

    Very quickly after the detection by IceCube was announced, telescopes around the world including VERITAS (which stands for the “Very Energetic Radiation Imaging Telescope Array System”) swung into action to identify the source. The VERITAS, MAGIC [above], and H.E.S.S. gamma-ray observatories all looked at the neutrino position.

    HESS Cherenkov Telescope Array, located on the Cranz family farm, Göllschau, in Namibia, near the Gamsberg searches for cosmic rays, altitude, 1,800 m (5,900 ft)

    In addition, two gamma-ray observatories that monitor much of the sky at lower and higher energies also provided coverage.

    These follow-up observations of the rough IceCube neutrino position suggest that the source of the neutrino is a blazar, which is a supermassive black hole with powerful outflowing jets that can change dramatically in brightness over time. This blazar, known as TXS 0506+056, is located at the center of a galaxy about 4 billion light years from Earth.

    “We know that the blazar jet is accelerating particles to very high energies, but it is difficult to tell from gamma rays alone if it is accelerating just electrons or also protons and heavier nuclei,” said David Williams, adjunct professor of physics at UC Santa Cruz and the Santa Cruz Institute for Particle Physics (SCIPP) and a member of the VERITAS collaboration. “If the blazar is a neutrino source, that’s a smoking gun for protons, because high-energy protons colliding with gas produce pions, which decay into neutrinos,” he said.

    Initially, NASA’s Fermi Gamma-ray Space Telescope [above] observed that TXS 0506+056 was several times brighter than usually seen in its all-sky monitoring. Eventually, the MAGIC observatory made a detection of much higher-energy gamma rays within two weeks of the neutrino detection, while VERITAS, H.E.S.S., and HAWC did not see the blazar in any of their observations during the two weeks following the alert.

    Given the importance of higher-energy gamma-ray detections in identifying the possible source of the neutrino, VERITAS continued to observe TXS 0506+056 over the following months, through February 2018, and revealed the source but at a dimmer state than what was detected by MAGIC.

    “The VERITAS detection shows us that the gamma-ray brightness of the source changes, which is a signature of a blazar,” said Wystan Benbow of the Smithsonian Astrophysical Observatory (SAO), which operates and manages VERITAS. “Finding a link between an astrophysical source and a neutrino event could open yet another window of exploration to the extreme universe.”

    Cosmic rays

    The detection of gamma rays coincident with neutrinos is tantalizing, since both particles must be produced in the generation of cosmic rays. Since they were first detected over 100 years ago, cosmic rays—highly energetic particles that continuously rain down on Earth from space—have posed an enduring mystery. What creates and launches these particles across such vast distances? Where do they come from?

    “The potential connection between the neutrino event and TXS 0506+056 would shed new light on the acceleration mechanisms that take place at the core of these galaxies and provide clues on the century-old question of the origin of cosmic rays,” said coauthor and VERITAS spokesperson Reshmi Mukherjee of Barnard College, Columbia University in New York.

    “Astrophysics is entering an exciting new era of multi-messenger observations, in which celestial sources are being studied through the detection of the electromagnetic radiation they emit across the spectrum, from radio waves to high-energy gamma rays, in combination with non-electromagnetic means, such as gravitational waves and high-energy neutrinos,” said coauthor Marcos Santander of the University of Alabama in Tuscaloosa, who led the study.

    A paper describing the deep VERITAS observations of TXS 0506+056 (“VERITAS Observations of the BL Lac Object TXS 0506+056”) has been accepted for publication in The Astrophysical Journal Letters and appears online on July 12, 2018. A paper on the IceCube and initial gamma-ray observations, including VERITAS’s, appears in the latest issue of the journal Science.

    “This is a terrific step forward in multi-messenger astrophysics,” said Williams, who worked on the analysis of the VERITAS data and coordinated the VERITAS contributions to the Science paper.

    VERITAS is a ground-based facility located at the SAO’s Fred Lawrence Whipple Observatory in southern Arizona. It consists of an array of four 12-meter optical telescopes that can detect gamma rays via the extremely brief flashes of blue “Cherenkov” light created when gamma rays are absorbed in the Earth’s atmosphere. The VERITAS Collaboration consists of about 80 scientists from 20 institutions in the United States, Canada, Germany and Ireland.

    The Fermi-LAT Collaboration [above], which also played an important role in this research, includes researchers at the Santa Cruz Institute for Particle Physics at UC Santa Cruz.

    From ESA INTEGRAL joins multi-messenger campaign to study high-energy neutrino source

    12 July 2018
    Erik Kuulkers
    ESA INTEGRAL Project Scientist
    European Space Agency
    Tel: +31 6 30249526
    Email: Erik.Kuulkers@esa.int

    Carlo Ferrigno
    INTEGRAL Science Data Centre
    University of Geneva, Switzerland
    Email: Carlo.Ferrigno@unige.ch

    Volodymyr Savchenko
    INTEGRAL Science Data Centre
    University of Geneva, Switzerland
    Email: Volodymyr.Savchenko@unige.ch

    Francis Halzen
    IceCube Principal Investigator
    University of Wisconsin–Madison, USA
    Email: francis.halzen@icecube.wisc.edu

    Sílvia Bravo Gallart
    IceCube Press Office
    University of Wisconsin–Madison, USA
    Email: silvia.bravo@icecube.wisc.edu

    Markus Bauer
    ESA Science Communication Officer
    Tel: +31 71 565 6799
    Mob: +31 61 594 3 954
    Email: markus.bauer@esa.int

    An international team of scientists has found first evidence of a source of high-energy neutrinos: a flaring active galaxy, or blazar, 4 billion light years from Earth. Following a detection by the IceCube Neutrino Observatory on 22 September 2017, ESA’s INTEGRAL satellite joined a collaboration of observatories in space and on the ground that kept an eye on the neutrino source, heralding the thrilling future of multi-messenger astronomy.

    ESA/Integral

    Neutrinos are nearly massless, ‘ghostly’ particles that travel essentially unhindered through space at close to the speed of light [1]. Despite being some of the most abundant particles in the Universe – 100 000 billion pass through our bodies every second – these electrically neutral, subatomic particles are notoriously difficult to detect because they interact with matter incredibly rarely.

    While primordial neutrinos were created during the Big Bang, more of these elusive particles are routinely produced in nuclear reactions across the cosmos. The majority of neutrinos arriving at Earth derive from the Sun, but those that reach us with the highest energies are thought to stem from the same sources as cosmic rays – highly energetic particles originating from exotic sources outside the Solar System.

    Unlike neutrinos, cosmic rays are charged particles and so their path is bent by magnetic fields, even weak ones. The neutral charge of neutrinos instead means they are unaffected by magnetic fields, and because they pass almost entirely through matter they can be used to trace a straight path all the way back to their source.

    Acting as ‘messengers’, neutrinos directly carry astronomical information from the far reaches of the Universe. Over the past decades, several instruments have been built on Earth and in space to decode their messages, though detecting these particles is no easy feat. In particular, the source of high-energy neutrinos has, until now, remained unproven.

    On 22 September 2017, one of these high-energy neutrinos arrived at the IceCube Neutrino Observatory at the South Pole [2]. The event was named IceCube-170922A.

    The IceCube observatory, which encompasses a cubic kilometre of deep, pristine ice, detects neutrinos through their secondary particles, muons. These muons are produced on the rare occasion that a neutrino interacts with matter in the vicinity of the detector, and they create tracks, kilometres in length, as they pass through layers of Antarctic ice. Their long paths mean their position can be well defined, and the source of the parent neutrino can be pinned down in the sky.

    During the 22 September event, a traversing muon deposited 22 TeV of energy in the IceCube detector. From this, scientists estimated the energy of the parent neutrino to be around 290 TeV, indicating a 50 percent chance that it had an astrophysical origin beyond the Solar System.

    When the origin of a neutrino cannot be robustly identified by IceCube, like in this case, multi-wavelength observations are required to investigate its source. So, following the detection, IceCube scientists circulated the coordinates in the sky of the neutrino’s origin, inferred from their observations, to a worldwide network of ground and space-based observatories working across the full electromagnetic spectrum.

    These included NASA’s Fermi gamma-ray space telescope [above] and the Major Atmospheric Gamma-Ray Imaging Cherenkov (MAGIC) [above] on La Palma, in the Canary Islands, which looked to this portion of the sky and found the known blazar, TXS 0506+056, in a ‘flaring’ state – a period of intense high-energy emission – at the same time the neutrino was detected at the South Pole.

    Blazars are the central cores of giant galaxies that host an actively accreting supermassive black-hole at their heart, where matter spiralling in forms a hot, rotating disc that generates enormous amounts of energy, along with a pair of relativistic jets.

    These jets are colossal columns that funnel radiation, photons and particles – including neutrinos and cosmic rays – tens of light years away from the central black hole at speeds very close to the speed of light. A specific feature of blazars is that one of these jets happens to point towards Earth, making its emission appear exceptionally bright.

    Scientists around the world began observing this blazar – the likely source of the neutrino detected by IceCube – in a variety of wavelengths, from radio waves to high-energy gamma rays. ESA’s INTEGRAL gamma-ray observatory was part of this international collaboration [3].

    “This is a very important milestone to understanding how high-energy neutrinos are produced,” says Carlo Ferrigno from the INTEGRAL Science Data Centre at the University of Geneva, Switzerland.

    “There have been previous claims that blazar flares were associated with the production of neutrinos, but this, the first confirmation, is absolutely fundamental. This is an exciting period for astrophysics,” he adds.

    INTEGRAL, which surveys the sky in hard X-rays and soft gamma rays, is also sensitive to transient high-energy sources across the whole sky. At the time the neutrino was detected, it did not record any burst of gamma rays from the location of the blazar, so scientists were able to rule out prompt emissions from certain sources, such as a gamma-ray burst.

    After the neutrino alert from IceCube, INTEGRAL pointed to this area of the sky on various occasions between 30 September and 24 October 2017 with its wide-field instruments, and it did not observe the blazar to be in a flaring state in the hard X-ray or soft gamma-ray range.

    The fact that INTEGRAL could not detect the source in the follow-up observations provided significant information about this blazar, allowing scientists to place a useful upper limit on its energy output during this period.

    “INTEGRAL was important in constraining the properties of this blazar, but also in allowing scientists to exclude other neutrino sources such as gamma-ray bursts,” explains Volodymyr Savchenko from the INTEGRAL Science Data Centre, who led the analysis of the INTEGRAL data.

    With facilities spread across the globe and in space, scientists now have the capability to detect a plethora of ‘cosmic messengers’ travelling vast distances at extremely high speeds, in the form of light, neutrinos, cosmic rays, and even gravitational waves.

    “The ability to globally marshal telescopes to make a discovery using a variety of wavelengths in cooperation with a neutrino detector like IceCube marks a milestone in what scientists call multi-messenger astronomy,” says Francis Halzen from the University of Wisconsin–Madison, USA, lead scientist for the IceCube Neutrino Observatory.

    By combining the information gathered by each of these sophisticated instruments to investigate a wide range of cosmic processes, the era of multi-messenger astronomy has truly entered the phase of scientific exploitation.

    ESA’s high-energy space telescopes are fully integrated into this network of large multi-messenger collaborations, as demonstrated during the recent detection of gravitational waves with a corresponding gamma-ray burst – the latter detected by INTEGRAL – released by the collision of two neutron stars, and in the subsequent follow-up campaign, with contributions by INTEGRAL as well as the XMM-Newton X-ray observatory.

    ESA/XMM Newton

    Pooling resources from these and other observatories is key for the future of astrophysics, fostering our ability to decode the messages that reach us from across the Universe.

    “INTEGRAL is the only observatory available in the hard X-ray and soft gamma-ray domain that has the ability to perform dedicated imaging and spectroscopy, as well as having an instantaneous all-sky view at any time,” notes Erik Kuulkers, INTEGRAL project scientist at ESA.

    “After more than 15 years of operations, INTEGRAL is still at the forefront of high-energy astrophysics.”
    Notes

    [1] Described by Frederick Reines, one of the scientists who made the first neutrino detection, as “… the most tiny quantity of reality ever imagined by a human being,” one neutrino is estimated to contain one millionth of the mass of an electron.

    [2] The IceCube Collaboration is funded primarily by the National Science Foundation and is operated by a team headquartered at the University of Wisconsin–Madison, USA. The research efforts, including critical contributions to the detector operation, are supported by funding agencies in Australia, Belgium, Canada, Denmark, Germany, Japan, New Zealand, Republic of Korea, Sweden, Switzerland, the United Kingdom, and the USA.

    [3] These results are detailed in the paper Multimessenger observations of a flaring blazar coincident with high-energy neutrino IceCube-170922A by The IceCube, Fermi-LAT, MAGIC, AGILE, ASAS-SN, HAWC, H.E.S.S, INTEGRAL, Kanata, Kiso, Kapteyn, Liverpool telescope, Subaru, Swift/NuSTAR, VERITAS, and VLA/17B-403 teams, published in Science. DOI:10.1126/science.aat1378

     
  • richardmitnick 11:53 am on July 12, 2018 Permalink | Reply
    Tags: A cosmic particle spewed from a distant galaxy strikes Earth, , , , , , , , , Supermassive Black Holes, ,   

    From Astronomy Magazine: “A cosmic particle spewed from a distant galaxy strikes Earth” 

    Astronomy magazine

    From Astronomy Magazine

    July 12, 2018
    Michelle Hampson

    The rare detection of a high-energy neutrino hints at how these strange particles are created.

    U Wisconsin ICECUBE neutrino detector at the South Pole



    IceCube Gen-2 DeepCore PINGU annotated

    Four billion years ago, an immense galaxy with a black hole at its heart spewed forth a jet of particles at nearly the speed of light. One of those particles, a neutrino that is just a fraction of the size of a regular atom, traversed across the universe on a collision course for Earth, finally striking the ice sheet of Antarctica last September. Coincidentally, a neutrino detector planted by scientists within the ice recorded the neutrino’s charged interaction with the ice, which resulted in a blue flash of light lasting just a moment. The results are published today in the journal Science.

    This detection marks the second time in history that scientists have pinpointed the origins of a neutrino from outside of our solar system. And it’s the first time they’ve confirmed that neutrinos are created in the supermassive black holes at the centers of galaxies — a somewhat unexpected source.

    Neutrinos are highly energetic particles that rarely ever interact with matter, passing through it as though it weren’t even there. Determining the type of cosmological events that create these particles is critical for understanding the nature of the universe. But the only confirmed source of neutrinos, other than our Sun, is a supernova that was recorded in 1987.

    2
    The most recent Hubble image of SN 1987A, taken in January 2017, captures the glow of hydrogen gas around the supernova remnant.
    NASA, ESA, and R. Kirshner (Harvard-Smithsonian Center for Astrophysics and Gordon and Betty Moore Foundation) and P. Challis (Harvard-Smithsonian Center for Astrophysics)

    Physicists have a number of theories about what sort of astronomical events may create neutrinos, with some suggesting that blazars could be a source. Blazars are massive galaxies with black holes at their center, trying to suck in too much matter at once, causing jets of particles to be ejected outward at incredible speeds. Acting like the giant counterparts to terrestrial particle accelerators, blazar jets are believed to produce cosmic rays that can in turn create neutrinos.

    “This [detection] in particular is a chance of nature,” says Darren Grant, a lead scientist of the team that first discovered the high-energy neutrino, as part of the neutrino detection project IceCube. “There’s a blazar there that just happened to turn on at the right time and we happened to capture it. It’s one of those eureka moments. You hope to experience those a few times in your career and this was one of them, where everything aligned.”

    A cosmic messenger

    On September 22, 2017, the neutrino reached the Antarctica ice sheet, passing by an ice crystal at just the right angle to cause a subatomic particle (called a muon) to be created from the interaction. The resulting blue flash was recorded by one of IceCube’s 5,160 detectors, embedded within the ice. Grant was in the office when the detection occurred. This neutrino was about 300 million times more energetic than those that are emitted by the Sun.

    Grant and his colleague briefly admired the excellent image depicting the trajectory of the muon, which provides basic information necessary to begin tracing back the neutrino’s origin. However, they weren’t overly excited quite yet. His team observes about 10 to 20 high-energy neutrinos each year, but the right combination of events — in space, time and energy, for example — is required to precisely pinpoint the source of the neutrino. Such an alignment had eluded scientists so far. As Grant’s team began their analysis, though, they began to narrow in on a region: an exceptionally bright blazar called TXS 0506+056.

    3
    IceCube employs more than 5,000 detectors lowered on 86 strings into almost 100 holes in the Antarctic ice.
    NSF / B. Gudbjartsson, IceCube Collaboration

    Upon the detection, an automatic alert was sent to other astronomy teams around the world, which monitor various incoming cosmic signals, such as radio and gamma rays. A few days later a team of scientists using the MAGIC telescope in the Canary Islands responded with some exciting news: the arrival of the neutrino had coincided with a burst of gamma rays – which are extremely energetic photons – also coming from the direction of TXS 0506+056.

    MAGIC Cherenkov gamma ray telescope on the Canary island of La Palma, Spain, Altitude 2,200 m (7,200 ft)

    Other teams analyzing the region following the initial detection observed changes in X-ray emissions and radio signals too. Collectively, the data is a huge step forward for physicists in understanding blazars, and high-energy cosmological events in general.

    John Learned of University of Hawaii, Manoa, who was not involved in the study, says that the data linking the blazar as the source is “overwhelmingly convincing” and he emphasizes the importance of this finding. “This is the realization of many long-standing scientific dreams. Neutrinos at high energies can tell us about the guts of these extremely luminous objects … The implications of the finding are that we are now finally … [able] to see inside the most dense and luminous objects, and to further our grasp of the ‘deus ex machina’ which drives them and powers these awesome phenomena.”

    For example, this detection also provides the first evidence that a blazar can produce the high-energy protons needed to generate neutrinos such as the one IceCube saw.

    4
    Blazars are active supermassive black holes sucking in immense amounts of material, which form swirling accretion disks and generate high-powered particle jets that churn out particles that astronomers have believed eventually result in neutrinos. DESY, Science Communication Lab

    Sources of high-energy protons also remain largely a mystery, so the identification of one such source is another big step forward for astronomers. “It’s really quite convincing that we’ve unlocked one piece of that puzzle,” says Grant.

    Gems from the past

    And it gets even better. “We looked back at [archival] data [that had been collected since 2010], in the direction of this particular blazar source, and what we discovered was really quite remarkable,” Grant says. A barrage of high-energy neutrinos and gamma rays from TXS 0506+056 reached Earth in late 2014 and early 2015. At the time, IceCube’s real-time alert system was not fully functioning, so other scientific teams were not aware of the detection. But now these previous neutrinos are on scientists’ radar, providing a more long-term glimpse into the life of a blazar.

    “That was really icing on the cake, because what [the archived data indicated] was that the source had been active in neutrinos in the past, and then again, with this very high-energy neutrino in September — those are the pieces that really start to come together, to make a picture of what’s happening there,” explains Grant.

    6
    The alert IceCube sent once the neutrino’s interaction with the ice was detected resulted in follow-up observations from about 20 Earth- and space-based observatories. This immense effort resulted in the clear identification of a distant blazar as the source of the neutrino — as well as gamma rays, X-rays, radio emission, and optical light.
    Nicolle R. Fuller/NSF/IceCube

    The data also reveal that radio emissions from TXS 0506+056 gradually increased in the 18 months leading up to the September neutrino detection. Greg Sivakoff, an associate professor at the University of Alberta who helped analyze the data, says one possibility is that the black hole began to consume surrounding matter much faster during this time, causing the jet of particles being emitted to speed up. He says, “If the jet gets too fast too quickly, it might run into some of its own material, creating what astronomers call a shock. Shocks have long been used in astronomy to explain how particles are accelerated to high energies. We are not sure that this is the answer yet, but this may be part of the story.”

    Scientists are continuing to monitor TXS 0506+056, hoping to learn more about this colossal event. One team conducted a detailed analysis to determine how far away the blazar is from us, astounded to discover that it is a whopping four billion light years away. While TXS 0506+056 was always considered a bright object in the sky, this luminosity at such a distance makes it one of the brightest objects in the universe. No doubt future studies of this powerful blazar will yield valuable insights into the most energetic events to occur in our universe.

    Learned says, “We are just opening a new door and I would love to be able to say what we shall find beyond. But I guarantee that initiating this new means of observing the universe will bring surprises and new insights. In an extreme analogy it is like asking Galileo what his new astronomical telescope will reveal.”

    See the full article here .
    See also From CfA: VERITAS Supplies Critical Piece to Neutrino Discovery Puzzle


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  • richardmitnick 11:19 am on May 28, 2018 Permalink | Reply
    Tags: , , , , , , , Supermassive Black Holes   

    From Ethan Siegel: “This Is Why The Event Horizon Telescope Still Doesn’t Have An Image Of A Black Hole” 

    From Ethan Siegel
    May 28, 2018

    1
    The black hole at the center of our Milky Way, simulated here, is the largest one seen from Earth’s perspective. The Event Horizon Telescope should, this year, come out with their first image of what this central black hole’s event horizon looks like. The white circle represents the Schwarzschild radius of the black hole. Ute Kraus, Physics education group Kraus, Universität Hildesheim; background: Axel Mellinger

    Across multiple continents, including Antarctica, an array of radio telescopes observe the galactic center.

    EHT APEX, IRAM, G. Narayanan, J. McMahon, JCMT/JAC, S. Hostler, D. Harvey, ESO/C. Malin


    A view of the different telescopes contributing to the Event Horizon Telescope’s imaging capabilities from one of Earth’s hemispheres. The data taken from 2011 to 2017 should enable us to now construct an image of Sagittarius A*.

    This network, the Event Horizon Telescope (EHT), is imaging, for the first time, a black hole’s event horizon.

    SGR A* , the supermassive black hole at the center of the Milky Way. NASA’s Chandra X-Ray Observatory


    SgrA* NASA/Chandra


    Sgr A* from ESO VLT

    2
    The most-visualized black hole of all, as illustrated in the movie Interstellar, shows a predicted event horizon fairly accurately for a very specific class of rotating black holes. Interstellar / R. Hurt / Caltech

    Of all the black holes visible from Earth, the largest is at the galactic center: 37 μas [Microarc-second].

    4
    This multiwavelength view of the Milky Way’s galactic center goes from the X-ray through the optical and into the infrared, showcasing Sagittarius A* and the intragalactic medium located some 25,000 light years away. Using radio data, the EHT will resolve the event horizon of the central black hole. X-ray: NASA/CXC/UMass/D. Wang et al.; Optical: NASA/ESA/STScI/D.Wang et al.; IR: NASA/JPL-Caltech/SSC/S.Stolov

    NASA/Chandra X-ray Telescope

    NASA/ESA Hubble Telescope

    With a theoretical resolution of 15 μas, the EHT should resolve it.

    Despite the incredible news that they’ve detected the black hole’s structure at the galactic center, however, there’s still no direct image.

    5
    A plot of the coverage in space of the area around the galactic center’s black hole from the telescopes whose data has been brought together so far. Additional telescopes will further constrain the black hole’s size, shape and orientation. R.-S. Lu et al, ApJ 859, 1

    They found evidence for an asymmetric source, about 3 Schwarzschild radii large: consistent with Einstein’s prediction of 2.5.

    66
    Two of the possible models that can successfully fit the Event Horizon Telescope data thus far. Both show an off-center, asymmetric event horizon that’s enlarged versus the Schwarzschild radius, consistent with the predictions of Einstein’s General Relativity. R.-S. Lu et al, ApJ 859, 1

    But before the South Pole data, delivered five months ago, can be added, all error sources must be identified.

    South Pole Telescope SPTPOL. The SPT collaboration is made up of over a dozen (mostly North American) institutions, including the University of Chicago, the University of California, Berkeley, Case Western Reserve University, Harvard/Smithsonian Astrophysical Observatory, the University of Colorado Boulder, McGill University, The University of Illinois at Urbana-Champaign, University of California, Davis, Ludwig Maximilian University of Munich, Argonne National Laboratory, and the National Institute for Standards and Technology. It is funded by the National Science Foundation.


    The South Pole Telescope, a 10 meter radio telescope located at the South Pole, will be the most important addition to the EHT as far as resolving the central black hole goes.

    Earth’s atmospheric turbulence, instrumentation noise, and spurious signals require identification, obtainable through additional imaging.

    8
    A map of the 7 million second exposure of the Chandra Deep Field-South. This region shows hundreds of supermassive black holes, each one in a galaxy far beyond our own. There should be hundreds of thousands of times as many stellar-mass black holes; we’re just waiting for the capability of detecting them. NASA/CXC/B. Luo et al., 2017, ApJS, 228, 2

    Although the data has been combined, novel algorithms must be developed to process them into an image.

    9
    Five different simulations in general relativity, using a magnetohydrodynamic model of the black hole’s accretion disk, and how the radio signal will look as a result. Note the clear signature of the event horizon in all the expected results. GRMHD simulations of visibility amplitude variability for Event Horizon Telescope images of Sgr A*, L. Medeiros et al., arXiv:1601.06799

    Only two black holes, Sagittarius A* and Messier 87, could have event horizon “silhouettes” imaged.

    10
    The second-largest black hole as seen from Earth, the one at the center of the galaxy Messier 87, is shown in three views here. Despite its mass of 6.6 billion Suns, it is over 2000 times farther away than Sagittarius A*. It may not be resolvable by the EHT.Top, optical, Hubble Space Telescope / NASA / Wikisky; lower left, radio, NRAO / Very Large Array (VLA); lower right, X-ray, NASA / Chandra X-ray 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)

    New data will be taken annually, improving the future, overall pictures through subsequent analysis.

    Event Horizon Telescope Array

    Arizona Radio Observatory
    Arizona Radio Observatory/Submillimeter-wave Astronomy (ARO/SMT)

    ESO/APEX
    Atacama Pathfinder EXperiment

    CARMA Array no longer in service
    Combined Array for Research in Millimeter-wave Astronomy (CARMA)

    Atacama Submillimeter Telescope Experiment (ASTE)
    Atacama Submillimeter Telescope Experiment (ASTE)

    Caltech Submillimeter Observatory
    Caltech Submillimeter Observatory (CSO)

    IRAM NOEMA interferometer
    Institut de Radioastronomie Millimetrique (IRAM) 30m

    James Clerk Maxwell Telescope interior, Mauna Kea, Hawaii, USA
    James Clerk Maxwell Telescope interior, Mauna Kea, Hawaii, USA

    Large Millimeter Telescope Alfonso Serrano
    Large Millimeter Telescope Alfonso Serrano

    CfA Submillimeter Array Hawaii SAO
    Submillimeter Array Hawaii SAO

    ESO/NRAO/NAOJ ALMA Array
    ESO/NRAO/NAOJ ALMA Array, Chile

    South Pole Telescope SPTPOL
    South Pole Telescope SPTPOL

    NSF CfA Greenland telescope

    Greenland Telescope

    Future Array/Telescopes

    Plateau de Bure interferometer
    Plateau de Bure interferometer

    Over the coming months, preliminary images will show the:

    size,
    shape,
    changes,
    and surrounding environment,

    of our first directly-observed black holes.

    11
    High-Angular-Resolution and High-Sensitivity Science Enabled by Beamformed ALMA, V. Fish et al., arXiv:1309.3519

    Some of the possible profile signals of the black hole’s event horizon as simulations of the Event Horizon Telescope indicate.

    See the full article here .


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    Please help promote STEM in your local schools.
    stem
    Stem Education Coalition

    “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 11:37 am on April 6, 2018 Permalink | Reply
    Tags: A telescope bigger than our planet reveals minute details in a nearby galaxy's center, Astronomers zoom in on a supermassive black hole's jets, , , , , , , Perseus Cluster of galaxies, Supermassive Black Holes   

    From Astronomy Magazine: “Astronomers zoom in on a supermassive black hole’s jets” 

    Astronomy magazine

    Astronomy Magazine

    April 03, 2018
    Alison Klesman

    A telescope bigger than our planet reveals minute details in a nearby galaxy’s center.

    1
    This image shows how radio telescopes on Earth and in space (left) combined to observe a very small region around another galaxy’s supermassive black hole (right). In this radio image, the black hole is located in the bright yellow-green spot at the top; a young jet about 3 light-years long shoots away from the black hole.
    Pier Raffaele Platania INAF/IRA (compilation); ASC Lebedev Institute (RadioAstron image).

    Supermassive black holes millions to billions of times the mass of our Sun lurk in the centers of most galaxies. In addition to feeding on nearby gas and dust, some of these black holes launch massive jets of plasma that not only dwarf the black hole itself, but the entire galaxy in which they reside. The mechanics of these jets, including exactly where they are launched, are still poorly understood, but observations such as those recently achieved using a combination of Earth- and space-based radio telescopes will help unlock the mysteries surrounding these dramatic structures.

    In a paper published April 2 in Nature Astronomy, an international collaboration of astronomers released observations of the jets around the black hole in the galaxy NGC 1275, located in the Perseus Cluster of galaxies about 230 million light-years away.

    Perseus galaxy cluster by NASA/Chandra

    Also known as Perseus A or 3C 84, this galaxy is classified as a Seyfert galaxy, meaning it has an “active” black hole currently feeding on surrounding material. That black hole is in the early stages of generating massive jets, which have now been mapped out via radio observations down to a mere 12 light-days from their origin around the black hole. That’s just a few hundred times the radius of the black hole itself (1 light-day is about 16 billion miles [26 billion kilometers]).

    What they found surprised them. “It turned out that the observed width of the jet was significantly wider than what was expected in the currently favored models where the jet is launched from the black hole’s ergosphere — an area of space right next to a spinning black hole where space itself is dragged to a circling motion around the hole,” said the paper’s lead author, Gabriele Giovannini from the Italian National Institute for Astrophysics, in a press release.

    Instead, “this may imply that at least the outer part of the jet is launched from the [much larger] accretion disk surrounding the black hole,” said said Tuomas Savolainen of Aalto University in Finland, and leader of the RadioAstron observing program that created the images.

    These images took advantage of a technique called very long baseline interferometry, or VLBI. This technique links several radio telescopes together to essentially observe with a “virtual” dish as large as the distance between the telescopes. In this case, the team linked Earth-based radio telescopes with a Russian 10-meter (33 feet) radio telescope orbiting Earth as part of the RadioAstron project, creating a virtual radio telescope with a diameter of over 200,000 miles (350,000 km), nearly the distance between Earth and the Moon.

    RadioAstron Spektr R satellite, the Astro Space Center of Lebedev Physical Institute in Moscow, Russia

    The larger the radio telescope, the finer the detail it can see, which allowed astronomers to zoom in on the region around NGC 1275’s black hole to look for clues about how and where the jet is generated. Their resulting images are 10 times better than anything previously achieved using ground-based radio telescopes alone. This same technique is the one utilized by the Event Horizon Telescope last year in an attempt to image the shadow of a supermassive black hole on its accretion disk; astronomers are eagerly awaiting the results, which should be announced later this year.

    Event Horizon Telescope Array

    Arizona Radio Observatory
    Arizona Radio Observatory/Submillimeter-wave Astronomy (ARO/SMT)

    ESO/APEX
    Atacama Pathfinder EXperiment

    CARMA Array no longer in service
    Combined Array for Research in Millimeter-wave Astronomy (CARMA)

    Atacama Submillimeter Telescope Experiment (ASTE)
    Atacama Submillimeter Telescope Experiment (ASTE)

    Caltech Submillimeter Observatory
    Caltech Submillimeter Observatory (CSO)

    IRAM NOEMA interferometer
    Institut de Radioastronomie Millimetrique (IRAM) 30m

    James Clerk Maxwell Telescope interior, Mauna Kea, Hawaii, USA
    James Clerk Maxwell Telescope interior, Mauna Kea, Hawaii, USA

    Large Millimeter Telescope Alfonso Serrano
    Large Millimeter Telescope Alfonso Serrano

    CfA Submillimeter Array Hawaii SAO
    Submillimeter Array Hawaii SAO

    ESO/NRAO/NAOJ ALMA Array
    ESO/NRAO/NAOJ ALMA Array, Chile

    South Pole Telescope SPTPOL
    South Pole Telescope SPTPOL

    Future Array/Telescopes

    Plateau de Bure interferometer
    Plateau de Bure interferometer

    NSF CfA Greenland telescope

    But while these observations don’t mesh exactly with expectations, “Our result does not yet falsify the current models where the jets are launched from the ergosphere, but it hopefully gives the theorists insight about the jet structure close to the launching site and clues how to develop the models,” said Savolainen.

    5
    The galaxy NGC 1275 contains the black hole around which jets were imaged in this study. This composite image shows detail from optical, radio, and X-ray observations. The purple X-ray lobes near the brightest part of the galaxy contain the young radio jets from the black hole.
    NASA, ESA, NRAO and L. Frattare (STScI). Science Credit: X-ray: NASA/CXC/IoA/A.Fabian et al.; Radio: NRAO/VLA/G. Taylor; Optical: NASA, ESA, the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration, and A. Fabian (Institute of Astronomy, University of Cambridge, UK)

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

    NASA/Chandra 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)

    NASA/ESA Hubble Telescope

    This is only the second observation of jets at such close proximity to the black hole; the only other system that has been observed with this level of detail is M87. But the jets in M87 are much older, which, researchers say, may be why they look different from those in NGC 1275. “The jet in NGC 1275 was re-started just over a decade ago and is currently still forming, which provides a unique opportunity to follow the very early growth of a black hole jet,” said Masanori Nakamura from Academia Sinica in Taiwan, a co-author on the paper. “Continuing these observations will be very important.”

    See the full article here .

    Please help promote STEM in your local schools.

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