Tag Archives: galaxies

The elliptical galaxy NGC 1600, 200 million light-years away — shown in the centre of the image and highlighted in the box —, hosts in its centre one of the biggest supermassive black holes known . Until the discovery of this example, astronomers assumed that such huge black holes could only be found in the centres of massive galaxies at the centre of galaxy clusters. NGC 1600, however, is a rather isolated galaxy.

The image is a composition of a ground based view and observations made with the NASA/ESA Hubble Space Telescope.

Credit:
NASA, ESA, Digital Sky Survey 2

NGC 1600′s super massive blackhole discovery puzzles astronomers

Astronomers have uncovered one of the biggest supermassive black holes, with the mass of 17 billion Suns, in an unlikely place: the centre of a galaxy that lies in a quiet backwater of the Universe. The observations, made with the NASA/ESA Hubble Space Telescope and the Gemini Telescope in Hawaii, indicate that these monster objects may be more common than once thought. The results of this study are released in the journal Nature.

The elliptical galaxy NGC 1600, 200 million light-years away — shown in the centre of the image and highlighted in the box —, hosts in its centre one of the biggest supermassive black holes known . Until the discovery of this example, astronomers assumed that such huge black holes could only be found in the centres of massive galaxies at the centre of galaxy clusters. NGC 1600, however, is a rather isolated galaxy. The image is a composition of a ground based view and observations made with the NASA/ESA Hubble Space Telescope. Credit: NASA, ESA, Digital Sky Survey 2
The elliptical galaxy NGC 1600, 200 million light-years away — shown in the centre of the image and highlighted in the box —, hosts in its centre one of the biggest supermassive black holes known . Until the discovery of this example, astronomers assumed that such huge black holes could only be found in the centres of massive galaxies at the centre of galaxy clusters. NGC 1600, however, is a rather isolated galaxy.
The image is a composition of a ground based view and observations made with the NASA/ESA Hubble Space Telescope.
Credit:
NASA, ESA, Digital Sky Survey 2

Until now, the biggest supermassive black holes — those having more than 10 billion times the mass of our Sun — have only been found at the cores of very large galaxies in the centres of massive galaxy clusters. Now, an international team of astronomers using the NASA/ESA Hubble Space Telescope has discovered a supersized black hole with a mass of 17 billion Suns in the centre of the rather isolated galaxy NGC 1600.

NGC 1600 is an elliptical galaxy which is located not in a cluster of galaxies, but in a small group of about twenty. The group is located 200 million light-years away in the constellation Eridanus. While finding a gigantic supermassive black hole in a massive galaxy within a cluster of galaxies is to be expected, finding one in an average-sized galaxy group like the one surrounding NGC 1600 is much more surprising.

“Even though we already had hints that the galaxy might host an extreme object in the centre, we were surprised that the black hole in NGC 1600 is ten times more massive than predicted by the mass of the galaxy,” explains lead author of the study Jens Thomas from the Max Planck-Institute for Extraterrestrial Physics, Germany.

Based on previous Hubble surveys of supermassive black holes, astronomers had discovered a correlation between a black hole’s mass and the mass of its host galaxy’s central bulge of stars: the larger the galaxy bulge, the more massive the black hole is expected to be. “It appears from our finding that this relation does not work so well with extremely massive black holes,” says Thomas. “These monster black holes account for a much larger fraction of the host galaxy’s mass than the previous correlations would suggest.”

Finding this extremely massive black hole in NGC 1600 leads astronomers to ask whether these objects are more common than previously thought. “There are quite a few galaxies the size of NGC 1600 that reside in average-size galaxy groups,” explains co-author Chung-Pei Ma, an astronomer from the University of California, Berkeley, USA, and head of the MASSIVE Survey [1]. “We estimate that these smaller groups are about fifty times more abundant than large, dense galaxy clusters. So the question now is: is this the tip of an iceberg? Maybe there are a lot more monster black holes out there.”

It is assumed that this black hole grew by merging with another supermassive black hole from another galaxy. It may then have continued to grow by gobbling up gas funneled to the core of the galaxy by further galaxy collisions. Thus may also explain why NGC 1600 resides in a sparsely populated region of the Universe and why it is at least three times brighter than its neighbours.

As the supermassive black hole is currently dormant, astronomers were only able to find it and estimate its mass by measuring the velocities of stars close to it, using the Gemini North 8-metre telescope on Mauna Kea, Hawaii. Using these data the team discovered that stars lying about 3000 light-years from the core are moving as if there had been many more stars in the core in the distant past. This indicates that most of the stars in this region have been kicked out from the centre of the galaxy.

Archival Hubble images, taken with the Near Infrared Camera and Multi-Object Spectrometer (NICMOS), support the idea that the two merging supermassive black holes in the distant past gave stars the boot. The NICMOS images revealed that the galaxy’s core is unusually faint, indicating a lack of stars close to the galactic centre. “We estimate that the mass of stars tossed out of the central region of NGC 1600 is equal to 40 billion Suns,” concludes Thomas. “This is comparable to ejecting the entire disc of our Milky Way galaxy.”

Notes
[1] The MASSIVE Survey, which began in 2014, measures the mass of stars, dark matter, and the central black hole of the 100 most massive, nearby galaxies, those larger than 300 billion solar masses and within 350 million light-years of Earth. Among its goals are to find the descendants of luminous quasars that may be sleeping unsuspected in large nearby galaxies and to understand how galaxies form and grow supermassive black holes.

More information
The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

The study “A 17-billion-solar-mass black hole in a group galaxy with a diffuse core” appeared in the journal Nature.

The international team of astronomers in this study consists of J. Thomas (Max Planck Institute for Extraterrestrial Physics, Germany), C.-P. Ma (University of California, Berkeley, USA), N. McConnell (Dominion Astrophysical Observatory, Canada), J. Greene (Princeton University, USA), J. Blakeslee (Dominion Astrophysical Observatory, Canada), and R. Janish (University of California, Berkeley, USA)

Source: Space Telescope

Star formation in what are now "dead" galaxies sputtered out billions of years ago. ESO’s Very Large Telescope and the NASA/ESA Hubble Space Telescope have revealed that three billion years after the Big Bang, these galaxies still made stars on their outskirts, but no longer in their interiors. The quenching of star formation seems to have started in the cores of the galaxies and then spread to the outer parts.

This diagram illustrates this process. Galaxies in the early Universe appear at the left. The blue regions are where star formation is in progress and the red regions are the "dead" regions where only older redder stars remain and there are no more young blue stars being formed. The resulting giant spheroidal galaxies in the modern Universe appear on the right.

Credit:
ESO

Giant Galaxies Die from the Inside Out

VLT and Hubble observations show that star formation shuts down in the centres of elliptical galaxies first


Astronomers have shown for the first time how star formation in “dead” galaxies sputtered out billions of years ago. ESO’s Very Large Telescope and the NASA/ESA Hubble Space Telescope have revealed that three billion years after the Big Bang, these galaxies still made stars on their outskirts, but no longer in their interiors. The quenching of star formation seems to have started in the cores of the galaxies and then spread to the outer parts. The results will be published in the 17 April 2015 issue of the journal Science.

Star formation in what are now "dead" galaxies sputtered out billions of years ago. ESO’s Very Large Telescope and the NASA/ESA Hubble Space Telescope have revealed that three billion years after the Big Bang, these galaxies still made stars on their outskirts, but no longer in their interiors. The quenching of star formation seems to have started in the cores of the galaxies and then spread to the outer parts. This diagram illustrates this process. Galaxies in the early Universe appear at the left. The blue regions are where star formation is in progress and the red regions are the "dead" regions where only older redder stars remain and there are no more young blue stars being formed. The resulting giant spheroidal galaxies in the modern Universe appear on the right. Credit: ESO
Star formation in what are now “dead” galaxies sputtered out billions of years ago. ESO’s Very Large Telescope and the NASA/ESA Hubble Space Telescope have revealed that three billion years after the Big Bang, these galaxies still made stars on their outskirts, but no longer in their interiors. The quenching of star formation seems to have started in the cores of the galaxies and then spread to the outer parts.
This diagram illustrates this process. Galaxies in the early Universe appear at the left. The blue regions are where star formation is in progress and the red regions are the “dead” regions where only older redder stars remain and there are no more young blue stars being formed. The resulting giant spheroidal galaxies in the modern Universe appear on the right.
Credit:
ESO

A major astrophysical mystery has centred on how massive, quiescent elliptical galaxies, common in the modern Universe, quenched their once furious rates of star formation. Such colossal galaxies, often also called spheroids because of their shape, typically pack in stars ten times as densely in the central regions as in our home galaxy, the Milky Way, and have about ten times its mass.

Astronomers refer to these big galaxies as red and dead as they exhibit an ample abundance of ancient red stars, but lack young blue stars and show no evidence of new star formation. The estimated ages of the red stars suggest that their host galaxies ceased to make new stars about ten billion years ago. This shutdown began right at the peak of star formation in the Universe, when many galaxies were still giving birth to stars at a pace about twenty times faster than nowadays.

“Massive dead spheroids contain about half of all the stars that the Universe has produced during its entire life,” said Sandro Tacchella of ETH Zurich in Switzerland, lead author of the article. “We cannot claim to understand how the Universe evolved and became as we see it today unless we understand how these galaxies come to be.”

Tacchella and colleagues observed a total of 22 galaxies, spanning a range of masses, from an era about three billion years after the Big Bang [1]. The SINFONI instrument on ESO’s Very Large Telescope (VLT) collected light from this sample of galaxies, showing precisely where they were churning out new stars. SINFONI could make these detailed measurements of distant galaxies thanks to its adaptive optics system, which largely cancels out the blurring effects of Earth’s atmosphere.

The researchers also trained the NASA/ESA Hubble Space Telescope on the same set of galaxies, taking advantage of the telescope’s location in space above our planet’s distorting atmosphere. Hubble’s WFC3 camera snapped images in the near-infrared, revealing the spatial distribution of older stars within the actively star-forming galaxies.

“What is amazing is that SINFONI’s adaptive optics system can largely beat down atmospheric effects and gather information on where the new stars are being born, and do so with precisely the same accuracy as Hubble allows for the stellar mass distributions,” commented Marcella Carollo, also of ETH Zurich and co-author of the study.

According to the new data, the most massive galaxies in the sample kept up a steady production of new stars in their peripheries. In their bulging, densely packed centres, however, star formation had already stopped.

“The newly demonstrated inside-out nature of star formation shutdown in massive galaxies should shed light on the underlying mechanisms involved, which astronomers have long debated,” says Alvio Renzini, Padova Observatory, of the Italian National Institute of Astrophysics.

A leading theory is that star-making materials are scattered by torrents of energy released by a galaxy’s central supermassive black hole as it sloppily devours matter. Another idea is that fresh gas stops flowing into a galaxy, starving it of fuel for new stars and transforming it into a red and dead spheroid.

“There are many different theoretical suggestions for the physical mechanisms that led to the death of the massive spheroids,” said co-author Natascha Förster Schreiber, at the Max-Planck-Institut für extraterrestrische Physik in Garching, Germany. “Discovering that the quenching of star formation started from the centres and marched its way outwards is a very important step towards understanding how the Universe came to look like it does now.”

Notes
[1] The Universe’s age is about 13.8 billion years, so the galaxies studied by Tacchella and colleagues are generally seen as they were more than 10 billion years ago.

Source: ESO


This artist's impression shows schematically the mysterious alignments between the spin axes of quasars and the large-scale structures that they inhabit that observations with ESO’s Very Large Telescope have revealed. These alignments are over billions of light-years and are the largest known in the Universe.

The large-scale structure is shown in blue and quasars are marked in white with the rotation axes of their black holes indicated with a line.

This picture is for illustration only and does not depict the real distribution of galaxies and quasars.

Credit:

ESO/M. Kornmesser

Spooky Alignment of Quasars Across Billions of Light-years

VLT reveals alignments between supermassive black hole axes and large-scale structure


New observations with ESO’s Very Large Telescope (VLT) in Chile have revealed alignments over the largest structures ever discovered in the Universe. A European research team has found that the rotation axes of the central supermassive black holes in a sample of quasars are parallel to each other over distances of billions of light-years. The team has also found that the rotation axes of these quasars tend to be aligned with the vast structures in the cosmic web in which they reside.

Quasars are galaxies with very active supermassive black holes at their centres. These black holes are surrounded by spinning discs of extremely hot material that is often spewed out in long jets along their axes of rotation. Quasars can shine more brightly than all the stars in the rest of their host galaxies put together.

This artist's impression shows schematically the mysterious alignments between the spin axes of quasars and the large-scale structures that they inhabit that observations with ESO’s Very Large Telescope have revealed. These alignments are over billions of light-years and are the largest known in the Universe. The large-scale structure is shown in blue and quasars are marked in white with the rotation axes of their black holes indicated with a line. This picture is for illustration only and does not depict the real distribution of galaxies and quasars. Credit: ESO/M. Kornmesser
This artist’s impression shows schematically the mysterious alignments between the spin axes of quasars and the large-scale structures that they inhabit that observations with ESO’s Very Large Telescope have revealed. These alignments are over billions of light-years and are the largest known in the Universe.
The large-scale structure is shown in blue and quasars are marked in white with the rotation axes of their black holes indicated with a line.
This picture is for illustration only and does not depict the real distribution of galaxies and quasars.
Credit:
ESO/M. Kornmesser

A team led by Damien Hutsemékers from the University of Liège in Belgium used the FORS instrument on the VLT to study 93 quasars that were known to form huge groupings spread over billions of light-years, seen at a time when the Universe was about one third of its current age.

The first odd thing we noticed was that some of the quasars’ rotation axes were aligned with each other — despite the fact that these quasars are separated by billions of light-years,” said Hutsemékers.

The team then went further and looked to see if the rotation axes were linked, not just to each other, but also to the structure of the Universe on large scales at that time.

When astronomers look at the distribution of galaxies on scales of billions of light-years they find that they are not evenly distributed. They form a cosmic web of filaments and clumps around huge voids where galaxies are scarce. This intriguing and beautiful arrangement of material is known as large-scale structure.

The new VLT results indicate that the rotation axes of the quasars tend to be parallel to the large-scale structures in which they find themselves. So, if the quasars are in a long filament then the spins of the central black holes will point along the filament. The researchers estimate that the probability that these alignments are simply the result of chance is less than 1%.

A correlation between the orientation of quasars and the structure they belong to is an important prediction of numerical models of evolution of our Universe. Our data provide the first observational confirmation of this effect, on scales much larger that what had been observed to date for normal galaxies,” adds Dominique Sluse of the Argelander-Institut für Astronomie in Bonn, Germany and University of Liège.

The team could not see the rotation axes or the jets of the quasars directly. Instead they measured the polarisation of the light from each quasar and, for 19 of them, found a significantly polarised signal. The direction of this polarisation, combined with other information, could be used to deduce the angle of the accretion disc and hence the direction of the spin axis of the quasar.

The alignments in the new data, on scales even bigger than current predictions from simulations, may be a hint that there is a missing ingredient in our current models of the cosmos,” concludes Dominique Sluse.

More information

This research was presented in a paper entitled “Alignment of quasar polarizations with large-scale structures“, by D. Hutsemékers et al., to appear in the journal Astronomy & Astrophysics on 19 November 2014.

The team is composed of D. Hutsemékers (Institut d’Astrophysique et de Géophysique, Université de Liège, Liège, Belgium), L. Braibant (Liège), V. Pelgrims (Liège) and D. Sluse (Argelander-Institut für Astronomie, Bonn, Germany; Liège).

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning the 39-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

Source: ESO


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The Party’s Over for These Youthful Compact Galaxies

Researchers using NASA’s Hubble Space Telescope and Chandra X-ray Observatory have uncovered young, massive, compact galaxies whose raucous star-making parties are ending early. The firestorm of star birth has blasted out most of the remaining gaseous fuel needed to make future generations of stars. Now the party’s over for these gas-starved galaxies, and they are on track to possibly becoming so-called “red and dead galaxies,” composed only of aging stars.

Astronomers have debated for decades how massive galaxies rapidly evolve from active star-forming machines to star-starved graveyards. Previous observations of these galaxies reveal geysers of gas shooting into space at up to 2 million miles an hour. Astronomers have suspected that powerful monster black holes lurking at the centers of the galaxies triggered the gaseous outflows and shut down star birth by blowing out any remaining fuel.

Now an analysis of 12 merging galaxies at the end of their star-birthing frenzy is showing that the stars themselves are turning out the lights on their own star-making party. This happened when the universe was half its current age of 13.7 billion years.

“Before our study, the common belief was that stars cannot drive high-velocity outflows in galaxies; only more powerful supermassive black holes can do that,” explained Paul Sell of Texas Tech University in Lubbock, lead author of a science paper describing the study’s results. “Through our analysis we found that if you have a compact enough starburst, which Hubble showed was the case with these galaxies, you can actually produce the velocities of the outflows we observed from the stars alone without needing to invoke the black hole.”

Team member Christy Tremonti of the University of Wisconsin-Madison first identified the galaxies from the Sloan Digital Sky Survey as post-starburst objects spouting high-speed gaseous fountains. The sharp visible-light views from Hubble’s Wide Field Camera 3 show that the outflows are arising from the most compact galaxies yet found. These galaxies contain as much mass as our Milky Way galaxy, but packed into a much smaller area. The smallest galaxies are about 650 light-years across.

In such small regions of space, these galaxies are forming a few hundred suns a year. (By comparison, the Milky Way makes only about one sun a year.) This makes for a rowdy party that wears itself out quickly, in only a few tens of millions of years. One reason for the stellar shutdown is that the gas rapidly heats up, becoming too hot to contract under gravity to form new stars. Another possibility is that the star-birthing frenzy blasts out most of the star-making gas via powerful stellar winds.

“The biggest surprise from Hubble was the realization that the newly formed stars were born so close together,” said team member Aleks Diamond-Stanic of the University of Wisconsin-Madison, who first suggested the possibility of starburst-driven outflows from these galaxies in a 2012 science paper. “The extreme physical conditions at the centers of these galaxies explain how they can expel gas at millions of miles per hour.”

To identify the mechanism triggering the high-velocity outflows, Sell and his team used the Chandra X-ray Observatory and other telescopes to determine whether the galaxies’ supermassive black holes (weighing up to a billion suns) were the powerhouses driving them. After analyzing all of the observations, the team concluded that the black holes were not the source of the outflows. Rather, it was the powerful stellar winds from the most massive and short-lived stars at the end of their lives, combined with their explosive deaths as supernovae.


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Based on their analysis of the Hubble and Chandra data, team members suggest that the “party begins” when two gas-rich galaxies collide, funneling a torrent of cold gas into the merging galaxies’ compact center. The large amount of gas compressed into the small space ignites the birth of numerous stars. The energy from the stellar firestorm then blows out the leftover gas, quenching further star formation.

“If you stop the flow of cold gas to form stars, that’s it,” explained Sell, who conducted the research while a graduate student at the University of Wisconsin-Madison. “The stars stop forming, and the galaxy rapidly evolves and may eventually become a red, dead elliptical galaxy. These extreme starbursts are quite rare, however, so they may not grow into the typical giant elliptical galaxies seen in our nearby galactic neighborhood. They may, instead, be more compact.”

The team’s results were published in the July 11 edition of the Monthly Notices of the Royal Astronomical Society.

Source: Hubble Site

This artist’s impression depicts the formation of a galaxy cluster in the early Universe. The galaxies are vigorously forming new stars and interacting with each other. Such a scene closely resembles the Spiderweb Galaxy (formally known as MRC 1138-262) and its surroundings, which is one of the best-studied protoclusters.

Credit:

ESO/M. Kornmesser

Universe may face a darker future

Since the discovery of the accelerated expansion of the universe in 1997 by High-Z Supernova Team led by Prof. Brian Schmidt and Adam Rees, and by Supernova Cosmology Project Team led by Prof. Saul Perlmutter, the question of the nature of this expansion and the role of the mysterious dark energy has puzzled the minds of many theoretical and observational physicists/astrophysicists.

Another puzzling question in astronomy comes from the unusual behavior of the stars revolving around the galaxies with higher velocities than expected if we consider the apparent baryonic matter in the galaxy.This has led to many new questions related to something we called the dark matter, another unexplained phenomenon.

 


 

New research offers a novel insight into the nature of dark matter and dark energy and what the future of our Universe might be.

Researchers in Portsmouth and Rome have found hints that dark matter, the cosmic scaffolding on which our Universe is built, is being slowly erased, swallowed up by dark energy.

The findings appear in the journal Physical Review Letters, published by the American Physical Society. In the journal cosmologists at the Universities of Portsmouth and Rome, argue that the latest astronomical data favours a dark energy that grows as it interacts with dark matter, and this appears to be slowing the growth of structure in the cosmos.

Professor David Wands, Director of Portsmouth’sInstitute of Cosmology and Gravitation, is one of the research team.

He said: “This study is about the fundamental properties of space-time. On a cosmic scale, this is about our Universe and its fate.

“If the dark energy is growing and dark matter is evaporating we will end up with a big, empty, boring Universe with almost nothing in it.

 

“Dark matter provides a framework for structures to grow in the Universe. The galaxies we see are built on that scaffolding and what we are seeing here, in these findings, suggests that dark matter is evaporating, slowing that growth of structure.”

Cosmology underwent a paradigm shift in 1998 when researchers announced that the rate at which the Universe was expanding was accelerating. The idea of a constant dark energy throughout space-time (the “cosmological constant”) became the standard model of cosmology, but now the Portsmouth and Rome researchers believe they have found a better description, including energy transfer between dark energy and dark matter.

Research students Valentina Salvatelli and Najla Said from the University of Rome worked in Portsmouth with Dr Marco Bruni and Professor Wands, and with Professor Alessandro Melchiorri in Rome. They examined data from a number of astronomical surveys, including the Sloan Digital Sky Survey, and used the growth of structure revealed by these surveys to test different models of dark energy.

Professor Wands said: “Valentina and Najla spent several months here over the summer looking at the consequences of the latest observations. Much more data is available now than was available in 1998 and it appears that the standard model is no longer sufficient to describe all of the data. We think we’ve found a better model of dark energy.

“Since the late 1990s astronomers have been convinced that something is causing the expansion of our Universe to accelerate. The simplest explanation was that empty space – the vacuum – had an energy density that was a cosmological constant. However there is growing evidence that this simple model cannot explain the full range of astronomical data researchers now have access to; in particular the growth of cosmic structure, galaxies and clusters of galaxies, seems to be slower than expected.”

Professor Dragan Huterer,of the University of Michigan, has read the research and said scientists need to take notice of the findings.

He said: “The paper does look very interesting. Any time there is a new development in the dark energy sector we need to take notice since so little is understood about it. I would not say, however, that I am surprised at the results, that they come out different than in the simplest model with no interactions. We’ve known for some months now that there is some problem in all data fitting perfectly to the standard simplest model.”

Source: Materials taken from Uop News

This artist’s impression depicts the formation of a galaxy cluster in the early Universe. The galaxies are vigorously forming new stars and interacting with each other. Such a scene closely resembles the Spiderweb Galaxy (formally known as MRC 1138-262) and its surroundings, which is one of the best-studied protoclusters.

Credit:

ESO/M. Kornmesser

Syracuse Physicists Closer to Understanding Balance of Matter, Antimatter

Physicists in the College of Arts and Sciences have made important discoveries regarding Bs meson particles—something that may explain why the universe contains more matter than antimatter. Distinguished Professor Sheldon Stone and his colleagues recently announced their findings at a workshop at CERN in Geneva, Switzerland. Titled “Implications of LHCb Measurements and Their Future Prospects,” the workshop enabled him and other members of the Large Hadron Collider beauty (LHCb) Collaboration to share recent data results. The LHCb Collaboration is a multinational experiment that seeks to explore what happened after the Big Bang, causing matter to survive and flourish in the Universe. LHCb is an international experiment, based at CERN, involving more than 800 scientists and engineers from all over the world. At CERN, Stone heads up a team of 15 physicists from Syracuse. “Many international experiments are interested in the Bs meson because it oscillates between a matter particle and an antimatter particle,” says Stone, who heads up Syracuse’s High-Energy Physics Group. “Understanding its properties may shed light on charge-parity [CP] violation, which refers to the balance of matter and antimatter in the universe and is one of the biggest challenges of particle physics.” Scientists believe that, 14 billion years ago, energy coalesced to form equal quantities of matter and antimatter. As the universe cooled and expanded, its composition changed. Antimatter all but disappeared after the Big Bang (approximately 3.8 billion years ago), leaving behind matter to create everything from stars and galaxies to life on Earth. “Something must have happened to cause extra CP violation and, thus, form the universe as we know it,” Stone says. He thinks part of the answer lies in the Bs meson, which contains an antiquark and a strange quark and is bound together by a strong interaction. (A quark is a hard, point-like object found inside a proton and neutron that forms the nucleus of an atom.) Enter CERN, a European research organization that operates the world’s largest particle physics laboratory. In Geneva, Stone and his research team—which includes Liming Zhang, a former Syracuse research associate who is now a professor at Tsinghua University in Beijing, China—have studied two landmark experiments that took place at Fermilab, a high-energy physics laboratory near Chicago, in 2009. The experiments involved the Collider Detector at Fermilab (CDF) and the DZero (D0), four-story detectors that were part of Fermilab’s now-defunct Tevatron, then one of the world’s highest-energy particle accelerators. “Results from D0 and CDF showed that the matter-antimatter oscillations of the Bs meson deviated from the standard model of physics, but the uncertainties of their results were too high to make any solid conclusions,” Stone says. He and Zhang had no choice but to devise a technique allowing for more precise measurements of Bs mesons. Their new result shows that the difference in oscillations between the Bs and anti-Bs meson is just as the standard model has predicted. Stone says the new measurement dramatically restricts the realms where new physics could be hiding, forcing physicists to expand their searches into other areas. “Everyone knows there is new physics. We just need to perform more sensitive analyses to sniff it out,” he adds.

Source: Syracuse University

New observations reveal how stardust forms around a supernova

A group of astronomers has been able to follow stardust being made in real time — during the aftermath of a supernova explosion. For the first time they show that these cosmic dust factories make their grains in a two-stage process, starting soon after the explosion, but continuing for years afterwards. The team used ESO’s Very Large Telescope (VLT) in northern Chile to analyse the light from the supernova SN2010jl as it slowly faded. The new results are published online in the journal Nature on 9 July 2014.

The origin of cosmic dust in galaxies is still a mystery [1]. Astronomers know that supernovae may be the primary source of dust, especially in the early Universe, but it is still unclear how and where dust grains condense and grow. It is also unclear how they avoid destruction in the harsh environment of a star-forming galaxy. But now, observations using ESO’s VLT at the Paranal Observatory in northern Chile are lifting the veil for the first time.

An international team used the X-shooter spectrograph to observe a supernova — known as SN2010jl — nine times in the months following the explosion, and for a tenth time 2.5 years after the explosion, at both visible and near-infrared wavelengths [2]. This unusually bright supernova, the result of the death of a massive star, exploded in the small galaxy UGC 5189A.

By combining the data from the nine early sets of observations we were able to make the first direct measurements of how the dust around a supernova absorbs the different colours of light,” said lead author Christa Gall from Aarhus University, Denmark. “This allowed us to find out more about the dust than had been possible before.

The team found that dust formation starts soon after the explosion and continues over a long time period. The new measurements also revealed how big the dust grains are and what they are made of. These discoveries are a step beyond recent results obtained using the Atacama Large Millimeter/submillimeter Array (ALMA), which first detected the remains of a recent supernova brimming with freshly formed dust from the famous supernova 1987A (SN 1987A; eso1401).

 Artist’s impression of dust formation around a supernova explosion. Credit: ESO

Artist’s impression of dust formation around a supernova explosion.
Credit: ESO

The team found that dust grains larger than one thousandth of a millimetre in diameter formed rapidly in the dense material surrounding the star. Although still tiny by human standards, this is large for a grain of cosmic dust and the surprisingly large size makes them resistant to destructive processes. How dust grains could survive the violent and destructive environment found in the remnants of supernovae was one of the main open questions of the ALMA paper, which this result has now answered — the grains are larger than expected.

Our detection of large grains soon after the supernova explosion means that there must be a fast and efficient way to create them,” said co-author Jens Hjorth from the Niels Bohr Institute of the University of Copenhagen, Denmark, and continued: “We really don’t know exactly how this happens.

But the astronomers think they know where the new dust must have formed: in material that the star shed out into space even before it exploded. As the supernova’s shockwave expanded outwards, it created a cool, dense shell of gas — just the sort of environment where dust grains could seed and grow.

Results from the observations indicate that in a second stage — after several hundred days — an accelerated dust formation process occurs involving ejected material from the supernova. If the dust production in SN2010jl continues to follow the observed trend, by 25 years after the supernova, the total mass of dust will be about half the mass of the Sun; similar to the dust mass observed in other supernovae such as SN 1987A.

Previously astronomers have seen plenty of dust in supernova remnants left over after the explosions. But they also only found evidence for small amounts of dust actually being created in the supernova explosions. These remarkable new observations explain how this apparent contradiction can be resolved,” concludes Christa Gall.

Notes

[1] Cosmic dust consists of silicate and amorphous carbon grains — minerals also abundant on Earth. The soot from a candle is very similar to cosmic carbon dust, although the size of the grains in the soot are ten or more times bigger than typical grain sizes for cosmic grains.

[2] Light from this supernova was first seen in 2010, as is reflected in the name, SN 2010jl. It is classed as a Type IIn supernova. Supernovae classified as Type II result from the violent explosion of a massive star with at least eight times the mass of the Sun. The subtype of a Type IIn supernova — “n” denotes narrow — shows narrow hydrogen lines in its spectra. These lines result from the interaction between the material ejected by the supernova and the material already surrounding the star.

More information

This research was presented in a paper “Rapid formation of large dust grains in the luminous supernova SN 2010jl”, by C. Gall et al., to appear online in the journal Nature on 9 July 2014.

The team is composed of Christa Gall (Department of Physics and Astronomy, Aarhus University, Denmark; Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Denmark; Observational Cosmology Lab, NASA Goddard Space Flight Center, USA), Jens Hjorth (Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Denmark), Darach Watson (Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Denmark), Eli Dwek (Observational Cosmology Lab, NASA Goddard Space Flight Center, USA), Justyn R. Maund (Astrophysics Research Centre School of Mathematics and Physics Queen’s University Belfast, UK; Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Denmark; Department of Physics and Astronomy, University of Sheffield, UK), Ori Fox (Department of Astronomy, University of California, Berkeley, USA), Giorgos Leloudas (The Oskar Klein Centre, Department of Physics, Stockholm University, Sweden; Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Denmark), Daniele Malesani (Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Denmark) and Avril C. Day-Jones (Departamento de Astronomia, Universidad de Chile, Chile).

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