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Awesome power of supermassive black holes revealed

April 17, 2010 By vani Leave a Comment

Washington, April 17 (ANI): Nottingham University researchers have shed new light on the super destructive capacity of black holes.

For the study, Asa Bluck in the School of Physics and Astronomy and colleagues, used images of unprecedented depth and resolution from the Hubble Space Telescope and the Chandra X-Ray Observatory to detect black holes in distant galaxies.

Scientists looked for galaxies emitting high levels of radiation and x-rays – a classic signature of black holes devouring gas and dust through accretion, or attracting matter gravitationally.

As this matter swirls around the event horizon of a black hole it heats up and radiates energy – as an accretion disc.

In supermassive black holes this radiation can reach huge proportions, emitting X-ray radiation in far greater quantities then is emitted by the rest of the objects in the galaxy combined – meaning that the black hole ”shines” far brighter than the entire galaxy it lies at the heart of.

In fact, the amount of energy released is sufficient to strip the galaxy of gas at least 25 times over.

Results have also demonstrated that the vast majority of the X-ray radiation present in the universe is produced in these accretion discs surrounding supermassive black holes, with a small proportion produced by all other objects, including galaxies and neutron stars.

The accretions discs surrounding supermassive black holes produce so much energy that they heat up the cold gases lying at the heart of massive galaxies.

The accretion disc shines across all wavelengths – from radio waves to gamma waves.

This speeds up the random motions of the gas, making it rise in temperature and pushing it away from the galactic centre, where it becomes less dense.

Gas needs to be cold and dense to collapse under gravity to form new stars, this resulting hot, low-density material must cool down before gravity will take effect – a process which would take longer than the age of the universe to achieve.

Old stars are therefore left to die out with no new stars replacing them, leaving the galaxy to grow dark and die.

And by pushing gas away from the galactic centre, the accretion disc starves the supermassive black hole of new material to devour, leading to its eventual demise.

Asa Bluck, a PhD student at the University and a Fellow of the Royal Astronomical Society, said: “It”s thought that black holes form inside their host galaxies and grow in proportion to them, forming an accretion disc which will eventually destroy the host. In this sense they can be described as viral in nature.

“Massive galaxies are in the minority in our visible universe – about one in a thousand galaxies is thought to be massive, but it may be much less. And at least a third of these have supermassive black holes at their centre. That”s why it”s so interesting that this type of black hole produces most of the X-ray light in the universe. They are the minority but they dominate energy output.”

The study, a collaboration between researchers at The University of Nottingham and Imperial College London, was presented at the Royal Astronomical Society National Astronomy Meeting in Glasgow. (ANI)

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Scientists discover most massive form of antimatter to date

March 5, 2010 By vani Leave a Comment

Washington, March 5 (ANI): An international team of scientists studying high-energy collisions of gold ions at the Relativistic Heavy Ion Collider (RHIC) has published evidence of the most massive antinucleus discovered to date.

The RHIC is a 2.4-mile-circumference particle accelerator located at the US Department of Energy’s (DOE) Brookhaven National Laboratory.

The new antinucleus, discovered at RHIC’s STAR detector, is a negatively charged state of antimatter containing an antiproton, an antineutron, and an anti-Lambda particle.

It is also the first antinucleus containing an anti-strange quark.

“This experimental discovery may have unprecedented consequences for our view of the world,” commented theoretical physicist Horst Stoecker, Vice President of the Helmholtz Association of German National Laboratories.

“This antimatter pushes open the door to new dimensions in the nuclear chart — an idea that just a few years ago, would have been viewed as impossible,” he added.

The discovery may help elucidate models of neutron stars and opens up exploration of fundamental asymmetries in the early universe.

All terrestrial nuclei are made of protons and neutrons (which in turn contain only up and down quarks).

The standard Periodic Table of Elements is arranged according to the number of protons, which determine each element’s chemical properties.

Physicists use a more complex, three-dimensional chart to also convey information on the number of neutrons, which may change in different isotopes of the same element, and a quantum number known as “strangeness,” which depends on the presence of strange quarks.

Nuclei containing one or more strange quarks are called hypernuclei.

For all ordinary matter, with no strange quarks, the strangeness value is zero and the chart is flat.

Hypernuclei appear above the plane of the chart.

The new discovery of strange antimatter with an antistrange quark (an antihypernucleus) marks the first entry below the plane.

This study of the new antihypernucleus also yields a valuable sample of normal hypernuclei, and has implications for our understanding of the structure of collapsed stars.

“The strangeness value could be non-zero in the core of collapsed stars, so the present measurements at RHIC will help us distinguish between models that describe these exotic states of matter,” said Jinhui Chen, one of the lead authors, a postdoctoral researcher at Kent State University and currently a staff scientist at the Shanghai Institute of Applied Physics.

The findings also pave the way towards exploring violations of fundamental symmetries between matter and antimatter that occurred in the early universe, making possible the very existence of our world. (ANI)

Filed Under: International News Tagged With: brookhaven national laboratory, Dimensional Chart, early universe, Energy Collisions, Experimental Discovery, Gold Ions, Ion Collider, Lambda Particle, neutron stars, new discovery, Number Of Neutrons, Number Of Protons, particle accelerator, Periodic Table Of Elements, Protons And Neutrons, Quantum Number, Star Detector, Strange Quark, Theoretical Physicist, Us Department Of Energy

Indian scientist discovers X-ray bursts from neutron stars can help reveal their size

September 8, 2009 By admin Leave a Comment

Sydney, September 8 (ANI): In a new research, an Indian scientist has determined that the pattern of x-rays generated by neutron stars may reveal their true size.

According to a report by ABC News, Dr Sudip Bhattacharyya of the Tata Institute of Fundamental Research in India led the research.

Neutron stars are the densest objects in the universe; a teaspoonful would weigh as much as a mountain.

“Neutron stars provide a natural laboratory to probe matter at a density five to 10 times higher than that of an atomic nucleus. Such studies cannot be done in terrestrial laboratories,” said Bhattacharyya.

But neutron stars are also very small – approximately 10 kilometres in diameter – making them difficult to detect.

The only neutron stars we can see are pulsars, which spin rapidly and give off bursts of radiation, similar to a lighthouse.

The researchers used a data set of more than 900 bursts from 43 neutron stars gathered by NASA’s Rossi X-ray Timing Explorer satellite.

The bursts occur as the stars consume material from a nearby binary companion, which they orbit.

Neutron stars are so bright that they can radiate as much x-ray energy in one minute as the amount of light radiated by the Sun in approximately one week.

Bhattacharyya and colleagues modelled how the temperature of the bursts changes as they faded and found it varied in relation to the radius of the star.

This change is most likely due to the changing composition of the surface as heavy elements, such as iron, are formed on the star’s outer layer.

Astronomers have long hoped to use the x-ray bursts to determine the radius of neutron stars more precisely.

“Now that this effect is better understood, it is hoped that further analysis will lead to more accurate measurements of the neutron star radius,” said Dr Duncan Galloway, co-author of the study, from Monash University in Melbourne.

“For a given mass, the neutron star’s radius depends on the star’s original composition,” he said.

“If we can simultaneously measure the mass and radius for just one neutron star, we can (in principle) determine which of the possible candidate compositions is correct,” he added.

Astrophysicist Dr Helen Johnston, of the University of Sydney, said that the research is a “nice piece of work.”

She said this should allow astronomers to not only measure the size of neutron stars, but to follow the synthesis of heavier elements normally hidden within the star’s interior. (ANI)

Filed Under: Science News Tagged With: Abc News, accurate measurements, atomic nucleus, bhattacharyya, binary companion, dr duncan, duncan galloway, explorer satellite, indian scientist, NASA, natural laboratory, neutron star, neutron stars, Ray Bursts, Sudip, tata institute of fundamental research, terrestrial laboratories, True Size, University In Melbourne, x rays, x-ray

Astronomers see high-speed galaxy collision in action

July 10, 2009 By admin Leave a Comment

Washington, July 10 (ANI): Astronomers at the Chandra X-ray Observatory have spotted a galaxy collision in action, with one galaxy passing through the core of other galaxies at almost 2 million miles per hour.

The image obtained is of Stephan’s Quintet, a compact group of galaxies discovered about 130 years ago and located about 280 million light years from Earth.

Four of the galaxies in the group are visible in the optical image from the Canada-France-Hawaii Telescope.

A labeled version identifies these galaxies (NGC 7317, NGC 7318a, NGC 7318b and NGC 7319) as well as a prominent foreground galaxy (NGC 7320) that is not a member of the group.

The galaxy NGC 7318b is passing through the core of galaxies at almost 2 million miles per hour, and is thought to be causing the ridge of X-ray emission by generating a shock wave that heats the gas.

Additional heating by supernova explosions and stellar winds has also probably taken place in Stephan’s Quintet.

A larger halo of X-ray emission, detected by ESA’s (European Space Agency’s) XMM-Newton could be evidence of shock heating by previous collisions between galaxies in this group.

Some of the X-ray emissions are likely caused by binary systems containing massive stars that are losing material to neutron stars or black holes.

Stephan’s Quintet provides a rare opportunity to observe a galaxy group in the process of evolving from an X-ray faint system dominated by spiral galaxies to a more developed system dominated by elliptical galaxies and bright X-ray emission.

According to scientists, being able to witness the dramatic effect of collisions in causing this evolution is important for increasing the understanding of the origins of the hot, X-ray bright halos of gas in groups of galaxies.

Stephan’s Quintet shows an additional sign of complex interactions in the past, notably the long tails visible in the optical image.

These features were probably caused by one or more passages through the galaxy group by NGC 7317. (ANI)

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Scientists see singular cosmic act of rebirth

May 22, 2009 By admin Leave a Comment

Washington, May 22 (ANI): An international team of astrophysicists has observed a singular cosmic act of rebirth, by seeing the transformation of an ordinary, slow-rotating pulsar into a superfast millisecond pulsar with an almost infinitely extended lifespan.

The discovery was made during a large radio sky survey by astrophysicists at McGill University, the University of British Columbia (UBC), West Virginia University, the US National Radio Astronomy Observatory (NRAO) and several other institutions in the US, the Netherlands and Australia.

“This survey has found many new pulsars, but this one is truly special – it is a very freshly ‘recycled’ pulsar that is emerging straight from the recycling plant,” said astrophysicist Anne Archibald of the McGill Pulsar Group. ulsars are rapidly rotating, highly magnetized neutron stars, the remnants left after massive stars have exploded as supernovae.

Pulsars emit lighthouse-like beams of radio waves that sweep around as the star rotates.

Most rotate relatively slowly, ten times a second or less, and their magnetic fields ordinarily slow them down even further over the course of millennia.

Millisecond pulsars, however, rotate hundreds of times a second.

“We know normal pulsars typically pulsate in the radio spectrum for one million to ten million years, but eventually they slow down enough to die out,” said Victoria Kaspi of the McGill Pulsar Group.

“But, a few of these old pulsars get ‘recycled’ into millisecond pulsars. They end up spinning extremely fast, and then they can pulsate forever. How does nature manage to be so green?” she added.

It has long been theorized that millisecond pulsars are created in double-star systems when matter from the companion star falls into the pulsar’s gravity well and increases the rotation speed, but until now, the process has never been observed directly.

“We’ve seen systems that are undergoing spin-up, because when the matter is falling in, the stars get really bright in X-rays and they’re easy to see,” said Archibald.

“But, we’ve never seen radio pulsations from these stars during the process of spin-up. At last, we’ve found a true radio pulsar that shows direct evidence for having just been recycled,” she added.

The pulsar found by the survey team was fortuitously observed by an independent, optical research group to have had swirling matter surrounding it roughly a decade ago.

“In other words, for the first time, we have caught a glimpse at an actual cosmic recycling factory in action,” said Ingrid Stairs of UBC.

“This system gives us an unparalleled cosmic laboratory for studying how millisecond pulsars evolve and get reborn,” Stairs added. (ANI)

Filed Under: Science News Tagged With: astrophysicists, companion star, double star systems, massive stars, Mcgill University, millisecond pulsar, national radio astronomy, National Radio Astronomy Observatory, neutron stars, pulsar group, pulsars, Radio Astronomy Observatory, radio sky, radio spectrum, radio waves, recycling plant, rotation speed, Sky Survey, university of british columbia, west virginia university

Star crust found to be 10 billion times stronger than steel

May 7, 2009 By admin Leave a Comment

Washington, May 7 (ANI): A new research by a scientist has shown that the crusts of neutron stars are 10 billion times stronger than steel or any other of the earth’s strongest metal alloys.

The research was done by Charles Horowitz, a professor in the IU (Indiana University) College of Arts and Sciences’ Department of Physics.

He came to came to the conclusion after large-scale molecular dynamics computer simulations were conducted at Indiana University and Los Alamos National Laboratory in New Mexico.

Exhibiting extreme gravity while rotating as fast as 700 times per second, neutron stars are massive stars that collapsed once their cores ceased nuclear fusion and energy production.

The only things more dense are black holes, as a teaspoonful of neutron star matter would weigh about 100 million tons.

Scientists want to understand the structure of neutron stars, in part, because surface irregularities, or mountains, in the crust could radiate gravitational waves and in turn may create ripples in space-time.

“We modeled a small region of the neutron star crust by following the individual motions of up to 12 million particles,” Horowitz said of the work conducted through IU’s Nuclear Theory Center in the Office of the Vice Provost for Research.

“We then calculated how the crust deforms and eventually breaks under the extreme weight of a neutron star mountain,” he added.

Performed on a large computer cluster at Los Alamos National Laboratory and built upon smaller versions created on special-purpose molecular dynamics computer hardware at IU, the simulations identified a neutron star crust that far exceeded the strength of any material known on earth.

The crust could be so strong as to be able to elicit gravitational waves that could not only limit the spin periods of some stars, but that could also be detected by high-resolution telescopes called interferometers, the modeling found.

“The maximum possible size of these mountains depends on the breaking strain of the neutron star crust,” Horowitz said.

“The large breaking strain that we find should support mountains on rapidly rotating neutron stars large enough to efficiently radiate gravitational waves,” he added.

Because of the intense pressure found on neutron stars, structural flaws and impurities that weaken things like rocks and steel are less likely to strain the crystals that form during the nucleosynthesis that occurs to form neutron star crust.

Squeezed together by gravitational force, the crust can withstand a breaking strain 10 billion times the pressure it would take to snap steel. (ANI)

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Crust of neutron stars 10 billion times stronger than steel

April 15, 2009 By admin Leave a Comment

London, April 15 (ANI): New simulations indicate that the crust of neutron stars is 10 billion times stronger than steel.

According to a report in New Scientist, this finding makes the surface of these ultra-dense stars tough enough to support long-lived bulges that could produce gravitational waves detectable by experiments on Earth.

Neutron stars are the cores left behind when relatively massive stars explode in supernovae. They are incredibly dense, packing about as much mass as the sun into a sphere just 20 kilometers or so across, and some rotate hundreds of times per second.

Because of their extreme gravity and rotational speed, neutron stars could potentially make large ripples in the fabric of space – but only if their surfaces contain bumps or other imperfections that would make them asymmetrical.

A number of mechanisms have been proposed to create these bumps. In theory, these bulges could be stable on the outer surface of the star.

Neutron stars are thought to be made up of a soup of neutrons covered with a solid crust. The crust is composed of crystals of neutron-rich atoms.

“But one of the big unknowns for all that work is the strength of the crust. Can you really support a mountain, or will the crust just collapse under the weight?” said Charles Horowitz of Indiana University in Bloomington.

Since laboratory experiments cannot replicate the extreme conditions on the surface of a neutron star, astronomers have largely assumed that the crust’s strength would be similar to that of the strongest substances on Earth.

But in new computer simulations, Horowitz and Kai Kadau of the Los Alamos National Laboratory show the crust of a neutron star is much stronger.

Materials like rock and steel break because their crystals have gaps and other defects that link up to create cracks. But, the enormous pressures in neutron stars squeeze out many of the imperfections.

That produces extraordinarily clean crystals that are harder to break.

A cube of neutron star crust can be deformed by 20 times more than a cube of stainless steel before breaking.

But the atoms in neutron star crusts are pulled together much more tightly than in steel, so it takes 10 billion times as much pressure to push it to the breaking point, Horowitz told New Scientist.

The stronger crust means a neutron star can support a larger bulge than thought. A “mountain” could rise some 10 centimeters above the surface, stretching over several kilometers.

That would produce gravitational waves with 100 times the energy as those previously calculated. (ANI)

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Scientists find oldest isolated pulsar ever

February 27, 2009 By admin Leave a Comment

Washington, Feb 27 (ANI): With the help of NASA’s Chandra X-ray Observatory, scientists have found the oldest isolated pulsar ever detected in X-rays.

The pulsar, PSR J0108-1431 (J0108 for short), which is about 200 million years old, turns out to be surprisingly active.

Among isolated pulsars, ones that have not been spun-up in a binary system, it is over 10 times older than the previous record holder with an X-ray detection.

At a distance of 770 light years, it is one of the nearest pulsars known.

Pulsars are born when stars that are much more massive than the Sun collapse in supernova explosions, leaving behind a small, incredibly weighty core, known as a neutron star.

At birth, these neutron stars, which contain the densest material known in the Universe, are spinning rapidly, up to a hundred revolutions per second.

As the rotating beams of their radiation are seen as pulses by distant observers, similar to a lighthouse beam, astronomers call them “pulsars”.

Astronomers observe a gradual slowing of the rotation of the pulsars as they radiate energy away.

Radio observations of J0108 show it to be one of the oldest and faintest pulsars known, spinning only slightly faster than one revolution per second.

The surprise came when a team of astronomers led by George Pavlov of Penn State University observed J0108 in X-rays with Chandra.

They found that it glows much brighter in X-rays than was expected for a pulsar of such advanced years.

Some of the energy that J0108 is losing as it spins more slowly is converted into X-ray radiation. The efficiency of this process for J0108 is found to be higher than for any other known pulsar.

“This pulsar is pumping out high-energy radiation much more efficiently than its younger cousins,” said Pavlov. “So, although it’s clearly fading as it ages, it is still more than holding its own with the younger generations,” he added.

At its advanced age, J0108 is close to the so-called “pulsar death line,” where its pulsed radiation is expected to switch off and it will become much harder, if not impossible, to observe.

“We can now explore the properties of this pulsar in a regime where no other pulsar has been detected outside the radio range,” said co-author Oleg Kargaltsev of the University of Florida.

“To understand the properties of ‘dying pulsars,’ it is important to study their radiation in X-rays. Our finding that a very old pulsar can be such an efficient X-ray emitter gives us hope to discover new nearby pulsars of this class via their X-ray emission,” he added. (ANI)

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Indian space engineers start work on country’s first national Astronomy satellite

February 6, 2009 By admin Leave a Comment

London, Feb 5 (ANI): A team of space engineers from India has arrived in England to work with a team from the University of Leicester to start work on Astrosat, which is India’s first national Astronomy satellite.

The team, from the Tata Institute of Fundamental Research (TIFR), Mumbai, will assemble key components of Astrosat, which is due for launch in 2009.

The engineers will work on the next phase of the mission, when hardware manufactured in India arrives in Leicester for inspection, testing and assembly into a space qualified X-ray camera.

“In several months, when the camera has been assembled and the Leicester built detector assembly and control electronics installed, it will be tested to space qualified standards and shipped back to India for integration into the spacecraft,” said Guy Peters, Astrosat SXT Project Manager UK.

According to Sangam Sinha from the Tata Institute, “Astrosat is critical to the Indian space programme as it is the first satellite entirely dedicated to the pursuit of science.”
Astrosat also forms the beginning of a long term collaboration between TIFR and the University of Leicester through which it is hoped that many more missions will be undertaken jointly by the Indian and UK teams,” he added.

Astrosat will carry five instruments to observe exotic objects such as black holes, neutron stars, and active galaxies at a number of different wavelengths simultaneously, from the ultraviolet band to energetic x-rays.

The camera was designed by the University of Leicester and the manufacture of the hardware components was undertaken by the Tata Institute of Fundamental Research.
n addition to the manufacture of the camera hardware, the Tata Institute of Fundamental Research has built the main telescope body and mirror.

The University of Leicester is to assemble the camera, support the project through consultancy and calibrate the camera at the Space Research Centre. (ANI)

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