Posted on by Tammy Plotner

Chandra Captures Enticing Evidence Of Black Hole’s Bondi Radius

The galaxy NGC 3115 is shown here in a composite image of data from NASA's Chandra X-ray Observatory and the European Southern Observatory's Very Large Telescope (VLT). Credit: X-ray: NASA/CXC/Univ. of Alabama/K.Wong et al, Optical: ESO/VLT

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Those who are interested in black holes are familiar with the event horizon, but the Chandra X-Ray Observatory is giving us an even more detailed look into the structure surrounding these enigmas by imaging the inflowing hot gases. Galaxy NGC 3115 contains a supermassive black hole at its heart and for the first time astronomers have evidence of a critical threshold known as the “Bondi radius”.

Located approximately 32 million light years from the Solar System in the constellation of Sextans, NGC 3115 is a prime candidate for study. Contained in its nucleus is a billion-solar-mass black hole which is stripping away hot gases from nearby stars which can be imaged in X-ray. “The Chandra data are shown in blue and the optical data from the VLT are colored gold. The point sources in the X-ray image are mostly binary stars containing gas that is being pulled from a star to a stellar-mass black hole or a neutron star. The inset features the central portion of the Chandra image, with the black hole located in the middle.” says the team. “No point source is seen at the position of the black hole, but instead a plateau of X-ray emission coming from both hot gas and the combined X-ray emission from unresolved binary stars is found.”

In order to see the machination of the black hole at work, the Chandra team eradicated the signal given off by the binary stars, separating it from the super-heated gas flow. By observing the gas at varying distances the team could then pinpoint a threshold where the gas first becomes impacted by the supermassive black hole’s gravity and begins moving towards the center. This point is known as the Bondi radius.

“As gas flows toward a black hole it becomes squeezed, making it hotter and brighter, a signature now confirmed by the X-ray observations. The researchers found the rise in gas temperature begins at about 700 light years from the black hole, giving the location of the Bondi radius.” says the Chandra team. “This suggests that the black hole in the center of NGC 3115 has a mass of about two billion times that of the Sun, supporting previous results from optical observations. This would make NGC 3115 the nearest billion-solar-mass black hole to Earth.”

Original Story Source: Chandra News Further Reading: Resolving the Bondi Accretion Flow toward the Supermassive Black Hole of NGC 3115 with Chandra.

Posted on by Nancy Atkinson

Is This a Scene from Star Wars or a Real Image from the ISS?

An X-Wing fighter in space? Actually the ATV2 (Johannes Kepler) as it departs the ISS in 2011. Credit: NASA/Ron Garan

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What an amazing image! The ATV-2 Johannes Kepler looks like an X-Wing fighter from Star Wars as it departed from the International Space Station. Astronaut Ron Garan posted the image on his Twitpic page, asking viewers if they thought the spacecraft looked like the fictional fighter jets of the Alliance.

The ATV-2 left the ISS and entered Earth’s atmosphere on June 21. The spacecraft had a “blackbox” on board, a Re-Entry Breakup Recorder (REBR) to monitor temperature, acceleration, rotation rate, and other data as it tumbled and disintegrated through the atmosphere. The data was sent down via a “phone call” to an Iridium satellite to help scientists better understand the physics of what happens to a spacecraft when it breaks up on re-entry.

So, enjoy one last beautiful look at the ATV-2 in this stunning image.

You can follow Universe Today senior editor Nancy Atkinson on Twitter: @Nancy_A. Follow Universe Today for the latest space and astronomy news on Twitter @universetoday and on Facebook.

Posted on by Nancy Atkinson

No Joy for Dark Matter Detector’s First 100 Days

Bottom photomultiplier tube array on the XENON 100 detector. Credit: the XENON collaboration

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We’re still mostly in the dark about Dark Matter, and the highly anticipated results from the XENON100 detector has perhaps shed a tad more light on the subject – by not making a detection in the first 100 days of the experiment. Researchers from the project say they have now been able to place the most stringent limits yet on the properties of dark matter.

To look for any possible hints of Dark Matter interacting with ordinary matter, the project has been looking for WIMPS — or weakly interacting massive particles – but for now, there is no new evidence for the existence of WIMPS, or Dark Matter either.

The extremely sensitive XENON100 detector is buried beneath the Gran Sasso mountain in central Italy, shielding it from cosmic radiation so it hopefully can detect WIMPS, hypothetical particles that might be heavier than atomic nuclei, and the most popular candidate for what Dark Matter might be made of. The detector consists of 62 kg of liquid xenon contained within a heavily shielded tank. If a WIMP would enter the detector, it should interact with the xenon nuclei to generate light and electric signals – which would be a kind of “You Have Won!” indicator.

Dark Matter is thought to make up more than 80% of all mass in the universe, but the nature of it is still unknown. Scientists believe that it is made up of exotic particles unlike the normal (baryonic) matter, which we, the Earth, Sun and stars are made of, and it is invisible so it has only been inferred from its gravitational effects.

The XENON detector ran from January to June 2010 for its first run, and in their paper on arxiv, the team revealed they found three candidate events that might be due to Dark Matter. But two of these were expected to appear anyway because of background noise, the team said, so their results are effectively negative.

Does this rule out the existence of WIMPS? Not necessarily – the team will keep working on their search. Plus, results from a preliminary analysis from11.2 days worth of data, taken during the experiment’s commissioning phase in October and November 2009, already set new upper limits on the interaction rate of WIMPs – the world’s best for WIMP masses below about 80 times the mass of a proton.

And the XENON100 team was optimistic. “These new results reveal the highest sensitivity reported as yet by any dark matter experiment, while placing the strongest constraints on new physics models for particles of dark matter,” the team said in a statement.

Read the team’s paper.

More info on XENON100

Sources: EurekAlert, physicsworld

Posted on by Nancy Atkinson

A New Way to Visualize Warped Space and Time

By combining theory with computer simulations, Thorne and his colleagues at Two doughnut-shaped vortexes ejected by a pulsating black hole. Also shown at the center are two red and two blue vortex lines attached to the hole, which will be ejected as a third doughnut-shaped vortex in the next pulsation. Credit: The Caltech/Cornell SXS Collaboration

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Trying to understand the warping of space and time is something like visualizing a scene from Alice in Wonderland where rooms can change sizes and locations. The most-used description of the warping of space-time is how a heavy object deforms a stretched elastic sheet. But in actuality, physicists say this warping is so complicated that they really haven’t been able to understand the details of what goes on. But new conceptual tools that combines theory and computer simulations are providing a better way to for scientists to visualize what takes place when gravity from an object or event changes the fabric of space.

Researchers at Caltech, Cornell University, and the National Institute for Theoretical Physics in South Africa developed conceptual tools that they call tendex lines and vortex lines which represent gravitation waves. The researchers say that tendex and vortex lines describe the gravitational forces caused by warped space-time and are analogous to the electric and magnetic field lines that describe electric and magnetic forces.

“Tendex lines describe the stretching force that warped space-time exerts on everything it encounters,” said says David Nichols, a Caltech graduate student who came up with the term ‘tendex.’. “Tendex lines sticking out of the Moon raise the tides on the Earth’s oceans, and the stretching force of these lines would rip apart an astronaut who falls into a black hole.”

Vortex lines, on the other hand, describe the twisting of space. So, if an astronaut’s body is aligned with a vortex line, it would get wrung like a wet towel.

Two spiral-shaped vortexes (yellow) of whirling space sticking out of a black hole, and the vortex lines (red curves) that form the vortexes. Credit: The Caltech/Cornell SXS Collaboration

They tried out the tools specifically on computer simulated black hole collisions, and saw that such impacts would produce doughnut-shaped vortex lines that fly away from the merged black hole like smoke rings. The researchers also found that a bundle of vortex lines spiral out of the black hole like water from a rotating sprinkler. Depending on the angles and speeds of the collisions, the vortex and tendex lines — or gravitational waves — would behave differently.

“Though we’ve developed these tools for black-hole collisions, they can be applied wherever space-time is warped,” says Dr. Geoffrey Lovelace, a member of the team from Cornell. “For instance, I expect that people will apply vortex and tendex lines to cosmology, to black holes ripping stars apart, and to the singularities that live inside black holes. They’ll become standard tools throughout general relativity.”

The researchers say the tendex and vortex lines provide a powerful new way to understand the nature of the universe. “Using these tools, we can now make much better sense of the tremendous amount of data that’s produced in our computer simulations,” says Dr. Mark Scheel, a senior researcher at Caltech and leader of the team’s simulation work.

Their paper has been published in the April 11 in the Physical Review Letters.

Source: CalTech

Posted on by Nancy Atkinson

Particle Physicists See Something Little That Could be Really Big

The dijet invariant mass distribution seen by Fermilab. The blue histogram represents something that is not predicted by the Standard Model. Credit: Fermilab

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Physicists from Fermilab have seen a “bump” in their data that could indicate a brand new particle unlike any ever seen before. If verified, this could re-write particle physics as we know it. “Essentially, the Tevatron has seen evidence for a new particle, 150 times mass of proton, that doesn’t behave like a standard Higgs particle,” said physicist Brian Cox on Twitter. “If this stands up to scrutiny and more data (there is not yet enough data for a “discovery”), then it is RIP Standard Model.”

“It was hard for us to not go crazy when we saw the results,” said Viviana Cavaliere from the University of Illinois (UIUC), one of the 500-member team working with the CDF particle detector at Fermi National Accelerator Laboratory in Batavia, Illinois, speaking on a webcast on April 6. “But for now, we need to stay focused on what we do know.”

The result comes from CDF’s (the Collider Detector at Fermilab) analysis of billions of collisions of protons and antiprotons produced by Fermilab’s Tevatron collider. In high energy collisions, subatomic particles can be detected that otherwise can’t be seen. Physicists try to identify the particles they see by studying the combinations of more-familiar particles into which they decay, while trying to find new particles, such as the theoretical Higgs Boson which is predicted by the Standard Model of particle physics.

The Standard Model contains a description of the elementary particles and forces inside atoms which make up everything around us. The model has been successful at making predictions that have been subsequently verified. There are sixteen named particles in the Standard Model, and the last particles discovered were the W and Z bosons in 1983, the top quark in 1995, and the tauon neutrino in 2000. But most physicists agree the Standard Model is probably not the final word in particle physics.

The researchers at Fermilab were searching for collisions that produced a W boson, which weighs about 87 times as much as a proton, as well as some other particles that disintegrate into two sprays of particles called “jets,” which are produced when a collision scatters out a particle called a quark.

Instead, they saw about 250 events which indicate a new particle weighing about 150 times as much as a proton, the team said at the webcast from Fermilab and in their paper on arXiv.

The researchers estimate the statistical chances of random jets or jet pairs from other sources producing a fake signal that strong at 1 in 1300.

The Standard Model does not predict anything like what was seen in the CDF experiment, and since this particle has not been seen before and appears to have some strange properties, the physicists want to verify and retest before claiming a discovery.

“If it is not a fluctuation, it is a new particle,” Cox said.

The Tevatron accelerator at Fermilab is scheduled to be shut down later this year, due to lack of funding and because of sentiments that it would be redundant to the Large Hadron Collider.

You can see more complete discussions and interpretations of the results at:

Cosmic Variance

Science News

MSNBC

Posted on by Nancy Atkinson

The Moon Helps Radio Astronomers Search for Neutrinos

Radio astronomers get an assist from the Moon. Credit: Ted Jaeger, University of Iowa, NRAO/AUI/NSF

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From an NRAO press release:

Seeking to detect mysterious, ultra-high-energy neutrinos from distant regions of space, a team of astronomers used the Moon as part of an innovative telescope system for the search. Their work gave new insight on the possible origin of the elusive subatomic particles and points the way to opening a new view of the Universe in the future.

The team used special-purpose electronic equipment brought to the National Science Foundation’s Very Large Array (VLA) radio telescope, and took advantage of new, more-sensitive radio receivers installed as part of the Expanded VLA (EVLA) project. Prior to their observations, they tested their system by flying a small, specialized transmitter over the VLA in a helium balloon.

In 200 hours of observations, Ted Jaeger of the University of Iowa and the Naval Research Laboratory, and Robert Mutel and Kenneth Gayley of the University of Iowa did not detect any of the ultra-high-energy neutrinos they sought. This lack of detection placed a new limit on the amount of such particles arriving from space, and cast doubt on some theoretical models for how those neutrinos are produced.

Neutrinos are fast-moving subatomic particles with no electrical charge that readily pass unimpeded through ordinary matter. Though plentiful in the Universe, they are notoriously difficult to detect. Experiments to detect neutrinos from the Sun and supernova explosions have used large volumes of material such as water or chlorine to capture the rare interactions of the particles with ordinary matter.

The ultra-high-energy neutrinos the astronomers sought are postulated to be produced by the energetic, black-hole-powered cores of distant galaxies; massive stellar explosions; annihilation of dark matter; cosmic-ray particles interacting with photons of the Cosmic Microwave Background; tears in the fabric of space-time; and collisions of the ultra-high-energy neutrinos with lower-energy neutrinos left over from the Big Bang.

Radio telescopes can’t detect neutrinos, but the scientists pointed sets of VLA antennas around the edge of the Moon in hopes of seeing brief bursts of radio waves emitted when the neutrinos they sought passed through the Moon and interacted with lunar material. Such interactions, they calculated, should send the radio bursts toward Earth. This technique was first used in 1995 and has been used several times since then, with no detections recorded. The latest VLA observations have been the most sensitive yet done.

“Our observations have set a new upper limit — the lowest yet — for the amount of the type of neutrinos we sought,” Mutel said. “This limit eliminates some models that proposed bursts of these neutrinos coming from the halo of the Milky Way Galaxy,” he added. To test other models, the scientists said, will require observations with more sensitivity.

“Some of the techniques we developed for these observations can be adapted to the next generation of radio telescopes and assist in more-sensitive searches later,” Mutel said. “When we develop the ability to detect these particles, we will open a new window for observing the Universe and advancing our understanding of basic astrophysics,” he said.

The scientists reported their work in the December edition of the journal Astroparticle Physics.

Source: NRAO

Posted on by Nancy Atkinson

Penrose: WMAP Shows Evidence of ‘Activity’ Before Big Bang

WMAP data of the Cosmic Microwave Background. Credit: NASA
WMAP data of the Cosmic Microwave Background. Credit: NASA

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Have scientists seen evidence of time before the Big Bang, and perhaps a verification of the idea of the cyclical universe? One of the great physicists of our time, Roger Penrose from the University of Oxford, has published a new paper saying that the circular patterns seen in the WMAP mission data on the Cosmic Microwave Background suggest that space and time perhaps did not originate at the Big Bang but that our universe continually cycles through a series of “aeons,” and we have an eternal, cyclical cosmos. His paper also refutes the idea of inflation, a widely accepted theory of a period of very rapid expansion immediately following the Big Bang.

Penrose says that inflation cannot account for the very low entropy state in which the universe was thought to have been created. He and his co-author do not believe that space and time came into existence at the moment of the Big Bang, but instead, that event was just one in a series of many. Each “Big Bang” marked the start of a new aeon, and our universe is just one of many in a cyclical Universe, starting a new universe in place of the one before.

Penrose’s co-author, Vahe Gurzadyan of the Yerevan Physics Institute in Armenia, analyzed seven years’ worth of microwave data from WMAP, as well as data from the BOOMERanG balloon experiment in Antarctica. Penrose and Gurzadyan say they have identified regions in the microwave sky where there are concentric circles showing the radiation’s temperature is markedly smaller than elsewhere.

These circles allow us to “see through” the Big Bang into the aeon that would have existed beforehand. The circles were created when black holes “encountered” or collided with a previous aeon.

“Black-hole encounters, within bound galactic clusters in that previous aeon, would have the observable effect, in our CMB sky,” the duo write in their paper, “of families of concentric circles over which the temperature variance is anomalously low.”

And these circles don’t jive with the idea of inflation, because inflation proposes that the distribution of temperature variations across the sky should be Gaussian, or random, rather than having discernable structures within it.

Penrose’s new theory even projects how the distant future might emerge, where things will again be similar to the beginnings of the Universe at the Big Bang where the Universe was smooth, as opposed to the current jagged form. This continuity of shape, he maintains, will allow a transition from the end of the current aeon, when the universe will have expanded to become infinitely large, to the start of the next, when it once again becomes infinitesimally small and explodes outwards from the next big bang.

Penrose and Gurzadyan say that the entropy at the transition stage will be very low, because black holes, which destroy all information that they suck in, evaporate as the universe expands and in so doing remove entropy from the universe.

“These observational predictions of (Conformal cyclic cosmology) CCC would not be easily explained within standard inflationary cosmology,” they write in their paper.

Read Penrose and Gurzadyan’s paper: “Concentric circles in WMAP data may provide evidence of violent pre-Big-Bang activity”

Additional source: PhysicsWorld

Posted on by Jon Voisey

Hawking(ish) Radiation Observed

In 1974, Steven Hawking proposed a seemingly ridiculous hypothesis. Black holes, the gravitational monsters from which nothing escapes, evaporate. To justify this, he proposed that pairs of virtual particles in which one strayed too close to the event horizon, could be split, causing one particle to escape and become an actual particle that could escape. This carrying off of mass would take energy and mass away from the black hole and deplete it. Due to the difficulty of observing astronomical black holes, this emission has gone undetected. But recently, a team of Italian physicists, led by Francesco Belgiorno, claims to have observed Hawking radiation in the lab. Well, sort of. It depends on your definition.

The experiment worked by sending powerful laser pulses through a block of ultra-pure glass. The intensity of the laser would change the optical properties of the glass increasing the refractive index to the point that light could not pass. In essence, this created an artificial event horizon. But instead of being a black hole which particles could pass but never return, this created a “white hole” in which particles could never pass in the first place. If a virtual pair were created near this barrier, one member could be trapped on one side while the other member could escape and be detected creating a situation analogous to that predicted by Hawking radiation.

Readers with some background in quantum physics may be scratching their heads at this point. The experiment uses a barrier to impede the photons, but quantum tunneling has demonstrated that there’s no such thing as a perfect barrier. Some photons should tunnel through. To avoid detecting these photons, the team simply moved the detector. While some photons will undoubtedly tunnel through, they would continue on the same path with which they were set. The detector was moved 90º to avoid detecting such photons.

The change in position also helped to minimize other sources of false detections such as scattering. At 90º, scattering only occurs for vertically polarized light and the experiment used horizontally polarized light. As a check to make sure none of the light became mispolarized, the team checked to ensure no photons of the emitted wavelength were observed. The team also had to guard against false detections from absorption and re-emission from the molecules in the glass (fluorescence). This was achieved through experimentation to gain an understanding of how much of this to expect so the effects could be subtracted out. Additionally, the group chose a wavelength in which fluorescence was minimized.

After all the removal of sources of error for which the team could account, they still reported a strong signal which they interpreted as coming from separated virtual particles and call a detection of Hawking radiation. Other scientists disagree in the definition. While they do not question the interpretation, others note that Hawking radiation, by definition, only occurs at gravitational event horizons. While this detection is interesting, it does not help to shed light on the more interesting effects that come with such gravitational event horizons such as quantum gravity or the paradox provided by the Trans-Planckian problem. In other words, while this may help to establish that virtual particles like this exist, it says nothing of whether or not they could truly escape from near a black hole, which is a requirement for “true” Hawking radiation.

Meanwhile, other teams continue to explore similar effects with other artificial barriers and event horizons to explore the effects of these virtual particles. Similar effects have been reported in other such systems including ones with water waves to form the barrier.

Posted on by Jerry Coffey

What Is Mechanical Energy

Millennium Force roller coaster Credit: Cedar Point
Millennium Force roller coaster Credit: Cedar Point

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The straight forward answer to ‘what is mechanical energy’ is that it is the sum of energy in a mechanical system. This energy includes both kinetic energy(energy of motion) and potential energy(stored energy).

Objects have mechanical energy if they are in motion and/or if they are at some position relative to a zero potential energy position. A few examples are: a moving car possesses mechanical energy due to its motion(kinetic energy) and a barbell lifted high above a weightlifter’s head possesses mechanical energy due to its vertical position above the ground(potential energy).

Kinetic energy is the energy of motion. An object that has motion, vertical or horizontal motion, has kinetic energy. There are many forms of kinetic energy: vibrational (the energy due to vibrational motion), rotational (the energy due to rotational motion), and translational (the energy due to motion from one location to another).

Potential energy is the energy stored in a body or in a system due to its position in a force field or its configuration. The standard unit of measure for energy and work is the joule. The term “potential energy” has been used since the 19th century.

Because of the different components of mechanical energy, it exists in every system in the universe. From a baseball being thrown to a brick falling off of a ledge, mechanical energy surrounds us. Defining what is mechanical energy is easy, but finding examples of it are even easier.

We have written many articles about mechanical energy for Universe Today. Here’s an article about how generators work, and here’s an article about what is energy.

If you’d like more info on Mechanical Energy, check out a Discussion on Energy, and here’s a link to an article about Momentum.

We’ve also recorded an entire episode of Astronomy Cast all about Gravity. Listen here, Episode 102: Gravity.

Posted on by Steve Nerlich

Astronomy Without A Telescope – Is An Anomalous Anomaly A Normality?

The lack of any flyby anomaly effect when the Rosetta spacecraft passed Earth in November 2009 is what, an anomaly? No. Anomalies arise when there is a mismatch between a predicted and an observed value. When it happens our first thought shouldn’t be that OMG there’s something wrong with physics! We should probably start by reviewing whether we really got the math right.

The flyby anomaly story starts with the Galileo spacecraft‘s flyby of Earth in December 1990 – where it was measured to have gained a speed increase (at least, an increase over the predicted value) of 2.5 millimeters per second at perigee. In its second pass in December 1992, the predicted value was the same as the observed value, although it has been suggested that atmospheric drag effects confound any analysis of this particular flyby.

The next, and biggest anomaly so far detected, was the NEAR spacecraft‘s flyby in 1998 (a whopping 7.2 millimeters per second at perigee increase over the predicted value). After that you have Rosetta showing an anomaly on its first flyby in 2005. Then a quantitative formula which aimed to model the various flybys to date was developed by Anderson et al in 2007 – predicting a small but detectable speed increase would be found in Rosetta’s second fly-by of 13 November 2007. However (or should I say anomalously), no such increase was detected in this, or in Rosetta’s third (2009), pass.

So, on balance, our spacecraft (and often the same spacecraft) are more likely to behave as predicted than to behave anomalously. This reduces (though not negates) the likelihood of the anomaly being anything of substance. One might sagely state that the intermittent absence of an anomaly is not in itself anomalous.

More recently, Mbelek in 2009 has proposed that the anomalous flyby data (including Anderson et al’s formula) can be explained by a more rigorous application of special relativity principles, concluding that ‘spacecraft flybys of heavenly bodies may be viewed as a new test of SR which has proven to be successful near the Earth’. If such recalculated predicted values match observed values in future flybys, that would seem to be that.

Pioneer 10 - launched in 1972 and now making its way out towards the star Aldebaran, which it should pass in about 2 million years. Credit: NASA

Then there’s the Pioneer anomaly. This has no obvious connection with the flyby anomaly, apart from a common use of the word anomaly, which gives us another epistemological maxim – two unrelated anomalies do not one bigger anomaly make.

Between around 20 and 70 AU out from Earth, Pioneer 10 and 11 both showed tiny but unexpected decelerations of around 0.8 nanometers per second2 – although again we are just talking about an observed value that differed from a predicted value.

Some key variables not considered in calculating the original predicted value are radiation pressure from sunlight-heated surfaces, as well as internal radiation generated from the spacecrafts’ own (RTG) power source. A Planetary Society update of an ongoing review of the Pioneer data indicated that revised predicted values now show less discrepancy from the observed values. Again, this doesn’t yet negate the anomaly – but given the trend for more scrutiny equals less discrepancy, it’s fair to say that this anomaly is also becoming less substantial.

Don’t get me wrong, this is all very useful science, teaching us more about how our spacecraft operate out there in the field. I am just suggesting that when faced with a data anomaly perhaps our first reaction should be Doh! rather than OMG!