Telescope Camera Debuts With Peek At Nest Of Black Holes

Less than two months after they inaugurated the world’s largest telescope, University of Florida astronomers have used one of the world’s most advanced telescopic instruments to gather images of the heavens.

A team led by astronomy professor Stephen Eikenberry late last week captured the first images of the cosmos ever made with a UF-designed and built camera/spectrometer affixed to the Gemini South telescope in Chile. The handful of “first light” images include a yellow and blue orb-like structure that depicts our Milky Way galaxy, home to thousands of black holes – including, at its core, a “supermassive” black hole thought to be as massive as 4 million suns put together.

“We plan to use this instrument to provide the first accurate tracking of the growth and evolution of this black hole over the last 4 billion years,” Eikenberry says.

Installation of the instrument, called FLAMINGOS-2, caps a seven-year, $5 million effort involving 30 UF scientists, engineers, students and staff. Once the instrument is scientifically tested — a process expected to last around six months — it will support a range of new science. Astronomers will use FLAMINGOS-2 (FLAMINGOS is short for the Florida Array Multi-object Imaging Grism Spectrometer) to hunt the universe’s first galaxies, view stars as they are being born, reveal black holes and investigate other phenomena.

“Achieving first light is a great achievement and important milestone,” says Nancy Levenson, deputy director of the Gemini Observatory.

The 8-meter Gemini South telescope in the Chilean Andes is one of only about a dozen 8- to 10-meter telescopes worldwide. All require technologically sophisticated instruments to interpret the light they gather. FLAMINGOS-2 “sees” near-infrared or heat-generated light beyond the range of human vision. It can reveal objects invisible to the eye, such as stars obscured by cosmic dust, or objects so far away they have next to no visible light.

The instrument joins other near-infrared imagers installed on other large telescopes. But it is unusual in its ability to also act as a spectrometer, dividing the light into its component wavelengths. Astronomers analyze these wavelengths to figure out what distant objects are made of, how hot or cold they are, their distance from Earth, and other qualities.

Uniquely, FLAMINGOS-2 can take spectra of up to 80 different objects simultaneously, speeding astronomers’ hunt for old galaxies, black holes or newly forming stars and planets.

“At a cost of $1 per second for operating the Gemini telescope, it will make a huge gain in the scientific productivity and efficiency of the observatory,” Eikenberry says. “What would take an entire year previously can now be done in four nights. This is a real game changer.”

Astronomers compete heavily for time on the world’s largest telescopes, often waiting months or years for the opportunity to make observations. Eikenberry said his FLAMINGOS-2 agreement with Gemini South entitles him to at least 25 nights of observations. He will use the time to contribute to three large studies, or surveys, of the sky headed by UF astronomers.

The first is aimed at learning more about the thousands of black holes and neutron stars at the Milky Way’s center. The second will probe the formation and evolution of galaxies across time, while the third will investigate the birth of new stars.

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Paper on Safety of Large Hadron Collider to be Published

Particle colliders creating black holes that could devour the Earth. Sounds like a great Hollywood script.

But, according to University of California Santa Barbara physics professor Steve Giddings, it's pure fiction.

Giddings has co-authored a paper, "Astrophysical implications of hypothetical stable TeV-scale black holes," that has been accepted for publication in an upcoming edition of the peer-reviewed journal Physical Review D, documenting his study of the safety of microscopic black holes that might possibly be produced by the Large Hadron Collider (LHC), which is nearing completion in Europe. The paper, co-authored by Michelangelo Mangano of the European Center for Nuclear Research (CERN), which is building the world's largest particle collider, investigates hypothesized behavior of tiny black holes that might be created by high-energy collisions in the CERN particle accelerator.

If they appear at all, these black holes would exist for "about a nano-nano-nanosecond," Giddings says, adding that they would have no effect of consequence. However, the paper studies whether there could be any large-scale effects in an extremely hypothetical situation where the black holes don't evaporate.

The Giddings/Mangano study concludes that such microscopic black holes would be harmless. In fact, he added, nature is continuously creating LHC-like collisions when much higher-energy cosmic rays collide with the Earth's atmosphere, with the Sun, and with other objects such as white dwarfs and neutron stars. If such collisions posed a danger, the consequences for Earth or these astronomical objects would have become evident already, Giddings said.

"The future health of our planet and the safety of its people are of paramount concern to us all," Giddings says. "There were already very strong physics arguments that there is no risk from hypothetical micro black holes, and we've provided additional arguments ruling out risk even under very bizarre hypotheses."

The LHC, near Geneva, Switzerland, is expected to begin operations this summer. It will collide proton beams at levels of energy never before produced in a particle accelerator. Those results will then be studied for clues to new forces of nature, and possibly even extra dimensions of space. The first collision of beams is likely to be in September. The $8 billion project has taken 14 years.

Two men have filed a federal lawsuit in Hawaii in an attempt to halt the LHC due to their concerns about the safety of black holes. Giddings' study has been cited by CERN as evidence of the safety of the LHC.

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Milky Way's Giant Black Hole Awoke From Slumber 300 Years Ago

Using NASA,Japanese, and European X-ray satellites, a team of Japanese astronomers has discovered that our galaxy's central black hole let loose a powerful flare three centuries ago.

The finding helps resolve a long-standing mystery: why is the Milky Way's black hole so quiescent? The black hole, known as Sagittarius A* (pronounced "A-star"), is a certified monster, containing about 4 million times the mass of our Sun. Yet the energy radiated from its surroundings is billions of times weaker than the radiation emitted from central black
holes in other galaxies.

"We have wondered why the Milky Way's black hole appears to be a slumbering giant," says team leader Tatsuya Inui of Kyoto University in Japan. "But now we realize that the black hole was far more active in the past. Perhaps it's just resting after a major outburst."

The new study, which will appear in the Publications of the Astronomical Society of Japan, combines results from Japan's Suzaku and ASCA X-ray satellites, NASA's Chandra X-ray Observatory, and the European Space Agency's XMM-Newton X-ray Observatory.

The observations, collected between 1994 and 2005, revealed that clouds of gas near the central black hole brightened and faded quickly in X-ray light as they responded to X-ray pulses emanating from just outside the black hole. When gas spirals inward toward the black hole, it heats up to millions of degrees and emits X-rays. As more and more matter piles up near
the black hole, the greater the X-ray output.

These X-ray pulses take 300 years to traverse the distance between the central black hole and a large cloud known as Sagittarius B2, so the cloud responds to events that occurred 300 years earlier. When the X-rays reach the cloud, they collide with iron atoms, kicking out electrons that are close to the atomic nucleus. When electrons from farther out fill in these gaps, the iron atoms emit X-rays. But after the X-ray pulse passes through, the cloud fades to its normal brightness.

Amazingly, a region in Sagittarius B2 only 10 light-years across varied considerably in brightness in just 5 years. These brightenings are known as light echoes. By resolving the X-ray spectral line from iron, Suzaku's observations were crucial for eliminating the possibility that subatomic particles caused the light echoes.

"By observing how this cloud lit up and faded over 10 years, we could trace back the black hole's activity 300 years ago," says team member Katsuji Koyama of Kyoto University. "The black hole was a million times brighter three centuries ago. It must have unleashed an incredibly powerful flare."

This new study builds upon research by several groups who pioneered the light-echo technique. Last year, a team led by Michael Muno, who now works at the California Institute of Technology in Pasadena, Calif., used Chandra observations of X-ray light echoes to show that Sagittarius A* generated a powerful burst of X-rays about 50 years ago -- about a dozen years before
astronomers had satellites that could detect X-rays from outer space. "The outburst three centuries ago was 10 times brighter than the one we detected," says Muno.

The galactic center is about 26,000 light-years from Earth, meaning those on Earth see events as they occurred 26,000 years ago. Astronomers still lack a detailed understanding of why Sagittarius A* varies so much in its activity. One possibility, says Koyama, is that a supernova a few centuries ago plowed up gas and swept it into the black hole, leading to a temporary feeding frenzy that awoke the black hole from its slumber and produced the giant flare.

Launched in 2005, Suzaku is the fifth in a series of Japanese satellites devoted to studying celestial X-ray sources and is managed by the Japan Aerospace Exploration Agency (JAXA). This mission is a collaborative effort between Japanese universities and institutions and NASA Goddard Spaceflight Center.

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Listening For The Cosmic Symphony

Scientists hope that a new supercomputer being built by Syracuse University's Department of Physics may help them identify the sound of a celestial black hole. The supercomputer, dubbed SUGAR (SU Gravitational and Relativity Cluster), will soon receive massive amounts of data from the California Institute of Technology (Caltech) that was collected over a two-year period at the Laser Interferometer Gravitational-Wave Observatory (LIGO). LIGO is funded by the National Science Foundation and operated by Caltech and the Massachusetts Institute of Technology.

Duncan Brown, assistant professor of physics and member of SU's Gravitational Wave Group, is assembling SUGAR. The department's Gravitational Wave Group is also part of the LIGO Scientific Collaboration (LSC), a worldwide initiative to detect gravitational waves. Brown worked on the LIGO project at Caltech before coming to SU last August.

Gravitational waves are produced by violent events in the distant universe, such as the collision of black holes or explosions of supernovas. The waves radiate across the universe at the speed of light. While Albert Einstein predicted the existence of these waves in 1916 in his general theory of relativity, it has taken decades to develop the technology to detect them. Construction of the LIGO detectors in Hanford, Wash., and Livingston, La., was completed in 2005. Scientists recently concluded a two-year "science run" of the detectors and are now searching the data for these waves. LSC scientists will be analyzing this data while the sensitivity of the detectors is being improved. Detectors have also been built in France, Germany, Italy and Japan.

Before they can isolate the sound of a black hole from the LIGO data, the scientists must figure out what a black hole sounds like. That's where Einstein's theories come in. Working with colleagues from the Simulating eXtreme Spacetimes (SXS) project, Brown will use SUGAR and Einstein's equations to create models of gravitational wave patterns from the collision of two black holes. SXS is a collaborative project with Caltech and Cornell University.

Black holes are massive gravitational fields in the universe that result from the collapse of giant stars. Because black holes absorb light, they cannot be studied using telescopes or other instruments that rely on light waves. However, scientists believe they can learn more about black holes by listening for their gravitational waves.

"Looking for gravitational waves is like listening to the universe," Brown says. "Different kinds of events produce different wave patterns. We want to try to extract a wave pattern -- a special sound -- that matches our model from all of the noise in the LIGO data."

It takes massive amounts of computer power and data storage capacity to analyze the data against the gravitational wave models Duncan and his colleagues built. SUGAR is a collection of 80 computers, packing 320 CPUs of power and 640 Gigabytes of random access memory. SUGAR also has 96 terabytes of disk space on which to store the LIGO data.

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NASA Scientists Predict Black Hole Light Echo Show

It's well known that black holes can slow time to a crawl and tidally stretch large objects into spaghetti-like strands. But according to new theoretical research from two NASA astrophysicists, the wrenching gravity just outside the outer boundary of a black hole can produce yet another bizarre effect: light echoes.

"The light echoes come about because of the severe warping of spacetime predicted by Einstein," says Keigo Fukumura of NASA's Goddard Space Flight Center in Greenbelt, Md. "If the black hole is spinning fast, it can literally drag the surrounding space, and this can produce some wild special effects."

Fukumura and his NASA Goddard colleague Demosthenes Kazanas are presenting their research this Wednesday in a poster session at the American Astronomical Society's 2008 winter meeting in Austin, Texas.

Many black holes are surrounded by disks of searing hot gas that whirl around at nearly the speed of light. Hot spots within these disks sometimes emit random bursts of X-rays, which have been detected by orbiting X-ray observatories. But according to Fukumura and Kazanas, things get more interesting when they take into account Einstein's general theory of relativity, which describes how extremely massive objects like black holes can actually warp and drag the surrounding space-time.

Many of these X-ray photons travel to Earth by taking different paths around the black hole. Because the black hole's extreme gravity warps the surrounding spacetime, it bends the trajectories of the photons so they arrive here with a delay that depends on the relative positions of the X-ray flare, the black hole, and Earth.

But if the black hole rotates very fast, then, according to Fukumura and Kazanas' calculations, the delay between the photons is constant, independent of the source's position. They discovered that for rapidly spinning black holes, about 75 percent of the X-ray photons arrive at the observer after completing a fraction of one orbit around the black hole, while the remaining photons travel the exact same fraction plus one or more full orbits.

"For each X-ray burst from a hot spot, the observer will receive two or more flashes separated by a constant interval, so even a signal made up from a totally random collection of bursts from hot spots at different positions will contain an echo of itself," says Kazanas.

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