yeah, um, that's what i was thinking

I saw this earlier today, amazing pictures.

Is the small black hole feeding or consuming mater from it's companion star? The picture gives that impression.

Yes, it is stripping the outer atmosphere from the companion. It is not only black holes that do this, compact companion stars often do this to larger less compact companions if they orbit closely enough to each other, for example a white dwarf will often strip the atmosphere from a red giant.

News Release Number: STScI-2008-14


A well-known star cluster that glitters with the light of millions of stars may have a mysterious dark object tugging at its core. Astronomers have found evidence for a medium- size black hole at the core of Omega Centauri, one of the largest and most massive globular star clusters orbiting our Milky Way Galaxy.

The intermediate-mass black hole is estimated to be roughly 40,000 times the mass of the Sun. The black hole was discovered with NASA's Hubble Space Telescope and Gemini Observatory on Cerro Pachon in Chile. The ancient cluster is located 17,000 light-years from Earth.

Globular clusters are gravitationally bound swarms of typically up to a million stars. There are more than 200 globular clusters in our Milky Way Galaxy.

"This result shows that there is a continuous range of masses for black holes, from supermassive, to intermediate, to small, stellar types," explained astronomer Eva Noyola of the Max-Planck Institute for Extraterrestrial Physics in Garching, Germany, and leader of the team that made the discovery. "This finding also is important because the theory of formation for supermassive black holes requires seed black holes that are exactly in the mass range of the one we found. Such seeds have not been identified so far. If these types of intermediate-mass black holes happen to be common in star clusters, then they can provide numerous seeds for the formation of the supermassive black holes."

Astronomers have debated the existence of moderately sized black holes because they have not found strong evidence for them, and there is no widely accepted mechanism for how they could form. They have ample evidence that small black holes of a few solar masses are produced when giant stars die. There is similar evidence that supermassive black holes weighing the equivalent of millions to billions of solar masses sit at the heart of many galaxies, including our Milky Way.

"Before this observation, we had only one example of an intermediate-mass black hole in the globular cluster G1, in the nearby Andromeda Galaxy," said astronomer Karl Gebhardt of the University of Texas at Austin and a member of the team that made the discovery.

Noyola and Gebhardt used Hubble and Gemini to gather evidence for the black hole. Hubble's Advanced Camera for Surveys showed how the stars are bunching up near the center of Omega Centauri, as seen in the gradual increase in starlight near the center.

Measuring the speed of the stars swirling near the cluster's center with the Gemini Observatory, the astronomers found that the stars closer to the core are moving faster than the stars farther away. The measurement implies that some unseen matter at the core is tugging on stars near it.

By comparing these results with standard models, the astronomers determined that the most likely cause of this accelerating stellar traffic jam is the gravitational pull of a massive, dense object, the astronomers explained. They also used models to calculate the black hole's mass.

Although the presence of an intermediate-mass black hole is the most likely reason for the stellar speedway near the cluster's center, the astronomers said they have considered a couple of other possible causes.

In the first scenario, the traffic jam of stars near the center is due to a collection of burned- out stars such as white dwarfs or neutron stars. Another possibility is that stars in the center of Omega Centauri have elongated orbits that would make the stars closest to the center appear to speed up.

"For both alternative scenarios it is very hard to get stars to behave that way, either the burned-out stars really bunched up in the center or many stars with very elongated orbits," Noyola explained. "The normal evolution of a star cluster like Omega Centauri should not end up with stars behaving in those ways. But even if we assume that either scenario did happen somehow, both configurations are expected to be very short lived. A clump of burned-out stars, for example, are expected to move farther away from the center quickly. The stars with elongated orbits are expected to become circular very quickly."

Many astronomers regard Omega Centauri as an unusual globular cluster because of its enormous size and mass. In fact, the 12 billion year old cluster has long been suspected of being the stripped-down core of a dwarf galaxy that had been shredded of most of its stars long ago. A previous Hubble survey of supermassive black holes and their host galaxies showed a correlation between the mass of a black hole and that of its host. Astronomers estimated that the mass of the suspected Omega Centauri dwarf galaxy was roughly 10 million solar masses. If lower-mass galaxies obey the same rule, then the mass of Omega Centauri does match that of its black hole.

Noyola and Gebhardt will use the European Southern Observatory's Very Large Telescope in Paranal, Chile to conduct follow-up observations of the velocity of the stars near the cluster's center to confirm the discovery.

The finding appeared in the April 1 issue of The Astrophysical Journal.

CONTACT
Ray Villard
Space Telescope Science Institute, Baltimore, Md.
410-338-4514
villard@stsci.edu

Peter Michaud
Gemini Observatory, Hilo, Hawaii
808-974-2510
pmichaud@gemini.edu

Lars Lindberg Christensen
Hubble/ESA, Garching, Germany
011-49-89-3200-6306
lars@eso.org

Eva Noyola
Max-Planck Institute for Extraterrestrial Physics, Garching/University of Texas, Austin, Texas
011-49-89-30000-3890
noyola@mpe.mpg.de

Karl Gebhardt
University of Texas, Austin, Texas
512-471-1473
gebhardt@astro.as.utexas.edu

Source: HubbleSite - Newsdesk

Starry Splendor in Core of Omega Centauri

News Release Number: STScI-2008-14



ABOUT THIS IMAGE:
The core of the spectacular globular cluster Omega Centauri glitters with the combined light of 2 million stars. The entire cluster contains 10 million stars, and is among the biggest and most massive of some 200 globular clusters orbiting the Milky Way Galaxy. Omega Centauri lies 17,000 light-years from Earth.

Astronomers Eva Noyola, of the Max-Planck Institute of Extraterrestrial Physics in Garching, Germany, and Karl Gebhardt of the University of Texas at Austin, have reported on the possible detection of an intermediate-mass black hole in the core of Omega Centauri.

The result is primarily based on spectroscopic measurements obtained with the Gemini South observatory in Chile which suggest the stars are moving around the central core of the cluster at higher than expected velocities.

Among the possible explanations for these speedy stars — and the one favored by their study — is that an intermediate-mass black hole of approximately 40,000 solar masses resides at the center of Omega Centauri. Its powerful gravitational field speeds up the motions of stars near the core.

Astronomers have speculated for years that some globular clusters may harbor in their centers medium-size, or intermediate-mass, black holes with masses of some tens of thousands of suns. Medium-size black holes are much less massive than the supermassive black holes, which are up to billions of solar masses and reside in the centers of large galaxies.

Hubble images taken with the Advanced Camera for Surveys were used in key areas in support of this study: to help pinpoint the center of the cluster, as well as to measure the amount of starlight at the cluster center.

Using the European Southern Observatory's Very Large Telescope in Paranal, Chile, Noyola and Gebhardt are planning to obtain follow-up observations to help confirm the existence of an intermediate-mass black hole.

The Hubble images were taken in June 2002.

Object Name: NGC 2371

Image Type: Astronomical

Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

Acknowledgment: A. Cool (San Francisco State University) and J. Anderson (STScI)

Source: HubbleSite - Newsdesk

GSFC Release

For Release: April 16, 2008



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 we 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.

Robert Naeye / Rob Gutro
Goddard Space Flight Center,
Greenbelt, Md.
301-286-4453 / 4044

Additional information and images are available at:


Source: Chandra - Press Room

The Penn State University, Eberly College of Science press release is reproduced below:

14 May 2008—Physicists at Penn State have provided a mechanism by which information can be recovered from black holes, those regions of space where gravity is so strong that, according to Einstein's theory of general relativity, not even light can escape. The team's findings pave the way toward ending a decades-long debate sparked by renowned physicist Stephen Hawking. The team's work will be published in the 20 May 2008 issue of the journal Physical Review Letters.

Click on image for high-resolution file.

Credit: ESA / V. Beckmann (NASA-GSFC)
An artist's depiction of the accretion of a thick
ring of dust into a supermassive black hole.
The accretion produces jets of gamma rays and
X-rays.

n the 1970s, Hawking showed that black holes evaporate by quantum processes; however, he asserted that information, such as the identity of matter that is gobbled up by black holes, is still permanently lost. At the time, Hawking's assertion threatened to turn quantum mechanics--the most successful physical theory posited by humankind--on its head, since a fundamental tenet of the theory is that information cannot be lost.

Hawking's idea was generally accepted by physicists until the late 1990s, when many began to doubt the assertion. Even Hawking himself renounced the idea in 2004. Yet no one, until now, has been able to provide a plausible mechanism for how information might escape from a black hole. A team of physicists led by Abhay Ashtekar, Holder of the Eberly Family Chair in Physics and director of the Penn State Institute for Gravitation and the Cosmos, has discovered such a mechanism. Broadly, their findings expand space-time beyond its assumed size, thus providing room for information to reappear.

To explain the issue, Ashtekar used an analogy from Alice in Wonderland. "When the Cheshire cat disappears, his grin remains," he said. "We used to think it was the same way with black holes. Hawking's analysis suggested that at the end of a black hole's life, even after it has completely evaporated away, a singularity--or a final edge to space-time--is left behind, and this singularity serves as a sink for unrecoverable information."

But Ashtekar and his collaborators, Victor Taveras, a graduate student in the Penn State Department of Physics, and Madhavan Varadarajan, a professor at the Raman Research Institute in India, suggest that singularities do not exist in the real world. "Information only appears to be lost because we have been looking at a restricted part of the true quantum mechanical space-time," said Varadarajan. "Once you consider quantum gravity, then space-time becomes much larger and there is room for information to reappear in the distant future on the other side of what was first thought to be the end of space-time."

According to Ashtekar, space-time is not a continuum as physicists once believed. Instead, it is made up of individual building blocks, just as a piece of fabric, though it appears to be continuous, is made up of individual threads. "Once we realized that the notion of space-time as a continuum is only an approximation of reality, it became clear to us that singularities are merely artifacts of our insistence that space-time should be described as a continuum."

To conduct their studies, the team used two-dimensional black holes to investigate the quantum nature of real black holes, which exist in four dimensions. That's because two-dimensional systems are simpler mathematically to study. But because of the close similarities between two-dimensional black holes and spherical four-dimensional black holes, the team believes that this is a general mechanism that can be applied in four-dimensions. The group is pursuing methods for directly studying four-dimensional black holes.

This work was funded by the National Science Foundation and the Penn State Eberly College of Science.



CONTACTS:
Abhay Ashtekar: (+1) 814-863-9601, ashtekar@gravity.psu.edu
Barbara Kennedy (PIO): (+1) 814-863-4682, science@psu.edu

Source: PSU Press Release