Mysterious Light Originates Near A Galaxy's Black Hole

Mysterious Light Originates Near A Galaxy's Black Hole

Photons with a trillion times more energy than visible light are flying out of a relatively nearby galaxy.

Until now, scientists didn't understand this light's origin, but a new study shows that its source is a giant black hole inside the M87 galaxy.

The radiation takes the form of high-frequency gamma rays.

"We detect it in roughly 25 galaxies so far but we never knew where exactly it was coming from," said study team member Matthias Beilicke, an astrophysicist at Washington University in St. Louis. "Only in the case of M87 were we able to narrow it down to the black hole vicinity."

Matter funnels into the supermassive black hole from a ring of material circling around it and called an accretion disk. Some matter is also propelled out in very bright jets that stream across space.

One hypothesis suggests the gamma-ray flares occur when an extra amount of matter is pulled out of the accretion disk and injected into the jets. Either electrons or protons in the jet could interact with light photons or matter to create the extremely high-energy gamma rays.

"This acceleration mechanism requires strong magnetic fields which can be found around the black hole," Beilicke said. "We need charged particles accelerated to very high energies in order to emit gamma rays at these energies."

The observations could help scientists understand the environment around gigantic black holes like this one, which contains the mass of more than six billion suns.

"The fact that there are particles accelerated up to such high speeds gives us input for the modeling of these systems," Beilicke told SPACE.com. "M87 is so far more or less the only source which really allows this particular kind of study."

The researchers were able to pin down the radiation's origination point by combining measurements of the gamma-rays with radio-wave observations. Even though gamma rays cannot usually pierce through Earth's atmosphere, ground-based telescopes can detect them by looking for telltale flashes of faint blue light that result when gamma rays hit the air. These observations also reflect the direction the gamma rays came from, though they are not very precise.

Astronomers also observed M87 with the National Science Foundation's Very Long Baseline Array (VLBA), a group of radio telescopes spread out around the United States. These observations revealed a burst of radio light that coincided with the gamma-ray flares, which usually lasted a few days.

The radio flares, imaged with much more precision than gamma-ray light, could be traced back to the location of the supermassive black hole in the center of M87.

"Combining the gamma-ray observations with the supersharp radio 'vision' of the VLBA allowed us to see that the gamma rays are coming from a region very near the black hole itself," said team member Craig Walker of the National Radio Astronomy Observatory (NRAO).

M87, at 50 million light-years from Earth, is much closer than any similar gamma-ray flare sources, so it could be scientists best bet to study these systems for a while.

The new study is detailed in the July 2 issue of the journal Science.

Spectacular View.

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Evidence Found for Ancient Mars Lake

Evidence Found for Ancient Mars Lake

Several studies in recent years have claimed evidence for shorelines and other features that suggest ancient lakes on Mars. Firm evidence has remained elusive.

Now a University of Colorado at Boulder research team claims "the first definitive evidence of shorelines on Mars" in a statement released today.

The scientists see signs of "a deep, ancient lake," which would have implications for the potential for past life on Mars. Life as we know it requires water, and while Mars is dry now, if there was abundant water in the past -- as many studies have suggested -- then life would have been a possibility. There is, however, no firm evidence that life does or ever did exist on the red planet.

Researchers estimate the lake existed more than 3 billion years ago. It covered as much as 80 square miles and was up to 1,500 feet deep -- roughly the equivalent of Lake Champlain bordering the United States and Canada, said Gaetano Di Achille, who led the study out of the University of Colorado at Boulder.

The shoreline evidence, found along a broad delta, included a series of alternating ridges and troughs thought to be surviving remnants of beach deposits.

"This is the first unambiguous evidence of shorelines on the surface of Mars," Di Achille said. "The identification of the shorelines and accompanying geological evidence allows us to calculate the size and volume of the lake, which appears to have formed about 3.4 billion years ago."

The findings have been published online in Geophysical Research Letters, a journal of the American Geophysical Union.

Other studies have claimed evidence for lakes on Mars too, however, including one in Holden Crater announced last year.

And several studies have found evidence â€" from possible shorelines to salty deposits indicating the evaporation of water â€" for shallow lakes or oceans. Ancient Mars had abundant water, many lines of evidence indicate.

Images used for the study were taken by the High Resolution Imaging Science Experiment, or HiRISE camera on NASA's Mars Reconnaissance Orbiter.

An analysis of the images indicates water carved a 30-mile-long canyon that opened up into a valley, depositing sediment that formed a large delta, the researchers conclude. This delta and others surrounding the basin imply the existence of a large, long-lived lake, said Hynek, also an assistant professor in CU-Boulder's geological sciences department. The presumed lake bed is located within a much larger valley known as the Shalbatana Vallis.

"Finding shorelines is a Holy Grail of sorts to us," said Brian Hynek, also of CU-Boulder.

In addition, the evidence shows the lake existed during a time when Mars is generally believed to have been cold and dry, which is at odds with current theories proposed by many planetary scientists, he said. "Not only does this research prove there was a long-lived lake system on Mars, but we can see that the lake formed after the warm, wet period is thought to have dissipated."

Further research will be needed to sort out the discrepancies, however.

Planetary scientists think the oldest surfaces on Mars formed during the wet and warm Noachan epoch from about 4.1 billion to 3.7 billion years ago that featured a bombardment of large meteors and extensive flooding. The newly discovered lake is believed to have formed during the Hesperian epoch and postdates the end of the warm and wet period on Mars by 300 million years, according to the study.

The deltas adjacent to the lake are of high interest to planetary scientists because deltas on Earth rapidly bury organic carbon and other biomarkers of life, Hynek said. Most astrobiologists believe any present indications of life on Mars will be discovered in the form of subterranean microorganisms.

But in the past, lakes on Mars would have provided cozy surface habitats rich in nutrients for such microbes, Hynek said.

The retreat of the lake apparently was rapid enough to prevent the formation of additional, lower shorelines, Di Achille said. The lake probably either evaporated or froze over with the ice slowly turning to water vapor and disappearing during a period of abrupt climate change, according to the study.

Di Achille said the newly discovered pristine lake bed and delta deposits would be would be a prime target for a future landing mission to Mars in search of evidence of past life.

"On Earth, deltas and lakes are excellent collectors and preservers of signs of past life," said Di Achille. "If life ever arose on Mars, deltas may be the key to unlocking Mars' biological past."

Pretty interesting discovery indeed.

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NASA heads to moon as panel weighs its future

NASA heads to moon as panel weighs its future

CAPE CANAVERAL, Fla., June 17 (Reuters) - As NASA prepared to launch its debut mission in a program aimed at returning astronauts to the moon, a presidential panel on Wednesday began looking at alternative ways to get there and whether the United States should even go.

The Lunar Reconnaissance Orbiter, scheduled to launch from Cape Canaveral Air Force Station at 5:12 p.m. (2112 GMT) on Thursday, is designed to map the lunar surface so NASA can find safe and scientifically interesting landing spots for future human missions.

The United States is shifting the focus of its human space program from research and technology development in low-Earth orbit with the space shuttle and International Space Station to an exploration initiative. That would culminate in the return of U.S. astronauts to the moon in 2020 -- a half-century after the pioneering Apollo lunar landings of 1969 to 1972.

NASA plans to retire the shuttle fleet in 2010 after eight more missions to complete space station construction. It would then shift funding to ramp up development of a pair of expendable rockets, known as Ares, and a beefed-up Apollo-style capsule called Orion that can ferry crews to the moon and other destinations.

Orion's debut flight to the space station is targeted for 2015 -- five years after the shuttle stops flying.

With costs estimated at more than $100 billion for a lunar excursion and concerns about the five-year gap, President Barack Obama has ordered a top-level review of the U.S. human space program.

Hearings in Washington opened on Wednesday with commercial companies, NASA and other space advocates laying out options for flying astronauts to the space station and getting to the moon.

Panel members will also consider whether the moon should even be a destination. The panel, headed by retired Lockheed Martin Chief Executive Norm Augustine, is expected to issue a report in August.

PROPOSING ALTERNATIVES

At the meeting, United Launch Alliance, a Boeing (BA.N) and Lockheed Martin (LMT.N) joint venture that markets the unmanned Atlas and Delta rockets, pitched an upgraded version of its rockets to replace NASA's planned Ares booster, an option a NASA-backed study found to be less expensive.

But the consultancy that prepared the study cautioned that would only be cheaper if NASA dropped plans for a second Ares rocket, a heavy-lifter that could carry cargo to the moon.

NASA's original plan for the new exploration initiative, known as Constellation, was a complete program that folded together the cost of developing both versions of the Ares rocket, using one as a predecessor for the other.

"When one starts contemplating replacing pieces of that architecture, all kinds of things begin to happen," said Gary Pulliam of The Aerospace Corporation.

Another company, Space Exploration Technologies, known as SpaceX, proposed another alternative to carry crews.

SpaceX founder Elon Musk said his firm's Dragon capsule, already purchased by NASA to haul cargo to the space station, could be used to transport astronauts by adding an escape system and making minor upgrades.

"The whole purpose of SpaceX from the beginning has been human space flight. That's why I created it," said Musk. "Dragon has five windows. You don't need windows for cargo." (Editing by Jane Sutton and Peter Cooney)

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