Posted on by Ray Sanders

Can “Warp Speed” Planets Zoom Through Interstellar Space?

Artist’s conception of a runaway planet zooming through interstellar space. A glowing volcano on the planet’s surface hints at active plate tectonics that may keep the planet warm. Image Credit: David A. Aguilar (CfA)

[/caption]Nearly ten years ago, astronomers were stunned to discover a star that had been apparently flung from its own system and travelling at over a million kilometers per hour. Over the years, a question was brought up: If stars can be ejected at a high velocity, what about planets?

Avi Loeb (Harvard-Smithsonian Center for Astrophysics) states, “These warp-speed planets would be some of the fastest objects in our Galaxy. If you lived on one of them, you’d be in for a wild ride from the center of the galaxy to the Universe at large.”

Idan Ginsburg (Dartmouth College) adds, “Other than subatomic particles, I don’t know of anything leaving our galaxy as fast as these runaway planets.”

The mechanics responsible for the super-fast planets are similar to those responsible for “hypervelocity” stars. With stars, if a binary system drifts too closely to a supermassive black hole (such as the ones in the center of galaxies), the gravitational forces can separate the stars – sending one outward at incredible speeds, and the other in orbit around the black hole. Interestingly enough, “Warp Speed” planets can theoretically travel at a few percent of the speed of light – not quite as fast as Star Trek’s Enterprise, but you get the point.

The team, which includes Loeb and Ginsburg, created computer models to simulate the outcome if each star had planets orbiting it. The outcome of the model showed that the star shot into interstellar space would keep its planets, but the star “captured” into orbit around the black hole would have its planets stripped and sent outward at incredible speeds. Typical speeds for the planets range from 11-16 million kilometers per hour, but given the proper conditions could approach even higher velocities.

As of now, it’s impossible for astronomers to detect a wandering planet due to their small size, distance, and rarity. By detecting the dimming of light levels from a hypervelocity star as an orbiting planet crosses its face, astronomers could detect planets that orbit said star.

Ginsburg added, “With one-in-two odds of seeing a transit, if a hypervelocity star had a planet, it makes a lot of sense to watch for them.”

Loeb concluded with, “Travel agencies advertising journeys on hypervelocity planets might appeal to particularly adventurous individuals.”

If you’d like to learn more about hypervelocity planets, you can access a draft version of the upcoming paper at: http://arxiv.org/abs/1201.1446

Source(s): Harvard-Smithsonian Center for Astrophysics , Hypervelocity Planets and Transits Around Hypervelocity Stars

Posted on by Tammy Plotner

To The Extreme… NASA’s Fermi Gamma-Ray Telescope Gathers In High Energy

This all-sky Fermi view includes only sources with energies greater than 10 GeV. From some of these sources, Fermi's LAT detects only one gamma-ray photon every four months. Brighter colors indicate brighter gamma-ray sources. Credit: NASA/DOE/Fermi LAT Collaboration

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It scans the entire visible sky every three hours. Its job is to gather light – but not just any light. What’s visible to our eyes averages about 2 and 3 electron volts, but NASA’s Fermi Gamma-Ray Space Telescope is taking a deep look into a higher realm… the electromagnetic range. Here the energy doesn’t need a boost. It slams out gamma-rays with energies ranging from 20 million to more than 300 billion electron volts (GeV). After three years of space time, the Fermi Large Area Telescope (LAT) has produced its first census of these extreme energy sources.

Over its current operating time, Fermi has continued to paint an ever-deepening portrait of the gamma-ray sky. Even with the huge amount of data which pours in over its 180 minute window, high energy events are not common. When it comes to sources above 10 GeV, even Fermi’s LAT detects only one source about three times a year.

“Before Fermi, we knew of only four discrete sources above 10 GeV, all of them pulsars,” said David Thompson, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Md. “With the LAT, we’ve found hundreds, and we’re showing for the first time just how diverse the sky is at these high energies.”

Just what exactly is out there which can produce such a powerful process? When it comes to gamma-rays, more than half of Fermi’s nearly 500 findings are active galaxies where matter falling into their central supermassive black holes produces intense jets spewing out at close to light speed. A small portion – around 10% – of the census belongs to sources within the Milky Way. These are pulsars, supernova debris and a handful of binary systems which house massive stars. What’s really interesting is the portion of totally unidentifiable sources that constitute about a third of the findings. They simply don’t have any spectroscopic counterparts and astronomers are hoping that these higher energy sources will give them new material to compare their findings against.

New sources emerge and old sources fade as the LAT's view extends into higher energies. Credit: NASA/DOE/Fermi LAT Collaboration and A. Neronov et al.

When it comes to light – obey the rules. Just as we understand that sources of infra-red light fade away when viewed in the ultra-violet, gamma-ray sources above 1 GeV can disappear without a trace when viewed at higher, or “harder,” energies. “One example is the well-known radio galaxy NGC 1275, which is a bright, isolated source below 10 GeV.” says the Fermi team. ” At higher energies it fades appreciably and another nearby source begins to appear. Above 100 GeV, NGC 1275 becomes undetectable by Fermi, while the new source, the radio galaxy IC 310, shines brightly.” The Fermi hard-source list is the product of an international team led by Pascal Fortin at the Ecole Polytechnique’s Laboratoire Leprince-Ringuet in Palaiseau, France, and David Paneque at the Max Planck Institute for Physics in Munich.

More than half of the sources above 10 GeV are black-hole-powered active galaxies. More than a third of the sources are completely unknown, having no identified counterpart detected in other parts of the spectrum. Credit: NASA's Goddard Space Flight Center

The new Fermi census will be a unique source of comparative information to assist ground-based facilities called Atmospheric Cherenkov Telescopes. These sources have confirmed 130 gamma-ray sources with energies above 100 GeV. They include the Major Atmospheric Gamma Imaging Cherenkov telescope (MAGIC) on La Palma in the Canary Islands, the Very Energetic Radiation Imaging Telescope Array System (VERITAS) in Arizona, and the High Energy Stereoscopic System (H.E.S.S.) in Namibia.

“Our catalog will have a significant impact on ground-based facilities’ work by pointing them to the most likely places to find gamma-ray sources emitting above 100 GeV,” Paneque said.

But big ground-based telescopes have big limitations. In this case, their field of view is very constricted and they can’t operate during daylight hours, full Moon or bad weather. But don’t count them out.

“As Fermi’s exposure constantly improves our view of hard sources, ground-based telescopes are becoming more sensitive to lower-energy gamma rays, allowing us to bridge these two energy regimes,” Fortin added.

Original Story Source: NASA Fermi News Release. For Further Reading: Major Atmospheric Gamma Imaging Cherenkov telescope (MAGIC) on La Palma in the Canary Islands, Very Energetic Radiation Imaging Telescope Array System (VERITAS) in Arizona and High Energy Stereoscopic System (H.E.S.S.) in Namibia. For Further Images: Fermi Images.

Posted on by Tammy Plotner

NASA’s Rossi X-Ray Timing Explorer Retires

Technicians work on RXTE in 1995. Credit: NASA/Goddard

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For more than 16 years, 2,200 papers in refereed journals, 92 doctoral theses, and more than 1,000 rapid notifications alerting astronomers around the globe to new astronomical activity, the NASA Rossi X-Ray Timing Explorer is now retired. It sent the last of its data on January 4th of this year and on January 5th the plucky little satellite was decommissioned. If you’re not familiar with Rossi’s activities, then picture sending back images and data on the extreme environments around white dwarfs, neutron stars and black holes… because that’s what made the mission famous.

On December 30, 1995, the mission was launched as XTE from Cape Canaveral, Florida on board a Delta II 7920 rocket. Within weeks it was named in honor of Bruno Rossi, an MIT astronomer and a pioneer of X-ray astronomy and space plasma physics who died in 1993. However, the mission itself didn’t die – it excelled with honors. The entire scientific community recognized the importance of RXTE research and bestowed it with five awards – four Rossi Prizes (1999, 2003, 2006 and 2009) from the High Energy Astrophysics Division of the AAS and the 2004 NWO Spinoza prize, the highest Dutch science award, from the Netherlands Organization for Scientific Research.

On board, the Rossi was three scientific instruments housed in one unit. The first was the Proportional Counter Array (PCA), which was centered on the lower end of the energy band and was crafted by Goddard. The second instrument was the High Energy X-Ray Timing Experiment (HEXTE) that could be aimed at very specific targets and was manufactured by the University of California at San Diego for exploring the upper energy range. The last of the trio was the All-Sky Monitor developed by the Massachusetts Institute of Technology (MIT) in Cambridge. It took in about 80% of the sky during each orbit, delivering astronomers with an unprecedented amount of data on the wide variances of X-Ray sky and allowing them to record bright sources over a period of time as short as a few microseconds up to months. All of this information was taken in over a broad span of energy ranging from 2,000 to 250,000 electron volts.

The Rossi X-Ray Timing Explorer asked little and returned much. Over its operating lifetime it gave us new insight in the life cycles of neutron stars and black holes. Through its eyes we learned about magnetars and discovered the first accreting millisecond pulsar. But that’s not all. The RXTE provided hard evidence which supported Einstein’s theory by observing “frame dragging” in the neighborhood of a black hole. Even though the instrumentation would be considered antique by today’s standards, it certainly served its purpose. “The spacecraft and its instruments had been showing their age, and in the end RXTE had accomplished everything we put it up there to do, and much more,” said Tod Strohmayer, RXTE project scientist at Goddard.

According to the NASA news release, the decision to decommission RXTE followed the recommendations of a 2010 review board tasked to evaluate and rank each of NASA’s operating astrophysics missions. The three and a half ton satellite is expected to return to Earth sometime between the years 2014 and 2023, depending on solar activity. It will have a fiery end… burning out like the superstar that it was. To celebrate its career, the scientific community will hold a special session on RXTE during the 219th meeting of the American Astronomical Society (AAS) in Austin, Texas. The session is scheduled for Tuesday, January 10, at 3 p.m. CST. A press conference on new RXTE results will also be held at the meeting on January 10 at 1:45 p.m. EST. The decision to decommission RXTE followed the recommendations of a 2010 review board tasked to evaluate and rank each of NASA’s operating astrophysics missions. “After two days we listened to verify that none of the systems we turned off had autonomously re-activated, and we’ve heard nothing,” said Deborah Knapp, RXTE mission director at Goddard.

On the contrary… We heard a lot from Rossi!

Original Story Source: NASA News Release.

Posted on by Ray Sanders

Looking at Early Black Holes with a ‘Time Machine’

The large scale cosmological mass distribution in the simulation volume of the MassiveBlack. The projected gas density over the whole volume ('unwrapped' into 2D) is shown in the large scale (background) image. The two images on top show two zoom-in of increasing factor of 10, of the regions where the most massive black hole - the first quasars - is formed. The black hole is at the center of the image and is being fed by cold gas streams. Image Courtesy of Yu Feng.

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What fed early black holes enabling their very rapid growth? A new discovery made by researchers at Carnegie Mellon University using a combination of supercomputer simulations and GigaPan Time Machine technology shows that a diet of cosmic “fast food” (thin streams of cold gas) flowed uncontrollably into the center of the first black holes, causing them to be “supersized” and grow faster than anything else in the Universe.

When our Universe was young, less than a billion years after the Big Bang, galaxies were just beginning to form and grow. According to prior theories, black holes at that time should have been equally small. Data from the Sloan Digital Sky Survey has shown evidence to the contrary – supermassive black holes were in existence as early as 700 million years after the Big Bang.

“The Sloan Digital Sky Survey found supermassive black holes at less than 1 billion years. They were the same size as today’s most massive black holes, which are 13.6 billion years old,” said Tiziana Di Matteo, associate professor of physics (Carnegie Mellon University). “It was a puzzle. Why do some black holes form so early when it takes the whole age of the Universe for others to reach the same mass?”

Supermassive black holes are the largest black holes in existence – weighing in with masses billions of times that of the Sun. Most “normal” black holes are only about 30 times more massive than the Sun. The currently accepted mechanism for the formation of supermassive black holes is through galactic mergers. One problem with this theory and how it applies to early supermassive black holes is that in early Universe, there weren’t many galaxies, and they were too distant from each other to merge.

Rupert Croft, associate professor of physics (Carnegie Mellon University) remarked, “If you write the equations for how galaxies and black holes form, it doesn’t seem possible that these huge masses could form that early, But we look to the sky and there they are.”

In an effort to understand the processes that formed the early supermassive black holes, Di Matteo, Croft and Khandai created MassiveBlack – the largest cosmological simulation to date. The purpose of MassiveBlack is to accurately simulate the first billion years of our universe. Describing MassiveBlack, Di Matteo remarked, “This simulation is truly gigantic. It’s the largest in terms of the level of physics and the actual volume. We did that because we were interested in looking at rare things in the universe, like the first black holes. Because they are so rare, you need to search over a large volume of space”.

Croft and the team started the simulations using known models of cosmology based on theories and laws of modern day physics. “We didn’t put anything crazy in. There’s no magic physics, no extra stuff. It’s the same physics that forms galaxies in simulations of the later universe,” said Croft. “But magically, these early quasars, just as had been observed, appear. We didn’t know they were going to show up. It was amazing to measure their masses and go ‘Wow! These are the exact right size and show up exactly at the right point in time.’ It’s a success story for the modern theory of cosmology.”

The data from MassiveBlack was added to the GigaPan Time Machine project. By combining the MassiveBlack data with the GigaPan Time Machine project, researchers were able to view the simulation as if it was a movie – easily panning across the simulated universe as it formed. When the team noticed events which appeared interesting, they were also able to zoom in to view the events in greater detail than what they could see in our own universe with ground or space-based telescopes.

When the team zoomed in on the creation of the first supermassive black holes, they saw something unexpected. Normal observations show that when cold gas flows toward a black hole it is heated from collisions with other nearby gas molecules, then cools down before entering the black hole. Known as ‘shock heating’, the process should have stopped early black holes from reaching the masses observed. Instead, the team observed thin streams of cold dense gas flowing along ‘filaments’ seen in large-scale surveys that reveal the structure of our universe. The filaments allowed the gas to flow directly into the center of the black holes at incredible speed, providing them with cold, fast food. The steady, but uncontrolled consumption provided a mechanism for the black holes to grow at a much faster rate than their host galaxies.

The findings will be published in the Astrophysical Journal Letters.

If you’d like to read more, check out the papers below ( via Physics arXiv ):
Terapixel Imaging of Cosmological Simulations
The Formation of Galaxies Hosting z~6 Quasars
Early Black Holes in Cosmological Simulations
Cold Flows and the First Quasars

Learn more about Gigapan and MassiveBlack at: http://gigapan.org/gigapans/76215/ and http://www.psc.edu/science/2011/supermassive/

Source: Carnegie Mellon University Press Release

Posted on by Gemma Lavender

Astronomers Complete the Puzzle of Black Hole Description

The optical image on the left, from the Digitized Sky Survey, shows Cygnus X-1 outlined in a red box located near large active regions of star formation in the Milky Way that spans 700 light-years across. An artist’s illustration on the right depicts what astronomers believe is happening within the Cygnus X-1 system with the black hole pulling material from a massive, blue companion star. This material forms a disk (shown in red and orange) that rotates around the black hole before falling into it or being directed away in the form of powerful jets. Credit: X-ray: NASA/CXC; Optical: Digitized Sky Survey.

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Light may not be able to escape a black hole, but now enough information has escaped one black hole’s clutches that astronomers have, for the first time, been able to provide a complete description of it. A team of astronomers from the Harvard-Smithsonian Center for Astrophysics (CfA) and San Diego State University have made the most accurate measurements ever of X-ray binary system Cygnus X-1, allowing them to unravel the longstanding mysteries of its black hole and to retrace its history since its birth around six million years ago.

Cygnus X-1, which consists of a black hole that is drawing material from its massive blue companion star, was found to be emitting powerful X-rays nearly half a century ago. Since its discovery in 1964, this galactic X-ray source has been intensely scrutinized with astronomers attempting to gain information about its mass and spin. But without an accurate measurement of its distance from the Earth, which has been estimated to be between 5,800 and 7,800 light-years, we could only imagine what secrets Cygnus X-1 was harboring.

Astronomer Mark Reid of CfA led his team to garner the most accurate measurement of the distance to Cygnus X-1 with the help of the National Science Foundation’s Very Long Baseline Array (VLBA), a continent-wide radio-telescope system. The team locked down a direct trigonometric measurement of 6,070 light-years.

“Because no other information can escape a black hole, knowing its mass, spin and electrical charge gives a complete description of it,” says Reid who is a co-author of three papers on Cygnus X-1, published in the Astrophysical Journal Letters (available here, here, and here). “The charge of this black hole is nearly zero, so measuring its mass and spin make our description complete.”

Using their new precise distance measurement along with the Chandra X-ray Observatory, the Rossi X-ray Timing Explorer, the Advanced Satellite for Cosmology and Astrophysics and visible-light observations made over more than two decades, the team pieced together the “No Hair” theorem – the complete description that Reid speaks of – by revealing a hefty mass of nearly 15 solar masses and a turbo spin speed of 800 revolutions per second. “We now know that Cygnus X-1 is one of the most massive stellar black holes in the Milky Way,” says Jerry Orosz of San Diego State University, also an author of the paper with Reid and Lijun Gou of the CfA. “It’s spinning as fast as any black hole we’ve ever seen.”

As an added bonus, observations using the VLBA back in 2009 and 2010 had also measured Cygnus X-1’s movement through the galaxy leading scientists to the conclusion that it is much too slow to have been produced by the explosion of a supernova and without evidence of a large “kick” at birth, astronomers believe that it may have resulted from the dark collapse of a progenitor star with a mass greater than about 100 times the mass of the Sun that got lost in a vigorous stellar wind. “There are suggestions that this black hole could have formed without a supernova explosion and our results support those suggestions,” says Reid.

It seems that with these measurements, Professor Stephen Hawking has well and truly had to eat his own words after placing a bet with fellow astrophysicist Kip Thorne, a professor of theoretical physics at the California Institute of Technology, that Cygnus X-1 did not contain a black hole.

“For forty years, Cygnus X-1 has been the iconic example of a black hole. However, despite Hawking’s concession, I have never been completely convinced that it really does contain a black hole – until now,” says Thorne. “The data and modeling in these three papers at last provide a completely definitive description of this binary system.”

Sources: CfA

Posted on by Ray Sanders

Are Black Holes Planet Smashers?

Light echo of dust illuminated by nearby star V838 Monocerotis as it became 600,000 times more luminous than our Sun in January 2002. Credit: NASA/ESA

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Some supermassive black holes are obscured by oddly shaped dust clouds which resemble doughnuts. These clouds have been an unsolved puzzle, but last week a scientist at the University of Leicester proposed a new theory to explain the origins of these clouds, saying that they could be the results of high-speed collisions between planets and asteroids in the central region of galaxies, where the supermassive black holes reside.

While black holes are a death knell for any objects wandering too close, this may mean even planets in a region nearby a black hole are doomed — but not because they would be sucked in. The central regions of galaxies just may be mayhem for planets.

“Too bad for life on these planets, ” said Dr. Sergei Nayakshin, whose paper will be published in the Monthly Notices of the Royal Astronomical Society journal.

In the center of nearly all galaxies are supermassive black holes. Previous studies show that about half of supermassive black holes are obscured by dust clouds.

Nayakshin and his team found inspiration for their new theory from our Solar System, and based their theory on the zodiacal dust which is known to originate from collisions between solid bodies such as asteroids and comets.

The central point of Nayakshin’s theory is that not only are black holes present in the central region of a galaxy, but stars, planets and asteroids as well.

The team’s theory asserts that any collisions between planets and asteroids in the central region of a galaxy would occur at speeds of up to 1000 km/sec. Given the tremendous speeds and energy present in such collisions, eventually rocky objects would be pulverized into microscopic dust grains.

Nayakshin also mentioned that the central region of a galaxy is an extremely harsh environment, given high amounts of deadly radiation and frequent collisions, both of which would make any planets near a supermassive black hole inhospitable well before they were destroyed in any collisions.

While Nayakshin said the frequent collisions would be bad news for any life that may exist on the planets, he added, “On the other hand the dust created in this way blocks much of the harmful radiation from reaching the rest of the host galaxy. This in turn may make it easier for life to prosper elsewhere in the rest of the central region of the galaxy.”

Nayakshin believes that a greater understanding of the origins of the dust near black holes is important to better understand how black holes grow and affect their host galaxy, and concluded with, “We suspect that the supermassive black hole in our own Galaxy, the Milky Way, expelled most of the gas that would otherwise turn into more stars and planets. Understanding the origin of the dust in the inner regions of galaxies would take us one step closer to solving the mystery of the supermassive black holes.”

Source: University of Leicester Press Release

Posted on by Jon Voisey

Missing Black Holes

Artists concept of a black hole.

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As astronomers began working out how stars die, they expected that the mass of remnants, whether white dwarfs, neutron stars, or black holes, should be essentially continuous. In other words, there should be a smooth distribution of remnant masses from a fraction of a solar mass, up to nearly 100 times the mass of the sun. Yet observations have shown a distinct lack of objects at the borderline of neutron stars and black holes weighing 2-5 solar masses. So where have they all gone and what might this imply about the explosions that create such objects?

The gap was first noted in 1998 and was originally attributed to a lack of observations of black holes at the time. But in the past 13 years, the gap has held up.

In an attempt to explain this, a new study has been conducted by a team of astronomers led by Krzystof Belczynski at Warsaw University. Following the recent observations, the team assumed the paucity was not caused by a lack of observations or selection effect, but rather, there simply weren’t many objects in this mass range.

Instead, the team looked at the engines of supernovae that would create such objects. Stars less than ~20 solar masses are expected to explode into supernovae, leaving behind neutron stars, while ones greater than 40 solar masses should collapse directly into black holes with little to no fanfare. Stars between these ranges were expected to fill this gap of 2-5 solar mass remnants.

The new study proposes that the gap is created by a fickle switch in the supernova explosion process. In general, supernovae occur when the cores are filled with iron which can no longer create energy through fusion. When this happens, the pressure supporting the star’s mass disappears and the outer layers collapse onto the immensely dense core. This creates a shockwave which is reflected by the core and rushes outwards, slamming into more collapsing material and creates a stalemate, where the outwards pressure balances the infalling material. For the supernova to proceed, that outwards shockwave needs an extra boost.

While astronomers disagree on exactly what might cause this revitalization, some suggest that it is generated as the core, superheated to hundreds of billions of degrees, emits neutrinos. Under normal densities, these particles travel right past most matter, but in the superdense regions inside the supernova, many are captured, reheating the material and driving the shockwave back out to create the event we observe as a supernova.

Regardless of what causes it, the team suggests that this point is critical for the final mass of the object. If it explodes, much of the mass of the progenitor will be lost, pushing it towards a neutron star. If it fails to push outwards, the material collapses and enters the event horizon, piling on mass and driving the final mass upwards. It’s an all or nothing moment.

And moment is a good description of how fast this occurs. At most, astronomers suggest that this interplay between the outwards shock and the inwards collapse takes a single second. Other models place the timescale at a tenth of a second. The new study notes that the more quickly the decision takes place, the more pronounced the gap is in the resulting objects. As such, the fact that the gap exists may be taken as evidence for this being a split second decision.

Posted on by Nancy Atkinson

More Details on the Black Hole that Swallowed a Screaming Star

Images from Swift's Ultraviolet/Optical (white, purple) and X-Ray telescopes (yellow and red) were combined to make this view of Swift J1644+57. Evidence of the flares is seen only in the X-ray image, which is a 3.4-hour exposure taken on March 28, 2011. Credit: NASA/Swift/Stefan Immler

Back in June we reported on the black hole that devoured a star and then hurled the x-ray energy across billions of light years, right at Earth. It was such a spectacular and unprecedented event, that more studies have been done on the source, known as Swift J1644+57, and the folks at the Goddard Space Flight Center mulitmedia team have produced an animation (above) of what the event may have looked like. Two new papers were published yesterday in Nature; one from a group at NASA studying the data from the Swift satellite and the Japanese Monitor of All-sky X-ray Image (MAXI) instrument aboard the International Space Station, and the other from scientists using ground-based observatories.

They have confirmed what happened was the result of a truly extraordinary event — the awakening of a distant galaxy’s dormant black hole as it shredded, sucked and consumed a star, and the X-ray burst was akin to the death screams of the star.

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In the new studies, detailed analysis of MAXI and Swift observations revealed this was the first time that a nucleus with no previous X-ray emission had ever suddenly started such activity. The strong X-ray and rapid variation indicated that the X-ray came from a jet that was pointed right at Earth.

“Incredibly, this source is still producing X-rays and may remain bright enough for Swift to observe into next year,” said David Burrows, professor of astronomy at Penn State University and lead scientist for Swift’s X-Ray Telescope instrument. “It behaves unlike anything we’ve seen before.”

The galaxy is so far away, it took the light from the event approximately 3.9 billion years to reach Earth (that distance was updated from the 3.8 billion light years reported in June).

The black hole in the galaxy hosting Swift J1644+57, located in the constellation Draco, may be twice the mass of the four-million-solar-mass black hole in the center of the Milky Way galaxy. As a star falls toward a black hole, it is ripped apart by intense tides. The gas is corralled into a disk that swirls around the black hole and becomes rapidly heated to temperatures of millions of degrees.

The innermost gas in the disk spirals toward the black hole, where rapid motion and magnetism create dual, oppositely directed “funnels” through which some particles may escape. Jets driving matter at velocities greater than 90 percent the speed of light form along the black hole’s spin axis.

This illustration steps through the events that scientists think likely resulted in Swift J1644+57. Credit: NASA/Goddard Space Flight Center/Swift

The Swift satellite detected flares from this region back on March 28, 2011, and the flares were initially assumed to signal a gamma-ray burst, one of the nearly daily short blasts of high-energy radiation often associated with the death of a massive star and the birth of a black hole in the distant universe. But as the emission continued to brighten and flare, astronomers realized that the most plausible explanation was the tidal disruption of a sun-like star seen as beamed emission.

“The radio emission occurs when the outgoing jet slams into the interstellar environment, and by contrast, the X-rays arise much closer to the black hole, likely near the base of the jet,” said Ashley Zauderer, from the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass, lead author of a study of the event from numerous ground-based radio observatories, including the National Radio Astronomy Observatory’s Expanded Very Large Array (EVLA) near Socorro, N.M.

“Our observations show that the radio-emitting region is still expanding at more than half the speed of light,” said Edo Berger, an associate professor of astrophysics at Harvard and a coauthor of the radio paper. “By tracking this expansion backward in time, we can confirm that the outflow formed at the same time as the Swift X-ray source.”

Swift launched in November 2004 and MAXI is mounted on the Japanese Kibo module on the ISS (installed in July 2009) and has been monitoring the whole sky since August 2009.

See more images and animations at the Goddard Space Flight Center Multimedia page.

Sources: Nature, JAXA, NASA

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

Nearby Galaxy Has Two Monster Black Holes

Viewed in visible light, Markarian 739 resembles a smiling face. Inside are two supermassive black holes, separated by about 11,000 light-years. The galaxy is 425 million light-years away from Earth. Credit: Sloan Digital Sky Survey

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Why does this galaxy appear to be smiling? The answer might be because it has been holding a secret that astrophysicists have only now just uncovered: there are two — count ‘em – two gigantic black holes inside this nearby galaxy, named Markarian 739 (or NGC 3758), and both are very active. While massive black holes are common, only about one percent of them are considered as active and powerful – called active galactic nuclei (AGN). Binary AGN are rarer still: Markarian 739 is only the second identified within half a billion light-years from Earth.

Markarian 739 is actually a pair of merging galaxies. For decades, astronomers have known that the eastern nucleus of Markarian 739 contains a black hole that is actively accreting matter and generating an exceptional amount of energy. Now, data from the Swift satellite along with the Chandra X-ray Observatory Swift has revealed an AGN in the western half as well. This makes the galaxy one of the nearest and clearest cases of a binary AGN.

The galaxy is 425 million light-years away from Earth.

How did the second AGN remain hidden for so long? “Markarian 739 West shows no evidence of being an AGN in visible, ultraviolet and radio observations,” said Sylvain Veilleux, a professor of astronomy at University of Maryland in College Park , and a coauthor of a new paper published in Astrophysical Journal Letters. “This highlights the critical importance of high-resolution observations at high X-ray energies in locating binary AGN.”

Since 2004, the Burst Alert Telescope (BAT) aboard Swift has been mapping high-energy X-ray sources all around the sky. The survey is sensitive to AGN up to 650 million light-years away and has uncovered dozens of previously unrecognized systems.

Michael Koss, the lead author of this study, from NASA’s Goddard Space Flight Center and UMCP, did follow-up studies of the BAT mapping and he and his colleagues published a paper in 2010 that revealed that about a quarter of the Swift BAT AGN were either interacting or in close pairs, with perhaps 60 percent of them poised to merge in another billion years.

“If two galaxies collide and each possesses a supermassive black hole, there should be times when both black holes switch on as AGN,” said coauthor Richard Mushotzky, professor of astronomy at UMCP. “We weren’t seeing many double AGN, so we turned to Chandra for help.”

Swift’s BAT instrument is scanning one-tenth of the sky at any given moment, its X-ray survey growing more sensitive every year as its exposure increases. Where Swift’s BAT provided a wide-angle view, the X-ray telescope aboard the Chandra X-ray Observatory acted like a zoom lens and resolved details a hundred times smaller.

The distance separating the two black holes is about 11,000 light-years , or about a third of the distance separating the solar system from the center of our own galaxy. The dual AGN of Markarian 739 is the second-closest known, both in terms of distance from one another and distance from Earth. However, another galaxy known as NGC 6240 holds both records.

Source: Swift Telescope webpage

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