NASA Chandra Captures Whirlpool Galaxy Sparkling in X-rays

Image courtesy X-ray: NASA/CXC/Wesleyan Univ./R.Kilgard, et al; Optical: NASA/STScI.

Nearly a million seconds of observing time with NASA's Chandra X-ray Observatory has revealed a spiral galaxy similar to the Milky Way glittering with hundreds of X-ray points of light.

The galaxy is officially named Messier 51 (M51) or NGC 5194, but often goes by its nickname of the "Whirlpool Galaxy."

Like the Milky Way, the Whirlpool is a spiral galaxy with spectacular arms of stars and dust.

M51 is located 30 million light years from Earth, and its face-on orientation to Earth gives us a perspective that we can never get of our own spiral galactic home.

By using Chandra, astronomers can peer into the Whirlpool to uncover things that can only be detected in X-rays.

In this new composite image, Chandra data are shown in purple. Optical data from the Hubble Space Telescope are red, green and blue.

Most of the X-ray sources are X-ray binaries (XRBs). These systems consist of pairs of objects where a compact star, either a neutron star or, more rarely, a black hole, is capturing material from an orbiting companion star.

The infalling material is accelerated by the intense gravitational field of the compact star and heated to millions of degrees, producing a luminous X-ray source.

The Chandra observations reveal that at least ten of the XRBs in M51 are bright enough to contain black holes. In eight of these systems the black holes are likely capturing material from companion stars that are much more massive than the sun.

Because astronomers have been observing M51 for about a decade with Chandra, they have critical information about how X-ray sources containing black holes behave over time.

The black holes with massive stellar companions are consistently bright over the ten years of Chandra observations.

These results suggest that the high-mass stars in these X-ray sources also have strong winds that allow for a steady stream of material to flow onto the black hole.

A difference between the Milky Way and the Whirlpool galaxy is that M51 is in the midst of merging with a smaller companion galaxy seen in the upper left of the image. Scientists think this galactic interaction is triggering waves of star formation.

The most massive of the newly formed stars will race through their evolution in a few million years and collapse to form neutron stars or black holes.

Most of the XRBs containing black holes in M51 are located close to regions where stars are forming, showing their connection to the oncoming galactic collision.

Previous studies of the Whirlpool Galaxy with Chandra revealed just over 100 X-ray sources. The new dataset, equivalent to about 900,000 seconds of Chandra observing time, reveals nearly 500 X-ray sources.

About 400 of these sources are thought to be within M51, with the remaining either being in front of or behind the galaxy itself.

Much of the diffuse, or fuzzy, X-ray emission in M51 comes from gas that has been superheated by supernova explosions of massive stars.

Simulations re-create X-rays emerging from the neighbourhood of black holes

Black holes may be dark, but the areas around them definitely are not. These dense, spinning behemoths twist up gas and matter just outside their event horizon, and generate heat and energy that gets radiated, in part, as light and when black holes merge, they produce a bright intergalactic burst that may act as a beacon for their collision.

Karl Schwarzschild

Astrophysicists became deeply interested in black holes in the 1960s, but the idea of their event horizon was first intimated in a paper by Karl Schwarzschild published after Einstein introduced general relativity in 1915.

Knowledge about black holes—these still-unseen objects—has grown tremendously in recent years.

Part of this growth comes from researchers' ability to use detailed numerical models and powerful supercomputers to simulate the complex dynamics near a black hole.

This is no trivial matter. Warped spacetime, gas pressure, ionizing radiation, magnetized plasma—the list of phenomena that must be included in an accurate simulation goes on and on.

Scott Noble

"It's not something that you want to do with a paper and pencil," said Scott Noble, an astrophysicist at the Rochester Institute of Technology (RIT).

Working with Jeremy Schnittman of Goddard Space Flight Center and Julian Krolik of Johns Hopkins University, Noble and his colleagues created a new tool that predicts the light that an accreting black hole would produce.

They did so by modeling how photons hit gas particles in the disk around the black hole (also known as an accretion disk), generating light—specifically light in the X-ray spectrum—and producing signals detected with today's most powerful telescopes.

In their June 2013 paper in the Astrophysical Journal, the researchers presented the results of a new global radiation transport code coupled to a relativistic simulation of an accreting, non-rotating black hole.

For the first time, they were able to re-create and explain nearly all the components seen in the X-ray spectra of stellar-mass black holes.

The ability to generate realistic light signals from a black hole simulation is a first and brings with it the possibility of explaining a whole host of observations taken with multiple X-ray satellites during the past 40 years.

"We felt excited and also incredibly lucky, like we'd turned up ten heads in a row," Noble said. "The simulations are very challenging and if you don't get it just right, it won't give you an accurate answer."

"This was the first time that people have put all of the pieces together from first principles in such a thorough way."

More information: "X-Ray Spectra from Magnetohydrodynamic Simulations of Accreting Black Holes." Jeremy D. Schnittman, Julian H. Krolik, Scott C. Noble. 2013 ApJ 769 156. DOI: 10.1088/0004-637X/769/2/156

Spanish Research: Black hole that doesn't emit x-rays discovered near massive star

Trailed intensity image of the two lines constructed from the phase binned spectra. 

Two orbital cycles are displayed for clarity. 

The colour scale indicates counts normalised to the continuum, with the black colour corresponding to 0.98 and the white colour to 1.08 in Fe II and 1.16 in HeII. 

Credit: Nature 

Researchers in Instituto de Astrofísica de Canarias, Universidad de Alicante, Universitat de Barcelona, and Institut de Ciències de l’Espai (IEEC-CSIC), Spain have discovered a black hole that doesn't reveal itself through x-ray radiation thrown off by material that is being sucked into it.

In their paper published in the journal Nature, team members from several research institutions throughout Spain, report that the black hole appears to exist as a companion (binary) to a massive Be star that spins so fast it's surrounded by a gas disk.

I. Negueruela

Up until now, virtually all black holes have been discovered via x-ray radiation signals—as material is pulled in past the point of no return, radiation is flung out into space where it is noted by space scientists here on Earth.

In this new effort, the research team was able to identify the black hole because of its behaviour, rather than its signature.

Many Be stars have been found to have companions—most of the time they are supernova remnants (neutron stars) but never before has a Be star been found to have a black hole as a companion.

The star, named MWC 656 is really big—approximately 10 to 16 times as massive as our sun. It spins really fast too (approximately 671,000 mph) which the researchers say, explains why the black hole next to it doesn't emit any radiation.

J. Casares

They suggest that because the star is spinning so fast, it casts gas into a disk surrounding its equator which in turn is cast off towards the black hole, but rather than being pulled in, the gas joins an accretion disk that surrounds the "mouth" of the black hole, moving so fast (due to the angular momentum of the gas cast off from the star) that it can't be pulled in. Thus the disk simply continues to grow larger.

The black hole is pretty big too (approximately 3.8 to 6.9 more massive than our sun) which likely puts it in the category of stellar mass black holes—those that come into existence when a star runs out of fuel.

The discovery of the "silent" black hole suggests that many more like it might exist, which will undoubtedly lead researchers to look for more, now that they know what to look for.

More information: A Be-type star with a black-hole companion, Nature 505, 378–381 (16 January 2014) J. Casares, I. Negueruela, M. Ribó, I. Ribas, J. M. Paredes, A. Herrero & S. Simón-Díaz DOI: 10.1038/nature12916

A blast from its past dates the youngest neutron-star binary

The youngest member of an important class of objects in space has been found by a team that includes Penn State Distinguished Professor of Astronomy and Astrophysics Niel Brandt. 

This composite image shows the energies streaming toward Earth from this object -- X-rays in blue and the radio emission in purple.

These energy detections have been overlaid in this image on an optical field of view from the Digitized Sky Survey. 

This discovery allows scientists to study a critical phase after a supernova and the birth of a neutron star. 

Credit: X-ray: NASA/CXC /Univ. of Wisconsin-Madison /S. Heinz et al; Optical: DSS; Radio: CSIRO/ATNF/ATCA

X-rays streaming toward Earth from the region near a neutron star that is cannibalizing its companion star have revealed the pair to be the youngest "X-ray binary" yet known.

The discovery by a team that includes a Penn State astronomer is being published in this week's issue of the The Astrophysical Journal.

The team discovered the age of this record-breaking pair, named Circinus X-1, by using data from NASA's Chandra X-ray Observatory, which revealed faint remnants of the supernova explosion that created the neutron star.

"I have been perplexed by the unusually strong evolution of the orbit of Circinus X-1 since my graduate-school days," said Niel Brandt, Distinguished Professor of Astronomy and Astrophysics.

"The discovery now of this system's youth provides a satisfying explanation for why its orbit evolves so strongly—because the system likely still is settling down after its violent birth."

The research team, which was led by Sebastian Heinz at the University of Wisconsin-Madison, determined that Circinus X-1 is less than 4,600 years old.

"X-ray binaries provide us with opportunities to study matter under extreme conditions that would be impossible to recreate in a laboratory," Heinz said.

"For the first time, we can study a newly minted neutron star in an X-ray binary system."

This is an artist's conception of the life of X-ray binary systems and the young and turbulent history of Circinus X-1, which formed in a supernova explosion less than 4,600 years ago, approximately 500 B.C.E., making it the youngest known X-ray binary. 

Credit: University of Wisconsin-Madison

X-ray binaries are star systems made up of two parts: a compact stellar remnant—either a neutron star or a black hole; and a companion star—a normal star like our Sun.

The new discovery, made in parallel with a radio telescope in Australia, provides scientists with unique insight into the formation of neutron stars and supernovas, and the effect of the supernova's explosion on a nearby companion star.

As the two objects orbit one another, the neutron star or black hole pulls in gas from the companion star, heating the gas to millions of degrees, producing intense X-ray radiation, and making these star systems some of the brightest X-ray sources in the sky.

To determine the age of Circinus X-1, the astronomers needed to examine the material around the orbiting pair of stars.

However, the overwhelming brightness of the neutron star made it too difficult for researchers to observe that interstellar gas.

The team recently caught a break, however, when they observed the neutron star in a very faint state—dim enough for scientists to detect the X-rays from the supernova shock wave that plowed through the surrounding interstellar gas.

Read the full story here

Chandra sees eclipsing planet in X-rays

Using Chandra and XMM-Newton, astronomers have detected an exoplanet passing in front of its parent star for the first time in X-rays. 

The artist's illustration shows HD 189733b, a "hot Jupiter" that goes around its star once every 2.2 days. 

The illustration also reveals the presence of a faint red companion star in the system. 

The new X-ray observations (inset) suggest that HD 189733b has a larger atmosphere than implied by previous optical studies. 

HD 189733b is the closest hot Jupiter to Earth, making it a prime target for astronomers who want to learn more about this type of exoplanet and the atmosphere around it. 

Credit: X-ray: NASA/CXC/SAO/K.Poppenhaeger et al; Illustration: NASA/CXC/M.Weiss

For the first time since exoplanets, or planets around stars other than the sun, were discovered almost 20 years ago, X-ray observations have detected an exoplanet passing in front of its parent star.

An advantageous alignment of a planet and its parent star in the system HD 189733, which is 63 light-years from Earth, enabled NASA's Chandra X-ray Observatory and the European Space Agency's XMM Newton Observatory to observe a dip in X-ray intensity as the planet transited the star.

"Thousands of planet candidates have been seen to transit in only optical light," said Katja Poppenhaeger of Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass., who led a new study to be published in the Aug. 10 edition of the Astrophysical Journal.

"Finally being able to study one in X-rays is important because it reveals new information about the properties of an exoplanet."

The team used Chandra to observe six transits and data from XMM Newton observations of one.

The planet, known as HD 189733b, is a hot Jupiter, meaning it is similar in size to Jupiter in our solar system but in very close orbit around its star. HD 189733b is more than 30 times closer to its star than Earth is to the sun. It orbits the star once every 2.2 days.

HD 189733b is the closest hot Jupiter to Earth, which makes it a prime target for astronomers who want to learn more about this type of exoplanet and the atmosphere around it.

They have used NASA's Kepler space telescope to study it at optical wavelengths, and NASA's Hubble Space Telescope to confirm it is blue in colour as a result of the preferential scattering of blue light by silicate particles in its atmosphere.

The study with Chandra and XMM Newton has revealed clues to the size of the planet's atmosphere. The spacecraft saw light decreasing during the transits. The decrease in X-ray light was three times greater than the corresponding decrease in optical light.

"The X-ray data suggest there are extended layers of the planet's atmosphere that are transparent to optical light but opaque to X-rays," said co-author Jurgen Schmitt of Hamburger Sternwarte in Hamburg, Germany. "However, we need more data to confirm this idea."

The researchers also are learning about how the planet and the star can affect one another.

Astronomers have known for about a decade ultraviolet and X-ray radiation from the main star in HD 189733 are evaporating the atmosphere of HD 189733b over time. The authors estimate it is losing 100 million to 600 million kilograms of mass per second.

HD 189733b's atmosphere appears to be thinning 25 percent to 65 percent faster than it would be if the planet's atmosphere were smaller.

"The extended atmosphere of this planet makes it a bigger target for high-energy radiation from its star, so more evaporation occurs," said co-author Scott Wolk, also of CfA.

Hubble Chandra Image: The Ring Galaxy NGC 922

Credits: X-ray: NASA/CXC/SAO/A. Prestwich et al; Optical: NASA/STScI.

Astronomers are studying the number of black holes in galaxies with different compositions.

One of these galaxies, the ring galaxy NGC 922, is seen in this composite image containing X-rays from NASA's Chandra X-ray Observatory (red) and optical data from the Hubble Space Telescope (pink, yellow and blue).

NGC 922 was formed by the collision between two galaxies - one seen in this image and another located outside the field of view.

This collision triggered the formation of new stars in the shape of a ring. Some of these were massive stars that evolved and collapsed to form black holes.

Most of the bright X-ray sources in Chandra's image of NGC 922 are black holes pulling material in from the winds of massive companion stars. Seven of these are what astronomers classify as "ultraluminous X-ray sources" (ULXs).

These are thought to contain stellar-mass black holes that are at least ten times more massive than the sun, which places them in the upper range for this class of black hole.

They are a different class from the supermassive black holes found at the centers of galaxies, which are millions to billions of times the mass of the sun.

Theoretical work suggests that the most massive stellar-mass black holes should form in environments containing a relatively small fraction of elements heavier than hydrogen and helium, called "metals" by astronomers.

In massive stars, the processes that drive matter away from the stars in stellar winds work less efficiently if the fraction of metals is smaller.

Thus, stars with fewer of these metals among their ingredients should lose less of their mass through winds as they evolve. A consequence of this reduced mass loss is that a larger proportion of massive stars will collapse to form black holes when their nuclear fuel is exhausted.

This theory appeared to be supported by the detection of a large number (12) of ULXs in the Cartwheel galaxy, where stars typically contain only about 30% of the metals found in the sun.

To test this theory, scientists studied NGC 922, which contains about the same fraction of metals as the sun, meaning that this galaxy is about three times richer in metals than the Cartwheel galaxy.

Perhaps surprisingly, the number of ULXs found in NGC 922 is comparable to the number seen in the Cartwheel galaxy.

Rather, the ULX tally appears to depend only on the rate at which stars are forming in the two galaxies, not on the fraction of metals they contain.

One explanation for these results is that the theory predicting the most massive stellar-mass black holes should form in metal poor conditions is incorrect.

Hubble Image Hercules A: Huge black hole emits two beams of matter into space.

Hercules A, a galaxy which contains a massive black hole blasting out energy and matter.

This picture is a combination of visible light seen by the Hubble Space Telescope and radio waves, coloured pink in the image, detected by the Karl G. Jansky Very Large Array.

Image credit: NASA, ESA, S. Baum and C. O'Dea (RIT), R. Perley and W. Cotton (NRAO/AUI/NSF), and the Hubble Heritage Team (STScI/AURA)

In the heart of the galaxy Hercules A is a monster black hole: It’s about 600 times as massive as the black hole in the center of our Milky Way, making it about 2.5 billion times the Sun’s mass.

Material is actively funneling down into this black hole, forming a huge disk and blasting out the jets of material seen in the picture.

Focused tightly, those jets shoot across space at very high speed, slamming into material around them.

Eventually they lose energy and slow down, causing them to spread outward, forming the twin lobes shown.

Also when this happens, the material emits light in the radio part of the electromagnetic spectrum. The lobes of Herc A make it one of the brightest sources of radio waves in the entire sky.



The scale of this event is incredible.
Those lobes are well over 1.5 million light years across from edge to edge, 15 times the size of our entire galaxy, and they’re powerful, emitting a billion times the energy our Sun does at radio wavelengths.

The energy flowing out of Hercules A is beyond belief. The black hole blasts out 100 billion times as much energy in X-rays, as our Sun does in all wavelengths of light.

The black hole at the heart of Hercules A emits enough X-ray energy to easily vapourise our entire Earth and most of the Solar System.

NASA Fermi: Mysterious Objects at the Edge of the Electromagnetic Spectrum

From end to end, the newly discovered gamma-ray bubbles extend 50,000 light-years, or roughly half of the Milky Way's diameter, as shown in this illustration. 

Hints of the bubbles' edges were first observed in X-rays (blue) by ESA's ROSAT, a Germany-led mission operating in the 1990s. 

The gamma rays mapped by Fermi (magenta) extend much farther from the galaxy's plane. 

Credit: NASA's Goddard Space Flight Center.

The human eye is crucial to astronomy. Without the ability to see, the luminous universe of stars, planets and galaxies would be closed to us, unknown forever. Nevertheless, astronomers cannot shake their fascination with the invisible.

Outside the realm of human vision is an entire electromagnetic spectrum of wonders. Each type of light from radio waves to gamma-rays reveals something unique about the universe. Some wavelengths are best for studying black holes; others reveal newborn stars and planets; while others illuminate the earliest years of cosmic history.

NASA has many telescopes "working the wavelengths" up and down the electromagnetic spectrum. One of them, the Fermi Gamma-Ray Telescope orbiting Earth, has just crossed a new electromagnetic frontier.

"Fermi is picking up crazy-energetic photons," says Dave Thompson, an astrophysicist at NASA's Goddard Space Flight Center. "And it's detecting so many of them we've been able to produce the first all-sky map of the very high energy universe."

"This is what the sky looks like near the very edge of the electromagnetic spectrum, between 10 billion and 100 billion electron volts."

The light we see with human eyes consists of photons with energies in the range 2 to 3 electron volts. The gamma-rays Fermi detects are billions of times more energetic, from 20 million to more than 300 billion electron volts.

These gamma-ray photons are so energetic, they cannot be guided by the mirrors and lenses found in ordinary telescopes. Instead Fermi uses a sensor that is more like a Geiger counter than a telescope.

If we could wear Fermi's gamma ray "glasses," we'd witness powerful bullets of energy - individual gamma rays - from cosmic phenomena such as supermassive black holes and hypernova explosions. The sky would be a frenzy of activity.

Astrophysicists Discover Stellar Black Hole In Andromeda Galaxy

Astrophysicists claim to have discovered a stellar black hole in the Andromeda galaxy.

The scientists, from Clemson University and the Max Planck Institute for Extraterrestrial Physics, have discovered a stellar mass black hole in Andromeda, a spiral galaxy about 2.6 million light years from Earth.

The discovery was made with data from NASA's Chandra observatory.

The team was studying ultra-luminous X-Rays, emitted a long time ago.

The black hole was suspected when they detected an unusual X-Ray transient light source in Andromeda.

They concluded the source was emitting X-Rays because the black hole was absorbing material at very high rates.

"The brightness suggested that these X-rays belonged to the class of ultra=luminous X-ray sources, or ULXs," said Amanpreet Kaur, a graduate student in physics from the Clemson University, adding, "But ULXs are rare.

There are none at all in the Milky Way where Earth is located, and this is the first to be confirmed in Andromeda. Proving it required detailed observations." The team concluded the ULX source probably originated from a system similar to X-Ray binaries in our own galaxy.

Stellar black holes are small black holes formed by the collapse of very massive stars, each of which weighs about 10 times as much as our Sun.

"We were very lucky that we caught the ULX early enough to see most of its light curve, which showed a very similar behavior to other X-ray sources from our own galaxy," said Wolfgang Pietsch of the Max Planck Institute.

"This means that the ULX in Andromeda likely contains a normal, stellar black hole swallowing material at very high rates," he added.

ESA INTEGRAL deciphers diffuse signature of cosmic-ray electrons

This image shows the entire sky at hard X-ray energies, between 50 and 100 keV, as observed with the Spectrometer on board INTEGRAL (SPI). The image is based on six years worth of data collected with this instrument.

The two main contributions to the emission at these energies are clearly visible: point sources, galactic and extragalactic alike, and diffuse emission. 

Point sources are scattered across the sky, albeit mainly concentrated along the Galactic Plane; the diffuse emission also traces the Galactic Plane and is fainter, at these energies, than the emission arising from point sources.

To study the diffuse emission in great detail and to break it down into the individual physical processes that contribute to it, astronomers need to carefully scrutinise the data and remove the contamination due to point sources. Credits: ESA/INTEGRAL/SPI.

ESA XMM-Newton: Cosmic Ornament

Image Credit: NASA/CXC/Univ. of Potsdam/L. Oskinova et al.

A new image from an assembly of telescopes reveals a pulsar that appears like a spinning cosmic ornament. Combined data from NASA's Chandra X-ray Observatory and ESA's XMM-Newton were used in the discovery of a young pulsar in the remains of a supernova located in the Small Magellanic Cloud, or SMC.

This is the first time a pulsar, which is a spinning, ultra-dense star, has been found in a supernova remnant in the SMC, a small satellite galaxy to the Milky Way.

In this composite image, X-rays from Chandra and XMM-Newton have been colored blue and optical data from the Cerro Tololo Inter-American Observatory in Chile are coloured red and green.

The pulsar, known as SXP 1062, is the bright white source located on the right-hand side of the image in the middle of the diffuse blue emission inside a red shell.

The diffuse X-rays and optical shell are both evidence of a supernova remnant surrounding the pulsar. The optical data also displays spectacular formations of gas and dust in a star-forming region on the left side of the image.

SXP 1062 interests astronomers because the Chandra and XMM-Newton data show that it is rotating unusually slowly -- about once every 18 minutes. (In contrast, some pulsars are found to revolve multiple times per second, including most newly born pulsars.)

This relatively leisurely pace of SXP 1062 makes it one of the slowest rotating X-ray pulsars in the SMC.

Scientists have estimated that the supernova remnant around SXP 1062 is between 10,000 and 40,000 years old, as it appears in the image.

This means that the pulsar is very young, from an astronomical perspective, since it was presumably formed in the same explosion that produced the supernova remnant.

Therefore, assuming that it was born with rapid spin, it is a mystery why SXP 1062 has been able to slow down by so much, so quickly.

Work has already begun on theoretical models to understand the evolution of this unusual object.

Astronomy Image: Sculptor Group of Galaxies

NGC 253 is not only one of the brightest spiral galaxies visible, it is also one of the dustiest.

Discovered in 1783 by Caroline Herschel in the constellation of Sculptor, NGC 253 lies only about ten million light-years distant. NGC 253 is the largest member of the Sculptor Group of Galaxies, the nearest group to our own Local Group of Galaxies.

The dense dark dust accompanies a high star formation rate, giving NGC 253 the designation of starburst galaxy. Visible in the above photograph is the active central nucleus, also known to be a bright source of X-rays and gamma rays.

Gamma-rays detected by Fermi's LAT show that the remnant of Tycho's supernova shines in the highest-energy form of light. 

This portrait of the shattered star includes gamma rays (magenta), X-rays (yellow, green, and blue), infrared (red) and optical data. (Credit: Gamma ray, NASA/DOE/Fermi LAT Collaboration; X-ray, NASA/CXC/SAO; Infrared, NASA/JPL-Caltech; Optical, MPIA, Calar Alto, O. Krause et al. and DSS).

In early November 1572, observers on Earth witnessed the appearance of a "new star" in the constellation Cassiopeia, an event now recognised as the brightest naked-eye supernova in more than 400 years.

It's often called "Tycho's supernova" after the great Danish astronomer Tycho Brahe, who gained renown for his extensive study of the object.

Now, years of data collected by NASA's Fermi Gamma-Ray Space Telescope reveal that the shattered star's remains shine in high-energy gamma rays.

The detection gives astronomers another clue in understanding the origin of cosmic rays, subatomic particles - mainly protons - that move through space at nearly the speed of light.

Exactly where and how these particles attain such incredible energies has been a long-standing mystery because charged particles speeding through the galaxy are easily deflected by interstellar magnetic fields. This makes it impossible to track cosmic rays back to their sources.

"Fortunately, high-energy gamma rays are produced when cosmic rays strike interstellar gas and starlight. These gamma rays come to Fermi straight from their sources," said Francesco Giordano at the University of Bari and the National Institute of Nuclear Physics in Italy. He is the lead author of a paper describing the findings in the Dec. 7 edition of The Astrophysical Journal Letters.

Better understanding the origins of cosmic rays is one of Fermi's key goals. Its Large Area Telescope (LAT) scans the entire sky every three hours, gradually building up an ever-deeper view of the gamma-ray sky. Because gamma rays are the most energetic and penetrating form of light, they serve as signposts for the particle acceleration that gives rise to cosmic rays.

"This detection gives us another piece of evidence supporting the notion that supernova remnants can accelerate cosmic rays," said co-author Stefan Funk, an astrophysicist at the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC), jointly located at SLAC National Accelerator Laboratory and Stanford University, Calif.

In 1949, physicist Enrico Fermi - the satellite's namesake - suggested that the highest-energy cosmic rays were accelerated in the magnetic fields of interstellar gas clouds. In the decades that followed, astronomers showed that supernova remnants may be the galaxy's best candidate sites for this process.

NASA Chandra: Oldest Recorded Supernova

RCW 86 is approximately 8,000 light-years away. At about 85 light-years in diameter, it occupies a region of the sky in the southern constellation of Circinus that is slightly larger than the full moon.

Credits: X-ray: NASA/CXC/SAO and ESA; Infared: NASA/JPL-Caltech/B. Williams (NCSU)

This image combines data from four different space telescopes to create a multi-wavelength view of all that remains of the oldest documented example of a supernova, called RCW 86. The Chinese witnessed the event in 185 A.D., documenting a mysterious "guest star" that remained in the sky for eight months.

X-ray images from NASA's Chandra X-ray Observatory and the European Space Agency's XMM-Newton Observatory are combined to form the blue and green colors in the image. The X-rays show the interstellar gas that has been heated to millions of degrees by the passage of the shock wave from the supernova.

Infrared data from NASA's Spitzer Space Telescope, as well as NASA's Wide-Field Infrared Survey Explorer (WISE) are shown in yellow and red, and reveal dust radiating at a temperature of several hundred degrees below zero, warm by comparison to normal dust in our Milky Way galaxy.

By studying the X-ray and infrared data together, astronomers were able to determine that the cause of the explosion witnessed nearly 2,000 years ago was a Type Ia supernova, in which an otherwise-stable white dwarf, or dead star, was pushed beyond the brink of stability when a companion star dumped material onto it.

Furthermore, scientists used the data to solve another mystery surrounding the remnant - how it got to be so large in such a short amount of time.

By blowing a wind prior to exploding, the white dwarf was able to clear out a huge "cavity," a region of very low-density surrounding the system. The explosion into this cavity was able to expand much faster than it otherwise would have.

This is the first time that this type of cavity has been seen around a white dwarf system prior to explosion. Scientists say the results may have significant implications for theories of white-dwarf binary systems and Type Ia supernovae.

RCW 86 is approximately 8,000 light-years away. At about 85 light-years in diameter, it occupies a region of the sky in the southern constellation of Circinus that is slightly larger than the full moon.

Tycho's supernova remnant shows its stripes

(Image: X-ray: NASA/CXC/Rutgers/K.Eriksen et al.; Optical: DSS)

X-ray stripes have been spotted lurking in the high-energy blast wave of a stellar explosion spotted by Danish astronomer Tycho Brahe in 1572.

Expanding debris from the explosion shines in low-energy (red) X-rays, while the blast wave, a shell of energetic electrons, shines in high-energy (blue) X-rays.
 
The band pattern, which has never been seen before in any remnant, appears in the high-energy X-ray observations.

The stripes are thought to be regions where magnetic fields in the blast wave are more tangled than in surrounding areas. Electrons spiral around these magnetic field lines, and the radius of this corkscrew motion is thought to dictate the size of the gaps between the stripes.

That size corresponds to particles at energies about 100 times as high as those produced at the Large Hadron Collider, according to Kristoffer Eriksen of Rutgers University in Piscataway, New Jersey, and colleagues.

The study suggests that supernova remnants can account for some of the high-energy particles called cosmic rays that bombard Earth from space.

Galactic 'Supervolcano' Seen Erupting With X-Rays

A galactic "supervolcano" in the massive galaxy M87 is erupting, blasting gas outwards. The cosmic volcano — driven by a giant black hole in M87's center — is preventing hundreds of millions of new stars from forming.

An image, taken by NASA's Chandra X-ray Observatory and the National Radio Astronomy Observatory's Very Large Array, captures the drama in action. [Photo of the galactic "supervolcano."]

"Our results show in great detail that supermassive black holes have a surprisingly good control over the evolution of the galaxies in which they live," said Norbert Werner of the SLAC National Accelerator Laboratory in Melo Park, Calif., who led one of two studies of M87's black hole and its effects. "The black hole's reach extends ever farther into the entire cluster, similar to how one small volcano can affect practically an entire hemisphere on Earth."

X-ray galaxy

M87 is about 50 million light-years from Earth and lies at the center of the Virgo cluster, which contains thousands of galaxies. M87 is filled with hot gas that emits X-ray light, which is detectable by Chandra. As the gas cools, it can fall toward the galaxy's center, where it should continue to cool even faster and form new stars.

Yet, radio observations from the Very Large Array suggest that in M87, jets of very energetic particles produced by the black hole interrupt this process. These jets lift up the relatively cool gas near the galaxy's center and produce shock waves in the galaxy's atmosphere from their supersonic speed.

Scientists have found that the interaction of this cosmic "eruption" with the galaxy's environment is very similar to volcanic processes on Earth. In particular, the researchers compared it to the aftermath of the Eyjafjallajokull volcanic eruption, which forced much of Europe to close its airports earlier this year.

The energetic particles produced near the black hole rise through the X-ray-emitting atmosphere of the cluster, lifting up the coolest gas near the center of M87 in their wake, similar to the way hot volcanic gases drag up clouds of dark ash.