NASA Chandra: Signal from Dark Matter

An X-ray image of the hot gas in the central region of the Perseus Cluster of galaxies, taken by the Chandra X-ray Observatory. 

The Perseus Cluster is one of the most massive objects in the Universe with thousands of galaxies immersed in an enormous cloud of superheated gas. 

The image shows enormous bright loops, ripples, and jet-like streaks throughout the cluster. 

Astronomers may have detected an emission line from a form of dark matter, the sterile neutrino, in the spectrum of galaxy clusters like Perseus. 

Credit: Chandra/NASA/ESA

Galaxies are often found in groups or clusters, the largest known aggregations of matter and dark matter.

The Milky Way, for example, is a member of the "Local Group" of about three dozen galaxies, including the Andromeda Galaxy located about 2 million light-years away.

Very large clusters can contain thousands of galaxies, all bound together by gravity.

The closest large cluster of galaxies to us, the Virgo Cluster with about 2000 members, is about 50 million light-years away.

The space between galaxies is not empty. It is filled with hot intergalactic gas whose temperature is of order ten million kelvin, or even higher.

The gas is enriched with heavy elements that escape from the galaxies and accumulate in the intracluster medium over billions of years of galactic and stellar evolution.

These intracluster gas elements can be detected from their emission lines in X-ray, and include oxygen, neon, magnesium, silicon, sulphur, argon, calcium, iron, nickel, and even chromium and manganese.

The relative abundances of these elements contain valuable information on the rate of supernovae in the different types of galaxies in the clusters since supernovae make and/or disburse them into the gas.

Therefore it came as something of a surprise when CfA astronomers and their colleagues discovered a faint line corresponding to no known element.

Esra Bulbul, Adam Foster, Randall Smith, Scott Randall and their team were studying the averaged X-ray spectrum of a set of seventy-three clusters (including Virgo) looking for emission lines too faint to be seen in any single one when they uncovered a line with no known match in a particular spectral interval not expected to have any features.

The scientists propose a tantalizing suggestion: the line is the result of the decay of a putative, long-sought-after dark matter particle, the so-called sterile neutrino.

It had been suggested that the hot X-ray emitting gas in a galaxy cluster might be a good place to look for dark matter signatures, and if the sterile neutrino result is confirmed it would mark a breakthrough in dark matter research (it is of course possible that it is a statistical or other error).

Recent unpublished results from another group tend to support the detection of this feature; the team suggests that observations with the planned Japanese Astro-H X-ray mission in 2015 will be critical to confirm and resolve the nature of this line.

More information: "Detection of an Unidentified Emission Line in the Stacked X-Ray Spectrum of Galaxy Clusters," Esra Bulbul, Maxim Markevitch, Adam Foster, Randall K. Smith, Michael Loewenstein, and Scott W. Randall, ApJ 789, 13, 2014.

NASA NuSTAR Space Telescope: 'Hand of God' image

The hand might look like an X-ray from the doctor's office, but it is actually a cloud of material ejected from a star that exploded. 

NASA's NuSTAR spacecraft has imaged the structure in high-energy X-rays for the first time, shown in blue. 

Lower-energy X-ray light previously detected by NASA's Chandra X-ray Observatory is shown in green and red. 

Credit: NASA/JPL-Caltech/McGill

Religion and astronomy may not overlap often, but a new NASA X-ray image captures a celestial object that resembles the "Hand of God."

The cosmic "hand of God" photo was produced when a star exploded and ejected an enormous cloud of material, which NASA's Nuclear Spectroscopic Telescope Array (NuSTAR), glimpsed in high-energy X-rays, shown in blue in the photo.

NASA's Chandra X-ray Observatory had imaged the green and red parts previously, using lower-energy X-rays.

"NuSTAR's unique viewpoint, in seeing the highest-energy X-rays, is showing us well-studied objects and regions in a whole new light," NuSTAR telescope principal investigator Fiona Harrison, of the California Institute of Technology in Pasadena, said in a statement.

The new image depicts a pulsar wind nebula, produced by the dense remnant of a star that exploded in a supernova.

What's left behind is a pulsar, called PSR B1509-58 (B1509 for short), which spins around 7 times per second blowing a wind of particles into material ejected during the star's death throes.

As these particles interact with nearby magnetic fields, they produce an X-ray glow in the shape of a hand. (The pulsar is located near the bright white spot in the image but cannot be seen itself, NASA officials said.)

Scientists aren't sure whether the ejected material actually assumes the shape of a hand, or whether its interaction with the pulsar's particles is just making it appear that way.

Hongjun An

"We don't know if the hand shape is an optical illusion," Hongjun An, of McGill University in Montreal, said in a statement. "With NuSTAR, the hand looks more like a fist, which is giving us some clues."

The red cloud appearing at the fingertips is a separate structure called RCW 89. The pulsar's wind may be heating the cloud to produce the low-energy X-ray glow, astronomers believe.

The X-ray energies seen by NuSTAR range from 7 to 25 kiloelectron volts, or keV, whereas the energies seen by Chandra range from 0.5 to 2 keV.

The Hand of God is an example of pareidolia, the psychological phenomenon of perceiving familiar shapes in random or vague images.

Other common forms of pareidolia include seeing animals or faces in clouds, or the man in the moon. Despite its supernatural appearance, the Hand of God was produced by natural astrophysical phenomena.

NASA NuSTAR delivers the X-ray goods

Artist's concept of NuSTAR on orbit. NuSTAR has a 10-m (30') mast that deploys after launch to separate the optics modules (right) from the detectors in the focal plane (left). 

Credit: NASA/JPL-Caltech

NASA's Nuclear Spectroscopic Telescope Array (NuSTAR), is giving the wider astronomical community a first look at its unique X-ray images of the cosmos.

The first batch of data from the black-hole hunting telescope was publicly available on Aug. 29, via NASA's High Energy Astrophysics Science Archive Research Center, (HEASARC).

Fiona Harrison

"We are pleased to present the world with NuSTAR's first look at the sky in high-energy X-rays with a true focusing telescope," said Fiona Harrison, the mission's principal investigator at the California Institute of Technology (Caltech), Pasadena.

The images, taken from July to August 2012, shortly after the spacecraft launched, comprise an assortment of extreme objects, including black holes near and far.

The more distant black holes are some of the most luminous objects in the universe, radiating X-rays as they ferociously consume surrounding gas.

One type of black hole in the new batch of data is a blazar, which is an active, supermassive black hole pointing a jet toward Earth.

Systems known as X-ray binaries, in which a compact object such as a neutron star or black hole feeds off a stellar companion, are also in the mix, along with the remnants of stellar blasts called supernovas.

The data set only contains complete observations. Data will be released at a later date for those targets still being observed.

"Astronomers can use these data to better understand the capabilities of NuSTAR and design future observing proposals. The first opportunity will be this fall, for joint observations with XMM-Newton," said Karl Forster of Caltech, who is leading the effort to package the data for the public.

The European Space Agency's XMM-Newton X-ray telescope, like NASA's Chandra X-ray Observatory, complements NuSTAR.

While XMM-Newton and Chandra see lower-energy X-ray light, NuSTAR is the first telescope capable of focusing high-energy X-ray light, allowing for more detailed images than were possible before.

Astronomers can compare data sets from different missions using HEASARC, which gives them a broader understanding of an object of interest.

NuSTAR's high-energy observations help scientists bridge a gap that existed previously in X-ray astronomy, and will lead to new revelations about the bizarre and energetic side of our universe.

Other NASA missions with data available via HEASARC include Chandra, Fermi, Swift, Cosmic Background Explorer (COBE), Wilkinson Microwave Anisotropy Probe (WMAP) and many more.

NASA NuSTAR X-Ray Data analysis of Spiral galaxy

This new view of spiral galaxy IC 342, also known as Caldwell 5, includes data from NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR.

High-energy X-ray data from NuSTAR have been translated to the color magenta, and superimposed on a visible-light view highlighting the galaxy and its star-studded arms.

NuSTAR is the first orbiting telescope to take focused pictures of the cosmos in high-energy X-ray light; previous observations of this same galaxy taken at similar wavelengths blurred the entire object into one pixel.

The two magenta spots are blazing black holes first detected at lower-energy X-ray wavelengths by NASA's Chandra X-ray Observatory.

With NuSTAR's complementary data, astronomers can start to home in on the black holes' mysterious properties.

The black holes appear much brighter than typical stellar-mass black holes, such as those that pepper our own galaxy, yet they cannot be supermassive black holes or they would have sunk to the galaxy’s center.

Instead, they may be intermediate in mass, or there may be something else going on to explain their extremely energetic state. NuSTAR will help solve this puzzle.

IC 342 lies 7 million light-years away in the Camelopardalis constellation. The outer edges of the galaxy cannot be seen in this view.

This image shows NuSTAR X-ray data taken at 10 to 35 kiloelectron volts.

The visible-light image is from the Digitized Sky Survey.

› NuSTAR data only

Image credit: NASA/JPL-Caltech/DSS

NASA - The Pinwheel Galaxy

This image of the Pinwheel Galaxy, also known as M101, combines data in the infrared, visible, ultraviolet and X-rays from four of NASA's space-based telescopes.

This multi-spectral view shows that both young and old stars are evenly distributed along M101's tightly-wound spiral arms.

Such composite images allow astronomers to see how features in one part of the spectrum match up with those seen in other parts.

It is like seeing with a regular camera, an ultraviolet camera, night-vision goggles and X-ray vision, all at the same time.

The Pinwheel Galaxy is in the constellation of Ursa Major (also known as the Big Dipper). It is about 70 percent larger than our own Milky Way Galaxy, with a diameter of about 170,000 light years, and sits at a distance of 21 million light years from Earth.

This means that the light we're seeing in this image left the Pinwheel Galaxy about 21 million years ago - many millions of years before humans ever walked the Earth.

Image Credits: X-ray: NASA/CXC/SAO; IR & UV: NASA/JPL-Caltech; Optical: NASA/STScI

ESA ESO Elst Pizarro: Strangest Comet

On August 7, 1996, Eric W. Elst (Royal Observatory, Uccle, Belgium) reported his discovery of a cometary image on mid-July exposures by Guido Pizarro with the 1.0-m ESO Schmidt telescope at the La Silla Observatory.

Further ESO Schmidt plates were then obtained, and on August 19, with the help of orbital computations by Brian Marsden (IAU Central Bureau for Astronomical Telegrams, Cambridge, Mass., USA), Elst was able to identify the object on them.

Even though the orbit (Period = 5.6 years; inclination = 1.4 deg; eccentricity = 0.17) is entirely characteristic of that of a main-belt minor planet with the implied long-term orbital stability, the continued presence of a tail seemingly confirms the object as a 'comet'.

The object now carries the designation 'Comet P/1996 N2 (Elst-Pizarro)'.

Guido Pizarro and his brother Oscar have worked as nights assistants at the ESO Schmidt telescope since 1973. It is the first comet which carries their name.

Zdenek Sekanina (Jet Propulsion Laboratory, Pasadena, California, USA) believes that the comet's narrow, straight and structureless tail is likely to be a signature of a past dust-emission episode, probably in late May - early July 1996.

At this moment, it is not known, whether it was caused by an outburst from the surface of the object (dust being pushed into space by the gas pressure of evaporating ice), or perhaps a collision with another orbiting object.

It is therefore not entirely excluded that the object is in fact a minor planet (a kilometre-size piece of solid rock), and not a comet with a comparatively large content of icy materials. Further observations are needed to decide this question.

Eso9637a is also available in a larger version. It is reproduced from a 10-min R-filter exposure obtained on Augus t 23, 1996 with the 1.5-m Danish telescope at La Silla and the DFOSC multi-mode instrument. The observers were visiting astronomers Heike Rauer (Paris Observatory, Meudon France) and Hermann Boehnhardt (Munich Observatory, Germany).

The field of view here shown is 8.1 x 6.6 arcmin with North up and East to the left. At the time of the observation, the comet was 1.68 AU from Earth and 2.68 AU from the Sun.

The comet can easily be identified in the frame. No coma is seen, only the pronounced, extremely narrow dust tail which points towards position angle p.a. = 252 deg (about 2 deg away from the direction towards the Sun).

The overall length of the tail in the frame is about 7.6 arcmin (= 555,000 km at the comet), but actually it is longer than 8.5 arcmin, since it extends beyond the edge of the field of view of the original image.

Chandra Image: Abell 3376

Two different teams have reported using Chandra observations of galaxy clusters to study the properties of gravity on cosmic scales and test Einstein's theory of General Relativity.

Such studies are crucial for understanding the evolution of the universe, both in the past and the future, and for probing the nature of dark energy, one of the biggest mysteries in science.

This composite image of the galaxy cluster Abell 3376 shows X-ray data from the Chandra X-ray Observatory and the ROSAT telescope in gold, an optical image from the Digitized Sky Survey in red, green and blue, and a radio image from the VLA in blue.

The "bullet-like" appearance of the X-ray data is caused by a merger, as material flows into the galaxy cluster from the right side. The giant radio arcs on the left side of the image may be caused by shock waves generated by this merger.

The growth of galaxy clusters like Abell 3376 is influenced by the expansion rate of the universe - controlled by the competing effects of dark matter and dark energy - and by the properties of gravity over large scales.

By contrast, observations of supernovas or the large-scale distribution of galaxies, which measure cosmic distances, depend only on the expansion rate of the universe and are not sensitive to the properties of gravity.

In the first of the new studies of gravity, an alternative theory to General Relativity called "f(R) gravity" was tested.

In this theory, the acceleration of the expansion of the universe does not come from an exotic form of energy but from a modification of the gravitational force.

Mass estimates of galaxy clusters in the local universe were compared with model predictions for f(R) gravity.

Data from geometrical studies, such as supernova work, were also used. Using this comparison between theory and observation, no evidence was found that gravity is different from General Relativity on scales larger than 130 million light years.

This limit corresponds to a hundred-fold improvement on the bounds of the modified gravitational force's range that can be set without using the cluster data.

In the second study, a comparison was made between X-ray observations of how rapidly galaxy clusters have grown over cosmic time to the predictions of General Relativity.

Once again, data from geometrical studies such as distances to supernovas and galaxy clusters were incorporated.

Nearly complete agreement was seen between observation and theory, arguing against any alternative gravity models with a different rate of growth.

In particular "DGP gravity" (named after its inventors Gia Dvali, Gregory Gabadadze, and Massimo Porrati) predicts a slower rate of cluster growth than General Relativity, because gravity is weakened on large scales as it leaks into an extra dimension. Like f(R) gravity, the DGP model is designed to avoid the need for an exotic form of energy causing cosmic acceleration.

Chandra observations of galaxy clusters have previously been used to show that dark energy has stifled the growth of these massive structures over the last 5 billion years and to provide independent evidence for the existence of dark energy by offering a different way to measure cosmic distances.

NASA Fermi Tycho Supernova: Cosmic Mystery

Gamma rays detected by NASA's Fermi space telescope 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

A well-known exploded star that is pumping out powerful gamma rays may be the celestial smoking gun astronomers have in the search for the origins of some of the fastest-moving particles in the universe, a new study reports.

NASA's Fermi space telescope has detected gamma rays — the highest-energy form of light — emanating from the shattered husk of Tycho's supernova, a star that exploded in 1572.

The find could help astronomers pinpoint the origin of cosmic rays, super-speedy subatomic particles that crash constantly into Earth's atmosphere, researchers said.

ESA XMM-Newton: Strangely slow X-Ray pulsar discovered

The X-ray pulsar SXP 1062 embedded in the remnant of the supernova that created it. Credit: ESA/XMM-Newton/ L.Oskinova/ M.Guerrero; CTIO/R.Gruendl/Y.H.Chu.

Astronomers have discovered a very slowly rotating X-ray pulsar still embedded in the remnant of the supernova that created it.

This unusual object was detected on the outskirts of the Small Magellanic Cloud, a satellite galaxy of the Milky Way, using data from a number of telescopes, including ESA's XMM-Newton.

A puzzling mismatch between the fairly young age of the supernova remnant and the slow rotation of the pulsar, which would normally indicate a much older object, raises interesting questions about the origin and evolution of pulsars.

The spectacular supernova explosion that marks the end of a massive star's life also has an intriguing aftermath.

On the one hand, the explosion sweeps up the surrounding interstellar material creating a supernova remnant that is often characterised by a distinctive bubble-like shape, on the other hand, the explosion also leaves behind a compact object - a neutron star or a black hole.

Since supernova remnants shine only for a few tens of thousands of years before dispersing into the interstellar medium, not many compact objects have been detected while still enclosed in their expanding shell.

An international team of astronomers has now discovered one of these rarely observed pairs, consisting of a strongly magnetised, rotating neutron star - a pulsar - surrounded by the remains of the explosion that generated it.

The newly found pulsar, named SXP 1062, is located at the outskirts of the Small Magellanic Cloud (SMC), one of the satellite galaxies of the Milky Way. SXP 1062 is an X-ray pulsar, part of a binary system in which the compact object is accreting mass from a companion star, resulting in the emission of copious amounts of X-rays.

The astronomers first detected the pulsar's X-ray emission using data from ESA's XMM-Newton as well as NASA's Chandra space-based observatories. A later study of optical images of the source and its surroundings revealed the bubble-shaped signature of the supernova remnant around the binary system.

"The most interesting aspect of this pulsar is possibly its extremely long period - 1062 seconds - which makes it one of the slowest pulsars on record," comments Lidia Oskinova from the Institute for Physics and Astronomy in Potsdam, Germany, coordinator of the team that analysed the X-ray data.

Pulsars rotate quite rapidly in their early stages, with periods of only a fraction of a second, and then slow down gradually with age. "Slowly spinning pulsars are particularly difficult to detect. Only a few with periods longer than a thousand seconds have been observed to date," she adds.

Xmas Tree - Happy Holidays!

NASA Chandra X-ray Image: Abell 2052 Galaxy Cluster Sloshes cosmic gas

Like wine in a glass, vast clouds of hot gas are sloshing back and forth in Abell 2052, a galaxy cluster located about 480 million light years from Earth.

X-ray data (blue) from NASA's Chandra X-ray Observatory shows the hot gas in this dynamic system, and optical data (gold) from the Very Large Telescope shows the galaxies.

The hot, X-ray bright gas has an average temperature of about 30 million degrees.

A huge spiral structure in the hot gas, spanning almost a million light years, is seen around the outside of the image, surrounding a giant elliptical galaxy at the center.

This spiral was created when a small cluster of galaxies smashed into a larger one that surrounds the central elliptical galaxy.

The smaller cluster passed the cluster core, the direction of motion of the cluster gas reversed and it travelled back towards the cluster centre.

The cluster gas moved through the centre again and "sloshed" back and forth, similar to wine sloshing in a glass that was jerked sideways.

The sloshing gas ended up in a spiral pattern because the collision between the two clusters was off-center.

The Chandra data show clear bubbles evacuated by material blasted away from the black hole, which are surrounded by dense, bright, cool rims.

As with the sloshing, this activity helps prevent cooling of the gas in the cluster's core, setting limits on the growth of the giant elliptical galaxy and its supermassive black hole.

Image Credit: X-ray: NASA/CXC/BU/L.Blanton; Optical: ESO/VLT

X-rays Unravels Mysteries of Earth’s Core

The window of opportunity for implementing radical changes to combat global warming may be as narrow as five years, warns a new report by the International Energy Agency. (Photo: NASA/Reuters)

The Earth's core, which is some 3,000km (1,900 miles) below sea level, will never be reached by scientists but a new experiment will attempt to unravel the mysterious processes at the center of the planet.

The European Synchrotron Radiation Facility's ID24 beam line will use X-ray beams to subject iron and other materials to extraordinary temperatures and pressures to recreate the extreme conditions at the center of the Earth as it investigate on the origin of the Earth's magnetic field, and how shock waves from earthquakes propagate through it.

The ID24 will utilize what is known as a diamond anvil cell - an established and remarkably simple means to create high pressures by confining tiny samples between the points of two carefully cut diamonds.

These samples are then compressed at a pressure millions of times higher than that on the Earth's surface after which high-power lasers are fired through the diamonds to heat them to higher than 10,000C.

The newly upgraded ID24 makes it possible to focus the X-rays to a much smaller spot than existing facilities to determine the precise composition and chemistry of the samples.

The X-rays are also able to monitor the reactions that happen as matter is heated and squeezed with a resolution several hundreds higher, and "snapshots" taken every millionth of a second.

The microsecond time resolution makes the ID24 unique, according to Sakura Pascarelli, chief scientist on the ID24 beam line.

Located in Grenoble, France, the ID24 is the first of eight beam lines at the ESRF that will be radically overhauled as part of the eight year 180 million euro project.

ROSAT Space telescope set to crash to Earth

As the world waits for the six-ton satellite UARS to crash to Earth this week, we can reveal that a second giant piece of space junk is set for a similar fiery demise within weeks.

It wasn’t always junk. The latest doomed craft, called ROSAT, is a German space telescope that observed in X-ray light from 1990 to 1999 in an orbit 575 km above the Earth.

Atmospheric drag has already brought ROSAT (ROentgen SATellite) to a height of less than 327 km and it has no on-board propulsion system to control its descent.

NASA experts are warning that as many as 30 fragments, weighing a total of 1.6 tons, could survive re-entry to hit the ground, including the largest chunk, the observatory’s hefty glass mirror.

It will re-enter the atmosphere at a speed of around 28,000 km per hour and disintegrate in early November. There is currently an error of plus or minus five weeks in this prediction, so the crash landing could occur in early October.

Fluctuations in solar activity which can cause variation in the density of the fringes of the atmosphere add to the uncertainty.

Most of the inhabited world lies under the track of ROSAT which flies in an orbit that carries it from 53 degrees north to 53 degrees south. Experts expect most of the debris to impact the ground in a compact region but fragments could fall within an 80 km wide path.

EURS and FEMA
With UARS, a massive dead satellite due to plunge back to Earth this week, the Federal Emergency Management Agency (FEMA) is laying the groundwork for a fast response in case the 6 1/2-ton spacecraft falls over, or on American soil.

NASA Swift: Gamma-Ray Bursts More Active Than Thought

From time to time, a huge explosion followed by a bright flash of light can be observed in space.

It's a colossal gamma-ray burst (GRB), emitting for a few seconds as much radiation as a million galaxies.

A new discovery made by NASA's Swift satellite showed that the extremely energetic flares that follow a gamma-ray burst (GRB) are not just space "hiccups", but in fact, they represent a continuation of the burst itself.

They are truly impressive space phenomena, as even the smallest GRB can emit the same amount of energy our Sun will emit over its expected 10 billion-year lifetime, in just one second.

The most luminous events known in the universe since the Big Bang are flashes of gamma rays, coming from seemingly random places in the sky and at random times, that last from milliseconds to many minutes and are often followed by "afterglow" emission at longer wavelengths (X-ray, UV, optical, IR and radio).

What causes such a tremendous discharge of energy? The core of a massive star collapsing to form a black hole or neutron star. The initial pulse of gamma-rays is usually followed by what was thought to be a short-lived X-ray flare.

Hans Krimm of Universities Space Research Association, Columbia, Md. and NASA's Goddard Space Flight Center in Greenbelt, Md., and eight colleagues, have been able to prove that these X-ray flares are actually a continuation of the initial pulse, which proves that the GRB central engines are active much longer than previously thought.

This was done after analyzing such an event, named GRB 060714, for its detection date of July 14, 2006 and the results showed that the prompt gamma-ray emission and the subsequent X-ray flares appear to form a continuously connected and evolving succession of events.

"This pattern points to a continuous injection of energy from the central engine, perhaps fueled by sporadic infall of material onto a black hole. 

The black hole just keeps gobbling up gas and the engine keeps spewing out energy," says Krimm.

NASA Chandra Image: Spiral Galaxy NGC 3393

Evidence for a pair of supermassive black holes in a spiral galaxy has been found in data from NASA's Chandra X-ray Observatory.

This main image is a composite of X-rays from Chandra (blue) and optical data from the Hubble Space Telescope (gold) of the spiral galaxy NGC 3393.

Meanwhile, the inset box shows the central region of NGC 3993 as observed just by Chandra.

The diffuse blue emission in the large image is from hot gas near the center of NGC 3393 and shows low energy X-rays.

The inset shows only high energy X-rays, including emission from iron.

This type of emission is a characteristic feature of growing black holes that are heavily obscured by dust and gas.

Two separate peaks of X-ray emission (roughly at 11 o'clock and 4 o'clock) can clearly be seen in the inset box. These two sources are black holes that are actively growing, generating X-ray emission as gas falls towards the black holes and becomes hotter.

The obscured regions around both black holes block the copious amounts of optical and ultraviolet light produced by infalling material.

At a distance of 160 million light years, NGC 3393 contains the nearest known pair of supermassive black holes. It is also the first time a pair of black holes has been found in a spiral galaxy like our Milky Way.

Separated by only 490 light years, the black holes in NGC 3393 are likely the remnant of a merger of two galaxies of unequal mass a billion or more years ago.

Dubbed "minor mergers" by scientists, such collisions of one larger and another smaller galaxy may, in fact, be the most common way for black hole pairs to form.

Until the latest Chandra observations of NGC 3393, however, it has has been difficult to find good candidates for minor mergers because the merged galaxy is expected to look like an ordinary spiral galaxy.

If this was a minor merger, the black hole in the smaller galaxy should have had a smaller mass than the other black hole before their host galaxies started to collide.

Good estimates of the masses of both black holes are not yet available to test this idea, although the observations do show that both black holes are more massive than about a million Suns.

Credits: X-ray: NASA/CXC/SAO/G. Fabbiano et al; Optical: NASA/STScI

Chandra Image:: Antennae Galaxies

A new composite image from NASA's Great Observatories presents a stunning display of the Antennae galaxies.

X-ray data from Chandra (blue), optical data from Hubble (gold and brown), and infrared data from Spitzer (red) are featured.

Supernova explosions are enriching the intergalactic gas with elements like oxygen, iron, and silicon that will be incorporated into new generations of stars and planets

GOES-15 Solar X-Ray Imager Makes a Miraculous First Light

GOES-15 Solar X-Ray Imager Makes a Miraculous First Light

The Solar X-Ray Imager instrument aboard the GOES-15 satellite has just provided its first light image of the sun, but it required a lot of experts to make it happen.

Scientists and engineers from NASA and the National Oceanic and Atmospheric Administration (NOAA) have been working to bring the Solar X-Ray Imager (SXI) instrument to full functionality since the Geostationary Operational Environmental Satellite (GOES)-15, formerly known as the GOES-P satellite achieved orbit.

GOES-15 launched on March 4, 2010 from Cape Canaveral, Fla. On April 6, 2010, GOES-15 captured its first visible image of Earth and on April 26, GOES-15 took its first full-disk infrared image.

"Since the early checkout of GOES 15 (P) and the anomalous turn on of the Solar X-Ray Imager, the team has been aggressively pursuing all avenues to recover the instrument," said Andre' Dress, GOES N-P Deputy Project Manager at NASA's Goddard Space Flight Center in Greenbelt, Md." Frankly, we were down to our last straw when all the teams' hard work and efforts finally paid off.

We now believe we have a full recovery of the instrument's functionality! It's an incredible story and a true testament of our NASA/contractor teams expertise, hard work and determination."

On June 3, the GOES 15 Solar X-Ray Imager finally came on-line. Scientists and engineers had subjected SXI to a series of long duration turn on tests in the hopes of clearing the short. About 16 hours into the testing, the instrument voltages returned to normal values and SXI now appears to be functioning properly.

"We were facing a tough problem when we first attempted to bring SXI on line," said George Koerner, SXI program manager at the Lockheed Martin Space Systems Company (LMSSC) Advanced Technology Center (ATC) in Palo Alto, Calif. where the Solar X-ray Imager was designed and built.

"But because of our ability to bring together subject matter experts from both government and industry, to move forward step by step, and to work as a team patiently and persistently, together we achieved mission success. This is an enormously satisfying outcome."

Since its recovery, several test solar images have also been subsequently taken successfully. The GOES team continue to assess the health of the instrument. This new round of testing will assess SXI's total functionality. That functionality means the team will capture images of the sun with the camera to assess whether the camera is properly processing image data

Survivor Black Holes May Be Mid-Sized

New evidence from NASA's Chandra X-ray Observatory and ESA's XMM-Newton strengthens the case that two mid-sized black holes exist close to the center of a nearby starburst galaxy.

These "survivor" black holes avoided falling into the center of the galaxy and could be examples of the seeds required for the growth of supermassive black holes in galaxies, including the one in the Milky Way.

For several decades, scientists have had strong evidence for two distinct classes of black hole: the stellar-mass variety with masses about ten times that of the Sun, and the supermassive ones, located at the center of galaxies, that range from hundreds of thousands to billions of solar masses.

But a mystery has remained: what about black holes that are in between? Evidence for these objects has remained controversial, and until now there were no strong claims of more than one such black hole in a single galaxy. Recently, a team of researchers has found signatures in X-ray data of two mid-sized black holes in the starburst galaxy M82 located 12 million light years from Earth.

"This is the first time that good evidence for two mid-sized black holes has been found in one galaxy," said Hua Feng of the Tsinghua University in China, who led two papers describing the results. "Their location near the center of the galaxy might provide clues about the origin of the Universe's largest black holes - supermassive black holes found in the centers of most galaxies."

One possible mechanism for the formation of supermassive black holes involves a chain reaction of collisions of stars in compact star clusters that results in the buildup of extremely massive stars, which then collapse to form intermediate-mass black holes. The star clusters then sink to the center of the galaxy, where the intermediate-mass black holes merge to form a supermassive black hole.

Compton Observatory: Detection of Gamma Ray Bursts

Compton Gamma Ray Observatory
Cosmic gamma ray bursts (GRBs) were discovered by accident in the late 1960's by satellites designed to detect gamma rays produced by atomic bomb tests on Earth.

The GRBs appear first as a brilliant flash of gamma rays, that rises and falls in a matter of minutes. These bursts are often followed by afterglows at X-ray, optical and radio wavelengths.

A major leap forward in understanding the source of cosmic GRBs was made when the Burst and Transient Source Experiment (BATSE) was launched aboard the Compton Gamma Ray Observatory in 1991.

BATSE had an all-sky monitor that was capable of detecting a GRB virtually anywhere in the sky. Over a period of 9 years BATSE recorded thousands of GRBs, about 1 per day. Among other things, these results showed that the bursts occurred at random all over the sky.

If the bursts were associated with objects in our Milky Way Galaxy, they would not show such a universal distribution. Rather, they would be concentrated along the plane of our galaxy like most of the matter in the Milky Way.

The BATSE data was so good that it allowed astronomers to also rule out the possibility that the GRBs might be originating in the halo of our galaxy.

The Observatory was named in honor of Dr. Arthur Holly Compton, who won the Nobel prize in physics for work on scattering of high-energy photons by electrons - a process which is central to the gamma-ray detection techniques of all four instruments.

Read the full article on the Chandra X-ray Observatory here ....

X-Ray of child with Food Beater stuck in mouth

An X-ray of a three-year-old girl with a food mixer accessory embedded in her palate.

The toddler was running around at a nursery school in Haifa, Israel, with the spiral kneading accessory in her mouth when she fell. Doctors removed it safely