Winds of Supermassive Black Holes Can Shape Galaxy-Wide Star Formation

The combined observations from two generations of X-Ray space telescopes have now revealed a more complete picture of the nature of high-speed winds expelled from super-massive black holes. Scientist analyzing the observations discovered that the winds linked to these black holes can travel in all directions and not just a narrow beam as previously thought. The black holes reside at the center of active galaxies and quasars and are surrounded by accretion discs of matter. Such broad expansive winds have the potential to effect star formation throughout the host galaxy or quasar. The discovery will lead to revisions in the theories and models that more accurately explain the evolution of quasars and galaxies.

This plot of data from NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) and the European Space Agency's (ESA's) XMM-Newton determines for the first time the shape of ultra-fast winds from supermassive black holes, or quasars. The winds blow in every direction, in a nearly spherical fashion, coming from both sides of a galaxy (Credit: NASA/JPL-Caltech/Keele Univ.;XMM-Newton and NuSTAR Missions)
This plot of data from NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR) and the European Space Agency’s (ESA’s) XMM-Newton determines for the first time the shape of ultra-fast winds from supermassive black holes, or quasars. The winds blow in every direction, in a nearly spherical fashion, coming from both sides of a galaxy (Credit: NASA/JPL-Caltech/Keele Univ.;XMM-Newton and NuSTAR Missions, [Ref])
The observations were by the XMM-Newton and NuSTAR x-ray space telescopes of the quasar PDS 456. The observations were combined into the graphic, above. PDS 456 is a bright quasar residing in the constellation Serpens Cauda (near Ophiuchus). The data graph shows both a peak and a trough in the otherwise nominal x-ray emission profile as shown by the NuSTAR data (pink). The peak represents X-Ray emissions directed towards us (i.e.our telescopes) while the trough is X-Ray absorption that indicates that the expulsion of winds from the super-massive black hole is in many directions – effectively a spherical shell. The absorption feature caused by iron in the high speed wind is the new discovery.

X-Rays are the signature of the most energetic events in the Cosmos but also are produced from some of the most docile bodies – comets. The leading edge of a comet such as Rosetta’s P67 generates X-Ray emissions from the interaction of energetic solar ions capturing electrons from neutral particles in the comet’s coma (gas cloud). The observations of a super-massive black hole in a quasar billions of light years away involve the generation of x-rays on a far greater scale, by winds that evidently has influence on a galactic scale.

A diagram of the ESA XMM-Newton X-Ray Telescope. Delivered to orbit by a Ariane 5 launch vehicle in 1999. (Illustration Credit: ESA/XMM-Newton)
A diagram of the ESA XMM-Newton X-Ray Telescope. Delivered to orbit by a Ariane 5 launch vehicle in 1999. (Illustration Credit: ESA/XMM-Newton)

The study of star forming regions and the evolution of galaxies has focused on the effects of shock waves from supernova events that occur throughout the lifetime of a galaxy. Such shock waves trigger the collapse of gas clouds and formation of new stars. This new discovery by the combined efforts of two space telescope teams provides astrophysicists new insight into how star and galaxy formation takes place. Super-massive blackholes, at least early in the formation of a galaxy, can influence star formation everywhere.

The NuStar Space Telescope launched into Earth orbit by a Orbital Science Corp. Pegasus rocket, 2012. The Wolter telescope design images throughout a spectral range from 5 to 80 KeV. (Credit: NASA/Caltech-JPL)
The NuStar Space Telescope launched into Earth orbit by a Orbital Science Corp. Pegasus rocket, 2012. The Wolter telescope design – optics in the foreground, 10 meter truss and detectors at back – images throughout a spectral range from 5 to 80 KeV. (Credit: NASA/Caltech-JPL)

Both the ESA built XMM-Newton and the NuSTAR X-Ray space telescope, a SMEX class NASA mission, use grazing incidence optics, not glass (refraction) or mirrors (reflection) as in conventional visible light telescopes. The incidence angle of the X-rays must be very shallow and consequently the optics are extended out on a 10 meter (33 foot) truss in the case of NuSTAR and over a rigid frame on the XMM-Newton.

Diagram of one of three x-ray telescopes of the XMM-Newton design. Only a few of the grazing angle concentric mirrors are shown. Inset: a simplified illustration of how a Wolter telescope works. (Credits: Wikimedia, ESA)
Diagram of one of three x-ray telescopes of the XMM-Newton design. Only a few of the grazing angle concentric mirrors are shown. Inset: a simplified illustration of how a Wolter telescope works. (Credits: Wikimedia, ESA) [click to enlarge]
The spectral ranges of the XMM-Newton and NuSTAR Telescopes. (Credits: NASA, ESA)
The spectral ranges of the XMM-Newton and NuSTAR Telescopes. (Credits: NASA, ESA)

The ESA built XMM-Newton was launched in 1999, an older generation design that used a rigid frame and structure. All the fairing volume and lift capability of the Ariane 5 launch vehicle was needed to put the Newton in orbit. The latest X-Ray telescope – NuSTAR – benefits from tens years of technological advances. The detectors are more efficient and faster and the rigid frame was replaced with a compact truss which required all of 30 minutes to deploy. Consequently, NuSTAR was launched on a Pegasus rocket piggybacked on a L-1011, a significantly smaller and less expensive launch system.

So now these observations are effectively delivered to the theorists and modelers. The data is like a new ingredient in the batter from which a galaxy and stars are formed. The models of galaxy and star formation will improve and will more accurately describe how quasars, with their active super-massive black-holes, transition into more quiescent galaxies such as our own Milky Way.

Reference:

XMM-NEWTON AND NUSTAR SPECTRUM OF THE QUASAR PDS 456

ARTIST’S IMPRESSION OF BLACK-HOLE WIND IN A GALAXY

Intriguing X-Ray Signal Might be Dark Matter Candidate

Could a strange X-ray signal coming from the Perseus galaxy cluster be a hint of the elusive dark matter in our Universe?

Using archival data from the Chandra X-ray Observatory and the XMM-Newton mission, astronomers found an unidentified X-ray emission line, or a spike of intensity at a very specific wavelength of X-ray light. This spike was also found in 73 other galaxy clusters in XMM-Newton data.

The scientists propose that one intriguing possibility is that the X-rays are produced by the decay of sterile neutrinos, a hypothetical type of neutrino that has been proposed as a candidate for dark matter and is predicted to interact with normal matter only via gravity.

“We know that the dark matter explanation is a long shot, but the pay-off would be huge if we’re right,” said Esra Bulbul of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Massachusetts, who led the study. “So we’re going to keep testing this interpretation and see where it takes us.”

Astronomers estimate that roughly 85 percent of all matter in the Universe is dark matter, invisible to even the most powerful telescopes, but detectable by its gravitational pull.

Galaxy clusters are good places to look for dark matter. They contain hundreds of galaxies as well as a huge amount of hot gas filling the space between them. But measurements of the gravitational influence of galaxy clusters show that the galaxies and gas make up only about one-fifth of the total mass. The rest is thought to be dark matter.

Bulbul explained in a post on the Chandra blog that she wanted try hunting for dark matter by “stacking” (layering observations on top of each other) large numbers of observations of galaxy clusters to improve the sensitivity of the data coming from Chandra and XMM-Newton.

“The great advantage of stacking observations is not only an increased signal-to-noise ratio (that is, the amount of useful signal compared to background noise), but also the diminished effects of detector and background features,” wrote Bulbul. “The X-ray background emission and instrumental noise are the main obstacles in the analysis of faint objects, such as galaxy clusters.”

Her primary goal in using the stacking technique was to refine previous upper limits on the properties of dark matter particles and perhaps even find a weak emission line from previously undetected metals.

“These weak emission lines from metals originate from the known atomic transitions taking place in the hot atmospheres of galaxy clusters,” said Bulbul. “After spending a year reducing, carefully examining, and stacking the XMM-Newton X-ray observations of 73 galaxy clusters, I noticed an unexpected emission line at about 3.56 kiloelectron volts (keV), a specific energy in the X-ray range.”

In theory, a sterile neutrino decays into an active neutrino by emitting an X-ray photon in the keV range, which can be detectable through X-ray spectroscopy. Bulbul said that her team’s results are consistent with the theoretical expectations and the upper limits placed by previous X-ray searches.

Bulbul and her colleagues worked for a year to confirm the existence of the line in different subsamples, but they say they still have much work to do to confirm that they’ve actually detected sterile neutrinos.

“Our next step is to combine data from Chandra and JAXA’s Suzaku mission for a large number of galaxy clusters to see if we find the same X-ray signal,” said co-author Adam Foster, also of CfA. “There are lots of ideas out there about what these data could represent. We may not know for certain until Astro-H launches, with a new type of X-ray detector that will be able to measure the line with more precision than currently possible.”

Astro-H is another Japanese mission scheduled to launch in 2015 with a high-resolution instrument that should be able to see better detail in the spectra, and Bulbul said they hope to be able to “unambiguously distinguish an astrophysical line from a dark matter signal and tell us what this new X-ray emission truly is.”

Since the emission line is weak, this detection is pushing the capabilities Chandra and XMM Newton in terms of sensitivity. Also, the team says there may be explanations other than sterile neutrinos if this X-ray emission line is deemed to be real. There are ways that normal matter in the cluster could have produced the line, although the team’s analysis suggested that all of these would involve unlikely changes to our understanding of physical conditions in the galaxy cluster or the details of the atomic physics of extremely hot gases.

The authors also note that even if the sterile neutrino interpretation is correct, their detection does not necessarily imply that all of dark matter is composed of these particles.

The Chandra press release shared an interesting behind-the-scenes look into how science is shared and discussed among scientists:

Because of the tantalizing potential of these results, after submitting to The Astrophysical Journal the authors posted a copy of the paper to a publicly accessible database, arXiv. This forum allows scientists to examine a paper prior to its acceptance into a peer-reviewed journal. The paper ignited a flurry of activity, with 55 new papers having already cited this work, mostly involving theories discussing the emission line as possible evidence for dark matter. Some of the papers explore the sterile neutrino interpretation, but others suggest different types of candidate dark matter particles, such as the axion, may have been detected.

Only a week after Bulbul et al. placed their paper on the arXiv, a different group, led by Alexey Boyarsky of Leiden University in the Netherlands, placed a paper on the arXiv reporting evidence for an emission line at the same energy in XMM-Newton observations of the galaxy M31 and the outskirts of the Perseus cluster. This strengthens the evidence that the emission line is real and not an instrumental artifact.

Further reading:
Paper by Bulbul et al.
Chandra press release
ESA press release
Chandra blog

A Cosmic Intruder Grabbed Hot Gas From This Galaxy Group

So galaxy group NGC 5044 was just sitting quietly by itself a few million years ago when galaxy NGC 5054 decided to pass right through it. That close encounter finished long ago, but the ricochet is still visible in telescopes as astronomers spotted hot gas rippling through the host galaxy.

“Galaxies are social beasts that are mostly found in groups or clusters – large assemblies of galaxies that are permeated by even larger amounts of diffuse gas. With temperatures of 10 million degrees or more, the gas in galaxy groups and clusters is hot enough to shine brightly in X-rays and be detected by ESA’s XMM-Newton X-ray observatory,” the European Space Agency stated.

“As galaxies speed through these gigantic cauldrons, they occasionally jumble the gas and forge it into lop-sided shapes. An example is revealed in this composite image of the galaxy group NGC 5044, the brightest group in X-rays in the entire sky.”

Fresh observations from XMM-Newton (in blue) are visible in this composite image with other pictures from the Wide-field Infrared Survey Explorer, the Digitized Sky Survey (optical) and Galex (near-ultraviolet).

Publication of this research was accepted in MNRAS and is currently available on prepublishing site Arxiv. The lead author is Ewan O’Sullivan, a visiting scientist at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass.

NuSTAR Puts New Spin On Supermassive Black Holes

A supermassive black hole has been found in an unusual spot: an isolated region of space where only small, dim galaxies reside. Image credit: NASA/JPL-Caltech

Checking out the spin rate on a supermassive black hole is a great way for astronomers to test Einstein’s theory under extreme conditions – and take a close look at how intense gravity distorts the fabric of space-time. Now, imagine a monster … one that has a mass of about 2 million times that of our Sun, measures 2 million miles in diameter and rotating so fast that it’s nearly breaking the speed of light.

A fantasy? Not hardly. It’s a supermassive black hole located at the center of spiral galaxy NGC 1365 – and it is about to teach us a whole lot more about how black holes and galaxies mature.

What makes researchers so confident they have finally taken definitive calculations of such an incredible spin rate in a distant galaxy? Thanks to data taken by the Nuclear Spectroscopic Telescope Array, or NuSTAR, and the European Space Agency’s XMM-Newton X-ray satellites, the team of scientists has peered into the heart of NGC 1365 with x-ray eyes – taking note of the location of the event horizon – the edge of the spinning hole where surrounding space begins to be dragged into the mouth of the beast.

“We can trace matter as it swirls into a black hole using X-rays emitted from regions very close to the black hole,” said the coauthor of a new study, NuSTAR principal investigator Fiona Harrison of the California Institute of Technology in Pasadena. “The radiation we see is warped and distorted by the motions of particles and the black hole’s incredibly strong gravity.”

However, the studies didn’t stop there, they advanced to the inner edge to encompass the location of the accretion disk. Here is the “Innermost Stable Circular Orbit” – the proverbial point of no return. This region is directly related to a black hole’s spin rate. Because space-time is distorted in this area, some of it can get even closer to the ISCO before being pulled in. What makes the current data so compelling is to see deeper into the black hole through a broader range of x-rays, allowing astronomers to see beyond veiling clouds of dust which only confused past readings. These new findings show us it isn’t the dust that distorts the x-rays – but the crushing gravity.

Scientists measure the spin rates of supermassive black holes by spreading the X-ray light into different colors. Image credit: NASA/JPL-Caltech
Scientists measure the spin rates of supermassive black holes by spreading the X-ray light into different colors. Image credit: NASA/JPL-Caltech

“This is the first time anyone has accurately measured the spin of a supermassive black hole,” said lead author Guido Risaliti of the Harvard-Smithsonian Center for Astrophysics (CfA) and INAF — Arcetri Observatory.

“If I could have added one instrument to XMM-Newton, it would have been a telescope like NuSTAR,” said Norbert Schartel, XMM-Newton Project Scientist at the European Space Astronomy Center in Madrid. “The high-energy X-rays provided an essential missing puzzle piece for solving this problem.”

Even though the central black hole in NGC 1365 is a monster now, it didn’t begin as one. Like all things, including the galaxy itself, it evolved with time. Over millions of years it gained in girth as it consumed stars and gas – possibly even merging with other black holes along the way.

“The black hole’s spin is a memory, a record, of the past history of the galaxy as a whole,” explained Risaliti.

“These monsters, with masses from millions to billions of times that of the sun, are formed as small seeds in the early universe and grow by swallowing stars and gas in their host galaxies, merging with other giant black holes when galaxies collide, or both,” said the study’s lead author, Guido Risaliti of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., and the Italian National Institute for Astrophysics.

This new spin on black holes has shown us that a monster can emerge from “ordered accretion” – and not simply random multiple events. The team will continue their studies to see how factors other than black hole spin changes over time and continue to observe several other supermassive black holes with NuSTAR and XMM-Newton.

“This is hugely important to the field of black hole science,” said Lou Kaluzienski, NuSTAR program scientist at NASA Headquarters in Washington, D.C. “NASA and ESA telescopes tackled this problem together. In tandem with the lower-energy X-ray observations carried out with XMM-Newton, NuSTAR’s unprecedented capabilities for measuring the higher energy X-rays provided an essential, missing puzzle piece for unraveling this problem.”

Original Story Source: JPL/NASA News Release.

What Happens When the Winds of Giant Stars Collide?

XMM-Newton observation of the core of the very massive cluster Cyg OB2 located in the constellation of Cygnus, 4700 light-years from Earth. Credit: ESA/G. Rauw

From an ESA press release:

Two massive stars racing in orbit around each other have had their colliding stellar winds X-rayed for the first time, thanks to the combined efforts of ESA’s XMM-Newton and NASA’s Swift space telescopes. Stellar winds, pushed away from a massive star’s surface by its intense light, can have a profound influence on their environment. In some locations, they may trigger the collapse of surrounding clouds of gas and dust to form new stars. In others, they may blast the clouds away before they have the chance to get started.

Now, XMM-Newton and Swift have found a ‘Rosetta stone’ for such winds in a binary system known as Cyg OB2 #9, located in the Cygnus star-forming region, where the winds from two massive stars orbiting around each other collide at high speeds.

Cyg OB2 #9 remained a puzzle for many years. Its peculiar radio emission could only be explained if the object was not a single star but two, a hypothesis that was confirmed in 2008. At the time of the discovery, however, there was no direct evidence for the winds from the two stars colliding, even though the X-ray signature of such a phenomenon was expected.

This signature could only be found by tracking the stars as they neared the closest point on their 2.4-year orbit around each other, an opportunity that presented itself between June and July 2011.

As the space telescopes looked on, the fierce stellar winds slammed together at speeds of several million kilometres per hour, generating hot plasma at a million degrees which then shone brightly in X-rays.

The telescopes recorded a four-fold increase in energy compared with the normal X-ray emission seen when the stars were further apart on their elliptical orbit.

“This is the first time that we have found clear evidence for colliding winds in this system,” says Yael Nazé of the Université de Liège, Belgium, and lead author of the paper describing the results reported in Astronomy & Astrophysics.

“We only have a few other examples of winds in binary systems crashing together, but this one example can really be considered an archetype for this phenomenon.”

Unlike the handful of other colliding wind systems, the style of the collision in Cyg OB2 #9 remains the same throughout the stars’ orbit, despite the increase in intensity as the two winds meet.

“In other examples the collision is turbulent; the winds of one star might crash onto the other when they are at their closest, causing a sudden drop in X-ray emission,” says Dr Nazé.

“But in the Cyg OB2 #9 system there is no such observation, so we can consider it the first ‘simple’ example that has been discovered – that really is the key to developing better models to help understand the characteristics of these powerful stellar winds. ”

“This particular binary system represents an important stepping stone in our understanding of stellar wind collisions and their associated emissions, and could only be achieved by tracking the two stars orbiting around each other with X-ray telescopes,” adds ESA’s XMM-Newton project scientist Norbert Schartel.

Read the team’s paper: The 2.35 year itch of Cyg OB2 #9 – I. Optical and X-ray monitoring

NASA press release

Young Star Cluster In Disintegrated Galaxy Reveals First-Ever Intermediate Mass Black Hole

[/caption]

Score another first for NASA’s Hubble Space Telescope! Along with observations taken with the Swift X-ray telescope, a team of astronomers have identified a young stellar cluster of stars pointing the way towards the first verified intermediate mass black hole. This grouping of stars provides significant indication that black holes of this type may have been at the center of a now shredded dwarf galaxy – a finding which increases our knowledge of galaxy evolution.

“For the first time, we have evidence on the environment, and thus the origin, of this middle-weight black hole,” said Mathieu Servillat, a member of the Harvard-Smithsonian Center for Astrophysics research team.

Designated as ESO 243-49 HLX-1, this incredible intermediate mass black hole was discovered in 2009 by Sean Farrell, of the Sydney Institute for Astronomy in Australia, using the European Space Agency’s XMM-Newton X-ray space telescope. Hyper-Luminous X-ray Source 1 is a 20,000 solar mass beauty which resides at the edge of galaxy ESO 243-49 some 290 million light years away. However, the Newton’s findings weren’t the only contribution – HLX-1 was also verified with NASA’s Swift observatory in X-ray and Hubble in near-infrared, optical, and ultraviolet wavelengths. What stands out is the presence of a cluster of young stars encircling the black hole and stretching out across about 250 light years of space. While the stars themselves are too far away to be resolved, their magnitude and spectra match with other young clusters seen in similar galaxies.

Just what clued the team to the presence of a star cluster? In this case their instruments revealed the blue spectrum of hot gases being emitted from the accretion disk located at the periphery of the black hole… and there was more. They also noted the presence of red light spawned by cooler gases which may indicate the presences of stars. Time to match up the findings against computer modeling.

“What we can definitely say with our Hubble data is that we require both emission from an accretion disk and emission from a stellar population to explain the colors we see.” said Farrell.

Why is the presence of a young star cluster unusual? According to what we know so far, they just don’t occur outside a flattened disk such as HLX-1. This finding may indicate the intermediate mass black hole may have once been at the heart of a dwarf galaxy engaged in a merger event. The dwarf galaxy’s stars were stripped away, but not its capabilities to form new. During the interaction, the gas around the black hole was compressed and star formation began again… but how long ago?

“The age of the population cannot be uniquely constrained, with both very young and very old stellar populations allowed. However, the very old solution requires excessively high levels of disc reprocessing and an extremely small disc, leading us to favour the young solution with an age of ~13 Myr.” says the team. “In addition, the presence of dust lanes and the lack of any nuclear activity from X-ray observations of the host galaxy lead us to propose that a gas-rich minor merger may have taken place less than ~200 Myr ago. Such a merger event would explain the presence of the intermediate mass black hole and support a young stellar population.”

Discoveries such as HLX-1 will help astronomers further understand how supermassive black holes are formed. Current conjecture is that intermediate mass black holes may migrate together to form their larger counterparts. Studying the trajectory of this new find may provide valuable information… even if it is unknown at this point. HLX-1 may be drawn into a merger event and it may just end up orbiting ESO 243-49. Regardless of what happens, chances are it will fade away in X-ray as it exhausts its gas supply.

“This black hole is unique in that it’s the only intermediate-mass black hole we’ve found so far. Its rarity suggests that these black holes are only visible for a short time,” said Servillat.

Original Story Source: Harvard Center for Astrophysics News Release. For Further Reading: A Young Massive Stellar Population Around the Intermediate Mass Black Hole ESO 243-49 HLX-1.

The Eagle Nebula as You’ve Never Seen it Before

[/caption]

Here’s a stunning new look deep inside the iconic “Pillars of Creation.” As opposed to the famous Hubble Space Telescope image (below) — which shows mainly the surface of the pillars of gas and dust — this composite image from ESA’s Herschel Space Observatory in far-infrared and XMM-Newton telescope in X-rays allows astronomers to peer inside the pillars and see more detail of the structures in this region. It shows how the hot young stars detected by the X-ray observations are carving out cavities, sculpting and interacting with the surrounding ultra-cool gas and dust.

But enjoy the view while you can. The sad part is that likely, this beautiful region has already been destroyed by a supernova 6,000 years ago. But because of the distance, we haven’t seen it happen yet.

Gas Pillars in the Eagle Nebula
Gas Pillars in the Eagle Nebula, as seen by the Hubble Space Telescope. Credit: NASA/ESA/STScI, Hester & Scowen (Arizona State University)

The Eagle Nebula is 6,500 light-years away in the constellation of Serpens. It contains a young hot star cluster, NGC6611, which is visible with modest back-yard telescopes. This cluster is sculpting and illuminating the surrounding gas and dust, resulting in a huge hollowed-out cavity and pillars, each several light-years long.

The Hubble image hinted at new stars being born within the pillars, deep inside small clumps known as ‘evaporating gaseous globules’ or EGGs, but because of the obscuring dust, Hubble’s visible light picture was unable to see inside and prove that young stars were indeed forming.

The new image shows those hot young stars are responsible for carving the pillars.

The new image also uses data from near-infrared images from the European Southern Observatory’s (ESO’s) Very Large Telescope at Paranal, Chile, and visible-light data from its Max Planck Gesellschaft 2.2m diameter telescope at La Silla, Chile. All the individual images are below:

M16 seen in several different wavelengths. Credits: far-infrared: ESA/Herschel/PACS/SPIRE/Hill, Motte, HOBYS Key Programme Consortium; ESA/XMM-Newton/EPIC/XMM-Newton-SOC/Boulanger; optical: MPG/ESO; near-infrared/VLT/ISAAC/McCaughrean & Andersen/AIP/ESO

Earlier mid-infrared images from ESA’s Infrared Space Observatory and NASA’s Spitzer, and the new XMM-Newton data, have led astronomers to suspect that one of the massive, hot stars in NGC6611 may have exploded in a supernova 6,000 years ago, emitting a shockwave that destroyed the pillars. But we won’t see the destruction for several hundred years yet.

Source: ESA

X-rays Unwrap a Poky Little Pulsar

[/caption]

For the first time astronomers have located a pulsar – the super-dense, spinning remains of a star – nestled within the remnants of a supernova in the Small Magellanic Cloud. The image above, a composite of x-ray  and optical light data acquired by NASA’s Chandra Observatory and ESA’s XMM-Newton, shows the pulsar shining brightly on the right surrounded by the ejected outer layers of its former stellar life.

The optically-bright area on the left is a large star-forming region of dust and gas nearby SXP 1062.

A pulsar is a neutron star that emits high-energy beams of radiation from its magnetic poles. These poles are not always aligned with its axis of rotation, and so the beams swing through space as the neutron star spins. If the Earth happens to be in direct line with the beams at some point along their path, we see them as rapidly flashing radiation sources… sort of like a cosmic lighthouse on overdrive.

What’s unusual about this pulsar – called SXP 1062 – is its slow rate of rotation. Its beams spin around at a rate of about once every 18 minutes, which is downright poky for a pulsar, most of which spin several times a second.

X-ray image of SXP 1062

This makes SXP 1062 one of the slowest known pulsars discovered within the Small Magellanic Cloud, a dwarf galaxy cruising alongside our own Milky Way about 200,000 light-years distant.

The supernova that presumably created the pulsar and its surrounding remnant wrapping is estimated to have taken place between 10,000 and 40,000 years ago – relatively recently, by cosmic standards. To see a young pulsar spinning so slowly is extra unusual since younger pulsars have typically been observed to have rapid rotation rates. Understanding the cause of its leisurely pace will be the next goal for SXP 1062 researchers.

Read more about SXP 1062on the Chandra photo album page.

 

Image credit: X-ray & Optical: NASA/CXC/Univ.Potsdam/L.Oskinova et al.

Space Telescopes Provide New Look at 2,000 Year Old Supernova

[/caption]

What caused a huge explosion nearly 2,000 years ago, seen by early Chinese astronomers? Scientists have long known that a “guest star” that had mysteriously appeared in the sky and stayed for about 8 months in the year 185 was the first documented supernova. But now the combined efforts of four space observatories have provided insight into this stellar explosion and why it was so huge – and why its shattered remains — the object known as RCW 86 – is now spread out to great distances.

“This supernova remnant got really big, really fast,” said Brian Williams, an astronomer at North Carolina State University in Raleigh. “It’s two to three times bigger than we would expect for a supernova that was witnessed exploding nearly 2,000 years ago. Now, we’ve been able to finally pinpoint the cause.”

By studying new infrared observations from the Spitzer Space Telescope and data from the Wide-field Infrared Survey Explorer, and previous data from NASA’s Chandra X-ray Observatory and the European Space Agency’s XMM-Newton Observatory, astronomers were able to determine that the ancient supernova was a Type Ia supernova. And doing some “forensics” on the stellar remains, the astronomers could piece together that prior to exploding, winds from the white dwarf cleared 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. The ejected material would have traveled into the cavity, unimpeded by gas and dust and spread out quickly.

This is the first time that astronomers have been able to deduce that this type of cavity was created, and scientists say the results may have significant implications for theories of white-dwarf binary systems and Type Ia supernovae.

At about 85 light-years in diameter, RCW occupies a region of the sky that is slightly larger than the full moon. It lies in the southern constellation of Circinus.

Source: JPL