NASASpaceFlight.com Forum
Robotic Spacecraft (Astronomy, Planetary, Earth, Solar/Heliophysics) => Space Science Coverage => Topic started by: jacqmans on 04/23/2007 01:33 pm
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Warm gas escaping from the clutches of enormous black holes could be the key to a form of intergalactic 'pollution' that made life possible, according to new results from ESA's XMM-Newton space observatory, published today.
More at:
http://www.esa.int/esaSC/SEMDV2MJC0F_index_0.html
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The orbiting X-ray telescopes XXM-Newton and Chandra have caught a pair of galaxy clusters merging into a giant cluster. The discovery adds to existing evidence that galaxy clusters can collide faster than previously thought.
More at:
http://www.esa.int/esaSC/SEMHOPNSP3F_index_0.html
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Astronomers using XMM-Newton and Suzaku have seen Einstein's predicted distortion of space-time and pioneered a ground-breaking technique for determining the properties of neutron stars.
Full story:
http://www.esa.int/esaSC/SEMPJXE1P5F_index_0.html
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Right in time for the festive season, ESA's XMM-Newton X-ray observatory has discovered a huge cloud of high-temperature gas resting in a spectacular nearby star-forming region, shaped somewhat like the silhouette of Santa Claus.
Read more at:
http://www.esa.int/esaSC/SEMOCI73R8F_index_0.html
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XMM-Newton gives new insight into neutron stars
8 January 2008
XMM-Newton has given astronomers and physics a valuable new insight into the most exotic stars in the Universe. Known as neutron stars, the composition of these extremely dense stellar objects has always been something of a puzzle. Now, XMM-Newton has revealed that they almost certainly resemble over-sized atomic nuclei.
http://www.esa.int/esaCP/SEMHDX2MDAF_index_0.html
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XMM-Newton has been surprised by a rare type of galaxy, from which it has detected a higher number of X-rays than thought possible. The observation gives new insight into the powerful processes shaping galaxies during their formation and evolution.
Read more at:
http://www.esa.int/esaSC/SEMDHJXMMEF_index_0.html
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Detective astronomers unearth hidden celestial gem
10 June 2008
ESA's orbiting X-ray observatory XMM-Newton has re-discovered an ignored celestial gem. The object in question is one of the youngest and brightest supernova remnants in the Milky Way, the corpse of a star that exploded around 1000 years ago.
http://www.esa.int/esaCP/SEM1OPUG3HF_index_0.html
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XMM-Newton discovers the star that everyone missed
18 July 2008
XMM-Newton has discovered an exploding star in the Milky Way. Usually that would be important in itself, but this time there is a special twist. Calculations show that the explosion must have been clearly visible to the unaided eye but was missed by the legions of star watchers around the planet.
http://www.esa.int/esaSC/SEMH9HWIPIF_index_0.html
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XMM-Newton's massive discovery
25 August 2008
ESA's orbiting X-ray observatory XMM-Newton has discovered the most massive cluster of galaxies seen in the distant Universe until now. The galaxy cluster is so big that there can only be a handful of them at that distance, making this a rare catch indeed. The discovery confirms the existence of dark energy.
http://asimov.esrin.esa.int/esaCP/SEMY70XIPIF_index_0.html
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XMM-Newton has caught the fading glow of a tiny celestial object, revealing its rotation rate for the first time. The new information confirms this particular object as one of an extremely rare class of stellar zombie - each one the dead heart of a star that refuses to die.
More at:
http://www.esa.int/esaCP/SEMAD2UTGOF_index_0.html
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Using new data from ESA's XMM-Newton spaceborne observatory, astronomers have probed closer than ever to a supermassive black hole lying deep at the core of a distant active galaxy.
More at:
http://www.esa.int/esaCP/SEMTIX0OWUF_index_0.html
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Astronomers using ESA's XMM-Newton X-ray observatory have discovered a black hole weighing more than 500 solar masses, a missing link between lighter stellar-mass and heavier supermassive black holes, in a distant galaxy. This discovery is the best detection to date of a new class that has long been searched for: intermediate mass black holes.
More at:
http://www.esa.int/esaCP/SEMZGM1P0WF_index_0.html
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ESA's XMM-Newton orbiting X-ray telescope has uncovered a celestial Rosetta stone: the first close-up of a white dwarf star, circling a companion star, that could explode into a particular kind of supernova in a few million years. These supernovae are used as beacons to measure cosmic distances and ultimately understand the expansion of our Universe.
More at:
http://www.esa.int/esaCP/SEM4F8LW3ZF_index_0.html
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ESA's XMM-Newton X-ray observatory is celebrating its 10th anniversary. During its decade of operation, this remarkable space observatory has supplied new data for every aspect of astronomy. From our cosmic backyard to the further reaches of the Universe, XMM-Newton has changed the way we think of space.
More at:
http://www.esa.int/esaCP/SEMX6X6JT2G_index_0.html
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Are most pulsars really magnetars in disguise?
Astronomers using XMM-Newton and other world-class X-ray telescopes have probed a curious source, which emits flares and bursts just like a magnetar but lacks the extremely high external magnetic field typical of these objects. The detection of this source, which could be powered by a strong, internal magnetic field hidden to observations, may mean that many 'ordinary' pulsars are dormant magnetars waiting to erupt.
Massive stars remain objects of curiosity even well after their demise. Ending their lives in dramatic fashion, as supernova explosions, they leave a very dense and compact remnant behind - a neutron star or a black hole, depending on the mass of the star. These remnants, characterised by intense gravitational fields, are the source of some extremely energetic events and give rise to a variety of interesting phenomena which can be observed throughout the entire electromagnetic spectrum.
Neutron stars, in particular, derive from the collapse of stars originally as massive as 8 to 25 times the mass of the Sun and they harbour magnetic fields a million times stronger than the strongest ones ever produced on Earth. Spinning neutron stars can be observed as pulsating sources -hence the name, pulsars- with exceptionally short periods, ranging from about one thousandth of a second to ten seconds. Powerful beams of electromagnetic radiation are created by jets of energetic particles that stream out above the magnetic poles of the star; the 'blinking' effect arises because the pulsar's magnetic dipole is not always aligned with its axis of rotation. Young pulsars rotate extremely fast but release rotational energy and slow down as they age: older pulsars have thus longer periods than younger ones. By measuring the rate at which a pulsar spins down it is possible to estimate the intensity of its surface dipolar magnetic field.
Magnetars are a special class of pulsars that stand out from the crowd because of their striking characteristics: they have long rotations periods, occasionally undergo episodes of extremely enhanced emission (about 10–100 times the usual value) and produce intense, short bursts of X-rays and gamma-rays.
"Ordinary pulsars are powered by their rotation. The extreme events observed in magnetars, instead, require an additional energy reservoir, believed to reside in a particularly strong magnetic field," says Nanda Rea from the CSIC - Institute of Space Sciences in Barcelona, Spain, who led the study which is to be published in the journal, Science. "Thus far, 15 magnetars were identified, all of them exhibiting extraordinarily high values of the surface dipolar magnetic field," she adds.
All of these magnetars have magnetic fields of about 1014–1015 Gauss, hundreds to thousands of times stronger than those detected in ordinary pulsars. The object of the study of Rea and collaborators, a source called SGR 0418+5729, appears to challenge this trend. "Surprisingly, SGR 0418+5729 behaves just like a magnetar, with a period of about 9 seconds and evidence of intense X-ray bursts, but its magnetic field is not remotely as strong as a magnetar's. In fact, it is of the same order as that of an ordinary pulsar's magnetic field," explains Rea.
Astronomers monitored SGR 0418+5729 for several months employing virtually all available X-ray telescopes, including XMM-Newton, Chandra, RXTE and Swift, in order to achieve the most complete coverage possible.
"The use of XMM-Newton was particularly beneficial in this context," comments Norbert Schartel, XMM-Newton Project Scientist. "Its large effective area allows observations to be performed at high sensitivity, which translates into a very precise estimate of the period of the source."
After months of observations with a series of world-class telescopes, no sign of variation in the period of SGR 0418+5729 was recorded. This allowed astronomers to place only an upper limit on its dipolar magnetic field, which must be smaller than 7.5 x 1012 Gauss. With such a weak magnetic field, what can be powering the intense bursts and the overall magnetar-like behaviour of this puzzling source?
"Astronomical measurements are only sensitive to the dipolar magnetic field of a pulsar," explains co-author Sandro Mereghetti from INAF-IASF in Milan, Italy. "However, SGR 0418+5729 could conceal a strong magnetic field in its interior, which would cause the bursts and extreme emission but remain unnoticed by any observations,” he adds.
If this scenario proves to be true, it would dramatically change the standard picture astronomers have regarding magnetars, lifting the curtain on a large population of pulsars with a broad range of magnetic field values. "This would mean that many sources, currently classified as 'ordinary' pulsars, could turn on as magnetars at any time, regardless of the surface dipolar magnetic field we measure," comments Rea.
In order to assess that, more observations of SGR 0418+5729 have to be performed. Depending on whether its spin-down rate is close to the current limit or is much lower than it, anything from a few months up to a few years of careful monitoring will be needed before a firm estimate of the surface magnetic field can be obtained. If this turns out to be significantly lower than the current limit, then the entire magnetar scenario might need to be revised.
"The new framework affects also our theoretical understanding of supernova explosions that lead to the formation of neutron stars," says Mereghetti. In order to produce a remnant with such a strong inner magnetic field, explosions must be more powerful than those currently accounted for. Such scenarios could also lead to intense emission of gravitational waves.
"We are eager to perform further observations of this baffling object and to determine whether it actually represents the norm or the exception," Rea concludes.
Related publications
Rea, N., et al., "A low-magnetic field Soft Gamma Repeater", Science Express, published online 14 October 2010. DOI: 10.1126/science.1196088
Notes for editors
SGR 0418+5729 was discovered on 5 June 2009 by the Fermi Gamma-ray Burst Monitor (GBM), which recorded two magnetar-like bursts of hard X-rays. Follow-up observations were conducted for 160 days with several X-ray satellites in order to monitor the source and measure its period. These observations are necessary to estimate the rate at which the object possibly spins down and, from this, to derive the value of the dipolar magnetic field.
For the first 160 days of observations, SGR 0418+5729 showed no sign of variations in the rotation period. After that, SGR 0418+5729 could not be monitored for a while because its position on the sky was too close to the Sun's.
An extensive monitoring of SGR 0418+5729, involving XMM-Newton, Swift, and Chandra, began on 9 July 2010. The current estimate of the period, based on a best fit to all data, is P=9.07838827 seconds.
To date, no variation of the period has been detected; the upper limit is of P_dot<6.0 x 10-15, which translates into a surface dipolar magnetic field B< 7.5 x 1012 Gauss.
http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=47844
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Neutron star bites off more than it can chew
28 June 2011
ESA’s XMM-Newton space observatory has watched a faint star flare up at X-ray wavelengths to almost 10 000 times its normal brightness. Astronomers believe the outburst was caused by the star trying to eat a giant clump of matter.
http://www.esa.int/esaCP/SEMWVL3TBPG_index_0.html
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ESA spacecraft reveal new anatomy around a black hole
29 September 2011
A fleet of spacecraft including ESA's XMM-Newton and Integral have shown unprecedented details close to a supermassive black hole. They reveal huge 'bullets' of gas being driven away from the 'gravitational monster'.
The black hole that the team chose to study lies at the heart of the galaxy Markarian 509, 500 million light years away in space. This black hole is colossal, containing 300 million times the mass of the Sun and growing more massive every day as it continues to feed.
Markarian 509 was chosen because it is known to vary in brightness, which indicates that the flow of matter into the black hole is turbulent. The radiation from this inner region then drives an outflow of some gas away from the black hole.
http://www.esa.int/esaCP/SEMAQQ6UXSG_index_0.html
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Strangely slow pulsar discovered nestled in young supernova remnant
20 Dec 2011
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.
http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=49784
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XMM-Newton measures the power of black-hole driven outflows in galaxies
27 Feb 2012
Astronomers using ESA's XMM-Newton X-ray Observatory have discovered that ultra-fast outflows are quite common in active galaxies. About 40 per cent of the sources in their sample show outflows that arise from the vicinity of the central black holes. By estimating the mass and energy released by the outflows, the astronomers have identified them as major agents in the feedback processes required by models of galactic evolution to explain the observed correlation between the mass of black holes and the stellar content of their host galaxies.
http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=50097
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XMM-Newton reveals light 'echo' around supermassive black hole
31 May 2012
Astronomers studying the galaxy NGC 4151 with ESA's XMM-Newton space observatory have detected X-rays emitted and then reflected by ionised iron atoms very close to the supermassive black hole hosted at the galaxy's core. By measuring the time delays occurring in these 'reverberation' events, they were able to map the vicinity of this black hole in unprecedented detail.
http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=50408
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X-raying the beating heart of a newborn star
03 Jul 2012
An international team of scientists has used the world's most powerful X-ray observatories - including ESA's XMM-Newton orbiter - to probe the dusty surroundings of a newborn star and discover some of its innermost secrets. These findings shed new light on one of the most fundamental processes in the Universe, the creation of stars.
http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=50462
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Final cry of disrupted star points to site of oblivion
03 Aug 2012
Astronomers have detected tell-tale luminosity fluctuations in the X-ray signal from a star that was torn apart and devoured by the supermassive black hole at the centre of a distant galaxy. The fluctuations, which have a period of 200 seconds, originate from the innermost stable orbit around the black hole and represent the last signal sent by the debris of the disrupted star before disappearing beyond the black hole's event horizon. The discovery, based on data from ESA's XMM-Newton and the Japan/US Suzaku space observatories, has allowed astronomers to probe the details of matter accretion onto a supermassive black hole in the distant Universe for the first time.
http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=50638
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Aftermath of a stellar explosion
13 August 2012
Suspended in time and space, the aftermath of a massive star’s dramatic ending in a supernova explosion is captured by ESA’s XMM-Newton space observatory.
http://www.esa.int/export/esaSC/SEMHODYXP5H_index_0.html
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XMM-Newton Announcement of Opportunity (AO-12)
21 Aug 2012
Proposals are solicited for observations with XMM-Newton in response to the twelfth Announcement of Opportunity, AO-12, issued 21 August 2012. This AO covers the period May 2013 to April 2014 and is open to proposers from all over the world.
http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=50672
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X-raying stellar winds in a high-speed collision
12 October 2012
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.
http://www.esa.int/esaSC/SEM3H93S18H_index_0.html
http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=50904
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Fire burn and cauldron bubble
A giant bubble blown by the massive Wolf-Rayet star HD 50896, the pink star in the centre of the image.
X-ray data from XMM-Newton’s EPIC camera are shown in blue, while optical images were acquired using the Michigan Curtis Schmidt Telescope at Cerro Tololo Inter-American Observatory (CTIO) and presented in red (H-alpha) and green (OIII).
The bubble, known as S 308, is about 60 light-years across and is located 5000 light-years away in the constellation of Canis Major.
Credits: ESA, J. Toala & M. Guerrero (IAA-CSIC), Y.-H. Chu & R. Gruendl (UIUC), S. Arthur (CRyA–UNAM), R. Smith (NOAO/CTIO), S. Snowden (NASA/GSFC) and G. Ramos-Larios (IAM)
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Weakling magnetar reveals hidden strength
14 August 2013
Astronomers using ESA's XMM-Newton have measured the magnetic field in a small surface feature of a magnetar - a highly magnetised pulsar - for the first time. Until now, only the dipolar magnetic field of magnetars had been measured. With a new technique, the astronomers have now revealed a strong, localised surface magnetic field in the magnetar that had the lowest measured dipolar field. The discovery yields conclusive proof that magnetars conceal some of the strongest magnetic fields in the Universe.
http://sci.esa.int/xmm-newton/52772-weakling-magnetar-reveals-hidden-strength/
Image credit: ESA/ATG medialab
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Volatile pulsar reveals millisecond missing link
25 September 2013
For the first time, astronomers have caught a pulsar in a crucial transitional phase that explains the origin of the mysterious millisecond pulsars. These pulsars spin much faster than expected for their old age, and astronomers believe their rotation receives a boost as they accrete matter in a binary system. The newly found pulsar swings back and forth between accretion-powered X-ray emission and rotation-driven radio emission, bringing conclusive evidence for their 'rejuvenation'. The discovery was made possible by the coordinated efforts of ESA's two missions that scan the high-energy sky: INTEGRAL and XMM-Newton.
http://sci.esa.int/integral/52866-volatile-pulsar-reveals-millisecond-missing-link/
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Unravelling the Cosmic Web: Survey gives insights into Universe's structure
15 December 2015
Today marks the release of the first papers to result from the XXL survey, the largest survey of galaxy clusters ever undertaken, carried out with ESA's XMM-Newton X-ray observatory. The gargantuan clusters of galaxies surveyed are key features of the large-scale structure of the Universe and to better understand them is to better understand this structure and the circumstances that led to its evolution. The first results from the survey, published in a special issue of Astronomy and Astrophysics, hint at the answers and surprises that are captured in this unique bank of data and reveal the true potential of the survey.
http://sci.esa.int/xmm-newton/57031-unravelling-the-cosmic-web-survey-gives-insights-into-universes-structure/
Image credit: ESA/XMM-Newton/XXL survey consortium
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Andromeda's pulsing neutron star
Andromeda, or M31, is a spiral galaxy similar to our own Milky Way. For the first time, a spinning neutron star has been inferred in XMM-Newton data.
Related article: Andromeda's first spinning neutron star (http://sci.esa.int/xmm-newton/57661-found-andromeda-s-first-spinning-neutron-star/)
Image credit: Andromeda: ESA/Herschel/PACS/SPIRE/J. Fritz, U. Gent/XMM-Newton/EPIC/W. Pietsch, MPE; data: P. Esposito et al. (2016)
http://sci.esa.int/xmm-newton/57662-andromedas-pulsing-neutron-star/
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Space selfie
Launched on 10 December 1999, XMM-Newton is an X-ray observatory designed to investigate some of the most violent phenomena in the Universe. Sources that emit large amounts of X-rays include remnants of supernova explosions and the surroundings of black holes.
Detecting this energetic radiation is a daunting endeavour, requiring techniques that are greatly different from those used in traditional telescopes. In the case of XMM-Newton, it carries three telescopes of 58 nested mirrors each. These sit at one end of a 7 m-long tube, while at the other end are the scientific instruments at the focus.
The two images in this collage were taken by the two low-resolution monitoring cameras mounted on opposite sides of the focal plane assembly, looking along the pointing direction of the telescope tube towards the service module (see below for an annotated version with explanation).
The cameras were originally used by controllers to check how the solar wings unfolded after launch, and have remained dormant since 2003.
When these images were captured on 14 September 2016 at 06:50 GMT, XMM-Newton was in its 3070th orbit at around 50 000 km altitude and in contact with mission controllers at ESA’s mission control in Darmstadt, Germany, via the antenna at Kourou, French Guiana.
http://www.esa.int/spaceinimages/Images/2016/12/Space_selfie
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The brightest furthest pulsar in the Universe
21 February 2017
ESA's XMM-Newton has found a pulsar – the spinning remains of a once-massive star – that is a thousand times brighter than previously thought possible.
The pulsar is also the most distant of its kind ever detected, with its light travelling 50 million light-years before being detected by XMM-Newton.
http://sci.esa.int/xmm-newton/58817-the-brightest-furthest-pulsar-in-the-universe/
Image credit: ESA/XMM-Newton; NASA/Chandra and SDSS
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WHERE IS THE UNIVERSE'S MISSING MATTER?
18 April 2018
Astronomers using ESA's XMM-Newton space observatory have probed the gas-filled haloes around galaxies in a quest to find 'missing' matter thought to reside there, but have come up empty-handed – so where is it?
http://sci.esa.int/xmm-newton/60173-where-is-the-universes-missing-matter/
Image credit: ESA/XMM-Newton; J-T. Li (University of Michigan, USA); Sloan Digital Sky Survey (SDSS)
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20 years in space next year, and still running, and still productive. Must be ESA longest mission ever, by a large margin.
It is really ESA very own Hubble, albeit a little less glamourous.
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Just wondering, why this and some other ESA, and possibly other, mission are not in space science section?
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Because the section didn't exist when old mission threads were created. Moved to its appropriate section.
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Not even NSF existed when it was launched. Well, Internet itself had barely happened when it launched... (was in high school back then. Is that so far away ? :o )
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20 years in space next year, and still running, and still productive. Must be ESA longest mission ever, by a large margin.
It is really ESA very own Hubble, albeit a little less glamourous.
ESAs Integral https://en.wikipedia.org/wiki/INTEGRAL (https://en.wikipedia.org/wiki/INTEGRAL) was launched in 2002 and is still operating, so I don't know that Xmm stands out particularly by its lifetime.
And if you allow joint missions then SOHO was built by European partners, launched in 1995, and still working.
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COSMIC BLAST TAKES REST AT LAST
31 May 2018
Last year, the first detection of gravitational waves linked to a gamma-ray burst triggered a vast follow-up campaign with ground and space telescopes to study the aftermath of the neutron star merger that gave rise to the explosion. ESA's XMM-Newton observations, obtained a few months after the discovery, caught the moment when its X-ray emission stopped increasing, opening new questions about the nature of this peculiar source.
http://sci.esa.int/xmm-newton/60376-cosmic-blast-takes-rest-at-last/
Image credit: ESA/XMM-Newton; P. D'Avanzo (INAF–Osservatorio Astronomico di Brera)
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STAR SHREDDED BY RARE BREED OF BLACK HOLE
18 June 2018
ESA's XMM-Newton observatory has discovered the best-ever candidate for a very rare and elusive type of cosmic phenomenon: a medium-weight black hole in the process of tearing apart and feasting on a nearby star.
There are various types of black hole lurking throughout the Universe: massive stars create stellar-mass black holes when they die, while galaxies host supermassive black holes at their centres, with masses equivalent to millions or billions of Suns.
Lying between these extremes is a more retiring member of the black hole family: intermediate-mass black holes. Thought to be seeds that will eventually grow to become supermassive, these black holes are especially elusive, and thus very few robust candidates have ever been found.
Now, a team of researchers using data from ESA's XMM-Newton X-ray space observatory, as well as NASA's Chandra X-Ray Observatory and Swift X-Ray Telescope, has found a rare telltale sign of activity. They detected an enormous flare of radiation in the outskirts of a distant galaxy, thrown off as a star passed too close to a black hole and was subsequently devoured.
http://sci.esa.int/xmm-newton/60424-star-shredded-by-rare-breed-of-black-hole/
Image credit: ESA/XMM-Newton/UNH/D.Lin et al; Acknowledgement: NASA/CXC
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XMM-NEWTON FINDS MISSING INTERGALACTIC MATERIAL
20 June 2018
After a nearly twenty-year long game of cosmic hide-and-seek, astronomers using ESA's XMM-Newton space observatory have finally found evidence of hot, diffuse gas permeating the cosmos, closing a puzzling gap in the overall budget of 'normal' matter in the Universe.
http://sci.esa.int/xmm-newton/60427-xmm-newton-finds-missing-intergalactic-material/
Image credit: ESA
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FLARING SOURCE IN NGC 6540
A peculiar X-ray source spotted in the globular cluster NGC 6540 as part of a collaboration between scientists at the National Institute of Astrophysics (INAF) in Milan, Italy, and a group of students from a local high school.
In 2005, ESA's XMM-Newton saw this source undergo a flare that boosted the luminosity of the source by up to 50 times its normal level for about five minutes.
Too short to be an ordinary stellar flare, but too faint to be linked to a compact object, this event is challenging our understanding of X-ray outbursts.
- Related article: Students digging into data archive spot mysterious X-ray source (http://sci.esa.int/xmm-newton/60533-students-digging-into-data-archive-spot-mysterious-x-ray-source/)
http://sci.esa.int/xmm-newton/60535-flaring-source-in-ngc-6540/
Image credit: ESA/XMM-Newton; A. De Carlo (INAF)
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TRACING THE UNIVERSE: X-RAY SURVEY SUPPORTS STANDARD COSMOLOGICAL MODEL
04 October 2018
Scanning the sky for X-ray sources, ESA's XMM-Newton X-ray observatory has been busy with the XXL Survey, its largest observational programme to date. The second batch of data from the survey has just been released, including information on 365 galaxy clusters, which trace the large-scale structure of the Universe and its evolution through time, and on 26 000 active galactic nuclei (AGN).
By examining two large regions of the sky at great sensitivity, this is the first X-ray survey to detect enough galaxy clusters and AGN in contiguous volumes of space to make it possible for scientists to map the distribution of these objects out to the distant Universe in unprecedented detail. The results are compatible with expectations from the currently-accepted cosmological model.
http://sci.esa.int/xmm-newton/60686-tracing-the-universe-x-ray-survey-supports-standard-cosmological-model/
Credits: ESA/XMM-Newton/XXL Survey and CFHT Legacy Survey/CTIO/XXL Survey
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FROM GAMMA RAYS TO X-RAYS: NEW METHOD PINPOINTS PREVIOUSLY UNNOTICED PULSAR EMISSION
21 November 2018
Based on a new theoretical model, a team of scientists explored the rich data archive of ESA's XMM-Newton and NASA's Chandra space observatories to find pulsating X-ray emission from three sources. The discovery, relying on previous gamma-ray observations of the pulsars, provides a novel tool to investigate the mysterious mechanisms of pulsar emission, which will be important to understand these fascinating objects and use them for space navigation in the future.
http://sci.esa.int/xmm-newton/60950-from-gamma-rays-to-x-rays-new-method-pinpoints-previously-unnoticed-pulsar-emission/
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ACTIVE GALAXIES POINT TO NEW PHYSICS OF COSMIC EXPANSION
28 January 2019
Investigating the history of our cosmos with a large sample of distant 'active' galaxies observed by ESA's XMM-Newton, a team of astronomers found there might be more to the early expansion of the Universe than predicted by the standard model of cosmology.
According to the leading scenario, our Universe contains only a few percent of ordinary matter. One quarter of the cosmos is made of the elusive dark matter, which we can feel gravitationally but not observe, and the rest consists of the even more mysterious dark energy that is driving the current acceleration of the Universe's expansion.
This model is based on a multitude of data collected over the last couple of decades, from the cosmic microwave background, or CMB – the first light in the history of the cosmos, released only 380 000 years after the big bang and observed in unprecedented detail by ESA's Planck mission – to more 'local' observations. The latter include supernova explosions, galaxy clusters and the gravitational distortion imprinted by dark matter on distant galaxies, and can be used to trace cosmic expansion in recent epochs of cosmic history – across the past nine billion years.
A new study, led by Guido Risaliti of Universitŕ di Firenze, Italy, and Elisabeta Lusso of Durham University, UK, points to another type of cosmic tracer – quasars – that would fill part of the gap between these observations, measuring the expansion of the Universe up to 12 billion years ago.
http://sci.esa.int/xmm-newton/61068-active-galaxies-point-to-new-physics-of-cosmic-expansion/
Image credit: Elisabeta Lusso & Guido Risaliti
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XMM-Newton discovers galactic ‘chimneys’ – annotated
Artist’s impression of two ‘chimneys’ funneling hot, X-ray emitting material from the centre of our Galaxy into two huge cosmic bubbles.
The two galactic chimneys were revealed using data collected between 2016 and 2018 by ESA’s XMM-Newton space observatory, which completed the most extensive X-ray map ever made of the Milky Way’s core.
The giant, gamma-ray emitting bubbles had been discovered by NASA’s Fermi Gamma-ray Space Telescope. They form a shape akin to a colossal hourglass, spanning about 50 000 light years from end to end – comparable to the size of the Milky Way’s stellar disc, and to around half the diameter of the entire Galaxy.
The two hot channels found by XMM-Newton stream outwards from Sagittarius A*, our Galaxy’s central supermassive black hole, and extend each for hundreds of light years, finally linking the immediate surroundings of the black hole and the bubbles together. Scientists think that these ‘chimneys’ act as a set of exhaust pipes through which energy and mass are transported from our Galaxy’s heart out to the base of the bubbles, replenishing them with new material.
More information: Giant ‘chimneys’ vent X-rays from Milky Way’s core (http://sci.esa.int/xmm-newton/61230-giant-chimneys-vent-x-rays-from-milky-way-core/)
https://www.esa.int/spaceinimages/Images/2019/03/XMM-Newton_discovers_galactic_chimneys_annotated
Image credit: ESA/XMM-Newton/G. Ponti et al. 2019; ESA/Gaia/DPAC (Milky Way map)
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Black hole at the core of distant galaxy periodically brightens up
An X-ray view of the active black hole at the core of distant galaxy GSN 069, about 250 million light years away, based on data from ESA’s XMM-Newton X-ray observatory. The upper part of the animation shows the actual observations, and the graph in the lower part shows variations of the X-ray brightness of the source relative to its ‘dormant’ level.
This animation is based on nearly 40 hours of observations of this source, which undergoes never-before-seen flashes – dubbed ‘quasi-periodic eruptions’, or QPEs – every nine hours. The sequence has been speeded up for illustration purposes; each frame corresponds to about three minutes of actual XMM-Newton exposure time.
These flares were first detected on 24 December 2018, when the source was observed to suddenly increase its brightness by up to a factor 100, then dimmed back to its normal levels within one hour and lit up again nine hours later.
Although never before observed, scientists think periodic flares like these might actually be quite common in the Universe.
Related article: Unexpected periodic flares may shed light on black hole accretion (https://sci.esa.int/web/xmm-newton/-/unexpected-periodic-flares-may-shed-light-on-black-hole-accretion)
http://www.esa.int/spaceinimages/Images/2019/09/Black_hole_at_the_core_of_distant_galaxy_periodically_brightens_up
Image credit: ESA/XMM-Newton; G. Miniutti & M. Giustini (CAB, CSIC-INTA, Spain)
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Mysteriously in-sync pulsar challenges existing theories
13 September 2019
For the first time, astronomers have detected synchronised pulses of optical and X-ray radiation from a mysterious pulsar some 4500 light years away. The observations indicate that a new physical mechanism might be needed to explain the behaviour of fast-spinning sources like this one, known as transitional millisecond pulsars.
The discovery was made as part of a two-day observation campaign spearheaded in 2017 by ESA's XMM-Newton X-ray observatory and other telescopes in space and on ground, including the optical Galileo National Telescope, which is operated by INAF, Italy's National Institute for Astrophysics, and located in the Canary Islands. The combination of both facilities allowed astronomers to measure with very high temporal resolution the two types of radiation coming from the ultrafast rotating pulsar.
https://sci.esa.int/web/xmm-newton/-/mysteriously-in-sync-pulsar-challenges-existing-theories
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XMM-Newton’s 20th anniversary in space
On 10 December, ESA’s XMM-Newton X-ray space observatory is celebrating its 20th launch anniversary. In those two decades, the observatory has supplied a constant stream of outstanding science. One area that the mission has excelled in is the science of black holes, having had a profound effect on our understanding of these cosmic enigmas.
Black holes are celestial objects so dense that nothing, not even light, can escape their pull. In this artist’s impression, the weird shapes of light around the black hole are what computer simulations predict will happen in the vicinity of its intense gravitational field.
Although neither XMM-Newton nor any other telescope can actually see black holes in this detail, the mission’s data and observations have provided a great source of information about these mysterious gravitational traps. In particular, XMM-Newton has been particularly good at isolating the X-rays given out by high-temperature, ionised atoms of iron as they swirl towards doom in the black hole.
The X-rays given out from the iron contain information about the geometry and dynamics of the black hole. In 2013, XMM-Newton was used to measure such emission in order to study the rotation rate of the supermassive black hole at the centre of the spiral galaxy NGC 1365.
Supermassive black holes, with masses between millions and billions of times the mass of our Sun, are thought to lurk in the centre of almost every large galaxy in the Universe. Their rotation rate is important because it can give away important details about the history of their host galaxy.
A fast rotating black hole is fed by a uniform stream of matter falling together, or by galaxies merging with one another, whereas a slowly rotating black hole is buffeted from all sides by small clumps of matter hitting it. In the case of NGC 1365, XMM-Newton showed that the black hole was rotating quickly and so the galaxy probably grew steadily over time, or merged with others.
More recently, XMM-Newton discovered mysterious flashes from the black hole at the centre of another galaxy called GSN 069. These flares took place every nine hours or so, raising the brightness of the X-ray emission by a factor of 100. These eruptions are thought to be coming from the matter caught in the black hole’s gravitational grip or from a less massive black hole circling the more massive one.
As XMM-Newton continues into its third decade, black holes and the galaxies they are found in will continue to be a priority target.
More about XMM-Newton’s first two decades in space:
XMM-Newton at 20: The fascinating X-ray Universe (https://sci.esa.int/web/xmm-newton/-/xmm-newton-at-20-the-fascinating-x-ray-universe)
XMM-Newton at 20: The large-scale Universe (https://sci.esa.int/web/xmm-newton/-/xmm-newton-at-20-the-large-scale-universe)
XMM-Newton at 20: Taking care of the science operations (https://sci.esa.int/web/xmm-newton/-/xmm-newton-at-20-taking-care-of-the-science-operations)
https://www.esa.int/ESA_Multimedia/Images/2019/12/XMM-Newton_s_20th_anniversary_in_space#.Xe-DeAf05Cs.link
Image credit: ESA/XMM-Newton/I. de la Calle
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FIRST SIGHTING OF HOT GAS SLOSHING IN GALAXY CLUSTER
10 January 2020
ESA's XMM-Newton X-ray observatory has spied hot gas sloshing around within a galaxy cluster – a never-before-seen behaviour that may be driven by turbulent merger events.
Galaxy clusters are the largest systems in the Universe bound together by gravity. They contain hundreds to thousands of galaxies and large quantities of hot gas known as plasma, which reaches temperatures of around 50 million degrees and shines brightly in X-rays.
Very little is known about how this plasma moves, but exploring its motions may be key to understanding how galaxy clusters form, evolve and behave.
https://sci.esa.int/s/8937LXw
Image credit: ESA/XMM-Newton/DSS-II/J. Sanders et al. 2019
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XMM-Newton discovers scorching gas in Milky Way’s halo
16/01/2020
ESA / Science & Exploration / Space Science
ESA’s XMM-Newton has discovered that gas lurking within the Milky Way’s halo reaches far hotter temperatures than previously thought and has a different chemical make-up than predicted, challenging our understanding of our galactic home.
A halo is a vast region of gas, stars and invisible dark matter surrounding a galaxy. It is a key component of a galaxy, connecting it to wider intergalactic space, and is thus thought to play an important role in galactic evolution.
Until now, a galaxy’s halo was thought to contain hot gas at a single temperature, with the exact temperature of this gas dependent on the mass of the galaxy.
However, a new study using ESA’s XMM-Newton X-ray space observatory now shows that the Milky Way’s halo contains not one but three different components of hot gas, with the hottest of these being a factor of ten hotter than previously thought. This is the first time multiple gas components structured in this way have been discovered in not only the Milky Way, but in any galaxy.
http://www.esa.int/Science_Exploration/Space_Science/XMM-Newton_discovers_scorching_gas_in_Milky_Way_s_halo
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XMM-Newton maps black hole surroundings
20/01/2020
Material falling into a black hole casts X-rays out into space – and now, for the first time, ESA’s XMM-Newton X-ray observatory has used the reverberating echoes of this radiation to map the dynamic behaviour and surroundings of a black hole itself.
Most black holes are too small on the sky for us to resolve their immediate environment, but we can still explore these mysterious objects by watching how matter behaves as it nears, and falls into, them.
As material spirals towards a black hole, it is heated up and emits X-rays that, in turn, echo and reverberate as they interact with nearby gas. These regions of space are highly distorted and warped due to the extreme nature and crushingly strong gravity of the black hole.
http://www.esa.int/Science_Exploration/Space_Science/XMM-Newton_maps_black_hole_surroundings
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XMM-NEWTON REVEALS GIANT FLARE FROM A TINY STAR
20 February 2020
A star of about eight percent the Sun's mass has been caught emitting an enormous 'super flare' of X-rays – a dramatic high-energy eruption that poses a fundamental problem for astronomers, who did not think it possible on stars that small.
The culprit, known by its catalogue number J0331-27, is a kind of star called an L dwarf. This is a star with so little mass that it is only just above the boundary of actually being a star. If it had any less mass, it would not possess the internal conditions necessary to generate its own energy.
Astronomers spotted the enormous X-ray flare in data recorded on 5 July 2008 by the European Photon Imaging Camera (EPIC) onboard ESA's XMM-Newton X-ray observatory. In a matter of minutes, the tiny star released more than ten times more energy of even the most intense flares suffered by the Sun.
Flares are released when the magnetic field in a star's atmosphere becomes unstable and collapses into a simpler configuration. In the process, it releases a large proportion of the energy that has been stored in it.
This explosive release of energy creates a sudden brightening – the flare – and this is where the new observations present their biggest puzzle.
https://sci.esa.int/web/xmm-newton/-/xmm-newton-reveals-giant-flare-from-a-tiny-star
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The most powerful black hole eruption in the Universe (annotated)
Astronomers using ESA’s XMM-Newton and NASA’s Chandra X-ray space observatories, along with radio telescopes on ground, have spotted the aftermath of the most powerful explosion ever seen in the Universe.
The huge outburst occurred in the Ophiuchus galaxy cluster, a large cosmic conglomerate with thousands of galaxies, hot gas and dark matter held together by gravity, lying some 390 million light years away. In particular, the eruption is linked to powerful jets released by the supermassive black hole that sits at the core of the cluster’s central galaxy and actively feeds on the surrounding gas, occasionally blasting off large amounts of matter and energy.
In this image, the diffuse hot gas pervading the cluster is revealed through X-ray observations from XMM-Newton (shown in pink), radio data from the Giant Metrewave Radio Telescope (shown in blue), and infrared data from the 2MASS survey (shown in white). The inset in the lower right shows a zoomed-in X-ray view based on Chandra data (also shown in pink), while bright dots sprinkled across the image reflect the distribution of foreground stars and galaxies.
The X-ray emission reveals the edge of a large cavity, carved in the hot gas by the black hole jets. The cavity is filled with radio emission from electrons accelerated to almost the speed of light – likely a result of the black hole’s feeding activity – providing evidence that an eruption of unprecedented size took place there.
Related article: The most powerful black hole eruption in the Universe (https://www.esa.int/Science_Exploration/Space_Science/The_most_powerful_black_hole_eruption_in_the_Universe)
Image: Link (https://www.esa.int/ESA_Multimedia/Images/2020/02/The_most_powerful_black_hole_eruption_in_the_Universe_annotated)
Image credit: X-ray: ESA/XMM-Newton and NASA/CXC/Naval Research Lab/S. Giacintucci; Radio: NCRA/TIFR/GMRTN; Infrared: 2MASS/UMass/IPAC-Caltech/NASA/NSF
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RETHINKING COSMOLOGY: UNIVERSE EXPANSION MAY NOT BE UNIFORM (https://sci.esa.int/web/xmm-newton/-/rethinking-cosmology-universe-expansion-may-not-be-uniform)
Astronomers have assumed for decades that the Universe is expanding at the same rate in all directions. A new study based on data from ESA’s XMM-Newton, NASA’s Chandra and the German-led ROSAT X-ray observatories suggests this key premise of cosmology might be wrong.
Konstantinos Migkas, a PhD researcher in astronomy and astrophysics at the University of Bonn, Germany, and his supervisor Thomas Reiprich originally set out to verify a new method that would enable astronomers to test the so-called isotropy hypothesis. According to this assumption, the Universe has, despite some local differences, the same properties in each direction on the large scale.
Widely accepted as a consequence of well-established fundamental physics, the hypothesis has been supported by observations of the cosmic microwave background (CMB). A direct remnant of the Big Bang, the CMB reflects the state of the Universe as it was in its infancy, at only 380 000 years of age. The CMB's uniform distribution in the sky suggests that in those early days the Universe must have been expanding rapidly and at the same rate in all directions.
In today's Universe, however, this may no longer be true.
“Together with colleagues from the University of Bonn and Harvard University, we looked at the behaviour of over 800 galaxy clusters in the present Universe,” says Konstantinos. “If the isotropy hypothesis was correct, the properties of the clusters would be uniform across the sky. But we actually saw significant differences.”
The astronomers used X-ray temperature measurements of the extremely hot gas that pervades the clusters and compared the data with how bright the clusters appear in the sky. Clusters of the same temperature and located at a similar distance should appear similarly bright. But that is not what the astronomers observed.
“We saw that clusters with the same properties, with similar temperatures, appeared to be less bright than what we would expect in one direction of the sky, and brighter than expected in another direction,” says Thomas. “The difference was quite significant, around 30 per cent. These differences are not random but have a clear pattern depending on the direction in which we observed in the sky.”
Before challenging the widely accepted cosmology model, which provides the basis for estimating the cluster distances, Konstantinos and colleagues first looked at other possible explanations. Perhaps, there could be undetected gas or dust clouds obscuring the view and making clusters in a certain area appear dimmer. The data, however, do not support this scenario.
In some regions of space the distribution of clusters could be affected by bulk flows, large-scale motions of matter caused by the gravitational pull of extremely massive structures such as large cluster groups. This hypothesis, however, also seems unlikely. Konstantinos adds that the findings took the team by surprise.
Video: https://www.esa.int/ESA_Multimedia/Videos/2020/04/Rethinking_cosmic_expansion
Image credit: K. Migkas et al. 2020
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XMM-Newton spies youngest baby pulsar ever discovered
17/06/2020
An observation campaign led by ESA’s XMM-Newton space observatory reveals the youngest pulsar ever seen – the remnant of a once-massive star – that is also a ‘magnetar’, sporting a magnetic field some 70 quadrillion times stronger than that of Earth.
Pulsars are some of the most exotic objects in the Universe. They form as massive stars end their lives via powerful supernova explosions and leave extreme stellar remnants behind: hot, dense and highly magnetised. Sometimes pulsars also undergo periods of greatly enhanced activity, in which they throw off enormous amounts of energetic radiation on timescales from milliseconds to years.
Smaller bursts often mark the onset of a more enhanced ‘outburst’, when X-ray emission can become a thousand times more intense. A multi-instrument campaign led by XMM-Newton has now captured such an outburst emanating from the youngest baby pulsar ever spotted: Swift J1818.0−1607, which was originally discovered by NASA’s Swift Observatory in March.
And there is more. Not only is this pulsar the youngest of the 3000 known in our Milky Way galaxy, but it also belongs to a very rare category of pulsars: magnetars, the cosmic objects with the strongest magnetic fields ever measured in the Universe.
http://www.esa.int/Science_Exploration/Space_Science/XMM-Newton_spies_youngest_baby_pulsar_ever_discovered
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Composite image of Swift J1818.0−1607, the youngest pulsar ever observed, as seen by the EPIC-pn camera on ESA’s XMM-Newton. The image combines observations in the following energy bands: 2–4 keV (red), 4–7.5 keV (green) and 8.5–12 keV (blue).
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Cosmic furnace seen by XMM-Newton
12/11/2020
This burst of colour shows a fascinating discovery: a galaxy cluster acting as a cosmic furnace. The cluster is heating the material within to hundreds of millions of degrees Celsius – well over 25 times hotter than the core of the Sun.
The cluster, named HSC J023336-053022 (XLSSC 105), lies four billion light-years from Earth and was independently discovered by both ESA’s space-based XMM-Newton X-ray Observatory and NAOJ’s Subaru optical-infrared telescope in Hawaii, USA. XMM-Newton detected the cluster via the international XXL survey, which is exploring two large areas of space outside our galaxy.
Galaxies are not distributed randomly throughout the Universe, and instead exist within groups and larger clusters. These aggregations can be mammoth and sometimes contain many thousands of individual galaxies in a single structure, all embedded in clumps of invisible dark matter. Different sub-groups of galaxies can also form within a single cluster, as shown here by the two blue-purple circles on either side of centre. These circles mark the locations of two sub-clusters within HSC J023336-053022 which are slowly moving towards and colliding with one another, ‘shock heating’ gas to intense temperatures in the process.
To create this image, three different international teams of astronomers explored observations of the cluster across the electromagnetic spectrum, in order to isolate and pinpoint different aspects of this region of space. These aspects are shown here in different colours. Individual galaxies within the cluster show up in orange, and dark matter – which maps the location of the two sub-clusters – in blue (via optical observations from Subaru). Hot, dense gas shows up in green (X-ray from XMM-Newton), while hot, thin, high-pressure gas shows up in red (radio from the Green Bank Telescope in Virginia, USA). This gas is something known as the ‘intracluster medium’, which permeates galaxy clusters and fills the space between galaxies.
The addition of radio observations makes this image special, as many studies of collisions within or between galaxy clusters have not captured this shock-heating process – which is represented visually in the region where green changes to red – in radio. This process releases immense amounts of energy and heats already scorching gas to temperatures tens of times hotter. Before shock heating, the gas sits at around 40 million degrees Celsius – already some 2.7 times hotter than the core of the Sun.
https://www.esa.int/ESA_Multimedia/Images/2020/11/Cosmic_furnace_seen_by_XMM-Newton
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Cosmic neon lights
11/01/2021
This image shows a new type of star that has never been seen before in X-ray light. This strange star formed after two white dwarfs – remnants of stars like our Sun – collided and merged. But instead of destroying each other in the event, the white dwarfs formed a new object that shines bright in X-ray light.
A team of astronomers led by Lidia Oskinova of the University of Potsdam, Germany, used ESA’s XMM-Newton X-ray telescope to study the object that was originally discovered in 2019. Back then, astronomers already reported that the object has very high wind speeds and is too bright, and therefore too massive, to be an ordinary white dwarf. They suggested that the object is a new type of star that survived the merger of two white dwarfs.
Based on new information from XMM-Newton, Lidia and her team now suggest that what we see in the image is a new type of X-ray source powered by the merger of two white dwarfs. The remnant of the clash – the nebula – is also visible in this image, and is mostly made out of the element neon (shown in green). The star is very unstable and will likely collapse into a neutron star within 10 000 years.
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Orphan cloud discovered in galaxy cluster
29/06/2021
New observations made with ESA’s X-ray XMM Newton telescope have revealed an “orphan cloud” – an isolated cloud in a galaxy cluster that is the first discovery of its kind.
A lot goes on in a galaxy cluster. There can be anything from tens to thousands of galaxies bound together by gravity. The galaxies themselves have a range of different properties, but typically contain systems with stars and planets, along with the material in between the stars – the interstellar medium. In between the galaxies is more material – tenuous hot gas known as the intercluster medium. And sometimes in all the chaos, some of the interstellar medium can get ripped out of a galaxy and get stranded in an isolated region of the cluster, as this new study reveals.
Unexpected discovery
Abell 1367, also known as the Leo Cluster, is a young cluster that contains around 70 galaxies and is located around 300 million light-years from Earth. In 2017, a small warm gas cloud of unknown origin was discovered in A1367 by the Subaru telescope in Japan. A follow-up X-ray survey to study other aspects of A1367 unexpectedly discovered X-rays emanating from this cloud, revealing that the cloud is actually bigger than the Milky Way.
This is the first time an intercluster clump has been observed in both X-rays and the light that comes from the warm gas. Since the orphan cloud is isolated and not associated with any galaxy, it has likely been floating in the space between galaxies for a long time, making its mere survival surprising.
The discovery of this orphan cloud was made by Chong Ge at the University of Alabama in Huntsville, and colleagues, and the study has been published in Monthly Notices of the Royal Astronomical Society.
Along with data from XMM-Newton and Subaru, Chong and colleagues also used the Multi Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope (VLT) to observe the cluster in visible light.
The orphan cloud is the blue umbrella-shaped part of the image. It has been colour-coded to show the X-ray part of the cloud in blue, the warm gas in red, and the visible region in white shows some of the galaxies in the cluster. The part of the cloud that had been discovered in 2017 (in red) overlaps with the X-ray at the bottom of the cloud.
How the cloud became an orphan
It was previously thought that the distribution of material between galaxies is smooth, however more recent X-ray studies have revealed the presence of clumps in clusters. It was theorised that clumps of gas in the clusters were originally the gas that exists between stars in individual galaxies. The intercluster gas acts as a wind that is strong enough to pull the interstellar gas out of the galaxy as the galaxy is moving through the cluster. However, observations showing that intercluster clumps are originally stripped interstellar material have never been made until now. The observation of the warm gas in the clump provides the evidence to show that this orphan cloud originated within a galaxy. Interstellar material is much cooler than intercluster material, and the temperature of the orphan cloud matches that of interstellar gas. The researchers were also able to determine why the orphan cloud has survived for as long as it has. An isolated cloud would be expected to be ripped apart by instabilities caused by velocity and density differences. However, they found that a magnetic field in the cloud would be able to suppress these instabilities.
Searching for the parent galaxy
It is likely that the parent galaxy of the orphan cloud is a massive one as the mass of the X-ray gas in the orphan is substantial. It is possible that the parent might one day be discovered with future observations by following some breadcrumbs. For example, there are traces of the warm gas that extend beyond the orphan cloud that could be used to identify the parent with more data. There are other unsolved mysteries regarding the cloud that could be deciphered with more observations, such as mysterious offset between the brightest X-rays and the brightest light from the warm gas.
A closer inspection of this orphan will also further our understanding of the evolution of stripped interstellar medium at such a great distance from its parent galaxy and will provide a rare laboratory to study other things such as turbulence and heat conduction. This study paves the way for research on intercluster clumps, as future warm gas surveys can now be targeted to search for other orphan clouds.
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Jupiter’s mysterious X-ray auroras explained
Jupiter’s mysterious X-ray auroras have been explained, ending a 40-year quest for an answer. For the first time, astronomers have seen the way Jupiter’s magnetic field is compressed, which heats the particles and directs them along the magnetic field lines down into the atmosphere of Jupiter, sparking the X-ray aurora. The connection was made by combining in-situ data from NASA’s Juno mission with X-ray observations from ESA’s XMM-Newton.
Related article: The mystery of what causes Jupiter’s X-ray auroras is solved (https://www.esa.int/Science_Exploration/Space_Science/The_mystery_of_what_causes_Jupiter_s_X-ray_auroras_is_solved)
https://www.esa.int/ESA_Multimedia/Images/2021/07/Jupiter_s_mysterious_X-ray_auroras_explained
Image credit: Yao/Dunn/ESA/NASA
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XMM-Newton sees light echo from behind a black hole
28/07/2021
For the first time, astronomers have seen light coming from behind a black hole.
Using ESA’s XMM-Newton and NASA’s NuSTAR space telescopes, an international team of scientists led by Dan Wilkins of Stanford University in the USA observed extremely bright flares of X-ray light coming from around a black hole.
The X-ray flares echoed off of the gas falling into the black hole, and as the flares were subsiding, the telescopes picked up fainter flashes, which were the echoes of the flares bouncing off the gas behind the black hole.
This supermassive black hole is 10 million times as massive as our Sun and located in the centre of a nearby spiral galaxy called I Zwicky 1, 800 million light-years away from Earth.
The astronomers did not expect to see anything from behind the black hole, since no light can escape from it. But because of the black hole’s extreme gravity warping the space around it, light echoes from behind the black hole were bent around the black hole, making them visible from XMM and NuSTAR’s point of view.
The discovery began with the search to find out more about the mysterious ‘corona’ of the black hole, which is the source of the bright X-ray light. Astronomers think that the corona is a result of gas that falls continuously into the black hole, where it forms a spinning disk around it – like water flushing down a drain.
This gas disk is heated up to millions of degrees and generates magnetic fields that get twisted into knots by the spinning black hole. When the magnetic field gets tied up, it eventually snaps, releasing the energy stored within it. This heats everything around it and produces the corona of high energy electrons that produce the X-ray light.
The X-ray flare observed from I Zwicky 1 was so bright that some of the X-rays shone down onto the disk of gas falling into the black hole. The X-rays that reflected on the gas behind the black hole were bent around the black hole, and these smaller flashes arrived at the telescopes with a delay. These observations match Einstein’s predictions of how gravity bends light around black holes, as described in his theory of General Relativity.
The echoes of X-rays from the disk have specific ‘colours’ of light and as the X-rays travel around the black hole, their colours change slightly. Because the X-ray echoes have different colours and are seen at different times, depending where on the disk they reflected from, they contain a lot of information about what is happening around a black hole. The astronomers want to use this technique to create a 3D map of the black hole surroundings.
Another mystery to be solved in future studies is how the corona produces such bright X-ray flares. The mission to characterise and understand black hole coronas will continue with XMM-Newton and ESA’s future X-ray observatory, Athena (Advanced Telescope for High-ENergy Astrophysics).
The team published their findings in Nature.
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A planet in another galaxy - infographic
Using ESA's XMM-Newton and NASA's Chandra X-ray space telescopes, astronomers discovered that something temporarily blocked the light coming from an X-ray binary outside of the Milky Way.
After investigating many options, the team think a planet the size of Saturn could be responsible for blocking the light.
Related article: Could this be a planet in another galaxy? (https://www.esa.int/Science_Exploration/Space_Science/Could_this_be_a_planet_in_another_galaxy)
https://www.esa.int/ESA_Multimedia/Images/2021/10/A_planet_in_another_galaxy_-_infographic
Image credit: ESA
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XMM-Newton spies black holes eating the same stars again and again
12/01/2023
Two teams of astronomers using ESA’s XMM-Newton space telescope have observed repeated outbursts of light from inactive black holes that partially destroy stars again and again. This discovery is unexpected, since outbursts of black holes usually appear only once when a black hole consumes a star.
Supermassive black holes lie at the centres of most galaxies. Their masses range from hundreds of thousands to billions of times the mass of our Sun. Despite this, black holes are elusive, trapping light and remaining hard to detect.
A hidden supermassive black hole can be uncovered when a star veers on a close approach to it. The star gets ripped apart by strong tidal forces, forming a disk of stellar debris on which the black hole is feeding. Energetic X-rays, UV, optical and radio light can be detected during this process known as a tidal disruption event.
Not totally destroyed
Typical tidal disruption events exhibit a bright outburst of light, known as a flare, which lasts a few months during which the black hole consumes the star. However, two new flares with peculiar behaviour have been observed by XMM-Newton. These flares repeatedly shine bright in X-ray and UV light after the first outburst, suggesting that the stars have not been totally destroyed during the initial encounter with the black holes.
The studies led by astronomers Thomas Wevers from the European Southern Observatory, and Zhu Liu from the Max Planck Institute for Extraterrestrial Physics, Germany, reveal that part of the stars may have survived their first attack from the black holes. The X-ray and UV data suggest that parts of the stars are not entirely eaten up, continue their orbit and encounter the disruptive black hole again, leading to recurring flares. This activity is called a partial tidal disruption event.
The astronomers found repeated flares from two separate galaxies hosting supermassive black holes. These galaxies lie well beyond the outskirts of the Milky Way at distances of almost 900 million light-years and 1 billion light-years.
One of the re-brightening events, called eRASSt J045650.3−203750, was discovered by the X-ray telescope eROSITA on board the Spectrum-Roentgen-Gamma mission. XMM-Newton observations in 2021 and 2022 by a team led by Zhu found that the original flare was followed by repeated outbursts roughly every 223 days.
Zhu explains: “The results from our first XMM-Newton observation were surprising. The black hole showed an unusually drastic dimming of X-ray light, compared to when it had been discovered two weeks previously by the eROSITA telescope. Follow-up observations with XMM-Newton and other instruments confirmed our speculations that this behaviour was being caused by a partial tidal disruption event.”
The other tidal disruption event, called AT2018fyk, was discovered by the All-Sky Automated Survey for Supernovae. It shone bright in UV and X-rays for at least 500 days, followed by a sudden dimming. In May 2022, Thomas and colleagues used XMM-Newton to study the dramatic increase in X-ray and UV brightness 1200 days after it first appeared.
https://www.esa.int/Science_Exploration/Space_Science/XMM-Newton_spies_black_holes_eating_the_same_stars_again_and_again