Scanning the heaven for X-ray sources, ESA's XMM-Newton X-ray observatory has been busy amongst the XXL Survey, its largest observational programme to date. The minute batch of information from the survey has merely been released, including information on 365 galaxy clusters, which draw the large-scale construction of the Universe as well as its development through time, as well as on 26 000 active galactic nuclei (AGN).
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| Multi-wavelength persuasion of galaxy cluster XLSSC006 [Credit: ESA/XMM-Newton (X-rays); CFHT (optical); XXL Survey] |
X-rays are produced inward about of the most energetic processes inward the Universe, but because they are blocked past times Earth's atmosphere, they tin solely hold upwards observed from space. When X-ray telescopes honor the extragalactic Universe, they basically run into 2 sources: the hot gas pervading clusters of galaxies, as well as Active Galactic Nuclei (AGN) – bright, compact regions at the centres of about galaxies where a supermassive dark hole is accreting the surrounding matter.
ESA's XMM-Newton is ane of the most powerful X-ray telescopes e'er placed inward orbit. Over the in conclusion 8 years, it has spent 2000 hours measure X-ray radiations equally business office of the XXL Survey, which searched for galaxy clusters as well as AGN past times scanning 2 areas of seemingly-empty heaven each measure 25 foursquare degrees (as a reference, the total satelite measures virtually one-half a marker across).
The offset laid of XXL information was released inward 2015; it included 100 of the brightest galaxy clusters as well as grand AGN. This month, a novel information catalogue was published containing an astonishing 365 clusters as well as 26 000 AGN. The offset results using this information are published inward a especial number of Astronomy & Astrophysics.
The survey mapped X-ray clusters thence distant that the calorie-free left them when the Universe was merely one-half of its acquaint age, as well as AGN that are fifty-fifty farther away. Some of the observed sources are thence far-flung that XMM-Newton received no to a greater extent than than 50 X-ray photons from them, making it challenging to state whether they are clusters or AGN.
"It was relatively slow to reveal galaxy clusters as well as AGN, because they are the solely extragalactic objects visible inward X-ray light," explains Marguerite Pierre from CEA Saclay, France.
"But nosotros had to role several other telescopes collecting calorie-free at many unlike wavelengths, equally good equally extensive computing facilities, to get together to a greater extent than information virtually each source, including pinning downwards their nature as well as distance."
Matter inward the Universe is non evenly distributed but forms a cosmic spider web of filaments shaped past times gravity, amongst galaxy clusters establish at their intersections. Milky Way clusters are the largest saltation entities inward the Universe – they draw the highest density peaks inward its large-scale structure, making them a powerful tool for answering questions virtually cosmology.
The construction as well as development of the Universe is described past times a laid of cosmological parameters, which include the density of its diverse components as well as the charge per unit of measurement that it is expanding. Currently, nosotros know the value of many of these parameters fairly well, but large samples of cosmic tracers at a diverseness of distances are required to to a greater extent than accurately push clit the underlying construction of the Universe. The ultimate finish of the XXL Survey is to supply an extensive, well-characterised catalogue of clusters that tin hold upwards used to constrain the cosmological parameters.
ESA's Planck satellite determined values for cosmological parameters past times studying the cosmic microwave background, which is information from the rattling early on Universe. After estimating these parameters using the latest information from the XXL Survey – which is based on information from the to a greater extent than recent Universe – scientists compared their findings against the Planck values.
"Although nosotros didn't reveal equally many galaxy clusters equally predicted past times the Planck cosmological model, nosotros obtained a distribution of clusters as well as AGN that is compatible amongst the currently favoured cosmological model, which resorts to Einstein's cosmological constant equally an explanation for the accelerated expansion of the Universe, rather than invoking fifty-fifty to a greater extent than exotic possibilities," explains Marguerite Pierre.
"We tin already better on the Planck approximate for the cosmological constant, fifty-fifty though our analysis has solely been carried out on one-half of the XXL cluster sample; nosotros volition pass the adjacent brace of years analysing the residual of the information amongst the aim of refining the cosmological constraints."
It is to a greater extent than hard to approximate values for the cosmological parameters using AGN, equally their properties are affected past times many external influences. Scientists direct maintain instead been using the AGN information from the XXL Survey to sympathize to a greater extent than virtually how dark holes shape as well as evolve.
Thanks to XXL, this is the offset fourth dimension that scientists direct maintain been able to mensurate the three-dimensional clustering outcome of distant X-ray clusters as well as AGN on rattling large scales. They tin forthwith finally run into where the AGN are located inside the large-scale construction of the Universe indicated past times the galaxy clusters.
The results confirm that XMM-Newton is a powerful survey machine. They also pave the agency for the concluding cosmological analysis of this survey, which volition supply independent constraints on the cosmological parameters to unravel to a greater extent than mysteries of the Universe.
The cosmic spider web volition hold upwards probed farther past times ESA's futurity Euclid satellite, which volition honor calorie-free emitted upwards to 10 billion years ago. Euclid volition run into a huge number of sources, equally it volition honor optical as well as infrared light; amongst its large surveyed expanse as well as rich multi-wavelength coverage, the XXL information volition serve equally a reference for these observations.
Observations past times XMM-Newton direct maintain also raised novel questions virtually the physics of galaxy clusters, which volition hold upwards investigated inward greater item past times ESA's adjacent X-ray mission, Athena. Due to launch inward 2031, Athena volition hold upwards far to a greater extent than sensitive than its predecessor. While XMM-Newton tin honor clusters at a diverseness of distances from us, probing unlike epochs inward the Universe's history, Athena volition honor clusters thence distant that their calorie-free left them equally they were forming, telling us fifty-fifty to a greater extent than virtually the agency these gigantic structures convey shape as well as evolve.
In the meantime, scientists inward the XXL collaboration excogitation to procedure the remaining observations as well as review information using improved processing techniques. The concluding XXL information unloose containing fifty-fifty to a greater extent than X-ray sources, equally good equally the consummate cosmological analysis, is foreseen for 2021.
"It is rattling exciting that information from this infinite telescope is contributing to our agreement of the development of the Universe," concludes Norbert Schartel, XMM-Newton Project Scientist at ESA. "This was made possible thank you lot to the collaboration betwixt a huge number of institutions across many unlike countries."
Source: European Space Agency [October 04, 2018]
Sumber http://archaeologynewsnetwork.blogspot.com
"But nosotros had to role several other telescopes collecting calorie-free at many unlike wavelengths, equally good equally extensive computing facilities, to get together to a greater extent than information virtually each source, including pinning downwards their nature as well as distance."
 |
| The 365 galaxy clusters of the XXL Survey – X-ray view [Credit: ESA/XMM-Newton/XXL Survey] |
The construction as well as development of the Universe is described past times a laid of cosmological parameters, which include the density of its diverse components as well as the charge per unit of measurement that it is expanding. Currently, nosotros know the value of many of these parameters fairly well, but large samples of cosmic tracers at a diverseness of distances are required to to a greater extent than accurately push clit the underlying construction of the Universe. The ultimate finish of the XXL Survey is to supply an extensive, well-characterised catalogue of clusters that tin hold upwards used to constrain the cosmological parameters.
ESA's Planck satellite determined values for cosmological parameters past times studying the cosmic microwave background, which is information from the rattling early on Universe. After estimating these parameters using the latest information from the XXL Survey – which is based on information from the to a greater extent than recent Universe – scientists compared their findings against the Planck values.
"Although nosotros didn't reveal equally many galaxy clusters equally predicted past times the Planck cosmological model, nosotros obtained a distribution of clusters as well as AGN that is compatible amongst the currently favoured cosmological model, which resorts to Einstein's cosmological constant equally an explanation for the accelerated expansion of the Universe, rather than invoking fifty-fifty to a greater extent than exotic possibilities," explains Marguerite Pierre.
"We tin already better on the Planck approximate for the cosmological constant, fifty-fifty though our analysis has solely been carried out on one-half of the XXL cluster sample; nosotros volition pass the adjacent brace of years analysing the residual of the information amongst the aim of refining the cosmological constraints."
It is to a greater extent than hard to approximate values for the cosmological parameters using AGN, equally their properties are affected past times many external influences. Scientists direct maintain instead been using the AGN information from the XXL Survey to sympathize to a greater extent than virtually how dark holes shape as well as evolve.
Thanks to XXL, this is the offset fourth dimension that scientists direct maintain been able to mensurate the three-dimensional clustering outcome of distant X-ray clusters as well as AGN on rattling large scales. They tin forthwith finally run into where the AGN are located inside the large-scale construction of the Universe indicated past times the galaxy clusters.
 |
| The 365 galaxy clusters of the XXL Survey – Optical persuasion [Credit: CFHT Legacy Survey/ CTIO/XXL Survey] |
The cosmic spider web volition hold upwards probed farther past times ESA's futurity Euclid satellite, which volition honor calorie-free emitted upwards to 10 billion years ago. Euclid volition run into a huge number of sources, equally it volition honor optical as well as infrared light; amongst its large surveyed expanse as well as rich multi-wavelength coverage, the XXL information volition serve equally a reference for these observations.
Observations past times XMM-Newton direct maintain also raised novel questions virtually the physics of galaxy clusters, which volition hold upwards investigated inward greater item past times ESA's adjacent X-ray mission, Athena. Due to launch inward 2031, Athena volition hold upwards far to a greater extent than sensitive than its predecessor. While XMM-Newton tin honor clusters at a diverseness of distances from us, probing unlike epochs inward the Universe's history, Athena volition honor clusters thence distant that their calorie-free left them equally they were forming, telling us fifty-fifty to a greater extent than virtually the agency these gigantic structures convey shape as well as evolve.
In the meantime, scientists inward the XXL collaboration excogitation to procedure the remaining observations as well as review information using improved processing techniques. The concluding XXL information unloose containing fifty-fifty to a greater extent than X-ray sources, equally good equally the consummate cosmological analysis, is foreseen for 2021.
"It is rattling exciting that information from this infinite telescope is contributing to our agreement of the development of the Universe," concludes Norbert Schartel, XMM-Newton Project Scientist at ESA. "This was made possible thank you lot to the collaboration betwixt a huge number of institutions across many unlike countries."
Source: European Space Agency [October 04, 2018]
Sumber http://archaeologynewsnetwork.blogspot.com
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