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📰 The dark matter of the cosmic web revealed by the effect of the gravitational lens

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A new step has been taken in the field of weak gravitational lenses (weak lens) with the production of one of the richest catalogs of galaxies. This catalog contains the ultra-precise morphology of 100 million galaxies (Galaxies is a French quarterly magazine dedicated to science fiction. With …) distant, allowing you to measure the tiny deformations caused by the gravitational lens acting on the light (Light is the set of electromagnetic waves visible to the eye …) spreading through the cosmic web of black matter (In astrophysics, dark matter (or dark matter), translation from English …) present in everything (The whole understood as the whole of what exists is often interpreted as the world or …) L’Universe (The Universe is the sum of all that exists and the laws that govern it.).


A typical CFHT-MegaCam image for UNIONS: the surface of sky (The sky is the earth’s atmosphere as seen from the planet earth.) covered here is only 0.2 degrees2 (1 / 25,000 of the full survey) but already reveals several thousand distant galaxies (the small weak points) used to study the properties of it matters (Matter is the substance that makes up any body having a tangible reality. Its …) Black.
© CFHT / UNIONS.

This new collection is based on thousands of deep images of the Sometimes (Once (or vault) is an architectural element of internal cladding of a …) celestial hemisphere north (North is a cardinal point, opposite south.)captured by a camera (The term camera derives from the Latin: camera, for photographic camera. It designates a device …) built at the CEA (the MegaCam) mounted on the Telescope (A telescope, (from the Greek tele which means “far” and skopein which means …) Canada-France-Hawaii (CFHT). The morphology catalog is distributed within the collaboration scientific (A scientist is a person who devotes himself to the study of one or more sciences and who …) UNIONS (for Optical northern survey in the near ultraviolet infrared), a great statement byimages (Images are mainly the creation and trade of physical images that …) of the northern hemisphere sky in the fields optical (Optics is the branch of physics that deals with light, radiation …) and in the near infrared, co-directed by Jean-Charles Cuillandre of IRFU / DAp.

Under the direction of Martin Kilbinger, the catalog was created by the CEA. A complete processing pipeline (ShapePipe) was developed under the responsibility of Samuel Farrens to process the data (In information technology (IT), data is an elementary description, often …) CFHT UNIONS. A total sky area of ​​3,500 square degrees was processed.

Two scientific projects led by CosmoStat members and using data from weak lens UNIONS have been published. At first paper (Paper (from the Latin papyrus) is a material made up of fibers …)following a thesis (A thesis (from the Greek name thesis, which translates to “pose action”) is …) from doctorate (The doctorate (from the Latin doctorem, from doctum, supin da docere, to teach) is usually …)the team presents dark matter maps and profiles of mass (The term mass is used to designate two quantities linked to one …) of the cluster of galaxies (A cluster of galaxies is the association of more than one hundred galaxies connected together since …) detected by ESA’s Planck mission. A second article by a 2 masters student (submitted to Astronomy & Astrophysics magazine) examines the number (The notion of number in linguistics is dealt with in the article “Number …) of weak lens peaks as a method of measuring cosmological parameters.


Dark matter distribution map of the cosmic web produced by UNIONS weak gravitational lens data. This area of ​​the sky represents 275 degrees2less than a tenth of the area then covered by UNIONS (it will reach 5,000 degrees2 of the northern sky). The yellow dots indicate areas of overdensity of dark matter corresponding to clusters of galaxies and the blue areas correspond to areas of low density. density (The density or relative density of a body is the ratio of its density to the …)great cosmic voids.
© CEA / Cosmostat.

to know more

– Guinot et al. ShapePipe: A new shape measurement pipeline and weak lens application to UNIONS / CFI data
-Aycoberry et al. UNIONS: The impact of systematic errors on weak lens peak counts
Software (In computer science, software is a set of information related to processing …) ShapePipe: https://cosmostat.github.io/shapepipe/

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