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EI2GYB > ASTRO 20.09.21 08:02z 97 Lines 5087 Bytes #999 (0) @ WW
BID : 14821_EI2GYB
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Subj: Part of the Universe's missing matter found
Path: HB9ON<IW2OHX<UA6ADV<I0OJJ<EA2RCF<LU9DCE<N7HPX<W9GM<N3HYM<EI2GYB
Sent: 210920/0757Z @:EI2GYB.DGL.IRL.EURO #:14821 BPQ6.0.22
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Part of the Universe's missing matter found
Summary:
Galaxies can receive and exchange matter with their external environment
thanks to the galactic winds created by stellar explosions. An international
research team has now mapped a galactic wind for the first time. This unique
observation helped to reveal where some of the Universe's missing matter is
located and to observe the formation of a nebula around a galaxy.
Galaxies can receive and exchange matter with their external environment thanks
to the galactic winds created by stellar explosions. Thanks to the MUSE
instrument1 from the Very Large Telescopeat the ESO, an international research
team, led on the French side by the CNRS and l'Universit‚ Claude Bernard Lyon
12, has mapped a galactic wind for the first time. This unique observation,
which is detailed in a study published in MNRAS on 16 September 2021, helped to
reveal where some of the Universe's missing matter is located and to observe
the formation of a nebula around a galaxy.
Galaxies are like islands of stars in the Universe, and possess ordinary or
baryonic matter, which consists of elements from the periodic table, as well as
dark matter, whose composition remains unknown. One of the major problems in
understanding the formation of galaxies is that approximately 80% of the
baryons3 that make up the normal matter of galaxies is missing. According to
models, they were expelled from galaxies into inter-galactic space by the
galactic winds created by stellar explosions.
An international team4, led on the French side by researchers from the CNRS and
l'Universit‚ Claude Bernard Lyon 1, successfully used the MUSE instrument to
generate a detailed map of the galactic wind driving exchanges between a young
galaxy in formation and a nebula (a cloud of gas and interstellar dust).
The team chose to observe galaxy Gal1 due to the proximity of a quasar, which
served as a "lighthouse" for the scientists by guiding them toward the area of
study. They also planned to observe a nebula around this galaxy, although the
success of this observation was initially uncertain, as the nebula's luminosity
was unknown.
The perfect positioning of the galaxy and the quasar, as well as the discovery
of gas exchange due to galactic winds, made it possible to draw up a unique
map. This enabled the first observation of a nebula in formation that is
simultaneously emitting and absorbing magnesium -- some of the Universe's
missing baryons -- with the Gal1 galaxy.
This type of normal matter nebula is known in the near Universe, but their
existence for young galaxies in formation had only been supposed.
Scientists thus discovered some of the Universe's missing baryons, thereby
confirming that 80-90% of normal matter is located outside of galaxies, an
observation that will help expand models for the evolution of galaxies.
Notes
1 -- MUSE, which stands for Multi Unit Spectroscopic Explorer, is a 3D
spectrograph designed to explore the distant Universe. The Centre de recherch‚
astrophysique de Lyon (CNRS/Universit‚ Claude Bernard-Lyon 1/ENS de Lyon) led
its construction.
2 -- Researchers from the Centre de recherch‚ astrophysique de Lyon
(CNRS/Universit‚ Claude Bernard Lyon 1/ENS de Lyon), the Galaxies, ‚toiles,
physique, instrumentation laboratory (CNRS/Observatoire de Paris -- PSL), and
the Institut de recherch‚ en astrophysique et plan‚tologie (CNRS/Universit‚
Toulouse III -- Paul Sabatier/CNES) participated in the project.
3 -- Baryons are particles consisting of three quarks, such as protons and
neutrons. They make up atoms and molecules as well as all visible structures in
the observable Universe (stars, galaxies, galaxy clusters, etc.). The "missing"
baryons, which had never before been observed, must be distinguished from dark
matter, which consists of non-baryonic matter of an unknown nature.
4 -- Including scientists from Saint Mary's University in Canada, the Institute
for Astrophysics at the University of Potsdam in Germany, Leiden University in
the Netherlands, the University of Geneva and the Swiss Federal Polytechnic
School in Zurich, the Inter-University Centre for Astronomy and Astrophysics in
India, and the University of Porto in Portugal.
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