Part of the Universe's missing matter found

Date:
September 16, 2021
Source:
CNRS
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.



FULL STORY ========================================================================== 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'Universite' 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'Universite' 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 recherche' astrophysique de Lyon (CNRS/Universite' Claude Bernard-Lyon
1/ENS de Lyon) led its construction.

2 -- Researchers from the Centre de recherche' astrophysique de Lyon
(CNRS/ Universite' Claude Bernard Lyon 1/ENS de Lyon), the Galaxies,
e'toiles, physique, instrumentation laboratory (CNRS/Observatoire de Paris
-- PSL), and the Institut de recherche' en astrophysique et plane'tologie (CNRS/Universite' 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.

========================================================================== Story Source: Materials provided by CNRS. Note: Content may be edited
for style and length.


========================================================================== Journal Reference:
1. Johannes Zabl, Nicolas F Bouche', Lutz Wisotzki, Joop Schaye,
Floriane
Leclercq, Thibault Garel, Martin Wendt, Ilane Schroetter,
Sowgat Muzahid, Sebastiano Cantalupo, Thierry Contini, Roland
Bacon, Jarle Brinchmann, Johan Richard. MusE GAs FLOw and Wind
(MEGAFLOW) VIII. Discovery of a Mgii emission halo probed by a
quasar sightline. Monthly Notices of the Royal Astronomical Society,
2021; 507 (3): 4294 DOI: 10.1093/mnras/ stab2165 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/09/210916114621.htm

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