News

2020-09-16

In our latest MEGAFLOW (MusE GAs FLOw and Wind) paper we probed the circumgalactic medium of a typical distant (z=0.7) galaxy in absorption and, rather spectacularly, also in emission. The data are consistent with an outflow. The paper is today featured in a CNRS press release:

Press release English: https://www.cnrs.fr/en/part-universes-missing-matter-found-thanks-muse-instrument
Press release French: https://www.cnrs.fr/fr/une-partie-manquante-de-la-matiere-de-lunivers-trouvee-grace-linstrument-muse
Science paper is published in Monthly Notices of the Royal Astronomical Society, Volume 507, Issue 3, November 2021, Pages 4294–4315 ( https://academic.oup.com/mnras/article-abstract/507/3/4294/6329693 )

We probed the cool-warm (~10^4 to 10^5K) metal-enriched gas with a line from single ionized magnesium. Both the emission, which extends in the deep VLT/MUSE observations well beyond the galaxy's stellar light, and the absorption, which is seen imprinted on a bright background quasar in VLT/UVES data, are consistent with a biconical outflow ejected perpendicular to the galaxy's disk.
Outflows, which are understood to be launched by the energy and momentum injected into the galaxy's interstellar medium by supernovae and or AGNs (an AGN is probably not relevant in our case), are long understood to play a crucial part in regulating the evolution of galaxies.
Outflows are also responsible for enriching the circumgalactic medium (CGM) with metals. In order to get a complete census of the baryonic matter, it is crucial to count not only the matter in galaxies, but also that in the CGM.
Spectacular outflows have been observed in emission in close-by galaxies, such as the famous starburst M82. However, most information we have about outflows in the more distant Universe, especially for metals in the cool-warm phases, comes from the absorption that the outflowing gas imprints on the spectra of background sources (or the spectra of the galaxies themselves).
Only with the advent of panoramic IFUs, such as VLT/MUSE, it has become possible to efficiently study these CGM metals also in emission. Exploiting these capabilities, we can now create "maps" of the metal-enriched CGM at times when the Universe was only half of its present age.

2020-02-09

The MEGAFLOW IV paper ("A two sightline tomography of a galactic wind") has now been assigned an issue: "Monthly Notices of the Royal Astronomical Society, Volume 492, Issue 3, p.4576-4588" ( ADS ; MNRAS webpage ).

2019-12-06

Perliminary version of this new webpage is up (content still under construction)