Résumé / Abstract Journal-club_Galaxies

Journal-club Galaxies

« Dense molecular gas in the Circumgalactic Medium of distant massive galaxies, groups, and photo-clusters: halos, dynamically cold clumps, and streams »

Matt Lehnert
Institut d'Astrophysique de Paris (Paris, France)

I discuss recent detections of molecules in the circumgalactic medium (CGM) of galaxies in the early Universe (z~2-4). We have known for decades that the CGM contains warm ionized gas via the detection of Ly-alpha and other UV lines both through their emission and absorption. The absorption lines observed in the light of background QSOs passing through galactic halos — much of this work was pioneered at IAP in studies led by Jacqueline Bergeron, Patrick Petitijean, Patrick Boissé, Pasquier Noterdaeme, and many researchers passing through IAP — has provided great insights into the nature of the CGM in distant and local galaxies but limited information about its molecular gas content and properties. Recently, with the Australian Compact Telescope Array (ACTA) in Australia, Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, and the Very Large Array (VLA) in the USA, we are pioneering the detection of molecules such as CO, [CI], and water in the halos of massive galaxies and proto-clusters at high redshift. I present a simple phenomenological theory for how molecular gas forms in such an unusual environment and some observations which are just beginning to reveal the complex nature of this gas. One thing is becoming clear that the molecular gas contains a significant amount of kinetic energy in bulk flows and turbulence and has not yet dissipated/thermalized.
jeudi 16 avril 2020 - 10:30
Webinaire, Institut d'Astrophysique
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