Résumé / Abstract Seminaire_IAP
« Light up the darkness! The cold molecular medium around high-z radio galaxies »

Bjorn Emonts
Centro de Astrobiología, Consejo Sup. Invest. Cient. (Madrid, Espagne)

Most of the baryons in the Universe are dark, i.e, too faint to be easily detected. In galaxy halos, these dark baryons lie mostly in the circum-galactic medium surrounding the galaxies. At high-z, we view glimpses of these dark baryonic halos through quasar absorption lines, or cooling-radiation emitted as Ly-alpha. Most studies only trace down to this warm gas phase where Lya-cooling is important (~10,000 K). Therefore, a direct connection to the stellar growth of massive galaxies is missing, because we have yet to identify the ultimate reservoir of halo gas that has sufficient mass to fuel widespread star-formation, namely the cold molecular gas (~10-100 K). Using sensitive low-surface-brightness observations of carbon-monoxide (CO), we discovered an extended (~70 kpc) reservoir of molecular gas across the halo of the massive Spiderweb Galaxy, which resides in a proto-cluster at z~2. The bulk of this molecular gas is found outside the radio galaxy as part of an enriched circum-galactic medium, where it fuels widespread `in-situ’ star formation. This result supports the notion that giant cluster galaxies formed from extended regions of recycled gas early in their formation. I will also present cases where we found luminous CO tens of kpc outside the host galaxy, at the tip of the radio jet, as evidence for jet-triggered feedback on scales of galaxy halos. I will argue why typical millimeter observations are not sensitive for tracing this Cold Molecular Medium, and how we can use our telescopes to reliably trace the molecular gas content of the Early Universe.
vendredi 7 octobre 2016 - 11:00
Salle des séminaires Évry Schatzman, Institut d'Astrophysique de Paris
Page web du séminaire / Seminar's webpage