Matthew David Lehnert
Institut d'Astrophysique de Paris
I present ALMA and rest-frame UV observations from MUSE and X-shooter of a sample of distant powerful radio galaxies. These radio galaxies are amongst the most massive galaxies at redshifts 1-3. Our observations provide unique insights into how massive galaxies cease to form stars (quenched) and how they may form their extended envelopes. Surprisingly, our ALMA continuum observations combined with existing Herschel and radio data imply that most of the host galaxies are not forming stars vigorously but lie below the relation between star formation rate and stellar mass for star forming galaxies. The few hosts that do have vigorous star formation have spectral signatures of O- and B-type stars in their rest-frame UV spectra providing robust constraints on their ages and other parameters. Interestingly, we have evidence that at least one radio galaxy has star formation and molecular gas over scales of ~100 kpc and this extended star formation lies on the relation between stellar mass and gas mass surface densities (the "Schmidt-Kennicutt relation"). I discuss the mechanisms underlying these results and the hypothesis that star formation must have played a key role in exhausting the gas supply and extinguishing these galaxies.
2019 February 27, 13:30
Centro de Astrofísica da Universidade do Porto (Auditorium)
Rua das Estrelas, 4150-762 Porto