Astro-technology seminar
Time: Monday, October 22, 2018, at 15:30
Location: FCUL, building C1, room 1.4.14
Speaker:
Dr. Fernando Buitrago Alonso (Instituto de Astrofísica e Ciências do Espaço - IA)
Abstract:
There are galaxies that remain untouched since the high-z Universe. These objects, the so-called relic galaxies, are several times more massive than our Milky Way but with much smaller sizes, and containing very old (>10 Gyr) stellar populations. For the very few of them already found and analysed, they seem to host "too heavy" central super massive black holes, also displaying an overabundance of low mass vs high mass stars and retaining their primeval morphologies and kinematics. How did they survive until the present day? Simulations predict that they live in galaxy overdensities whose large internal random motions prevent galaxies from merging. However, we have not yet determined observationally neither the environments these galaxies inhabit nor how many there are (their number densities). I am participating in the GAMA survey, that allows us to conduct a complete census of this elusive galaxy population, because of its large area and spectroscopy. After inspecting hundreds of square degrees of the sky using the deepest photometric images, we have identified 29 of these unique relics in the nearby Universe (up to 1500 Mpc distance), that are true windows to the ancient Universe. I will present the first paper about this exceptional sample, describing its properties and highlighting the fact that while some of galaxies seem to be satellites of bigger objects, others do not reside in clusters, at odds with the theoretical expectations.