Letters of Intent received in 2018

LoI 2020-2033
Non-GA Symposium: Galaxy Evolution and Feedback Across Different Environments

Topics

1 - Formation and early evolution of galaxies and their supermassive black holes (SMBHs)

2 - Growth of galaxies and SMBHs: evolution of galaxy dynamics, stellar populations, star formation rates, gas content and metallicity

3 - Mechanisms for fuelling star formation and AGN

4 - Stellar and AGN feedback and their impact on host galaxies and SMBH

5 - The role of dense environments: galaxy evolution and SMBH growth in groups and clusters

Rationale

Abstract and Goals: We propose an IAU Symposium to bring together the AGN (Active Galactic Nuclei) and Galaxy Evolution communities in order to advance our understanding of the interplay between these two processes via observations and models across different environments and cosmic time. How do galaxies acquire their gas and how efficiently is it transformed into stars? What is the main physical mechanism that quenches star formation? How is the Supermassive Black Hole in the center fuelled to become an AGN? How powerful are the stellar and AGN feedback processes in regulating galaxy evolution? Which is the role of the environment on galaxy evolution and AGN triggering? An IAU Symposium addressing these topics is timely due to the recent availability of new studies of distant and nearby galaxies via integral field spectroscopy (IFS) surveys in the optical and infrared, new results from ALMA, LOFAR and SKA pathfinders, and the observation of the interplay between radio and X-ray observations in galaxy clusters. These capabilities allow: (1) the observation of different gas phases - molecular, neutral and ionized; (2) spatially resolving the star formation histories and the feeding and feedback processes at play inside the galaxies; (3) the observation of the effects of the environment and interactions between galaxies and with the intergalactic medium.

From high z to the present-day Universe - We shall address the formation of galaxies at very high redshifts (z~10-4), as well as their early evolution and feeding by streams from the cosmic web, comparing prediction from models with observations. At z~1-4, we shall address the "compaction events" and the formation and evolution from “blue nuggets” to "red nuggets" and their relation with AGN, again comparing models to observations.

The role of AGN as agents of galaxy evolution is now a fundamental ingredient of galaxy evolution models, and observations reveal their importance also in studies focusing on other properties, such as star formation. In the near-IR, surveys of star forming galaxies at z=1-3 (with the instruments KMOS & MOSFIRE) - which have now observed more than a thousand galaxies - there is compelling evidence for AGN driven outflows from galaxies that were previously not expected to host significantly powerful AGN. There is a lot that these large high redshift surveys can contribute to our understanding of galaxy evolution and the role played by AGN. These surveys are complementary to the low redshift ones, such as CALIFA and MANGA, but so far studies focusing on star formation seem to be disconnected with those focusing on AGN. With this Symposium, we hope to bridge the studies on feedback from the ``galaxy evolution community", that focus mostly in the role of star formation, and the ``AGN community", which concentrate on feedback from the environs of the nuclear SMBH, in order to advance our understanding of galaxy evolution, comparing model predictions with observations.

In the near Universe, low surface brightness observations are revealing that cold gas flows and low-luminosity dwarf galaxies may have played an important role in shaping the present day massive galaxies. IFS surveys such as CALIFA, MaNGA and SAMI are providing spatially resolved studies of the stellar population properties in galaxies allowing the mapping of its star formation history. Detailed studies with Gemini, Keck and the Very Large Telescopes are allowing increasingly detailed constraints on the magnitude of inflows and outflows in the inner kiloparsec of galaxies, as well as on the mechanisms of feeding and feedback. The access to the geometry of the flows and their velocity fields is also allowing the constraint of the feedback power of the outflows and the impact on the host galaxies, which shall be compared to those required by models. These constraints - observed in the optical and near-infrared, need to be combined with those provided by the observations of outflows in neutral (e.g. LOFAR and SKA pahtfinders) and molecular gas phases (e.g. ALMA), that, in many cases dominate the mass and power of the outflows.

High energy and feedback in galaxy groups and clusters - Direct emission from AGN is better isolated at high energies, and catalogs from Swift, Chandra, and XMM have been fundamental to pinpoint and provide a census of these sources at a range of redshifts that is independent of obscuration. Current generation of X-ray satellites have revealed a complex interplay between cooling and heating in the large scale environments of active galaxies, from both spectroscopic measurements of gas cooling and high resolution imaging of jets interacting with the hot intergalactic medium in galaxy clusters and groups. Multiphase gas can now be observed in the hot halo, with cooling gas being observed falling into the galaxies where they can trigger and feed an AGN. Feedback from the AGN is observed as radio jets extending to hundreds of thousands of kpc, where their interaction with ambient gas produce X-ray emission. The digging of cavities is now seen in X-rays with Chandra in galaxies, groups, and clusters (e.g. NGC5044, NGC5846, NGC4636, Perseus and Phoenix Cluster), and their increasingly deep observations are allowing to constrain also this type of feedback. We will discuss the most recent results obtained with current X-ray facilities in comparison with those expected to be achieved with the next generation of X-ray telescopes.

Lower energy and molecular and neutral gas - Observations of distant galaxies and AGN are becoming available with ALMA, and by 2020 we expect to have the first results from the HI surveys with LOFAR and the new SKA pathfinders which will allow us to trace the evolution of the atomic hydrogen content of the Universe. Unexpected large amounts of molecular gas have been seen with ALMA in many groups, where it has been concluded that they provide the necessary fuel for the growing SMBHs and the surrounding galaxy. ALMA is also revealing the first signatures of inflows in molecular gas within the inner kpc of galaxies, although more common being the outflows, which reach tens of solar masses per year in some sources. These high mass outflow rates suggest that molecular gas is the dominant phase of outflows in galaxies. Outflows are also observed in neutral gas, and the new surveys with the SKA pathfinders and LOFAR mentioned above will also introduce new constraints on the occurrence of outflows in radio galaxies.

Outreach: Outreach activities are a tradition in our Department at IF-UFRGS (Instituto de Fisica da Universidade Federal do Rio Grande do Sul) in Porto Alegre, with two on-going successful programs: (1) "Meninas na Ciência" with the goal to stimulate young female students in the pursuing of science, capturing their interests via hands-on astronomy activities; (2) "Observatorio Educativo Itinerante", through which we visit schools mostly in the countryside with activities for teachers of high and fundamental schools with a Van where we also bring a Meade portable telescope for night-time observations. We plan to promote activities in these two programs both for students and for the general public, besides promoting public talks at night, taking advantage of the excellent lectures expected to come to the conference in the topics of Galaxy Formation, Galaxy Evolution, Supermassive Black Holes and Galaxy Clusters.