Galaxy formation and evolution from the early universe to today

Understanding how galaxies form in the early universe and how they evolve through cosmic time is one of the main aims of modern cosmology. In the past decade astrophysical research has clearly demonstrated that a panchromatic – X-ray to radio – observational approach is key to developing a consensus on galaxy evolution and formation.

Based on observations of the sky over the full electromagnetic spectrum, with facilities such as e.g. the XMM-Newton, Chandra, GALEX, Hubble, Spitzer, and Herschel space telescopes, large 8-10m class ground based telescopes, dedicated survey telescopes, and VLA, ATCA, PdBI mm/radio interferometers, past studies have significantly advanced our understanding of galaxy formation and evolution. Galaxies are now thought to generally evolve from an initial stage of blue star forming disk or irregular galaxies towards quiescent red galaxies with elliptical (or S0) morphologies and with typically high stellar masses M∗ ∼ 1011 M. This evolution is non–linear and driven by both on-going but variable accretion and episodes of intensive star formation and supermassive black hole (SMBH) activity triggered by galactic merging, secular evolution, or hot halo accretion. Both the stellar body and SMBHs in the galaxy build up via strong accretion episodes, with the bulk activity peaking when the universe was ~2-6 Gyr old (z=1-3). The bulk stellar and SMBH build up in the universe appears to be roughly coeval, yet in individual galaxies the star formation phase presumably precedes the onset of SMBH growth, or vice-versa.

One of the surprising discoveries of the past decade was the tight (σ<0.3 dex) relationship at redshift z<1 between stellar mass and the star formation rate per unit mass (Specific Star Formation rate or SSFR). Evolution in the scatter, outlier fraction, normalization and slope of this relationship imply changes in the gas content and relative importance of mergers and quenching mechanisms. Both vigorous star formation and SMBH growth have been shown to impact the properties of the galaxy itself by quenching its star formation either by heating or expelling a fraction of the galaxy’s gas (so called stellar or AGN feedback). These feedback processes, considered by now to be key mechanisms in galaxy formation and evolution, are regularly invoked in state-of-the-art cosmological models and are crucial to reproduce the observed galaxy properties, such as the galaxy color bimodality, luminosity and stellar mass functions.

Although major advances in understanding the formation and evolution of galaxies have been achieved in the last decade, many questions still remain open: What are the triggers for star formation? Which mechanisms shape galaxies over cosmic time? Can AGN feedback be observationally supported as an important process in galaxy formation over cosmic time?

Given the current major development of next-generation facilities and projects, such as e.g. the JVLA, SKA, ALMA, Pan-STARRS, LSST, JWST, the symposium is intended to synthesize the state-of-the art of the field of galaxy formation and evolution, and discuss open questions to be solved in the next decade. In particular, the symposium will focus on

  1. Major discoveries in the context of galaxy formation and evolution in the last decade of multi-wavelength surveys, such as the SDSS, FIRST, NVSS, COSMOS, GOODS, CANDELS, Ultra-VISTA, VVDS, CFHTLS/WIRDS, SXDS, UKIDSS etc.
  2. Open questions in galaxy formation and evolution
  3. Upcoming surveys, projects, and facilities, such as LSST, EMU, JWST, ALMA, SKA, ELTs, EUCLID, SUMIRE, VUDS, eROSITA etc

Galaxy formation and evolution from the early universe to today