Thesis

The KMOS/VLT revolution: rotation curves, metallicities, dust extinction and galaxy formation and evolution with hundreds of very distant galaxies

• Call:

  IDPASC Portugal - PHD Programme 2014

• Academic Year:

  2014 /2015

• Domain:

  Astrophysics

• Supervisor:

  David Sobral

• Co-Supervisor:

• Institution:

  Faculdade de Ciências - Universidade de Lisboa

• Host Institution:

  Faculdade de Ciências - Universidade de Lisboa

• Abstract:

  What are the physical drivers of galaxy formation and evolution? How much (and why) did galaxies like our own change across cosmic time (e.g. metallicities, dynamics)? When, how and through which physical mechanisms are galaxies “quenched”? In order to make progress, the student will explore our unique, large surveys that have yielded 1000s of galaxies (similar to the Milky Way), selected in the same way across the last 11 billion years (with WIRCam/CFHT and WFCAM/UKIRT telescopes). These are ideal samples to study the metallicities, dust extinction and rotation curves/dynamics of “typical” star-forming galaxies and how these have evolved from the peak of the star-formation history (z~2.5) till today. By using KMOS (observations already started and thus all data is guaranteed both as PI and as part of GTO collaboration), the student will be able to gain unprecedentedly detailed information on a large sample of galaxies. KMOS, with its 24 Integral Field Units (IFUs) allows to target up to 24 galaxies at the same time, obtaining an image and a near-infrared spectrum for each pixel. This is a unique opportunity to map the distribution and intensity of star formation, dynamics and metallicity on ~4 kpc scales and address (and to fully interpret them): (i) What is the fraction of primitive disks, spheroids and mergers? (ii) Is the distribution of star formation at high-z more centrally concentrated than comparably luminous/turbulent galaxies at z~0? and iii) Are chemical abundance gradients weaker or stronger than local spiral galaxies and do those change with time? Answers to these questions using our well selected samples will provide some of the strongest tests/constraints to the most sophisticated models of galaxy formation and evolution. By selection, all of the targets have known Hα fluxes and all are sufficiently bright so their resolved properties can be recovered and the survey efficiency will be >95% (GTO observations already yielded samples of ~400 galaxies). The results will be fully compared and contrasted to the best local IFU surveys (including artificially redshifting a variety of local galaxies and fully addressing biases and systematics), and will be interpreted using our unique 3D modelling capabilities developed at CAUP. Another unique aspect of this project is that there are significant over-densities in the very large samples of Hα emitters, and thus, with KMOS, the student will be able to confirm and characterise the high redshift structures, derive accurate metallicities, measure the mass-metallicity relation, obtain Balmer decrement extinctions and identify AGN for a sample of hundreds of Hα-selected galaxies and investigate if the environment plays a role in setting these galaxy properties.