Thesis

Testing the impact of kappa-distributed electron energies in quasar nebulae

• Call:

  IDPASC Portugal - PHD Programme 2016

• Academic Year:

  2016 / 2017

• Domain:

  Astrophysics

• Supervisor:

  Andrew Humphrey

• Co-Supervisor:

• Institution:

  Universidade do Porto

• Host Institution:

  IA / U.Porto / CAUP

• Abstract:

  A long-held assumption is that the electron energies in extrasolar warm ionized nebulae (HII regions, quasar-ionized nebulae, etc.) follow the Maxwell-Boltzmann (MB) distribution. However, direct measurements from a number of plasmas within our Solar system have revealed the presence non-equilibrium electron energy distributions, which have been characterised by the ‘kappa-distribution’ (KD). Armed with the MAPPINGS 1e photoionization code – the first to include kappa-distributed electron energies – an extensive exploration of photoionization model parameter space will be conducted, to ascertain the generalized impact of KD election energies on quasar / AGN line spectra, and how this impact depends on various model parameters (e.g., density, metallicity, kappa, ionization parameter, ionizing spectral energy distribution). Observational tests for the presence of KD in photoionized nebulae will be developed. Moreover, diagnostics of gas physical conditions with the least (or no) dependence on the value of kappa, or on the choice of KD of MB cases, will be developed. The possible impact on BPT diagrams (and similar), and on the spectral classification of emission line galaxies, will also be elucidated.