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  • Type Ib/c Supernovae, host galaxies and Gamma-ray Bursts

    Prof P. Mazzali, Prof. P. James & Dr D. Bersier

    Massive stars end their lives when their core can no longer produce nuclear energy and collapses under its own gravity. This produces a compact remnant (a Neutron Star or a Black Hole). An explosion ensues that ejects the outer layers of the star in a bright display known as a Supernova. Although even a massive star should be composed mostly of hydrogen and helium, in some cases these elements have been lost in a wind or through binary interaction. The SN is then called type Ib (if only H was lost) or Ic (if He was also lost). This is the best opportunity for us to observe the details of the explosion, which affects mostly the inner regions of the star. These SNe are also linked to one of the most mysterious phenomena in the Universe, Gamma-ray Bursts, but the relation between GRBs, SNe Ib/c and their progenitor stars are only superficially understood.

    The aim of this project is to quantify the properties of SNe Ib/c, compare to those of the possible progenitor stars, attempt to infer the nature of the compact object left behind (NS v. BH), and to determine whether special conditions are required for the production of a GRB.

    The student working on this topic will have access to a large database of SN Ib/c data (light curves and spectra), as well as to radiation transport codes which can be used to model the data and extract physical information. The thesis can be developed according to the student's vocation. The student can take part in observational campaigns (telescopes on La Palma and in Chile, observations with HST) and work on the analysis of the data; investigate the properties of existing datasets (e.g. attempting to subclassify SNe as a function of energy released, building a luminosity function which should reflect the properties of the progenitor stars, investigating properties that depend on host galaxy type, and looking in detail at the local environments of different SN types within their host galaxies); perform detailed modelling of individual SNe in order to determine their properties with a high level of accuracy and confidence; compare observational results with the predictions of theoretical models; and work on extending and improving existing codes and testing these new tools.

    The student will have opportunities to work with a number of collaborators both in the UK and abroad while pursuing his/her thesis work.