Gamma-ray burst host galaxies

I work at the Department of Physics and Astronomy of the University of Leicester, in the X-ray and Observational Astronomy group. My main interests are the environments of the most extreme explosions in the Universe: gamma-ray bursts. I am interested in using GRBs as a tool to understand galaxies, and galaxies as a tool to understand GRBs (particularly to narrow down the families of possible progenitor models). To gain better knowledge I am interested in acquiring large samples of basic data as well as detailed studies of individal (bright) sources. I am most interested in detailed spectroscopy of GRB afterglows at high redshift, and GRB host galaxies at low redshift. These datasets allow us to derive element abundances, temperature and kinematics of the circumburst medium (and of course the redshift of the burst). Variable excited finestructure lines are frequently found in GRB afterglow spectra, giving us a wealth of information about the ISM in dwarf starforming galaxies at high redshift. At the low redhsift end, I am interested in the dust properties of the starforming regions in which GRBs form, as well as in the properties of the stellar populations in these regions. To further our understanding of GRB environments I do observations of GRBs in Target of Opportunity mode with large telescopes (e.g. VLT, Gemini, WHT) as well as service and visitor mode observations of their hosts.

Gamma-ray burst afterglows

The afterglows of GRBs form a unique laboratory for relativistic shock physics. To derive the physical parameters that play a role (a good 8 parameters even for the simplest models) we require lightcurves and spectra at high cadence over a long time interval and using a wide wavelength range, from radio to X-rays. I do rapid ToO observations of GRB afterglows with large optical telescopes, and am involved in efforts to get good datasets at longer and shorter wavelengths. In particular I am PI (or was PI in the past) of programmes at VLT to obtain high accuracy polarimetry and photometric jet breaks.

X-ray binaries and ULXs

Recently I have become interested in X-ray binaries and ULXs, as local laboratories of accretion and jet physics. My main interest is again in the optical wavelengths, particularly in spectroscopic characterisations of these objects. I have been involved several programmes at VLT and Gemini, and led papers for spectroscopic or photometric studies of peculiar sources, in particular SAX J1712-3739, XTE 1710-281 and the most promising intermediate mass black hole candidate to date: HLX-1.

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