Multi-wavelength strong lensing study of low redshift cluster cores

May, Paul Edward (2013). Multi-wavelength strong lensing study of low redshift cluster cores. University of Birmingham. Ph.D.

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Abstract

This thesis covers initial work to increase the total number of galaxy clusters with strong lensing features and, therefore, lensing derived masses. These clusters also possess other multi-wavelength measurements that can be, and were, used for comparison. The work included an investigation into what additional information Dressler Shectman analysis of the incomplete redshift cluster member galaxy samples produced as a result of prioritising mask slit placement on potential strong lensing images. With the test blind on areas centred around the BCG, only a qualitative link was found, providing possible assistance with mass model parametisation.

From the sample of eight clusters reduced, five had strong lensing features, of which, A3084 had an unusual and rare lensing configuration. Analysis of A3084 with relatively shallow survey data revealed a cluster with the largest cluster-scale halo centred on the intra-cluster gas and not the BCG: these two were offset from one another. The BCG had a compact DM halo coincident with it, yielding a high substructure fraction of f\(_{sub}\)= 0.73±0.13 which, along with smooth X-ray surface brightness contours, bi-modal cluster galaxy redshift histogram and luminosity map, provided evidence that the interpretation of the cluster had suffered a cluster-cluster merger.

From the redshift reduction, five new strong lensing models were produced following similar methods to the ones used for A3084. With the addition of a cluster from Paraficz et al. (2012), this increased the initial sample size from 17 to 23, providing a ∼ 35% in- crease, with all clusters having other multi-wavelength measurements. Following previous literature comparisons a fit of M SL2D (R < 250 kpc) against T\(_X\) was carried out, but large scatter was observed in this. A possible link was found between the residuals of the fit with that of the clusters’ BCG ellipticity after a cut was made of m\(_{12}\) ≥ 1 for luminosity gap to remove potentially disturbed clusters.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):