RSAA Colloquia / Seminars / Feast-of-Facts: Thursday, 02 May 2019, 13:30-14:30; Duffield Lecture Theatre

Soniya Sharma

"High Resolution Source Reconstruction of Lensed High Redshift Galaxies (End-of-Thesis Talk)"

Strong gravitational lensing coupled with Integral field spectrographic observations (IFS) and adaptive optics (AO) imaging techniques have pioneered spatially resolved studies of high redshift galaxies (z>1). The most magnificent cases of strong lensing are the giant arcs or multiple images around massive galaxy groups or clusters, amplifying the total flux by a factor few times 10-100. With the recent advent of wide-field and multiple IFS (e.g., KCWI, MUSE, KMOS) on large telescopes, we are now entering an era of efficiently collecting spectra along the entire giant arcs. However, there are a number of challenges in recovering the source galaxy properties of such highly magnified arcs. The accuracy and precision of source-plane reconstruction of the most strongly lensed cases are fundamentally limited by 1. the lensing mass model and 2. the effect of the differential point-spread-function (PSF). While a huge effort has been made in the past decade to understand the systematics in lens modelling methods (e.g., Hubble Frontier Fields), relatively fewer work has been done on addressing the effect of the differential PSF. I aim to improve the source reconstruction algorithms to achieve the highest resolution enabled by these lens models. Over the past 4 years of my PhD candidature, we have developed an automated algorithm for forward source modelling of lensed galaxies behind cluster-scale lenses that deconvolves the effects of PSF. Furthermore, this algorithm fully exploits the natural resolution of lensing and allows us to easily combine multiple images of the lensed galaxy to increase the signal to noise ratio in the source plane. Please join me in looking at high-redshift galaxies via nature’s telescopes.