Gravitational Lensing and Dynamics (GLaD): Combined analysis to unveil properties of high-redshift galaxies

Abstract

The dynamical modelling of integral field unit (IFU) stellar kinematics is a powerful tool to unveil the dynamical structure and mass build-up of galaxies in the local Universe, while gravitational lensing is nature's cosmic telescope to explore the properties of galaxies beyond the local Universe. We present a new approach, which unifies dynamical modelling of galaxies with the magnification power of strong gravitational lensing, to reconstruct the structural and dynamical properties of high-redshift galaxies. By means of axisymmetric Jeans modelling, we create a dynamical model of the source galaxy, assuming a surface brightness and surface mass density profile. We then predict how the source's surface brightness and kinematics would look when lensed by the foreground mass distribution and compare with the mock observed arcs of strong gravitational lensing systems. For demonstration purposes, we created and also analysed mock data of the strong lensing system RX J1131-1231. By modelling both the lens and source, we recover the dynamical mass within the effective radius of strongly lensed high-redshift sources within 5% uncertainty, and we improve the constraints on the lens mass parameters by up to 50%. This machinery is particularly well-suited for future observations from large segmented-mirror telescopes, such as the James Webb Space Telescope, which will yield high sensitivity and angular-resolution IFU data for studies on distant and faint galaxies.