Abstract
The goal of this project was to determine time delays and the effects of microlensing in gravitationally lensed quasars. We have studied two gravitationally lensed quasars. The fi rst is the sextuply cluster-lensed quasar SDSS J2222+2745, where we have measured the time delays between the three brightest images A, B and C. With respect to image A, the measured time delays are ΔtAB = -42.44 +1.44/-1.36 days, and ΔtAC = 696.65 +2.10/2.00 days (95% confidence interval). This provides a signi cant improvement to existing results and one of the smallest fractional uncertainties measured for a time delay yet (in the AD time delay). We also see strong evidence of gravitational microlensing in both the B and C image, measured with A as a reference.
Secondly, the time delays in the quadruply lensed quasar PS1 J0147+4630 were measured for the fi rst time. The time delays between the four images were found to be ΔtAB = -2.21 +2.08/-2.16, ΔtAC = -5.28 +2.16/-2.22 and ΔtAD = -170.47 ± 7.61 days (95% confi dence interval). We also found microlensing effects in all the images, i.e. images B,C and D with respect to A. The longest time delay is a good candidate for calculating the Hubble constant H0, and by using the lens model from Shajib et al. (2019) and scaled uncertainties, we found a Hubble constant H0 = 79.5 ± 7.95 km s-1 Mpc-1 based on the A-D time delay.
Veileder: Førsteamanuensis Sijing Shen, Institutt for teoretisk astrofysikk, UiO
Medveileder: Forsker Håkon Dahle, Institutt for teoretisk astrofysikk, UiO
Intern sensor: Professor Øystein Elgarøy, Institutt for teoretisk astrofysikk, UiO
Ekstern sensor: Førsteamanuensis Ingunn Burud, Fakultet for Realfag og Teknologi, NMBU