Despite the remarkable success of the Lambda Cold Dark Matter (LCDM) cosmological model, several challenges have recently emerged. One of the most prominent is the “Hubble tension”: the Hubble expansion rate (H_0) measured using the Cepheid-calibrated distance ladder of type Ia supernovae and the value extrapolated from the cosmic microwave background using LCDM disagree by 5 standard deviations. To confirm that new physics beyond the LCDM model is needed to resolve this disagreement, we must rule out any unknown systematic errors in these measurements using another independent probe. Strong gravitational lensing time delays provide such a probe that can independently constrain H_0 to 1% precision and potentially confirm new physics. This will be made possible by the very large samples of galaxy-scale lenses to be discovered by the Rubin and Roman Observatories — two orders of magnitude larger than current samples — and with follow-up data from the JWST. These surveys will also provide new samples of exotic lenses to competitively constrain dark energy parameters and to study the impact of baryonic feedback on the evolution of massive galaxies to redshift z~1. Strong lensing in the JWST-Rubin-Roman era thus promises a revolution in the study of both cosmology and galaxy evolution.
BIO
Anowar Shajib is a NASA Einstein Fellow at the University of Chicago and a KICP Fellow at the Kavli Institute of Cosmological Physics in Chicago. He was born and raised in Bangladesh. After finishing high school in Bangladesh, he moved to Japan for his undergraduate studies at the University of Tokyo. Then, he moved to the USA and finished his PhD in 2020 at the University of California, Los Angeles, with Prof. Tommaso Treu as his thesis advisor.
Anowar’s principal research interest is using strong gravitational lensing for observational cosmology and studying galaxy evolution. He works with galaxy-galaxy strong lenses and strongly lensed quasar/supernova systems to measure cosmological parameters such as the Hubble constant and to study properties of elliptical galaxies at the intermediate redshift (z∼0.5). He is currently one of the co-conveners of the Strong Lensing Topical Team within the Rubin Observatory LSST’s Dark Energy Science Collaboration (DESC). He is also an active member of a few other collaborations, including TDCOSMO, H0LiCOW, and Rubin LSST’s Strong Lensing Science Collaboration.
