AR 16149 (Archival Research)

Sat Jul 20 09:55:49 GMT 2024

Principal Investigator: Anowar Shajib
PI Institution: University of Chicago
Investigators (xml)

Title: Systematics in H_0 from lensing: a comprehensive study of internal structure in elliptical galaxies
Cycle: 28

Recently, there has been a strong tension between different measurements of the Hubble constant, H_0. If systematics can be ruled out in these measurements, then this discrepancy will point to new physics either beyond the standard Lambda cold dark matter cosmology, or beyond our current understanding of the galactic/stellar astrophysics. Time-delay cosmography has provided a competitive measurement of H_0 with ~2% uncertainty combining only seven lens systems. However, if the true mass distribution deviates from the power law, the assumption of a power-law mass distribution in the lens galaxies can be a source of systematic in the measured H_0. We will analyze a large sample of galaxy-galaxy lenses that is representative of the time-delay lens population to study the internal structure of the elliptical lens galaxies. We will identify if the mass distribution in these galaxies deviate from (or closely follow) the power law and thus the presence (or absence) of systematic biases in the reported H_0 values from time-delay cosmography. Furthermore, we will provide tight empirical priors for elliptical galaxy structural parameters for use in future time-delay lens analyses.