Astro2020 Science White Paper: A New Era for X-ray Lensing Studies of Quasars and Galaxies

TL;DR

This white paper advocates for a new X-ray telescope with high spatial resolution and large collecting area to enable advanced studies of gravitational lensing in quasars and galaxies, leveraging upcoming surveys like LSST.

Contribution

It proposes specific technical requirements for future X-ray telescopes to significantly enhance gravitational lensing research with large samples from LSST.

Findings

Current X-ray telescopes limit lensing studies due to resolution and sensitivity.

LSST will discover over 4,000 new lensed systems, expanding research opportunities.

A telescope with <0.5 arcsec resolution and >0.5 m^2 area at 1 keV is needed.

Abstract

Current X-ray observations and simulations show that gravitational lensing can be used to infer the structure near the event horizons of black holes, constrain the dynamics and evolution of black-hole accretion and outflows, test general relativity in the strong-gravity regime and place constraints on the evolution of dark matter in the lensing galaxies. These science goals currently cannot be achieved in a statistically large sample of z = 0.5 - 5 lensed quasars due to the limited capabilities of current X-ray telescopes and the relatively low number (~200) of known lensed quasars. The latter limitation will be resolved with the multi-band and wide-field photometric optical survey of LSST that is expected to lead to the discovery of > 4,000 additional gravitationally lensed systems. As we show in this white paper, these science goals can be reached with an X-ray telescope having a spatial resolution of <0.5arcsec to resolve the lensed images and a collecting area of >0.5 m^2 at 1 keV.