Stellar masses calibrated with micro-lensed quasars

TL;DR

This paper introduces a novel method using micro-lensing of macro-lensed quasars to directly measure the stellar mass surface densities in early type galaxies, providing a new calibration for stellar mass estimates.

Contribution

It presents a new technique to calibrate stellar masses by analyzing micro-lensing effects, offering an alternative to traditional decomposition methods.

Findings

Median calibration factor F is 1.23 for Salpeter stellar masses.

Confidence interval for F ranges from 0.77 to 2.10.

Method directly measures the graininess of gravitational potential.

Abstract

We measure the stellar mass surface densities of early type galaxies by observing the micro-lensing of macro-lensed quasars caused by individual stars, including stellar remnants, brown dwarfs and red dwarfs too faint to produce photometric or spectroscopic signatures. Our method measures the graininess of the gravitational potential, in contrast to methods that decompose a smooth total gravitational potential into two smooth components, one stellar and one dark. We find the median likelihood value for the calibration factor F by which Salpeter stellar masses (with a low mass cutoff of 0.1 solar masses) must be multiplied is 1.23, with a one sigma confidence range of 0.77 < F < 2.10.