Microlensing Evidence That A Type 1 Quasar Is Viewed Face On

TL;DR

This study uses microlensing data over 11 years to determine that a specific quasar's accretion disk is viewed face-on, measuring its size and challenging simple thin disk models.

Contribution

It provides the first microlensing-based measurement of the inclination angle of a quasar's accretion disk, constraining its orientation and size.

Findings

Inclination angle is likely face-on with cos i > 0.66 at 68% confidence.

Accretion disk radius measured to be approximately 5.8 x 10^15 cm.

Projected disk area exceeds predictions from simple thin disk models.

Abstract

Using a microlensing analysis of 11-years of OGLE V-band photometry of the four image gravitational lens Q2237+0305, we measure the inclination i of the accretion disk to be cos i > 0.66 at 68% confidence. Very edge on (cos i < 0.39) solutions are ruled out at 95% confidence. We measure the V-band radius of the accretion disk, defined by the radius where the temperature matches the monitoring band photon emission, to be R_V = 5.8 (+3.8) (-2.3) x 10^15 cm assuming a simple thin disk model and including the uncertainties in its inclination. The projected radiating area of the disk remains too large to be consistent with the observed flux for a T proportional to R^-3/4 thin disk temperature profile. There is no strong correlation between the direction of motion (peculiar velocity) of the lens galaxy and the orientation of the disk.