Modelling the Light Echo in Active Galaxy BL Lacertae Using High-Cadence Light Curve Data

Overview

Active galactic nuclei (AGN) are supermassive black holes found at the centre of galaxies. AGN BL Lacertae contains an accretion disk and high-energy jets emitted perpendicular to the disk, aimed at Earth. Above and below the accretion disk lies a turbulent, billion-degree cloud, called the corona. It emits high-energy X-rays, which are reflected off the accretion disk, producing light echoes. The red and near-infrared band of this light echo was captured by NASA’s TESS telescope, measuring light intensity every 20 seconds. By applying machine learning models and the partial autocorrelation function to this light curve, the light echo length, innermost stable circular orbit (ISCO), and orbital velocity of visible and dark matter were estimated. Comparing the ISCO radius to the event horizon of a stationary black hole of equal mass, BL Lacertae is confirmed to be a Kerr black hole, spinning in the same direction as its accretion disk.

Awards (2)

• Silver Medal
• Selected for CWSF 2026

Competition history

• CWSF 2026 Aerospace

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