Revealing an Oscillating and Contracting Compact Corona near the Event Horizon of the Supermassive Black Hole in 1ES 1927+654

TL;DR

This study uncovers a contracting, oscillating corona near a supermassive black hole in 1ES 1927+654, using phase-resolved analysis of a quasi-periodic oscillation to reveal coronal dynamics and geometry.

Contribution

First observational evidence of an oscillating and contracting compact corona around a supermassive black hole, based on novel phase-resolved analysis of QPOs.

Findings

Detection of a unique `U'-shaped QPO lag-energy spectrum

Coronal spectral variability observed over QPO phase

Corona is contracting within a few gravitational radii near SMBH

Abstract

Dynamic processes in the accretion flow near black holes produce X-ray flux variability, sometimes quasi-periodic. Determining its physical origin is key to mapping accretion geometry but remains unresolved. We perform a novel phase-resolved analysis on a newly discovered quasi-periodic oscillation (QPO) in the active galactic nucleus 1ES 1927+654. For the first time in a supermassive black hole (SMBH), we detect a unique `U'-shaped QPO lag-energy spectrum and observe coronal spectral variability over the QPO phase. We find that the QPO is adequately explained by plasma resonant oscillations within a corona. Modeling of QPO spectral properties and reverberation mapping reveal that the corona is contracting and confined to only a few gravitational radii regions near the SMBH, consistent with theoretical predictions for a decreasing QPO period of near 10 minutes. These results present the first observational evidence for an oscillating and contracting compact corona around an SMBH.