LBQS 0103-2753: A Binary Quasar in a Major Merger

TL;DR

This paper reports on the discovery and analysis of a close binary quasar system in a major galaxy merger, showing simultaneous high-luminosity activity in both black holes at a late merger stage.

Contribution

It provides detailed imaging and spectral evidence of a binary quasar in a major merger, demonstrating simultaneous black hole fueling at small nuclear separation.

Findings

Binary quasar LBQS 0103-2753 is at 2 kpc separation.

Both quasars are at the same redshift, confirming a physical pair.

The system shows active black hole fueling during a late-stage merger.

Abstract

We present HST and UKIRT spectra and images of the 2 kpc binary quasar LBQS 0103-2753 (z=0.858). The HST images (V- and I-band) show tidal features demonstrating that this system is a major galaxy merger in progress. A two-color composite image brings out knots of star formation along the tidal arc and elsewhere. The infrared spectrum shows that both objects are at the same redshift, and that the discrepant redshift of C IV in component A is a consequence of the BAL absorption in the spectrum of this component. LBQS 0103-2753 is one of the most closely spaced binary QSOs known, and is one of relatively few dual AGN showing confirmed broad emission lines from both components. While statistical studies of binary QSOs suggest that simultaneous fueling of both black holes during a merger may be relatively rare, LBQS 0103-2753 demonstrates that such fueling can occur at high luminosity at a late stage in the merger at nuclear spacing of only a few kpc, without severe obscuration of the nuclei.