Discovery of spin modulated circular polarization from IGR J17014-4306, the remnant of Nova Scorpii 1437 A.D

TL;DR

This study reports the discovery of spin-modulated circular polarization in IGR J17014-4306, confirming it as the longest period eclipsing intermediate polar, with polarization indicating cyclotron emission from a magnetic white dwarf.

Contribution

It is the first detection of spin-modulated circular polarization in this system, revealing its magnetic and accretion properties and its status as a long-period eclipsing intermediate polar.

Findings

Periodic circular polarization confirms magnetic white dwarf presence.

System identified as the longest period eclipsing intermediate polar.

Negative polarization suggests one magnetic pole dominates emission.

Abstract

Polarimetry of IGR J1401-4306, a long period (12.7 hours), eclipsing intermediate polar and remnant of Nova Scorpii 1437 A.D., reveals periodic variations of optical circular polarization, confirming the system as the longest period eclipsing intermediate polar known. This makes it an interesting system from an evolutionary perspective. The circular polarization is interpreted as optical cyclotron emission from an accreting magnetic white dwarf primary. Based on the polarimetry, we propose that it is a disc-fed intermediate polar. The detection of predominantly negative circular polarization is consistent with only one of the magnetic poles dominating the polarized emission, while the other is mostly obscured by the accretion disc.