V392 Persei: a \gamma-ray bright nova eruption from a known dwarf nova

TL;DR

V392 Persei, a known dwarf nova, experienced a rapid and bright nova eruption in 2018, exhibiting multiple mass ejections, shock-driven gamma-ray emission, and a transition to a high mass transfer state post-eruption, revealing complex nova-dwarf nova interactions.

Contribution

This study provides the first multi-wavelength, long-term observation of V392 Persei's nova eruption, highlighting its rapid evolution, shock interactions, and sustained high mass transfer state after eruption.

Findings

V392 Per is one of the fastest evolving novae with a 2-day decline time.

Evidence of multiple interacting mass ejections and shocks driving gamma-ray and optical luminosity.

Post-eruption, the system remains in a high mass transfer state driven by irradiation effects.

Abstract

V392 Persei is a known dwarf nova (DN) that underwent a classical nova eruption in 2018. Here we report ground-based optical, Swift UV and X-ray, and Fermi-LAT \gamma-ray observations following the eruption for almost three years. V392 Per is one of the fastest evolving novae yet observed, with a $t_2$ decline time of 2 days. Early spectra present evidence for multiple and interacting mass ejections, with the associated shocks driving both the \gamma-ray and early optical luminosity. V392 Per entered Sun-constraint within days of eruption. Upon exit, the nova had evolved to the nebular phase, and we saw the tail of the super-soft X-ray phase. Subsequent optical emission captured the fading ejecta alongside a persistent narrow line emission spectrum from the accretion disk. Ongoing hard X-ray emission is characteristic of a standing accretion shock in an intermediate polar. Analysis of the optical data reveals an orbital period of 3.230 \pm 0.003 days, but we see no evidence for a white dwarf (WD) spin period. The optical and X-ray data suggest a high mass WD, the pre-nova spectral energy distribution (SED) indicates an evolved donor, and the post-nova SED points to a high mass accretion rate. Following eruption, the system has remained in a nova-like high mass transfer state, rather than returning to the pre-nova DN low mass transfer configuration. We suggest that this high state is driven by irradiation of the donor by the nova eruption. In many ways, V392 Per shows similarity to the well-studied nova and DN GK Persei.