AstroSat Soft X-ray observations of the symbiotic recurrent nova V3890 Sgr during its 2019 outburst

Abstract

Two long AstroSat Soft X-ray Telescope observations were taken of the third recorded outburst of the Symbiotic Recurrent Nova, V3890 Sgr. The first observing run, 8.1-9.9 days after the outburst, initially showed a stable intensity level with a hard X-ray spectrum that we attribute to shocks between the nova ejecta and the pre-existing stellar companion. On day 8.57, the first, weak, signs appeared of Super Soft Source (SSS) emission powered by residual burning on the surface of the White Dwarf. The SSS emission was observed to be highly variable on time scales of hours. After day 8.9, the SSS component was more stable and brighter. In the second observing run, on days 15.9-19.6 after the outburst, the SSS component was even brighter but still highly variable. The SSS emission was observed to fade significantly during days 16.8-17.8 followed by re-brightening. Meanwhile the shock component was stable leading to increase in hardness ratio during the period of fading. AstroSat and XMM-Newton observations have been used to study the spectral properties of V3890 Sgr to draw quantitative conclusions even if their drawback is model-dependence. We used the xspec to fit spectral models of plasma emission, and the best fits are consistent with the elemental abundances being lower during the second observing run compared to the first for spectra >1 keV. The SSS emission is well fit by non-local thermal equilibrium model atmosphere used for white dwarfs. The resulting spectral parameters, however, are subject to systematic uncertainties such as completeness of atomic data.

15 pages, 10 figures, Accepted for publication in the Monthly Notices of the Royal Astronomical Society

References in corpus (7)

• The Super-Soft X-ray Phase of Nova RS Ophiuchi 2006
• NLTE model atmospheres for the hottest white dwarfs: Spectral analysis of the compact component in nova V4743 Sgr
• Three-dimensional modeling of the asymmetric blast wave from the 2006 outburst of RS Ophiuchi: Early X-ray emission
• Origin of asymmetries in X-ray emission lines from the blast wave of the 2014 outburst of nova V745 Sco
• Chandra High Energy Transmission Gratings Spectra of V3890 Sgr
• Theoretical Studies of Accretion of Matter onto White Dwarfs and the Single Degenerate Scenario for Supernovae of Type Ia
• Hydrodynamic Simulations of Classical Novae; CO and ONe White Dwarfs are Supernova Ia Progenitors

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• The symbiotic recurrent nova V3890 Sgr: binary parameters and pre-outburst activity
• The Super-Soft Source Phase of the recurrent nova V3890 Sgr
• Science with the $AstroSat$ Soft X-ray Telescope: an overview
• Synchrotron emission from double-peaked radio light curves of the symbiotic recurrent nova V3890 Sagitarii
• X-ray observations of the nova shell IPHASX J210204.7+471015
• Survival of the accretion disk in LMC Recurrent Nova 1968-12a: UV--X-ray case study of the 2024 eruption