A NuSTAR observation of the fast symbiotic nova V745 Sco in outburst

Abstract

The fast recurrent nova V745 Sco was observed in the 3-79 keV X-rays band with NuSTAR 10 days after the optical discovery. The measured X-ray emission is consistent with a collisionally ionized optically thin plasma at temperature of about 2.7 keV. A prominent iron line observed at 6.7 keV does not require enhanced iron in the ejecta. We attribute the X-ray flux to shocked circumstellar material. No X-ray emission was observed at energies above 20 keV, and the flux in the 3-20 keV range was about 1.6 $\times$ 10${}^{-11}$ erg cm${}^{-2}$ s${}^{-1}$. The emission measure indicates an average electron density of order of 10${}^7$ cm${}^{-3}$. The X-ray flux in the 0.3-10 keV band almost simultaneously measured with Swift was about 40 times larger, mainly due to the luminous central supersoft source emitting at energy below 1 keV. The fact that the NuSTAR spectrum cannot be fitted with a power law, and the lack of hard X-ray emission, allow us to rule out Comptonized gamma rays, and to place an upper limit of the order of 10${}^{-11}$ erg cm${}^{-2}$ s${}^{-1}$ on the gamma-ray flux of the nova on the tenth day of the outburst.

in press in Monthly Notices of the Royal Astronomical Society, 2014

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• Shocks in nova outflows. I. Thermal emission
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• Near-IR studies of recurrent nova V745 Scorpii during its 2014 outburst
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• Evolution of X-ray spectra and light curves of V1494 Aquilae
• The Swift BAT Perspective on Non-thermal Emission in HIFLUGCS Galaxy Clusters

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• Chandra High Energy Transmission Gratings Spectra of V3890 Sgr
• Origin of asymmetries in X-ray emission lines from the blast wave of the 2014 outburst of nova V745 Sco
• X-ray Spectroscopy of the gamma-ray Brightest Nova V906 Car (ASASSN-18fv)
• The multi-wavelength view of shocks in the fastest nova V1674 Her
• Chemical and physical parameters from X-ray high resolution spectra of the Galactic nova V959 Mon
• Early multiwavelength analysis of the recurrent nova V745 Sco
• Supersoft X-Ray Phases of Recurrent Novae as an Indicator of their White Dwarf Masses
• X-ray evolution of the nova V959 Mon suggests a delayed ejection and a non-radiative shock
• A Reanalysis of High Resolution XMM-Newton Data of V2491 Cyg Using Collisionally Ionized Hot Absorber Models
• Dissecting accretion and outflows in accreting white dwarf binaries
• AT 2019qyl in NGC 300: Internal Collisions in the Early Outflow from a Very Fast Nova in a Symbiotic Binary