Photoionization Heating of Nova Ejecta by the Post-Outburst Supersoft Source

Abstract

The expanding ejecta from a classical nova remains hot enough ($\sim 10^4\mathrm{K}$) to be detected in thermal radio emission for up to years after the cessation of mass loss triggered by a thermonuclear instability on the underlying white dwarf (WD). Nebular spectroscopy of nova remnants confirms the hot temperatures observed in radio observations. During this same period, the unstable thermonuclear burning transitions to a prolonged period of stable burning of the remnant hydrogen-rich envelope, causing the WD to become, temporarily, a super-soft X-ray source. We show that photoionization heating of the expanding ejecta by the hot WD maintains the observed nearly constant temperature of $(1-4)\times 10^4\mathrm{K}$ for up to a year before an eventual decline in temperature due to either the cessation of the supersoft phase or the onset of a predominantly adiabatic expansion. We simulate the expanding ejecta using a one-zone model as well as the Cloudy spectral synthesis code, both incorporating the time-dependent WD effective temperatures for a range of masses from $0.60M_{\odot }$ to $1.10M_{\odot }$. We show that the duration of the nearly isothermal phase depends most strongly on the velocity and mass of the ejecta and that the ejecta temperature depends on the WD's effective temperature, and hence its mass.

8 pages, 6 figures. Submitted to the Astrophysical Journal

References in corpus (13)

• Modules for Experiments in Stellar Astrophysics (MESA)
• Modules for Experiments in Stellar Astrophysics (MESA): Giant Planets, Oscillations, Rotation, and Massive Stars
• Hydrogen Burning on Accreting White Dwarfs: Stability, Recurrent Novae, and the Post-Novae Supersoft Source
• Swift X-Ray Observations of Classical Novae. II. The Super Soft Source sample
• X-ray monitoring of classical novae in the central region of M31. III. Autumn and winter 2009/10, 2010/11 and 2011/12
• A Prediction Formula of Supersoft X-ray Phase of Classical Novae
• Models for the soft X-ray emission of post-outburst classical novae
• An Accreting White Dwarf near the Chandrasekhar Limit in the Andromeda Galaxy
• X-ray monitoring of classical novae in the central region of M 31. II. Autumn and winter 2007/2008 and 2008/2009
• A remarkable recurrent nova in M31 - The X-ray observations
• The spectroscopic evolution of the recurrent nova T Pyxidis during its 2011 outburst. II.The optically thin phase and the structure of the ejecta in recurrent novae
• New Elemental Abundances for V1974 Cygni
• V723 Cas (Nova Cassiopeiae 1995): MERLIN observations from 1996 to 2001

Cited by in corpus (15)

• A Bright Year for Tidal Disruptions?
• New Insights into Classical Novae
• Gamma-ray emission from internal shocks in novae
• A Detailed Observational Analysis of V1324 Sco, the Most Gamma-Ray Luminous Classical Nova to Date
• Non-Thermal Radio Emission from Colliding Flows in Classical Nova V1723 Aql
• Classical Novae at Radio Wavelengths
• Shock-powered radio emission from V5589 Sagittarii (Nova Sgr 2012 1)
• The multi-wavelength view of shocks in the fastest nova V1674 Her
• Internal Shocks from Variable Outflows in Classical Novae
• The luminosity evolution of nova shells -- I. A new analysis of old data
• Radio light curves and imaging of the helium nova V445 Puppis reveal seven years of synchrotron emission
• Shocks and dust formation in nova V809 Cep
• A Radio Emission Analysis of Classical Nova V351 Pup (1991)
• Today a Duo, But Once a Trio? The Double White Dwarf HS 2220$+$2146 May Be A Post-Blue Straggler Binary
• A half-ring of ionized circumstellar material trapped in the magnetosphere of a white dwarf merger remnant