Multiwavelength modeling the SED of Luminous Supersoft X-ray Sources in Large Magellanic Cloud and Small Magellanic Cloud

Abstract

Classical supersoft X-ray sources (SSSs) are understood as close binary systems in which a massive white dwarf (WD) accretes from its companion at rates sustaining steady hydrogen burning on its surface generating bolometric luminosities of $10^{36}-2\times 10^{38}$ erg/s. Here, we perform for the first time the global supersoft X-rays to near-infrared (NIR) spectral energy distribution (SED) for the brightest SSSs in LMC and SMC. We test a model in which the ultraviolet--NIR is dominated by the emission from a compact (unresolved) circumstellar nebula represented by the ionized gas out-flowing from the SSS. The SED models correspond to luminosities of SSSs a few times $10^{38}-10^{39}$ erg/s, radiating at blackbody temperatures of $\approx 3\times 10^5$ K, and indicate nebular continuum, whose emission measure of $\gtrsim 2\times 10^{60}$ cm${}^{-3}$ corresponds to a wind mass-loss at rates $\gtrsim 2\times 10^{-6}$ $M_{\odot }{\mathrm{yr}}^{-1}$. Such extreme parameters suggest that the brightest SSSs could be unidentified optical novae in a post-nova SSS state sustained at a high long-lasting luminosity by resumed accretion, possibly at super-Eddington rates. New observations and theoretical multiwavelength modeling of the global SED of SSSs are needed to reliably determine their parameters, and thus understand their proper stage in stellar evolution.

26 pages, 9 figures, 4 tables, accepted for AJ

References in corpus (22)

• A mass of less than 15 solar masses for the black hole in an ultraluminous X-ray source
• IGR J16194-2810: a new symbiotic X-ray binary
• A transient relativistic radio jet from Cygnus X-1
• Broad H-alpha wings from the optically thin stellar wind of the hot components in symbiotic binaries
• Accretion Rates and Beaming in Ultraluminous X-ray Sources
• Radio and X-ray Properties of Relativistic Beaming Models for Ultra-Luminous X-ray Sources
• X-ray broad-band study of the symbiotic X-ray binary 4U 1954+31
• Transient jets in the symbiotic prototype Z Andromedae
• Early evolution of the extraordinary Nova Del 2013 (V339 Del)
• Multiwavelength observations of nova SMCN 2016-10a --- one of the brightest novae ever observed
• Wind mass transfer in S-type symbiotic binaries I. Focusing by the wind compression model
• Wind mass transfer in S-type symbiotic binaries III. Confirmation of a wind focusing in EG Andromedae from the nebular [OIII]λ5007 line
• Transition to the disk dominant state of a new ultraluminous X-ray source in M82
• Geometry of the Draco C1 Symbiotic Binary
• Multiwavelength modeling the SED of nova V339~Del: Stopping the wind and long-lasting super-Eddington luminosity with dust emission
• Variability in the cycle length of the supersoft source RX J0513.9-6951
• Discovery of a ~30-Year-Duration Post-Nova Pulsating Supersoft Source in the Large Magellanic Cloud
• Symbiotic Stars in the APOGEE Survey: The Case of LIN 358 and SMC N73 (LIN 445a)
• LIN 358: A symbiotic binary accreting above the steady hydrogen fusion limit
• Supersoft X-Ray Nebulae in the Large Magellanic Cloud
• An eLIMA model for the 67 s X-ray periodicity in CAL 83
• New outburst from the luminous supersoft source SSS1 in NGC 300 with periodic modulation

Cited by in corpus (3)

• Application of hydrostatic local thermodynamic equilibrium atmosphere models to interpretations of supersoft X-ray source spectra
• Broad Observational Perspectives Achieved by the Accreting White Dwarf Sciences in the XMM-Newton and Chandra Eras
• V1047 Cen: The first Z And-type outburst observed in the classical nova binary