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تسجيل مستخدم جديدMulti-Dimensional Radiative Transfer Calculations of Double Detonations of Sub-Chandrasekhar-Mass White Dwarfs
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Study of the double detonation Type Ia supernova scenario, in which a helium shell detonation triggers a carbon core detonation in a sub-Chandrasekhar-mass white dwarf, has experienced a resurgence in the past decade. New evolutionary scenarios and a better understanding of which nuclear reactions are essential have allowed for successful explosions in white dwarfs with much thinner helium shells than in the original, decades-old incarnation of the double detonation scenario. In this paper, we present the first suite of light curves and spectra from multi-dimensional radiative transfer calculations of thin-shell double detonation models, exploring a range of white dwarf and helium shell masses. We find broad agreement with the observed light curves and spectra of non-peculiar Type Ia supernovae, from subluminous to overluminous subtypes, providing evidence that double detonations of sub-Chandrasekhar-mass white dwarfs produce the bulk of observed Type Ia supernovae. Some discrepancies in spectral velocities and colors persist, but these may be brought into agreement by future calculations that include more accurate initial conditions and radiation transport physics.
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Type Ia supernovae (SNe Ia) span a range of luminosities and timescales, from rapidly evolving subluminous to slowly evolving overluminous subtypes. Previous theoretical work has, for the most part, been unable to match the entire breadth of observed
SNe Ia with one progenitor scenario. Here, for the first time, we apply non-local thermodynamic equilibrium radiative transfer calculations to a range of accurate explosion models of sub-Chandrasekhar-mass white dwarf detonations. The resulting photometry and spectra are in excellent agreement with the range of observed non-peculiar SNe Ia through 15 d after the time of B-band maximum, yielding one of the first examples of a quantitative match to the entire Phillips (1993) relation. The intermediate-mass element velocities inferred from theoretical spectra at maximum light for the more massive white dwarf explosions are higher than those of bright observed SNe Ia, but these and other discrepancies likely stem from the one-dimensional nature of our explosion models and will be improved upon by future non-local thermodynamic equilibrium radiation transport calculations of multi-dimensional sub-Chandrasekhar-mass white dwarf detonations.
Sub-Chandrasekhar mass carbon-oxygen white dwarfs (CO WDs) with a surface helium (He) shell have been proposed as progenitors of Type Ia supernovae (SNe Ia). If true, the resulting thermonuclear explosions should be able to account for at least some
of the range of SNe Ia observables. To study this, we conduct a parameter study based on 3D simulations of double detonations in CO WDs with a He shell, assuming different core and shell masses. An admixture of C to the shell and solar metallicity are included in the models. The hydrodynamic simulations are carried out using the AREPO code. This allows us to follow the He shell detonation with high numerical resolution, and improves the reliability of predicted nucleosynthetic shell detonation yields. The addition of C to the shell leads to a lower production of 56Ni while including solar metallicity increases the production of IMEs. The production of higher mass elements is further shifted to stable isotopes at solar metallicity. Moreover, we find different core detonation ignition mechanisms depending on the core and shell mass configuration. This has an influence on the ejecta structure. We present the bolometric light curves predicted from our explosion simulations using the radiative transfer code ARTIS, and make comparisons with SNe Ia data. The bolometric light curves of our models show a range of brightnesses, able to account for sub-luminous to normal SNe Ia. We show the model bolometric width-luminosity relation compared to data for a range of viewing angles. We find that, on average, our brighter models lie within the observed data. The ejecta asymmetries produce a wide distribution of observables, which might account for outliers in the data. However, the models overestimate the extent of this compared to data. We also find the bolometric decline rate over 40 days appears systematically faster than data. (abridged)
Since 2012, we have initiated a new idea showing that the mass of highly magnetized or modified Einsteins gravity induced white dwarfs could be significantly super-Chandrasekhar with a different mass-limit. This discovery has several important conseq
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