Hard X‐Rays and Gamma Rays from Type Ia Supernovae

The mixing of the photon with a hypothetical sterile paraphotonic state would have consequences on the cosmological propagation of photons. The absence of distortions in the optical spectrum of distant Type Ia supernovae allows to extend by two orders of magnitude the previous limit on the Lorentz-violating parameter δ associated to the photon–paraphoton transition, extracted from the absence of distortions in the spectrum of the cosmic microwave background. The new limit is consistent with the interpretation of the dimming of distant Type Ia supernovae as a consequence of a nonzero cosmological constant. Observations of gamma-rays from active galactic nuclei allow to further extend the limit on δ.

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Evolution of 3–9M⊙Stars for \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $Z=0.001- 0.03$ \end{document} and Metallicity Effects on Type Ia Supernovae

The Astrophysical Journal ◽

10.1086/306887 ◽

1999 ◽

Vol 513 (2) ◽

pp. 861-868 ◽

Cited By ~ 121

Author(s):

Hideyuki Umeda ◽

Ken'ichi Nomoto ◽

Hitoshi Yamaoka ◽

Shinya Wanajo

Keyword(s):

Type Ia Supernovae ◽

Type Ia ◽

Ia Supernovae

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Gravitational Collapse versus Thermonuclear Explosion of Degenerate Stellar Cores

International Astronomical Union Colloquium ◽

10.1017/s0252921100026373 ◽

1994 ◽

Vol 147 ◽

pp. 186-213

Author(s):

J. Isern ◽

R. Canal

Keyword(s):

Neutron Star ◽

White Dwarfs ◽

Light Curves ◽

Type Ia Supernovae ◽

Radioactive Elements ◽

Border Line ◽

Thermonuclear Explosion ◽

Type Ia ◽

Γ Rays ◽

Ia Supernovae

AbstractIn this paper we review the behavior of growing stellar degenerate cores. It is shown that ONeMg white dwarfs and cold CO white dwarfs can collapse to form a neutron star. This collapse is completely silent since the total amount of radioactive elements that are expelled is very small and a burst of γ-rays is never produced. In the case of an explosion (always carbonoxygen cores), the outcome fits quite well the observed properties of Type Ia supernovae. Nevertheless, the light curves and the velocities measured at maximum are very homogeneous and the diversity introduced by igniting at different densities is not enough to account for the most extreme cases observed. It is also shown that a promising way out of this problem could be the He-induced detonation of white dwarfs with different masses. Finally, we outline that the location of the border line which separetes explosion from collapse strongly depends on the input physics adopted.

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