The (54Fe+58Ni)/56Ni ratio as a second parameter for Type Ia supernova properties
The (54Fe+58Ni)/56Ni ratio as a second parameter for Type Ia supernova properties
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DOI：
10.1111/j.1745-3933.2006.00165.x
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发表时间：
2006-04
影响因子：
--
通讯作者：
P. Mazzali;P. Podsiadlowski
中科院分区：
文献类型：
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作者：
P. Mazzali;P. Podsiadlowski
(54Fe+58Ni)与56Ni的相对含量的变化可能是观测到的Ia型超新星(SNE Ia)本征亮度与其光曲线形状之间的平均关系散射的原因。合成光曲线由常动能Chandrasekhar质量爆炸模型计算，抛射物被划分为由(54Fe+58Ni)内和外56Ni组成的内核统计平衡(NSE)区、含有中等质量元素的外区和CO区。NSE区的大小和(54Fe+58Ni)相对于56Ni的比例都是系统地变化的。原始NSe含量相同但(54Fe+58Ni)/56Ni比值不同的模型的峰值亮度不同，但具有相似的光曲线形状。合成光谱表明V带衰减率不受(54Fe+58Ni)/56Ni比的影响。虽然56Ni质量和总NSe质量分别是决定峰值光度和光曲线形状的主要参数，但(54Fe+58Ni)/56Ni比值的变化很可能解释了观测到的局域SNE Ia关于平均亮度-衰减率关系的很大一部分散射，这可能取决于前体的金属丰度。
A variation of the relative content of ( 54 Fe+ 58 Ni) versus 56 Ni may be responsible for the observed scatter of Type Ia supernovae (SNe Ia) about a mean relation between their intrinsic brightness and the shape of their light curve. Synthetic light curves are computed from parametrized Chandrasekhar-mass explosion models of constant kinetic energy, where the ejecta are divided into an inner nuclear statistical equilibrium (NSE) zone, composed of ( 54 Fe+ 58 Ni) inside and 56 Ni outside, an outer zone with intermediate-mass elements, and a CO zone. Both the size of the NSE zone and the fraction of ( 54 Fe+ 58 Ni) versus 56 Ni are varied systematically. Models with the same original NSE content but different ( 54 Fe+ 58 Ni)/ 56 Ni ratios reach different peak brightness but have similar light curve shapes. Synthetic spectra indicate that the V-band decline rate is not affected by the ( 54 Fe+ 58 Ni)/ 56 Ni ratio. While the 56 Ni mass and the total NSE mass are the dominant parameters that determine the peak luminosity and the shape of the light curve, respectively, a variation in the ( 54 Fe+ 58 Ni)/ 56 Ni ratio, which may depend on the metallicity of the progenitor is likely to account for a significant part of the observed scatter of local SNe Ia about the mean brightness‐decline rate relation.