由于尘埃颗粒的旋转破坏引起的 Ia 型超新星的时变消光、极化和颜色,The Astrophysical Journal

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由于尘埃颗粒的旋转破坏引起的 Ia 型超新星的时变消光、极化和颜色
The Astrophysical Journal ( IF 4.8 ) Pub Date : 2020-01-13 , DOI: 10.3847/1538-4357/ab5d37
Nguyen Chau Giang ₁ , Thiem Hoang _{2,

3} , Le Ngoc Tram _{1,

4}

Affiliation

对 Ia 型超新星 (SNe Ia) 的光度和偏振观测经常报告异常低的总选择性消光比 ($R_{\rm V} < 2$) 和小的偏振峰值波长 ($\lambda_{\rm max }< 0.4 \mu m$）。最近，Hoang 等人。提出，由于辐射扭矩中断（RATD），小晶粒相对于大晶粒在 SNe Ia 附近的丰度增加可以解释这个难题。为了测试这种情况，我们将对 SNe Ia 的尘埃消光和极化进行详细建模，以解释 RATD 引起的颗粒破坏和 RAdiative Torques (RAT) 引起的颗粒排列。对于距离源 $d< 4$ pc 处的尘埃云，我们发现 $R_{\rm V}$ 在中断时间 $t_{\rm 后从标准值 $3.1$ 迅速下降到 $\sim 1.5$ disr}\le 40$ 天。然后我们计算了观测到的 SNe Ia 光变曲线，发现 SNe Ia 的颜色会随着时间的推移而变化，这是由于 $d<4$pc 距离处的尘埃云随时间变化消光。我们还计算了由 RAT 与磁场对齐的晶粒产生的波长相关极化。我们发现 $\lambda_{\rm max}$ 在 $t_{\rm align}< 10$ 天的对齐时间内从 $\sim 0.55 \mu$m 迅速下降到 $\sim 0.15 \mu$m小晶粒的增强排列。通过用 Serkowski 定律拟合理论极化曲线，我们发现当大晶粒被 RATD 破坏时，来自 Serkowski 定律的参数 $K$ 增加，这可以解释 $K$ vs. $\lambda_{\rm max}$ 数据观察到 SNe Ia。最后，我们发现 $K$ 和 $R_{\rm V}$ 之间的反相关性，这可能已经得到 SNe Ia 观测数据的支持。我们的结果证明了辐射扭矩对尘埃颗粒的旋转破坏对 SNe Ia 的时间相关消光、极化和颜色的重要影响。

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Time-varying Extinction, Polarization, and Colors of Type Ia Supernovae due to Rotational Disruption of Dust Grains

Photometric and polarimetric observations toward type Ia supernovae (SNe Ia) frequently report an unusually low total-to-selective extinction ratio ($R_{\rm V} < 2$) and small peak wavelength of polarization ($\lambda_{\rm max}< 0.4 \mu m$). Recently, Hoang et al. proposed that the increase in the abundance of small grains relative to large grains near SNe Ia due to RAdiative Torque Disruption (RATD) can explain this puzzle. To test this scenario, we will perform detailed modeling of dust extinction and polarization of SNe Ia accounting for grain disruption by RATD and grain alignment by RAdiative Torques (RATs). For dust clouds at distance $d< 4$ pc from the source, we find that $R_{\rm V}$ decreases rapidly from the standard value of $3.1$ to $\sim 1.5$ after a disruption time $t_{\rm disr}\le 40$ days. We then calculate the observed SNe Ia light curve and find that the colors of SNe Ia would change with time due to time-varying extinction for dust clouds at distance of $d<4$ pc. We also calculate the wavelength-dependence polarization produced by grains aligned with the magnetic fields by RATs. We find that $ \lambda_{\rm max}$ decreases rapidly from $\sim 0.55 \mu$m to $\sim 0.15 \mu$m over an alignment time of $t_{\rm align}< 10$ days due to the enhanced alignment of small grains. By fitting the theoretical polarization curve with the Serkowski law, we find that the parameter $K$ from the Serkowski law increases when large grains are disrupted by RATD which can explain the $K$ vs. $\lambda_{\rm max}$ data observed for SNe Ia. Finally, we discover an anti-correlation between $K$ and $R_{\rm V}$ which might already be supported by SNe Ia observational data. Our results demonstrate the important effect of rotational disruption of dust grains by radiative torques on the time-dependent extinction, polarization, and colors of SNe Ia.

更新日期：2020-01-13

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