论文标题
了解$ρ$ ophiuchi a的两极分化灰尘排放，从谷物对齐和辐射扭矩中断
Understanding polarized dust emission from $ρ$ Ophiuchi A in light of grain alignment and disruption by radiative torques
论文作者
论文摘要
灰尘晶粒与环境磁场的比对产生星光的极化以及热灰尘发射。 Using the archival SOFIA/HAWC+ polarimetric data observed toward $ρ$ Ophiuchus (Oph) A cloud hosted by a B association star at 89 $μ$m and 154 $μ$m, we find that the fractional polarization of thermal dust emission first increases with the grain temperature and then decreases once the grain temperature exceeds $\simeq$ 25-32 K. The latter trend differs from the prediction of the popular辐射扭矩（大鼠）对准理论，暗示着晶粒温度的极化部分的单调增加。我们对$ρ$ OPH-A云的极化灰尘发射进行数值建模，并通过同时考虑大鼠的灰尘粒度对准和旋转破坏来计算灰尘极化程度。我们的建模结果可以成功地再现观测数据的上升和下降趋势。此外，我们表明仅硅酸盐晶粒或复合结构内的硅酸盐 - 碳晶粒的混合物可以重现观察趋势，假设所有粉尘晶粒都遵循幂律尺寸分布。尽管我们的建模有许多简化和局限性，但我们的结果表明，$ρ$ OPH-A云中的谷物具有复合结构，并且晶粒尺寸的分布比星际介质的标准尺寸分布更陡峭。索非亚/HAWC+数据与JCMT观测值的组合450 $ $ m $ m和850 $ $ m $ m对于基于谷物对齐和大鼠的破坏来测试所提出的方案。
The alignment of dust grains with the ambient magnetic field produces polarization of starlight as well as thermal dust emission. Using the archival SOFIA/HAWC+ polarimetric data observed toward $ρ$ Ophiuchus (Oph) A cloud hosted by a B association star at 89 $μ$m and 154 $μ$m, we find that the fractional polarization of thermal dust emission first increases with the grain temperature and then decreases once the grain temperature exceeds $\simeq$ 25-32 K. The latter trend differs from the prediction of the popular RAdiative Torques (RATs) alignment theory which implies a monotonic increase of the polarization fraction with the grain temperature. We perform numerical modeling of polarized dust emission for the $ρ$ Oph-A cloud and calculate the degree of dust polarization by simultaneously considering the dust grain alignment and rotational disruption by RATs. Our modeling results could successfully reproduce both the rising and declining trends of the observational data. Moreover, we show that the alignment of only silicate grains or a mixture of silicate-carbon grains within a composite structure can reproduce the observational trends, assuming that all dust grains follow a power-law size distribution. Although there are a number of simplifications and limitations to our modeling, our results suggest grains in $ρ$ Oph-A cloud have a composite structure, and the grain size distribution has steeper slope than the standard size distribution for the interstellar medium. Combination of SOFIA/HAWC+ data with JCMT observations 450 $μ$m and 850 $μ$m would be useful to test the proposed scenario based on grain alignment and disruption by RATs.
