论文标题
CH $ _3 $ COCH $ _3 $ ICE的X射线光解：紧凑物体对天体物理冰的辐射影响的影响
X-ray photolysis of CH$_3$COCH$_3$ ice: Implications for the radiation effects of compact objects towards astrophysical ices
论文作者
论文摘要
在这项研究中，我们采用了宽带X射线（$ 6-2000 $ eV）来照射冷冻丙酮CH $ _3 $ _3 $ COCH $ _3 $，在12 K的温度下，不同的光子通量为$ 2.7 \ times 10^{18} $ photos cm $ $^{ - 2} $。在这里，我们认为丙酮是星际冰晶粒上存在的代表性复合有机分子（COM）。使用红外光谱法（FTIR）在巴西同步加速器设施（LNLS/CNPEN）处诱导实验，以监测冰样中辐射引起的化学变化。我们确定了丙酮分子的有效破坏横截面和儿子物种的有效形成横截面。化学平衡，用于VULUNES $ 2 \ times 10^{18} $光子CM $^{ - 2} $的化学平衡，并确定了在此阶段的分子丰度，其中还包括在冰中产生但未检测到的一大堆未知分子的估计值。在假设的雪线距离处，冰的时间尺度在几个紧凑型和主要序列X射线源附近达到化学平衡。 We estimate timescales of 18 days, 3.6 and 1.8 months, $1.4\times 10^9-6\times 10^{11}$ years, 600 and $1.2\times 10^7$ years, and $10^7$ years, for the Sun at 5 AU, for O/B stars at 5 AU, for white dwarfs at 1 LY, for the Crab pulsar at 2.25 LY, for Vela pulsar at 2.25 ly，分别为3 ly的射手座a*。这项研究提高了我们目前对辐射对冷冻材料化学的影响的理解，特别是首次集中于紧凑型物体在其最终周围的冰中产生的X射线影响。
In this study, we employed broadband X-rays ($6-2000$ eV) to irradiate the frozen acetone CH$_3$COCH$_3$, at the temperature of 12 K, with different photon fluences up to $2.7\times 10^{18}$ photons cm$^{-2}$. Here, we consider acetone as a representative complex organic molecule (COM) present on interstellar ice grains. The experiments were conduced at the Brazilian synchrotron facility (LNLS/CNPEN) employing infrared spectroscopy (FTIR) to monitor chemical changes induced by radiation in the ice sample. We determined the effective destruction cross-section of the acetone molecule and the effective formation cross-section for daughter species. Chemical equilibrium, obtained for fluence $2\times 10^{18}$ photons cm$^{-2}$, and molecular abundances at this stage were determined, which also includes the estimates for the abundance of unknown molecules, produced but not detected, in the ice. Timescales for ices, at hypothetical snow line distances, to reach chemical equilibrium around several compact and main-sequence X-ray sources are given. We estimate timescales of 18 days, 3.6 and 1.8 months, $1.4\times 10^9-6\times 10^{11}$ years, 600 and $1.2\times 10^7$ years, and $10^7$ years, for the Sun at 5 AU, for O/B stars at 5 AU, for white dwarfs at 1 LY, for the Crab pulsar at 2.25 LY, for Vela pulsar at 2.25 LY, and for Sagittarius A* at 3 LY, respectively. This study improves our current understanding about radiation effects on the chemistry of frozen material, in particular, focusing for the first time, the effects of X-rays produced by compact objects in their eventual surrounding ices.
