First extragalactic detection of a phosphorus-bearing molecule with ALCHEMI: Phosphorus nitride (PN)
First extragalactic detection of a phosphorus-bearing molecule with ALCHEMI: Phosphorus nitride (PN)
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首次使用 ALCHEMI 在河外探测到含磷分子：氮化磷 (PN)
DOI：
10.1051/0004-6361/202142032
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发表时间：
2022
影响因子：
6.5
通讯作者：
van der Werf P.
中科院分区：
文献类型：
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作者：
Haasler D.;Rivilla V. M.;Martin S.;Holdship J.;Viti S.;Harada N.;Mangum J.;Sakamoto K.;Muller S.;Tanaka K.;Yoshimura Y.;Nakanishi K.;Colzi L.;Hunt L.;Emig K. L.;Aladro R.;Humire P.;Henkel C.;van der Werf P.
磷(P)是生命的关键元素，因为它在几种生物分子中起着核心作用。在银河系的不同区域已经发现了含磷分子，但还没有在河外环境中发现。我们在银河系外寻找邻近的星暴星系ngc253的含p分子。方法利用ALMA综合高分辨率星系外分子清查（ALCHEMI）项目的观测数据，利用MAdrid Data CUBe Analysis软件包对假设局域热力学平衡（LTE）条件下含磷分子的发射进行建模。我们还使用SpectralRadex进行了非lte分析。研究人员首次在河外环境中探测到ngc253的两个巨大分子云（GMCs）中的含磷分子氮化磷（PN）。LTE分析得到总PN束平均柱密度esn =（1.20±0.09）× 1013cm−2和n =（6.5±1.6）× 1012cm−2，其转化为h2ofx χ=（8.0±1.0）× 10−12和χ=（4.4±1.2）× 10−12。我们得到了PN发射最亮的GMC的低激发温度tex =(4.4±1.3)K，这表明PN是次热激发的。非LTE分析结果柱密度与LTE值一致。我们还搜索了其他含磷分子（PO, PH3， CP和CCP），并得出了上限。推导出的PO/PN比值分别< 1.3和< 1.7。NGC 253的PN和激波示踪剂SiO之间的丰度比遵循了先前在银河系源中发现的相同趋势。结论与化学模型的比较表明，ngc253中PN的分子丰度可以用激波驱动化学和宇宙射线驱动光化学来解释。
ContextPhosphorus (P) is a crucial element for life given its central role in several biomolecules. P-bearing molecules have been discovered in different regions of the Milky Way, but not yet towards an extragalactic environment.AimsWe searched for P-bearing molecules outside the Milky Way towards the nearby starburst Galaxy NGC 253.MethodsUsing observations from the ALMA Comprehensive High-resolution Extragalactic Molecular Inventory (ALCHEMI) project, we used the MAdrid Data CUBe Analysis package to model the emission of P-bearing molecules assuming local thermodynamic equilibrium (LTE) conditions. We also performed a non-LTE analysis using SpectralRadex.ResultsWe report the detection of a P-bearing molecule, phosphorus nitride (PN), for the first time in an extragalactic environment, towards two giant molecular clouds (GMCs) of NGC 253. The LTE analysis yields total PN beam-averaged column densitiesN= (1.20 ± 0.09) × 1013cm−2andN= (6.5 ± 1.6) × 1012cm−2, which translate into abundances with respect to H2ofχ= (8.0 ± 1.0) × 10−12andχ= (4.4 ± 1.2) × 10−12. We derived a low excitation temperature ofTex= (4.4 ± 1.3) K towards the GMC with the brightest PN emission, which indicates that PN is sub-thermally excited. The non-LTE analysis results in column densities consistent with the LTE values. We also searched for other P-bearing molecules (PO, PH3, CP, and CCP), and upper limits were derived. The derived PO/PN ratios are < 1.3 and < 1.7. The abundance ratio between PN and the shock-tracer SiO derived towards NGC 253 follows the same trend previously found towards Galactic sources.ConclusionsComparison of the observations with chemical models indicates that the derived molecular abundances of PN in NGC 253 can be explained by shock-driven chemistry followed by cosmic-ray-driven photochemistry.
磷的化学演化：天体生物学的跨学科方法
DOI：
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发表时间：
2019
期刊：
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影响因子：
--
作者：
Enrique Maciá
通讯作者：
Enrique Maciá