Absorption by Spinning Dust: A Contaminant for High-redshift 21cm Observations
Absorption by Spinning Dust: A Contaminant for High-redshift 21cm Observations
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DOI：
10.3847/2041-8213/aac08a
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发表时间：
2018-05-01
影响因子：
7.9
通讯作者：
Miralda-Escude, Jordi
中科院分区：
文献类型：
--
作者：
Draine, B. T.;Miralda-Escude, Jordi
在明亮的银河系同步加速器背景前旋转的尘埃颗粒会产生微弱的吸收信号，这可能会影响对高红移21厘米吸收的测量。在接近80 MHz的频率下，探测全球EoR特征的实验（EDGES）已经报告了在z接近17处的21 cm吸收，吸收可以由冷星际介质（ISM）中半径接近50埃的星际纳米颗粒产生，旋转温度T接近50 K。大气中的气溶胶可能有助于增加吸收。吸收的强度取决于这些颗粒的丰度和它们的偶极矩，这是不确定的。旋转尘埃的吸收光谱的宽度限制了其对相对窄的21 cm吸收特征的测量的可能影响。
Spinning dust grains in front of the bright Galactic synchrotron background can produce a weak absorption signal that could affect measurements of high-redshift 21 cm absorption. At frequencies near 80 MHz where the Experiment to Detect the Global EoR Signature (EDGES) has reported 21 cm absorption at z approximate to 17, absorption could be produced by interstellar nanoparticles with radii a approximate to 50 angstrom in the cold interstellar medium (ISM), with rotational temperature T approximate to 50 K. Atmospheric aerosols could contribute additional absorption. The strength of the absorption depends on the abundance of such grains and on their dipole moments, which are uncertain. The breadth of the absorption spectrum of spinning dust limits its possible impact on measurement of a relatively narrow 21 cm absorption feature.