2018/04/30 by B. T. Draine, Jordi Miralda-Escudé · 1 citation
Physics and Astronomy · #Absorption (acoustics) #Absorption spectroscopy #Analytical Chemistry (journal) #Astro and Planetary Science #Astrophysics and Star Formation Studies #Interstellar medium #Spinning #Superconducting and THz Device Technology #Synchrotron #astro-ph.GA
paper · pdf · doi:10.3847/2041-8213/aac08a
published as Astrophysical Journal Letters, 858:L10 (2018) · version published in ApJL
openalex created_date 2018/04/13 · arxiv created 2018/05/07 · openalex publication_date 2018/05/07 · arxiv updated 2018/05/08 · openalex updated_date 2026/08/05
Abstract 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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>z</mml:mi> <mml:mo>≈</mml:mo> <mml:mn>17</mml:mn> </mml:math> , absorption could be produced by interstellar nanoparticles with radii <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>a</mml:mi> <mml:mo>≈</mml:mo> <mml:mn>50</mml:mn> <mml:mspace width="0.25em"/> <mml:mi>Å</mml:mi> </mml:math> in the cold interstellar medium (ISM), with rotational temperature T ≈ 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.