Investigation of the Origin of the Anomalous Microwave Emission in Lambda Orionis

Abstract

The anomalous microwave emission (AME) still lacks a conclusive explanation. This excess of emission, roughly between 10 and 50 GHz, tends to defy attempts to explain it as synchrotron or free-free emission. The overlap with frequencies important for cosmic microwave background explorations, combined with a strong correlation with interstellar dust, drive cross-disciplinary collaboration between interstellar medium and observational cosmology. The apparent relationship with dust has prompted a ``spinning dust'' hypothesis. The typical peak frequency range of the AME profile implicates spinning grains on the order of 1 nm. This points to polycyclic aromatic hydrocarbons (PAHs). We use data from the AKARI/Infrared Camera (IRC), due to its thorough PAH-band coverage, to compare AME from the Planck Collaboration astrophysical component separation product with infrared dust emission in the Orionis AME-prominent region. We look also at infrared dust emission from other mid IR and far-IR bands. The results and discussion contained here apply to an angular scale of approximately 1°. We find that certainly dust mass correlates with AME, and that PAH-related emission in the AKARI/IRC 9 μm band correlates slightly more strongly. Using hierarchical Bayesian inference and full dust spectral energy distribution (SED) modeling we argue that AME in λOrionis correlates more strongly with PAH mass than with total dust mass, lending support for a spinning PAH hypothesis within this region. We emphasize that future efforts to understand AME should focus on individual regions, and a detailed comparison of the PAH features with the variation of the AME SED.

31 pages, 22 figures. Accepted by PASJ

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• A refined model for spinning dust radiation
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Cited by in corpus (13)

• The Astrodust+PAH Model: A Unified Description of the Extinction, Emission, and Polarization from Dust in the Diffuse Interstellar Medium
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• Polycyclic Aromatic Hydrocarbons, the Anomalous Microwave Emission, and Their Connection to the Cold Neutral Medium
• Spinning nano-carbon grains: Viable origin for anomalous microwave emission
• QUIJOTE scientific results -- X. Spatial variations of Anomalous Microwave Emission along the Galactic plane
• BeyondPlanck XVI. Limits on Large-Scale Polarized Anomalous Microwave Emission from Planck LFI and WMAP
• QUIJOTE Scientific Results -- VII. Galactic AME sources in the QUIJOTE-MFI Northern Hemisphere Wide-Survey
• Searching for Anomalous Microwave Emission in nearby galaxies. K-band observations with the Sardinia Radio Telescope
• Tracing PAH Emission in $\lambda$-Orionis Using COBE/DIRBE Data
• Spinning Nanoparticles Impacted by C-shock: Implications for Radio-millimeter Emission from Star-forming Regions
• The mm-to-cm SED of spiral galaxies. Synergies between NIKA2 and SRT instruments
• Far-infrared to centimeter emission of very nearby galaxies with archival data
• Modeling Long-Wavelength Amorphous Dust Emission Based on the Physically Motivated Soft-Potential Model