[Paper Review] Heliosheath Synchrotron Radiation As A Possible Source For The Arcade 2 CMB Distortions

H. N. Sharpe|ArXiv.org|Feb 2, 2009

Solar and Space Plasma Dynamics7 references3 citations

TL;DR

This paper proposes that synchrotron radiation from relativistic electrons in the Sun's heliosheath could explain the anomalous microwave emission detected by the ARCADE 2 experiment. Using a power-law spectrum with a spectral index of +2, the model shows that an optically thin shell of plasma ~1 AU thick can produce the observed 1 K brightness temperature distortion, suggesting heliospheric magnetic fields and double layers as energy sources for the electrons.

ABSTRACT

This brief note speculates that the recently reported residual CMB signal [Seiffert et al 2009] may originate within the Sun's heliosheath. A temperature spectrum function is derived that has the same power law form as the fitted function in Seiffert et al. In particular a spectral index of +2 is implied. An optically thin radiating shell of thickness ~1AU could match the required 1K deg power law amplitude. A possible mechanism for the heliosheath magnetic fields is discussed based on Alfven's heliospheric current model with embedded double layers as the energy source for the relativistic electrons.

Motivation & Objective

• To investigate the origin of the anomalous microwave signal detected by ARCADE 2, which exceeds predictions from known astrophysical sources.
• To explore whether the heliosheath region of the solar system could host a source of microwave emission matching the observed spectral shape.
• To model the synchrotron radiation from relativistic electrons in the heliosheath and assess its consistency with the ARCADE 2 data.
• To examine the feasibility of heliospheric magnetic fields and double layers as energy sources for relativistic electrons.
• To derive a temperature spectrum function matching the power-law fit reported in Seiffert et al. (2009).

Proposed method

• Derives a temperature spectrum function for synchrotron radiation in the heliosheath with a power-law form matching the ARCADE 2 data.
• Assumes an optically thin radiating shell of thickness ~1 AU to model the emission region.
• Uses a spectral index of +2 to match the observed amplitude of 1 K brightness temperature distortion.
• Applies Alfven's heliospheric current sheet model to explain the magnetic field structure in the heliosheath.
• Proposes embedded double layers as a mechanism for energizing relativistic electrons.
• Compares the derived spectrum to the fitted function from Seiffert et al. (2009) to validate consistency.

Experimental results

Research questions

• RQ1 Can heliosheath synchrotron radiation account for the excess microwave emission observed by ARCADE 2?
• RQ2 What spectral index and emission geometry are required to match the 1 K brightness temperature distortion?
• RQ3 Is there a plausible mechanism for generating relativistic electrons in the heliosheath capable of producing detectable synchrotron emission?
• RQ4 Can the heliospheric current sheet model with embedded double layers explain the magnetic field configuration needed for electron acceleration?
• RQ5 Does the derived spectrum from heliosheath emission match the power-law form observed in ARCADE 2 data?

Key findings

• The derived temperature spectrum function for heliosheath synchrotron radiation matches the power-law form observed in ARCADE 2 data.
• A spectral index of +2 is implied by the model, consistent with the observed microwave spectrum.
• An optically thin radiating shell of thickness approximately 1 AU can produce the required 1 K brightness temperature amplitude.
• The model suggests that heliosheath magnetic fields, possibly generated via Alfven's current sheet model, could support the observed emission.
• Embedded double layers in the heliosheath may provide the energy source for relativistic electrons responsible for the synchrotron radiation.
• The proposed mechanism offers a plausible astrophysical explanation for the ARCADE 2 anomaly without invoking exotic physics.