Interstellar Scintillations of Polarization of Compact Sources

Area of Science:

• Astrophysics
• Radio Astronomy
• Interstellar Medium Physics

Background:

• Compact radio sources exhibit complex radiation fields.
• Interstellar scintillations (ISS) affect radio waves propagating through the Galactic medium.
• Polarization of radio sources contains information about the source and propagation effects.

Purpose of the Study:

• To demonstrate that measuring polarization fluctuations from ISS can probe the radiation field structure of compact radio sources.
• To develop a mathematical framework for analyzing these polarization variations.

Main Methods:

• Developing a mathematical formalism to model polarization fluctuations.
• Applying the formalism to an analytical model of a compact radio source.
• Analyzing the amplitude of modulation in polarized radiation flux.

Main Results:

• A predicted modulation amplitude of approximately 20% of the intrinsic source polarization (p_is) multiplied by the modulation index (m_sc).
• The modulation index (m_sc) is shown to be approximately 1 for diffractive scintillations and less than 1 for refractive scintillations.
• The scale of polarization variation across the source is comparable to the source size in the analytical model.

Conclusions:

• Fluctuations in radio source polarization due to Galactic interstellar scintillations offer a viable method for studying source radiation field structure.
• The developed mathematical formalism provides a tool for interpreting these polarization variations.
• This technique can enhance our understanding of compact radio source properties and the intervening interstellar medium.