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Identifier

000433409

Title

Study of the impact of the interstellar cloud shapes on CMB polarization foregrounds

Alternative Title

Μελέτη της επιρροής του σχήματος των διαστρικών νεφών στις παρεμβολές της πόλωσης της κοσμικής ακτινοβολίας υποβάθρου

Author

Κωνσταντίνου, Άννα Κ.

Thesis advisor

Τάσσης, Κωνσταντίνος
Pelgrims, Vincent

Reviewer

Χαρμανδάρης, Βασίλης
Diaz-Santos, Tanio

Abstract

In the quest for the primordial B-mode in the polarization of cosmic microwave background (CMB) radiation, the understanding and characterization of Galactic foregrounds has become of utmost importance. On this subject, we have noticed that the dust clouds of the magnetized interstellar medium are generally considered as filamentary structures by the CMB community whereas it has been established for some time that they are most likely sheet structures by the radio astrophysics community. In this project, we investigate whether the morphology of the dust clouds has an impact on the statistical characterization of the polarized emission. To that end, we simulate interstellar clouds with both filamentary and sheet-like structure, using the software "Asterion" which is dedicated to this work and we generate synthetic polarization maps. We then explore some characteristics of the power spectra, such as the E/B power asymmetry, quantified through the EE/BB ratio and the correlation coefficient between intensity and E mode power r^{T E}, and lead a statistical analysis. Our results about filaments are consistent with theoretical expectation (e.g. Zaldarriaga 2001). For the first time we carry a statistical analysis for sheet-like interstellar clouds. The behaviour of sheets present similarities and differences as compared to filaments. Finally, we found that there is degeneracy between sheets and filaments in quantities extracted from their power spectra as well as with their apparent shape, at the map level. In a sense, we have set the stage for future and more detailed investigations that will be needed to fully characterize the latter.

Language

English

Subject

B Mode

Filaments

Interstellar dust clouds

Polarization maps

Power spectra

Sheets

Διαστρικά νέφη

Δομές υμενίων

Νηματώδεις δομές