Anisotropic power spectrum and the observed low-l power in PLANCK CMB data

TL;DR

This paper explores a direction-dependent power spectrum in anisotropic Finsler space-time to explain the low-l power anomaly in PLANCK CMB data, providing a modified model that fits low multipoles but not the entire range.

Contribution

It introduces a novel anisotropic Finsler space-time model to account for observed low-l anomalies in CMB data, extending previous isotropic models.

Findings

Lower amplitude in angular power spectrum for l=2-40

Good fit to data for l=2-10, poor fit for l=2-40

Model modifies primordial power spectrum to break rotational invariance

Abstract

In this work, we study a direction dependent power spectrum in anisotropic Finsler space-time. We use this direction dependent power spectrum to address the low-l power observed in WMAP and PLANCK data. The angular power spectrum of the temperature fluctuations has a lower amplitude in comparison to the $\Lambda$CDM model in the multipole range l = 2-40. Our theoretical model gives a correction to the isotropic angular power spectrum $C^{TT}_l$ due to the breaking of the rotational invariance of the primordial power spectrum. We estimate best-fit model parameters along with the six $\Lambda$CDM cosmological parameters using PLANCK likelihood code in CosmoMC software. We see that this modified angular power spectrum fits the CMB temperature data in the multipole range l=2-10 to a good extent but fails for the whole multipole range l = 2-40.