Abstract Details
| Name: VIPIN SUDEVAN Affiliation: IISER BHOPAL Conference ID: ASI2018_1765 Title : A MEASUREMENT OF CMB ANGULAR POWER SPECTRUM FROM PLANCK & WMAP OBSERVATIONS Authors and Co-Authors : Pavan K. Aluri, Sarvesh Kumar Yadav, Rajib Saha, Tarun Souradeep Abstract Type : Contributed Talk Abstract Category : General Relativity and Cosmology Abstract : The cosmic microwave background (CMB) is one of the important tool available for cosmologists to probe into and understand the physics of the early Universe. The CMB data collected by various balloon and satellite missions are severely contaminated due to the foreground emissions from various astrophysical processes present within and outside our galaxy. These foreground contaminations should be removed properly without disturbing the underlying CMB signal. There exists various techniques in the Literature for the component separation and thereby to estimate the angular power spectrum of the foreground removed CMB signal. One of the author Saha et.al (2008) has obtained Temperature Power Spectra using the Linear Combination Method, which is insensitive to the modelling of the foreground in order to precisely determine the cosmological CMB signal. In the present work, we have made various improvements on this work and the foreground removal of the PLANCK and WMAPS is achieved through a multiphase iterative harmonic space inetrnal-linear-combination (HILC) approach. The new procedure consists of two phases. In phase 1 of foreground removal, a diffuse foreground cleaned map is obtained by performing a usual ILC operation in the harmonic space in a single iteration over the entire portion of the sky. In phase 2, we obtain the final foreground cleaned map using an iterative ILC approach also in the harmonic space, however, now, during each iteration of foreground minimization, some of the regions of the sky that are not being cleaned in the current iteration, are replaced by the corresponding cleaned portions of the phase 1 cleaned map. This method nullifies the leakage which is present in the old and usual iterative HILC method. We have obtained the TT angular power spectrum for the multipole range 2<=l<=2500 from the foreground cleaned CMB map which matches with the power spectrum obtained by Planck Team. We have also validated our method with the aid of Monte Carlo simulations. In this talk, I will discuss about several improvements that we have made over the usual HILC method, which aids in obtaining better cleaned maps. Reference: Sudevan, V., Aluri, P. K., Yadav, S. K., Saha, R., & Souradeep, T. 2017, Astrophys. J., 842, 62 |