Abstract Details
| Name: N. Udaya Shankar Affiliation: RRI, Bangalore Conference ID: ASI2016_1012 Title : Modeling the Radio Foreground for detection of spectral distortions from the Epoch of Reionization Authors and Co-Authors : Mayuri Sathyanarayana Rao (Raman Research Institute, Bangalore & Australian National University, Canberra) Ravi Subrahmanyan (Raman Research Institute, Bangalore), N Udaya Shankar (Raman Research Institute, Bangalore), Jens Chluba (Kavli Institute for Cosmology, Cambridge) Abstract Type : Poster Abstract Category : General Relativity and Cosmology Abstract : Cosmological Reionization results in additive spectral features in the cosmic microwave background (CMB) at low frequencies. A detection of these spectral features arising from the Epoch Of Reionization or EoR ($30\lesssim z \lesssim 6$) would provide clues to the thermal history of the baryons and the nature and timing of the first collapsed objects. There are global, all-sky isotropic spectral features as well as angular variations in spectral structure, embedded as tiny additive components in the radio background. Galactic and Extragalactic radio emission is the dominant foreground in the radio band; together with the CMB these are orders of magnitude brighter than the EoR signatures. Therefore, detection requires methods for precise modeling of foregrounds. Since telescope beams average over foreground sources along line of sight and over beam area, and foreground radio sources have a spread in their emission spectral indices, the functional form for the foreground detected by telescope beams is a priori unknown. Conventional methods adopt polynomial forms of higher orders for modeling foregrounds with greater accuracy, inevitably confusing the foreground with the embedded weak EoR signatures. Here we investigate the radio foreground for the global EoR signal and present a physically motivated sky-model. Using this sky-model we generate synthetic sky-spectra as observed by an ideal instrument and investigates methods to detect the global EoR signal, distinguishing it from the bright foreground, without compromising signal integrity. We also provide results of statistical tests on the simulated sky-spectra to determine the confidence in detection of the global EoR signal with various methods of foreground subtraction. |