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23 April 2024 |
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Modeling the Radio Foreground for detection of CMB spectral distortions from Cosmic Dawn and Epoch of Reionization | | Mayuri Sathyanarayana Rao
; Ravi Subrahmanyan
; N Udaya Shankar
; Jens Chluba
; | | Date: |
14 Nov 2016 | | Abstract: | Cosmic baryon evolution during Cosmic Dawn and Cosmological Reionization
results in spectral distortions in the cosmic microwave background (CMB) owing
to redshifted 21-cm absorption and emission. These spectral features from
redshifts $30 lesssim z lesssim 6$ appear at meter wavelengths ($lesssim200$
MHz) as a tiny CMB distortion component in addition to the Galactic and
extragalactic radio sky spectrum, which is orders of magnitude brighter. These
spectral distortions encode information about the thermal history of baryons
and the nature and timing of the first collapsed objects. However detecting
them requires methods for precise modeling of foregrounds. Here we present an
improvement over previous efforts to simulate foregrounds. We adopt GMOSS, a
physically motivated sky model that represents sky spectra using radiative
processes to simulate realistic expectation of sky spectra over 40--200 MHz.
From mock observations resulting plausible spectral shapes we demonstrate that
a polynomial of at least order seven is required to model foregrounds alone,
indicating a greater level of spectral complexity in foregrounds than
previously assumed. However, using polynomials to describe foregrounds results
in a significant part of the EoR signal being potentially subsumed. As an
alternative we demonstrate the benefits of adopting Maximally Smooth (MS)
functions to model foregrounds. We find that foregrounds resulting from GMOSS
are describable using MS functions and hence are smooth. Unlike polynomials, MS
functions preserve EoR signal strength and turning points. We demonstrate that
using a frequency-independent antenna and an ideal receiver of noise
temperature 50 K, the global EoR signal can be detected with 90% confidence in
ten minutes integration time, using MS functions to model foregrounds. | | Source: | arXiv, 1611.4602 | | Services: | Forum | Review | PDF | Favorites | |
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