Testing synchrotron models and frequency resolution in BINGO 21 cm
  simulated maps using GNILC
  To recover the 21 cm hydrogen line, it is essential to separate the
cosmological signal from the much stronger foreground contributions at radio
frequencies. The BINGO radio telescope is designed to measure the 21 cm line
and detect BAOs using the intensity mapping technique. This work analyses the
performance of the GNILC method, combined with a power spectrum debiasing
procedure. The method was applied to a simulated BINGO mission, building upon
previous work from the collaboration. It compares two different synchrotron
emission models and different instrumental configurations, in addition to the
combination with ancillary data to optimize both the foreground removal and
recovery of the 21 cm signal across the full BINGO frequency band, as well as
to determine an optimal number of frequency bands for the signal recovery. We
have produced foreground emissions maps using the Planck Sky Model, the
cosmological Hi emission maps are generated using the FLASK package and thermal
noise maps are created according to the instrumental setup. We apply the GNILC
method to the simulated sky maps to separate the Hi plus thermal noise
contribution and, through a debiasing procedure, recover an estimate of the
noiseless 21 cm power spectrum. We found a near optimal reconstruction of the
Hi signal using a 80 bins configuration, which resulted in a power spectrum
reconstruction average error over all frequencies of 3%. Furthermore, our tests
showed that GNILC is robust against different synchrotron emission models.
Finally, adding an extra channel with CBASS foregrounds information, we reduced
the estimation error of the 21 cm signal. The optimisation of our previous
work, producing a configuration with an optimal number of channels for binning
the data, impacts greatly the decisions regarding BINGO hardware configuration
before commissioning.
