From BeyondPlanck to Cosmoglobe: Preliminary WMAP Q-band analysis
  We present the first application of the Cosmoglobe analysis framework by
analyzing 9-year WMAP time-ordered observations using similar machinery as
BeyondPlanck utilizes for Planck LFI. We analyze only the Q1-band (41 GHz) data
and report on the low-level analysis process from uncalibrated time-ordered
data to calibrated maps. Most of the existing BeyondPlanck pipeline may be
reused for WMAP analysis with minimal changes to the existing codebase. The
main modification is the implementation of the same preconditioned biconjugate
gradient mapmaker used by the WMAP team. Producing a single WMAP Q1-band sample
requires 44 CPU-hrs, which is less than the cost of a Planck 70 GHz sample of
69 CPU-hrs; this demonstrates that full end-to-end Bayesian processing of the
WMAP data is computationally feasible. Our recovered maps are generally similar
to the maps released by the WMAP team, but more work is needed on sidelobe
modeling before the new pipeline is ready for science grade production. While
comparing the Cosmoglobe and WMAP polarization maps, we identify the same
large-scale pattern in the Q1-band as was previously reported in the V- and
W-band polarization maps by the WMAP team, and we show that this morphology may
be reproduced deterministically in terms of temperature-to-polarization leakage
arising from the coupling between the CMB Solar dipole, transmission imbalance,
and sidelobes. Given that this structure is present in the Q1-, V-, and
W-bands, it could have a nonnegligible impact on cosmological and astrophysical
conclusions drawn from these polarized maps.
