Suppressing CMB low multipoles with ISW effect
  Recent results of Planck data reveal that the power in the low multipoles of
the CMB angular power spectrum, approximately up to $l=30$, is significantly
lower than the theoretically predicted in the best fit $\Lambda$CDM model. In
this paper we investigate the possibility of invoking the Integrated
Sachs-Wolfe (ISW) effect to explain this power deficit at low multipoles. The
ISW effect that originates from the late time expansion history of the universe
is rich in possibilities given the limited understanding of the origin of dark
energy (DE). It is a common understanding that the ISW effect adds to the power
at the low multipoles of the CMB angular power spectrum. In this paper we carry
out an analytic study to show that there are some expansion histories in which
the ISW effect, instead of adding power, provides negative contribution to the
power at low multipoles. Guided by the analytic study, we present examples of
the features required in the late time expansion history of the universe that
could explain the power deficiency through the ISW effect. We also show that an
ISW origin of power deficiency is consistent, at present, with other
cosmological observations that probe the expansion history such as distance
modulus, matter power spectrum and the evolution of cluster number count. We
also show that the ISW effect may be distinguished from power deficit
originating from features in the PPS using the measurements of the CMB
polarization spectrum at low multipoles expected from Planck. We conclude that
the power at low multipoles of the CMB anisotropy could well be closely linked
to Dark Energy puzzle in cosmology and this observation could be actually
pointing to richer phenomenology of DE beyond the cosmological constant
$\Lambda$. (abbreviated)
