The reconstructed CMB lensing bispectrum. (arXiv:2210.16203v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Kalaja_A/0/1/0/all/0/1">Alba Kalaja</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Orlando_G/0/1/0/all/0/1">Giorgio Orlando</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bowkis_A/0/1/0/all/0/1">Aleksandr Bowkis</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Challinor_A/0/1/0/all/0/1">Anthony Challinor</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Meerburg_P/0/1/0/all/0/1">P. Daniel Meerburg</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Namikawa_T/0/1/0/all/0/1">Toshiya Namikawa</a>
Weak gravitational lensing by the intervening large-scale structure (LSS) of
the Universe is the leading non-linear effect on the anisotropies of the cosmic
microwave background (CMB). The integrated line-of-sight mass that causes the
distortion — known as lensing convergence — can be reconstructed from the
lensed temperature and polarization anisotropies via estimators quadratic in
the CMB modes, and its power spectrum has been measured from multiple CMB
experiments. Sourced by the non-linear evolution of structure, the bispectrum
of the lensing convergence provides additional information on late-time
cosmological evolution complementary to the power spectrum. However, when
trying to estimate the summary statistics of the reconstructed lensing
convergence, a number of noise-biases are introduced, as previous studies have
shown for the power spectrum. Here, we explore for the first time the
noise-biases in measuring the bispectrum of the reconstructed lensing
convergence. We compute the leading noise-biases in the flat-sky limit and
compare our analytical results against simulations, finding excellent
agreement. Our results are critical for future attempts to reconstruct the
lensing convergence bispectrum with real CMB data.
Weak gravitational lensing by the intervening large-scale structure (LSS) of
the Universe is the leading non-linear effect on the anisotropies of the cosmic
microwave background (CMB). The integrated line-of-sight mass that causes the
distortion — known as lensing convergence — can be reconstructed from the
lensed temperature and polarization anisotropies via estimators quadratic in
the CMB modes, and its power spectrum has been measured from multiple CMB
experiments. Sourced by the non-linear evolution of structure, the bispectrum
of the lensing convergence provides additional information on late-time
cosmological evolution complementary to the power spectrum. However, when
trying to estimate the summary statistics of the reconstructed lensing
convergence, a number of noise-biases are introduced, as previous studies have
shown for the power spectrum. Here, we explore for the first time the
noise-biases in measuring the bispectrum of the reconstructed lensing
convergence. We compute the leading noise-biases in the flat-sky limit and
compare our analytical results against simulations, finding excellent
agreement. Our results are critical for future attempts to reconstruct the
lensing convergence bispectrum with real CMB data.
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