Developing a unified pipeline for large-scale structure data analysis with angular power spectra — II. A case study for magnification bias and radio continuum surveys. (arXiv:1909.10539v2 [astro-ph.CO] UPDATED)

<a href="http://arxiv.org/find/astro-ph/1/au:+Tanidis_K/0/1/0/all/0/1">Konstantinos Tanidis</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Camera_S/0/1/0/all/0/1">Stefano Camera</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Parkinson_D/0/1/0/all/0/1">David Parkinson</a>

Following on our purpose of developing a unified pipeline for large-scale

structure data analysis with angular (i.e. harmonic-space) power spectra, we

now include the weak lensing effect of magnification bias on galaxy clustering

in a publicly available, modular parameter estimation code. We thus forecast

constraints on the parameters of the concordance cosmological model, dark

energy, and modified gravity theories from galaxy clustering tomographic

angular power spectra. We find that a correct modelling of magnification is

crucial in order not to bias the estimation of cosmological parameters,

especially in the case of deep galaxy surveys. Our case study adopts

specifications of the Evolutionary Map of the Universe (EMU), which is a

full-sky, deep radio-continuum survey, and is expected to probe the Universe up

to redshift $zsim6$. We assume the Limber approximation, and include

magnification bias on top of density fluctuations and redshift-space

distortions. By restricting our analysis to the regime where the Limber

approximation holds true, we significantly minimise the computational time

needed, compared to that of the exact calculation. We also show that there is a

trend for more biased parameter estimates from neglecting magnification when

the redshift bins are very wide. We conclude that this result implies a strong

dependence on the lensing contribution, which is an integrated effect and

becomes dominant when wide redshift bins are considered. Finally, we note that

instead of being considered a contaminant, magnification bias encodes important

cosmological information, and its inclusion leads to an alleviation of the

degeneracy between the galaxy bias and the amplitude normalisation of the

matter fluctuations.

Following on our purpose of developing a unified pipeline for large-scale

structure data analysis with angular (i.e. harmonic-space) power spectra, we

now include the weak lensing effect of magnification bias on galaxy clustering

in a publicly available, modular parameter estimation code. We thus forecast

constraints on the parameters of the concordance cosmological model, dark

energy, and modified gravity theories from galaxy clustering tomographic

angular power spectra. We find that a correct modelling of magnification is

crucial in order not to bias the estimation of cosmological parameters,

especially in the case of deep galaxy surveys. Our case study adopts

specifications of the Evolutionary Map of the Universe (EMU), which is a

full-sky, deep radio-continuum survey, and is expected to probe the Universe up

to redshift $zsim6$. We assume the Limber approximation, and include

magnification bias on top of density fluctuations and redshift-space

distortions. By restricting our analysis to the regime where the Limber

approximation holds true, we significantly minimise the computational time

needed, compared to that of the exact calculation. We also show that there is a

trend for more biased parameter estimates from neglecting magnification when

the redshift bins are very wide. We conclude that this result implies a strong

dependence on the lensing contribution, which is an integrated effect and

becomes dominant when wide redshift bins are considered. Finally, we note that

instead of being considered a contaminant, magnification bias encodes important

cosmological information, and its inclusion leads to an alleviation of the

degeneracy between the galaxy bias and the amplitude normalisation of the

matter fluctuations.

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