Power spectrum of halo intrinsic alignments in simulations. (arXiv:2004.12579v2 [astro-ph.CO] UPDATED)

<a href="http://arxiv.org/find/astro-ph/1/au:+Kurita_T/0/1/0/all/0/1">Toshiki Kurita</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Takada_M/0/1/0/all/0/1">Masahiro Takada</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nishimichi_T/0/1/0/all/0/1">Takahiro Nishimichi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Takahashi_R/0/1/0/all/0/1">Ryuichi Takahashi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Osato_K/0/1/0/all/0/1">Ken Osato</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kobayashi_Y/0/1/0/all/0/1">Yosuke Kobayashi</a>

We use a suite of $N$-body simulations to study intrinsic alignments (IA) of

halo shapes with the surrounding large-scale structure in the $Lambda$CDM

model. For this purpose, we develop a novel method to measure multipole moments

of the three-dimensional power spectrum of the $E$-mode field of halo shapes

with the matter/halo distribution, $P_{delta E}^{(ell)}(k)$ (or

$P^{(ell)}_{{rm h}E}$), and those of the auto-power spectrum of the $E$ mode,

$P^{(ell)}_{EE}(k)$, based on the $E$/$B$-mode decomposition. The IA power

spectra have non-vanishing amplitudes over the linear to nonlinear scales, and

the large-scale amplitudes at $klesssim 0.1~h~{rm Mpc}^{-1}$ are related to

the matter power spectrum via a constant coefficient ($A_{rm IA}$), similar to

the linear bias parameter of galaxy or halo density field. We find that the

cross- and auto-power spectra $P_{delta E}$ and $P_{EE}$ at nonlinear scales,

$kgtrsim 0.1~h~{rm Mpc}^{-1}$, show different $k$-dependences relative to the

matter power spectrum, suggesting a violation of the nonlinear alignment model

commonly used to model contaminations of cosmic shear signals. The IA power

spectra exhibit baryon acoustic oscillations, and vary with halo samples of

different masses, redshifts and cosmological parameters ($Omega_{rm m},

S_8$). The cumulative signal-to-noise ratio for the IA power spectra is about

60% of that for the halo density power spectrum, where the super-sample

covariance is found to give a significant contribution to the total covariance.

Thus our results demonstrate that the IA power spectra of galaxy shapes,

measured from imaging and spectroscopic surveys for an overlapping area of the

sky, can be used to probe the underlying matter power spectrum, the primordial

curvature perturbations, and cosmological parameters, in addition to the

standard galaxy density power spectrum.

We use a suite of $N$-body simulations to study intrinsic alignments (IA) of

halo shapes with the surrounding large-scale structure in the $Lambda$CDM

model. For this purpose, we develop a novel method to measure multipole moments

of the three-dimensional power spectrum of the $E$-mode field of halo shapes

with the matter/halo distribution, $P_{delta E}^{(ell)}(k)$ (or

$P^{(ell)}_{{rm h}E}$), and those of the auto-power spectrum of the $E$ mode,

$P^{(ell)}_{EE}(k)$, based on the $E$/$B$-mode decomposition. The IA power

spectra have non-vanishing amplitudes over the linear to nonlinear scales, and

the large-scale amplitudes at $klesssim 0.1~h~{rm Mpc}^{-1}$ are related to

the matter power spectrum via a constant coefficient ($A_{rm IA}$), similar to

the linear bias parameter of galaxy or halo density field. We find that the

cross- and auto-power spectra $P_{delta E}$ and $P_{EE}$ at nonlinear scales,

$kgtrsim 0.1~h~{rm Mpc}^{-1}$, show different $k$-dependences relative to the

matter power spectrum, suggesting a violation of the nonlinear alignment model

commonly used to model contaminations of cosmic shear signals. The IA power

spectra exhibit baryon acoustic oscillations, and vary with halo samples of

different masses, redshifts and cosmological parameters ($Omega_{rm m},

S_8$). The cumulative signal-to-noise ratio for the IA power spectra is about

60% of that for the halo density power spectrum, where the super-sample

covariance is found to give a significant contribution to the total covariance.

Thus our results demonstrate that the IA power spectra of galaxy shapes,

measured from imaging and spectroscopic surveys for an overlapping area of the

sky, can be used to probe the underlying matter power spectrum, the primordial

curvature perturbations, and cosmological parameters, in addition to the

standard galaxy density power spectrum.

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