Measuring the tidal response of structure formation: anisotropic separate universe simulations using <scp>treepm</scp>

Stücker, Jens; Schmidt, Andreas S.; White, Simon D. M.; Hahn, Oliver

doi:10.1093/mnras/stab473

Cited by 25 publications

(38 citation statements)

References 53 publications

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“…[20] followed this approach using several realizations of gravity-only simulations with sizes ranging between L box = 1000Mpc/h and L box = 2400Mpc/h, but these simulation volumes are currently numerically prohibitive with galaxy formation models like IllustrisTNG. Methods based on separate universe simulations [9,25,[85][86][87][88][89][90][91][92] do not strictly require large simulation volumes, but estimates of b 1 and b 2 still involve re-running the simulations for cosmological parameters that mimic different values of the long-wavelength overdensity. The same is true for separate universe simulations with tidal fields [89][90][91][92], although these have not yet been performed with galaxy formation simulations.…”

Section: Discussionmentioning

confidence: 99%

Galaxy bias from forward models: linear and second-order bias of IllustrisTNG galaxies

Barreira,

Lazeyras,

Schmidt

2021

Preprint

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We use field-level forward models of galaxy clustering and the EFT likelihood formalism to study, for the first time for self-consistently simulated galaxies, the relations between the linear b 1 and second-order bias parameters b 2 and b K 2 . The forward models utilize all of the information available in the galaxy distribution up to a given order in perturbation theory, which allows us to infer these bias parameters with high signal-to-noise, even from relatively small volumes (L box = 205Mpc/h). We consider galaxies from the IllustrisTNG simulations, and our main result is that the b 2 (b 1 ) and b K 2 (b 1 ) relations obtained from gravity-only simulations for total mass selected objects are broadly preserved for simulated galaxies selected by stellar mass, star formation rate, color and black hole accretion rate. This consistency under different galaxy selection criteria suggests that theoretical priors on these bias relations may be used to improve cosmological constraints based on observed galaxy samples. We do identify some small differences between the bias relations in the hydrodynamical and gravity-only simulations, which we show can be linked to the environmental dependence of the relation between galaxy properties and mass. We also show that the EFT likelihood recovers the value of σ 8 to percent-level from various galaxy samples (including splits by color and star formation rate) and after marginalizing over 8 bias parameters. This demonstration using simulated galaxies adds to previous works based on halos as tracers, and strengthens further the potential of forward models to infer cosmology from galaxy data.

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Section: Discussionmentioning

confidence: 99%

Galaxy bias from forward models: linear and second-order bias of IllustrisTNG galaxies

Barreira,

Lazeyras,

Schmidt

2021

Preprint

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“…and are solved alongside the N-body equations of motion (31) by computing the tidal tensor T. One caveat with the GDE approach is that the evolution of D xq is determined not by the force but by the tidal field-which contains one higher spatial derivative of the potential than the force-and therefore is significantly less regular than the force field (see the detailed discussion and analysis in Stu ¨cker et al (2021c) who have also studied the stream density evolution in virialised halos, based on a novel low-noise force calculation). This approach thus requires larger softening to achieve converged answers than a usual N-body simulation, and possibly cannot be shown to converge in the limit of infinite density caustics.…”

Section: Tracking Deformation In Phase Space-the Gde Approachmentioning

confidence: 99%

“…More realistically, a given volume will also be exposed to anisotropic deformation due to a large-scale tidal field. Schmidt et al (2018) (see also Stu ¨cker et al 2021c;Masaki et al 2020;Akitsu et al 2020) have demonstrated that such a global anisotropy can be accounted for by a modification of the force calculation in numerical simulations. These simulations have been used to study the role of largescale tidal fields in the abundance and shape of dark matter halos and the response of the anisotropic power spectrum, and will be very useful also for studies of coherent alignment effects of haloes and galaxies which are important to understand intrinsic alignments in weak gravitational lensing.…”

Section: Separate Universe Simulationsmentioning

confidence: 99%

Large-scale dark matter simulations

Angulo

Hahn

2022

Living Rev Comput Astrophys

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We review the field of collisionless numerical simulations for the large-scale structure of the Universe. We start by providing the main set of equations solved by these simulations and their connection with General Relativity. We then recap the relevant numerical approaches: discretization of the phase-space distribution (focusing on N-body but including alternatives, e.g., Lagrangian submanifold and Schrödinger–Poisson) and the respective techniques for their time evolution and force calculation (direct summation, mesh techniques, and hierarchical tree methods). We pay attention to the creation of initial conditions and the connection with Lagrangian Perturbation Theory. We then discuss the possible alternatives in terms of the micro-physical properties of dark matter (e.g., neutralinos, warm dark matter, QCD axions, Bose–Einstein condensates, and primordial black holes), and extensions to account for multiple fluids (baryons and neutrinos), primordial non-Gaussianity and modified gravity. We continue by discussing challenges involved in achieving highly accurate predictions. A key aspect of cosmological simulations is the connection to cosmological observables, we discuss various techniques in this regard: structure finding, galaxy formation and baryonic modelling, the creation of emulators and light-cones, and the role of machine learning. We finalise with a recount of state-of-the-art large-scale simulations and conclude with an outlook for the next decade.

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“…where 𝐺 1 and 𝐺 𝐾 are so-called growth-only response functions, which can be measured very efficiently in the nonlinear regime of structure formation using separate universe simulations. In this paper, we use the measurements of 𝐺 1 from Wagner et al (2015) and the measurements of 𝐺 𝐾 from Schmidt et al (2018) (see also Stücker et al (2021)); the time and scale-dependence of the resulting 𝑅 1 (𝑘, 𝜏), 𝑅 𝐾 (𝑘, 𝜏) functions can be seen alongside one another in Fig. 1 of Barreira et al 2018.…”

Section: Response Approach To the Squeezed Matter Bispectrummentioning

confidence: 99%

Response approach to the integrated shear 3-point correlation function: the impact of baryonic effects on small scales

Halder,

Barreira

2022

Preprint

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The integrated shear 3-point correlation function 𝜁 ± is a higher-order statistic of the cosmic shear field that describes the modulation of the 2-point correlation function 𝜉 ± by long-wavelength features in the field. Here, we introduce a new theoretical model to calculate 𝜁 ± that is accurate on small angular scales, and that allows to take baryonic feedback effects into account. Our model builds on the realization that the small-scale 𝜁 ± is dominated by the nonlinear matter bispectrum in the squeezed limit, which can be evaluated accurately using the nonlinear matter power spectrum and its first-order response functions to density and tidal field perturbations. We demonstrate the accuracy of our model by showing that it reproduces the small-scale 𝜁 ± measured in simulated cosmic shear maps. The impact of baryonic feedback enters effectively only through the corresponding impact on the nonlinear matter power spectrum, thereby permitting to account for these astrophysical effects on 𝜁 ± similarly to how they are currently accounted for on 𝜉 ± . Using a simple idealized Fisher matrix forecast for a DES-like survey we find that, compared to 𝜉 ± , a combined 𝜉 ± & 𝜁 ± analysis can lead to improvements of order 20 − 40% on the constraints of cosmological parameters such as 𝜎 8 or the dark energy equation of state parameter 𝑤 0 . We find similar levels of improvement on the constraints of the baryonic feedback parameters, which strengthens the prospects for cosmic shear data to obtain tight constraints not only on cosmology but also on astrophysical feedback models. These are encouraging results that motivate future works on the integrated shear 3-point correlation function towards applications to real survey data.

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Measuring the tidal response of structure formation: anisotropic separate universe simulations using treepm

Cited by 25 publications

References 53 publications

Galaxy bias from forward models: linear and second-order bias of IllustrisTNG galaxies

Galaxy bias from forward models: linear and second-order bias of IllustrisTNG galaxies

Large-scale dark matter simulations

Response approach to the integrated shear 3-point correlation function: the impact of baryonic effects on small scales

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