Unmasking the masked Universe: the 2M++ catalogue through Bayesian eyes

Lavaux, Guilhem; Jasche, Jens

doi:10.1093/mnras/stv2499

Cited by 79 publications

(114 citation statements)

References 43 publications

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“…The application of Bayesian quasi-linear Hamiltonian Markov Chain Monte Carlo sampling methods to galaxy redshift surveys has provided a new and interesting way to reconstruct the local universe (see e.g. Kitaura et al 2010;Jasche et al 2010;Wang et al 2014;Ata et al 2015;Lavaux & Jasche 2016). Yet, these methods have a limited scope of resolution of a few megaparsecs and therefore are unable to resolve the LG itself.…”

Section: Introductionmentioning

confidence: 99%

Constrained Local UniversE Simulations: a Local Group factory

Carlesi¹,

Sorce

Hoffman³

et al. 2016

Mon. Not. R. Astron. Soc.

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Near field cosmology is practiced by studying the Local Group (LG) and its neighbourhood. The present paper describes a framework for simulating the "near field" on the computer. Assuming the ΛCDM model as a prior and applying the Bayesian tools of the Wiener filter (WF) and constrained realizations of Gaussian fields to the Cosmicflows-2 (CF2) survey of peculiar velocities, constrained simulations of our cosmic environment are performed. The aim of these simulations is to reproduce the LG and its local environment. Our main result is that the LG is likely a robust outcome of the ΛCDM scenario when subjected to the constraint derived from CF2 data, emerging in an environment akin to the observed one. Three levels of criteria are used to define the simulated LGs. At the base level, pairs of halos must obey specific isolation, mass and separation criteria. At the second level the orbital angular momentum and energy are constrained and on the third one the phase of the orbit is constrained. Out of the 300 constrained simulations 146LGs obey the first set of criteria, 51 the second and 6 the third. The robustness of our LG 'factory' enables the construction of a large ensemble of simulated LGs. Suitable candidates for high resolution hydrodynamical simulations of the LG can be drawn from this ensemble, which can be used to perform comprehensive studies of the formation of the LG.

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Section: Introductionmentioning

confidence: 99%

Constrained Local UniversE Simulations: a Local Group factory

Carlesi¹,

Sorce

Hoffman³

et al. 2016

Mon. Not. R. Astron. Soc.

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“…Second, it has a homogeneous limiting K-band magnitude (mK < 12.5), which will facilitate our modelling of the contributions to the proxies from missing objects by means of an N-body simulation in Section 2.2. Finally, the catalogue has already been used to estimate the smoothed density field in the survey volume (Lavaux & Jasche 2016), which provides an important contribution to our proxies that is largely independent of those above.…”

Section: Primary Source Cataloguementioning

confidence: 99%

“…The analysis of Section 2.2 therefore continues to underestimate the proxies. To model the remaining mass we use the results of Lavaux & Jasche (2016), who apply 2LPT in a Bayesian framework to derive the probability distribution for the z = 0 density field consistent with the number density and peculiar velocities of the 2M++ galaxies. This is done on a 3D grid of spacing 2.3 h −1 Mpc and therefore provides an accurate estimate of the power spectrum on scales k 1 h Mpc −1 .…”

Section: Modelling the Remaining Missing Massmentioning

confidence: 99%

“…Although this method reconstructs approximately 100 per cent of the mass in the 2M++ volume, the smoothing scale of ∼ 3.4 Mpc means that the screening proxies cannot be estimated from this mass alone; their scaling with r −n makes them sensitive to smaller-scale overdensities such as we have already modelled in Sections 2.1 and 2.2. We estimate the proxy values due to all mass by summing the contributions from the resolved halos and 2M++ galaxies, derived in Section 2.2, to those from the mass field derived by smoothly interpolating the density grid of Lavaux & Jasche (2016) at a representative point in their MCMC chain.…”

Section: Modelling the Remaining Missing Massmentioning

confidence: 99%

“…Thus the 2M++ galaxy sample corresponds to a range of possible Φvis, avis and Kvis fields, of which we show simply example realisations. Within the AM framework, this derives from the combination of a statistical uncertainty due to Smoothed density field Galaxy number density and peculiar velocity fields (Lavaux & Jasche 2016) P (M vir , c|L; α, σ AM ) Abundance matching mock with fixed halo proxy and scatter…”

Section: Sources Of Uncertaintymentioning

confidence: 99%

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Reconstructing the gravitational field of the local Universe

Desmond

Ferreira

Lavaux

et al. 2017

Monthly Notices of the Royal Astronomical Society

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Tests of gravity at the galaxy scale are in their infancy. As a first step to systematically uncovering the gravitational significance of galaxies, we map three fundamental gravitational variables -the Newtonian potential, acceleration and curvature -over the galaxy environments of the local universe to a distance of approximately 200 Mpc. Our method combines the contributions from galaxies in an all-sky redshift survey, halos from an N-body simulation hosting low-luminosity objects, and linear and quasilinear modes of the density field. We use the ranges of these variables to determine the extent to which galaxies expand the scope of generic tests of gravity and are capable of constraining specific classes of model for which they have special significance. Finally, we investigate the improvements afforded by upcoming galaxy surveys.

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Large-scale dark matter simulations

Angulo

Hahn

2022

Living Rev Comput Astrophys

111

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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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Unmasking the masked Universe: the 2M++ catalogue through Bayesian eyes

Cited by 79 publications

References 43 publications

Constrained Local UniversE Simulations: a Local Group factory

Constrained Local UniversE Simulations: a Local Group factory

Reconstructing the gravitational field of the local Universe

Large-scale dark matter simulations

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