scholarly journals Baryonic effects on the matter bispectrum

2020 ◽  
Vol 498 (2) ◽  
pp. 2887-2911 ◽  
Author(s):  
Simon Foreman ◽  
William Coulton ◽  
Francisco Villaescusa-Navarro ◽  
Alexandre Barreira
Keyword(s):  
Perturbation Theory ◽  
Power Spectrum ◽  
Active Galactic Nuclei ◽  
Response Function ◽  
Large Scale ◽  
State Of The Art ◽  
Galactic Nuclei ◽  
Matter Power Spectrum ◽  
Hydrodynamical Simulations ◽  
Selection Of

ABSTRACT The large-scale clustering of matter is impacted by baryonic physics, particularly active galactic nuclei (AGN) feedback. Modelling or mitigating this impact will be essential for making full use of upcoming measurements of cosmic shear and other large-scale structure probes. We study baryonic effects on the matter bispectrum, using measurements from a selection of state-of-the-art hydrodynamical simulations: IllustrisTNG, Illustris, EAGLE, and BAHAMAS. We identify a low-redshift enhancement of the bispectrum, peaking at $k\sim 3\,h\, {\rm Mpc}^{-1}$, which is present in several simulations, and discuss how it can be associated to the evolving nature of AGN feedback at late times. This enhancement does not appear in the matter power spectrum, and therefore represents a new source of degeneracy breaking between two- and three-point statistics. In addition, we provide physical interpretations for other aspects of these measurements, and make initial comparisons to predictions from perturbation theory, empirical fitting formulas, and the response function formalism. We publicly release our measurements (including estimates of their uncertainty due to sample variance) and bispectrum measurement code as resources for the community.

scholarly journals The effect of AGN feedback on Sunyaev-Zeldovich properties of simulated galaxy clusters

2016 ◽  
Vol 12 (S324) ◽  
pp. 237-238
Author(s):  
Dunja Fabjan ◽  
S. Planelles ◽  
S. Borgani ◽  
G. Murante ◽  
E. Rasia ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galaxy Clusters ◽  
State Of The Art ◽  
Galaxy Cluster ◽  
Galactic Nuclei ◽  
Stellar Feedback ◽  
The Galaxy ◽  
History Of ◽  
Hydrodynamical Simulations ◽  
Massive Clusters

AbstractWe studied the imprints that feedback from Active Galactic Nuclei (AGN) leaves on the intracluster plasma during the assembly history of galaxy clusters. To this purpose we used state-of-the-art cosmological hydrodynamical simulations based on an updated version of the Tree-PM SPH GADGET-3 code, comparing three sets of simulations with different prescriptions for the physics of baryons (including AGN and/or stellar feedback). We explore the effect of these different physics, in particular AGN feedback, on IntraCluster medium (ICM) properties observed via Sunyaev-Zel’dovich (SZ) effect using an extended set of galaxy clusters (~100 clusters with M500 masses above 5 × 1013M⊙/h). Some of the main findings are that the scaling relation between the integrated SZ flux and the galaxy cluster total mass is in good accordance with several observed samples, especially for massive clusters, and does not show any clear redshift evolution, with the slope of the relation close to the theoretical one in the AGN feedback case. As for the scatter of this relation, we obtain a mild dependence on the cluster dynamical state.

scholarly journals Impact of cosmological signatures in two-point statistics beyond the linear regime

2020 ◽  
Author(s):  
D V Gomez-Navarro ◽  
A J Mead ◽  
A Aviles ◽  
A de la Macorra
Keyword(s):  
Perturbation Theory ◽  
Correlation Function ◽  
Power Spectrum ◽  
Large Scale ◽  
Line Of Sight ◽  
Linear Regime ◽  
Dark Sector ◽  
Linear Evolution ◽  
Matter Power Spectrum ◽  
Small Scales

Abstract Some beyond ΛCDM cosmological models have dark-sector energy densities that suffer phase transitions. Fluctuations entering the horizon during such a transition can receive enhancements that ultimately show up as a distinctive bump in the power spectrum relative to a model with no phase transition. In this work, we study the non-linear evolution of such signatures in the matter power spectrum and correlation function using N-body simulations, perturbation theory and hmcode- a halo-model based method. We focus on modelling the response, computed as the ratio of statistics between a model containing a bump and one without it, rather than in the statistics themselves. Instead of working with a specific theoretical model, we inject a parametric family of Gaussian bumps into otherwise standard ΛCDM spectra. We find that even when the primordial bump is located at linear scales, non-linearities tend to produce a second bump at smaller scales. This effect is understood within the halo model due to a more efficient halo formation. In redshift space these nonlinear signatures are partially erased because of the damping along the line-of-sight direction produced by non-coherent motions of particles at small scales. In configuration space, the bump modulates the correlation function reflecting as oscillations in the response, as it is clear in linear Eulerian theory; however, they become damped because large scale coherent flows have some tendency to occupy regions more depleted of particles. This mechanism is explained within Lagrangian Perturbation Theory and well captured by our simulations.

scholarly journals Anisotropic separate universe simulations

2020 ◽  
Vol 496 (1) ◽  
pp. 483-496 ◽  
Author(s):  
Shogo Masaki ◽  
Takahiro Nishimichi ◽  
Masahiro Takada
Keyword(s):  
Power Spectrum ◽  
Structure Formation ◽  
Response Function ◽  
Large Scale ◽  
Tidal Force ◽  
Simulation Code ◽  
Long Wavelength ◽  
Matter Power Spectrum ◽  
Anisotropic Expansion ◽  
Local Background

ABSTRACT The long-wavelength coherent overdensity and tidal force, which are not direct observables for a finite-volume survey, affect time evolution of cosmic structure formation and therefore clustering observables through the mode coupling. In this paper, we develop an ‘anisotropic’ separate universe (SU) simulation technique to simulate large-scale structure formation taking into account the effect of large-scale tidal force into the anisotropic expansion of local background. We modify the treepmN-body simulation code to implement the anisotropic SU simulations, and then study the ‘response’ function of matter power spectrum that describes how the matter power spectrum responds to the large-scale tidal effect as a function of wavenumber and redshift for a given global cosmology. We test and validate the SU simulation results from the comparison with the perturbation theory predictions and the results from high-resolution particle-mesh simulations. We find that the response function displays characteristic scale dependencies over the range of scales down to non-linear scales, up to k ≃ 6 h Mpc−1.

scholarly journals Modelling the large-scale mass density field of the universe as a function of cosmology and baryonic physics

2020 ◽  
Vol 495 (4) ◽  
pp. 4800-4819 ◽  
Author(s):  
Giovanni Aricò ◽  
Raul E Angulo ◽  
Carlos Hernández-Monteagudo ◽  
Sergio Contreras ◽  
Matteo Zennaro ◽  
...  
Keyword(s):  
Power Spectrum ◽  
Gravitational Lensing ◽  
Large Scale ◽  
Mass Density ◽  
Energy Models ◽  
Matter Power Spectrum ◽  
Non Linear ◽  
Massive Neutrinos ◽  
Hydrodynamical Simulations ◽  
The Universe

ABSTRACT We present and test a framework that models the 3D distribution of mass in the universe as a function of cosmological and astrophysical parameters. Our approach combines two different techniques: a rescaling algorithm that modifies the cosmology of gravity-only N-body simulations, and a ‘baryonification’ algorithm that mimics the effects of astrophysical processes induced by baryons, such as star formation and active galactic nuclei (AGN) feedback. We show how this approach can accurately reproduce the effects of baryons on the matter power spectrum of various state-of-the-art hydrodynamical simulations (EAGLE, Illustris, Illustris-TNG, Horizon-AGN, and OWLS, Cosmo-OWLS and BAHAMAS), to better than 1 per cent from very large down to small, highly non-linear, scales ($k\sim 5 \, h\, {\rm Mpc}^{-1}$), and from z = 0 up to z ∼ 2. We highlight that, because of the heavy optimization of our algorithms, we can obtain these predictions for arbitrary baryonic models and cosmology (including massive neutrinos and dynamical dark energy models) with an almost negligible CPU cost. With these tools in hand, we explore the degeneracies between cosmological and astrophysical parameters in the non-linear mass power spectrum. Our findings suggest that after marginalizing over baryonic physics, cosmological constraints inferred from weak gravitational lensing should be moderately degraded.

scholarly journals Imprint of baryons and massive neutrinos on velocity statistics

2020 ◽  
Vol 644 ◽  
pp. A170
Author(s):  
Joseph Kuruvilla ◽  
Nabila Aghanim ◽  
Ian G. McCarthy
Keyword(s):  
Active Galactic Nuclei ◽  
Large Scale ◽  
Galactic Nuclei ◽  
Microwave Background ◽  
Velocity Statistics ◽  
Sunyaev Zel'dovich Effect ◽  
Massive Neutrinos ◽  
Hydrodynamical Simulations ◽  
The Impact ◽  
Velocity Bias

We explored the impact of baryonic effects (namely stellar and active galactic nuclei feedback) on the moments of pairwise velocity using the Illustris-TNG, EAGLE, cosmo-OWLS, and BAHAMAS suites of cosmological hydrodynamical simulations. The assumption that the mean pairwise velocity of the gas component follows that of the dark matter is studied here at small separations, and we find that even at pair separations of 10–20 h−1Mpc, there is a 4–5% velocity bias. At smaller separations, it gets larger with varying strength depending on the sub-grid prescription. By isolating different physical processes, our findings suggest that the large-scale velocity bias is mainly driven by stellar rather than active galactic nuclei feedback. If unaccounted for, this velocity offset could possibly bias cosmological constraints from the kinetic Sunyaev-Zel’dovich effect in future cosmic microwave background (CMB) surveys. Furthermore, we examined how the first and the second moment of the pairwise velocity are affected by both the baryonic and the neutrino free-streaming effects for both the matter and gas components. For both moments, we were able to disentangle the effects of baryonic processes from those of massive neutrinos; and for pair separations below 20 h−1Mpc, we find that these moments of the pairwise velocity decrease with increasing neutrino mass. Our work thus sets out a way in which the pairwise velocity statistics can be utilised to constrain the summed mass of neutrinos from future CMB surveys and peculiar velocity surveys.

scholarly journals Accelerating Large-Scale-Structure data analyses by emulating Boltzmann solvers and Lagrangian Perturbation Theory

2021 ◽  
Vol 1 ◽  
pp. 152
Author(s):  
Giovanni Arico' ◽  
Raul Angulo ◽  
Matteo Zennaro
Keyword(s):  
Perturbation Theory ◽  
Power Spectrum ◽  
Large Scale ◽  
Theoretical Models ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Matter Power Spectrum ◽  
Linear Spectrum ◽  
Massive Neutrinos ◽  
Cold Matter

The linear matter power spectrum is an essential ingredient in all theoretical models for interpreting large-scale-structure observables. Although Boltzmann codes such as CLASS or CAMB are very efficient at computing the linear spectrum, the analysis of data usually requires 104-106 evaluations, which means this task can be the most computationally expensive aspect of data analysis. Here, we address this problem by building a neural network emulator that provides the linear theory (total and cold) matter power spectrum in about one millisecond with ≈0.2%(0.5%) accuracy over redshifts z ≤ 3 (z ≤ 9), and scales10-4 ≤ k [h Mpc-1] < 50. We train this emulator with more than 200,000 measurements, spanning a broad cosmological parameter space that includes massive neutrinos and dynamical dark energy. We show that the parameter range and accuracy of our emulator is enough to get unbiased cosmological constraints in the analysis of a Euclid-like weak lensing survey. Complementing this emulator, we train 15 other emulators for the cross-spectra of various linear fields in Eulerian space, as predicted by 2nd-order Lagrangian Perturbation theory, which can be used to accelerate perturbative bias descriptions of galaxy clustering. Our emulators are specially designed to be used in combination with emulators for the nonlinear matter power spectrum and for baryonic effects, all of which are publicly available at http://www.dipc.org/bacco.

scholarly journals The anisotropy of the power spectrum in periodic cosmological simulations

2021 ◽  
Vol 503 (4) ◽  
pp. 5638-5645
Author(s):  
Gábor Rácz ◽  
István Szapudi ◽  
István Csabai ◽  
László Dobos
Keyword(s):  
Dark Matter ◽  
Power Spectrum ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Initial Conditions ◽  
Power Spectra ◽  
Cosmological Simulations ◽  
Spherical Collapse ◽  
Lower Amplitude ◽  
Hydrodynamical Simulations

ABSTRACT The classical gravitational force on a torus is anisotropic and always lower than Newton’s 1/r2 law. We demonstrate the effects of periodicity in dark matter only N-body simulations of spherical collapse and standard Lambda cold dark matter (ΛCDM) initial conditions. Periodic boundary conditions cause an overall negative and anisotropic bias in cosmological simulations of cosmic structure formation. The lower amplitude of power spectra of small periodic simulations is a consequence of the missing large-scale modes and the equally important smaller periodic forces. The effect is most significant when the largest mildly non-linear scales are comparable to the linear size of the simulation box, as often is the case for high-resolution hydrodynamical simulations. Spherical collapse morphs into a shape similar to an octahedron. The anisotropic growth distorts the large-scale ΛCDM dark matter structures. We introduce the direction-dependent power spectrum invariant under the octahedral group of the simulation volume and show that the results break spherical symmetry.

scholarly journals Probing the cool ISM in galaxies via 21 cm H i absorption

2012 ◽  
Vol 8 (S292) ◽  
pp. 188-188
Author(s):  
J. R. Allison ◽  
E. M. Sadler ◽  
S. J. Curran ◽  
S. N. Reeves
Keyword(s):  
Spectral Line ◽  
Active Galactic Nuclei ◽  
Large Scale ◽  
Galactic Nuclei ◽  
Host Galaxies ◽  
The Galaxy ◽  
Early Type Galaxy ◽  
Finding Method ◽  
Compact Array ◽  
Cold Gas

AbstractRecent targeted studies of associated H i absorption in radio galaxies are starting to map out the location, and potential cosmological evolution, of the cold gas in the host galaxies of Active Galactic Nuclei (AGN). The observed 21 cm absorption profiles often show two distinct spectral-line components: narrow, deep lines arising from cold gas in the extended disc of the galaxy, and broad, shallow lines from cold gas close to the AGN (e.g. Morganti et al. 2011). Here, we present results from a targeted search for associated H i absorption in the youngest and most recently-triggered radio AGN in the local universe (Allison et al. 2012b). So far, by using the recently commissioned Australia Telescope Compact Array Broadband Backend (CABB; Wilson et al. 2011), we have detected two new absorbers and one previously-known system. While two of these show both a broad, shallow component and a narrow, deep component (see Fig. 1), one of the new detections has only a single broad, shallow component. Interestingly, the host galaxies of the first two detections are classified as gas-rich spirals, while the latter is an early-type galaxy. These detections were obtained using a spectral-line finding method, based on Bayesian inference, developed for future large-scale absorption surveys (Allison et al. 2012a).

scholarly journals Symmetry and the Arrow of Time in Theoretical Black Hole Astrophysics

2015 ◽  
Vol 2015 ◽  
pp. 1-5
Author(s):  
David Garofalo
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Active Galactic Nuclei ◽  
Accretion Disks ◽  
Time Reversal ◽  
Large Scale ◽  
Galactic Nuclei ◽  
Arrow Of Time ◽  
Time Symmetry ◽  
The Universe

While the basic laws of physics seem time-reversal invariant, our understanding of the apparent irreversibility of the macroscopic world is well grounded in the notion of entropy. Because astrophysics deals with the largest structures in the Universe, one expects evidence there for the most pronounced entropic arrow of time. However, in recent theoretical astrophysics work it appears possible to identify constructs with time-reversal symmetry, which is puzzling in the large-scale realm especially because it involves the engines of powerful outflows in active galactic nuclei which deal with macroscopic constituents such as accretion disks, magnetic fields, and black holes. Nonetheless, the underlying theoretical structure from which this accreting black hole framework emerges displays a time-symmetric harmonic behavior, a feature reminiscent of basic and simple laws of physics. While we may expect such behavior for classical black holes due to their simplicity, manifestations of such symmetry on the scale of galaxies, instead, surprise. In fact, we identify a parallel between the astrophysical tug-of-war between accretion disks and jets in this model and the time symmetry-breaking of a simple overdamped harmonic oscillator. The validity of these theoretical ideas in combination with this unexpected parallel suggests that black holes are more influential in astrophysics than currently recognized and that black hole astrophysics is a more fundamental discipline.

scholarly journals Disentangling AGN and starburst activities in NGC 6240 from an X-ray perspective

2014 ◽  
Vol 10 (S312) ◽  
pp. 36-38
Author(s):  
Junfeng Wang
Keyword(s):  
Active Galactic Nuclei ◽  
Large Scale ◽  
Imaging Spectroscopy ◽  
Galactic Nuclei ◽  
Resolving Power ◽  
High Excitation ◽  
X Ray ◽  
Supermassive Black Hole ◽  
X Ray Imaging ◽  
High Temperature Gas

AbstractThe circum-nuclear region in an active galaxy is often complex with presence of high excitation gas, collimated radio outflow, and star formation activities, besides the actively accreting supermassive black hole. The unique spatial resolving power of Chandra X-ray imaging spectroscopy enables more investigations to disentangle the active galactic nuclei and starburst activities. For galaxies in the throes of a violent merging event such as NGC6240, we were able to resolve the high temperature gas surrounding its binary active black holes and discovered a large scale soft X-ray halo.

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