Baryon-CDM isocurvature galaxy bias with IllustrisTNG

Abstract

We study the impact that baryon-CDM relative density perturbations ${\delta }_{bc}$ have on galaxy formation using cosmological simulations with the IllustrisTNG model. These isocurvature (non-adiabatic) perturbations can be induced primordially, if multiple fields are present during inflation, and are generated before baryon-photon decoupling when baryons did not comove with CDM. The presence of long-wavelength ${\delta }_{bc}$ perturbations in our simulations is mimicked by modifying the ratios of the cosmic densities of baryons ${\Omega }_b$ and CDM ${\Omega }_c$, at fixed total matter density ${\Omega }_m$. We measure the corresponding galaxy bias parameter $b_{\delta }^{bc}$ as the response of galaxy abundances to ${\delta }_{bc}$. When selecting by total host halo mass, $b_{\delta }^{bc}$ is negative and it decreases with mass and redshift. Stellar-mass selected simulated galaxies show a weaker or even the opposite trend because of the competing effects of ${\delta }_{bc}$ on the halo mass function and stellar-to-halo-mass relations. We show that simple modeling of the latter two effects describes $b_{\delta }^{bc}$ for stellar-mass-selected objects well. We find $b_{\delta }^{bc}=0.6$ for $M_{\ast }=10^{11}{M}_{\odot }/h$ and $z=0.5$, which is representative of BOSS DR12 galaxies. For ${\delta }_{bc}$ modes generated by baryon-photon interactions, we estimate the impact on the DR12 power spectrum to be below $1\%$, and shifts on inferred distance and growth rate parameters should not exceed $0.1\%$.

18 pages (+8 pages with appendices and references); 8 figures; 1 table; comments welcomed. In v2: (i) extended discussion with new figure on the generation of baryon-CDM perturbations; (ii) new figure quantifying the contributions to the bias parameter from changes in the mass function and changes in the stellar-to-halo-mass relations. v3 matches version published in JCAP

References in corpus (25)

• Introducing the Illustris Project: Simulating the coevolution of dark and visible matter in the Universe
• Simulating galaxy formation with black hole driven thermal and kinetic feedback
• Introducing the Illustris Project: the evolution of galaxy populations across cosmic time
• Clustering of dark matter tracers: generalizing bias for the coming era of precision LSS
• The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: Anisotropic galaxy clustering in Fourier-space
• Gravity and Large-Scale Non-local Bias
• Understanding higher-order nonlocal halo bias at large scales by combining the power spectrum with the bispectrum
• Cosmology with the SPHEREX All-Sky Spectral Survey
• Separate Universe Simulations
• Large-scale BAO signatures of the smallest galaxies
• Analytic Prediction of Baryonic Effects from the EFT of Large Scale Structures
• Super-Sample Signal
• On the signature of the baryon-dark matter relative velocity in the two and three-point galaxy correlation functions
• Third-order Perturbation Theory With Non-linear Pressure
• Forecasted 21 cm constraints on compensated isocurvature perturbations
• Supersonic Relative Velocity between Dark Matter and Baryons: A Review
• Separate Universe Simulations with IllustrisTNG: baryonic effects on power spectrum responses and higher-order statistics
• Biased Tracers of Two Fluids in the Lagrangian Picture
• The Supersonic Project: Shining Light on SIGOs - a New Formation Channel for Globular Clusters
• A robust measurement of the first higher-derivative bias of dark matter halos
• Probing correlated compensated isocurvature perturbations using scale-dependent galaxy bias
• Accurate initial conditions in mixed Dark Matter--Baryon simulations
• The IllustrisTNG Simulations: Public Data Release
• A new scale in the bias expansion
• BAO Modulation as a Probe of Compensated Isocurvature Perturbations

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• New Interpretations of the Cosmological Preference for a Negative Neutrino Mass
• Magnetic Fields from Compensated Isocurvature Perturbations
• Scale-dependent halo bias and the squeezed limit bispectrum in the presence of radiation
• The intrinsic bispectrum of the CMB from isocurvature initial conditions
• Cosmic voids and BAO with relative baryon-CDM perturbations