The density distribution of accreting cosmic filaments as shaped by Kelvin-Helmholtz instability

Abstract

Cosmic filaments play a crucial role in galaxy evolution transporting gas from the intergalactic medium into galaxies. However, little is known about the efficiency of this process and whether the gas is accreted in a homogenous or clumpy way. Recent observations suggest the presence of broad gas density distributions in the circumgalactic medium which could be related to the accretion of filaments. By means of high-resolution hydrodynamical simulations, we explore here the evolution of cold accreting filaments flowing through the hot circumgalactic medium (CGM) of high-z galaxies. In particular, we examine the nonlinear effects of Kelvin-Helmholtz instability (KHI) on the development of broad gas density distributions and on the formation of cold, dense clumps. We explore a large parameter space in filament and perturbation properties, such as, filament Mach number, initial perturbation wavelength, and thickness of the interface between the filament and the halo. We find that the time averaged density distribution of the cold gas is qualitatively consistent with a skewed log-normal probability distribution function (PDF) plus an additional component in form of a high density tail for high Mach-numbers. Our results suggest a tight correlation between the accreting velocity and the maximum densities developing in the filament which is consistent with the variance-Mach number relation for turbulence. Therefore, cosmological accretion could be a viable mechanism to produce turbulence and broad gas density distributions within the CGM.

arXiv comment12 pages, 14 figures, submitted to MNRAS on April 3rd 2019

References in corpus (35)

• How Do Galaxies Get Their Gas?
• Cosmological Hydrodynamics with Adaptive Mesh Refinement: a new high resolution code called RAMSES
• Galaxy Bimodality due to Cold Flows and Shock Heating
• Cold streams in early massive hot haloes as the main mode of galaxy formation
• How Filaments are Woven into the Cosmic Web
• Virial shocks in galactic haloes?
• The Stellar IMF from Turbulent Fragmentation
• Comparing the statistics of interstellar turbulence in simulations and observations: Solenoidal versus compressive turbulence forcing
• The Density Probability Distribution in Compressible Isothermal Turbulence: Solenoidal versus Compressive Forcing
• A cosmic web filament revealed in Lyman-alpha emission around a luminous high-redshift quasar
• Density probability distribution in one-dimensional polytropic gas dynamics
• Bimodal gas accretion in the Horizon-MareNostrum galaxy formation simulation
• The rates and modes of gas accretion on to galaxies and their gaseous haloes
• Ubiquitous giant Ly $\alpha$ nebulae around the brightest quasars at $z\sim 3.5$ revealed with MUSE
• The Baryonic Assembly of Dark Matter Halos
• High-redshift clumpy discs and bulges in cosmological simulations
• Quasar Quartet Embedded in Giant Nebula Reveals Rare Massive Structure in Distant Universe
• Supersonic turbulence in the ISM: stellar extinction determinations as probes of the structure and dynamics of dark clouds
• Clustering of intermediate redshift quasars using the final SDSS III-BOSS sample
• The survival of gas clouds in the Circumgalactic Medium of Milky Way-like galaxies
• Discovery of an Enormous Ly$\alpha$ nebula in a massive galaxy overdensity at $z=2.3$
• IGM Emission Observations with the Cosmic Web Imager: I. The Circum-QSO Medium of QSO 1549+19, and Evidence for a Filamentary Gas Inflow
• A Model for (Non-Lognormal) Density Distributions in Isothermal Turbulence
• The large and small scale properties of the intergalactic gas in the Slug Ly-alpha nebula revealed by MUSE HeII emission observations
• Computational Eulerian Hydrodynamics and Galilean Invariance
• A Validated Nonlinear Kelvin-Helmholtz Benchmark for Numerical Hydrodynamics
• Deep HeII and CIV Spectroscopy of a Giant Lyman alpha Nebula: Dense Compact Gas Clumps in the Circumgalactic Medium of a z~2 Quasar
• Instability of Supersonic Cold Streams Feeding Galaxies I: Linear Kelvin-Helmholtz Instability with Body Modes
• The survival of interstellar clouds against Kelvin-Helmholtz instabilities
• Instability of Supersonic Cold Streams Feeding Galaxies III: Kelvin-Helmholtz Instability in Three Dimensions
• The distribution of density in supersonic turbulence
• The Stability of Radiatively Cooled Jets in Three Dimensions
• Instability of Supersonic Cold Streams Feeding Galaxies II. Nonlinear Evolution of Surface and Body Modes of Kelvin-Helmholtz Instability
• On the Kelvin-Helmholtz instability with smooth initial conditions -- Linear theory and simulations
• Kelvin-Helmholtz Instability in Self-Gravitating Streams

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• The Gravitational Instability of Adiabatic Filaments
• Clouds accreting from the IGM are not able to feed the star formation of low-redshift disc galaxies
• Characterizing the Circumgalactic Medium of Quasars at z $\sim$ 2.2 through H$\alpha$ and Ly$\alpha$ Emission
• Stability and Ly$\alpha$ emission of Cold Stream in the Circumgalactic Medium: impact of magnetic fields and thermal conduction
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