Turbulence-induced deviation between baryonic field and dark matter field in the spatial distribution of the Universe

Abstract

The cosmic baryonic fluid at low redshifts is similar to a fully developed turbulence. In this work, we use simulation samples produced by the hybrid cosmological hydrodynamical/N-body code, to investigate on what scale the deviation of spatial distributions between baryons and dark matter is caused by turbulence. For this purpose, we do not include the physical processes such as star formation, SNe and AGN feedbacks into our code, so that the effect of turbulence heating for IGM can be exhibited to the most extent. By computing cross-correlation functions rm(k) for the density field and rv(k) for the velocity field of both baryons and dark matter, we find that deviations between the two matter components for both density field and velocity field, as expected, are scale-dependent. That is, the deviations are the most significant at small scales and gradually diminish on larger and larger scales. Also, the deviations are time-dependent, i.e. they become larger and larger with increasing cosmic time. The most emphasized result is that the spatial deviations between baryons and dark matter revealed by velocity field are more significant than that by density field. At z = 0, at the $1\%$ level of deviation, the deviation scale is about 3.7 h−1Mpc for density field, while as large as 23 h−1Mpc for velocity field, a scale that falls within the weakly non-linear regime for the structure formation paradigm. Our results indicate that the effect of turbulence heating is indeed comparable to that of these processes such as SNe and AGN feedbacks.

The spatial distribution deviation and the power suppression of baryons from dark matter

“…As demonstrated in Yang et al (2020), the linear bias model is oversimplified and is not able to describe the bias of spatial distribution between dark matter and baryon matter. In this work, we continue to use the non-linear bias model previously used as follows,…”

“…The valid scale range is restricted to be k < 8 hMpc −1 for WIGEON data. One can find the reason of such choice in Yang et al (2020). The error bars are computed in the same way as in Yang et al (2020).…”

“…One can find the reason of such choice in Yang et al (2020). The error bars are computed in the same way as in Yang et al (2020).…”

“…Both observations and theories of contemporary cosmology reveal that the spatial distribution of the cosmic dark matter and baryons is biased or deviates from each other. In a previous work (Yang et al 2020), we make use of numerical simulation data produced by the cosmological N -body/hydrodynamical code WIGEON (Zhu et al 2013), to study to what extent the deviation of spatial distribution between dark matter and baryons is. By computing the cross-correlation functions of density field and velocity field for the two matter components, we find that deviations between dark matter and baryonic matter are the most prominent on small scales and diminish gradually on increasingly large scales.…”

Continuous wavelet analysis of matter clustering using the Gaussian-derived wavelet

“…However, luminous objects are made up of baryons, whose clustering is not completely consistent with that of dark matter (DM) component because of a series of physical processes such as radiative cooling, star formation and feedback processes. With hybrid Nbody/hydrodynamic simulations, the baryonic effects on the large-scale clustering of matter have been extensively studied in Fourier space, and these studies show that the deviation between baryons and dark matter in mass distribution depends on the scale and redshift (Chisari et al 2019;van Daalen et al 2020;Yang et al 2020). Moreover, many studies indi-cate that the clustering of both dark matter and baryonic matter is environment-dependent (Abbas & Sheth 2005;Peng et al 2010;Wang et al 2018;Man et al 2019).…”