Galaxy orientation with the cosmic web across cosmic time

Abstract

This work investigates the alignment of galactic spins with the cosmic web across cosmic time using the cosmological hydrodynamical simulation Horizon-AGN. The cosmic web structure is extracted via the persistent skeleton as implemented in the DISPERSE algorithm. It is found that the spin of low-mass galaxies is more likely to be aligned with the filaments of the cosmic web and to lie within the plane of the walls while more massive galaxies tend to have a spin perpendicular to the axis of the filaments and to the walls. The mass transition is detected with a significance of 9 sigmas. This galactic alignment is consistent with the alignment of the spin of dark haloes found in pure dark matter simulations and with predictions from (anisotropic) tidal torque theory. However, unlike haloes, the alignment of low-mass galaxies is weak and disappears at low redshifts while the orthogonal spin orientation of massive galaxies is strong and increases with time, probably as a result of mergers. At fixed mass, alignments are correlated with galaxy morphology: the high-redshift alignment is dominated by spiral galaxies while elliptical centrals are mainly responsible for the perpendicular signal. These predictions for spin alignments with respect to cosmic filaments and unprecendently walls are successfully compared with existing observations. The alignment of the shape of galaxies with the different components of the cosmic web is also investigated. A coherent and stronger signal is found in terms of shape at high mass. The two regimes probed in this work induce competing galactic alignment signals for weak lensing, with opposite redshift and luminosity evolution. Understanding the details of these intrinsic alignments will be key to exploit future major cosmic shear surveys like Euclid or LSST.

The SAMI Galaxy Survey: first detection of a transition in spin orientation with respect to cosmic filaments in the stellar kinematics of galaxies

“…Using more than 150, 000 galaxies, Dubois et al (2014) and Codis et al (2018) predict that such a signal is robust and detectable using various tracers of galaxy evolution, yet very weak in the redshift ranges z = 1.2 − 1.8 and z = 1 − 0, with typical excess probabilities ξ < 0.05. Most of these predictions however include galaxies in massive groups and clusters, where processes such as dynamical friction and local torques on satellites decrease the signal significantly, as highlighted in Dubois et al (2014).…”

“…This algorithm has not only been used to analyse simulations (e.g. Dubois et al 2014;Welker et al 2014Welker et al , 2018Codis et al 2018;) but has also been successfully applied to real spectroscopic (VIPERS, GAMA) and photometric (COSMOS) surveys on wider redshift ranges (e.g. Malavasi et al 2017;Laigle et al 2018;.…”

“…An important predicted effect of the cosmic web on growing haloes and galaxies was first identified in N-body cosmological simulations (Aubert et al 2004;Aragón-Calvo et al 2007;Hahn et al 2007;Paz et al 2008;Bett & Frenk 2012;Codis et al 2012) and later extended to galaxies in hydrodynamic runs (Hahn et al 2007;Dubois et al 2014;Codis et al 2018). It is the mass-dependent trend of galactic spins to align with nearby filaments, which reveals a strong connection between the complex accretion of material on galactic scales and cosmic flows on extra-galactic scales.…”

Cosmological evolution of orientations of cluster-sized dark matter haloes and their central galaxies in the Horizon-AGN simulation

“…Furthermore, there are many recent studies that report the alignment of clusters over ∼ 100 h −1 Mpc scales, and also between galaxies/clusters and the large-scale structure surrounding them (e.g. Catelan et al 2001;Hirata & Seljak 2004;Patiri et al 2006;Hirata et al 2007;Brunino et al 2007;Blazek et al 2011;Smargon et al 2012;Codis et al 2015;Blazek et al 2015;Chen et al 2016;van Uitert & Joachimi 2017;Okumura et al 2017;Chisari et al 2017;van Uitert & Joachimi 2017;Blazek et al 2017;Osato et al 2018;Piras et al 2018;Codis et al 2018;Chen et al 2019;Durret et al 2019). This raises the possibility that the orientation of DM haloes is imprinted in the large-scale structure in the Universe and BCGs tend to be aligned dynamically toward a particular direction.…”

Testing tidal alignment models for anisotropic correlations of halo ellipticities with N-body simulations

“…The intrinsic alignment (IA) of galaxy images (Heavens et al 2000;Croft & Metzler 2000;Lee & Pen 2000;Catelan et al 2001;Crittenden et al 2001;Hirata & Seljak 2004) (See Troxel & Ishak 2015;Joachimi et al 2015;Kirk et al 2015;Kiessling et al 2015, for reviews) is known to contaminate cosmological parameter estimations from weak lensing surveys, by 5 − 10% (Mandelbaum et al 2006;Hirata et al 2007;Joachimi et al 2011;Singh et al 2015). Precise modeling of the intrinsic alignments (IAs) is thus crucial for the cosmic shear to be a useful cosmological tool (Jing 2002;Smith & Watts 2005;Bridle & King 2007;Zhang 2010;Schneider & Bridle 2010;Blazek et al 2011Blazek et al , 2015Xia et al 2017;Codis et al 2018;Yao et al 2019b,a;Vlah et al 2019;Blazek et al 2019;). On the other hand, less focus has been drawn to the cosmological information IAs encode.…”