The MillenniumTNG Project: Intrinsic alignments of galaxies and halos

Delgado, Ana Maria; Hadzhiyska, Boryana; Bose, Sownak; Springel, Volker; Hernquist, Lars; Barrera, Monica; Pakmor, Rüdiger; Ferlito, Fulvio; Kannan, Rahul; Hernández-Aguayo, César; White, Simon DM; Frenk, Carlos

Abstract

The intrinsic alignment (IA) of observed galaxy shapes with the underlying cosmic web is a source of contamination in weak lensing surveys. Sensitive methods to identify the IA signal will therefore need to be included in the upcoming weak lensing analysis pipelines. Hydrodynamical cosmological simulations allow us to directly measure the intrinsic ellipticities of galaxies and thus provide a powerful approach to predict and understand the IA signal. Here we employ the novel, large-volume hydrodynamical simulation MTNG740, a product of the MillenniumTNG (MTNG) project, to study the IA of galaxies. We measure the projected correlation functions between the intrinsic shape/shear of galaxies and various tracers of large-scale structure, w+g, w+m, w++ over the radial range rp ∈ [0.02, 200] h−1Mpc and at redshifts z = 0.0, 0.5 and 1.0. We detect significant signal-to-noise IA signals with the density field for both elliptical and spiral galaxies. We also find significant intrinsic shear-shear correlations for ellipticals. We further examine correlations of the intrinsic shape of galaxies with the local tidal field. Here we find a significant IA signal for elliptical galaxies assuming a linear model. We also detect a weak IA signal for spiral galaxies under a quadratic tidal torquing model. Lastly, we measure the alignment between central galaxies and their host dark-matter halos, finding small to moderate misalignments between their principal axes that decline with halo mass.

Citation

Delgado, A. M., Hadzhiyska, B., Bose, S., Springel, V., Hernquist, L., Barrera, M., Pakmor, R., Ferlito, F., Kannan, R., Hernández-Aguayo, C., White, S. D., & Frenk, C. (2023). The MillenniumTNG Project: Intrinsic alignments of galaxies and halos. Monthly Notices of the Royal Astronomical Society, 523(4), 5899–5914. https://doi.org/10.1093/mnras/stad1781

• Journal Article Type: Article
• Acceptance Date: Apr 24, 2023
• Online Publication Date: Jun 16, 2023
• Publication Date: Aug 4, 2023
• Deposit Date: Jun 23, 2023
• Publicly Available Date: Jun 23, 2023
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Royal Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 523
• Issue: 4
• Pages: 5899–5914
• DOI: https://doi.org/10.1093/mnras/stad1781
• Public URL: https://durham-repository.worktribe.com/output/1170918
• Related Public URLs: https://doi.org/10.48550/arXiv.2304.12346