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Interpreting Sunyaev–Zel’dovich observations with MillenniumTNG: mass and environment scaling relations

Hadzhiyska, Boryana; Ferraro, Simone; Pakmor, Rüdiger; Bose, Sownak; Delgado, Ana Maria; Hernández-Aguayo, César; Kannan, Rahul; Springel, Volker; White, Simon D M; Hernquist, Lars

Interpreting Sunyaev–Zel’dovich observations with MillenniumTNG: mass and environment scaling relations Thumbnail


Boryana Hadzhiyska

Simone Ferraro

Rüdiger Pakmor

Ana Maria Delgado

César Hernández-Aguayo

Rahul Kannan

Volker Springel

Simon D M White

Lars Hernquist


Sunyaev–Zel’dovich (SZ) measurements can dramatically improve our understanding of the intergalactic medium and the role of feedback processes in galaxy formation, allowing us to calibrate important astrophysical systematics in cosmological constraints from weak lensing galaxy clustering surveys. However, the signal is only measured in a two-dimensional projection, and its correct interpretation relies on understanding the connection between observable quantities and the underlying intrinsic properties of the gas, in addition to the relation between the gas and the underlying matter distribution. One way to address these challenges is through the use of hydrodynamical simulations such as the high-resolution, large-volume MillenniumTNG suite. We find that measurements of the optical depth, τ , and the Compton-y parameter, Y, receive large line-of-sight contributions that can be removed effectively by applying a compensated aperture photometry filter. In contrast with other τ probes (e.g. X-rays and fast radio bursts), the kinematic SZ-inferred τ receives most of its signal from a confined cylindrical region around the halo due to the velocity decorrelation along the line of sight. Additionally, we perform fits to the Y–M and τ–M scaling relations and report best-fitting parameters adopting the smoothly broken power law formalism. We note that subgrid physics modelling can broaden the error bar on these by 30 per cent for intermediate-mass haloes (∼1013 M). The scatter of the scaling relations can
be captured by an intrinsic dependence on concentration and an extrinsic dependence on tidal shear. Finally, we comment on the
effect of using galaxies rather than haloes in observations, which can bias the inferred profiles by ∼20 per cent for L∗ galaxies.


Hadzhiyska, B., Ferraro, S., Pakmor, R., Bose, S., Delgado, A. M., Hernández-Aguayo, C., …Hernquist, L. (2023). Interpreting Sunyaev–Zel’dovich observations with MillenniumTNG: mass and environment scaling relations. Monthly Notices of the Royal Astronomical Society, 526(1), 369–382.

Journal Article Type Article
Acceptance Date Sep 7, 2023
Online Publication Date Sep 12, 2023
Publication Date 2023-11
Deposit Date Feb 1, 2024
Publicly Available Date Feb 1, 2024
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 526
Issue 1
Pages 369–382
Public URL


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