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1. Mass proxy quality of massive halo properties in the illustrisTNG and flamingo simulations: I. Hot gas

   https://doi.org/10.1093/mnras/staf1665  

   Aljamal, Eddie; Evrard, August E; Farahi, Arya; Pillepich, Annalisa; Nelson, Dylan; Schaye, Joop; Schaller, Matthieu; Braspenning, Joey (October 2025, Monthly Notices of the Royal Astronomical Society)

   ABSTRACT We examine scale and redshift dependence of mass–property relations (MPRs) for five hot gas properties of two large group- bservationsand cluster-scale halo samples realized by the Illustris tng, TNG-Cluster, and FLAMINGO cosmological hydrodynamical simulations. For intrinsic properties of (i) hot gas mass ($$M_{\rm gas}$$), (ii) spectroscopic-like temperature ($$T_{\rm sl}$$), (iii) soft-band X-ray luminosity ($$L_{\rm X}$$), and (iv) X-ray ($$Y_{\rm X}$$), and (v) Sunyaev–Zel’dovich ($$Y_{\rm SZ}$$) thermal energies, we use MPR parameters to infer mass proxy quality (MPQ) – the implied scatter in total halo mass conditioned on a property – for haloes with $$M_{\rm 500c}\ge 10^{13}\, {\rm M}_\odot$$ at redshifts, $$z \in \lbrace 0, 0.5, 1, 2\rbrace$$. We find: (1) in general, scaling relation slopes and covariance display moderate to strong dependence on halo mass, with redshift dependence secondary; (2) for haloes with $$M_{\rm 500c}> 10^{14}\, {\rm M}_\odot$$, scalings of $$M_{\rm gas}$$ and $$Y_{\rm SZ}$$ simplify toward self-similar slope and constant intrinsic scatter (5 and 10 per cent, respectively) nearly independent of scale, making both measures ideal for cluster finding and characterization to $z=2$; (3) halo mass-conditioned likelihoods of hot gas mass and thermal energy closely follow a lognormal form; and (4) despite normalization differences up to 0.4 dex between the two simulations, higher order scaling features such as slopes and property covariance show much better agreement. Slopes show appreciable redshift dependence at the group scale, while redshift dependence of the scatter is exhibited by low-mass flamingo haloes only; (5) property correlations are largely consistent between the simulations, with values that mainly agree with existing empirical measurements. We close with a literature survey placing our MPR slopes and intrinsic scatter estimates into community context. 

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2. Improving Cosmological Constraints from Galaxy Cluster Number Counts with CMB-cluster-lensing Data: Results from the SPT-SZ Survey and Forecasts for the Future

   https://doi.org/10.3847/1538-4357/ac6a55  

   Chaubal, P. S.; Reichardt, C. L.; Gupta, N.; Ansarinejad, B.; Aylor, K.; Balkenhol, L.; Baxter, E. J.; Bianchini, F.; Benson, B. A.; Bleem, L. E.; et al (June 2022, The Astrophysical Journal)

   Abstract We show the improvement to cosmological constraints from galaxy cluster surveys with the addition of cosmic microwave background (CMB)-cluster lensing data. We explore the cosmological implications of adding mass information from the 3.1 σ detection of gravitational lensing of the CMB by galaxy clusters to the Sunyaev–Zel’dovich (SZ) selected galaxy cluster sample from the 2500 deg 2 SPT-SZ survey and targeted optical and X-ray follow-up data. In the ΛCDM model, the combination of the cluster sample with the Planck power spectrum measurements prefers σ 8 Ω m / 0.3 0.5 = 0.831 ± 0.020 . Adding the cluster data reduces the uncertainty on this quantity by a factor of 1.4, which is unchanged whether the 3.1 σ CMB-cluster lensing measurement is included or not. We then forecast the impact of CMB-cluster lensing measurements with future cluster catalogs. Adding CMB-cluster lensing measurements to the SZ cluster catalog of the ongoing SPT-3G survey is expected to improve the expected constraint on the dark energy equation of state w by a factor of 1.3 to σ ( w ) = 0.19. We find the largest improvements from CMB-cluster lensing measurements to be for σ 8 , where adding CMB-cluster lensing data to the cluster number counts reduces the expected uncertainty on σ 8 by respective factors of 2.4 and 3.6 for SPT-3G and CMB-S4. 

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3. ACT-DR5 Sunyaev-Zel’dovich clusters: Weak lensing mass calibration with KiDS

   https://doi.org/10.1051/0004-6361/202346712  

   Robertson, Naomi Clare; Sifón, Cristóbal; Asgari, Marika; Battaglia, Nicholas; Bilicki, Maciej; Richard_Bond, John; Devlin, Mark J; Dunkley, Jo; Giblin, Benjamin; Heymans, Catherine; et al (January 2024, Astronomy & Astrophysics)

   We present Weak Gravitational Lensing measurements of a sample of 157 clusters within the Kilo Degree Survey (KiDS), detected with a > 5σthermal Sunyaev-Zel’dovich (SZ) signal by the Atacama Cosmology Telescope (ACT). Using a halo-model approach, we constrained the average total cluster mass,M_WL, accounting for the ACT cluster selection function of the full sample. We find that the SZ cluster mass estimateM_SZ, which was calibrated using X-ray observations, is biased withM_SZ/M_WL = (1 − b_SZ) = 0.65 ± 0.05. Separating the sample into six mass bins, we find no evidence of a strong mass dependency for the mass bias, (1 − b_SZ). Adopting this ACT-KiDS SZ mass calibration would bring thePlanckSZ cluster count into agreement with the counts expected from thePlanckcosmic microwave background ΛCDM cosmological model, although it should be noted that the cluster sample considered in this work has a lower average massM_SZ, uncor = 3.64 × 10¹⁴ M_⊙compared to thePlanckcluster sample which has an average mass in the rangeM_SZ, uncor = (5.5 − 8.5)×10¹⁴ M_⊙, depending on the sub-sample used. 

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4. The mass and galaxy distribution around SZ-selected clusters

   https://doi.org/10.1093/mnras/stab2505  

   Shin, T; Jain, B; Adhikari, S; Baxter, E J; Chang, C; Pandey, S; Salcedo, A; Weinberg, D H; Amsellem, A; Battaglia, N; et al (September 2021, Monthly Notices of the Royal Astronomical Society)

   null (Ed.)

   ABSTRACT We present measurements of the radial profiles of the mass and galaxy number density around Sunyaev–Zel’dovich (SZ)-selected clusters using both weak lensing and galaxy counts. The clusters are selected from the Atacama Cosmology Telescope Data Release 5 and the galaxies from the Dark Energy Survey Year 3 data set. With signal-to-noise ratio of 62 (45) for galaxy (weak lensing) profiles over scales of about 0.2–20 h−1 Mpc, these are the highest precision measurements for SZ-selected clusters to date. Because SZ selection closely approximates mass selection, these measurements enable several tests of theoretical models of the mass and light distribution around clusters. Our main findings are: (1) The splashback feature is detected at a consistent location in both the mass and galaxy profiles and its location is consistent with predictions of cold dark matter N-body simulations. (2) The full mass profile is also consistent with the simulations. (3) The shapes of the galaxy and lensing profiles are remarkably similar for our sample over the entire range of scales, from well inside the cluster halo to the quasilinear regime. We measure the dependence of the profile shapes on the galaxy sample, redshift, and cluster mass. We extend the Diemer & Kravtsov model for the cluster profiles to the linear regime using perturbation theory and show that it provides a good match to the measured profiles. We also compare the measured profiles to predictions of the standard halo model and simulations that include hydrodynamics. Applications of these results to cluster mass estimation, cosmology, and astrophysics are discussed. 

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5. Cosmological shocks around galaxy clusters: a coherent investigation with DES, SPT, and ACT

   https://doi.org/10.1093/mnras/stad3726  

   Anbajagane, D; Chang, C; Baxter, E J; Charney, S; Lokken, M; Aguena, M; Allam, S; Alves, O; Amon, A; An, R; et al (November 2023, Monthly Notices of the Royal Astronomical Society)

   ABSTRACT We search for signatures of cosmological shocks in gas pressure profiles of galaxy clusters using the cluster catalogues from three surveys: the Dark Energy Survey (DES) Year 3, the South Pole Telescope (SPT) SZ survey, and the Atacama Cosmology Telescope (ACT) data releases 4, 5, and 6, and using thermal Sunyaev–Zeldovich (SZ) maps from SPT and ACT. The combined cluster sample contains around 105 clusters with mass and redshift ranges $$10^{13.7} \lt M_{\rm 200m}/\, {\rm M}_\odot \lt 10^{15.5}$$ and 0.1 < z < 2, and the total sky coverage of the maps is $$\approx 15\, 000 \deg ^2$$. We find a clear pressure deficit at R/R200m ≈ 1.1 in SZ profiles around both ACT and SPT clusters, estimated at 6σ significance, which is qualitatively consistent with a shock-induced thermal non-equilibrium between electrons and ions. The feature is not as clearly determined in profiles around DES clusters. We verify that measurements using SPT or ACT maps are consistent across all scales, including in the deficit feature. The SZ profiles of optically selected and SZ-selected clusters are also consistent for higher mass clusters. Those of less massive, optically selected clusters are suppressed on small scales by factors of 2–5 compared to predictions, and we discuss possible interpretations of this behaviour. An oriented stacking of clusters – where the orientation is inferred from the SZ image, the brightest cluster galaxy, or the surrounding large-scale structure measured using galaxy catalogues – shows the normalization of the one-halo and two-halo terms vary with orientation. Finally, the location of the pressure deficit feature is statistically consistent with existing estimates of the splashback radius. 

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