Ziyang Chen, Drew Jamieson, Eiichiro Komatsu, Alexandre Barreira, Klaus Dolag, R\"udiger Pakmor, Volker Springel

In this work, we show that the statistics of thermal gas pressure \(\langle b_\mathrm{h}P_e\rangle\) is sensitive to both cosmology and galaxy formation model. We find that state-of-the-art hydrodynamical simulations of galaxy formation, Magneticum and MillenniumTNG, predict a larger \(\langle b_\mathrm{h}P_e\rangle\) than that observed at z<0.5 by a factor of 1.05. This can be explained by a lower value of \(\sigma_8\) and \(\Omega_\mathrm{m}\), similar to the so-called "\(S_8\) tension" seen in the gravitational lensing effect. At higher redshift, we find that both simulations are in a modest tension with the existing upper bounds on \(\langle b_\mathrm{h}P_e\rangle\). We also find a significant difference between these simulations, which we attribute to the difference in the galaxy formation models. Therefore, more precise measurements of \(\langle b_\mathrm{h}P_e\rangle\) at z>2 will provide a new test of our understanding of galaxy formation.

Ziyang Chen, Pengjie Zhang, Xiaohu Yang

We carry out a thermal energy census of hot baryons at \(z < 1\), by cross-correlating the \emph{Planck} MILCA y-map with 0.8 million clusters/groups selected from the Yang et.al (2021) catalog. The thermal Sunyaev-Zel'dovich (tSZ) effect around these clusters/groups are reliably obtained, which enables us to make our model constraints based on one-halo (1h) and two-halo (2h) contributions, respectively.

(1)One-halo term

The total measurement S/N of the one-halo term is 63. We constrain the Y-M relation over the halo mass range of \(10^{13}-10^{15} M_\odot/h\), and find \(Y\propto M^{\alpha}\) with \(\alpha= 1.8 \) at z=0.14 (\(\alpha=2.1\) at z=0.75). The hot gas fraction \(f_{\rm gas}\) in clusters/groups monotonically increase with halo mass, where \(f_{\rm gas}\) of a \(10^{14} M_\odot/h\) halo is \(\sim 50\% (25\%\)) of the cosmic mean at z=0.14 (0.75).

(2) Two-halo term

The two-halo term is used to constrain the bias-weighted electron pressure $\langle b_yP_e \rangle$. We find that $\langle b_yP_e \rangle$ (in unit of $\rm meV/cm^3$) increases from $0.24\pm 0.02$ at $z=0.14$ to $0.45\pm 0.02$ at $z=0.75$. These results lead to several implications.

The above results lead to significant suppression of matter and weak lensing power spectrum at small scales. These implications are important for astrophysics and cosmology, and we will further investigate them with improved data and gas modeling.

Ziyang Chen, Pengjie Zhang, Xiaohu Yang, Yi Zheng

Combining galaxy clusters in DESI imaging and the Planck temperature maps, We report a \(5\sigma\) detection of the pairwise kinematic Sunyaev-Zel'dovich (kSZ) effect. The detection is facilitated by both improvements in the data and in the analysis method. The baseline cluster sample, containing the \(1.2\times 10^5\) richest galaxy clusters of typical mass \(\sim 10^{14} M_{\odot}/h\) at typical redshift \(0.2\sim0.5\), rules out the null hypothesis at $5\sigma$. When fitting with a pairwise kSZ template from simulations, the signal is detected at \(4.7\sigma\) and the average optical depth is constrained as \(\bar{\tau}_e=(1.66\pm 0.35)\times 10^{-4}\).