Atacama Cosmology Telescope: Combined kinematic and thermal Sunyaev-Zel’dovich measurements from BOSS CMASS and LOWZ halos

Abstract

The scattering of cosmic microwave background (CMB) photons off the free-electron gas in galaxies and clusters leaves detectable imprints on high resolution CMB maps: the thermal and kinematic Sunyaev-Zel'dovich effects (tSZ and kSZ respectively). We use combined microwave maps from the Atacama Cosmology Telescope DR5 and Planck in combination with the CMASS (mean redshift hzi ¼ 0.55 and host halo mass hM vir i ¼ 3 × 10 13 M ⊙ ) and LOWZ (hzi ¼ 0.31, hM vir i ¼ 5 × 10 13 M ⊙ ) galaxy catalogs from the Baryon Oscillation Spectroscopic Survey (BOSS DR10 and DR12), to study the gas associated with these galaxy groups. Using individual reconstructed velocities, we perform a stacking analysis and reject the no-kSZ hypothesis at 6.5σ, the highest significance to date. This directly translates into a measurement of the electron number density profile, and thus of the gas density profile. Despite the limited signal to noise, the measurement shows at high significance that the gas density profile is more extended than the dark matter density profile, for any reasonable baryon abundance (formally >90σ for the cosmic baryon abundance). We simultaneously measure the tSZ signal, i.e., the electron thermal pressure profile of the same CMASS objects, and reject the no-tSZ hypothesis at 10σ. We combine tSZ and kSZ measurements to estimate the electron temperature to 20% precision in several aperture bins, and find it comparable to the virial temperature. In a companion paper, we analyze these measurements to constrain the gas thermodynamics and the properties of feedback inside galaxy groups. We present the corresponding LOWZ measurements in this paper, ruling out a null kSZ (tSZ) signal at 2.9 ð13.9Þσ, and leave their interpretation to future work. This paper and the companion paper demonstrate that current CMB experiments can detect and resolve gas profiles in low mass halos and at high redshifts, which are the most sensitive to feedback in galaxy formation and the most difficult to measure any other way. They will be a crucial input to cosmological hydrodynamical simulations, thus improving our understanding of galaxy formation. These precise gas profiles are already sufficient to reduce the main limiting theoretical systematic in galaxy-galaxy lensing: baryonic uncertainties. Future such measurements will thus unleash the statistical power of weak lensing from the Rubin, Euclid and Roman observatories. Our stacking software ThumbStackis publicly available and directly applicable to future Simons Observatory and CMB-S4 data.

Atacama Cosmology Telescope: Modeling the gas thermodynamics in BOSS CMASS galaxies from kinematic and thermal Sunyaev-Zel’dovich measurements

“…The kSZ measurements [8,18] have traced the distribution of free electrons around galaxies using independent measurements of the peculiar velocity from the galaxy overdensity field. Combining CMB data from the Atacama Cosmology Telescope (ACT) with individual velocity estimates from the "constant stellar mass" (CMASS) catalog of the Baryon Oscillation Spectroscopic Survey (BOSS DR10) [19], they showed that the gas density profiles in groups deviate significantly from a "dark matter only" Navarro-Frenk-White profile (NFW) [20] expected in the absence of feedback.…”

“…In this paper, we use the new stacked tSZ and kSZ measurements obtained in a companion paper [18] by cross-correlating the CMASS galaxy catalogs of BOSS DR10 [19] and temperature maps from combined ACT DR5 and Planck data from [44] in the f150 and f090 bands (centered at roughly 150 GHz and 98 GHz, respectively) to constrain the baryonic processes, such as feedback and nonthermal pressure support, and the thermodynamic profiles of the CGM/ICM. Our models include a correction for the contamination of the tSZ signal by the thermal emission of dust from galaxies in our sample, which we estimate from ACT DR5 (f090, f150) and Herschel/H-ATLAS data [45] in the three bands centered at 500 μm (600 GHz), 350 μm (857 GHz), and 250 μm (1200 GHz).…”

“…In this paper and [18], our main interest is instead in the radial dependence of the kSZ and tSZ signals, and particularly the baryon profiles. We focus on the CMASS galaxy sample, for which clustering and galaxy lensing measurements are available, in order to obtain a complete picture of the gas thermodynamics.…”

“…This allows us to constrain the properties of feedback in these halos, and shed new light on the low lensing tension [26]. Because these two pairs of papers focus on different information from the kSZ and tSZ signals, they use different estimators: the pairwise kSZ estimator in [47,48] is particularly suited to measure the velocity correlation function, whereas the stacking with reconstructed velocities of [18] and this work is convenient for measuring the baryon profiles. Overall, these two pairs of papers are complementary, and highlight the wealth of information in joint kSZ and tSZ measurements.…”

The Atacama Cosmology Telescope: Summary of DR4 and DR5 Data Products and Data Access

“…Optimally combining data from the ACT-MBAC, ACTPol, and AdvACT surveys as well as Planck, the DR5 co-added maps cover the same total ∼18,000 deg 2 sky footprint as DR4 but with a full co-added depth of 10 mK CMB ′ over ∼2500 deg 2 . These maps are ideal for producing cluster catalogs, such as in Section 3.9, and are well suited for stacking analyses such as measurements of the tSZ and kinematic Sunyaev-Zel'dovich (kSZ) effects (Amodeo et al 2021;Schaan et al 2021;Calafut et al 2021;Vavagiakis et al 2021), cluster lensing (Madhavacheril et al 2020b), point-source and cluster studies, and Galactic science. Due to the preliminary nature of the s17-s18 data, the DR5 co-added maps are not recommended for precision cosmology.…”