Planck 2015 results. XXIII. The thermal Sunyaev-Zeldovich effect--cosmic infrared background correlation (1509.06555v1)

Abstract: We use Planck data to detect the cross-correlation between the thermal Sunyaev-Zeldovich (tSZ) effect and the infrared emission from the galaxies that make up the the cosmic infrared background (CIB). We first perform a stacking analysis towards Planck-confirmed galaxy clusters. We detect infrared emission produced by dusty galaxies inside these clusters and demonstrate that the infrared emission is about 50% more extended than the tSZ effect. Modelling the emission with a Navarro--Frenk--White profile, we find that the radial profile concentration parameter is $c_{500} = 1.00^{+0.18}_{-0.15}$. This indicates that infrared galaxies in the outskirts of clusters have higher infrared flux than cluster-core galaxies. We also study the cross-correlation between tSZ and CIB anisotropies, following three alternative approaches based on power spectrum analyses: (i) using a catalogue of confirmed clusters detected in Planck data; (ii) using an all-sky tSZ map built from Planck frequency maps; and (iii) using cross-spectra between Planck frequency maps. With the three different methods, we detect the tSZ-CIB cross-power spectrum at significance levels of (i) 6 $\sigma$, (ii) 3 $\sigma$, and (iii) 4 $\sigma$. We model the tSZ-CIB cross-correlation signature and compare predictions with the measurements. The amplitude of the cross-correlation relative to the fiducial model is $A_{\rm tSZ-CIB}= 1.2\pm0.3$. This result is consistent with predictions for the tSZ-CIB cross-correlation assuming the best-fit cosmological model from Planck 2015 results along with the tSZ and CIB scaling relations.

• The paper establishes the cross-correlation between the thermal Sunyaev-Zeldovich effect and the cosmic infrared background using stacking analysis on Planck data.
• It models infrared emission with a Navarro–Frenk–White profile, yielding a concentration parameter of c₅₀₀ = 1.00⁺⁰·¹⁸₋₀·₁₅, which indicates more extended emissions beyond cluster cores.
• The measured cross-correlation amplitude of Aₜₛ𝑧-C𝐼𝐵 = 1.2 ± 0.3 supports current cosmological models and informs future high-resolution CMB research.

Overview of the Cross-Correlation Between the Thermal Sunyaev-Zeldovich Effect and Cosmic Infrared Background

The research presented in this paper investigates the cross-correlation between the thermal Sunyaev-Zeldovich (tSZ) effect and the cosmic infrared background (CIB) using data from the Planck satellite. This analysis is crucial because the interaction between these two cosmic phenomena provides insights into the spatial distribution of galaxies and large-scale structural formation in the universe.

Methodology

The authors use Planck data to conduct a stacking analysis targeting confirmed galaxy clusters to detect infrared emissions from galaxies within these clusters. The stacking analysis reveals infrared emissions that are about 50% more extended than the tSZ effect and employs a Navarro–Frenk–White (NFW) profile to model this emission, finding a concentration parameter of $c_{500} = 1.00^{+0.18}_{-0.15}$. This suggests a higher infrared flux from galaxies in the outskirts of clusters versus those in the cluster cores.

The paper also examines the cross-power spectra between tSZ and CIB anisotropies via three methodologies: confirmed clusters, an all-sky tSZ map, and cross-spectra between Planck frequency maps. The tSZ-CIB cross-power spectrum is detected with varying significance: 6$\,\sigma$ for the cluster catalogue, 3$\,\sigma$ for the all-sky map, and 4$\,\sigma$ for the frequency maps. The relative amplitude of the cross-correlation is consistent with predictions derived from the best-fit cosmological model from the Planck 2015 results.

Key Results

• Detection of Infrared Emission: The infrared signal is significant across all approaches, revealing more extended emission than the tSZ signal within clusters, suggesting differential star formation rates.
• Cross-Correlation Analysis: The amplitude of the cross-correlation, measured at $A_{\rm tSZ-CIB} = 1.2 \pm 0.3$, is consistent across multiple methodological approaches and reflects predictions using current cosmological models.
• Cosmological Implications: These findings confirm that infrared galaxies in the outskirts indeed have higher infrared fluxes due to reduced star formation quenching.

Implications and Future Directions

The ability to distinguish and measure the tSZ-CIB cross-correlation allows researchers to refine models of the universe's large-scale structure. The findings impact the understanding of astrophysical processes such as star formation in galaxy clusters and provide constraints on cosmological parameters. Accurate measurements of the tSZ-CIB correlation factor are crucial for determining the kinetic SZ effect and corresponding power spectrum, enhancing our comprehension of reionization epochs.

Future work could expand upon these methodologies by leveraging next-generation cosmic microwave background (CMB) experiments, which promise higher resolution and more precise measurement capabilities. Additionally, further exploration of the differential impact of galaxy environment on star formation rates via cross-correlation studies across different frequency scales and redshift ranges can yield deeper insights into the evolution of cosmic structures and energy distributions.