Survey Reveals Discrete Sources in Galaxy Clusters, Impacting Mass Estimates

A recent survey using the MUSTANG2 instrument on the Green Bank Telescope has identified 24 discrete sources in 243 galaxy clusters selected via the thermal Sunyaev-Zeldovich (tSZ) effect. The survey, conducted at 90 GHz, achieved a detection limit of 1 mJy at the center of each cluster. Of the detected sources, 18 correspond to known radio sources, with five showing significant variability. The remaining sources have no clear counterparts at other wavelengths.

The findings indicate that these sources can potentially bias mass estimates of galaxy clusters, which are crucial for understanding the large-scale structure of the universe. The study compared the results to the Websky simulation, which matched observations at the clusters' centers but not further out. Sources located over 104 arcseconds from a cluster's center can bias the tSZ signal by more than 50% in some cases. When averaged over the entire cluster population, this effect is smaller but still significant, ranging from 1 to 2%.

Interestingly, the survey discovered an unexpected enhancement of source counts in the outer regions of the clusters and fewer sources than expected in the centers. This contrasts with previous measurements and simulations, suggesting that the distribution of sources in galaxy clusters may be more complex than previously thought.

These findings have important implications for future surveys and the accuracy of galaxy cluster mass estimates, which are essential for cosmological studies.

The paper, titled "Sensitive 3mm Imaging of Discrete Sources in the Fields of tSZ-Selected Galaxy Clusters," was authored by Simon R. Dicker, Karen Perez Sarmiento, Brian Mason, Tanay Bhandarkar, Mark J. Devlin, Luca Di Mascolo, Saianeesh Haridas, Matt Hilton, Mathew Madhavacheril, Emily Moravec, Tony Mroczkowski, John Orlowski-Scherer, Charles Romero, Craig L. Sarazin, and Jonathan Sievers .