Oral Presentation

Probing Missing Baryons: Stacking Compton y-map in All-sky Filamentary Structures.

Author(s): Ting-An Wu (National Taiwan University)

Presenter: Ting-An Wu (National Taiwan University)

In addressing the 'missing baryon problem', simulations indicate that these baryons may reside in the warm-hot intergalactic medium (WHIM) within the filamentary structures between galaxy halos. Leveraging the Planck thermal Sunyaev-Zeldovich effect (tSZ) maps (Compton y-map), we perform an all-sky stacking analysis of about 1.5 million galaxy pairs from over 0.38 million selected galaxies in the Gaia DR3 galaxy candidate catalog.
The redshift of samples from Gaia exhibits high completeness and homogeneity but lower purity. To enhance accuracy, we employ machine learning to construct a new, high-purity redshift catalog trained by redshift and photometry from Gaia, WISE x SuperCOSMOS, and SDSS.
The selected galaxy pairs are in the redshift range 0.09 < z < 0.18, with a median redshift z = 0.13. The median length of galaxy pairs is 25.3 Mpc.
Upon stacking these refined samples, we observe significant detections of the tSZ signal within the filament regions between galaxy pairs. These excess tSZ signals are potentially originated from WHIM in the filaments and carry the information of the baryon fraction.
During the presentation, I will elucidate how we characterize the baryon distribution within the filamentary structures based on the all-sky stacking results.