Speaker
Description
Baryonic matter only accounts for 5% of the mass-energy density of our Universe, where the other 95% is shared between dark energy and dark matter. About half of these baryons are currently undetected, and this discrepancy between predicted and observed baryons is known as the “missing baryon” problem. Cosmological simulations predict that a significant fraction of the missing baryons could reside in the form of the warm–hot intergalactic medium (WHIM) trapped inside large scale structures that constitute the cosmic web. Thus, the characterization of the WHIM is a crucial piece of the missing baryon puzzle. Since the baryons reside in a low density, low temperature state, they are difficult to observe.
A useful tool to probe the missing baryons is the Sunyaev-Zel’dovich effect (SZe), an anisotropic spectral distortion of the cosmic microwave background (CMB), caused by the inverse Compton scattering between the hot electrons in galaxy clusters or filaments and the low energy photons of the CMB. This effect has been extensively used by Planck to study clusters and few filament candidates, but at a low resolution of ~10 arcminutes. More recent ground-based CMB experiments like Atacama Cosmology Telescope (ACT) and South Pole Telescope (SPT) have enabled the study of galaxy clusters at arcminute scales. However, only few observations of individual cosmic filaments exist because of their extremely faint SZe footprint. These single detections are limited to multiple cluster systems, in which the filament is compressed and heated as the clusters gravitate into each other, increasing the signal.
In this contribution we present results on the detection of hot gas outside galaxy clusters obtained with the latest high resolution (1.65´), high sensitivity Compton-y maps from ACT. We consider a set of candidate double cluster systems extracted from a preliminary ACT-DR6 catalog of blindly detected clusters to study their general properties through stacking. This sample in focuses on short filaments with a projected length Lfil< 10 Mpc and typical halo mass M500 ~ 2e14 m_sun. Additionally, we study individual pairs of clusters to identify promising candidates for follow-up observations using high resolution millimeter cameras or X-ray satellites.
| Would you be interested in presenting a poster if the conference is oversubcribed? | Yes |
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