View Full Version : A Thermometer for Galaxy Cluster Gas Temperatures

2018-Mar-12, 03:57 PM
The Sunyaev-Zeldovich Effect, hereafter, SZ, occurs when hot gas interacts with the CMB background. Normal Compton scattering occurs when energetic photons collide with electrons, lose energy, are redshifted, and kick up the speeds of the collided electrons. Inverse Compton scattering occurs when the opposite exchange happens, particularly high speed electrons interact with photons to boost the photon energy while simultaneously dropping electron kinetic energy. Sunyaev predicted a "shadow " of the CMB due to it's interaction with hot gas in galaxy clusters, and it's there.
The authors find two components to the SZ effect, kinetic due to cluster motion, and the use of the relativistic component, rSZ, to calibrate the temperature of gas in clusters and find a match to the existing X-ray estimates. Kind of like sticking a thermometer in from light years away. Neat trick. SEE:https://arxiv.org/abs/1803.03277


2018-Mar-12, 09:01 PM
Might this partially explain the Boomerang's temperature being lower than the 2.7K background, or is expansion-only the definitive answer?