Anomalous absorption in Cosmic H2CS molecule

Absorption against the Cosmic Microwave Background (CMB), called the anomalous absorption, is an unusual phenomenon. The transition 1₁₁-1₁₀ at 4.829 GHz of formaldehyde (H₂CO) was the first one showing the anomalous absorption. The c-C₃H₂ is the second molecule showing anomalous absorption through its transition 2₂₀-2₁₁ at 21.590 GHz. Structure of thioformaldehyde (H₂CS) is very similar to that of the H₂CO. Therefore, we have investigated about the physical conditions under which the transition 1₁₁-1₁₀ at 1.0465 GHz of H₂CS would be found in anomalous absorption in cool cosmic objects. As in case of H₂CO, the anomalous absorption of 1₁₁-1₁₀ of H₂CS is found sensitive to the relative collisional rates and it requires that the collisional rate for the transition 1₁₁-2₁₁ must be smaller than that for the transition 1₁₀-2₁₂.