The relationship of dense molecular gas and HI/H₂ gas in a MALATANG galaxy, NGC 6946

We present the results from our comparisons of HCN and HCO+ (J=4-3) with HI and $H_2$ gas in NGC 6946, a sample from a mapping study of the dense molecular gas in the strongest star-forming galaxies (MALATANG). The MALATANG is one of the JCMT legacy surveys on the nearest 23 IR-brightest galaxies beyond the Local Group, which aims to study the relations of dense molecular gas with more general cool gas such as atomic and molecular hydrogen gas, and star formation properties in active galaxies. In this work, we particularly focus on the comparisons between the JCMT HCN/HCO+ (J=4-3) data and the THINGS HI/the NRO CO (J=1-0) data. We probe the dense molecular gas mass as a function of HI and $H_2$ mass in different locations in the central ${\sim}1.5kpc^2$ region. We discuss how the excess/deficit of $HI/H_2$ or total cool gas ($HI+H_2$) mass controls the presence and/or the fraction of dense molecular gas.