Abstract
The study of the molecular gas is fundamental for the understanding of the highly enshrouded, compact nuclear regions in galaxies, as well as the on- set and evolution of star formation and the growth of supermassive black holes. Unbiased extragalactic molecular line surveys at mm wavelengths are mandatory to detect many species and identify those that provide the best information about the physical properties around the nuclear regions. The instantaneous bandwidth of 37 GHz covering frequencies from 73 to 111 GHz of the RSR at the 32m-Large Millimeter Telescope Alfonso Serrano (LMT, Sierra la Negra, Mexico), allows the simultaneous detection of a large number of molecular species and eliminates many systematic problems as varying pointing or calibration problems present in receivers with shorter coverage. We present high signal to noise millimeter spectra of a sample of 23 galaxies spanning a large range in infrared luminosities, nuclear activity, metallicity and morphological types. We started the analysis of their cold and dense molecular content based on molecular line ratios diagnostic diagrams and empirical relations between molecular line intensities and the properties of the host galaxies like nuclear activity, star forming rate, and metallicity.
