Cyanopolyyne line survey towards high-mass star-forming regions with TMRT

We carried out a cyanopolyyne line survey towards large sample of HMSFRs using the Shanghai Tian Ma 65m Radio Telescope (TMRT). Our consisted 123 targets taken from TMRT C band survey. It included three kinds sources, namely those with detection 6.7 GHz CH3OH maser alone, radio recombination (RRL) and both (hereafter referred to as Maser-only, RRL-only, Maser-RRL respectively). detected HC3N in 38 HC5N 11 HC7N G24.790+0.084, highest rate being found for sources very low RRL-only sources. Their column densities were derived rotational temperature measured NH3 lines. And we constructed fitted far-infrared (FIR) spectral energy distributions. Based on these, derive their dust temperatures, H2 densities, abundances cyanopolyynes relative H2. The rate, density, abundance increase Maser-only decrease This trend is consistent proposed evolutionary under assumption that our Maser-RRL, correspond massive young stellar objects, ultra-compact HII regions, normal classical respectively. Furthermore, statistical analysis integrated intensity density shock-tracing molecules (SiO, H2CO) enabled us find positive correlations between them. suggests may be another tracer shocks, should therefore subject further observations corresponding chemical simulations. results indirectly support idea neutral--neutral reaction C2H2 CN dominant formation pathway HC3N.