Ammonia survey of the BGPS sources with the Nanshan  26-m telescope

ABSTRACT We conducted an ammonia survey targeting 217 sources from the Bolocam Galactic Plane Survey v1.0 using the Nanshan 26-m radio telescope, focusing on the $\rm NH_3$(1,1) and (2,2) lines, selecting sources based on the criteria that their 1.1 mm fluxes are greater than 5 Jy and that they are observable with the Nanshan 26-m radio telescope at the Xinjiang Astronomical Observatory. We successfully detected 188 (86.6 per cent) of our sources. These sources span a galactic longitude range of 1.2$^\circ$–192.6$^\circ$ and reside in the local, Perseus, Saggitarius–Carina, Scutum–Centaurus, and Norma spiral arms and between them. Among them, 185 sources exhibit NH$_3$ (1,1) and (2,2) inversion lines, all showing well-defined structural characteristics. Total $\rm NH_3$ column densities vary from 0.12 $\times$ 10$^{15}$ to 15 $\times$ 10$^{15}$ cm$^{-2}$, with para-$\rm NH_3$ fractional abundances averaging 1.8 $\times$ 10$^{-7}$. This study concludes that 82 per cent of our observed sources exhibit star formation activity, evidenced by 22 GHz water maser emission, and 52 per cent are identified as high-mass star formation regions through 6.7 GHz Class II methanol maser detections. Turbulence, reflected in non-thermal velocity dispersion, correlates positively with kinetic temperature, influencing cloud evolution and star formation. These results emphasize the role of turbulence in star formation processes and maser emission as their indicator. We also find a weak negative trend between ammonia column density and galactocentric distance with the 2$\sigma$ significance, potentially linked to Galactic isotope ratio and gas density gradients.