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We aim at characterising dense cores in the clustered environments associatedwith massive star-forming regions. For this, we present an uniform analysis ofVLA NH3(1,1) and (2,2) observations towards a sample of 15 massive star-formingregions, where we identify a total of 73 cores, classify them as protostellar,quiescent starless, or perturbed starless, and derive some physical properties.The average sizes and ammonia column densities are 0.06 pc and 10^15 cm^-2,respectively, with no significant differences between the starless andprotostellar cores, while the linewidth and rotational temperature of quiescentstarless cores are smaller, 1.0 km/s and 16 K, than those of protostellar (1.8km/s, 21 K), and perturbed starless (1.4 km/s, 19 K) cores. Such linewidths andtemperatures for these quiescent starless cores in the surroundings of massivestars are still significantly larger than the typical values measured instarless cores of low-mass star-forming regions, implying an importantnon-thermal component. We confirm at high angular resolutions the correlationspreviously found with single-dish telescopes between the linewidth, thetemperature of the cores, and the bolometric luminosity. In addition, we find acorrelation between the temperature of each core and the incident flux from themost massive star in the cluster, suggesting that the large temperaturesmeasured in the starless cores of our sample could be due to heating from thenearby massive star. A simple virial equilibrium analysis seems to suggest ascenario of a self-similar, self-graviting, turbulent, virialised hierarchy ofstructures from clumps (0.1-10 pc) to cores (0.05 pc). A closer inspection ofthe dynamical state taking into account external pressure effects, reveal thatrelatively strong magnetic field support may be needed to stabilise the cores,or that they are unstable and thus on the verge of collapse.

Properties of dense cores in clustered massive star-forming regions at high angular resolution