We present the first detection of CS in the Antennae galaxies towards the NGC 4038 nucleus, as well as the first detections of two high-J (5-4 and 7-6) CS lines in the center of M 82. The CS(7-6) line in M 82 shows a profile that is surprisingly different to those of other low-J CS transitions we observed. This implies the presence of a separate, denser and warmer molecular gas component. The derived physical properties and the likely location of the CS(7-6) emission suggests an association with the supershell in the centre of M 82.
@article{arxiv.0808.2815,
title = {Tracing high density gas in M 82 and NGC 4038},
author = {E. Bayet and C. Lintott and S. Viti and J. Martín-Pintado and S. Martín and D. A. Williams and J. M. C. Rawlings},
journal= {arXiv preprint arXiv:0808.2815},
year = {2009}
}