Observing molecular clouds in halo dark clusters through absorption lines

In addition to Massive Astrophysical Compact Halo Objects (MACHOs), as detected by microlensing, cold molecular clouds (mainly ofH 2) may well contribute substantially to the galactic halo dark matter. Here, we argue that the existence of such halo clouds can be inferred from the observation of absorption lines (due to heavy molecules located in the clouds themselves) towards stars of the Large Magellanic Cloud, which lie very close, within ˜1', to a previously microlensed one.