| Description |
Despite of all theoretical speculations and various observational constraints, the nature of the dark matter in the outer Galaxy is still unknown. Herschel-HIFI offers the unique opportunity to detect or set a significant upper limit to a potential component of baryonic matter in the form of cold gas, which is molecular in hydrogen, but does not form CO. Such gas can be potentially be traced through [CII] 150 um and HF J=1-0 absorption against continuum background sources. We propose a set of 7 the brightest outer Galaxy dust continuum sources, for which we will determine the positions of peak emission by PACS mapping. Deep integrations in [CII] and HF towards the 4 brightest peaks in these sources will potentially detect a cold gas component and will, in any case, give significant upper limits to its column density. |
