| Description |
We propose to obtain the PACS and SPIRE scan maps of a sample of 34 exceptionally gas-rich galaxies extracted from the ALFALFA extragalactic HI survey. These very HIgh HI mass (HIghMass) galaxies have HI masses > 10^10 Msun and are also very gas-rich for their stellar masses; 17/34 have M_HI>M_star. Are they in an arrested stage of evolution or do their huge HI disks, evident in our HI synthesis maps, result from recent baryon accretion? In combination with the HI synthesis maps (EVLA, GMRT, WSRT), GALEX UV, Halpha, optical broadband and CO studies, FIR/submm maps will cover a critical wavelength range of the dust emission spectral energy distribution and will allow us to determine the dust masses, temperatures and grain size distributions so that we can explore the interplay between the dust, stellar, gas and dark matter components within each galaxy and identify the dust variation trends within the HIghMass sample. In particular, Herschel observations will help us to (1) explore the unique dust behavior in the HIghMass galaxies and map the extent of the cold dust disk; (2) test the origin and evolutionary stage of them and infer molecular masses via the dust to gas ratio; (3) probe the dust-obscured star formation and study the dust heating mechanisms in their extended massive HI disks. Identified first as a class only by ALFALFA, the HIghMass galaxies represent the local counterparts of the populations which are likely to dominate future studies of HI at higher redshift with the Square Kilometer Array. |
