PI: Shan Huang, Cornell University, email@example.com
Address: Astronomy Department, 518 Space Sciences Building, Cornell University, Ithaca, NY 14853, USA
CoI: Martha Haynes, Cornell University
CoI: Riccardo Giovanelli, Cornell University
Title: Massive Gas-Rich Underluminous Disks in the ALFALFA Survey
Abstract: We propose to obtain narrow-band H(alpha) and R-band images for a sample of 26 of the most massive gas-rich (HI mass > 10^10 M_\odot) galaxies detected by the ongoing Arecibo Legacy Fast ALFA (ALFALFA) survey. Besides possessing exceptionally massive HI disks, our targets are chosen to have high ratios of HI to stellar mass and thus are relatively underluminous at optical wavelengths; in fact, 16/26 have M_HI > M_*. Deep KPNO 2.1m H(alpha) images will localize the star formation activity in their extended disks as well as trace diffuse H(alpha) emission from ionizing photons which are unable to escape their huge gas reservoirs. This study is part of a coordinated effort to assemble multiwavelength data (UV, optical, IR/FIR, CO, HI synthesis maps) for a sufficiently-sized sample of HI-selected massive galaxies that we can explore the interrelationships of their star formation, gas, dust and dark matter components and determine their evolutionary states. In particular, the FUV to H(alpha) flux ratio will help us to constrain the star formation history, and the shape and upper mass cutoff of the IMF. These objects represent the present day counterparts of the populations which are likely to dominate future studies of HI in galaxies at high redshift with the Square Kilometre Array.
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