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Description
We obtained Arecibo HI line follow-up observations of 154 of the 2600 galaxies in the Nancay Interstellar Baryons Legacy Extragalactic Survey (NIBLES) sample. These observations are on average four times more sensitive than the original observations at the Nancay Radio Telescope. The main goal of this survey is to characterize the underlying HI properties of the NIBLES galaxies which were undetected or marginally detected at Nancay. Of the Nancay non-detections, 85% were either clearly or marginally detected at Arecibo, while 89% of the Nancay marginal detections were clearly detected. Based on the statistics of the detections relative to g-i color and r-band luminosity (Lr) distribution among our Arecibo observations, we anticipate ~60% of our 867 Nancay non-detections and marginal detections could be detected at the sensitivity of our Arecibo observations. Follow-up observations of our low luminosity (Lr<10^8.5^L_{sun}_) blue sources indicate that they have, on average, more concentrated stellar mass distributions than the Nancay detections in the same luminosity range, suggesting we may be probing galaxies with intrinsically different properties. These follow-up observations enable us to probe HI mass fractions, log(MHI/M*) 0.5dex and 1dex lower, on average, than the NIBLES and ALFALFA surveys respectively.
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