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abstract: 'Using data taken as part of the Bluedisk project we study the connection between neutral hydrogen ([[H]{}[<span style="font-variant:small-caps;">i</span> ]{}]{}) in the environment of spiral galaxies and that in the galaxies themselves. We measure the total [[H]{}[<span style="font-variant:small-caps;">i</span> ]{}]{}mass present in the environment in a statistical way by studying the distribution of noise peaks in the [[H]{}[<span style="font-variant:small-caps;">i</span> ]{}]{}data cubes obtained for 40 galaxies observed with WSRT. We find that galaxies whose [[H]{}[<span style="font-variant:small-caps;">i</span> ]{}]{}mass fraction is high relative to standard scaling relations have an excess [[H]{}[<span style="font-variant:small-caps;">i</span> ]{}]{}mass in the surrounding environment as well. Gas in the environment consists of gas clumps which are individually below the detection limit of our [[H]{}[<span style="font-variant:small-caps;">i</span> ]{}]{}data. These clumps may be hosted by small satellite galaxies and$\slash$or be the high-density peaks of a more diffuse gas distribution in the inter-galactic medium. We interpret this result as an indication for a picture in which the ${\rm H}{\textsc i}$-rich central galaxies accrete gas from an extended gas reservoir present in their environment.'
author:
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    Jing Wang$^{1}$[^1], Paolo Serra$^{1}$, Gyula I. G. Józsa$^{2,3,4}$, Bärbel Koribalski$^{1}$,\
    Thijs van der Hulst$^{5}$, Peter Kamphuis$^{1}$, Cheng Li$^{6}$ , Jian Fu$^{6}$, Ting Xiao$^{6}$,\
    Roderik Overzier$^{7}$, Mark Wieringa$^{1}$, Enci 