An HI view of galaxy conformity: HI-rich environment around HI-excess galaxies.

Using data taken as part of the Bluedisk project, we study the connection between neutral hydrogen (H I) in the environment of spiral galaxies and that in the galaxies themselves. We measure the total H I mass present in the environment in a statistical way by studying the distribution of noise peaks in the H I data cubes obtained for 40 galaxies observed with Westerbork Synthesis Radio Telescope. We find that galaxies whose H I mass fraction is high relative to standard scaling relations have an excess H I 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 I data. These clumps may be hosted by small satellite galaxies and/or be the high-density peaks of a more diffuse gas distribution in the intergalactic medium. We interpret this result as an indication for a picture in which the [Math Processing Error]-rich central galaxies accrete gas from an extended gas reservoir present in their environment. [ABSTRACT FROM AUTHOR]