Wang$^{6}$\
    $^1$Australia Telescope National Facility, CSIRO Astronomy and Space Science, PO box 76, Epping, NSW 1710, Australia\
    $^2$SKA South Africa Radio Astronomy Research Group, 3rd Floor, The Park, Park Road, Pinelands, 7405, South Africa\
    $^3$Rhodes University, Department of Physics and Electronics, Rhodes Centre for Radio Astronomy Techniques & Technologies,\
    PO Box 94, Grahamstown, 6140, South Africa\
    $^4$Argelander-Institut für Astronomie, Auf dem Hügel 71, D-53121 Bonn, Germany\
    $^5$University of Groningen, Kapteyn Astronomical Institute, Landleven 12, 9747 AD, Groningen, The Netherlands\
    $^6$Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Astronomical Society,\
    80 Nandan Rd, Shanghai 200030, China\
    $^7$Observatório Nacional, Ministry of Science, Technology, and Innovation, Rio de Janeiro, Brazil\
date: 'Accepted 2014 ???? ?? Received 2014 ???? ??; in original form 2014 January'
title: 'An HI View of Galaxy Conformity: HI-rich Environment around HI-excess Galaxies'
---

galaxies:spiral; intergalactic medium

Introduction
============

Gas accretion is an important process in the evolution of galaxies. Galaxies like the Milky Way would run out of their gas in less than 1 Gyr given their current star formation rate unless their gas reservoir is continuously replenished (Kennicutt 1983). The source of this fresh gas is unknown but the majority is unlikely to be 