H I observations of galaxies in the southern filament of the Virgo Cluster with the Square Kilometre Array Pathfinder KAT-7 and the Westerbork Synthesis Radio Telescope

A. Sorgho, K. Hess, C. Carignan, T. A. Oosterloo

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Abstract

We map the H I distribution of galaxies in a ˜1.5 × 2.5° region located at the virial radius south of the Virgo Cluster using the KAT-7 and the Westerbork Synthesis Radio Telescope interferometers. Because of the different beam sizes of the two telescopes, a similar column density sensitivity of NH I ˜ 1 × 1018 atoms cm- 2 was reached with the two observations over 16.5 km s-1. We pioneer a new approach to combine the observations and take advantage of their sensitivity to both the large- and small-scale structures. Out to an unprecedented extent, we detect an H I tail of ˜60 kpc being stripped off NGC 4424, a peculiar spiral galaxy. The properties of the galaxy, together with the shape of the tail, suggest that NGC 4424 is a post-merger galaxy undergoing ram pressure stripping as it falls towards the centre of the Virgo Cluster. We detect a total of 14 galaxies and three H I clouds lacking optical counterparts. One of the clouds is a new detection with an H I mass of 7 × 107 M⊙ and a strong H I profile with W50 = 73 km s-1. We find that 10 out of the 14 galaxies present H I deficiencies not higher than those of the cluster's late spirals, suggesting that the environmental effects are not more pronounced in the region than elsewhere in the cluster.
Original languageEnglish
Pages (from-to)530-552
Number of pages23
JournalMonthly Notices of the Royal Astronomical Society
Volume464
Issue number1
DOIs
Publication statusPublished - Jan-2017

Keywords

  • techniques: interferometric
  • galaxies: clusters:
  • individual: Virgo
  • galaxies: individual: NGC 4424
  • galaxies: ISM
  • SINGLE-DISH
  • I CONTENT
  • FAST-ALPHA SURVEY
  • ALL-SKY SURVEY
  • SPIRAL GALAXIES
  • STAR-FORMATION
  • RAM PRESSURE
  • NEUTRAL HYDROGEN
  • VIRIAL RADIUS
  • TULLY-FISHER

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