| 21st of January 2019 |
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| ASKAP images of the NGC 7232 galaxy group (Part 1) |
| by Karen Lee-Waddell |
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Lee-Waddell et al. (2019) have used the Australian Square Kilometre
Array Pathfinder (ASKAP) to detect HI in the NGC 7232 galaxy group.
The observations were taken on behalf of WALLABY (the Widefield ASKAP
L-band Legacy All-sky Blind surveY) using 12 ASKAP antennas during
various commissioning and Early Science phases of the array. The left
panel shows circles representing the beams across ASKAP’s wide field
of view, which are colour-coded based on each 36-beam footprint that
can be simultaneously observed. Footprint A (red) is alternated with
footprint B (blue) to provide more even sensitivity across the field.
The rotated footprint (green) was observed during a couple of nights
to test optimization based on the electronics of the Phased Array
Feeds (PAFs).
The right panel shows ASKAP total HI intensity contours (white)
obtained from combining 150 hours of data from the central region of
ASKAP beams. These high resolution ASKAP observations are able to
spatially resolve several gas-rich galaxies. For comparison,
single-dish HIPASS total intensity contours are shown in yellow.
Within the region analyzed, ASKAP detects 17 HI sources. Eleven of
these detections are identified with stellar counterparts, of which
five are newly resolved HI galaxies (indicated by the blue
diamonds). The other six HI detections (circled in green) are likely
tidal debris associated with NGC 7232/3 triplet.
Reference: K. Lee-Waddell, B.S. Koribalski, T. Westmeier, A. Elagali, B.-Q. For, D. Kleiner, J.P. Madrid, A. Popping, T. N. Reynolds, J. Rhee, P. Serra, L. Shao, L. Staveley-Smith, J. Wang, M.T. Whiting, O.I. Wong, J.R. Allison, S. Bhandari, J.D. Collier, G. Heald, J. Marvil, S.M. Ord, 2019, MNRAS, in press (arXiv:1901.00241) |