WALLABY early science - I. The NGC 7162 galaxy group

TY - JOUR

T1 - WALLABY early science - I. The NGC 7162 galaxy group

AU - Reynolds, T. N.

AU - Westmeier, T.

AU - Staveley-Smith, L.

AU - Elagali, A.

AU - For, B.-Q.

AU - Kleiner, Dane

AU - Koribalski, B. S.

AU - Lee-Waddell, K.

AU - Madrid, J. P.

AU - Popping, A.

AU - Rhee, J.

AU - Whiting, Matthew

AU - Wong, O. I.

AU - Davies, L. J. M.

AU - Driver, S.

AU - Robotham, A.

AU - Allison, J. R.

AU - Bekiaris, G.

AU - Collier, J. D.

AU - Heald, G.

AU - Meyer, M.

AU - Chippendale, A. P.

AU - MacLeod, A.

AU - Voronkov, M. A.

PY - 2019/1/21

Y1 - 2019/1/21

N2 - We present Widefield ASKAP L-band Legacy All-sky Blind Survey (WALLABY) early science results from the Australian Square Kilometre Array Pathfinder (ASKAP) observations of the NGC 7162 galaxy group. We use archival HIPASS and Australia Telescope Compact Array (ATCA) observations of this group to validate the new ASKAP data and the data reduction pipeline ASKAP SOFT. We detect six galaxies in the neutral hydrogen (H I) 21-cm line, expanding the NGC 7162 group membership from four to seven galaxies. Two of the new detections are also the first H I detections of the dwarf galaxies, AM 2159-434 and GALEXASC J220338.65-431128.7, for which we have measured velocities of cz = 2558 and cz = 2727 km s-1, respectively. We confirm that there is extended H I emission around NGC 7162 possibly due to past interactions in the group as indicated by the 40° offset between the kinematic and morphological major axes for NGC 7162A, and its H I richness. Taking advantage of the increased resolution (factor of ˜1.5) of the ASKAP data over archival ATCA observations, we fit a tilted ring model and use envelope tracing to determine the galaxies' rotation curves. Using these we estimate the dynamical masses and find, as expected, high dark matter fractions of fDM ˜ 0.81-0.95 for all group members. The ASKAP data are publicly available.

AB - We present Widefield ASKAP L-band Legacy All-sky Blind Survey (WALLABY) early science results from the Australian Square Kilometre Array Pathfinder (ASKAP) observations of the NGC 7162 galaxy group. We use archival HIPASS and Australia Telescope Compact Array (ATCA) observations of this group to validate the new ASKAP data and the data reduction pipeline ASKAP SOFT. We detect six galaxies in the neutral hydrogen (H I) 21-cm line, expanding the NGC 7162 group membership from four to seven galaxies. Two of the new detections are also the first H I detections of the dwarf galaxies, AM 2159-434 and GALEXASC J220338.65-431128.7, for which we have measured velocities of cz = 2558 and cz = 2727 km s-1, respectively. We confirm that there is extended H I emission around NGC 7162 possibly due to past interactions in the group as indicated by the 40° offset between the kinematic and morphological major axes for NGC 7162A, and its H I richness. Taking advantage of the increased resolution (factor of ˜1.5) of the ASKAP data over archival ATCA observations, we fit a tilted ring model and use envelope tracing to determine the galaxies' rotation curves. Using these we estimate the dynamical masses and find, as expected, high dark matter fractions of fDM ˜ 0.81-0.95 for all group members. The ASKAP data are publicly available.

KW - instrumentation: interferometers

KW - telescopes

KW - galaxies: distances and redshifts

KW - galaxies: groups: general

KW - galaxies: kinematics and dynamics

KW - radio lines: galaxies

U2 - 10.1093/mnras/sty2930

DO - 10.1093/mnras/sty2930

M3 - Article

VL - 482

SP - 3591

EP - 3608

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 3

ER -