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  • The MeerKAT Fornax Survey: III. Ram-pressure stripping of the tidally interacting galaxy NGC 1427A in the Fornax cluster
Title: The MeerKAT Fornax Survey: III. Ram-pressure stripping of the tidally interacting galaxy NGC 1427A in the Fornax cluster
We present MeerKAT Fornax Survey H Iobservations of NGC 1427A, a blue irregular galaxy with a stellar mass of ∼2 × 109M⊙located near the centre of the Fornax galaxy cluster. Thanks to the excellent resolution (1–6 kpc spatially, 1.4 km s−1in velocity) and H Icolumn density sensitivity (∼4 × 1019to ∼1018cm−2depending on resolution), our data deliver new insights on the long-debated interaction of this galaxy with the cluster environment. We confirm the presence of a broad, one-sided, starless H Itail stretching from the outer regions of the stellar body and pointing away from the cluster centre. We find the tail to have 50% more H I(4 × 108M⊙) and to be 3 times longer (70 kpc) than in previous observations. In fact, we detect scattered H Iclouds out to 300 kpc from the galaxy in the direction of the tail – possibly the most ancient remnant of the passage of NGC 1427A through the intracluster medium of Fornax. Both the velocity gradient along the H Itail and the peculiar kinematics of H Iin the outer region of the stellar body are consistent with the effect of ram pressure given the line-of-sight motion of the galaxy within the cluster. However, several properties cannot be explained solely by ram pressure and suggest an ongoing tidal interaction. This includes: the close match between dense H Iand stars within the disturbed stellar body; the abundant kinematically anomalous H I; and the inversion of the H Ivelocity gradient near the base of the H Itail. We rule out an interaction with the cluster tidal field, and conclude that NGC 1427A is the result of a high-speed galaxy encounter or of a merger started at least 300 Myr ago, where ram pressure shapes the distribution and kinematics of the H Iin the perturbed outer stellar body and in the tidal tails.  more » « less
Award ID(s):
2108470
PAR ID:
10545114
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;
Publisher / Repository:
EDP Sciences
Date Published:
Journal Name:
Astronomy & Astrophysics
Volume:
690
ISSN:
0004-6361
Page Range / eLocation ID:
A4
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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