Mapping HI 21-cm in the Klemola 31 group at z = 0.029: emission and absorption towards PKS2020-370. (arXiv:2206.09940v2 [astro-ph.GA] UPDATED)

Mapping HI 21-cm in the Klemola 31 group at z = 0.029: emission and absorption towards PKS2020-370. (arXiv:2206.09940v2 [astro-ph.GA] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Maina_E/0/1/0/all/0/1">E. K. Maina</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mohapatra_A/0/1/0/all/0/1">Abhisek Mohapatra</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jozsa_G/0/1/0/all/0/1">G. I. G. Jozsa</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gupta_N/0/1/0/all/0/1">N. Gupta</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Combes_F/0/1/0/all/0/1">F. Combes</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Deka_P/0/1/0/all/0/1">P. Deka</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wagenveld_J/0/1/0/all/0/1">J. D. Wagenveld</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Srianand_R/0/1/0/all/0/1">R. Srianand</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Balashev_S/0/1/0/all/0/1">S. A. Balashev</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chen_H/0/1/0/all/0/1">Hsiao-Wen Chen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Krogager_J/0/1/0/all/0/1">J.-K. Krogager</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Momjian_E/0/1/0/all/0/1">E. Momjian</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Noterdaeme_P/0/1/0/all/0/1">P. Noterdaeme</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Petitjean_P/0/1/0/all/0/1">P. Petitjean</a>

We present MeerKAT Absorption Line Survey (MALS) observations of the HI gas
in the Klemola31 galaxy group ($z=0.029$), located along the line of sight to
the radio-loud quasar PKS2020-370 ($z=1.048$). Four galaxies of the group are
detected in HI emission, and HI absorption is also detected in front of
PKS2020-370 in Klemola31A. The emission and absorption are somewhat
compensating on the line of sight of the quasar, and the derived column density
of the absorption appears under-estimated, with respect to the neighbouring
emission. A symmetric tilted-ring model of Klemola31A, assuming the absorbing
gas in regular rotation in the plane, yields a rather high spin temperature of
530K. An alternative interpretation is that the absorbing gas is extra-planar,
which will also account for its non-circular motion. The NaI/CaII ratio also
suggests that the absorbing gas is unrelated to cold HI disk. Two of the
galaxies in the Klemola group are interacting with a small companion, and
reveal typical tidal tails, and velocity perturbations. Only one of the
galaxies, ESO400-13, reveals a strong HI deficiency, and a characteristic
ram-pressure stripping, with a total asymmetry in the distribution of its gas.
Since a small galaxy group as Klemola31 is not expected to host a dense
intra-group gas, this galaxy must be crossing the group at a very high
velocity, mostly in the sky plane.

We present MeerKAT Absorption Line Survey (MALS) observations of the HI gas
in the Klemola31 galaxy group ($z=0.029$), located along the line of sight to
the radio-loud quasar PKS2020-370 ($z=1.048$). Four galaxies of the group are
detected in HI emission, and HI absorption is also detected in front of
PKS2020-370 in Klemola31A. The emission and absorption are somewhat
compensating on the line of sight of the quasar, and the derived column density
of the absorption appears under-estimated, with respect to the neighbouring
emission. A symmetric tilted-ring model of Klemola31A, assuming the absorbing
gas in regular rotation in the plane, yields a rather high spin temperature of
530K. An alternative interpretation is that the absorbing gas is extra-planar,
which will also account for its non-circular motion. The NaI/CaII ratio also
suggests that the absorbing gas is unrelated to cold HI disk. Two of the
galaxies in the Klemola group are interacting with a small companion, and
reveal typical tidal tails, and velocity perturbations. Only one of the
galaxies, ESO400-13, reveals a strong HI deficiency, and a characteristic
ram-pressure stripping, with a total asymmetry in the distribution of its gas.
Since a small galaxy group as Klemola31 is not expected to host a dense
intra-group gas, this galaxy must be crossing the group at a very high
velocity, mostly in the sky plane.

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