We present MeerKAT neutral hydrogen (H i) observations of the Fornax A group, which is likely falling into the Fornax cluster for
the first time. Our H i image is sensitive to 1.4 × 1019 atoms cm−2 over 44.1 km s−1
, where we detect H i in 10 galaxies and a total
of (1.12 ± 0.02) × 109 M of H i in the intra-group medium (IGM). We search for signs of pre-processing in the 12 group galaxies
with confirmed optical redshifts that reside within the sensitivity limit of our H i image. There are 9 galaxies that show evidence of
pre-processing and we classify each galaxy into their respective pre-processing category, according to their H i morphology and gas
(atomic and molecular) scaling relations. Galaxies that have not yet experienced pre-processing have extended H i discs and a high
H i content with a H2-to-H i ratio that is an order of magnitude lower than the median for their stellar mass. Galaxies that are currently
being pre-processed display H i tails, truncated H i discs with typical gas fractions, and H2-to-H i ratios. Galaxies in the advanced
stages of pre-processing are the most H i deficient. If there is any H i, they have lost their outer H i disc and efficiently converted
their H i to H2, resulting in H2-to-H i ratios that are an order of magnitude higher than the median for their stellar mass. The central,
massive galaxy in our group (NGC 1316) underwent a 10:1 merger ∼ 2 Gyr ago and ejected 6.6 – 11.2 × 108 M of H i, which we
detect as clouds and streams in the IGM, some of which form coherent structures up to ∼ 220 kpc in length. We also detect giant
(∼ 100 kpc) ionised hydrogen (Hα) filaments in the IGM, likely from cool gas being removed (and subsequently ionised) from an
in-falling satellite. The Hα filaments are situated within the hot halo of NGC 1316 and there are localised regions that contain H i. We
speculate that the Hα and multiphase gas is supported by magnetic pressure (possibly assisted by the NGC 1316 AGN), such that the
hot gas can condense and form H i that survives in the hot halo for cosmological timescales.
We have undertaken a systematic study of FR I and FR II radio galaxies with the upgraded Giant Metrewave Radio Telescope (uGMRT) and MeerKAT. The main goal is to explore whether the unprecedented few μJy sensitivity reached ...
We present a progress report of a study of FR I and FR II radio galaxies. Several new morphological features in the radio emission are now revealed using the high (mJy) sensitivity reached in the range 550–1712 MHz, more ...
Shafi, N.; Oosterloo, T.A.; Morganti, R.; Booth, Roy S.; Colafrancesco, S.(Oxford University Press, 2015-09-14)
We present deep neutral hydrogen (H i) observations of the starburst/Seyfert galaxy NGC 3079
and its environment, obtained with the Westerbork Synthesis Radio Telescope. Our observations
reveal previously unknown components, ...