The cycle of metals in the infalling elliptical galaxy NGC 1404
  Hot atmospheres pervading galaxy clusters, groups, and early-type galaxies
are rich in metals, produced during epochs and diffused via processes that are
still to be determined. While this enrichment has been routinely investigated
in clusters, metals in lower mass systems are more challenging to probe with
standard X-ray exposures and spectroscopy. In this paper, we focus on very deep
XMM-Newton ($\sim$350 ks) observations of NGC 1404, a massive elliptical galaxy
experiencing ram-pressure stripping of its hot atmosphere while infalling
toward the centre of the Fornax cluster, with the aim to derive abundances
through its hot gas extent. Importantly, we report the existence of a new
fitting bias - the "double Fe bias" - leading to an underestimate of the Fe
abundance when two thermal components cannot realistically model the complex
temperature structure present in the outer atmosphere of the galaxy.
Contrasting with the ''metal conundrum'' seen in clusters, the Fe and Mg masses
of NGC 1404 are measured 1-2 orders of magnitude below what stars and
supernovae could have reasonably produced and released. In addition, we note
the remarkable Solar abundance ratios of the galaxy's halo, different from its
stellar counterpart but similar to the chemical composition of the ICM of rich
clusters. Completing the clusters regime, all these findings provide additional
support toward a scenario of early enrichment, at play over two orders of
magnitude in mass. A few peculiar and intriguing features, such as a possible
double metal peak as well as an apparent ring of enhanced Si near the galaxy
core, are also discussed.
