Abstract
El Gordo (ACT-CL J0102-4915) is an extraordinarily large and bright galaxy
cluster collision. In a previous study, we found that El Gordo is in
$6.2\sigma$ tension with the $Łambda$CDM standard model when assuming the
nominal mass and infall velocity values from the hydrodynamical simulations of
Zhang et al. ($M_200 = 3.2 10^15 M_ødot$ and $V_infall
= 2500~km~s^-1$, respectively). The recent weak lensing study of Kim
et al. showed that the mass of El Gordo is actually $2.13^+0.25_-0.23
10^15 M_ødot$. Here we explore the level of tension between El
Gordo and $Łambda$CDM for the new mass estimate, assuming several
$V_infall$ values. We find that in order to reduce the tension below
the $5\sigma$ level, the El Gordo subclusters should have $V_infall
< 2300~km~s^-1$ ($V_infall < 1800~km~s^-1$
when considering the combined tension with the Bullet Cluster). To the best of
our knowledge, the El Gordo hydrodynamical simulations conducted so far require
$V_infall 2500~km~s^-1$ to simultaneously reproduce
its morphology and its high X-ray luminosity and temperature. We therefore
conclude that El Gordo still poses a significant challenge to $Łambda$CDM
cosmology. Whether the properties of El Gordo can be reconciled with a lower
$V_infall$ should be tested with new hydrodynamical simulations that
explore different configurations of the interaction.
Users
Please
log in to take part in the discussion (add own reviews or comments).