Stellar feedback in a clumpy galaxy at $z \sim$ 3.4
  Giant star-forming regions (clumps) are widespread features of galaxies at $z
\approx 1-4$. Theory predicts that they can play a crucial role in galaxy
evolution if they survive to stellar feedback for > 50 Myr. Numerical
simulations show that clumps' survival depends on the stellar feedback recipes
that are adopted. Up to date, observational constraints on both clumps'
outflows strength and gas removal timescale are still uncertain. In this
context, we study a line-emitting galaxy at redshift $z \simeq 3.4$ lensed by
the foreground galaxy cluster Abell 2895. Four compact clumps with sizes
$\lesssim$ 280 pc and representative of the low-mass end of clumps' mass
distribution (stellar masses $\lesssim 2\times10^8\ {\rm M}_\odot$) dominate
the galaxy morphology. The clumps are likely forming stars in a starbursting
mode and have a young stellar population ($\sim$ 10 Myr). The properties of the
Lyman-$\alpha$ (Ly$\alpha$) emission and nebular far-ultraviolet absorption
lines indicate the presence of ejected material with global outflowing
velocities of $\sim$ 200-300 km/s. Assuming that the detected outflows are the
consequence of star formation feedback, we infer an average mass loading factor
($\eta$) for the clumps of $\sim$ 1.8 - 2.4 consistent with results obtained
from hydro-dynamical simulations of clumpy galaxies that assume relatively
strong stellar feedback. Assuming no gas inflows (semi-closed box model), the
estimates of $\eta$ suggest that the timescale over which the outflows expel
the molecular gas reservoir ($\simeq 7\times 10^8\ \text{M}_\odot$) of the four
detected low-mass clumps is $\lesssim$ 50 Myr.
