  The measurement of two-particle angular correlations is a powerful tool to
study jet quenching in a $p_{\mathrm{T}}$ region inaccessible by direct jet
identification. In these measurements pseudorapidity ($\Delta\eta$) and
azimuthal ($\Delta\varphi$) differences are used to extract the shape of the
near-side peak formed by particles associated to a higher $p_{\mathrm{T}}$
trigger particle ($1 < p_{\mathrm{T, trig}} <$ 8 GeV/c). A combined fit of the
near-side peak and long-range correlations is applied to the data allowing the
extraction of the centrality evolution of the peak shape in Pb-Pb collisions at
$\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV. A significant broadening of the peak in
the $\Delta\eta$ direction at low $p_{\mathrm{T}}$ is found from peripheral to
central collisions, which vanishes above 4 GeV/c, while in the $\Delta\varphi$
direction the peak is almost independent of centrality. For the 10% most
central collisions and $1 < p_{\mathrm{T, assoc}} <$ 2 GeV/c, $1 <
p_{\mathrm{T, trig}} <$ 3 GeV/c a novel feature is observed: a depletion
develops around the centre of the peak. The results are compared to pp
collisions at the same centre of mass energy and to AMPT model simulations. The
comparison to the investigated models suggests that the broadening and the
development of the depletion is connected to the strength of radial and
longitudinal flow.
