A giant Ly$\alpha$ nebula and a small-scale clumpy outflow in the system
  of the exotic quasar J0952+0114 unveiled by MUSE
  The well-known quasar SDSS J095253.83+011421.9 (J0952+0114) at z=3.02 has one
of the most peculiar spectra discovered so far, showing the presence of narrow
Ly$\alpha$ and broad metal emission lines. Although recent studies have
suggested that a Proximate Damped Ly$\alpha$ system (PDLA) causes this peculiar
spectrum, the origin of the gas associated with the PDLA is unknown. Here we
report the results of MUSE observations that reveal a new giant ($\approx$ 100
physical kpc) Lyman $\alpha$ nebula. The detailed analysis of the Ly$\alpha$
velocity, velocity dispersion, and surface brightness profiles suggests that
the J0952+0114 Ly$\alpha$ nebula shares similar properties of other QSO nebulae
previously detected with MUSE, implying that the PDLA in J0952+0144 is covering
only a small fraction of the QSO emission solid angle. We also detected bright
and spectrally narrow CIV$\lambda$1550 and HeII$\lambda$1640 extended emission
around J0952+0114 with velocity centroids similar to the peak of the extended
and central narrow Ly$\alpha$ emission. The presence of a peculiarly bright,
unresolved, and relatively broad HeII$\lambda$1640 emission in the central
region at exactly the same PDLA redshift hints at the possibility that the PDLA
originates in a clumpy outflow with a bulk velocity of about 500 km/s. The
smaller velocity dispersion of the large scale Ly$\alpha$ emission suggests
that the high-speed outflow is confined to the central region. Lastly, the
derived spatially resolved HeII/Ly$\alpha$ and CIV/Ly$\alpha$ maps show a
positive gradient with the distance to the QSO hinting at a non-homogeneous
ionization parameter distribution.
