Mapping the ionized gas of the metal-poor HII galaxy PHL 293B with
  MEGARA
  Here we report the first spatially resolved spectroscopic study for the
galaxy PHL293B using the high-resolution GTC/MEGARA IFU. PHL293B is a local,
extremely metal-poor, high ionization galaxy. This makes PHL 293B an excellent
analogue for galaxies in the early Universe. The MEGARA aperture (~12.5''x
11.3'') covers the entire PHL 293B main body and its far-reaching ionized gas.
We created and discussed maps of all relevant emission lines, line ratios and
physical-chemical properties of the ionized ISM. The narrow emission gas
appears to be ionized mainly by massive stars according to the observed
diganostic line ratios, regardless of the position across the MEGARA aperture.
We detected low intensity broad emission components and blueshifted absorptions
in the Balmer lines (H$\alpha$,H$\beta$) which are located in the brightest
zone of the galaxy ISM. A chemically homogeneity, across hundreds of parsecs,
is observed in O/H. We take the oxygen abundance 12+log(O/H)=7.64 $\pm$ 0.06
derived from the PHL293B integrated spectrum as the representative metallicity
for the galaxy. Our IFU data reveal for the first time that the nebular
HeII4686 emission from PHL 293B is spatially extended and coincident with the
ionizing stellar cluster, and allow us to compute its absolute HeII ionizing
photon flux. Wolf-Rayet bumps are not detected excluding therefore Wolf-Rayet
stars as the main HeII excitation source. The origin of the nebular HeII4686 is
discussed.
