Uncovering the nucleus candidate for NGC 253
  NGC253 is the nearest spiral galaxy with a nuclear starburst which becomes
the best candidate to study the relationship between starburst and AGN
activity. However, this central region is veiled by large amounts of dust, and
it has been so far unclear which is the true dynamical nucleus. The near
infrared spectroscopy could be advantageous in order to shed light on the true
nucleus identity. Using Flamingos-2 at Gemini South we have taken deep K-band
spectra along the major axis and through the brightest infrared source. We
present evidence showing that the brightest near infrared and mid infrared
source in the central region, already known as radio source TH7 and so far
considered just a stellar supercluster, in fact, presents various symptoms of a
genuine galactic nucleus. Therefore, it should be considered a valid nucleus
candidate. It is the most massive compact infrared object in the central
region, located at 2.0" of the symmetry center of the galactic bar. Moreover,
our data indicate that this object is surrounded by a large circumnuclear
stellar disk and it is also located at the rotation center of the large
molecular gas disk of NGC 253. Furthermore, a kinematic residual appears in the
H2 rotation curve with a sinusoidal shape consistent with an outflow centered
in the candidate nucleus position. The maximum outflow velocity is located
about 14 pc from TH7, which is consistent with the radius of a shell detected
around the nucleus candidate observed at 18.3 {\mu}m (Qa) and 12.8 {\mu}m
([NeII]) with T-ReCS. Also, the Br_gamma emission line profile is blue-shifted
and this emission line has also the highest equivalent width at this position.
All these evidences point out TH7 as the best candidate to be the galactic
nucleus of NGC 253.
