The early phases of the type Iax supernova SN 2011ay
  We present a detailed study of the early phases of the peculiar supernova
2011ay based on BVRI photometry obtained at Konkoly Observatory, Hungary, and
optical spectra taken with the Hobby-Eberly Telescope at McDonald Observatory,
Texas. The spectral analysis carried out with SYN++ and SYNAPPS confirms that
SN 2011ay belongs to the recently defined class of SNe Iax, which is also
supported by the properties of its light and color curves. The estimated
photospheric temperature around maximum light, T_{phot} ~8,000 K, is lower than
in most Type Ia SNe, which results in the appearance of strong Fe II features
in the spectra of SN 2011ay, even during the early phases. We also show that
strong blending with metal features (those of Ti II, Fe II, Co II) makes the
direct analysis of the broad spectral features very difficult, and this may be
true for all SNe Iax. We find two alternative spectrum models that both
describe the observed spectra adequately, but their photospheric velocities
differ by at least 3,000 km/s. The quasi-bolometric light curve of SN~2011ay
has been assembled by integrating the UV-optical spectral energy distributions.
Fitting a modified Arnett-model to L_{bol}(t), the moment of explosion and
other physical parameters, i.e. the rise time to maximum, the ^{56}Ni mass and
the total ejecta mass are estimated as t_{rise} ~14 +/-1 days, M_{Ni} ~0.22 +/-
0.01 M_{sol} and M_{ej} ~0.8 M_{sol}, respectively.
