Near-infrared integrated spectra of Galactic globular clusters: testing
  simple stellar population models
  We present SOAR/OSIRIS cross-dispersed NIR integrated spectra of 12 Galactic
globular clusters that are employed to test Maraston (2005, M05) NIR EPS
models, and to provide spectral observational constraints to calibrate future
models. We measured Ew of the most prominent NIR absorption features. Optical
Ew were also measured. The globular clusters Ew were compared with model
predictions with ages within 4-15 Gyr, and metallicities between 1/200 and 2
Zsun. Observed integrated colours were also compared with models. The NIR
integrated spectra among our sample appear qualitatively similar in most the
absorption features. The M05 models can properly predict the optical Ew
observed in globular clusters. Regarding the NIR, they do underestimate the
strength of Mg I 1.49mum, but they can reproduce the observed Ew of Fe I
1.58mum, Si I 1.59mum, and CO 2.29mum, in about half of our sample. The
remaining objects require the inclusion of intermediate-age populations. Thus,
we suggest that the presence of C- and O-rich stars in models is important to
reproduce the observed strengths of metallic lines. Another possibility is the
lack of alpha-enhancement in the models. In the case of the optical and NIR Fe
I lines, standard models and those that include blue horizontal branch stars,
produce similar results. A similar trend is observed for Na I 5895A, while in
the case of the G-band, the models with blue horizontal branch do describe
better the observations. For most of the sample the optical to NIR colours are
well described by the M05 models. In general, M05 models can provide reliable
information on the NIR stellar population of galaxies, but only when Ew and
colours are taken together, in other words, Ew and continuum fluxes should be
simultaneously fitted. However, the results should be taken with caution, since
the models tend to predict results biased towards young ages.
