The nuclear near-infrared spectral properties of nearby galaxies

We present spectra of the nuclear regions of 50 nearby (D = 1–92 Mpc, median = 20 Mpc) galaxies of morphological types E to Sm. The spectra, obtained with the Gemini Near-IR Spectrograph on the Gemini North telescope, cover a wavelength range of approximately 0.85–2.5 μm at R ~ 1300–1800. There is evidence that most of the galaxies host an active galactic nucleus (AGN), but the range of AGN luminosities (log (L $_{2-10\;{\rm keV}}$ [erg s−1]) = 37.0–43.2) in the sample means that the spectra display a wide variety of features. Some nuclei, especially the Seyferts, exhibit a rich emission-line spectrum. Other objects, in particular the type 2 Low Ionization Nuclear Emission Region galaxies, show just a few, weak emission lines, allowing a detailed view of the underlying stellar population. These spectra display numerous absorption features sensitive to the stellar initial mass function, as well as molecular bands arising in cool stars, and many other atomic absorption lines. We compare the spectra of subsets of galaxies known to be characterized by intermediate-age and old stellar populations, and find clear differences in their absorption lines and continuum shapes. We also examine the effect of atmospheric water vapor on the signal-to-noise ratio achieved in regions between the conventional NIR atmospheric windows, which are of potential interest to those planning observations of redshifted emission lines or other features affected by telluric H2O. Further exploitation of this data set is in progress, and the reduced spectra and data reduction tools are made available to the community.C.R.A. is supported by a Marie Curie Intra European Fellowship within the 7th European Community Framework Programme (PIEF-GA-2012-327934). L.C.H. acknowledges support from the Kavli Foundation, Peking University, and the Chinese Academy of Science through grant No. XDB09030100 (Emergence of Cosmological Structures) from the Strategic Priority Research Program. A.A.-H. acknowledges support from the Spanish Plan Nacional de Astronomía y Astrofísica under grant AYA2012-31447. A.R.A. thanks the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) for partial support of this work through grant 307403/2012-2.Peer Reviewe