Bibcode
Riffel, R.; Mason, Rachel E.; Martins, Lucimara P.; Rodríguez-Ardila, Alberto; Ho, Luis C.; Riffel, Rogemar A.; Lira, Paulina; Gonzalez Martin, O.; Ruschel-Dutra, D.; Alonso-Herrero, Almudena; Flohic, Helene; McDermid, Richard M.; Ramos Almeida, C.; Thanjavur, Karun; Winge, Claudia
Bibliographical reference
Monthly Notices of the Royal Astronomical Society, Volume 450, Issue 3, p.3069-3079
Advertised on:
7
2015
Citations
28
Refereed citations
27
Description
We analyse the stellar absorption features in high signal-to-noise ratio
(S/N) near-infrared (NIR) spectra of the nuclear region of 12 nearby
galaxies, mostly spirals. The features detected in some or all of the
galaxies in this sample are the TiO (0.843 and 0.886 μm), VO (1.048
μm), CN (1.1 and 1.4 μm), H2O (1.4 and 1.9 μm) and
CO (1.6 and 2.3 μm) bands. The C2 (1.17 and 1.76 μm)
bands are generally weak or absent, although C2 (1.76 μm)
may be weakly present in the mean galaxy spectrum. A deep feature near
0.93 μm, likely caused by CN, TiO and/or ZrO, is also detected in all
objects. Fitting a combination of stellar spectra to the mean spectrum
shows that the absorption features are produced by evolved stars: cool
giants and supergiant stars in the early- or thermally pulsing
asymptotic giant branch (E-AGB or TP-AGB) phases. The high luminosity of
TP-AGB stars, and the appearance of VO and ZrO features in the data,
suggest that TP-AGB stars dominate these spectral features. However, a
contribution from other evolved stars is also likely. Comparison with
evolutionary population synthesis models shows that models based on
empirical libraries that predict relatively strong NIR features provide
a more accurate description of the data. However, none of the models
tested accurately reproduces all of the features observed in the
spectra. To do so, the models will need to not only improve the
treatment of TP-AGB stars, but also include good quality spectra of red
giant and E-AGB stars. The uninterrupted wavelength coverage, high S/N
and quantity of features we present here will provide a benchmark for
the next generation of models aiming to explain and predict the NIR
properties of galaxies.
Related projects
Nuclear Activity in Galaxies: a 3D Perspective from the Nucleus to the Outskirts
This project consists of two main research lines. First, the study of quasar-driven outflows in luminous and nearby obscured active galactic nuclei (AGN) and the impact that they have on their massive host galaxies (AGN feedback). To do so, we have obtained Gran Telescopio CANARIAS (GTC) infrared and optical observations with the instruments
Cristina
Ramos Almeida