Riffel, R. A.; Ho, Luis C.; Mason, Rachel; Rodríguez-Ardila, Alberto; Martins, Lucimara; Riffel, Rogério; Diaz, Ruben; Colina, Luis; Alonso-Herrero, Almudena; Flohic, Helene; Gonzalez Martin, O.; Lira, Paulina; McDermid, Richard; Ramos Almeida, C.; Schiavon, Ricardo; Thanjavur, Karun; Ruschel-Dutra, D.; Winge, Claudia; Perlman, Eric
Referencia bibliográfica
Monthly Notices of the Royal Astronomical Society, Volume 446, Issue 3, p.2823-2836
Fecha de publicación:
1
2015
Número de citas
20
Número de citas referidas
20
Descripción
We examine the stellar velocity dispersions (σ) of a sample of 48
galaxies, 35 of which are spirals, from the Palomar nearby galaxy
survey. It is known that for ultra-luminous infrared galaxies (ULIRGs)
and merger remnants, the σ derived from the near-infrared CO band
heads is smaller than that measured from optical lines, while no
discrepancy between these measurements is found for early-type galaxies.
No such studies are available for spiral galaxies - the subject of this
paper. We used cross-dispersed spectroscopic data obtained with the
Gemini Near-Infrared Spectrograph, with spectral coverage from 0.85 to
2.5 μm, to obtain σ measurements from the 2.29 μm CO band
heads (σCO) and the 0.85 μm calcium triplet
(σCaT). For the spiral galaxies in the sample, we found
that σCO is smaller than σCaT, with a
mean fractional difference of 14.3 per cent. The best fit to the data is
given by σopt = (46.0 ± 18.1) + (0.85 ±
0.12)σCO. This `σ-discrepancy' may be related to
the presence of warm dust, as suggested by a slight correlation between
the discrepancy and the infrared luminosity. This is consistent with
studies that have found no σ-discrepancy in dust-poor early-type
galaxies, and a much larger discrepancy in dusty merger remnants and
ULIRGs. That σCO is lower than σopt
may also indicate the presence of a dynamically cold stellar population
component. This would agree with the spatial correspondence between
low-σCO and young/intermediate-age stellar populations
that has been observed in spatially resolved spectroscopy of a handful
of galaxies.
Proyectos relacionados
Actividad Nuclear en Galaxias: una Perspectiva 3D del Núcleo y su Entorno
Nuestro proyecto puede dividirse en dos líneas principales de investigación. En primer lugar, el estudio de los vientos producidos por cuásares luminosos oscurecidos y del impacto que estos tienen en sus galaxias anfitrionas (retroalimentación del AGN). Para ello hemos obtenido observaciones infrarrojas y ópticas con los instrumentos del Gran
Cristina
Ramos Almeida