2006/02/08 by H. Kuntschner, E. Emsellem, Éric Emsellem +17 · 196 citations
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Effective radius #Elliptical galaxy #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy formation and evolution #Geometry #Lenticular galaxy #Line (geometry) #Metallicity #Photometry (optics) #Physics #RADIUS #Spectral line #Spectrograph #Stars #Stellar, planetary, and galactic studies #Surface brightness #Surface brightness fluctuation #Velocity dispersion #astro-ph
paper · pdf · open access · doi:10.1111/j.1365-2966.2006.10153.x
published in Monthly Notices of the Royal Astronomical Society 369(2), 497-528 (Oxford University Press) · 33 pages, 28 figures. Accepted for publication in MNRAS. A version with full resolution figures is available at http://www.strw.leidenuniv.nl/sauron/papers/kuntschner2006_sauron6.pdf
arxiv created 2006/02/08 · openalex publication_date 2006/05/26 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present absorption line strength maps of 48 representative elliptical and lenticular galaxies obtained as part of a survey of nearby galaxies using our custom-built integral-field spectrograph, SAURON, operating on the William Herschel Telescope. Using high-quality spectra, spatially binned to a constant signal-to-noise ratio, we measure four key age, metallicity and abundance ratio sensitive indices from the Lick/IDS system over a two-dimensional field extending up to approximately one effective radius. A discussion of calibrations and offsets is given, along with a description of error estimation and nebular emission correction. We modify the classical Fe5270 index to define a new index, Fe5270S, which maximizes the useable spatial coverage of SAURON. Maps of Hβ, Fe5015, Mg b and Fe5270S are presented for each galaxy. We use the maps to compute average line strengths integrated over circular apertures of one-eighth effective radius, and compare the resulting relations of index versus velocity dispersion with previous long-slit work. The metal line strength maps show generally negative gradients with increasing radius roughly consistent with the morphology of the light profiles. Remarkable deviations from this general trend exist, particularly the Mg b isoindex contours appear to be flatter than the isophotes of the surface brightness for about 40 per cent of our galaxies without significant dust features. Generally, these galaxies exhibit significant rotation. We infer from this that the fast-rotating component features a higher metallicity and/or an increased Mg/Fe ratio as compared to the galaxy as a whole. The Hβ maps are typically flat or show a mild positive outwards radial gradient, while a few galaxies show strong central peaks and/or elevated overall Hβ strength likely connected to recent star formation activity. For the most prominent post-starburst galaxies, even the metal line strength maps show a reversed gradient.