Galaxies within galaxies in the TIMER survey: stellar populations of inner bars are scaled replicas of main bars

Abstract

Inner bars are frequent structures in the local Universe and thought to substantially influence the nuclear regions of disc galaxies. In this study we explore the structure and dynamics of inner bars by deriving maps and radial profiles of their mean stellar population content and comparing them to previous findings in the context of main bars. To this end, we exploit observations obtained with the integral-field spectrograph MUSE of three double-barred galaxies in the TIMER sample. The results indicate that inner bars can be distinguished based on their stellar population properties alone. More precisely, inner bars show elevated metallicities and depleted [$\alpha$/Fe] abundances. Although they exhibit slightly younger stellar ages compared to the nuclear disc, the typical age differences are small, except at their outer ends. These ends of the inner bars are clearly younger compared to their inner parts, an effect known from main bars as orbital age separation. In particular, the youngest stars (i.e. those with the lowest radial velocity dispersion) seem to occupy the most elongated orbits along the (inner) bar major axis. We speculate that these distinct ends of bars could be connected to the morphological feature of ansae. Radial profiles of metallicity and [$\alpha$/Fe] enhancements are flat along the inner bar major axis, but show significantly steeper slopes along the minor axis. This radial mixing in the inner bar is also known from main bars and indicates that inner bars significantly affect the radial distribution of stars. In summary, based on maps and radial profiles of the mean stellar population content and in line with previous TIMER results, inner bars appear to be scaled down versions of the main bars seen in galaxies. This suggests the picture of a "galaxy within a galaxy", with inner bars in nuclear discs being dynamically equivalent to main bars in main galaxy discs.

Accepted for publication in A&A; 11 pages, 4 figures, 2 tables

References in corpus (33)

• Overview of the SDSS-IV MaNGA Survey: Mapping Nearby Galaxies at Apache Point Observatory
• Improving the full spectrum fitting method: accurate convolution with Gauss-Hermite functions
• The Atlas3D Project - XXX. Star formation histories and stellar population scaling relations of early-type galaxies
• Evolutionary stellar population synthesis with MILES - II. Scaled-solar and α-enhanced models
• The Data Processing Pipeline for the MUSE Instrument
• The MUSE Hubble Ultra Deep Field Survey: I. Survey description, data reduction and source detection
• A Classical Morphological Analysis of Galaxies in the Spitzer Survey of Stellar Structure in Galaxies (S4G)
• The population of barred galaxies in the local universe I. Detection and characterisation of bars
• The SAURON project - VII. Integral-field absorption and emission-line kinematics of 24 spiral galaxy bulges
• Bars in Disk-Dominated and Bulge-Dominated Galaxies at z~0: New Insights from ~3600 SDSS Galaxies
• Stellar Population gradients in galaxy discs from the CALIFA survey
• Image Decomposition of Barred Galaxies and AGN Hosts
• The SAURON project - XI. Stellar Populations from Absorption Line Strength Maps of 24 Early-Type Spirals
• Galaxy Zoo: Secular evolution of barred galaxies from structural decomposition of multi-band images
• Kinematic signatures of nuclear discs and bar-driven secular evolution in nearby galaxies of the MUSE TIMER project
• The Fornax 3D project: unveiling the thick disk origin in FCC 170: signs of accretion?
• Secular- and merger-built bulges in barred galaxies
• The inside-out formation of nuclear discs and the absence of old central spheroids in barred galaxies of the TIMER survey
• 2D kinematic signatures of boxy/peanut bulges
• Confirmation of a Kinematic Diagnostic for Face-On B/P Bulges
• Star formation in isolated AMIGA galaxies: dynamical influence of bars
• SDSS-IV MaNGA: Spatially resolved star formation in barred galaxies
• Metallicity-dependendent kinematics and morphology of the Milky Way bulge
• A Morphological and Statistical Analysis of Ansae in Barred Galaxies
• The distribution of stellar population age in galactic bars
• The distribution of star formation in galactic bars as seen with H$\alpha$ and stacked GALEX UV imaging
• SDSS-IV MaNGA: Stellar Population Gradients Within Barred Galaxies
• Clocking the assembly of double-barred galaxies with the MUSE TIMER project
• New light on the formation and evolution of bars: Trends in the stellar line-strength indices distribution inside the bar region
• The Close AGN Reference Survey (CARS): Comparative analysis of the structural properties of star-forming and non-star-forming galaxy bars
• Stellar kinematics in double-barred galaxies: the sigma-hollows
• Bar effect on gas-phase abundance gradients. II. Luminosity-dependent flattening
• How well can we determine ages and chemical abundances from spectral fitting of integrated light spectra?

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