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.

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

References in corpus (83)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Astropy: A Community Python Package for Astronomy
• On the variation of the Initial Mass Function
• Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
• The SIMBAD astronomical database
• Parametric Recovery of Line-of-Sight Velocity Distributions from Absorption-Line Spectra of Galaxies via Penalized Likelihood
• Secular Evolution and the Formation of Pseudobulges in Disk Galaxies
• Overview of the SDSS-IV MaNGA Survey: Mapping Nearby Galaxies at Apache Point Observatory
• A large stellar evolution database for population synthesis studies. I. Scaled solar models and isochrones
• Improving the full spectrum fitting method: accurate convolution with Gauss-Hermite functions
• Adaptive spatial binning of integral-field spectroscopic data using Voronoi tessellations
• CALIFA, the Calar Alto Legacy Integral Field Area survey: I. Survey presentation
• The SAURON project - V. Integral-field emission-line kinematics of 48 elliptical and lenticular galaxies
• An updated MILES stellar library and stellar population models
• A large stellar evolution database for population synthesis studies. II. Stellar models and isochrones for an alpha-enhanced metal distribution
• The SAURON project. I. The panoramic integral-field spectrograph
• The Spitzer Survey of Stellar Structure in Galaxies (S^4G)
• The Atlas3D Project - XXX. Star formation histories and stellar population scaling relations of early-type galaxies
• The Galactic Thick Disk Stellar Abundances
• Evolution of the Bar Fraction in COSMOS: Quantifying the Assembly of the Hubble Sequence
• 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
• Nested and Single Bars in Seyfert and Non-Seyfert Galaxies
• Galaxy Zoo: Bars in Disk Galaxies
• Stellar Content from high resolution galactic spectra via Maximum A Posteriori
• 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
• STEllar Content and Kinematics from high resolution galactic spectra via Maximum A Posteriori
• Image Decomposition of Barred Galaxies and AGN Hosts
• Star formation history of barred disc galaxies
• Bar Diagnostics in Edge-On Spiral Galaxies. III. N-Body Simulations of Disks
• Separation of Stellar Populations by an Evolving Bar: Implications for the Bulge of the Milky Way
• Double Bars, Inner Disks, and Nuclear Rings in Early-Type Disk Galaxies
• The two-phase formation history of spiral galaxies traced by the cosmic evolution of the bar fraction
• Can bars be destroyed by a central mass concentration? I. Simulations
• Chemodynamics of barred galaxies in cosmological simulations: On the Milky Way's quiescent merger history and in-situ bulge
• A large stellar evolution database for population synthesis studies. V. Stellar models and isochrones with CNONa abundance anticorrelations
• The impact of bars on disk breaks as probed by S4G imaging
• Secular Evolution and Structural Properties of Stellar Bars in Galaxies
• A Short Scale Length for the α-Enhanced Thick Disk of the Milky Way: Evidence from Low-Latitude SEGUE Data
• Time Inference with MUSE in Extragalactic Rings (TIMER): Properties of the Survey and High-Level Data Products
• The SAURON project - XI. Stellar Populations from Absorption Line Strength Maps of 24 Early-Type Spirals
• Catalogue of the morphological features in the Spitzer Survey of Stellar Structure in Galaxies (S${}^4$G)
• 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 Kinematic Signature of Face-On Peanut-Shaped Bulges
• The Fornax 3D project: unveiling the thick disk origin in FCC 170: signs of accretion?
• The GIST Pipeline: A Multi-Purpose Tool for the Analysis and Visualisation of (Integral-field) Spectroscopic Data
• Secular- and merger-built bulges in barred galaxies
• The disc origin of the Milky Way bulge: Dissecting the chemo-morphological relations using N-body simulations and APOGEE
• The BaSTI Stellar Evolution Database: models for extremely metal-poor and super-metal-rich stellar populations
• The inside-out formation of nuclear discs and the absence of old central spheroids in barred galaxies of the TIMER survey
• The H alpha Galaxy Survey VII. The spatial distribution of star formation within disks and bulges
• 2D kinematic signatures of boxy/peanut bulges
• Confirmation of a Kinematic Diagnostic for Face-On B/P Bulges
• Study of the stellar line-strength indices and kinematics along bars
• Star formation in isolated AMIGA galaxies: dynamical influence of bars
• SDSS-IV MaNGA: Spatially resolved star formation in barred galaxies
• Stellar population constraints on the ages of galactic bars
• 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
• Redistribution of Stars and Gas in the Star Formation Deserts of Barred Galaxies
• Constraining the formation of inner bars. Photometry, kinematics and stellar populations in NGC 357
• Distinct stellar populations in the inner bars of double-barred galaxies
• SDSS-IV MaNGA: Stellar Population Gradients Within Barred Galaxies
• Stellar populations across galaxy bars in the MUSE TIMER project
• 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 BaLROG project - II. Quantifying the influence of bars on the stellar populations of nearby galaxies
• Inner bars also buckle. The MUSE TIMER view of the double-barred galaxy NGC 1291
• 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?
• Secular evolution in action: central values and radial trends in the stellar populations of boxy bulges
• Deconstructing double-barred galaxies in 2D and 3D. II. Two distinct groups of inner bars
• The Stellar Kinematics of Extragalactic Bulges

Cited by in corpus (10)

• Revisiting the role of bars in AGN fuelling with propensity score sample matching
• Bar ages derived for the first time in nearby galaxies: Insights on secular evolution from the TIMER sample
• A first glimpse at the line-of-sight structure of the Milky Way's nuclear stellar disc
• The Carnegie-Irvine Galaxy Survey. X. Bulges in Stellar Mass-based Scaling Relations
• Unveiling the kinematics of a central region in the triple AGN host NGC 7733-7734 interacting group
• The Ancient Globular Clusters of NGC 1291
• Unravelling the Post-Collision Properties of the Cartwheel Galaxy: A MUSE Exploration of its Bar and Inner Region
• Capivara: A Spectral-based Segmentation Method for IFU Data Cubes
• Kinematics of the lens host S0 galaxy NGC 1553: role of secular processes
• Self-consistent modelling of the Milky Way's Nuclear Stellar Disc