Glance: A Comprehensive Framework for Galactic Archaeology

Abstract

A central topic in extragalactic astronomy is understanding the formation and evolutionary histories of galaxies. These systems often comprise multiple structural components with distinct physical and dynamical properties, making it challenging to disentangle their individual contributions. Aiming at investigating the true structure of the inner stellar disk, we have developed a comprehensive pipeline for the chronochemical and dynamical analysis of galaxies (Glance: Galactic archaeoLogy via chronochemicAl & dyNamiCal modElling). The presented pipeline employs several state-of-the-art techniques by integrating them into a single, automated pipeline, enabling streamlined analysis of integral-field spectroscopy data, by allowing users to easily and directly extract valuable information on stellar populations, kinematics, dynamics, and gas properties. It automates multiple analysis techniques, including stellar population synthesis (Fado, Starlight, post-processing with RemoveYoung, kinematic extraction (pPXF, Bayes-LOSVD), and dynamical modelling (Dynamite). It handles tasks such as Galactic extinction correction, de-redshifting, Voronoi binning, and nebular continuum correction, while offering extensive customization options. Parallel processing significantly reduces computational time. When applied to MUSE data sampling the central region of NGC 1566, this methodology reveals that its stellar disk significantly deviates from the conventional exponential model, challenging the assumption of universality in disk morphology. In summary, this work presents a powerful, publicly available pipeline for conducting galactic archaeology, designed to advance our understanding of the formation and evolution of galaxies.

Figures (10)

• Figure 1: Schematic overview of the Glance pipeline. The code utilizes IFS data cubes and broad-band photometric frames, performing: photometric analysis, spectral synthesis via Fado & Starlight, stellar stratigraphy trough ${\cal RY}$, emission-line analysis, stellar kinematic extraction via pPXF & Bayes-LOSVD, and dynamical modelling by means of Dynamite. Each module can be executed independently, facilitating specific user requirements.
• Figure 2: Left panel: $K$-band photometric image of NGC 1566, as observed by VISTA (VHS), rotated to the kinematic PA. The FoV of the MUSE observation is indicated by a dashed square, with contours highlighting the morphology within this region. The blue circle indicates the central region as assessed by the Sérsic fit, while the ellipse illustrates the widest point in the SBP, outlining the galaxy's size. Right panel: Derived SBP with a blue line indicating the best-fitting Sérsic model to the central luminosity excess. The blue dashed vertical line marks the radius derived from the Sérsic fit, while the black dashed line indicates MUSE's FoV.
• Figure 3: FADO Spectral Synthesis Results for NGC 1566 (BC03 SSP Library). The figure presents 24 maps, displaying: 1) Stellar population properties, including mass- and luminosity-weighted ages (Gyr) and metallicities (Z$_\odot$), present-day and total ever-formed stellar masses (logM$_\odot$), and stellar surface density; 2) Emission-line fluxes (with units of $10^{-17}$$\cdot$ erg s$^{-1}$ cm$^{-2}$, in log-space) and equivalent widths (Å) for H$\beta$, [OIII]$\lambda\lambda$4959,5007, H$\alpha$, [NII]$\lambda\lambda$6548,6583, and [SII]$\lambda\lambda$6717,6731; 3) Extinction maps, including $E(B-V)_{\text{neb}}$ and $A_{\rm V}$. Similar figures are produced for other SSP libraries (e.g., CB19) and for Starlight, though the latter excludes extinction maps. Photometric contours are overplotted, and the black circle represents the characteristic central region.
• Figure 4: BPT diagram and Kennicutt relation for NGC 1566. Left panel: BPT diagram with emission-line ratios [NII]$\lambda$6584/H$\alpha$ vs. [OIII]$\lambda$5007/H$\beta$, color-coded by distance from the galaxy centre. Demarcation lines from Kew01, Sch07, and Kau03 are overlaid to classify regions as star-forming, AGN-dominated, or composite. Right panel: spatially resolved star-formation rate (SFR) derived from the Kennicutt relation using H$\alpha$ luminosity, with values in units of M$_\odot$/yr. The central region is demarcated by a black circle and the map is rotated to the kinematic PA. The total estimated SFR is shown at the bottom of the figure (an asterisk (*) indicates that the MUSE FoV does not fully cover the stellar disk).
• Figure 5: Stellar kinematic maps for NGC 1566, displaying the mean velocity, velocity dispersion, and higher-order moments (h$_3$ and h$_4$). Maps are rotated to the kinematic PA, with color bars in units of km/s. The black circle represents the central region as assessed by $K$-band surface photometry.