Traces of Galaxy Formation: Stellar populations, Dynamics and Morphology

    General
    Description

    Welcome to the Traces of Galaxy Formation research group website.

    We are a large, diverse, and very active research group aiming to provide a comprehensive picture for the formation of galaxies in the Universe. Rooted in detailed stellar population analysis, we are constantly exploring and developing new tools and ideas to understand how galaxies came to be what we now observe.

    A complex star formation history, as the one expected to describe galaxy evolution, needs a multidisciplinary approach to be fully understood. Our group at the IAC consists of experienced researchers in cosmological simulations, dynamical studies, stellar populations and morphological properties of galaxies up to high redshift. We combine different approaches (e.g. observations and theory, secular and cosmological evolution studies) to obtain a complete view of the dominant mechanisms driving the evolution of galaxies.

    Within this general framework, we are currently exploring three main areas of research:

    1. Stellar population synthesis models
      • Development of new stellar population synthesis models
      • Stellar population analysis tools
      • Universality of the stellar initial mass function (IMF)
       
    2. Cosmic evolution of galaxies
      • Massive galaxy evolution
      • Stellar populations in different environments
      • Low surface brightness science
      • Machine learning and cosmological simulations
       
    3. Evolutionary processes in nearby galaxies
      • The role of black holes in the evolution of galaxies
      • Surveys of nearby galaxies
      • Stellar kinematics and dynamical models

    If you want to get in contact or work with us, please send an email to the head of the group (Ignacio Martín-Navarro ignacio.martin [at] iac.es (ignacio[dot]martin[at]iac[dot]es)).

    Here you can find some of our most recent highlights:

    Related publications

    • sMILES: a library of semi-empirical MILES stellar spectra with variable [α/Fe] abundances
      We present a new library of semi-empirical stellar spectra that is based on the empirical Medium resolution Isaac Newton Library of Empirical Spectra (MILES) library. A new, high-resolution library of theoretical stellar spectra is generated that is specifically designed for use in stellar population studies. We test these models across their full
      Knowles, Adam T. et al.

      Advertised on:

      6
      2021
      Citations
      16
    • Numerical simulations of dark matter haloes produce polytropic central cores when reaching thermodynamic equilibrium
      Self-gravitating astronomical objects often show a central plateau in the density profile (core) whose physical origin is hotly debated. Cores are theoretically expected in N-body systems of maximum entropy, however, they are not present in the canonical N-body numerical simulations of cold dark matter (CDM). Our work shows that despite this
      Sánchez Almeida, Jorge et al.

      Advertised on:

      6
      2021
      Citations
      7
    • Fingerprints of stellar populations in the near-infrared: an optimized set of spectral indices in the JHK bands 0
      Stellar population studies provide unique clues to constrain galaxy formation models. So far, detailed studies based on absorption line strengths have mainly focused on the optical spectral range although many diagnostic features are present in other spectral windows. In particular, the near-infrared (NIR) can provide a wealth of information about
      Eftekhari, Elham et al.

      Advertised on:

      6
      2021
      Citations
      7
    • Beyond the hubble sequence - exploring galaxy morphology with unsupervised machine learning
      We explore unsupervised machine learning for galaxy morphology analyses using a combination of feature extraction with a vector-quantized variational autoencoder (VQ-VAE) and hierarchical clustering (HC). We propose a new methodology that includes: (1) consideration of the clustering performance simultaneously when learning features from images; (2
      Cheng, Ting-Yun et al.

      Advertised on:

      5
      2021
      Citations
      44
    • Investigating the projected phase space of Gaussian and non-Gaussian clusters
      By way of the projected phase space (PPS), we investigate the relation between galaxy properties and cluster environment in a subsample of groups from the Yang catalogue. The sample is split according to the Gaussianity of the velocity distribution in the group into Gaussian (G) and non-Gaussian (NG). Our sample is limited to massive clusters with
      Sampaio, V. M. et al.

      Advertised on:

      5
      2021
      Citations
      12
    • The Fornax3D project: Assembly histories of lenticular galaxies from a combined dynamical and population orbital analysis
      In order to assess the impact of the environment on the formation and evolution of galaxies, accurate assembly histories of such galaxies are needed. However, these measurements are observationally difficult owing to the diversity of formation paths that lead to the same present-day state of a galaxy. In this work, we apply a powerful new technique
      Poci, A. et al.

      Advertised on:

      3
      2021
      Citations
      24
    • The number of globular clusters around the iconic UDG DF44 is as expected for dwarf galaxies
      There is a growing consensus that the vast majority of ultradiffuse galaxies (UDGs) are dwarf galaxies. However, there remain a few UDGs that seem to be special in terms of their globular cluster (GC) systems. In particular, according to some authors, certain UDGs exhibit large GC populations when compared to expectations from their stellar (or
      Saifollahi, Teymoor et al.

      Advertised on:

      4
      2021
      Citations
      47
    • Evaluating hydrodynamical simulations with green valley galaxies
      We test cosmological hydrodynamical simulations of galaxy formation regarding the properties of the blue cloud (BC), green valley (GV), and red sequence (RS), as measured on the 4000Å break strength versus stellar mass plane at z = 0.1. We analyse the RefL0100N1504 run of EAGLE and the TNG100 run of IllustrisTNG project, by comparing them with the
      Angthopo, J. et al.

      Advertised on:

      4
      2021
      Citations
      13
    • BAYES-LOSVD: A Bayesian framework for non-parametric extraction of the line-of-sight velocity distribution of galaxies
      We introduce BAYES-LOSVD, a novel implementation of the non-parametric extraction of line-of-sight velocity distributions (LOSVDs) in galaxies. We employed Bayesian inference to obtain robust LOSVDs and associated uncertainties. Our method relies on a principal component analysis to reduce the dimensionality on the set of templates required for the
      Falcón-Barroso, J. et al.

      Advertised on:

      2
      2021
      Citations
      11
    • Constraining stellar population parameters from narrow band photometric surveys using convolutional neural networks
      Upcoming large-area narrow band photometric surveys, such as Javalambre Physics of the Accelerating Universe Astrophysical Survey (J-PAS), will enable us to observe a large number of galaxies simultaneously and efficiently. However, it will be challenging to analyse the spatially resolved stellar populations of galaxies from such big data to
      Liew-Cain, Choong Ling et al.

      Advertised on:

      3
      2021
      Citations
      8
    • Galaxies within galaxies in the TIMER survey: stellar populations of inner bars are scaled replicas of main bars
      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
      Bittner, Adrian et al.

      Advertised on:

      2
      2021
      Citations
      10
    • The nature of giant clumps in high-z discs: a deep-learning comparison of simulations and observations
      We use deep learning to explore the nature of observed giant clumps in high-redshift disc galaxies, based on their identification and classification in cosmological simulations. Simulated clumps are detected using the 3D gas and stellar densities in the VELA zoom-in cosmological simulation suite, with ${\sim}25\ \rm {pc}$ maximum resolution
      Ginzburg, Omri et al.

      Advertised on:

      2
      2021
      Citations
      11
    • A deep learning approach to test the small-scale galaxy morphology and its relationship with star formation activity in hydrodynamical simulations
      Hydrodynamical simulations of galaxy formation and evolution attempt to fully model the physics that shapes galaxies. The agreement between the morphology of simulated and real galaxies, and the way the morphological types are distributed across galaxy scaling relations are important probes of our knowledge of galaxy formation physics. Here, we
      Zanisi, Lorenzo et al.

      Advertised on:

      3
      2021
      Citations
      53
    • The kinematics of young and old stellar populations in nuclear rings of MUSE TIMER galaxies
      Context. Studying the stellar kinematics of galaxies is a key tool in the reconstruction of their evolution. However, the current measurements of the stellar kinematics are complicated by several factors, including dust extinction and the presence of multiple stellar populations. Aims: We use integral field spectroscopic data of four galaxies from
      Rosado-Belza, D. et al.

      Advertised on:

      12
      2020
      Citations
      7
    • Galactic cirri in deep optical imaging
      The ubiquitous presence of Galactic cirri in deep optical images represents a major obstacle to study the low surface brightness features of extragalactic sources. To address this issue, we have explored the optical properties of cirri using g, r, i, and z bands in the Sloan Digital Sky Survey (SDSS) Stripe82 region. Using state-of-the-art, custom
      Román, Javier et al.

      Advertised on:

      12
      2020
      Citations
      83
    • The Galaxy "Missing Dark Matter" NGC 1052-DF4 is Undergoing Tidal Disruption
      The existence of long-lived galaxies lacking dark matter represents a challenge to our understanding of how galaxies form. Here, we present evidence that explains the lack of dark matter in one such galaxy: NGC 1052-DF4. Deep optical imaging of the system has detected tidal tails in this object caused by its interaction with its neighboring galaxy
      Montes, Mireia et al.

      Advertised on:

      12
      2020
      Citations
      50
    • Detecting outliers in astronomical images with deep generative networks
      With the advent of future big-data surveys, automated tools for unsupervised discovery are becoming ever more necessary. In this work, we explore the ability of deep generative networks for detecting outliers in astronomical imaging data sets. The main advantage of such generative models is that they are able to learn complex representations
      Margalef-Bentabol, Berta et al.

      Advertised on:

      6
      2020
      Citations
      38
    • Stellar masses of giant clumps in CANDELS and simulated galaxies using machine learning
      A significant fraction of high redshift star-forming disc galaxies are known to host giant clumps, whose nature and role in galaxy evolution are yet to be understood. In this work, we first present a new method based on neural networks to detect clumps in galaxy images. We use this method to detect clumps in the rest-frame optical and UV images of
      Huertas-Company, Marc et al.

      Advertised on:

      9
      2020
      Citations
      33
    • Inside-out formation of nuclear discs and the absence of old central spheroids in barred galaxies of the TIMER survey
      The centres of disc galaxies host a variety of structures built via both internal and external processes. In this study, we constrain the formation and evolution of these central structures, in particular, nuclear rings and nuclear discs, by deriving maps of mean stellar ages, metallicities, and [α/Fe] abundances. We use observations obtained with
      Bittner, Adrian et al.

      Advertised on:

      11
      2020
      Citations
      51
    • Kinematic signatures of nuclear discs and bar-driven secular evolution in nearby galaxies of the MUSE TIMER project
      The central regions of disc galaxies hold clues to the processes that dominate their formation and evolution. To exploit this, the TIMER project has obtained high signal-to-noise and spatial resolution integral-field spectroscopy data of the inner few kpc of 21 nearby massive barred galaxies, which allows studies of the stellar kinematics in their
      Gadotti, Dimitri A. et al.

      Advertised on:

      11
      2020
      Citations
      65

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