Spiral Galaxies: Evolution and Consequences

    General
    Description

    Our small group is well known and respected internationally for our innovative and important work on various aspects of the structure and evolution of nearby spiral galaxies. We primarily use observations at various wavelengths, exploiting synergies that allow us to answer the most pertinent questions relating to what the main properties of galaxies are, and how galaxies have evolved to their current state. We use imaging and spectroscopy, at UV, optical, infrared, millimetre, and radio wavelengths, fully exploiting observing facilities available to us in Spain, at ESO, or elsewhere, along with state-of-the-art analysis tools. The success of this approach can be measured from the employment opportunities offered to ex-members of the group, from the number and quality of collaborations with leading external scientists, from continued citation of our published work, and from invitations to co-organise or speak at the leading international conferences in the field.

    In the last few years our group has put a lot of effort into opening up joint research lines with computer scientists, recognising the paradigm shift that is upon us due to the enormous quantities of data that will soon be produced by facilities such as LSST, Euclid, and SKA. We collaborate with computer scientists and aim to prepare the analysis tools, including detection of structure from noise, correction for scattered light and Galactic cirrus, and the use of machine learning-based techniques, so that once LSST (2020) and Euclid (2023) start releasing their huge data sets, our group is ready to analyse them and extract the science from the oceans of bytes.

    Principal investigator
    Project staff
    1. From thermal and non-thermal radio maps of the centre of NGC 1097, we discovered that the massive star formation is quenched by non-thermal effects, including pressure from the magnetic field, cosmic rays and turbulence.
    2. In the centre of NGC 7742, we found a slightly warped inner disk, and two separate stellar components: an old population that counter-rotates with the gas, and a young one, concentrated to the ring, that co-rotates with the gas.
    3. We re-analysed our deep IR imaging of thick disks to correct for the extended S4G point spread function (PSF), confirming all our previous results and in particular confirming the significant mass present in the thick disk component.
    4. Analysing a new high-resolution e-MERLIN 1.5 GHz radio continuum map together with HST and SDSS imaging of NGC 5322, an elliptical galaxy hosting radio jets, we found that the low-luminosity AGN/jet-driven feedback may have quenched the late-time nuclear star formation promptly.
    5. From MUSE observations of low-surface-brightness Lyman-α emission surrounding faint galaxies at redshifts between 3 and 6 we find that the projected sky coverage approaches 100 per cent.

    Related publications

    • ARRAKIS: atlas of resonance rings as known in the S4G
      Context. Resonance rings and pseudorings (here collectively called rings) are thought to be related to the gathering of material near dynamical resonances caused by non-axisymmetries in galaxy discs. This means that they are the result of secular evolution processes that redistribute material and angular momentum in discs. Studying them may give
      Comerón, S. et al.

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      2
      2014
      Citations
      96
    • Unveiling the Structure of Barred Galaxies at 3.6 μm with the Spitzer Survey of Stellar Structure in Galaxies (S4G). I. Disk Breaks
      We have performed two-dimensional multicomponent decomposition of 144 local barred spiral galaxies using 3.6 μm images from the Spitzer Survey of Stellar Structure in Galaxies. Our model fit includes up to four components (bulge, disk, bar, and a point source) and, most importantly, takes into account disk breaks. We find that ignoring the disk
      Seibert, Mark et al.

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      2
      2014
      Citations
      46
    • The circumnuclear environment of NGC 613: a nuclear starburst caught in the act?
      We present near-infrared (H- and K-band) integral-field observations of the inner ˜700 pc of the active spiral galaxy NGC 613, obtained with SINFONI on the Very Large Telescope. We use emission-line ratios to determine the dominant excitation mechanisms in different regions within our field of view, in particular, the active nucleus and the star
      Lançon, A. et al.

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      2
      2014
      Citations
      34
    • Morphological Parameters of a Spitzer Survey of Stellar Structure in Galaxies
      The morphology of galaxies can be quantified to some degree using a set of scale-invariant parameters. Concentration (C), asymmetry (A), smoothness (S), the Gini index (G), the relative contribution of the brightest pixels to the second-order moment of the flux (M 20), ellipticity (E), and the Gini index of the second-order moment (GM ) have all
      Holwerda, B. W. et al.

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      1
      2014
      Citations
      31
    • Embedded Star Formation in S4G Galaxy Dust Lanes
      Star-forming regions that are visible at 3.6 μm and Hα but not in the u, g, r, i, z bands of the Sloan Digital Sky Survey are measured in five nearby spiral galaxies to find extinctions averaging ~3.8 mag and stellar masses averaging ~5 × 104 M ☉. These regions are apparently young star complexes embedded in dark filamentary shock fronts connected
      Mizusawa, Trisha et al.

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      1
      2014
      Citations
      17
    • Interlocking Resonance Patterns in Galaxy Disks
      We have developed a method for finding dynamical resonances in disk galaxies using the change in sense of the radial component of the in-plane velocity at a resonance radius. Using simulations we show that we would expect to find these changes at corotation radii with a weaker effect at the Lindblad resonances. The method works well with
      Querejeta, M. et al.

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      1
      2014
      Citations
      38
    • Shock Excited Molecules in NGC 1266: ULIRG Conditions at the Center of a Bulge-dominated Galaxy
      We investigate the far infrared (IR) spectrum of NGC 1266, a S0 galaxy that contains a massive reservoir of highly excited molecular gas. Using the Herschel Fourier Transform Spectrometer, we detect the 12CO ladder up to J = (13-12), [C I] and [N II] lines, and also strong water lines more characteristic of UltraLuminous IR Galaxies (ULIRGs). The
      Dale, D. A. et al.

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      12
      2013
      Citations
      43
    • Massive star formation in galaxies with excess ultraviolet emission
      From an analysis of almost 2000 Galaxy Evolution Explorer images of galaxies with morphological types ranging from E to Sab, we have found a significant subset (28 per cent) that show ultraviolet (UV) emission outside R25. We have obtained Hα imaging of 10 such galaxies, and found that their star formation rates are similar in the UV and in Hα
      Hagen, Lea M. Z. et al.

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      12
      2013
      Citations
      6
    • The bifurcated age-metallicity relation of Milky Way globular clusters and its implications for the accretion history of the galaxy
      We use recently derived ages for 61 Milky Way (MW) globular clusters (GCs) to show that their age-metallicity relation (AMR) can be divided into two distinct, parallel sequences at [Fe/H] ≳ -1.8. Approximately one-third of the clusters form an offset sequence that spans the full range in age (˜10.5-13 Gyr), but is more metal rich at a given age by
      Leaman, R. et al.

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      11
      2013
      Citations
      197
    • The James Clerk Maxwell Telescope Nearby Galaxies Legacy Survey - IX. 12CO J = 3→2 observations of NGC 2976 and NGC 3351
      We present 12CO J = 3→2 maps of NGC 2976 and NGC 3351 obtained with the James Clerk Maxwell Telescope (JCMT), both early targets of the JCMT Nearby Galaxy Legacy Survey (NGLS). We combine the present observations with 12CO J = 1→0 data and find that the computed 12CO J = 3→2 to 12CO J = 1→0 line ratio (R31) agrees with values measured in other NGLS
      Tan, Boon-Kok et al.

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      11
      2013
      Citations
      8
    • X-Ray Nuclear Activity in S4G Barred Galaxies: No Link between Bar Strength and Co-occurrent Supermassive Black Hole Fueling
      Stellar bars can lead to gas inflow toward the center of a galaxy and stimulate nuclear star formation. However, there is no compelling evidence on whether they also feed a central supermassive black hole: by measuring the fractions of barred active and inactive galaxies, previous studies have yielded conflicting results. In this paper, we aim to
      Cisternas, M. et al.

      Advertised on:

      10
      2013
      Citations
      51
    • The Ages of 55 Globular Clusters as Determined Using an Improved \Delta V^HB_TO Method along with Color-Magnitude Diagram Constraints, and Their Implications for Broader Issues
      Ages have been derived for 55 globular clusters (GCs) for which Hubble Space Telescope Advanced Camera for Surveys photometry is publicly available. For most of them, the assumed distances are based on fits of theoretical zero-age horizontal-branch (ZAHB) loci to the lower bound of the observed distributions of HB stars, assuming reddenings from
      VandenBerg, D. A. et al.

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      10
      2013
      Citations
      396
    • On the Origin of Lopsidedness in Galaxies as Determined from the Spitzer Survey of Stellar Structure in Galaxies (S4G)
      We study the m = 1 distortions (lopsidedness) in the stellar components of 167 nearby galaxies that span a wide range of morphologies and luminosities. We confirm the previous findings of (1) a high incidence of lopsidedness in the stellar distributions, (2) increasing lopsidedness as a function of radius out to at least 3.5 exponential scale
      Zaritsky, Dennis et al.

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      8
      2013
      Citations
      47
    • The Impact of Bars on Disk Breaks as Probed by S4G Imaging
      We have analyzed the radial distribution of old stars in a sample of 218 nearby face-on disks, using deep 3.6 μm images from the Spitzer Survey of Stellar Structure in Galaxies. In particular, we have studied the structural properties of those disks with a broken or down-bending profile. We find that, on average, disks with a genuine single
      Muñoz-Mateos, Juan Carlos et al.

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      7
      2013
      Citations
      109
    • The Comparative Chemical Evolution of an Isolated Dwarf Galaxy: A VLT and Keck Spectroscopic Survey of WLM
      Building on our previous spectroscopic and photometric analysis of the isolated Local Group dwarf irregular (dIrr) galaxy WLM, we present a comparison of the metallicities of its red giant branch stars with respect to the well-studied Local Group dwarf spheroidal galaxies (dSphs) and Magellanic Clouds. We calculate a mean metallicity of [Fe/H] =–1
      Tolstoy, Eline et al.

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      4
      2013
      Citations
      82
    • The 2011 Periastron Passage of the Be Binary δ Scorpii
      We describe the results of the world-wide observing campaign of the highly eccentric Be binary system δ Scorpii 2011 periastron passage which involved professional and amateur astronomers. Our spectroscopic observations provided a precise measurement of the system orbital period at 10.8092 ± 0.0005 yr. Fitting of the He II 4686 Å line radial
      Reinecke, N. et al.

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      4
      2013
      Citations
      18
    • Hydrogen volume densities in nearby galaxies - I. An automated approach
      Using a simple model of photodissociated atomic hydrogen on a galactic scale, it is possible to derive total hydrogen volume densities. These densities, obtained through a combination of atomic hydrogen, far-ultraviolet and metallicity data, provide an independent probe of the combined atomic and molecular hydrogen gas in galactic discs. We present
      Knapen, J. H. et al.

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      2
      2013
      Citations
      4
    • Hα kinematics of S4G spiral galaxies - I. NGC 864
      We present a study of the kinematics of the isolated spiral galaxy NGC 864, using Hα Fabry-Perot data obtained with the Galaxy Hα Fabry-Perot System (GHαFaS) instrument at the William Herschel Telescope in La Palma, complemented with images at 3.6 μm, in the R band and in Hα filter, and integral-field spectroscopic data. The resulting data cubes
      Seibert, Mark et al.

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      12
      2012
      Citations
      20
    • A unified picture of breaks and truncations in spiral galaxies from SDSS and S4G imaging
      The mechanism causing breaks in the radial surface-brightness distribution of spiral galaxies is not yet well known. Despite theoretical efforts, there is not a unique explanation for these features and the observational results are not conclusive. In an attempt to address this problem, we have selected a sample of 34 highly inclined spiral
      Seibert, Mark et al.

      Advertised on:

      12
      2012
      Citations
      61
    • Spectral Energy Distributions of Type 1 Active Galactic Nuclei in the COSMOS Survey. I. The XMM-COSMOS Sample
      The "Cosmic Evolution Survey" (COSMOS) enables the study of the spectral energy distributions (SEDs) of active galactic nuclei (AGNs) because of the deep coverage and rich sampling of frequencies from X-ray to radio. Here we present an SED catalog of 413 X-ray (XMM-Newton)-selected type 1 (emission line FWHM > 2000 km s–1) AGNs with Magellan, SDSS
      Elvis, M. et al.

      Advertised on:

      11
      2012
      Citations
      69

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