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

    • Triggered star formation in a merging, gas-rich dwarf galaxy around NGC 7241
      Using multiwavelength kinematic and photometric data we have analysed the gaseous and stellar properties of a previously uncharacterized low-mass star-forming companion and newly discovered stellar stream seen projected against the edge-on spiral galaxy NGC 7241. The companion object was identified serendipitously as an offset velocity component in
      Leaman, R. et al.

      Advertised on:

      7
      2015
      Citations
      5
    • A Classical Morphological Analysis of Galaxies in the Spitzer Survey of Stellar Structure in Galaxies (S4G)
      The Spitzer Survey of Stellar Structure in Galaxies (S4G) is the largest available database of deep, homogeneous middle-infrared (mid-IR) images of galaxies of all types. The survey, which includes 2352 nearby galaxies, reveals galaxy morphology only minimally affected by interstellar extinction. This paper presents an atlas and classifications of
      Buta, R. J. et al.

      Advertised on:

      4
      2015
      Citations
      239
    • Liverpool telescope 2: a new robotic facility for rapid transient follow-up
      The Liverpool Telescope is one of the world's premier facilities for time domain astronomy. The time domain landscape is set to radically change in the coming decade, with synoptic all-sky surveys such as LSST providing huge numbers of transient detections on a nightly basis; transient detections across the electromagnetic spectrum from other major
      Copperwheat, C. M. et al.

      Advertised on:

      3
      2015
      Citations
      13
    • Stellar population synthesis models between 2.5 and 5 μm based on the empirical IRTF stellar library
      We present the first single-burst stellar population models in the infrared wavelength range between 2.5 and 5 μm which are exclusively based on empirical stellar spectra. Our models take as input 180 spectra from the stellar IRTF (Infrared Telescope Facility) library. Our final single-burst stellar population models are calculated based on two
      Röck, B. et al.

      Advertised on:

      5
      2015
      Citations
      46
    • The Role of Bars in AGN Fueling in Disk Galaxies Over the Last Seven Billion Years
      We present empirical constraints on the influence of stellar bars on the fueling of active galactic nuclei (AGNs) out to z = 0.84 using a sample of X-ray-selected AGNs hosted in luminous non-interacting face-on and moderately inclined disk galaxies from the Chandra COSMOS survey. Using high-resolution Hubble Space Telescope imaging to identify bars
      Cisternas, M. et al.

      Advertised on:

      4
      2015
      Citations
      40
    • Spectroscopic variability of two Oe stars
      Context. The two Oe stars HD 45 314 and HD 60 848 have recently been found to exhibit very different X-ray properties: whilst HD 60 848 has an X-ray spectrum and the emission level typical of most OB stars, HD 45 314 features a much harder and brighter X-ray emission, making it a so-called γ Cas analogue. Aims: Monitoring the optical spectra could
      Rauw, G. et al.

      Advertised on:

      3
      2015
      Citations
      4
    • Globular Cluster Populations: First Results from S4G Early-type Galaxies
      Using 3.6 μm images of 97 early-type galaxies, we develop and verify methodology to measure globular cluster populations from the S4G survey images. We find that (1) the ratio, T N, of the number of clusters, N CL, to parent galaxy stellar mass, M *, rises weakly with M * for early-type galaxies with M * > 1010 M ☉ when we calculate galaxy masses
      Zaritsky, D. et al.

      Advertised on:

      2
      2015
      Citations
      11
    • The GALEX/S4G UV–IR Color–Color Diagram: Catching Spiral Galaxies Away from the Blue Sequence
      We obtained GALEX FUV, NUV, and Spitzer/IRAC 3.6 μm photometry for \gt 2000 galaxies, available for 90% of the S4G sample. We find a very tight GALEX blue sequence (GBS) in the (FUV–NUV) versus (NUV–[3.6]) color–color diagram, which is populated by irregular and spiral galaxies, and is mainly driven by changes in the formation timescale (τ) and a
      Bouquin, A. Y. K. et al.

      Advertised on:

      2
      2015
      Citations
      16
    • The Mass Profile and Shape of Bars in the Spitzer Survey of Stellar Structure in Galaxies (S4G): Search for an Age Indicator for Bars
      We have measured the radial light profiles and global shapes of bars using two-dimensional 3.6 μm image decompositions for 144 face-on barred galaxies from the Spitzer Survey of Stellar Structure in Galaxies. The bar surface brightness profile is correlated with the stellar mass and bulge-to-total (B/T) ratio of their host galaxies. Bars in massive
      Kim, T. et al.

      Advertised on:

      1
      2015
      Citations
      34
    • Overview of the SDSS-IV MaNGA Survey: Mapping nearby Galaxies at Apache Point Observatory
      We present an overview of a new integral field spectroscopic survey called MaNGA (Mapping Nearby Galaxies at Apache Point Observatory), one of three core programs in the fourth-generation Sloan Digital Sky Survey (SDSS-IV) that began on 2014 July 1. MaNGA will investigate the internal kinematic structure and composition of gas and stars in an
      Bundy, K. et al.

      Advertised on:

      1
      2015
      Citations
      1000
    • Evidence for the concurrent growth of thick discs and central mass concentrations from S4G imaging
      We have produced 3.6 μm + 4.5 μm vertically integrated radial luminosity profiles of 69 edge-on galaxies from the Spitzer Survey of Stellar Structure in Galaxies (S4G). We decomposed the luminosity profiles into a disc and a central mass concentration (CMC). These fits, combined with thin/thick disc decompositions from our previous studies, allow
      Comerón, S. et al.

      Advertised on:

      11
      2014
      Citations
      37
    • Two physical regimes for the giant H II regions and giant molecular clouds in the Antennae galaxies
      We have combined observations of the Antennae galaxies from the radio interferometer ALMA (Atacama Large Millimeter/submillimeter Array) and from the optical interferometer GHαFaS (Galaxy Hα Fabry-Perot System). The two sets of observations have comparable angular and spectral resolutions, enabling us to identify 142 giant molecular clouds (GMCs)
      Zaragoza-Cardiel, J. et al.

      Advertised on:

      12
      2014
      Citations
      20
    • A search for stellar tidal debris of defunct dwarf galaxies around globular clusters in the inner Galactic halo
      In the hierarchical formation scenario in which the outer halo of the Milky Way is the result of the continuous accretion of low-mass galaxies, a fraction of the Galactic globular cluster system might have originated in and been accreted with already extinct dwarf galaxies. In this context, we expect that the remnants of these progenitor galaxies
      Carballo-Bello, J. A. et al.

      Advertised on:

      12
      2014
      Citations
      44
    • Delayed Star Formation in Isolated Dwarf galaxies: Hubble Space Telescope Star Formation History of the Aquarius Dwarf Irregular
      We have obtained deep images of the highly isolated (d = 1 Mpc) Aquarius dwarf irregular galaxy (DDO 210) with the Hubble Space Telescope Advanced Camera for Surveys. The resulting color-magnitude diagram (CMD) reaches more than a magnitude below the oldest main-sequence turnoff, allowing us to derive the star formation history (SFH) over the
      Cole, A. A. et al.

      Advertised on:

      11
      2014
      Citations
      59
    • Spitzer/Infrared Array Camera near-infrared features in the outer parts of S4G galaxies
      We present a catalogue and images of visually detected features, such as asymmetries, extensions, warps, shells, tidal tails, polar rings, and obvious signs of mergers or interactions, in the faint outer regions (at and outside of R25) of nearby galaxies. This catalogue can be used in future quantitative studies that examine galaxy evolution due to
      Laine, S. et al.

      Advertised on:

      11
      2014
      Citations
      15
    • Optical imaging for the Spitzer Survey of Stellar Structure in Galaxies. Data release and notes on interacting galaxies
      Context. The Spitzer Survey for Stellar Structure in Galaxies (S4G) and its more recently approved extension will lead to a set of 3.6 and 4.5 μm images for 2829 galaxies, which can be used to study many different aspects of the structure and evolution of local galaxies. Aims: We have collected and re-reduced optical images of 1768 of the survey
      Knapen, J. H. et al.

      Advertised on:

      9
      2014
      Citations
      29
    • Reconstructing the Stellar Mass Distributions of Galaxies Using S4G IRAC 3.6 and 4.5 μm Images. II. The Conversion from Light to Mass
      We present a new approach for estimating the 3.6 μm stellar mass-to-light (M/L) ratio Upsilon3.6 in terms of the [3.6]-[4.5] colors of old stellar populations. Our approach avoids several of the largest sources of uncertainty in existing techniques using population synthesis models. By focusing on mid-IR wavelengths, we gain a virtually dust
      Meidt, S. E. et al.

      Advertised on:

      6
      2014
      Citations
      213
    • Stellar haloes outshine disc truncations in low-inclined spirals
      The absence of stellar disc truncations in low-inclined spiral galaxies has been a matter of debate in the last decade. Disc truncations are often observed in highly inclined galaxies but no obvious detection of this feature has so far been made in face-on spirals. Here we show, using a simple exponential disc plus stellar halo model based on
      Martín-Navarro, I. et al.

      Advertised on:

      7
      2014
      Citations
      25
    • Morphology and environment of galaxies with disc breaks in the S4G and NIRS0S
      We study the surface brightness profiles of disc galaxies in the 3.6 μm images from the Spitzer Survey of Stellar Structure in Galaxies (S4G) and Ks-band images from the Near-Infrared S0-Sa galaxy Survey (NIRS0S). We particularly connect properties of single exponential (type I), downbending double exponential (type II), and upbending double
      Laine, J. et al.

      Advertised on:

      7
      2014
      Citations
      60
    • The Baryonic Tully-Fisher Relationship for S4G Galaxies and the "Condensed" Baryon Fraction of Galaxies
      We combine data from the Spitzer Survey for Stellar Structure in Galaxies, a recently calibrated empirical stellar mass estimator from Eskew et al., and an extensive database of H I spectral line profiles to examine the baryonic Tully-Fisher (BTF) relation. We find (1) that the BTF has lower scatter than the classic Tully-Fisher (TF) relation and
      Zaritsky, D. et al.

      Advertised on:

      6
      2014
      Citations
      72

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