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

    • Breaks in Thin and Thick Disks of Edge-on Galaxies Imaged in the Spitzer Survey Stellar Structure in Galaxies (S4G)
      Breaks in the radial luminosity profiles of galaxies have until now been mostly studied averaged over disks. Here, we study separately breaks in thin and thick disks in 70 edge-on galaxies using imaging from the Spitzer Survey of Stellar Structure in Galaxies. We built luminosity profiles of the thin and thick disks parallel to midplanes and we
      Comerón, Sébastien et al.

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      11
      2012
      Citations
      81
    • Unveiling the Nature of M94's (NGC4736) Outer Region: A Panchromatic Perspective
      We have conducted a deep multiwavelength analysis (0.15-160 μm) to study the outer region of the nearby galaxy M94. We show that the non-optical data support the idea that the outskirts of this galaxy are not formed by a closed stellar ring (as traditionally claimed in the literature) but by a spiral arm structure. In this sense, M94 is a good
      Trujillo, I. et al.

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      10
      2009
      Citations
      24
    • Thick Disks of Edge-on Galaxies Seen through the Spitzer Survey of Stellar Structure in Galaxies (S4G): Lair of Missing Baryons?
      Most, if not all, disk galaxies have a thin (classical) disk and a thick disk. In most models thick disks are thought to be a necessary consequence of the disk formation and/or evolution of the galaxy. We present the results of a study of the thick disk properties in a sample of carefully selected edge-on galaxies with types ranging from T = 3 to T
      Comerón, Sébastien et al.

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      11
      2011
      Citations
      107
    • The Unusual Vertical Mass Distribution of NGC 4013 Seen through the Spitzer Survey of Stellar Structure in Galaxies (S4G)
      NGC 4013 is a nearby Sb edge-on galaxy known for its "prodigious" H I warp and its "giant" tidal stream. Previous work on this unusual object shows that it cannot be fitted satisfactorily by a canonical thin+thick disk structure. We have produced a new decomposition of NGC 4013, considering three stellar flattened components (thin+thick disk plus
      Comerón, Sébastien et al.

      Advertised on:

      9
      2011
      Citations
      24
    • The Thick Disk in the Galaxy NGC 4244 from S4G Imaging
      If thick disks are ubiquitous and a natural product of disk galaxy formation and/or evolution processes, all undisturbed galaxies that have evolved during a significant fraction of a Hubble time should have a thick disk. The late-type spiral galaxy NGC 4244 has been reported as the only nearby edge-on galaxy without a confirmed thick disk. Using
      Comerón, S. et al.

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      3
      2011
      Citations
      41
    • The S4G Perspective on Circumstellar Dust Extinction of Asymptotic Giant Branch Stars in M100
      We examine the effect of circumstellar dust extinction on the near-IR (NIR) contribution of asymptotic giant branch (AGB) stars in intermediate-age clusters throughout the disk of M100. For our sample of 17 AGB-dominated clusters we extract optical-to-mid-IR spectral energy distributions (SEDs) and find that NIR brightness is coupled to the mid-IR
      Meidt, Sharon E. et al.

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      4
      2012
      Citations
      17
    • The JCMT Nearby Galaxies Legacy Survey. VI. The distribution of gas and star formation in M 81
      We present the first complete 12CO J = 3-2 map of M 81, observed as part of the Nearby Galaxies Legacy Survey being carried out at the James Clerk Maxwell Telescope. We detect nine regions of significant CO emission located at different positions within the spiral arms, and confirm that the global CO emission in the galaxy is low. We combine these
      Sánchez-Gallego, J. R. et al.

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      3
      2011
      Citations
      8
    • The JCMT Nearby Galaxies Legacy Survey - VIII. CO data and the LCO(3-2)-LFIR correlation in the SINGS sample
      The James Clerk Maxwell Telescope Nearby Galaxies Legacy Survey (NGLS) comprises an H I-selected sample of 155 galaxies spanning all morphological types with distances less than 25 Mpc. We describe the scientific goals of the survey, the sample selection and the observing strategy. We also present an atlas and analysis of the CO J=3 - 2 maps for
      Wilson, C. D. et al.

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      8
      2012
      Citations
      73
    • The JCMT Nearby Galaxies Legacy Survey - VII. Hα imaging and massive star formation properties
      We present Hα fluxes, star formation rates (SFRs) and equivalent widths (EWs) for a sample of 156 nearby galaxies observed in the 12CO J= 3-2 line as part of the James Clerk Maxwell Telescope Nearby Galaxies Legacy Survey. These are derived from images and values in the literature and from new Hα images for 72 galaxies which we publish here. We
      Sánchez-Gallego, J. R. et al.

      Advertised on:

      6
      2012
      Citations
      25
    • The JCMT Nearby Galaxies Legacy Survey - V. The CO(J= 3-2) distribution and molecular outflow in NGC 4631
      We have made the first map of CO(J= 3-2) emission covering the disc of the edge-on galaxy, NGC 4631, which is known for its spectacular gaseous halo. The strongest emission, which we model with a Gaussian ring, occurs within a radius of 5 kpc. Weaker disc emission is detected out to radii of 12 kpc, the most extensive molecular component yet seen
      Irwin, Judith A. et al.

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      1
      2011
      Citations
      25
    • The JCMT Nearby Galaxies Legacy Survey - IV. Velocity dispersions in the molecular interstellar medium in spiral galaxies
      An analysis of large-area CO J= 3-2 maps from the James Clerk Maxwell Telescope for 12 nearby spiral galaxies reveals low velocity dispersions in the molecular component of the interstellar medium. The three lowest luminosity galaxies show a relatively flat velocity dispersion as a function of radius while the remaining nine galaxies show a central
      Wilson, C. D. et al.

      Advertised on:

      1
      2011
      Citations
      45
    • The JCMT Nearby Galaxies Legacy Survey - III. Comparisons of cold dust, polycyclic aromatic hydrocarbons, molecular gas and atomic gas in NGC 2403
      We used Spitzer Space Telescope 3.6, 8.0, 70 and 160μm data, James Clerk Maxwell Telescope HARP-B CO J = (3-2) data, National Radio Astronomy Observatory 12 m telescope CO J = (1-0) data and Very Large Array HI data to investigate the relations among polycyclic aromatic hydrocarbons (PAHs), cold (~20K) dust, molecular gas and atomic gas within NGC
      Bendo, G. J. et al.

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      3
      2010
      Citations
      63
    • The James Clerk Maxwell Telescope Nearby Galaxies Legacy Survey. II. Warm Molecular Gas and Star Formation in Three Field Spiral Galaxies
      We present the results of large-area 12CO J = 3-2 emission mapping of three nearby field galaxies, NGC 628, NGC 3521, and NGC 3627, completed at the James Clerk Maxwell Telescope as part of the Nearby Galaxies Legacy Survey. These galaxies all have moderate to strong 12CO J = 3-2 detections over large areas of the fields observed by the survey
      Warren, B. E. et al.

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      5
      2010
      Citations
      40
    • The James Clerk Maxwell Telescope Nearby Galaxies Legacy Survey. I. Star-Forming Molecular Gas in Virgo Cluster Spiral Galaxies
      We present large-area maps of the CO J = 3-2 emission obtained at the James Clerk Maxwell Telescope for four spiral galaxies in the Virgo Cluster. We combine these data with published CO J = 1-0, 24 μm, and Hα images to measure the CO line ratios, molecular gas masses, and instantaneous gas depletion times. For three galaxies in our sample (NGC
      Wilson, C. D. et al.

      Advertised on:

      3
      2009
      Citations
      96
    • The Hα Galaxy Survey. VIII. Close Companions and Interactions, and the Definition of Starbursts
      We consider the massive star formation properties, radial profiles, and atomic gas masses of those galaxies in our Hα Galaxy Survey that have close companion galaxies, in comparison with a matched control sample of galaxies without companions. Our analysis is based on Hα and continuum images of 327 disk galaxies that form a representative sample of
      Knapen, Johan H. et al.

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      6
      2009
      Citations
      83
    • The Hα galaxy survey. VII. The spatial distribution of star formation within disks and bulges
      Aims: We analyse the current build-up of stellar mass within the disks and bulges of nearby galaxies through a comparison of the spatial distributions of forming and old stellar populations. Methods: Hα and R-band imaging are used to determine the distributions of young and old stellar populations in 313 S0a-Im field galaxies out to ~40 Mpc
      James, P. A. et al.

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      7
      2009
      Citations
      63
    • The Hα Galaxy survey. IV. Star formation in the local Universe
      Aims: We present an analysis of the star formation properties of field galaxies within the local volume out to a recession velocity limit of 3000 km s-1. Methods: A parent sample of 863 star-forming galaxies is used to calculate a B-band luminosity function. This is then populated with star formation information from a subsample of 327 galaxies
      James, P. A. et al.

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      5
      2008
      Citations
      41
    • Spectroscopy of the archetype colliding-wind binary WR 140 during the 2009 January periastron passage
      We present the results from the spectroscopic monitoring of WR 140 (WC7pd + O5.5fc) during its latest periastron passage in 2009 January. The observational campaign consisted of a constructive collaboration between amateur and professional astronomers. It took place at six locations, including Teide Observatory, Observatoire de Haute Provence
      Fahed, R. et al.

      Advertised on:

      11
      2011
      Citations
      46
    • Reconstructing the Stellar Mass Distributions of Galaxies Using S4G IRAC 3.6 and 4.5 μm Images. I. Correcting for Contamination by Polycyclic Aromatic Hydrocarbons, Hot Dust, and Intermediate-age Stars
      With the aim of constructing accurate two-dimensional maps of the stellar mass distribution in nearby galaxies from Spitzer Survey of Stellar Structure in Galaxies 3.6 and 4.5 μm images, we report on the separation of the light from old stars from the emission contributed by contaminants. Results for a small sample of six disk galaxies (NGC 1566
      Meidt, Sharon E. et al.

      Advertised on:

      1
      2012
      Citations
      158
    • Photometric scaling relations of lenticular and spiral galaxies
      Photometric scaling relations are studied for S0 galaxies and compared with those obtained for spirals. New two-dimensional multi-component decompositions are presented for 122 early-type disc galaxies, using deep Ks-band images. Combining them with our previous decompositions, the final sample consists of 175 galaxies (Near-Infrared Survey of S0s
      Laurikainen, E. et al.

      Advertised on:

      6
      2010
      Citations
      204

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