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).

    Here you can find some of our most recent highlights:

    Related publications

    • The Formation of Shell Galaxies Similar to NGC 7600 in the Cold Dark Matter Cosmogony

      We present new deep observations of "shell" structures in the halo of the nearby elliptical galaxy NGC 7600, alongside a movie of galaxy formation in a cold dark matter (CDM) universe. The movie, based on an ab initio cosmological simulation, shows how continuous accretion of clumps of dark matter and stars creates a swath of diffuse circumgalactic

      Cooper, Andrew P. et al.

      Advertised on:

      12
      2011
      Citations
      47
    • Outer density profiles of 19 Galactic globular clusters from deep and wide-field imaging

      Using deep photometric data from Wide Field Camera at the Isaac Newton Telescope and Wide Field Imager at the ESO 2.2-m telescope we measure the outer number density profiles of 19 stellar clusters located in the inner region of the Milky Way halo (within a Galactocentric distance range of 10-30 kpc) in order to assess the impact of internal and

      Carballo-Bello, J. A. et al.

      Advertised on:

      1
      2012
      Citations
      63
    • COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses. IX. Time delays, lens dynamics and baryonic fraction in HE 0435-1223

      We present accurate time delays for the quadruply imaged quasar HE 0435-1223. The delays were measured from 575 independent photometric points obtained in the R-band between January 2004 and March 2010. With seven years of data, we clearly show that quasar image A is affected by strong microlensing variations and that the time delays are best

      Courbin, F. et al.

      Advertised on:

      12
      2011
      Citations
      106
    • Age and metallicity gradients in early-type galaxies: a dwarf-to-giant sequence

      We studied the stellar populations of 40 early-type galaxies using medium-resolution long-slit spectroscopy along their major axes (and along the minor axis for two of them). The sample, including elliptical and lenticular galaxies as well as dwarf galaxies, is combined with other previously published data in order to discuss the systematics of the

      Koleva, M. et al.

      Advertised on:

      11
      2011
      Citations
      116
    • A journey from the outskirts to the cores of groups. I. Color- and mass-segregation in 20K-zCOSMOS groups

      Context. Studying theevolution of galaxies located within groups may have important implications for our understanding of the global evolution of the galaxy population as a whole. The fraction of galaxies bound in groups at z ~ 0 is as high as 60% and therefore any mechanism (among the many suggested) that could quench star formation when a galaxy

      Presotto, V. et al.

      Advertised on:

      3
      2012
      Citations
      35
    • Stellar population models in the UV. I. Characterisation of the New Generation Stellar Library

      Context. The spectral predictions of stellar population models are not as accurate in the ultra-violet (UV) as in the optical wavelength domain. One of the reasons is the lack of high-quality stellar libraries. The New Generation Stellar Library (NGSL), recently released, represents a significant step towards the improvement of this situation. Aims

      Koleva, M. et al.

      Advertised on:

      2
      2012
      Citations
      84
    • Mg and TiO spectral features at the near-IR: spectrophotometric index definitions and empirical calibrations

      Using the near-infrared spectral stellar library of Cenarro et al., the behaviour of the MgI line at 8807 Å and nearby TiO bands is analyzed in terms of the effective temperature, surface gravity and metallicity of the library stars. New spectroscopic indices for both spectral features - namely MgI and sTiO - are defined, and their sensitivities to

      Cenarro, A. J. et al.

      Advertised on:

      7
      2009
      Citations
      21
    • Field O stars: formed in situ or as runaways?

      A significant fraction of massive stars in the Milky Way and other galaxies are located far from star clusters and star-forming regions. It is known that some of these stars are runaways, i.e. possess high space velocities (determined through the proper motion and/or radial velocity measurements), and therefore most likely were formed in embedded

      Gvaramadze, V. V. et al.

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      8
      2012
      Citations
      82
    • Evidence of a Distinct Stellar Population in the Counterrotating Core of NGC 1700

      We find a distinct stellar population in the counterrotating and kinematically decoupled core of the isolated massive elliptical galaxy NGC 1700. Coinciding with the edge of this core, we find a significant change in the slope of the gradient of various representative absorption line indices. Our age estimate for this core is markedly younger than

      Kleineberg, K. et al.

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      5
      2011
      Citations
      8
    • Evidence for Blue Straggler Stars Rejuvenating the Integrated Spectra of Globular Clusters

      Integrated spectroscopy is the method of choice for deriving the ages of unresolved stellar systems. However, hot stellar evolutionary stages, such as hot horizontal branch stars and blue straggler stars (BSSs), can affect the integrated ages measured using Balmer lines. Such hot, ``noncanonical'' stars may lead to overestimation of the temperature

      Cenarro, A. Javier et al.

      Advertised on:

      12
      2008
      Citations
      24
    • An optimized Hβ index for disentangling stellar population ages

      We have defined a new Hβ absorption index definition, Hβo, which has been optimized as an age indicator for old and intermediate age stellar populations. Rather than using stellar spectra, we employed for this purpose a library of stellar population spectral energy distributions of different ages and metallicities at moderately high resolution. Hβo

      Cervantes, J. L. et al.

      Advertised on:

      1
      2009
      Citations
      66
    • 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.

      Advertised on:

      10
      2009
      Citations
      24
    • The Hubble Space Telescope GOODS NICMOS Survey: overview and the evolution of massive galaxies at 1.5< z< 3

      We present the details and early results from a deep near-infrared survey utilizing the NICMOS instrument on the Hubble Space Telescope centred around massive M* > 1011 M&sun; galaxies at 1.7 < z < 2.9 found within the Great Observatories Origins Deep Survey (GOODS) fields North and South. The GOODS NICMOS Survey (GNS) was designed to obtain deep

      Conselice, C. J. et al.

      Advertised on:

      5
      2011
      Citations
      93
    • The Ghost of a Dwarf Galaxy: Fossils of the Hierarchical Formation of the Nearby Spiral Galaxy NGC 5907

      We present an extragalactic perspective of an extended stellar tidal stream wrapping around the edge-on spiral galaxy NGC 5907. Our deep images reveal for the first time a large-scale complex of arcing loops that is an excellent example of how low-mass satellite accretion can produce an interwoven, rosette-like structure of debris dispersed in the

      Martínez-Delgado, David et al.

      Advertised on:

      12
      2008
      Citations
      140
    • The evolutionary sequence of submillimetre galaxies: from diffuse discs to massive compact ellipticals?

      The population of compact massive galaxies observed at z > 1 is hypothesized, both observationally and in simulations, to be merger remnants of gas-rich disc galaxies. To probe such a scenario, we analyse a sample of 12 gas-rich and active star-forming submillimetre galaxies (SMGs) at 1.8 < z < 3. We present a structural and size measurement

      Ricciardelli, E. et al.

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      7
      2010
      Citations
      44
    • Size Evolution of the Most Massive Galaxies at 1.7 < z < 3 from GOODS NICMOS Survey Imaging

      We measure the sizes of 82 massive (M>=1011 Msolar) galaxies at 1.72 our results are compatible with both a leveling off, or a mild evolution in size. Furthermore, the high density (~2 × 1010 Msolar kpc-3) of massive galaxies at these redshifts, which are similar to present-day globular clusters, possibly makes any further evolution in sizes beyond

      Buitrago, Fernando et al.

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      11
      2008
      Citations
      383
    • Satellites around Massive Galaxies Since z ~ 2: Confronting the Millennium Simulation with Observations

      Minor merging has been postulated as the most likely evolutionary path to produce the increase in size and mass observed in the massive galaxies since z ~ 2. In this Letter, we directly test this hypothesis, comparing the population of satellites around massive galaxies in cosmological simulations versus the observations. We use state-of-the-art

      Quilis, Vicent et al.

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      6
      2012
      Citations
      21
    • Mild Velocity Dispersion Evolution of Spheroid-Like Massive Galaxies Since z ~ 2

      Making use of public spectra from Cimatti et al., we measure for the first time the velocity dispersion of spheroid-like massive (M sstarf ~ 1011 M sun) galaxies at z ~ 1.6. By comparing with galaxies of similar stellar mass at lower redshifts, we find evidence for a mild evolution in velocity dispersion, decreasing from ~240 km s-1 at z ~ 1.6 down

      Cenarro, A. Javier et al.

      Advertised on:

      5
      2009
      Citations
      113
    • Measuring star formation in high-z massive galaxies: a mid-infrared to submillimetre study of the GOODS NICMOS Survey sample

      We present measurements of the mean mid-infrared to submillimetre flux densities of massive (M★≳ 1011 M&sun;) galaxies at redshifts 1.7 < z < 2.9, obtained by stacking positions of known objects taken from the GOODS NICMOS Survey (GNS) catalogue on maps at 24 ?m (Spitzer/MIPS); 70, 100 and 160 ?m (Herschel/PACS); 250, 350 and 500 ?m (BLAST); and

      Viero, M. P. et al.

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      4
      2012
      Citations
      29
    • Gemini K-band NIRI Adaptive Optics Observations of massive galaxies at 1 < z < 2

      We present deep K-band adaptive-optics observations of eight very massive (M* ~ 4 × 1011Msolar) galaxies at 1 < z < 2 utilizing the Gemini NIRI/Altair Laser Guide System. These systems are selected from the Palomar Observatory Wide-Field Infrared survey, and are amongst the most massive field galaxies at these epochs. The depth and high spatial

      Carrasco, Eleazar R. et al.

      Advertised on:

      7
      2010
      Citations
      53

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