Patricia Sanchez-Blazquez

Universidad Autónoma de Madrid, Madrid, Madrid, Spain

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Publications (49)129.02 Total impact

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    ABSTRACT: Aims. Using a suite of cosmological chemodynamical disc galaxy simulations, we assess how (a) radial metallicity gradients evolve with scaleheight; (b) the vertical metallicity gradients change through the thick disc; and (c) the vertical gradient of the stellar rotation velocity varies through the disc. We compare with the Milky Way to search for analogous trends. Methods. We analyse five simulated spiral galaxies with masses comparable to the Milky Way. The simulations span a range of star formation and energy feedback strengths and prescriptions, particle- and grid-based hydrodynamical implementations, as well as initial conditions/assembly history. Results. Consistently, we find that the steeper, negative, radial metallicity gradients seen in the mid-plane flatten with increasing height away from the plane. In simulations with stronger (and/or more spatially-extended) feedback, the negative radial gradients invert, becoming positive for heights in excess of 1 kpc. Such behaviour is consistent with that inferred from recent observations. Our measurements of the vertical metallicity gradients show no clear correlation with galactocentric radius, and are in good agreement with those observed in the Milky Way's thick disc (locally). Conclusions. Simulations employing stronger/more extended feedback prescriptions possess radial and vertical metallicity and kinematic gradients more in line with recent observations. The inverted, positive, radial metallicity gradients seen in the simulated thick stellar discs originate from a population of younger, more metal-rich, stars formed in-situ, superimposed upon a background population of older migrators from the inner disc; the contrast provided by the former increases radially, due to the inside-out growth of the disc. A similar behaviour may be responsible for the same flattening seen in the radial gradients with scaleheight in the Milky Way.
    Preview · Article · Dec 2015 · Astronomy and Astrophysics
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    Anna Ferré-Mateu · Patricia Sánchez-Blázquez · Alexandre Vazdekis · Ignacio G. de la Rosa
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    ABSTRACT: We present a detailed stellar population analysis for a sample of 24 early-type galaxies belonging to the rich cluster RXJ0152.7-1357 at z=0.83. We have derived the age, metallicity, abundance pattern and star formation history for each galaxy individually, to further characterize this intermediate-z reference cluster. We then study how these stellar population parameters depend on local environment. This provides a better understanding on the formation timescales and subsequent evolution of the substructures in this cluster. We have also explored the evolutionary link between z$\sim$0.8 ETGs and those in the local Universe by comparing the trends that the stellar population parameters follow with galaxy velocity dispersion at each epoch. We find that the ETGs in Coma are consistent with being the (passively-evolving) descendants of the ETG population in RXJ10152.7-1357. Furthermore, our results favor a downsizing picture, where the subclumps centers were formed first. This central parts contain the most massive galaxies, which formed the bulk of their stars in a short, burst-like event at high-z. On the contrary, the cluster outskirts are populated with less massive, smaller galaxies, which show a wider variety of Star Formation Histories. In general, they present extended star formation episodes over cosmic time, which seems to be related to their posterior incorporation into the cluster, around 4Gyr later after the initial event of formation.
    Preview · Article · Oct 2014 · The Astrophysical Journal
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    Ignacio Trujillo · Anna Ferre-Mateu · Marc Balcells · Alexandre Vazdekis · Patricia Sanchez-Blazquez
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    ABSTRACT: As early as 10 Gyr ago, galaxies with more than 1011M ☉ of stars already existed. While most of these massive galaxies must have subsequently transformed through on-going star formation and mergers with other galaxies, a small fraction (0.1%) may have survived untouched until today. Searches for such relic galaxies, useful windows to explore the early universe, have been inconclusive to date: galaxies with masses and sizes like those observed at high redshift (M 1011M ☉; Re 1.5 kpc) have been found in the local universe, but their stars are far too young for the galaxy to be a relic galaxy. This paper explores the first case of a nearby galaxy, NGC 1277 (at a distance of 73 Mpc in the Perseus galaxy cluster), which fulfills many criteria to be considered a relic galaxy. Using deep optical spectroscopy, we derive the star formation history along the structure of the galaxy: the stellar populations are uniformly old (>10 Gyr) with no evidence for more recent star formation episodes. The metallicity of their stars is super-solar ([Fe/H] = 0.20 ± 0.04 with a smooth decline toward the outer regions) and α-enriched ([α/Fe] = 0.4 ± 0.1). This suggests a very short formation time scale for the bulk of the stars in this galaxy. This object also rotates very fast (V rot ~ 300 km s–1) and has a large central velocity dispersion (σ > 300 km s–1). NGC 1277 allows the exploration in full detail of properties such as the structure, internal dynamics, metallicity, and initial mass function as they were at ~10-12 Gyr ago when the first massive galaxies were built.
    Preview · Article · Oct 2013 · The Astrophysical Journal
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    Patricia Sanchez-Blazquez · Fabian Rosales-Ortega · Angeles Diaz · Sebastian Sanchez
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    ABSTRACT: We present a stellar population analysis of the nearby, face-on, SA(s)c galaxy, NGC628, which is part of the PPAK IFS Nearby Galaxies Survey (PINGS). The data cover a field of view of ~6 arcmin in diameter with a sampling of $\sim$2.7 arcsec per spectrum and a wavelength range (3700-7000A). We apply spectral inversion methods to derive 2-dimensional maps of star formation histories and chemical enrichment. We present maps of the mean (luminosity- and mass-weighted) age and metallicity that reveal the presence of structures such as a nuclear ring, previously seen in molecular gas. The disk is dominated in mass by an old stellar component at all radii sampled by our data, while the percentage of young stars increase with radius. The mean stellar age and metallicity profiles have a two defined regions, an inner one with flatter gradients (even slightly positive) and an external ones with a negative, steeper one, separated at $\sim$60 arcsec. This break in the profiles is more prominent in the old stellar component. The young component shows a metallicity gradient that is very similar to that of the gas, and that is flatter in the whole disc. The agreement between the metallicity gradient of the young stars and the gas, and the recovery of the measured colours from our derived star formation histories validate the techniques to recover the age-metallicity and the star formation histories in disc galaxies from integrated spectra. We speculate about the possible origin of the break and conclude that the most likely scenario is that we are seeing, in the center of NGC 628, a dissolving bar, as predicted in some numerical simulations.
    Full-text · Article · Oct 2013 · Monthly Notices of the Royal Astronomical Society
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    Andre Milone · Ronaldo da Silva · Anne Sansom · Patricia Sanchez-Blazquez
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    ABSTRACT: We report on two distinct computational approaches to self-consistently measure photospheric properties of large samples of stars. Both procedures consist of a set of several semi-integrated tasks based on shell and Python scripts, which efficiently run either our own codes or open source software commonly adopted by the astronomical community. One approach aims to derive the main stellar photospheric parameters and abundances of a few elements by analysing high-resolution spectra from a given public library homogeneously constructed. The other one is applied to recover the abundance of a single element in stars with known photospheric parameters by using mid-resolution spectra from another open homogeneous database and calibrating derived abundances. Both semi-automated computational approaches provide homogeneity and objectivity to every step of the process and represent a fast way to reach partial and final results as well as to estimate measurement errors, making possible to systematically evaluate and improve the distinct steps.
    Preview · Article · Sep 2013
  • A Ferré-Mateu · A Vazdekis · I Trujillo · P Sánchez-Blázquez · E Ricciardelli · I ~G Rosa

    No preview · Conference Paper · Jul 2013
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    R Cacho · P Sánchez-Blázquez · J Gorgas · I Pérez · T Ruiz-Lara

    Full-text · Conference Paper · May 2013
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    ABSTRACT: In these proceedings we summarize the characteristics and current status of MEGARA, the future optical IFU and MOS for the 10.4 m GTC. MEGARA is being built by a Consortium led by the UCM (Spain) that also includes the INAOE (Mexico), the IAA-CSIC (Spain) and the UPM (Spain). The MEGARA IFU offers two different bundles, one called LCB with a field-of-view of 14×12 arcsec2 and a spaxel size of 0.685 arcsec yielding spectral resolutions between R=6000-19000 and another one called SCB covering 10×8 arcsec2 with 0.48 arcsec spaxels and resolutions R=8000-25000. The MOS component allows observing up to 100 targets in 3.5×3.5 arcmin 2. In September 2010 MEGARA was selected as the next optical spectrograph for GTC. Its PDR is scheduled for March 2012 with First Light on 2015. © 2013: Instituto de Astronomía, UNAM - Fourth Science Meeting with the GTC Ed. C. Muñoz-Tuñón & J. M. Rodríguez-Espinosa.
    No preview · Conference Paper · May 2013

  • No preview · Conference Paper · May 2013
  • T Ruiz-Lara · E Florido · I Pérez · P Sánchez-Blázquez · J Falcón-Barroso · R Cacho

    No preview · Conference Paper · May 2013
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    Anne E. Sansom · Andre de Castro Milone · Alexandre Vazdekis · Patricia Sánchez-Blázquez
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    ABSTRACT: Element abundance ratios hold important clues to understanding the evolution of stellar populations, through the varying timescales of different nucleosynthetic contributors. Newly measured and compiled [Mg/Fe] ratios in the MILES stellar library are used to confront models of star spectra. Such models have been used in recent years to provide estimates of differential changes in spectral line strengths, due to enhancements in [α/Fe]. In this paper we test one widely used set of theoretical element response functions. Using magnesium as a proxy for all alpha elements we test the reliability of these theoretical response functions against empirical observations, and thus the reliability of current methods of measuring element abundance ratios in the stellar populations.
    Preview · Article · Aug 2012 · Proceedings of the International Astronomical Union
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    ABSTRACT: With the goal of assembling a new generation of more realistic single stellar population (SSP) models, we have obtained magnesium abundances for nearly 80% of the stars of the widely employed MILES empirical spectral library. Additional spectroscopic observations of carefully selected stars have recently been obtained to improve the parametric coverage of this library. Here we report on: (i) the framework of Mg abundance determination carried out at mid-resolution, (ii) the newly acquired data, and (iii) the preliminary steps towards modelling stellar populations.
    Preview · Article · Aug 2012 · Proceedings of the International Astronomical Union
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    ABSTRACT: We characterize the kinematics, morphology, stellar populations and star formation histories of a sample of massive compact galaxies in the nearby Universe, which might provide a closer look at the nature of their high-redshift (z >rsim 1.0) massive counterparts. We find that nearby compact massive objects show elongated morphologies and are fast rotators. New high-quality long-slit spectra show that they have young mean luminosity-weighted ages (2 Gyr) and metallicities solar or above ([Z/H] >rsim 0.0). No significant stellar population gradients are found. The analysis of their star formation histories suggests that these objects have experienced recently enormous bursts which, in some cases, represent unprecedented large fractions of their total stellar mass. These galaxies seem to be truly unique, as they do not follow the characteristic kinematical and stellar population patterns of present-day massive ellipticals, spirals or even dwarfs.
    Preview · Article · Mar 2012 · Monthly Notices of the Royal Astronomical Society
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    Joel C. Roediger · Stephane Courteau · Patricia Sanchez-Blazquez · Michael A. McDonald
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    ABSTRACT: We present stellar age profiles for 64 Virgo cluster disk galaxies whose analysis poses a challenge for current galaxy formation models. Our results can be summarized as follows: first, and contrary to observations of field galaxies, these cluster galaxies are distributed almost equally amongst the three main types of disk galaxy luminosity profiles (I/II/III), indicating that the formation and/or survival of Type II breaks is suppressed within the cluster environment. Second, we find examples of statistically-significant inversions ("U-shapes") in the age profiles of all three disk galaxy types, reminescent of predictions from high-resolution simulations of classically-truncated Type II disks in the field. These features characterize the age profiles for only about a third (<36%) of each disk galaxy type in our sample. An even smaller fraction of cluster disks (~11% of the total sample), exhibit age profiles which decrease outwards (i.e., negative age gradients). Instead, flat and/or positive age gradients prevail (>50%) within our Type I, II and III sub-samples. These observations thus suggest that while stellar migrations and inside-out growth can play a significant role in the evolution of all disk galaxy types, other factors contributing to the evolution of galaxies can overwhelm the predicted signatures of these processes. We interpret our observations through a scenario whereby Virgo cluster disk galaxies formed initially like their bretheren in the field but which, upon falling into the cluster, were transformed into their present state through external processes linked to the environment. Current disk galaxy formation models fail to reproduce these results, thus calling for adequate hydrodynamical simulations of dense galaxy environments, for which the current paper provides many constraints. [Abridged]
    Preview · Article · Jan 2012 · The Astrophysical Journal
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    Patricia Sánchez-Blázquez · Isabel Pérez · Pierre Ocvirk
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    ABSTRACT: Numerical simulations have shown that strong gravitational torque by non-axisymmetric components induce evolutionary processes such as redistribution of mass and angular momentum in the galactic disks and consequent change of chemical abundance profiles. If we hope to understand chemical evolution gradients and their evolution we must understand the secular processes and re-arrangement of material by non-axisymmetric components and vice-versa. The most obvious of these aforementioned non-axisymmetric components are bars - at least 2/3 of spiral galaxies host a bar, and possibly all disk galaxies have hosted a bar at some point in their evolution. While observationally it has been found that barred galaxies have shallower gas-phase metallicity gradients than non-barred galaxies, a complementary analysis of the stellar abundance profiles has not yet been undertaken. This is unfortunate because the study of both gas and stars is important in providing a complete picture, as the two components undergo (and suffer from) very different evolutionary process. We present here a pilot study of the gas and stellar metallicity and age distributions in a sample of barred and non-barred galaxies using 2D spectroscopic observations. We found that the majority of the stellar mass in our sample is composed of old (~10 Gyr) stars. This is true in the bulge and the disc region, even beyond two disc scalelengths. In the disc region, a larger fraction of young stars is present in the external parts of the disc compared with the inner disc. The disc growth is, therefore, compatible with a moderate inside-out formation scenario, where the luminosity-weighted age changes from ~10 Gyrs in the centre, to ~4 Gyrs at two disc scalelengths, depending upon the galaxy. However, the presence of substructure, like star forming rings, can produce stellar population trends that are not directly related with the growing of the disc but to the bar potential. In the disc region, the metallicity gradient always decrease with the radius. In the bulge region this is not always true and we find inverse metallicity gradients in several galaxies.
    Preview · Article · Dec 2011 · Proceedings of the International Astronomical Union
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    ABSTRACT: With the aim of distinguishing between possible physical mechanisms acting on galaxies when they fall into clusters, we study the properties of the gas and the stars in a sample of 422 emission-line galaxies from EDisCS in different environments up to z~1. We identify galaxies with kinematical disturbances (from emission-lines in their 2D spectra) and find that they are more frequent in clusters than in the field. The fraction of kinematically-disturbed galaxies increases with cluster velocity dispersion and decreases with distance from the cluster centre, but remains constant with projected galaxy density. We also studied morphological disturbances in the stellar light from HST/F814W images, finding that the fraction of morphologically disturbed galaxies is similar in all environments. Moreover, there is little correlation between the presence of kinematically-disturbed gas and morphological distortions. We also study the dependence of the Tully-Fisher relation, star formation, and extent of the emission on environment, and conclude that the gas disks in cluster galaxies have been truncated, and therefore their star formation is more concentrated than in low-density environments. If spirals transform into S0s, our findings imply that the physical mechanism transforming cluster galaxies efficiently disturbs the star-forming gas and reduces their specific star formation rate. Moreover, this star-forming gas is either removed more efficiently from the outskirts of the galaxies or is driven towards the centre (or both), helping to build the bulges of S0s. These results, in addition to the finding that the transformation mechanism does not seem to induce strong morphological disturbances on the galaxies, suggest that the physical processes involved are related to the intracluster medium, with galaxy-galaxy interactions playing only a limited role in clusters.
    Full-text · Article · Sep 2011 · Monthly Notices of the Royal Astronomical Society
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    ABSTRACT: In the first paper in this series, we proposed a new framework in which to model the chemical evolution of globular clusters. This model, is predicated upon the assumption that clusters form within an interstellar medium enriched locally by the ejecta of a single Type Ia supernova and varying numbers of asymptotic giant branch stars, superimposed on an ambient medium pre-enriched by low-metallicity Type II supernovae. Paper I was concerned with the application of this model to the observed abundances of several reactive elements and so-called non-metals for three classical intermediate-metallicity clusters, with the hallmark of the work being the successful recovery of many of their well-known elemental and isotopic abundance anomalies. Here, we expand upon our initial analysis by (a) applying the model to a much broader range of metallicities (from the factor of three explored in Paper I, to now, a factor of ~50; i.e., essentially, the full range of Galactic globular cluster abundances, and (b) incorporating a broader suite of chemical species, including a number of iron-peak isotopes, heavier alpha-elements, and fluorine. While most empirical globular cluster abundance trends are reproduced, our model would suggest the need for a higher production of Ca, Si, and Cu in low-metallicity (or so-called "prompt") Type Ia supernovae than predicted in current stellar models in order to reproduce the observed trends in NGC 6752, and a factor of two reduction in carbon production from asymptotic giant branch stars to explain the observed trends between carbon and nitrogen. Observations of heavy-element isotopes produced primarily by Type Ia supernovae, including those of titanium, iron, and nickel, could support/refute unequivocally our proposed framework. Hydrodynamical simulations would be necessary to study its viability from a dynamical point of view.
    Full-text · Article · Sep 2011 · Monthly Notices of the Royal Astronomical Society
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    ABSTRACT: We present Gran-Telescopio-Canarias/OSIRIS optical spectra of 4 of the most compact and massive early-type galaxies in the Groth Strip Survey at redshift z~1, with effective radii Reff=0.5-2.4 kpc and photometric stellar masses Mstar=1.2-4x10^11 Msun. We find these galaxies have velocity dispersions sigma=156-236 km/s. The spectra are well fitted by single stellar population models with approximately 1 Gyr of age and solar metallicity. We find that: i) the dynamical masses of these galaxies are systematically smaller by a factor of ~6 than the published stellar masses using BRIJK photometry; ii) when estimating stellar masses as 0.7xMdyn, a combination of passive luminosity fading with mass/size growth due to minor mergers can plausibly evolve our objects to match the properties of the local population of early-type galaxies.
    Full-text · Article · Jul 2011 · The Astrophysical Journal Letters

  • No preview · Conference Paper · Jul 2011
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    ABSTRACT: Semi-analytic models (SAMs) are currently one of the primary tools with which to model statistically significant ensembles of galaxies. The underlying physical prescriptions inherent to each SAM are, in many cases, different from one another. Several SAMs have been applied to the dark matter merger trees extracted from the Millennium Run, including those associated with the well-known Munich and Durham lineages. We compare the predicted luminosity distributions of galaxy groups using four publicly available SAMs (De Lucia et al. 2006; Bower et al. 2006; Bertone et al. 2007; Font et al. 2008), in order to explore a galactic environment in which the models have not been explored to the same degree as they have in the field or in rich clusters. We identify a characteristic "wiggle" in the group galaxy luminosity function generated using the De Lucia et al. (2006) SAM, that is not present in the Durham-based models, consistent to some degree with observations. However, a comparison between conditional luminosity functions of groups between the models and observations of Yang et al. (2007) suggest that neither model is a particularly good match. The luminosity function wiggle is interpreted as the result of the two-mode AGN feedback implementation used in the Munich models, which itself results in flattened magnitude gap distribution. An associated analysis of the magnitude gap distribution between first- and second-ranked group galaxies shows that while the Durham models yield distributions with approximately equal luminosity first- and second-ranked galaxies, in agreement with observations, the De Lucia et al. models favours the scenario in which the second-ranked galaxy is approximately one magnitude fainter than the primary,especially when the dynamic range of the mock data is limited to 3 magnitudes.
    Full-text · Article · Apr 2011 · Monthly Notices of the Royal Astronomical Society

Publication Stats

464 Citations
129.02 Total Impact Points

Institutions

  • 2010-2014
    • Universidad Autónoma de Madrid
      • Department of Theoretical physics
      Madrid, Madrid, Spain
    • Instituto de Astrofísica de Canarias
      San Cristóbal de La Laguna, Canary Islands, Spain
  • 2006-2011
    • University of Central Lancashire
      Preston, England, United Kingdom
  • 2005
    • University of Vic
      Vic, Catalonia, Spain
    • Swinburne University of Technology
      • Centre for Astrophysics and Supercomputing
      Melbourne, Victoria, Australia