Pérez González, Pablo Guillermo

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First Name
Pablo Guillermo
Last Name
Pérez González
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
Astronomía y Astrofísica
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Now showing 1 - 10 of 23
  • Publication
    The minor role of gas-rich major mergers in the rise of intermediate-mass early types at z ≤ 1
    (American Astronomical Society, 2010-02-20) López Sanjuan, Carlos; Balcells, Marc; Pérez González, Pablo Guillermo; Barro, Guillermo; García Dabó, César Enrique; Gallego Maestro, Jesús; Zamorano Calvo, Jaime
    We study the evolution of galaxy structure since z ~ 1 to the present. From a Great Observatories Origins Deep Survey South (GOODS-S) multi-band catalog, we define (blue) luminosity- and mass-weighted samples, limited by MB ≤ –20 and M sstarf ≥ 1010 M ☉, comprising 1122 and 987 galaxies, respectively. We extract early-type (ET; E/S0/Sa) and late-type (LT; Sb-Irr) subsamples by their position in the concentration-asymmetry plane, in which galaxies exhibit a clear bimodality. We find that the ET fraction, f ET, rises with cosmic time, with a corresponding decrease in the LT fraction, f LT, in both luminosity- and mass-selected samples. However, the evolution of the comoving number density is very different: the decrease in the total number density of MB ≤ –20 galaxies since z = 1 is due to the decrease in the LT population, which accounts for ~75% of the total star formation rate in the range under study, while the increase in the total number density of M sstarf ≥ 1010 M ☉ galaxies in the same redshift range is due to the evolution of ETs. This suggests that we need a structural transformation between LT galaxies that form stars actively and ET galaxies in which the stellar mass is located. Comparing the observed evolution with the gas-rich major merger rate in GOODS-S, we infer that only ~20% of the new ET galaxies with M sstarf ≥ 1010 M ☉ appeared since z ~ 1 can be explained by this kind of mergers, suggesting that minor mergers and secular processes may be the driving mechanisms of the structural evolution of intermediate-mass (M sstarf ~ 4 × 1010 M ☉) galaxies since z ~ 1.
  • Publication
    Formation of S0 galaxies through mergers. V - Antitruncated stellar discs resulting from major mergers
    (EDP Sciencies, 2014-10) Borlaff, Alejandro; Eliche Moral, María del Carmen; Rodríguez Pérez, Cristina; Querejeta, Miguel; Tapia, Trinidad; Pérez González, Pablo Guillermo; Zamorano Calvo, Jaime; Gallego Maestro, Jesús; Beckman, John
    Context. Lenticular galaxies (S0s) are more likely to host antitruncated (Type III) stellar discs than galaxies of later Hubble types. Major mergers are popularly considered too violent to make these breaks. Aims. We have investigated whether major mergers can result into S0-like remnants with realistic antitruncated stellar discs or not. Methods. We have analysed 67 relaxed S0 and E/S0 remnants resulting from dissipative N-body simulations of major mergers from the GalMer database. We have simulated realistic R-band surface brightness profiles of the remnants to identify those with antitruncated stellar discs. Their inner and outer discs and the breaks have been quantitatively characterized to compare with real data. Results. Nearly 70% of our S0-like remnants are antitruncated, meaning that major mergers that result in S0s have a high probability of producing Type III stellar discs. Our remnants lie on top of the extrapolations of the observational trends (towards brighter magnitudes and higher break radii) in several photometric diagrams, because of the higher luminosities and sizes of the simulations compared to observational samples. In scale-free photometric diagrams, simulations and observations overlap and the remnants reproduce the observational trends, so the physical mechanism after antitruncations is highly scalable. We have found novel photometric scaling relations between the characteristic parameters of the antitruncations in real S0s, which are also reproduced by our simulations. We show that the trends in all the photometric planes can be derived from three basic scaling relations that real and simulated Type III S0s fulfill: h_i ∝ R_brkIII, h_o ∝ R_brkIII, and μ_brkIII ∝ R_brkIII, where h_i and h_o are the scalelengths of the inner and outer discs, and μ_brkIII and R_brkIII are the surface brightness and radius of the breaks. Bars and antitruncations in real S0s are structurally unrelated phenomena according to the studied photometric planes. Conclusions. Major mergers provide a feasible mechanism to form realistic antitruncated S0 galaxies.
  • Publication
    UV-to-fir analysis of spitzer/irac sources in the extended groth strip. II. Photometric redshifts, stellar masses, and star formation rates
    (University Chicago Press, 2011-04) Barro, Guillermo; Pérez González, Pablo Guillermo; Gallego Maestro, Jesús; Ashby, M. L. N.; Kajisawa, M.; Miyazaki, S.; Villar, V.; Yamada, T.; Zamorano Calvo, Jaime
    Based on the ultraviolet to far-infrared photometry already compiled and presented in a companion paper (Paper I), we present a detailed spectral energy distribution (SED) analysis of nearly 80,000 IRAC 3.6 + 4.5 μ m selected galaxies in the Extended Groth Strip. We estimate photometric redshifts, stellar masses, and star formation rates (SFRs) separately for each galaxy in this large sample. The catalog includes 76,936 sources with [3.6] ≤ 23.75 (85% completeness level of the IRAC survey) over 0.48 deg^2. The typical photometric redshift accuracy is ∆z/(1 + z) = 0.034, with a catastrophic outlier fraction of just 2%. We quantify the systematics introduced by the use of different stellar population synthesis libraries and initial mass functions in the calculation of stellar masses. We find systematic offsets ranging from 0.1 to 0.4 dex, with a typical scatter of 0.3 dex. We also provide UV- and IR-based SFRs for all sample galaxies, based on several sets of dust emission templates and SFR indicators. We evaluate the systematic differences and goodness of the different SFR estimations using the deep FIDEL 70 μ m data available in the Extended Groth Strip. Typical random uncertainties of the IR-bases SFRs are a factor of two, with non-negligible systematic effects at z ≳1.5 observed when only MIPS 24 μ m data are available. All data products (SEDs, postage stamps from imaging data, and different estimations of the photometric redshifts, stellar masses, and SFRs of each galaxy) described in this and the companion paper are publicly available, and they can be accessed through our the Web interface utility Rainbow-navigator.
  • Publication
    Radial distribution of dust properties in nearby galaxies
    (Springer-Verlag Berlin, 2010) Muñoz Mateos, J.C.; Gil de Paz, Armando; Zamorano Calvo, Jaime; Pérez González, Pablo Guillermo; Gallego Maestro, Jesús
    We present a detailed analysis of the radial distribution of dust properties (extinction, PAH abundance and dust-to-gas ratio) in 57 galaxies in the SINGS sample, performed on a multi-wavelength set of UV, IR and radio surface brightness profiles, combined with published molecular gas profiles and metallicity gradients.
  • Publication
    MEGARA, the new intermediate-resolution optical IFU and MOS for GTC: getting ready for the telescope
    (SPIE-Int Soc Optical Engineering, 2016) Gil de Paz, Armando; Gallego Maestro, Jesús; Cardiel López, Nicolás; Castillo Morales, África; Cruz García, Jesús Manuel de la; Esteban San Román, Segundo; López Orozco, José Antonio; Pascual, S.; Picazo, P.; Sánchez-Penim, A.; Zamorano Calvo, Jaime; Pérez González, Pablo Guillermo; otros, ...
    MEGARA (Multi-Espectrografo en GTC de Alta Resolucion para Astronomia) is an optical Integral-Field Unit (IFU) and Multi-Object Spectrograph (MOS) designed for the GTC 10.4m telescope in La Palma that is being built by a Consortium led by UCM (Spain) that also includes INAOE (Mexico), IAA-CSIC (Spain), and UPM (Spain). The instrument is currently finishing AIV and will be sent to GTC on November 2016 for its on-sky commissioning on April 2017. The MEGARA IFU fiber bundle (LCB) covers 12.5x11.3 arcsec(2) with a spaxel size of 0.62 arcsec while the MEGARA MOS mode allows observing up to 92 objects in a region of 3.5x3.5 arcmin(2) around the IFU. The IFU and MOS modes of MEGARA will provide identical intermediate-to-high spectral resolutions (R-FWHM similar to 6,000, 12,000 and 18,700, respectively for the low-, mid-and high-resolution Volume Phase Holographic gratings) in the range 3700-9800 angstrom angstrom. An x-y mechanism placed at the pseudo-slit position allows (1) exchanging between the two observing modes and (2) focusing the spectrograph for each VPH setup. The spectrograph is a collimator-camera system that has a total of 11 VPHs simultaneously available (out of the 18 VPHs designed and being built) that are placed in the pupil by means of a wheel and an insertion mechanism. The custom-made cryostat hosts a 4kx4k 15-mu m CCD. The unique characteristics of MEGARA in terms of throughput and versatility and the unsurpassed collecting are of GTC make of this instrument the most efficient tool to date to analyze astrophysical objects at intermediate spectral resolutions. In these proceedings we present a summary of the instrument characteristics and the results from the AIV phase. All subsystems have been successfully integrated and the system-level AIV phase is progressing as expected.
  • Publication
    Evolutionary paths among different red galaxy types at 0.3 < z < 1.5 and the late buildup of massive E-S0's through major mergers
    (Wiley, 2013-01) Prieto, Mercedes; Eliche Moral, María del Carmen; Balcells, Marc; Cristobal Hornillos, David; Erwin, Peter; Abreu, David; Domínguez Palmero, Lilian; Hempel, Ángela; López Sanjuan, Carlos; Guzmán, Rafael; Pérez González, Pablo Guillermo; Barro, Guillermo; Gallego Maestro, Jesús; Zamorano Calvo, Jaime
    Some recent observations seem to disagree with hierarchical theories of galaxy formation about the role played by major mergers in the late buildup of massive E-S0s. We re-address this question by analysing the morphology, structural distortion level and star formation enhancement of a sample of massive galaxies (M_* > 5x10^10M_⨀) lying on the Red Sequence and its surroundings at 0.3 < z < 1.5. We have used an initial sample of ∼1800 sources with K_s < 20.5 mag over an area ∼155 arcmin^2 on the Groth Strip, combining data from the Rainbow Extragalactic Database and the Galaxy Origins and Young Assembly survey. Red galaxy classes that can be directly associated with intermediate stages of major mergers and with their final products have been defined. We report observational evidence of the existence of a dominant evolutionary path among massive red galaxies at 0.6 < z < 1.5, consisting in the conversion of irregular discs into irregular spheroids, and of these ones into regular spheroids. This result implies: (1) the massive red regular galaxies at low redshifts derive from the irregular ones populating the Red Sequence and its neighbourhood at earlier epochs up to z ∼ 1.5; (2) the progenitors of the bulk of present-day massive red regular galaxies have been discs that seem to have migrated to the Red Sequence mostly through major mergers at 0.6 < z < 1.2 (these mergers thus starting at z ∼ 1.5) and (3) the formation of E-S0s that end up with M_* > 10^11 M_⨀ at z = 0 through gas-rich major mergers has frozen since z similar to 0.6. All these facts support that major mergers have played a dominant role in the definitive buildup of present-day E-S0s with M-* > 10(11) M-circle dot at 0.6 < z < 1.2, in good agreement with hierarchical scenarios of galaxy formation.
  • Publication
    The buildup of E–S0 galaxies at z < 2 from pure luminosity evolution models
    (Springer-Verlag Berlin, 2010) Eliche Moral, María del Carmen; Prieto, M.; Barro, Guillermo; Balcells, M.; Gallego Maestro, Jesús; Pérez González, Pablo Guillermo; Zamorano Calvo, Jaime; Cardiel López, Nicolás; Gil de Paz, Armando; Guzmán, R.; Pelló, R.; Villar, V.
    Considering that the recent history of E-S0’s can be approximated by Pure Luminosity Evolution (PLE), we have examined a set of PLE models in order to de-limit the epoch in which the majority of the red galaxy population moved away this simple evolution framework. The models assume that they were assembled and formed most of their stars at a given formation redshift (zf), and that they have evolved without merging or substantial dust obscuration since then. Comparing the model predictions with real data, we conclude that most of E-S0’s at low and inter-mediate luminosities must have been progressively built up at 1 < z < 2, being the bulk of formation at z ∼ 1.5, as recently claimed by several observational studies.
  • Publication
    Deconstructing the K-band number counts
    (Springer-Verlag Berlin, 2010) Barro, Guillermo; Gallego Maestro, Jesús; Pérez González, Pablo Guillermo; Eliche Moral, María del Carmen; Balcells, M.; Villar, V.; Cardiel López, Nicolás; Cristobal Hornillos, D.; Gil de Paz, Armando; Guzmán, R.; Pelló, R.; Prieto, M.; Zamorano Calvo, Jaime
    We present a study that links the NCs to the rest-frame luminosity functions (LFs) at the passbands probed by the observed K-band at different epochs. Making use of a large K-band selected sample in the Groth Field, HDFN and CDFS (∼0.27deg^(2)), we have derived highly reliable photometric redshift estimates that allow us to estimate LFs in the redshift range [0.25-1.25]. We find that the larger flattening in the slope of the K-band NCs is mostly a consequence of a prominent decrease in the characteristic density (φ∗) around z∼1, and an almost flat evolution of M∗.
  • Publication
    GUAIX: The UCM Group of Extragalactic Astrophysics and Astronomical Instrumentation
    (Springer-Verlag Berlin, 2010) Cardiel López, Nicolás; Gallego Maestro, Jesús; Pascual Ramírez, Sergio; Eliche Moral, María del Carmen; Castillo Morales, África; Guzmán, R.; Gil de Paz, Armando; Pérez González, Pablo Guillermo; Gorgas García, Francisco Javier; Zamorano Calvo, Jaime
    We present a short summary of the activities developed by GUAIX, the Universidad Complutense de Madrid (UCM) Group of Extragalactic Astrophysics and Astronomical Instrumentation. At present we are focused in the development of data reduction pipelines for several future instruments for the Spanish 10m GTC (Gran Telescopio Canarias). The careful treatment of the random error propagation throughout the data reduction is one of the main improvements of those pipelines. The first hardware development leaded by the GUAIX group will be FISIR, a fully-cryogenic (optimized for the K band) tunable filter in the near-infrared, to be installed within CIRCE, a near-IR camera for GTC.
  • Publication
    Integral field spectroscopy and multi-wavelength imaging of the nearby spiral galaxy ngc 5668*: an unusual flattening in metallicity gradient
    (American Astronomical Society, 2012-07-20) Marino, Raffaella Anna; Gil de Paz, Armando; Castillo Morales, África; Muñoz Mateos, J. C.; Sánchez, S. F.; Pérez González, Pablo Guillermo; Gallego Maestro, Jesús; Zamorano Calvo, Jaime; Alonso Herrero, A.; Boissier, S.
    We present an analysis of the full bidimensional optical spectral cube of the nearby spiral galaxy NGC 5668, observed with the Pmas fiber PAcK Integral Field Unit (IFU) at the Calar Alto observatory 3.5 m telescope. We make use of broadband imaging to provide further constraints on the evolutionary history of the galaxy. This data set will allow us to improve our understanding of the mechanisms that drive the evolution of disks. We investigated the properties of 62 H II regions and concentric rings in NGC 5668 and derived maps in ionized-gas attenuation and chemical (oxygen) abundances. We find that while inward of r similar to 36 '' similar to 4.4 kpc similar to 0.36 (D-25/2) the derived O/H ratio follows the radial gradient typical of spiral galaxies, the abundance gradient beyond r similar to 36 '' flattens out. The analysis of the multi-wavelength surface brightness profiles of NGC 5668 is performed by fitting these profiles with those predicted by chemo-spectrophotometric evolutionary models of galaxy disks. From this, we infer a spin and circular velocity of lambda = 0.053 and nu(c) = 167 km s(-1), respectively. The metallicity gradient and rotation curve predicted by this best-fitting galaxy model nicely match the values derived from the IFU observations, especially within r similar to 36 ''. The same is true for the colors despite some small offsets and a reddening in the bluest colors beyond that radius. On the other hand, deviations of some of these properties in the outer disk indicate that a secondary mechanism, possibly gas transfer induced by the presence of a young bar, must have played a role in shaping the recent chemical and star formation histories of NGC 5668.