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 - 7 of 7
  • 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
    SHARDS: stellar populations and star formation histories of a mass-selected sample of 0.65 < z < 1.1 galaxies
    (Wiley, 2013-09) Pérez González, Pablo Guillermo; Cardiel López, Nicolás; Cava, Antonio; Barro, Guillermo; Gallego Maestro, Jesús
    We report on results from the analysis of a stellar mass-selected (log (M-*/M-circle dot) >= 9.0) sample of 1644 galaxies at 0.65 < z < 1.1 with ultradeep (m(AB) < 26.5) optical medium-band (R similar to 50) photometry from the Survey for High-z Absorption Red and Dead Sources (SHARDS). The spectral resolution of SHARDS allows us to consistently measure the strength of the 4000 A spectral break [D-n(4000), an excellent age indicator for the stellar populations of quiescent galaxies] for all galaxies at z similar to 0.9 down to log (M-*/M-circle dot) similar to 9. The D-n(4000) index cannot be resolved from broad-band photometry, and measurements from optical spectroscopic surveys are typically limited to galaxies at least 10 times more massive. When combined with the rest-frame U - V colour, (U - V)(r), D-n(4000) provides a powerful diagnostic of the extinction affecting the stellar population that is relatively insensitive to degeneracies with age, metallicity or star formation history. We use this novel approach to estimate de-reddened colours and light-weighted stellar ages for individual sources. We explore the relationships linking stellar mass, (U - V)(r), and D-n(4000) for the sources in the sample, and compare them to those found in local galaxies. The main results are: (a) both D-n(4000) and (U - V)(r) correlate with M-*. The dispersion in D-n(4000) values at a given M-* increases with M-*, while the dispersion for (U - V)(r) decreases due to the higher average extinction prevalent in massive star-forming galaxies. (b) For massive galaxies, we find a smooth transition between the blue cloud and red sequence in the intrinsic U - V colour, in contrast with other recent results. (c) At a fixed stellar age, we find a positive correlation between extinction and stellar mass. (d) The fraction of sources with declining or halted star formation increases steeply with the stellar mass, from similar to 5 per cent at log (M-*/M-circle dot) = 9.0-9.5 to similar to 80 per cent at log (M-*/M-circle dot) > 11, in agreement with downsizing scenarios.
  • Publication
    Optically faint massive Balmer break galaxies at z > 3 in the CANDELS/GOODS fields
    (IOP Publishing LTD, 2019-05-10) Alcalde Pampliega, Belén; Pérez González, Pablo Guillermo; Barro, Guillermo; Domínguez Sánchez, Helena; Eliche Moral, M. Carmen; Cardiel López, Nicolás; Hernán Caballero, Antonio; Rodríguez Muñoz, Lucía; Sánchez Blázquez, Patricia; Esquej, Pilar
    We present a sample of 33 Balmer break galaxies (BBGs) selected as Hubble Space Telescope/F160W dropouts in the deepest CANDELS/GOODS fields (H >/~ 27.3 mag) but relatively bright in Spitzer/IRAC ([3.6], [4.5] < 24.5 mag), implying red colors (median and quartiles: {H - [3.6]} = 3.1^(3.4)_(2.8) mag ). Half of these BBGs are newly identified sources. Our BBGs are massive ({ log (M/ M_(☉))} = 10.8_(10.4)^( 11.0)), high-redshift ({z} = 4.8_(4.4)^(5.1)), dusty ({A(V)} = 2.0_(1.5)^(2.0) mag) galaxies. The spectral energy distributions (SEDs) of half of our sample indicate that they are star-forming galaxies with typical specific star formation rates (SFRs) of 0.5–1.0 Gyr^(−1), qualifying them as main-sequence (MS) galaxies at 3 < z < 6. One-third of these SEDs indicate the presence of prominent emission lines (Hβ + [O III], Hα + [N II]) boosting the IRAC fluxes and red colors. Approximately 20% of the BBGs are very dusty (A (V) ∼ 2.5 mag) starbursts with strong mid-to-far-infrared detections and extreme SFRs (SFR > 10^(3) M_(☉) yr^(−1)) that place them above the MS. The rest, 30%, are post-starbursts or quiescent galaxies located >2σ below the MS with mass-weighted ages older than 700 Myr. Only two of the 33 galaxies are X-ray-detected active galactic nuclei (AGNs) with optical/near-infrared SEDs dominated by stellar emission, but the presence of obscured AGNs in the rest of the sources cannot be discarded. Our sample accounts for 8% of the total number density of log(M / M_(☉)) > 10 galaxies at z > 3, but it is a significant contributor (30%) to the general population of red log(M / M_(☉) > 11 galaxies at 4 < z < 6. Finally, our results point out that one of every 30 massive log (M / M_(☉) > 11 galaxies in the local universe was assembled in the first 1.5 Gyr after the big bang, a fraction that is not reproduced by state-of-the-art galaxy formation simulations.
  • Publication
    Shards: an optical spectro-photometric survey of distant galaxies
    (IOP Publishing, 2013-01-01) Pérez González, Pablo Guillermo; Cava, Antonio; Barro, Guillermo; Villar, Victor; Cardiel López, Nicolás; Espino, Néstor; Gallego Maestro, Jesús; Zamorano Calvo, Jaime
    We present the Survey for High-z Absorption Red and Dead Sources (SHARDS), an ESO/GTC Large Program carried out using the OSIRIS instrument on the 10.4 m Gran Telescopio Canarias (GTC). SHARDS is an ultra-deep optical spectro-photometric survey of the GOODS-N field covering 130 arcmin(2) at wavelengths between 500 and 950 nm with 24 contiguous medium-band filters (providing a spectral resolution R similar to 50). The data reach an AB magnitude of 26.5 (at least at a 3 sigma level) with sub-arcsec seeing in all bands. SHARDS' main goal is to obtain accurate physical properties of intermediate-and high-z galaxies using well-sampled optical spectral energy distributions (SEDs) with sufficient spectral resolution to measure absorption and emission features, whose analysis will provide reliable stellar population and active galactic nucleus (AGN) parameters. Among the different populations of high-z galaxies, SHARDS' principal targets are massive quiescent galaxies at z > 1, whose existence is one of the major challenges facing current hierarchical models of galaxy formation. In this paper, we outline the observational strategy and include a detailed discussion of the special reduction and calibration procedures which should be applied to the GTC/OSIRIS data. An assessment of the SHARDS data quality is also performed. We present science demonstration results on the detection and study of emission-line galaxies (star-forming objects and AGNs) at z = 0-5. We also analyze the SEDs for a sample of 27 quiescent massive galaxies with spectroscopic redshifts in the range 1.0 < z less than or similar to 1.4. We discuss the improvements introduced by the SHARDS data set in the analysis of their star formation history and stellar properties. We discuss the systematics arising from the use of different stellar population libraries, typical in this kind of study. Averaging the results from the different libraries, we find that the UV-to-MIR SEDs of the massive quiescent galaxies at z = 1.0-1.4 are well described by an exponentially decaying star formation history with scale t = 100-200 Myr, age around 1.5-2.0 Gyr, solar or slightly sub-solar metallicity, and moderate extinction, A(V) similar to 0.5 mag. We also find that galaxies with masses above M* are typically older than lighter galaxies, as expected in a downsizing scenario of galaxy formation. This trend is, however, model dependent, i.e., it is significantly more evident in the results obtained with some stellar population synthesis libraries, and almost absent in others.
  • Publication
    Velocity Dispersions and Stellar Populations of the Most Compact and Msssive early-Type Galaxies at Redshift similar to 1
    (IOP Publishing, 2011-09-10) Martínez Manso, Jesús; Guzmán, Rafael; Barro, Guillermo; Cenarro, Javier; Pérez González, Pablo Guillermo; Sánchez Blázquez, Patricia; Trujillo, Ignacio; Balcells, Marc; Cardiel López, Nicolás; Hempel, Angela; Prieto, Mercedes
    We present Gran-Telescopio-Canarias/OSIRIS optical spectra of four of the most compact and massive early-type galaxies (ETGs) in the Groth Strip Survey at redshift z similar to 1, with effective radii R-e = 0.5-2.4 kpc and photometric stellarmasses M-star = (1.2-4) x 10(11)M(circle dot). We find that these galaxies have velocity dispersions sigma = 156-236 km s(-1). The spectra are well fitted by single stellar population models with approximately 1 Gyr of age and solar metallicity. We find that (1) the dynamical masses of these galaxies are systematically smaller by a factor of similar to 6 than the published stellarmasses using BRIJK photometry, and (2) when estimating stellarmasses as 0.7xM(dyn), 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 ETGs.
  • Publication
    Evolution of the anti-truncated stellar profiles of S0 galaxies since z=0.6 in the SHARDS survey I. Sample and methods
    (EDP Sciencies, 2017-08) Borlaff, Alejandro; Eliche Moral, María del Carmen; Beckman, John E.; Ciambur, Bogdan C.; Pérez González, Pablo Guillermo; Barro, Guillermo; Cava, Antonio; Cardiel López, Nicolás
    Context. The controversy about the origin of the structure of early-type S0-E/S0 galaxies may be due to the difficulty of comparing surface brightness profiles with different depths, photometric corrections and point spread function (PSF) effects (which are almost always ignored). Aims. We aim to quantify the properties of Type-III (anti-truncated) discs in a sample of S0 galaxies at 0.2 < z < 0.6. In this paper, we present the sample selection and describe in detail the methods to robustly trace the structure in their outskirts and correct for PSF effects. Methods. We have selected and classified a sample of 150 quiescent galaxies at 0.2 < z < 0.6 in the GOODS-N field. We performed a quantitative structural analysis of 44 S0-E/S0 galaxies. We have corrected their surface brightness profiles for PSF distortions and analysed the biases in the structural and photometric parameters when the PSF correction is not applied. Additionally, we have developed Elbow, an automatic statistical method to determine whether a possible break is significant - or not - and its type. We have made this method publicly available. Results. We find 14 anti-truncated S0-E/S0 galaxies in the range 0.2 < z < 0.6 (similar to 30% of the final sample). This fraction is similar to the those reported in the local Universe. In our sample, similar to 25% of the Type-III breaks observed in PSF-uncorrected profiles are artifacts, and their profiles turn into a Type I after PSF correction. PSF effects also soften Type-II profiles. We find that the profiles of Type-I S0 and E/S0 galaxies of our sample are compatible with the inner profiles of the Type-III, in contrast with the outer profiles. Conclusions. We have obtained the first robust and reliable sample of 14 anti-truncated S0-E/S0 galaxies beyond the local Universe, in the range 0.2 < z < 0.6. PSF effects significantly affect the shape of the surface brightness profiles in galaxy discs even in the case of the narrow PSF of HST/ACS images, so future studies on the subject should make an effort to correct them.