The evolution of the number density of compact galaxies

We compare the number density of compact (small size) massive galaxies at low and high redshift using our Padova Millennium Galaxy and Group Catalogue (PM2GC) at z=0.03-0.11 and the CANDELS results from Barro et al. (2013) at z=1-2. The number density of local compact galaxies with luminosity weighted (LW) ages compatible with being already passive at high redshift is compared with the density of compact passive galaxies observed at high-z. Our results place an upper limit of a factor ~2 to the evolution of the number density and are inconsistent with a significant size evolution for most of the compact galaxies observed at high-z. The evolution may be instead significant (up to a factor 5) for the most extreme, ultracompact galaxies. Considering all compact galaxies, regardless of LW age and star formation activity, a minority of local compact galaxies (<=1/3) might have formed at z<1. Finally, we show that the secular decrease of the galaxy stellar mass due to simple stellar evolution may in some cases be a non-negligible factor in the context of the evolution of the mass-size relation, and we caution that passive evolution in mass should be taken into account when comparing samples at different redshifts.Comment: ApJ in pres

Colour gradients in normal and compact early-type galaxies at 1<z<2

We have derived colour gradients for a sample of 20 early-type galaxies (ETGs) at 1 < z_spec < 2 selected from the GOODS-South field. The sample includes both normal ETGs (13) having effective radii comparable to the mean radius of local ones and compact ETGs (7) having effective radii from two to six times smaller. Colour gradients have been derived in the F606W-F850LP bands (UV-U rest-frame) taking advantage of the ultradeep HST-ACS observations covering this field and providing a spatial resolution of about 0.8 kpc at the redshift of the galaxies. Despite of the narrow wavelength baseline covered (1000 Angstrom), sampling approximatively the emission dominated by the same stellar population, we detect significant radial colour variations in 50 per cent of our sample. In particular, we find five ETGs with positive colour gradients (cores bluer than the external regions), and five galaxies with negative colour gradients (cores redder than the external regions), as commonly observed in the local Universe. These results show that at 1 < z < 2, when the Universe was only 3-4 Gyr old, ETGs constituted a composite population of galaxies whose different assembly histories have generated different stellar distributions with the bluest stellar population either in the center or in the outskirts as well as throughout the whole galaxy. Moreover, we find that compact galaxies seem to preferentially show a blue cores while moving towards normal galaxies, central stellar populations become progressively redder. Nonetheless, the narrow baseline covered together with the low statistics still prevent us to be conclusive about a possible physical connection between colour gradients and the degree of compactness of high-z ETGs.Comment: 11 pages, 8 figures, accepted for publication in MNRA

Propuesta didáctica de enseñanza de física por experimentación: desarrollo de actividad práctica agronómica en entorno virtual

Conclusiones Dado el escenario de aislamiento social que debió asumirse frente a la pandemia, tanto docentes como alumnos cambiamos nuestros entornos de desempeño de tareas habituales. La propuesta de hacer un experimento con materiales accesibles en el hogar o en la cercanía de donde residieran los estudiantes fue una instrumentación didáctica para que pudieran hacer una trasposición de los conceptos teórico prácticos planteados desde la virtualidad a situaciones del mundo real, concreto y palpable.En este trabajo se presenta una estrategia didáctica utilizada en la asignatura Física I (primer año de las carreras Ingeniería Agronómica, Ingeniería Zootecnista y Licenciatura en Agroalimentos) que fue desarrollada de manera virtual durante el año 2020. El objetivo de dicha estrategia es que los alumnos integren los conocimientos adquiridos para resolver una situación práctica. Se plantea una actividad práctica para evaluar la consistencia de suelo con posibilidad de desarrollarse en el Campo Escuela de la Facultad de Ciencias Agropecuarias (UNC) o bien, en los domicilios de los alumnos empleando materiales de uso cotidiano. La tarea práctica fue desarrollada en tres etapas, con el acompañamiento de las docentes mediante las consultas a través del aula virtual. Al ser una actividad planteada con consignas abiertas, cada uno tuvo que organizar su trabajo e identificar los puntos importantes a informar; esto les permitió desarrollar su ingenio y creatividad. Mediante esta actividad alcanzó la promoción más del 40% de los alumnos. Las devoluciones de los alumnos evidencian que esta actividad les ayudó a comprender cómo se relaciona la Física con el ámbito de la Agronomía.publishedVersionFil: Valentinuzzi, María Cecilia. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias. Departamento de Ingeniería y Mecanización Rural. Cátedra de Física; Argentina.Fil: Valentinuzzi, María Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Física "Enrique Gaviola"; Argentina.Fil: Sbarato, V. M. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias. Departamento de Ingeniería y Mecanización Rural. Cátedra de Física; Argentina

The evolution of galaxy sizes

We present a study of galaxy sizes in the local Universe as a function of galaxy environment, comparing clusters and the general field. Galaxies with radii and masses comparable to high-z massive and compact galaxies represent 4.4% of all galaxies more massive than 3 X 10^{10} M_sun in the field. Such galaxies are 3 times more frequent in clusters than in the field. Most of them are early-type galaxies with intermediate to old stellar populations. There is a trend of smaller radii for older luminosity-weighted ages at fixed galaxy mass. We show the relation between size and luminosity-weighted age for galaxies of different stellar masses and in different environments. We compare with high-z data to quantify the evolution of galaxy sizes. We find that, once the progenitor bias due to the relation between galaxy size and stellar age is removed, the average amount of size evolution of individual galaxies between high- and low-z is mild, of the order of a factor 1.6.Comment: to appear in the proceedings of the IAU S295: The intriguing life of massive galaxies, editors D. Thomas, A. Pasquali & I. Ferrera

Relatos de mujeres que dejaron huellas

Este trabajo da cuenta de una investigación que un equipo interdisciplinario de docentes conjuntamente con cadetes de cuarto año de la Escuela de Aviación Militar de la Fuerza Aérea Argentina realizara sobre las vivencias que esposas, madres, hijas de héroes de Malvinas y enfermeras tuvieran durante el Conflicto del Atlántico Sur. Los objetivos estaban orientados a: reconstruir las historias de vida de mujeres que de una u otra manera estuvieron involucradas con la guerra; revalorizar el rol que cumplió la mujer en la historia argentina durante el Conflicto y fortalecer el espíritu de investigación por parte de los cadetes en el ambiente Universitario. Se desarrolló una investigación cualitativa de carácter exploratoria, utilizándose como metodología de trabajo el estudio de casos. Para la recolección de la información se apeló al método biográfico: historias de vida acompañado de entrevistas en profundidad. La reconstrucción de los relatos se realizó en torno a las siguientes categorías analíticas: la mirada femenina de la guerra, mujeres- familia y profesión, mujeres enfermeras y la guerra. Este trabajo implicó indagar un área de conocimiento que resulta de vital importancia para nuestra historia argentina, dado que no se cuenta con material suficiente sobre esta temática de género y la guerra de Malvinas, especialmente en relación con la Fuerza Aérea Argentina.Eje temático: Representaciones, sentidos e identidades en disputa: c- Las mujeres en la guerra de MalvinasFacultad de Humanidades y Ciencias de la Educació

On the central stellar mass density and the inside-out growth of early-type galaxies

[Abridged] In this paper we derive the central stellar mass density within a fixed radius and the effective stellar mass density within the effective radius for a complete sample of 34 ETGs morphologically selected at 0.9<z_{spec}<2 and compare them with those derived for a sample of ~900 local ETGs in the same mass range. We find that the central stellar mass density of high-z ETGs spans just an order of magnitude and it is similar to the one of local ETGs as actually found in previous studies.However, we find that the effective stellar mass density of high-z ETGs spans three orders of magnitude, exactly as the local ETGs and that it is similar to the effective stellar mass density of local ETGs showing that it has not changed since z~1.5, in the last 9-10 Gyr. Thus, the wide spread of the effective stellar mass density observed up to z~1.5 must originate earlier, at z>2. Also, we show that the small scatter of the central mass density of ETGs compared to the large scatter of the effective mass density is simply a peculiar feature of the Sersic profile hence, independent of redshift and of any assembly history experienced by galaxies. Thus, it has no connection with the possible inside-out growth of ETGs. Finally, we find a tight correlation between the central stellar mass density and the total stellar mass of ETGs in the sense that the central mass density increases with mass as M^{~0.6}. This implies that the fraction of the central stellar mass of ETGs decreases with the mass of the galaxy. These correlations are valid for the whole population of ETGs considered independently of their redshift suggesting that they originate in the early-phases of their formation.Comment: 11 pages, 6 figures. Accepted for publication in MNRAS (MNRAS version

A Compact Early-type Galaxy at z = 0.6 Under a Magnifying Lens: Evidence For Inside-out Growth

We use Keck laser guide star adaptive optics imaging and exploit the magnifying effects of strong gravitational lensing (the effective resolution is FWHM ~ 200 pc) to investigate the sub-kpc scale of an intermediate-redshift (z = 0.63) massive early-type galaxy being lensed by a foreground early-type galaxy; we dub this class of strong gravitational lens systems EELs, e.g., early-type/early-type lenses. We find that the background source is massive (M* = 10^{10.9} M_sun) and compact (r_e = 1.1 kpc), and a two-component fit is required to model accurately the surface brightness distribution, including an extended low-surface-brightness component. This extended component may arise from the evolution of higher-redshift `red nuggets' or may already be in place at z ~ 2 but is unobservable due to cosmological surface brightness dimming.Comment: 5 pages, 4 figures; accepted to MNRA

WINGS: a WIde-field nearby Galaxy-cluster survey III. Deep near-infrared photometry of 28 nearby clusters

Context. This is the third paper of a series devoted to the WIde-field Nearby Galaxy-cluster Survey (WINGS).WINGS is a long term project aimed at gathering wide-field, multiband imaging and spectroscopy of galaxies in a complete sample of 77 X-ray selected nearby clusters (0.04<z<0.07) located far from the galactic plane (b>20deg). The main goal of this project is to establish a local reference sample for evolutionary studies of galaxies and galaxy clusters. Aims. This paper presents the near-infrared (J,K) photometric catalogs of 28 clusters of the WINGS sample and describes the procedures followed to construct them. Methods. The raw data has been reduced at CASU and special care has been devoted to the final coadding, drizzling technique, astrometric solution and magnitude calibration for the WFCAM pipeline processed data. We have constructed the photometric catalogs based on the final calibrated coadded mosaics (0.79 deg2) in J (19 clusters) and K (27 clusters) bands. A customized interactive pipeline has been used to clean the catalogs and to make mock images for photometric errors and completeness estimates. Results. We provide deep near-infrared photometric catalogs (90% complete in detection rate at total magnitudes J =20.5, K =19.4, and in classification rate at J = 19.5 and K = 18.5), giving positions, geometrical parameters, total and aperture magnitudes for all detected sources. For each field we classify the detected sources as stars, galaxies and objects of "unknown" nature.Comment: Published by A&A501.851 - 15 pages, 3 tables, 13 figures. Catalogs will be available via CDS and http://web.oapd.inaf.it/wing