122 research outputs found
La densidad de tasa de formación estelar del Universo a z=0.61 medida en Halpha
En este trabajo estudiamos una muestra de 46 galaxias con formación estelar activa, seleccionadas por su emisión en la línea Halpha a z=0.61. Las observaciones de los objetos fueron realizadas con el instrumento HAWK-I del telescopio VLT en un filtro estrecho del infrarrojo cercano, destacando la extrema profundidad alcanzada (32h de tiempo de exposición). El objetivo principal de este estudio consiste en la determinación de la densidad de tasa de formación estelar (SFRd en inglés) del Universo a z=0.61. Obtenemos la función de luminosidad observada y corregida de extinción para cada galaxia, y además utilizamos la profundidad de los datos para determinar un valor de la pendiente del extremo débil de esta función. Por último realizamos un estudio morfológico y calculamos propiedades físicas de la muestra. Los resultados suponen una conexión de la SFRd entre el Universo local y z~1, confirmando el crecimiento de esta magnitud entre estas épocas de la historia del Universo.---[ABSTRACT]--- In this work we study a sample of 46 active star-forming galaxies, selected for their Halpha emission line at z = 0.61. The observations of the objects were made with the HAWK -I instrument of the VLT telescope in a near-infrared narrow filter, highlighting the extreme depth reached (32h exposure time). The main objective of this study is the determination of the star formation rate density (SFRd) of the universe at z=0.61. We obtain the observed luminosity function and extintion corrected for each galaxy, and also we use the depth data to determine a value of the faint end slope of this function. Finally, we performe a morphological study and we calculate physical properties of the sample. The results imply a connection between the local Universe and z~1 SFRd, confirming the growth of this magnitude between these epochs of cosmic history
The rest-frame optical sizes of massive galaxies with suppressed star formation at
We present the rest-frame optical sizes of massive quiescent galaxies (QGs)
at measured at -band with the Infrared Camera and Spectrograph
(IRCS) and AO188 on the Subaru telescope. Based on a deep multi-wavelength
catalog in the Subaru XMM-Newton Deep Survey Field (SXDS), covering a wide
wavelength range from the -band to the IRAC over 0.7 deg, we
evaluate photometric redshift to identify massive ($M_{\star}\sim10^{11}\
M_\odot\rm \AAz\sim4K'K_{AB,total}=22.5\sim23.4z\sim4r_{eff}=0.21.8r_{eff}=0.7\rm\ kpcz\sim4\sim0.2z\sim4\log(r_e/{\rm kpc})= -0.44+1.77
\log(t/\rm Gyr)$. Their size growth is proportional to the square of stellar
mass, indicating the size-stellar mass growth driven by minor dry mergers.Comment: 15 pages, 11 figures, ApJ accepte
A comparison between the soft X-ray and [O III] morphologies of active galactic nuclei
Several studies of nearby active galactic nuclei (AGN) have shown that the
soft X-ray emission presents a size and morphology that resembles that of the
narrow-line region (NLR) traced by [O III]. Since the NLR is mainly constituted
by gas photoionised by the AGN, it seems logical to assume that this is also
the primary source of the soft X-ray emission. However, these results are based
on individual sources or small samples, particularly focused on type-2 Seyfert
galaxies. Very little has been said concerning other types of AGN. The purpose
of this work is to compare the circumnuclear morphologies of soft X-ray and [O
III] images to test whether they match in different optical classes of AGN. Our
sample is composed of 27 AGN: nine type-1 Seyferts, 10 type-2 Seyferts, and
eight low ionisation nuclear emission-line regions (LINERs). We find a good
match in 100% of the type-2 Seyferts in our sample. This correspondence is less
frequent in type-1 Seyferts (22%) and it is not seen in LINERs. The good
resemblance in type-2 Seyferts constitutes an evidence for a common physical
origin. We argue that the lack of correspondence in type-1 Seyferts might be
due to the line of sight perpendicular to the accretion disk. Based on the
morphologies of the eight LINERs in our sample, we discard a common origin for
the soft X-ray and [O III] emissions in these objects. Regarding the X-ray
properties, both high column density and hard X-ray luminosity are associated
with matched morphologies.Comment: Accepted by MNRAS. 20 pages, 9 figure
Properties of galaxies at the faint end of the H luminosity function at
Studies measuring the star formation rate density, luminosity function, and
properties of star-forming galaxies are numerous. However, it exists a gap at
in H-based studies. Our main goal is to study the
properties of a sample of faint H emitters at . We focus on
their contribution to the faint end of the luminosity function and derived star
formation rate density, characterising their morphologies and basic photometric
and spectroscopic properties. We use a narrow-band technique in the
near-infrared, with a filter centred at 1.06 m. The data come from
ultra-deep VLT/HAWK-I observations in the GOODS-S field with a total of 31.9 h
in the narrow-band filter. We perform a visual classification of the sample and
study their morphologies from structural parameters available in CANDELS. Our
28 H-selected sample of faint star-forming galaxies reveals a robust
faint-end slope of the luminosity function . The
derived star formation rate density at is . The sample is
mainly composed of disks, but an important contribution of compact galaxies
with S\'ersic indexes display the highest specific star formation
rates. The luminosity function at from our ultra-deep data points
towards a steeper when an individual extinction correction for each
object is applied. Compact galaxies are low-mass, low-luminosity, and
starburst-dominated objects with a light profile in an intermediate stage from
early to late types.Comment: Published in Astronomy & Astrophysics. 19 pages, 14 figures. New
version includes language edited by the journa
La evaluación de los riesgos de deterioro en el patrimonio cultural. Métodos y estrategias para su estudio en el ámbito docente de la conservación preventiva
Se presenta la enseñanza-aprendizaje de la evaluación de riesgos como herramienta de gestión para la conservación del patrimonio complutense. Se propone el uso de distintas métodos de análisis y procedimientos de trabajo a aplicar con actitud crítica de manera colaborativa e interdisciplinar.Fac. de Bellas ArtesFALSEsubmitte
Evaluación continua con Quizzes (ECQ)
La evaluación de la experiencia, tanto por parte de los estudiantes como de los profesores, ha sido muy positiva; por ello la propuesta actual es utilizar las Quizzes del programa Wiris para potenciar un mejor y mayor aprendizaje de los estudiantes y facilitar al profesorado una evaluación continua de los mismos.
La utilización de Wiris Quizzes facilita la generación de preguntas con una gran aleatoriedad obteniendo un abanico muy amplio de cuestionarios. El tipo de preguntas que pueden crearse es muy diverso, pueden incluirse gráficas y fórmulas generadas con la calculadora y el editor de Wiris.
Los cuestionarios tienen una doble utilidad, tanto de autoevaluación del aprendizaje por parte del estudiante, como de evaluación continuada por parte del profesor de los conocimientos alcanzados por los alumnos. Sus resultados permiten comprobar el nivel de conocimientos adquiridos y ayudan al estudiante en el estudio continuado del temario.Departamento de Matemática Aplicad
Stellar Velocity Dispersion of a Massive Quenching Galaxy at z = 4.01
We present the first stellar velocity dispersion measurement of a massive quenching galaxy at z = 4. The galaxy is first identified as a massive z ≥ 4 galaxy with suppressed star formation from photometric redshifts based on deep multiband data. A follow-up spectroscopic observation with MOSFIRE on Keck revealed strong multiple absorption features, which are identified as Balmer lines, giving a secure redshift of z = 4.01. This is the most distant quiescent galaxy known to date. Thanks to the high S/N of the spectrum, we are able to estimate the stellar velocity dispersion, σ=268±59 km s⁻¹, making a significant leap from the previous highest redshift measurement at z = 2.8. Interestingly, we find that the velocity dispersion is consistent with that of massive galaxies today, implying no significant evolution in velocity dispersion over the last 12 Gyr. Based on a stringent upper limit on its physical size from deep optical images (r_(eff) < 1.3 kpc), we find that its dynamical mass is consistent with the stellar mass inferred from photometry. Furthermore, the galaxy is located on the mass fundamental plane extrapolated from lower redshift galaxies. The observed no strong evolution in σ suggests that the mass in the core of massive galaxies does not evolve significantly, while most of the mass growth occurs in the outskirts of the galaxies, which also increases the size. This picture is consistent with a two-phase formation scenario in which mass and size growth is due to accretion in the outskirts of galaxies via mergers. Our results imply that the first phase may be completed as early as z ~ 4
Fitting pseudo-Sérsic (Spergel) light profiles to galaxies in interferometric data: The excellence of the uυ-plane
Modern (sub)millimeter interferometers, such as ALMA and NOEMA, offer high angular resolution and unprecedented sensitivity. This provides the possibility to characterize the morphology of the gas and dust in distant galaxies. To assess the capabilities of the current software in recovering morphologies and surface brightness profiles in interferometric observations, we tested the performance of the Spergel model for fitting in the uυ-plane, which has been recently implemented in the IRAM software GILDAS (uv_fit). Spergel profiles provide an alternative to the Sérsic profile, with the advantage of having an analytical Fourier transform, making them ideal for modeling visibilities in the uυ-plane. We provide an approximate conversion between the Spergel index and the Sérsic index, which depends on the ratio of the galaxy size to the angular resolution of the data. We show through extensive simulations that Spergel modeling in the uυ-plane is a more reliable method for parameter estimation than modeling in the image plane, as it returns parameters that are less affected by systematic biases and results in a higher effective signal-to-noise ratio. The better performance in the uυ-plane is likely driven by the difficulty of accounting for a correlated signal in interferometric images. Even in the uυ-plane, the integrated source flux needs to be at least 50 times larger than the noise per beam to enable a reasonably good measurement of a Spergel index. We characterized the performance of Spergel model fitting in detail by showing that parameter biases are generally low (<10%) and that uncertainties returned by uv_fit are reliable within a factor of two. Finally, we showcase the power of Spergel fitting by reexamining two claims of extended halos around galaxies from the literature, showing that galaxies and halos can be successfully fitted simultaneously with a single Spergel model
Insight Into a Lensed -dark Galaxy and its Quiescent Companion at
Using the novel /NIRCam observations in the Abell 2744 field, we
present a first spatially resolved overview of an -dark galaxy,
spectroscopically confirmed at with magnification .
While being largely invisible at 1 m with NIRCam, except for sparse
clumpy sub-structures, the object is well-detected and resolved in the
long-wavelength bands with a spiral shape clearly visible in F277W. By
combining ancillary ALMA and data, we infer that this object is an
edge-on dusty spiral with an intrinsic stellar mass log
and a dust-obscured SFR~yr. A massive quiescent galaxy
(log) with tidal features lies 2\farcs{0} away
(9 kpc), at a consistent redshift as inferred by photometry,
indicating a potential major merger. The dusty spiral lies on the main-sequence
of star formation, and shows high dust attenuation in the optical (). In the far-infrared, its integrated dust SED is optically thick up to
m, further supporting the extremely dusty nature.
Spatially resolved analysis of the -dark galaxy reveals a largely uniform
area spanning 57 kpc, which spatially matches to
the ALMA 1 mm continuum emission. Accounting for the surface brightness dimming
and the depths of current surveys, unlensed analogs of the -dark
galaxy at would be only detectable in F356W and F444W in UNCOVER-like
survey, and become totally -dark at . This suggests that
detecting highly attenuated galaxies in the Epoch of Reionization might be a
challenging task for .Comment: 15 pages, 5 figures, 1 table. Accepted to ApJ
Massive galaxy formation caught in action at z~5 with JWST
We report the discovery of a compact group of galaxies, CGG-z5, at z~5.2 in
the EGS field covered by the JWST/CEERS survey. CGG-z5 was selected as the
highest overdensity of galaxies at z>2 in recent JWST public surveys and it
consists of six candidate members lying within a projected area of
(1020~kpc). All group members are HST/F435W and
HST/F606W dropouts while securely detected in the JWST/NIRCam bands, yielding a
narrow range of robust photometric redshifts . The most massive
galaxy in the group has a stellar mass log, while
the rest are low-mass satellites (log). While
several group members were already detected in the HST and IRAC bands, the low
stellar masses and the compactness of the structure required the sensitivity
and resolution of JWST for its identification. To assess the nature and
evolutionary path of CGG-z5, we searched for similar compact structures in the
\textsc{Eagle} simulations and followed their evolution with time. We find that
all the identified structures merge into a single galaxy by z=3 and form a
massive galaxy (log) at z~1. This implies that CGG-z5
could be a "proto-massive galaxy" captured during a short-lived phase of
massive galaxy formation.Comment: A&A Letter in pres
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