Deep multi-frequency radio observations of the SHADES fields and the nature of the faint radio populaton

The two SCUBA HAlf-Degree Extragalactic Survey (SHADES) fields are amongst the richest places in the sky in terms of multi-wavelength coverage. They comprise an eastern section of the Lockman Hole (LH) and the central portion of the Subaru- XMM/Newton Deep Field (SXDF). In this thesis, I have obtained extremely deep, multi-frequency radio imaging of the SHADES fields using the GiantMetre-wave Radio Telescope (GMRT) and the Very Large Array (VLA), at 610MHz and 1.4GHz, respectively. These data are used to analyse the nature of the sub-milliJansky (sub-mJy) radio population, which has been hotly debated in the last few years: are they powered by star-forming or nuclear activity? To tackle the problem, I employ different approaches making use of the large variety of multi-wavelength data in the SHADES fields. I begin by analysing the spectral index, α610MHz 1.4GHz , of radio sources detected in the LH, to explore the dominant emission mechanism. Based on a robust 10 σ detection criterion, I find a constantmedian spectral index of α610MHz 1.4GHz ≈ −0.6 to −0.7 for sources between S1.4GHz ≈ 200 μJy and 10mJy. This result suggests that the galaxy population in the sub-mJy regime is powered by optically-thin synchrotron emission – starforming galaxies or lobe-dominated active galactic nuclei (AGN). Making use of X-ray observations in the LH, I show that the fraction of radio sources detected in the hard X-ray band (between 2 and 10 keV) decreases from 50 to 15 per cent between S1.4GHz ≈ 1mJy and . 100 μJy, which strongly suggests a transition from AGN to star-forming galaxies. Based on the deep, multi-wavelength coverage of the SXDF, I explore the behaviour of the far-infrared (FIR)/radio correlation as a function of redshift. I combine the q24 factor – the logarithmic flux density ratio between Spitzer 24-μm and VLA 1.4- GHz flux densities – with available photometric redshifts and find strong evidence that the correlation holds out to z ≈ 3.5. Based on M82-like k-corrections and using a high-significance (S1.4GHz > 300 μJy) radio sub-sample, I find a mean and scatter of q24 = 0.71 ± 0.47. Monte-Carlo simulations based on these findings show that fewer sources deviate from the correlation at fainter flux densities (i.e. fewer radioloud AGN). I predict that the radio-loud fraction drops from 50 per cent at ∼ 1mJy to zero at . 100 μJy. The validity of the FIR/radio correlation out to very high redshifts adds credibility to identifications of sub-millimetre (submm) galaxies (SMGs) made at radio wavelengths. Based on a sample of 45 radio-identified SMGs in the LH, I find a median radio spectral index of α610MHz 1.4GHz = −0.72 ± 0.07, which suggests that optically-thin synchrotron is the dominant radio emission mechanism. Finally, as anAppendix I include a theoretical treatment that constrains the average geometry of the dusty, torus-like structures believed to obscure a large fraction of the AGN population. I use the distribution of column densities (NH) obtained from deep ∼ 1Msec X-ray observations in the Chandra Deep Field South. I find that to reproduce the wide observed range of NH, the best torus model is given by a classical “donut”- shaped distribution with an exponential angular dependency of the density profile

La silla criolla argentina : Un estudio de las tipologías más relevantes de muebles para sentarse (urbano-rurales) de la República Argentina

En este trabajo abordamos la siguiente pregunta: ¿se puede considerar que dentro de la producción de Arquitectura y Diseño de Interiores en la República Argentina podemos hablar de un estilo campo? Para poder responder la pregunta anterior, se debe poder responder: ¿qué es el estilo campo? ¿A qué nos referimos cuando hablamos de estilo campo? Para lo cual se deberán establecer algunas categorías teórico-analíticas previas, el lenguaje de diseño. En efecto, son los paradigmas y categorías analíticas de orden moderno los que entran en juego para analizar el diseño pre-moderno gauchesco, con reminiscencias inspiradas en la cultura aborigen sudamericana. Para lo cual se efectuara un desarrollo teórico-analítico basado en la semiología de las necesidades funcionales, estéticas y simbólicas de la silla (caso de estudio). En efecto, la silla, ese mueble de culto fue, es y será objeto de deseo y análisis teórico constructivo (material), antropológico y estético-simbólico por parte de arquitectos y diseñadores industriales profesionales. Nos centraremos en un abordaje cultural amplio, híbrido y complejo que dé cuenta de su profundidad histórica. También de la influencia cultural que el Nuevo Mundo -en Sudamérica y Argentina principalmente- recibió del Viejo Mundo -de la Península Ibérica y España principalmente- a partir del descubrimiento-conquista que significó Cristóbal Colón (1451-1506).In this work we address the following question: can it be considered that within the production of Architecture and Interior Design in the Argentine Republic we can speak of a country style? In order to answer the previous question, it must be possible to answer: what is the field style? What do we mean when we talk about “country style”? For which some previous theoretical-analytical categories must be established, the design language. Indeed, it is the paradigms and analytical categories of a modern order that come into play to analyze the pre-modern gaucho design, with reminiscences inspired by the South American aboriginal culture. For which a theoretical-analytical development will be carried out based on the semiology of the functional, aesthetic and symbolic needs of the chair (case study). Indeed, the chair, that cult piece of furniture was, is and will be the object of desire and theoretical constructive (material), anthropological and aesthetic-symbolic analysis by architects and professional industrial designers. We will focus on a broad, hybrid and complex cultural approach that accounts for its historical depth. Also from the cultural influence that the New World –in South America and Argentina mainly– received from the Old World –from the Iberian Peninsula and Spain mainly– from the discovery-conquest that Christopher Columbus (1451-1506) meant.Facultad de Arte

Scattering de electrones fuertemente interactuantes en nanotiras

El principal objetivo de este trabajo es el desarrollo de un trabajo teórico sobre el estudio del transporte y scattering de electrones interactuantes contra un Quantum Dot, usando como modelo un Hamiltoniano tipo tight-binding. Para realizar esta tarea haremos uso de una técnica de redes tensoriales conocida como Matrix Product States (MPS), así como otros métodos aproximados como la aproximación de Suzuki-trotter o la evolución en tiempo imaginario. El algoritmo que desarrollaremos permitirá el estudio del scattering y fenómenos de interacción, permitiéndonos también el estudio no solo de uno sino de varios electrones en proyectos futuros

ALMA reveals the molecular gas properties of five star-forming galaxies across the main sequence at 3

International audienceWe present the detection of CO(5-4) with S/N> 7 - 13 and a lower CO transition with S/N > 3 (CO(4-3) for 4 galaxies, and CO(3-2) for one) with ALMA in band 3 and 4 in five main sequence star-forming galaxies with stellar masses 3-6x10^10 M/M_sun at 3 < z < 3.5. We find a good correlation between the total far-infrared luminosity LFIR and the luminosity of the CO(5-4) transition L'CO(5-4), where L'CO(5-4) increases with SFR, indicating that CO(5-4) is a good tracer of the obscured SFR in these galaxies. The two galaxies that lie closer to the star-forming main sequence have CO SLED slopes that are comparable to other star-forming populations, such as local SMGs and BzK star-forming galaxies; the three objects with higher specific star formation rates (sSFR) have far steeper CO SLEDs, which possibly indicates a more concentrated episode of star formation. By exploiting the CO SLED slopes to extrapolate the luminosity of the CO(1-0) transition, and using a classical conversion factor for main sequence galaxies of alpha_CO = 3.8 M_sun(K km s^-1 pc^-2)^-1, we find that these galaxies are very gas rich, with molecular gas fractions between 60 and 80%, and quite long depletion times, between 0.2 and 1 Gyr. Finally, we obtain dynamical masses that are comparable with the sum of stellar and gas mass (at least for four out of five galaxies), allowing us to put a first constraint on the alpha_CO parameter for main sequence galaxies at an unprecedented redshift

Resolving debris discs in the far-infrared: early highlights from the DEBRIS survey

We present results from the earliest observations of DEBRIS, a Herschel Key Programme to conduct a volume- and flux-limited survey for debris discs in A-type through M-type stars. PACS images (from chop/nod or scan-mode observations) at 100 and 160 micron are presented toward two A-type stars and one F-type star: beta Leo, beta UMa and eta Corvi. All three stars are known disc hosts. Herschel spatially resolves the dust emission around all three stars (marginally, in the case of beta UMa), providing new information about discs as close as 11 pc with sizes comparable to that of the Solar System. We have combined these data with existing flux density measurements of the discs to refine the SEDs and derive estimates of the fractional luminosities, temperatures and radii of the discs.Comment: to be published in A&A, 5 pages, 2 color figure

Interannual Climate Variability in the West Antarctic Peninsula under Austral Summer Conditions

[EN] This study aimed to describe the interannual climate variability in the West Antarctic Peninsula (WAP) under austral summer conditions. Time series of January sea-surface temperature (SST) at 1 km spatial resolution from satellite-based multi-sensor data from Moderate Resolution Imaging Spectrometer (MODIS) Terra, MODIS Aqua, and Visible Infrared Imager Radiometer Suite (VIIRS) were compiled between 2001 and 2020 at localities near the Gerlache Strait and the Carlini, Palmer, and Rothera research stations. The results revealed a well-marked spatial-temporal variability in SST at the WAP, with a one-year warm episode followed by a five-year cold episode. Warm waters (SST > 0 degrees C) reach the coast during warm episodes but remain far from the shore during cold episodes. This behavior of warm waters may be related to the regional variability of the Antarctic Circumpolar Current, particularly when the South Polar Front (carrying warm waters) reaches the WAP coast. The WAP can be divided into two zones representing two distinct ecoregions: the northern zone (including the Carlini and Gerlache stations) corresponds to the South Shetland Islands ecoregion, and the southern zone (including the Palmer and Rothera stations) corresponds to the Antarctic Peninsula ecoregion. The Gerlache Strait is likely situated on the border between the two ecoregions but under a greater influence of the northern zone. Our data showed that the Southern Annular Mode (SAM) is the primary driver of SST variability, while the El Nino Southern Oscillation (ENSO) plays a secondary role. However, further studies are needed to better understand regional climate variability in the WAP and its relation with SAM and ENSO; such studies should use an index that adequately describes the ENSO in these latitudes and addresses the limitations of the databases used for this purpose. Multi-sensor data are useful in describing the complex climate variability resulting from the combination of local and regional processes that elicit different responses across the WAP. It is also essential to continue improving SST approximations at high latitudes.This work was supported by the Universidad Autónoma de Baja California, AmeriGEOSS, and the CONACYT's project number CB-2012-01/179753.Santamaría-Del-Ángel, E.; Cañón-Páez, M.; Sebastiá-Frasquet, M.; González-Silvera, A.; Gutiérrez, A.; Aguilar-Maldonado, JA.; López-Calderón, J.... (2021). Interannual Climate Variability in the West Antarctic Peninsula under Austral Summer Conditions. Remote Sensing. 13(6). https://doi.org/10.3390/rs1306112213

Detailed modelling of a large sample of Herschel sources in the Lockman Hole: identification of cold dust and of lensing candidates through their anomalous SEDs

We have studied in detail a sample of 967 SPIRE sources with 5σ detections at 350 and 500 μm and associations with Spitzer-SWIRE 24 μm galaxies in the HerMES-Lockman survey area, fitting theirmid- and far-infrared, and submillimetre, spectral energy distributions (SEDs) in an automatic search with a set of six infrared templates. For almost 300 galaxies,we havemodelled their SEDs individually to ensure the physicality of the fits. We confirm the need for the new cool and cold cirrus templates, and also of the young starburst template, introduced in earlier work. We also identify 109 lensing candidates via their anomalous SEDs and provide a set of colour–redshift constraints which allow lensing candidates to be identified from combined Herschel and Spitzer data. The picture that emerges of the submillimetre galaxy population is complex, comprising ultraluminous and hyperluminous starbursts, lower luminosity galaxies dominated by interstellar dust emission, lensed galaxies and galaxies with surprisingly cold (10–13 K) dust. 11 per cent of 500 μm selected sources are lensing candidates. 70 per cent of the unlensed sources are ultraluminous infrared galaxies and 26 per cent are hyperluminous. 34 per cent are dominated by optically thin interstellar dust (‘cirrus’) emission, but most of these are due to cooler dust than is characteristic of our Galaxy. At the highest infrared luminosities we see SEDs dominated by M82, Arp 220 and young starburst types, in roughly equal proportions

ALMA Reveals the Molecular Gas Properties of Five Star-forming Galaxies across the Main Sequence at 3

We present the detection of CO (5−4) with signal-to-noise ratio (S/N) > 7-13 and a lower CO transition with S/N > 3 (CO (4−3) for four galaxies, and CO (3−2) for one) with the Atacama Large Millimeter/submillimeter Array in bands 3 and 4 in five main-sequence (MS) star-forming galaxies with stellar masses (3-6) x 1010 M ⊙ at 3 < z < 3.5. We find a good correlation between the total far-infrared luminosity L FIR and the luminosity of the CO (5−4) transition ${L}_{\mathrm{CO}(5-4)}^{{\prime} }$, where ${L}_{\mathrm{CO}(5-4)}^{{\prime} }$ increases with star formation rate (SFR), indicating that CO (5−4) is a good tracer of the obscured SFR in these galaxies. The two galaxies that lie closer to the star-forming MS have CO spectral line energy distribution (SLED) slopes that are comparable to other star-forming populations, such as local submillimeter galaxies and BzK star-forming galaxies; the three objects with higher specific star formation rates have far steeper CO SLEDs, which possibly indicates a more concentrated episode of star formation. By exploiting the CO SLED slopes to extrapolate the luminosity of the CO (1−0) transition and using a classical conversion factor for MS galaxies of ${\alpha }_{\mathrm{CO}}=3.8\,{M}_{\odot }{({\rm{K}}\mathrm{km}{{\rm{s}}}^{-1}{\mathrm{pc}}^{-2})}^{-1}$, we find that these galaxies are very gas-rich, with molecular gas fractions between 60% and 80% and quite long depletion times, between 0.2 and 1 Gyr. Finally, we obtain dynamical masses that are comparable to the sum of stellar and gas mass (at least for four out of five galaxies), allowing us to put a first constraint on the α CO parameter for MS galaxies at an unprecedented redshift.This work is based on ALMA data from the project ADS/JAO. ALMA#2015.1.01590.S. ALMA is a partnership of ESO (representing its member states), NSF (USA), and NINS (Japan), together with NRC (Canada), NSC and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/ NRAO, and NAOJ. We are grateful for the support from the Italian regional ALMA ARC. P.C. and L.M. acknowledge support from the BIRD 2018 research grant from the Università degli Studi di Padova; P.C. acknowledges support from the CONICYT/FONDECYT program No. 1150216; E.I. acknowledges partial support from FONDECYT through grant No. 1171710; D.L. and E.S. acknowledge funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 694343)