6,427 research outputs found
Audiomobiles, Sculptures and Conundrums
No full textRoberto Gerhard was a pioneer of electronic music in England creating a number of substantial concert, theatre and radio works from as early as 1954. Gerhard’s electronic music is one of the richest repositories for understanding the development of the composer’s late compositional technique. Apart from the Symphony no.3, ‘Collages’, none of Gerhard’s electronic music is published. This paper will discuss aspects of Gerhard’s electronic music, focusing on Audiomobiles (1958-59) and Sculptures (1963)
The formation and cosmic evolution of dust in the early Universe. I. Dust sources
No full textDust-obscured star formation has dominated the cosmic history of star formation, since z ≃4 . However, the recent finding of significant amount of dust in galaxies out to z ≃8 has opened the new frontier of investigating the origin of dust also in the earliest phases of galaxy formation, within the first 1.5 billion years from the Big Bang. This is a key and rapid transition phase for the evolution of dust, as galaxy evolutionary timescales become comparable with the formation timescales of dust. It is also an area of research that is experiencing an impressive growth, especially thanks to the recent results from cutting edge observing facilities, ground-based, and in space. Our aim is to provide an overview of the several findings on dust formation and evolution at z >4 , and of the theoretical efforts to explain the observational results. We have organized the review in two parts. In the first part, presented here, we focus on dust sources, primarily supernovae and asymptotic giant branch stars, and the subsequent reprocessing of dust in the interstellar medium, through grain destruction and growth. We also discuss other dust production mechanisms, such as Red Super Giants, Wolf-Rayet stars, Classical Novae, Type Ia Supernovae, and dust formation in quasar winds. The focus of this first part is on theoretical models of dust production sources, although we also discuss the comparison with observations in the nearby Universe, which are key to put constraints on individual sources and processes. While the description has a general applicability at any redshift, we emphasize the relative role of different sources in the dust build-up in the early Universe. In the second part, which will be published later on, we will focus on the recent observational results at z >4 , discussing the theoretical models that have been proposed to interpret those results, as well as the profound implications for galaxy formation
Roberto Gerhard’s Sound Compositions: A Historical-Philological Perspective. Archive, Process, Intent and reenactment
No full textThis research advances the current state of knowledge in the field of early tape music both empirically and methodologically. The purpose of this study is to evaluate the impact that the electronic medium exerted in the musical thinking of Roberto Gerhard, one of the most outspoken, prolific and influential composers in the Spanish diaspora whose musical legacy, for the most part unknown, is a major landmark in the early history of electroacoustic music. Gerhard’s personal tape collection, one of the largest historical archives of its kind reported in the literature, is exceptional for both its antiquity (50+-year-old tapes) and its abundance of production materials. Through the digitisation and analysis of the composer’s tape collection this research argues that the empirical study of audio documents sets out a basis for a broader understanding of textual processes. More specifically, the research demonstrates that the reconstruction of works based on magnetic tape sketches is a powerful method to advance the understanding of early tape music. This research also examines Gerhard’s sound compositions in relation to the post-war context in which they were composed. Finally, this research presents performance documentation that proposes an approach to the electroacoustic music repertoire in which creativity is not at odds with rigor and critical discernment demonstrating that archival study can be closely aligned to the concept of re-enactment
Observational constrains on the chemical evolution of high redshift galaxies through 3D spectroscopy.
No full textIn this thesis I investigate the properties of 34 star forming galaxies at z ~3.4, by exploiting data
obtained with the VLT near-infrared integral field spectrometer SINFONI. By using the SINFONI
spectra, along with multi-band photometric images, I investigate the metal content, dynamics and
star formation in these galaxies.
One of the most important results is that z~ 3.4 galaxies deviate from the scaling relations between
mass, star formation rate and metallicity characterizing local and low redshift galaxies (z<2), in the
sense that galaxies at z>3 are characterized by metallicities significantly lower. This deviation
occurring only at z>3 must trace a different galaxy evolutionary mechanism in place at such early
epochs, with respect to galaxies at 0<z<2. However, I show that the deviation from the local scaling
relations is not associated with dynamics of the host galaxy (rotating disks and mergers/interacting
galaxies deviate by the same amount), hence an increased rate of merging cannot be responsible for
such deviations.
By using the integral field spectroscopic information I could map the metallicity in a subsample of
10 galaxies at z ~3.4. These are among the first metallicity gradients measured at such high redshift.
We find that a significant fraction of galaxies are characterized by inverted (positive) metallicity
gradients, i.e. the metallicity increases towards the outer regions, in contrast to what observed locally.
Also for what concerns the metallicity gradients, I found that the occurrence of inverted gradients
is not correlated with the galaxy dynamical properties. A more detailed investigation reveals that
the metallicity anticorrelates with the star formation rate, which peaks in the central region of
galaxies. This result supports the models of smooth gas inflows feeding galaxies at high redshift. In
this scenario the pristine infall both boosts star formation (through the Schmidt-Kennicutt law) and
dilutes the metallicity, generating the observed anti-correlation.
By mapping the distribution of the star formation, and by inverting the Schmidt-Kennicutt relation,
I could also infer the distribution and total content of molecular gas in these z~ 3 galaxies. I found evidence
that the average gas fraction in galaxies at z>3 does not follow the steep increasing evolution
from z=0 to z ~2. Between z~ 2 and z~ 3 the average gas fraction in galaxies remains constant or,
possibly, even decreases. Our findings are marginally consistent with the models expectations on the
evolution of the gas content in galaxies and further support the scenario that the evolution of cosmic
star formation in galaxies is primarily driven by the evolution of the amount of gas in galaxies, and
not by an evolution in the efficiency of star formation.
By combining the information on the gas content and on the metallicity I could infer the galaxy
properties can only be explained by a combination of massive inflows and massive outflows, both
of which a factor of few to several higher than in the host galaxy. Such massive flows in the early
universe are likely responsible for the different properties and deviations of galaxies at z 3 relative
to local and low redshift galaxies.
I further explore the physical mechanisms driving galaxy formation and evolution by comparingmy
observational results with detailed semi-analytical models and cosmological simulations specifically
developed, in collaboration with other teams, to trace the metallicity evolution and distribution in
early galaxies.This work was funded by the Marie Curie Initial Training Network ELIXIR of the European Commission
under contract PITN-GA-2008-214227
Quasar feedback in the early Universe: The case of SDSS J1148+5251
No full textGalaxy-scale gas outflows triggered by active galactic nuclei have been proposed as a key physical process to regulate the co-evolution of nuclear black holes and their host galaxies. The recent detection of a massive gas outflow in one of the most distant quasars, SDSS J1148+5251 at z = 6.4, presented by Maiolino et al., strongly supports this idea and suggests that strong quasar feedback is already at work at very early times. In a previous work, Valiante et al., we have presented a hierarchical semi-analytical model, GAMETE/QSOdust, for the formation and evolution of high-redshift quasars, and we have applied it to the quasar SDSS J1148+5251, with the aim of investigating the star formation history, the nature of the dominant stellar populations and the origin and properties of the large dust mass observed in the host galaxy. A robust prediction of the model is that the evolution of the nuclear black hole and of the host galaxy are tightly coupled by quasar feedback in the form of strong galaxy-scale winds. In the present Letter, we show that the gas outflow rate predicted by GAMETE/QSOdust is in good agreement with the lower limit of 3500 M circle dot yr(-1) inferred by the observations. According to the model, the observed outflow at z = 6.4 is dominated by quasar feedback, as the outflow rate has already considerably depleted the gas content of the host galaxy, leading to a downturn in the star formation rate at z <78. Hence, we predict that supernova explosions give a negligible contribution to the observed winds at z = 6.4
Filologia editoriale, Roberto Calasso in dialogo con Paola Italia e Francisco Rico
No full textPaola Italia e Francisco Rico intervengono sul libro di Roberto Calasso, presidente e fondatore di Adelphi Edizioni, L'impronta dell'editore, e discutono di problemi di filologia delle forme editoriali, dal punto di vista dell'autore, del lettore e dell'editore.Paola Italia and Francisco Ricos interview Roberto Calasso, Publisher, Writer, and Founder of Adelphi Edizioni, about his book: L'impronta dell'editore, talking about philology, publishing and editing, from the author, the reader and the publisher's point of view
Roberto Tibau and the process of making architecture
No full textEste estudo documenta a vida e a obra de Roberto José Goulart Tibau (1924-2003), arquiteto brasileiro. O objetivo fundamental - e mais importante - é reunir informações sobre os projetos e obras mais significativos desenvolvidos durante sua atividade profissional, tornando-os acessíveis através dessa pesquisa. O trabalho baseou-se em pesquisa bibliográfica, levantamento e registro das obras e projetos realizados, currículo profissional, e depoimento de Tibau, concedido ao autor, em 1998. Em Roberto Tibau e o fazer arquitetura são descritos os caminhos percorridos pelo arquiteto; o contexto histórico de sua formação e atuação profissional; a relação de sua produção arquitetônica com outras obras da época; e eventuais referências projetuais utilizadas na criação dos seus projetos. Este trabalho vem preencher uma lacuna bibliográfica considerável, trazendo à luz, a obra deste significativo arquiteto, que dedicou sua vida ao trabalho na prancheta, na qual deixou sua marca de humanista.This study documents the life and work of Roberto José Goulart Tibau (1924-2003), a Brazilian architect. It aims to collect information about the most significant projects developed during the years of his professional career, which will become available through this research. The present study based on bibliographical research, examination and registration of the projects executed by the architect, his resumé, and his testimonial to the author of this research, in 1998. In Roberto Tibau and the process of making architecture there is a description of the ways in which his projects were conceived; the historical context through his professional activity since graduation, the relation between his own production and the production of other architects of the same period, and the projecting references used for his creations. This research is also an attempt to fill a signicant bibliographical gap of architecture history in Brazil by bringing to light the work of this relevant architect, who dedicated his life to working on his drawing table, leaving to us his humanistic style
Roberto Bolaño, la memoria antiheroica del exilio chileno
No full textThis article discusses the personality and the work of the Chilean writer Roberto Bolaño in an attempt to expand on the relationship between the author and his homeland Chile. Even though Bolaño left Chile at an early age and lived in many countries throughout his life, he tried to regain his roots as reflected in the novels about the Chilean dictatorship, Estrella distante and Nocturno de Chile. The author also attempts to vindicate his own origin in his literary alterego Arturo Belano. Thus, this article will highlight and analyse the relation between Roberto Bolaño and Chile through the antiheroic vision given not only to the characters but also to the settings of the narratives.Este artículo se centra en la personalidad del escritor chileno Roberto Bolaño y su obra para profundizar en la relación existente entre el autor y Chile, su país de origen. Pese a haber abandonado el país siendo muy joven y a haber residido en otros países a lo largo de su vida, Bolaño nunca perdió el interés por recuperar sus raíces chilenas tanto como lo reflejan las novelas que dedica a la dictadura chilena, Estrella distante y Nocturno de Chile sobre todo, así como por reivindicar su propio origen a través de su álter ego literario Arturo Belano. En este artículo se señalarán y analizarán estas relaciones entre Roberto Bolaño y Chile a través de la visión antiheroica que el autor confiere tanto a los ambientes como a los personajes que articulan su narrativa
First CO(17–16) emission line detected in a z > 6 quasar
No full textWe report the serendipitous detection of the CO(17-16) emission line toward
the quasar SDSSJ114816.64+525150.3 (J1148) at redshift z = 6.4 obtained with
the Plateau de Bure Interferometer. The CO(17-16) line is possibly contaminated
by OH+ emission, that may account for ~ 35 - 60% of the total flux observed.
Photo-Dissociation and X-ray Dominated Regions (PDRs and XDRs) models show that
PDRs alone cannot reproduce the high luminosity of the CO(17-16) line relative
to low-J CO transitions and that XDRs are required. By adopting a composite
PDR+XDR model we derive molecular cloud and radiation field properties in the
nuclear region of J1148. Our results show that highly excited CO lines
represent a sensitive and possibly unique tool to infer the presence of X-ray
faint or obscured supermassive black hole progenitors in high-z galaxies
Physical properties of the first quasars
No full textSince the beginning of the new millennium, more than 100 quasars
have been discovered through several surveys and followed-up with
multi-wavelength observations. These data provided a large amount of
information on the growth of supermassive black holes at the early epochs, the
properties of quasar host galaxies and the joint formation and evolution of
these massive systems. We review the properties of the highest- quasars
known so far, especially focusing on some of the most recent results obtained
in (sub-)millimeter bands. We discuss key observational challenges and open
issues in theoretical models and highlight possible new strategies to improve
our understanding of the galaxy-black hole formation and evolution in the early
Universe
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