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Gas e polvere freddi nelle galassie ospiti dei QSOs a z>6
No full textI QSOs luminosi, alimentati dall'accrescimento su buchi neri supermassicci (SMBHs), erano già presenti durante l'Epoca della Reionizzazione (EoR), quando l'Universo aveva solo 0.5-1 miliardo di anni. Negli ultimi decenni, Herschel, il Northern Extended Millimeter Array (NOEMA), il Very Large Array (VLA) e, in particolare, l'Atacama Large Millimeter/sub-millimeter Array (ALMA) ci hanno permesso di approfondire le proprietà del gas e della polvere all'interno del mezzo interstellare delle galassie ospiti dei QSOs. Queste proprietà sono fondamentali per svelare l'origine e la natura di questi primi QSOs.
L'obiettivo di questa tesi è quello di condurre un'analisi del gas freddo e della polvere nelle galassie ospiti dei QSOs nell'EoR, gettando luce sulle proprietà di questi oggetti, sulla loro formazione ed evoluzione. Presenterò i risultati su un campione di 12 QSOs a 66 (Zappacosta+2023), alimentati dai SMBHs in più rapida crescita e più massicci del loro epoca, e probabilmente assemblati dai semi di buchi neri più grandi, o che hanno avuto storie di accrescimento di massa particolari, possibilmente supercritiche.
Mostrerò analisi delle osservazioni NOEMA e ALMA a risoluzione sub-kpc che ci hanno permesso di condurre uno studio dettagliato della cinematica e dinamica del gas nelle galassie ospiti del nostro campione, rivelando segni di mergers, dischi di H2O, potenti outflows e fornendo le prime rivelazioni di CO a z>7. Abbiamo anche effettuato una decomposizione dinamica della curva di rotazione del QSO J2310+1855 a z=6.0031, basata su osservazioni ad alta risoluzione di ALMA, e abbiamo scoperto che la massa del SMBH di 5x10^9 Msun non è sufficiente a spiegare le alte velocità nelle regioni centrali. Il nostro modello dinamico suggerisce la presenza di un bulge stellare con una massa di M_ bulge~10^10 Msun in questo oggetto, quando l'Universo aveva meno di 1 miliardo di anni.
Inoltre, grazie alle osservazioni senza precedenti di ALMA a frequenza molto elevata (670 GHz, Banda 9), abbiamo modellato con precisione la distribuzione spettrale di energia (SED) della polvere fredda dei QSOs nel nostro campione e ottenuto una determinazione affidabile e precisa delle proprietà della polvere, come la temperatura della polvere, la massa della polvere e l'indice di emissività della polvere, nonché una stima precisa del tasso di formazione stellare delle galassie ospiti dei QSO. Discuteremo l'importanza delle osservazioni ad alta frequenza nel derivare le proprietà della polvere e il tasso di formazione stellare, nonché le sistematiche introdotte dalla presenza dell'AGN centrale come ulteriore fonte di riscaldamento della polvere.
Ci concentreremo anche sulle proprietà di 10 QSOs nel nostro campione e discuteremo lo scenario evolutivo di questi oggetti. Infatti, la straordinaria crescita di massa dei SMBHs nell'EoR e la sua relazione con la crescita simultanea delle galassie ospiti pone sfide ai modelli teorici volti a spiegare come questi sistemi si siano formati su tempi brevi (<1 miliardo di anni). Per tracciare i percorsi evolutivi medi dei QSOs e delle loro galassie ospiti nel piano della massa del BH rispetto alla massa della galassia (M_dyn), si confronta il tasso di formazione stellare, derivato dalla stima accurata della temperatura della polvere e dalla massa della polvere basata sulle SED nell'infrarosso e nel submillimetro, con il tasso di accrescimento del BH, derivato da L_bol basato sulle SED nell’X-ray, nell'ottico e nell'ultravioletto. Di conseguenza, presenteremo lo studio del percorso evolutivo dei SMBHs e delle loro galassie ospiti nel nostro campione, con l'obiettivo finale di acquisire una comprensione più ampia delle proprietà dei QSOs ad alto redshift.Luminous quasi-stellar objects (QSOs), fueled by accretion onto supermassive black holes (SMBHs), were already in place during the Epoch of Reionisation (EoR), when the Universe was only 0.5-1 Gyr old. In recent decades, Herschel, the Northern Extended Millimeter Array (NOEMA), the Very Large Array (VLA), and, notably, the Atacama Large Millimeter/sub-millimeter Array (ALMA) have enabled us to delve into the properties of the gas and dust inside the inter stellar medium (ISM) of the QSO's host galaxies. These properties are pivotal in unraveling the assembly and nature of these early QSOs.
The goal of this Thesis is to perform a comprehensive analysis of the cold gas and dust in the host galaxies of QSOs at the EoR, shedding light on the properties of these objects and on their formation and evolution. I will present results on a sample of 12 QSOs at 66 QSOs (Zappacosta+2023), powered by the fastest growing and most massive SMBH at their epoch, and likely assembled from the largest BH seeds, or experienced peculiar, possibly supercritical, mass accretion histories. I will show analyses of NOEMA and ALMA (sub) kpc-resolution observations that allowed us to perform detailed study of the kinematics and dynamics of the gas in the host galaxies of our sample, revealing signatures of mergers, H2O disks, powerful outflows, and provided the first CO detections at z>7 (Tripodi+2022,Tripodi+2023a,Tripodi+2023b,Tripodi+2023c,Feruglio+2023). We also performed a dynamical decomposition of the rotation curve of QSO J2310+1855 at z=6.0031, based on high-resolution ALMA observations, and we found that the SMBH mass of 5x10^9 Msun is not sufficient to explain the high velocities in the central regions. Our dynamical model suggest the presence of a stellar bulge with a mass of M_bulge~ 10^10 Msun in this object, when the Universe was less than 1 Gyr old. Moreover, thanks to unprecedented ALMA observations at very high frequency (670 GHz, Band 9), we accurately modelled the cold dust SED of the QSOs in our sample, and we obtained a reliable and precise determination of the dust properties, such as dust temperature, dust mass and dust emissivity index, and a precise estimate for the SFR of the QSO’s host galaxies. We will discuss the importance of high frequency observations in deriving the dust properties and SFR, and the systematics introduced by the presence of the central AGN as an additional source of dust heating.
I will also focus on the properties of 10 quasars in our sample, and discuss the evolutionary scenario of these objects. Indeed, the outstanding mass growth of SMBHs at the EoR and its relation to the concurrent growth of their host galaxies poses challenges to theoretical models aimed at explaining how these systems formed on short timescales (<1 Gyr). To trace the average evolutionary paths of QSOs and their host galaxies in the plane of BH mass to host mass (M_dyn), we compare the SFR, derived from the accurate estimate of the dust temperature and the dust mass based on infrared and sub-millimeter (sub-mm) SED, with the BH accretion rate, derived from L_bol based on X-ray, optical and ultraviolet SED. Consequently, I will present the study of the evolutionary path of SMBHs and their host galaxies within our sample, with the ultimate goal of gaining a broader understanding of the properties of high-z QSOs
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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