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Gotowa bibliografia na temat „AGN Jet”

Autor: Grafiati

Data publikacji: 6 września 2023

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Artykuły w czasopismach na temat "AGN Jet"

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HOMAN, DANIEL C. "PHYSICAL PROPERTIES OF JETS IN AGN". International Journal of Modern Physics: Conference Series 08 (styczeń 2012): 163–71. http://dx.doi.org/10.1142/s2010194512004552.

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I review constraints on the physical properties of AGN jets revealed through Very Long Baseline Interferometry (VLBI) studies of the structure and time-evolution of parsec-scale jets, including recent results from the MOJAVE program. In particular I focus on constraints available from very long time baseline studies which probe a wide range of jet behavior over many outbursts. Kinematic studies of propagating jet features find an apparent speed distribution that peaks around 10c for blazars, with speeds up to 50c observed. These observed speeds require Lorentz factors at least as large, implying that parsec-scale Lorentz factors up to 10-20 are common for blazars with a tail up to ~ 50. Jet flows are still becoming organized on these scales as evidenced by the high incidence of non-radial motions and/or accelerations of jet features (including increases and decreases in apparent speed and direction). Changes in Lorentz factors of propagating jet features appear to play a significant role in the observed accelerations, and while the connection between acceleration of jet features and the underlying flow is not clear, the pattern of observed accelerations suggest the flow may increase in speed near the base of the jet and decrease further out. In some jets, ejections of new features span a range of ejection angles over many epochs, tracing out wider opening angles on parsec-scales than are apparent in single epoch observations.

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Sbarrato, Tullia, Paolo Padovani i Gabriele Ghisellini. "The jet–disc connection in AGN". Proceedings of the International Astronomical Union 10, S313 (wrzesień 2014): 48–52. http://dx.doi.org/10.1017/s1743921315001854.

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AbstractWe present our latest results on the connection between the accretion rate and the power of relativistic jets. To this aim we use blazars, whose jet is pointing at us, with visible broad emission lines, along with broad lineless radio–galaxies. We trace the jet power with two proxies (gamma–ray and radio luminosities), while the broad emission lines are a direct measure of the accretion disc luminosity. We find a correlation between the broad emission line and the gamma–ray or luminosities in blazars, suggesting a direct tight connection between the jet and the accretion rate. Only extending our analysis to radio–galaxies, and using as jet tracer the radio luminosity, we are finally able to conclude that jetted AGN can accrete both through a radiatively efficient accretion disc and a hot accretion flow, depending on the accretion rate. We finally observe the transition between the two states among the family of jetted AGN.

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Tanner, Ryan, i Kimberly A. Weaver. "Simulations of AGN-driven Galactic Outflow Morphology and Content". Astronomical Journal 163, nr 3 (17.02.2022): 134. http://dx.doi.org/10.3847/1538-3881/ac4d23.

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Abstract Using a series of 3D relativistic hydrodynamical simulations of active galactic nuclei (AGN) we investigate how AGN power, a clumpy interstellar medium (ISM) structure, and AGN jet angle with respect to the galactic disk affect the morphology and content of the resulting galactic outflow. For low-power AGN across three orders of magnitude of AGN luminosities (1041–1043 erg s−1) our simulations did not show significant changes to either the morphology or total mass of the outflow. Changing the angle of the AGN jet with respect to the galaxy did show small changes in the total outflow mass of a factor of 2–3. Jets perpendicular to the galactic disk created hot single-phase outflows, while jets close to parallel with the disk created multiphase outflows with equal parts warm and hot, and significant cold gas. Overall the final morphology of low-power AGN outflows depends primarily on how the jet impacts and interacts with large, dense clouds in the clumpy ISM. These clouds can disrupt, deflect, split, or suppress the jet, preventing it from leaving the galactic disk as a coherent structure. But for simulations with AGN luminosities > 1044 erg s−1 the ISM played a minor role in determining the morphology of the outflow with an undisrupted jet leaving the disk. The final morphology of AGN outflows is different for low-power AGNs versus high-power AGNs with the final morphology of low-power AGN outflows dependent on the ISM structure within the first kiloparsec surrounding the AGN.

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King, Ashley L., Anne Lohfink i Erin Kara. "AGN Coronae through a Jet Perspective". Astrophysical Journal 835, nr 2 (31.01.2017): 226. http://dx.doi.org/10.3847/1538-4357/835/2/226.

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Ferrari, Attilio. "Agn Jet Modeling: Setting the Stage". Astrophysics and Space Science 293, nr 1/2 (2004): 15–26. http://dx.doi.org/10.1023/b:astr.0000044648.48465.1a.

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Sbarrato, T., P. Padovani i G. Ghisellini. "The jet–disc connection in AGN". Monthly Notices of the Royal Astronomical Society 445, nr 1 (22.09.2014): 81–92. http://dx.doi.org/10.1093/mnras/stu1759.

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Gurvits, Leonid I., Sándor Frey i Zsolt Paragi. "Jets in AGN at extremely high redshifts". Proceedings of the International Astronomical Union 10, S313 (wrzesień 2014): 327–28. http://dx.doi.org/10.1017/s1743921315002434.

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The jet phenomenon is a trademark of active galactic nuclei (AGN). In most general terms, the current understanding of this phenomenon explains the jet appearance by effects of relativistic plasma physics. The fundamental source of energy that feeds the plasma flow is believed to be the gravitational field of a central supermassive black hole. While the mechanism of energy transfer and a multitude of effects controlling the plasma flow are yet to be understood, major properties of jets are strikingly similar in a broad range of scales from stellar to galactic. They are supposed to be controlled by a limited number of physical parameters, such as the mass of a central black hole and its spin, magnetic field induction and accretion rate. In a very simplified sense, these parameters define the formation of a typical core–jet structure observed at radio wavelengths in the region of the innermost central tens of parsecs in AGN. These core–jet structures are studied in the radio domain by Very Long Baseline Interferometry (VLBI) with milli- and sub-milliarcsecond angular resolution. Such structures are detectable at a broad range of redshifts. If observed at a fixed wavelength, a typical core–jet AGN morphology would appear as having a steep-spectrum jet fading away with the increasing redshift while a flat-spectrum core becoming more dominant. If core–jet AGN constitute the same population of objects throughout the redshift space, the apparent “prominence” of jets at higher redshifts must decrease (Gurvits 1999): well pronounced jets at high z must appear less frequent than at low z.

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Komissarov, Serguei. "The remarkable AGN jets". Proceedings of the International Astronomical Union 12, S324 (wrzesień 2016): 141–48. http://dx.doi.org/10.1017/s1743921317001922.

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AbstractThe jets from active galactic nuclei exhibit stability which seems to be far superior compared to that of terrestrial and laboratory jets. They manage to propagate over distances up to a billion of initial jet radii. Yet this may not be an indication of some exotic physics but mainly a reflection of the specific environment these jets propagate through. The key property of this environment is a rapid decline of density and pressure along the jet, which promotes its rapid expansion. Such an expansion can suppress global instabilities, which require communication across the jet, and hence ensure its survival over huge distances. At kpc scales, some AGN jets do show signs of strong instabilities and even turn into plumes. This could be a result of the flattening of the external pressure distribution in their host galaxies or inside the radio lobes. In this regard, we discuss the possible connection between the stability issue and the Fanaroff-Riley classification of extragalactic radio sources. The observations of AGN jets on sub-kpc scale do not seem to support their supposed lack of causal connectivity. When interpreted using simple kinematic models, they reveal a rather perplexing picture with more questions than answers on the jets dynamics.

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Kharb, Preeti, i Sasikumar Silpa. "Looking for Signatures of AGN Feedback in Radio-Quiet AGN". Galaxies 11, nr 1 (8.02.2023): 27. http://dx.doi.org/10.3390/galaxies11010027.

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In this article, we discuss the state of “AGN feedback” in radio-quiet (RQ) AGN. This study involves heterogeneous samples of nearby Seyfert and LINER galaxies as well as quasi-stellar objects (QSOs) that have been observed at low radio frequencies (few ∼100 MHz) with the upgraded Giant Meterwave Radio Telescope (GMRT) and ∼GHz frequencies with the Karl G. Jansky Very Large Array (VLA) and Very Long Baseline Array (VLBA). These multi-frequency, multi-resolution observations detect a range of arcsecond-scale radio spectral indices that are consistent with the presence of multiple contributors including starburst winds and AGN jets or winds; steep spectrum “relic” emission is observed as well. Polarization-sensitive data from the VLA and GMRT suggest that the radio outflows are stratified (e.g., in IIIZw2, Mrk231); distinct polarization signatures suggest that there could either be a “spine + sheath” structure in the radio outflow, or there could be a “jet + wind” structure. Similar nested biconical outflows can also explain the VLBA and SDSS emission-line data in the KISSR sample of double-peaked emission-line Seyfert and LINER galaxies. Furthermore, the modeling of the emission-lines with plasma modeling codes such as MAPPINGS indicates that parsec-scale jets and winds in these sources can disturb or move the narrow-line region (NLR) gas clouds via the “shock + precursor” mechanism. Apart from the presence of “relic” emission, several Seyfert and LINER galaxies show clear morphological signatures of episodic jet activity. In one such source, NGC2639, at least four distinct episodes of jets are observed, the largest one of which was only detectable at 735 MHz with the GMRT. Additionally, a ∼6 kpc hole in the CO molecular gas along with a dearth of young stars in the center of its host galaxy is observed. Multiple jet episodes on the 10–100 parsec scales and a ∼10 parsec hole in the molecular gas is also observed in the Seyfert galaxy NGC4051. This suggests a link between episodic jet activity in RQ AGN and “AGN feedback” influencing the evolution of their host galaxies. However, a similar simple relationship between radio outflows and molecular gas mass is not observed in the Palomar–Green (PG) QSO sample, indicating that “AGN feedback” is a complex phenomenon in RQ AGN. “AGN feedback” must occur through the local impact of recurring multi-component outflows in RQ AGN. However, global feedback signatures on their host galaxy properties are not always readily evident.

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Cielo, S., A. Babul, V. Antonuccio-Delogu, J. Silk i M. Volonteri. "Feedback from reorienting AGN jets". Astronomy & Astrophysics 617 (wrzesień 2018): A58. http://dx.doi.org/10.1051/0004-6361/201832582.

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Aims. We test the effects of re-orienting jets from an active galactic nucleus (AGN) on the intracluster medium in a galaxy cluster environment with short central cooling time. We investigate both the appearance and the properties of the resulting cavities, and the efficiency of the jets in providing near-isotropic heating to the cooling cluster core. Methods. We use numerical simulations to explore four models of AGN jets over several active/inactive cycles. We keep the jet power and duration fixed across the models, varying only the jet re-orientation angle prescription. We track the total energy of the intracluster medium (ICM) in the cluster core over time, and the fraction of the jet energy transferred to the ICM. We pay particular attention to where the energy is deposited. We also generate synthetic X-ray images of the simulated cluster and compare them qualitatively to actual observations. Results. Jets whose re-orientation is minimal (≲20°) typically produce conical structures of interconnected cavities, with the opening angle of the cones being ~15–20°, extending to ~300 kpc from the cluster centre. Such jets transfer about 60% of their energy to the ICM, yet they are not very efficient at heating the cluster core, and even less efficient at heating it isotropically, because the jet energy is deposited further out. Jets that re-orientate by ≳20° generally produce multiple pairs of detached cavities. Although smaller, these cavities are inflated within the central 50 kpc and are more isotropically distributed, resulting in more effective heating of the core. Such jets, over hundreds of millions of years, can deposit up to 80% of their energy precisely where it is required. Consequently, these models come the closest in terms of approaching a heating/cooling balance and mitigating runaway cooling of the cluster core even though all models have identical jet power/duration profiles. Additionally, the corresponding synthetic X-ray images exhibit structures and features closely resembling those seen in real cool-core clusters.

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Rozprawy doktorskie na temat "AGN Jet"

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Smith, Duncan Peter. "AGN jet-gas cloud interactions". Thesis, University of Bristol, 2017. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.761232.

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Omma, Henrik Nilsen. "Jet-powered cooling cores : reversing cooling flows through AGN activity". Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419330.

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Cielo, Salvatore [Verfasser], i Andrea Valerio [Akademischer Betreuer] Macciò. "Numerical Models of AGN Jet Feedback / Salvatore Cielo ; Betreuer: Andrea Valerio Macciò". Heidelberg : Universitätsbibliothek Heidelberg, 2015. http://d-nb.info/1180395263/34.

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Dhalla, Sarah M. "Analysis of Kepler Active Galactic Nuclei Using A Revised Kirk, Rieger, Mastichiadis (1998) Model". FIU Digital Commons, 2014. http://digitalcommons.fiu.edu/etd/1521.

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Active Galactic Nuclei (AGN) are cores of distant protogalaxies, with a supermassive blackhole at the center surrounded by an accretion disk, and bipolar jets. Blazars, a subset of AGN, have their jets aligned with our line of sight. Emission from blazars is highly variable on all timescales and frequencies. Microvariability refers to rapid continuum variations that arise within the jet. Bhatta et al. (2013) suggest a modified Kirk, Rieger, \& Mastichiadis (1998) model (KRM) to explain microvariability. The KRM model assumes that when shock waves passes though the jet, each turbulent cell encountered produces a pulse of emission characterized by cell size, local density enhancement, and magnetic field strength. NASA's \kepler\ has monitored optical emission from four AGN. We use the modified KRM model to analyze micro-variations in these \kepler\ data. The distribution of cell sizes computed from these data is consistent with the distribution expected from a turbulent plasma.

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Su, Meng. "Discovery of Giant Gamma-ray Bubbles in the Milky Way". Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10429.

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Based on data from the Fermi Gamma-ray Space Telescope, we have discovered two gigantic gamma-ray emitting bubble structures in our Milky Way (known as the Fermi bubbles), extending \(\sim 50\) degrees above and below the Galactic center with a width of \(\sim 40\) degrees in longitude. The gamma-ray emission associated with these bubbles has a significantly harder spectrum \((dN/dE \sim E^{-2})\) than the inverse Compton emission from known cosmic ray electrons in the Galactic disk, or the gamma-rays produced by decay of pions from proton-ISM collisions. There is no significant difference in the spectrum or gamma-ray luminosity between the north and south bubbles. The bubbles are spatially correlated with the hard-spectrum microwave excess known as the WMAP haze; we also found features in the ROSAT soft X-ray maps at \(1.5 - 2 keV\) which line up with the edges of the bubbles. The Fermi bubbles are most likely created by some large episode of energy injection in the Galactic center, such as past accretion events onto the central massive black hole, or a nuclear starburst in the last \(\sim 10 Myr\). Study of the origin and evolution of the bubbles also has the potential to improve our understanding of recent energetic events in the inner Galaxy and the high-latitude cosmic ray population. Furthermore, we have recently identified a gamma-ray cocoon feature within the southern bubble, with a jet-like feature along the cocoon's axis of symmetry, and another directly opposite the Galactic center in the north. If confirmed, these jets are the first resolved gamma-ray jets ever seen.
Astronomy

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Fransson, Emma. "High energy gamma ray emission and multi-wavelength view of the AGN PKS 0537-441". Thesis, Linnéuniversitetet, Institutionen för fysik och elektroteknik (IFE), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-66894.

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This thesis describes the analysis of Very High Energy (VHE) emission from the Active Galactic Nucleus PKS 0537-441. It also aims to put the results in a wider context by implementing previous work done on this source. The data chosen for the analysis is provided by the Fermi-LAT satellite and covers the energy range between 300 MeV and 300 GeV. Initially a lightcurve of the received ﬂux from the source was generated, containing data from August 2008 to April 2017, with a mean ﬂux of 4∗10−8 photons per second per squared centimeter. The lightcurve contained sections of diﬀerent ﬂux intensities giving periods of special interest, such as a ﬂaring period at August 2008 to August 2011, an enormous ﬂare at April 2010 and a less active period between April 2013 - January 2016 that could be identiﬁed for further investigations. The diﬀerences in observed ﬂux over time was tested and PKS 0537-441 was found to be a signiﬁcantly variable source. Spectral Energy Distribution (SED) analysis was performed over both the entire period as well as over the selected subperiods and ﬁtted against models using the tools provided by the Fermi Science Support Center (FSSC). The models used in the ﬁtting was PowerLaw2, LogParabola and PLSuperExpCutoﬀ and the best ﬁt for the data was obtained from the PLSuperExpCutoﬀ, except for the less intense period where the LogParabola gave the best ﬁt. The result from the SED analysis was integrated with results from previous work done on the source, ranging over multiple wavelengths in order to get a SED which spanned over the entire electromagnetic spectrum. Finally, modeling of this multi wavelength SED was performed in order to obtain parameters for the physical processes involved in the creation of the radiation received from PKS 0537-441.

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Macconi, Duccio. "Radio morphology-accretion mode link in FRII low-excitation radio galaxies". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/17756/.

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Questo lavoro di tesi consiste nello studio sistematico di una popolazione di radiogalassie con comportamenti apparentemente difformi tra banda radio e ottica. Si tratta di AGN radio-loud molto potenti, con emissione radio estesa tipica di radiogalassie. Gli oggetti analizzati in questo lavoro sono classificati in banda radio come FRII, essendo caratterizzate su larga scala dalla presenza di hot-spot e assenza di getti gemelli. Sono invece classificate come LERG (Low Excitation Galaxies) in banda ottica, per via della presenza di alcune righe di emissione che permettono di stabilire il grado di eccitazione delle regioni centrali. Il catalogo da cui queste sono estratte è il 3CR, imponendo un taglio in redshift per z<0.3. Per quanto riguarda i dati ottici, radio e la classificazione di tutte le sorgenti, si è fatto riferimento agli articoli di Buttiglione et al. (2009). L'analisi in banda X è stata svolta utilizzando i dati di archivio pubblici dei telescopi Chandra e XMM-Newton. Una volta estratto lo spettro di emissione, per ogni sorgente si è cercato di ricostruire e studiare il modello fisico che meglio ne descrivesse l'emissione. La raccolta e unione di dati radio, ottici e X per un campione completo di FRII-LERGs costituisce un punto nodale per la comprensione complessiva delle proprietà ambientali, di emissione ed accrescimento delle radio galassie. Lo studio dei meccanismi che portano alla formazione di questa popolazione è infatti, allo stato attuale, lontano da una comprensione completa e univoca. Una volta unite le informazioni provenienti dalle varie bande è stato possibile raggiungere una visione d'insieme e trarre alcune conclusioni. Per alcune proprietà intrinseche questa popolazione di radiogalassie si trova a metà strada tra FRII-HERGs e FRI-LERGs, permettendo di avvalorare l'ipotesi secondo cui la popolazione delle FRII-LERGs stia sperimentando una fase di transizione.

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Bollström, Nadja. "A gamma-ray study of a highly variable blazar : The Fermi-LAT analysis and the modeling of the FSRQ PKS 1510–089". Thesis, Linnéuniversitetet, Institutionen för fysik och elektroteknik (IFE), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-104617.

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The subject of this thesis is the analysis and modeling of the active galactic nucleus PKS 1510-089. The aim is to present a thorough background of active galactic nuclei combined with the analysis and modeling of a specific active galactic nucleus. The results will then be linked to previous research and theories about active galactic nuclei. The data used in the analysis were retrieved from the Fermi Gamma-ray Space Telescope. A light curve analysis that extended over 12 years provided knowledge about variability and presented four interesting flaring periods. The four periods underwent a spectral analysis, and the results showed that a log parabolic curvature could best describe all four periods. The last step before the modeling was to create spectral energy distributions for all four periods to retrieve spectral points from wavelengths other than those available from Fermi. Unfortunately, there were only sufficient data for one period. That period was later used in the modeling and resulted in a well-fitted external Compton model, which was compared, with relatively good results, with previous research.

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Meliani, Zakaria. "Modélisation de vents et de jets relativistes". Phd thesis, Université Paris-Diderot - Paris VII, 2004. http://tel.archives-ouvertes.fr/tel-00008067.

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Les vents et les jets sont un des phénomènes les plus répandu et spectaculaire en astrophysique des hautes énergies. En effet, une variété d'objets astrophysiques exhibent des écoulements aussi bien sous forme de vents que de jets fortement collimatés. Ils sont observés dans les étoiles jeunes, les noyaux actifs de galaxies (AGN), les étoiles à neutrons et les étoiles de la séquence principale. Cependant, malgré l'abondance des jets en astrophysique, le problème de la formation et de la collimation de ces écoulements reste ouvert. Différents modèles sont proposés pour résoudre ce problème. La plupart de ces modèles sont développés dans la limite newtonienne. Nous avons, dans cette thèse, élaboré des modèles hydrodynamiques et magnétohydrodynamiques en relativité générale pour analyser les différents mécanismes d'accélération et de collimation des écoulements aussi bien relativistes que classiques. Nous avons étudié les solutions d'écoulements purement hydrodynamique sphérique avec une équation d'état polytropique généralisée. Nous nous sommes intéressés aux effets de changement de l'état de la matière dans les écoulements sur l'accélération thermique, lorsqu'elle subit des grandes variations de température. Nous avons montré qu'avec notre nouvelle équation d'état, les effets de la gravité et thermique sont couplés, permettant une plus grande efficacité de l'accélération du vent. Nous avons aussi montré la nécessité de l'utilisation de ce nouveau polytrope plus cohérent dans le traitement des écoulements relativistes polytropiques. Dans la deuxième partie de la thèse, nous avons développé un modèle d'écoulement axial magnétisé 2.5D. La température élevée du plasma dans la couronne centrale due à la gravité élevée et la proximité de l'axe de rotation nous ont permis de négliger, dans un premier temps, les effets du cylindre de lumière comparativement aux effets thermiques. Dans ce cadre, nous avons montré que les effets relativistes favorisent l'accélération thermique au détriment de la collimation magnétique. Nous avons aussi montré l'importance de l'expansion initiale du jet sur l'efficacité de l'accélération du jet dans la partie basse. D'autre part, nous avons étudié les effets de la rotation relativiste sur la collimation du jet. Nous avons aussi utilisé le modèle pour déduire quelques différences entres les propriétés intrinsèques des jets d'AGN de type FRI et de FRII. Nous avons trouvé que les jets des FRI se caractérisés par une faible vitesse de rotation à la base et qu'asymptotiquement, ils sont confinés par le milieu ambiant. Par contre, les jets des FRII sont caractérisés par une vitesse de rotation à la base plus élevée que celle des jets de FRI, qui reste cependant sub-keplerienne. De plus, les jets des FRII s'auto-collimatent par leur propre champ magnétique. Nous avons développé un troisième modèle de jet dans le cas des rotateurs relativistes. En premier lieu, ce modèle nous a permis de mieux traiter les jets accélérés par le flux de Poynting contrairement au modèle précédent. Nous avons aussi étudié les effets du cylindre de lumière sur la collimation du jet et confirmé qu'il tend à décollimater ce dernier. D'autre part, nous avons trouvé que, dans les solutions caractérisés par un cylindre de lumière proche de la surface d'Alfvén, la rotation relativiste dans ces jets limite l'accélération de ces derniers. En effet, dans les solutions que nous avons étudiées, les vitesses poloïdales obtenues restent faibles, de l'ordre de $0.6c$. Nous avons aussi amorcé un code de simulation numérique d'écoulements relativistes utilisant la bibliothèque LORENE. Dans la thèse nous avons commencé à tester le code dans le cas simple de vents purement hydrodynamiques sphériques.

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Powling, Alexander. "Jet substructure : an analytical approach". Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/jet-substructure-an-analytical-approach(e1e67bdc-ddda-41e6-a263-af9c0836f278).html.

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In the past few years, detailed study of the internal structure of hadronic jets has become an active area of research. In particular, jet substructure information has been used to distinguish signal from QCD initiated jets, which constitute a significant background for many physics searches. Prior to the work undertaken in this thesis, theoretical research on jet substructure was largely Monte Carlo based, with limited analytical input. This work presents an analytical approach to the study of jet substructure techniques in the context of high-p_T heavy resonance searches at the LHC.In this thesis, we compute the mass distribution of QCD initiated jets after application of several jet substructure algorithms using approximate fixed-order perturbative QCD at leading and next-to-leading order. This is sufficient to extract the leading logarithmic structure for each technique, which we compare to exact fixed-order results. Using this analytical insight, we propose modifications to some of these algorithms and use our results to discuss the phenomenological impact of different parameter choices. We also perform analytical calculations and Monte Carlo studies to examine the impact of QCD radiation on jets that arise from boosted Higgs decay after application of several jet substructure algorithms. Understanding the action on signal jets is important when two techniques perform similarly on background jets. An example studied here is the Y-splitter and Y-pruning techniques, which both perform well at rejecting background; however, the former retains signal jets which are subject to significant radiative and non-perturbative corrections. We demonstrate that the combination of Y-splitter with trimming ameliorates the poor signal tagging efficiency of Y-splitter whilst retaining effective background rejection. Consequently, we find that this combination outperforms the other techniques studied here, at high p_T. We use our analytical expressions to perform an approximate optimisation of parameters for each algorithm and compare our results to Monte Carlo simulation. Finally, we undertake an analytical fixed-order and resummed study of the mass distribution for QCD jets for the combination of Y-splitter with trimming. We demonstrate that the trimming has a numerically subleading effect on the Y-splitter distribution for typical parameter choices and discuss why such techniques can prove to be superior when compared to the currently proposed individual methods.

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Książki na temat "AGN Jet"

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Jefferis, David. The jet age. London: F. Watts, 1987.

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Jefferis, David. The jet age. London: F. Watts, 1987.

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Mike, Machat, i Kodera Craig, red. From props to jets: Commercial aviation's transition to the jet age 1952-1962. North Branch, MN: Specialty Press, 2010.

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Kershaw, Tim. Jet pioneers: Gloster and the birth of the jet age. Stroud: Sutton, 2004.

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Bednarek, Janet R. Airports, Cities, and the Jet Age. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-31195-1.

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Johnston, A. M. Tex Johnston: Jet-age test pilot. Washington, D.C: Smithsonian Institution Press, 1991.

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Fighter combat in the jet age. London: HarperCollins, 1997.

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Airlines of the Jet Age: A history. Washington, D.C: Smithsonian Institution Scholarly Press, 2011.

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Wise, Alan R. Jet age flight helmets: Aviation headgear in the modern age. Atglen, PA: Schiffer Pub., 1996.

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Hypersonic thunder: A novel of the jet age. New York: Forge, 2009.

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Części książek na temat "AGN Jet"

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Ferrari, Attilio. "AGN Jet Modeling: Setting the Stage". W Virtual Astrophysical Jets, 15–26. Dordrecht: Springer Netherlands, 2004. http://dx.doi.org/10.1007/978-1-4020-2664-5_2.

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Markoff, S. "From Multiwavelength to Mass Scaling: Accretion and Ejection in Microquasars and AGN". W The Jet Paradigm, 143–72. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-76937-8_6.

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McHardy, I. "X-Ray Variability of AGN and Relationship to Galactic Black Hole Binary Systems". W The Jet Paradigm, 203–32. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-76937-8_8.

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Neumann, M., K. Meisenheimer, H. J. Röser i M. Stickel. "Near IR — Observations of the Jet in M87". W Multi-Wavelength Continuum Emission of AGN, 329. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-010-9537-2_59.

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Röser, H. J., K. Meisenheimer, M. Neumann i R. G. Conway. "Multifrequency Observations of the Jet of 3C 273". W Multi-Wavelength Continuum Emission of AGN, 333–34. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-010-9537-2_63.

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Romanova, M. M., i R. V. E. Lovelace. "Simultaneous Implosive Accretion and Jet Formation in Quasars: Correlation of Optical Outbursts with VLBI Jets". W Multi-Wavelength Continuum Emission of AGN, 490. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-010-9537-2_191.

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Steffen, W., T. P. Krichbaum, A. Witzel, J. A. Zensus i S. J. Qian. "Helical Motion and Non-Adiabatic Expansion in the Jet of 3C345". W Multi-Wavelength Continuum Emission of AGN, 432. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-010-9537-2_142.

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Kovalev, Y. Y. "Directivity Pattern Simulation of the Jet Radio Emission in an AGN Model". W Multi-Wavelength Continuum Emission of AGN, 428. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-010-9537-2_138.

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Kovalev, Y. Y., i G. M. Larionov. "A Jet Model Interpretation of Multi Frequency Flux Observations of Radio Outbursts in the AGN 0235+16". W Multi-Wavelength Continuum Emission of AGN, 397. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-010-9537-2_111.

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Uchida, Y., M. Nakamura, S. Hirose i S. Uemura. "On Magnetodynamic Jet Formation from Accretion Process Of Magnetized GAS in AGN Core". W Numerical Astrophysics, 221–22. Dordrecht: Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-011-4780-4_70.

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Streszczenia konferencji na temat "AGN Jet"

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Kaiser, Christian R. "AGN jet models". W VI Microquasar Workshop: Microquasars and Beyond. Trieste, Italy: Sissa Medialab, 2007. http://dx.doi.org/10.22323/1.033.0028.

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Sauty, C., Z. Meliani, E. Trussoni, K. Tsinganos i N. Vlahakis. "Relativistic Jet Modeling: Application to AGN". W ALBERT EINSTEIN CENTURY INTERNATIONAL CONFERENCE. AIP, 2006. http://dx.doi.org/10.1063/1.2399651.

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Macchetto, F. "HST observations of the jet in M87". W Testing the AGN paradigm diagnostics. AIP, 1992. http://dx.doi.org/10.1063/1.42259.

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Sadun, Alberto C., i Philip Morrison. "Reflections: The optical jet of 3C 273". W Testing the AGN paradigm diagnostics. AIP, 1992. http://dx.doi.org/10.1063/1.42267.

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Kartje, J. F., A. Königl i P. S. Coppi. "High energy spectra from the jet/disk interface". W Testing the AGN paradigm diagnostics. AIP, 1992. http://dx.doi.org/10.1063/1.42208.

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Romero, Gustavo E. "Predictions of Inhomogeneous Jet Models for CTA". W AGN Physics in the CTA Era. Trieste, Italy: Sissa Medialab, 2012. http://dx.doi.org/10.22323/1.141.0008.

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Marlowe, A. T., C. M. Urry i I. M. George. "Time-dependent inhomogeneous jet models for BL Lac objects". W Testing the AGN paradigm diagnostics. AIP, 1992. http://dx.doi.org/10.1063/1.42268.

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Clausen-Brown, Eric, Tuomas Savolainen, Alexander Pushkarev, Yuri Y. Kovalev i Matt L. Lister. "AGN jet physics and apparent opening angles". W 11th European VLBI Network Symposium & Users Meeting. Trieste, Italy: Sissa Medialab, 2016. http://dx.doi.org/10.22323/1.178.0014.

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O'Sullivan, Shane. "Jet Physics and Magnetic Field Geometry in Parsec-Scale AGN Jets". W The 9th European VLBI Network Symposium on The role of VLBI in the Golden Age for Radio Astronomy and EVN Users Meeting. Trieste, Italy: Sissa Medialab, 2009. http://dx.doi.org/10.22323/1.072.0016.

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Barkov, Maxim, Felix Aharonian, Sergei Bogovalov, Valenti Bosch-Ramon, Stanislav Rikhardovich Kelner i Dmitry Khangulyan. "Gamma-ray flares from red giant/jet interactions in AGN". W 25th Texas Symposium on Relativistic Astrophysics. Trieste, Italy: Sissa Medialab, 2011. http://dx.doi.org/10.22323/1.123.0162.

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Raporty organizacyjne na temat "AGN Jet"

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Wibowo, Johannes, i Jamie López-Soto. Field Jet Erosion Tests on Benbrook Dam, Texas. Engineer Research and Development Center (U.S.), grudzień 2021. http://dx.doi.org/10.21079/11681/42545.

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This report summarizes the results of eight field Jet Erosion Tests (JETs) performed on Benbrook Dam, TX. The results from these tests will be used by the U.S. Army Corps of Engineers, Fort Worth District, in assessments of the erosion resistance of the Benbrook Dam with regards to possible overtopping by extreme flooding. The JETs were performed at four different locations, i.e., two locations at the lowest crest elevation and two locations at the mid-slope face of the downstream embankment. Variations in estimated critical hydraulic shear stress and erosion rate values may have been caused by differences in soil composition, i.e., when the material changed from silt/sand to clay. The resulting values of the Erodibility Coefficient, Kd, and Critical Stress, τc, are very useful information in assessing the stability of Benbrook Dam during an overtopping event. Because of the observed natural variability of the materials, combining the erosion parameters presented in this report with the drilling logs and local geology will be imperative for assessing erosion-related failure modes of Benbrook Dam.

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Nowlin, Jacob, Kevin Wallace, Kyle Beurlot, Mark Patterson i Timothy Jacobs. PR-457-21206-R01 CFD Study of Prechamber NOx Production Mechanisms. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), lipiec 2023. http://dx.doi.org/10.55274/r0000027.

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Use of the pre-combustion chamber (PCC) as an ignition source in large-bore natural gas engines has shown promise in reducing emissions. By increasing the ignition energy and surface area via a turbulent jet, these devices can extend the lean operating limit of the engine and reduce oxides of nitrogen (NOx). This study aims to characterize the sensitivity of main chamber NOx formation to changes in the PCC jet. A CFD model of a Cooper-Bessemer GMV two-stroke lean-burn natural gas engine is used for this purpose. The temperature and chemical composition of the PCC jet are varied across several tasks, and the resulting changes in main chamber NO and shy;x emissions are recorded. Three-dimensional plotting tools are used to determine where and when NOx forms in the engine during the cycle. Data on the chemical pathways to NO and NO2 and shy; and shy; formation and destruction is also presented.

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Baker, Ernest L., James Pham i Tan Vuong. An Empirical Shaped Charge Jet Breakup Model. Fort Belvoir, VA: Defense Technical Information Center, lipiec 2014. http://dx.doi.org/10.21236/ada604020.

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Lottes, S. A., i S. L. Chang. Particle-jet interactions in an MHD second stage combustor. Office of Scientific and Technical Information (OSTI), lipiec 1992. http://dx.doi.org/10.2172/10156492.

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Kadija, K., G. Paic, D. Vranic, F. P. Brady, J. E. Draper, J. L. Romero, J. Carroll i in. An experiment on particle and jet production at midrapidity. Office of Scientific and Technical Information (OSTI), wrzesień 1990. http://dx.doi.org/10.2172/6366571.

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J.C. Lin i D. Rockwell. Oscillations of a Turbulent Jet Incident Upon an Edge. Office of Scientific and Technical Information (OSTI), wrzesień 2000. http://dx.doi.org/10.2172/821367.

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BARKHATOV, NIKOLAY, i SERGEY REVUNOV. A software-computational neural network tool for predicting the electromagnetic state of the polar magnetosphere, taking into account the process that simulates its slow loading by the kinetic energy of the solar wind. SIB-Expertise, grudzień 2021. http://dx.doi.org/10.12731/er0519.07122021.

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The auroral activity indices AU, AL, AE, introduced into geophysics at the beginning of the space era, although they have certain drawbacks, are still widely used to monitor geomagnetic activity at high latitudes. The AU index reflects the intensity of the eastern electric jet, while the AL index is determined by the intensity of the western electric jet. There are many regression relationships linking the indices of magnetic activity with a wide range of phenomena observed in the Earth's magnetosphere and atmosphere. These relationships determine the importance of monitoring and predicting geomagnetic activity for research in various areas of solar-terrestrial physics. The most dramatic phenomena in the magnetosphere and high-latitude ionosphere occur during periods of magnetospheric substorms, a sensitive indicator of which is the time variation and value of the AL index. Currently, AL index forecasting is carried out by various methods using both dynamic systems and artificial intelligence. Forecasting is based on the close relationship between the state of the magnetosphere and the parameters of the solar wind and the interplanetary magnetic field (IMF). This application proposes an algorithm for describing the process of substorm formation using an instrument in the form of an Elman-type ANN by reconstructing the AL index using the dynamics of the new integral parameter we introduced. The use of an integral parameter at the input of the ANN makes it possible to simulate the structure and intellectual properties of the biological nervous system, since in this way an additional realization of the memory of the prehistory of the modeled process is provided.

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Lyutikov, M. Polarization and Structure of Relativistic Parsec-Scale AGN Jets. Office of Scientific and Technical Information (OSTI), czerwiec 2004. http://dx.doi.org/10.2172/826966.

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Kuettner, Lindsey A. Use of Atmospheric-Pressure Plasma Jet for Polymer Surface Modification: An Overview. Office of Scientific and Technical Information (OSTI), marzec 2017. http://dx.doi.org/10.2172/1351174.

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RENSSELAER POLYTECHNIC INST TROY NY. An Experimental Study of Plunging Liquid Jet Induced Air Carryunder and Dispersion. Fort Belvoir, VA: Defense Technical Information Center, marzec 1992. http://dx.doi.org/10.21236/ada248315.

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