Academic literature on the topic 'Circum-galactic medium'

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Journal articles on the topic "Circum-galactic medium"

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Li, Jiang‐Tao. "An X‐ray view of the hot circum‐galactic medium." Astronomische Nachrichten 341, no. 2 (February 2020): 177–83. http://dx.doi.org/10.1002/asna.202023775.

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Augustin, Ramona, Céline Péroux, Palle Møller, Varsha Kulkarni, Hadi Rahmani, Bruno Milliard, Matthew Pieri, et al. "Characterizing the circum-galactic medium of damped Lyman-α absorbing galaxies." Monthly Notices of the Royal Astronomical Society 478, no. 3 (May 17, 2018): 3120–32. http://dx.doi.org/10.1093/mnras/sty1287.

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Arrigoni Battaia, Fabrizio, Joseph F. Hennawi, Sebastiano Cantalupo, and J. Xavier Prochaska. "THE STACKED LYαEMISSION PROFILE FROM THE CIRCUM-GALACTIC MEDIUM OFz∼ 2 QUASARS." Astrophysical Journal 829, no. 1 (September 13, 2016): 3. http://dx.doi.org/10.3847/0004-637x/829/1/3.

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Hirashita, Hiroyuki, and Ting-Wen Lan. "Shattering as a source of small grains in the circum-galactic medium." Monthly Notices of the Royal Astronomical Society 505, no. 2 (May 17, 2021): 1794–805. http://dx.doi.org/10.1093/mnras/stab1416.

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ABSTRACT Observed reddening in the circum-galactic medium (CGM) indicates a significant abundance of small grains, of which the origin is still to be clarified. We examine a possible path of small-grain production through shattering of pre-existing large grains in the CGM. Possible sites where shattering occurs on a reasonable time-scale are cool clumps with hydrogen number density nH ∼ 0.1 cm−3 and gas temperature Tgas ∼ 104 K, which are shown to exist through observations of Mg ii absorbers. We calculate the evolution of grain size distribution in physical conditions appropriate for cool clumps in the CGM, starting from a large-grain-dominated distribution suggested from theoretical studies. With an appropriate gas turbulence model expected from the physical condition of cold clumps (maximum eddy size and velocity of ∼100 pc and 10 km s−1, respectively), together with the above gas density and temperature and the dust-to-gas mass ratio inferred from observations (0.006), we find that small-grain production occurs on a time-scale (a few × 108 yr) comparable to the lifetime of cool clumps derived in the literature. Thus, the physical conditions of the cool clouds are favourable for small-grain production. We also confirm that the reddening becomes significant on the above time-scale. Therefore, we conclude that small-grain production by shattering is a probable cause for the observed reddening in the CGM. We also mention the effect of grain materials (or their mixtures) on the reddening at different redshifts (1 and 2).
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Zhou, Zi-Hang, Jin-Ping Zhu, and Kai Wang. "High-energy Neutrino Production from AGN Disk Transients Impacted by the Circum-disk Medium." Astrophysical Journal 951, no. 1 (July 1, 2023): 74. http://dx.doi.org/10.3847/1538-4357/acd380.

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Abstract Various supernovae, compact object coalescences, and tidal disruption events are widely believed to occur embedded in active galactic nucleus (AGN) accretion disks and generate detectable electromagnetic signals. We collectively refer to them as AGN disk transients. The inelastic hadronuclear (pp) interactions between shock-accelerated cosmic rays and AGN disk materials shortly after the ejecta shock breaks out of the disk can produce high-energy neutrinos. However, the expected efficiency of neutrino production would decay rapidly by adopting a pure Gaussian density atmosphere profile applicable for stable gas-dominated disks. On the other hand, AGN outflows and disk winds are commonly found around AGN accretion disks. In this paper, we show that the circum-disk medium would further consume the shock kinetic energy to more efficiently produce high-energy neutrinos, especially for ∼ TeV−PeV neutrinos that IceCube detects. Thanks to the existence of the circum-disk medium, we find that the neutrino production will be enhanced significantly and make a much higher contribution to the diffuse neutrino background. Optimistically, ∼20% of the diffuse neutrino background can be contributed by AGN disk transients.
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Hani, Maan H., Martin Sparre, Sara L. Ellison, Paul Torrey, and Mark Vogelsberger. "Galaxy mergers moulding the circum-galactic medium – I. The impact of a major merger." Monthly Notices of the Royal Astronomical Society 475, no. 1 (December 20, 2017): 1160–76. http://dx.doi.org/10.1093/mnras/stx3252.

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Olsen, Karen, Andrea Pallottini, Aida Wofford, Marios Chatzikos, Mitchell Revalski, Francisco Guzmán, Gergö Popping, et al. "Challenges and Techniques for Simulating Line Emission." Galaxies 6, no. 4 (September 20, 2018): 100. http://dx.doi.org/10.3390/galaxies6040100.

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Modeling emission lines from the millimeter to the UV and producing synthetic spectra is crucial for a good understanding of observations, yet it is an art filled with hazards. This is the proceedings of “Walking the Line”, a 3-day conference held in 2018 that brought together scientists working on different aspects of emission line simulations, in order to share knowledge and discuss the methodology. Emission lines across the spectrum from the millimeter to the UV were discussed, with most of the focus on the interstellar medium, but also some topics on the circumgalactic medium. The most important quality of a useful model is a good synergy with observations and experiments. Challenges in simulating line emission are identified, some of which are already being worked upon, and others that must be addressed in the future for models to agree with observations. Recent advances in several areas aiming at achieving that synergy are summarized here, from micro-physical to galactic and circum-galactic scale.
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Wendt, Martin, Nicolas F. Bouché, Johannes Zabl, Ilane Schroetter, and Sowgat Muzahid. "MusE GAs FLOw and Wind V. The dust/metallicity-anisotropy of the circum-galactic medium." Monthly Notices of the Royal Astronomical Society 502, no. 3 (January 11, 2021): 3733–45. http://dx.doi.org/10.1093/mnras/stab049.

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ABSTRACT We investigate whether the dust content of the circum-galactic medium (CGM) depends on the location of the quasar sightline with respect to the galaxy major-axis using 13 galaxy-Mg ii absorber pairs (9–81 kpc distance) from the MusE GAs FLOw and Wind (MEGAFLOW) survey at 0.4 < z < 1.4. The dust content of the CGM is obtained from [Zn/Fe] using ultraviolet and visual echelle spectrograph data. When a direct measurement of [Zn/Fe] is unavailable, we estimate the dust depletion from a method that consists in solving for the depletion from multiple singly ionized ions (e.g. Mn ii, Cr ii, and Zn ii) since each ion depletes on dust grains at different rates. We find a positive correlation between the azimuthal angle and [Zn/Fe] with a Pearson’s r = 0.70 ± 0.14. The sightlines along the major axis show [Zn/Fe] < 0.5, whereas the [Zn/Fe] is > 0.8 along the minor axis. These results suggest that the CGM along the minor axis is on average more metal enriched (by ≈ 1 dex) than the gas located along the major axis of galaxies provided that dust depletion is a proxy for metallicity. This anisotropic distribution is consistent with recent results on outflow and accretion in hydro-dynamical simulations.
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Sravan, Niharika, Claude-André Faucher-Giguère, Freeke van de Voort, Dušan Kereš, Alexander L. Muratov, Philip F. Hopkins, Robert Feldmann, Eliot Quataert, and Norman Murray. "Strongly time-variable ultraviolet metal-line emission from the circum-galactic medium of high-redshift galaxies." Monthly Notices of the Royal Astronomical Society 463, no. 1 (August 8, 2016): 120–33. http://dx.doi.org/10.1093/mnras/stw1962.

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Momose, Rieko, Tomotsugu Goto, Yousuke Utsumi, Tetsuya Hashimoto, Chia-Ying Chiang, Seong-Jin Kim, Nobunari Kashikawa, Kazuhiro Shimasaku, and Satoshi Miyazaki. "Possible evolution of the circum-galactic medium around QSOs with QSO age and cosmic time revealed by Ly α haloes." Monthly Notices of the Royal Astronomical Society 488, no. 1 (June 25, 2019): 120–34. http://dx.doi.org/10.1093/mnras/stz1707.

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ABSTRACT We first present new Subaru narrow-band observations of the Ly α halo around the quasi-stellar object (QSO) CFHQ J232908−030158 at z = 6.42, which appears the most luminous and extended halo at z > 5 (LLy α = 9.8 × 1043 erg s−1 within 37 pkpc diameter). Then, combining these measurements with available data in the literature, we find two different evolutions of QSOs’ Ly α haloes. First is a possible short-term evolution with QSO age seen in four z > 6 QSOs. We find the anticorrelation between the Ly α halo scales with QSOs’ infrared (IR) luminosity, with J2329−0301’s halo being the brightest and largest. It indicates that ionizing photons escape more easily out to circum-galactic regions when host galaxies are less dusty. We also find a positive correlation between IR luminosity and black hole mass (MBH). Given MBH as an indicator of QSO age, we propose a hypothesis that a large Ly α halo mainly exists around QSOs in the young phase of their activity due to a small amount of dust. The second is an evolution with cosmic time seen over z ∼ 2–5. We find the increase of surface brightness towards lower redshift with a similar growth rate to that of dark matter haloes (DHs) that evolve to MDH = 1012–1013 M⊙ at z = 2. The extent of Ly α haloes is also found to increase at a rate scaling with the virial radius of growing DHs, $r_\text{vir} \propto M_\text{DH}^{1/3}(1+z)^{-1}$. These increases are consistent with a scenario that the circum-galactic medium around QSOs evolves in mass and size keeping pace with hosting DHs.
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Dissertations / Theses on the topic "Circum-galactic medium"

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Augustin, Ramona. "Characterising the circum-galactic medium : observations in absorption and simulations of emission." Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0254.

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Comprendre les processus de flux de gaz entrant et sortant des galaxies est crucial pour les études de l’évolution des galaxies. Cependant, l’observation du médium circum-galactique (CGM) faible et diffus, où se déroulent ces processus, reste difficile. Dans ce travail, j’explore différentes méthodes pour observer, simuler et caractériser le gaz autour des galaxies dans le CGM. J'ai identifié et caractérisé des homologues de galaxie aux systèmes lorentziens (DLA) à z équivalent 1 en utilisant des observations au télescope spatial de Hubble (HS) hautement résolues spatialement. Je détermine leurs masses stellaires et constate que les galaxies sont généralement moins massives que la population moyenne des galaxies, mais suivent les tendances prédites en termes de taux de formation d'étoiles et de métallicité. La haute résolution spatiale des données optiques HST permet également de mieux regarder la morphologie de ces galaxies et de révéler des structures complexes et inattendues. Pour cartographier le CGM nous avons besoin d’observations en émission. Pour améliorer les stratégies d’observation du CGM en émission, j’ai calculé des prédictions à partir de simulations de zoom cosmologique dédiées, post-traitées avec un modèle d'émission du code CLOUDY. Cette combinaison permet de créer des cubes de données de type galaxie halo de type IFU simulés qui sont ensuite utilisés comme entrées dans les modèles d’instruments afin de préparer les observations CGM avec FIREBall-2 (spectrographe UV sur ballon) et HARMONI (IFU proche infrarouge sur l’ELT). Je trouve que FIREBall-2 est capable de détecter Ly alpha et que HARMONI est compétitif pour les études CGM
Understanding the processes of gas flows in and out of galaxies is crucial in galaxy evolution studies. Yet, observations of the faint and diffuse Circum-Galactic Medium (CGM), where these processes take place, remain challenging. In this work, I explore different methods to observe, simulate and characterise the gas around galaxies in the CGM. I identified and characterised galaxy counterparts to Damped Lyman-alpha Absorbers (DLAs) at z equivalent 1 using highly spatially resolved Hubble Space Telescope (HST) observations. I determine their stellar masses and find that the galaxies are generally less massive than the average galaxy population, but follow the predicted trends in terms of star formation rate and metallicity. The high spatial resolution of the optical HST data also allows for a closer look at the morphology at those galaxies and reveals complex, unexpected structures. While absorption lets us investigate very faint gas, it is usually limited to a single line of sight and we need observations in emission to map the CGM and gain information on its extent and clumpiness. To improve observing strategies of the CGM in emission, I make predictions from dedicated cosmological zoom-in simulations, post-processed with a CLOUDY emission model. This combination allows to create mock IFU-like galaxy halo data cubes which are next used as input to instrument models in order to prepare CGM observations with FIREBall-2 (UV spectrograph on a balloon) and HARMONI (near-infrared IFU on the ELT). I predict that FIREBall-2 is capable of detecting Ly alpha and find HARMONI to be competitive for CGM studies
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Quiret, Samuel. "Circum galactic medium emission : from modeling to detection by a dedicated UV space mission." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4735/document.

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L’évolution des galaxies est un sujet relativement débattu en astronomie extra-galactique, étant donné que la plupart des mécanismes responsables des propriétés observées dans les galaxies (masse, taux de formation d’étoiles, contenu en métaux, moment angulaire) sont encore peu contraints et certains ne sont probablement même pas encore observés. Ma thèse porte sur une analyse de la région entourant les galaxies, connue sous le nom de Milieu Circum Galactique (MCG). Le MCG est à l’interface entreles galaxies et le Milieu Inter Galactique (MIG) et est considéré comme le lieu de prédilection pour les échanges gazeux et énergétiques entre les galaxies et le MIG, ce qui en fait la clé pour une meilleure compréhension de l’évolution des galaxies et du destin des baryons. Je présenterai dans un premier temps l’analyse d’un échantillon de systèmes à forte absorption issuent de la spectroscopie de quasars en absorption qui tracent les régions denses en hydrogène généralement associées au MCG des galaxies.Dans un deuxième temps, je présenterai ma contribution au développement d’une mission ballon embarquant un spectrographe UV, FIREBall-2, spécialement conçu pour observer l’émission faible et diffuse du MCG des galaxies à décalage vers le rouge inférieur à 1. D’un point de vue technique, je présenterai l’étude du composant optique clé de l’instrument: le réseau. D’un point de vue modélisation, je décrirai une simulation complète des observations, qui servira à la préparation du vol prévu pour l’Automne 2017notamment en ce qui concerne la sélection des cibles, la stratégie observationelle et le traitement des données
The evolution of galaxies is a rather hot topic in extra galactic astronomy, as many of the main mechanisms underlying the observed properties of galaxies (mass, star formation rate, metal content, angular momentum) are still poorly constraints and many of them are probably undiscovered yet. My thesis focuses on an analysis of the region surrounding galaxies, known as the Circum Galactic Medium (CGM). The CGMinterfaces the galaxy with the Inter Galactic Medium (IGM) and is thought to be the most active location for gas and energy exchanges (in and out), which makes it a key ingredient towards a better understanding of galaxy evolution and the fate of all baryons. I will present in a first part, the analysis of a sample of strong absorption features based on quasar absorption spectroscopy, that probe the dense neutral hydrogen usually associated with galaxies’ CGM. In a second part, I will present my contribution to the development of a balloon-borne UV spectrograph, FIREBall-2, specifically designed to observe the faint and diffuse emissions from the CGM of galaxies at redshifts below 1. On the technical side, I will present the characterization of the key optical component ofthe instrument: the grating. On the modeling side, I will focus on an end-to-end pixel simulation of the observations to prepare for the upcoming flight, planned for Autumn 2017, in terms of target selection, observational strategy and data analysis
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Röttgers, Bernhard [Verfasser], and Simon D. M. [Akademischer Betreuer] White. "Simulated absorption lines in the circum-galactic medium / Bernhard Röttgers ; Betreuer: Simon D. M. White." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2017. http://d-nb.info/1137466766/34.

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Falkendal, Theresa Maria. "Constraining star formation rates and AGN feedback in high-z radio galaxies." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS248.

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L’évolution des galaxies reste assez mal comprise. La densité de formation piquant entre 1
The evolution of galaxies is something that is still not well understood. The cosmic star formation rate density peaks between 1 < z < 3. It is therefore important to investigate the high-z Universe and the mechanisms which triggers or quenches star-formation in galaxies. In this thesis I investigate the effects of AGN feedback by studying high-z radio galaxies (HzRGs). For a sample of 25 HzRGs at 1 < z < 5.2, I add new ALMA data and determine the star formation rates (SFR) by multi-wavelength spectral energy distribution fitting. The ALMA data reveals that the mm continuum emission can be complicated, with contributions from several thermal dust emission components and/or synchrotron emission. The new estimated SFRs are 7 times lower than in previous studies. We might therefore be observing the effect of the AGN suppressing the growth of the host galaxy. For one source I explore the possibilities of constraining the gas Physics of the host galaxy and the halo gas by combining MUSE and ALMA data cubes. Quiescent ionized halo gas is detected, which coincide with a molecular gas reservoir detected with ALMA in [C I]. These observations probe the complex multi-phase halo gas and show the power of multi-wavelength observations
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Vijayan, Aditi. "Understanding Multi-Wavelength Signatures of Galactic Outflows Through 3-D Simulations." Thesis, 2020. https://etd.iisc.ac.in/handle/2005/4539.

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Evolution of galaxies is a phenomenon that affects the formation and composition of galaxies, and the intergalactic medium. It is mediated by processes that establish a symbiotic relationship between a galaxy and the surrounding circum-galactic medium (CGM) by enabling the exchange of mass, momentum, energy, and metals between the two. For star-forming galaxies, one side of the exchange is driven by galactic outflows (GOs) emerging from supernovae explosions (SNes). GOs posses a complex, multiphase structure which covers several orders in magnitudes of density and temperature. A complete description of GOs should be able to capture all its characteristics and replicate its multi-wavelength observations. Due to its complicated phase structure, analytical modelling of GOs is limited in scope and therefore, significant effort in this field is devoted to the simulations of these outflows. In this thesis, we use idealised simulations of isolated galaxies to understand GOs from star-forming Milky Way (MW) -type galaxies. We consider the evolution of the outflowing gas over several Myr and focus on the properties of the extraplanar gas. We produce synthetic observations which we compare with existing X-ray and radio observations. By conducting simulations with various star formation rates, we connect the properties of the extraplanar gas with the underlying star formation occurring in the disc. We study the different thermal phases and their kinematical and dynamical properties in GOs as they travel through the CGM. To quantify the interactions taking place between the different phases, we analyse simulations of a local patch of the solar neighbourhood.
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