Observational Constraints On The Influence Of Active Galactic Nuclei On The Evolution Of Galaxies

Author : Christopher Mark Harrison
Publisher : Springer
ISBN 13 : 3319284541
Total Pages : 208 pages
Book Rating : 4.45/5 ( download)

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Download or read book Observational Constraints on the Influence of Active Galactic Nuclei on the Evolution of Galaxies written by Christopher Mark Harrison and published by Springer. This book was released on 2016-01-20 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: This prize-winning Ph.D. thesis by Chris Harrison adopts a multi-faceted approach to address the lack of decisive observational evidence, utilising large observational data sets from several world-leading telescopes. Developing several novel observational techniques, Harrison demonstrated that energetic winds driven by Active Galactic Nuclei (AGN) are found in a large number of galaxies, with properties in agreement with model predictions. One of the key unsolved problems in astrophysics is understanding the influence of AGN, the sites of growing supermassive black holes, on the evolution of galaxies. Leading theoretical models predict that AGN drive energetic winds into galaxies, regulating the formation of stars. However, until now, we have lacked the decisive observational evidence to confirm or refute these key predictions. Careful selection of targets allowed Harrison, to reliably place these detailed observations into the context of the overall galaxy population. However, in disagreement with the model predictions, Harrison showed that AGN have little global effect on star formation in galaxies. Theoretical models are now left with the challenge of explaining these results.

Author : Jonathan Florez
Publisher :
ISBN 13 :
Total Pages : 432 pages
Book Rating : 4.53/5 ( download)

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Download or read book Exploring the Interplay Between Star Formation and Active Galactic Nuclei and the Role of Environment in Galaxy Evolution written by Jonathan Florez and published by . This book was released on 2021 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the central goals of extragalactic astronomy is to understand how galaxies grow their stellar mass and central black holes, the connection between star formation and active galactic nuclei (AGN), and the impact of environment on this growth. In this thesis, I utilize multiwavelength surveys that are both deep and wide, advanced computational codes that model the spectral energy distributions of galaxies with and without AGN, as well as state-of-the-art simulations of galaxy evolution in order to explore how galaxy properties are impacted by their surrounding environment and AGN activity. These studies explore galaxies over a redshift range of 0.015 z 0.023 (lookback time of ~ 0.2 to ~ 0.3 Gyr), and over a redshift range of 0.5 z 3.0 (lookback time of ~ 5 to ~ 12 Gyr). The large-area surveys used here provide some of the largest and most statistically robust samples to-date of rare massive galaxies (with stellar mass M [subscript *] 1011 M☉) and extremely luminous AGN (with X-ray luminosity L [subscript X] 1044 erg s−1) out to z ~ 3, thereby limiting the effects of cosmic variance and Poisson statistics. I analyze the observed stellar masses and star formation rates of galaxies as a function of environment and AGN activity, compare the empirical results to theoretical models of galaxy evolution, and discuss the implications of such comparisons. This work will provide significant guidance and constraints to the future development of theoretical models of galaxy growth. In Chapter 2 (Florez et al. 2021, ApJ, 906, 97) I measure the environmental dependence, where environment is defined by the distance to the third nearest neighbor, of multiple galaxy properties inside the Environmental COntext (ECO) catalog. I focus primarily on void galaxies at redshifts z = 0.015 - 0.023, which I define as the 10% of galaxies having the lowest local density. I compare the properties of void and non-void galaxies: baryonic mass, color, fractional stellar mass growth rate (FSMGR), morphology, and gas-to-stellar-mass ratio. The void galaxies typically have lower baryonic masses than galaxies in denser environments, and they display the properties expected of a lower mass population: they have more late-types, are bluer, have higher FSMGR, and are more gas rich. I also control for baryonic mass and investigate the extent to which void galaxies are different at fixed mass. I find that void galaxies are bluer, more gas-rich, and more star forming at fixed mass than non-void galaxies, which is a possible signature of galaxy assembly bias and other environmental processes. Furthermore, I show that these trends persist even at fixed mass and morphology, and I find that voids host a distinct population of early-types that are bluer and more star-forming than the typical red and quenched early-types. In addition to these empirical observational results, I also present theoretical results from mock catalogs with built-in galaxy assembly bias. I show that a simple matching of galaxy properties to (sub)halo properties, such as mass and age, can recover the observed environmental trends in the local galaxy population. In Chapter 3 (Florez et al. 2020, MNRAS, 497, 3273) I investigate the relation between AGN and star formation activity at 0.5 z 3 by analyzing 898 galaxies with high X-ray luminosity AGN (L [subscript X] 1044 erg s−1) and a large comparison sample of ~ 320,000 galaxies without such AGN. My samples are selected from a large (11.8 deg2) area in Stripe 82 that has multi-wavelength (X-ray to far-IR) data. The enormous comoving volume (~ 0.3 Gpc3) at 0.5

Author : Gene Chun Kwan Leung
Publisher :
ISBN 13 :
Total Pages : 193 pages
Book Rating : 4.97/5 ( download)

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Download or read book Properties and Impact of Active Galactic Nuclei-driven Outflows Through Cosmic Time written by Gene Chun Kwan Leung and published by . This book was released on 2020 with total page 193 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation studies the properties of outflows driven by active galactic nuclei (AGNs) and their impact on the evolution of galaxies. AGNs are predicted by theoretical models of galaxy formation to provide the necessary feedback to produce realistic galaxies. In theoretical models, AGNs provide feedback by driving outflows that remove gas from the host galaxy, thereby quenching star formation in massive galaxies and producing scaling relations between supermassive black holes and galaxies. Despite being indispensable in theory, critical open questions remain for AGN-driven outflows from an observational perspective. This dissertation first presents two studies using data from the MOSDEF survey, a large spectroscopic survey of galaxies when the Universe was about 3.5 billions years old (z~2). The first study focuses on the incidence and physical properties of AGN-driven outflows at z~2. We show that AGN-drive outflows are at least as prevalent at z~2 as they are in the local Universe. They are fast and extend to distances comparable to the size of the host galaxy. Using emission line ratio diagnostics, we find our data consistent with the picture of negative AGN feedback, where AGN-driven outflows suppress star formation, and find no evidence of galaxy-wide positive AGN feedback. The second study focuses on the demographics of galaxies hosting AGN-driven outflows and the relation between outflow properties and the galaxy and AGN population at z~2. We show that AGN-driven outflows are a ubiquitous phenomenon occurring across the galaxy population and in different phases of galaxy evolution, both before and after quenching. By measuring the energetics and correlations of AGN-driven outflows, we find that the outflows are more energetic at z~2 than in the local Universe, where AGNs are more powerful on average. We find that the outflows remove gas at a rate comparable to or faster than gas is being converted into stars. This shows that AGN-driven outflows at z~2 are capable of regulating star formation in the host galaxy. The third study in this dissertation presents integral field spectroscopy of a nearby ultraluminous infrared galaxy (ULIRG) and AGN Mrk 273. The study focuses on the extended ionized gas on scales of ~20 kpc. We detect for the first time highly ionized gas in one of the extended nebula surrounding the galaxy. From this, we show that shocks contribute significantly to the ionization of the gas in the extended nebulae, mixed with AGN photoionization. Our data is compatible with theoretical models in which AGNs drive a multiphase outflow, and slower-moving extended cold gas filaments form out of a more spatially confined but faster warm outflow. Our data suggests that AGNs play an important role in ejecting gas in the ULIRG phase of galaxy evolution.

Author : Paola Marziani
Publisher : Frontiers Media SA
ISBN 13 : 2889456048
Total Pages : 447 pages
Book Rating : 4.48/5 ( download)

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Download or read book Quasars at All Cosmic Epochs written by Paola Marziani and published by Frontiers Media SA. This book was released on 2018-10-05 with total page 447 pages. Available in PDF, EPUB and Kindle. Book excerpt: The last 50 years have seen a tremendous progress in the research on quasars. From a time when quasars were unforeseen oddities, we have come to a view that considers quasars as active galactic nuclei, with nuclear activity a coming-of-age experienced by most or all galaxies in their evolution. We have passed from a few tens of known quasars of the early 1970s to the 500,000 listed in the catalogue of the Data Release 14 of the Sloan Digital Sky Survey. Not surprisingly, accretion processes on the central black holes in the nuclei of galaxies — the key concept in our understanding of quasars and active nuclei in general — have gained an outstanding status in present-day astrophysics. Accretion produces a rich spectrum of phenomena in all bands of the electromagnetic spectrum. The power output of highly-accreting quasars has impressive effects on their host galaxies. All the improvement in telescope light gathering and in computing power notwithstanding, we still miss a clear connection between observational properties and theory for quasars, as provided, for example, by the H-R diagram for stars. We do not yet have a complete self-consistent view of nuclear activity with predictive power, as we do for main-sequence stellar sources. At the same time quasars offer many “windows open onto the unknown". On small scales, quasar properties depend on phenomena very close to the black hole event horizon. On large scales, quasars may effect evolution of host galaxies and their circum-galactic environments. Quasars’ potential to map the matter density of the Universe and help reconstruct the Universe’s spacetime geometry is still largely unexploited. The times are ripe for a critical assessment of our present knowledge of quasars as accreting black holes and of their evolution across the cosmic time. The foremost aim of this research topic is to review and contextualize the main observational scenarios following an empirical approach, to present and discuss the accretion scenario, and then to analyze how a closer connection between theory and observation can be achieved, identifying those aspects of our understanding that are still on a shaky terrain and are therefore uncertain knowledge. This research topic covers topics ranging from the nearest environment of the black hole, to the environment of the host galaxies of active nuclei, and to the quasars as markers of the large scale structure and of the geometry of spacetime of the Universe. The spatial domains encompass the accretion disk, the emission and absorption regions, circum-nuclear starbursts, the host galaxy and its interaction with other galaxies. Systematic attention is devoted to some key problems that remain outstanding and are clearly not yet solved: the existence of two quasar classes, radio quiet and radio loud, and in general, the systematic contextualization of quasar properties the properties of the central black hole, the dynamics of the accretion flow in the inner parsecs and the origin of the accretion matter, the quasars’ small and large scale environment, the feedback processes produced by the black hole into the host galaxy, quasar evolutionary patterns from seed black holes to the present-day Universe, and the use of quasars as cosmological standard candles. The timing is appropriate as we are now witnessing a growing body of results from major surveys in the optical, UV X, near and far IR, and radio spectral domains. Radio instrumentation has been upgraded to linear detector — a change that resembles the introduction of CCDs for optical astronomy — making it possible to study radio-quiet quasars at radio frequencies. Herschel and ALMA are especially suited to study the circum-nuclear star formation processes. The new generation of 3D magnetohydrodynamical models offers the prospective of a full physical modeling of the whole quasar emitting regions. At the same time, on the forefront of optical astronomy, applications of adaptive optics to long-slit spectroscopy is yielding unprecedented results on high redshift quasars. Other measurement techniques like 2D and photometric reverberation mapping are also yielding an unprecedented amount of data thanks to dedicated experiments and instruments. Thanks to the instrumental advances, ever growing computing power as well as the coming of age of statistical and analysis techniques, the smallest spatial scales are being probed at unprecedented resolution for wide samples of quasars. On large scales, feedback processes are going out of the realm of single-object studies and are entering into the domain of issues involving efficiency and prevalence over a broad range of cosmic epochs. The Research Topic "Quasars at all Cosmic Epochs" collects a large fraction of the contributions presented at a meeting held in Padova, sponsored jointly by the National Institute for Astrophysics, the Padova Astronomical Observatory, the Department of Physics and Astronomy of the University of Padova, and the Instito de Astrofísica de Andalucía (IAA) of the Consejo Superiór de Investigación Cientifica (CSIC). The meeting has been part of the events meant to celebrate the 250th anniversary of the foundation of the Padova Observatory.

Author : Jan Scholtz
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.18/5 ( download)

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Download or read book Constraints on the Impact of Active Galactic Nuclei on Star Formation in Galaxies written by Jan Scholtz and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Author : Hagai Netzer
Publisher : Cambridge University Press
ISBN 13 : 1107021510
Total Pages : 369 pages
Book Rating : 4.18/5 ( download)

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Download or read book The Physics and Evolution of Active Galactic Nuclei written by Hagai Netzer and published by Cambridge University Press. This book was released on 2013-09-16 with total page 369 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive introduction to the theory underpinning our study of active galactic nuclei and the ways we observe them.

Author : Alexander Edward Spacek
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.25/5 ( download)

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Download or read book Investigating Galaxy Evolution and Active Galactic Nucleus Feedback with the Sunyaev-Zel'dovich Effect written by Alexander Edward Spacek and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Galaxy formation is a complex process with aspects that are still very uncertain or unknown. A mechanism that has been utilized in simulations to successfully resolve several of these outstanding issues is active galactic nucleus (AGN) feedback. Recent work has shown that a promising method for directly measuring this energy is by looking at small increases in the energy of cosmic microwave background (CMB) photons as they pass through ionized gas, known as the thermal Sunyaev-Zel'dovich (tSZ) effect. In this work, I present stacked CMB measurements of a large number of elliptical galaxies never before measured using this method. I split the galaxies into two redshift groups, "low-z" for z=0.5-1.0 and "high-z" for z=1.0-1.5. I make two independent sets of CMB measurements using data from the South Pole Telescope (SPT) and the Atacama Cosmology Telescope (ACT), respectively, and I use data from the Planck telescope to account for contamination from dust emission. With SPT I find average thermal energies of 7.6(+3.0/−2.3) × 10^60 erg for 937 low-z galaxies, and 6.0(+7.7/−6.3) × 10^60 erg for 240 high-z galaxies. With ACT I find average thermal energies of 5.6(+5.9/−5.6) × 10^60 erg for 227 low-z galaxies, and 7.0(+4.7/−4.4) × 10^60 erg for 529 high-z galaxies. I then attempt to further interpret the physical meaning of my observational results by incorporating two large-scale cosmological hydrodynamical simulations, one with (Horizon-AGN) and one without (Horizon-NoAGN) AGN feedback. I extract simulated tSZ measurements around a population of galaxies equivalent to those used in my observational work, with matching mass distributions, and compare the results. I find that the SPT measurements are consistent with Horizon-AGN, falling within 0.4[sigma] at low-z and 0.5[sigma] at high-z, while the ACT measurements are very different from Horizon-AGN, off by 6.9[sigma] at low-z and 14.6[sigma] at high-z. Additionally, the SPT measurements are loosely inconsistent with Horizon-NoAGN, off by 1.8[sigma] at low-z but within 0.6[sigma] at high-z, while the ACT measurements are loosely consistent with Horizon-NoAGN (at least much more so than with Horizon-AGN), falling within 0.8[sigma] at low-z but off by 1.9[sigma] at high-z.

Author : COMBES
Publisher : Programme: Aas-Iop Astronomy
ISBN 13 : 9780750330336
Total Pages : 120 pages
Book Rating : 4.33/5 ( download)

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Download or read book Active Galactic Nuclei written by COMBES and published by Programme: Aas-Iop Astronomy. This book was released on 2022-03-15 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: Almost all galaxies host in their center a supermassive black hole of mass between a million and tens of billions solar masses. Supermassive black holes grow in symbiosis with their host galaxies across the Hubble time, occasionally accreting surround matter, giving rise to an Active Galactic Nuclei (AGN). This book gives a general review of our current knowledge of AGN, powered by supermassive black holes: how they are fueled by gas (or stars) and what problems are encountered; how can we account for the wide variety of AGN, from Seyfert/Liners to quasars, and for the two types (AGN 1 and 2) either through dust obscuration, and geometrical orientation arguments, or through intrinsic activity difference, qualitative or quantitative. With modern instruments, providing high resolution and sensitivity, like ALMA in radio, or MUSE at the ESO/VLT, it is possible to unveil the interstellar medium and stars in the circumnuclear regions, discover molecular disks and tori, in the sphere of influence of the black holes. While AGN are accreting matter, they are providing so much energy that part of the surrounding gas is expelled and is observed in molecular outflows, identified as the main feedback process of AGN on their host. Key Features:  Reviews our current knowledge of AGN, with case studies and examples of observed AGN in their host galaxies. Discusses the long-standing problem of AGN fueling and feedback, and proposes educated models of the circum-nuclear regions, which are still difficult to resolve. Covers recent advances in the field of AGN research provided by current astronomical instrumentation (e.g., ALMA, VLT). Written by a world-leading expert in the field.

Author : Ekta Arjunkumar Shah
Publisher :
ISBN 13 :
Total Pages : 180 pages
Book Rating : 4.70/5 ( download)

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Download or read book The Effect of Galaxy Interactions on Star Formation and AGN Activity at 0:5 written by Ekta Arjunkumar Shah and published by . This book was released on 2021 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Galaxy interactions and mergers play an important role in the hierarchical formation and evolution of galaxies. Studies in the nearby universe show a higher star formation rate (SFR) and active galactic nuclei (AGN) fraction in interacting and merging galaxies than in their isolated counterparts, indicating that such interactions are important contributors to star formation and black hole growth. A large fraction of massive galaxies is thought to be affected by galaxy mergers at high redshifts because the galaxy merger rate increases with redshift. We use deep observations and cosmological simulations to study the role of galaxy mergers and interactions in enhancing SFR and AGN activity in galaxies at $0.5 z 3.0$, covering the peak of cosmic star formation and AGN activity ($z\sim2$). For the observational study, we use deep CANDELS and COSMOS observations to compile the largest known sample of major spectroscopic galaxy pairs (2381 with $V

Author : Ryan Brennan
Publisher :
ISBN 13 :
Total Pages : 219 pages
Book Rating : 4.97/5 ( download)

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Download or read book Exploring the Effect of Active Galactic Nuclei on Quenching, Morphological Transformation and Gas Flows with Simulations of Galaxy Evolution written by Ryan Brennan and published by . This book was released on 2017 with total page 219 pages. Available in PDF, EPUB and Kindle. Book excerpt: We study the evolution of simulated galaxies in the presence of feedback from active galactic nuclei (AGN). First, we present a study conducted with a semi-analytic model (SAM) of galaxy formation and evolution that includes prescriptions for bulge growth and AGN feedback due to galaxy mergers and disk instabilities. We find that with this physics included, our model is able to qualitatively reproduce a population of galaxies with the correct star-formation and morphological properties when compared with populations of observed galaxies out to z~3. We also examine the characteristic histories of galaxies with different star-formation and morphological properties in our model in order to draw conclusions about the histories of observed galaxies. Next, we examine the structural properties of galaxies (morphology, size, surface density) as a function of distance from the ``star-forming main sequence'' (SFMS), the observed correlation between the star formation rates (SFRs) and stellar masses of star-forming galaxies. We find that, for observed galaxies, as we move from galaxies above the SFMS (higher SFRs) to those below it (lower SFRs), there exists a nearly monotonic trend towards more bulge-dominated morphology, smaller radius, lower SFR density, and higher stellar density. We find qualitatively similar results for our model galaxies, again driven by our prescriptions for bulge growth and AGN feedback. Next, we conduct a study of the effect of AGN feedback on the gas in individual galaxies using a suite of cosmological hydrodynamical simulations. We compare two sets of 24 galaxies with halo masses of 10^12 - 10^13.4 Msun run with two different feedback models: one which includes stellar feedback via UV heating, stellar winds and supernovae, AGN feedback via momentum-driven winds and X-ray heating, and metal heating via photoelectric heating and cosmic X-ray background heating from accreting black holes in background galaxies (MrAGN), and another model which is identical except that it does not include any AGN feedback (NoAGN). We find that our AGN feedback prescription acts both ``ejectively, '' removing gas from galaxies in powerful outflows, and ``preventatively'', suppressing the inflow of gas onto the galaxy. The histories of MrAGN galaxies are gas ejection-dominated, while the histories of NoAGN galaxies are gas recycling-dominated. This difference in gas cycles results in the quenching of star formation in MrAGN galaxies, while their NoAGN counterparts continue to form stars until z=0. Finally, we examine how this change in the baryon cycle affects the metal content of MrAGN galaxies relative to NoAGN galaxies and find that a combination of gas removal from and metal injection into the hot gas halo results in higher average halo metallicities in MrAGN galaxies.