Exploring The Effect Of Active Galactic Nuclei On Quenching Morphological Transformation And Gas Flows With Simulations Of Galaxy Evolution PDF Download

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Exploring the Effect of Active Galactic Nuclei on Quenching, Morphological Transformation and Gas Flows with Simulations of Galaxy Evolution

Exploring the Effect of Active Galactic Nuclei on Quenching, Morphological Transformation and Gas Flows with Simulations of Galaxy Evolution
Author: Ryan Brennan
Publisher:
Total Pages: 219
Release: 2017
Genre: Galaxies
ISBN:
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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.

Exploring the Interplay Between Star Formation and Active Galactic Nuclei and the Role of Environment in Galaxy Evolution

Exploring the Interplay Between Star Formation and Active Galactic Nuclei and the Role of Environment in Galaxy Evolution
Author: Jonathan Florez
Publisher:
Total Pages: 432
Release: 2021
Genre:
ISBN:
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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

Properties and Impact of Active Galactic Nuclei-driven Outflows Through Cosmic Time

Properties and Impact of Active Galactic Nuclei-driven Outflows Through Cosmic Time
Author: Gene Chun Kwan Leung
Publisher:
Total Pages: 193
Release: 2020
Genre:
ISBN:
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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.

The Physical Connection Between Cosmic Gas Flows, Supermassive Black Holes Growth, and Galaxy Evolution

The Physical Connection Between Cosmic Gas Flows, Supermassive Black Holes Growth, and Galaxy Evolution
Author: Natalie Nicole Bran Sanchez
Publisher:
Total Pages: 0
Release: 2022
Genre:
ISBN:
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The circumgalactic medium (CGM) represents a key interface in the processes of galactic evolution. Here, the gas which enters galaxies through mergers and filaments and the gas expelled from a disk through stellar and black hole feedback intersect, maintaining a reservoir that will shape a galaxy throughout its lifetime. However, due to the diffuse and difficult-to- observe nature of this gaseous region, the degree to which galactic processes impact it are still uncertain, making the CGM a natural laboratory for testing the impact of different feedback models. The CGM of Milky Way-mass galaxies are the best targets for these analyses as these galaxies lie at the turnover mass during which galaxies switch from being dominated by stellar processes and become dominated by supermassive black hole (SMBH) or active galactic nucleus (AGN) processes.My focus of my thesis work is in exploring the impact of supermassive black hole (SMBH) feedback on the evolution of Milky Way-mass (MW-mass) galaxies in hydrodynamic sim- ulations. We use simulations from the N-body+Smoothed particle hydrodynamics code, ChaNGa, and include a 25 Mpc cosmological volume, Romulus25, and a suite of "genet- ically modified" (GM) galaxies. These GM galaxies originate from nearly identical initial conditions resulting in minor modifications to their accretion histories that maintain the large scale structure and final halo mass of the original simulation. We find that (1) the SMBH propagates metals from the disk out into CGM, (2) the mass of metals retained by the galaxy depends on its deviation from the M-sigma relation, and (3) black hole accretion histories can be influenced by larger scale galaxy accretion physics, which work in tandem to quench star formation.

Numerical Models of Galaxy Evolution

Numerical Models of Galaxy Evolution
Author: Jackson Eugene DeBuhr
Publisher:
Total Pages: 322
Release: 2012
Genre:
ISBN:
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This thesis explores two topics in contemporary galaxy evolution using numerical models and N-body simulation: feedback in active galactic nuclei and the heating of stellar disks. Two numerical models of feedback from active galactic nuclei are developed and applied to the case of a major merger between two disk galaxies. Accretion into central black holes is modeled via a subgrid prescription based on angular momentum transport on unresolved scales. Feedback from black holes is modeled in two ways, both of which deposit a momentum [tau] L / c into the surroundings, where L is the luminosity of radiation produced by the galactic nucleus. In the first model, the momentum is divided equally among the nearby gas particles to model processes like the absorption of ultraviolet light by dust grains. The second model deposits the same amount of momentum into the surroundings, but it does so by launching a wind with a fixed speed, which only has a direct effect on a small fraction of the gas in the black hole's vicinity. Both models successfully regulate the growth of the black hole, reproducing, for example, the MBH-[sigma] relationship, albeit for large amounts of momentum deposition (large [tau]). This regulation is largely independent of the fueling model employed, and thus is d̀emand limited' black hole growth, rather than a s̀upply limited' mode. However, only the model that implements an active galactic nucleus wind explicitly has an effect on large scales, quenching star formation in the host galaxy, and driving a massive galaxy-scale outflow. In a separate set of calculations, a method for including a stellar disk in cosmological zoom-in simulation is presented and applied to a set of realistic dark matter halos taken from the Aquarius suite of simulations. The halos are adiabatically adjusted from z = 1.3 to z = 1.0 by a rigid disk potential, at which point the rigid potential is replaced with a live stellar disk of particles. The halos respond to the disks, in every orientation simulated, by contracting in their central regions and by becoming oblate instead of prolate. The resulting disks, with few exceptions, form large bars which contain a fair fraction of the mass of the disk. These bars buckle and dominate the dynamics of the disk, increasing not only the scale height of the disk, but also the vertical velocity dispersion. During the simulations, the disks tumble coherently with their host halo, but can leave the outermost edges of the disk behind, creating streams that are far out of the plane of the disk. Some first steps are taken to relate the evolution of the disk to the substructure in the halo, but the situation is complicated by the massive bar.

Investigating Galaxy Evolution and Active Galactic Nucleus Feedback with the Sunyaev-Zel'dovich Effect

Investigating Galaxy Evolution and Active Galactic Nucleus Feedback with the Sunyaev-Zel'dovich Effect
Author: Alexander Edward Spacek
Publisher:
Total Pages: 0
Release: 2017
Genre: Galaxies
ISBN:
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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.

Probing Galaxy Evolution Through Numerical Simulations

Probing Galaxy Evolution Through Numerical Simulations
Author: Maan H. Hani
Publisher:
Total Pages:
Release: 2020
Genre:
ISBN:
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Large observational surveys have compiled substantial galaxy samples with an array of different properties across cosmic time. While we have a broad understanding of how galaxies grow and build their observable properties, the details of galaxy growth and evolution pose a fundamental challenge to galaxy evolution theories. Nonetheless, galaxy evolution is ultimately regulated by the properties of the gas reservoir. In this thesis I use numerical simulations to answer key questions related to the galactic gas reservoir, and galaxy mergers: a major transformational process. In Chapter 2 I present an analysis of 28 simulated L* galaxies to understand the physical processes that shape the massive gas reservoir surrounding galaxies (i.e. the circum-galactic medium; CGM). I show that (1) the gas and metal content of the CGM is driven by galaxy growth and the strength/presence of feedback processes, and (2) the ionisation and internal structures of the CGM are shaped by galactic outflows, and active galactic nucleus luminosity. Albeit dependent on internal galactic properties and the physical processes that shape them, the CGM remains greatly diverse, thus posing a challenge for observational surveys. As a follow-up to my study of normal L* galaxy gas halos, in Chapter 3 I present a theoretical study of the effect of galaxy mergers on the CGM. I demonstrate that galaxy mergers can leave a strong imprint on the CGM's gas and metal content, metallicity, and size. The merger can increase (1) the CGM's metallicity by 0.2-0.3 dex within 0.5 Gyr post-merge, and (2) the metal covering fractions by factors of 2-3. In spite of the increase in the CGM's metal content, the hard ionising field during the merger can drive a decline in the covering fractions of commonly observed ions. In Chapter 4 I shift focus to star formation, particularly the effects of galaxy mergers on star formation. While the effects of galaxy mergers have been proven observationally, theoretical predictions are limited to small binary merger suites and cosmological zoom-in studies. I present a statistical study of 27,691 post-merger galaxies from IllustrisTNG to quantify the effect of galaxy mergers on galactic star formation. I report a dependence in the merger-induced star formation rate (SFR) on mass ratio, stellar mass, gas fraction, and galaxy SFR. I also track the evolution of the effects of galaxy mergers demonstrating their decay over ~500 Myr. In Chapter 6, I leverage galactic scaling relations to extend my work on the effects of galaxy mergers to resolved scales. However, before using the simulated resolved scaling relations, I first examine their existence and robustness. In Chapter 5, I demonstrate the emergence of the kpc-scale star forming main sequence (rSFMS) in the FIRE-2 simulations. Nonetheless, the slope of the rSFMS is dependent on the (1) star formation tracer's timescale, and (2) observed resolution, which I propose is caused by the clumpiness of star formation. I develop a toy model that quantitatively captures the effects of clumpy star formation. I then illustrate how the model can be used to characterise the mass of star-forming clumps. Having demonstrated the existence and robustness of known scaling relations in numerical simulations, I explore the effects of galaxy mergers on resolved scales in Chapter 6. I generate synthetic observations for 1,927 post-mergers in IllustrisTNG and examine the radially-dependent merger-driven SFR enhancement, and metallicity suppression in post-mergers. Galaxy mergers preferentially boost star formation in the centres and suppress metallicities globally. The effects of the merger depends on galaxy properties such as stellar mass, SFR, mass ratio, and gas fraction.

Structure and Evolution of Active Galactic Nuclei

Structure and Evolution of Active Galactic Nuclei
Author: G. Giuricin
Publisher: Springer
Total Pages: 808
Release: 1986-01-31
Genre: Science
ISBN:
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Proceedings of International Meeting held in Trieste, Italy, April 10-13, 1985

The Physics and Evolution of Active Galactic Nuclei

The Physics and Evolution of Active Galactic Nuclei
Author: Hagai Netzer
Publisher: Cambridge University Press
Total Pages: 369
Release: 2013-09-16
Genre: Science
ISBN: 1107021510
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A comprehensive introduction to the theory underpinning our study of active galactic nuclei and the ways we observe them.

Quenching Star Formation in Low-mass Galaxies Hosting Active Galactic Nuclei

Quenching Star Formation in Low-mass Galaxies Hosting Active Galactic Nuclei
Author: Catherine Witherspoon (Ph.D.)
Publisher:
Total Pages: 0
Release: 2023
Genre:
ISBN:
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This thesis aims to better understand the role active galactic nuclei (AGN) play in shutting down - quenching - star formation in low-mass galaxies. Using the Sloan Digital Sky Survey IV (SDSS-IV) Mapping Nearby Galaxies at Apache Point Observatory (MaNGA), we select a sample of low-mass galaxies with signatures of accretion onto a massive black hole. In order to disentangle the effects of environmental quenching mechanisms and AGN feedback, we investigate the group richness for active and inactive low-mass galaxies and their quiescent and star-forming sub-samples. We find that the quiescent low-mass galaxies hosting AGN prefer isolation or small groups suggesting that environmental process are not the primary quenching mechanisms. We also observed HI and CO gas in low-mass galaxies with AGN, and we find that the active galaxies are gas-depleted in both their atomic and molecular gas reservoirs, which indicates that these galaxies are in the process of quenching. Finally, we show that the mass-weighted stellar ages of low-mass galaxies hosting AGN have significantly younger stellar populations in their centers than their outskirts while the inactive galaxies have relatively flat radial stellar age gradients. These radial age gradients may be dependent on the strength of the AGN such that strong-AGN efficiently clear out the gas in the galaxy centers and prevent further star formation. Because weak-AGN cannot completely remove the centrally-located gas, the remaining gas in the galaxy is used for fueling the AGN and forming the last stars before the galaxy quenches. The combination of these works suggest that AGN could influence the star formation in low-mass galaxies and potentially be a dominant quenching mechanism.