The inefficiency of star formation in massive elliptical galaxies is widely believed to be caused by the interactions of an active galactic nucleus (AGN) with the surrounding gas. Achieving a sufficiently rapid reddening of moderately massive galaxies without expelling too many baryons has however proven difficult for hydrodynamical simulations of galaxy formation, prompting us to explore a new model for the accretion and feedback effects of supermassive black holes. For high accretion rates relative to the Eddington limit, we assume that a fraction of the accreted rest mass energy heats the surrounding gas thermally, similar to the `quasar mode' in previous work. For low accretion rates, we invoke a new, pure kinetic feedback model which imparts momentum into the surrounding gas in a stochastic manner. These two modes of feedback are motivated both by theoretical conjectures for the existence of different types of accretion flows as well as recent observational evidence for the importance of kinetic AGN winds in quenching galaxies. We find that a large fraction of the injected kinetic energy in this mode thermalises via shocks in the surrounding gas, thereby providing a distributed heating channel. In cosmological simulations, the resulting model produces red, non star-forming massive elliptical galaxies, and achieves realistic gas fractions, black hole growth histories and thermodynamic profiles in large haloes.
Nuclear star clusters (NCs) are found to exist in the centres of many galaxies and appear to follow scaling relations similar to those of super-massive black holes. Previous analytical work has suggested that such relations are a consequence of feedback regulated growth. We explore this idea using high resolution hydrodynamical simulations, focusing on the validity of the simplifying assumptions made in analytical models. In particular, we investigate feedback emanating from multiple stellar sources rather than from a single source, as is usually assumed, and show that collisions betweens shel…
We introduce the Stars and MUltiphase Gas in GaLaxiEs -- SMUGGLE model, an explicit and comprehensive stellar feedback model for the moving-mesh code arepo. This novel sub-resolution model resolves the multiphase gas structure of the interstellar medium and self-consistently generates gaseous outflows. The model implements crucial aspects of stellar feedback including photoionization, radiation pressure, energy and momentum injection from stellar winds and from supernovae. We explore this model in high-resolution isolated simulations of Milky Way-like disc galaxies. Stellar feedback regulates …
Radiative feedback is an important consequence of cluster formation in Giant Molecular Clouds (GMCs) in which newly formed clusters heat and ionize their surrounding gas. The process of cluster formation, and the role of radiative feedback, has not been fully explored in different GMC environments. We present a suite of simulations which explore how the initial gravitational boundedness, and radiative feedback, affect cluster formation. We model the early evolution ($<$ 5 Myr) of turbulent, 10$^6$ M$_{\odot}$ clouds with virial parameters ranging from 0.5 to 5. To model cluster formation, we u…
We investigate the formation of a galaxy reaching a virial mass of $~ 10^8$ solar mass at $z=10$ by carrying out a zoomed radiation-hydrodynamical cosmological simulation. This simulation traces Population~III (Pop~III) star formation, characterized by a modestly top-heavy initial mass function (IMF), and considers stellar feedback such as photoionization heating from Pop III and Population~II (Pop~II) stars, mechanical and chemical feedback from supernovae (SNe), and X-ray feedback from accreting black holes (BHs) and high-mass X-ray binaries (HMXBs). We self-consistently impose a transition …
In order to better understand the relationship between feedback and galactic chemical evolution, we have developed a new model for stellar feedback at grid resolutions of only a few parsecs in global disk simulations, using the adaptive mesh refinement hydrodynamics code Enzo. For the first time in galaxy scale simulations, we simulate detailed stellar feedback from individual stars including asymptotic giant branch winds, photoelectric heating, Lyman-Werner radiation, ionizing radiation tracked through an adaptive ray-tracing radiative transfer method, and core collapse and Type Ia supernovae…
Observational and theoretical arguments increasingly suggest that the initial mass function (IMF) of stars may depend systematically on environment, yet most galaxy formation models to date assume a universal IMF. Here we investigate simulations of the formation of Milky Way analogues run with an empirically derived metallicity-dependent IMF and the moving-mesh code AREPO in order to characterize the associated uncertainties. In particular, we compare a constant Chabrier and a varying metallicity-dependent IMF in cosmological, magneto-hydrodynamical zoom-in simulations of Milky Way-sized halos…
Radiative feedback is among the most important consequences of clustered star formation inside molecular clouds. At the onset of star formation, radiation from massive stars heats the surrounding gas, which suppresses the formation of many low-mass stars. When simulating pre-main-sequence stars, their stellar properties must be defined by a prestellar model. Different approaches to prestellar modeling may yield quantitatively different results. In this paper, we compare two existing prestellar models under identical initial conditions to gauge whether the choice of model has any significant ef…
The process of radiative feedback in Giant Molecular Clouds (GMCs) is an important mechanism for limiting star cluster formation through the heating and ionization of the surrounding gas. We explore the degree to which radiative feedback affects early ($\lesssim$5 Myr) cluster formation in GMCs having masses that range from 10$^{4-6}$ M$_{\odot}$ using the FLASH code. The inclusion of radiative feedback lowers the efficiency of cluster formation by 20-50\% relative to hydrodynamic simulations. Two models in particular --- 5$\times$10$^4$ and 10$^5$ M$_{\odot}$ --- show the largest suppression …
Feedback from supernovae is essential to understanding the self-regulation of star formation in galaxies. However, the efficacy of the process in a cosmological context remains unclear due to excessive radiative losses during the shock propagation. To better understand the impact of SN explosions on the evolution of galaxies, we perform a suite of high-resolution (12 pc), zoom-in cosmological simulations of a Milky Way-like galaxy at z=3 with adaptive mesh refinement. We find that SN explosions can efficiently regulate star formation, leading to the stellar mass and metallicity consistent with…
Introducing RAFIKI: Refining AGN Feedback in Kinetic Implementations
School of Earth and Space Exploration, Arizona State University（亚利桑那州立大学地球与空间探索学院）；Institute for Astronomy, Royal Observatory, University of Edinburgh（爱丁堡大学皇家天文台天体物理研究所）；Department of Physics and Astronomy, University of the Western Cape（西开普大学物理与天文学系）；Stellenbosch Institute for Advanced Studies（斯特伦博斯高等研究院）；Department of Physics and Astronomy, University of Victoria（维多利亚大学物理与天文学系）；Leverhulme Visiting Professor（莱弗休姆访问教授）；Centre for Space Research, North-West University（西北大学太空研究中心）；National Institute for Theoretical and Computational Sciences (NITheCS)（国家理论与计算科学研究所）
We present self-consistent radiation hydrodynamic simulations of hydrogen reionization performed with Arepo-RT complemented by a state-of-the-art galaxy formation model. We examine how photoheating feedback, due to reionization, shapes the galaxies properties. Our fiducial model completes reionization by $z\approx6$ and matches observations of the Ly$α$ forest, the CMB electron scattering optical depth, the high-redshift UV luminosity function, and stellar mass function. Contrary to previous works, photoheating suppresses star formation rates by more than $50\%$ only in halos less massive than…
Jet--ISM Interactions in Gaseous Disks: Simulating Kinetic Feedback in the Radio Galaxy 3C 326 N
Zhejiang University（浙江大学）；Inter-University Centre for Astronomy and Astrophysics（大学间天文与天体物理中心）；Savitribai Phule Pune University（萨维特里拜·普勒浦那大学）；Université de la Côte d’Azur（蔚蓝海岸大学）；Observatoire de la Côte d’Azur（蔚蓝海岸天文台）；Laboratoire Lagrange（拉格朗日实验室）；The Australian National University（澳大利亚国立大学）；European Southern Observatory（欧洲南方天文台）；Leibniz Institute for Astrophysics（莱布尼茨天体物理研究所）
We describe a new method for adding a prescribed amount of kinetic energy to simulated gas modeled on a cartesian grid by directly altering grid cells' mass and velocity in a distributed fashion. The method is explored in the context of supernova feedback in high-resolution ($\sim 10$ pc) hydrodynamic simulations of galaxy formation. Resolution-dependence is a primary consideration in our application of the method and simulations of isolated explosions (performed at different resolutions) motivate a resolution-dependent scaling for the injected fraction of kinetic energy that we apply in cosmo…
Simulating AGN wind feedback with variable feedback efficiencies in idealised disc galaxies
Institute for Computational Cosmology, Department of Physics, University of Durham（达勒姆大学物理学院宇宙计算研究所）；Department of Astronomy, School of Physics, Peking University（北京大学物理学院天文学系）；Kavli Institute for Astronomy and Astrophysics, Peking University（北京大学卡弗里天文与天体物理研究所）；Leiden Observatory, Leiden University（莱顿大学莱顿天文台）
MACER3D -- an upgrade of MACER2D with enhanced subgrid models and gas physics -- and its application to simulating AGN feedback in a massive elliptical galaxy
本文提出三维流体模拟套件 MACER3D，通过增强亚网格模型和气体物理，研究椭圆星系中 AGN 与超新星联合反馈对恒星形成、金属富集及 X 射线性质的影响，并与二维前身 MACER2D 的结果进行对比。
Cosmological simulations make use of sub-grid recipes for the implementation of galactic winds driven by massive stars because direct injection of supernova energy in thermal form leads to strong radiative losses, rendering the feedback inefficient. We argue that the main cause of the catastrophic cooling is a mismatch between the mass of the gas in which the energy is injected and the mass of the parent stellar population. Because too much mass is heated, the temperatures are too low and the cooling times too short. We use analytic arguments to estimate, as a function of the gas density and t…
Feedback from both supermassive black holes and massive stars plays a fundamental role in the evolution of galaxies and the inter-galactic medium. In this paper we use available data to estimate the total amount of kinetic energy and momentum created per co-moving volume element over the history of the universe from three sources: massive stars and supernovae, radiation pressure and winds driven by supermassive black holes, and radio jets driven by supermassive black holes. Kinetic energy and momentum injection from jets peaks at z ~ 1, while the other two sources peak at z ~ 2. Massive stars …
Recent observations provide evidence that some cool-core clusters (CCCs) host quasars in their brightest cluster galaxies (BCGs). Motivated by these findings we use 3D radiation-hydrodynamic simulations with the code Enzo to explore the joint role of the kinetic and radiative feedback from supermassive black holes (SMBHs) in BCGs. We implement kinetic feedback as sub-relativistic plasma outflows and model radiative feedback using the ray-tracing radiative transfer or thermal energy injection. In our simulations the central SMBH transitions between the radiatively efficient and radiatively inef…
We present a detailed study of AGN feedback in the narrow-line region (NLR) of the Seyfert 1 galaxy NGC 4151. We illustrate the data and techniques needed to determine the mass outflow rate and kinetic luminosity of the outflowing ionized gas as a function of position in the NLR. We find that the mass outflow rate peaks at a value of 3 solar masses per year at a distance of 70 pc from the central supermassive black hole (SMBH), which is about 10 times the outflow rate coming from inside 13 pc, and 230 times the mass accretion rate inferred from the bolometric luminosity of NGC 4151. Thus, most…
Determining the distance of quasar absorption outflows from the central source (R) and their kinetic luminosity are crucial for understanding their contribution to active galactic nucleus (AGN) feedback. Here we summarize the results for a sample of nine luminous quasars that were observed with the Hubble Space Telescope. We find that the outflows in more than half of the objects are powerful enough to be the main agents for AGN feedback, and that most outflows are found at R>100 pc. The sample is representative of the quasar absorption outflow population as a whole and is unbiased towards spe…
Based on two-dimensional high resolution hydrodynamic numerical simulation, we study the mechanical and radiative feedback effects from the central AGN on the cosmological evolution of an isolated elliptical galaxy. Physical processes such as star formation and supernovae are considered. The inner boundary of the simulation domain is carefully chosen so that the fiducial Bondi radius is resolved and the accretion rate of the black hole is determined self-consistently. In analogy to previous works, we assume that the specific angular momentum of the galaxy is low. It is well-known that when the…
We have simulated star formation in prestellar cores, using SPH and initial conditions informed by observations of the cores in Ophiuchus. Because the observations are limited to two spatial dimensions plus radial velocity, we cannot infer initial conditions for the collapse of a particular core. However, with a minimum of assumptions (isotropic turbulence with a power-law spectrum, a thermal mix of compressive and solenoidal modes, a critical Bonnor-Ebert density profile) we can generate initial conditions that match, in a statistical sense, the distributions of mass, projected size and aspec…
We have constructed an analytical model of AGN feedback and studied its implications for elliptical galaxies and galaxy clusters. The results show that momentum injection above a critical value will eject material from low mass elliptical galaxies, and leads to an X-ray luminosity, $L_{\rm X}$, that is $\propto$ $σ^{8-10}$, depending on the AGN fuelling mechanism, where $σ$ is the velocity dispersion of the hot gas. This result agrees well with both observations and semi-analytic models. In more massive ellipticals and clusters, AGN outflows quickly become buoyancy-dominated. This necessarily …
We compare 5 sub-grid models for supernova (SN) feedback in adaptive mesh refinement (AMR) simulations of isolated dwarf and L-star disk galaxies with 20-40 pc resolution. The models are thermal dump, stochastic thermal, 'mechanical' (injecting energy or momentum depending on the resolution), kinetic, and delayed cooling feedback. We focus on the ability of each model to suppress star formation and generate outflows. Our highest-resolution runs marginally resolve the adiabatic phase of the feedback events, which correspond to 40 SN explosions, and the first three models yield nearly identical …
Stellar winds and supernova (SN) explosions of massive stars ("stellar feedback") create bubbles in the interstellar medium (ISM) and insert newly produced heavy elements and kinetic energy into their surroundings, possibly driving turbulence. Most of this energy is thermalized and immediately removed from the ISM by radiative cooling. The rest is available for driving ISM dynamics. In this work we estimate the amount of feedback energy retained as kinetic energy when the bubble walls have decelerated to the sound speed of the ambient medium. We show that the feedback of the most massive star …
We introduce the LYRA project, a new high resolution galaxy formation model built within the framework of the cosmological hydro-dynamical moving mesh code AREPO. The model resolves the multi-phase interstellar medium down to 10 K. It forms individual stars sampled from the initial mass function (IMF), and tracks their lifetimes and death pathways individually. Single supernova (SN) blast waves with variable energy are followed within the hydrodynamic calculation to interact with the surrounding interstellar medium (ISM). In this paper, we present the methods and apply the model to a $10^{10} …
We present radiation hydrodynamic simulations of collapsing protostellar cores with initial masses of 30, 100, and 200 M$_{\odot}$. We follow their gravitational collapse and the formation of a massive protostar and protostellar accretion disk. We employ a new hybrid radiative feedback method blending raytracing techniques with flux-limited diffusion for a more accurate treatment of the temperature and radiative force. In each case, the disk that forms becomes Toomre-unstable and develops spiral arms. This occurs between 0.35 and 0.55 freefall times and is accompanied by an increase in the acc…
The massive galaxy cluster "El Gordo" (ACT-CL J0102--4915) is a rare merging system with a high collision speed suggested by multi-wavelength observations and the theoretical modeling. Zhang et al. (2015) propose two types of mergers, a nearly head-on merger and an off-axis merger with a large impact parameter, to reproduce most of the observational features of the cluster, by using numerical simulations. The different merger configurations of the two models result in different gas motion in the simulated clusters. In this paper, we predict the kinetic Sunyaev-Zel'dovich (kSZ) effect, the rela…
We implement novel numerical models of AGN feedback in the SPH code GADGET-3, where the energy from a supermassive black hole (BH) is coupled to the surrounding gas in the kinetic form. Gas particles lying inside a bi-conical volume around the BH are imparted a one-time velocity (10,000 km/s) increment. We perform hydrodynamical simulations of isolated cluster (total mass 10^14 /h M_sun), which is initially evolved to form a dense cool core, having central T<10^6 K. A BH resides at the cluster center, and ejects energy. The feedback-driven fast wind undergoes shock with the slower-moving gas, …
Active galactic nuclei (AGN) feedback has a major impact onto the supermassive black-hole (SMBH) growth, the properties of the host galaxies, and their cosmic evolution. We investigate the effects of different kinetic feedback prescriptions on the observable properties of AGN and their host galaxies at $z>6$ in a suite of zoom-in cosmological simulations. We find that kinetic feedback decreases the column density of the interstellar medium (ISM) in the host galaxy by up to a factor of $\approx10$, especially when the SMBHs reach high accretion rates ($\approx10-30\,\mathrm{M_\odot\,yr^{-1}}$).…
We present three-dimensional hydrodynamical simulations showing the effect of kinetic and radiative AGN feedback on a model galaxy representing a massive quiescent low-redshift early-type galaxy of $M_* = 8.41\times 10^{10} M_\odot$, harbouring a $M_\mathrm{BH} = 4\times 10^8 M_\odot $ black hole surrounded by a cooling gaseous halo. We show that, for a total baryon fraction of $\sim 20\%$ of the cosmological value, feedback from the AGN can keep the galaxy quiescent for about 4.35 Gyr and with properties consistent with black hole mass and X-ray luminosity scaling relations. However, this can…
It is well established that the properties of supermassive black holes and their host galaxies are correlated through scaling relations. While hydrodynamical cosmological simulations have begun to account for the co-evolution of BHs and galaxies, they typically have neglected the BH spin, even though it may play an important role in modulating the growth and feedback of BHs. Here we introduce a new sub-grid model for the BH spin evolution in the moving-mesh code {\small AREPO} in order to improve the physical faithfulness of the BH modelling in galaxy formation simulations. We account for seve…
We compare several common sub-grid implementations of AGN feedback, focusing on the effects of different triggering mechanisms and the differences between thermal and kinetic feedback. Our main result is that pure thermal feedback that is centrally injected behaves differently from feedback with even a small kinetic component. Specifically, pure thermal feedback results in excessive condensation and smothering of the AGN by cold gas because the feedback energy does not propagate to large enough radii. We do not see large differences between implementations of different triggering mechanisms, a…
We perform zoom-in cosmological simulations of a suite of dwarf galaxies, examining the impact of cosmic-rays generated by supernovae, including the effect of diffusion. We first look at the effect of varying the uncertain cosmic ray parameters by repeatedly simulating a single galaxy. Then we fix the comic ray model and simulate five dwarf systems with virial masses range from 8-30 $\times 10^{10}$ Msun. We find that including cosmic ray feedback (with diffusion) consistently leads to disk dominated systems with relatively flat rotation curves and constant star formation rates. In contrast, o…
It is the twentieth anniversary of the publication of the seminal papers by Magorrian et al. and Silk & Rees which, along with other related work, ignited an explosion of publications connecting active galactic nuclei (AGN)-driven outflows to galaxy evolution. With a surge in observations of AGN outflows, studies are attempting to directly test AGN feedback models using the outflow properties. With a focus on outflows traced by optical and CO emission lines, we discuss significant challenges which greatly complicate this task from both an observational and theoretical perspective. We highlight…
We introduce an updated physical model to simulate the formation and evolution of galaxies in cosmological, large-scale gravity+magnetohydrodynamical simulations with the moving mesh code AREPO. The overall framework builds upon the successes of the Illustris galaxy formation model, and includes prescriptions for star formation, stellar evolution, chemical enrichment, primordial and metal-line cooling of the gas, stellar feedback with galactic outflows, and black hole formation, growth and multi-mode feedback. In this paper we give a comprehensive description of the physical and numerical adva…
Interpreting the stacked kinetic SZ signal II: the degeneracy between satellite galaxies and baryonic feedback
Institute of Astronomy, University of Cambridge（剑桥大学天文学研究所）；Kavli Institute for Cosmology Cambridge（卡弗里宇宙学剑桥研究所）；Donostia International Physics Center（多诺斯蒂亚国际物理中心）；IKERBASQUE, Basque Foundation for Science（伊克巴萨奎，巴斯克科学基金会）
We study the impact of a warm dark matter (WDM) cosmology on dwarf galaxy formation through a suite of cosmological hydrodynamical zoom-in simulations of $M_{\rm halo} \approx10^{10}\,M_{\odot}$ dark matter halos as part of the Feedback in Realistic Environments (FIRE) project. A main focus of this paper is to evaluate the combined effects of dark matter physics and stellar feedback on the well-known small-scale issues found in cold dark matter (CDM) models. We find that the $z=0$ stellar mass of a galaxy is strongly correlated with the central density of its host dark matter halo at the time …
We discuss the role of protostellar outflow feedback in clustered star formation using the observational data of recent molecular outflow surveys toward nearby cluster-forming clumps. We found that for almost all clumps, the outflow momentum injection rate is significantly larger than the turbulence dissipation rate. Therefore, the outflow feedback is likely to maintain supersonic turbulence in the clumps. For less massive clumps such as B59, L1551, and L1641N, the outflow kinetic energy is comparable to the clump gravitational energy. In such clumps, the outflow feedback probably affects sign…
Recent observations of giant ellipticals and brightest cluster galaxies (BCGs) provide tentative evidence for a correlation between the luminosity of the H$α$ emitting gas filaments and the strength of feedback associated with the active galactic nucleus (AGN). Motivated by this, we use 3D radiation-hydrodynamic simulations with the code Enzo to examine and quantify the relationship between the observable properties of the H$α$ filaments and the kinetic and radiative feedback from supermassive black holes in BCGs. We find that the spatial extent and total mass of the filaments show positive co…
We study the population of supermassive black holes (SMBHs) and their effects on massive central galaxies in the IllustrisTNG cosmological hydrodynamical simulations of galaxy formation. The employed model for SMBH growth and feedback assumes a two-mode scenario in which the feedback from active galactic nuclei occurs through a kinetic, comparatively efficient mode at low accretion rates relative to the Eddington limit, and in the form of a thermal, less efficient mode at high accretion rates. We show that the quenching of massive central galaxies happens coincidently with kinetic-mode feedbac…
We investigate black hole-host galaxy scaling relations in cosmological simulations with a self-consistent black hole growth and feedback model. The sub-grid accretion model captures the key scalings governing angular momentum transport from galactic scales down to parsec scales, while our kinetic feedback implementation enables the injection of outflows with properties chosen to match observed nuclear outflows. We show that "quasar mode" feedback can have a large impact on the thermal properties of the intergalactic medium and the growth of galaxies and massive black holes for kinetic feedbac…
