Include Active Galactic Nuclei Feedback Research Articles

The role of active galactic nucleus feedback on the evolution of dwarf galaxies from cosmological simulations. Supermassive black holes suppress star formation in low-mass galaxies

Recent observational studies suggest that feedback from active galactic nuclei (AGNs) may play an important role in the formation and evolution of dwarf galaxies, an issue that has received little attention from a theoretical perspective. We investigated this using two sets of 12 cosmological magnetohydrodynamic simulations of the formation of dwarf galaxies (10$^ M_ M$_ M_ one set using a version of the AURIGA galaxy formation physics model including AGN feedback and a parallel set with AGN feedback turned off. We show that the full-physics AGN runs satisfactorily reproduce several scaling relations, including the black-hole-to-stellar mass (M$_ BH $-M$_ star $), the black-hole-to-sigma (M$_ BH and the baryonic Tully-Fisher relation. We find that the global star formation (SF) of galaxies run with an AGN is reduced compared to the one in which the AGN has been turned off, suggesting that AGN feedback is a viable way of suppressing SF in dwarf galaxies, even though none of our galaxies is completely quenched by $z$=$0$. Furthermore, we find a tight correlation between the median SF rates and the BH $/M$_ star $ ratio in our simulated dwarfs. Star formation is suppressed due to gas heating in the vicinity of the AGN: less HI gas is available in AGN runs, though the total amount of gas is preserved across the two settings within each galaxy. This indicates that the main effect of AGN feedback in our dwarfs is to heat up and push the gas away from the galaxy's centre rather than expelling it completely. Finally, we show that the two galaxies harbouring the largest supermassive black holes have suffered a considerable (up to sim 65$\,<!PCT!>$) reduction in their central dark matter density, pinpointing the role of AGNs in determining the final dark matter mass distribution within dwarf galaxies. This pilot paper highlights the importance of modelling AGN feedback at the lowest mass scales and the impact this can have on dwarf galaxy evolution.

Qwind3: UV line-driven accretion disc wind models for AGN feedback

ABSTRACT The ultraviolet (UV) bright accretion disc in active galactic nuclei (AGNs) should give rise to line driving, producing a powerful wind that may play an important role in AGN feedback as well as in producing structures like the broad-line region. However, coupled radiation-hydrodynamic codes are complex and expensive, so we calculate the winds instead using a non-hydrodynamical approach (the qwind framework). The original qwind model assumed the initial conditions in the wind, and had only simple radiation transport. Here, we present an improved version that derives the wind initial conditions and has significantly improved ray tracing to calculate the wind absorption self-consistently, given the extended nature of the UV emission. We also correct the radiation flux for relativistic effects and assess the impact of this on the wind velocity. These changes mean the model is more physical, so its predictions are more robust. We find that, even when accounting for relativistic effects, winds can regularly achieve velocities ≃(0.1−0.5)c, and carry mass-loss rates that can be up to 80 per cent of the accreted mass for black hole masses of 107−9 M⊙, and mass accretion rates of 50 per cent of the Eddington rate. Overall, the ratio of kinetic power carried by the wind to bolometric luminosity increases with mass accretion rate at a given black hole mass, unlike the constant fraction generally assumed in current cosmological simulations that include AGN feedback. The updated code, qwind3, is publicly available in GitHub.1

A Parameter Space Exploration of High-resolution Numerically Evolved Early Type Galaxies Including AGN Feedback and Accurate Dynamical Treatment of Stellar Orbits

An extensive exploration of the model parameter space of axisymmetric early type galaxies (ETGs) hosting a central supermassive black hole (SMBH) is conducted by means of high-resolution hydrodynamical simulations performed with our code MACER. Global properties such as (1) total SMBH accreted mass, (2) final X-ray luminosity and temperature of the X-ray emitting halos, (3) total amount of new stars formed from the cooling gas, and (4) total ejected mass in the form of supernovae and active galactic nuclei (AGN) feedback induced galactic winds, are obtained as a function of galaxy structure and internal dynamics. In addition to the galactic dark matter halo, the model galaxies are also embedded in a group/cluster dark matter halo; finally, cosmological accretion is also included, with the amount and time dependence derived from cosmological simulations. Angular momentum conservation leads to the formation of cold H i disks; these disks further evolve under the action of star formation induced by disk instabilities, of the associated mass discharge onto the central SMBH, and of the consequent AGN feedback. At the end of the simulations, the hot (metal-enriched) gas mass is roughly 10% the mass in the old stars, with twice as much having been ejected into the intergalactic medium. The cold gas disks are approximately kiloparsec in size, and the metal-rich new stars are in 0.1 kpc disks. The masses of cold gas and new stars are roughly 0.1% of the mass of the old stars. Overall, the final systems appear to reproduce quite successfully the main global properties of real ETGs.

The impact of AGN feedback on galaxy intrinsic alignments in the Horizon simulations

ABSTRACT The intrinsic correlations of galaxy shapes and orientations across the large-scale structure of the Universe are a known contaminant to weak gravitational lensing. They are known to be dependent on galaxy properties, such as their mass and morphologies. The complex interplay between alignments and the physical processes that drive galaxy evolution remains vastly unexplored. We assess the sensitivity of intrinsic alignments (shapes and angular momenta) to active galactic nuclei (AGN) feedback by comparing galaxy alignment in twin runs of the cosmological hydrodynamical Horizon simulation, which do and do not include AGN feedback, respectively. We measure intrinsic alignments in three dimensions and in projection at $z$ = 0 and $z$ = 1. We find that the projected alignment signal of all galaxies with resolved shapes with respect to the density field in the simulation is robust to AGN feedback, thus giving similar predictions for contamination to weak lensing. The relative alignment of galaxy shapes around galaxy positions is however significantly impacted, especially when considering high-mass ellipsoids. Using a sample of galaxy ‘twins’ across simulations, we determine that AGN changes both the galaxy selection and their actual alignments. Finally, we measure the alignments of angular momenta of galaxies with their nearest filament. Overall, these are more significant in the presence of AGN as a result of the higher abundance of massive pressure-supported galaxies.

Using Real and Simulated Measurements of the Thermal Sunyaev–Zel’dovich Effect to Constrain Models of AGN Feedback

Abstract Energetic feedback from active galactic nuclei (AGNs) is often used in simulations to resolve several outstanding issues in galaxy formation, but its impact is still not fully understood. Here, we derive new constraints on AGN feedback by comparing observations and simulations of the thermal Sunyaev–Zel’dovich (tSZ) effect. We draw on previous observational results that used data from the South Pole Telescope (SPT) and Atacama Cosmology Telescope (ACT) to measure the tSZ signal from ≥1011 M ⊙ and ≥1 Gyr galaxies at z = 0.5–1.0 (low-z) and z = 1.0–1.5 (high-z). Using the large-scale cosmological hydrodynamical simulations Horizon-AGN and Horizon-NoAGN, which include and omit AGN feedback, we extract simulated tSZ measurements around galaxies equivalent to the observational work. We find that the Horizon-AGN results only differ from the SPT measurements at levels of 0.4σ (low-z) and 0.6σ (high-z), but differ from the ACT measurements by 3.4σ (low-z) and 2.3σ (high-z). The Horizon-noAGN results provide a slightly better fit to the SPT measurements by differing by 0.2σ (low-z) and 0.4σ (high-z), but are a significantly better match to the ACT measurements by differing by only 0.5σ (low-z) and 1.4σ (high-z). We conclude that, while the lower-mass (≲5 × 1011 M ⊙) SPT results allow for the presence AGN feedback energy, the higher-mass (≳5 × 1011 M ⊙) ACT results show significantly less energy than predicted in the simulation including AGN feedback, while more closely matching the simulation without AGN feedback, indicating that AGN feedback may be milder than often predicted in simulations.

Constraints on AGN feedback from its Sunyaev–Zel'dovich imprint on the cosmic background radiation

We derive constraints on feedback by active galactic nuclei (AGN) by setting limits on their thermal Sunyaev-Zel'dovich (SZ) imprint on the cosmic microwave background (CMB). The amplitude of any SZ signature is small and degenerate with the poorly known sub-mm spectral energy distribution of the AGN host galaxy and other unresolved dusty sources along the line of sight. Here we break this degeneracy by combining microwave and sub-mm data from Planck with all-sky far-infrared maps from the AKARI satellite. We first test our measurement pipeline using the Sloan Digital Sky Survey (SDSS) redMaPPer catalogue of galaxy clusters, finding a highly significant detection ($>$$20\sigma$) of the SZ effect together with correlated dust emission. We then constrain the SZ signal associated with spectroscopically confirmed quasi-stellar objects (QSOs) from SDSS data release 7 (DR7) and the Baryon Oscillation Spectroscopic Survey (BOSS) DR12. We obtain a low-significance ($1.6\sigma$) hint of an SZ signal, pointing towards a mean thermal energy of $\simeq 5 \times 10^{60}$ erg, lower than reported in some previous studies. A comparison of our results with high-resolution hydrodynamical simulations including AGN feedback suggests QSO host masses of $M_{200c} \sim 4 \times 10^{12}~h^{-1}M_\odot$, but with a large uncertainty. Our analysis provides no conclusive evidence for an SZ signal specifically associated with AGN feedback.

CONSTRAINING AGN FEEDBACK IN MASSIVE ELLIPTICALS WITH SOUTH POLE TELESCOPE MEASUREMENTS OF THE THERMAL SUNYAEV–ZEL’DOVICH EFFECT

ABSTRACT Energetic feedback due to active galactic nuclei (AGNs) is likely to play an important role in the observed anti-hierarchical trend in the evolution of galaxies, and yet the energy injected into the circumgalactic medium by this process is largely unknown. One promising approach to constrain this feedback is through measurements of spectral distortions in the cosmic microwave background due to the thermal Sunyaev–Zeldovich (tSZ) effect, whose magnitude is directly proportional to the energy input by AGNs. With current instruments, making such measurements requires stacking large numbers of objects to increase signal-to-noise. While one possible target for such stacks is AGNs themselves, these are relatively scarce sources that contain contaminating emission that complicates tSZ measurements. Here we adopt an alternative approach and co-add South Pole Telescope SZ (SPT-SZ) survey data around a large set of massive quiescent elliptical galaxies at z ≥ 0.5 ?> , which are much more numerous and less contaminated than active AGNs, yet are subject to the same feedback processes from the AGNs they hosted in the past. We use data from the Blanco Cosmology Survey and VISTA Hemisphere Survey to create a large catalog of galaxies split up into two redshift bins: one with 3394 galaxies at 0.5 ≤ z ≤ 1.0 ?> and one with 924 galaxies at 1.0 ≤ z ≤ 1.5 , ?> with typical stellar masses of 1.5 × 10 11 M ⊙ . ?> We then co-add the emission around these galaxies, resulting in a measured tSZ signal at 2.2 &sgr; ?> significance for the lower redshift bin and a contaminating signal at 1.1 &sgr; ?> for the higher redshift bin. To remove contamination due to dust emission, we use SPT-SZ source counts to model a contaminant source population in both the SPT-SZ bands and Planck high-frequency bands for a subset of 937 galaxies in the low-redshift bin and 240 galaxies in the high-redshift bin. This increases our detection to 3.6 &sgr; ?> for low redshifts and 0.9 &sgr; ?> for high redshifts. We find the mean angularly integrated Compton-y values to be 2.2 − 0.7 + 0.9 × 10 − 7 ?> Mpc2 for low redshifts and 1.7 − 1.8 + 2.2 × 10 − 7 ?> Mpc2 for high redshifts, corresponding to total thermal energies of 7.6 − 2.3 + 3.0 × 10 60 ?> erg and 6.0 − 6.3 + 7.7 × 10 60 ?> erg, respectively. These numbers are higher than expected from simple theoretical models that do not include AGN feedback, and serve as constraints that can be applied to current simulations of massive galaxy formation.

Theoretical uncertainties due to AGN subgrid models in predictions of galaxy cluster observable properties

Cosmological constraints derived from galaxy clusters rely on accurate predictions of cluster observable properties, in which feedback from active galactic nuclei (AGN) is a critical component. In order to model the physical effects due to supermassive black holes (SMBH) on cosmological scales, subgrid modeling is required, and a variety of implementations have been developed in the literature. However, theoretical uncertainties due to model and parameter variations are not yet well understood, limiting the predictive power of simulations including AGN feedback. By performing a detailed parameter sensitivity study in a single cluster using several commonly-adopted AGN accretion and feedback models with FLASH, we quantify the model uncertainties in predictions of cluster integrated properties. We find that quantities that are more sensitive to gas density have larger uncertainties (~20% for Mgas and a factor of ~2 for Lx at R500), whereas Tx, Ysz, and Yx are more robust (~10-20% at R500). To make predictions beyond this level of accuracy would require more constraints on the most relevant parameters: the accretion model, mechanical heating efficiency, and size of feedback region. By studying the impact of AGN feedback on the scaling relations, we find that an anti-correlation exists between Mgas and Tx, which is another reason why Ysz and Yx are excellent mass proxies. This anti-correlation also implies that AGN feedback is likely to be an important source of intrinsic scatter in the Mgas-Tx and Lx-Tx relations.

Heating and enriching the intracluster medium

We present numerical simulations of galaxy clusters with stochastic heating from active galactic nuclei (AGN) that are able to reproduce the observed entropy and temperature profiles of non-cool-core (NCC) clusters. Our study uses N-body hydrodynamical simulations to investigate how star formation, metal production, black hole accretion and the associated feedback from supernovae and AGN heat and enrich diffuse gas in galaxy clusters. We assess how different implementations of these processes affect the thermal and chemical properties of the intracluster medium (ICM), using high-quality X-ray observations of local clusters to constrain our models. For the purposes of this study we have resimulated a sample of 25 massive galaxy clusters extracted from the Millennium Simulation. Sub-grid physics is handled using a semi-analytic model of galaxy formation, thus guaranteeing that the source of feedback in our simulations is a population of galaxies with realistic properties. We find that supernova feedback has no effect on the entropy and metallicity structure of the ICM, regardless of the method used to inject energy and metals into the diffuse gas. By including AGN feedback, we are able to explain the observed entropy and metallicity profiles of clusters, as well as the X-ray luminosity-temperature scaling relation for NCC systems. A stochastic model of AGN energy injection motivated by anisotropic jet heating - presented for the first time here - is crucial for this success. With the addition of metal-dependent radiative cooling, our model is also able to produce CC clusters, without overcooling of gas in dense, central regions.

Gas expulsion by quasar-driven winds as a solution to the overcooling problem in galaxy groups and clusters

Galaxy groups are not scaled down versions of massive galaxy clusters - the hot gas in groups (known as the intragroup medium, IGrM for short) is, on average, less dense than the intracluster medium, implying that one or more non-gravitational processes (e.g., radiative cooling, star formation, and/or feedback) has had a relatively larger effect on groups. In the present study, we compare a number of cosmological hydrodynamic simulations that form part of the OverWhelmingly Large Simulations project to isolate and quantify the effects of cooling and feedback from supernovae (SNe) and active galactic nuclei (AGN) on the gas. This is achieved by comparing Lagrangian thermal histories of the gas in the different runs, which were all started from identical initial conditions. While radiative cooling, star formation, and SN feedback are all necessary ingredients, only runs that also include AGN feedback are able to successfully reproduce the optical and X-ray properties of groups and low-mass clusters. We isolate how, when, and exactly what gas is heated by AGN. Interestingly, we find that the gas that constitutes the present-day IGrM is that which was not strongly heated by AGN. Instead, the low median density/high median entropy of the gas in present-day groups is achieved by the ejection of lower entropy gas from low-mass progenitor galaxies at high redshift (primarily 2 < z < 4). This corresponds to the epoch when supermassive black holes accreted most of their mass, typically at a rate that is close to the Eddington limit (i.e., when the black holes are in a `quasar mode').