TBD

The origin of supermassive black holes remains a major outstanding issue in modern astrophysics. These monster black holes reside in the nuclei of essentially every massive galaxy and power the most luminous quasars at the edge of the observable Universe. However, directly observing the first seed black holes in the early Universe - that can eventually grow to upwards of a billion solar masses - is not feasible with current telescopes. Present-day dwarf galaxies, on the other hand, are within observational reach and offer another avenue to learn about black hole seeds since low-mass galaxies can host relatively pristine black holes. In this talk, I will present ongoing multi-wavelength searches for AGNs in dwarf galaxies, as well as follow-up studies of existing samples. I will also discuss how this work has implications for directly detecting black hole activity in the first galaxies at high redshift.

I will present results from our search for dwarf Black Holes (BHs) in the nearby Universe. Two independent methods have been used: the spectroscopic follow up of candidate small BHs selected from the SDSS, which hints a paucity of (active) BHs below galaxy absolute magnitudes of Mg = -18; the search of (active) dwarf BHs by variability signatures detected in the HiTS survey, which explored 120-150 square degrees of sky during a week in 2013, 2014 and 2015 each, and is sensitive to time scales of a few hours (Forster et al., 2016, Martinez et al., 2018).

The population and properties of massive black holes in dwarf galaxies provide our best constraints on the formation of black hole seeds at high redshift and are important for our understanding of co-evolution of galaxies and their black holes. I will discuss recent results characterizing the structure of RGG 118, the host galaxy of an active 50,000 solar mass black hole, and the position of this system on scaling relations between black hole mass and host galaxy properties. I will also present our larger efforts to populate the low-mass end of the M-sigma relation, and discuss potential new methodologies for searching for black holes in dwarf galaxies.

Reverberation mapping and scaling relationships based on reverberation results provide the underpinning of all estimates of quasar black hole masses. When applying these scaling relationships, there are potential pitfalls that are widely unappreciated and can result in biases that can, in turn, lead to systematic errors in the black hole mass function and therefore conclusions about the evolution of black holes over time. I will discuss potential sources of biases and show how they can be mitigated.

Supermassive black holes (BHs) residing in the brightest cluster galaxies (BCGs) are over-massive relative to the stellar bulge mass or central stellar velocity dispersion of their host galaxy. Since BHs residing at the bottom of the galaxy cluster's potential well may undergo physical processes that are driven by the large-scale characteristics of the galaxy clusters, it is possible that the growth of these BHs is (indirectly) governed by the properties of their host clusters. We investigate a sample of BCGs with dynamical BH mass measurements and utilize X-ray observations to measure the virial temperatures and infer the total mass of the galaxy clusters. We demonstrate that the M_BH - kT (hence M_BH - M_500) relation is significantly tighter and exhibits smaller scatter than the M_BH - M_bulge relation. Thus, the BH mass of BCGs may be set by physical processes that are governed by the properties of the host galaxy group/cluster.

The observed scaling relations between supermassive black hole (SMBH) masses and host galaxy properties suggest that both SMBHs and galaxies evolve in tandem, a process that could be regulated by AGN feedback. I will show how this synchronized SMBH-galaxy evolution paradigm has been recently challenged by the discovery that (i) those SMBHs at the high-mass end of the scaling relations and residing in brightest cluster galaxies (BCGs) are found to be, on average, offset from the fundamental plane of black hole accretion, which is an empirical correlation between a black hole’s X-ray and radio luminosity and mass supported by theoretical models of accretion. For BCGs to on average follow the fundamental plane, a large fraction should have black hole masses >1e10 Msun and thus host ultramassive black holes. The local SMBH-galaxy scaling relations would not hold for these extreme objects; (ii) on the low-mass end, the M-sigma flattens and forms a plume, as expected from models in which AGN in low-mass galaxies are the fossils of those seed black holes from the early Universe that did not grow into SMBHs. We find that the break in the M-sigma occurs at a stellar mass of ~3e10 Msun, remarkably similar to that of the galaxy luminosity function, and that it marks a transition from the AGN-dominated feedback regime of high-mass galaxies to a supernovae-driven regime in low-mass systems, in agreement with numerical simulations.

The discovery of relations between supermassive black holes (BHs) and their host-galaxy properties has sparked many observational studies pertaining both to the local Universe and cosmic history. Nevertheless, a clear understanding of their origin and fundamental drivers still eludes us. Studying the evolution of these relations depends on our understanding of the slope and scatter of local relations for active galaxies (AGNs). From a unique sample of ~100 local type-1 AGNs spanning a wide range of BH masses (MBH), morphologies, and stellar masses, we build a robust baseline of the BH mass scaling relations (MBH-sigma, MBH-L, MBH-M), combining spatially-resolved Keck spectroscopy with HST and Gemini near-infrared imaging. We establish the fundamental MBH relationship and determine whether the scaling relations are universal or depend on other parameters such as (minor) mergers, (pseudo) bulges, and/or bars. This identifies the driving force behind the relations, hierarchical assembly vs. AGN feedback. Selection biases in the reverberation-mapped (RM) AGN sample, the MBH calibrator of the Universe, can be probed. Comparing the results with low resolution and low S/N data provides recipes to correct derived galaxy properties for effects of data quality. We will also present first results of spatially-resolved kinematics of RM AGNs host galaxies, the most robust MBH and sigma measurements of AGNs in the Universe. Our sample more than double existing data in the high mass regime, essential to determine the slope of the MBH-sigma relation, its intercept and scatter, constrain the average f factor, and identify dependencies of the relation on luminosity, Eddington ratio and host-galaxy morphology. Our sample forms the crucial low-z anchor for the determination of MBH in AGNs throughout the Universe.

It has been long assumed that SMBHs form and evolve hand in hand with their galaxy host. However, a sample of nearby massive compact galaxies, fossil relics of the high-z massive population, is telling us a different history (Ferre-Mateu et al. 2015, 2017a). These local red nuggets, massive compact galaxies without merging accretion since z~2, seem to have a set of very thrilling properties. One of them is that they all host seemingly ubermassive SMBHs. This makes them extreme outliers in the SMBH-galaxy local scaling relations, challenging the assumed universal co-evolution. In this talk, I will show that this is due to the uncommon evolutionary path followed by these relic galaxies, whereas the SMBHs grow in an expected way. Finally, I will show that there is a strong dependence with galaxy mass, which changes the nature of such deviations. The relic scenario prevails for massive galaxies, but as we go to less massive ones, stripping of the galaxy mass becomes the relevant process that places them outside the scaling relations.

Observations of the ionised and molecular gas dynamics in the nuclei of galaxies are essential to characterise AGN fuelling. Changing-look AGN show a dramatic change in accretion rate (over a factor of 100) that occurs in only a matter of decades. They provide a laboratory to study the physics of AGN fuelling and the onset of black hole accretion in a much shorter timescale than the thousands of years or more expected for the typical AGN on/off transitions. In this contribution I will present recent MUSE optical integral field observations of the gas and stellar dynamics in a changing-look AGN. We observe an interplay of inflow and outflow gas dynamics in the centre of the galaxy which suggests a cyclic nature for the fuelling of the AGN. Combining our new data with observations of the cold and warm molecular gas allowed us to determine the role of the AGN in the excitation and dynamics of the gas and to characterise the AGN gas fuelling reservoir. I will discuss how changing-look AGN can be used as a tool to set constraints on the AGN fuelling process in general.

I will discuss recent progress in cosmological hydrodynamic simulations of galaxy formation at unprecedented volumes and resolution. I will focus on predictions of the formation the first large galaxies and quasars. These massive objects at high redshifts will be investigated with the next generation telescopes (Euclid, JWST and WFIRST).

To reach the observed masses in excess of a billion solar masses by z=7, seed black holes must a have grown by orders of magnitude through gas accretion or mergers. In the gas-rich early universe, gas accretion is expected to play a major role in the origin of these first supermassive black holes. How much mass a black hole is able to gain via gas accretion is determined both by the global gas supply, and by the detailed structure of gas in the black hole vicinity. Using the black hole zoom algorithm to resolve the immediate black hole environment by orders of magnitude above that of that of the host galaxy, the simulations presented here are able to follow the early black hole evolution in great detail. This work demonstrates the importance of sub-pc size gas features for the accretion duty cycle of the black hole, highlights the importance of dynamics of the black hole within its host, and sheds light on the early co-evolution between supermassive black hole progenitors and their host galaxies at redshift z>10.

In the traditional picture of co-evolving galaxies and BHs, gas inflows in galaxy mergers are thought to be the main trigger for AGN activity being closely linked to starbursts of the host galaxy. Recent observations and advanced theoretical models, however, question the universality of this simple picture. I will discuss new insights on the evolution of galaxies and their central BHs in a cosmological setting employing two different approaches, semi-analytic galaxy formation models (SAMs) and large-scale cosmological, hydrodynamic simulations. Both methods are successful in reproducing a number of observational, statistical constraints, such as the observed anti-hierarchical trend in the evolution of AGN number densities. These models indicate that only luminous AGN are preferentially driven by merger events, while for the majority of moderately luminous AGN, also other driving processes seem to be needed. Despite of the great success in matching many observational facts, further comparisons with observations also reveal several deficiencies of the adopted models for BH growth and AGN feedback such as e.g. an under-estimation of active BHs at low redshifts. Future perspectives for further improvement of models for BH growth will be given.

TBD

Understanding nuclear fueling in a cosmological context is a crucial step towards uncovering the nature of black hole-galaxy co-evolution. Recent progress from cosmological hydrodynamic simulations has been limited by either resolution, interstellar medium and stellar feedback physics, or the treatment of black hole accretion. In this talk, I will present results from the Feedback In Realistic Environments (FIRE) project, modeling stellar feedback by supernovae, stellar winds, and radiation on the scale of star-forming regions and black hole growth using a gravitational torque-based prescription tied to the properties of galactic nuclei. By resolving the inner 100 pc of galaxies, I will show that bursty stellar feedback regulates the gas reservoir in galactic nuclei and can severely limit early black hole growth, which has important implications for black hole-galaxy scaling relations, AGN demographics and time variability, the formation of early quasars, and massive black hole mergers.

I propose to discuss the multiplicity of ALMA Compact Array (ACA) 870 []micron counterparts of 28 infrared-bright SDSS quasars at redshifts 2 – 4. Their star formation rates (SFRs) are estimated to be above 1000 Msol/yr. The majority (80%) of the sources have unique ACA counterparts, with only a handful of clear cases of multiple sources. I will discuss the implications of this multiplicity (or lack thereof) and place these results in the general context of major mergers as triggers of bright AGN.

I will review recent results on the clustering and environments of AGN, comparing results for AGN identified at different wavelengths, luminosities, and redshifts. I will also compare the clustering of AGN to galaxies in the same redshift and volume, taking into account AGN identification biases, and discuss the fundamental role that these biases play when interpreting AGN clustering and environment results.

Supermassive black holes potentially play an important role in galaxy evolution via feedback mechanisms that could regulate or even quench star formation in galaxies. However, there are also indications that galaxies may shield themselves thanks to their substructure, or that the growth and fueling of black holes may simply follow along that of galaxies due to sharing a common gas reservoir. I will present a few lines of evidence including a statistical analysis of a large sample of >200,000 galaxies, a detailed case study of a nearby AGN host for which we obtained 3D spectroscopy in order to investigate the multi-scale connection between the AGN and its host, and I will tie the results together with simulations of isolated AGN hosts with resolved interstellar medium structure.

We study the population of supermassive black holes (BHs) and the connection between active galactic nuclei (AGN) and their host galaxies through cosmic time, in the large-scale cosmological hydrodynamical simulations IllustrisTNG. We first present BH properties, such the hard X-ray BH luminosity function, BH/AGN galaxy occupation fraction, and distribution of BH Eddington ratios, and compare them to available observational constraints. We then study galaxy stellar mass and size distributions across cosmic time, and design redshift-dependent criteria to identify star-forming vs quiescent, and compact vs extended galaxies in the simulations. We build a specific star-formation rate - stellar surface density diagram, and analyze how the simulated galaxies populate this diagram. There has been much debate in the literature about the physical processes that drive galaxys’ evolution through this diagram, and the role of AGN feedback in quenching galaxies. For a large fraction of quiescent galaxies, we find that their star-forming progenitors first experienced a compaction event, forming the population of star-forming compact galaxies, and then a quenching event that brings these galaxies to the compact quiescent galaxy population. We measure the dependence of AGN fraction on a galaxy's location in the diagram, and find a high fraction of X-ray luminous AGN in the compact star-forming part of the diagram, and a low AGN fraction in the quiescent compact part, in good agreement with recent results from observational data of the CANDELS survey.

Black hole (BH) feedback is a common ingredient to virtually all state-of-the-art numerical simulations. In particular, energy input from active galactic nuclei (AGN) is thought to be the main channel for quenching star formation in the most massive halos. Yet, observationally constraining this AGN-regulated quenching path remains challenging because of the radically different time-scales of AGN activity and star formation processes. I will present an innovative observational approach to understand the interplay between BHs and host galaxies that combines detailed stellar population analyses with known BH scaling relations. We find that star formation histories and stellar population properties of host galaxies depend on the mass of the central BH, and that this coupled evolution applies to all generations of stars formed throughout a galaxy's life. Our results suggest that the effect of BH feedback is a function of galaxy mass, with more massive galaxies being more BH-dominated. Our findings are in remarkable agreement with a bi-modal paradigm of star formation, where supernova feedback controls baryonic cooling within low-mass dark matter halos, and AGN regulates star formation in massive galaxies, as expected from simulations.

We will present recent results on galaxy quenching and morphology in clusters and proto-clusters detected as overdensities around radio-loud AGN at z>1.5 from the CARLA (Clusters Around Radio-Loud AGN) survey. Galaxy clusters in the local Universe predominantly host a population of massive, passive early-type galaxies, which formed the bulk of their stellar populations at redshifts z~2-3. The progenitors of these present-day clusters are clusters and proto-clusters at z>1.5 that are still in the process of assembling. CARLA is the largest homogeneous sample of spectroscopically confirmed clusters and proto-clusters currently available, with 16 clusters and proto-clusters that cover the redshift range 1.6

Galaxy mergers have long been implicated as drivers of supermassive black hole (BH) and galaxy co-evolution, but the relative importance of mergers for fueling active galactic nuclei (AGN) is still uncertain. The ongoing debate stems in part from selection effects inherent to empirical studies of the merger-AGN connection. For example, the most luminous AGN are often heavily obscured in late-stage mergers; some of these can be revealed only in the infrared (IR) or hard X-rays. AGN in pairs or binaries, or even recoiling AGN, can provide direct evidence of a link between mergers and BH growth. Conclusive evidence for such systems continues to be largely elusive, but growing numbers of promising candidate binaries and confirmed kpc-scale AGN pairs have been found. I will review recent progress from theory and observations in uncovering the role of mergers in BH fueling and co-evolution with galaxies, as well as the prospects for further advances in the near future with next-generation simulations and telescope.

The gravitational interaction at parsec to sub-parsec scales between a gaseous circumbinary disc and a super massive black hole binary (SMBHB) is a promising mechanism to drive the migration of SMBHBs toward coalescence. The typical dynamical evolution can be separated in two main regimes: I) Slow migration (T mig ∼ 1e3−1e4 × T orb ), where viscous torques are not efficient enough to redistribute the extracted angular momentum from the binary, leading to the formation of a low density cavity around the binary. II) Fast migration (T_{mig} ∼ 1e2-1e3 × T orb ), in which the redistribution of angular momentum is efficient and no low density cavity is formed in the circumbinary disc. Using N-Body/SPH simulations we study the effect of AGN feedback in this phase of a SMBHB evolution. We implement an AGN accretion/feedback model in the SPH code Gadget-3 which include momentum feedback from winds, x-ray heating/radial-momentum and Eddington force. Using this implementation we run a set of simulations of SMBHB+disc in the two main shrinking regimes. From these simulations we conclude that the effect of the AGN mechanical feedback is negligible for SMBHBs in the slowly shrinking regime. However, in the fast shrinking regime the AGN wind excavate a “feedback cavity” leaving the SMBHB almost naked, thus stalling the orbital decay of the binary.

Black holes (BHs) can build up their mass through accretion and/or BH-BH mergers. The latter is a long journey that begins with two BHs, separated by hundreds of kpc in the center of two different galaxies, and it ends with the merger of these two BHs via the emission of gravitational waves occurring when they are separated by a less than a micro-pc. Due to the wide range of scales involved, capturing the whole story is today impossible, but it is needed to understand how long the BH merger might take and how efficient is the growth via mergers. We perform simulations of galaxy mergers up to the formation of the BHs binary. I will present the last phase of the galaxy merger, when the two BHs are separated by a few kpc up to the formation of the BHs binary. We find that, in this suite of galaxy mergers, dynamical friction from the smooth stellar component of the nucleus is the main process that drives black holes dynamics. Gas does not play a crucial role and even clumps do not induce scattering or perturb the orbits.

Near the end of its inspiral, a black hole binary recoils due to anisotropic emission of gravitational waves. I will discuss simulations of such recoiling black holes from z = 20 to z = 0 in dark matter haloes, quantifying how parameter choices affect escape velocities. These choices include the strength of dynamical friction, the presence of stars and gas, the accelerating expansion of the Universe (Hubble acceleration), host halo accretion and motion, and seed black hole mass. LCDM halo accretion increases escape velocities by up to 0.6 dex and significantly shortens return time-scales compared to non-accreting cases. Other parameters change orbit damping rates but have subdominant effects on escape velocities. I conclude by discussing how these findings affect black hole mass assembly as well as minimum stellar and halo masses necessary to retain supermassive black holes.

I will briefly summarize results on the cosmic evolution of black holes at various wavelengths, which gives us a general picture of the era of quasars, cosmic downsizing, and trends in quasar properties. I will then highlight some issues, concerns, and outliers from that general picture, including studies of the most heavily obscured, most luminous AGN, the most distant quasars, super-Eddington accretion, and new results from time domain studies.

The detection of large, statistically meaningful samples of QSOs around and below L* at z >6, and over a wide range of obscuring column densities, would provide unique constraints on the formation and early growth of BHs. This will require a next generation of X-ray observatories that can perform surveys to comparable depths as the deepest Chandra fields, but over a substantially larger areas. The ATHENA X-ray observatory (Nandra et al. 2013), currently approved as an ESA large mission for a launch in 2028, has the capability to probe this new discovery space. After a brief summary of the state of the art of present deep XMM and Chandra surveys, I will present the observational strategy of future multi-cone ATHENA Wide Field Imager (WFI) surveys and the expected breakthroughs in the determination of the luminosity function and its evolution at high (> 4) and very high (> 6) redshifts. The survey is considered a major investement of the entire ATHENA science program and will take more tha one year of observations. I will conclude discussing the perspectives for the detection of line dominated, heavily obscured, sources triugh the detection of redshifted Kalpha lines with the XIFU calorimeter.

Feedback from active galactic nuclei (AGN) is likely to play a key role in the observed evolution history of massive 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 CMB spectral distortions due to the thermal Sunyaev-Zel'dovich (tSZ) effect, whose magnitude is directly proportional to the energy input by AGN. I will describe our ongoing efforts to apply this approach to moderate-redshift elliptical galaxies outside of galaxy clusters, which maintain the thermal signatures of past AGN, but do not contaminate the signal through their radio emission. I will show that existing data from the South Pole Telescope and the Atacama Cosmology Telescope (ACT) are already sensitive enough to derive preliminary constraints on models of AGN feedback that are otherwise very difficult to distinguish. These constraints will soon improve dramatically with the next generation of CMB and submillimeter experiments.

Radio-loud AGN are typically found in the most massive galaxies at all cosmic epochs, and the energy injected by radio jets into the interstellar medium of these galaxies can have a profound effect on their evolution. I will describe some recent results from a spectroscopic study of over 10,000 radio galaxies and radio-loud QSOs, showing that there are two distinct populations that differ both in their cosmic evolution and in the environments where they are found. I will also present some early results from a search for redshifted 21cm HI absorption in and around distant radio galaxies, taking advantage of the new parameter space opened up by the Australian SKA Pathfinder (ASKAP) telescope in its commissioning phase.

The last few years has seen major progress in large surveys of quasars across the electromagnetic spectrum. Astronomers are beginning to constrain the luminosity function and clustering of quasars across a large span of redshift, and a wide range of the quasar SED. In this talk, I will review recent measurements of quasars as a function of luminosity, wavelength and redshift. I will place a particular emphasis on how the large-scale distribution of quasars informs us about the dark matter halos that quasars inhabit. By combining measurements in the IR, X-rays and optical, I will discuss current measurements in the context of the cosmic evolution of quasars as a population. Finally, I will project possible future constraints from the next generation of large surveys.

I will discuss the contribution of quasars to reionization and the AGN quenching of star formation in high-redshift massive quiescent galaxies using the Meraxes semi-analytic model. The model is calibrated against observed galaxy properties including the stellar mass, black hole mass, and quasar luminosity functions at z ∼ 0.6–6, as well as the reionization history using the global ionizing emissivity at z ∼ 2–5 and the Thomson scattering optical depth. Our model disfavours the possibility that faint AGN dominate reionization, suggesting that stellar light from galaxies hosting faint AGN contributes the bulk of the observed UV flux in these systems at high redshift. Indeed, the ionising photons from central massive black holes alone cannot reionize the Universe by z~5. However, AGN feedback is seen to play an important role in quenching star formation in massive galaxies at z~4, and our model suggests the recently discovered massive quiescent galaxy, ZF-COSMOS-20115 to be the decendent of a luminous z>6 quasar.

AGN have always been a challenge for accretion disk models, which generally do not do a good job in explaining observations. I will highlight some of the basic physical issues that must be theoretically understood in order to make progress, focusing on high luminosity systems. These include the consequences of high levels of radiation pressure and the roles of winds.

The environments in which supermassive black holes form and grow probably contain a substantial, organized magnetic field, even at high redshifts. I will discuss how this field might affect the formation and accretion process, including the possibility that net magnetic flux accumulates to the point where it flips the accretion disk into a magnetically elevated state or disrupts it entirely.

I present the results of a large XMM-Newton program on a sample of 30 extremely UV-luminous quasars at z>3, providing the first high-quality study of the disk-corona connection in high luminosity, high redshift quasars. About 30% of the sources show a relatively weak/flat X-ray emission, indicative of a low efficiency in the disk-corona connection; the remaining 70% of the sources are X-ray bright and show very homogeneous X-ray properties, indicative of a common physical state of the disk+corona system. The non-linear X-ray to UV relation for these objects has a dispersion of only 0.11 dex. This implies that quasars are excellent standard candles: 7-8 quasars provide the same cosmological information as one supernova 1A, opening the possibility to extend the Hubble diagram up to redshifts z>6.

Supermassive black holes (SMBHs) reside in essentially every massive galaxy and are energetically important components of their host systems. From a cosmological perspective, the growth of SMBHs through accretion (observed via AGN activity) broadly tracks the evolution of star formation (SF), and both processes are likely to be primarily fueled by the supply of cold gas in galaxies. Still, the extent to which SMBH growth is connected to SF in *individual* galaxies has remained a matter of intense investigation that faces many challenges. For example, SMBH accretion occurs on much shorter timescales and smaller physical scales than SF, and AGN or SF activity can often be highly obscured. There is also complex physics at play in the processes of accretion, SF, and positive (or negative) feedback. I will give an overview of recent observational and theoretical progress in studying the AGN - SF connection, and point toward future potential breakthroughs with new observational facilities.

I will present evidence, based on new ALMA measurements, for mergers, feedback and star formation in a complete flux limited sample of 40 high luminosity AGN at a very narrow redshift range around z=4.8. The new data, part of a large multi-wavelength project in collaboration with Paulina Lira, Benny Trakhtenbrot and several others, make this the most uniform, best studied sample of massive black holes and their host galaxies in the early universe. We are able to measure accurate SF rates (SFRs) which are well below the Herschel limit, because of the improved ALMA sensitivity, and because we can remove the contribution of Herschel-unresolved companions that are SMGs. Combined with dynamical estimates of the stellar mass, we find that in some objects the SFR is below the main sequence at this redshift. We can asses the importance of mergers on the evolution and starburst activity and provide evidence for extremely large SFR, exceeding 2000 Msun/yr, which is not associated with merger activity. A comparison of the SFRs and black hole accretion rates in this sample with measurements in the local universe provides a way to measure the relative duty cycles of the two processes. For massive systems at high redshift, the two processes have comparable duty cycles.

In this talk I will present our latest results on the star formation properties of X-ray selected AGN at both low (z~0) and high (z~1.5-3.0) redshift, utilising sensitive Herschel and ALMA data. I will show how the star-formation properties of the X-ray AGN population, particularly the distribution of star-formation rates, are consistent with those expected from AGN feedback predicted by a leading hydrodynamical simulation (EAGLE). Significantly I will also show that the properties of the star-formation rate distributions are inconsistent with the EAGLE simulation without AGN feedback. I will discuss these results in the broader context of the role of AGN in the formation and evolution of galaxies.

I will discuss the suppression of black-hole growth at low galaxy masses and the activation of rapid black-hole growth above a critical halo mass due to the interplay between supernova feedback, a hot CGM, and the crucial role of wet compaction. This is based on a combination of basic analytic modeling and simulations.

The latest models of AGN-galaxy co-evolution suggest a crucial influence of the AGN on the host, being the former capable to drive energetic outflows from the inner to the outer regions, thus acting on the dust content and so on both the star formation and the black hole accretion. I will present the results obtained from two large samples with complementary properties. The first one is represented by the WISSH project, where we are investigating the presence of outflows in the most luminous quasars known, in which the coupling between the central engine output and the host galaxy is expected to be at its maximum. We studied the SED of ~90 type I AGN at 2

Collisions and interactions between galaxies are thought to be pivotal stages in their formation and evolution, causing the rapid production of new stars, and possibly serving as a mechanism for fueling supermassive black holes (BHs). Harnessing the exquisite spatial resolution afforded by the Hyper Suprime-Cam (HSC) Survey, I will present our new constraints on the importance of galaxy-galaxy major mergers in growing obscured BHs throughout the last ~7 Gyrs. Using a novel machine-learning technique, we identify galaxy interactions and use these data to map the growth of BHs as a function of interaction-stage, redshift and AGN luminosity, ultimately providing the necessary large-number statistics required to investigate merger-AGN triggering in the context of galaxy evolution out to z~1.

The emergence of the three-dimensional structure of the cosmic web over the history of the Universe displays very distinctive features when observed in X-rays, where both the most massive collapsed structure (clusters of galaxies) and the most energetic events in the life of galaxies (AGN and Quasars) reveal themselves unambiguously. In the past 50 years, astronomers have used X-ray surveys to tackle fundamental questions for structure formation; In particular, I will focus my attention on those related to black holes’ evolution, such as: How did supermassive black holes form and grow in the nuclei of galaxies? Why are their physical properties today so tightly linked to those of their hosts? How did scaling relations emerge over the history of the Universe? What was the impact on the surrounding structures of the copious energy release, either in radiative or mechanical form, associated to the growth of such black holes in active galactic nuclei (AGN)? In my talk, I will review how constraints available from a multi-wavelength AGN surveys on the growth of the supermassive black holes can be used to give at least partial answers to some of these questions.

I will present an update on the on-going surveys of luminous quasars during the epoch of reionization, at z>6.5. Using the combination of deep, wide-area photometric imaging surveys in optical, near and mid-IR wavelengths, we are now establishing the first complete sample of quasars at z~7, with the highest redshift at z=7.5. I will discuss the determination of luminosity function of z~7 quasars, and the implications of the discovery of these early quasars to the models of black hole growth at high redshift.

Understanding how supermassive black holes (SMBHs) grow and co-evolve with their host galaxies, especially at high redshift, remains one of the main challenges in astrophysics. Several aspects of this co-evolution have been studied theoretically and in observations, indicating for instance, a close correlation between galaxy (bulge) mass and SMBH mass. However, a consensus on how this correlation and others come about, has yet to be reached. I will present results from the MassiveFIRE suite of high-resolution, cosmological simulations regarding the co-evolution of galaxies and SMBHs at high redshift. In particular, I will discuss the growth of SMBHs in the context of different gas accretion models that were added in post-processing and discuss the origin of the observed scaling relations in the simulations. Furthermore, I will discuss the conditions of high-z galaxies under which SMBHs can grow efficiently.

Luminous, dust-obscured quasars have been hypothesized to represent the missing evolutionary link between starburst galaxies and unobscured quasars and are therefore an important transition population in galaxy evolution. Using infrared surveys over wide areas, we have identified a unique population of extremely dusty, high-luminosity quasars at z=2-3, which host some of the most massive black-holes seen at these epochs (Banerji et al. 2012, 2015). The first ALMA observations of the population demonstrated that gas-rich, dusty host galaxies are ubiquitous in these quasars (Banerji et al. 2017). I will summarise these results and present new observations of the host galaxies of these quasars with SCUBA-2, ALMA and the VLA. Observations of multiple molecular lines in these galaxies are now allowing us to constrain the gas excitation and interstellar medium properties of the quasar hosts. Finally, high angular-resolution observations with ALMA are enabling us to resolve close separation major-mergers as well as map the velocity fields to perform full dynamical modelling of the host galaxies, thus placing important constraints on the location of these transition systems on the MBH-Mgal relation.

I will present the relation between blackhole mass and host galaxy dynamical mass at high z (z~4-6). We have considered a sample of ~15 quasars at high redshift for which we have obtained measurements of the host galaxy kinematics from ALMA observations of molecular or atomic transitions. For the first time, we are able to measure galaxy masses dynamically, by modelling the kinematics of galaxy disks, thus avoiding all the problems and biases from photometric measurements of stellar masses. I will discuss the results obtained within the coevolution scenario and highlight the constraints that they pose on models of galaxy evolution.

In preparation for the Large Synoptic Survey Telescope (LSST), which will revolutionize time-domain astronomy, it is critical that we understand variable phenomena as deeply as possible. Variability is arguably the defining feature of Active Galactic Nuclei (AGN), and is observed in every waveband, so variability studies are fundamental to understanding the extreme physical conditions of accretion disks near supermassive black holes. Several efforts have analyzed variability in the optical. However, to relate the variability and physical properties of AGN, we need well sampled light curves, which are still rare. At the same time very little is known about variability in the near infrared (NIR). At low redshift this waveband gives us information about the dust surrounding the accretion disk; at high redshift it tells us about the accretion disk itself. In this talk I will present the current status of our QUEST-La Silla AGN variability survey. We are using the QUEST camera on the ESO-Schmidt telescope to obtain well sampled optical light curves of AGN in well-studied extragalactic fields that already have multiwavelength observations. I will present our results on the study of the link between the variability properties (e.g., characteristic time-scales and amplitudes of variation) with physical parameters of the system (e.g., black-hole mass, luminosity, and Eddington ratio). In addition, I will present our statistical study of the NIR variability of AGN in the COSMOS field, using UltraVISTA data. This dataset give us a huge sample of light curves, allowing us to construct a global description of the nature of AGNs for different ranges of redshift, and for different levels of obscuration.

The observation of extremely massive black holes shining as quasars up to z~7.5 requires either large BH seeds or episodes of supercritical accretion. I will comment on the current and future constraints on supercritical accretion, on how it can be triggered, and on the possibility of observing supercritically growing MBHs.

AGN that seem to be triggered (or die out) on short timescales of 10-20 years may hold important clues to how black holes feed and to the structure of the central engine of AGN. This is because they often go from no (or low) black hole activity gradually to full activity which allow us to disentangle and study how the emission components build up.  They may also allow insights on whether supermassive black holes go through hard/soft accretion state changes like stellar mass black holes.  I will report on a recent multi-wavelength study and monitoring campaign of one such target that appear to play hide-and-seek with us. After 20 years as a bona-fide AGN, its broad emission lines and its nuclear continuum disappeared suddenly within years. Now 10 years on, it went into a sudden outburst for several months and died out again.  I will give a status of our ongoing study and what we have learned from studying such targets with a multitude of telescopes such as ALMA, Swift, HST, VLT and VLBA.

Several observations show that the presence of an AGN has an impact on the surrounding gas. Numerical simulations of galaxy formation and evolution include such a feedback by injecting energy or momentum into the ISM / ICM. However, the details of the interaction of the AGN-jet or AGN-radiation with the different phases of the gas are still difficult to probe. The advent of ALMA now gives access to the cold (molecular) gas phase at low and high redshift. Observing the physical and dynamical state of this gas tells us about the amount of gas available to fuel star formation. Molecular disk, outflows or filaments are now observed in emission or absorption and sometimes, the AGN radio-feedback appears to be a driver to form locally cold and dense gas in the interacting zone. In this talk I will present recent examples of such AGN-gas interactions and open discussions on the state and the fate of this gas.

One of the major remaining goals in observational cosmology is to understand how our Universe transitioned from the dark ages, following recombination, into the ionized universe we can observe today. For this purpose we compiled a new data set of 36 high redshift (5.8

Unified theories explain the wide diversity of observed properties of AGN mainly as due to the nuclear obscuration by dusty/molecular tori that extend on 1-10 parsec scales. Due to their limited (u, v) coverage, IR interferometric data have been thus far limited in providing a direct image of the putative AGN tori. Thanks to its large number of antennas, this limitation can be to a large extent circumvented in the submillimeter using interferometers like ALMA. We will review the recent results obtained by ALMA in a sample of 10 nearby Seyfert galaxies, which includes the prototypical Seyfert 2 galaxy NGC1068, where ALMA has imaged for the first time its molecular/dusty torus in several molecular transitions.

Quasars at z>6 (age of the Universe: <1 Gyr) are arguably the most active astrophysical objects in the early universe. They are powered by fast accretion on their central black holes (which already have masses of 0.1-10 billion Msun). Their galaxies form stars at rates of >100 Msun/yr, and, despite the young cosmic age, they appear chemically enriched. These humongous star formation and accretion rates are fueled by immense gaseous reservoirs. We present a systematic study of the gas reservoirs in z>6 quasars. Our observations at (sub-)mm wavelengths reveal for the first time the mass, spatial extent, chemistry, kinematics, and physical properties of the interstellar medium in these quasars, thus constraining the build up of the first massive galaxies and black holes and the AGN impact on their gas.

Molecular hydrogen (H2) is a fundamental component of galaxies, being the most abundant element in molecular clouds, where stars form, and an important source of radiative cooling at low temperature. With the advent of the ALMA telescope, we have started to collect data of the H2 distribution in galaxies with unprecedented resolution. In particular, we are now starting to resolve the distribution of molecular gas in high redshift quasar hosts, and this is giving us important information about the kinematics and dynamics of the system. However, the large majority of numerical simulations on galactic and cosmological scales still lacks the ability to directly follow the formation and dissociation of H2, and must rely on pre-calibrated sub-grid models to compare the results with observations. I will present a numerical study of the H2 kinematics and dynamics in a massive halo at z=6, expected to be a quasar host, in which I self-consistently follow the evolution of H2 with non-equilibrium chemistry, including gas and dust shielding, H2 self-shielding, star formation, supernova feedback, and extragalactic and local stellar radiation. I will discuss in particular the role of the central AGN in shaping its galaxy host, and in producing outflows, both in the ionised/neutral and molecular phases.

Understanding the gaseous halo surrounding a galaxy is an integral part to understanding galaxy evolution. The z ~ 2 universe is interesting as this is the peak of star formation and AGN activity. My work is part of the Quasars Probing Quasars survey, which is nearing conclusion. Quasars Probing Quasars is designed for studying massive galaxy formation and quasar feedback. I use background quasar sightlines that pass close to foreground quasars to study the circumgalactic medium of quasar-host galaxies, in absorption. I present results on the statistical and physical properties of the absorbing gas clumps. Compared to more typical coeval star-forming galaxies, the quasar circumgalactic medium is more massive, is more enriched, and exhibits more extreme kinematics. Then I present evidence that the ionizing radiation from the quasar is anisotropic or intermittent and that the circumgalactic gas is not in inflow. I will discuss future directions of (1) studying the impact of the quasar on its gaseous environments in emission with IFU; and (2) going to the lower redshift universe for better constraining AGN feedback.

Quantifying how and how much of the ionizing radiation produced in high-redshift galaxies escapes in the IGM is one of the main challenges in understanding the sources of reionization. While star forming dwarf galaxies are often considered as the primary driver of reionization, their actual contribution to the cosmic ultraviolet background is still uncertain, mostly because of the uncertainty on the escape fraction of ionizing radiation. While it has been shown previously that supernovae can carve holes in the gas distribution through which ionizing photons can escape, the effect of AGN feedback on the escape fraction is still a relatively unexplored area. Using radiation-hydrodynamic cosmological zoom simulations performed with Ramses-RT, we investigate in Trebitsch et al (submitted, arXiv:1712.05804) the combined role of AGN and stellar feedback in regulating the escape fraction in dwarf galaxies. In relation with the issue of understanding black hole growth in high-redshift dwarf galaxies, I will discuss how this extra source of feedback could (or not) enhance the escape fraction of stellar ionizing radiation in these galaxies. We confirm that in low mass galaxies, supernova feedback reduces BH growth by preventing gas to be accreted. This implies that AGN feedback in dwarf galaxies is inefficient at affecting the gas distribution in the ISM, and thus does not enhance the leakage of ionizing radiation further than what results from supernova feedback. A second consequence is that any contribution to the ionizing budget of reionization resulting from the accretion onto MBH in dwarf galaxies must be very low.

Feedback from supermassive black holes is now thought to be one of the key components of galaxy formation. It is well known that active nuclei are capable of launching powerful winds and jets, but until recently the impact of these phenomena on galactic scales was poorly measured and poorly understood. I will review observational techniques used in measuring feedback from active galactic nuclei, summarize exciting new results and discuss unsolved problems and outstanding issues.

Recent molecular line observations with ALMA in several nearby Seyferts have revealed the existence of molecular tori, and the nature of gas flows at 10-20pc scale. In some cases, the angular resolution of up to 80mas allows us to reach the BH-zone of influence and the BH mass can be derived more precisely than with the M-sigma relation. The role of nuclear molecular outflows and molecular tori can now be studied in detail. At 100pc scale, or kpc-scale, previous work on gravitational torques had shown that only about one third of Seyfert galaxies experienced molecular inflow and central fueling, while in most cases the gas was stalled in rings. At higher resolution, i.e. 10-20pc scale, it is possible now to see AGN fueling due to nuclear trailing spirals, influenced by the black hole potential. This brings smoking gun evidence for nuclear fueling.

I present ALMA and high spectral resolution optical/infrared observations from the ESO-VLT of a sample of distant powerful radio galaxies which provide insights into how massive galaxies are quenched. Unlike previous results, our new deeper ALMA observations imply that most of the host galaxies are not forming stars vigorously but are, in fact, quenched. The hosts that do have vigorous star formation have signatures of O- and B-type stars in their rest-frame UV spectra providing robust constraints on their ages and other parameters. I discuss the mechanisms underlying these results and the hypothesis that star formation must have played a key role in exhausting the gas supply and extinguishing these galaxies. However, our results raise many more interesting questions then they solve and hence this presentation will hopefully motivate vigorous discussion throughout the meeting.

AGN feedback is now accepted as an integral part of galaxy evolution. One of the most successful feedback models is the wind-driven outflow model, which has been shown, both analytically and numerically, to reproduce many of the observed correlations between AGN and outflow properties. However, when setting up models and analysing observations, several simplifying assumptions are typically made, one of which is that the AGN luminosity has been constant over the duration of the outflow. This is highly unlikely to be the case, and so in order to move forward, we have to understand the effects of repeated AGN episodes and of AGN luminosity decay at the end of episodes, to the evolution of the outflows. I will review the basic physics and the major results of the wind-driven outflow model and present the recent advances in treating the different time-evolution of the AGN luminosity and the outflow properties. I will focus on how this affects the observed correlations and how the correlations can be used as constraints on the evolutionary scenarios of AGN.

Galactic winds are invoked in simulations of galaxy evolution to shut down star formation and therefore explain several observed properties, such as the lack of over-massive galaxies or the correlation between the supermassive black hole and its host galaxy. Observational evidence of outflows has been seen in many phases. Ionised outflows have been observed on kpc-scales in many local galaxies and increasingly also detections of massive molecular outflows are reported, but only few studies have compared the different phases and often using inhomogeneous samples. Unlike previous studies, we investigate the molecular and the ionised phase of galactic outflows in the same sample, therefore allowing detailed studies about their connection, physical origin and establish how effective they are in quenching star formation in the local Universe. The multi-phase approach allows us to probe different spatial scales and to obtain a more detailed and more complete picture of the mechanism driving outflows. We collect an unprecedented sample of about 50 local (z < 0.2) galaxies with molecular outflows in low-J CO lines using the Atacama Large Millimetre Array (ALMA). We derive their properties, i.e. momentum, energy and outflow rate, explore their dependence on host galaxy properties and investigate whether they are consistent with model predictions. In sub-sample of over 20 galaxies, we compare the properties and scaling relations of molecular outflows with ionised outflows from the literature or available Multi Unit Spectroscopic Explorer (MUSE) data. The excellent spatial resolution of MUSE allows an in-depth comparison with ALMA results of molecular outflows concerning the morphology and also what the connection between the two phases is.

We present a mechanism for quenching star formation in galaxies that is driven and maintained by large-scale AGN outflows. Using the high resolution Romulus25 cosmological simulation, which incorporates a careful implementation of supermassive black hole (SMBH) physics (Tremmel+ 2017), we show how AGN feedback can drive powerful outflows reaching 10s - 100s of kpc. These outflows then interact with inflowing material and can cut off the gas supply onto the central galaxy. Quenched galaxies that are unable to sustain large-scale winds will eventually rejuvenate back onto the star forming main-sequence. Extending this analysis to cluster-scales using the RomulusC simulation, the highest resolution simulation of a galaxy cluster to date, we show how this process is also able to limit and quench star formation in the central galaxy of cool-core clusters.

We investigate the effects of AGN feedback on the cosmological evolution of an isolated elliptical galaxy by performing two-dimensional high-resolution hydrodynamical numerical simulations. The inner boundary of the simulation is chosen so that the Bondi radius is resolved, which is crucial for the determination of the mass accretion rate of the AGN. According to the theory of black hole accretion, there are two accretion modes, hot and cold, which correspond to different accretion rates and have different radiation and wind outputs. In our simulations, the two modes are discriminated and the feedback effects by radiation and wind in each mode are taken into account. The main improvement of the present work compared to previous ones is that we adopt the most updated AGN physics, including the descriptions of radiation and wind from the hot accretion flows and wind from cold accretion disks. Physical processes like star formation, Type Ia and Type II supernovae are taken into account. We study the AGN light ce, typical AGN lifetime, growth of the black hole mass, AGN duty-cycle, star formation, and the X-ray surface brightness of the galaxy. We have compared our simulation results with observations and found general consistency. Comparisons with previous simulation works find significant differences, indicating the importance of AGN physics. The respective roles of radiation and wind feedbacks are examined and it is found that they are different for different problems of interest such as AGN luminosity and star formation. We find that it is hard to neglect any of them, so we suggest to simply use the names of cold feedback mode and hot feedback mode to replace the currently used names.

Theoretical models of AGN radiative feedback predict that AGN-driven, galaxy wide massive outflows are not a rare and peculiar phenomenon, but a fundamental process affecting the bulk of the baryons in the universe. I will report the results of our on-going studies to address three questions: a) demography of AGN driven outflows on a statistical sample of AGN; b) how the properties (e.g. energetics and geometry) of such outflows are connected with the properties of the central SMBH; c) which is the impact of such outflows on the gas content of the host galaxy. The studies are focused on z~2 AGNs, and they are based on data taken with SINFONI (SUPER survey and archival data) to trace the ionized gas and ALMA CO observations to trace the molecular gas content.

High-redshift AGN have become a prominent tool for the study of the epoch of hydrogen reionisation. One of the most surprising results to come from the study of the lines of sight towards AGN relates to extreme fluctuations in the IGM's opacity to Lyman-alpha radiation at the end of reionisation. This patchiness has been the basis of many new models, some including populations of (yet undetected) faint AGN during the EoR. We have assembled the largest sample to date of z>5.7 AGN spectra in the optical in order to refine the constraints on this patchiness and evaluate the viability of such models. Using 92 such objects, we more than triple on previous samples and constrain cosmic variance better than ever before. I will present the results of this investigation, and an update on the evidence for faint AGN during the EoR.

Relativistic jets from AGNs are an important driver of feedback in galaxies. Although primarily considered in the context of energy deposition at scales of ~50-100 kpc to regulate mass inflow, the jets first interact with the host galaxy's ISM before breaking out to larger scales. Our recent 3D relativistic hydrodynamic simulations, performed on scales of ~5 kpc with a resolution of 6pc, investigates the interaction of such jets with an inhomogeneous turbulent ISM within the potential of a galaxy. These simulations address the local gas physics, which is often missed in large scale cosmological simulations due to lack of sufficient resolution. The jets are found to couple strongly with the turbulent ISM, driving fast moving lateral outflows of multi-phase gas. The resultant outflows though strong, do not escape the galaxy, supporting a galactic fountain scenario of feedback, rather than a blow out phase as envisaged previously. We compare the effect of jet power and ISM density on the feedback efficiency. We show that low power jets remain confined within the host for a longer time driving shocks through the ISM, potentially quenching star formation on a large scale. We have performed simulations with two different ISM morphologies: spherical and disk. Jet-ISM coupling is stronger in spherically distributed gas. In gas disks, although the jet breaks out easily, the ensuing high pressure bubble compresses the disk driving shocks. Jets inclined to the disk behave differently, launching sub-relativistic vertical outflows while strongly perturbing the disk, as observed in galaxies like NGC 1052, IC 5063 etc. I will discuss the implications of these results on the evolution of the ISM of the host galaxy, and the effects on observable diagnostics such as line emission from shocked gas, thermal Xrays and synchrotron emission in radio wavelengths.

The role of AGN in the transition of galaxies from actively star forming to quiescence is still not fully understood, and is particularly challenging to study for AGN that are weak or hidden by obscuration or host dilution. NGC1266 is a transitioning galaxy, home to massive molecular outflow driven by its AGN. The turbulence injected into its interstellar medium by the outflow, indicated by its shocked optical gas ratios, may account for the suppression of its star formation activity by a factor of at least 50. While the AGN clearly has an important mechanical impact on NGC1266, its radiative qualities are more difficult to characterize. ALMA and CARMA measurements of dense gas tracers show that its nuclear region lies behind a column of at least N(H2) = 3 x 10^24 cm^-2. Continuum ALMA observations marginally resolve a region of FIR emission within 30pc of the nucleus emitting L(IR) > 10^10 Lsun, which could be heated either by a luminous AGN or an ultracompact nuclear starburst. We use a deep Chandra observation combined with a NuSTAR observation of NGC1266 to determine the radiative properties of its AGN and thereby its contribution to the dust heating observed by ALMA with implications on the distribution of the star formation suppression.