Dans l’Univers, on observe des galaxies lointaines ne formant plus d’étoiles, mais les astrophysiciens n’ont pas encore identifié avec certitude les phénomènes physiques à l’origine de leur “mort”. Pour apporter des éléments de réponse, je me suis penchée sur l’étude de phénomènes qui pourraient y jouer un rôle : les processus de rétroaction des étoiles et des trous noirs supermassifs actifs, la formation stellaire, et les vents galactiques. Le Chapitre 1 présente toutes les notions nécessaires à la compréhension du problème : les caractéristiques des galaxies typiques de l’Univers proche et lointain ; les vents galactiques ; la mort des galaxies; les trous noirs supermassifs actifs (noyaux actifs de galaxies, AGN) et les étoiles ; et leur rétroaction. Dans le Chapitre 2, je présente les techniques numériques utilisées : le code de simulations astrophysiques RAMSES et le code de transfert radiatif Cloudy, que j’ai utilisé pour développer une méthode de calcul de l’état d’ionisation d’une galaxie, détaillée au Chapitre 3. Le Chapitre 4 étudie le couplage entre les trous noirs actifs et les étoiles, avec le projet POGO, Origines Physiques des Vents Galactiques. Durant cette thèse, j’ai montré que les trous noirs actifs n’étaient pas en mesure de tuer subitement leur hôte, même en prenant en compte la rétroaction des étoiles, et que leur couplage peut réduire ou renforcer les vents dans les galaxies en fonction de leur masse. Le Chapitre 5 fait un état de l’art du domaine avant et pendant mon doctorat, reprend les conclusions de cette thèse et donne quelques perspectives, notamment en ce qui concerne le rôle additionnel des rayons cosmiques dans la mort des galaxies / In the Universe, we observe galaxies forming no, or almost no, stars anymore, but astrophysicists do not know yet what physical mechanisms cause their “death”. To give clues to solve the problem, I studied feedback processes from stars and active supermassive black holes, star formation and galactic outflows. Chapter 1 presents all the notions to understand the problem: the characteristics of typical galaxies in the local and distant Universe, galactic outflows, galaxy death, active supermassive black holes, stars, and their feedback processes. In Chapter 2, I describe the numerical techniques I used: the simulation code RAMSES, and the radiative transfer code Cloudy, which I used to develop a computation method to get the ionization state of an entire galaxy. This method is presented in Chapter 3. Chapter 4 studies the coupling between the feedback processes of active supermassive black holes and stars, with the POGO project, Physical Origins of Galactic Outflows. During this thesis, I showed that typical active supermassive black hole cannot suddenly kill their host, even when stellar feedback processes are accounted for, and that their coupling either reduces or enhances the mass outflow rate depending on the mass of the host. In Chapter 5, I give a state-of-the-art about active supermassive black holes before and during my thesis, sum up the conclusions of the work, and give perspectives to enlarge the scope of the study, especially regarding the additional role of cosmic rays in the death of galaxies

In recent years, advances in deep optical, and especially deep near-infrared imaging with the Hubble Space Telescope (HST) and wide-field ground-based telescopes such as VISTA, have revolutionized our understanding of the cosmological evolution of galaxies and supermassive black-holes (as manifest through active galactic nuclei; AGN). In particular, the dynamic range provided by the survey `wedding cake' of available HST+ground-based optical/IR data offers new opportunities to push the meaningful statistical study of galaxy and AGN evolution out to high redshifts. Much recent attention has focused, unsurprisingly, on using these new data to push studies of galaxy formation back to within a billion years of the Big Bang, and exploring the role of young galaxies in driving cosmic hydrogen reionization during the crucial era corresponding to redshifts z ≃ 6-10. However, these data have not been as thoroughly exploited at intermediate redshifts, and have only recently been used to explore black-hole/AGN evolution. In this thesis I utilise the latest deep optical/near-infrared imaging and spectroscopy to explore three key facets of cosmological evolution. First, I present a new, robust measurement of the evolving rest-frame ultraviolet (UV) galaxy luminosity function (LF) over the key redshift range from z ≃ 2 to z ≃ 4. My results are based on the high dynamic range provided by combining the Hubble Ultra Deep Field (HUDF), CANDELS/GOODS-South, and UltraVISTA/COSMOS surveys. I utilise the unparalleled multi-frequency photometry available in this survey `wedding cake' to compile complete galaxy samples at z ≃ 2; 3; 4 via photometric redshifts (calibrated against the latest spectroscopy). This study is important as the peak of star-formation is shown to happen within a redshift range z = 2 - 4 and determining the exact epoch that the galaxies were forming most of their stars depends significantly on the UV luminosity density which requires robust measurements of the galaxy UV luminosity function and its accurate parameterization. My new determinations of the UV LF extend from M1500 ≃ -22 (AB mag) down to M1500 =-14.5, -15.5 and -16 at z ≃2, 3 and 4 respectively (thus reaching ≃ 3-4 magnitudes fainter than previous blank-field studies at z ≃ 2 - 3). At z ≃ 2 - 3 I find a much shallower faint-end slope (α = -1:32 ± 0:03) than the steeper values (α ≃ -1:7) reported in the literature, and show that this new measurement is robust. By z ≃ 4 the faint-end slope has steepened slightly, to α = -1:43 ± 0:04, and I show that these measurements are consistent with the overall evolutionary trend from z = 0 to z = 8. I then calculate the UV luminosity density (and hence unobscured star-formation density) and show that it peaks at z ≃ 2:5 - 3, when the Universe was ≃ 2:5 Gyr old. Second, I have used these data to revisit the possibility that X-ray AGN played a significant role in cosmic hydrogen reionization which is one of the major processes in the formation of the Universe we see today. Hence, it is really important to understand this phenomenon thoroughly by studying the properties of sources capable of ionising photons, such as star-forming galaxies and high redshift AGNs. Although most recent studies have suggested that the emerging population of young star-forming galaxies can bathe the Universe in sufficient high-energy photons to complete reionization by z ≃ 6, some authors have reasserted the potentially important role of high-redshift AGN in the hydrogen reionization process. In an effort to clarify this situation, I reinvestigate a claimed sample of 22 X-ray detected active galactic nuclei (AGN) at redshifts z > 4, which has reignited the debate as to whether young galaxies or AGN reionized the Universe. These sources lie within the GOODS-S/CANDELS field, and I examine both the robustness of the claimed X-ray detections (within the Chandra 4Ms imaging) and perform an independent analysis of the photometric redshifts of the optical/infrared counterparts. I confirm the reality of only 15 of the 22 reported X-ray detections, and moreover find that only 12 of the 22 optical/infrared counterpart galaxies actually lie robustly at z > 4. I recalculate the evolving far-UV (1500Å) luminosity density produced by AGN at high redshift, and find that it declines rapidly from z ≃ 4 to z ≃ 6, in agreement with several other recent studies of the evolving AGN luminosity function. The associated rapid decline in inferred hydrogen-ionizing emissivity contributed by AGN falls an order-of-magnitude short of the level required to maintain hydrogen ionization at z ≃ 6. I conclude that AGNs make a very minor contribution to cosmic hydrogen reionization. Finally, I have utilized the deep optical/near-infrared survey data to explore the prevalence of quenched/passive galaxies at high redshift. Applying a robust method to isolate passive galaxies from star-forming galaxies is the key to improving our understanding of the quenching process. Focusing primarily on the deep HUDF data-set, I have revisited the effectiveness of simple colour-colour (UVJ) selection techniques in isolating robust samples of quenched galaxies, and find that dust plays a more important role in this selection process than has been previously appreciated. Through careful SED fitting I successfully isolate a sample of apparently dust-free quiescent galaxies in the redshift range 0:5 < z < 4:5 but (at least in the HUDF) fail to find any galaxy which has remained truly quiescent for > 1 Gyr. I conclude by focusing on the properties of a refined/robust sample of apparently quenched galaxies at z > 3, and in particular establishing the contribution of quenched galaxies to stellar-mass density at early times. I conclude with a summary of my findings, and a brief discussion of the most promising avenues for future advances with the next generation of facilities, such as the James Webb Space Telescope (JWST).

This projects studies which early galaxy populations will be visible using the telescopes JWST and Euclid. Galaxy luminosity functions are calculated for different redshifts, with the galaxy number density as a function of apparent magnitude. The apparent magnitude is used to enable easy comparisons with the observational limits of JWST and Euclid. Added to the calculations were also the impact of gravitational lensing and how it may magnify the flux of the galaxies.  Another part of the project studied the impact of a lowest DM halo mass, the limit of the halo mass needed to create a galaxy. The existence of such a limit changes the luminosity function at low luminosities. The aim was to study if this change will be visible using the telescopes. The studies was done using a semi-analytical model of high-redshift galaxies with a Python interface.  The results showed that the visible galaxy populations varies significantly with both redshift and magnification. For lower redshifts and higher magnification more galaxies, mostly for low luminosities, are visible. The lowest DM halo masses needed to be noticeable by the telescopes was between Mmin = 2.0 × 1010 − 1.6 × 1011 M⊙. With a magnification of factor ten or 100 they instead lay between Mmin = 2.2 × 109 − 2.8 × 1010 M⊙. Compared to previous studies the effect from the limiting mass will most probably be visible by JWST with the magnification, while the values without magnification are close to the limit. For Euclid deep field the effects are not predicted to be visible even with a magnification of factor ten, but they will probably be visible with a higher magnification of a factor 100. / I detta projekt studeras vilka tidiga galaxpopulationer som kommer vara synliga med teleskopen JWST och Euclid. Galaxluminositetsfunktioner beräknas för olika rödförskjtningar med galaxtätheten som en funktion av apparent magnitud. Just apparent magnitud används för att jämförelser med de observationella gränserna för JWST och Euclid ska vara enkla att genomföra. Gravitationslinser och hur de kan förstärka galaxers luminositet lades även till beräkningarna.  I projektet studerades även hur en lägsta massa för mörk materia halos kan påverka beräkningarna. Denna massa är då gränsen för halomassan som behövs för att en galax ska kunna skapas. Ifall en sådan begränsning finns så ändras luminositetsfunktionerna för låga luminositeter. I detta projekt undersöktes det ifall denna förändring kommer vara synlig med teleskopen. Fo ̈r att utföra projektet användes en semi-analytisk modell av galaxer med hög rödförskjutning, med ett gränssnitt i Python.  Resultaten visar att de synliga galaxpopulationerna varierade starkt när förstärkning av galaxluminositet eller rödförskjutning ändrades. Med lägre rödförskjutning och högre magnifikation syntes fler galaxer, och de främsta förändringarna skedde för låga lumi- nositeter. De halomassor som behövdes för att vara synliga med teleskopen var mellan Mmin = 2.0 × 1010 − 1.6 × 1011 M⊙ utan förstärkning av luminositeten och mellan Mmin = 2.2 × 109 − 2.8 × 1010 M⊙ med en förstärkning av faktor tio eller 100. Jämfört med tidigare studier så kommer förändringarna troligtvis vara synliga med JWST ifall en förstärkning inkluderas. Utan magnifikation ligger massorna precis på gränsen. För Euclid deep field kommer effekterna ej vara synliga ens med en förstärkning av faktor tio, men de kommer troligtvis vara synliga med en högre magnifikation av faktor 100.

This thesis presents spectroscopic observations of z ≥ 7 galaxy candidates in the Hubble Ultra Deep Field, which were selected with HST WFC3 imaging, using the Lyman-Break technique. Four z-band (z ≈ 7) dropout galaxies were targeted with Gemini/GNIRS, one z-band dropout galaxy and three Y -band (z ≈ 8 − 9) dropout galaxies with VLT/XSHOOTER, and 22 z-band dropouts with VLT/FORS2, where 15 of the latter are strong candidates. No evidence of Lyman-α emission is found, and the upper limits on the Lyman-α flux and the broad-band magnitudes are used to constrain the rest-frame equivalent widths for this line emission. Amongst the targeted objects, observations were made of HUDF.YD3, a relatively bright Y -band dropout galaxy likely to be at z ≈ 8 − 9 on the basis of its colours in the HST ACS and WFC3 images. Lehnert et al. (2010) observed this galaxy using the VLT/SINFONI integral field spectrograph and claim that it exhibits Lyman-α emission at z = 8.55. In observations of this object described in this thesis, which were made with VLT/XSHOOTER and Subaru/MOIRCS, this line was not reproduced despite the expected signal in the combined MOIRCS & XSHOOTER data being 5σ. Hence it appears unlikely that the reported Lyman-α line emission at z > 8 is real. Accounting for incomplete spectral coverage, in total (across all spectro- graphs) 9.63 z-band dropouts and 1.15 Y -band dropouts are surveyed to a Lyman-α rest-frame Equivalent Width better than 75 ̊A. A model where the fraction of high rest-frame equivalent width emitters follows the trend seen at z = 3−6.5 is inconsistent with these non-detections at z = 7−9 at a confidence level of ∼ 91%, which may indicate that a significant neutral HI fraction (χHI) in the intergalactic medium suppresses the Lyman-α line at z > 7. In particular, the lack of detection of Lyman-α emission in this spectroscopy is compared with results at lower redshift by Stark et al. (2010), who derive a mapping between Lyman-α fractions and χHI based on radiative transfer simulations by McQuinn et al. (2007). These results suggest a lower limit of χHI ~ 0.5.

We calculate the angular power spectrum of the cosmic microwave background temperature fluctuations induced by the kinetic Sunyaev-Zel'dovich (kSZ) effect from the epoch of reionization (EOR). We use detailed N-body+radiative-transfer simulations to follow inhomogeneous reionization of the intergalactic medium. For the first time, we take into account the "self-regulation" of reionization: star formation in low-mass dwarf galaxies or minihalos is suppressed if these halos form in the regions that were already ionized or Lyman-Werner dissociated. Some previous work suggested that the amplitude of the kSZ power spectrum from the EOR can be described by a two-parameter family: the epoch of half-ionization and the duration of reionization. However, we argue that this picture applies only to simple forms of the reionization history which are roughly symmetric about the half-ionization epoch. In self-regulated reionization, the universe begins to be ionized early, maintains a low level of ionization for an extended period, and then finishes reionization as soon as high-mass atomically cooling halos dominate. While inclusion of self-regulation affects the amplitude of the kSZ power spectrum only modestly (~10%), it can change the duration of reionization by a factor of more than two. We conclude that the simple two-parameter family does not capture the effect of a physical, yet complex, reionization history caused by self-regulation. When added to the post-reionization kSZ contribution, our prediction for the total kSZ power spectrum is below the current upper bound from the South Pole Telescope. Therefore, the current upper bound on the kSZ effect from the EOR is consistent with our understanding of the physics of reionization. / text

Le milieu circum-galactique (CGM pour "Circum-Galactic Medium" en anglais) constitue l'interface entre les galaxies et les grandes structures au sein desquelles elles évoluent. Le milieu inter-galactique est principalement composé de gaz d'hydrogène froid, dit primordial, qui en s'accretant sur les galaxies constitue le carburant de la formation stellaire. La formation stellaire apparait alors régulée par les échanges de matière entre la galaxie et l'extérieur. En ce sens, l'étude de l'environnement des galaxies se révèle cruciale pour comprendre les mécanismes qui régissent leur formation et leur évolution. L'observation directe du CGM est toutefois assez délicate en raison de la chute de brillance des galaxies dans leurs régions externes. Sa détection est d'autant plus difficile pour les galaxies de l'Univers lointain. Quelques techniques existent pour contrecarrer cette difficulté : l'observation du CGM en absorption dans le spectre d'un quasar brillant situe sur la ligne de visée de la galaxie, ou sa détection statistique en combinant de nombreuses images de galaxies. Ces techniques ont toutefois de sévères limitations car elles ne donnent que des informations parcellaires sur le CGM. Je rapporte dans cette thèse la détection de gaz d'hydrogène froid autour de 145 galaxies (soit 80% des galaxies testees) peu massives, peu lumineuses et très distantes, émettant de l'émission Lyα. Longtemps utilisée pour son pouvoir de détection des galaxies lointaines, l'émission Lyα est maintenant utilisée comme un traceur du gaz froid du CGM, alors observable sous forme de "halos" Lyα. Notre échantillon constitue le plus grand échantillon de halos Lyα détectés individuellement autour de galaxies de faible masse et ce, à une époque pendant laquelle l'Univers est en pleine construction. Ces avancées ont été rendues possible grâce à l'incomparable sensibilité de l'instrument MUSE installé sur le "Very Large Telescope" au Chili il y a bientôt 4 ans. Seule une centaine d'heures de télescope dans la région du champ ultra profond de Hubble ont été nécessaires pour permettre la détection de halos Lyα. Nos résultats confirment la présence de grande quantité de gaz froid dans l'environnement immédiat des galaxies distantes. Ces observations étaient en effet prédites par les modèles théoriques et les simulations numériques. En plus d'être quasi-omniprésents autour des galaxies, les halos Lyα observés montrent une diversité (taille, flux, forme, profil de la raie d'émission, etc) particulièrement remarquable dans une région du ciel si restreinte (9_×9_). De plus, la possibilité d'analyser le CGM galaxie par galaxie et en trois dimensions permet maintenant d'étudier de manière directe l'impact de l'environnement sur la galaxie mais aussi l'évolution des propriétés du CGM avec les époques cosmiques. Notre grand échantillon de galaxies nous a permis de réaliser un traitement statistique robuste et de mettre en évidence que les propriétés stellaires des galaxies étudiées ne sont pas systématiquement liées à celles de l'émission Lyα. Enfin, d'après les modèles théoriques, nos observations (spectroscopiques) indiquent la présence de matière en expansion dans et/ou autour des galaxies. La présence d'accrétion de matière est, quant à elle, moins bien contrainte par nos données. Finalement, l'analyse décrite dans ce manuscrit rapporte des informations importantes et inédites sur les propriétés du CGM d'une population de galaxies relativement peu lumineuses et très abondantes dans l'Univers lointain / The circum-galactic medium (CGM) serves as the interface between galaxies and the larger structures within which they evolve. Composed primarily of cold hydrogen gas (also called primordial gas), the CGM is a major fuel source for star formation as material falls onto a galaxy from its surrounding halo. This suggests that star formation is in fact regulated by gas exchange between a galaxy and its vicinity. Thus, studying the surrounding environment of galaxies represents a crucial step in understanding the mechanisms governing their formation and evolution. Unfortunately, direct observation of the CGM is often quite difficult, since these regions are very faint. This task becomes even more challenging for galaxies in the distant Universe, though some techniques have been developed for this purpose. The CGM can be detected through absorption features in the spectrum of a more-distant quasar located along a galaxy’s line of sight or statistically, by stacking many images of galaxies together, in order to increase the overall S/N ratio of the sample. However, these methods are not ideal : both have severe limitations and only provide partial information about the CGM. In this thesis, I report the detection of cold hydrogen gas surrounding 145 low-mass, faint and very distant galaxies emitting Lyα photons (forming 80% of the total galaxy sample used in this work). While historically, Lyα emission was seen simply as a powerful tool for detecting distant galaxies, it is now possible to use it as a tracer of cold CGM gas in the form of Lyα halos. The sample presented here represents the largest collection ever compiled of individually-detected Lyα halos around normal star forming galaxies, observed in an epoch when the Universe was still forming. This achievement is possible thanks to the unrivaled sensitivity of the Multi-Unit Spectroscopic Explorer (MUSE), a next-generation instrument installed on the Very Large Telescope (VLT). In particular, we need only 100 hours of telescope time to detect the presence of Lyα halos, a significant improvement over previous efforts. My results confirm the presence of large amounts of cold gas in the immediate vicinity of distant galaxies. While such results have been predicted by theoretical models and numerical simulations, this work provides some of the first direct observational evidence of this fact. Besides being quasi-ubiquitous around galaxies, the observed Lyα halos show a large diversity in physical properties which is particularly remarkable for such a small region of the sky (9_×9_). Moreover, the 3D galaxy-by-galaxy nature of my analysis allows me to study the direct impact of environment on galaxies, as well as the evolution of the CGM with cosmic time. With such a large sample, I am also able to perform a robust statistical analysis, highlighting the fact that the stellar properties of galaxies are not systematically linked to the Lyα ones. Finally, based on theoretical models, my (spectroscopic) observations indicate the presence of expanding materials inside and/or around the galaxies. However, the presence of galactic inflows are less constrained by the data. Taken as a whole, the analysis described in this thesis represents important, new information about the CGM properties of the relatively faint galaxies which make up the bulk of the galaxy population in the distant Universe. Therefore, this work should serve as a useful reference point as research into the CGM continues to advance

No description available.

Il y a de plus en plus d'indications que les trous noirs super-massifs ont joué un rôle important dans l'évolution des galaxies, en particulier au moment de la formation des galaxies les plus massives à haut décalage spectral vers le rouge (z ~ 2 - 3). Nous nous sommes attachés à quantifier les effets sur le milieu interstellaire des galaxies hôtes que peuvent avoir les jets des radio-galaxies, d'une part, et les importantes luminosités bolometriques des quasars, d'autre part. Pour cela, nous avons étudié la cinématique du gaz ionisé dans 12 radio-galaxies modérément puissantes et dans 11 quasars (6 avec une détection en radio et 5 sans jet détectable) à grand décalage spectral vers le rouge avec le spectro-imageur proche infra-rouge SINFONI du VLT, qui nous donnait accès aux raies d'émission normalement sitées dans le domaine visible. Afin d'évaluer la capacité du NAG à stopper la formation d'étoiles, nous avons cherché des traces de leur rétroaction dans ces galaxies, comme de vents de gaz s'échappant de la galaxie hôte. Dans notre échantillon de radio-galaxies modérément puissantes, nous observons des dispersions de vitesse presque aussi importantes que dans les plus puissantes (avec une FWHM ~ 1000 km/s), mais les quantités de gaz ionisé observées y sont inférieures d'un ordre de grandeur (Mion gas ~ 10^8 - 10^9 Msun) et les gradients de vitesse sont plus faibles (Δv < 400 km/s), quand ils sont observés. Dans notre échantillon de quasars, nous devions d'abord soustraire la composante large des raies d'émission avant de pouvoir étudier leur composante étroite, celle susceptible d'être étendue spatialement. Nous détectons des régions d'émission véritablement étendue autour de quatre des six sources avec une détection en radio et autour d'une seule des cinq sans détection radio. Nous estimons qu'il y a moins de gaz ionisé dans ces sources que dans notre échantillon de radio-galaxies (avec Mion gas ~ 10^7 - 10^8 Msun) et la cinématique de ce gaz est aussi plus calme, similaire à ce qui est observé autour de certains quasars proches. Enfin, de nouvelles observations de deux radio-galaxies particulières nous ont révélé que l'une d'entre elles est entourée de quatorze galaxies-companions et qu'elle se trouve donc dans une partie sur-dense de l'Univers. Nous expliquons donc la morphologie inhabituelle du gaz ionisé présent autour de ces deux radio-galaxies par des cycles répétés d'activité du NAG, en analogie à ce qui est observé dans les amas de galaxies proches, qui sont d'excellents exemples de rétroaction du NAG dans l'Univers local. / There is growing evidence that supermassive black holes may play a crucial role for galaxy evolution, in particular during the formation of massive galaxies at high redshift (z ~ 2 - 3). Our work focuses on quantifying the effects of jets of radiogalaxies and of large bolometric luminosities of quasars on the interstellar gas in their host galaxies. To this end, we studied the kinematics of the ionized gas in 12 moderately powerful radio galaxies and 11 quasars (6 radio-loud and 5 radio-quiet) at high redshifts with rest-frame optical imaging spectroscopy obtained at the VLT with SINFONI. We searched for outflows and other signatures of feedback from the supermassive black holes in the centers of these galaxies to evaluate if the AGN may plausibly quench star formation. In our sample of moderately powerful radiogalaxies, we observe velocity dispersions nearly as large as those observed in the most powerful ones (with FWHM ~ 1000 km/s), but the quantity of ionized gas is decreased by one order of magnitude (Mion gas ~ 10^8 - 10^9 Msun) and velocity gradients tend to be less dramatic (Δv < 400 km/s), when they are observed. In our sample of quasars, we had to carefully subtract the broad spectral component of emission lines to have access to its narrow, and spatially extended, component. We detect truly extended emission line regions in 4/6 sources of our radio-loud subsample and in 1/5 source of our radio-quiet subsample. We estimate that masses of ionized gas in these sources are smaller than in our sample of high-redshift radiogalaxies (with Mion gas ~ 10^7 - 10^8 Msun) and kinematics tend to be more quiescent, akin to what is observed in local quasars. Finally, detailed observations of two outliers among our sample of high-redshift radiogalaxies revealed that one of them is closely surrounded by 14 companions galaxies, hence lying in an overdensity. We therefore interpret the presence and morphology of ionized gas around these galaxies as evidence for repeated cycles ouf AGN outbursts, akin to what can be observed in local clusters of galaxies, which are prime examples of AGN feedback in the nearby Universe.

There is growing evidence that supermassive black holes may play a crucial role for galaxy evolution, in particular during the formation of massive galaxies at high redshift (z ~ 2 - 3). Our work focuses on quantifying the effects of jets of radiogalaxies and of large bolometric luminosities of quasars on the interstellar gas in their host galaxies. To this end, we studied the kinematics of the ionized gas in 12 moderately powerful radio galaxies and 11 quasars (6 radio-loud and 5 radio-quiet) at high redshifts with rest-frame optical imaging spectroscopy obtained at the VLT with SINFONI. We searched for outflows and other signatures of feedback from the supermassive black holes in the centers of these galaxies to evaluate if the AGN may plausibly quench star formation. In our sample of moderately powerful radiogalaxies, we observe velocity dispersions nearly as large as those observed in the most powerful ones (with FWHM ~ 1000 km/s), but the quantity of ionized gas is decreased by one order of magnitude (Mion gas ~ 10^8 - 10^9 Msun) and velocity gradients tend to be less dramatic (Δv < 400 km/s), when they are observed. In our sample of quasars, we had to carefully subtract the broad spectral component of emission lines to have access to its narrow, and spatially extended, component. We detect truly extended emission line regions in 4/6 sources of our radio-loud subsample and in 1/5 source of our radio-quiet subsample. We estimate that masses of ionized gas in these sources are smaller than in our sample of high-redshift radiogalaxies (with Mion gas ~ 10^7 - 10^8 Msun) and kinematics tend to be more quiescent, akin to what is observed in local quasars. Finally, detailed observations of two outliers among our sample of high-redshift radiogalaxies revealed that one of them is closely surrounded by 14 companions galaxies, hence lying in an overdensity. We therefore interpret the presence and morphology of ionized gas around these galaxies as evidence for repeated cycles ouf AGN outbursts, akin to what can be observed in local clusters of galaxies, which are prime examples of AGN feedback in the nearby Universe.