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  • 1
    Online Resource
    Online Resource
    Oxford University Press (OUP) ; 2017
    In:  Monthly Notices of the Royal Astronomical Society Vol. 472, No. 1 ( 2017-11), p. 1163-1181
    In: Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP), Vol. 472, No. 1 ( 2017-11), p. 1163-1181
    Type of Medium: Online Resource
    ISSN: 0035-8711 , 1365-2966
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2017
    detail.hit.zdb_id: 2016084-7
    SSG: 16,12
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  • 2
    In: Astronomy & Astrophysics, EDP Sciences, Vol. 652 ( 2021-08), p. A44-
    Abstract: Context. Feedback processes play a fundamental role in the regulation of the star formation (SF) activity in galaxies and, in particular, in the quenching of early-type galaxies (ETGs) as has been inferred by observational and numerical studies of Λ-CDM models. At z  = 0, ETGs exhibit well-known fundamental scaling relations, but the connection between scaling relations and the physical processes shaping ETG evolution remains unknown. Aims. This work aims to study the impact of the energetic feedback due to active galactic nuclei (AGN) on the formation and evolution of ETGs. We focus on assessing the impact of AGN feedback on the evolution of the mass–plane and the fundamental plane (FP; defined using mass surface density) as well as on morphology, kinematics, and stellar age across the FP. Methods. The Horizon-AGN and Horizon-noAGN cosmological hydrodynamical simulations were performed with identical initial conditions, including the same physical processes except for the activation of the AGN feedback in the former. We selected a sample of central ETGs from both simulations using the same criteria and exhaustively studied their SF activity, kinematics, and scaling relations for z  ≤ 3. Results. We find that Horizon-AGN ETGs identified at z  = 0 follow the observed fundamental scaling relations (mass–plane, FP, and mass–size relation) and qualitatively reproduce kinematic features albeit conserving a rotational inner component with a mass fraction regulated by the AGN feedback. We discover that AGN feedback seems to be required to reproduce the bimodality in the spin parameter distribution reported by observational works and the mass–size relation; more massive galaxies have older stellar populations, larger sizes, and are slower rotators. We study the evolution of the fundamental relations with redshift, finding a mild evolution of the mass–plane of Horizon-AGN ETGs for z   〈  1, whereas a stronger change is detected for z   〉  1. The ETGs in Horizon-noAGN show a strong systematic redshift evolution of the mass–plane. The FP of Horizon-AGN ETGs agrees with observations at z  = 0. When AGN feedback is switched off, a fraction of galaxies depart from the expected FP at all analysed redshifts owing to the presence of a few extended galaxies with an excess of stellar surface density. We find that AGN feedback regulates the SF activity as a function of stellar mass and redshift being able to reproduce the observed relations. Our results show the impact of AGN feedback on the mass-to-light ratio ( M / L ) and its relation with the tilt of the luminosity FP (L-FP; defined using the averaged surface brightness). Overall, AGN feedback has an impact on the regulation of the SF activity, size, stellar surface density, stellar ages, rotation, and masses of ETGs that is reflected on the fundamental relations, particularly on the FP. We detect a dependence of the FP on stellar age and galaxy morphology that evolves with redshfit. The characteristics of the galaxy distribution on the FP according to these properties change drastically by z  ∼ 1 in Horizon-AGN and hence this feature could provide further insight into the action of AGN feedback.
    Type of Medium: Online Resource
    ISSN: 0004-6361 , 1432-0746
    RVK:
    RVK:
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2021
    detail.hit.zdb_id: 1458466-9
    SSG: 16,12
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  • 3
    In: Astronomy & Astrophysics, EDP Sciences, Vol. 653 ( 2021-09), p. A82-
    Abstract: We present a bright galaxy sample with accurate and precise photometric redshifts (photo- z s), selected using ugriZYJHK s photometry from the Kilo-Degree Survey (KiDS) Data Release 4. The highly pure and complete dataset is flux-limited at r   〈  20 mag, covers ∼1000 deg 2 , and contains about 1 million galaxies after artifact masking. We exploit the overlap with Galaxy And Mass Assembly spectroscopy as calibration to determine photo- z s with the supervised machine learning neural network algorithm implemented in the ANNz2 software. The photo- z s have a mean error of |⟨ δz ⟩|∼5 × 10 −4 and low scatter (scaled mean absolute deviation of ∼0.018(1 +  z )); they are both practically independent of the r -band magnitude and photo- z at 0.05  〈   z phot   〈  0.5. Combined with the 9-band photometry, these allow us to estimate robust absolute magnitudes and stellar masses for the full sample. As a demonstration of the usefulness of these data, we split the dataset into red and blue galaxies, used them as lenses, and measured the weak gravitational lensing signal around them for five stellar mass bins. We fit a halo model to these high-precision measurements to constrain the stellar-mass–halo-mass relations for blue and red galaxies. We find that for high stellar mass ( M ⋆   〉  5 × 10 11   M ⊙ ), the red galaxies occupy dark matter halos that are much more massive than those occupied by blue galaxies with the same stellar mass.
    Type of Medium: Online Resource
    ISSN: 0004-6361 , 1432-0746
    RVK:
    RVK:
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2021
    detail.hit.zdb_id: 1458466-9
    SSG: 16,12
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  • 4
    In: Astronomy & Astrophysics, EDP Sciences, Vol. 638 ( 2020-06), p. L1-
    Abstract: We present a combined tomographic weak gravitational lensing analysis of the Kilo Degree Survey (KV450) and the Dark Energy Survey (DES-Y1). We homogenize the analysis of these two public cosmic shear datasets by adopting consistent priors and modeling of nonlinear scales, and determine new redshift distributions for DES-Y1 based on deep public spectroscopic surveys. Adopting these revised redshifts results in a 0.8 σ reduction in the DES-inferred value for S ​ 8 , which decreases to a 0.5 σ reduction when including a systematic redshift calibration error model from mock DES data based on the MICE2 simulation. The combined KV450+DES-Y1 constraint on S 8 = 0.762 −0.024 +0.025 is in tension with the Planck 2018 constraint from the cosmic microwave background at the level of 2.5 σ . This result highlights the importance of developing methods to provide accurate redshift calibration for current and future weak-lensing surveys.
    Type of Medium: Online Resource
    ISSN: 0004-6361 , 1432-0746
    RVK:
    RVK:
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2020
    detail.hit.zdb_id: 1458466-9
    SSG: 16,12
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  • 5
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2011
    In:  Experiments in Fluids Vol. 50, No. 2 ( 2011-2), p. 397-406
    In: Experiments in Fluids, Springer Science and Business Media LLC, Vol. 50, No. 2 ( 2011-2), p. 397-406
    Type of Medium: Online Resource
    ISSN: 0723-4864 , 1432-1114
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2011
    detail.hit.zdb_id: 710083-8
    detail.hit.zdb_id: 1476361-8
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  • 6
    Online Resource
    Online Resource
    EDP Sciences ; 2018
    In:  Astronomy & Astrophysics Vol. 613 ( 2018-5), p. A4-
    In: Astronomy & Astrophysics, EDP Sciences, Vol. 613 ( 2018-5), p. A4-
    Abstract: Context. The anisotropic distribution of satellites around the central galaxy of their host halo is both well-documented in observations and predicted by the ΛCDM model. However its amplitude, direction and possible biases associated to the specific dynamics of such satellite galaxies are still highly debated. Aims. Using the cosmological hydrodynamics simulation Horizon-AGN, we aim to quantify the anisotropy of the spatial distribution of satellite galaxies relative to their central counterpart and explore its connexion to the local cosmic web, in the redshift range between 0.3 and 0.8. Methods. Haloes and galaxies were identified and their kinematics computed using their dark matter and stellar particles respectively. Sub-haloes were discarded and galaxies lying within 5 R vir of a given halo are matched to it. The filamentary structure of the cosmic web was extracted from the density field – smoothed over a 3 h −1 Mpc typical scale – as a network of contiguous segments. We then investigated the distribution function of relevant angles, most importantly the angle α between the central-to-satellite separation vector and the group’s nearest filament, aside with the angle between this same separation and the central minor axis. This allowed us to explore the correlations between filamentary infall, intra-cluster inspiralling and the resulting distribution of satellites around their central counterpart. Results. We find that, on average, satellites tend to be located on the galactic plane of the central object. This effect is detected for central galaxies with a stellar mass larger than 10 10 M ⊙ and found to be strongest for red passive galaxies, while blue galaxies exhibit a weaker trend. For galaxies with a minor axis parallel to the direction of the nearest filament, we find that the coplanarity is stronger in the vicinity of the central galaxy, and decreases when moving towards the outskirts of the host halo. By contrast, the spatial distribution of satellite galaxies relative to their closest filament follows the opposite trend: their tendency to align with them dominates at large distances from the central galaxy, and fades away in its vicinity. In that redshift range, we find hints that massive red centrals with a spin perpendicular to their filament also have corotating satellites well aligned with both the galactic plane and the filament. On the other hand, lower-mass blue centrals with a spin parallel to their filament have satellites flowing straight along this filament, and hence orthogonally to their galactic plane. The orbit of these satellites is then progressively bent towards a better alignment with the galactic plane as they penetrate the central region of their host halo. Conclusions. The kinematics previously described are consistent with satellite infall and spin build-up via quasi-polar flows, followed by a re-orientation of the spin of massive red galaxies through mergers.
    Type of Medium: Online Resource
    ISSN: 0004-6361 , 1432-0746
    RVK:
    RVK:
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2018
    detail.hit.zdb_id: 1458466-9
    SSG: 16,12
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  • 7
    In: Astronomy & Astrophysics, EDP Sciences, Vol. 626 ( 2019-06), p. A72-
    Abstract: Context . Accurate model predictions including the physics of baryons are required to make the most of the upcoming large cosmological surveys devoted to gravitational lensing. The advent of hydrodynamical cosmological simulations enables such predictions on sufficiently sizeable volumes. Aims . Lensing quantities (deflection, shear, convergence) and their statistics (convergence power spectrum, shear correlation functions, galaxy-galaxy lensing) are computed in the past lightcone built in the Horizon-AGN hydrodynamical cosmological simulation, which implements our best knowledge on baryonic physics at the galaxy scale in order to mimic galaxy populations over cosmic time. Methods . Lensing quantities are generated over a one square degree field of view by performing multiple-lens plane ray-tracing through the lightcone, taking full advantage of the 1 kpc resolution and splitting the line of sight over 500 planes all the way to redshift z  ∼ 7. Two methods are explored (standard projection of particles with adaptive smoothing, and integration of the acceleration field) to ensure a good implementation. The focus is on small scales where baryons matter most. Results . Standard cosmic shear statistics are affected at the 10% level by the baryonic component for angular scales below a few arcminutes. The galaxy-galaxy lensing signal, or galaxy-shear correlation function, is consistent with measurements for the redshift z  ∼ 0.5 massive galaxy population. At higher redshift z  ≳ 1, the effect of magnification bias on this correlation is relevant for separations greater than 1 Mpc. Conclusions . This work is pivotal for all current and upcoming weak-lensing surveys and represents a first step towards building a full end-to-end generation of lensed mock images from large cosmological hydrodynamical simulations.
    Type of Medium: Online Resource
    ISSN: 0004-6361 , 1432-0746
    RVK:
    RVK:
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2019
    detail.hit.zdb_id: 1458466-9
    SSG: 16,12
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  • 8
    Online Resource
    Online Resource
    EDP Sciences ; 2011
    In:  Astronomy & Astrophysics Vol. 526 ( 2011-2), p. A15-
    In: Astronomy & Astrophysics, EDP Sciences, Vol. 526 ( 2011-2), p. A15-
    Type of Medium: Online Resource
    ISSN: 0004-6361 , 1432-0746
    RVK:
    RVK:
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2011
    detail.hit.zdb_id: 1458466-9
    SSG: 16,12
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  • 9
    Online Resource
    Online Resource
    Oxford University Press (OUP) ; 2017
    In:  Monthly Notices of the Royal Astronomical Society Vol. 472, No. 1 ( 2017-11-21), p. 949-965
    In: Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP), Vol. 472, No. 1 ( 2017-11-21), p. 949-965
    Abstract: The observed massive end of the galaxy stellar mass function is steeper than its predicted dark matter halo counterpart in the standard Λ cold dark matter paradigm. In this paper, we investigate the impact of active galactic nuclei (AGN) feedback on star formation in massive galaxies. We isolate the impact of AGN by comparing two simulations from the HORIZON suite, which are identical except that one also includes supermassive black holes (SMBHs) and related feedback models. This allows us to cross-identify individual galaxies between simulations and quantify the effect of AGN feedback on their properties, including stellar mass and gas outflows. We find that massive galaxies (M* ≥ 1011 M⊙) are quenched by AGN feedback to the extent that their stellar masses decrease by up to 80 per cent at z = 0. SMBHs affect their host halo through a combination of outflows that reduce their baryonic mass, particularly for galaxies in the mass range 109 M⊙ ≤ M* ≤ 1011 M⊙, and a disruption of central gas inflows, which limits in situ star formation. As a result, net gas inflows on to massive galaxies, M* ≥ 1011 M⊙, drop by up to 70 per cent. We measure a redshift evolution in the stellar mass ratio of twin galaxies with and without AGN feedback, with galaxies of a given stellar mass showing stronger signs of quenching earlier on. This evolution is driven by a progressive flattening of the MSMBH–M* relation with redshift, particularly for galaxies with M* ≤ 1010 M⊙. MSMBH/M* ratios decrease over time, as falling average gas densities in galaxies curb SMBH growth.
    Type of Medium: Online Resource
    ISSN: 0035-8711 , 1365-2966
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2017
    detail.hit.zdb_id: 2016084-7
    SSG: 16,12
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  • 10
    Online Resource
    Online Resource
    Oxford University Press (OUP) ; 2022
    In:  Monthly Notices of the Royal Astronomical Society Vol. 515, No. 3 ( 2022-08-08), p. 3603-3631
    In: Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP), Vol. 515, No. 3 ( 2022-08-08), p. 3603-3631
    Abstract: The high abundance of disc galaxies without a large central bulge challenges predictions of current hydrodynamic simulations of galaxy formation. We aim to shed light on the formation of these objects by studying the redshift and mass dependence of their intrinsic 3D shape distributions in the COSMOS galaxy survey below redshift z = 1.0. This distribution is inferred from the observed distribution of 2D shapes, using a reconstruction method which we test using hydrodynamic simulations. Our tests reveal a moderate bias for the inferred average disc circularity and relative thickness, but a large bias on the dispersion of these quantities. Applying the reconstruction method on COSMOS data, we find variations of the average disc circularity and relative thickness with redshift of around ∼1 per cent and ∼10 per cent, respectively, which is comparable to the error estimates on these quantities. The average relative disc thickness shows a significant mass dependence which can be accounted for by the scaling of disc radius with galaxy mass. We conclude that our data provides no evidence for a strong dependence of the average circularity and absolute thickness of disc-dominated galaxies on redshift and mass that is significant with respect to the statistical uncertainties in our analysis. These findings are expected in the absence of disruptive merging or feedback events that would affect galaxy shapes. They hence support a scenario where present-day discs form early ( z & gt; 1.0) and subsequently undergo a tranquil evolution in isolation. However, more data and a better understanding of systematics are needed to reaffirm our results.
    Type of Medium: Online Resource
    ISSN: 0035-8711 , 1365-2966
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2022
    detail.hit.zdb_id: 2016084-7
    SSG: 16,12
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