ORCID Profile
0000-0003-4221-6718
Current Organisation
Utrecht University
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Publisher: The Open Journal
Date: 26-06-2019
Publisher: Oxford University Press (OUP)
Date: 25-07-2023
Abstract: Using Herschel-SPIRE imaging and the Canada-France Imaging Survey (CFIS) Low Surface Brightness data products from the Ultraviolet Near-Infrared Optical Northern Survey (UNIONS), we present a cross-correlation between the cosmic far-infrared background and cosmic optical background fluctuations. The cross-spectrum is measured for two cases: all galaxies are kept in the images or all in idually detected galaxies are masked to produce ‘background’ maps. We report the detection of the cross-correlation signal at $\\gtrsim 18\\, \\sigma$ ($\\gtrsim 14\\, \\sigma$ for the background map). The part of the optical brightness variations that are correlated with the submm emission translates to an rms brightness of $\\simeq 32.5\\, {\\rm mag}\\, {\\rm arcsec}^{-2}$ in the r band, a level normally unreachable for in idual sources. A critical issue is determining what fraction of the cross-power spectrum might be caused by emission from Galactic cirrus. For one of the fields, the Galactic contamination is 10 times higher than the extragalactic signal however, for the other fields, the contamination is around 20 per cent. An additional discriminant is that the cross-power spectrum is of the approximate form P(k) ∝ 1/k, much shallower than that of Galactic cirrus. We interpret the results in a halo-model framework, which shows good agreement with independent measurements for the scalings of star-formation rates in galaxies. The approach presented in this study holds great promise for future surveys such as FYST/CCAT-prime combined with Euclid or the Vera Rubin Observatory (LSST), which will enable a detailed exploration of the evolution of star formation in galaxies.
Publisher: EDP Sciences
Date: 07-2023
DOI: 10.1051/0004-6361/202245158
Abstract: We present constraints on the flat Λ cold dark matter cosmological model through a joint analysis of galaxy abundance, galaxy clustering, and galaxy-galaxy lensing observables with the Kilo-Degree Survey. Our theoretical model combines a flexible conditional stellar mass function, which describes the galaxy-halo connection, with a cosmological N -body simulation-calibrated halo model, which describes the non-linear matter field. Our magnitude-limited bright galaxy s le combines nine-band optical-to-near-infrared photometry with an extensive and complete spectroscopic training s le to provide accurate redshift and stellar mass estimates. Our faint galaxy s le provides a background of accurately calibrated lensing measurements. We constrain the structure growth parameter to S 8 = σ 8 √Ω m /0.3 =√0.773 −0.030 +0.028 and the matter density parameter to Ω m = 0.290 −0.017 +0.021 . The galaxy-halo connection model adopted in the work is shown to be in agreement with previous studies. Our constraints on cosmological parameters are comparable to, and consistent with, joint ‘3 × 2pt’ clustering-lensing analyses that additionally include a cosmic shear observable. This analysis therefore brings attention to the significant constraining power in the often excluded non-linear scales for galaxy clustering and galaxy-galaxy lensing observables. By adopting a theoretical model that accounts for non-linear halo bias, halo exclusion, scale-dependent galaxy bias, and the impact of baryon feedback, this work demonstrates the potential for, and a way towards, including non-linear scales in cosmological analyses. Varying the width of the satellite galaxy distribution with an additional parameter yields a strong preference for sub-Poissonian variance, improving the goodness of fit by 0.18 in terms of the reduced χ 2 value (and increasing the p -value by 0.25) compared to a fixed Poisson distribution.
Publisher: Oxford University Press (OUP)
Date: 09-2020
Abstract: We use KiDS weak lensing data to measure variations in mean halo mass as a function of several key galaxy properties (namely stellar colour, specific star formation rate, Sérsic index, and effective radius) for a volume-limited s le of GAMA galaxies in a narrow stellar mass range [M* ∼ (2–5) × 1010 M⊙]. This mass range is particularly interesting, inasmuch as it is where bimodalities in galaxy properties are most pronounced, and near to the break in both the galaxy stellar mass function and the stellar-to-halo mass relation (SHMR). In this narrow mass range, we find that both size and Sérsic index are better predictors of halo mass than either colour or SSFR, with the data showing a slight preference for Sérsic index. In other words, we find that mean halo mass is more tightly correlated with galaxy structure than either past star formation history or current star formation rate. Our results lead to an approximate lower bound on the dispersion in halo masses among log M* ≈ 10.5 galaxies: We find that the dispersion is ≳0.3 dex. This would imply either that offsets from the mean SHMR are closely coupled to size/structure or that the dispersion in the SHMR is larger than what past results have suggested. Our results thus provide new empirical constraints on the relationship between stellar and halo mass assembly at this particularly interesting mass range.
Publisher: Oxford University Press (OUP)
Date: 08-05-2019
Publisher: Oxford University Press (OUP)
Date: 21-07-2017
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 in idual 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.
Publisher: EDP Sciences
Date: 09-2021
DOI: 10.1051/0004-6361/202140352
Abstract: We present a bright galaxy s le 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 s le. 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.
Publisher: Oxford University Press (OUP)
Date: 04-07-2017
Publisher: EDP Sciences
Date: 05-2018
DOI: 10.1051/0004-6361/201629007
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 litude, 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.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Nora Chisari.