ORCID Profile
0000-0002-5031-3721
Current Organisation
The University of Edinburgh
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Publisher: Oxford University Press (OUP)
Date: 17-01-2019
DOI: 10.1093/MNRAS/STZ189
Publisher: Oxford University Press (OUP)
Date: 24-08-2018
Publisher: EDP Sciences
Date: 06-2021
DOI: 10.1051/0004-6361/202040108
Abstract: We present measurements of the radial gravitational acceleration around isolated galaxies, comparing the expected gravitational acceleration given the baryonic matter ( g bar ) with the observed gravitational acceleration ( g obs ), using weak lensing measurements from the fourth data release of the Kilo-Degree Survey (KiDS-1000). These measurements extend the radial acceleration relation (RAR), traditionally measured using galaxy rotation curves, by 2 decades in g obs into the low-acceleration regime beyond the outskirts of the observable galaxy. We compare our RAR measurements to the predictions of two modified gravity (MG) theories: modified Newtonian dynamics and Verlinde’s emergent gravity (EG). We find that the measured relation between g obs and g bar agrees well with the MG predictions. In addition, we find a difference of at least 6 σ between the RARs of early- and late-type galaxies (split by Sérsic index and u − r colour) with the same stellar mass. Current MG theories involve a gravity modification that is independent of other galaxy properties, which would be unable to explain this behaviour, although the EG theory is still limited to spherically symmetric static mass models. The difference might be explained if only the early-type galaxies have significant ( M gas ≈ M ⋆ ) circumgalactic gaseous haloes. The observed behaviour is also expected in Λ-cold dark matter (ΛCDM) models where the galaxy-to-halo mass relation depends on the galaxy formation history. We find that MICE, a ΛCDM simulation with hybrid halo occupation distribution modelling and abundance matching, reproduces the observed RAR but significantly differs from BAHAMAS, a hydrodynamical cosmological galaxy formation simulation. Our results are sensitive to the amount of circumgalactic gas current observational constraints indicate that the resulting corrections are likely moderate. Measurements of the lensing RAR with future cosmological surveys (such as Euclid) will be able to further distinguish between MG and ΛCDM models if systematic uncertainties in the baryonic mass distribution around galaxies are reduced.
Publisher: Oxford University Press (OUP)
Date: 02-03-2022
Abstract: In Galaxy And Mass Assembly Data Release 4 (GAMA DR4), we make available our full spectroscopic redshift s le. This includes 248 682 galaxy spectra, and, in combination with earlier surveys, results in 330 542 redshifts across five sky regions covering ∼250 deg2. The redshift density, is the highest available over such a sustained area, has exceptionally high completeness (95 per cent to rKiDS = 19.65 mag), and is well-suited for the study of galaxy mergers, galaxy groups, and the low redshift (z & 0.25) galaxy population. DR4 includes 32 value-added tables or Data Management Units (DMUs) that provide a number of measured and derived data products including GALEX, ESO KiDS, ESO VIKING, WISE, and HerschelSpace Observatory imaging. Within this release, we provide visual morphologies for 15 330 galaxies to z & 0.08, photometric redshift estimates for all 18 million objects to rKiDS ∼ 25 mag, and stellar velocity dispersions for 111 830 galaxies. We conclude by deriving the total galaxy stellar mass function (GSMF) and its sub- ision by morphological class (elliptical, compact-bulge and disc, diffuse-bulge and disc, and disc only). This extends our previous measurement of the total GSMF down to 106.75 M$_{\\odot } \\, h_{70}^{-2}$ and we find a total stellar mass density of ρ* = (2.97 ± 0.04) × 108 M$_{\\odot } \\, h_{70}$ Mpc−3 or $\\Omega _*=(2.17 \\pm 0.03) \\times 10^{-3} \\, h_{70}^{-1}$. We conclude that at z & 0.1, the Universe has converted 4.9 ± 0.1 per cent of the baryonic mass implied by big bang Nucleosynthesis into stars that are gravitationally bound within the galaxy population.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Benjamin Giblin.