Beecroft Institute for Particle Astrophysics and Cosmology

Abstract:

In recentwork, Lelli et al. argue that the tightness of the baryonic Tully–Fisher relation (BTFR) of the SPARC galaxy sample, and the weakness of the correlation of its residuals with effective radius, pose challenges to Λ cold dark matter cosmology. In this Letter, we calculate the statistical significance of these results in the framework of halo abundance matching, which imposes a canonical galaxy–halo connection. Taking full account of sample variance among SPARC-like realizations of the parent halo population, we find the scatter in the predicted BTFR to be 3.6σ too high, but the correlation of its residuals with galaxy size to be naturally weak. Further, we find abundance matching to generate BTFR curvature in 3.0σ disagreement with the data, and a fraction of galaxies with non-flat rotation curves somewhat larger than observed.

Abstract:

Context

The Kilo-Degree Survey (KiDS) is an ongoing optical wide-field imaging survey with the OmegaCAM camera at the VLT Survey Telescope. It aims to image 1500 square degrees in four filters (ugri). The core science driver is mapping the large-scale matter distribution in the Universe, using weak lensing shear and photometric redshift measurements. Further science cases include galaxy evolution, Milky Way structure, detection of high-redshift clusters, and finding rare sources such as strong lenses and quasars.

Aims

Here we present the third public data release and several associated data products, adding further area, homogenized photometric calibration, photometric redshifts and weak lensing shear measurements to the first two releases.

Methods

A dedicated pipeline embedded in the Astro-WISE information system is used for the production of the main release. Modifications with respect to earlier releases are described in detail. Photometric redshifts have been derived using both Bayesian template fitting, and machine-learning techniques. For the weak lensing measurements, optimized procedures based on the THELI data reduction and lensfit shear measurement packages are used.

Results

In this third data release an additional 292 new survey tiles (≈ 300 deg2) stacked ugri images are made available, accompanied by weight maps, masks, and source lists. The multi-band catalogue, including homogenized photometry and photometric redshifts, covers the combined DR1, DR2 and DR3 footprint of 440 survey tiles (447 deg2). Limiting magnitudes are typically 24.3, 25.1, 24.9, 23.8 (5σ in a 200aperture) in ugri, respectively, and the typical r-band PSF size is less than 0.700. The photometric homogenization scheme ensures accurate colors and an absolute calibration stable to ≈ 2% for gri and ≈ 3% in u. Separately released for the combined area of all KiDS releases to date are a weak lensing shear catalogue and photometric redshifts based on two different machine-learning techniques.

Abstract:

The observed massive end of the local galaxy stellar mass function is steeper than its predicted dark matter (DM) halo counterpart in the standard $\Lambda $CDM paradigm. We investigate how active galactic nuclei (AGN) feedback can account for such a reduction in the stellar content of massive galaxies, through an influence on the gas content of their interstellar (ISM) and circum-galactic medium (CGM). We isolate the impact of AGNs by comparing two simulations from the HORIZON suite, which are identical except that one includes super massive black holes (SMBH) and related feedback. This allows us to cross-identify individual galaxies between these simulations and quantify the effect of AGN feedback on their properties, such as stellar mass and gas outflows. We find that the most massive galaxies ($ \rm M_{*} \geq 3 \times 10^{11} M_\odot $) are quenched to the extent that their stellar masses decrease by about 80% at $z=0$. More generally, SMBHs affect their host halo through a combination of outflows that reduce their baryonic mass, particularly for galaxies in the mass range $ \rm 10^9 M_\odot \leq M_{*} \leq 10^{11} M_\odot $, and a disruption of central gas inflows, which limits in-situ star formation, particularly massive galaxies with $ \rm M_{*} \approx10^{11} M_\odot $. As a result of these processes, net gas inflows onto massive galaxies drop by up to 70%. Finally, 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 $\rm M_{SMBH}-M_* $ relation for galaxies with $\rm M_{*} \leq 10^{10} M_\odot $ as redshift decreases, which translates into smaller SBMHs being harboured by galaxies of any fixed stellar mass, and indicates stronger AGN feedback at higher redshift.