Galaxy formation and evolution

Abstract:

Over the past two decades, tight correlations between black hole masses (M•) and their host galaxy properties have been firmly established for massive galaxies (with stellar mass log(M*/M⊙)≳10 ) at low-z (z < 1), indicating coevolution of supermassive black holes and galaxies. However, the situation at high-z, especially beyond cosmic noon (z ≳ 2.5), is controversial. With a combination of JWST Near Infrared Camera (NIRCam)/wide field slitless spectroscopy (WFSS) from FRESCO, CONGRESS and deep multiband NIRCam/image data from JADES in the GOODS fields, we study the black-hole-to-galaxy mass relation at z ∼ 1–4. After identifying 18 broad-line active galactic nuclei (AGNs) at 1 < z < 4 (with 8 at z > 2.5) from the WFSS data, we measure their black hole masses based on broad near-infrared lines (Paα, Paβ, and He i λ10833 Å), and constrain their stellar masses from AGN-galaxy image decomposition or spectral energy distribution decomposition. Taking account of the observational biases, the intrinsic scatter of the M•−M* relation, and the errors in mass measurements, we find no significant difference in the M•/M* ratio for 2.5 < z < 4 compared to that at lower redshifts (1 < z < 2.5), suggesting no evolution of the M•−M* relation at log(M*/M⊙)≳10 up to z ∼ 4.

Abstract:

The morphology of a galaxy reflects the mix of physical processes occurring within and around it, offering indirect clues to its formation and evolution. We apply both visual classification and computer vision to test the suspected connection between galaxy mergers and active galactic nucleus (AGN) activity, as evidenced by a close/merging galaxy pair, or tidal features surrounding an apparently singular system. We use JADES JWST/NIRCam imagery of a complete, multiwavelength AGN sample recently expanded with JWST/Mid-Infrared Instrument (MIRI) photometry. This 0.9–25 μm data set enables constraints on the host-galaxy morphologies of a broad range of AGN beyond z ∼ 1, including heavily obscured examples missing from previous studies. Our primary AGN sample consists of 243 lightly to highly obscured X-ray-selected AGN and 138 presumed Compton-thick, mid-infrared-bright/X-ray-faint AGN revealed by MIRI. Utilizing the shape asymmetry morphology indicator, AS, as the metric for disturbance, we find that 88% of the Seyferts sampled are strongly spatially disturbed (AS > 0.2). The experimental design we employ reveals a ≳3σ obscuration–merger (NH–AS) correlation at 0.6 < z < 2.4, and also recovers a physical distinction between the X-ray- and mid-IR-detected AGN suggestive of their link to a common evolutionary scenario. Placing the observed pattern of disturbances in the context of the other average host-galaxy properties, we conclude that mergers are common among obscured AGN. This finding presents tension with the leading model on AGN fueling that requires Seyfert AGN with subquasar luminosities (Lbol < 1045 erg s−1) to evolve only through nonmerger mechanisms.