Galaxy formation and evolution

Abstract:

James Webb Space Telescope (JWST) has revealed a large population of active galactic nuclei (AGNs) in the distant Universe, which are challenging our understanding of early massive black hole (BH) seeding and growth. We expand the exploration of this population to lower luminosities by stacking 600 NIRSpec grating spectra from the JWST Advanced Deep Extragalactic Survey (JADES) at , in bins of redshift, [O iii]5007 luminosity and equivalent width, UV luminosity, and stellar mass. In multiple stacks, we detect a broad component of H without a counterpart in [O iii], implying that it is not due to outflows but traces the broad-line region of a large population of low-luminosity AGNs not detected in individual spectra. The detection, in some stacks, of high [O iii]4363/H , typical of AGNs, further confirms the detection of a large population of AGNs. We infer that the stacks probe BHs with masses of a few times accreting at rates 0.02–0.1, i.e. a low-mass and dormant parameter space poorly explored by previous studies on individual targets. We identify populations of BHs that fall within the scatter of the local scaling relation, indicating that there is a population of high-z BHs that are not overmassive relative to their host galaxies. Yet, on average, the stacks are still overmassive relative the local relation, with some of them 1–2 dex above it. We infer that the BH mass function at is consistent with models in which BHs evolve through short bursts of super-Eddington accretion.

Abstract:

We present a systematic statistical analysis of an informal astrophysical phenomenon known as Renzo’s rule (or Sancisi’s law), which states that ‘for any feature in a galaxy’s luminosity profile, there is a corresponding feature in the rotation curve, and vice versa’. This is often posed as a challenge for the standard Λ cold dark matter (CDM) model while supporting alternative theories such as modified Newtonian dynamics (MOND). Indeed, we identify clear features in the dwarf spiral NGC 1560 – a prime example for Renzo’s rule – and find correlation statistics which support Renzo’s rule with a slight preference for MOND over CDM halo fits. However, a broader analysis on galaxies in the Spitzer Photometry & Accurate Rotation Curves (SPARC) data base reveals an excess of features in rotation curves that lack clear baryonic counterparts, with correlation statistics deviating up to on average from that predicted by both MOND and CDM haloes, challenging the validity of Renzo’s rule. Thus we do not find clear evidence for Renzo’s rule in present galaxy data overall. We additionally perform mock tests, which show that a definitive test of Renzo’s rule is primarily limited by the lack of clearly resolved baryonic features in current galaxy data.

Abstract:

Abstract We use deep NIRCam and MIRI imaging from the JWST PRIMER survey to study the properties of ALMA detected (sub)mm sources in the COSMOS field, with the aim of defining the cosmic history of dust-enshrouded star formation. The wealth of ALMA data in this field enabled us to isolate a robust sample of 128 (sub)mm sources within the 175 arcmin2 PRIMER COSMOS survey footprint, spanning two decades in (sub)mm flux density. The JWST imaging is deep and red enough to reveal secure galaxy counterparts for all of these sources. This 100% identification completeness is accompanied by a high level of redshift completeness: 52% of the sources have spectroscopic redshifts, and this has enabled us to refine the photometric redshifts for the remaining galaxies. Armed with robust redshift information, we calculate the star-formation rates (SFR) and stellar masses (M*) of all 128 ALMA-detected galaxies, and place them in the context of other galaxies in the field. We find that the vast majority of star formation is dust-enshrouded in all of the ALMA-detected galaxies, with SFR ranging from ≃ 1000 M⊙ yr−1 down to ≃ 20 M⊙ yr−1. We also find that virtually all (126/128) have high stellar masses, M* > 1010 M⊙, independent of redshift. The unusually high quality of our sample enables us to make a robust estimate of the contribution of the ALMA-detected galaxies to cosmic star-formation rate density, ρSFR. The existing ALMA imaging only covers <20% of the PRIMER COSMOS area, but based on our knowledge of all other massive galaxies in the field, we produce a completeness-corrected estimate of dust-enshrouded ρSFR. This confirms that UV-visible star formation dominates ρSFR at z > 4, but also indicates that dust-enshrouded star formation still makes a contribution of ≃ 20% at z ≃ 8, and ≃ 5% at z ≃ 10.