Galaxy formation and evolution

Abstract:

We derive circular velocity curves (CVCs) from stellar dynamical models for ∼6000 nearby galaxies in the final data release of the Sloan Digital Sky Survey-IV MaNGA survey with integral-field spectroscopy, exploring connections between the inner gravitational potential (traced by CVC amplitude/shape) and galaxy properties. The maximum circular velocity ( Vcircmax ) and circular velocity at the half-light radius ( Vcirc(Remaj) ) both scale linearly with the stellar second velocity moment σe2≡〈V2+σ2〉 within the half-light isophote, following Vcircmax≈1.72σe (7% error) and Vcirc(Remaj)≈1.62σe (7% error). CVC shapes (rising, flat, declining) correlate strongly with structural and stellar population properties: declining curves dominate in massive, early-type, bulge-dominated galaxies with old, metal-rich stars and early quenching, while rising CVCs prevail in disk-dominated systems with younger stellar populations and ongoing star formation. Using a unified bulge–disk–halo model, we predict CVC shapes with minimal bias, identifying three governing parameters: bulge-to-total mass ratio (B/T), dark matter fraction within Re, and bulge Sérsic index. The distribution of CVC shapes across the mass–size plane reflects evolutionary pathways driven by (i) in situ star formation (spurring bulge growth) and (ii) dry mergers. This establishes CVC morphology as a diagnostic for galaxy evolution, linking dynamical signatures to structural and stellar population histories.

Abstract:

Abstract Black hole (BH) superradiance can provide strong constraints on the properties of ultralight bosons (ULBs). While most of the previous work has focused on the theoretical predictions, here we investigate the most suitable statistical framework to constrain ULB masses and self-interactions using BH spin measurements. We argue that a Bayesian approach based on a simple timescales analysis provides a clear statistical interpretation, deals with limitations regarding the reproducibility of existing BH analyses, incorporates the full information from BH data, and allows us to include additional nuisance parameters or to perform hierarchical modelling with BH populations in the future. We demonstrate the feasibility of our approach using mass and spin posterior samples for the X-ray binary BH M33 X-7 and, for the first time in this context, the supermassive BH IRAS 09149-6206. We explain the differences to existing ULB constraints in the literature and illustrate the effects of various assumptions about the superradiance process (equilibrium regime vs cloud collapse, higher occupation levels). As a result, our procedure yields the most statistically rigorous ULB constraints available in the literature, with important implications for the QCD axion and axion-like particles. We encourage all groups analysing BH data to publish likelihood functions or posterior samples as supplementary material to facilitate this type of analysis, and for theory developments to compress their findings to effective timescale modifications. https://github.com/sebhoof/bhsr

Abstract:

Using the Dark Energy Survey 5-yr sample, we determine the properties of type Ia supernova (SN Ia) host galaxies across a wide multiwavelength range – from the optical to far-infrared – including data from the Herschel and Spitzer space telescopes. We categorize the SNe Ia into three distinct groups according to the distribution of their host galaxies on the star formation rate (SFR) – stellar mass () plane. Each region comprises host galaxies at distinct stages in their evolutionary pathways: Region 1 – low-mass hosts; Region 2 – high-mass, star-forming hosts and Region 3 – high-mass, passive hosts. We find SNe Ia in host galaxies located in Region 1 have the steepest slope (quantified by ) between their colours and luminosities, with . This differs at the significance level to SNe Ia in Region 3, which have the shallowest colour–luminosity slope with . After correcting SNe Ia in each subsample by their respective , events in Region 3 (high-mass, passive hosts) are mag () brighter, post-standardization. We conclude that future cosmological analyses should apply standardization relations to SNe Ia based upon the region in which the SN host galaxy lies in the SFR– plane. Alternatively, cosmological analyses should restrict the SN Ia sample to events whose host galaxies occupy a single region of this plane.

Abstract:

Supermassive black holes are prevalent at the centers of massive galaxies, and their masses scale with galaxy properties, increasing evidence suggesting that these trends continue to low stellar masses. Seeds are needed for supermassive black holes, especially at the highest redshifts explored by the James Webb Space Telescope. We study the hierarchical merging of galaxies via cosmological merger trees and argue that the seeds of supermassive black holes formed in nuclear star clusters via stellar black hole mergers at early epochs. Observable tracers include intermediate-mass black holes, nuclear star clusters, and early gas accretion in host dwarf galaxies, along with a potentially detectable stochastic gravitational-wave background, ejection of intermediate and supermassive black holes, and consequences of a significant population of early tidal disruption events and extreme mass ratio inspirals.

Abstract:

Radio continuum emission provides a unique opportunity to study star formation unbiased by dust obscuration. However, if radio observations are to be used to accurately trace star formation to high redshifts, it is crucial that the physical processes that affect the radio emission from star-forming galaxies are well understood. While inverse Compton (IC) losses from the cosmic microwave background (CMB) are negligible in the local universe, the rapid increase in the strength of the CMB energy density with redshift [] means that this effect becomes increasingly important at . Using a sample of high-redshift () Lyman-break galaxies selected in the rest-frame ultraviolet (UV), we have stacked radio observations from the MIGHTEE survey to estimate their 1.4-GHz flux densities. We find that for a given rest-frame UV magnitude, the 1.4-GHz flux density and luminosity decrease with redshift. We compare these results to the theoretical predicted effect of energy losses due to IC scattering off the CMB, and find that the observed decrease is consistent with this explanation. We discuss other possible causes for the observed decrease in radio flux density with redshift at a given UV magnitude, such as a top-heavy initial mass function at high redshift or an evolution of the dust properties, but suggest that IC scattering is the most compelling explanation.