ABSTRACT
In this letter, we explore the quiescent lives of central galaxies using the Semi-Analytical Galaxy Evolution galaxy model and Uchuu dark matter simulation. We ask three questions: (1) How ...much of a galaxy’s life is spent in quiescence? (2) How often do galaxies transit off the main sequence? (3) What is the typical duration of a quiescent phase? We find that the low- and high-mass galaxies spend the highest fraction of their lives in quiescence: 45 ± 19 per cent for log10(Mstar) < 9.0 (3.68 ± 1.80 Gyr) and 26 ± 25 per cent for log10(Mstar) > 11.5 (3.46 ± 3.30 Gyr), falling to 7 ± 13 per cent for galaxies in-between (0.82 ± 1.57 Gyr). Low-mass galaxies move in and out of quiescence frequently, 2.8 ± 1.3 times on average, though only for short periods, 1.49 ± 1.04 Gyr. This can be traced to the influence of supernova feedback on their quite stochastic evolution. Galaxies of higher mass have fewer quiescent periods, ∼0.7 ± 0.9, and their length increases with mass, peaking at 1.97 ± 2.27 Gyr. However, our high-mass population comprises star-forming and quiescent galaxies with diverging evolutionary paths, so the actual time may be even longer. These high-mass trends are driven by radio-mode feedback from supermassive black holes, which, once active, tend to remain active for extended periods.
We analyze a suite of 33 cosmological simulations of the evolution of Milky-Way-mass galaxies in low-density environments. Our sample spans a broad range of Hubble types at z = 0, from nearly ...bulgeless disks to bulge-dominated galaxies. Despite the fact that a large fraction of the bulge is typically in place by z ~ 1, we find no significant correlation between the morphology at z = 1 and at z = 0. The z = 1 progenitors of disk galaxies span a range of morphologies, including smooth disks, unstable disks, interacting galaxies, and bulge-dominated systems. By z ~ 0.5, spiral arms and bars are largely in place and the progenitor morphology is correlated with the final morphology. We next focus on late-type galaxies with a bulge-to-total ratio (B/T) < 0.3 at z = 0. These show a correlation between B/T at z = 0 and the mass ratio of the largest merger at z < 2, as well as with the gas accretion rate at z > 1. We find that the galaxies with the lowest B/T tend to have a quiet baryon input history, with no major mergers at z < 2, and with a low and constant gas accretion rate that keeps a stable angular-momentum direction. More violent merger or gas accretion histories lead to galaxies with more prominent bulges. Most disk galaxies have a bulge Sersic index n < or =, slant 2. The galaxies with the highest bulge Sersic index tend to have histories of intense gas accretion and disk instability rather than active mergers.
ABSTRACT
We compute the bispectra of the 21cm signal during the epoch of reionization for three different reionization scenarios that are based on a dark matter N-body simulation combined with a ...self-consistent, semi-numerical model of galaxy evolution and reionization. Our reionization scenarios differ in their trends of ionizing escape fractions (fesc) with the underlying galaxy properties and cover the physically plausible range, i.e. fesc effectively decreasing, being constant, or increasing with halo mass. We find the 21 cm bispectrum to be sensitive to the resulting ionization topologies that significantly differ in their size distribution of ionized and neutral regions throughout reionization. From squeezed to stretched triangles, the 21 cm bispectra features a change of sign from negative to positive values, with ionized and neutral regions representing below-average and above-average concentrations contributing negatively and positively, respectively. The position of the change of sign provides a tracer of the size distribution of the ionized and neutral regions, and allows us to identify three major regimes that the 21 cm bispectrum undergoes during reionization. In particular the regime during the early stages of reionization, where the 21 cm bispectrum tracks the peak of the size distribution of the ionized regions, provides exciting prospects for pinning down reionization with the forthcoming Square Kilometre Array.
This paper describes a new publicly available codebase for modeling galaxy formation in a cosmological context, the "Semi-Analytic Galaxy Evolution" model, or sage for short. super(5) sage is a ...significant update to the 2006 model of Croton et al. and has been rebuilt to be modular and customizable. The model will run on any N-body simulation whose trees are organized in a supported format and contain a minimum set of basic halo properties. In this work, we present the baryonic prescriptions implemented in sage to describe the formation and evolution of galaxies, and their calibration for three N-body simulations: Millennium, Bolshoi, and GiggleZ. Updated physics include the following: gas accretion, ejection due to feedback, and reincorporation via the galactic fountain; a new gas cooling-radio mode active galactic nucleus (AGN) heating cycle; AGN feedback in the quasar mode; a new treatment of gas in satellite galaxies; and galaxy mergers, disruption, and the build-up of intra-cluster stars. Throughout, we show the results of a common default parameterization on each simulation, with a focus on the local galaxy population.
The origin of dust in galaxies across cosmic time Triani, Dian P; Sinha, Manodeep; Croton, Darren J ...
Monthly notices of the Royal Astronomical Society,
04/2020, Letnik:
493, Številka:
2
Journal Article
Recenzirano
Odprti dostop
ABSTRACT
We study the dust evolution in galaxies by implementing a detailed dust prescription in the SAGE semi-analytical model (SAM) for galaxy formation. The new model, called Dusty SAGE, follows ...the condensation of dust in the ejecta of Type II supernovae and asymptotic giant branch stars, grain growth in the dense molecular clouds, destruction by supernovae shocks, and the removal of dust from the interstellar medium (ISM) by star formation, reheating, inflows, and outflows. Our model successfully reproduces the observed dust mass function at redshift z = 0 and the observed scaling relations for dust across a wide range of redshifts. We find that the dust mass content in the present Universe is mainly produced via grain growth in the ISM. By contrast, in the early Universe, the primary production mechanism for dust is the condensation in stellar ejecta. The shift of the significant production channel for dust characterizes the scaling relations of dust-to-gas (DTG) and dust-to-metal (DTM) ratios. In galaxies where the grain growth dominates, we find positive correlations for DTG and DTM ratios with both metallicity and stellar mass. On the other hand, in galaxies where dust is produced primarily via condensation, we find negative or no correlation for DTM and DTG ratios with either metallicity or stellar mass. In agreement with observation showing that the circumgalactic medium contains more dust than the ISM, our model also shows the same trend for z < 4. Our SAM is publicly available at https://github.com/dptriani/dusty-sage.
We present a simple model of how quasars occupy dark matter haloes from z= 0 to 5 using the observed mBH–σ relation and quasar luminosity functions. This provides a way for observers to statistically ...infer host halo masses for quasar observations using luminosity and redshift alone. Our model is deliberately simple and sidesteps any need to explicitly describe the physics. In spite of its simplicity, the model reproduces many key observations and has predictive power: (i) model quasars have the correct luminosity function (by construction) and spatial clustering (by consequence); (ii) we predict high-redshift quasars of a given luminosity live in less massive dark matter haloes than the same luminosity quasars at low redshifts; (iii) we predict a factor of ∼5 more 108.5 M⊙ black holes at z∼ 2 than is currently observed; (iv) we predict a factor of ∼20 evolution in the amplitude of the mBH–Mhalo relation between z= 5 and the present day; (v) we expect luminosity-dependent quasar lifetimes of between tQ∼ 107 and 108 yr, but which may become as short as 105-6 yr for quasars brighter than L* and (vi) while little luminosity-dependent clustering evolution is expected at z≲ 1, increasingly strong evolution is predicted for L > L* quasars at higher redshifts. These last two results arise from the narrowing distribution of halo masses that quasars occupy as the Universe ages. We also deconstruct both ‘downsizing’ and ‘upsizing’ trends predicted by the model at different redshifts and space densities. Importantly, this work illustrates how current observations cannot distinguish between more complicated physically motivated quasar models and our simple phenomenological approach. It highlights the opportunities such methodologies provide.
ABSTRACT
We introduce the Uchuu suite of large high-resolution cosmological N-body simulations. The largest simulation, named Uchuu, consists of 2.1 trillion (12 8003) dark matter particles in a box ...of side-length 2.0 $\, h^{-1} \, \rm Gpc$, with particle mass of 3.27 × 108$\, h^{-1}\, \rm M_{\odot }$. The highest resolution simulation, Shin-Uchuu, consists of 262 billion (64003) particles in a box of side-length 140 $\, h^{-1} \, \rm Mpc$, with particle mass of 8.97 × 105$\, h^{-1}\, \rm M_{\odot }$. Combining these simulations, we can follow the evolution of dark matter haloes and subhaloes spanning those hosting dwarf galaxies to massive galaxy clusters across an unprecedented volume. In this first paper, we present basic statistics, dark matter power spectra, and the halo and subhalo mass functions, which demonstrate the wide dynamic range and superb statistics of the Uchuu suite. From an analysis of the evolution of the power spectra, we conclude that our simulations remain accurate from the baryon acoustic oscillation scale down to the very small. We also provide parameters of a mass–concentration model, which describes the evolution of halo concentration and reproduces our simulation data to within 5 per cent for haloes with masses spanning nearly eight orders of magnitude at redshift 0 ≤ z ≤ 14. There is an upturn in the mass–concentration relation for the population of all haloes and of relaxed haloes at z ≳ 0.5, whereas no upturn is detected at z < 0.5. We make publicly available various N-body products as part of Uchuu Data Release 1 on the Skies & Universes site.1 Future releases will include gravitational lensing maps and mock galaxy, X-ray cluster, and active galactic nucleus catalogues.
We present the new semi-analytic model of galaxy evolution, Dark Sage, a heavily modified version of the publicly available sage code. The model is designed for detailed evolution of galactic discs. ...We evolve discs in a series of annuli with fixed specific angular momentum, which allows us to make predictions for the radial and angular-momentum structure of galaxies. Most physical processes, including all channels of star formation and associated feedback, are performed in these annuli. We present the surface density profiles of our model spiral galaxies, both as a function of radius and specific angular momentum, and find that the discs naturally build a pseudo-bulge-like component. Our main results are focused on predictions relating to the integrated mass–specific angular momentum relation of stellar discs. The model produces a distinct sequence between these properties in remarkable agreement with recent observational literature. We investigate the impact Toomre disc instabilities have on shaping this sequence and find they are crucial for regulating both the mass and spin of discs. Without instabilities, high-mass discs would be systematically deficient in specific angular momentum by a factor of ∼2.5, with increased scatter. Instabilities also appear to drive the direction in which the mass–spin sequence of spiral galaxy discs evolves. With them, we find galaxies of fixed mass have higher specific angular momentum at later epochs.
We explore the growth of supermassive black holes and host galaxy bulges in the galaxy population using the Millennium Run Λ cold dark matter (ΛCDM) simulation coupled with a model of galaxy ...formation. We find that, if galaxy mergers are the primary drivers for both bulge and black hole growth, then in the simplest picture one should expect the mBH–mbulge relation to evolve with redshift, with a larger black hole mass associated with a given bulge mass at earlier times relative to the present day. This result is independent of an evolving cold gas fraction in the galaxy population. The evolution arises from the disruption of galactic discs during mergers that make a larger fractional mass contribution to bulges at low redshift than at earlier epochs. There is no comparable growth mode for the black hole population. Thus, this effect produces evolution in the mBH–mbulge relation that is driven by bulge mass growth and not by black holes.
ABSTRACT
We explore the relation between dust and several fundamental properties of simulated galaxies using the Dusty SAGE semi-analytic model. In addition to tracing the standard galaxy properties, ...Dusty SAGE also tracks cold dust mass in the interstellar medium (ISM), hot dust mass in the halo, and dust mass ejected by feedback activity. Based on their ISM dust content, we divide our galaxies into two categories: ISM dust-poor and ISM dust-rich. We split the ISM dust-poor group into two subgroups: halo dust-rich and dust-poor (the latter contains galaxies that lack dust in both the ISM and halo). Halo dust-rich galaxies have high outflow rates of heated gas and dust and are more massive. We divide ISM dust-rich galaxies based on their specific star formation rate (sSFR) into star-forming and quenched subgroups. At redshift z = 0, we find that ISM dust-rich galaxies have a relatively high sSFR, low bulge-to-total (BTT) mass ratio, and high gas metallicity. The high sSFR of ISM dust-rich galaxies allows them to produce dust in the stellar ejecta. Their metal-rich ISM enables dust growth via grain accretion. The opposite is seen in the ISM dust-poor group. Furthermore, ISM dust-rich galaxies are typically late-types, while ISM dust-poor galaxies resemble the early-type population, and we show how their ISM content evolves from being dust-rich to dust-poor. Finally, we investigate dust production from z = 3 to z = 0 and find that all groups evolve similarly, except for the quenched ISM dust-rich group.
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