Baryonic Mass Research Articles

The Gas Accretion Rate of Galaxies over z ≈ 0–1.3

We present here estimates of the average rates of accretion of neutral gas onto main-sequence galaxies and the conversion of atomic gas to molecular gas in these galaxies at two key epochs in galaxy evolution: (i) z ≈ 1.3–1.0, toward the end of the epoch of peak star formation activity in the Universe, and (ii) z ≈ 1–0, when the star formation activity declines by an order of magnitude. We determine the net gas accretion rate R Acc and the molecular gas formation rate R Mol by combining the relations between the stellar mass and the atomic gas mass, the molecular gas mass, and the star formation rate (SFR) at three epochs, z = 1.3, z = 1.0, and z = 0, with the assumption that galaxies evolve continuously on the star-forming main sequence. We find that, for all galaxies, R Acc is far lower than the average SFR R SFR at z ≈ 1.3–1.0; however, R Mol is similar to R SFR during this interval. Conversely, both R Mol and R Acc are significantly lower than R SFR over the later interval, z ≈ 1–0. We find that massive main-sequence galaxies had already acquired most of their present-day baryonic mass by z ≈ 1.3. At z ≈ 1.3–1.0, the rapid conversion of the existing atomic gas to molecular gas was sufficient to maintain a high average SFR, despite the low net gas accretion rate. However, at later times, the combination of the lower net gas accretion rate and the lower molecular gas formation rate leads to a decline in the fuel available for star formation and results in the observed decrease in the SFR density of the Universe over the last 8 Gyr.

General relativistic simulations of high-mass binary neutron star mergers: rapid formation of low-mass stellar black holes

ABSTRACT Almost a hundred compact binary mergers have been detected via gravitational waves by the LIGO-Virgo-KAGRA collaboration in the past few years providing us with a significant amount of new information on black holes and neutron stars. In addition to observations, numerical simulations using newly developed modern codes in the field of gravitational wave physics will guide us to understand the nature of single and binary degenerate systems and highly energetic astrophysical processes. We here presented a set of new fully general relativistic hydrodynamic simulations of high-mass binary neutron star systems using the open-source EINSTEIN TOOLKIT and LORENE codes. We considered systems with total baryonic masses ranging from 2.8$\, \mathrm{M}_\odot$ to 4.0$\, \mathrm{M}_\odot$ and used the SLy equation of state. We analysed the gravitational wave signal for all models and report potential indicators of systems undergoing rapid collapse into a black hole that could be observed by future detectors like the Einstein Telescope and the Cosmic Explorer. The properties of the post-merger black hole, the disc and ejecta masses, and their dependence on the binary parameters were also extracted. We also compared our numerical results with recent analytical fits presented in the literature and provided parameter-dependent semi-analytical relations between the total mass and mass ratio of the systems and the resulting black hole masses and spins, merger frequency, BH formation time, ejected mass, disc mass, and radiated gravitational wave energy.

Low-lying baryon masses using twisted mass fermions ensembles at the physical pion mass

Low-lying baryon masses using twisted mass fermions ensembles at the physical pion mass

Polar-ring galaxies in the Illustris TNG50 simulation

ABSTRACT Polar-ring galaxies (PRGs) are an outstanding example of galaxies with misaligned kinematics where a typically red central galaxy is surrounded by a large-scale ring or disc of stars, gas, and dust oriented almost perpendicular to the main body. It is believed that polar structures (PSs) are formed in a secondary event after the assembly of a central galaxy, but due to their scarcity, their formation paths are not well constrained yet. We present a study of PRGs from TNG50 cosmological simulations, focusing on the origin of their PSs. Based on the synthetic images and baryonic mass distribution, we found six galaxies with stellar polar rings. Using Supplementary Data Catalogues and available particle data, we confirm that the selected galaxies are direct analogues of real PRGs. In our sample, the PSs are a result of the close interaction between the host galaxy and its companion. We track two formation paths for the stellar polar rings in our sample: (i) star formation in the accreted gas and (ii) tidal disruption of the satellite’s stellar component. Rings formed during the first scenario are, on average, bluer and younger than ones formed due to the satellite disruption. We report a steady increase of the ring’s inclination around the two most massive galaxies across a few billion years with a rate of ≈8° Gyr−1. The formation of a PS in some cases can increase the nuclear activity of the central galaxy and/or turn the active nucleus off completely.

QCD vacuum and baryon masses

To study a possible role of the quantum chromodynamics (QCD) vacuum in nuclear and hadron physics, we evaluate a physical quantity in a candidate of the QCD vacuum. In this study, we adopt the Copenhagen (spaghetti) picture of the QCD vacuum and calculate the ground state baryon masses in a constituent quark model. We find that the calculated baryon mass does depend on a parameter that characterizes the Copenhagen picture of the QCD vacuum and satisfies the Gell-Mann–Okubo mass relation for the baryon octet. We also observe that the effective constituent quark mass defined in this study contains a contribution attributed to the Copenhagen vacuum, that is the gluon background field. We then estimate the value of the background gluon field as a function of the up (down) constituent quark mass by using the baryon masses as inputs.

The Tully–Fisher relation and the Bosma effect

ABSTRACT We show that the rotation curves of 16 nearby disc galaxies in the THINGS sample and the Milky Way can be described by the Navarro–Frenk–White halo model and by the Bosma effect at approximately the same level of accuracy. The latter effect suggests that the behaviour of the rotation curve at large radii is determined by the rescaled gas component and thus that dark matter and gas distributions are tightly correlated. By focusing on galaxies with exponential decay in their gas surface density, we can normalize their rotation curves to match the exponential thin disc model at large enough radii. This normalization assumes that the galaxy mass is estimated consistently within this model, assuming a thin disc structure. We show that this rescaling allows us to derive a new version of the Tully–Fisher (TF) relation, the Bosma TF relation that nicely fit the data. In the framework of this model, the connection between the Bosma TF relation and the baryonic TF relation can be established by considering an additional empirical relation between the baryonic mass and the total mass of the disc, as measured in the data.

Black Hole Formation Accompanied by the Supernova Explosion of a 40 M ⊙ Progenitor Star

We have simulated the collapse and evolution of the core of a solar-metallicity 40 M ⊙ star and find that it explodes vigorously by the neutrino mechanism, despite its very high “compactness.” Within ∼1.5 s of explosion, a black hole forms. The explosion is very asymmetrical and has a total explosion energy of ∼1.6 × 1051 erg. At black hole formation, its baryon mass is ∼2.434 M ⊙ and gravitational mass is 2.286 M ⊙. Seven seconds after black hole formation, an additional ∼0.2 M ⊙ is accreted, leaving a black hole baryon mass of ∼2.63 M ⊙. A disk forms around the proto−neutron star, from which a pair of neutrino-driven jets emanates. These jets accelerate some of the matter up to speeds of ∼45,000 km s−1 and contain matter with entropies of ∼50. The large spatial asymmetry in the explosion results in a residual black hole recoil speed of ∼1000 km s−1. This novel black hole formation channel now joins the other black hole formation channel between ∼12 and ∼15 M ⊙ discovered previously and implies that the black hole/neutron star birth ratio for solar-metallicity stars could be ∼20%. However, one channel leaves black holes in perhaps the ∼5–15 M ⊙ range with low kick speeds, while the other leaves black holes in perhaps the ∼2.5–3.0 M ⊙ mass range with high kick speeds. However, even ∼8.8 s after core bounce the newly formed black hole is still accreting at a rate of ∼2 × 10−2 M ⊙ s−1, and whether the black hole eventually achieves a significantly larger mass over time is yet to be determined.

Tracking the evolution of satellite galaxies: mass stripping and dark-matter deficient galaxies

ABSTRACT Satellite galaxies undergo a variety of physical processes when they are accreted by groups and clusters, often resulting in the loss of baryonic and dark matter (DM) mass. In this work, we evaluate the predictions from the IllustrisTNG hydrodynamical simulation regarding the evolution of the matter content of satellites, focusing on a population that are accreted at z > 1 and retain their identity as satellites down to z = 0. At fixed host halo mass, the amount of DM and stellar mass stripped depends mostly on the pericentric distance, dperi, here normalized by host halo virial radius. The closest encounters result in significant loss of DM, with subhaloes retaining between 20 and a few per cent of their z = 1 mass. At fixed dperi, DM mass stripping seems more severe in lower mass haloes. Conversely, the average satellite in higher mass haloes has its stellar mass growth halted earlier, having lost a higher fraction of stellar mass by z = 0. We also show that mass stripping has a strong impact on the quenched fractions. The IllustrisTNG boxes are qualitatively consistent in these predictions, with quantitative differences mostly originating from the distinct subhalo mass ranges covered by the boxes. Finally, we have identified DM-deficient systems in all TNG boxes. These objects are preferentially found in massive clusters (Mhost ≳ 1013 M⊙), had very close encounters with their central galaxies ($d_{\rm peri}\simeq 0.05\, R_{\rm vir}$), and were accreted at high redshift (zinfall ≳ 1.4), reinforcing the notion that tidal stripping is responsible for their remarkable lack of DM.

Diquarks and Λ0/π+, Ξ−/π+ Ratios in the Framework of the EPNJL Model

The applicability of the effective models to the description of baryons and the behaviour of ratios of strange baryons to pions is discussed. In the framework of the EPNJL model, the Bethe–Salpeter equation is used to find masses of baryons, which are considered to be in a diquark-quark state. Baryon melting is discussed at a finite chemical potential, and a flavor dependence of the hadronic deconfinement temperature is pointed out. It is shown that the description of the diquark-quark state at finite chemical potential is limited due to the occurrence of Bose condensate. This effect is strongly manifested in the description of light diquarks and baryons. Both the Λ0/π+ and Ξ−/π+ ratios show a sharp behaviour as functions of the T/μB variable, where T and μB are calculated along the melting lines.

Examining the relationship between the bulge-to-total stellar mass ratio and dwarf galaxy count in the context of ΛCDM

Previous results suggest that there is a correlation between the size of the bulge of a galaxy and the number of its dwarf galaxy satellites. This was found to be inconsistent with the standard model of cosmology based on comparisons to semi-analytical dark-matter-only simulations, where no such correlation was found. In this work, we extend these studies using the volume-complete ELVES dwarf galaxy catalog, which increases the number of systems compared to previous work by a factor of four. For each giant galaxy we compiled the bulge-to-total baryonic mass (B/T) ratio and present it as a function of the number of dwarf galaxies surrounding them within 250 kpc (N250). For the 29 galaxy systems in the ELVES catalog, we find a linear relation between B/T and N250, which is consistent with previous data. However, for a given stellar mass of the host galaxy, this relation is mainly driven by the galaxies’ morphologies: early-type galaxies have a larger B/T ratio and a larger N250 than late-type galaxies. By investigating spiral galaxies in TNG100 of the IllustrisTNG suite, we tested whether the inclusion of baryons in the simulations would result in differences from those based on Millennium-II. Contrary to dark-matter-only simulations, we do find a correlation between B/T and N250, indicating that the standard model of cosmology does predict a correlation. The empirical relation between the number of satellites and the bulge to total stellar mass is therefore not necessarily in tension with Λ cold dark matter.

Correction to: Analytical Determination of Mass and Magnetic Moment of Baryons in Diquark Model

Correction to: Analytical Determination of Mass and Magnetic Moment of Baryons in Diquark Model

Baryonic Mass Inventory for Galaxies and Rarefied Media from Theory and Observations of Rotation and Luminosity

Available inventories of baryonic mass in the universe are based largely on galactic data and empirical calculations made >20 years ago. Values falling below cosmological estimates underlie proposals that certain rarified gassy regions could have extremely high T, which motivated absorption measurements and hydrodynamic models. Yet, the shortfall remains. We inventory the total baryonic mass, focusing on gravitational interactions and updated measurements. A recent analytical inverse method for analyzing galactic rotation curves quantified how baryon mass and associated volumetric density (ρ) depend on distance (r) from galactic centers. The model is based on the dynamical consequences of the observed oblate shape of galaxies and the Virial Theorem. The parameter-free solution provides ρ(r) ∝ 1/r2 which describes star-rich galactic interiors, gas-rich outer discoids, circumgalactic media, and gradation into intergalactic media. Independent observational determinations of baryonic ρ validate that our 1/r2 result describes baryons alone. This solution shows that total baryonic mass associated with any galaxy is 2.4 to 40 times detectable luminosity, depending on galaxy size and spacing. Luminosity data within 50 Mpc show that Andromeda equivalents separated by ~1 Mpc represent the local universe. Combining the above yields (6 ± 2) × 10−25 kg m−3 for the present-day universe. Three other approaches support this high density: (1) evaluating trends and luminosity data near 1000 Mpc; (2) using a recent estimate for the number of galaxies in the universe; (3) calculating an energy balance. We discuss uncertainties in the critical density. Implications of large baryonic ρ are briefly discussed.

The integrated galaxy-wide stellar initial mass function over the radial acceleration range of early-type galaxies

ABSTRACT The observed radial accelerations of 462 early-type galaxies (ETGs) at their half-mass radii are discussed. They are compared to the baryonic masses of the same galaxies, which are derived from theoretical expectations for their stellar populations and cover a range from $\approx 10^4 \, {\rm M}_{\odot }$ to $\approx 10^{11} \, {\rm M}_{\odot }$. Both quantities are plotted against each other, and it is tested whether they lie (within errors) along theoretical radial acceleration relations (RARs). We choose the Newtonian RAR and two Milgromian, or MONDian RARs. At low radial accelerations (corresponding to low masses), the Newtonian RAR fails without non-baryonic dark matter, but the two MONDian ones may work, provided moderate out-of-equilibrium dynamics in some of the low-mass ETGs. However all three RARs fail at high accelerations (corresponding to high masses) if all ETGs have formed their stellar populations with the canonical stellar initial mass function (IMF). A much better agreement with the observations can however be accomplished, if the theory of the integrated galaxy-wide stellar initial mass functions (IGIMFs) is used instead. This is because the IGIMF-theory predicts the formation of an overabundance of stellar remnants during the lifetime of the massive ETGs. Thus their baryonic masses today are higher than they would be if the ETGs had formed with a canonical IMF. Also the masses of the stellar-mass black holes should be rather high, which would mean that most of them probably formed when the massive ETGs were not as metal-enriched as they are today. The IGIMF-approach confirms downsizing.

Exploring the angular momentum – atomic gas content connection with eagle and IllustrisTNG

ABSTRACT We use the Evolution and Assembly of GaLaxies and their Environments (eagle) and IllustrisTNG (The Next Generation) cosmological simulations to investigate the properties of the baryonic specific angular momentum (j), baryonic mass (M), and atomic gas fraction (fatm) plane for nearby galaxies. We find EAGLE and TNG to be in excellent agreement with each other. These simulations are also consistent with the results obtained with eXtended GALEX Arecibo SDSS Survey (xGASS) for gas fractions greater than 0.01. This implies that the disagreements previously identified between xGASS and predictions from simple analytical disc stability arguments also holds true for eagle and tng. For lower gas fraction (the regime currently unconstrained by observations), both simulations deviate from the plane but still maintain good agreement with each other. Despite the challenges posed by resolution limits at low gas fractions, our findings suggest a potential disconnect between angular momentum and gas fraction in the gas-poor regime, implying that not all gas-poor galaxies have low specific angular momentum.

Comparable dark matter and baryon abundances with a heavy dark sector

We propose a scenario that explains the comparable abundances of dark matter (DM) and baryons without any coincidence in the corresponding particle masses. Here, DM corresponds to heavy “dark baryons” in a hidden MSSM-like dark sector, where the supersymmetry breaking scale can be several orders of magnitude larger than in the visible sector. In both sectors a baryon asymmetry is generated via the Affleck-Dine mechanism, and the smaller dark baryon-to-entropy ratio partially compensates the larger dark baryon masses to give similar densities in the two sectors. The large mass hierarchy also naturally results in an asymmetric reheating of these sequestered sectors. Moreover, this scenario predicts uncorrelated DM and baryon isocurvature perturbations.

Metal-THINGS: a panchromatic analysis of the local scaling relationships of the dwarf irregular galaxy NGC 1569

ABSTRACT We investigate several panchromatic scaling relations (SRs) for the dwarf irregular galaxy NGC 1569 using Integral Field Unit (IFU) data from the Metal-THINGS Survey. Among the spatially resolved properties analysed, we explore SRs between the stellar mass, SFR, molecular gas, total gas, baryonic mass, gas metallicity, gas fraction, SFE, and effective oxygen yields. Such multiwavelength SRs are analysed at a spatial resolution of 180 pc, by combining our IFU observations with data from the surveys THINGS, CARMA, and archival data from DustPedia. Although we recover several known relations, our slopes are different to previously reported ones. Our star formation main sequence, Kennicutt–Schmidt (KS), and molecular KS relations show higher SFRs, lower scatter, and higher correlations, with steeper (1.21), and flatter slopes (0.96, 0.58), respectively. The shape of the SRs including metallicity, stellar mass, and gas fraction are flat, with an average value of 12 + log(O/H) ∼ 8.12 dex. The baryonic mass versus effective oxygen yields, and the stellar, gas and baryonic mass versus SFE show higher dispersions and lower correlations. Since we use the dust mass as a tracer of gas mass, we derive the dust-to-gas ratio and the CO luminosity-to-molecular gas mass conversion factors, showing differences of 0.16 and 0.95 dex for the total and molecular gas surface density, respectively, in comparison to previously reported values. We use a self-regulated feedback model to conclude that stellar feedback plays an important role generating outflows in NGC 1569.

Thesan-hr: how does reionization impact early galaxy evolution?

ABSTRACT The feedback loop between the galaxies producing the background radiation field for reionization and their growth is crucial, particularly for low-mass haloes. Despite this, the vast majority of galaxy formation studies employ a spatially uniform, time-varying reionizing background, with the majority of reionization studies employing galaxy formation models only required to work at high redshift. This paper uses the well-studied TNG galaxy formation model, calibrated at low redshift, coupled to the arepo-rt code, to self-consistently solve the coupled problems of galaxy evolution and reionization, evaluating the impact of patchy (and slow) reionization on early galaxies. thesan-hr is an extension of the thesan project to higher resolution (a factor of 50 increase, with a baryonic mass of mb ≈ 104 M⊙), to additionally enable the study of ‘mini-haloes’ with virial temperatures Tvir < 104 K. Comparing the self-consistent model to a uniform UV background, we show that galaxies in thesan-hr are predicted to be larger in physical extent (by a factor ∼2), less metal enriched (by ∼0.2 dex), and less abundant (by a factor ∼10 at M1500 = − 10) by z = 5. We show that differences in star formation and enrichment patterns lead to significantly different predictions for star formation in low mass haloes, low-metallicity star formation, and even the occupation fraction of haloes. We posit that cosmological galaxy formation simulations aiming to study early galaxy formation (z ≳ 3) must employ a spatially inhomogeneous UV background to accurately reproduce galaxy properties.

Phenomenologies in Hypersphere Soliton and Stringy Photon Models

We consider the Dirac quantization in the first-class formalism to investigate the hypersphere soliton model (HSM) defined on the S3 hypersphere. To do this, we construct the first-class Hamiltonian possessing the Weyl ordering correction. In the HSM, we evaluate the baryon physical quantities such as the baryon masses, magnetic moments, axial coupling constant and charge radii, most predicted values of which are in good agreement with the corresponding experimental data. Moreover, shuffling the baryon and transition magnetic moments, we find the model independent sum rules. In the HSM we also evaluate the baryon intrinsic frequencies such as ωN=0.87×1023s−1 and ωΔ=1.74×1023s−1 of the nucleon and delta baryon, respectively, to yield the identity ωΔ=2ωN. Next, making use of the Nambu-Goto string action and its extended rotating bosonic string theory, we formulate the stringy photon model to obtain the energy of the string configuration, which consists of the rotational and vibrational energies of the open string. Exploiting this total string energy, we evaluate the photon intrinsic frequency ωγ=9.00×1023s−1, which is comparable to the corresponding baryon intrinsic frequencies. We also predict the photon size ⟨r2⟩1/2(photon)=0.17fm, which is approximately 21% of the proton magnetic charge radius.

Analytical Determination of Mass and Magnetic Moment of Baryons in Diquark Model

Analytical Determination of Mass and Magnetic Moment of Baryons in Diquark Model

The FLAMINGO project: cosmological hydrodynamical simulations for large-scale structure and galaxy cluster surveys

ABSTRACT We introduce the Virgo Consortium’s FLAMINGO suite of hydrodynamical simulations for cosmology and galaxy cluster physics. To ensure the simulations are sufficiently realistic for studies of large-scale structure, the subgrid prescriptions for stellar and AGN feedback are calibrated to the observed low-redshift galaxy stellar mass function and cluster gas fractions. The calibration is performed using machine learning, separately for each of FLAMINGO’s three resolutions. This approach enables specification of the model by the observables to which they are calibrated. The calibration accounts for a number of potential observational biases and for random errors in the observed stellar masses. The two most demanding simulations have box sizes of 1.0 and 2.8 Gpc on a side and baryonic particle masses of 1 × 108 and $1\times 10^9\, \text{M}_\odot$, respectively. For the latter resolution, the suite includes 12 model variations in a 1 Gpc box. There are 8 variations at fixed cosmology, including shifts in the stellar mass function and/or the cluster gas fractions to which we calibrate, and two alternative implementations of AGN feedback (thermal or jets). The remaining 4 variations use the unmodified calibration data but different cosmologies, including different neutrino masses. The 2.8 Gpc simulation follows 3 × 1011 particles, making it the largest ever hydrodynamical simulation run to z = 0. Light-cone output is produced on-the-fly for up to 8 different observers. We investigate numerical convergence, show that the simulations reproduce the calibration data, and compare with a number of galaxy, cluster, and large-scale structure observations, finding very good agreement with the data for converged predictions. Finally, by comparing hydrodynamical and ‘dark-matter-only’ simulations, we confirm that baryonic effects can suppress the halo mass function and the matter power spectrum by up to ≈20 per cent.