Local Mass Density Research Articles

Confirming the evolution of the dust mass function in galaxies over the past 5 billion years

ABSTRACT The amount of evolution in the dust content of galaxies over the past 5 billion years of cosmic history is contested in the literature. Here, we present a far-infrared (FIR) census of dust based on a sample of 29 241 galaxies with redshifts ranging from $0 \lt z \lt 0.5$ using data from the Herschel Astrophysical Terahertz Large Area Survey ($H$-ATLAS). We use the spectral energy distribution fitting tool magphys and a stacking analysis to investigate the evolution of dust mass and temperature of FIR-selected galaxies as a function of both luminosity and redshift. At low redshifts, we find that the mass-weighted and luminosity-weighted dust temperatures from the stacking analysis both exhibit a trend for brighter galaxies to have warmer dust. In higher redshift bins, we see some evolution in both mass-weighted and luminosity-weighted dust temperatures with redshift, but the effect is strongest for luminosity-weighted temperature. The measure of dust content in galaxies at $z\lt 0.1$ (the dust mass function) has a different shape to that derived using optically selected galaxies from the same region of sky. We revise the local dust mass density ($z\lt 0.1$) to $\rho _{\rm d} =(1.37\pm 0.08)\times 10^5 {\rm \, {\rm M}_{\odot }\, Mpc^{-3}}\, h_{70}^{-1}$; corresponding to an overall fraction of baryons (by mass) stored in dust of $f_{\rm mb} {(\rm dust)} = (2.22\pm 0.13) \times 10^{-5}$. We confirm evolution in both the luminosity density and dust mass density over the past few billion years ($\rho _{\rm d} \propto (1+z)^{2.6 \pm 0.6}$), with a flatter evolution than observed in previous FIR-selected studies. We attribute the evolution in $\rho _{\rm L}$ and $\rho _{\rm m}$ to an evolution in the dust mass.

Constraining the Initial Mass Function via Stellar Transients

The stellar initial mass function (IMF) represents a fundamental quantity in astrophysics and cosmology describing the mass distribution of stars from low mass all the way up to massive and very massive stars. It is intimately linked to a wide variety of topics, including stellar and binary evolution, galaxy evolution, chemical enrichment, and cosmological reionization. Nonetheless, the IMF still remains highly uncertain. In this work, we aim to determine the IMF with a novel approach based on the observed rates of transients of stellar origin. We parametrize the IMF with a simple but flexible Larson shape, and insert it into a parametric model for the cosmic UV luminosity density, local stellar mass density, type Ia supernova (SN Ia), core-collapse supernova (CCSN), and long gamma-ray burst (LGRB) rates as a function of redshift. We constrain our free parameters by matching the model predictions to a set of empirical determinations for the corresponding quantities via a Bayesian Markov Chain Monte Carlo method. Remarkably, we are able to provide an independent IMF determination with a characteristic mass mc=0.10−0.08+0.24M⊙ and high-mass slope ξ=−2.53−0.27+0.24 that are in accordance with the widely used IMF parameterizations (e.g., Salpeter, Kroupa, Chabrier). Moreover, the adoption of an up-to-date recipe for the cosmic metallicity evolution allows us to constrain the maximum metallicity of LGRB progenitors to Zmax=0.12−0.05+0.29Z⊙. We also find which progenitor fraction actually leads to SN Ia or LGRB emission (e.g., due to binary interaction or jet-launching conditions), put constraints on the CCSN and LGRB progenitor mass ranges, and test the IMF universality. These results show the potential of this kind of approach for studying the IMF, its putative evolution with the galactic environment and cosmic history, and the properties of SN Ia, CCSN, and LGRB progenitors, especially considering the wealth of data incoming in the future.

LIGO-Virgo-KAGRA Limit on Relativistic Interstellar Objects near Earth

Relativistic interstellar objects (RISOs) are not constrained by astronomical sky surveys because they are smeared in sky images and at best appear in one frame. Here, I show that irrespective of their nature, RISOs more massive than ∼1014 g would have been detected by the LIGO-Virgo-KAGRA collaboration through their tidal gravitational signal at a frequency of f ∼ 50 Hz within a distance comparable to the Earth radius. This constrains the passage of relativistic primordial black holes or other exotic objects at the local mass density of dark matter near Earth over the past decade.

Dark matter in the Milky Way: Measurements up to 3 kpc from the Galactic plane above the Sun

We probe the gravitational force perpendicular to the Galactic plane at the position of the Sun based on a sample of red giants, with measurements taken from the DR3 Gaia catalogue. Measurements far out of the Galactic plane up to 3.5 kpc allow us to determine directly the total mass density, where dark matter is dominant and the stellar and gas densities are very low. In a complementary way, we have also used a new determination of the local baryonic mass density to help determine the density of dark matter in the Galactic plane at the solar position. For the local mass density of dark matter, we obtained $ dm $0.0008\,M$_ $ = 0.486 pm 0.030 Gev\ $. For the flattening of the gravitational potential of the dark halo, it is $q_ phi,h For its density, $q_ rho,h $=0.781pm 0.055.

Relation between the Local Width and Linear Halo Mass Density of Cosmic Filaments

Large-scale cosmic filaments may have played an important role in shaping the properties of galaxies. Meanwhile, cosmic filaments are believed to harbor a substantial portion of the missing baryons at redshift z < 2. To inspect the role of filaments in these issues, many properties of filaments need to be examined, including their lengths, thicknesses, and density profiles. However, measuring some of these properties poses challenges. This study concentrates on estimating filament width/thickness, investigating potential correlations between the local width of filaments and the properties of dark matter halos within filaments. We find that the local width of filaments generally increases with the mass of dark matter halos embedded in filaments per unit length, roughly following a second-order polynomial, although with notable scatter. We probe and discuss means that may refine our findings. After further verification and improvements, this relation could be applied to filament samples constructed from the observed galaxy distribution, aiding in understanding the roles of cosmic filaments in galaxy evolution and uncovering the missing baryons.

Refracted Gravity Solutions from Small to Large Scales

If visible matter alone is present in the Universe, general relativity (GR) and its Newtonian weak field limit (WFL) cannot explain several pieces of evidence, from the largest to the smallest scales. The most investigated solution is the cosmological model Λ cold dark matter (ΛCDM), where GR is valid and two dark components are introduced, dark energy (DE) and dark matter (DM), to explain the ∼70% and ∼25% of the mass–energy budget of the Universe, respectively. An alternative approach is provided by modified gravity theories, where a departure of the gravity law from ΛCDM is assumed, and no dark components are included. This work presents refracted gravity (RG), a modified theory of gravity formulated in a classical way where the presence of DM is mimicked by a gravitational permittivity ϵ(ρ) monotonically increasing with the local mass density ρ, which causes the field lines to be refracted in small density environments. Specifically, the flatter the system the stronger the refraction effect and thus, the larger the mass discrepancy if interpreted in Newtonian gravity. RG presented several encouraging results in modelling the dynamics of disk and elliptical galaxies and the temperature profiles of the hot X-ray emitting gas in galaxy clusters and a covariant extension of the theory seems to be promising.

Water distribution in human hair microstructure elucidated by spin contrast variation small-angle neutron scattering

Dynamic nuclear polarization (DNP) is effective for controlling the neutron scattering length of protons and can be utilized for contrast variation in small-angle neutron scattering (SANS). Using the TEMPOL solution soaking method as electron spin doping, the DNP–SANS technique was applied to human hair fiber for the first time. For dry and D2O-swollen hair samples, a drastic change in the SANS profile was observed at high polarization conditions (|P H P N| ∼ 60%, where P H and P N are the proton and neutron spin polarization, respectively). The SANS profile as a function of the magnitude of the scattering vector, q, was composed of a low-q upturn, a middle-q oscillation and a high-q flat region. The low-q upturn was assumed to be a combination of two power-law functions, q −4 due to a large structure interface (Porod's law) and q −2 due to random coil. The middle-q oscillation was well reproduced by numerical calculation based on the structure model of intermediate filaments (IFs) as proposed by Er Rafik et al. [Biophys. J. (2004), 86, 3893–3904]: one pair of keratin coiled-coils is located at the center and surrounded by seven pairs of keratin coiled-coils located in a circle (called the `7 + 1' model), and a collection of IFs is arranged in a quasi-hexagonal manner. For the observed SANS profiles for different P H P N, the IF term contribution maintained a constant q-dependent profile, despite significant changes in intensity. This indicates that the macrofibril is composed of two domains (keratin coiled-coils and matrix). In addition, D2O swelling enhanced the IF term intensity and shifted the polarization-dependent local minimum to higher P H P N. This behavior was reproduced by contrast factor calculation based on the two-domain model. Scattering length densities of keratin coiled-coil and surrounding matrix domains were calculated by use of the known amino acid composition, considering the hydrogen–deuterium exchange reaction during soaking with D2O solution of TEMPOL. As a result, it was found that for keratin coiled-coil domains, about 40% of the peptide backbone amide NH protons were replaced with deuterons. This means that 68% of the α-helix domain is rigid, but the rest is flexible to allow dynamic dissociation of the hydrogen bond. Furthermore, the local mass density of each domain was precisely evaluated. The obtained data are expected to be a guide for further detailed investigation of keratin and keratin-associated protein distribution. This approach is expected to be applied to a wide variety of bio-derived materials, which are water absorbing in general.

Covariant formulation of refracted gravity

We propose a covariant formulation of refracted gravity (RG), which is a classical theory of gravity based on the introduction of gravitational permittivity – a monotonic function of the local mass density – in the standard Poisson equation. Gravitational permittivity mimics dark matter phenomenology. The covariant formulation of RG (CRG) that we propose belongs to the class of scalar-tensor theories, where the scalar fieldφhas a self-interaction potential 𝒱(φ) = − Ξφ, with Ξ being a normalization constant. We show that the scalar field is twice the gravitational permittivity in the weak-field limit. Far from a spherical source of densityρs(r), the transition between the Newtonian and the RG regime appears below the acceleration scaleaΞ = (2Ξ − 8πGρ/φ)1/2, withρ = ρs + ρbgandρbgbeing an isotropic and homogeneous background. In the limit 2Ξ ≫ 8πGρ/φ, we obtainaΞ ∼ 10−10m s−2. This acceleration is comparable to the accelerationa0originally introduced in MOdified Newtonian Dynamics (MOND). From CRG, we also derived the modified Friedmann equations for an expanding, homogeneous, and isotropic universe. We find that the same scalar fieldφthat mimics dark matter also drives the accelerated expansion of the Universe. From the stress-energy tensor ofφ, we derived the equation of state of a redshift-dependent effective dark energywDE = pDE/ρDE. Current observational constraints onwDEand distance modulus data of type Ia supernovae suggest that Ξ has a comparable value to the cosmological constant Λ in the standard model. Since Ξ also plays the same role of Λ, CRG suggests a natural explanation of the known relationa0 ∼ Λ1/2. CRG thus appears to describe both the dynamics of cosmic structure and the expanding Universe with a single scalar field, and it falls within the family of models that unify the two dark sectors, highlighting a possible deep connection between phenomena currently attributed to dark matter and dark energy separately.

Influence of Curing Agents Molecular Structures on Interfacial Characteristics of Graphene/Epoxy Nanocomposites: A Molecular Dynamics Framework

AbstractThis paper presents a comprehensive molecular dynamics study on the effects of the stoichiometric ratio of epoxy:hardener, hardener's linear and cyclic structure, and number of aromatic rings on the interfacial characteristics of graphene/epoxy nanocomposite. The van der Waals gap and polymer peak density as a function of the type of the hardener is calculated by analyzing the local mass density profile. Additionally, steered molecular dynamics are used to conduct normal pull‐out of graphene to study the effect of the mentioned features of hardeners on the interfacial mechanical properties of nanocomposites, including traction force, separation distance, and distribution quality of reacted epoxide rings in the epoxy. Influence of the hardeners on the damage mechanism and its initiation point are also studied by analyzing the evolution of local mass density profile during the normal pull‐out simulation. It is seen that stoichiometric ratio and geometrical structure of the hardeners affect the interfacial strength. It is also revealed that the hardener type can change the epoxy damage initiation point. The damage occurs in the interphase region for a higher stoichiometric ratio or cyclic structure of hardener. In comparison, for hardener's lower stoichiometric ratio and non‐cyclic structure, failure begins in the epoxy near graphene layers.

Application of a linear interpolation algorithm in radiation therapy dosimetry for 3D dose point acquisition

Air-vented ion chambers are generally used in radiation therapy dosimetry to determine the absorbed radiation dose with superior precision. However, in ion chamber detector arrays, the number of array elements and their spacing do not provide sufficient spatial sampling, which can be overcome by interpolating measured data. Herein, we investigated the potential principle of the linear interpolation algorithm in volumetric dose reconstruction based on computed tomography images in the volumetric modulated arc therapy (VMAT) technique and evaluated how the ion chamber spacing and anatomical mass density affect the accuracy of interpolating new data points. Plane measurement doses on 83 VMAT treatment plans at different anatomical sites were acquired using Octavius 729, Octavius1500, and MatriXX ion chamber detector arrays, followed by the linear interpolation to reconstruct volumetric doses. Dosimetric differences in planning target volumes (PTVs) and organs at risk (OARs) between treatment planning system and reconstruction were evaluated by dose volume histogram metrics. The average percentage dose deviations in the mean dose (Dmean) of PTVs reconstructed by 729 and 1500 arrays ranged from 4.7 to 7.3% and from 1.5 to 2.3%, while the maximum dose (Dmax) counterparts ranged from 2.3 to 5.5% and from 1.6 to 7.6%, respectively. The average percentage dose/volume deviations of mixed PTVs and OARs in the abdomen/gastric and pelvic sites were 7.6%, 3.5%, and 7.2%, while mediastinum and lung plans showed slightly larger values of 8.7%, 5.1%, and 8.9% for 729, 1500, and MatriXX detector arrays, respectively. Our findings indicated that the smaller the spacing between neighbouring detectors and the more ion chambers present, the smaller the error in interpolating new data points. Anatomical regions with small local mass density inhomogeneity were associated with superior dose reconstruction. Given a large mass density difference in the various human anatomical structures and the characteristics of the linear interpolation algorithm, we suggest that an alternative data interpolation method should be used in radiotherapy dosimetry.

Gas metallicity distributions in SDSS-IV MaNGA galaxies: what drives gradients and local trends?

ABSTRACTThe gas metallicity distributions across individual galaxies and across galaxy samples can teach us much about how galaxies evolve. Massive galaxies typically possess negative metallicity gradients, and mass and metallicity are tightly correlated on local scales over a wide range of galaxy masses; however, the precise origins of such trends remain elusive. Here, we employ data from SDSS-IV MaNGA to explore how gas metallicity depends on the local stellar mass density and on galactocentric radius within individual galaxies. We also consider how the strengths of these dependencies vary across the galaxy mass-size plane. We find that radius is more predictive of local metallicity than stellar mass density in extended lower-mass galaxies, while we find density and radius to be almost equally predictive in higher-mass and more compact galaxies. Consistent with previous work, we find a mild connection between metallicity gradients and large-scale environment; however, this is insufficient to explain variations in gas metallicity behaviour across the mass-size plane. We argue our results to be consistent with a scenario in which extended galaxies have experienced smooth gas accretion histories, producing negative metallicity gradients over time. We further argue that more compact and more massive systems have experienced increased merging activity that disrupts this process, leading to flatter metallicity gradients and more dominant density-metallicity correlations within individual galaxies.

Interaction of nanoparticles with micro organisms under Lorentz force in a polymer liquid with zero mass flux

BackgroundRheological fluids enduring bio convection are gaining great attention in modern day industrial, technological and several manufacturing industries. Such flows are evident in chemical and mining industry, biomedical flows, and many other fields of science and engineering. Among the many other rheolgical liquids, Sutterby fluid model is significant due to its characteristics of Pseudoplastic and dilatant fluids. It portrays dilute polymer solutions, which has numerous applications in industrial practice. MethodsIn this theoretical research two-dimensional hydromagnetic stagnation point flow of Sutterby bio convective fluid through an elastic surface has been discussed. The mathematical model of governed problem is transformed into a set of ordinary differential equations using similarity transformation. These nonlinear coupled ordinary differential equations are handled by using shooting scheme (numerical technique). Significant findingsInfluence of all physical constraints for temperature, concentration of gyrotactic microorganism and velocity profiles are presented graphically. Local heat & mass flux and density of microorganisms (Physical quantities of interest) are presented numerically through bar charts.

Mass Density Inferred From Toroidal Wave Frequencies and Energization of Low‐Energy Helium Ions During H‐Band EMIC Wave Interval

AbstractVan Allen Probe A observed strongly enhanced hydrogen (H+) band electromagnetic ion cyclotron (EMIC) waves lasting &gt;6 hr without helium (He+) band EMIC wave activity outside the plasmasphere on 23 February 2014. During the H‐band EMIC wave interval, multiharmonic toroidal waves were detected by the spacecraft. We estimated the local mass density using the observed toroidal wave frequencies and background electron number density. It was found that the average ion mass is close to 1. This indicates that the protons are the dominant ion species for the H‐band wave interval. From these observations, we suggest that the cold ion composition plays a major role in determining the spectral properties of EMIC waves. We also observed low‐energy He+ ion flux enhancements associated with the H‐band EMIC waves in the direction perpendicular to the background magnetic field. We discuss how the H‐band waves energize the low‐energy He+ ions in the perpendicular direction.

The $\kappa $-model, a minimal model alternative to dark matter: application to the galactic rotation problem

The determination of the velocities, accelerations and the gravitational field intensity at a given location in a galaxy could potentially be achieved in an unexpected manner with the environment of the observer, for instance, the local mean mass density in the galaxy. This idea, mathematically supported by the asymmetric distance concept, is illustrated here by a study regarding the rotation of spiral galaxies. This suggestion is new in the astrophysics field (in the following, it is called the \k{appa}-model) and could help to mimic the main effects seen in modified Newtonian dynamics (MOND) theory, modified gravity (MOG) models, or other related models built with the aim of eliminating dark matter that are already well-established theories. Thus, starting from two selected examples of galaxies, in section 5, we show that there is an equivalence between MOND and the \k{appa}-model. In particular, on the opposite side, we have the speculative nature of the dominant paradigm, the elusive dark matter, a matter whose properties always remain undefined despite intense theoretical, experimental and observational efforts for over 50 years.

The Milky Way tomography with APOGEE: intrinsic density distribution and structure of mono-abundance populations

ABSTRACT The spatial distribution of mono-abundance populations (MAPs, selected in [Fe/H] and [Mg/Fe]) reflect the chemical and structural evolution in a galaxy and impose strong constraints on galaxy formation models. In this paper, we use APOGEE data to derive the intrinsic density distribution of MAPs in the Milky Way, after carefully considering the survey selection function. We find that a single exponential profile is not a sufficient description of the Milky Way’s disc. Both the individual MAPs and the integrated disc exhibit a broken radial density distribution; densities are relatively constant with radius in the inner Galaxy and rapidly decrease beyond the break radius. We fit the intrinsic density distribution as a function of radius and vertical height with a 2D density model that considers both a broken radial profile and radial variation of scale height (i.e. flaring). There is a large variety of structural parameters between different MAPs, indicative of strong structure evolution of the Milky Way. One surprising result is that high-α MAPs show the strongest flaring. The young, solar-abundance MAPs present the shortest scale height and least flaring, suggesting recent and ongoing star formation confined to the disc plane. Finally we derive the intrinsic density distribution and corresponding structural parameters of the chemically defined thin and thick discs. The chemical thick and thin discs have local surface mass densities of 5.62 ± 0.08 and 15.69 ± 0.32 M⊙pc−2, respectively, suggesting a massive thick disc with a local surface mass density ratio between thick to thin disc of 36 per cent.

Mock catalogues of emission-line galaxies based on the local mass density in dark-matter only simulations

ABSTRACT The high-precision measurement of spatial clustering of emission-line galaxies (ELGs) is a primary objective for upcoming cosmological spectroscopic surveys. The source of strong emission of ELGs is nebular emission from surrounding ionized gas irradiated by massive short-lived stars in star-forming galaxies. As a result, ELGs are more likely to reside in newly formed haloes and this leads to a non-linear relation between ELG number density and matter density fields. In order to estimate the covariance matrix of cosmological observables, it is essential to produce many independent realizations to simulate ELG distributions for large survey volumes. To this end, we present a novel and fast scheme to populate ELGs in dark-matter only N-body simulations based on local density field. This method enables fast production of mock ELG catalogues suitable for verifying analysis methods and quantifying observational systematics in upcoming spectroscopic surveys and can populate ELGs in moderately high-density regions even though the halo structure cannot be resolved due to low resolution. The power spectrum of simulated ELGs is consistent with results of hydrodynamical simulations up to fairly small scales ($\lesssim 1 h \, \mathrm{Mpc}^{-1}$), and the simulated ELGs are more likely to be found in filamentary structures, which is consistent with results of semi-analytic and hydrodynamical simulations. Furthermore, we address the redshift-space power spectrum of simulated ELGs. The measured multipole moments of simulated ELGs clearly exhibit a weaker Finger-of-God effect than those of matter due to infalling motions towards halo centre, rather than random virial motions inside haloes.

A Re-Interpretation of Quasi-Local Mass

Because the equivalence principle forbids local mass density, we cannot formulate general relativistic mass as an integral over mass density as in Newtonian gravity. This century-old problem was addressed forty years ago by Penrose, and many papers have since extended the concept. Currently there is no satisfactory physical understanding of the nature of quasi-local mass. In this paper I review the key issues, the current status, and propose an alternative interpretation of the problem of local mass and energy density for gravity systems from an information perspective.

The Black Hole Mass Function Across Cosmic Times. I. Stellar Black Holes and Light Seed Distribution

Abstract This is the first paper in a series aimed at modeling the black hole (BH) mass function, from the stellar to the intermediate to the (super)massive regime. In the present work, we focus on stellar BHs and provide an ab initio computation of their mass function across cosmic times; we mainly consider the standard, and likely dominant, production channel of stellar-mass BHs constituted by isolated single/binary star evolution. Specifically, we exploit the state-of-the-art stellar and binary evolutionary code SEVN, and couple its outputs with redshift-dependent galaxy statistics and empirical scaling relations involving galaxy metallicity, star formation rate and stellar mass. The resulting relic mass function dN / dVd log m • as a function of the BH mass m • features a rather flat shape up to m • ≈ 50 M ⊙ and then a log-normal decline for larger masses, while its overall normalization at a given mass increases with decreasing redshift. We highlight the contribution to the local mass function from isolated stars evolving into BHs and from binary stellar systems ending up in single or binary BHs. We also include the distortion on the mass function induced by binary BH mergers, finding that it has a minor effect at the high-mass end. We estimate a local stellar BH relic mass density of ρ • ≈ 5 × 107 M ⊙ Mpc−3, which exceeds by more than two orders of magnitude that in supermassive BHs; this translates into an energy density parameter Ω• ≈ 4 × 10−4, implying that the total mass in stellar BHs amounts to ≲1% of the local baryonic matter. We show how our mass function for merging BH binaries compares with the recent estimates from gravitational wave observations by LIGO/Virgo, and discuss the possible implications for dynamical formation of BH binaries in dense environments like star clusters. We address the impact of adopting different binary stellar evolution codes (SEVN and COSMIC) on the mass function, and find the main differences to occur at the high-mass end, in connection with the numerical treatment of stellar binary evolution effects. We highlight that our results can provide a firm theoretical basis for a physically motivated light seed distribution at high redshift, to be implemented in semi-analytic and numerical models of BH formation and evolution. Finally, we stress that the present work can constitute a starting point to investigate the origin of heavy seeds and the growth of (super)massive BHs in high-redshift star-forming galaxies, that we will pursue in forthcoming papers.

The dynamics of three nearby E0 galaxies in refracted gravity

We tested whether refracted gravity, a theory of modified gravity that describes the dynamics of galaxies without the aid of dark matter, can model the dynamics of the three massive elliptical galaxies, NGC 1407, NGC 4486, and NGC 5846, out to ∼10Re, where the baryonic mass component fades out and dark matter is required in Newtonian gravity. We probed these outer regions with the kinematics of the globular clusters provided by the SLUGGS survey. Refracted gravity mimics dark matter with the gravitational permittivity, a monotonic function of the local mass density depending on three parameters,ϵ0,ρc, andQ, which are expected to be universal. Refracted gravity satisfactorily reproduces the velocity dispersion profiles of the stars and red and blue globular clusters, with stellar mass-to-light ratios in agreement with stellar population synthesis models, and orbital anisotropy parameters consistent with previous results obtained in Newtonian gravity with dark matter. The sets of the three parameters of the gravitational permittivity found for each galaxy are consistent with each other within ∼2σ. We compare the mean {ϵ0,Q,log10(ρc[g cm−3])} = {0.089−0.035+0.038, 0.47−0.21+0.29, −24.25−0.20+0.28} found here with the means of the parameters required to model the rotation curves and vertical velocity dispersion profiles of 30 disk galaxies from the DiskMass Survey (DMS):ρcandQagree within 1σwith the DMS values, whereasϵ0agrees within 3σ. This agreement suggests that ellipticals and disk galaxies allow for common values of the parameters of the permittivity and supports the universality of the permittivity function.

Capturing Centimeter-Scale Local Variations in Paper Pore Space via μ-CT: A Benchmark Study Using Calendered Paper

Abstract A two-step framework to analyze local microstructure variations of paper sheets based on 3D image data is presented. First, a multi-stage workflow efficiently acquires a large set of highly resolved tomographic image data, which enables—in combination with statistical image analysis—the quantification of local variations and pairwise correlations of morphological microstructure characteristics on length scales ranging from micrometers to centimeters. Secondly, the microstructure is analyzed in terms of the local behavior of porosity, thickness, and further descriptors related to transportation paths. The power of the presented framework is demonstrated, showing that it allows one (i) to quantitatively reveal the difference in terms of local structural variations between a model paper before and after unidirectional compression via hard-nip calendering and that (ii) the field of view which is required to reliably compute the probability distributions of the considered local microstructure characteristics is at least 20 mm. The results elucidate structural differences related to local densification. In particular, it is shown how calendering transforms local variations in sheet thickness into marked local mass density variations. The obtained results are in line with experimental measurements of macroscopic properties (basis weight, Bekk smoothness parameters, thickness, and Gurley retention times).