Normal Matter Research Articles

Edge‐Preserved Tversky Indexive Hellinger with Deep Perceptive Czekanowski‐Based Image Classification

The texture is identifiable in optical and easy ways. Texture classification is an imperative region in texture analysis, where it gives descriptors for classifying the images. The categorization of normal and abnormal matter by magnetic resonance (MR), computed tomography (CT), and texture images has made noteworthy evolution in modern years. Recently, different novel robust classification techniques have been introduced to classify the different kinds of images for prediction. However, the accuracy of classification was not improved with lesser time. To address these issues, the edge‐preserved Tversky indexive Hellinger and deep perceptive Czekanowski classifier (ETIH‐DPCC) technique is introduced to segment and classify the images with more accuracy. The ETIH‐DPCC technique includes diverse processes namely preprocessing, segmentation, feature extraction, as well as classification. At first, different types of images, such as magnetic resonance imaging, CT, and texture, are used as input. With the acquired input, edge‐preserving normalized adaptive bilateral filtering is employed to carry the image preprocessing. In this stage, the noisy pixels are removed and edges are preserved. Then, the Tversky‐indexed quantile regression is applied to segment the images into diverse texture regions. After that, the feature extraction is performed on the segmented region using Hellinger kernel feature extraction, where a more informative feature for image prediction is extracted. During this process, the irrelevant features are avoided to decrease the dimensionality and feature extraction time. These extracted features are finally classified into positive and negative classes for disease prediction using DPCC. DPCC comprises multiple layers to deeply analyze the association between training and testing features. With this, the prediction accuracy is improved. Experimental outcomes show that the ETIH‐DPCC technique efficiently enhances prediction accuracy and less time compared to conventional methods.

Constraining physical parameters of DESs via the secondary component of the GW190814 event and other self-bound NS pulsars in f(Q)-gravity theory

The spherically symmetric dark energy (DE) stellar model is presented here within the context of the f(Q) theory of gravity. In order to develop the model, we take into account the linear functional form of f(Q) as f(Q)=mQ+n\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$f(Q)=mQ+n$$\\end{document}, where m is the coupling parameter and n is a real constant. We further assume that the stellar model is composed of normal baryonic matter along with DE; however, for the sake of simplicity, we avoid the interaction between them. The impact of the coupling parameter m on different physical parameters of DE stars (DESs) has been thoroughly investigated. For various values of m specified in the figure, the numerical values of the physical parameters are shown in tabular form. It is found that as m increases, the DES candidates become gradually massive and larger in size. In order to compare the behaviour of DESs with the observational results, we use the measurement of the GW190814 event and the three NS pulsars, viz. 4U1608-52 (mass =1.74-0.14+0.14M⊙\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$= 1.74_{- 0.14}^{+0.14}~M_{\\odot }$$\\end{document}), PSR J1614-2230 (mass =1.97-0.04+0.04M⊙\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$=1.97_{-0.04}^{+0.04}~M_{\\odot }$$\\end{document}), and PSR J0952-0607 (mass =2.35-0.17+0.17M⊙\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$=2.35_{- 0.17}^{+0.17}~M_{\\odot }$$\\end{document}). With the help of the M-R\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$M-R$$\\end{document} plot, the maximum mass of the DES obtained from our model is 2.57M⊙\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$2.57~M_{\\odot }$$\\end{document}, which is located within the lower “mass gap” range. To cover the observational constraints, this DES can be a representative for the secondary component of the GW190814 event, whose mass range is detected to be 2.59-0.09+0.08M⊙\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$2.59_{-0.09}^{+0.08}~M_{\\odot }$$\\end{document} by LIGO/VIRGO experiments.

The big-bang started from nothing: Not the initially hot cosmic matter, but a positive vacuum pressure made the universe explode!

Mankind all over its past epochs did ask the question, how this huge and materially impressive universe could ever have started its existence. The standard dogmatic answer presently given by the majority of modern cosmologists is: By the Big-Bang! - i.e. that initial explosion of the central highly condensed world matter system! But why - it could be asked - should this system have exploded at all? Perhaps this popular BB-hypothesis of a general and global cosmic explosion creating the world is especially suggestive just in these days of wars and weapons all around. Nevertheless to declare such an initial event as the begin of the universe unexpectedly turns out to be extremely hard to explain when based on purely physical grounds. Though it is easy to envisage a granate explosion causing matter to fly apart in all directions from the center of the explosion, but as a total surprise it is extremely hard to explain which physically operating forces or pressures might be responsible to drive the initially highly compacted cosmic matter agglomeration apart of each other. If the explosion forces are imagined as due to acting thermal pressure forces of normal massive matter, then the needed pressures cannot be due to the extremely high temperatures of the condensed matter, because the thermal energy of relativistically hot matter, as relativity theory tells us, will act as an additional source of gravity, i.e. making matter even "heavier"! Hence this just impedes the initial mass agglomeration to explode and fly apart. As we shall show in the following article the explosive BB- event can only physically be explained, if the necessary pressure is not conventionally realized by the temperature of the gravitating matter, but to the contrary by the immaterial cosmic vacuum. In fact - as we shall demonstrate here - without a cosmic vacuum pressure, the so-called Big-Bang never at all could have happened. Certainly vacuum pressure up to the present days of cosmology still is a fully speculative subject, but it will become evident in the following article, that without this highly speculative, physically handable quantity a primordial Big-Bang would not have happened at all.

Unimodular Theory of Gravity in Light of the Latest Cosmological Data

The unimodular theory of gravity is an alternative perspective to the traditional general relativity of Einstein and opens new possibilities for exploring its implications in cosmology. In this paper, we investigated Unimodular Gravity (UG) with the cosmological data from the Pantheon sample of Type Ia Supernovae (SNs) (2018), Baryon Acoustic Oscillations (BAOs), and the observational H(z) data from the Differential Age method (DA). We also used the Cosmic Microwave Background (CMB) distance priors from the Planck 2018 results. We considered a model consisting of a generalized cosmological constant, radiation, and a dark matter component along with normal matter. The considered theory respects only unimodular coordinate transformations. We first fit our model with low-redshift data from SNs and DA and determined the value of the model parameters (ξ,H0). We found the best-fit value of parameter ξ=6.03±0.40, which deviates slightly from 6, for which the theory becomes the standard general theory of relativity. We observed a small deviation in the value of the Hubble constant (H0=72.6±3.5 km s−1 Mpc−1) in the UG model compared with the standard ΛCDM model (H0=72.2±1.2 km s−1 Mpc−1). Using the BAO + CMB constraint in the UG model, we obtained H0=68.45±0.66kms−1Mpc−1, and ξ is ∼6.029. For the combined datasets (SN + DA + BAO + CMB), the estimated H0=69.01±0.60kms−1Mpc−1 with ξ∼6.037, and in standard gravity, H0=68.25±0.40kms−1Mpc−1.

Dark Matter is Just Gravity, Only Normal Matter is the truth Dark Matter is Just Gravity

All the major observational evidences available so far for the existence of dark matter can be explained by simple physical equations and derived astronomical data proving that dark matter theory is wrong. Furthermore, the normal matter is the only matter this is causing all the phenomena’s to happen that was previously believed to be due to unexplained dark matter. New general laws of physics for galactical rotation that cannot be explained by Kepler’s law alone is also derived.

Confirmation of an Anomalously Low Dark Matter Content for the Galaxy NGC 1052-DF4 from Deep, High-resolution Continuum Spectroscopy

NGC 1052-DF4 was found to be the second “galaxy lacking dark matter” in the NGC 1052 group, based on its velocity dispersion of km s−1 as measured from the radial velocities of seven of its globular clusters. Here we verify this result by measuring the stellar velocity dispersion of the galaxy. We observed the diffuse stellar light in NGC 1052-DF4 with the Keck Cosmic Web Imager in its highest-resolution mode, with km s−1. With a total science + sky exposure time of 34 hr, the resulting spectrum is exceptional in both its spectral resolution and its signal-to-noise ratio of 23 Å−1. We find a stellar velocity dispersion of km s−1, consistent with the previous measurement from the globular clusters. Combining both measurements gives a fiducial dispersion of km s−1. The implied dynamical mass within the half-light radius is . The expected velocity dispersion of NGC 1052-DF4 from the stellar mass alone is 7 ± 1 km s−1, and for a Navarro–Frenk–White (NFW) halo that follows the stellar mass–halo mass relation and the halo mass–concentration relation, the expectation is ∼30 km s−1. The low velocity dispersion rules out a normal NFW dark matter halo, and we confirm that NGC 1052-DF4 is one of at least two galaxies in the NGC 1052 group that have an anomalously low dark matter content. While any viable model for their formation should explain the properties of both galaxies, we note that NGC 1052-DF4 now poses the largest challenge, as it has the most stringent constraints on its dynamical mass.

Quantitative GABA magnetic resonance spectroscopy as a measure of motor learning function in the motor cortex after subarachnoid hemorrhage.

The neural mechanisms underlying gross and fine motor dysfunction after subarachnoid hemorrhage (SAH) remain unknown. The γ-aminobutyric acid (GABA) deficit hypothesis proposes that reduced neuronal GABA concentrations and the subsequent lack of GABA-mediated inhibition cause motor impairment after SAH. This study aimed to explore the correlation between GABA levels and a behavioral measure of motor performance in patients with SAH. Motor cortical GABA levels were assessed in 40 patients with SAH and 10 age-matched healthy controls using proton magnetic resonance spectroscopy. The GABA and N-acetylasparate (NAA) ratio was measured in the normal gray matter within the primary motor cortex. The relationship between GABA concentration and hand-motor performance was also evaluated. Results showed significantly lower GABA levels in patients with SAH's left motor cortex than in controls (GABA/NAA ratio: 0.282 ± 0.085 vs. 0.341 ± 0.031, respectively; p = 0.041). Reaction times (RTs), a behavioral measure of motor performance potentially dependent on GABAergic synaptic transmission, were significantly longer in patients than in controls (936.8 ± 303.8 vs. 440.2 ± 67.3 ms, respectively; p < 0.001). Moreover, motor cortical GABA levels and RTs exhibited a significant positive linear correlation among patients (r = 0.572, rs = 0.327, p = 0.0001). Therefore, a decrease in GABA levels in the primary motor cortex after SAH may lead to impaired cortical inhibition of neuronal function and indicates that GABA-mediated synaptic transmission in the motor cortex is critical for RT.

Traversable Lorentzian wormhole on the Shtanov-Sahni braneworld with matter obeying the energy conditions

In this paper we have explored the possibility of constructing a traversable wormhole on the Shtanov-Sahni braneworld with a timelike extra dimension. We find that the Weyl curvature singularity at the throat of the wormhole can be removed with physical matter satisfying the NEC ρ + p ≥ 0, even in the absence of any effective Λ-term or any type of charge source on the brane. (The NEC is however violated by the effective matter description on the brane arising due to effects of higher dimensional gravity.) Besides satisfying NEC the matter constituting the wormhole also satisfies the Strong Energy Condition (SEC), ρ + 3p ≥ 0, leading to the interesting possibility that normal matter on the brane may be harnessed into a wormhole. Incidentally, these conditions also need to be satisfied to realize a non-singular bounce and cyclic cosmology on the brane [1] where both past and future singularities can be averted. Thus, such a cyclic universe on the brane, constituted of normal matter can naturally contain wormholes. The wormhole shape function on the brane with a time-like extra dimension represents the tubular structure of the wormhole spreading out at large radial distances much better than in wormholes constructed in a braneworld with a spacelike extra dimension and have considerably lower mass resulting in minimization of the amount of matter required to construct a wormhole. Wormholes in the Shtanov-Sahni (SS) braneworld also have sufficiently low tidal forces, facilitating traversability. Additionally they are found to be stable and exhibit a repulsive geometry. We are left with the intriguing possibility that both types of curvature singularity can be resolved with the SS model, which we discuss at the end of the concluding section.

Emerging Newtonian potential in pure R2 gravity on a de Sitter background

In [27] Alvarez-Gaume et al. established that pure mathcal{R} 2 theory propagates massless spin-2 graviton on a de Sitter (dS) background but not on a locally flat background. We build on this insight to derive a Newtonian limit for the theory. Unlike most previous works that linearized the metric around a locally flat background, we explicitly employ the dS background to start with. We directly solve the field equation of the action {left(2kappa right)}^{-1}int {d}^4xsqrt{-g}{mathcal{R}}^2 coupled with the stress-energy tensor of normal matter in the form Tμν = Mc2δ( overrightarrow{r} ) {delta}_{mu}^0{delta}_{nu}^0 . We obtain the following Schwarzschild-de Sitter metric d{s}^2=-left(1-frac{Lambda}{3}{r}^2-frac{kappa {c}^2}{48pi Lambda}frac{M}{r}right){c}^2d{t}^2+{left(1-frac{Lambda}{3}{r}^2-frac{kappa {c}^2}{48pi Lambda}frac{M}{r}right)}^{-1}d{r}^2+{r}^2d{varOmega}^2 which features a potential V(r)=-frac{kappa {c}^4}{96pi Lambda}frac{M}{r} with the correct Newtonian tail. The parameter Λ plays a dual role: (i) it sets the scalar curvature for the background dS metric, and (ii) it partakes in the Newtonian potential V(r). We reach two key findings. Firstly, the Newtonian limit only emerges owing to the de Sitter background. Most existing studies of the Newtonian limit in modified gravity chose to linearize the metric around a locally flat background. However, this is a false vacuum to start with for pure mathcal{R} 2 gravity. These studies unknowingly omitted the information about Λ of the de Sitter background, hence incapable of attaining a Newtonian behavior in pure mathcal{R} 2 gravity. Secondly, as Λ appears in V(r) in a singular manner, viz. V(r) ∝ Λ−1, the Newtonian limit for pure mathcal{R} 2 gravity cannot be obtained by any perturbative approach treating Λ as a small parameter.

Evaluate the Mystery of Creation of Universe and Existence of Antimatter, Dark Matter and Dark Energy

We know relatively little about the cosmos. What we know about what we don’t know is even more tenuous. Antimatter is just matter with some properties swapped, such as electric charge. The positron serves as the antimatter counterpart to the electron, displaying a remarkable similarity in mass while possessing contrasting electric charges. Antimatter differs from regular matter in that it annihilates when it collides with regular matter. For instance, a proton and a positron have a lot in common. Both of them are of regular mass. They each possess a positive electric charge of equal strength. They both have one-half quantum spin. When a proton and an electron collide, a stable hydrogen atom is produced. When a positron and an electron collide, they destroy each other. The main distinction is that a positron is antimatter while a proton is matter. Knowledge dark matter and dark energy is critical for gaining a fundamental knowledge of the shape, structure, and properties of our Earth, galaxy, and universe. By fitting a theoretical model of the universe’s composition to the combined set of cosmological measurements, scientists found that the cosmos has around sixty-eight percent of dark energy, twenty-seven percent of dark matter, and five percent of normal matter. We should never touch our anti-self because we will perish if we do. It is a thoughtful and analytical article that draws on the knowledge and insight of scientists, physicists, technologists, and inventors about how the universe, dark energy, dark matter, antimatter and matter were formed. This knowledge will help in the development of new technologies for the civilization and prosperity of our precious planet Earth.

Tau influences the severity of delusions in older persons with early‐stage cognitive decline

AbstractBackgroundThe relationship between delusional severity and structural brain changes in patients with cognitive decline is unclear. In prior work by our group, we conducted texture and volume analysis of Normal Appearing Brain Matter (NABM) using FLAIR MRI sequences in a cognitively impaired delusional cohort. Our results demonstrated that with more severe delusions, greater global brain disease burden and tissue degeneration in NABM is apparent. In this study we examined the relationship between our findings and neurodegenerative biomarkers, ApoE4 and plasma tau.MethodsA total of 42 patients with Alzhiemer’s disease (AD) or Mild Cognitive Impairment (MCI) with delusions as identified by the Neuropsychiatric Inventory‐Quick version (NPI‐Q) were selected from the Alzheimer’s Disease Neuroimaging Initiative (ADNI). From fluid‐attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI) images, Brain extraction and intensity standardization alghorthims were applied to extract the normal‐appearing brain matter (NABM). Three biomarkers were measured from the NABM region, which included volume and two texture features called integrity and damage that measure the structural integrity of tissue and tissue damage. Statistical analysis included a multivariable stepwise regression of each biomarker as a dependent variable across delusional severity groups 1 (lowest severity) to 3 (highest severity) and the inclusion of sex, age, education, ApoE4 and plasma tau as co‐variates.ResultsData were gathered on the 42 participants representing 164 MRI scans. Significant associations were found between baseline plasma tau, delusional severity group 3 for the NABM integrity and volume biomarkers (p&lt;.05). Additionally, ApoE4 homozygotes were signficantly associated to NABM volume, integrity and damage, though no association was found with delusional severity.ConclusionThese findings suggest that plasma tau may be linked to both delusional severity and structural alterations within the NABM while ApoE4 status is more strongly associated with structural alterations in the NABM with no effect on delusional severity. Further longitudinal studies are required to establish plasma tau associated mechanisms of delusional severity.

Quark matter supported wormhole in third order Lovelock gravity

It is generally believed that wormholes are supported by exotic matter violating Null Energy Condition (NEC). However, various studies of wormhole geometries under Lovelock theories of gravity have reported existence of wormhole supported by matter satisfying NEC. Being inspired by these results, we explore the possibility of the existence of wormhole supported by normal quark matter in third order Lovelock gravity theory. Well known MIT Bag Model Equation of state is chosen for describing the quark matter. Taking physically acceptable approximations, we solve the field equations for shape function which satisfies flare out condition. The residual of the approximate solution is studied for accuracy and found to be acceptable.

Properties of strange quark matter and strange star in a new mass scaling

Previous research studies observed that quark mass scalings typically neglect the inclusion of asymptotic freedom. However, we have introduced a Woods–Saxon-like factor to incorporate the effects of asymptotic freedom into our new mass scaling. Our findings indicate that the equation of state and sound velocity for strange quark matter exhibit different behaviors at zero temperature when using this new mass scaling. This suggests the presence of novel properties in the phase transition and structure of strange stars. Additionally, through numerical calculations, we have successfully obtained a strange star with a mass two times that of the Sun, aligning with astronomical observations. In a parameter group considering first-order perturbation effects, characterized by large C and small D, we have made an interesting discovery: the surface density of the strange star can be lower than that of normal nuclear matter. This observation serves as a possible signal of a phase transition from quark matter to nuclear matter.

Matter-antimatter rearrangements using the R-matrix method

Antihydrogen atoms, H―, are now routinely created and can be stored for long enough to allow comparison with ordinary matter. A major goal of these efforts is to test potential physics beyond the Standard Model. This will require further developments in the experiments including the accumulation of more antihydrogen atoms and their storage over longer times. The latter is limited by the unavoidable presence of normal hydrogen molecules. Interactions of H― with H2 lead to the destruction of the hard-won antimatter. Little is known about these interactions but quantitative information will be crucial in guiding experimental developments. Physically realistic modelling of rearrangement scattering of “heavy” antimatter particles (antiprotons, p―, and antihydrogen atoms) by normal matter molecules, such as H2 + H―→ Pn + Ps + H (where Pn represents protonium and Ps positronium), requires the development of new theoretical and computational methodologies. R-matrix theory offers a strong prospect for tackling such problems having proved itself in atomic, molecular and optical physics. It divides the problem into a computationally demanding but energy-independent inner region and simpler energy-dependent outer regions. We propose to adapt the new RmatReact ultracold chemistry approach for the more complex molecular matter-antimatter problems. Here, developments required for the inner region, the boundary and outer regions are outlined. We also report some preliminary bound-state calculations on the {p,p,p―} system and a study of the required mixed coordinate systems for the general effective 3-body case and their transformations at the R-matrix boundary surfaces.

Yukawa–Casimir wormholes in 4-D Einstein Gauss–Bonnet gravity

It is an undeniable fact that the negative energy source is essential for the stability of traversable wormholes. Recently, it has been shown that the Casimir energy which is the only artificial source of negative energy till date, could source the negative energy to the traversable wormholes as well. In this paper, we explore the possibility of non-exotic traversable wormholes in 4-D EGB gravity. We use the Yukawa–Casimir shape function and investigate the various energy conditions. We observe that for appropriate choices of shape function and the parameters, traversable wormholes with normal matter at throat can be found.

Constraint of the Nuclear Dissipation Coefficient in Fission of Hypernuclei.

Experimental studies of nuclear fission induced by fusion, transfer, spallation, fragmentation, and electromagnetic reactions in combination with state-of-the-art calculations are successful to investigate the nuclear dissipation mechanism in normal nuclear matter, containing only nucleons. The dissipation mechanism has been widely studied by the use of many different fission observables and nowadays the dissipation coefficients involved in transport theories are well constrained. However, the existence of hypernuclei and the possible presence of hyperons in neutron stars make it necessary to extend the investigation of the nuclear dissipation coefficient to the strangeness sector. In this Letter, we use fission reactions of hypernuclei to constrain for the first time the dissipation coefficient in hypernuclear matter, observing that this coefficient increases a factor of 6 in the presence of a single Λ hyperon with respect to normal nuclear matter.

(Anti)kaon condensation in strongly magnetized dense matter

Recent observations of several massive pulsars, with masses near and above $2~M_\odot$, point towards the existence of matter at very high densities, compared to normal matter that we are familiar with in our terrestrial world. This leads to the possibility of appearance of exotic degrees of freedom other than nucleons inside the core of the neutrons stars (NS). Another significant property of NSs is the presence of high surface magnetic field, with highest range of the order of $\sim~10^{16}$ G. We study the properties of highly dense matter with the possibility of appearance of heavier strange and non-strange baryons, and kaons in presence of strong magnetic field. We find that the presence of a strong magnetic field stiffens the matter at high density, delaying the kaon appearance and, hence, increasing the maximum attainable mass of NS family.

Dark Energy Star: Physical Constraints on the Bounds

AbstractIn the present article, we explore a new solution to the Einstein‐Maxwell field equations to describe spherically symmetric, charged and anisotropic dark energy stars. The interior of such stars containing two non‐interacting fluids like dark and normal matter with a relation that the dark energy density is proportional to the energy density of a isotropic matter. We have used modified chaplygin gas equation to define the dark energy part. Also we have defined the interior space‐time through Krori‐Barua (KB) space‐time and matched it with the exterior Reissner‐Nordström space‐time. The well‐behaveness of the physical attributes have been discussed by plotting graphs for three specific compact objects with respect to our solutions. We conclude that all the physical attributes satisfy the required conditions for viability as well as stability and hence our model can be used to characterize dark energy stars for a set of parametric values belong to the present study.

Accretion-induced Collapse of Dark Matter-admixed Rotating White Dwarfs: Dynamics and Gravitational-wave Signals

We present two-dimensional hydrodynamic simulations of the accretion-induced collapse (AIC) of rotating white dwarfs admixed with an extended component of dark matter (DM) comprising sub-gigaelectronvolt degenerate fermionic DM particles. We find that the DM component follows the collapse of the normal matter (NM) component to become a bound DM core. Thus, we demonstrate how a DM-admixed neutron star could form through DM-admixed AIC (DMAIC) for the first time, with the dynamics of DM taken into account. The gravitational-wave (GW) signature from the DMAIC shows distinctive features. In the diffusive DM limit, the DM admixture indirectly suppresses the post-bounce spectral peak of the NM GWs. In the compact DM limit, the collapse dynamics of the DM in a Milky Way event generate GWs that are strong enough to be detectable by Advanced LIGO as continuous low-frequency (<1000 Hz) signals after the NM core bounce. Our study not only is the first-ever computation of GW from a collapsing DM object but also provides the key features to identify DM in AIC events through future GW detections.

The impact of the dark matter on galaxy formation

Contemporarily, dark matter exerts dominant impacts on galaxy formation, which is the spine bone of the galaxy. Herein, we investigate the attraction effect of initial dark matter distribution on the normal matter (hydrogen and other gases), which will form the dark matter halos. Subsequently, an introduction to the properties of dark matter halos and some disputes about it are demonstrated. Besides, the cold dark matter (CDM) is chosen to fit the current observation and interpret the influences of dark matter on galaxy formation. Overall, this paper offers a clear procession of the impact of dark matter on galaxy formation, which will be guideline for future development of both galaxy formation theory as well as dark matter detection.