Matter Clumps Research Articles

Probing primordial black holes and dark matter clumps in the Solar System with gravimeter and Global Navigation Satellite Systems networks

Probing primordial black holes and dark matter clumps in the Solar System with gravimeter and Global Navigation Satellite Systems networks

Correction to: Neutron star mass in dark matter clumps

Correction to: Neutron star mass in dark matter clumps

Supernovae and superbursts triggered by dark matter clumps

Cosmologies in which dark matter clumps strongly on small scales are unfavorable to terrestrial detectors that are as yet unexposed to the clumps. I show that subhectometer clumps could trigger thermonuclear runaways by scattering on nuclei in white dwarf cores (carbon and oxygen) and neutron star oceans (carbon), setting off type-Ia-like supernovae and x-ray superbursts, respectively. I consider two scenarios: “dark clusters” that are essentially microhalos and “long-range dark nuggets,” essentially macroscopic composites, with long-range Yukawa baryonic interactions that source the energy for igniting explosions. I constrain dark clusters, weighing between the Planck mass and asteroid masses, and long-range dark nuggets over a wider mass range spanning 40 orders of magnitude. These limits greatly complement searches proposed by myself and co-workers [] for scattering interactions of dark clumps in neutron stars, cosmic rays, and prehistoric minerals. Published by the American Physical Society 2024

The missing quasar image in the gravitationally lensed quasar HE0230−2130: Implications for the cored lens mass distribution and dark satellites

Strongly lensed systems with peculiar configurations allow us to probe the local properties of the deflecting lens mass while simultaneously testing general profile assumptions. The quasar HE0230−2130 is lensed by two galaxies at similar redshifts (Δz ∼ 0.003) into four observed images. Using modeled quasar positions from fitting the brightness of the quasar images in ground-based imaging data from the Magellan telescope, we find that lens-mass models where each of these two galaxies is parametrized with a singular power-law (PL) profile predict five quasar images. One of the predicted images is unobserved despite it being distinctively offset from the lensing galaxies and likely bright enough to be observable. This missing image gives rise to new opportunities to study the mass distribution of these galaxies. To interpret the quad configuration of the system, we tested 12 different profile assumptions with the aim of obtaining lens-mass models that correctly predict only four observed images. We tested the effects of adopting: cored profiles for the lensing galaxies; external shear; and additional profiles to represent a dark matter clump. We find that half of our model classes can produce the correct image multiplicity. By comparing the Bayesian evidence of different model parametrizations, we favor two model classes: (i) one that incorporates two singular PL profiles for the lensing galaxies and a cored isothermal sphere in the region of the previously predicted fifth image (rNIS profile), and (ii) one with a bigger lensing galaxy parametrized by a singular PL profile and the smaller galaxy by a cored PL profile with external shear. We estimated the mass of the rNIS clump for each candidate model of our final Markov chain Monte Carlo sample, and find that only 2% are in the range of 106 M⊙ ≤ MrNIS ≤ 109 M⊙, which is the predicted mass range of dark matter subhalos in cold dark matter simulations, or the mass of dark-matter-dominated and low-surface-brightness galaxies. We therefore favor the models with a cored mass distribution for the lens galaxy close to the predicted fifth image. Our study further demonstrates that lensed quasar images are sensitive to the dark matter structure in the gravitational lens. We are able to describe this exotic lensing configuration with relatively simple models, which demonstrates the power of strong lensing for studying galaxies and lens substructure.

Searching for large dark matter clumps using the Galileo Constellation clock variations

This study presents bounds on transient variations of fundamental constants, with typical timescales ranging from minutes to months, using clocks in space. The underlying phenomenology describing such transient variations relies on models for Dark Matter (DM) which suggest possible encounters of macroscopic compact objects with the Earth, due to the motion of the solar system in the galactic halo. If such compact objects possess an effective feeble interaction with the ordinary matter beyond the gravitational one, it may result in effective transient variations of fundamental constants. Such variations leave signatures on clocks onboard GNSS satellites. In this paper, we introduce a phenomenological study dedicated to the search for such DM transient objects using the network of passive hydrogen masers (H-Masers) onboard Galileo satellites. We first model the signature of transient variations of fundamental constants as a frequency modulation in the difference between two satellite clocks, considering the satellite trajectories relative to the transient event. Then, we present first results based on a fast analysis method, the maximum reach analysis. The main result is a significant extension of the discovery range for DM transients, with a sensitivity never achieved before. We investigate indeed the range of transient sizes from 105 to 109 kilometres, which, apart from indirect and model-dependent non-transient effects, has never been explored previously.

Millimeter-wave CO and SiO Observations toward the Broad-velocity-width Molecular Feature CO 16.134–0.553: A Smith Cloud Scenario?

We report the results of the CO J = 1–0 and SiO J = 2–1 mapping observations toward the broad-velocity-width molecular feature (BVF) CO 16.134–0.553 with the Nobeyama Radio Observatory 45 m telescope. The high-quality CO map shows that the 5 pc size BVF bridges two separate velocity components at V LSR ≃ 40 km s−1 and 65 km s−1 in the position–velocity space. The kinetic power of CO 16.134–0.553 amounts to 7.8 × 102 L ⊙, whereas no apparent driving sources were identified. Prominent SiO emission was detected from the BVF and its root in the V LSR ≃ 40 km s−1 component. In the CO Galactic plane survey data, CO 16.134–0.553 appears to correspond to the Galactic eastern rim of a 15 pc diameter expanding CO shell. A 1° diameter H i emission void and 4° long vertical H i filament were also found above and below the CO shell, respectively. We propose that the high-velocity plunge of a dark matter subhalo with a clump of baryonic matter was responsible for the formation of the H i void, CO 16.134–0.553/CO shell, and the H i filament.

Neutron star mass in dark matter clumps

ABSTRACT This paper investigates a hypothesis proposed in previous research relating neutron star (NS) mass and its dark matter (DM) accumulation. As DM accumulates, NS mass decreases, predicting lower NS masses toward the Galactic centre. Due to limited NSs data near the Galactic centre, we examine NSs located within DM clumps. Using the CLUMPY code simulations, we determine the DM clumps distribution, with masses from 10 to 108 M⊙ and scales from 10−3 to 10 kpc. These clumps’ DM exhibit a peak at the centre, tapering toward the outskirts, resembling our Galaxy’s DM distribution. We analyse these DM clumps’ NS mass variations, considering diverse DM particle masses and galaxy types. We find relatively stable NS mass within 0.01 – 5 kpc from the clump centre. This stability supports the initial hypothesis, particularly for NSs located beyond 0.01 kpc from the clump centre, where NS mass reaches a plateau around 0.1 kpc. Nevertheless, NS mass near the clump’s periphery reveals spatial dependence: NS position within DM clumps influences its mass in Milky Way-type galaxies. Moreover, this dependence varies with the DM model considered. In summary, our study investigates the proposed link between NS mass and DM accumulation by examining NSs within DM clumps. While NS mass remains stable at certain distances from the clump centre, spatial dependencies arise near the clump’s outer regions, contingent on the specific DM model.

Self-similar solutions for fuzzy dark matter

Self-similar solutions for fuzzy dark matter are very different from their counterparts in the standard cold dark matter model. In contrast to the familiar hierarchical collapse of the current model for structure formation, they correspond to an inverse hierarchical blow-up. This fact highlights the gravitational cooling process, which in the absence of dissipation, allows the system to eject excess energy through the intermittent expulsion of clumps of matter. These surprising behaviours are due to the wave properties of the Schrödinger equation and to the quantum pressure. These features are printed in the Eulerian density-velocity representation of the nonrelativistic scalar field, or in the Lagrangian representation in the mass-shell trajectories.

First Ejection from the PSR B1259-63/LS 2883 High Mass Gamma-Ray Binary Detected During the 2021–2024 Binary Cycle

LS 2883/PSR B1259-63 is a high mass, eccentric gamma-ray binary that has previously been observed to eject X-ray emitting material. We report the results of recent Chandra observations near binary apastron in which a new X-ray emitting clump of matter was detected. The clump has a high projected velocity of v ⊥ ≈ 0.07c and hard X-ray spectrum, which fits an absorbed power-law model with Γ = 1.1 ± 0.3. Although clumps with similar velocities and spectra were detected in some of the previous binary cycles, no resolved clumps were seen near apastron in the preceding cycle of 2017–2021.

Small-scale clumping of dark matter and the mean free path of ionizing photons at z = 6

Recently, the mean free path of ionizing photons in the z = 6 intergalactic medium (IGM) was measured to be very short, presenting a challenge to existing reionization models. At face value, the measurement can be interpreted as evidence that the IGM clumps on scales M ≲ 108 M ⊙, a key but largely untested prediction of the cold dark matter (CDM) paradigm. Motivated by this possibility, we study the role that the underlying dark matter cosmology plays in setting the z > 5 mean free path. We use two classes of models to contrast against the standard CDM prediction: (1) thermal relic warm dark matter (WDM), representing models with suppressed small-scale power; (2) an ultralight axion exhibiting a white noise-like power enhancement. Differences in the mean free path between the WDM and CDM models are subdued by pressure smoothing and the possible contribution of neutral islands to the IGM opacity. For example, comparing late reionization scenarios with a fixed volume-weighted mean neutral fraction of 20% at z = 6, the mean free path is 19 (45)% longer in a WDM model with mx = 3 (1) keV. The enhanced power in the axion-like model produces better agreement with the short mean free path measured at z = 6. However, drawing robust conclusions about cosmology is hampered by large uncertainties in the reionization process, extragalactic ionizing background, and thermal history of the Universe. This work highlights some key open questions about the IGM opacity during reionization.

A self-consistent wave description of axion miniclusters and their survival in the galaxy

We present a solution of the Schrödinger-Poisson system based on the WKB ansatz for the wave function. In this way we obtain a description of a gravitationally bound clump of axion dark matter by a superposition of energy eigenstates with random phases. It can be applied to any self-consistent pair of radial density distribution and phase space density f(E) related by Eddington's formula. We adopt this as a model for axion miniclusters in our galaxy and use it to study the mass loss due to a star encounter by using standard perturbation theory methods known from quantum mechanics. Finally, we perform a Monte Carlo study to estimate the surviving fraction of axion miniclusters in the dark matter halo of our galaxy. We find that the reaction to perturbations and the survival probability depend crucially on the density profile. Weakly bound clusters are heated up and eventually destroyed, whereas more strongly bound systems get even more compact as a result of perturbations and are driven towards an axion star configuration.

Dark matter in galaxy clusters: Parametric strong-lensing approach

We present a parametric strong-lensing analysis of three massive galaxy clusters for which Hubble Space Telescope imaging is available, as well as spectroscopy of multiply imaged systems and galaxy cluster members. Our aim is to probe the inner shape of dark matter haloes, in particular the existence of a core. We adopted the following working hypothesis: any group- or cluster-scale dark matter clump introduced in the modelling should be associated with a luminous counterpart. We also adopted some additional well-motivated priors in the analysis, even when this degraded the quality of the fit, quantified using the root mean square between the observed and model-generated images. In particular, in order to alleviate the degeneracy between the smooth underlying component and the galaxy-scale perturbers, we used the results from previous spectroscopic campaigns, which allowed us to fix the mass of the galaxy-scale component. In the unimodal galaxy cluster AS 1063, a core mass model is favoured over a non-core mass model, and this is also the case in the multimodal cluster MACS J0416. In the unimodal cluster MACS J1206, we fail to reproduce the strong-lensing constraints using a parametric approach within the adopted working hypothesis. We then successfully added a mild perturbation in the form of a superposition of B-spline potentials, which allowed us to obtain a decent fit (root mean square = 0.5″), and finally find that a core mass model is favoured. Overall, our analysis suggest evidence for core cluster-scale dark matter haloes in these three clusters. These findings may be useful for the interpretation within alternative dark matter scenario, such as self-interacting dark matter. We propose a working hypothesis for parametric strong-lensing modelling in which the quest for the best-fit model is balanced by the quest for presenting a physically motivated mass model, in particular by imposing priors.

The Bohmian Approach to the Problems of Cosmological Quantum Fluctuations

There are two kinds of quantum fluctuations relevant to cosmology that we focus on in this article: those that form the seeds for structure formation in the early universe and those giving rise to Boltzmann brains in the late universe. First, structure formation requires slight inhomogeneities in the density of matter in the early universe, which then get amplified by the effect of gravity, leading to clumping of matter into stars and galaxies. According to inflation theory, quantum fluctuations form the seeds of these inhomogeneities. However, these quantum fluctuations are described by a quantum state which is homogeneous and isotropic, and this raises a problem, connected to the foundations of quantum theory, as the unitary evolution alone cannot break the symmetry of the quantum state. Second, Boltzmann brains are random agglomerates of particles that, by extreme coincidence, form functioning brains. Unlikely as these coincidences are, they seem to be predicted to occur in a quantum universe as vacuum fluctuations if the universe continues to exist for an infinite (or just very long) time, in fact to occur over and over, even forming the majority of all brains in the history of the universe. We provide a brief introduction to the Bohmian version of quantum theory and explain why in this version, Boltzmann brains, an undesirable kind of fluctuation, do not occur (or at least not often), while inhomogeneous seeds for structure formation, a desirable kind of fluctuation, do.

Cosmological milestones, conformal frameworks and quiescent cosmology.

To understand the nature of the birth of our Universe and its eventual demise is a driving force in theoretical physics and astronomy and, indeed, for humanity. A zoo of definitions has appeared in the literature to catalogue different types of cosmological milestones such as 'Big Bangs', 'Big Crunches', 'Big Rips', 'Sudden Singularities', 'Bounces' and 'Turnarounds'. Quiescent cosmology is the notion that the Universe commenced in a Big Bang that was highly regular and smooth, and evolved away from this initial isotropy and homogeneity due to gravitational attraction. The quiescent cosmology concept meshes well with Penrose's ideas regarding gravitational entropy and the clumping of matter, and the associated Weyl Curvature Hypothesis. Conformal frameworks, such as the Isotropic Past Singularity (IPS), have been devised to encapsulate initial and final states for the Universe which are in accordance with these programmes. These geometric definitions are independent of models, coordinates and the equation of state of the source of the gravitational field. Much of the research on cosmological milestones has been focussed on the FRW solutions, many of which possess initial singularities which are isotropic Big Bangs. We analyse here the relationship between cosmological milestones and conformal frameworks for these solutions. We establish the general properties of FRW models which admit these conformal frameworks, including whether they satisfy various energy conditions, and are therefore physically reasonable. These results inform future development of the quiescent cosmology program. This article is part of the theme issue 'The future of mathematical cosmology, Volume 1'.

Probing dark matter clumps, strings and domain walls with gravitational wave detectors

Gravitational wave astronomy has recently emerged as a new way to study our Universe. In this work, we survey the potential of gravitational wave interferometers to detect macroscopic astrophysical objects comprising the dark matter. Starting from the well-known case of clumps we expand to cosmic strings and domain walls. We also consider the sensitivity to measure the dark matter power spectrum on small scales. Our analysis is based on the fact that these objects, when traversing the vicinity of the detector, will exert a gravitational pull on each node of the interferometer, in turn leading to a differential acceleration and corresponding Doppler signal, that can be measured. As a prototypical example of a gravitational wave interferometer, we consider signals induced at LISA. We further extrapolate our results to gravitational wave experiments sensitive in other frequency bands, including ground-based interferometers, such as LIGO, and pulsar timing arrays, e.g. ones based on the Square Kilometer Array. Assuming moderate sensitivity improvements beyond the current designs, clumps, strings and domain walls may be within reach of these experiments.

Looking through the photoionisation wake: Vela X−1 at φorb ≈ 0.75 with Chandra/HETG

Context. The supergiant X-ray binary Vela X−1 represents one of the best astrophysical sources to investigate the wind environment of an O/B star irradiated by an accreting neutron star. Previous studies and hydrodynamic simulations of the system have revealed a clumpy environment and the presence of two wakes: an accretion wake surrounding the compact object and a photoionisation wake trailing it along the orbit. Aims. Our goal is to conduct, for the first time, high-resolution spectroscopy on Chandra/HETGS data at the orbital phase φorb ≈ 0.75, when the line of sight is crossing the photoionisation wake. We aim to conduct plasma diagnostics, inferring the structure and the geometry of the wind. Methods. We performed a blind search employing a Bayesian block algorithm to find discrete spectral features and identify them thanks to the most recent laboratory results or through atomic databases. Plasma properties were inferred both with empirical techniques and with photoionisation models within CLOUDY and SPEX. Results. We detect and identify five narrow radiative recombination continua (Mg XI-XII, Ne IX-X, O VIII) and several emission lines from Fe, S, Si, Mg, Ne, Al, and Na, including four He-like triplets (S XV, Si XIII, Mg XI, and Ne IX). Photoionisation models reproduce the overall spectrum well, except for the near-neutral fluorescence lines of Fe, S, and Si. Conclusions. We conclude that the plasma is mainly photoionised, but more than one component is most likely present, which is consistent with a multi-phase plasma scenario, where denser and colder clumps of matter are embedded in the hot, photoionised wind of the companion star. Simulations with the future X-ray satellites Athena and XRISM show that a few hundred seconds of exposure is sufficient to disentangle the lines of the Fe Kα doublet and the He-like Fe XXV, improving, in general, the determination of the plasma parameters.

The Abell 3391/95 galaxy cluster system

Context.Inferences about dark matter, dark energy, and the missing baryons all depend on the accuracy of our model of large-scale structure evolution. In particular, with cosmological simulations in our model of the Universe, we trace the growth of structure, and visualize the build-up of bigger structures from smaller ones and of gaseous filaments connecting galaxy clusters.Aims.Here we aim to reveal the complexity of the large-scale structure assembly process in great detail and on scales from tens of kiloparsecs up to more than 10 Mpc with new sensitive large-scale observations from the latest generation of instruments. We also aim to compare our findings with expectations from our cosmological model.Methods.We used dedicated SRG/eROSITA performance verification (PV) X-ray, ASKAP/EMU Early Science radio, and DECam optical observations of a ~15 deg2region around the nearby interacting galaxy cluster system A3391/95 to study the warm-hot gas in cluster outskirts and filaments, the surrounding large-scale structure and its formation process, the morphological complexity in the inner parts of the clusters, and the (re-)acceleration of plasma. We also used complementary Sunyaev-Zeldovich (SZ) effect data from thePlancksurvey and custom-made Galactic total (neutral plus molecular) hydrogen column density maps based on the HI4PI and IRAS surveys. We relate the observations to expectations from cosmological hydrodynamic simulations from the Magneticum suite.Results.We trace the irregular morphology of warm and hot gas of the main clusters from their centers out to well beyond their characteristic radii,r200. Between the two main cluster systems, we observe an emission bridge on large scale and with good spatial resolution. This bridge includes a known galaxy group but this can only partially explain the emission. Most gas in the bridge appears hot, but thanks to eROSITA’s unique soft response and large field of view, we discover some tantalizing hints for warm, truly primordial filamentary gas connecting the clusters. Several matter clumps physically surrounding the system are detected. For the “Northern Clump,” we provide evidence that it is falling towards A3391 from the X-ray hot gas morphology and radio lobe structure of its central AGN. Moreover, the shapes of these X-ray and radio structures appear to be formed by gas well beyond the virial radius,r100, of A3391, thereby providing an indirect way of probing the gas in this elusive environment. Many of the extended sources in the field detected by eROSITA are also known clusters or new clusters in the background, including a known SZ cluster at redshiftz= 1. We find roughly an order of magnitude more cluster candidates than the SPT and ACT surveys together in the same area. We discover an emission filament north of the virial radius of A3391 connecting to the Northern Clump. Furthermore, the absorption-corrected eROSITA surface brightness map shows that this emission filament extends south of A3395 and beyond an extended X-ray-emitting object (the “Little Southern Clump”) towards another galaxy cluster, all at the same redshift. The total projected length of this continuous warm-hot emission filament is 15 Mpc, running almost 4 degrees across the entire eROSITA PV observation field. The Northern and Southern Filament are each detected at >4σ. ThePlanckSZ map additionally appears to support the presence of both new filaments. Furthermore, the DECam galaxy density map shows galaxy overdensities in the same regions. Overall, the new datasets provide impressive confirmation of the theoretically expected structure formation processes on the individual system level, including the surrounding warm-hot intergalactic medium distribution; the similarities of features found in a similar system in the Magneticum simulation are striking. Our spatially resolved findings show that baryons indeed reside in large-scale warm-hot gas filaments with a clumpy structure.

Gravitational waves from disks around spinning black holes: Simulations in full general relativity.

We present fully general-relativistic numerical evolutions of self-gravitating tori around spinning black holes with dimensionless spin a/M = 0.7 parallel or antiparallel to the disk angular momentum. The initial disks are unstable to the hydrodynamic Papaloizou-Pringle instability which causes them to grow persistent orbiting matter clumps. The effect of black hole spin on the growth and saturation of the instability is assessed. We find that the instability behaves similarly to prior simulations with nonspinning black holes, with a shift in frequency due to spin-induced changes in disk orbital period. Copious gravitational waves are generated by these systems, and we analyze their detectability by current and future gravitational wave observatories for a large range of masses. We find that systems of 10 M ⊙-relevant for black hole-neutron star mergers-are detectable by Cosmic Explorer out to ~300 Mpc, while DECIGO (LISA) will be able to detect systems of 1000 M ⊙ (105 M ⊙)-relevant for disks forming in collapsing supermassive stars-out to cosmological redshift of z ~ 5 (z ~ 1). Computing the accretion rate of these systems we find that these systems may also be promising sources of coincident electromagnetic signals.

Physical and chemical properties, elemental and material snow composition in Rostov-on-Don

To study the current distribution of the heavy metals (HM) levels and iron in the atmospheric precipitation in Rostov-on-Don, an expedition was conducted aimed at simultaneous river water and snow sampling in the Don River, the roadside and park areas. The pH values of the melt-water were characterized by a slightly acidic reaction, and the stale snow in the park had lower values in comparison with the fresh snow. The river water was slightly alkaline, and the concentrations of dissolved migration forms of Pb, Cd, Zn, Ni, Cr, Mn, and Fe did not exceed the MPC. The exception was the Cu content, which exceeded the MPC by 2.4 times. The contents of the dissolved migration forms of Pb, Cd, Zn, Cu, Ni, and Fe in snow exceeded their contents in river waters. The HM and Fe percentage in suspended form in river water and different snow states is calculated and the sequence series are constructed. The analysis showed that in melt-water, in comparison with river water, there is a higher percentage of the HM and iron in the solution. That may be due to the slightly acidic reaction of the snow water medium, which, as is known, promotes the HM and Fe mobilization from the suspension and their transition to the dissolved state. Using electron microscopy and X-ray phase analysis, the suspension composition in the snow of the park zone was studied, which is mainly represented by aggregates of clay minerals, quartz grains, water silicates, feldspars, and organic matter clumps.

КОМПЛЕКСНИЙ ФОРМАЛІЗМ У ТЕОРІЇ ГРАВІТАЦІЙНОГО ЛІНЗУВАННЯ І ГЕОМЕТРІЯ КАУСТИК

In the theory of gravitational lensing, the critical curves and caustics of the lens mapping are of particular interest. The most striking features of this phenomenon take place just when the source is in the vicinity of the caustic of the gravitational lens system. The main method for studying the properties of a lens mapping in the vicinity of a critical point is its approximation by a segment of a Taylor series in a special local coordinate system; this allows one to describe all the necessary properties with sufficient accuracy by means of a certain number of Taylor coefficients. In this article, we propose a general algorithm for calculating the mentioned coefficients directly in the original coordinates. The algorithm essentially uses the complex formulation of the lensing equations and the parameterization of critical curves, which was first proposed by Witt (1990). We analyzed the formula for the curvature of the caustic and introduced a closely related function D. For D > 0, the so-called positive side of the caustic neighborhood, whose points have two more images, corresponds to the convexity of the caustic, and for D < 0, to its concavity. The critical points, at which D = 0 , correspond to the inflection points of the caustic. The conditions for the critical point to be a cusp, as well as the positivity and negativity of the cusps are considered. The properties of caustics are illustrated with examples of the Chang-Refsdal lens and a simplified dark matter clump model.