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After years of null results in the search for dark matter, the biggest mystery of contemporary physics, a different prospective might be required beyond the standard WIMP paradigm. We present a new approach to estimate dark matter particle mass, size, density, and many other properties based on a cascade theory for the flow of dark matter, similar to the cascade in hydrodynamic turbulence. The energy cascade from small to large scales with a constant rate εu≈-4.6x10-7m2/s3is a fundamental feature of dark matter flow. Energy cascade leads to a two-thirds law for kinetic energy vr2≈(εur)2/3on scale r, as confirmed by N-body simulations. This is equivalent to a four-thirds law for mean halo density ρsenclosed in the halo scale radius rssuch that ρs≈εu2/3G-1rs-4/3, as confirmed by the data from galaxy rotation curves. By identifying key constants on relevant scales, properties of dark matter might be obtained. The smallest length scale in dark matter flow is dependent on the nature of dark matter. For collisionless dark matter, particle mass is estimated to be mX≈(-εuh5G4)1/9≈1012GeV with a size of rη≈(-εuhG)1/3≈10-13m, where h is the Planck constant. An uncertainty principle for momentum and acceleration fluctuations is also postulated to explain the physical origin of the rate of energy cascade εu. For self-interacting dark matter, the smallest structure has a sale rη≈εu2G-3(σ/m)3, where σ/m is the cross-section. On halo scale, the energy cascade leads to an asymptotic density slope γ=-4/3 for fully virialized halos with a vanishing radial flow, which might explain the nearly universal halo density. Based on the continuity equation, halo density is analytically shown to be closely dependent on the radial flow and mass accretion such that simulated halos can have different limiting slopes. A modified Einasto density profile is proposed accordingly. Accompanying slides and datasets for this work can be found at https://doi.org/10.5281/zenodo.6569901. Here are some applicationsof the cascade theory: Dark matter particle mass ,size, and properties from energy cascade in dark matter flow: 1) arxiv 2) zenodo slides Origin of MOND acceleration &deep-MOND fromacceleration fluctuation &energy cascade: 1) arxiv 2) zenodo slides The baryonic-to-halo mass relation from mass and energy cascade in dark matter flow: 1) arxiv 2) zenodo slides Universal scaling laws and density slope for dark matter halos from rotation curves: 1) arxiv 2) zenodo slides A unified theory for dark matter halo mass function and density profile: 1) arxiv 2) zenodo slides Energy cascade forevolution of host galaxy and supermassive black holes (SMBHs): 2) zenodo slides &nbsp

Supermassive black hole masses (MBH) can dynamically be estimated with various methods and using different kinematic tracers. Different methods have only been cross-checked for a small number of galaxies and often show discrepancies. To understand these discrepancies, detailed cross-comparisons of additional galaxies are needed. We present the first part of our cross-comparison between stellar- and gas-based MBH estimates in the nearby fast-rotating early-type galaxy NGC 6958. The measurements presented here are based on ground-layer adaptive optics-assisted Multi-Unit Spectroscopic Explorer (MUSE) science verification data at around 0.6 arcsec spatial resolution. The spatial resolution is a key ingredient for the measurement and we provide a Gaussian parametrisation of the adaptive optics-assisted point spread function (PSF) for various wavelengths. From the MUSE data, we extracted the stellar kinematics and constructed dynamical models. Using an axisymmetric Schwarzschild technique, we measured an MBH of (3.6+2.7-2.4)\times 10^8 Msun at 3\sigma significance taking kinematical and dynamical systematics (e.g.,radially-varying mass-to-light ratio) into account. We also added a dark halo, but our data does not allow to constrain the dark matter fraction. Adding dark matter with an abundance matching prior results in a 25 per cent more massive black hole. Jeans anisotropic models return MBH of (4.6+2.5-2.7) \times 10^8 Msun and (8.6+0.8-0.8) \times 10^8 Msun at 3\sigma confidence for spherical and cylindrical alignment of the velocity ellipsoid, respectively. In a follow-up study, we will compare the stellar-based MBH with those from cold and warm gas tracers, which will provide additional constraints for the MBH for NGC 6958, and insights into assumptions that lead to potential systematic uncertainty., Comment: Accepted for publication in MNRAS, 21 pages, 18 Figures (Including Appendix). Supplementary information is added at the end of the file (3 pages)

Different properties of dark matter haloes, including growth rate, concentration, interaction history, and spin, correlate with environment in unique, scale-dependent ways. While these halo properties are not directly observable, galaxies will inherit their host haloes' correlations with environment. In this paper, we show how these characteristic environmental signatures allow using measurements of galaxy environment to constrain which dark matter halo properties are most tightly connected to observable galaxy properties. We show that different halo properties beyond mass imprint distinct scale-dependent signatures in both the galaxy two-point correlation function and the distribution of distances to galaxies' $k$th nearest neighbours, with features strong enough to be accessible even with low-resolution (e.g., grism) spectroscopy at higher redshifts. As an application, we compute observed two-point correlation functions for galaxies binned by half-mass radius at $z=0$ from the Sloan Digital Sky Survey, showing that classic galaxy size models (i.e., galaxy size being proportional to halo spin) as well as other recent proposals show significant tensions with observational data. We show that the agreement with observed clustering can be improved with a simple empirical model in which galaxy size correlates with halo growth., Comment: 24 pages, MNRAS accepted

We study the relations between the mass of the central black hole (BH) $M_{\rm BH}$, the dark matter halo mass $M_{\rm h}$, and the stellar-to-halo mass fraction $f_\star\propto M_\star/M_{\rm h}$ in a sample of $55$ nearby galaxies with dynamically measured $M_{\rm BH}>10^6\,{\rm M}_\odot$ and $M_{\rm h}>5\times10^{11}\,{\rm M}_\odot$. The main improvement with respect to previous studies is that we consider both early- and late-type systems for which $M_{\rm h}$ is determined either from globular cluster dynamics or from spatially resolved rotation curves. Independently of their structural properties, galaxies in our sample build a well defined sequence in the $M_{\rm BH}$-$M_{\rm h}$-$f_\star$ space. We find that: (i) $M_{\rm h}$ and $M_{\rm BH}$ strongly correlate with each other and anti-correlate with $f_\star$; (ii) there is a break in the slope of the $M_{\rm BH}$-$M_{\rm h}$ relation at $M_{\rm h}$ of $10^{12}\,{\rm M}_\odot$, and in the $f_\star$-$M_{\rm BH}$ relation at $M_{\rm BH}$ of $\sim10^7\!-\!10^8\,{\rm M}_\odot$; (iii) at a fixed $M_{\rm BH}$, galaxies with a larger $f_\star$ tend to occupy lighter halos and to have later morphological types. We show that the observed trends can be reproduced by a simple equilibrium model in the $��$CDM framework where galaxies smoothly accrete dark and baryonic matter at a cosmological rate, having their stellar and black hole build-up regulated both by the cooling of the available gas reservoir and by the negative feedback from star formation and active galactic nuclei (AGN). Feature (ii) arises as the BH population transits from a rapidly accreting phase to a more gentle and self-regulated growth, while scatter in the AGN feedback efficiency can account for feature (iii)., 20 pages, 12 figures, accepted by MNRAS. Key figures are Fig.1 and Fig.6

We present observations and models of the kinematics and distribution of neutral hydrogen (HI) in the superthin galaxy FGC 1440 with an optical axial ratio $a/b = 20.4$. Using the Giant Meterwave Radio telescope (GMRT), we imaged the galaxy with a spectral resolution of 1.7 $\rm kms^{-1}$ and a spatial resolution of $15" \times 13.5"$. We find that FGC 1440 has an asymptotic rotational velocity of 141.8 $\rm kms^{-1}$ . The structure of the HI disc in FGC 1440 is that of a typical thin disc warped along the line of sight, but we can not rule out the presence of a central thick HI disc. We find that the dark matter halo in FGC 1440 could be modeled by a pseudo-isothermal (PIS) profile with $\rm R_{c}/ R_{d}, Comment: Accepted for publication in MNRAS

The first luminous objects forming in the universe produce radiation backgrounds in the far-ultraviolet and X-ray bands that affect the formation of Population III stars. Using a grid of cosmological hydrodynamics zoom-in simulations, we explore the impact of the Lyman–Warner (LW) and X-ray radiation backgrounds on the critical dark matter (DM) halo mass for Population III star formation and the total mass in stars per halo. We find that the LW radiation background lowers the H2 fraction and delays the formation of the Population III stars. On the other hand, X-ray irradiation anticipates the redshift of collapse and reduces the critical halo mass, unless the X-ray background is too strong and gas heating shuts down gas collapse into the haloes and prevents star formation. Therefore, an X-ray background can increase the number of DM haloes forming Population III stars by about a factor of 10, but the total mass in stars forming in each halo is reduced. This is because X-ray radiation increases the molecular fraction and lowers the minimum temperature of the collapsing gas (or equivalently the mass of the quasi-hydrostatic core) and therefore slows down the accretion of the gas on to the central protostar.

We estimate the 3D density profile of the Galactic dark matter (DM) halo within $r \lesssim 30$ kpc from the Galactic centre by using the astrometric data for halo RR Lyrae stars from Gaia DR2. We model both the stellar halo distribution function and the Galactic potential, fully taking into account the survey selection function, the observational errors, and the missing line-of-sight velocity data for RR Lyrae stars. With a Bayesian MCMC method, we infer the model parameters, including the density flattening of the DM halo $q$, which is assumed to be constant as a function of radius. We find that 99\% of the posterior distribution of $q$ is located at $q>0.963$, which strongly disfavours a flattened DM halo. We cannot draw any conclusions as to whether the Galactic DM halo at $r \lesssim 30$ kpc is prolate, because we restrict ourselves to axisymmetric oblate halo models with $q\leq1$. Our result is inconsistent with predictions from cosmological hydrodynamical simulations that advocate more oblate ($\langle{q}\rangle \sim0.8 \pm 0.15$) DM halos within $\sim 15\%$ of the virial radius for Milky-Way-sized galaxies. An alternative possibility, based on our validation tests with a cosmological simulation, is that the true value $q$ of the Galactic halo could be consistent with cosmological simulations but that disequilibrium in the Milky Way potential is inflating our measurement of $q$ by 0.1-0.2. As a by-product of our analysis, our model constrains the DM density in the Solar neighbourhood to be $��_{\mathrm{DM},\odot} = (9.01^{+0.18}_{-0.20})\times10^{-3}M_\odot \mathrm{pc}^{-3} = 0.342^{+0.007}_{-0.007}$ $\;\mathrm{GeV} \mathrm{cm}^{-3}$., MNRAS submitted. 15 pages (plus Appendix 7 pages). 6 figures (plus 10 figures in Appendix). Comments welcome

An overwhelming majority of galactic spiral arms trail with respect to the rotation of the galaxy, though a small sample of leading spiral arms has been observed. The formation of these leading spirals is not well understood. Here we show, using collisionless N-body simulations, that a barred disc galaxy in a retrograde dark matter halo can produce long-lived (∼3 Gyr) leading spiral arms. Due to the strong resonant coupling of the disc to the halo, the bar slows rapidly and spiral perturbations are forced ahead of the bar. We predict that such a system, if observed, will also host a dark matter wake oriented perpendicular to the stellar bar. More generally, we propose that any mechanism that rapidly decelerates the stellar bar will allow leading spiral arms to flourish.

Understanding the impact of halo properties beyond halo mass on the clustering of galaxies (namely galaxy assembly bias) remains a challenge for contemporary models of galaxy clustering. We explore the use of machine learning to predict the halo occupations and recover galaxy clustering and assembly bias in a semi-analytic galaxy formation model. For stellar-mass selected samples, we train a Random Forest algorithm on the number of central and satellite galaxies in each dark matter halo. With the predicted occupations, we create mock galaxy catalogues and measure the clustering and assembly bias. Using a range of halo and environment properties, we find that the machine learning predictions of the occupancy variations with secondary properties, galaxy clustering and assembly bias are all in excellent agreement with those of our target galaxy formation model. Internal halo properties are most important for the central galaxies prediction, while environment plays a critical role for the satellites. Our machine learning models are all provided in a usable format. We demonstrate that machine learning is a powerful tool for modelling the galaxy-halo connection, and can be used to create realistic mock galaxy catalogues which accurately recover the expected occupancy variations, galaxy clustering and galaxy assembly bias, imperative for cosmological analyses of upcoming surveys., 21 pages, 17 figures, submitted to MNRAS

We provide new values of the orbital parameters of 152 globular clusters, which are calculated using the new mean proper motions obtained from the Gaia EDR3 catalog data. The orbits were integrated 5 Gyr back in an axisymmetric three-component potential with a spherical bulge, disk component, and spherical dark halo in the Navarro-Frenk-White form, which we refined using the rotation curve of objects with large galactocentric distances up to 200 kpc. The obtained orbital parameters were compared with the orbital parameters of the same globular clusters calculated earlier in the same gravitational potential using proper motions from the Gaia DR2 catalog data. The objects whose orbits underwent significant changes were identified., Comment: 16 pages, 6 figures, 1 table

Let us recall the reasons for taking dark matter, and in particular non-baryonic dark matter, very seriously in the context of galaxy formation.