scholarly journals The splashback boundary of haloes in hydrodynamic simulations

2021 ◽  
Author(s):  
Stephanie O’Neil ◽  
David J Barnes ◽  
Mark Vogelsberger ◽  
Benedikt Diemer
Keyword(s):  
Dark Matter ◽  
Density Profile ◽  
Accretion Rate ◽  
Radial Density ◽  
Density Profiles ◽  
Hydrodynamic Simulations ◽  
Mass Accretion Rate ◽  
Significant Difference ◽  
Satellite Galaxies

Abstract The splashback radius, Rsp, is a physically motivated halo boundary that separates infalling and collapsed matter of haloes. We study Rsp in the hydrodynamic and dark matter only IllustrisTNG simulations. The most commonly adopted signature of Rsp is the radius at which the radial density profiles are steepest. Therefore, we explicitly optimise our density profile fit to the profile slope and find that this leads to a $\sim 5\%$ larger radius compared to other optimisations. We calculate Rsp for haloes with masses between 1013 − 15M⊙ as a function of halo mass, accretion rate and redshift. Rsp decreases with mass and with redshift for haloes of similar M200m in agreement with previous work. We also find that Rsp/R200m decreases with halo accretion rate. We apply our analysis to dark matter, gas and satellite galaxies associated with haloes to investigate the observational potential of Rsp. The radius of steepest slope in gas profiles is consistently smaller than the value calculated from dark matter profiles. The steepest slope in galaxy profiles, which are often used in observations, tends to agree with dark matter profiles but is lower for less massive haloes. We compare Rsp in hydrodynamic and N-body dark matter only simulations and do not find a significant difference caused by the addition of baryonic physics. Thus, results from dark matter only simulations should be applicable to realistic haloes.

scholarly journals Stellar splashback: the edge of the intracluster light

2020 ◽  
Vol 500 (3) ◽  
pp. 4181-4192
Author(s):  
Alis J Deason ◽  
Kyle A Oman ◽  
Azadeh Fattahi ◽  
Matthieu Schaller ◽  
Mathilde Jauzac ◽  
...  
Keyword(s):  
Dark Matter ◽  
Accretion Rate ◽  
Matter Distribution ◽  
Density Profiles ◽  
Mass Accretion Rate ◽  
Dark Matter Distribution ◽  
Intracluster Light ◽  
Physical Boundary ◽  
Fraction Bound ◽  
Good Agreement

ABSTRACT We examine the outskirts of galaxy clusters in the C-EAGLE simulations to quantify the ‘edges’ of the stellar and dark matter distribution. The radius of the steepest slope in the dark matter, commonly used as a proxy for the splashback radius, is located at $\sim \, r_{200 \rm m}$; the strength and location of this feature depends on the recent mass accretion rate, in good agreement with previous work. Interestingly, the stellar distribution (or intracluster light, ICL) also has a well-defined edge, which is directly related to the splashback radius of the halo. Thus, detecting the edge of the ICL can provide an independent measure of the physical boundary of the halo, and the recent mass accretion rate. We show that these caustics can also be seen in the projected density profiles, but care must be taken to account for the influence of substructures and other non-diffuse material, which can bias and/or weaken the signal of the steepest slope. This is particularly important for the stellar material, which has a higher fraction bound in subhaloes than the dark matter. Finally, we show that the ‘stellar splashback’ feature is located beyond current observational constraints on the ICL, but these large projected distances (≫1 Mpc) and low surface brightnesses (μ ≫ 32 mag arcsec−2) can be reached with upcoming observational facilities such as the Vera C. Rubin Observatory, the Nancy Grace Roman Space Telescope, and Euclid.

scholarly journals The Milky Way’s halo and subhaloes in self-interacting dark matter

2019 ◽  
Vol 490 (2) ◽  
pp. 2117-2123 ◽  
Author(s):  
Victor H Robles ◽  
Tyler Kelley ◽  
James S Bullock ◽  
Manoj Kaplinghat
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Elastic Cross Section ◽  
Too Big To Fail ◽  
Density Profiles ◽  
Potential Core ◽  
Cold Dark Matter Model ◽  
Matter Model ◽  
Satellite Galaxies ◽  
Dark Matter Model

ABSTRACT We perform high-resolution simulations of an MW-like galaxy in a self-interacting cold dark matter model with elastic cross-section over mass of $1~\rm cm^2\, g^{-1}$ (SIDM) and compare to a model without self-interactions (CDM). We run our simulations with and without a time-dependent embedded potential to capture effects of the baryonic disc and bulge contributions. The CDM and SIDM simulations with the embedded baryonic potential exhibit remarkably similar host halo profiles, subhalo abundances, and radial distributions within the virial radius. The SIDM host halo is denser in the centre than the CDM host and has no discernible core, in sharp contrast to the case without the baryonic potential (core size ${\sim}7 \, \rm kpc$). The most massive subhaloes (with $V_{\mathrm{peak}}\gt 20 \, \rm km\, s^{-1}$) in our SIDM simulations, expected to host the classical satellite galaxies, have density profiles that are less dense than their CDM analogues at radii less than 500 pc but the deviation diminishes for less massive subhaloes. With the baryonic potential included in the CDM and SIDM simulations, the most massive subhaloes do not display the too-big-to-fail problem. However, the least dense among the massive subhaloes in both these simulations tend to have the smallest pericenter values, a trend that is not apparent among the bright MW satellite galaxies.

scholarly journals Answers from the Void: VIDE and its Applications

2014 ◽  
Vol 11 (S308) ◽  
pp. 524-529
Author(s):  
P. M. Sutter ◽  
N. Hamaus ◽  
A. Pisani ◽  
G. Lavaux ◽  
B. D. Wandelt
Keyword(s):  
Dark Matter ◽  
Density Profile ◽  
Statistical Information ◽  
Distribution Model ◽  
Density Profiles ◽  
Redshift Surveys ◽  
Primordial Magnetic Fields ◽  
Galaxy Redshift ◽  
Galaxy Populations ◽  
Halo Occupation Distribution

AbstractWe discuss various applications of vide, the Void IDentification and Examination toolkit, an open-source Python/C++ code for finding cosmic voids in galaxy redshift surveys and $N$-body simulations. Based on a substantially enhanced version of ZOBOV, vide not only finds voids, but also summarizes their properties, extracts statistical information, and provides a Python-based platform for more detailed analysis, such as manipulating void catalogs and particle members, filtering, plotting, computing clustering statistics, stacking, comparing catalogs, and fitting density profiles. vide also provides significant additional functionality for pre-processing inputs: for example, vide can work with volume- or magnitude-limited galaxy samples with arbitrary survey geometries, or dark matter particles or halo catalogs in a variety of common formats. It can also randomly subsample inputs and includes a Halo Occupation Distribution model for constructing mock galaxy populations. vide has been used for a wide variety of applications, from discovering a universal density profile to estimating primordial magnetic fields, and is publicly available at http://bitbucket.org/cosmicvoids/vide\_public and http://www.cosmicvoids.net.

scholarly journals X-Ray Constraints on Dark Matter in Galaxy Clusters and Elliptical Galaxies: A View from Chandra and XMM

2004 ◽  
Vol 220 ◽  
pp. 149-158 ◽  
Author(s):  
David A. Buote
Keyword(s):  
Dark Matter ◽  
Galaxy Clusters ◽  
Elliptical Galaxies ◽  
Matter Content ◽  
The Self ◽  
Radial Density ◽  
Density Profiles ◽  
X Ray ◽  
Matter Model ◽  
Dark Matter Model

X-ray observations with Chandra and XMM are providing valuable new measurements of the dark matter content of elliptical galaxies and galaxy clusters. I review constraints on the radial density profiles and ellipticities of the dark matter in these systems (with an emphasis on clusters) obtained from recent X-ray observations and discuss their implications, especially for the self-interacting dark matter model.

scholarly journals Cosmology dependence of halo masses and concentrations in hydrodynamic simulations

2020 ◽  
Vol 500 (4) ◽  
pp. 5056-5071 ◽  
Author(s):  
Antonio Ragagnin ◽  
Alexandro Saro ◽  
Priyanka Singh ◽  
Klaus Dolag
Keyword(s):  
Density Profile ◽  
Observational Studies ◽  
Mass Concentration ◽  
Cosmological Parameters ◽  
Density Profiles ◽  
Hydrodynamic Simulations ◽  
Mass Conversion ◽  
Halo Masses ◽  
The Impact

ABSTRACT We employ a set of Magneticum cosmological hydrodynamic simulations that span over 15 different cosmologies, and extract masses and concentrations of all well-resolved haloes between z = 0 and 1 for critical overdensities $\Delta _\textrm {vir}, \Delta _{200c}, \Delta _{500c}, \Delta _{2500c}$ and mean overdensity Δ200m. We provide the first mass–concentration (Mc) relation and sparsity relation (i.e. MΔ1 − MΔ2 mass conversion) of hydrodynamic simulations that is modelled by mass, redshift, and cosmological parameters Ωm, Ωb, σ8, h0 as a tool for observational studies. We also quantify the impact that the Mc relation scatter and the assumption of Navarro–Frank–White (NFW) density profiles have on the uncertainty of the sparsity relation. We find that converting masses with the aid of an Mc relation carries an additional fractional scatter ($\approx 4{{\ \rm per\ cent}}$) originated from deviations from the assumed NFW density profile. For this reason, we provide a direct mass–mass conversion relation fit that depends on redshift and cosmological parameters. We release the package hydro_mc, a python tool that perform all kind of conversions presented in this paper.

scholarly journals Addressing γ-ray emissions from dark matter annihilations in 45 Milky Way satellite galaxies and in extragalactic sources with particle dark matter models

2020 ◽  
Vol 500 (4) ◽  
pp. 5589-5602
Author(s):  
Ashadul Halder ◽  
Shibaji Banerjee ◽  
Madhurima Pandey ◽  
Debasish Majumdar
Keyword(s):  
Dark Matter ◽  
Milky Way ◽  
Dwarf Galaxies ◽  
Upper Bounds ◽  
Density Profiles ◽  
Dark Energy Survey ◽  
Γ Rays ◽  
Γ Ray ◽  
Particle Dark Matter ◽  
Satellite Galaxies

ABSTRACT The mass-to-luminosity ratio of the dwarf satellite galaxies in the Milky Way suggests that these dwarf galaxies may contain substantial dark matter. The dark matter at the dense region such as within or at the vicinity of the centres of these dwarf galaxies may undergo the process of self-annihilation and produce γ-rays as the end product. The satellite borne γ-ray telescope such as Fermi-LAT reported the detection of γ-rays from around 45 Dwarf Spheroidals (dSphs) of Milky Way. In this work, we consider particle dark matter models described in the literature and after studying their phenomenologies, we calculate the γ-ray fluxes from the self-annihilation of the dark matter within the framework of these models in case of each of these 45 dSphs. We then compare the computed results with the observational upper bounds for γ-ray flux reported by Fermi-LAT and Dark Energy Survey for each of the 45 dSphs. The fluxes are calculated by adopting different dark matter density profiles. We then extend similar analysis for the observational upper bounds given by Fermi-LAT for the continuum γ-ray fluxes originating from extragalactic sources.

scholarly journals CONSTANT SURFACE GRAVITY AND DENSITY PROFILE OF DARK MATTER

2011 ◽  
Vol 26 (06) ◽  
pp. 1057-1072 ◽  
Author(s):  
H. J. DE VEGA ◽  
N. G. SANCHEZ
Keyword(s):  
Dark Matter ◽  
Density Profile ◽  
Particle Physics ◽  
Black Hole Entropy ◽  
Density Fluctuations ◽  
Surface Gravity ◽  
Density Profiles ◽  
Physics Model ◽  
Physical Consequences ◽  
Remarkable Agreement

Cumulative observational evidence confirms that the surface gravity of dark matter (DM) halos μ0 D = r0ρ0, where r0 and ρ0 are the halo core radius and central density, respectively, is nearly constant and independent of galaxy luminosity for a high number of galactic systems (spirals, dwarf irregular and spheroidals, elliptics) spanning over 14 magnitudes in luminosity and of different Hubble types. Remarkably, its numerical value, μ0D ≃140M⊙/ pc 2 = (18.6 MeV )3, is approximately the same (up to a factor of 2) in all these systems. First, we present the physical consequences of the independence of μ0D from r0: the energy scales as the volume [Formula: see text], while the mass and the entropy scale as the surface [Formula: see text] and the surface times log r0, respectively. Namely, the entropy scales similarly to the black hole entropy but with a much smaller coefficient. Second, we compute the surface gravity and the density profile for small scales from first principles and the evolution of primordial density fluctuations from the end of inflation till today using the linearized Boltzmann–Vlasov equation. The density profile ρ lin (r) obtained in this way decreases as r-1-ns/2 for intermediate scales, where ns≃0.964 is the primordial spectral index. This scaling is in remarkable agreement with the empirical behavior found observationally and in N-body simulations: r-1.6±0.4. The observed value of μ0D indicates that the DM particle mass m is on the keV scale. The theoretically derived density profiles ρ lin (r) turn to be cored for m on the keV scale and they are cusped for m on the GeV scale or beyond. We consider both fermions and bosons as DM particles decoupling either ultrarelativistically or nonrelativistically. Our results do not use any particle physics model and vary slightly with the statistics of the DM particle.

scholarly journals CLASH-VLT: a full dynamical reconstruction of the mass profile of Abell S1063 from 1 kpc out to the virial radius

2020 ◽  
Vol 637 ◽  
pp. A34 ◽  
Author(s):  
B. Sartoris ◽  
A. Biviano ◽  
P. Rosati ◽  
A. Mercurio ◽  
C. Grillo ◽  
...  
Keyword(s):  
Dark Matter ◽  
Density Profile ◽  
Velocity Dispersion ◽  
Mass Density ◽  
Dynamical Analysis ◽  
Cluster Galaxy ◽  
Data Set ◽  
Density Profiles ◽  
Dispersion Profile ◽  
Mass Profile

Context. The shape of the mass density profiles of cosmological halos informs us of the nature of dark matter (DM) and DM-baryons interactions. Previous estimates of the inner slope of the mass density profiles of clusters of galaxies are in opposition to predictions derived from numerical simulations of cold dark matter (CDM). Aims. We determine the inner slope of the DM density profile of a massive cluster of galaxies, Abell S1063 (RXC J2248.7−4431) at z = 0.35, with a dynamical analysis based on an extensive spectroscopic campaign carried out with the VIMOS and MUSE spectrographs at the ESO VLT. This new data set provides an unprecedented sample of 1234 spectroscopic members, 104 of which are located in the cluster core (R ≲ 200 kpc), extracted from the MUSE integral field spectroscopy. The latter also allows the stellar velocity dispersion profile of the brightest cluster galaxy (BCG) to be measured out to 40 kpc. Methods. We used an upgraded version of the MAMPOSSt technique to perform a joint maximum likelihood fit to the velocity dispersion profile of the BCG and to the velocity distribution of cluster member galaxies over a radial range from 1 kpc to the virial radius (r200 ≈ 2.7 Mpc). Results. We find a value of γDM = 0.99 ± 0.04 for the inner logarithmic slope of the DM density profile after marginalizing over all the other parameters of the mass and velocity anisotropy models. Moreover, the newly determined dynamical mass profile is found to be in excellent agreement with the mass density profiles obtained from the independent X-ray hydrostatic analysis based on deep Chandra data, as well as the strong and weak lensing analyses. Conclusions. Our value of the inner logarithmic slope of the DM density profile γDM is in very good agreement with predictions from cosmological CDM simulations. We will extend our analysis to more clusters in future works. If confirmed on a larger cluster sample, our result makes this DM model more appealing than alternative models.

scholarly journals HST spectra reveal accretion in MY Lupi

2019 ◽  
Vol 629 ◽  
pp. A108 ◽  
Author(s):  
J. M. Alcalá ◽  
C. F. Manara ◽  
K. France ◽  
C. P. Schneider ◽  
N. Arulanantham ◽  
...  
Keyword(s):  
Accretion Rate ◽  
Space Telescope ◽  
Low Contrast ◽  
Mass Accretion Rate ◽  
Excess Emission ◽  
Total Luminosity ◽  
Significant Difference ◽  
Chromospheric Emission ◽  
Order Of Magnitude ◽  
Far Ultraviolet

The mass accretion rate is a crucial parameter for the study of the evolution of accretion discs around young low-mass stellar and substellar objects (YSOs). We revisit the case of MY Lup, an object where VLT/X-shooter data suggested a negligible mass accretion rate, and show it to be accreting on a level similar to other Class II YSOs in Lupus based on Hubble Space Telescope (HST) observations. In our HST-Cosmic Origins Spectrograph (HST-COS) and -Space Telescope Imaging Spectrograph (HST-STIS) spectra, we find many emission lines, as well as substantial far-ultraviolet (FUV) continuum excess emission, which can be ascribed to active accretion. The total luminosity of the C IV λ1549 Å doublet is 4.1 × 10−4 L⊙. Using scalings between accretion luminosity, Lacc, and C IV luminosity from the literature, we derive Lacc ~2 × 10−1 L⊙, which is more than an order of magnitude higher than the upper limit estimated from the X-shooter observations. We discuss possible reasons for the X-shooter-HST discrepancy, the most plausible being that the low contrast between the continuum excess emission and the photospheric+chromospheric emission at optical wavelengths in MY Lup hampered detection of excess emission. The luminosity of the FUV continuum and C IV lines, strong H2 fluorescence, and a “1600 A Bump” place MY Lup in the class of accreting objects with gas-rich discs. So far, MY Lup is the only peculiar case in which a significant difference between the HST and X-shooter Ṁacc estimates exists that is not ascribable to variability. The mass accretion rate inferred from the revisited Lacc estimate is Ṁacc ~ 1(−0.5+1.5) × 10−8 M⊙ yr−1. This value is consistent with the typical value derived for accreting YSOs of similar mass in Lupus and points to less clearing of the inner disc than indicated by near- and mid-infrared observations. This is confirmed by Atacama Large Millimeter Array (ALMA) data, which show that the gaps and rings seen in the sub-millimetre are relatively shallow.

scholarly journals VEGAS-SSS. II. Comparing the globular cluster systems in NGC 3115 and NGC 1399 using VEGAS and FDS survey data

2018 ◽  
Vol 611 ◽  
pp. A93 ◽  
Author(s):  
Michele Cantiello ◽  
Raffaele D’Abrusco ◽  
Marilena Spavone ◽  
Maurizio Paolillo ◽  
Massimo Capaccioli ◽  
...  
Keyword(s):  
Globular Cluster ◽  
Radial Density ◽  
Density Profiles ◽  
Density Maps ◽  
Radial Profiles ◽  
Wide Range ◽  
Significant Difference ◽  
The Galaxy ◽  
Deep Survey ◽  
Specific Frequency

We analyze the globular cluster (GC) systems in two very different galaxies, NGC 3115 and NGC 1399. With the papers of this series, we aim at highlighting common and different properties in the GC systems in galaxies covering a wide range of parameter space. We compare the GCs in NGC 3115 and NGC 1399 as derived from the analysis of one square degree u-, g-, and i-band images taken with the VST telescope as part of the VST early-type galaxy survey (VEGAS) and Fornax deep survey (FDS). We selected GC candidates using as reference the morpho-photometric and color properties of confirmed GCs. The surface density maps of GCs in NGC 3115 reveal a morphology similar to the light profile of field stars; the same is true when blue and red GCs are taken separately. The GC maps for NGC 1399 are richer in structure and confirm the existence of an intra-cluster GC component. We confirm the presence of a spatial offset in the NGC 1399 GC centroid and find that the centroid of the GCs for NGC 3115 coincides well with the galaxy center. Both GC systems show unambiguous color bimodality in (g − i) and (u − i); the color–color relations of the two GC systems are slightly different with NGC 3115 appearing more linear than NGC 1399. The azimuthal average of the radial density profiles in both galaxies reveals a larger spatial extent for the total GCs population with respect to the galaxy surface brightness profile. For both galaxies, the red GCs have radial density profiles compatible with the galaxy light profile, while the radial profiles for blue GCs are shallower. As for the specific frequency of GCs, SN, we find it is a factor of two higher in NGC 1399 than for NGC 3115; this is mainly the result of extra blue GCs. By inspecting the radial behavior of the specific frequency, SN(<r), for the total, blue, and red GCs, we find notable similarities between the trends for red GCs in the two targets. In spite of extremely different host environments, the red GCs in both cases appear closely linked to the light distribution of field stars. Blue GCs extend to larger galactocentric scales than red GCs, marking a significant difference between the two galaxies: the blue/red GCs and field stellar components of NGC 3115 appear well thermalized with each other and the blue GCs in NGC 1399 appear to fade into an unrelaxed intra-cluster GC population.

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