scholarly journals Using the Outskirts of Galaxy Clusters to Determine their Mass Accretion Rate

2016 ◽  
Author(s):  
Cristiano De Boni
Keyword(s):  
Dark Matter ◽  
Spherical Shell ◽  
Galaxy Clusters ◽  
Accretion Rate ◽  
Redshift Range ◽  
Mass Accretion Rate ◽  
The Mean ◽  
Mass Profile

We explore the possibility of using the external regions of galaxy clusters to measure their mass accretion rate (MAR). The main goal is to provide a method to observationally investigate the growth of structures on the nonlinear scales of galaxy clusters. We derive the MAR by using the mass profile beyond the splashback radius, evaluating the mass of a spherical shell and the time it takes to fall in. The infall velocity of the shell is extracted from N-body simulations. The average MAR returned by our prescription in the redshift range z=[0, 2] is within 20-40% of the average MAR derived from the merger trees of dark matter haloes in the reference N-body simulations. Our result suggests that the external regions of galaxy clusters can be used to measure the mean MAR of a sample of clusters.

scholarly journals The Evolving Shape of Galaxy Clusters

2014 ◽  
Vol 11 (S308) ◽  
pp. 217-218
Author(s):  
Dennis W. Just ◽  
H. K. C. Yee ◽  
Adam Muzzin ◽  
Gillian Wilson ◽  
David G. Gilbank ◽  
...  
Keyword(s):  
Galaxy Clusters ◽  
Cosmic Time ◽  
Redshift Range ◽  
The Mean

AbstractWe present the first measurement of the evolution of the apparent projected shape of galaxy clusters from 0.2≲ z≲2. We measure the ellipticities (εcl) of homogeneously selected galaxy clusters over this wide redshift range. We confirm the predictions of N-body simulations that clusters are more elongated at higher redshift, finding the mean projected ellipticity changes linearly from 0.36±0.01 to 0.25±0.01 over that range. The fraction of relaxed clusters (defined as having εcl<0.2) is 9+5-3% at z∼1.8, steadily increasing to 42+7-6% by z∼0.3. Because more spherical clusters have a higher degree of virialization, our result shows significant evolution in the degree of cluster virialization over cosmic time.

scholarly journals THE MASS ACCRETION RATE OF GALAXY CLUSTERS: A MEASURABLE QUANTITY

2016 ◽  
Vol 818 (2) ◽  
pp. 188 ◽  
Author(s):  
C. De Boni ◽  
A. L. Serra ◽  
A. Diaferio ◽  
C. Giocoli ◽  
M. Baldi
Keyword(s):  
Galaxy Clusters ◽  
Accretion Rate ◽  
Measurable Quantity ◽  
Mass Accretion Rate

scholarly journals Testing Modified Dark Matter with galaxy clusters: Does dark matter know about the cosmological constant?

2017 ◽  
Vol 32 (18) ◽  
pp. 1750108 ◽  
Author(s):  
Douglas Edmonds ◽  
Duncan Farrah ◽  
Chiu Man Ho ◽  
Djordje Minic ◽  
Y. Jack Ng ◽  
...  
Keyword(s):  
Dark Matter ◽  
Cosmological Constant ◽  
Galaxy Clusters ◽  
Cold Dark Matter ◽  
Galactic Rotation ◽  
Dark Matter Mass ◽  
Mass Profile ◽  
The One ◽  
Gravitational Thermodynamics ◽  
Mass Profiles

We discuss the possibility that the cold dark matter mass profiles contain information on the cosmological constant [Formula: see text], and that such information constrains the nature of cold dark matter (CDM). We call this approach Modified Dark Matter (MDM). In particular, we examine the ability of MDM to explain the observed mass profiles of 13 galaxy clusters. Using general arguments from gravitational thermodynamics, we provide a theoretical justification for our MDM mass profile. In order to properly fit the shape of the mass profiles in galaxy clusters, we find it necessary to generalize the MDM mass profile from the one we used previously to fit galactic rotation curves. We successfully compare it to the NFW mass profiles both on cluster and galactic scales, though differences in form appear with the change in scales. Our results suggest that indeed the CDM mass profiles contain information about the cosmological constant in a nontrivial way.

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 Understanding the large inferred Einstein radii of observed low-mass galaxy clusters

2020 ◽  
Vol 494 (4) ◽  
pp. 4706-4712 ◽  
Author(s):  
Andrew Robertson ◽  
Richard Massey ◽  
Vincent Eke
Keyword(s):  
Dark Matter ◽  
Galaxy Clusters ◽  
Gravitational Lensing ◽  
Cold Dark Matter ◽  
Baryonic Matter ◽  
Analysis Method ◽  
Critical Curves ◽  
Hydrodynamical Simulation ◽  
Low Mass ◽  
Main Effects

ABSTRACT We assess a claim that observed galaxy clusters with mass ${\sim}10^{14} \mathrm{\, M_\odot }$ are more centrally concentrated than predicted in lambda cold dark matter (ΛCDM). We generate mock strong gravitational lensing observations, taking the lenses from a cosmological hydrodynamical simulation, and analyse them in the same way as the real Universe. The observed and simulated lensing arcs are consistent with one another, with three main effects responsible for the previously claimed inconsistency. First, galaxy clusters containing baryonic matter have higher central densities than their counterparts simulated with only dark matter. Secondly, a sample of clusters selected because of the presence of pronounced gravitational lensing arcs preferentially finds centrally concentrated clusters with large Einstein radii. Thirdly, lensed arcs are usually straighter than critical curves, and the chosen image analysis method (fitting circles through the arcs) overestimates the Einstein radii. After accounting for these three effects, ΛCDM predicts that galaxy clusters should produce giant lensing arcs that match those in the observed Universe.

scholarly journals The relativistic mass accretion rate for accretion disk in the equatorial of rapidly rotating neutron stars

2021 ◽  
Vol 1869 (1) ◽  
pp. 012156
Author(s):  
A Yasrina ◽  
N Widianingrum ◽  
N S Risdianto ◽  
D Andra ◽  
N A Pramono ◽  
...  
Keyword(s):  
Neutron Stars ◽  
Accretion Disk ◽  
Accretion Rate ◽  
Mass Accretion Rate ◽  
Relativistic Mass

scholarly journals Rotation of Galaxy Dark Matter Halos

2006 ◽  
Vol 2 (S235) ◽  
pp. 104-104
Author(s):  
Stéphane Herbert-Fort ◽  
Dennis Zaritsky ◽  
Yeun Jin Kim ◽  
Jeremy Bailin ◽  
James E. Taylor
Keyword(s):  
Dark Matter ◽  
Angular Momentum ◽  
Numerical Simulations ◽  
Galaxy Formation ◽  
Spiral Galaxy ◽  
Observational Studies ◽  
Spiral Galaxies ◽  
Satellite System ◽  
Dark Matter Halos ◽  
The Mean

AbstractThe degree to which outer dark matter halos of spiral galaxies rotate with the disk is sensitive to their accretion history and may be probed with associated satellite galaxies. We use the Steward Observatory Bok telescope to measure the sense of rotation of nearby isolated spirals and combine these data with those of their associated satellites (drawn from SDSS) to directly test predictions from numerical simulations. We aim to constrain models of galaxy formation by measuring the projected component of the halo angular momentum that is aligned with that of spiral galaxy disks, Jz. We find the mean bulk rotation of the ensemble satellite system to be co-rotating with the disk with a velocity of 22 ± 13 km/s, in general agreement with previous observational studies and suggesting that galaxy disks could be formed by halo baryons collapsing by a factor of ≈10. We also find a prograde satellite fraction of 51% and Jz, of the satellite system to be positively correlated with the disk, albeit at low significance (2655 ± 2232 kpc km/s).

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