scholarly journals Cluster density profiles as a test of modified gravity

2012 ◽  
Vol 85 (10) ◽  
Author(s):  
Lucas Lombriser ◽  
Fabian Schmidt ◽  
Tobias Baldauf ◽  
Rachel Mandelbaum ◽  
Uroš Seljak ◽  
...  
Keyword(s):  
Modified Gravity ◽  
Density Profiles ◽  
Cluster Density

scholarly journals Testing Gravity using Void Profiles

2014 ◽  
Vol 11 (S308) ◽  
pp. 555-560 ◽  
Author(s):  
Yan-Chuan Cai ◽  
Nelson Padilla ◽  
Baojiu Li
Keyword(s):  
Dark Matter ◽  
Gravitational Lensing ◽  
Modified Gravity ◽  
Large Scale ◽  
Line Of Sight ◽  
Number Density ◽  
Density Profiles ◽  
Photometric Redshift ◽  
Redshift Survey ◽  
Near Future

AbstractWe investigate void properties inf(R)models using N-body simulations, focusing on their differences from General Relativity (GR) and their detectability. In the Hu-Sawickif(R)modified gravity (MG) models, the halo number density profiles of voids are not distinguishable from GR. In contrast, the samef(R)voids are more empty of dark matter, and their profiles are steeper. This can in principle be observed by weak gravitational lensing of voids, for which the combination of a spectroscopic redshift and a lensing photometric redshift survey over the same sky is required. Neglecting the lensing shape noise, thef(R)model parameter amplitudesfR0=10-5and 10-4may be distinguished from GR using the lensing tangential shear signal around voids by 4 and 8 σ for a volume of 1 (Gpc/h)3. The line-of-sight projection of large-scale structure is the main systematics that limits the significance of this signal for the near future wide angle and deep lensing surveys. For this reason, it is challenging to distinguishfR0=10-6from GR. We expect that this can be overcome with larger volume. The halo void abundance being smaller and the steepening of dark matter void profiles inf(R)models are unique features that can be combined to break the degeneracy betweenfR0and σ8.

scholarly journals An analysis of galaxy cluster mis-centring using cosmological hydrodynamic simulations

2020 ◽  
Vol 493 (1) ◽  
pp. 1120-1129
Author(s):  
Z Yan ◽  
N Raza ◽  
L Van Waerbeke ◽  
A J Mead ◽  
I G McCarthy ◽  
...  
Keyword(s):  
Galaxy Cluster ◽  
Mass Range ◽  
Three Dimensions ◽  
Cumulative Distribution ◽  
Density Profiles ◽  
Hydrodynamic Simulations ◽  
The Galaxy ◽  
Cluster Density ◽  
Cluster Properties ◽  
Using Data

ABSTRACT The location of a galaxy cluster’s centroid is typically derived from observations of the galactic and/or gas component of the cluster, but these typically deviate from the true centre. This can produce bias when observations are combined to study average cluster properties. Using data from the BAryons and HAloes of MAssive Systems (BAHAMAS) cosmological hydrodynamic simulations, we study this bias in both two and three dimensions for 2000 clusters over the 1013–1015 M⊙ mass range. We quantify and model the offset distributions between observationally motivated centres and the ‘true’ centre of the cluster, which is taken to be the most gravitationally bound particle measured in the simulation. We fit the cumulative distribution function of offsets with an exponential distribution and a Gamma distribution fit well with most of the centroid definitions. The galaxy-based centres can be seen to be divided into a mis-centred group and a well-centred group, with the well-centred group making up about $60{{\ \rm per\ cent}}$ of all the clusters. Gas-based centres are overall less scattered than galaxy-based centres. We also find a cluster-mass dependence of the offset distribution of gas-based centres, with generally larger offsets for smaller mass clusters. We then measure cluster density profiles centred at each choice of the centres and fit them with empirical models. Stacked, mis-centred density profiles fit to the Navarro–Frenk–White dark matter profile and Komatsu–Seljak gas profile show that recovered shape and size parameters can significantly deviate from the true values. For the galaxy-based centres, this can lead to cluster masses being underestimated by up to $10{{\ \rm per\ cent}}$.

scholarly journals Cross-correlation Weak Lensing of SDSS galaxy Clusters II: Cluster Density Profiles and the Mass--Richness Relation

2007 ◽  
Author(s):  
David E. Johnston ◽  
Erin S. Sheldon ◽  
Risa H. Wechsler ◽  
Eduardo Rozo ◽  
Benjamin P. Koester ◽  
...  
Keyword(s):  
Galaxy Clusters ◽  
Cross Correlation ◽  
Weak Lensing ◽  
Density Profiles ◽  
Cluster Density

scholarly journals Convergence and scatter of cluster density profiles

2004 ◽  
Vol 353 (2) ◽  
pp. 624-632 ◽  
Author(s):  
Jürg Diemand ◽  
Ben Moore ◽  
Joachim Stadel
Keyword(s):  
Density Profiles ◽  
Cluster Density

scholarly journals Are the globular clusters with significant internal [Fe/H] spreads all former dwarf galaxy nuclei?

2015 ◽  
Vol 11 (S317) ◽  
pp. 110-115 ◽  
Author(s):  
G. S. Da Costa
Keyword(s):  
Distribution Function ◽  
Globular Clusters ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Density Profiles ◽  
Cluster Density ◽  
Galactic Globular Clusters ◽  
Metallicity Distribution

AbstractIn this contribution the hypothesis that the Galactic globular clusters with substantial internal [Fe/H] abundance ranges are the former nuclei of disrupted dwarf galaxies is discussed. Evidence considered includes the form of the metallicity distribution function, the occurrence of large diffuse outer envelopes in cluster density profiles, and the presence of ([s-process/Fe], [Fe/H]) correlations. The hypothesis is shown to be plausible but with the caveat that if significantly more than the current nine clusters known to have [Fe/H] spreads are found, then re-evaluation will be required.

scholarly journals The effects of ellipticity and substructure on estimates of cluster density profiles based on lensing and kinematics

2007 ◽  
Vol 381 (1) ◽  
pp. 171-186 ◽  
Author(s):  
Massimo Meneghetti ◽  
Matthias Bartelmann ◽  
Adrian Jenkins ◽  
Carlos Frenk
Keyword(s):  
Density Profiles ◽  
Cluster Density

scholarly journals Constraints on chameleon f(R)-gravity from galaxy rotation curves of the SPARC sample

2019 ◽  
Vol 489 (1) ◽  
pp. 771-787 ◽  
Author(s):  
Aneesh P Naik ◽  
Ewald Puchwein ◽  
Anne-Christine Davis ◽  
Debora Sijacki ◽  
Harry Desmond
Keyword(s):  
Modified Gravity ◽  
Convincing Evidence ◽  
Rotation Curves ◽  
Density Profiles ◽  
The Core ◽  
Modified Gravity Theory ◽  
Large Spread ◽  
The Galaxy ◽  
Mass Size ◽  
Galaxy Rotation Curves

ABSTRACT In chameleon f(R)-gravity, the fifth force will lead to ‘upturns’ in galaxy rotation curves near the screening radius. The location of the upturn depends on the cosmic background value of the scalar field $\bar{f}_\mathrm{R0}$, as well as the mass, size, and environment of the galaxy. We search for this signature of modified gravity in the SPARC sample of measured rotation curves, using an MCMC technique to derive constraints on $\bar{f}_\mathrm{R0}$. Assuming NFW dark matter haloes and with $\bar{f}_\mathrm{R0}$ freely varying for each galaxy, most galaxies prefer f(R) gravity to ΛCDM, but there is a large spread of inferred $\bar{f}_\mathrm{R0}$ values, inconsistent with a single global value. Requiring instead a consistent $\bar{f}_\mathrm{R0}$ value for the whole sample, models with $\log _{10}|\bar{f}_\mathrm{R0}|\gt -6.1$ are excluded. On the other hand, models in the range $-7.5\lt \log _{10}|\bar{f}_\mathrm{R0}|\lt -6.5$ seem to be favoured with respect to ΛCDM, with a significant peak at −7. However, this signal is largely a result of galaxies for which the f(R) signal is degenerate with the core/cusp problem, and when the NFW profile is replaced with a cored halo profile, ΛCDM gives better fits than any given f(R) model. Thus, we find no convincing evidence of f(R) gravity down to the level of $|\bar{f}_\mathrm{R0}|\sim 6 \times 10^{-8}$, with the caveat that if cored halo density profiles cannot ultimately be explained within ΛCDM, a screened modified gravity theory could possibly provide an alternative solution for the core/cusp problem. However, the f(R) models studied here fall short of achieving this.

scholarly journals The cosmological dependence of cluster density profiles

1994 ◽  
Vol 434 ◽  
pp. 402 ◽  
Author(s):  
Mary M. Crone ◽  
August E. Evrard ◽  
Douglas O. Richstone
Keyword(s):  
Density Profiles ◽  
Cluster Density

scholarly journals The Three Hundred Project: The evolution of galaxy cluster density profiles

2018 ◽  
Vol 483 (3) ◽  
pp. 3390-3403 ◽  
Author(s):  
Robert Mostoghiu ◽  
Alexander Knebe ◽  
Weiguang Cui ◽  
Frazer R Pearce ◽  
Gustavo Yepes ◽  
...  
Keyword(s):  
Galaxy Cluster ◽  
Density Profiles ◽  
Cluster Density

scholarly journals The connection between halo concentrations and assembly histories: a probe of gravity?

2019 ◽  
Vol 489 (4) ◽  
pp. 4658-4668
Author(s):  
Piotr Oleśkiewicz ◽  
Carlton M Baugh ◽  
Aaron D Ludlow
Keyword(s):  
General Relativity ◽  
Dark Matter ◽  
High Resolution ◽  
Modified Gravity ◽  
Mass Concentration ◽  
The Other ◽  
Formation Time ◽  
Density Profiles ◽  
Time Relation ◽  
Halo Population

ABSTRACT We use two high-resolution N-body simulations, one assuming general relativity (GR) and the other the Hu–Sawicki form of f(R) gravity with $\vert \bar{f}_{\mathrm{ R}} \vert = 10^{-6}$, to investigate the concentration–formation time relation of dark matter haloes. We assign haloes to logarithmically spaced mass bins, and fit median density profiles and extract median formation times in each bin. At fixed mass, haloes in modified gravity are more concentrated than those in GR, especially at low masses and low redshift, and do not follow the concentration–formation time relation seen in GR. We assess the sensitivity of the relation to how concentration and formation time are defined, as well as to the segregation of the halo population by the amount of gravitational screening. We find a clear difference between halo concentrations and assembly histories displayed in modified gravity and those in GR. Existing models for the mass–concentration–redshift relation that have gained success in cold and warm dark matter models require revision in f(R) gravity.

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