scholarly journals Cluster number counts dependence on dark energy inhomogeneities and coupling to dark matter

2006 ◽  
Vol 371 (3) ◽  
pp. 1373-1380 ◽  
Author(s):  
M. Manera ◽  
D. F. Mota
2010 ◽  
Vol 82 (8) ◽  
Author(s):  
S. Basilakos ◽  
M. Plionis ◽  
J. A. S. Lima

2013 ◽  
Vol 432 (2) ◽  
pp. 1513-1524 ◽  
Author(s):  
N. Chandrachani Devi ◽  
T. Roy Choudhury ◽  
Anjan A. Sen

2014 ◽  
Vol 10 (S306) ◽  
pp. 262-265
Author(s):  
Mariana Penna-Lima ◽  
Martín Makler ◽  
Carlos A. Wuensche

AbstractModels for galaxy clusters abundance and their spatial distribution are sensitive to cosmological parameters. Present and future surveys will provide high-redshift sample of clusters, such as Dark Energy Survey (z ⩽ 1.3), making cluster number counts one of the most promising cosmological probes. In the literature, some cosmological analyses are carried out using small cluster catalogs (tens to hundreds), like in Sunyaev-Zel'dovich (SZ) surveys. However, it is not guaranteed that maximum likelihood estimators of cosmological parameters are unbiased in this scenario. In this work we study different estimators of the cold dark matter density parameter Ωc, σ8 and the dark energy equation of state parameter w0 obtained from cluster abundance. Using an unbinned likelihood for cluster number counts and the Monte Carlo approach, we determine the presence of bias and how it varies with the size of the sample. Our fiducial models are based on the South Pole Telescope (SPT). We show that the biases from SZ estimators do not go away with increasing sample sizes and they may become the dominant source of error for an all sky survey at the SPT sensitivity.


2018 ◽  
Vol 614 ◽  
pp. A13 ◽  
Author(s):  
Laura Salvati ◽  
Marian Douspis ◽  
Nabila Aghanim

The thermal Sunyaev-Zel’dovich (tSZ) effect is one of the recent probes of cosmology and large-scale structures. We update constraints on cosmological parameters from galaxy clusters observed by the Planck satellite in a first attempt to combine cluster number counts and the power spectrum of hot gas; we used a new value of the optical depth and, at the same time, sampling on cosmological and scaling-relation parameters. We find that in the ΛCDM model, the addition of a tSZ power spectrum provides small improvements with respect to number counts alone, leading to the 68% c.l. constraints Ωm = 0.32  ± 0.02, σ8 = 0.76  ± 0.03, and σ8(Ωm/0.3)1/3 = 0.78  ± 0.03 and lowering the discrepancy with results for cosmic microwave background (CMB) primary anisotropies (updated with the new value of τ) to ≃1.8σ on σ8. We analysed extensions to the standard model, considering the effect of massive neutrinos and varying the equation of state parameter for dark energy. In the first case, we find that the addition of the tSZ power spectrum helps in improving cosmological constraints with respect to number count alone results, leading to the 95% upper limit ∑ mν < 1.88 eV. For the varying dark energy equation of state scenario, we find no important improvements when adding tSZ power spectrum, but still the combination of tSZ probes is able to provide constraints, producing w = −1.0 ± 0.2. In all cosmological scenarios, the mass bias to reconcile CMB and tSZ probes remains low at (1 − b) ≲ 0.67 as compared to estimates from weak lensing and X-ray mass estimate comparisons or numerical simulations.


2014 ◽  
Vol 29 (21) ◽  
pp. 1444010
Author(s):  
Bruce H. J. McKellar ◽  
T. J. Goldman ◽  
G. J. Stephenson

If fermions interact with a scalar field, and there are many fermions present the scalar field may develop an expectation value and generate an effective mass for the fermions. This can lead to the formation of fermion clusters, which could be relevant for neutrino astrophysics and for dark matter astrophysics. Because this system may exhibit negative pressure, it also leads to a model of dark energy.


2006 ◽  
Author(s):  
Roberto Mainini ◽  
Loris Colombo ◽  
Silvio Bonometto
Keyword(s):  

2003 ◽  
Vol 568 (1-2) ◽  
pp. 8-10 ◽  
Author(s):  
Ramzi R Khuri
Keyword(s):  

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