Reconstructing the projected gravitational potential of Abell 1689 from X-ray measurements

Tchernin, C.; Majer, Charles L.; Meyer, Sven; Sarli, Eleonora; Eckert, D.; Bartelmann, Matthias

doi:10.1051/0004-6361/201323242

Cited by 9 publications

(10 citation statements)

References 51 publications

(89 reference statements)

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“…A reasonable characterization of the 3D density profile may then fail to reproduce all the observable features of a halo. A description of the halo in terms of the potential could be more sensible [8].…”

Section: Introductionmentioning

confidence: 99%

Comparison of weak lensing by NFW and Einasto halos and systematic errors

Sereno

Fedeli

Moscardini

2016

J. Cosmol. Astropart. Phys.

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Abstract. Recent N -body simulations have shown that Einasto radial profiles provide the most accurate description of dark matter halos. Predictions based on the traditional NFW functional form may fail to describe the structural properties of cosmic objects at the percent level required by precision cosmology. We computed the systematic errors expected for weak lensing analyses of clusters of galaxies if one wrongly models the lens density profile. Even though the NFW fits of observed tangential shear profiles can be excellent, viral masses and concentrations of very massive halos ( > ∼ 10 15 M /h) can be over-and underestimated by ∼ 10 per cent, respectively. Misfitting effects also steepen the observed mass-concentration relation, as observed in multi-wavelength observations of galaxy groups and clusters. Based on shear analyses, Einasto and NFW halos can be set apart either with deep observations of exceptionally massive structures ( > ∼ 2 × 10 15 M /h) or by stacking the shear profiles of thousands of group-sized lenses ( > ∼ 10 14 M /h).

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Section: Introductionmentioning

confidence: 99%

Comparison of weak lensing by NFW and Einasto halos and systematic errors

Sereno

Fedeli

Moscardini

2016

J. Cosmol. Astropart. Phys.

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“…In this paper, we have moved away from this approach and presented a free-form model for the physical properties of galaxy clusters. Previous attempts to model clusters in this way have typically relied simply on dividing the cluster into a predefined number of cells, or concentric shells for spherical clusters, and determining the value of each physical quantity of interest within these subregions (Tchernin et al 2015). Such approaches typically lead to under-determined inverse problems that therefore need to be regularised in some way.…”

Section: Discussionmentioning

confidence: 99%

Free-form modelling of galaxy clusters: a Bayesian and data-driven approach

Olamaie

Hobson²,

Feroz³

et al. 2018

Monthly Notices of the Royal Astronomical Society

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A new method is presented for modelling the physical properties of galaxy clusters. Our technique moves away from the traditional approach of assuming specific parameterised functional forms for the variation of physical quantities within the cluster, and instead allows for a 'free-form' reconstruction, but one for which the level of complexity is determined automatically by the observational data and may depend on position within the cluster. This is achieved by representing each independent cluster property as some interpolating or approximating function that is specified by a set of control points, or 'nodes', for which the number of nodes, together with their positions and amplitudes, are allowed to vary and are inferred in a Bayesian manner from the data. We illustrate our nodal approach in the case of a spherical cluster by modelling the electron pressure profile P e (r) in analyses both of simulated Sunyaev-Zel'dovich (SZ) data from the Arcminute MicroKelvin Imager (AMI) and of real AMI observations of the cluster MACS J0744+3927 in the CLASH sample. We demonstrate that one may indeed determine the complexity supported by the data in the reconstructed P e (r), and that one may constrain two very important quantities in such an analysis: the cluster total volume integrated Comptonisation parameter (Y tot ) and the extent of the gas distribution in the cluster (r max ). The approach is also well-suited to detecting clusters in blind SZ surveys.

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“…We observed a radial trend between the re-constructed and the true projected gravitational potentials, which may indicate that the cluster is in a more complicated physical state than the assumed equilibrium. Such a study can thus be used to assess the physical state within the cluster, as it was pointed out for instance in Tchernin et al (2015) for the cluster A1689. On the other hand, assuming that the equilibrium assumptions are valid, a joint analysis could be used to constrain the geometry of the cluster (see e.g., De Filippis et al 2005).…”

Section: Discussionmentioning

confidence: 99%

“…To reconstruct cluster potentials, we use the Richardson-Lucy deprojection algorithm (R-L, Lucy 1974Lucy , 1994. The onedimensional (1D) R-L method has been successfully tested against other deprojection schemes (see for instance Tchernin et al 2015, where the outcome of the R-L deprojection was compared to the onion-peeling deprojection method). The R-L scheme offers the substantial advantage of allowing the deprojection of all lines-of-sight separately, and thus it is applicable to incomplete data sets, allowing us to exclude from the analysis data coming from regions where the assumptions made may not hold (such as, at the cluster center or in the outskirts).…”

Section: Introductionmentioning

confidence: 99%

Reconstruction of the two-dimensional gravitational potential of galaxy clusters from X-ray and Sunyaev-Zel’dovich measurements

Tchernin

Bartelmann

Huber

et al. 2018

A&A

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Context. The mass of galaxy clusters is not a direct observable, nonetheless it is commonly used to probe cosmological models. Based on the combination of all main cluster observables, that is, the X-ray emission, the thermal Sunyaev-Zel'dovich (SZ) signal, the velocity dispersion of the cluster galaxies, and gravitational lensing, the gravitational potential of galaxy clusters can be jointly reconstructed. Aims. We derive the two main ingredients required for this joint reconstruction: the potentials individually reconstructed from the observables and their covariance matrices, which act as a weight in the joint reconstruction. We show here the method to derive these quantities. The result of the joint reconstruction applied to a real cluster will be discussed in a forthcoming paper. Methods. We apply the Richardson-Lucy deprojection algorithm to data on a two-dimensional (2D) grid. We first test the 2D deprojection algorithm on a β-profile. Assuming hydrostatic equilibrium, we further reconstruct the gravitational potential of a simulated galaxy cluster based on synthetic SZ and X-ray data. We then reconstruct the projected gravitational potential of the massive and dynamically active cluster Abell 2142, based on the X-ray observations collected with XMM-Newton and the SZ observations from the Planck satellite. Finally, we compute the covariance matrix of the projected reconstructed potential of the cluster Abell 2142 based on the X-ray measurements collected with XMM-Newton. Results. The gravitational potentials of the simulated cluster recovered from synthetic X-ray and SZ data are consistent, even though the potential reconstructed from X-rays shows larger deviations from the true potential. Regarding Abell 2142, the projected gravitational cluster potentials recovered from SZ and X-ray data reproduce well the projected potential inferred from gravitational-lensing observations. We also observe that the covariance matrix of the potential for Abell 2142 reconstructed from XMM-Newton data sensitively depends on the resolution of the deprojected grid and on the smoothing scale used in the deprojection. Conclusions. We show that the Richardson-Lucy deprojection method can be effectively applied on a grid and that the projected potential is well recovered from real and simulated data based on X-ray and SZ signal. The comparison between the reconstructed potentials from the different observables provides additional information on the validity of the assumptions as function of the projected radius.

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Reconstructing the projected gravitational potential of Abell 1689 from X-ray measurements

Cited by 9 publications

References 51 publications

Comparison of weak lensing by NFW and Einasto halos and systematic errors

Comparison of weak lensing by NFW and Einasto halos and systematic errors

Free-form modelling of galaxy clusters: a Bayesian and data-driven approach

Reconstruction of the two-dimensional gravitational potential of galaxy clusters from X-ray and Sunyaev-Zel’dovich measurements

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