Reconstructing the projected gravitational potential of Abell 1689 from X-ray measurements
Abstract
Context. Galaxy clusters can be used as cosmological probes, but to this end, they need to be thoroughly understood. Combining all cluster observables in a consistent way will help us to understand their global properties and their internal structure.
Aims: We provide proof of the concept that the projected gravitational potential of galaxy clusters can directly be reconstructed from X-ray observations. We also show that this joint analysis can be used to locally test the validity of the equilibrium assumptions in galaxy clusters.
Methods: We used a newly developed reconstruction method, based on Richardson-Lucy deprojection, that allows reconstructing projected gravitational potentials of galaxy clusters directly from X-ray observations. We applied this algorithm to the well-studied cluster Abell 1689 and compared the gravitational potential reconstructed from X-ray observables to the potential obtained from gravitational lensing measurements. We also compared the X-ray deprojected profiles obtained by the Richardson-Lucy deprojection algorithm with the findings from the more conventional onion-peeling technique.
Results: Assuming spherical symmetry and hydrostatic equilibrium, the potentials recovered from gravitational lensing and from X-ray emission agree very well beyond 500 kpc. Owing to the fact that the Richardson-Lucy deprojection algorithm allows deprojecting each line of sight independently, this result may indicate that non-gravitational effects and/or asphericity are strong in the central regions of the clusters.
Conclusions: We demonstrate the robustness of the potential reconstruction method based on the Richardson-Lucy deprojection algorithm and show that gravitational lensing and X-ray emission lead to consistent gravitational potentials. Our results illustrate the power of combining galaxy-cluster observables in a single, non-parametric, joint reconstruction of consistent cluster potentials that can be used to locally constrain the physical state of the gas.
- Publication:
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Astronomy and Astrophysics
- Pub Date:
- February 2015
- DOI:
- 10.1051/0004-6361/201323242
- arXiv:
- arXiv:1501.03080
- Bibcode:
- 2015A&A...574A.122T
- Keywords:
-
- galaxies: clusters: general;
- X-rays: galaxies: clusters;
- gravitational lensing: weak;
- gravitational lensing: strong;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 8 pages, 4 figures. Accepted in A&