Radio relics tracing the projected mass distribution in CIZA J2242.8+5301*
Abstract
We present a weak-lensing analysis for a merging galaxy cluster, CIZA J2242.8+5301, which hosts double radio relics, using three-band Subaru/Suprime-Cam imaging (Br'z'). Since the lifetime of dark matter halos colliding into clusters is longer than that of X-ray emitting gas halos, weak-lensing analysis is a powerful method to constrain merger dynamics. Two-dimensional shear fitting using a clean background catalog suggests that the cluster undergoes a merger with a mass ratio of about 2 : 1. The main halo is located around the gas core in the southern region, while no concentrated gas core is associated with the northern sub-halo. We find that the projected cluster mass distribution resulting from an unequal-mass merger is in excellent agreement with the curved shapes of the two radio relics and the overall X-ray morphology, except for the lack of the northern gas core. The lack of a prominent radio halo enables us to constrain an upper limit of the fractional energy of magnetohydrodynamic turbulence of (δ B/B)^2<{O}(10^{-6}) at a resonant wavenumber, by finding a balance between the acceleration time and the time after the core passage or the cooling time, with an assumption of resonant acceleration by a second-order Fermi process.
- Publication:
-
Publications of the Astronomical Society of Japan
- Pub Date:
- December 2015
- DOI:
- arXiv:
- arXiv:1508.04558
- Bibcode:
- 2015PASJ...67..114O
- Keywords:
-
- galaxies: clusters: individual (CIZA J2242.8+5301);
- gravitational lensing: weak;
- X-rays: galaxies: clusters;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 9 pages, 3 figures and 1 table: accepted for the publication in PASJ