Astronomy and Astrophysics – Astrophysics
Scientific paper
2001-04-11
Astrophys.J. 553 (2001) L15-L18
Astronomy and Astrophysics
Astrophysics
4 pages, 1 figure, Accepted for Publication in The Astrophysical Journal Letters, updated references
Scientific paper
10.1086/320500
Previously it has been recognized that radio halos in galaxy clusters are preferentially associated with merging systems as indicated by substructure in the X-ray images and temperature maps. Since, however, many clusters without radio halos also possess substructure, the role of mergers in the formation of radio halos has remained unclear. By using power ratios to relate gravitational potential fluctuations to substructure in X-ray images, we provide the first quantitative comparison of the dynamical states of clusters possessing radio halos. A correlation between the 1.4 GHz power (P_{1.4}) of the radio halo (or relic) and the magnitude of the dipole power ratio (P_1/P_0) is discovered such that approximately P_{1.4} ~ P_1/P_0; i.e., the strongest radio halos appear only in those clusters currently experiencing the largest departures from a virialized state. From additional consideration of a small number of highly disturbed clusters without radio halos detected at 1.4 GHz, and recalling that radio halos are more common in clusters with high X-ray luminosity (Giovannini, Tordi, & Feretti), we argue that radio halos form preferentially in massive (L_x >~ 0.5 x 10^{45} erg/s) clusters experiencing violent mergers (P_1/P_0 >~ 0.5 x 10^{-4}) that have seriously disrupted the cluster core. The association of radio halos with massive, large-P_1/P_0, core-disrupted clusters is able to account for both the vital role of mergers in accelerating the relativistic particles responsible for the radio emission as well as the rare occurrence of radio halos in cluster samples.
No associations
LandOfFree
On The Origin of Radio Halos in Galaxy Clusters does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with On The Origin of Radio Halos in Galaxy Clusters, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and On The Origin of Radio Halos in Galaxy Clusters will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-441316