Updating the $σ$-$T$ relationship for galaxy clusters
| dc.creator | Wu, Xiang-Ping | |
| dc.creator | Fang, Li-Zhi | |
| dc.creator | Xu, Wen | |
| dc.date | 1998-08-18 | |
| dc.date.accessioned | 2026-07-07T02:27:39Z | |
| dc.date.available | 2026-07-07T02:27:39Z | |
| dc.description | The relationship between the X-ray determined temperature $T$ of the intracluster gas and the optical measured velocity dispersion $σ$ of the cluster galaxies is often believed to be not only a straightforward but also robust test for the dynamical properties of galaxy clusters. Here, we present the $σ$-$T$ relationship using the 94 clusters drawn from the largest sample of 149 clusters in literature, for which both $σ$ and $T$ are observationally determined. Employment of the doubly weighted orthogonal distance regression to our sample yields $σ=10^{2.47\pm0.06}T^{0.67\pm0.09}$, indicating an apparent deviation of dynamical state from that predicted by the isothermal and hydrostatic equilibrium model for galaxy clusters, though the average ratio $β_{spec}$ of specific energy in galaxies to that in gas is found to be in excellent agreement with unity. It shows that a nonisothermal gas distribution with a mean polytropic index of $γ=1.3$ can account for the reported $σ$-$T$ relationship, while overall clusters can still be regarded as dynamically-relaxed systems. | |
| dc.description | 6 pages + 6 figures + 2 tables, A&A, in press | |
| dc.identifier | https://arxiv.org/abs/astro-ph/9808181 | |
| dc.identifier | http://arxiv.org/abs/astro-ph/9808181 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/12784 | |
| dc.subject | Astrophysics | |
| dc.title | Updating the $σ$-$T$ relationship for galaxy clusters | |
| dc.type | text |