Speaker
Description
Cygnus A (CygA) is one of the most famous radio sources, and it has clear evidence of the central active galactic nucleus (AGN) interacting with its environment. The AGN is driving a cocoon shock that adds $10^{60}-10^{61}$ ergs of energy into the cluster gas surrounding CygA. The proximity of CygA ($z=0.0561$) allows us to answer two critical questions in cluster physics: (1) Which processes are most important to dissipate the energy from the AGN? (2) What are their relative contributions? In the last twenty years, Chandra and XMM-Newton constrained energy injection due to shocks and cavities in CygA. The recently launched XRISM telescope promises to build upon this knowledge by enabling precise measurements of gas motion and turbulence, speculated to be another important dissipation mechanism.
We present results from a 170 ks observation of CygA. We find a turbulent velocity of $\sim$260 km/s in the intracluster medium, corresponding to an energy injection of similar magnitude as the cocoon shocks, assuming that these motions eventually dissipate into heat. CygA has one of the most turbulent cluster environment among all clusters detected by XRISM so far. There is also an indication of non-Gaussian line profiles presumably due to the expansion of the cocoon. Furthermore, the shape of the 6.4 keV iron line from the AGN indicates reflection from both the accretion disk and torus region. Our work promises to significantly enhance our knowledge of both the central engine and the gas surrounding CygA.
| Talk category | NOVA Network 3 |
|---|---|
| Preference for a talk or poster | Talk |
