Multiple Shock Fronts in RBS 797: The Chandra Window on Shock Heating in Galaxy Clusters

Abstract

Using ∼427 ks of Chandra observations, we present a study of shock heating and intracluster medium (ICM) cooling in the galaxy cluster RBS 797. We discover three nested pairs of weak shocks at roughly 50, 80, and 130 kpc from the center. The total energy associated with the shocks is ∼6 × 1061 erg, with the central active galactic nucleus (AGN) driving a pair of weak shocks every 20–30 Myr with a power P sh ≈ 1046 erg s−1. Based on its morphology and age (∼30 Myr), the inner cocoon shock is associated with the four equidistant X-ray cavities previously discovered. From the thermodynamic analysis of the inner 30 kpc, we find evidence for ICM condensation into colder gas between and behind the X-ray cavities. The total AGN mechanical power (cavities and shocks) of 3.4 × 1046 erg s−1 can balance the ICM radiative losses, estimated as L cool = 2.3 × 1045 erg s−1. By building plots of P cav versus L cool, P shock versus L cool, and P tot versus L cool for RBS 797 and 14 other galaxy clusters, galaxy groups, and elliptical galaxies where both cavities and shocks are detected, we verify that the most powerful outbursts are found in the strongest cooling systems. Ultimately, we observe that the mechanical power of the AGN exceeds the gas radiative losses by a factor that is different for FR I and FR II radio galaxies, being less than a few tens for FR Is (as RBS 797) and more than roughly 100 for FR IIs.

Deciphering the Morphological Origins of X-shaped Radio Galaxies: Numerical Modeling of Backflow versus Jet Reorientation

“…We find the Mach number for this shell-like shock surface to be approximately 1.5 S  . The above result further supports the argument that the presence of multiple shock fronts associated with a jet in such an ambient medium implies an older jet reorientation activity, similar to, e.g., Ubertosi et al (2023). The presence of these differently aligned shocks also demonstrates the enhanced disruptive capability of jetted structures with bent morphologies, strongly supporting the idea that these structures can cause the isotropic heating of galaxy clusters, as has been reported in a number of recent studies (e.g., see Cielo et al 2018).…”

“…A recently discovered X-ray cavity system in the galaxy cluster RBS 797 (Ubertosi et al 2021) further demonstrates the existence of an analogous example in the deep-exposure X-ray map, validating the jet-reorientation hypothesis from their multiband observations. This geometrically complex cavity distribution is surrounded by a shocked surface farther out, as also seen in Ubertosi et al (2023), resembling our acquired X-ray map, which was formed as a result of the expansion of the older jet, and consequently, of the wing expansion.…”

“…For example, Ubertosi et al (2021) have identified two pairs of cavities that are located at similar distances from the cluster center and are aligned perpendicular to each other (see also Bogdán et al 2014). An even more complex example can be found in the Perseus galaxy cluster (Fabian et al 2017), which shows offaxis cavities, rims, and a geometrically complex distribution of pressure waves (also see Ubertosi et al 2023, for the RBS 797 galaxy cluster). Other galaxy groups or clusters with such intricate cavity structures include M84 (Bambic et al 2023), NGC 5813 (Randall et al 2015), A2052 (Blanton et al 2011), NGC 5044 (David et al 2011), Cygnus A (Smith et al 2002), andMS0735.6 +7421 (McNamara et al 2009).…”

Merging galaxy clusters in IllustrisTNG

“…If there are massive structures nearby, the gas mass content of the cluster will naturally be truncated by the Subfind algorithm, and its total gas mass will be smaller. Second, the shocks occurring in the gas can be due to not only mergers between large structures but also the result of active galactic nucleus (AGN) feedback (Ubertosi et al 2023). I verified, however, that the significant AGN feedback was present in the main clusters and subclusters only at higher redshifts of z = 2 − 3, so it does not contribute to the creation of large-scale bow shocks at z = 0.…”

From birth to maturity: tracing the evolution and impact of radio galaxies

“…It also shows the ejective mode where the gas is pushed out of the galaxy, and the preventive mode of feedback, in which the hot halo is prevented from cooling and condensing onto the galaxy to form stars. Rizza et al 1999;Tremblay et al 2012;Ubertosi et al 2023;Pandge et al 2021;Liu et al 2020;Vagshette et al 2019).…”