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We present the analysis of new, deep Chandra observations (130 ks) of the galaxy cluster A2495. This object is known for the presence of a triple offset between the peaks of the intracluster medium (ICM), the brightest cluster galaxy (BCG), and the warm gas glowing in H α line. The new Chandra data confirm that the X-ray emission peak is located at a distance of ∼6.2 kpc from the BCG, and at ∼3.9 kpc from the H α emission peak. Moreover, we identify two generations of X-ray cavities in the ICM, likely inflated by the central radio galaxy activity. Through a detailed morphological and spectral analysis, we determine that the power of the active galactic nucleus (AGN) outbursts ( P _cav = 4.7 ± 1.3 × 10 ^43 erg s ^−1 ) is enough to counterbalance the radiative losses from ICM cooling ( L _cool = 5.7 ± 0.1 × 10 ^43 erg s ^−1 ). This indicates that, despite a fragmented cooling core, A2495 still harbors an effective feedback cycle. We argue that the offsets are most likely caused by sloshing of the ICM, supported by the presence of spiral structures and a probable cold front in the gas at ∼58 kpc east of the center. Ultimately, we find that the outburst interval between the two generations of X-ray cavities is of the order of the dynamical sloshing timescale, as already hinted from the previous Chandra snapshot. We thus speculate that sloshing may be able to regulate the timescales of AGN feedback in A2495, by periodically fueling the central AGN.

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 × 10 ^61 erg, with the central active galactic nucleus (AGN) driving a pair of weak shocks every 20–30 Myr with a power P _sh ≈ 10 ^46 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 × 10 ^46 erg s ^−1 can balance the ICM radiative losses, estimated as L _cool = 2.3 × 10 ^45 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.

We present a combined radio/X-ray analysis of the poorly studied galaxy cluster A2495 (z = 0.07923) based on new EVLA and Chandra data. We also analyze and discuss Hα emission and optical continuum data retrieved from the literature. We find an offset of ∼6 kpc between the cluster brightest cluster galaxy (BCG) (MCG+02-58-021) and the peak of the X-ray emission, suggesting that the cooling process is not taking place on the central galaxy nucleus. We propose that sloshing of the intracluster medium (ICM) could be responsible for this separation. Furthermore, we detect a second, ∼4 kpc offset between the peak of the Hα emission and that of the X-ray emission. Optical images highlight the presence of a dust filament extending up to ∼6 kpc in the cluster BCG and allow us to estimate a dust mass within the central 7 kpc of 1.7 × 105M☉. Exploiting the dust-to-gas ratio and the LHα–Mmol relation, we argue that a significant amount (up to 109M☉) of molecular gas should be present in the BCG of this cluster. We also investigate the presence of ICM depressions, finding two putative systems of cavities; the inner pair is characterized by tage ∼ 18 Myr and Pcav ∼ 1.2 × 1043 erg s−1, the outer one by tage ∼ 53 Myr and Pcav ∼ 5.6 × 1042 erg s−1. Their age difference appears to be consistent with the freefall time of the central cooling gas and with the offset timescale estimated with the Hα kinematic data, suggesting that sloshing is likely playing a key role in this environment. Furthermore, the cavities’ power analysis shows that the active galactic nucleus energy injection is able to sustain the feedback cycle, despite cooling being offset from the BCG nucleus. [ABSTRACT FROM AUTHOR]