We present the results obtained from a total of 123 ks X-ray (Chandra) and 8 hrs of 1.4 GHz radio (Giant Metrewave Radio Telescope - GMRT) observations of the cool core cluster ZwCl 2701 (z = 0.214). These observations of ZwCl 2701 showed the presence of an extensive pair of ellipsoidal cavities along the East and West directions within the central region < 20 kpc. Detection of bright rims around the cavities suggested that the radio lobes displaced X-ray emitting hot gas forming shell-like structures. The total cavity power (mechanical power) that directly heated the surrounding gas and cooling luminosity of the cluster were estimated to be ~2.27 x 10^{45} erg\s and 3.5 x 10^{44} erg\s, respectively. Comparable values of cavity power and cooling luminosity of ZwCL 2701 suggested that the mechanical power of the AGN outburst is large enough to balance the radiative cooling in the system. The star formation rate derived from the H_alpha luminosity was found to be ~0.60 M_sun yr^{-1} which is about three orders of magnitude lower than the cooling rate of ~196 M_sun yr^{-1}. Detection of the floor in entropy profile of ZwCl 2701 suggested the presence of an alternative heating mechanism at the centre of the cluster. Lower value of the ratio (~10^{-2}) between black hole mass accretion rate and Eddington mass accretion rate suggested that launching of jet from the super massive black hole is efficient in ZwCl 2701. However, higher value of ratio (~10^{3}) between black hole mass accretion rate and Bondi accretion rate indicated that the accretion rate required to create cavities is well above the Bondi accretion rate.
We aim to investigate the AGN/ICM interplay in ZwCl 235, a galaxy cluster with high X-ray flux, an extended central radio galaxy, and evidence of multi-phase gas at its center. Using archival data from the Chandra telescope, the VLASS survey, the LOTSS survey and the VLBA telescope, we perform a complete study of ZwCl 235, dissecting the dynamics of the ICM, the thermodynamic state of the central gas, and the properties of the BCG. By means of radial profiles and 2D spectral maps, we measure the temperature, entropy and cooling time of the ICM, and we compare the morphology of the central radi…
The investigation of merging galaxy clusters that exhibit radio relics is strengthening our understanding of the formation and evolution of galaxy clusters, the nature of dark matter, the intracluster medium, and astrophysical particle acceleration. Each merging cluster provides only a single view of the cluster formation process and the variety of merging clusters is vast. Clusters hosting double radio relics are rare and extremely important because they allow tight constraints on the merger scenario. We present a weak-lensing and X-ray analysis of MACSJ1752.0+4440 ($z$=0.365) and ZWCL1856.8+…
I suggest that the main process that amplifies magnetic fields in cooling flows in clusters and group of galaxies is a jet-driven dynamo (JEDD). The main processes that are behind the JEDD is the turbulence that is formed by the many vortices formed in the inflation processes of bubbles, and the large scale shear formed by the propagating jet. It is sufficient that a strong turbulence exits in the vicinity of the jets and bubbles, just where the shear is large. The typical amplification time of magnetic fields by the JEDD near the jets and bubbles is approximately hundred million years. The am…
We present a deep Suzaku observation of H1821+643, an extremely rare example of a powerful quasar hosted by the central massive galaxy of a rich cooling-core cluster of galaxies. Informed by previous Chandra studies of the cluster, we achieve a spectral separation of emission from the active galactic nucleus (AGN) and the intracluster medium (ICM). With a high degree of confidence, we identify the signatures of X-ray reflection/reprocessing by cold and slowly moving material in the AGN's immediate environment. The iron abundance of this matter is found to be significantly sub-solar (Z~0.4Zsun)…
Magnetic fields in the intracluster medium with TNG-Cluster: properties, morphology, and tangential anisotropy
Universität Heidelberg, Zentrum für Astronomie（海德堡大学天文学中心）；Universität Heidelberg, Interdisziplinäres Zentrum für Wissenschaftliches Rechnen（海德堡大学跨学科科学计算中心）；Max-Planck-Institut für Astronomie（马克斯·普朗克天文学研究所）；Centre de recherche en astrophysique du Quebec (CRAQ)（魁北克天体物理学研究中心）
We present the results of an X-ray spectral analysis of 153 galaxy clusters observed with the Chandra, XMM-Newton, and Suzaku space telescopes. These clusters, which span 0 < z < 1.5, were drawn from a larger, mass-selected sample of galaxy clusters discovered in the 2500 square degree South Pole Telescope Sunyaev Zel'dovich (SPT-SZ) survey. With a total combined exposure time of 9.1 Ms, these data yield the strongest constraints to date on the evolution of the metal content of the intracluster medium (ICM). We find no evidence for strong evolution in the global (r<R500) ICM metallicity (dZ/dz…
We present a detailed study of the thermodynamic properties of the intracluster medium of the only low redshift galaxy cluster to contain a highly luminous quasar, H1821+643. The cluster is a highly massive, strong cool core cluster. We find that the ICM entropy around the quasar is significantly lower than that of other similarly massive strong cool core clusters within the central 80 kpc, and that the entropy lies significantly below the extrapolated baseline entropy profile from hierarchical structure formation. By comparing the scaled temperature profile with those of other strong cool cor…
We present far-UV spectroscopy from the Cosmic Origins Spectrograph on the Hubble Space Telescope of a cool, star-forming filament in the core of Abell 1795. These data, which span 1025A - 1700A, allow for the simultaneous modeling of the young stellar populations and the intermediate-temperature (10^5.5 K) gas in this filament, which is far removed (~30 kpc) from the direct influence of the central AGN. Using a combination of UV absorption line indices and stellar population synthesis modeling, we find evidence for ongoing star formation, with the youngest stars having ages of 7.5 +/- 2.0 Myr…
Cool cluster cores are in global thermal equilibrium but are locally thermally unstable. We study a nonlinear phenomenological model for the evolution of density perturbations in the ICM due to local thermal instability and gravity. We have analyzed and extended a model for the evolution of an over-dense blob in the ICM. We find two regimes in which the over-dense blobs can cool to thermally stable low temperatures. One for large $t_{\rm {cool}} / t_{\rm {ff}}$ ($t_{\rm {cool}}$ is the cooling time and $t_{\rm {ff}}$ is the free fall time), where a large initial over-density is required for th…
Kinetic structure of the intracluster medium across nearby clusters observed with XRISM
Nara Women’s University（奈良女子大学）；Argelander-Institut für Astronomie (AIfA), Universität Bonn（波恩大学阿尔兰德天文学研究所）；Frontier Research Institute for Interdisciplinary Sciences, Tohoku University（东北大学前沿交叉科学研究院）；University of Geneva（日内瓦大学）；Astronomical Institute, Tohoku University（东北大学天文研究所）；Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA)（日本宇宙航空研究开发机构空间科学研究所）
Using high-resolution hydrodynamical simulations of galaxy clusters, we study the interaction between the brightest cluster galaxy, its supermassive black hole (BH) and the intracluster medium (ICM). We create initial conditions for which the ICM is in hydrostatic equilibrium within the gravitational potential from the galaxy and an NFW dark matter halo. Two free parameters associated with the thermodynamic profiles determine the cluster gas fraction and the central temperature, where the latter can be used to create cool-core or non-cool-core systems. Our simulations include radiative cooling…
Cosmological simulations, as well as mounting evidence from observations, have shown that supermassive black holes play a fundamental role in regulating the formation of stars throughout cosmic time. This has been clearly demonstrated in the case of galaxy clusters in which powerful feedback from the central black hole is preventing the hot intracluster gas from cooling catastrophically, thus reducing the expected star formation rates by orders of magnitude. These conclusions have however been almost entirely based on nearby clusters. Based on new Chandra X-ray observations, we present the fir…
We use recent X-ray observations of the intracluster medium (ICM) of the galaxy group NGC 5813 to confront theoretical studies of ICM thermal evolution with the newly derived ICM properties. We argue that the ICM of the cooling flow galaxy group NGC 5813 is more likely to be heated by mixing of post-shock jets' gas residing in hot bubbles with the ICM, than by shocks or turbulent-heating. Shocks thermalize only a small fraction of their energy in the inner regions of the cooling flow; in order to adequately heat the inner part of the ICM, they would overheat the outer regions by a large factor…
We study the nature of feedback mechanisms in the 11 CLASH brightest cluster galaxies (BCGs) that exhibit extended ultraviolet and nebular line emission features. We estimate star formation rates (SFRs), dust masses, and starburst durations using a Bayesian photometry-fitting technique that accounts for both stellar and dust emission from the UV through far IR. By comparing these quantities to intracluster medium (ICM) cooling times and free-fall times derived from X-ray observations and lensing estimates of the cluster mass distribution, we discover a tight relationship between the BCG SFR an…
The distribution of metals in the intra-cluster medium encodes important information about the enrichment history and formation of galaxy clusters. Here we explore the metal content of clusters in IllustrisTNG - a new suite of galaxy formation simulations building on the Illustris project. Our cluster sample contains 20 objects in TNG100 - a ~(100 Mpc)^3 volume simulation with 2x1820^3 resolution elements, and 370 objects in TNG300 - a ~(300 Mpc)^3 volume simulation with 2x2500^3 resolution elements. The z=0 metallicity profiles agree with observations, and the enrichment history is consistent…
We conduct two kinds of homogeneous isotropic turbulence simulations relevant for the intracluster medium (ICM): (i) pure turbulence runs without radiative cooling; (ii) turbulent heating$+$radiative cooling runs with global thermal balance. For pure turbulence runs in the subsonic regime, the rms density and surface brightness (SB) fluctuations vary as the square of the rms Mach number ($\mathcal{M}_{\text{rms}}$). However, with thermal balance, the density and SB fluctuations $(δSB/SB)$ are much larger. These scalings have implications for translating SB fluctuations into a turbulent velocit…
Quasar absorption-line studies in the ultraviolet (UV) can uniquely probe the nature of the multiphase cool-warm (10^4 < T < 10^6 K) gas in and around galaxy clusters, promising to provide unprecedented insights into 1) interactions between the circumgalactic medium (CGM) associated with infalling galaxies and the hot (T > 10^6 K) X-ray emitting intracluster medium (ICM), 2) the stripping of metal-rich gas from the CGM, and 3) a multiphase structure of the ICM with a wide range of temperatures and metallicities. In this work, we present results from a high-resolution simulation of a ~10^14 sol…
Active galactic nucleus driven jet feedback in cosmologically forming cool-core galaxy clusters I: The effect of hierarchical assembly on intra-cluster medium properties
Leibniz Institute for Astrophysics Potsdam (AIP)（波茨坦阿基米德天体物理研究所）；Niels Bohr Institute（尼尔斯·玻尔研究所）；Universität Potsdam（波茨坦大学）；Max-Planck-Institut für Astrophysik（马克斯·普朗克天体物理研究所）
Galaxy groups are more than an intermediate scale between clusters and halos hosting individual galaxies, they are crucial laboratories capable of testing a range of astrophysics from how galaxies form and evolve to large scale structure (LSS) statistics for cosmology. Cosmological hydrodynamic simulations of groups on various scales offer an unparalleled testing ground for astrophysical theories. Widely used cosmological simulations with ~(100 Mpc)^3 volumes contain statistical samples of groups that provide important tests of galaxy evolution influenced by environmental processes. Larger vol…
We present new MUSE observations of a galaxy group probed by a background quasar. The quasar sightline passes between multiple $z=0.28$ galaxies, whilst showing at the same redshift low ionised metal line species, including Ca II, Mg I, Mg II and Fe II. Based on the galaxy redshifts measured from the MUSE data, we estimate the galaxies to be part of a small galaxy group with a halo mass of $\approx6\times10^{12}$ M$_{\odot}$. We use the MUSE data to reveal the two dimensional dynamical properties of the gas and stars in the group galaxies, and relate these to the absorber kinematics. With thes…
We present an ultraviolet quasar absorption line analysis of metal lines associated with three strong intervening H I absorbers (with $N$(H I) $>$ 10$^{16.5}$ cm$^{-2}$) detected in the outskirts of Sunyaev-Zel'dovich (SZ) effect-selected galaxy clusters ($z_{\rm cl} \sim 0.4 - 0.5$), within clustocentric impact parameters of $ρ_{cl}$ $\sim$ $(1.6 - 4.7)r_{500}$. Discovered in a recent set of targeted far-UV $HST$/COS spectroscopic observations, these absorbers have the highest H I column densities ever observed in the outskirts of galaxy clusters, and are also rich in metal absorption lines. …
Feedback from active galactic nuclei (AGN) is believed to prevent catastrophic cooling in galaxy clusters. However, how the feedback energy is transformed into heat, and how the AGN jets heat the intracluster medium (ICM) isotropically, still remain elusive. In this work, we gain insights into the relative importance of different heating mechanisms using three-dimensional hydrodynamic simulations including cold gas accretion and momentum-driven jet feedback, which are the most successful models to date in terms reproducing the properties of cool cores. We find that there is net heating within …
The discrepancy between expected and observed cooling rates of X-ray emitting gas has led to the {\it cooling flow problem} at the cores of clusters of galaxies. A variety of models have been proposed to model the observed X-ray spectra and resolve the cooling flow problem, which involves heating the cold gas through different mechanisms. As a result, realistic models of X-ray spectra of galaxy clusters need to involve both heating {\it and} cooling mechanisms. In this paper, we argue that the heating time-scale is set by the magnetohydrodynamic (MHD) turbulent viscous heating for the Intraclu…
Several galaxy clusters are known to present multiple and misaligned pairs of cavities seen in X-rays, as well as twisted kiloparsec-scale jets at radio wavelengths. It suggests that the AGN precessing jets play a role in the formation of the misaligned bubbles. Also, X-ray spectra reveal that typically these systems are also able to supress cooling flows, predicted theoretically. The absence of cooling flows in galaxy clusters has been a mistery for many years since numerical simulations and analytical studies suggest that AGN jets are highly energetic, but are unable to redistribute it at al…
We analyze our earlier three-dimensional hydrodynamical numerical simulation of jet-inflated bubbles in cooling flow clusters, and find that dense gas that was not heated by the jets' activity and that resides around the hot jet-inflated bubbles can be identified as uplifted gas as observed in some clusters. During the build up of the dense gas around the hot bubble, mixing of hot bubble gas with other regions of the intracluster medium (ICM) heats the ICM. The vortices that mix the ICM with the hot bubble gas also excite shock waves, sound waves, and turbulence. Sound waves, shocks, turbulenc…
Clusters of galaxies are outstanding laboratories for understanding the physics of supermassive black hole feedback. Here, we present the first \textit{Chandra}, Karl G. Janksy Very Large Array and \textit{Hubble Space Telescope} analysis of MACS J1447.4+0827 ($z = 0.3755$), one of the strongest cool core clusters known, in which extreme feedback from its central supermassive black hole is needed to prevent the hot intracluster gas from cooling. Using this multiwavelength approach, including 70 ks of \textit{Chandra} X-ray observations, we detect the presence of collimated jetted-outflows that…
The hot intra-cluster medium (ICM) permeating galaxy clusters and groups is not pristine, as it is continuously enriched by metals synthesised in Type Ia (SNIa) and core-collapse (SNcc) supernovae since the major epoch of star formation (z ~ 2-3). The cluster/group enrichment history and the mechanisms responsible for releasing and mixing the metals can be probed via the radial distribution of SNIa and SNcc products within the ICM. In this paper, we use deep XMM-Newton/EPIC observations from a sample of 44 nearby cool-core galaxy clusters, groups, and ellipticals (CHEERS) to constrain the aver…
We survey the incidence and absorption strength of the metal-line transitions CII 1334 and CIV from the circumgalactic medium (CGM) surrounding z~2 quasars, which act as signposts for massive dark matter halos M_halo~10^12.5 Msun. On scales of the virial radius (Mvir~160kpc), we measure a high covering fraction fC=0.73+/-0.10 to strong CII absorption (rest equivalent width W1334>0.2A), implying a massive reservoir of cool (T~10^4K) metal enriched gas. We conservatively estimate a metal mass exceeding 10^8 Msun. We propose these metals trace enrichment of the incipient intragroup/intracluster m…
We examine the heating of the intra-cluster medium (ICM) of cooling flow clusters of galaxies by jet-inflated bubbles and conclude that mixing of hot bubble gas with the ICM is more important than turbulent heating and shock heating. We use the PLUTO hydrodynamical code in full 3D to properly account for the inflation of the bubbles and to the multiple vortices induced by the jets and bubbles. The vortices mix some hot shocked jet gas with the ICM. For the parameters used by us the mixing process accounts for about four times as much heating as that by the kinetic energy in the ICM, namely, tu…
We place constraints on the propagation velocity of bulk turbulence within the intracluster medium of three clusters and an elliptical galaxy. Using Reflection Grating Spectrometer measurements of turbulent line broadening, we show that for these clusters, the 90% upper limit on turbulent velocities when accounting for instrumental broadening is too low to propagate energy radially to the cooling radius of the clusters within the required cooling time. In this way, we extend previous Hitomi-based analysis on the Perseus cluster to more clusters, with the intention of applying these results to …
