scholarly journals The relation between the diffuse X-ray luminosity and the radio power of the central AGN in galaxy groups

2020 ◽  
Vol 497 (2) ◽  
pp. 2163-2174
Author(s):  
T Pasini ◽  
M Brüggen ◽  
F de Gasperin ◽  
L Bîrzan ◽  
E O’Sullivan ◽  
...  
Keyword(s):  
Radio Emission ◽  
Galaxy Clusters ◽  
Active Galactic Nucleus ◽  
Statistical Tests ◽  
Control Sample ◽  
Radio Galaxies ◽  
Very Large Array ◽  
X Ray ◽  
Galaxy Groups ◽  
Hydrodynamical Simulations

ABSTRACT Our understanding of how active galactic nucleus feedback operates in galaxy clusters has improved in recent years owing to large efforts in multiwavelength observations and hydrodynamical simulations. However, it is much less clear how feedback operates in galaxy groups, which have shallower gravitational potentials. In this work, using very deep Very Large Array and new MeerKAT observations from the MIGHTEE survey, we compiled a sample of 247 X-ray selected galaxy groups detected in the COSMOS field. We have studied the relation between the X-ray emission of the intra-group medium and the 1.4 GHz radio emission of the central radio galaxy. For comparison, we have also built a control sample of 142 galaxy clusters using ROSAT and NVSS data. We find that clusters and groups follow the same correlation between X-ray and radio emission. Large radio galaxies hosted in the centres of groups and merging clusters increase the scatter of the distribution. Using statistical tests and Monte Carlo simulations, we show that the correlation is not dominated by biases or selection effects. We also find that galaxy groups are more likely than clusters to host large radio galaxies, perhaps owing to the lower ambient gas density or a more efficient accretion mode. In these groups, radiative cooling of the intra-cluster medium could be less suppressed by active galactic nucleus heating. We conclude that the feedback processes that operate in galaxy clusters are also effective in groups.

scholarly journals Cosmic dance in the Shapley Concentration Core

2018 ◽  
Vol 620 ◽  
pp. A25
Author(s):  
G. Di Gennaro ◽  
T. Venturi ◽  
D. Dallacasa ◽  
S. Giacintucci ◽  
P. Merluzzi ◽  
...  
Keyword(s):  
Radio Emission ◽  
Galaxy Clusters ◽  
Radio Galaxies ◽  
Wide Field ◽  
Host Galaxies ◽  
Very Large Array ◽  
Cluster Complexes ◽  
Dynamical State ◽  
Sky Survey ◽  
Radio Band

Context. The Shapley Concentration (⟨z⟩ ≈ 0.048) covers several degrees in the southern hemisphere, and includes galaxy clusters in advanced evolutionary stages, groups of clusters in the very early stages of merger, fairly massive clusters with ongoing accretion activity, and smaller groups located in filaments in the regions between the main clusters. Aims. With the goal to investigate the role of cluster mergers and accretion on the radio galaxy population, we performed a multi-wavelength study of the brightest cluster galaxies (BCGs) and of the galaxies showing extended radio emission in the cluster complexes of Abell 3528 and Abell 3558. In total, our study is based on a sample of 12 galaxies. Methods. We observed the clusters with the Giant Metrewave Radio Telescope (GMRT) at 235, 325, and 610 MHz, and with the Very Large Array (VLA) at 8.46 GHz. We complemented our study with the TIFR GMRT Sky Survey (TGSS) at 150 MHz, the Sydney University Molonglo Sky Survey (SUMSS) at 843 MHz, and the Australia Telescope Compact array (ATCA) at 1380, 1400, 2380, and 4790 MHz data. Finally, optical imaging with the VLT Survey Telescope (VST) is also available for the host galaxies as well as the mid-infrared coverage with the Wide-Field Infrared Survey Explorer (WISE). Results. We found significant differences in the properties of the radio emission of the BCGs in the two cluster complexes. The BCGs in the A 3528 complex and in A 3556, which are relaxed cool-core objects, are powerful active radio galaxies. They also present hints of restarted activity. On the contrary, the BCGs in A 3558 and A 3562, which are well-known merging systems, are very faint, or quiet, in the radio band. The optical and infrared properties of the galaxies, on the other hand, are fairly similar in the two complexes, showing all passive red galaxies. Conclusions. Our study shows remarkable differences in the radio properties of the BGCs, which we relate to the different dynamical state of the host cluster. On the contrary, the lack of changes between such different environments in the optical band suggests that the dynamical state of galaxy clusters does not affect the optical counterparts of the radio galaxies, at least over the lifetime of the radio emission.

scholarly journals Caught in the Act: Witnessing a~Transforming Spiral in a Galaxy Group

2006 ◽  
Vol 2 (S235) ◽  
pp. 239-239
Author(s):  
J. Rasmussen ◽  
T. J. Ponman ◽  
J. S. Mulchaey
Keyword(s):  
Galaxy Clusters ◽  
Direct Evidence ◽  
X Ray ◽  
Galaxy Groups ◽  
Ram Pressure

AbstractRam pressure stripping of galaxies is believed to be inefficient in galaxy groups, but Chandra X-ray observations of the starburst spiral NGC 2276, a member of a small galaxy group, shows that this galaxy is being stripped of its gas at a rate of ~5 M⊙ yr−1 due to its motion through hot intragroup gas. This provides direct evidence that mechanisms associated with ram pressure can strip galaxies of their gas in systems much smaller than galaxy clusters.

scholarly journals Athena X-IFU synthetic observations of galaxy clusters to probe the chemical enrichment of the Universe

2018 ◽  
Vol 620 ◽  
pp. A173 ◽  
Author(s):  
E. Cucchetti ◽  
E. Pointecouteau ◽  
P. Peille ◽  
N. Clerc ◽  
E. Rasia ◽  
...  
Keyword(s):  
Galaxy Clusters ◽  
Chemical Elements ◽  
Cosmic Time ◽  
Initial Mass Function ◽  
Metal Production ◽  
X Ray ◽  
Chemical Enrichment ◽  
Spatially Resolved ◽  
Hydrodynamical Simulations ◽  
The Universe

Answers to the metal production of the Universe can be found in galaxy clusters, notably within their intra-cluster medium (ICM). The X-ray Integral Field Unit (X-IFU) on board the next-generation European X-ray observatory Athena (2030s) will provide the necessary leap forward in spatially-resolved spectroscopy required to disentangle the intricate mechanisms responsible for this chemical enrichment. In this paper, we investigate the future capabilities of the X-IFU in probing the hot gas within galaxy clusters. From a test sample of four clusters extracted from cosmological hydrodynamical simulations, we present comprehensive synthetic observations of these clusters at different redshifts (up to z ≤ 2) and within the scaled radius R500 performed using the instrument simulator SIXTE. Through 100 ks exposures, we demonstrate that the X-IFU will provide spatially resolved mapping of the ICM physical properties with little to no biases (⪅5%) and well within statistical uncertainties. The detailed study of abundance profiles and abundance ratios within R500 also highlights the power of the X-IFU in providing constraints on the various enrichment models. From synthetic observations out to z = 2, we have also quantified its ability to track the chemical elements across cosmic time with excellent accuracy, and thereby to investigate the evolution of metal production mechanisms as well as the link to the stellar initial mass-function. Our study demonstrates the unprecedented capabilities of the X-IFU of unveiling the properties of the ICM but also stresses the data analysis challenges faced by future high-resolution X-ray missions such as Athena.

scholarly journals Particle re-acceleration and Faraday-complex structures in the RXC J1314.4-2515 galaxy cluster

2019 ◽  
Author(s):  
C Stuardi ◽  
A Bonafede ◽  
D Wittor ◽  
F Vazza ◽  
A Botteon ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Galaxy Clusters ◽  
Galaxy Cluster ◽  
Complex Structures ◽  
Very Large Array ◽  
Rotation Measure ◽  
Low Levels ◽  
Hydrodynamical Simulations ◽  
Polarization Fraction ◽  
The Magnetic Field

Abstract Radio relics are sites of electron (re)acceleration in merging galaxy clusters but the mechanism of acceleration and the topology of the magnetic field in and near relics are yet to be understood. We are carrying out an observational campaign on double relic galaxy clusters starting with RXC J1314.4-2515. With Jansky Very Large Array multi-configuration observations in the frequency range 1-4 GHz, we perform both spectral and polarization analyses, using the Rotation Measure synthesis technique. We use archival XMM-Newton observations to constrain the properties of the shocked region. We discover a possible connection between the activity of a radio galaxy and the emission of the eastern radio relic. In the northern elongated arc of the western radio relic, we detect polarized emission with an average polarization fraction of 31 % at 3 GHz and we derive the Mach number of the underlying X-ray shock. Our observations reveal low levels of fractional polarization and Faraday-complex structures in the southern region of the relic, which point to the presence of thermal gas and filamentary magnetic field morphology inside the radio emitting volume. We measured largely different Rotation Measure dispersion from the two relics. Finally, we use cosmological magneto-hydrodynamical simulations to constrain the magnetic field, viewing angle, and to derive the acceleration efficiency of the shock. We find that the polarization properties of RXC J1314.4-2515 are consistent with a radio relic observed at 70○ with respect to the line of sight and that efficient re-acceleration of fossil electrons has taken place.

scholarly journals AGN Feedback in Galaxy Groups: A Detailed Study of X-Ray Features and Diffuse Radio Emission in IC 1262

2019 ◽  
Vol 870 (2) ◽  
pp. 62
Author(s):  
M. B. Pandge ◽  
S. S. Sonkamble ◽  
Viral Parekh ◽  
Pratik Dabhade ◽  
Avni Parmar ◽  
...  
Keyword(s):  
Radio Emission ◽  
X Ray ◽  
Galaxy Groups

scholarly journals Precessing AGN jets, bubbles and cooling flows

2010 ◽  
Vol 6 (S275) ◽  
Author(s):  
D. Falceta-Gonçalves ◽  
A. Caproni ◽  
Z. Abraham ◽  
E. M. de Gouveia Dal Pino ◽  
D. M. Teixeira
Keyword(s):  
Galaxy Clusters ◽  
Flow Problem ◽  
X Rays ◽  
Intracluster Medium ◽  
X Ray ◽  
Cooling Flows ◽  
Cooling Flow ◽  
Central Regions ◽  
Multiple Bubbles ◽  
Hydrodynamical Simulations

AbstractSeveral 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 all directions. We performed 3D hydrodynamical simulations of the interaction between a precessing AGN jet and the warm intracluster medium plasma, in which dynamics is coupled to a NFW dark matter gravitational potential. Radiative cooling has been taken into account and the cooling flow problem was studied. We found that precession is responsible for multiple pairs of bubbles, as observed. The misaligned bubbles rise up to scales of tens of kiloparsecs, where the thermal energy released by the jets are redistributed. After ~150 Myrs, the temperature of the gas within the cavities is kept of order of ~107 K, while the denser plasma of the intracluster medium at the central regions reaches T ~ 105 K. The existence of multiple bubbles, at diferent directions, results in an integrated temperature along the line of sight much larger than the simulations of non-precessing jets. This result is in agreement with the observations. The simulations reveal that the cooling flows cessed ~50–70 Myr after the AGN jets are started.

scholarly journals Cosmological hydrodynamical simulations of galaxy clusters: X-ray scaling relations and their evolution

2017 ◽  
Vol 474 (3) ◽  
pp. 4089-4111 ◽  
Author(s):  
N Truong ◽  
E Rasia ◽  
P Mazzotta ◽  
S Planelles ◽  
V Biffi ◽  
...  
Keyword(s):  
Galaxy Clusters ◽  
Scaling Relations ◽  
X Ray ◽  
Hydrodynamical Simulations

scholarly journals A giant radio bridge connecting two clusters in Abell 1758

2020 ◽  
Author(s):  
A Botteon ◽  
R J van Weeren ◽  
G Brunetti ◽  
F de Gasperin ◽  
H T Intema ◽  
...  
Keyword(s):  
Radio Emission ◽  
Galaxy Clusters ◽  
Large Scale ◽  
Synchrotron Emission ◽  
X Ray ◽  
Compressed Gas ◽  
Order Of Magnitude ◽  
Thermal Phenomena ◽  
Cluster Pair ◽  
Radio Halos

Abstract Collisions between galaxy clusters dissipate enormous amounts of energy in the intra-cluster medium (ICM) through turbulence and shocks. In the process, Mpc-scale diffuse synchrotron emission in form of radio halos and relics can form. However, little is known about the very early phase of the collision. We used deep radio observations from 53 MHz to 1.5 GHz to study the pre-merging galaxy clusters A1758N and A1758S that are ∼2 Mpc apart. We confirm the presence of a giant bridge of radio emission connecting the two systems that was reported only tentatively in our earlier work. This is the second large-scale radio bridge observed to date in a cluster pair. The bridge is clearly visible in the LOFAR image at 144 MHz and tentatively detected at 53 MHz. Its mean radio emissivity is more than one order of magnitude lower than that of the radio halos in A1758N and A1758S. Interestingly, the radio and X-ray emissions of the bridge are correlated. Our results indicate that non-thermal phenomena in the ICM can be generated also in the region of compressed gas in-between infalling systems.

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