scholarly journals Discovery of radio jets in the Phoenix galaxy cluster center

2020 ◽  
Vol 72 (4) ◽  
Author(s):  
Takuya Akahori ◽  
Tetsu Kitayama ◽  
Shutaro Ueda ◽  
Takuma Izumi ◽  
Kianhong Lee ◽  
...  
Keyword(s):  
Radio Emission ◽  
Dust Emission ◽  
Galaxy Cluster ◽  
Cluster Center ◽  
Cluster Galaxy ◽  
Cooling Flow ◽  
Radio Jets ◽  
Spatially Resolved ◽  
Extended Radio ◽  
The Phoenix

Abstract We report the results of the Australia Telescope Compact Array (ATCA) 15 mm observation of the Phoenix galaxy cluster possessing an extreme star-burst brightest cluster galaxy (BCG) at the cluster center. We spatially resolved radio emission around the BCG, and found diffuse bipolar and bar-shape structures extending from the active galactic nucleus (AGN) of the BCG. They are likely radio jets/lobes, whose sizes are ∼10–20 kpc and locations are aligned with X-ray cavities. If we assume that the radio jets/lobes expand with the sound velocity, their ages are estimated to be ∼10 Myr. We also found compact radio emissions near the center and suggest that they are more young bipolar jets ∼1 Myr in age. Moreover, we found extended radio emission surrounding the AGN and discussed the possibility that the component is a product of the cooling flow, by considering synchrotron radiation partially absorbed by molecular clumps, free–free emission from the warm ionized gas, and the spinning dust emission from the dusty circumgalactic medium.

scholarly journals Prevalence of radio jets associated with galactic outflows and feedback from quasars

2019 ◽  
Vol 485 (2) ◽  
pp. 2710-2730 ◽  
Author(s):  
M E Jarvis ◽  
C M Harrison ◽  
A P Thomson ◽  
C Circosta ◽  
V Mainieri ◽  
...  
Keyword(s):  
Radio Emission ◽  
Feedback Mechanism ◽  
Ionized Gas ◽  
Massive Galaxies ◽  
Gas Kinematics ◽  
Radio Jets ◽  
Spatially Resolved ◽  
Radio Imaging ◽  
Extended Radio ◽  
Distinct Features

Abstract We present 1–7 GHz high-resolution radio imaging (VLA and e-MERLIN) and spatially resolved ionized gas kinematics for 10 z < 0.2 type 2 ‘obscured’ quasars (log [LAGN/erg s−1] ≳ 45) with moderate radio luminosities ($\log [L_{\rm {1.4\,GHz}}$/W Hz−1]  = 23.3–24.4). These targets were selected to have known ionized outflows based on broad [O iii] emission-line components (full width at half-maximum ≈ 800–1800 km s−1). Although ‘radio-quiet’ and not ‘radio AGN’ by many traditional criteria, we show that for nine of the targets, star formation likely accounts for ≲10 per cent of the radio emission. We find that ∼80–90 per cent of these nine targets exhibit extended radio structures on 1–25 kpc scales. The quasars’ radio morphologies, spectral indices, and position on the radio size–luminosity relationship reveals that these sources are consistent with being low power compact radio galaxies. Therefore, we favour radio jets as dominating the radio emission in the majority of these quasars. The radio jets we observe are associated with morphologically and kinematically distinct features in the ionized gas, such as increased turbulence and outflowing bubbles, revealing jet–gas interaction on galactic scales. Importantly, such conclusions could not have been drawn from current low-resolution radio surveys such as FIRST. Our observations support a scenario where compact radio jets, with modest radio luminosities, are a crucial feedback mechanism for massive galaxies during a quasar phase.

scholarly journals Mystery solved: discovery of extended radio emission in the merging galaxy cluster Abell 2146

2017 ◽  
Vol 475 (2) ◽  
pp. 2743-2753 ◽  
Author(s):  
J Hlavacek-Larrondo ◽  
M-L Gendron-Marsolais ◽  
D Fecteau-Beaucage ◽  
R J van Weeren ◽  
H R Russell ◽  
...  
Keyword(s):  
Radio Emission ◽  
Galaxy Cluster ◽  
Extended Radio

scholarly journals Radio observations of the merging galaxy cluster Abell 520

2019 ◽  
Vol 622 ◽  
pp. A20 ◽  
Author(s):  
D. N. Hoang ◽  
T. W. Shimwell ◽  
R. J. van Weeren ◽  
G. Brunetti ◽  
H. J. A. Röttgering ◽  
...  
Keyword(s):  
Mach Number ◽  
Radio Emission ◽  
Low Frequency ◽  
Galaxy Cluster ◽  
Shock Acceleration ◽  
Relativistic Electrons ◽  
Diffusive Shock Acceleration ◽  
Cluster Emission ◽  
X Ray ◽  
Extended Radio

Context. Extended synchrotron radio sources are often observed in merging galaxy clusters. Studies of the extended emission help us to understand the mechanisms in which the radio emitting particles gain their relativistic energies. Aims. We examine the possible acceleration mechanisms of the relativistic particles that are responsible for the extended radio emission in the merging galaxy cluster Abell 520. Methods. We performed new 145 MHz observations with the LOw Frequency ARay (LOFAR) and combined these with archival Giant Metrewave Radio Telescope (GMRT) 323 MHz and Very Large Array (VLA) 1.5 GHz data to study the morphological and spectral properties of extended cluster emission. The observational properties are discussed in the framework of particle acceleration models associated with cluster merger turbulence and shocks. Results. In Abell 520, we confirm the presence of extended (760 × 950 kpc2) synchrotron radio emission that has been classified as a radio halo. The comparison between the radio and X-ray brightness suggests that the halo might originate in a cocoon rather than from the central X-ray bright regions of the cluster. The halo spectrum is roughly uniform on the scale of 66 kpc. There is a hint of spectral steepening from the SW edge towards the cluster centre. Assuming diffusive shock acceleration (DSA), the radio data are suggestive of a shock Mach number of ℳSW = 2.6−0.2+0.3 that is consistent with the X-ray derived estimates. This is in agreement with the scenario in which relativistic electrons in the SW radio edge gain their energies at the shock front via acceleration of either thermal or fossil electrons. We do not detect extended radio emission ahead of the SW shock that is predicted if the emission is the result of adiabatic compression. An X-ray surface brightness discontinuity is detected towards the NE region that may be a counter shock of Mach number ℳNEX = 1.52±0.05. This is lower than the value predicted from the radio emission which, assuming DSA, is consistent with ℳNE = 2.1 ± 0.2. Conclusions. Our observations indicate that the radio emission in the SW of Abell 520 is likely effected by the prominent X-ray detected shock in which radio emitting particles are (re-)accelerated through the Fermi-I mechanism. The NE X-ray discontinuity that is approximately collocated with an edge in the radio emission hints at the presence of a counter shock.

scholarly journals Diffuse radio emission in the galaxy cluster SPT-CL J2031−4037: a steep-spectrum intermediate radio halo?

2020 ◽  
Vol 493 (1) ◽  
pp. L28-L32 ◽  
Author(s):  
Ramij Raja ◽  
Majidul Rahaman ◽  
Abhirup Datta ◽  
Jack O Burns ◽  
H T Intema ◽  
...  
Keyword(s):  
Radio Emission ◽  
Spectral Index ◽  
Low Frequency ◽  
Galaxy Cluster ◽  
Transition System ◽  
Cluster Galaxy ◽  
Radio Halo ◽  
Spectrum Radio ◽  
Upper Limits ◽  
The Galaxy

ABSTRACT The advent of sensitive low-frequency radio observations has revealed a number of diffuse radio objects with peculiar properties that are challenging our understanding of the physics of the intracluster medium. Here, we report the discovery of a steep-spectrum radio halo surrounding the central brightest cluster galaxy (BCG) in the galaxy cluster SPT-CL J2031−4037. This cluster is morphologically disturbed yet has a weak cool core, an example of a cool-core/non-cool-core transition system, which harbours a radio halo ∼0.7 Mpc in size. The halo emission detected at 1.7 GHz is less extended compared to that in the 325 MHz observation, and the spectral index of the part of the halo visible at the 325 MHz to 1.7 GHz frequencies was found to be −1.35 ± 0.07. Also, P1.4 GHz was found to be 0.77 × 1024 W Hz−1, which falls in the region where radio mini-haloes, halo upper limits and ultra-steep-spectrum (USS) haloes are found in the P1.4 GHz–LX plane. Additionally, simulations presented in the paper provide support for the scenario of the steep spectrum. The diffuse radio emission found in this cluster may be a steep-spectrum ‘intermediate’ or ‘hybrid’ radio halo that is transitioning into a mini-halo.

scholarly journals A molecular absorption line survey towards the AGN of Hydra-A

2020 ◽  
Vol 496 (1) ◽  
pp. 364-380
Author(s):  
Tom Rose ◽  
A C Edge ◽  
F Combes ◽  
S Hamer ◽  
B R McNamara ◽  
...  
Keyword(s):  
Elliptical Galaxy ◽  
Cluster Galaxy ◽  
Cluster Galaxies ◽  
Continuum Source ◽  
Radio Jets ◽  
Extended Radio ◽  
Brightest Cluster Galaxies ◽  
The Galaxy ◽  
Absorption Features ◽  
Recession Velocity

ABSTRACT We present Atacama Large Millimetre/submillimetre Array observations of the brightest cluster galaxy Hydra-A, a nearby (z = 0.054) giant elliptical galaxy with powerful and extended radio jets. The observations reveal CO(1−0), CO(2–1), 13CO(2–1), CN(2–1), SiO(5–4), HCO+(1–0), HCO+(2–1), HCN(1–0), HCN(2–1), HNC(1–0), and H2CO(3–2) absorption lines against the galaxy’s bright and compact active galactic nucleus. These absorption features are due to at least 12 individual molecular clouds that lie close to the centre of the galaxy and have velocities of approximately −50 to +10 km s−1 relative to its recession velocity, where positive values correspond to inward motion. The absorption profiles are evidence of a clumpy interstellar medium within brightest cluster galaxies composed of clouds with similar column densities, velocity dispersions, and excitation temperatures to those found at radii of several kpc in the Milky Way. We also show potential variation in a ∼10 km s−1 wide section of the absorption profile over a 2 yr time-scale, most likely caused by relativistic motions in the hot spots of the continuum source that change the background illumination of the absorbing clouds.

scholarly journals Extended Extragalactic Radio Emission

2002 ◽  
Vol 199 ◽  
pp. 171-178
Author(s):  
F.N. Owen ◽  
M.J. Ledlow ◽  
J.A. Eilek ◽  
N.E. Kassim ◽  
N. Miller ◽  
...  
Keyword(s):  
Radio Emission ◽  
High Redshift ◽  
Current Understanding ◽  
Linear Size ◽  
Radio Jets ◽  
Extended Radio ◽  
Dense Cluster ◽  
Cluster Cores ◽  
The Impact ◽  
Parent Galaxy

Extended radio emission and its relation to parent galaxy properties is briefly reviewed. Our current understanding of the relation between absolute radio and optical luminosity, radio morphology and linear size is discussed. The impact of radio jets on dense cluster cores is discussed using M87 as an example. Finally, the relation of AGN's to star-bursting galaxies at high redshift is considered.

scholarly journals Particle acceleration in a nearby galaxy cluster pair: the role of cluster dynamics

2019 ◽  
Vol 630 ◽  
pp. A77 ◽  
Author(s):  
A. Botteon ◽  
R. Cassano ◽  
D. Eckert ◽  
G. Brunetti ◽  
D. Dallacasa ◽  
...  
Keyword(s):  
Radio Emission ◽  
Galaxy Clusters ◽  
Surface Brightness ◽  
Power Spectra ◽  
Galaxy Cluster ◽  
Cluster Center ◽  
Nearby Galaxy ◽  
X Ray ◽  
Radio Halo ◽  
Cluster Pair

Context. Diffuse radio emission associated with the intracluster medium (ICM) is observed in a number of merging galaxy clusters. It is currently believed that a fraction of the kinetic energy in mergers is channeled into nonthermal components, such as turbulence, cosmic rays, and magnetic fields, which may lead to the formation of giant synchrotron sources in the ICM. Aims. Studying merging galaxy clusters in different evolutionary phases is fundamental for understanding the origin of radio emission in the ICM. Methods. We observed the nearby galaxy cluster pair RXC J1825.3+3026 (z ∼ 0.065) and CIZA J1824.1+3029 (z ∼ 0.071) at 120 − 168 MHz with the LOw Frequency ARray (LOFAR) and made use of a deep (240 ks) XMM-Newton dataset to study the nonthermal and thermal properties of the system. RXC J1825.3+3026 is in a complex dynamical state, with a primary ongoing merger in the E-W direction and a secondary later stage merger with a group of galaxies in the SW, while CIZA J1824.1+3029 is dynamically relaxed. These two clusters are in a pre-merger phase. Results. We report the discovery of a Mpc-scale radio halo with a low surface brightness extension in RXC J1825.3+3026 that follows the X-ray emission from the cluster center to the remnant of a galaxy group in the SW. This is among the least massive systems and the faintest giant radio halo known to date. In contrast to this, no diffuse radio emission is observed in CIZA J1824.1+3029, nor in the region between the pre-merger cluster pair. The power spectra of the X-ray surface brightness fluctuations of RXC J1825.3+3026 and CIZA J1824.1+3029 are in agreement with the findings for clusters exhibiting a radio halo and clusters where no radio emission has been detected, respectively. Conclusions. We provide quantitative support to the idea that cluster mergers play a crucial role in the generation of nonthermal components in the ICM.

scholarly journals The role of AGN jets and intracluster magnetic fields in the formation and acceleration of cosmic rays

2010 ◽  
Vol 6 (S275) ◽  
Author(s):  
Nectaria A. B. Gizani
Keyword(s):  
Cosmic Rays ◽  
Magnetic Fields ◽  
Radio Emission ◽  
Radio Galaxies ◽  
Powerful Radio ◽  
X Ray ◽  
Cooling Flow ◽  
The Core ◽  
Radio Jets

AbstractUsing radio and X-ray data of two powerful radio galaxies, we attempt to find out the role that radio jets (in terms of composition and power), as well as intracluster magnetic fields, play in the formation, propagation, and acceleration of cosmic rays. For this study we have selected the powerful radio galaxies Hercules A and 3C 310 because of the presence of ring-like features in their kpc-scale radio emission instead of the usual hotspots. These two FR1.5 lie at the center of galaxy cooling flow clusters in a dense environment. We observed the unique jets of Hercules both in kpc-scales (multifrequency VLA data) and pc-scales (EVN observations at 18 cm). We have also observed the core and inner jets of 3C310 at 18 cm using global VLBI. We report on the work in progress.

scholarly journals Probing the Origin of Diffuse Radio Emission in the Cool Core of the Phoenix Galaxy Cluster

2020 ◽  
Vol 889 (2) ◽  
pp. 128
Author(s):  
Ramij Raja ◽  
Majidul Rahaman ◽  
Abhirup Datta ◽  
Jack O. Burns ◽  
Brian Alden ◽  
...  
Keyword(s):  
Radio Emission ◽  
Galaxy Cluster ◽  
The Phoenix

scholarly journals Circumstellar radio emission from pre-main sequence stars

1987 ◽  
Vol 122 ◽  
pp. 63-64
Author(s):  
Alexander Brown
Keyword(s):  
Radio Emission ◽  
Main Sequence ◽  
Radio Continuum ◽  
Circumstellar Envelopes ◽  
Main Sequence Stars ◽  
Radio Jets ◽  
Extended Radio ◽  
Upper Limits ◽  
Infra Red ◽  
Pms Stars

VLA radio continuum observations have been obtained for a number of pre-main sequence (PMS) stars in Corona Australis, Lupus, Scorpius and Taurus. A variety of PMS sources were detected and for other stars upper limits to the ionized mass loss rates were determined. A strong double source, showing two radio jets, was found associated with an embedded infra-red source in the R CrA molecular cloud. Some of the PMS stars show extended radio emission associated with ionized circumstellar envelopes, even though photoionization by EUV photons is not sufficient to produce the ionized regions.

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