3,800 research outputs found
A VLA Study of 15 3CR Radio Galaxies
We present VLA radio maps in total intensity and polarization at 1.4, 4.9 and
8.4 GHz of fifteen 3CR radio galaxies for which good maps showing the
large-scale radio structure have not previously been available. Previously
unknown cores are detected in several sources and a bright one-sided jet in 3C
287.1 is mapped for the first time; several other jet-like features are also
imaged. Total and core fluxes are tabulated and radio core positions are listed
and compared to optical positions. The galaxy at the optical position listed
for 3C 169.1 is found to lie farther from the radio core position than another
dimmer, bluer galaxy. We discuss individual sources in some detail.Comment: 35 pages, 22 figures but 35 separate Postscript figure files, AASTeX,
Accepted for publication in the Astrophysical Journal Supplemen
Shock heating in the nearby radio galaxy NGC 3801
Original article can be found at: http://www.journals.uchicago.edu/ApJ/--Copyright American Astronomical SocietyPeer reviewe
The Disturbed 17 keV Cluster Associated with the Radio Galaxy 3C 438
We present results from a {\em Chandra} observation of the cluster gas
associated with the FR II radio galaxy 3C 438. This radio galaxy is embedded
within a massive cluster with gas temperature 17 keV and bolometric
luminosity of 6 ergs s. It is unclear if this high
temperature represents the gravitational mass of the cluster, or if this is an
already high ( 11 keV) temperature cluster that has been heated
transiently. We detect a surface brightness discontinuity in the gas that
extends 600 kpc through the cluster. The radio galaxy 3C 438 is too small
(110 kpc across) and too weak to have created this large disturbance in
the gas. The discontinuity must be the result of either an extremely powerful
nuclear outburst or the major merger of two massive clusters. If the observed
features are the result of a nuclear outburst, it must be from an earlier epoch
of unusually energetic nuclear activity. However, the energy required
( ergs) to move the gas on the observed spatial scales strongly
supports the merger hypothesis. In either scenario, this is one of the most
extreme events in the local Universe.Comment: 13 pages, 4 figures, 1 table - accepted for publication in the
Astrophysical Journal Letter
A Chandra study of particle acceleration in the multiple hotspots of nearby radio galaxies
We present Chandra observations of a small sample of nearby classical double
radio galaxies which have more than one radio hotspot in at least one of their
lobes. The X-ray emission from the hotspots of these comparatively low-power
objects is expected to be synchrotron in origin, and therefore to provide
information about the locations of high-energy particle acceleration. In some
models of the relationship between the jet and hotspot the hotspots that are
not the current jet termination point should be detached from the energy supply
from the active nucleus and therefore not capable of accelerating particles to
high energies. We find that in fact some secondary hotspots are X-ray sources,
and thus probably locations for high-energy particle acceleration after the
initial jet termination shock. In detail, though, we show that the spatial
structures seen in X-ray are not consistent with naive expectations from a
simple shock model: the current locations of the acceleration of the
highest-energy observable particles in powerful radio galaxies need not be
coincident with the peaks of radio or even optical emission.Comment: Accepted for ApJ. 33 pages, 8 figures inc. 2 in colo
The linear bias of radio galaxies at z~0.3 via cosmic microwave background lensing
© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical SocietyWe present a new measurement of the linear bias of radio loud active galactic nuclei (RLAGN) at and selected from the Best & Heckman (2012) sample, made by cross-correlating the RLAGN surface density with a map of the convergence of the weak lensing field of the cosmic microwave background from Planck. We detect the cross-power signal at a significance of and use the amplitude of the cross-power spectrum to estimate the linear bias of RLAGN, , corresponding to a typical dark matter halo mass of . When RLAGN associated with optically-selected clusters are removed we measure a lower bias corresponding to . These observations support the view that powerful RLAGN typically inhabit rich group and cluster environments.Peer reviewe
The dynamics and environmental impact of 3C452
We present a detailed analysis of a new XMM-Newton observation of the FRII
radio galaxy 3C452 and its environment. We detect X-ray emission from the hot
intragroup medium and measure its temperature as well as obtaining the surface
brightness and pressure profiles. We provide evidence that 3C452 is currently
heating its environment, measuring a temperature of keV for the
immediate environment of the radio source compared to
keV for the outer environment. We also present evidence that the outer regions
of the lobes are overpressured (internal pressure of Pa and
external pressure of Pa at the edge of the lobes)
and therefore are driving a shock at the lobe edges (with a temperature which
we constrain to be keV), while the inner regions of the
lobes are underpressured and contracting. Taking into account the very large
amount of energy stored in the lobes, we show that this relatively low-powered
FRII radio galaxy will have an extremely significant impact on its group
environment.Comment: 10 pages, 6 figures (4 in colour). Accepted by MNRA
Numerical modelling of the lobes of radio galaxies in cluster environments -- IV. Remnant radio galaxies
© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.We examine the remnant phase of radio galaxies using three-dimensional hydrodynamical simulations of relativistic jets propagating through cluster environments. By switching the jets off once the lobes have reached a certain length we can study how the energy distribution between the lobes and shocked intra-cluster medium compares to that of an active source, as well as calculate synchrotron emission properties of the remnant sources. We see that as a result of disturbed cluster gas beginning to settle back into the initial cluster potential, streams of dense gas are pushed along the jet axis behind the remnant lobes, causing them to rise out of the cluster faster than they would due to buoyancy. This leads to increased adiabatic losses and a rapid dimming. The rapid decay of total flux density and surface brightness may explain the small number of remnant sources found in samples with a high flux density limit and may cause analytic models to overestimate the remnant fraction expected in sensitive surveys such as those now being carried out with LOFAR.Peer reviewedFinal Accepted Versio
The Infrared Jet In 3C66B
We present images of infrared emission from the radio jet in 3C66B. Data at
three wavelengths (4.5, 6.75 and 14.5 microns) were obtained using the Infrared
Space Observatory. The 6.75 micron image clearly shows an extension aligned
with the radio structure. The jet was also detected in the 14.5 micron image,
but not at 4.5 micron. The radio-infrared-optical spectrum of the jet can be
interpreted as synchrotron emission from a population of electrons with a
high-energy break of 4e11 eV. We place upper limits on the IR flux from the
radio counter-jet. A symmetrical, relativistically beamed twin-jet structure is
consistent with our results if the jets consist of multiple components.Comment: 7 pages, 4 figure
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