24 research outputs found
The spectra and energies of classical double radio lobes
We compare two temporal properties of classical double radio sources: i)
radiative lifetimes of synchrotron-emitting particles and ii) dynamical source
ages. We discuss how these can be quite discrepant from one another, rendering
use of the traditional spectral ageing method inappropriate: we contend that
spectral ages give meaningful estimates of dynamical ages only when these ages
are << 10^7 years. In juxtaposing the fleeting radiative lifetimes with source
ages which are significantly longer, a refinement of the paradigm for radio
source evolution is required. The changing spectra along lobes are explained,
not predominantly by synchrotron ageing but, by gentle gradients in a magnetic
field mediated by a low-gamma matrix which illuminates an energy-distribution
of particles, controlled largely by classical synchrotron loss in the high
magnetic field of the hotspot. The energy in the particles is an order of
magnitude higher than that inferred from the minimum-energy estimate, implying
that the jet-power is of the same order as the accretion luminosity produced by
the quasar central engine. This refined paradigm points to a resolution of the
findings of Rudnick et al (1994) and Katz-Stone & Rudnick (1994) that both the
Jaffe-Perola and Kardashev-Pacholczyk model spectra are invariably poor
descriptions of the curved spectral shape of lobe emission, and indeed that for
Cygnus A all regions of the lobes are characterised by a `universal spectrum'.
[abridged]Comment: LaTeX, 4 figures. To appear in A
From Clock Synchronization to Dark Matter as a Relativistic Inertial Effect
Lecture at BOSS2011 on relativistic metrology, on clock synchronization,
relativistic dynamics and non-inertial frames in Minkowski spacetime, on
relativistic atomic physics, on ADM canonical tetrad gravity in asymptotically
Minkowskian spacetimes, on the York canonical basis identifying the inertial
(gauge) and tidal degrees of freedom of the gravitational field, on the
Post-Minkowskian linearization in 3-orthogonal gauges, on the Post-Newtonian
limit of matter Hamilton equations, on the possibility to interpret dark matter
as a relativistic inertial effect connected with relativistic metrology (i.e.
clock synchronization) in Einstein GR.Comment: 90 pages. Lecture at BOSS201
<span style="font-size:18.0pt;mso-bidi-font-size:12.0pt; font-family:"Times New Roman";mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-US;mso-fareast-language:EN-US;mso-bidi-language:AR-SA">(<i style="mso-bidi-font-style:normal">Z</i>) 1<span style="font-size:18.5pt; mso-bidi-font-size:12.5pt;font-family:"Times New Roman";mso-fareast-font-family: "Times New Roman";mso-ansi-language:EN-US;mso-fareast-language:EN-US; mso-bidi-language:AR-SA">'-Propylbutyl 3-octadecenoate from <i>Fagara budrunga </i>fruits</span></span>
122-124Chemical constituents of the
Indian medicinal plant Fagara
budrunga <span style="font-size:14.5pt;
mso-bidi-font-size:8.5pt;font-family:" times="" new="" roman";mso-fareast-font-family:="" "times="" roman";mso-ansi-language:en-us;mso-fareast-language:en-us;="" mso-bidi-language:ar-sa"="">commonly known as mullilam, have been isolated. In addition
to the known compounds a new ester has been obtained. It has been assigned the
structure (Z) 1' -propyl butyl 3-octadecenoate <b style="mso-bidi-font-weight:
normal">1 from chemical conversions and spectral analysis.</span
VLA observations of the wide-angle tailed radio source 1313 + 073
The authors present VLA observations at 20 and 6 cm of the wide-angle tailed source 1313+073. It has an asymmetric structure with a sharp bend in the eastern tail and a gradual bend in the western. Both tails become diffuse after the bends. The authors explore several models to explain this structure and conclude that the tails bend because of the motion of the parent cD galaxy through the intracluster medium, which is possible if the cluster containing the source is dynamically young. Examination of the optical fields of 26 similar sources shows that in 20 of them the parent galaxies have a fainter companion (by ≡2 mag), or are D, cD or db. This indicates that cannibalism may be important in the formation and powering of such sources