12,119 research outputs found
Shape evolution and shape coexistence in Pt isotopes: comparing interacting boson model configuration mixing and Gogny mean-field energy surfaces
The evolution of the total energy surface and the nuclear shape in the
isotopic chain Pt are studied in the framework of the interacting
boson model, including configuration mixing. The results are compared with a
self-consistent Hartree-Fock-Bogoliubov calculation using the Gogny-D1S
interaction and a good agreement between both approaches shows up. The
evolution of the deformation parameters points towards the presence of two
different coexisting configurations in the region 176 A 186.Comment: Submitted to PR
On the convex characterisation of the set of unital quantum channels
In this paper, we consider the convex set of dimensional unital quantum
channels. In particular, we parametrise a family of maps and through this
parametrisation we provide a partial characterisation of the set of unital
quantum maps with respect to this family of channels. For the case of qutrit
channels, we consider the extreme points of the set and their classification
with respect to the Kraus rank. In this setting, we see that the parametrised
family of maps corresponds to maps with Kraus rank three. Furthermore, we
introduce a novel family of qutrit unital quantum channels with Kraus rank four
to consider the extreme points of the set over all possible Kraus ranks. We
construct explicit examples of these two families of channels and we consider
the question of whether these channels correspond to extreme points of the set
of quantum unital channels. Finally, we demonstrate how well-known channels
relate to the examples presented.Comment: 18 page
An upgraded drift-diffusion model for evaluating the carrier lifetimes in radiation-damaged semiconductor detectors
Mid-infrared imaging- and spectro-polarimetric subarcsecond observations of NGC 1068
We present sub-arcsecond 7.513 m imaging- and spectro-polarimetric
observations of NGC 1068 using CanariCam on the 10.4-m Gran Telescopio
CANARIAS. At all wavelengths, we find:
(1) A 90 60 pc extended polarized feature in the northern ionization
cone, with a uniform 44 polarization angle. Its polarization
arises from dust and gas emission in the ionization cone, heated by the active
nucleus and jet, and further extinguished by aligned dust grains in the host
galaxy. The polarization spectrum of the jet-molecular cloud interaction at
24 pc from the core is highly polarized, and does not show a silicate
feature, suggesting that the dust grains are different from those in the
interstellar medium.
(2) A southern polarized feature at 9.6 pc from the core. Its
polarization arises from a dust emission component extinguished by a large
concentration of dust in the galaxy disc. We cannot distinguish between dust
emission from magnetically aligned dust grains directly heated by the jet close
to the core, and aligned dust grains in the dusty obscuring material
surrounding the central engine. Silicate-like grains reproduce the polarized
dust emission in this feature, suggesting different dust compositions in both
ionization cones.
(3) An upper limit of polarization degree of 0.3 per cent in the core. Based
on our polarization model, the expected polarization of the obscuring dusty
material is 0.1 per cent in the 813 m wavelength range. This
low polarization may be arising from the passage of radiation through aligned
dust grains in the shielded edges of the clumps.Comment: 17 pages, 10 figures, accepted for publication at MNRA
Starburst radio galaxies: general properties, evolutionary histories and triggering
In this paper we discuss the results of a programme of spectral synthesis
modelling of a sample of starburst radio galaxies in the context of scenarios
for the triggering of the activity and the evolution of the host galaxies. The
starburst radio galaxies -- comprising ~15 - 25% of all powerful extragalactic
radio sources -- frequently show disturbed morphologies at optical wavelengths,
and unusual radio structures, although their stellar masses are typical of
radio galaxies as a class. In terms of the characteristic ages of their young
stellar populations (YSP), the objects can be divided into two groups: those
with YSP ages t_ysp < 0.1 Gyr, in which the radio source has been triggered
quasi-simultaneously with the main starburst episode, and those with older YSP
in which the radio source has been triggered or re-triggered a significant
period after the starburst episode. Combining the information on the YSP with
that on the optical morphologies of the host galaxies, we deduce that the
majority of the starburst radio galaxies have been triggered in galaxy mergers
in which at least one of the galaxies is gas rich. However, the triggering (or
re-triggering) of the radio jets can occur immediately before, around, or a
significant period after the final coalescence of the merging nuclei,
reflecting the complex gas infall histories of the merger events. Overall, our
results provide further evidence that powerful radio jet activity can be
triggered via a variety of mechanisms, including different evolutionary stages
of major galaxy mergers; clearly radio-loud AGN activity is not solely
associated with a particular stage of a unique type of gas accretion event.Comment: 16 pages, 3 Figures, accepted for publication in MNRA
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