28,073 research outputs found
Fermi Variability Study of the Candidate Pulsar Binary 2FGL~J0523.3-2530
The Fermi source 2FGL~J0523.32530 has recently been identified as a
candidate millisecond pulsar binary with an orbital period of 16.5 hrs. We have
carried out detailed studies of the source's emission properties by analyzing
data taken with the Fermi Large Area Telescope in the 0.2--300 GeV energy
range. Long-term, yearly variability from the source has been found, with a
factor of 4 flux variations in 1--300 GeV. From spectral analysis, we find an
extra spectral component at 2--3 GeV that causes the source brightening. While
no orbital modulations have been found from the Fermi data over the whole
period of 2008--2014, orbital modulation in the source's 2 GeV emission is
detected during the last 1.5 yrs of the Fermi observation. Our results support
the millisecond pulsar binary nature of 2FGL~J0523.32530. Multi-wavelength
observations of the source are warranted in order to find any correlated flux
variations and thus help determine the origin of the long-term variability,
which currently is not understood.Comment: 8 pages, 5 figures, comments from Referee were incorporated, accepted
for publication in Ap
Geometric phase in dephasing systems
Beyond the quantum Markov approximation, we calculate the geometric phase of
a two-level system driven by a quantized magnetic field subject to phase
dephasing. The phase reduces to the standard geometric phase in the weak
coupling limit and it involves the phase information of the environment in
general. In contrast with the geometric phase in dissipative systems, the
geometric phase acquired by the system can be observed on a long time scale. We
also show that with the system decohering to its pointer states, the geometric
phase factor tends to a sum over the phase factors pertaining to the pointer
states.Comment: 4 page
Consistent picture for the electronic structure around a vortex core in iron-based superconductors
Based on a two-orbital model and taking into account the presence of the
impurity, we studied theoretically the electronic structure in the vortex core
of the iron-Pnictide superconducting materials. The vortex is pinned when the
impurity is close to the vortex core. The bound states shows up for the
unpinned vortex and are wiped out by a impurity. Our results are in good
agreement with recent experiments and present a consistent explanation for the
different electronic structure of vortex core revealed by experiments on
different materials.Comment: 4 pages, 5 figure
Dissipation Effects in Hybrid Systems
The dissipation effect in a hybrid system is studied in this Letter. The
hybrid system is a compound of a classical magnetic particle and a quantum
single spin. Two cases are considered. In the first case, we investigate the
effect of the dissipative quantum subsystem on the motion of its classical
partner. Whereas in the second case we show how the dynamics of the quantum
single spin are affected by the dissipation of the classical particle.
Extension to general dissipative hybrid systems is discussed.Comment: 4+ pages, 4 figure
- âŠ