1,502 research outputs found
Testing RIAF model for Sgr A* using the size measurements
Recent radio observations by the VLBA at 7 and 3.5 mm produced the
high-resolution images of the compact radio source located at the center of our
Galaxy--Sgr A*, and detected its wavelength-dependent intrinsic sizes at the
two wavelengths. This provides us with a good chance of testing
previously-proposed theoretical models for Sgr A*. In this {\em Letter}, we
calculate the size based on the radiatively inefficient accretion flow (RIAF)
model proposed by Yuan, Quataert & Narayan (2003). We find that the predicted
sizes after taking into account the scattering of the interstellar electrons
are consistent with the observations. We further predict an image of Sgr A* at
1.3 mm which can be tested by future observations.Comment: 10 pages, 1 figure; accepted by ApJ
Orbital Kondo effect in a parallel double quantum dot
We construct a theoretical model to study the orbital Kondo effect in a
parallel double quantum dot (DQD). Recently, pseudospin-resolved transport
spectroscopy of the orbital Kondo effect in a DQD has been experimentally
reported. The experiment revealed that when interdot tunneling is ignored,
there exist two and one Kondo peaks in the conductance-bias curve for the
pseudospin-non-resolved and pseudospin-resolved cases, respectively. Our
theoretical studies reproduce this experimental result. We also investigate the
situation of all lead voltages being non-equal (the complete
pseudospin-resolved case), and find that there are four Kondo peaks at most in
the curve of the conductance versus the pseudospin splitting energy. When the
interdot tunneling is introduced, some new Kondo peaks and dips can emerge.
Besides, the pseudospin transport and the pseudospin flipping current are also
studied in the DQD system. Since the pseudospin transport is much easier to be
controlled and measured than the real spin transport, it can be used to study
the physical phenomenon related to the spin transport.Comment: 18 pages, 7 figures, accepted by J. Phys.: Condens. Matter in
September 201
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