11,934 research outputs found
Phase transition of color-superconductivity and cooling behavior of quark stars
We discuss the color-superconductivity and its effect on the cooling behavior
of strange quark stars. The neutrino emissivity and specific heat of quark
matter are calculated within the BCS theory. In the superconducting phase, the
emissivity decreases and causes suppression of the cooling rate. It is shown
that the phase transition leads to a sudden discontinuous suppression of the
cooling rate in cooperation with the specific heat.Comment: 7 pages, 3 figure
The \gamma-ray production in neutral-current neutrino oxygen interaction in the energy range above 100 MeV
We calculate the cross section of the gamma-ray production from
neutral-current neutrino-oxygen quasi-elastic interaction, , or , in
which the residual nuclei (15N* or 15O*) lead to the gamma-ray emission with
gamma-ray energy >6 MeV at the branching ratio of 41%. Above 200 MeV, this
cross section dominates over that of gamma-ray production from the inelastic
reaction, . In the present calculation, spectral
function and the spectroscopic factors of
states are essential. The gamma-ray production is dominated by the deexcitation
of state of the residual nucleus
A Chandra View Of Nonthermal Emission In The Northwestern Region Of Supernova Remnant RCW 86: Particle Acceleration And Magnetic Fields
The shocks of supernova remnants (SNRs) are believed to accelerate particles
to cosmic ray (CR) energies. The amplification of the magnetic field due to CRs
propagating in the shock region is expected to have an impact on both the
emission from the accelerated particle population, as well as the acceleration
process itself. Using a 95 ks observation with the Advanced CCD Imaging
Spectrometer (ACIS) onboard the Chandra X-ray Observatory, we map and
characterize the synchrotron emitting material in the northwestern region of
RCW 86. We model spectra from several different regions, filamentary and
diffuse alike, where emission appears dominated by synchrotron radiation. The
fine spatial resolution of Chandra allows us to obtain accurate emission
profiles across 3 different non-thermal rims in this region. The narrow width
(l = 10''-30'') of these filaments constrains the minimum magnetic field
strength at the post-shock region to be approximately 80 {\mu}G.Comment: 7 pages, 3 figures, submitted for publication at the Astrophysical
Journa
Nonclassical Imaging for a quantum search of trapped ions
We discuss a simple search problem which can be pursued with different
methods, either on a classical or on a quantum basis. The system is represented
by a chain of trapped ions. The ion to be searched is a member of that chain,
consists, however, of an isotopic species different to the others. It is shown
that the classical imaging may lead as fast to the final result as the quantum
imaging. However, for the discussed case the quantum method gives more
flexibility and higher precision when the number of ions considered in the
chain is increasing. In addition, interferences are observable even when the
distances between the ions is smaller than half a wavelength of the incident
light.Comment: 5 pages, 5 figure
Elemental Abundances in the Possible Type Ia Supernova Remnant G344.7-0.1
Recent studies on the Galactic supernova remnant (SNR) G344.7-0.1 have
commonly claimed its origin to be a core-collapse supernova (SN) explosion,
based on its highly asymmetric morphology and/or proximity to a star forming
region. In this paper, however, we present an X-ray spectroscopic study of this
SNR using Suzaku, which is supportive of a Type Ia origin. Strong K-shell
emission from lowly ionized Fe has clearly been detected, and its origin is
determined, for the first time, to be the Fe-rich SN ejecta. The abundance
pattern is highly consistent with that expected for a somewhat-evolved Type Ia
SNR. It is suggested, therefore, that the X-ray point-like source CXOU
J170357.8-414302 located at the SNR's geometrical center is not associated with
the SNR but is likely to be a foreground object. Our result further indicates
that G344.7-0.1 is the first possible Type Ia SNR categorized as a member of
the so-called "mixed-morphology" class. In addition, we have detected emission
from He-like Al at ~1.6 keV, the first clear detection of this element in the
spectrum of an extended X-ray source. The possible enhancement of the Al/Mg
abundance ratio from the solar value suggests that the ambient interstellar
medium has a relatively high metallicity (not less than 10% of the solar
value), if this SNR has indeed a Type Ia origin. We also report marginal
detection of Cr and Mn, although the measured fluxes have large statistical and
systematic uncertainties.Comment: ApJ in pres
Correlator of Fundamental and Anti-symmetric Wilson Loops in AdS/CFT Correspondence
We study the two circular Wilson loop correlator in which one is of
anti-symmetric representation, while the other is of fundamental representation
in 4-dimensional super Yang-Mills theory. This correlator has a
good AdS dual, which is a system of a D5-brane and a fundamental string. We
calculated the on-shell action of the string, and clarified the Gross-Ooguri
transition in this correlator. Some limiting cases are also examined.Comment: 22 pages, 5 figures, v2: typos corrected, v3: final version in JHE
Semi-classical open string corrections and symmetric Wilson loops
In the AdS/CFT correspondence, an AdS_2 x S^2 D3-brane with electric flux in
AdS_5 x S^5 spacetime corresponds to a circular Wilson loop in the symmetric
representation or a multiply wound one in N=4 super Yang-Mills theory. In order
to distinguish the symmetric loop and the multiply wound loop, one should see
an exponentially small correction in large 't Hooft coupling. We study
semi-classically the disk open string attached to the D3-brane. We obtain the
exponent of the term and it agrees with the result of the matrix model
calculation of the symmetric Wilson loop.Comment: 14 pages, 4 figures. v2: explanation improved. v3: argument in
section 2 is improved, result not change
A note on Kerr/CFT and free fields
The near-horizon geometry of the extremal four-dimensional Kerr black hole
and certain generalizations thereof has an SL(2,R) x U(1) isometry group.
Excitations around this geometry can be controlled by imposing appropriate
boundary conditions. For certain boundary conditions, the U(1) isometry is
enhanced to a Virasoro algebra. Here, we propose a free-field construction of
this Virasoro algebra.Comment: 10 pages, v2: comments and references adde
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