3,262 research outputs found
Applicability of Relativistic Point-Coupling Models to Neutron Star Physics
Comparing with a wide range of covariant energy density functional models
based on the finite-range meson-exchange representation, the relativistic
mean-field models with the zero-range contact interaction, namely the
relativistic point-coupling models, are still infrequent to be utilized in
establishing nuclear equation of state (EoS) and investigating neutron star
properties, although comprehensive applications and achievements of them in
describing many nuclear properties both in ground and exited states are mature.
In this work, the EoS of neutron star matter is established constructively in
the framework of the relativistic point-coupling models to study neutron star
physics. Taking two selected functionals DD-PC1 and PC-PK1 as examples, nuclear
symmetry energies and several neutron star properties including proton
fractions, mass-radius relations, the core-crust transition density, the
fraction of crustal moment of inertia and dimensionless tidal deformabilities
are discussed. A suppression of pressure of neutron star matter found in the
functional PC-PK1 at high densities results in the difficulty of its prediction
when approaching to the maximum mass of neutron stars. In addition, the
divergences between two selected functionals in describing neutron star
quantities mentioned above are still large, ascribing to the less constrained
behavior of these functionals at high densities. Then it is expected that the
constraints on the dense matter EoS from precise and massive modern
astronomical observations, such as the tidal-deformabilities taken from
gravitational-wave events, would be essential to improve the parameterizing of
the relativistic point-coupling models.Comment: To appear in the AIP Proceedings of the Xiamen-CUSTIPEN Workshop on
the EOS of Dense Neutron-Rich Matter in the Era of Gravitational Wave
Astronomy, Jan. 3-7, Xiamen, Chin
Tentative evidence of spatially extended GeV emission from SS433/W50
We analyze 10 years of Fermi-LAT data towards the SS433/W50 region. With the
latest source catalog and diffuse background models, the gamma-ray excess from
SS433/W50 is detected with a significance of 6{\sigma} in the photon energy
range of 500 MeV - 10 GeV. Our analysis indicates that an extended flat disk
morphology is preferred over a point-source description, suggesting that the
GeV emission region is much larger than that of the TeV emission detected by
HAWC. The size of the GeV emission is instead consistent with the extent of the
radio nebula W50, a supernova remnant being distorted by the jets, so we
suggest that the GeV emission may originate from this supernova remnant. The
spectral result of the GeV emission is also consistent with an supernova
remnant origin. We also derive the GeV flux upper limits on the TeV emission
region, which put moderate constrains on the leptonic models to explain the
multiwavelength data.Comment: 7 pages, 4 figures, accepted for publication in A&
Assessment of Resident Physicians in Professionalism, Interpersonal and Communication Skills: a Multisource Feedback
Objective: To assess the internal validity and reliability of a multisource feedback (MSF) program by China Medical Board for resident physicians in China
Categorizing resonances X(1835), X(2120) and X(2370) in the pseudoscalar meson family
Inspired by the newly observed three resonances X(1835), X(2120) and X(2370),
in this work we systematically study the two-body strong decays and double pion
decays of , and
by categorizing , , X(2120) and
X(2370) as the radial excitations of . Our
numerical results indicate the followings: (1) The obtained theoretical strong
decay widths of three pseudoscalar states , and
are consistent with the experimental measurements; (2) X(1835)
could be the second radial excitation of ; (3) X(2120) and
X(2370) can be explained as the third and fourth radial excitations of
, respectively.Comment: 16 pages, 15 figures, 3 tables. Accepted for publication in Phys.
Rev.
Multi-wavelength study of the supernova remnant Kes 79 (G33.6+0.1): On its supernova properties and expansion into a molecular environment
Kes 79 (G33.6+0.1) is an aspherical thermal composite supernova remnant (SNR)
observed across the electromagnetic spectrum and showing an unusual
highly-structured morphology, in addition to harboring a central compact object
(CCO). Using the CO J=1-0, J=2-1, and J=3-2 data, we provide the first direct
evidence and new morphological evidence to support the physical interaction
between the SNR and the molecular cloud at km s. We
revisit the 380 ks XMM-Newton observations and perform a dedicated spatially
resolved X-ray spectroscopic study with careful background subtraction. The
overall X-ray-emitting gas is characterized by an under-ionized ( cm^) cool ( keV) plasma with solar
abundances, plus an under-ionized ( cm) hot
( keV) plasma with elevated Ne, Mg, Si, S and Ar abundances.
Kes 79 appears to have a double-hemisphere morphology viewed along the
symmetric axis. Projection effect can explain the multiple shell structures and
the thermal composite morphology. The X-ray filaments, spatially correlated
with the 24 um IR filaments, are suggested to be due to the SNR shock
interaction with dense gas, while the halo forms from SNR breaking out into a
tenuous medium. The high-velocity, hot (--1.6 keV) ejecta patch
with high metal abundances, together with the non-uniform metal distribution
across the SNR, indicating an asymmetric SN explosion of Kes 79. We refine the
Sedov age to 4.4--6.7 kyr and the mean shock velocity to 730 km s. Our
multi-wavelength study suggests a progenitor mass of --20 solar masses
for the core-collapse explosion that formed Kes 79 and its CCO, PSR J1852+0040.Comment: 17 pages, 12 figures, 3 tables, published in Ap
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