32,812 research outputs found
Interaction Between Supernova Remnant G22.7-0.2 And The Ambient Molecular Clouds
We have carried out 12CO (J=1-0 and 2-1), 13CO (J=1-0), and C18O (J=1-0)
observations in the direction of the supernova remnant (SNR) G22.7-0.2. A
filamentary molecular gas structure, which is likely part of a larger molecular
complex with VLSR~75-79 km/s, is detected and is found to surround the southern
boundary of the remnant. In particular, the high-velocity wing (77-110 km/s) in
the 12CO (J=1-0 and J=2-1) emission shows convincing evidence of the
interaction between SNR G22.7-0.2 and the 75-79 km/s molecular clouds (MCs).
Spectra with redshifted profiles, a signature of shocked molecular gas, are
seen in the southeastern boundary of the remnant. The association between the
remnant and the 77 km/s MCs places the remnant at the near distance of 4.0-4.8
kpc, which agrees with a location on the Scutum-Crux arm. We suggest that SNR
G22.7-0.2, SNR W41, and HII region G022.760-0.485 are at the same distance and
are associated with GMC G23.0-0.4.Comment: 9 pages, 9 figures, 3 tables, accepted for publication in Ap
Large-field CO(1--0) observations toward the Galactic historical supernova remnants: a large cavity around Tycho's supernova remnant
The investigation of the interaction between the supernova remnants (SNRs)
and interstellar gas is not only necessary to improve our knowledge of SNRs,
but also to understand the nature of the progenitor systems. As a part of the
Milky Way Imaging Scroll Painting CO line survey (MWISP), we study the
interstellar gas surrounding the Galactic historical SNRs, using the PMO
13.7-meter telescope. In this work, we present large-field
(32) and high-sensitivity CO(1-0) molecular line
observations toward Tycho's SNR. The CO observations reveal, from the outside
in, large molecular clouds, stream-like structures, and an inner rim around
Tycho's SNR. We derived the basic properties (column density, mass, and
kinematics) of these objects based on the CO observations. The large molecular
clouds individually show an arc toward the remnant center, outlining a large
cavity with radii of 0.30.6 (or 13 pc 27
pc at a distance of 2.5 kpc) around the remnant. The CO line broadenings and
asymmetries detected in the surrounding clouds, the observed expansion of the
cavity, in concert with enhanced CO(2-1)/(1-0) intensity ratio detected
in previous studies, suggest the interaction of the large cavity with a wind in
the region. After excluding the scenario of a large bubble produced by bright
massive stars, we suggest that the large cavity could be explained by accretion
wind from the progenitor system of Tycho's supernova. Nevertheless, the
possibility of the random distribution of a large cavity around Tycho's SNR
cannot be ruled out thus far. Further observations are needed to confirm the
physical association of the large cavity with Tycho's SNR.Comment: 15 pages, 9 figures, updated according to the A&A proo
Numerical evaluation of a two loop diagram in the cutoff regularization
The sunset diagram of theory is evaluated numerically in
cutoff scheme and a nonzero finite term (in accordance with dimensional
regularization (DR) result) is found in contrast to published calculations.
This finding dramatically reduces the critical couplings for symmetry breaking
in the two loop effective potential discussed in our previous work.Comment: 6 pages, revtex, to appear in Comm. Theor. Phy
Angular Momentum in Non-Relativistic QED and Photon Contribution to Spin of Hydrogen Atom
We study angular momentum in non-relativistic quantum electrodynamics
(NRQED). We construct the effective total angular momentum operator by applying
Noether's theorem to the NRQED lagrangian. We calculate the NRQED matching for
the individual components of the QED angular momentum up to one loop. We
illustrate an application of our results by the first calculation of the
angular momentum of the ground state hydrogen atom carried in radiative
photons, , which might be measurable in future atomic
experiments.Comment: 7 pages, 3 figure
Dynamics modeling and experimental modal analysis of bolt loosening for lightning rod
Lightning rods are effective to prevent lightning damage in power systems. However, under the influence of severe weather conditions, they often face failure problems, mainly manifested as tilt and fracture caused by bolt loosening which can result in significant economic losses. Therefore, it is very meaningful to detect the loosening of the lightning rod. The vibration-based method is an effective method for bolt loosening detection and is suitable for use on large lightning rods. This paper built a finite element model of the lightning rod Flange-Bolt Structure Unit (FBSU) based on the virtual material method, designed an effective acquisition test of the vibration signal under different loosening conditions of the lightning rod FBSU. The experimental results showed that it was effective to establish the dynamic model of the lightning rod FBSU by using the virtual material method. According to the measured vibration signal, the frequency response function was obtained by TIME MDOF method, and the preliminary judgment of bolt loosening can be realized. This study lays the foundation for the precise positioning and the extent of loosening detection of lightning rod bolt loosening, and also provides a guideline for the vibration test design of large bolted structures similar to lightning rods
Constraints on anomalous quartic gauge couplings via production at the LHC
The vector boson scattering at the Large Hadron Collider (LHC) is sensitive
to anomalous quartic gauge couplings (aQGCs). In this paper, we investigate the
aQGC contribution to production at the LHC with
TeV in the context of an effective field theory (EFT). The unitarity bound is
applied as a cut on the energy scale of this production process, which is found
to have significant suppressive effects on the signals. To enhance the
statistical significance, we analyse the kinematic and polarization features of
the aQGC signals in detail. We find that the polarization effects induced by
the aQGCs are unique and can discriminate the signals from the SM backgrounds
well. With the proposed event selection strategy, we obtain the constraints on
the coefficients of dimension-8 operators with current luminosity. The results
indicate that the process is powerful for searching for
the and operators.Comment: 29 pages, 11 figures, 7 tables, to be published in Chinese Physics
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