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1. chinaXiv:201611.00858 [pdf]

SkyMouse: A smart interface for astronomical on-line resources and services

Chen-Zhou CUI; Hua-Ping SUN; Yong-Heng ZHAO; Yu LUO; Da-Zhi QI
Subjects: Astronomy >> Astrophysical processes

With the development of network and the World Wide Web (WWW), the Internet has been growing and changing dramatically. More and more on-line database systems and different kinds of services are available for astronomy research. How to help users find their way through the jungle of information services becomes an important challenge. Although astronomers have been aware of the importance of interoperability and introduced the concept of Virtual Observatory as a uniform environment for future astronomical on-line resources and services, transparent access to heterogeneous on-line information is still difficult.

submitted time 2016-11-15 Hits5961Downloads1079 Comment 0

2. chinaXiv:201609.00999 [pdf]

Super Strong Magnetic Fields of Neutron Stars in Be X-Ray Binaries Estimated with New Torque and Magnetosphere Models

Chang-Sheng Shi; Shuang-Nan Zhang; Xiang-Dong Li
Subjects: Physics >> Nuclear Physics

We re-estimate the surface magnetic fields of neutron stars (NSs) in Be X-ray binaries (BeXBs) with different models of torque, improved beyond Klus et al. (2014). In particular, a new torque model (Dai \& Li 2006) is applied to three models of magnetosphere radius. Unlike the previous models, the new torque model does not lead to divergent results for any fastness parameter. The inferred surface magnetic fields of these NSs for the two compressed magnetosphere models are much higher than that for the uncompressed magnetosphere model. The new torque model using the compressed-magnetosphere radius (Shi, Zhang \& Li 2014) leads to unique solutions near spin equilibrium in all cases, unlike other models that usually give two branches of solutions. Although our conclusions are still affected by the simplistic assumptions about the magnetosphere radius calculations, we show several groups of possible surface magnetic field values with our new models when the interaction between the magnetosphere and the infalling accretion plasma is considered. The estimated surface magnetic fields for NSs BeXBs in the Large Magellanic Cloud, the Small Magellanic Cloud and the Milk Way are between the quantum critical field and the maximum "virial" value by the spin equilibrium condition.

submitted time 2016-09-14 Hits1524Downloads899 Comment 0

3. chinaXiv:201609.00960 [pdf]

Correlation Analysis between Tibet AS-$\gamma$ TeV Cosmic Ray and WMAP Nine-year Data

Qian-Qing Yin; Shuang-Nan Zhang
Subjects: Physics >> Nuclear Physics

The Wilkinson Microwave Anisotropy Probe (WMAP) team subtracted template-based foreground models to produce foreground-reduced maps, and masked point sources and uncertain sky regions directly; however, whether foreground residuals exist in the WMAP foreground-reduced maps is still an open question. Here, we use Pearson correlation coefficient (PCC) analysis with AS-γ?TeV cosmic ray (CR) data to probe possible foreground residuals in the WMAP nine-year data. The correlation results between the CR and foreground-contained maps (WMAP foreground-unreduced maps, WMAP template-based and MEM foreground models) suggest that: (1) CRs can trace foregrounds in the WMAP data; (2) at least some TeV CRs originate from the Milky Way; (3) foregrounds may be related to the existence of CR anisotropy (loss-cone and tail-in structures); (4) there exist differences among different types of foregrounds in the declination range of?<15?. Then, we generate 10,000 mock CMB sky maps to describe the cosmic variance, which is used to measure the effect of the fluctuations of all possible CMB maps to the correlations between CR and CMB maps. Finally, we do correlation analysis between the CR and WMAP foreground-reduced maps, and find that: (1) there are significant anticorrelations; and (2) the WMAP foreground-reduced maps are credible. However, the significant anticorrelations may be accidental, and the higher signal-to-noise ratio (SNR) Planck SMICA map cannot reject the hypothesis of accidental correlations. We therefore can only conclude that the foreground residuals exist with???95\% probability.

submitted time 2016-09-13 Hits1279Downloads728 Comment 0

4. chinaXiv:201609.00952 [pdf]

Modeling the evolution and distribution of the frequency's second derivative and the braking index of pulsar spin

Yi Xie; Shuang-Nan Zhang; Jin-Yuan Liao
Subjects: Physics >> Nuclear Physics

We model the evolution of the spin frequency's second derivative?ν¨?and the braking index?n?of radio pulsars with simulations within the phenomenological model of their surface magnetic field evolution, which contains a long-term power-law decay modulated by short-term oscillations. For the pulsar PSR B0329+54, a model with three oscillation components can reproduce its?ν¨?variation. We show that the "averaged"?n?is different from the instantaneous?n, and its oscillation magnitude decreases abruptly as the time span increases, due to the "averaging" effect. The simulated timing residuals agree with the main features of the reported data. Our model predicts that the averaged?ν¨?of PSR B0329+54 will start to decrease rapidly with newer data beyond those used in Hobbs et al.. We further perform Monte Carlo simulations for the distribution of the reported data in?|ν¨|?and?|n|?versus characteristic age?τc?diagrams. It is found that the magnetic field oscillation model with decay index?α=0?can reproduce the distributions quite well. Compared with magnetic field decay due to the ambipolar diffusion (α=0.5) and the Hall cascade (α=1.0), the model with no long term decay (α=0) is clearly preferred for old pulsars by the p-values of the two-dimensional Kolmogorov-Smirnov test.

submitted time 2016-09-13 Hits1455Downloads835 Comment 0

5. chinaXiv:201609.00871 [pdf]

Development of Yangbajing air shower core detector array for a new EAS hybrid experiment

LIU Jin-Sheng; HUANG Jing; CHEN Ding; ZHZNG Ying; ZHAI Liu-Ming; CHEN Xu; HU Xiao-Bin; LIN Yu-Hui; ZHANG Xue-Yao; FENG Cun-Feng; JIA Huan-Yu; ZHOU Xun-Xiu; ANZENGLUOBU; CHEN Tian-Lu; LI Hai-Jin; LIU Mao-Yuan; YUAN Ai-Fang
Subjects: Physics >> Nuclear Physics

Aiming at the observation of cosmic-ray chemical composition at the "knee" energy region, we have been developinga new type air-shower core detector (YAC, Yangbajing Air shower Core detector array) to be set up at Yangbajing (90.522??E, 30.102??N, 4300 m above sea level, atmospheric depth: 606 g/m2) in Tibet, China. YAC works together with the Tibet air-shower array (Tibet-III) and an underground water cherenkov muon detector array (MD) as a hybrid experiment. Each YAC detector unit consists of lead plates of 3.5 cm thick and a scintillation counter which detects the burst size induced by high energy particles in the air-shower cores. The burst size can be measured from 1 MIP (Minimum Ionization Particle) to?106?MIPs. The first phase of this experiment, named "YAC-I", consists of 16 YAC detectors each having the size 40 cm?×?50 cm and distributing in a grid with an effective area of 10 m2. YAC-I is used to check hadronic interaction models. The second phase of the experiment, called "YAC-II", consists of 124 YAC detectors with coverage about 500 m2. The inner 100 detectors of 80 cm?×?50 cm each are deployed in a 10?×?10 matrix from with a 1.9 m separation and the outer 24 detectors of 100 cm?×?50 cm each are distributed around them to reject non-core events whose shower cores are far from the YAC-II array. YAC-II is used to study the primary cosmic-ray composition, in particular, to obtain the energy spectra of proton, helium and iron nuclei between 5×1013?eV and?1016?eV covering the "knee" and also being connected with direct observations at energies around 100 TeV. We present the design and performance of YAC-II in this paper.

submitted time 2016-09-13 Hits1363Downloads774 Comment 0

6. chinaXiv:201608.00216 [pdf]

Performance of new 8-inch photomultiplier tube used for the Tibet muon-detector array

Ying Zhang; Jing Huang; Ding Chen; Liu-Ming Zhai; Xu Chen; Xiao-Bin Hu; Yu-Hui Lin; Hong-Bo Jin; Xue-Yao Zhang; Cun-Feng Feng: Huan-Yu Jia; Xun-Xiu Zhou; DANZENGLUOBU; Tian-Lu Chen; LABACIREN; Mao-Yuan Liu; Qi Gao; ZHAXICIREN
Subjects: Physics >> Nuclear Physics

A new hybrid experiment has been constructed to measure the chemical composition of cosmic rays around the "knee" in the wide energy range by the Tibet ASγ?collaboration at Tibet, China, since 2014. They consist of a high-energy air-shower-core array (YAC-II), a high-density air-shower array (Tibet-III) and a large underground water-Cherenkov muon-detector array (MD). In order to obtain the primary proton, helium and iron spectra and their "knee" positions in the energy range lower than?1016?eV, each of PMTs equipped to the MD cell is required to measure the number of photons capable of covering a wide dynamic range of 100 -?106?photoelectrons (PEs) according to Monte Carlo simulations. In this paper, we firstly compare the characteristic features between R5912-PMT made by Japan Hamamatsu and CR365-PMT made by Beijing Hamamatsu. This is the first comparison between R5912-PMT and CR365-PMT. If there exists no serious difference, we will then add two 8-inch-in-diameter PMTs to meet our requirements in each MD cell, which are responsible for the range of 100 - 10000 PEs and 2000 - 1000000 PEs, respectively. That is, MD cell is expected to be able to measure the number of muons over 6 orders of magnitude.

submitted time 2016-08-31 Hits1541Downloads944 Comment 0

7. chinaXiv:201608.00214 [pdf]

Sensitivity of YAC to measure the light-component spectrum of primary cosmic rays at the 'knee' energies

L M Zhai; J Huang; D Chen M Shibata; Y Katayose; Ying Zhang; J S Liu; Xu Chen; X B Hu; Y H Lin
Subjects: Physics >> Nuclear Physics

A new air-shower core-detector array (YAC : Yangbajing Air-shower Core-detector array) has been developed to measure the primary cosmic-ray composition at the "knee" energies in Tibet, China, focusing mainly on the light components. The prototype experiment (YAC-I) consisting of 16 detectors has been constructed and operated at Yangbajing (4300 m a.s.l.) in Tibet since May 2009. YAC-I is installed in the Tibet-III AS array and operates together. In this paper, we performed a Monte Carlo simulation to check the sensitivity of YAC-I+Tibet-III array to the cosmic-ray light component of cosmic rays around the knee energies, taking account of the observation conditions of actual YAC-I+Tibet-III array. The selection of light component from others was made by use of an artificial neural network (ANN). The simulation shows that the light-component spectrum estimated by our methods can well reproduce the input ones within 10\% error, and there will be about 30\% systematic errors mostly induced by the primary and interaction models used. It is found that the full-scale YAC and the Tibet-III array is powerful to study the cosmic-ray composition, in particular, to obtain the energy spectra of protons and helium nuclei around the knee energies.

submitted time 2016-08-31 Hits1425Downloads825 Comment 0

8. chinaXiv:201605.00850 [pdf]

South Galactic Cap u-band Sky Survey (SCUSS): Data Release

Hu Zou
Subjects: Astronomy >> Galaxy and Cosmology

The South Galactic Cap u-band Sky Survey (SCUSS) is a deep u-band imaging survey in the south Galactic capusing the 2.3 m Bok telescope. The survey observations were completed at the end of 2013, covering an area ofabout 5000 square degrees. We release the data in the region with an area of about 4000 deg2 that is mostly coveredby the Sloan digital sky survey. The data products contain calibrated single-epoch images, stacked images,photometric catalogs, and a catalog of star proper motions derived by Peng et al. The median seeing and magnitudelimit (5σ) are about 2 0 and 23.2 mag, respectively. There are about 8 million objects having measurements ofabsolute proper motions. All the data and related documentations can be accessed through the SCUSS data releasewebsite words: catalogs – surveys – techniques: image processing – techni

submitted time 2016-05-05 Hits2377Downloads1279 Comment 0

9. chinaXiv:201605.00848 [pdf]

Enhanced management of personal astronomical data with FITSManager

Chenzhou Cui; Dongwei Fan
Subjects: Astronomy >> Astronomical Instruments and Techniques

Although the roles of data centers and computing centers are becoming more and more important, and on-line research is becoming the mainstream for astronomy, individual research based on locally hosted data is still very common. With the increase of personal storage capacity, it is easy to find hundreds to thousands of FITS files in the personal computer of an astrophysicist. Because Flexible Image Transport System (FITS) is a professional data format initiated by astronomers and used mainly in the small community, data management toolkits for FITS files are very few. Astronomers need a powerful tool to help them manage their local astronomical data. Although Virtual Observatory (VO) is a network oriented astronomical research environment, its applications and related technologies provide useful solutions to enhance the management and utilization of astronomical data hosted in an astronomer’s personal computer. FITSManager is such a tool to provide astronomers an efficient management and utilization of their local data, bringing VO to astronomers in a seamless and transparent way. FITSManager provides fruitful functions for FITS file management, like thumbnail, preview, type dependent icons, header keyword indexing and search, collaborated working with other tools and on-line services, and so on. The development of the FITSManager is an effort to fill the gap between management and analysis of astronomical data.

submitted time 2016-05-05 Hits1645Downloads941 Comment 0

10. chinaXiv:201605.00847 [pdf]

South Galactic Cap u-band Sky Survey (SCUSS): Data Reduction

Hu Zou
Subjects: Astronomy >> Astrophysics

The South Galactic Cap u-band Sky Survey (SCUSS) is a deep u-band imaging survey in the Southern GalacticCap, using the 90Prime wide-field imager on the 2.3 Bok telescope at Kitt Peak. The survey observations started in2010 and ended in 2013. The final survey area is about 5000 deg2 with a median 5σ point source limitingmagnitude of ?23.2. This paper describes the survey data reduction process, which includes basic imagingprocessing, astrometric and photometric calibrations, image stacking, and photometric measurements. Surveyphotometry is performed on objects detected both on SCUSS u-band images and in the SDSS database. Automatic,aperture, point-spread function (PSF), and model magnitudes are measured on stacked images. Co-added aperture,PSF, and model magnitudes are derived from measurements on single-epoch images. We also present comparisonsof the SCUSS photometric ca

submitted time 2016-05-05 Hits2905Downloads1366 Comment 0

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