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1. chinaXiv:201711.02257 [pdf]

Insight-HXMT observations of the first binary neutron star merger GW170817

TiPei Li; ShaoLin Xiong; ShuangNan Zhang; FangJun Lu; LiMing Song; XueLei Cao; Zhi Chang; Gang Chen; Li Chen; TianXiang Chen; Yong Chen; YiBao Chen; YuPeng Chen; Wei Cui; WeiWei Cui; JingKang Deng; YongWei Dong; YuanYuan Du; MinXue Fu; GuanHua Gao
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Finding the electromagnetic (EM) counterpart of binary compact star merger, especially the binary neutron star (BNS) merger, is critically important for gravitational wave (GW) astronomy, osmology and fundamental physics. On Aug. 17, 2017, Advanced LIGO and Fermi/GBM independently triggered the first BNS merger, GW170817, and its high energy EM counterpart, GRB 170817A, respectively, resulting in a global observation campaign covering gamma-ray, X-ray, UV, optical, IR, radio as well as neutrinos. The High Energy X-ray telescope (HE) onboard Insight-HXMT (Hard X-ray Modulation Telescope) is the unique high-energy gamma-ray telescope that monitored the entire GW localization area and especially the optical counterpart (SSS17a/AT2017gfo) with very large collection area (~1000 cm2) and microsecond time resolution in 0.2-5 MeV. In addition, Insight-HXMT quickly implemented a Target of Opportunity (ToO) observation to scan the GW localization area for potential X-ray emission from the GW source. Although Insight-HXMT did not detect any significant high energy (0.2-5 MeV) radiation from GW170817, its observation helped to confirm the nexpected weak and soft nature of GRB 170817A. Meanwhile, Insight-HXMT/HE provides one of the most stringent constraints (~10-7 to 10-6 erg/cm2/s) for both GRB170817A and any other possible precursor or extended emissions in 0.2-5 MeV, which help us to better understand the properties of EM radiation from this BNS merger. Therefore the observation of Insight-HXMT constitutes an important chapter in the full context of multi-wavelength and multi-messenger observation of this historical GW event.

submitted time 2017-11-10 Hits1803Downloads970 Comment 0

2. chinaXiv:201711.02292 [pdf]

Analytic Forms for Cross Sections of Di-lepton Production from e+e? Collisions around the J/ψ Resonance

Xing-Yu Zhou; Ya-Di Wang; Li-Gang Xia
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

A detailed theoretical derivation of the cross sections of e+e? → e+e? and e+e? → ?+?? around the J/ψ resonance is reported. The resonance and interference parts of the cross sections, related to J/ψ resonance parameters, are calculated. Higher-order corrections for vacuum polarization and initial-state radiation are consid-ered. An arbitrary upper limit of radiative correction integration is involved. Full and simpli?ed versions of analytic formulae are given with precision at the level of 0.1% and 0.2%, respectively. Moreover, the results obtained in the paper can be applied to the case of the ψ(3686) resonance.

submitted time 2017-11-10 Hits1598Downloads893 Comment 0

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