We have searched for weak fast radio burst (FRB) events using a database containing 568,736,756 transient events detected using the Parkes radio telescope between 1997 and 2001. In order to classify these pulses, and to identify likely FRB candidates, we used a machine learning algorithm based on ResNet. We identified 81 new candidate FRBs and provide details of their positions, event times,...
We study the small scale magnetic reconnection above the radiative inefficient accretion flow around massive black hole via 2D magnetohydrodynamics (MHD) numerical simulation, in order to model the blob formation and ejection from the accretion flow around Sgr A*. The connection of both the newly emerging magnetic field and the pre-existing magnetic field is investigated to check whether blobs...
Plenty of crucial information about our Universe is encoded in the cosmic large-scale structure (LSS). However, the extractions of these information are usually hindered by the nonlinearities of the LSS, which can be largely alleviated by various techniques known as the reconstruction. In realistic applications, the efficiencies of these methods are always degraded by many limiting factors, a...
Based on the spectroscopic and shear catalogs for SDSS galaxies in the local Universe, we compare optically-selected active galactic nuclei (AGNs) with control star-forming and quiescent galaxies on galactic, inter-halo and larger scales. We find that AGNs are preferentially found in two specific stages of galaxy evolution: star-burst and `green valley' phases, and that the stellar population...
本次报告中我将介绍近期我们从SDSS DR14 quasar catalog中构建出的，目前为止最大的一批极端光变类星体(EVQs)样本，包括其搜寻方法、物理性质和相关物理过程的探讨。EVQs被认为是用来研究变脸(changing-look)类星体以及类星体点燃和熄灭过程(turn on/off)比较理想的样本，对这种传统模型难以解释的短时标大幅度光变源的研究也可以加深我们对星系核活动相关物理过程的认识。因此我们近期从SDSS DR14Q出发结合PAN-STARRS数据，通过谨慎的筛选，找到了14,012个类星体样本，并根据其光谱观测时的高低态进行了分类叠加，分析了不同状态下EVQs与对照组在连续谱和宽发射线上的区别。此外我们还将简要介绍目前针对该样本中个源的研究进展和计划。
Fallback in core-collapse supernovae (CCSNe) plays an important role in determining the properties of the central compact remnants, which might produce a black hole (BH) hyperaccretion system in the centre of a massive CCSN. When the accretion
rate is extremely high and neutrino cooling is dominant, the hyperaccretion should be in the phase of the neutrino-dominated accretion flows (NDAFs),...
Recently, the XENON1T experiments has reported the possible detection of an excess in the electronic recoil spectrum. We use mirror DM and plasma DM model to explain this excess and predict the possible signal in the future nuclear direct detection.
We probe the effect of cluster environment to the star formation quenching in galactic thin disks for 18 galaxies (17 early-type, 1 late-type) in the Fornax cluster. High quality data resolving the kinematical and chemical information across the observational plane are obtained through IFU observations with MUSE/VLT. We create population-orbit superposition models to each galaxy, the model...
We perform scanning tunneling microscopy/spectroscopy (STM/STS) study on the layered iron based superconductor KCa2Fe4As4F2 with a critical temperature of about 33.5 K. The commonly obtained surface shows full-gap feature with energy gap values close to 4.6 meV. This type of spectrum presents a uniform full gap in space indicating the absence of gap nodes in this superconductor. Quasiparticle...
Very high energy (VHE,>100 GeV) gamma-rays open a crucial window to explore the "non-thermal Universe". High-sensitivity, unbiased surveys of the gamma-ray sky are important to find new astrophysical objects - both to understand their bulk properties, and to constrain new physics beyond the standard model. Up to now, more than 230 sources are detected mainly by IACT (like Whipple, HESS, MAGIC...
Invariant curves are generally closed curves in the Poincare ́ surface of section. Here we study an interesting dynamical phenomenon, first discovered by Binney (1985) in a rotating Kepler potential, where an invariant curve of the surface of section can split into two disconnected line segments under certain conditions, which is distinctively different from the islands of resonant orbits. We...
最近，有研究者在几种镍氧化物薄膜 R1-xAxNiO2 (R = La, Pr, Nd; A = Ca, Sr) 中发现了约 5-15 K 的超导电性，这引起了超导和材料相关领域的极大关注。由于其母相 RNiO2 中Ni的 3d9 核外电子排布与铜基高温超导母体极其相似，因此人们认为这两类材料中的超导电性可能具有相同的起源。我们利用高温高压和低温软化学还原相结合的三步合成方法，成功制备了块材 Nd1−xSrxNiO2 (x = 0, 0.2,...
过渡金属化合物中，因为电荷、自旋、晶格、轨道等自由度之间的相互作用，很多有序态之间具有相似的能量。其中有个常见的态是电子向列相，它的出现破坏了晶体的面内旋转对称性，并经常和其他态共存、互相影响、合作或竞争。而具有kagome晶格的材料包含丰富的奇异电子特性，比如自旋液体、电荷密度波、超导和拓扑态等。最近，新的拓扑kagome金属家族AV3Sb5 (A = K, Rb, or Cs) 被发现，并迅速引起了广泛关注。我们在CsV3Sb5单晶的面内旋转磁场并测量c方向的电阻率，观测到c方向的电阻率无论在超导态还是正常态都具有二度旋转对称性，并且超导态和正常态对应曲线的极值角度方向相互垂直。我们的研究结果为理解CsV3Sb5特殊的物理性质提供了新的思路。
Dense dark matter is predicted around super-massive black hole (SMBH). Recently, the Event Horizon Telescope and GRAVITY groups, which focus on M87* and Galactic Center, have published their observations, which provide us a good chance to search dark matter.
With the continuous upgrade of detectors, more and more gravitational wave (GW) events were captured by the LIGO Scientific Collaboration and Virgo Collaboration (LVC), which offers a new avenue to test General Relativity and explore the nature of gravity. Although, various model-independent tests have been performed by LVC in previous works, it is still interesting to ask what constraints on...
Link(1992) considered the newly-developed observation could be a strong evidence for external torque interpretation of persistent offset, developed by Ruderman(1991), We conclude in this talk that after 30 years of accumulation of observation data volume, new observational evidence has in turn been able to rule out the external torque explanation in favor of the internal mechanism associated...
Microwave Kinetic Inductance Detectors(MKIDs) are very promising superconducting detector arrays used in the field of terahertz astronomy. It has attracted much attention due to its simple implementation of frequency-multiplexing readout technology. The Purple Mountain Observatory(PMO) of the Chinese Academy of Sciences has carried out related research on the MKIDs detector based on the...
Characterization the equilibrium topological invariants through the dynamics quench process attracts extensive interests very recently. Usually, the characterization of non-equilibrium topological invariants shown during the dynamics quench requires information in both the time and spatial dimensions. We propose the topological holographic quench dynamics in synthetic dimension to characterize...
在铜氧化物超导体中，由于电子的强关联特性，有许多与超导态共存或者与超导竞争的序。它们中反铁磁序是其中最主要的一个。往往在相图中超导出现的区域长程反铁磁已经被破坏了，但在高掺杂下会出现剩下的短程反铁磁涨落。它们在超导态中所扮演的角色仍然被高度的关注。这里我们利用自旋极化的扫描隧道显微镜，第一次直接观测到在掺杂进最佳掺杂的Bi2Sr2CaCu2O8+δ的Fe原子附近的一个非公度反铁磁序。Fe杂质压制了超导能隙结构中相干峰的强度，破坏了超导相干，但也将短程的非公度反铁磁序钉扎下来。我们的工作揭示了超导与反铁磁的密切关系，为理解高温超导与反铁磁的相互作用与高温超导配对提供了新的认识。
近期新发现的Kagome金属家族AV3Sb5 (A = K, Rb, or Cs)展现出电荷密度波、超导电性以及拓扑非平庸的Dirac能带, 迅速引起凝聚态物理学界的广泛关注，其中电荷密度波的驱动机制及其与超导电性的关系是当前该领域争论的焦点。我们利用红外光谱对CsV3Sb5中的电荷密度波进行了研究。结果显示，在TCDW=91...
There has been considerable recent progress in identifying candidate materials for the transverse-field Ising chain (TFIC), a paradigmatic model for quantum criticality. Here, we study the local spin dynamical structure factor of different spin components in the quantum disordered region of the TFIC. We show that the low-frequency local dynamics of the spins in the Ising- and transverse-field...
The transverse field Ising chain (TFIC) at its quantum critical point (QCP) in the scaling limit turns to be a central charge 1/2 conformal field theory (CFT). In the vicinity of a small longitudinal magnetic field, eight quasiparticles emerge and the whole system can be described by exceptional $E_{8}$ Lie algebra. This excitation essentially arises from weak confinement due to the...
TBG and moire system have attracted huge interest in both experimantal and theoretical community due to its exotic strong correlated properties and rich phase diagram. However there is still lack of a general theory for arbitrary twisted angle without commensurate approximation. And the superconductive pairing mechanism in TBG is still controversial.
We propose a new kind of geometric theory...
We explore the applications of a network of vector sensors, sensitive to certain spatial components of the signals, in identifying the property of light axion or dark photon background. These bosonic fields contribute to vector-like signals in the detectors, including effective magnetic fields triggering the spin precession, effective electric currents in a shielded room, and forces on the...
The PandaX-4T experiment will utilize a two-phase liquid/gas xenon time projection chamber to search dark matter. The PandaX-4T is located in the Hall B2 of the Jinping Underground Laboratory with 2400 m overburden. In the commissioning run, 1058 candidate events are identified with 3.7-tonne of liquid xenon target and an exposure of 0.63 tonne·year. A stringent limit to the dark...
Semi-Digital Hadron Calorimeter (SDHCAL) prototype for CEPC is a PFA-based hadron calorimeter that has shown good energy and position resolution with a CERN test beam. Considering the signal time of hadronic shower formed by neutrons is delayed, compared with that from charged hadrons, high-precision time measurement, requiring at least 100ps orders, helps improve separation between
neutrons...
原子核的质量是核物理中最基本的物理量之一，原子核质量的预言在核物理以及核天体领域中具有广泛且重要的应用。镜像核质量公式基于同位旋对称性和库仑相互作用，对丰质子区原子核质量进行精确描述，公式的精度达到 110–130 keV。通过奇偶性分组拟合和残差关联效应，质量公式的精度进一步降低到 50–90 keV。通过使用镜像核质量公式，可以对丰质子区原子核的质量进行预言，预言值和最新实验数据精确吻合。
In this work we present the analysis of Collins-Soper kernel extracted from pion transverse momentum dependent wave functions in the framework of large momentum effective theory from lattice QCD. We use clover fermion action with $2 + 1 + 1$ flavors of highly improved staggered quarks (HISQ), with lattice spacing $a=0.12$fm and volume $L^3\times T=48^3\times64$. The results are obtained based...
