Wenda Zhang
A5100691301- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Mechanics and Biomechanics Studies
- Galaxies: Formation, Evolution, Phenomena
- Particle Detector Development and Performance
- Astronomical Observations and Instrumentation
- Solar and Space Plasma Dynamics
- Astronomy and Astrophysical Research
- Nuclear Physics and Applications
- Urban Transport and Accessibility
- Ferroptosis and cancer prognosis
- High-pressure geophysics and materials
- Radio Astronomy Observations and Technology
- Stellar, planetary, and galactic studies
- Mathematical Dynamics and Fractals
- Urban Green Space and Health
- Urban Design and Spatial Analysis
- Experimental and Theoretical Physics Studies
- Underwater Vehicles and Communication Systems
- Geophysics and Sensor Technology
- Advanced Topology and Set Theory
- Chemical Looping and Thermochemical Processes
- Nanocomposite Films for Food Packaging
National Astronomical Observatories
2021-2024
Chinese Academy of Sciences
2004-2024
Czech Academy of Sciences, Astronomical Institute
2018-2024
China West Normal University
2024
Waseda University
2022-2024
Beihang University
2023
Harbin Institute of Technology
2018-2023
University of Kansas Medical Center
2023
Chongqing Jiaotong University
2023
Xuzhou Central Hospital
2023
A black hole x-ray binary (XRB) system forms when gas is stripped from a normal star and accretes onto hole, which heats the sufficiently to emit x-rays. We report polarimetric observation of XRB Cygnus X-1 using Imaging Polarimetry Explorer. The electric field position angle aligns with outflowing jet, indicating that jet launched inner emitting region. polarization degree (4.01+-0.20)% at 2 8 kiloelectronvolts, implying accretion disk viewed closer edge-on than orbit. observations reveal...
ABSTRACT We present an X-ray spectropolarimetric analysis of the bright Seyfert galaxy NGC 4151. The source has been observed with Imaging Polarimetry Explorer (IXPE) for 700 ks, complemented simultaneous XMM–Newton (50 ks) and NuSTAR (100 pointings. A polarization degree Π = 4.9 ± 1.1 per cent angle Ψ 86° 7° east north (68 confidence level) are measured in 2–8 keV energy range. shows that could be entirely due to reflection. Given low reflection flux IXPE band, this requires, however, a...
Abstract We report on an observational campaign the bright black hole (BH) X-ray binary Swift J1727.8–1613 centered around five observations by Imaging Polarimetry Explorer. These track for first time evolution of polarization a BH across hard to soft state transition. The 2–8 keV degree decreased from ∼4% ∼3% observations, but angle remained oriented in north–south direction throughout. Based with Australia Telescope Compact Array, we find that intrinsic 7.25 GHz radio aligns polarization....
<h3>Importance</h3> Long noncoding RNAs (lncRNAs) are involved in innate and adaptive immunity cancer by mediating the functional state of immunologic cells, pathways, genes. However, whether lncRNAs associated with immune molecular classification clinical outcomes immunotherapy is largely unknown. <h3>Objectives</h3> To explore lncRNA-based subtypes survival response to present a novel lncRNA score for prediction using computational algorithms. <h3>Design, Setting, Participants</h3> In this...
As a novel X-ray focusing technology, lobster eye micro-pore optics (MPO) feature both wide observing field of view and true imaging capability, promising sky monitoring with significantly improved sensitivity spatial resolution in soft X-rays. Since first proposed by Angel (1979), the have been extensively studied, developed trialed over past decades. In this Letter, we report on first-light results from flight experiment Lobster Eye Imager for Astronomy ($LEIA$), pathfinder wide-field...
Abstract We report the first detection of X-ray polarization bright transient Swift J1727.8−1613 with Imaging Polarimetry Explorer. The observation was performed at beginning 2023 discovery outburst, when source resided in hard state. find a time- and energy-averaged degree 4.1% ± 0.2% angle 2.°2 1.°3 (errors 68% confidence level; this translates to ∼20 σ significance detection). This finding suggests that hot corona emitting bulk detected X-rays is elongated, rather than spherical....
We report on a comprehensive analysis of simultaneous X-ray polarimetric and spectral data the bright atoll source GX 9+9 with Imaging Polarimetry Explorer (IXPE) NuSTAR. The is significantly polarized in 4--8 keV band, degree $2.2\% \pm 0.5\%$ (uncertainty at 68% confidence level). NuSTAR broad-band spectrum clearly shows an iron line, well described by model including thermal disk emission, Comptonized component, reflection. From spectro-polarimetric fit, we obtain upper limit to...
We present the first X-ray spectropolarimetric results for Cygnus X-1 in its soft state from a campaign of five IXPE observations conducted during 2023 May-June. Companion multiwavelength data are likewise shown. The 2-8 keV X-rays exhibit net polarization degree PD=1.99%+/-0.13% (68% confidence). signal is found to increase with energy across IXPE's bandpass. polarized an energy-independent angle PA=-25.7+/-1.8 deg. East North This consistent being aligned Cyg X-1's AU-scale compact radio...
Abstract The size and geometry of the X-ray-emitting corona in an active galactic nucleus (AGN) are still not well constrained. Dovčiak & Done proposed a method based on calculations assuming point-like lamp-post corona. To perform more self-consistent energy spectra extended coronae, we develop monk , Monte Carlo radiative transfer code dedicated to Comptonized Kerr spacetime. In assume Klein–Nishina scattering cross section include all general relativistic effects. We find that for...
We report on the first observation of a radio-quiet Active Galactic Nucleus (AGN) using polarized X-rays: Seyfert 1.9 galaxy MCG-05-23-16. This source was pointed with Imaging X-ray Polarimetry Explorer (IXPE) starting May 14, 2022 for net observing time 486 ks, simultaneously XMM-Newton (58 ks) and NuSTAR (83 ks). A polarization degree smaller than $\Pi<4.7\%$ (at 99% c.l.) is derived in 2-8 keV energy range, where emission dominated by primary component ascribed to hot corona. The...
ABSTRACT We report on the second observation of radio-quiet active galactic nucleus MCG-05-23-16 performed with Imaging X-ray Polarimetry Explorer (IXPE). The started 2022 November 6 for a net observing time 640 ks, and was partly simultaneous NuSTAR (86 ks). After combining these data those obtained in first IXPE pointing May (simultaneous XMM–Newton NuSTAR) we find 2–8 keV polarization degree Π = 1.6 ± 0.7 (at 68 per cent confidence level), which corresponds to an upper limit 3.2 99...
We report on the detection of X-ray polarisation in black-hole binary Swift J1727.8$-$1613 during its dim hard spectral state by Imaging Polarimetry Explorer (IXPE). This is first at transition from soft to an binary. find averaged 2$-$8 keV degree (3.3 ${\pm}$ 0.4) % and a corresponding angle 3{\deg} 4{\deg}, which matches detected rising stage outburst, September$-$October 2023, within 1${\sigma}$ uncertainty. The observational campaign complements previous studies this source enables...
The case histories are described of four brothers who suffered attacks transient global amnesia. coincidence this disorder in siblings suggests that the causative factors amnesia may have a familial basis and its incidence is more common than generally realised.
X-ray polarimetry can potentially constrain the unknown geometrical shape of AGN coronae. We present simulations polarization signal expected from coronae, assuming three different geometries, namely slab, spherical and conical. use fully relativistic Monte-Carlo Comptonization code monk to compute degree angle. explore coronal parameters such as shape, size, location optical depth. Different geometries give a significantly signal. A slab corona yields high degree, up 14% depending on...
We develop a new physical model for the broadband spectral energy distribution (SED) of X-ray illuminated accretion discs, that takes into account mutual interaction disc and corona, including all relativistic effects. assume Keplerian, optically thick geometrically thin an source in lamp-post geometry emits isotropic power-law spectrum with high-energy cut-off. would be released by thermal radiation standard its innermost part, is transported to effectively cooling this region. include...
ABSTRACT Measurements of the angular momentum (spin) astrophysical black holes are extremely important, as they provide information on hole formation and evolution. We present simulated observations an X-ray binary system with Imaging Polarimetry Explorer (IXPE), aim to study robustness spin geometry measurements using polarimetry. As a representative example, we used parameters GRS 1915+105 in its former unobscured, soft state. In order simulate polarization properties, modelled source...
A black hole (BH) can tear apart a star that ventures within its tidal radius, producing luminous flare as the stellar debris falls back, known disruption event (TDE). While TDEs in quiescent galaxies are relatively well understood, identifying active galactic nuclei (AGN) still remains significant challenge. We present discovery of AT2021aeuk, transient exhibiting dual flares around three years narrow-line Seyfert 1 galaxy. Multi-wavelength observations triggered during second 2023 revealed...
In September 2022, the transient neutron star low-mass X-ray binary XTE J1701--462 went into a new outburst. The objective of this work is to examine evolution accretion geometry by studying spectro-polarimetric properties along Z track source. simultaneous observations archived Insight -Hard Modulation Telescope (HXMT) and Imaging Polarimetry Explorer ( IXPE ) give us opportunity do this. We present comprehensive analysis J1701--462, using from -HXMT, NuSTAR . For observations, two methods...
Abstract A black hole (BH) can tear apart a star that ventures within its tidal radius, producing luminous flare as the stellar debris falls back, known disruption event (TDE). While TDEs in quiescent galaxies are relatively well understood, identifying active galactic nuclei (AGNs) still remains significant challenge. We present discovery of AT2021aeuk, transient exhibiting dual flares around 3 yr narrow-line Seyfert 1 galaxy. Multiwavelength observations triggered during second 2023...
Abstract Understanding the formation mechanisms of stellar-mass black hole X-ray binaries (BHXBs) remains a fundamental challenge in astrophysics. The natal kick velocities imparted during (BH) provide crucial constraints on these channels. In this work, we present new-epoch very long baseline interferometry (VLBI) observation Galactic BHXB AT2019wey carried out 2023. Combining with archival VLBI data from 2020, successfully measure proper motion over 3 yr timescale, namely, 0.78 ± 0.12 mas...
Accretion disks around stellar-mass black holes (BHs) emit radiation peaking in the soft X-rays when source is thermal state. The emerging photons are polarized and, for symmetry reasons, polarization integrated over expected to be either parallel or perpendicular (projected) disk axis, because of electron scattering disk. However, due General Relativity effects photon vectors will rotate with respect their original orientation, by an amount depending on both BH spin and observer's...
ABSTRACT X-ray polarimetry missions like Imaging Polarimetry Explorer will be able to measure for the first time polarization properties of accreting, weakly magnetized neutron stars in low-mass binaries. In this work, we present simulations expected polarized signal, including coronal emission different geometries corona itself, i.e. a slab above accretion disc and spherical shell around star. The are performed with fully relativistic Monte Carlo code monk capable computing degree angle...
ABSTRACT The central engine that powers gamma-ray bursts (GRBs), the most powerful explosions in universe, is still not identified. Besides hyper-accreting black holes, rapidly spinning and highly magnetized neutron stars, known as millisecond magnetars, have been suggested to power both long short GRBs. presence of a magnetar following compact star mergers particular interest it would provide essential constraints on poorly understood equation state for stars. Indirect indications these...