Chenhui Niu
A5000914186- Pulsars and Gravitational Waves Research
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Geophysics and Gravity Measurements
- Power Systems and Renewable Energy
- Power Systems and Technologies
- Antenna Design and Optimization
- Cosmology and Gravitation Theories
- Smart Grid and Power Systems
- Solar and Space Plasma Dynamics
- GNSS positioning and interference
- Astronomical Observations and Instrumentation
- Astronomy and Astrophysical Research
- Antenna Design and Analysis
- Islanding Detection in Power Systems
- HVDC Systems and Fault Protection
- Superconducting and THz Device Technology
- Radio Wave Propagation Studies
- High-pressure geophysics and materials
- Ga2O3 and related materials
- Soil Moisture and Remote Sensing
- Photovoltaic System Optimization Techniques
- Vibration Control and Rheological Fluids
Central China Normal University
2019-2025
Hebei University of Technology
2024-2025
Beijing University of Agriculture
2025
Beijing Academy of Agricultural and Forestry Sciences
2025
Shanxi Medical University
2025
National Astronomical Observatories
2019-2024
Chinese Academy of Sciences
2019-2024
Huaneng Clean Energy Research Institute
2022-2024
Yiwu Science and Technology Research Institute
2024
China Huaneng Group Co., Ltd. (China)
2021
The polarization of fast radio bursts (FRBs), which are bright astronomical transient phenomena, contains information about their environments. Using wide-band observations with two telescopes, we report measurements five repeating FRBs and find a trend lower at frequencies. This behavior is modeled as multipath scattering, characterized by single parameter, σRM, the rotation measure (RM) scatter. Sources higher σRM have RM magnitude scattering time scales. sources highest FRB 20121102A...
Fast radio bursts (FRBs) are brief, intense flashes of waves from unidentified extragalactic sources. Polarized FRBs originate in highly magnetized environments. We report observations the repeating FRB 20190520B spanning 17 months, which show that FRB's Faraday rotation is variable and twice changes sign. The also depolarizes below frequencies about 1 to 3 gigahertz. interpret these properties as being due parallel component magnetic field integrated along line sight, including reversing...
Abstract We report the observations of FRB 20220912A using Five-hundred-meter Aperture Spherical radio Telescope. conducted 17 totaling 8.67 hr and detected a total 1076 bursts with an event rate up to 390 −1 . The cumulative energy distribution can be well described broken power-law function lower- higher-energy slopes −0.38 ± 0.02 −2.07 0.07, respectively. also L -band (1–1.5 GHz) spectral index synthetic spectrum bursts, which is −2.6 0.21. average rotation measure value from −0.08 5.39...
Abstract Coherent curvature radiation as the mechanism for fast radio bursts (FRBs) has been discussed since FRBs were discovered. We study spectral and polarization properties of repeating within framework coherent by charged bunches in magnetosphere a highly magnetized neutron star. The spectra can be generally characterized multisegmented broken power laws, evolve move line sight sweeps. Emitted waves are linear polarized angles flat across burst envelopes, if is confined to beam an angle...
We report the properties of more than 800 bursts detected from repeating fast radio burst (FRB) source FRB 20201124A with Five-hundred-meter Aperture Spherical Telescope (FAST) during an extremely active episode on UTC September 25-28, 2021 in a series four papers. In this second paper series, we mainly focus energy distribution bursts. The event rate initially increased exponentially but activity stopped within 24 hours after 4th day. detection 542 one hour fourth day marked highest single...
Abstract We report on the optical spectroscopic observations of host galaxy hyperactive repeating fast radio burst (FRB) FRB 20240114A. The is a dwarf at redshift z = 0.1306 ± 0.0002. With rest-frame coverage 4300–7900 Å, we have detected H α , β [O iii ] λλ 4959,5007, [N ii 6548,6583, and [S λ 6716 emission lines. line ratios suggest that ionization in dominated by star formation. formation rate (SFR) derived from (0.06 0.01) M ⊙ yr −1 spectral energy distribution fitting suggests lower...
Abstract Fast radio bursts (FRBs) are signals that last milliseconds. They originate from cosmological distances and have relatively high dispersion measures (DMs), making them excellent distance indicators. However, the origins of FRB remain to be resolved. With its wide field view sensitivity, CHIME/FRB has discovered more than half all known FRBs. As FRBs located within or connected with their host galaxies, study progenitors is becoming important. In this work, we collect currently...
The Tianlai Dish Pathfinder Array is a radio interferometer designed to test techniques for 21~cm intensity mapping in the post-reionization universe as means measuring large-scale cosmic structure. It performs drift scans of sky at constant declination. We describe design, calibration, noise level, and stability this instrument based on analysis about $\sim 5 \%$ 6,200 hours on-sky observations through October, 2019. Beam pattern determinations using drones transit bright sources are good...
Abstract The repeating fast radio burst FRB 20190520B is localized to a galaxy at z = 0.241, much closer than expected given its dispersion measure DM 1205 ± 4 pc cm −3 . Here we assess implications of the large and scattering observed from for host galaxy’s plasma properties. A sample 75 bursts detected with Five-hundred-meter Aperture Spherical Telescope shows on two scales: mean temporal delay τ (1.41 GHz) 10.9 1.5 ms, which attributed galaxy, scintillation bandwidth Δ ν d 0.21 0.01 MHz,...
Abstract As the third paper in multiple-part series, we report statistical properties of radio bursts detected from repeating fast burst (FRB) source FRB 20201124A with Five-hundred-meter Aperture Spherical Telescope during an extremely active episode between 25th and 28th September 2021 (UT). We focus on polarization 536 bright S/N > 50. found that Faraday rotation measures (RMs) monotonically dropped −579 to −605 rad m −2 4 day window. The RM values were compatible (−300 −900 ) reported...
Abstract We report the properties of more than 800 bursts detected from repeating fast radio burst (FRB) source FRB 20201124A with Five-hundred-meter Aperture Spherical Telescope during an extremely active episode on UTC 2021 September 25th-28th in a series four papers. In this fourth paper series, we present systematic search spin period and linear acceleration object both 996 individual pulse peaks dedispersed time series. No credible was found data set. rule out presence significant...
The origin of fast radio bursts (FRBs), the brightest cosmic explosion in bands, remains unknown. We introduce here a novel method for comprehensive analysis active FRBs' behaviors time-energy domain. Using "Pincus Index" and "Maximum Lyapunov Exponent", we were able to quantify randomness chaoticity, respectively, bursting events put FRBs context common transient physical phenomena, such as pulsar, earthquakes, solar flares. In bivariate domain, repeated FRB bursts' deviate significantly...
Abstract We report the first detection of polarization angle orthogonal jumps, a phenomenon previously only observed from radio pulsars, fast burst (FRB) source FRB 20201124A. find three cases jumps in over 2000 bursts, all resembling those pulsar single pulses. propose that are due to superposition two emission modes could be produced highly magnetized plasma, and they caused by line sight sweeping across rotating magnetosphere. The shortest jump timescale is order 1 millisecond, which...
Abstract Fast radio bursts (FRBs) are bright originating at cosmological distances. Only three repeating FRBs FRB 20121102A, 20190520B, and 20201124A among ∼60 known have circular polarization. We observed the 20220912A with Robert C. Byrd Green Bank Telescope (GBT) L -band on 2022 October 24 detected 128 in 1.4 hr, corresponding to a burst rate of about 90 hr −1 , which is highest yet for by GBT. The average rotation measure (RM) was −0.4 ± 0.3 rad m −2 negligible intraday RM change,...
Abstract The possibility that primordial black holes (PBHs) form some part of dark matter has been considered for a long time but poorly constrained over wide mass range. Fast radio bursts (FRBs) are bright transients with millisecond duration. Their lensing effect proposed to be one the cleanest probes constraining presence PBHs in stellar-mass window. In this paper, we first apply normalized cross-correlation algorithm search and identify candidates lensed FRBs latest public FRB...
Fast radio bursts (FRBs) are bright millisecond at cosmological distances. Only a small fraction of FRBs apparently repeat. Polarization, fundamental property electromagnetic signals, often carries critical information about the radiation processes, environment, and intervening medium FRBs. Here we report circular polarization detections two active repeating FRBs, namely 20121102A 20190520B, with Five-hundred-meter Aperture Spherical Telescope. We detect in both which increases number to...
Abstract We report the timing analysis of PSR J1846−0513, a pulsar discovered by Five-hundred-meter Aperture Spherical radio Telescope (FAST) in Commensal Radio Astronomy FAST Survey. The possesses spin period 23.36 ms and spin-down rate ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover accent="true"> <mml:mrow> <mml:mi>P</mml:mi> </mml:mrow> <mml:mo>̇</mml:mo> </mml:mover> </mml:math> ) 1.0106(3) × 10 −18 s −1 , it is located an eccentric orbit e...
Abstract The detection of fast radio bursts (FRBs) in astronomy is a complex task due to the challenges posed by radio-frequency interference and signal dispersion interstellar medium. Traditional search algorithms are often inefficient, time-consuming, generate high number false positives. In this paper, we present DRAFTS , deep-learning-based transient pipeline. integrates object binary classification techniques accurately identify FRBs data. We developed large, real-world data set for...
Transient astrophysical events are characterized by short timescales, high energy, and multi-wavelength radiation, often accompanied violent energy releases. These phenomena a major focus of modern astronomical research. To reveal their underlying physical mechanisms, near-real-time, multi-wavelength, multi-messenger follow-up observations essential. However, current transient alert systems face multiple challenges, including fragmented messages, inconsistent formats, difficulties in...
The existing single-pulse search algorithms for fast radio bursts (FRBs) do not adequately consider the frequency bandpass pattern of pulse, rendering them incomplete relatively narrow-spectrum detection pulses. We present a new algorithm narrow-band pulses to update standard pipeline, Bandpass-Adaptive Single-pulse SEarch Toolkit (BASSET). BASSET employs time-frequency correlation analysis identify and remove noise involved by zero-detection band, thereby enhancing signal-to-noise ratio...