Conveners
session: open address
- Ruoyu Liu (Nanjing University)
session: cosmic-ray physics
- Shoushan Zhang (Institute of High Energy Physics)
session: PWN & pulsar halo
- Dmitriy Khangulyan (高能所)
session: SNRs
- Yang Chen (Department of Astronomy, Nanjing University)
session: computing platform and AI
- Yaodong Cheng (IHEP)
session: poster flash talks-1
- Huicai Li (高能所)
session: poster flash talks-2
- Zhiyong You ()
session: Binary
- Dahai Yan ()
session: extra-galactic source and GRB
- Zhuo Li (Peking University)
session: Cosmic-Ray Anisotropy
- Fulai Guo (Shanghai Astronomical Observatory)
session: Diffuse gamma
- Dmitri Semikoz (APC, Paris)
session: poster flash talk-3
- Zhiyong You ()
- Huicai Li (高能所)
session: new physics and multi-wavelength observation
- Bo-Qiang Ma (Peking University)
session: data&operaton&close remark
- songzhan（松战） CHEN（陈） (中科院高能物理研究所)
session: poster time
- There are no conveners in this block
session: poter time
- There are no conveners in this block
session: IB meeting
- There are no conveners in this block
In this talk, I will report the recent work of PCC.
The data quality is of core importance for an experimental collaboration. LHAASO collaboration has made great efforts to monitor the operation status of detectors and ensure the quality for selected data is good enough for future analysis. In this talk, I will give a brief introduction about the data check and monitoring for 3 sub-arrays, including KM2A , WCDA and WFCTA.
Magnetic fields are ubiquitous in relativistic outflows and are expected to play a central role in the acceleration of nonthermal particles. In recent years, particle-in-cell studies have shown that the current-driven kink instability can efficiently convert magnetic energy into energetic particles, but this picture has largely been developed for kinetic scales, highly magnetized plasmas, and...
Summary of work as a coordinator in cosmic ray physics and important progress made by LHAASO in cosmic ray energy spectrum measurement
15mins
LHAASO is a composite cosmic ray observatory comprising KM2A, WCDA, and WFCTA detector arrays. One of the core scientific goals is to precisely measure the energy spectra of individual cosmic ray components, establish a bridge between space-borne and ground-based experiments to constrain the origin, acceleration, and propagation mechanisms of cosmic rays. This work presents the joint...
The absence of cosmic ray flux data with known energy and composition in the high-energy range makes it impossible to perform a direct absolute calibration of the energy scale for ground-based cosmic ray experiments. This leads to a discrepancy between the measured cosmic ray energy and its true energy, which affects not only the fine structure of the cosmic ray spectrum but also the absolute...
In this work, the proton-air inelastic cross section at a primary cosmic ray energy of $1~\mathrm{PeV}$ is measured with LHAASO experiment. The analysis is based on hybrid observational data from KM2A and WFCTA. The depth of air shower maximum $X_{\max}$ is reconstructed using the WFCTA geometrical observable ${Dist}$. The distribution of $X_{\max}$ is strongly correlated with the exponential...
The cosmic ray all-particle energy spectrum exhibits a distinct softening at roughly $100 \, \rm PeV$, referred to as the second knee. This feature is widely regarded as signifying the cutoff of heavy Galactic nuclei and marking the onset of the Galactic-to-Extragalactic transition. Given the discrepancies in current experimental data regarding the second knee, the Large High Altitude Air...
This is a summary of convener's work on pulsar-related studies. (15 min + 5 min)
LHAASO J2027+3657 is an ultra-high-energy (UHE) gamma-ray extended source discovered by LHAASO in the Cygnus region. No significant gamma-ray emission with energy below 25 TeV has been detected from this source, and ground-based facilities like H.E.S.S. and HAWC have not detected it either, making the origin of its emission especially interesting. In this study, we use the latest LHAASO data...
We present an analysis of the source 1LHAASO J2028+3352 reported in the 1LHAASO catalog. The source is spatially coincident with the pulsar PSR J2028+3332, which has a characteristic age of 580 kyr. Based on the LHAASO data, our fitting results reveal that the source exhibits a large extension and an elliptical spatial morphology. These observational characteristics support the source as a...
We report a detailed LHAASO study of the extended very-high-energy $\gamma$-ray source LHAASO J0635$+$0619 and investigate its possible association with the middle-aged pulsar PSR J0633$+$0632 as a pulsar halo candidate toward the Monoceros Loop region. Using WCDA data collected from 2021 March to 2025 July and KM2A data from 2019 December to 2025 July, we performed a three-dimensional...
Pulsar wind nebulae (PWNe) are the dominant Ultra-high-energy (UHE) gamma-ray sources in the LHAASO catalog, suggesting that they are the dominant leptonic PeVatrons in our Galaxy. Despite this, very little is still known about their UHE gamma-ray emission, their number in the Galaxy, or their contribution to the gamma-ray emission of our Galaxy. In this work, we propose a self-consistent,...
I will report progresses on studies of SNRs.
We performed a detailed analysis of a region in the Galactic plane between 52° and 55° longitude using data collected from the LHAASO-KM2A (1570 days) and WCDA (1137 days) detectors, as well as the GeV observations from the Fermi-LAT. This area is exceptionally rich, hosting multiple supernova remnants (SNRs), pulsars, and pulsar wind nebulae (PWNe) that emit from radio to TeV. Consequently,...
We report a dedicated study of the newly discovered extended ultra-high-energy (UHE) γ-ray source 1LHAASO J1839-0545u using data collected between December 2019 and July 2025. The source is significantly detected with statistical significances of 24σ, 25σ, and 16σ in the 1–25 TeV, 25–100 TeV, and >100 TeV energy bands, respectively. Its morphology is best described by a disk model with an...
Using observational data from the LHAASO and the Fermi-LAT, we conduct a systematic investigation of the sky region harboring the TeV gamma-ray source LHAASO J2005+3415. This source displays a notably extended spatial morphology and a relatively soft energy spectrum in the TeV band; its GeV counterpart, however, exhibits spatial and morphological consistency with the TeV emission, indicating a...
Based on ParticleNet, ParticleTransformer, and physics prior knowledge, we modified the model architecture and achieved a significant improvement in performance on the 2024 experimental data of the Crab Nebula. In addition, we explored a semi-supervised learning approach. Using the SimSiam training framework, we performed extensive pretraining on a large amount of experimental data, which...
In this report, we present our exploration of leveraging Vision Transformers to enhance the performance of WCDA. Using pre-trained ViT and Swin Transformer, we inject the hit's charge and time information into different color channels of the images and conduct a systematic study on the effects of patch number, image resolution, and other factors. Based on the above methodology, we achieve...
The integration of AI and experimental physics has become a prominent trend, holding the promise of enhancing experimental performance without increasing engineering budgets. This report details the development of the LHAASO-AI model and presents its performance evaluation on both simulated and experimental data.
This report will present the recent operation status of the LHAASO computing platform, including job execution, computing and storage resources, network conditions, data transmission systems, and so on.
The ``knee'' of cosmic ray spectra may reflect the maximum energy accelerated by galactic cosmic ray sources or the limit of the galaxy's ability to bind cosmic rays. Measurements of individual energy spectra are a crucial tool to understand the origin of the knee. Energy reconstruction and composition identification are foundations of the individual energy spectra measurements. One of the...
Abstract: The longitudinal development of muons in air showers provides important constraints on cosmic-ray composition and serves as a test for hadronic interaction models. In this study, the muon production depth is reconstructed by analyzing muon arrival times over an energy range of 1 PeV to 50 PeV and a zenith angle range of 10°–30°. The depth at which muon production reaches its maximum...
As a significant fraction of LHAASO gamma-ray sources are still unidentified, part of them could correspond to illuminated (obscured) molecular clouds, thus acting as so called « dark sources ». Indeed, interaction between cosmic rays and dense clouds can generate gamma-rays via p-p collisions and pion decay processes. Clouds could be illuminated by a nearby accelerator of cosmic-rays or by...
Primary high-energy cosmic rays induce extensive air showers in the Earth's atmosphere, with the fluxes of neutrons, muons and other secondary cosmic ray particles showing significant anomalies during the seismogenic and pre-earthquake stages of strong earthquakes. Existing studies have verified a distinct statistical correlation between ground-observed cosmic ray intensity anomalies and...
In gamma-ray astronomy, Water Cherenkov Detectors (WCDs) have been proven by large-scale projects like HAWC and LHAASO to be a highly effective technology for constructing large-area air shower observation arrays. For such arrays, the timing performance of individual detector units is of critical importance to the angular resolution. This study presents the prototype testing of a surface WCD...
Cosmic ray (CR) observatories have detected characters of CR anisotropy across different energy ranges including contributions from both galactic cosmic rays (GCRs) and extragalactic cosmic rays (EGCRs). We obtain simulation CR anisotropy results by back-tracing test particles in turbulent magnetic fields. For GCRs, we discuss the anisotropy dipole flip happened between about 10 TeV to...
Coronal Mass Ejections (CMEs) are rapid energy-release events in which a large amount of plasma from the solar corona is ejected into the heliosphere. Some CMEs, if sufficiently intense and appropriately directed, can propagate into interplanetary space. Research on ICMEs primarily relies on direct observations of solar energetic particles, with corresponding particle energies typically below...
This work will focus on the galactic cosmic-ray Sun shadow observation during 2020 to 2025 with KM2A. Some features will be discussed to explore possible relation between shadow features and the solar eruptive activities, such as the CMEs.
The KM2A array of the LHAASO experiment, leveraging its unprecedented high statistical accuracy and daily sampling period, has achieved the daily observation of the cosmic ray sun shadow. This study aims to utilize solar photospheric magnetic field data (HMI/ADAPT) in combination with the PFSS model to extrapolate the coronal magnetic field, and to conduct particle back-tracking simulations...
Solar disk gamma rays, theorized to originate from hadronic galactic cosmic-ray interactions, exhibit many puzzling features. At 1 giga-electronvolts (GeV), these features include high flux and anti-correlation with the solar activity cycle. Between 10 and 50 GeV, it also displays an unexpected time- and energy- dependent morphology. A key question is how solar magnetic fields could affect...
Cosmic rays interacting with the solar atmosphere produce secondary high-energy gamma rays, but the observed solar gamma-ray emission still deviates from conventional theoretical expectations. Localized magnetic structures near the solar surface, especially coronal flux ropes associated with magnetic reconnection, may significantly affect the transport of incoming cosmic-ray protons and thus...
The Sun exhibits a TeV flux that significantly exceeds theoretical expectations, challenging conventional particle interaction models. In this Letter, we demonstrate that secondary electron-positron ($e^{\pm}$) pairs constitute a crucial and irreducible component of the observed solar signal. Due to their Extensive Air Shower (EAS) morphology being virtually indistinguishable from that of...
Vision-Language Models (VLMs) integrate image information into the representation space through visual encoders, overcoming the information bottleneck associated with pure text token inputs. Tailored to the structural characteristics of the LHAASO array detectors, this study explores the feasibility of employing array trigger images as a new input modality, aiming to enhance particle...
Telling apart Gamma and Cosmic rays is an important part of observing VHE sources. However, at low energies (10-100 TeV), this can often be challenging due to degeneracies in how the two show up on detectors such as LHAASO-KM2A. In this work, we leverage semi-supervised learning and explore if it is able to perform better than the traditional method (Q-Cut). Semi-Supervised Learning is a type...
The LHAASO experiment combines multiple detector arrays with complementary sensitivities to extensive air showers. Among them, KM2A has strong gamma–hadron discrimination capability, while LACT provides high-resolution imaging and precise directional reconstruction. Exploiting the synergy between these two detectors is crucial for improving the overall performance of the experiment.
In this...
We investigate the observational capabilities of the upcoming LACT Cherenkov telescope array for the microquasar SS 433 through detailed simulations. Our results indicate that a detection significance of 5𝜎 can be achieved with approximately 30 hours of observation; this exposure, coupled with LACT’s excellent angular resolution, enables the spatial separation of the eastern and western jets....
Spiders, are compact binary millisecond pulsars .These systems consist of neutron stars in tight orbits with low-mass companions, which are gradually ablated by the pulsar wind. They are promising targets for studying intrabinary shocks, particle acceleration, and possible TeV gamma-ray emission. We performed a stacking analysis of spiders using LHAASO observations from 2021 to 2025, combining...
Recently, a wide range of gamma-ray-emitting binaries have been detected in TeV gamma rays, including microquasars, pulsar binaries, colliding-wind binaries, and novae. In this talk, I will focus on neutron star (NS) binaries powered either by accretion or by a pulsar wind, and discuss their potential relevance to sources detected by LHAASO, including LS I +61° 303 and SAX J2103.5+4545. I will...
The microquasar MAXI J1820+070 was discovered during its X-ray outburst in 2018. Previous KM2A observations identified a point-like gamma-ray excess with a significance of about 6 sigma near the source, though the position was located 0.27 degrees northeast of the black hole. Based on approximately four and a half years of observations, WCDA also detected an excess with a significance of 4.3...
Binary systems can accelerate particles to the TeV energy range, thereby producing TeV radiation. Currently, tens of binary systems have been detected in the TeV band. Here, we report on the massive X-ray binary XTE J1858+034—a symbiotic system composed of an X-ray pulsar and a K–M type late-stage companion—located at the central position of the TeV source LHAASO J1858+0330, with an angular...
Using data from LHAASO's WCDA and KM2A, we detected TeV gamma-ray emission from the supernova remnant S147. The morphology of the emission can be described as a point source plus an extended component in the WCDA data, while the KM2A data suggests a point-like source (with a 95% upper limit on the extension of 0.15°). The fitted point source position is slightly offset (~0.1°) from the pulsar...
We present a systematic analysis of pulsar TeV halos using data from the LHAASO. A sample of at least six halo sources has been studied with a unified analysis framework, including Geminga, Monogem, PSR J0622+3749, PSR J0631+1036, PSR J0248+6021, and PSR J0633+0632. For each source, we perform spatial and spectral modeling to constrain the diffusion properties of high-energy electrons and...
Charged cosmic rays (CRs) are believed to propagate diffusively in the turbulent magnetic field of the Milky Way. The diffusion coefficient, which depends on the properties of the turbulent interstellar medium (ISM), is a key parameter governing CR propagation. We present an updated analysis of the extended very-high-energy (VHE) gamma-ray emission around the middle-aged (207.8 kyr) pulsar PSR...
LHAASO has discovered decades of PeVatrons, including Pulsar Wind Nebulae (PWN), Supernova Remnants (SNR), and binary systems, among others. One of the advantages of LHAASO is its wide field of view, which enables comprehensive surveys of the entire northern sky. Besides where sources are densely packed within the Galactic Plane and the Galactic Center direction, there may also be high-energy...
Gamma-ray observations have established energetic isolated pulsars as outstanding particle accelerators and antimatter factories. However, many questions are still open regarding the acceleration and radiation processes involved, as well as the locations where they occur. The radiation spectra of all gamma-ray pulsars observed to date show strong break above energies of a few GeV. LHAASO may...
We report the detection of a TeV gamma-ray source, designated as LHAASO J1915+1149. The detection significance is 11𝜎 in the WCDA band and 18.5𝜎 in the KM2A band. The source is spatially coincident with the pulsar PSR J1915+1150. Its morphology in the WCDA band is consistent with a diffusion model, whereas no significant extension is resolved in the KM2A band, aligning with a point-like source...
we describe the numerical framework used to simulate the 3D propagation of CRs from a SNR into a complex molecular environment. Our model couples the time-dependent injection of particles from the SNR shock with a non-linear transport scheme that accounts for CR self-confinement and environmental damping.
Transient gamma-ray sources are important for understanding the non-thermal universe and the origin of cosmic rays, but their short durations and unpredictable occurrence make them difficult to detect. With its wide field of view, high duty cycle, and broad energy coverage, LHAASO-KM2A is well suited for such searches.
In this work, we perform a systematic search for transient gamma-ray...
The first source catalog of the Large High Altitude Air Shower Observatory (LHAASO) reported
90 very-high-energy gamma-ray sources [1], providing a comprehensive view of the TeV–PeV sky.
With an expanded dataset, we perform an updated analysis to demonstrate how increased statis-
tics reveal changes in source morphology and resolve finer emission structures.
In this work, we focus on a...
Using LHAASO-KM2A (2021–2025) and LHAASO-WCDA (2021–2025) data, we detected a gamma-ray source, J2346+5145, with a test statistic (TS) of ~171.10 and a 2D Gaussian extension of ~0.14° . This source lies within the 95% positional uncertainty of 1LHAASO J2346+5138 (TS=47.6) from the First LHAASO Catalog. It is also spatially close to the intermittent extreme high-frequency-peaked BL Lac (EHBL)...
We present a search for periodic signals in the Galactic background region using LHAASO-KM2A data collected from the beginning of full-array operation in 2021 to August 2025. Using all valid-day observations in this period, we systematically organize the background signals in the Galactic plane and investigate their possible periodic behavior.
In this work, the Galactic region is divided...
The Large High Altitude Air Shower Observatory (LHAASO) has previously reported a catalog of gamma-ray sources above 25 TeV, revealing a population of very-high-energy emitters in the Galactic plane. Identifying sources that remain detectable beyond 400 TeV is crucial for pinpointing the most extreme Galactic particle accelerators (PeVatrons). At these energies, the implied parent particles...
Massive star-forming regions (SFRs) are promising environments for the acceleration of Galactic cosmic rays. The M17 region, one of the most active star-forming complexes in the Galaxy, comprises a prominent $\mathrm{H\,II}$ region, a young stellar cluster (NGC 6618), and a giant molecular cloud. Its unique and complex structure makes it a key target for the search for high-energy $\gamma$-ray...
In this talk I'll present self-consistent leptonic, hadronic, and leptohadronic models that reproduce both the observed spectrum and morphology of microquasar V4641 Sgr in X-rays and gamma-rays.
Results are published in two papers: arXiv:2512.13578 and Phys.Rev.D 111 (2025) 10, 103025
J2004+3252 is an extended source (~2° extension) listed in the 1LHAASO catalog. Based on four years of LHAASO observations, we decompose this complex region into three distinct sub-sources. One of them, J1959+3518, is spatially coincident with Cygnus X-1. For J1958+3017, we identify associated CO and HI gas distributions, along with two SNRs in its vicinity. Additionally, the third sub-source,...
We have implemented the Richardson–Lucy deconvolution algorithm for KM2A. Using this algorithm，our analysis reveals that the morphology of the TeV emission from the Cygnus X region closely resembles that observed in both infrared and radio bands. By comparing the TeV morphology with infrared emission features, we find morphological evidence linking the TeV radiation to either the Strömgren...
Recently, the Large High-Altitude Air Shower Observatory (LHAASO) collaboration reported ultra-high-energy gamma-rays from six microquasar systems. For five of these, the emission exceeds $100$ TeV, making microquasars promising Galactic PeVatrons. In this work, we investigate whether gamma-rays around $100$ TeV can originate from hadronic interactions of accelerated cosmic rays with the...
Summary on studies of AGNs with LHAASO
We review the research of gamma-ray burst in the LHAASO collaboration. The scientific merits of GRB 221009A dtected by LHAASO are summarized. We expect the enhancemant of multi-wavelength and multi-messenger works in the time-dormain research field of LHAASO collaboration in the future.
On 26 February 2026 at 10:38:18.84 UT, Fermi-LAT triggered on high-energy emission from GRB 260226A. This event exceeded a very high energy threshold, making it only the second GRB to do so since GRB 090510. Following this alert, we conducted follow-up observations of this source. Here, we present the WCDA observations from both triggered and triggerless data, along with some preliminary results.
协调人报告 10min
In this talk, we present the measurements of the cosmic-ray anisotropies using three years of WCDA data. We extended our measurement to the lower energy, about 600 GeV. We find a significant energy dependence of the dipole component of the sidereal-time anisotropy below several TeV. Meanwhile, we also find the remarkable influence of solar activities on the solar-time anisotropy at sub-TeV.
The weak anisotropies in the arrival directions of cosmic rays provide critical insights into their origin and propagation mechanisms. While rigidity-dependent variations offer a more direct and effective probe of cosmic-ray transport than energy-dependent evolution, such measurements have remained historically elusive. Here, for the first time, we reconstruct primary cosmic-ray rigidity using...
This talk presents new measurements of cosmic-ray anisotropy using the LHAASO-KM2A array, with a focus on composition-dependent features. A clear difference in anisotropy between light and heavy mass groups is observed. In addition, updated results on the all-particle anisotropy are reported.
This is a summary report of the working group progresses of diffuse gamma-ray analysis with LHAASO.
We analyze the 0mu events detected by LHAASO-KM2A. Above 400 TeV, these events achieve a cosmic-ray background rejection power of about . We find that differences in source masks can partly explain the discrepancies between the AS and LHAASO-KM2A measurements of GDE. A clustering analysis of the 0mu events further reveals several regions of enhanced gamma-ray emission, whose spatial...
The diffuse Galactic gamma-ray emission, mainly produced via interactions between cosmic rays and the interstellar medium and/or radiation field, is a crucial probe of the distribution, propagation, and interaction of cosmic rays in the Milky Way. Using the source deduction method and the latest data from WCDA and KM2A, we have preliminarily measured this emission and present the energy...
We present the preliminary 2LHAASO catalog of VHE-UHE gamma-ray sources detected by LHAASO, constructed using KM2A and WCDA data collected up to July 2025. Benefiting from increased exposure as well as improved reconstruction and analysis techniques, this catalog significantly improves upon the first release (1LHAASO) in detection sensitivity and source resolving. In this talk, we will...
We search for TeV quasi-periodic oscillations (QPOs) in the nearby high-synchrotron-peaked blazars Markarian 421 (z = 0.031) and Markarian 501 (z = 0.034) using the LHAASO-WCDA detector. Its high duty cycle and superior sensitivity enable long-term, high-statistical-significance, and continuous monitoring of these sources. Our analysis strategy involves constructing daily binned light curves...
High-frequency BL Lacertae objects (HBLs) are defined by a synchrotron peak of their broadband spectral energy distribution (SED) at a frequency of νₛ ≥ 10¹⁵ Hz. The BL Lac object 1ES 1218+304, at a redshift of z = 0.182, is a well-recognized HBL and is known to exhibit significant variability. Monitoring observations of 1ES 1218+304 with the LHAASO, conducted from March 2021 to July 2025,...
Galaxy clusters are the largest gravitationally bounded systems in the universe. Almost 80% of their content is dark matter (DM), while 15% is in the form of hot gas permeating the Intra Cluster Medium (ICM). It is believed that a relativistic population of protons have been accumulated through the formation history of the galaxy clusters. This component should interact with ambient protons...
Using data from the LHAASO-WCDA detector, an analysis can be conducted to investigate the presence of signals in the gamma-ray energy range from non-repeating fast radio bursts. The focus of the study is to estimate the significance and flux upper limits of gamma rays in the sky regions near the source during a certain time period after the FRB detection. This analysis filters the raw event...
HESS J1943+213 is an unidentified TeV gamma-ray source whose nature remains ambiguous, with the two leading interpretations being a high-frequency-peaked BL Lacertae (HBL) object or a pulsar wind nebula (PWN). This dichotomy is underscored by several unusual and conflicting observed characteristics, each of which selectively supports one scenario over the other. Resolving this identity is...
LHAASO-WCDA is a large water Cherenkov detector array located at a high altitude. It features all-weather capability, a wide field of view, and high sensitivity, offering unique advantages for the detection and long-term monitoring of extragalactic blazars. In this work, we will utilize observational data from LHAASO-WCDA to study the very-high-energy gamma-ray emission characteristics of the...
Based on current observations, the main conclusion derived from applying the single-zone conical jet synchrotron self-Compton model to the data is that this model requires a critically low magnetization, which is insonsistent with radio observations of nearby radio galaxies. Therefore, with the current dataset, we cannot favor or disfavor any of the considered models. Probing fast variability...
Using the publicly available observational data from the LHAASO, we conducted a detailed study of the gamma-ray emission properties of the source 1858+0330 in the TeV energy range. The analysis jointly utilized full-array observational data from the Water Cherenkov Detector Array (WCDA, using the Cod version data covering 1–25 TeV and divided into 7 energy bins) and the Kilometer Square Array...
Based on experimental data from the Large High Altitude Air Shower Observatory (LHAASO), this study compares the lateral distributions of electromagnetic particles and muons in Extensive Air Showers (EAS) and tests the accuracy of three hadronic- interaction models—QGSJETII-04, EPOS-LHC, and SIBYLL2.3d. The LHAASO-KM2A array, located at 4410 m above sea level, exhibits excellent detection...
Measurement of cosmic-ray component spectra with KM2A can be explored through template fitting as a practical route to studying the mass evolution of Galactic cosmic rays around the knee. In this work, the relative contributions of different mass groups are inferred by fitting the distribution of the muon-to-electromagnetic shower ratio in reconstructed-energy bins with a Markov Chain Monte...
J0956+4622 is a high-latitude ultra-high-energy gamma-ray source observed by LHAASO, and its physical interpretation requires a robust control of analysis systematics. In this work, we present a unified systematic-uncertainty study developed along our source-analysis chain, rather than focusing on a single effect. The study includes atmospheric effects (especially pressure-related variations),...
Due to large statistical fluctuations in low-energy events, different selection criteria are adopted to optimize the event sample. Furthermore, based on the correlation between electromagnetic particles and muon components, we optimize the composition-insensitive energy reconstruction variable $N_{e\mu}$. In this work, we develop a low-energy cosmic-ray energy reconstruction method with weak...
With its expansive field-of-view and nearly 100% duty cycle, the LHAASO Water Cherenkov Detector Array (WCDA) is uniquely positioned to monitor Very-High-Energy (VHE) emissions from transient and variable sources, including Gamma-Ray Bursts (GRBs), Active Galactic Nuclei (AGNs), and galactic sources such as pulsars and novae. However, many of these targets remain elusive due to limited...
The camera of an atmospheric Cherenkov telescope measures the intensity and profile of Cherenkov light that reaches the focal plane via reflective mirrors. As a key instrument for measuring Cherenkov light at the focal plane in WFCTA observations, the SiPM camera can operate normally under moonlight conditions; however, moonlight introduces significant fluctuations in night-sky background...
I will give a review on the recent results of new physics research at LHAASO and give a brief introduction about the present activities and future plans about new physics study at LHAASO.
15 min is enough for the talk.
The region surrounding the Galactic Center (GC) is one of the richest and most promising targets for the indirect detection of dark matter. Using large-zenith-angle KM2A data, we search for annihilating dark matter in the mass range 10 TeV–1 EeV. We derive the strongest constraints to date on the velocity-weighted annihilation cross section around 100 TeV, improving existing limits from dwarf...
Indirect detection is a prominent approach in the search for dark matter. We investigate gamma-ray signals from heavy dark matter decay and annihilation using 1438 days of KM2A and 1484 days of WCDA data from the LHAASO observatory. To reduce the astrophysical background, we mask the Galactic plane and perform a likelihood analysis over the full LHAASO field of view to search for dark matter...
Extensive air showers induced by ultra-relativistic magnetic monopoles are expected to exhibit a pronounced deficit of muons compared to standard cosmic-ray events. We exploit this distinctive phenomenological signature to search for monopoles using 4 years of observational data from the LHAASO-KM2A array. By capitalizing on the array's dense, overlapping coverage of electromagnetic and muon...
I will report the EP-FXT results of a few LHAASO sources on behalf of the LHAASO-FXT team.
Here we report our preliminary X-ray observations of the Microquasar V4641 Sgr. No eveident X-ray emissions are detected from this binary, but faint diffuse X-ray emissions are discovered spatially coincident with the $\gamma$-ray source in the north. We will discuss the physical origin of this diffuse X-ray structure including a PWN or an extended jet like SS 433. With a broadband SED...
Standard data analysis at LHAASO typically employs a zenith angle cutoff of $< 50^{\circ}$, a constraint that excludes the scientifically rich Galactic Center (GC) region. Key targets within this region, such as the supermassive black hole Sgr A*, the Central Molecular Zone (CMZ), and the supernova remnant G0.9+0.1, are only observable at zenith angles exceeding $58^{\circ}$, where standard...
Energy reconstruction of cosmic rays at large zenith angles
Due to the difficulty of traditional high-energy particle detectors in simultaneously achieving large effective area and sub-microsecond time resolution, direct experimental evidence for the spatiotemporal evolution characteristics of high-energy radiation during lightning leader processes has long been lacking. The Large High-Altitude Air Shower Observatory (LHAASO) is located in Daocheng,...
Large Array of imaging atmospheric Cherenkov Telescope (LACT) is an array of 32 Cherenkov telescopes with 6-meter diameter mirrors to be constructed at the LHAASO site, aiming to enhance our understanding of ultra-high energy gamma ray astronomy. This work presents a detailed performance assessment of the LACT array, focusing on the IRFs for both an 8-telescope subarray configuration optimized...
The EN detector is a novel instrument specifically designed for measuring cosmic ray energy spectra in the knee region. By detecting the abundant thermal neutron components generated from hadron interactions with terrestrial media, it functions as a hadron energy meter to enable more accurate estimation of cosmic ray energy and composition. Thermal neutron capture efficiency serves as a...
ENDA-64 keeps on running and taking data at the LHAASO site. We annalyzed the data about one year without the wet season in 2025. Energy is determined, independent on composition, with electrons, muons and thermal neutrons by using coincident events between ENDA and KM2A. All particle energy spectrum of cosmic ray around the knee region is upgraded. It is the first time to study cosmic ray...
The phenomenon of the incident angle theta of cosmic rays decreasing during thunderstorms has been observed in many cosmic ray experiments. This paper adopts a two-dimensional projection method and uses continuous comparison to demonstrate the changes in the incident direction of cosmic ray events during thunderstorms on a two-dimensional scale. It is hypothesized that the incident direction...
Abstract: As a next-generation imaging atmospheric Cherenkov telescope array, the mirror of LACT (Large Array of imaging atmospheric Cherenkov Telescope) serves as the core component of its optical system and is critical to achieving the desired technical performance. This report elaborates on the installation and alignment of the LACT mirror. For the Davies-Cotton structured mirror array, an...
1LHAASO J1902+0648 is associated with the GeV source 4FGL J1902.5+0654, which is believed to be a binary. We carried out detailed LHAASO data analysis on 1LHAASO J1902+0648 and explored the origin of UHE emission.
The Extragalactic Background Light (EBL) comprises diffuse ultraviolet, optical, and infrared photons emitted by all galaxies since the birth of the universe. It leaves a distinct imprint on observations in the TeV energy range through the electron-positron pair production effect. In this study, leveraging LHAASO's robust capabilities—including all-day operation, a wide field of view, and high...
