Up to now, the LHAASO collaboration have signed ten Memorandum of Understandings (MoUs), including seven international ones and three domestic ones, with the other collaborations on joint analysis. The facilities of The joint collaborations include ground radio, gamma ray, neutrino telescopes and observatories on satelites, so that the joint field covers multi-waveband astronomy and...
Based on the results of SNR G150.3+4.5 at the 38th International Cosmic Ray Conference (ICRC2023), we updated several main results: (1) Using the updated data, we obtained two Gaussian distributions, which basically corresponded to the energy segments of WCDA and KM2A by conjoint analyzing WCDA and KM2A data; (2) Using CO data from the Milky Way Imaging Scroll Painting survey (MWISP), it is...
It is difficult to identify hadronic PeVatrons (the PeV particle accelerator) from the ultra-high-energy (UHE, E>100TeV) gamma-ray sources, which is however crucial in revealing the origin of cosmic rays. As an endeavor in this regard, we focus in this work on the UHE gamma-ray source 1LHAASO J1857+0203u, which may associate with the supernova remnant (SNR) G35.6−0.4 and H II region G35.6−0.5....
Identification of cosmic-ray (CR) accelerators, especially those that can accelerate protons up to PeV regime (namely, PeVatrons), is one of major goals of high-energy astrophysics and plays a crucial role in understanding the origin of Galactic CRs. In this contribution, we report the LHAASO obsesrvation on an intriguing SNR-PWN complex consisting of the famous PeVatron candidate SNR...
Under Chinese-Russian cooperation, electron-neutron detector array (ENDA) makes progresses during the last half an year: ENDA has been extended from ENDA-16 to ENDA-64, covering area about 1000 m2. ENDA-64 is running smoothingly and sand cubes are being added into one cluster (16 detectors). In 2023, we got supports from both NSFC Major International Joint Research Project and NSFC General...
The temporal and spatial structure of an EAS front detected at ground level reflects the nature of the primary particle and its interactions with atmosphere nuclei. We give the experiment results of the temporal structure of the shower front of the electronic and muonic EAS components, observed to larger distances from the shower axis up to core distances of R = 500m at the maximum depth of...
This presentation will talk about the status of lhaaso computing platform in 2023.
In this presentation we report the very-high-energy (VHE) to ultra-high-energy (UHE) \gray emission detected by the Large High Altitude Air Shower Observation (LHAASO), from the direction toward the young star-forming region W43. The extended \gray source is detected with a significance of ${\sim}23\,\sigma$ with KM2A and a significance of ${\sim}27\,\sigma$ with WCDA. The angular extension of...
Understanding the origin of the knee in terms of the energy spectrum is often considered fundamental for determining the origin of cosmic rays. The kilometer-square array (KM2A) of the Large High Altitude Air Shower Observatory (LHAASO) simultaneously measures air shower sizes of both electromagnetic particles and muons with high precision at 4410 m a.s.l. where cosmic ray air showers with...
In recent years, the hardening of Cosmic Rays spectra above a few hundred GV and softening around 10TV received much attention. These features of observation may provide insights into the potential origins of nearby sources. Measurements of the anisotropy of light nuclei will provide compelling evidence supporting the existence of nearby sources. In this work, PINCness is used to identify...
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. One of the main scientific goals of Large High Altitude Air Shower Observatory (LHAASO) is measuring the cosmic ray energy spectra and...
Propagating individual cosmic rays in synthetic three-dimensional Kolmogorov turbulence, we calculate their anisotropy at the location of an observer. These are the first calculations of the cosmic ray anisotropy down to TeV energies for values of the turbulence coherence length that are realistic for the interstellar medium. We calculate the power spectrum 𝐶𝑙, of the cosmic ray anisotropy for...
We show that a large asymmetric halo may be misidentified as multiple "mirage" sources, and that asymmetric diffusion could lead to a very large offset between the injection site and the identified halo. We add background noise into the region and try to identify the sources. We utilize the concept of asymmetric diffusion to elucidate several observed sources that were previously challenging...
The origin of the knee in the cosmic ray (CR) spectrum is still unknown after 65 years of studies. Here, within the framework of anisotropic CR diffusion models, we show that the knee is a time-dependent feature, and that the flux in this region contains major contributions from one or a few nearby recent CR sources. We calculate the propagation of CRs in the Jansson-Farrar galactic magnetic...
Due to significant improvements in observatory sensitivity, numerous halo-like sources have been identified. It appears that TeV halos commonly exist around powerful middle-aged pulsars. In this study, we present an observation of 1LHAASO J0359+5406 conducted by LHAASO. By applying a mask to the region above 1LHAASO J0359+5406, our fitting results reveal that it is an extended source with an...
Recent LHAASO observations of the prompt emission phase of the brightest-of-all-time GRB 221009A imposes a stringent limit on the flux ratio between the TeV and MeV emissions, $F_{\rm TeV}/F_{\rm MeV}\le 2\times10^{-5}$, during the period $220 - 230\, {\rm s}$ after the trigger. This period covers the peak of the main MeV burst and is just before the TeV afterglow emerges. Within the...
LHAASO KM2A and WCDA are two detectors used to detect gamma rays for different energy range: greater than 10 TeV for KM2A and less than 10 TeV for WCDA. These detectors can be utilized for searching for dark matter. Decaying dark matter and annihilating dark matter can potentially result in a gamma ray excess compared to the background. In our study, we first performed data analysis to...
The gamma-ray spectral indexes of SNRs have a bimodal distribution. It has been suggested that the hard gamma-ray spectrum is produced via the inverse Comptonization processes of high-energy electrons in a low-density environment while the soft gamma-ray spectrum is dominated by pion decays produced via inelastic hadronic collisions in a high density region, the so-called leptonic and hadronic...
LHAASO J2032 is an ultra-high-energy extended gamma-ray source, one of the twelve first reported by LHAASO in 2021. It is potentially linked to the gamma-ray binary system J2032+4127. With four years data from the LHAASO, we have now resolved two distinct components within this source. The first is a compact source situated close to the binary system, exhibiting an exceptionally hard...
The Southern Wide-field Gamma-ray Observatory (SWGO) is a proposed next-generation gamma-ray survey experiment that will cover the southern sky with high sensitivity and a wide field of view. It will be built in South America to complement HAWC and LHAASO in the Northern Hemisphere. We designed a lake array proposal for SWGO to record particles from extensive air showers initiated by high...
G25 region is a complex region with various objects which can accelerate CRs. G24.7+0.6 is a filled-center SNR with an age of ~9500 yr. G25.18+0.26 is an OB association with massive stars. TeV source MAGIC J1835-069 is located between the two objects. RSGC1, one of the most massive star clusters, contains more than 200 massive stars located in the G25 region.There also exist two X-ray PWN...
The origin of Galactic PeV cosmic rays is still under debate. Shell-type supernova remnants (SNRs) are proposed to be one of the candidate sources of Galactic PeV cosmic rays, but observational evidence is lacking. Here we report LHAASO’s detection on a point source J2002+3238 with a significance of 5.8 sigma above 25 TeV and 6.8 sigma above 100 TeV. The spectrum is consistent with a power-law...
LHAASO J1959+1128 is a newly discovered gamma-ray source by LHAASO, which is spatially associated with a low mass binary 4U 1957+11, we carried out a detailed study of LHAASO J1959+1128 by analyzing LHAASO KM2A,
We studied some topological variables used in proton/gamma identification and tested how much they improve R-cut results.
Thanks to the huge effective area and strong composition discrimination of KM2A, the moon shadow cuased by the heavy cosmic ray nuclei have been observated with -14sigma by using 2022, 2023 KM2A data in the energy range about 50TeV. The westward shift of the shadow is about 0.4 degree, while the shift in the north-south direction is about 0.06 degree. In this poster, the details including the...
Galactic Ridge is brightest central part of Milky Way Galaxy with $|l|<30^\circ$.
It was detected by Fermi LAT in gamma-rays up to 3 TeV. Recently it was detected by ANTARES and IceCube in neutrinos. Here we study flux of Galactic Ridge in LHAASO km2a data.
We show that the total flux measured by LHAASO km2a above 10 TeV lies exactly at the extrapolation of the Fermi/LAT Galactic Ridge...
ith its large effective area and good time resolution, LHAASO provides a valuable opportunity to study thunderstorm-related high-energy atmospheric phenomena. By analyzing LHAASO-KM2A data and atmospheric electric fields, we observe an increase in particle numbers during thunderstorms caused by thunderstorm ground enhancements (TGEs). Nearly at the same time when some of the TGEs are...
Interplanetary coronal mass ejections (ICMEs) are known to affect the intensity and large-scale anisotropy of Galactic cosmic rays of energies up to ∼100 GeV, but such effects at higher energies have never been reported. Here we analyze data from LHAASO-WCDA since its full operation began in March 2021. We select events within 45 degrees of the zenith and normalize cosmic ray skymaps at each...
Since the completion and operation of the LHASSO-WCDA array, there has been a phenomenon of short-term abnormal decrease in counting rate followed by recovery. After analyzing monitoring data such as temperature, air pressure, and atmospheric electric field, it was finally determined to be related to the drastic changes in the atmospheric electric field during thunderstorms. By analyzing the...
Electrons and positrons escaping from pulasar wind nebulae (PENe) generated an extended gamma-ray structures and considered as a new class of gamma-ray sources - pulsar halo. We report the detection of an extended very-high-energy (VHE) gamma-ray source coincident with the locations of middle-aged (62.4 kyr) PSR J0248+6021, by using the LHAASO-WCDA data of live 784 days and LHAASO-KM2A data of...
microquasars have been proposed to be able to accelerate hadrons and contribute to Galactic cosmic rays. SS 433 is a canonical microquasar containing the most energetic jet in our Galaxy. It locates at a distance of about $4.6~\rm kpc$ from the earth and contains a compact objects, most likely a black hole of $10 - 20 M_{\odot}$ which is accreting from a massive A3-7 star at a rate of about...
Extended TeV sources associated with pulsars can be divide into two categories: pulsar wind nebula with TeV emission originating in the zone dominated by the pulsar; TeV halo with escaped particle diffusing into the ISM. The First LHAASO Catalog of Gamma-ray Sources found 35 sources with pulsar association. Based on it, we unveil the correlation between LHAASO sources and associated pulsars by...
脉冲星通常被认为是高速旋转的中子星，具有强磁场，并向星际空间释放大量正负电子，被认为是轻子宇宙线的主要来源之一。这些正负电子在星际空间中扩散，并通过逆康普顿散射的方式产生高能伽马射线，形成一类尺度很大的天体，称为脉冲星晕。研究脉冲星晕的形态有助于了解银河系内粒子的扩散过程。Geminga是离地球最近、形态最清晰的脉冲星晕，利用它，我们可以更加细致地研究星际空间的扩散过程，包括扩散系数的空间依赖以及随能量的变化等。本报告将介绍利用这一高海拔宇宙线观测站LHAASO对Geminga脉冲星晕的观测进展。
GRB221009A produced fruitful data on WCDA. In WCDA trigger mode (TM), 2000-ns data around the trigger time are packed as raw events. Those raw events will then be processed through the noise filter software, which keeps the 200-ns data around the pre-reconstructed shower front as reduced events. Those data dropped in the noise filter process are a sample of triggerless data, which are clean of...
The wide field of view Cherenkov telescope array (WFCTA) is one part of large high-altitude air shower observatory (LHAASO), its main scientific goal is to detect the single component of the cosmic rays energy spectrum around the knee with other parts of LHAASO. There are 18 telescopes in WFCTA and each telescope consists of 5 square meters sphere reflector which is made of 25 mirror facets....
We make use of a supervised machine-learning algorithm based on Logistic Regression (LR) to select TeV blazar candidates from the 4FGL-DR2/4LAC-DR2, 3FHL, 3HSP, and 2BIGB catalogs. LR constructs a hyperplane based on a selection of optimal parameters, named features, and hyperparameters whose values control the learning process and determine the values of features that a learning algorithm...
We report the discovery of an $\gamma$-ray source in the Galactic plane named LHAASO J1914+1150 with a significance of 10.3$\sigma$ at 2-20 TeV and 12.5$\sigma$ above 25TeV. The best-fit position is R.A. = $288.72^{\circ} \pm 0.3^{\circ}$ and decl. = $11.79^{\circ}\pm 0.03^{\circ}$. Due to the significant diffuse radiation in the Galactic plane, we used a dust template for evaluation. We...
The giant radio galaxy M 87 with its proximity (16 Mpc), famous jet, and very massive black hole ($(3-6)\times10^9 M_{\odot}$) provides a unique opportunity to investigate the origin of very high energy (VHE; E > 0.1 TeV) gamma-ray emission. It has been established as a VHE gamma-ray emitter since 2004. But the origin of the gamma-ray emission from M 87 is currently a matter of debate. Here we...
Here we report observation on SNR G065.1+00.6 region using LHAASO
data. By perfoming likelihood tests, multiple sources overlapping each
other are resolved. Independent fittings have been done by using WCDA
data and KM2A data respectively, and the results are consistent in gen-
eral. In the vicinity of the resolved sources, pulsars or supernova remnants
are present, which are likely...
Micro quasars that are compact binary star systems composed of a stellar-mass black hole or neutron star accreting matter from a companion star exhibit powerful and highly collimated jets of particles and radiation. These micro quasar jets are unique that provide valuable insights into particle acceleration and transport processes under extreme conditions. In this poster, I will present the...
Astrophysical neutrinos have been observed in the TeV to PeV energy range and are expected to be observable at several orders of magnitude higher still. These energetic neutrinos acts as probes of new physics models at energy scale well beyond the center-of-mass energies of current terrestrial experiments. Flavor ratios, and in particular, observations of tau neutrinos are important observable...
The Large High Altitude Air Shower Observatory (LHAASO) has been operating with a zenith cut of 50°, limiting its field of view (FOV) from declination -21° to 79°. However, expanding the FOV to include crucial regions such as the Galactic center for gamma-ray research and providing increased exposure to sources at large zenith angles, such as the Fermi Bubble and gamma-ray binaries like LSI...
T Coronae Borealis (T CrB), located at R.A. = $ 239.88^\circ $, Dec = $ 25.92^\circ $, is a famous recurrent novae, with two recorded fast nova eruptions in 1866 and 1946. In the 1946 eruption, the magnitude of T CrB peaks at $2.0^{\rm m}$, which is the brightest nova event from 1943–2022. Recently, Schaefer (2023)
observed the long-term monitored magnitude had a pre-eruption dip starting...
The interaction between secondary particles from cosmic ray air showers and electric fields in thundercloud is one of the hottest topics in high-energy atmospheric physics. Owing to the large active area and high-altitude location with frequent thunderstorms, LHAASO is suitable to study the correlation between thunderstorms and variations in cosmic rays. Based on the experiment data with...
The Andromeda Galaxy (M31) is a nearby (∼780 kpc) galaxy similar to our own Milky Way. Observational evidence suggests that it resides in a large halo of dark matter (DM), making it a good target for DM searches. We present a search for gamma rays from M31 using data from the LHAASO Observations. With its wide field of view and constant monitoring, LHAASO is well-suited to search for DM in...
Understanding the behavior of cosmic ray electrons is crucial for unraveling fundamental physics questions regarding the origin, acceleration, and propagation of cosmic rays. The theoretical hypothesis of nearby sources naturally explains the bumps observed in the cosmic ray energy spectrum around the hundred TeV range, as well as the reduction in amplitude and phase reversal of anisotropy....
We analyze the LHAASO KM2A data towards dwarf irregular galaxies, aiming to search for possible dark matter annihilation signal in these systems or constrain the dark matter cross section of annihilation if no signal is detected. We focus on the sources that are within the LHAASO's field of view and have largest J-factors.
The LHAASO (Large High Altitude Air Shower Observatory), with wide field of view and high duty cycle, coupled with the strongest detection sensitivity in the TeV-PeV energy range, offers a unique opportunity to unbiased search for and study the transient sources, such as GRBs, AGNs, XB, and other unforeseeable new astronomy phenomena in the universe. In this study, we all sky survey for...
The direct measurements of the proton spectrum show a softening at E ≈ 13 TeV and a similar softening at E ≈ 34.4 TeV on helium spectrum. Whether and where a softening on iron spectrum is very important to study the origin of cosmic rays. LHAASO hybrid observation can select the iron showers with 90% purity. The selection efficiency is 40%. It is expect to complete the measurement of iron...
Mkn501, one of the brightest TeV blazars, is renowned for its significant temporal variability, which has provided valuable constraints for AGN models and contributed to research on the origins of gamma rays.
To further study the energy distribution spectrum (SED) and light curves of Mkn501, we leverage the advantages of the LHAASO-WCDA, which include its all-weather capability, wide field...
The brightest gamma-ray burst, GRB 221009A, has spurred numerous theoretical investigations, with particular attention paid to the origins of ultrahigh-energy TeV photons during the prompt phase. However, analyzing the mechanism of radiation of photons in the ~MeV range has been difficult because the high flux causes pileup and saturation effects in most GRB detectors. In this Letter, we...
We studied the TeV emission toward 1LHAASO J1937+2128. PSRs in the FOV may contribute to parts of VHE in the whole region, while SNR G57.2+0.8 is another candidate of the PeVatrons based on multi-wavelength studies and SED fitting.
The Wide Field-of-view Cherenkov Telescope Array (WFCTA) of Large High Altitude Air Shower Observatory (LHAASO) is designed to perform nearly calorimetric measurements of extensive air showers induced by cosmic rays with energies between 10$^{13}$ eV - 10$^{18}$ eV. In order to achieve an end-to-end calibration of WFCTA and investigate properties of the atmospheric aerosol, five laser systems...
The Fermi bubbles are a pair of enormous gamma-ray-emitting bubbles discovered in 2010 in the inner Galaxy by the Fermi gamma-ray space telescope. In 2020, eROSITA X-ray telescope discovered a pair of even larger bubbles surrounding the Fermi bubbles in the soft X-ray band. The edges of these two bubble pairs may correspond to shock fronts, which could potentially accelerate cosmic ray...
Cosmic rays are high-energy particles originating from outer space. Many experimental studies have found that cosmic rays exist in the energy range from hundreds of GeV to PeV, and there is anisotropy in the intensity of cosmic rays in various directions at the level of one-thousandth. There are numerous theoretical hypotheses regarding the origin of cosmic rays. Studying the anisotropy of...
We first briefly introduce the UHECRs and detection situation, especially with space-based telescopes. In the following, we discusses the theoretical and scientific significance of detection. The fourth part describes the scientific objectives of detection, and finally we provides a theoretical research plan based on LHASSO detection data.
The arrival directions of TeV cosmic rays on the sky display an anisotropy at the 0.1 percent level. This anisotropy contains a dipole and higher order multipoles. Small-scale anisotropies should contain important information about the properties of the turbulent magnetic fields in the interstellar medium. These anisotropies have been predicted to vary on a time-scale of a decade at TeV...
We present our new model for the description of the $\rm{PeV}-\rm{TeV}$ Galactic gamma-ray emission assuming discrete distributions of cosmic-ray sources. Based on this model, we investigate the impact of the discreteness of the locations of the cosmis-ray sources and of the diffusion mechanism responsible for the propagation of cosmic rays on the morphology of the VHE Galactic diffuse...
An indirect measurement of the antiproton flux in cosmic rays is possible as the particles undergo
deflection by the geomagnetic field. This effect can be measured by studying the deficit in the flux,
or shadow, created by the Moon as it absorbs cosmic rays that are headed towards the Earth. The
shadow is displaced from the actual position of the Moon due to geomagnetic deflection, which is...
高斯过程（GP）方法是一类基于概率论和贝叶斯分析技术的统计模型，是一个强大的数据分析方法，可以有效地帮助我们理解数据背后的物理。我们的研究以时域分析为基础，利用 GP 方法对活动星系核（AGN）的长期光变和准周期振荡现象开展了研究，探寻了 AGN 的光变模式和起源。主要内容如下。
AGN 中高能伽马射线长期光变的研究。基于 Fermi-LAT 第四期源表的伽马射线数据，我们选取了 23 个具有高置信度和显著光变的 AGN，将 GP 方法应用于它们 $\sim$ 12.7 年的光变曲线分析中。具体采用了随机驱动的阻尼简单谐振子（SHO）模型和阻尼随机游走（DRW）模型对这些长期光变曲线进行建模。我们发现， SHO 和 DRW 模型都能很好地描述 23 个 AGN 的长期光变，但相比于 DRW 模型， SHO 模型没有明显改善拟合且参数约束较差。这表明， DRW 模型就可以描述...
