Cosmic-rays (CRs) have been recognized to play an important role in the galactic ecosystem through CR feedback. The key underlying microphysics lie in the CR gyro-resonant instabilities, which trigger the growth of Alfv’en waves that lead to energy and momentum exchange between the CRs and the background plasmas, as well as CR self-confinement. I will present simulations of the CR...
In the last decade several Young Star Clusters have been associated to diffuse gamma-ray sources both in the GeV and TeV energy ranges. The origin of such emission is still debated, however hadronic processes due to interaction between gas and locally accelerated cosmic rays seems to be favored at least in some cases. The acceleration mechanism is probably related to powerful stellar winds...
Unveiling the origin of the cosmic-ray (CR) flux observed at Earth remains among the main challenges in the field of astroparcle physics. The Galactic CR component is believed to be produced bysupernova remnants (SNRs) as a result of diffusive shock acceleration, though the acvity of this class of sources in the knee region is yet to be proven. In this context, the process through which...
Molecular clouds are the cold and dense part (n ≥ 10^2 cm-3) of hierarchical interstellar medium concentrated toward the Galactic disk. A number of wide-field surveys in molecular lines have been made to investigate the gas distribution and physical processes. Significant progresses have been made over the last 50 years. However, further improvement of our understanding of interstellar...
Einstein Probe (EP) is an upcoming space mission dedicated to the detection and characterization of high-energy transients. It will carry one wide-field lobster-eye X-ray telescope to monitor the soft X-ray sky in 0.5-4 keV with a 3600 square-degree FoV, and a narrow-field X-ray telescope in 0.3-10 keV for deep follow-up observations and precise source locating. Transient alerts can be issued...
The ASTRI program was launched 10 years ago with the goal of developing small-sized dual-mirror aplanatic wide-field IACT telescopes as a precursor to the array of small-sized telescopes (SSTs) for the Cherenkov Telescope Array (CTA) observatory's southern site. The program initially received support from INAF and MUR (the Italian Ministry for Universities and Research), but it later gained...
ASTRI is a 4 m class Imaging Atmospheric Cherenkov Telescope (IACT) devoted to the observation of gamma sources in the TeV emission band. The telescope implements an innovative optical design based on the dual-mirror Schwartzchild –Couder (SC) configuration. The SC configuration was proposed at the beginning of 1900 as an aplanatic configuration capable of reducing off-axis angular resolution...
Currently, the bulk of Galactic VHE sources are associated with isolated, rotation powered neutron stars (i.e. pulsars). However, how pulsars produce such sources is poorly understood. Answering this question requires understanding the evolution of the pulsar wind nebulae (PWN) produced by the neutron star -- where particles are believed to be accelerated to the required PeV energies and...
The microquasar system SS 433 provides a unique opportunity to study mildly relativistic collimated jets in our own Galaxy. From its core, a binary system hosting a stellar-mass black hole, two persistent, semi-relativistic jets are launched, almost perpendicular to the line of sight. X-ray observations reveal that these jets extend out to around 100 pc on either side of the central system,...
Recently LHAASO measured diffuse gamma-ray background from Milky Way in inner and outer Galaxy. In this talk I’ll discuss how combining this information with Fermi LAT gamma-ray,
IceCube neutrino and cosmic ray data we can constrain models
of cosmic ray propagation in Galaxy.
Winds and outflows are ubiquitous at several scales throughout the Cosmos.They often develop a bubble structure characterized by strong shocks and turbulence where high-energy particles can be efficiently produced.
I will present a model in which diffusive shock acceleration is a
key process to energize particles in such astrophysical winds.
I will show some model applications in the...
The emission of GRB 221009A beyond 10 TeV has been detected by LHAASO. We suggest jitter radiation as a possible explanation for the TeV emission of this energetic GRB. We first present a short review on both synchrotron mechanism and jitter mechanism. We then present the kinetic turbulence that can work on the small length scale. In our scenario, the jitter radiation field is linked to the...
The standard model (SM) of particle physics predicts the resonant scattering of electron anti-neutrinos off the electron target, as first pointed out by Sheldon Glashow. The Glashow resonance is the only feasible way now to distinguish between neutrinos and antineutrinos at ultrahigh energies. Recently, a candidate event with an energy deposition of around 6.05 PeV has been confirmed by the...
We analyzed 12-year Fermi Large Area Telescope gamma-ray data in the inner Galaxy centered at (l=30 degree, b=0 degree) and (l=330 degree, b=0 degree). We found significant hardening of the spectrum of the diffuse gamma-ray emission in these regions as previously reported. We further deduced that the diffuse gamma rays can be divided into two components from the likelihood analysis. One...
We analyzed the notable GRB 221009A using Fermi-GBM data, a gamma-ray burst lasting 600 seconds. The event is divided into three distinct phases: the Precursor, Main, and Tail. The Main phase is further subdivided into Main-1 and Main-2 subphases. During the Main-1 phase, we observed an evolution of the low-energy spectral index, with the index shifting from greater than -2/3 to less than...
Three tidal disruption event (TDE) candidates (AT2019dsg, AT2019fdr, AT2019aalc) have been found to be coincident with high energy astrophysical neutrinos in multi-messenger follow-ups. Recent studies suggest the presence of a quasi-spherical, optically thick envelope around the supermassive black holes in TDEs, resulted from stellar debris after the disruption. The envelope may expand...
Gamma-ray bursts (GRBs) are widely suggested as potential sources of ultrahigh-energy cosmic rays (UHECRs). The kinetic energy of the jets dissipates, leading to the acceleration of protons or nuclei which interact with the intense radiation field of GRBs via the photomeson and Bethe-Heitler processes. These processes initiate a series of electromagnetic cascades, giving rise to a broadband...
Isotopic and elemental abundances seen in Galactic cosmic rays (GCRs) imply that ∼20% of the cosmic-ray (CR) nuclei are probably synthesized by massive Wolf–Rayet (W-R) stars. Massive star clusters hosting W-R- and OBtype stars have been proposed as potential GCR accelerators for decades, in particular via diffusive shock acceleration at wind termination shocks. Here we report the analysis of...
Recently, a series of high-precision measurements by various experiments have revealed a hardening trend in the spectra of cosmic ray nuclei and the boron-to-carbon (B/C) ratio at around 200 GV. These anomalous structures have important implications for our understanding of the origin and propagation of Galactic cosmic rays (GCRs). We investigate several propagation models and verify that an...
Markarian (Mrk) 180 is a BL Lacertae (BL Lac) object located at a redshift of 0.045 and a potential candidate for high-energy cosmic ray acceleration.
We have analyzed the Fermi-LAT gamma-ray data of Mrk 180 collected over a period of 12.8 years. We have also analyzed Swift X-ray, ultraviolet & optical, and XMM-Newton X-ray data to construct the multi-wavelength SED. The SED has been modelled...
In this work we investigate the potential of Pulsar time array study using imaging air Cherenkov telescopes (IACTs). We simulated the detected photons from pulsars using the response of hypothetical low threshold IACTs taking into account of the cosmic ray (CR) backgrounds and timing profile. We then analyzed the timing property of the simulated data in analog to the PTA studies using Fermi...
It is considered that supernova remnant (SNRs) is one of the most possible accelerators of Galactic Cosmic Rays (CRs). For the high-energy observation of SNRs, there are a huge debate about the radiation mechanism and the physical processes. Whether SNRs are the efficiently hadronic accelerators is still a question. The Large High Altitude Air Shower Observatory (LHAASO) is the first great...
Hot accretion flows contain collisionless plasmas under turbulence generated by the magnetorotational instability (MRI), which can be potential source of particle acceleration. We conduct unstratified shearing-box magnetohydrodynamic (MHD) simulations of the MRI turbulence with net vertical magnetic flux, with and without explicit dissipation, and inject relativistic test particles in...
The Large Array of Imaging Atmospheric Cherenkov Telescopes (LACT) is a next-generation IACT array planned to be constructed on the LHAASO sites. With its exceptional angular resolution, it enables precise localization of gamma rays. Moreover, being built on the LHAASO sites, it benefits from remarkable gamma/proton separation capabilities. In this poster, we present some performance results...
Being an important supplement of LHAASO observatory, Large Array of Cherenkov Telescope (LACT) is designed to study the morphology and spectrum of ultra-high energy gamma ray sources observed by LHAASO experiment. Due to the strong sky survey ability for gamma ray sources of LHAASO and the high angular resolution of LACT, the combination of the two experiments will observe the gamma ray...
We report the discovery of an unidentified point-like very-high-energy (VHE) gamma-ray source around the PSR J1740+1000 named LHAASO J1740+0948.
Its significance is $12 \sigma$ ($5.4 \sigma$) above $25 \rm{TeV}$ ($100 \rm{TeV}$) and the best-fit position is $\rm{(R.A., decl)}=(265.01 \pm 0.03, 9.79 \pm 0.04)$. The energy spectrum can be described by a single power-law function with an index of...
The study on the dynamic evolution of young supernova remnants (SNRs) is an important way to understand the density structure of the progenitor’s circumstellar medium. We have reported the acceleration or deceleration,
proper motion, and brightness changes of 260 compact radio features in the second-youngest known SNR Cas A at 5 GHz based on the Very Large Array data of five epochs from 1987...
We study accelerations, energy loss and the escape of cosmic rays in GRB 221009A, and suggest that GRB 221009A is an ultra-high-energy(UHE) cosmic ray source with ability of accelerating protons to $> 10^{20}$ eV. It is difficult for UHE protons to escape from the source and the host galaxy, while neutrons at the energies of tens of EeV, produced in the process of $p+\gamma \rightarrow...
