arXiv subjects

Quangui Gao

Publications and source records attributed to Quangui Gao.

8 recordsLinked to original sources

arXiv2026

Revisiting Very High Energy Gamma-Ray Absorption in Cosmic Propagation under the Combined Effects of Axion-Like Particles and Lorentz Invariance Violation

Very-high-energy (VHE; $E \gtrsim 100$ GeV) gamma rays are expected to experience strong attenuation during cosmological propagation due to electron-positron pair production on the extragalactic background light (EBL). Recent observations of GRB 221009A (z = 0.151), including photons up to $\sim 18$ detected by LHAASO and a $\sim 300\ \mathrm{TeV}$ event reported by Carpet-3, suggest a higher-than-expected transparency of the Universe at extreme energies. These observations cannot be explained by standard EBL absorption alone; moreover, neither Lorentz invariance violation (LIV) nor photon-axion-like particle (ALP) oscillations, when considered in isolation, appear sufficient to account for the survival of such photons over cosmological distances. In this work, we propose a joint propagation scenario that incorporates photon-ALP mixing in astrophysical magnetic fields together with subluminal quadratic LIV corrections to the $γγ$ pair-production threshold. Applying this framework to the broadband gamma-ray spectrum of GRB 221009A, we show that ALPs with coupling ($g_{aγ} = 1.685 \times 10^{-10}\mathrm{GeV}^{-1}$ ) and mass ($m_a = 9.545 \times 10^{-8}\mathrm{eV}$), combined with a quadratic LIV energy scale ($E_{\rm LIV,2} = 1.30 \times 10^{-7} E_{\rm Pl}$) adopted from the literature, can significantly enhance the photon survival probability in the energy range (10\text{-}300) TeV. The resulting enhancement exceeds that obtained from either ALP mixing or LIV effects alone. These results indicate that a combined ALP-LIV scenario may provide a viable interpretation of the extreme-energy gamma-ray observations of GRB 221009A and highlight the potential of VHE gamma-ray measurements as probes of physics beyond the Standard Model.

astro-ph.HE↗

arXiv2024

The fundamental plane of blazars based on the black hole spin-mass energy

We examine the fundamental plane of 91 Blazars which include FSRQs and BL Lacs with known X-ray luminosity ($L_{R}$), radio luminosity ($L_X$), and black hole mass measurements ($M$) to reflect the relationship between jet and accretion for blazars. The fundamental plane of Blazars are log$L_{R}$=${0.273}_{+0.059}^{-0.059}$log$L_X$+${0.695}_{+0.191}^{-0.191}$log$M$+${25.457}_{+2.728}^{-2.728}$ and log$L_{R}$=${0.190}_{+0.049}^{-0.049}$log$L_X$+${0.475}_{+0.157}^{-0.157}$log$M$+${28.568}_{+2.245}^{-2.245}$ after considering the effect of beam factor. Our results suggest that the jet of blazars has connection with accretion. We set the black hole spin energy as a new variable to correct the black hole mass and explore the effect of black hole spin on the fundamental relationship. We find that the fundamental plane of Blazars is effected by the black hole spin, which is similar to the previous work for AGNs. We additionally examine a new fundamental plane which is based on the black hole spin-mass energy ($M_{spin}$). The new fundamental plane (log$L_{R}$=${0.332}_{+0.081}^{-0.081}$log$L_X$+${0.502}_{+0.091}^{-0.091}$log$M_{spin}$+${22.606}_{+3.346}^{-3.346}$ with R-Square=0.575) shows that $M_{spin}$ has a better correlation coefficient comparing to the $M$ for fundamental plane of Blazars. These results support that the black hole spin should be considered as a important factor for the study of fundamental plane for Blazars. And these may further our understanding of the Blandford-Znajek process in blazars.

astro-ph.HE↗

arXiv2023

Production of exotic electromagnetic bound systems in ultra-peripheral heavy ion collisions with two-photon processes

We calculate the production of exotic electromagnetic bound systems, which ia an consisting of a ($l^{+}l^{-}$) bound state system such as positronium, dimuonium, and ditauonium, by photon-photon interaction with the equivalent photon approximation in ultra-peripheral heavy ion collisions considering the nuclear form factor. The numerical results demonstrate that the experimental study of positronium, dimuonium, and ditauonium in ultra-peripheral collisions is feasible at Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) energies.

hep-ph↗

arXiv2023

Constraints on Extragalactic Background Light using TeV Observations of BL Lacertae objects

The extragalactic background light (EBL) in the IR to UV bands partly absorbs very high energy (VHE, $E \geq$ 100GeV) $γ-$ray photons travelling over cosmological distances via pair production. In this paper, to get stronger constraints on EBL, we use the deliberate selection of the EBL model and data of five BL Lacs with better statistics and the harder spectra to limit the EBL density and the radiation mechanism of BL Lacs. We constrain the upper limit of the EBL density by fitting the spectral energy distributions (SEDs) of TeV BL Lacs and find that our results are compatible with the published measurement, reaching 50 $\rm{nW m^{-2} sr^{-1}}$. We also obtain that the EBL is not necessarily transparent to high VHE photons. We fix the intrinsic spectral index $Γ_i$ of TeV BL Lacs as 1.0 and 1.5 under observation evidence and model assumption. Comparing the EBL density given by galaxy count and $Spitzer$ observations, we then obtain that 1ES 1101-232 has $Γ_i$ $\leq$ 1.0 and 1ES 0229+200 should have $Γ_i$ not harder than 1.0. We demonstrate that the common radiation assumption of BL Lacs, in which the $Γ_i$ is softer than 1.5, should be revisited. Furthermore, we propose that the upper EBL density could be given by fitting the hardest energy spectra of TeV BL Lacs.

astro-ph.HE↗

arXiv2022

Production of $χ_{c}$ and $η_{c}$ production in ultra-peripheral collisions with two-photon processes

We calculate the production of $χ_{c}$ and $η_{c}$ by the semi-coherent and coherent two-photon interaction in ultra-peripheral heavy ion collisions at Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) energies. The differential cross section of transverse momentum distribution and rapidity distribution for $AB\stackrel{γγ}{\longrightarrow}AHB$ (H=$χ_{c}$ and $η_{c}$), are estimated by using the equivalent photon approximation in ultra-peripheral nucleus-nucleus collisions. The numerical results demonstrate that the experimental study of $χ_{c}$ and $η_{c}$ in ultra-peripheral nucleus-nucleus collisions is feasible at RHIC and LHC energies.

hep-ph↗

arXiv2022

Compton scattering for photon and gluon in fixed-target collisions at AFTER@LHC

We calculate the Compton scattering for photon and gluon with the Klein-Nishina formula in fixed-target collisions by using the proton and lead beams at AFTER@LHC. In these collisions, we can investigate the particular case of Compton scattering at the partonic level, such as $γq\rightarrow qγ$, $γq\rightarrow qg$, $gq\rightarrow qγ$, and $gq\rightarrow qg$, that can help to check of the equivalent-photon approximation and understand the dynamics of hadron collisions at high energies, as well as probe the inner hadron structure.

hep-ph↗

arXiv2021

Coherent photoproduction of low-$p_{T}$ charmonium in peripheral heavy ion collisions within the color dipole model

We calculate the centrality dependence for coherent photoproduction of very low-$p_{T}$ $J/ψ$ at Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) energies within the impact parameter dependent saturated color dipole model. By using the large equivalent photon fluxes, we present the differential cross section of very low-$p_{T}$ $J/ψ$ produced by coherent photonuclear in peripheral heavy-ion collisions. The numerical results demonstrate that our calculation are agree with $J/ψ$ data in peripheral heavy ion collisions at Relativistic Heavy Ion Collider (RHIC) energies.

hep-ph↗

arXiv2020

Studies of Extragalactic Background Light with TeV BL Lac Objects

Very high energy (VHE; $E \geq$ 100GeV) $γ-$ray from cosmological distances are attenuated by the extragalactic background light (EBL) in the IR to UV band. By contrasting measured versus intrinsic emission, the EBL photon density can be derived. However, neither the intrinsic spectra nor the EBL is separately known~-~except their combined effect. Here we first present a flexible model-dependent optical depth method to study EBL by fitting the emission spectra of TeV BL Lacs objects via a one-zone leptonic synchrotron self-Compton model (SSC). We have little information about electron energy distributions (EEDs) in the jet, which is critically important to build spectral energy distributions (SEDs) in SSC scenario. Based on the current particle acceleration models, we use two types of EEDs, i,e., a power-law log-parabola (PLLP) EED and a broken power-law (BPL) EED to fit the observed spectra. We obtain that the upper limits of EBL density are around about 30 n W m$^{-2}$ sr$^{-1}$, which are similar to the published measurement. Furthermore, we propose an unprecedented method to test radiation mechanisms involved in TeV objects by simply comparing the reduced EBL density with the limit obtained by galaxy counts, and demonstrate that for some BL Lacs, at least, the one-zone SSC model should be reconsidered.

astro-ph.HE↗