arXiv subjects

Ze-Jun Jiang

Publications and source records attributed to Ze-Jun Jiang.

4 recordsLinked to original sources

arXiv2026

Timing and Spectral Studies of PSR J2022+3842 with NICER and NuSTAR

We report on the long-term timing analysis of PSR J2022+3842 using observations from the Neutron Star Interior Composition Explorer (NICER), along with spectral properties derived from joint observations with NICER and the Nuclear Spectroscopic Telescope Array (NuSTAR). Two large glitches are identified around MJD 58335 with $\Delta\nu=25.35(2)\times10^{-6}$ Hz and MJD 58875 with $\Delta\nu=52.078(6)\times10^{-6}$ Hz. Furthermore, phase-resolved spectroscopy reveals that the X-ray emission is well described by a power-law model across different phase intervals. The phase-integrated X-ray spectrum (1-79 keV) has a photon index of $\Gamma=1.22(7)$, yielding an unabsorbed 0.5-10 keV flux of $8.9(6)\times10^{-13}$ erg cm$^{-2}$ s$^{-1}$. The main pulse spectrum (1.2-79 keV) and the inter-pulse spectrum (1-70 keV) are harder with $\Gamma=1.17(4)$ and $\Gamma=1.03^{+0.07}_{-0.06}$ separately, producing an unabsorbed 0.5-10 keV flux of $33.2(2)\times10^{-13}$ erg cm$^{-2}$ s$^{-1}$ and $29(3)\times10^{-13}$ erg cm$^{-2}$ s$^{-1}$. Investigation of the pulse profile evolution with time shows that no significant variations were observed.

astro-ph.HE↗

arXiv2025

Broad-band noises in GX 339-4 during the 2021 outburst observed with Insight-HXMT and NICER

Rapid X-ray variability of GX 339$-$4 including the low-frequency quasi-periodic oscillations (LFQPOs) and broad-band noises have been observed with the Hard X-ray Modulation Telescope (\textit{Insight}-HXMT) and Neutron star Interior Composition Explorer (\textit {NICER}) during the 2021 outburst. Here we present a systematic study of the evolution and energy dependence properties of such broad-band noises (BBN). The outburst from February to March of 2021 can be divided into three stages: the low hard state (LHS), the hard intermediate state (HIMS) and soft intermediate state (SIMS). In the PDSs of the LHS and HIMS, the broad-band noises are well fitted with three Lorentzian components: a low-frequency component $L_1$, a middle-frequency component $L_2$ and a high-frequency component $L_3$. The increasing trend of the characteristic frequencies for $L_1$ and $L_2$ and the relation between the QPO frequency and characteristic BBN frequency are reported. We found that the energies corresponding to the peaks and shapes of the rms spectra for three BBN components are different. The comparison among three BBN components indicates that energy-dominant bands of these BBN components are distinct. Our results can be explained with the truncated disc/hot flow model with a large variable disc and a small hot inner flow. A possible description of the accretion structure and its evolution from the LHS to the SIMS is proposed. Further research is still required to probe such accretion structure in GX 339--4.

astro-ph.HE↗

arXiv2021

Fermi-LAT detection of GeV $γ$-ray emission from Type Ia supernova remnant G272.2-3.2

A new $γ$-ray source with a significance level of approximately 5$σ$ was reported in the region of SNR G272.2-3.2, analysing the approximately 12.4 years of observation data from the Fermi Large Area Telescope (Fermi-LAT). Its $γ$-ray spatial distribution did not show extended feature, and it had a soft spectrum with the spectral index of 2.56$\pm$0.01 of a power-law model. No significant variability of its light curve (LC) with 10 time bins was identified, and its spatial positions in the X-ray and GeV bands overlapped. We suggest that the new $γ$-ray source is a likely counterpart of SNR G272.2-3.2. Analysing its spectrum, we discussed the likely origins of the $γ$-ray emission.

astro-ph.HE↗

arXiv2017

A possible explanation of the knee of cosmic light component spectrum from 100 TeV to 3 PeV

The mixed Hydrogen and Helium (H + He) spectrum with a clear steepening at $\sim 700$ TeV has been detected by ARGO-YBJ experiments. In this paper, we demonstrate that the observed H + He spectrum can be well reproduced with the model of cosmic rays escaping from the supernova remnants (SNRs) in our Galaxy. In this model, particles are accelerated in a SNR through a non-linear diffusive shock acceleration mechanism and three components of high energy light nuclei escaped from the SNR are considered. It should be noted that the proton spectrum observed by KASCADE can be also explained by this model given a higher acceleration efficiency.

astro-ph.HE↗