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23 results on '"Zhang, S. N"'

1. Temporal and Spectral Analysis of the Unique and Second Brightest Gamma-Ray Burst GRB 230307A: Insights from GECAM and Fermi/GBM Observations

Author

Moradi, R., Wang, C. W., Zhang, B., Wang, Y., Xiong, S. -L., Yi, S. -X., Tan, W. -J., Karlica, M., and Zhang, S. -N.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

In this study, we present the pulse profile of the unique and the second brightest gamma-ray burst GRB 230307A, and analyze its temporal behavior using a joint GECAM--Fermi/GBM time-resolved spectral analysis. The utilization of GECAM data is advantageous as it successfully captured significant data during the pile-up period of the Fermi/GBM. We investigate the evolution of its flux, photon fluence, photon flux, peak energy, and the corresponding hardness-intensity and hardness-flux correlations. The findings within the first 27 seconds exhibit consistent patterns reported previously, providing valuable insights for comparing observations with predictions from the synchrotron radiation model invoking an expanding shell. Beyond the initial 27 seconds, we observe a notable transition in the emitted radiation, attributed to high latitude emission (HLE), influenced by the geometric properties of the shells and the relativistic Doppler effects. By modeling the data within the framework of the large-radius internal shock model, we discuss the required parameters as well as the limitations of the model. We conclude that a more complicated synchrotron emission model is needed to fully describe the observational data of GRB 230307A., Comment: Accepted for publication in The Astrophysical Journal (ApJ)

Published
2024

2. Extragalactic fast X-ray transient from a weak relativistic jet associated with a Type Ic-BL supernova

Author

Sun, H., Li, W. -X., Liu, L. -D., Gao, H., Wang, X. -F., Yuan, W., Zhang, B., Filippenko, A. V., Xu, D., An, T., Ai, S., Brink, T. G., Liu, Y., Liu, Y. -Q., Wang, C. -Y., Wu, Q. -Y., Wu, X. -F., Yang, Y., Zhang, B. -B., Zheng, W. -K., Ahumada, T., Dai, Z. -G., Delaunay, J., Elias-Rosa, N., Benetti, S., Fu, S. -Y., Howell, D. A., Huang, Y. -F., Kasliwal, M. M., Karambelkar, V., Stein, R., Lei, W. -H., Lian, T. -Y., Peng, Z. -K., Ridnaia, A. V., Svinkin, D. S., Wang, X. -Y., Wang, A. -L., Wei, D. -M., An, J., Andrews, M., Bai, J. -M, Dai, C. -Y., Ehgamberdiev, S. A., Fan, Z., Farah, J., Feng, H. -C., Fynbo, J. P. U., Guo, W. -J., Guo, Z., Hu, M. -K., Hu, J. -W., Jiang, S. -Q., Jin, J. -J., Li, A., Li, J. -D., Li, R. -Z., Liang, Y. -F., Ling, Z. -X., Liu, X., Mao, J. -R., McCully, C., Mirzaqulov, D., Newsome, M., Gonzalez, E. Padilla, Pan, X., Terreran, G., Tinyanont, S., Wang, B. -T., Wang, L. -Z., Wen, X. -D., Xiang, D. -F., Xue, S. -J., Yang, J., Zhu, Z. -P., Cai, Z. -M., Castro-Tirado, A. J., Chen, F. -S., Chen, H. -L., Chen, T. -X., Chen, W., Chen, Y. -H., Chen, Y. -F., Chen, Y., Cheng, H. -Q., Cordier, B., Cui, C. -Z., Cui, W. -W., Dai, Y. -F., Fan, D. -W., Feng, H., Guan, J., Han, D. -W., Hou, D. -J., Hu, H. -B., Huang, M. -H., Huo, J., Jia, S. -M., Jia, Z. -Q., Jiang, B. -W., Jin, C. -C., Jin, G., Kuulkers, E., Li, C. -K., Li, D. -Y., Li, J. -F., Li, L. -H., Li, M. -S., Li, W., Li, Z. -D., Liu, C. -Z, Liu, H. -Y., Liu, H. -Q., Liu, M. -J., Lu, F. -J., Luo, L. -D., Ma, J., Mao, X., Nandra, K., O'Brien, P., Pan, H. -W., Rau, A., Rea, N., Sanders, J., Song, L. -M., Sun, S. -L., Sun, X. -J., Tan, Y. -Y., Tang, Q. -J., Tao, Y. -H., Wang, H., Wang, J., Wang, L., Wang, W. -X., Wang, Y. -L., Wang, Y. -S., Xiong, D. -R., Xu, H. -T., Xu, J. -J., Xu, X. -P., Xu, Y. -F., Xu, Z., Xue, C. -B., Xue, Y. -L., Yan, A. -L., Yang, H. -N., Yang, X. -T., Yang, Y. -J., Zhang, C., Zhang, J., Zhang, M., Zhang, S. -N., Zhang, W. -D., Zhang, W. -J., Zhang, Y. -H., Zhang, Z., Zhang, Z. -L., Zhao, D. -H., Zhao, H. -S., Zhao, X. -F., Zhao, Z. -J., Zhou, Y. -L., Zhu, Y. -X., and Zhu, Z. -C.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Massive stars end their life as core-collapse supernovae, amongst which some extremes are Type Ic broad-lined supernovae associated with long-duration gamma-ray bursts (LGRBs) having powerful relativistic jets. Their less-extreme brethren make unsuccessful jets that are choked inside the stars, appearing as X-ray flashes or low-luminosity GRBs. On the other hand, there exists a population of extragalactic fast X-ray transients (EFXTs) with timescales ranging from seconds to thousands of seconds, whose origins remain obscure. Known sources that contribute to the observed EFXT population include the softer analogs of LGRBs, shock breakouts of supernovae, or unsuccessful jets. Here, we report the discovery of the bright X-ray transient EP240414a detected by the Einstein Probe (EP), which is associated with the Type Ic supernova SN 2024gsa at a redshift of 0.401. The X-ray emission evolution is characterised by a very soft energy spectrum peaking at < 1.3 keV, which makes it distinct from known LGRBs, X-ray flashes, or low-luminosity GRBs. Follow-up observations at optical and radio bands revealed the existence of a weak relativistic jet that interacts with an extended shell surrounding the progenitor star. Located on the outskirts of a massive galaxy, this event reveals a new population of explosions of Wolf-Rayet stars characterised by a less powerful engine that drives a successful but weak jet, possibly owing to a progenitor star with a smaller core angular momentum than in traditional LGRB progenitors., Comment: 43 pages, 9 figures, 4 tables, submitted. Comments are welcome

Published
2024

3. estimating the spin of MAXI J1348--630 from intermediate and soft states using \textit{Insight}-HXMT data

Author

Guan, J., Ma, R. C., Tao, L., Fabian, A. C., Tomsick, J. A., Zhang, S. N., Zhang, L., Qu, J. L., and Zhang, S.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We present a broadband spectral analysis of the soft-intermediate and soft states using \textit{Insight}-HXMT observations of the black hole binary MAXI J1348--630 during its outburst in 2019. We employ a combination of reflection and continuum fitting methods to measure the spin of the black hole and determine a spin of $a=0.79\pm0.13$, which is consistent with most of the previous results. Additionally, we investigate some sources of systematic uncertainty that could bias the measurement. The valid spectral hardening factor can partially account for the spin evolution observed during the outburst. Other potential factors, such as assumptions about the corona's structure and their interaction with reflected photons, can also affect the accuracy of spin measurements. Furthermore, our analysis reveals that MAXI J1348--630 exhibits a significantly high disc density ($\sim10^{22}\,\rm{cm}^{-3}$), with a moderate iron abundance of approximately 2.5 times solar., Comment: 10 pages, 6 figures, 3 tables

Published
2024

4. A Revised Spin of the Black Hole in GRS 1716-249 with a New Distance

Author

Zhao, S. J., Tao, L., Yin, Q. Q., Zhang, S. N., Ma, R. C., Li, P. P., Zhao, Q. C., Ge, M. Y., Zhang, L., Qu, J. L., Zhang, S., Ma, X., Huang, Y., Peng, J. Q., and Xiao, Y. X.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

GRS 1716-249 is a stellar-mass black hole in a low-mass X-ray binary that underwent a gaint outburst in 2016/17. In this paper we use simultaneous observations of Insight-HXMT and NuSTAR to determine its basic parameters. The observations were performed during the softest part of the outburst, and the spectra show clear thermal disk emission and reflection features. We have fitted the X-ray energy spectra using the joint fitting method of the continuum and reflection components with the kerrbb2+ relxill model. Since there is a possibility that the distance to this source was previously underestimated, we use the latest distance parameter of 6.9 kpc in our study, in contrast to previous work in which the distance was set at 2.4 kpc. Through spectral fitting of fixing black hole mass at 6.4 $M_{\rm \odot}$, we observe a strong dependence of the derived spin on the distance: $a_{*}=0.972_{-0.005}^{+0.004}$ at an assumed distance of 2.4 kpc and $a_{*}=0.464_{-0.007}^{+0.016}$ at an assumed distance of 6.9 kpc, at a confidence level of 90%. If considering the uncertainties in the distance and black hole mass, there will be a wider range of spin with $a_{*}$ < 0.78. The fitting results with the new distance indicate that GRS 1716-249 harbors a moderate spin black hole with an inclined ($i\sim 40-50^{\circ}$) accretion disk around it. Additionally, we have also found that solely using the method of the reflection component fitting but ignoring the constraints on the spin from the accretion disk component will result in an extremely high spin.

Published
2024

5. Broad-band X-ray spectral and timing properties of the accreting millisecond X-ray pulsar IGR J17498$-$2921 during the 2023 outburst

Author

Li, Zhaosheng, Kuiper, L., Pan, Y. Y., Falanga, M., Poutanen, J., Chen, Y. P., Xu, R. X., Ge, M. Y., Huang, Y., Song, L. M., Zhang, S., Lu, F. J., and Zhang, S. N.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report on the broadband spectral and timing properties of the accreting millisecond X-ray pulsar IGR J17498$-$2921 during its April 2023 outburst using data from NICER (1$-$10 keV), NuSTAR (3$-$79 keV), Insight-HXMT (2$-$150 keV), and INTEGRAL (30$-$150 keV). We detect significant 401 Hz pulsations across the 0.5$-$150 keV band. The pulse fraction increases from $\sim$2% at 1 keV to $\sim$13% at 66 keV. Five type-I X-ray bursts have been detected, including three photospheric radius expansion bursts, with a rise time of $\sim$2 s and an exponential decay time of $\sim$5 s. The recurrence time is $\sim$9.1 h, which can be explained by unstable thermonuclear burning of hydrogen-deficient material on the neutron star surface. The quasi-simultaneous 1$-$150 keV broadband spectra from NICER, NuSTAR, and INTEGRAL can be well fitted by an absorbed reflection model, relxillCp, and a Gaussian line of instrumental origin. The Comptonized emission from the hot corona is characterized by a photon index $\Gamma$ of $\sim$1.8 and an electron temperature $kT_{\rm e}$ of $\sim$40 keV. We obtain a low inclination angle $i\sim34^{\circ}$. The accretion disk shows properties of strong ionization, $\log(\xi/{\rm erg~cm~s^{-1}})\sim4.5$, over-solar abundance, $A_{\rm Fe}\sim 7.7$, and high density, $\log(n_{\rm e}/{\rm cm^{-3}})\sim 19.5$. However, a lower disk density with normal abundance and ionization could also be possible. From the inner disk radius $R_{\rm in}=1.67R_{\rm ISCO}$ and the long-term spin-down rate of $-3.1(2)\times10^{-15}~{\rm Hz~s^{-1}}$, we constrain the magnetic field of IGR J17498$-$2921 in the range of $(0.9-2.4)\times10^8$ G., Comment: Published in A&A

Published
2024
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6. Soft X-ray prompt emission from a high-redshift gamma-ray burst EP240315a

Author

Liu, Y., Sun, H., Xu, D., Svinkin, D. S., Delaunay, J., Tanvir, N. R., Gao, H., Zhang, C., Chen, Y., Wu, X. -F., Zhang, B., Yuan, W., An, J., Bruni, G., Frederiks, D. D., Ghirlanda, G., Hu, J. -W., Li, A., Li, C. -K., Li, J. -D., Malesani, D. B., Piro, L., Raman, G., Ricci, R., Troja, E., Vergani, S. D., Wu, Q. -Y., Yang, J., Zhang, B. -B., Zhu, Z. -P., Postigo, A. de Ugarte, Demin, A. G., Dobie, D., Fan, Z., Fu, S. -Y., Fynbo, J. P. U., Geng, J. -J., Gianfagna, G., Hu, Y. -D., Huang, Y. -F., Jiang, S. -Q., Jonker, P. G., Julakanti, Y., Kennea, J. A., Kokomov, A. A., Kuulkers, E., Lei, W. -H., Leung, J. K., Levan, A. J., Li, D. -Y., Li, Y., Littlefair, S. P., Liu, X., Lysenko, A. L., Ma, Y. -N., Martin-Carrillo, A., O'Brien, P., Parsotan, T., Quirola-Vasquez, J., Ridnaia, A. V., Ronchini, S., Rossi, A., Mata-Sanchez, D., Schneider, B., Shen, R. -F., Thakur, A. L., Tohuvavohu, A., Torres, M. A. P., Tsvetkova, A. E., Ulanov, M. V., Wei, J. -J., Xiao, D., Yin, Y. -H. I., Bai, M., Burwitz, V., Cai, Z. -M., Chen, F. -S., Chen, H. -L., Chen, T. -X., Chen, W., Chen, Y. -F., Chen, Y. -H., Cheng, H. -Q., Cui, C. -Z., Cui, W. -W., Dai, Y. -F., Dai, Z. -G., Eder, J., Fan, D. -W., Feldman, C., Feng, H., Feng, Z., Friedrich, P., Gao, X., Guan, J., Han, D. -W, Han, J., Hou, D. -J., Hu, H. -B., Hu, T., Huang, M. -H., Huo, J., Hutchinson, I., Ji, Z., Jia, S. -M., Jia, Z. -Q., Jiang, B. -W., Jin, C. -C., Jin, G., Jin, J. -J., Keereman, A., Lerman, H., Li, J. -F., Li, L. -H., Li, M. -S., Li, W., Li, Z. -D., Lian, T. -Y., Liang, E. -W., Ling, Z. -X., Liu, C. -Z., Liu, H. -Y., Liu, H. -Q., Liu, M. -J., Liu, Y. -R., Lu, F. -J., LU, H. -J., Luo, L. -D., Ma, F. L., Ma, J., Mao, J. -R., Mao, X., McHugh, M., Meidinger, N., Nandra, K., Osborne, J. P., Pan, H. -W., Pan, X., Ravasio, M. E., Rau, A., Rea, N., Rehman, U., Sanders, J., Santovincenzo, A., Song, L. -M., Su, J., Sun, L. -J., Sun, S. -L., Sun, X. -J., Tan, Y. -Y., Tang, Q. -J., Tao, Y. -H., Tong, J. -Z., Wang, H., Wang, J., Wang, L., Wang, W. -X., Wang, X. -F., Wang, X. -Y., Wang, Y. -L., Wang, Y. -S., Wei, D. -M., Willingale, R., Xiong, S. -L., Xu, H. -T., Xu, J. -J., Xu, X. -P., Xu, Y. -F., Xu, Z., Xue, C. -B., Xue, Y. -L., Yan, A. -L., Yang, F., Yang, H. -N., Yang, X. -T., Yang, Y. -J, Yu, Y. -W., Zhang, J., Zhang, M., Zhang, S. -N., Zhang, W. -D., Zhang, W. -J., Zhang, Y. -H., Zhang, Z., Zhang, Z. -L., Zhao, D. -H., Zhao, H. -S., Zhao, X. -F., Zhao, Z. -J., Zhou, L. -X., Zhou, Y. -L., Zhu, Y. -X., Zhu, Z. -C., and Zuo, X. -X.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Long gamma-ray bursts (GRBs) are believed to originate from core collapse of massive stars. High-redshift GRBs can probe the star formation and reionization history of the early universe, but their detection remains rare. Here we report the detection of a GRB triggered in the 0.5--4 keV band by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, designated as EP240315a, whose bright peak was also detected by the Swift Burst Alert Telescope and Konus-Wind through off-line analyses. At a redshift of $z=4.859$, EP240315a showed a much longer and more complicated light curve in the soft X-ray band than in gamma-rays. Benefiting from a large field-of-view ($\sim$3600 deg$^2$) and a high sensitivity, EP-WXT captured the earlier engine activation and extended late engine activity through a continuous detection. With a peak X-ray flux at the faint end of previously known high-$z$ GRBs, the detection of EP240315a demonstrates the great potential for EP to study the early universe via GRBs., Comment: 41 pages, 8 figures, 7 tables

Published
2024

7. Distribution of number of peaks within a long gamma-ray burst

Author

Guidorzi, C., Sartori, M., Maccary, R., Tsvetkova, A., Amati, L., Bazzanini, L., Bulla, M., Camisasca, A. E., Ferro, L., Frontera, F., Li, C. K., Xiong, S. L., and Zhang, S. N.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

The variety of long duration gamma-ray burst (LGRB) light curves (LCs) encode a wealth of information on how LGRB engines release energy following the collapse of the progenitor star. Attempts to characterise GRB LCs focused on a number of properties, such as the minimum variability timescale, power density spectra (both ensemble average and individual), or with different definitions of variability. In parallel, a characterisation as a stochastic process was pursued by studying the distributions of waiting times, peak flux, fluence of individual peaks within GRB time profiles. Yet, the question remains as to whether the diversity of profiles can be described in terms of a common stochastic process. Here we address this issue by studying for the first time the distribution of the number of peaks in a GRB profile. We used four different GRB catalogues: CGRO/BATSE, Swift/BAT, BeppoSAX/GRBM, and Insight-HXMT. The statistically significant peaks were identified by means of well tested algorithm MEPSA and further selected by applying a set of thresholds on signal-to-noise ratio. We then extracted the corresponding distributions of number of peaks per GRB. Among the different models considered (power-law, simple or stretched exponential) only a mixture of two exponentials models all the observed distributions, suggesting the existence of two distinct behaviours: (i) an average number of 2.1+-0.1 peaks per GRB ("peak poor") and accounting for about 80% of the observed population of GRBs; (ii) an average number of 8.3+-1.0 peaks per GRB ("peak rich") and accounting for the remaining 20% of the observed population. We associate the class of peak-rich GRBs with the presence of sub-second variability, which seems to be absent among peak-poor GRBs. The two classes could result from two different regimes through which GRB engines release energy or through which energy is dissipated into gamma-rays., Comment: 7 pages, 5 figures, accepted by A&A

Published
2024
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8. Broadband noise and quasi-periodic oscillation characteristics of the X-ray pulsar RX J0440.9+4431

Author

Li, P. P., Tao, L., Ma, R. C., Ge, M. Y., Zhao, Q. C., Zhao, S. J., Zhang, L., Bu, Q. C., Kong, L. D., Tuo, Y. L., Ji, L., Zhang, S., Qu, J. L., Zhang, S. N., Huang, Y., Ma, X., Ye, W. T., and Shui, Q. C.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, High Energy Physics - Phenomenology
Abstract

We present a comprehensive timing analysis on the Be/X-ray binary pulsar RX J0440.9+4431 using observations from \textit{NICER} and \textit{Insight}-HXMT during the 2022--2023 outburst. The power density spectrum (PDS) of RX J0440.9+4431 exhibits typical aperiodic variability in X-ray flux across a wide frequency range. During a super-critical accretion state, we detect quasi-periodic oscillations (QPOs) at 0.2--0.5\,Hz in the light curves of five pulses for RX J0440.9+4431. The observed QPOs manifest during flares, while the flares appear at the peaks of the pulse profiles on a timescale of seconds and are primarily caused by an increase in hard photons. These flares can be explained by increased material ingestion in the accretion column at a fixed phase, primarily generating hard photons. Alternatively, an increase in accretion rate, independent of phase, may result in highly beamed hard photons within the accretion column, causing the flares. We argue the origin of QPOs to instabilities within the accretion flow. Additionally, we find that the break frequencies in the noise power spectra align well with $\propto L_{\mathrm{x}}^{3 / 7}$ across three orders of magnitude in the luminosity, which points to a relatively strong magnetic field in RX J0440.9+4431, estimated to be \textasciitilde$10^{13}$\,G., Comment: 8 pages, 7 figures. Accepted in MNRAS

Published
2024

9. Pulsed Iron line Emission from the First Galactic Ultraluminous X-ray Pulsar Swift J0243.6+6124

Author

Xiao, Y. X., Xu, Y. J., Ge, M. Y., Lu, F. J., Zhang, S. N., Zhang, S., Tao, L., Qu, J. L., Wang, P. J., Kong, L. D., Tuo, Y. L., You, Y., Zhao, S. J., Peng, J. Q., Du, Y. F., Zhang, Y. H., and Ye, W. T.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report the phase-resolved spectral results of the first Galactic Pulsating Ultra-Luminous X-ray source (PULX) Swift J0243.6+6124, modeling at its 2017-2018 outburst peak using data collected by the Hard X-ray Modulation Telescope (Insight-HXMT). The broad energy coverage of Insight-HXMT allows us to obtain more accurate spectral continuum to reduce the coupling of broad iron line profiles with other components. We use three different continuum spectrum models but obtain similar iron line results. For the first time, we detected the pulse characteristics of the broad iron line in a PULX. The variation in width and intensity of this iron line with $\sigma \sim 1.2-1.5$\,keV has a phase offset of about 0.25 from the pulse phase. We suggest that the uneven irradiation of the thick inner disk by the accretion column produces the modulated variation of the broad iron line. In addition, the non-pulsed narrow line is suggested to come from the outer disk region.

Published
2024

11. Estimating the Spin of MAXI J1348–630 from Intermediate and Soft States Using Insight-HXMT Data.

Author

Guan, J., Ma, R. C., Tao, L., Fabian, A. C., Tomsick, J. A., Zhang, S. N., Zhang, L., Qu, J. L., and Zhang, S.

Abstract

We present a broadband spectral analysis of the soft-intermediate and soft states using Insight-HXMT observations of the black hole binary MAXI J1348–630 during its outburst in 2019. We employ a combination of reflection and continuum fitting methods to measure the spin of the black hole and determine a spin of a = 0.79 ± 0.13, which is consistent with most of the previous results. Additionally, we investigate some sources of systematic uncertainty that could bias the measurement. The valid spectral hardening factor can partially account for the spin evolution observed during the outburst. Other potential factors, such as assumptions about the corona's structure and their interaction with reflected photons, can also affect the accuracy of spin measurements. Furthermore, our analysis reveals that MAXI J1348–630 exhibits a significantly high disk density (∼1022 cm−3), with a moderate iron abundance of approximately 2.5 times solar. [ABSTRACT FROM AUTHOR]

Published
2024
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12. A simulation study on the sub-threshold joint gravitational wave–electromagnetic wave observation on binary neutron star mergers.

Author

Du, Y F, Yorgancioglu, Emre Seyit, Rao, J H, Kumar, Ankit, Yi, S X, Zhang, S N, and Zhang, Shu

Subjects
GAMMA ray bursts, NEUTRON stars, BINARY stars, STELLAR mergers, MERGERS & acquisitions
Abstract

The coalescence of binary neutron stars (BNS) is a prolific source of gravitational waves (GWs) and electromagnetic (EM) radiation, offering a dual observational window into the Universe. Lowering the signal-to-noise ratio (S/N) threshold is a simple and cost-effective way to enhance the detection probability of GWs from BNS mergers. In this study, we introduce a metric of the purity of joint GW and EM detections |$P_{\rm joint}$|⁠ , which is in analogue to |$P_{\rm astro}$| in GW-only observations. By simulating BNS merger GWs jointly detected by the Handford, LIGO Livingston, and Virgo network and EM counterparts (kilonovae and short gamma-ray bursts, sGRBs) with an assumed merger rate density of BNS, we generate catalogues of GW events and EM counterparts. Through this simulation, we analyse joint detection pairs, both correct and misidentified. We find the following: (1) For kilonovae, requiring |$P_{\rm joint}\gt $| 95 per cent instead of |$P_{\rm astro}\gt 95~{{\ \rm per\ cent}}$| reduces the S/N from 9.2 to 8.5–8.8, allowing 5–13 additional joint detections per year and increasing the GW detection volume by 9–17 per cent. (2) For sGRBs, requiring |$P_{\rm joint}\gt $| 95 per cent instead of |$P_{\rm astro}$| reduces the S/N from 9.2 to 8.1–8.5. (3) Increasing kilonova or sGRB detection capability does not improve |$P_{\rm joint}$| due to a higher rate of misidentifications. We also show that sub-threshold GW and kilonova detections can reduce the uncertainty in measuring the Hubble constant to 89–92 per cent of its original value, and sub-threshold GW and sGRB observations can enhance the precision of constraining the speed of GWs to 88 per cent of previously established values. [ABSTRACT FROM AUTHOR]

Published
2024
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13. Distribution of the number of peaks within a long gamma-ray burst

Author

Guidorzi, C., primary, Sartori, M., additional, Maccary, R., additional, Tsvetkova, A., additional, Amati, L., additional, Bazzanini, L., additional, Bulla, M., additional, Camisasca, A. E., additional, Ferro, L., additional, Frontera, F., additional, Li, C. K., additional, Xiong, S. L., additional, and Zhang, S. N., additional

Published
2024
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14. Pulsed Iron Line Emission from the First Galactic Ultraluminous X-Ray Pulsar Swift J0243.6+6124

Author

Xiao, Y. X., primary, Xu, Y. J., additional, Ge, M. Y., additional, Lu, F. J., additional, Zhang, S. N., additional, Zhang, S., additional, Tao, L., additional, Qu, J. L., additional, Wang, P. J., additional, Kong, L. D., additional, Tuo, Y. L., additional, You, Y., additional, Zhao, S. J., additional, Peng, J. Q., additional, Du, Y. F., additional, Zhang, Y. H., additional, and Ye, W. T., additional

Published
2024
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15. Polarization perspectives on Hercules X-1: further constraining the geometry.

Author

Zhao, Q C, Li, H C, Tao, L, Feng, H, Zhang, S N, Walter, R, Ge, M Y, Tong, H, Ji, L, Zhang, L, Qu, J L, Huang, Y, Ma, X, Zhang, S, Yin, Q Q, Yin, H X, Ma, R C, Zhao, S J, Li, P P, and Yang, Z X

Subjects
BREWSTER'S angle, MAGNETIC dipoles, NEUTRON stars, X-ray imaging, GEOMETRY, ANGLES
Abstract

We conduct a comprehensive analysis of the accreting X-ray pulsar, Hercules X-1, utilizing data from Imaging X-ray Polarimetry Explorer (IXPE) and Nuclear Spectroscopic Telescope Array. IXPE performed five observations of Her X-1, consisting of three in the Main-on state and two in the Short-on state. Our time-resolved analysis uncovers the linear correlations between the flux and polarization degree as well as the pulse fraction and polarization degree. Geometry parameters are rigorously constrained by fitting the phase-resolved modulations of Cyclotron Resonance Scattering Feature and polarization angle with a simple dipole model and Rotating Vector Model, respectively, yielding roughly consistent results. The changes of χp (the position angle of the pulsar's spin axis on the plane of the sky) between different Main-on observations suggest the possible forced precession of the neutron star crust. Furthermore, a linear association between the energy of Cyclotron Resonance Scattering Feature and polarization angle implies the prevalence of a dominant dipole magnetic field, and their phase-resolved modulations likely arise from viewing angle effects. [ABSTRACT FROM AUTHOR]

Published
2024
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16. Insight–HXMT observations of thermonuclear X-ray bursts from 4U 1608–52 in the low/hard state: the energy-dependent hard X-ray deficit and cooling saturation of the corona.

Author

Chen, Y P, Zhang, S, Ji, L, Zhang, S N, Peng, J Q, Kong, L D, Chang, Z, Shui, Q C, Tao, L, Qu, J L, Ge, M Y, and Li, J

Subjects
X-ray bursts, NEUTRON stars, EDDINGTON mass limit, HARD X-rays, X-ray binaries, SOFT X rays, GAMMA ray bursts, HIGH temperatures, SOLAR atmosphere
Abstract

During thermonuclear bursts, it is suspected that cooling of the corona by the burst emission may be the cause of hard X-ray deficits. Although such a deficit has been observed in nine sources, it has not been observed from 4U 1608–52, a nearby prolific burster. Therefore, the authenticity and universality of the hard X-ray deficit may be in question. To investigate this suspicion, Insight–HXMT performed cadence observations during the low/hard state of 4U 1608–52 in 2022 September and detected 10 thermonuclear X-ray bursts. Two of these bursts show a double-peaked structure in the soft X-ray band, which could be caused by the high temperature of the burst emission and a marginal photospheric radius expansion (PRE) around the burst peak time. This is indicated by their peak fluxes being up to the Eddington limit and having a large colour factor at the peak of the bursts. A hard X-ray deficit is observed at a significant level during bursts at > 30 keV. Furthermore, the fraction of this deficit shows saturation at 50 per cent for the first eight bursts. This saturation may indicate that the corona is layered and only part of the corona is cooled by the bursts: for example, the part close to the neutron star surface is cooled while the rest remains intact during bursts. This result provides a clue to the geometry of the corona. For example, a possible scenario is that the corona has two forms: a quasi-spheric corona between the neutron star and the disc and a disc corona on both surfaces of the disc. [ABSTRACT FROM AUTHOR]

Published
2024
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17. The bright black hole X-ray binary 4U 1543–47 during the 2021 outburst: A thick accretion disk inflated by high luminosity.

Author

Zhao, S. J., Tao, L., Li, P. P., Soria, R., Feng, H., Zhang, Y. X., Ma, R. C., Zhang, W. D., Qiao, E. L., Yin, Q. Q., Zhang, S. N., Zhang, L., Bu, Q. C., Ma, X., Huang, Y., Ge, M. Y., Li, X. B., Chen, L., Zhao, Q. C., and Peng, J. Q.

Subjects
BINARY black holes, X-ray binaries, ACCRETION disks, EDDINGTON mass limit, X-ray telescopes, HARD X-rays, LUMINOSITY
Abstract

The black hole X-ray binary source 4U 1543–47 experienced a super-Eddington outburst in 2021, reaching a peak flux of up to ∼1.96 × 10−7 erg cm−2 s−1 (∼8.2 Crab) in the 2−10 keV band. Soon after the outburst began, it rapidly transitioned into the soft state. Our goal is to understand how the accretion disk structure deviates from a standard thin disk when the accretion rate is near Eddington. To do so, we analyzed spectra obtained from quasi-simultaneous observations conducted by the Hard X-ray Modulation Telescope (Insight-HXMT), the Nuclear Spectroscopic Telescope Array (NuSTAR), and the Neil Gehrels Swift Observatory (Swift). These spectra are well fitted by a model comprising a disk, a weak corona, and a reflection component. We suggest that the reflection component is caused by disk self-irradiation, that is by photons emitted from the inner disk that return to the accretion disk surface as their trajectories are bent by the strong gravity field. In this scenario, the best-fitting parameters imply that the reflected flux represents more than half of the total flux. Using general relativistic ray-tracing simulations, we show that this scenario is viable when the disk becomes geometrically thick, with a funnel-like shape, as the accretion rate is near or above the Eddington limit. In the specific case of 4U 1543–47, an angle ≳45 deg between the disk surface and the equatorial plane can explain the required amount of self-irradiation. [ABSTRACT FROM AUTHOR]

Published
2024
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18. New insight into the hard X-ray emission influenced by the type I bursts observed by Insight-HXMT during the outburst of 4U 1636–536.

Author

Peng, J. Q., Zhang, S., Chen, Y. P., Kong, L. D., Wang, P. J., Zhang, S. N., Shui, Q. C., Ji, L., Zhang, G. B., Yan, Z., Tao, L., Qu, J. L., Ge, M. Y., Yu, Z. L., Li, J., Chang, Z., Li, Z. S., Zhang, P., Xiao, Y. X., and Zhao, S. J.

Subjects
HARD X-rays, X-ray bursts, X-ray binaries, LIGHT curves, NEUTRON stars, GAMMA ray bursts, DATA quality, SOLAR corona
Abstract

Context. Thermonuclear bursts, also known as type I X-ray bursts, result from unstable nuclear burning of H/He accreted to the surface of neutron stars, lasting from tens to hundreds of seconds. Thermonuclear bursts have an important impact on accretion environments around the neutron stars, such as their disks and coronas, and are therefore a subject of extensive research. Thermonuclear bursts can be used as probes to gain a deeper understanding of the properties of their disks and coronas. Aims. By analyzing the data from Insight-HXMT and NICER, we can determine the evolution of the significance of the hard shortage in 4U 1636–536 with its spectral state, as well as the evolution of the fraction of deficit with energy. Additionally, we investigate the possible geometry and evolution of the corona in 4U 1636–536 by combining our findings with the results of spectral analysis. Methods. We extracted the light curves from the Insight-HXMT low-energy, medium-energy, and high-energy data and subtracted their pre-burst emission, which allowed us to estimate the significance of the hard shortages during the bursts. By fitting the spectra, the correlation between the persistent spectral parameters and the significance of the hard shortages could be established. The bursts were then grouped according to the spectral state in which they occurred, and the significance of the hard shortages was estimated. These in turn helped to investigate the evolution of the fraction of deficit with energy. Results. We find that during the soft state the significance of possible hard X-ray shortage in bursts is almost zero. However, in the hard state, some bursts exhibit significant shortages (> 3σ), while others do not. We attempt to establish a correlation between the significance of the hard X-ray shortage and the spectral parameters, but the data quality and the limited number of bursts prevent us from finding a strong correlation. For bursts with insignificant shortages in the soft state, the fraction of the deficit remains small. However, in the hard state the fraction of deficit for all bursts increases with energy, regardless of the significance of the shortage of individual bursts. For bursts during the hard state, we investigated the evolution of the fraction of deficit during the bursts by stacking the peaks and decays of the bursts, and find that as the flux of the bursts decreases, the energy corresponding to the maximum of the fraction of deficit becomes progressively higher. Conclusions. We explore the possible geometry and evolution of the corona suggested by the evolution of the fraction of deficit, which is obtained from the spectral and temporal analysis. [ABSTRACT FROM AUTHOR]

Published
2024
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19. Broad-band noise and quasi-periodic oscillation characteristics of the X-ray pulsar RX J0440.9+4431.

Author

Li, P P, Tao, L, Ma, R C, Ge, M Y, Zhao, Q C, Zhao, S J, Zhang, L, Bu, Q C, Kong, L D, Tuo, Y L, Ji, L, Zhang, S, Qu, J L, Zhang, S N, Huang, Y, Ma, X, Ye, W T, and Shui, Q C

Subjects
BINARY pulsars, PULSARS, X-rays, POWER spectra, LIGHT curves, ACCRETION (Astrophysics), SOLAR flares, GAMMA ray bursts
Abstract

We present a comprehensive timing analysis on the Be/X-ray binary pulsar RX J0440.9+4431 using observations from NICER and Insight - HXMT during the 2022–2023 outburst. The power density spectrum (PDS) of RX J0440.9+4431 exhibits typical aperiodic variability in X-ray flux across a wide frequency range. During a supercritical accretion state, we detect quasi-periodic oscillations (QPOs) at 0.2–0.5 Hz in the light curves of five pulses for RX J0440.9+4431. The observed QPOs manifest during flares, while the flares appear at the peaks of the pulse profiles on a time-scale of seconds and are primarily caused by an increase in hard photons. These flares can be explained by increased material ingestion in the accretion column at a fixed phase, primarily generating hard photons. Alternatively, an increase in accretion rate, independent of phase, may result in highly beamed hard photons within the accretion column, causing the flares. We argue the origin of QPOs to instabilities within the accretion flow. Additionally, we find that the break frequencies in the noise power spectra align well with |$\propto L_{\mathrm{x}}^{3 / 7}$| across three orders of magnitude in the luminosity, which points to a relatively strong magnetic field in RX J0440.9+4431, estimated to be ~1013 G. [ABSTRACT FROM AUTHOR]

Published
2024
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20. GREEN FINANCE, GREEN TECHNOLOGY INNOVATION AND AGRICULTURAL CARBON EMISSIONS IN CHINA.

Author

DENG, Y. and ZHANG, S. N.

Subjects
AGRICULTURAL pollution, CARBON emissions, AGRICULTURAL innovations, GREEN technology, TECHNOLOGICAL innovations, AGRICULTURAL industries, AGRICULTURAL development
Abstract

Extensive agricultural development in China has given rise to a range of environmental issues that pose a significant hurdle to the country's "dual-carbon" goal. In order to tackle this challenge effectively, it becomes crucial to tap into the potential of green financial developments as means of reducing carbon emissions. To shed light on this matter, this study collates data from a total of 30 provinces in China from 2007 to 2019. And A two-way fixed-effects model was employed to examine the extent to which the advancement of green finance (GF) in China has effectively contributed to the decrease of carbon emissions in the agricultural sector. Furthermore, our research endeavors encompass the investigation of the specific mechanisms via which green finance has its influence on carbon emissions within the agricultural sector. The findings indicate that the implementation of green finance plays a crucial role in facilitating the reduction of carbon emissions within the agricultural sector in China. Technological advancements emerge as the primary mechanism through which green finance facilitates agricultural carbon emission reduction. Nevertheless, the impact of modernizing the regional industrial structure has been detrimental in this regard. [ABSTRACT FROM AUTHOR]

Published
2024
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21. The post-quiescence properties of Cir X-1 at orbital phase around periastron observed by NuSTAR and NICER.

Author

Yu, Z L, Zhang, S, Chen, Y P, Kong, L D, Wang, P J, Shui, Q C, Peng, J Q, Yan, Z, Li, X D, and Zhang, S N

Subjects
STELLAR winds, X-ray binaries, ACCRETION disks, OBSERVATORIES
Abstract

Cir X-1 is an unusual X-ray binary, which has resumed periodic outbursts since August 2019. We investigate the post-quiescence spectral properties of Cir X-1 at orbital phase around the periastron using NICER and NuSTAR X-ray observatories after the resumption of outbursts. We identify two distinct classes of spectral properties. The first class exhibits highly ionized absorption, whereas the second class does not. We suggest that the ionized absorption originates from the shelter of the disc wind, while the low-ionized/neutral absorption arises from the companion's stellar wind. We also suggest that the disc wind may be always present in both classes, and a warped precession disc could alter the visibility of the disc wind. [ABSTRACT FROM AUTHOR]

Published
2024
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22. Enhanced Jc in Bi-2212 Round Wires With Optimization of Calcination Atmosphere

Author

Jin, L. H., Xiong, Z. K., Xu, X. Y., Liu, G. Q., Feng, J. Q., Zhang, S. N., Hao, Q. B., Li, C. S., and Zhang, P. X.

Abstract

High-performance precursor powders are crucial for the transport current of Bi2Sr2CaCu2Ox (Bi-2212) round wires. However, the impact of the powder calcination process on the wire performance is not fully understood. Here, Bi-2212 precursor powders were prepared using ultrasonic spray pyrolysis technique and then calcined under different atmospheres. The influences of calcination atmosphere on the microstructures, melting behavior and critical current density (Jc) of Bi-2212 multi-filamentary wires were systematically discussed by tuning the oxygen partial pressure from 0.001 bar to 1.0 bar. As the oxygen partial pressure was increased, a more uniform melting behavior was observed in the Bi-2212 wires, and the large merging bridges was reduced in the filaments. High Jc of 2715 A/mm2 at 4.2 K, 12 T were achieved in the sample with 1.0 bar O2. Therefore, controlling calcination atmosphere of precursor powder was significant for achieving superior transport current of Bi-2212 wires.

Published
2024
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23. [Long-term health-related quality of life and related factors in children with severe hemophilia A who received regular low-dose prophylaxiss].

Author

Li Z, Zhou Y, Zhang SN, Li KX, Zhao YQ, Wang SJ, and Xiao J

Subjects
Humans, Child, Retrospective Studies, Adolescent, Surveys and Questionnaires, Male, Hemophilia A drug therapy, Quality of Life, Factor VIII therapeutic use
Abstract

Objective: To investigate long-term health-related quality of life (HRQoL) and related factors in children with severe hemophilia A (HA) who received regular low-dose prophylaxis. Methods: Clinical data of severe HA children who began to receive regular low-dose coagulation factor Ⅷ (FⅧ) prophylaxis in Peking Union Medical College Hospital from January 1, 2008 to December 31, 2011 were retrospectively enrolled. The longest last follow-up period was May 31, 2023. The attendance of school or work and daily physical activity during the last follow-up were investigated. The patients were divided into full attendance group and incomplete attendence group according to attendance. The patients were divided into into exercise attainment group (reached Chinese sports recommendation) and exercise nonattainment group according to the exercise status. Barthel score was used to assess activities of daily living and Haemo-QoL was used to assess quality of life. Long-term HRQoL for children aged 8-16 years and patients aged 17 years and above were assessed using Haemo-QoL SF and Haem-A-QoL versions, respectively. Spearman correlation analysis was used to examine the correlation between treatment conditions and Haemo-QoL scores. Results: A total of 22 cases were enrolled, the prophylaxis initiation age ranged from 1.8-17.9 (10.4±3.8) years old. The average prophylactic FⅧ dose during low-dose prophylaxis was 24.2 U/kg per week and the follow-up time was 6.3-15.1 (9.6±2.8) years. At the last follow-up, the age of the patients was (20.2±5.4) years, of which 14 (63.6%) were adults over 18 years old. There were 15 patients in the full attendance group and 7 patients in the incomplete attendence group. Compared with the full attendance group, the incomplete attendence group had a smaller preventive treatment dose [ M ( Q 1, Q 3 ), (28.4±11.1) vs (15.3±3.7) U/kg, P =0.012], shorter preventive treatment time [148. 1 (18.6, 346.5) vs 48.0 (32.0, 156.9) weeks, P =0.017], and higher annual joint bleeding rate (AJBR) [12.5 (6.0, 22.3) vs 14.2 (13.2, 17.8) times, P =0.017]. There were 7 cases in the exercise attainment group and 15 cases in the exercise nonattainment group. Compared to the exercise attainment group, the exercise nonattainment group had shorter preventive treatment time[313. 7 (156.9, 366.0) vs 48.0 (16.5, 108.9) weeks, P =0.006], a higher AJBR [7.0 (5.1, 10.0) vs 23.3 (12.5, 29.8), P =0.003] and a higher hemophilia joint health score (HJHS) [9.0 (2.0, 15.5) vs 23.0 (12.0, 27.8), P =0.014]. Barthel score showed 81.8% (18 cases) of the patients' living ability was not influenced by the illness. In Haemo-QoL score, the total score of Haemo-QoL SF in 7 cases was (47.6±17.0) scores, the total score of Haem-A-QoL in 15 cases was (45.2±22.6) scores. The daily activity dimension of the Haem-A-QoL score was the lowest [38.2 (10.9, 45.5) scores], which was positively correlated with the starting age of prophylactic initiation ( r =0.501, P =0.057), and negatively correlated with the duration of prophylaxis ( r =-0.545, P =0.036). Conclusions: Regular low-dose prophylaxis could improve the long-term HRQoL of some children with severe HA, and children with higher prophylactic doses and longer prophylactic treatment time have higher quality of life.

Published
2024
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