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  • American Astronomical Society  (6)
  • Tuo, You-Li  (6)
  • Physics  (6)
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  • American Astronomical Society  (6)
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Subjects(RVK)
  • Physics  (6)
RVK
  • 1
    Online Resource
    Online Resource
    An Insight-HXMT Dedicated 33 day Observation of SGR J1935+2154. I. Burst Catalog
    American Astronomical Society ; 2022
    In:  The Astrophysical Journal Supplement Series Vol. 260, No. 2 ( 2022-06-01), p. 24-
    Details
    In: The Astrophysical Journal Supplement Series, American Astronomical Society, Vol. 260, No. 2 ( 2022-06-01), p. 24-
    Abstract: Magnetars are neutron stars with an extreme magnetic field and sometimes manifest as soft gamma-ray repeaters (SGRs). SGR J1935+2154 is one of the most prolific bursters and the first confirmed source of a fast radio burst (FRB; i.e., FRB 200428). Encouraged by the discovery of the first X-ray counterpart of FRBs, the Insight-Hard X-ray Modulation Telescope (Insight-HXMT) implemented a dedicated 33-day-long Target of Opportunity observation of SGR J1935+2154 since 2020 April 28. With the HE, ME, and LE telescopes, Insight-HXMT provides a thorough monitoring of burst activity evolution of SGR J1935+2154, in a very broad energy range (1–250 keV) with high temporal resolution and high sensitivity, resulting in a unique valuable data set for detailed studies of SGR J1935+2154. In this work, we conduct a comprehensive analysis of this observation, including detailed burst search, identification, and temporal analyses. After carefully removing false triggers, we find a total of 75 bursts from SGR J1935+2154, out of which 70 are single pulsed. The maximum burst rate is about 56 bursts day −1 . Both the burst duration and the waiting time between two successive bursts follow lognormal distributions, consistent with previous studies. We also find that bursts with longer duration (some are multipulsed) tend to occur during the period with relatively high burst rate. There is no correlation between the waiting time and the fluence or duration of either the former or latter burst. It also seems that there is no correlation between burst duration and hardness ratio, in contrast to some previous reports. In addition, we do not find any X-ray burst associated with any reported radio bursts except for FRB 200428.
    Type of Medium: Online Resource
    ISSN: 0067-0049 , 1538-4365
    URL: Article
    DOI: 10.3847/1538-4365/ac6172
    RVK:
    UA 1000
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2022
    detail.hit.zdb_id: 2006860-8
    detail.hit.zdb_id: 2207650-5
    SSG: 16,12
    Location Call Number Limitation Availability
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    Online Resource
  • 2
    Online Resource
    Online Resource
    An Insight-HXMT Dedicated 33 day Observation of SGR J1935+2154. II. Burst Spectral Catalog
    American Astronomical Society ; 2022
    In:  The Astrophysical Journal Supplement Series Vol. 260, No. 2 ( 2022-06-01), p. 25-
    Details
    In: The Astrophysical Journal Supplement Series, American Astronomical Society, Vol. 260, No. 2 ( 2022-06-01), p. 25-
    Abstract: Since 2020 April 28, Insight-HXMT has implemented a dedicated observation on the magnetar SGR J1935+2154. Thanks to the wide energy band (1–250 keV) and high sensitivity of Insight-HXMT, we obtained 75 bursts from SGR J1935+2154 during a month-long activity episode after the emission of FRB 200428. Here we report the detailed time-integrated spectral analysis of these bursts and the statistical distribution of the spectral parameters. We find that for ∼15% (11/75) of SGR J1935+2154 bursts, the CPL model is preferred, and most of them occurred in the later part of this active epoch. In the cumulative fluence distribution, we find that the fluence of bursts in our sample is about an order of magnitude weaker than that of Fermi/GBM, but it follows the same power-law distribution. Finally, we find a burst with similar peak energy to the time-integrated spectrum of the X-ray burst associated with FRB 200428 (FRB 200428-Associated Burst), but the low energy index is harder.
    Type of Medium: Online Resource
    ISSN: 0067-0049 , 1538-4365
    URL: Article
    DOI: 10.3847/1538-4365/ac67e4
    RVK:
    UA 1000
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2022
    detail.hit.zdb_id: 2006860-8
    detail.hit.zdb_id: 2207650-5
    SSG: 16,12
    Location Call Number Limitation Availability
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    Online Resource
  • 3
    Online Resource
    Online Resource
    GECAM Detection of a Bright Type I X-Ray Burst from 4U 0614+09: Hint for Its Spin Frequency at 413 Hz
    American Astronomical Society ; 2022
    In:  The Astrophysical Journal Vol. 935, No. 1 ( 2022-08-01), p. 10-
    Details
    In: The Astrophysical Journal, American Astronomical Society, Vol. 935, No. 1 ( 2022-08-01), p. 10-
    Abstract: One month after launching the Gravitational Wave High-energy Electromagnetic Counterpart All-sky Monitor, a bright thermonuclear X-ray burst from 4U 0614+09 was observed on 2021 January 24. We report the time-resolved spectroscopy of the burst and a hint of burst oscillation at 413 Hz with a fractional amplitude ∼2.0% (rms). This coincides with the burst oscillation previously discovered with Swift/Burst Alert Telescope (Strohmayer et al. 2008), and therefore supports the spin frequency of this source. This burst is a bright one in the normal bursts detected from 4U 0614+09, which leads to an upper limit of distance estimation of 3.1 kpc. The folded light curve during the burst oscillation shows a sinusoidal structure, which is consistent with previous observations.
    Type of Medium: Online Resource
    ISSN: 0004-637X , 1538-4357
    URL: Article
    DOI: 10.3847/1538-4357/ac7ff8
    RVK:
    UA 1000
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2022
    detail.hit.zdb_id: 2207648-7
    detail.hit.zdb_id: 1473835-1
    SSG: 16,12
    Location Call Number Limitation Availability
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    Online Resource
  • 4
    Online Resource
    Online Resource
    Search for Quasiperiodic Oscillations in Precursors of Short and Long Gamma-Ray Bursts
    American Astronomical Society ; 2022
    In:  The Astrophysical Journal Vol. 941, No. 2 ( 2022-12-01), p. 166-
    Details
    In: The Astrophysical Journal, American Astronomical Society, Vol. 941, No. 2 ( 2022-12-01), p. 166-
    Abstract: The precursors of short and long gamma-ray bursts (SGRBs and LGRBs) can serve as probes of their progenitors, as well as shedding light on the physical processes of mergers or core-collapse supernovae. Some models predict the possible existence of quasiperiodic oscillations (QPOs) in the precursors of SGRBs. Although many previous studies have performed QPO searches in the main emission of SGRBs and LGRBs, so far there were no systematic QPO searches in their precursors. In this work, we perform a detailed QPO search in the precursors of SGRBs and LGRBs detected by Fermi/Gamma-ray Burst Monitor (GBM) from 2008 to 2019 using the power density spectrum (PDS) in the frequency domain and Gaussian processes in the time domain. We do not find any convinced QPO signal with significance above 3 σ , possibly due to the low fluxes of precursors. Finally, the PDS continuum properties of both the precursors and main emissions are also studied for the first time, and no significant difference is found in the distributions of the PDS slope for precursors and main emissions in both SGRBs and LGRBs.
    Type of Medium: Online Resource
    ISSN: 0004-637X , 1538-4357
    URL: Article
    DOI: 10.3847/1538-4357/aca018
    RVK:
    UA 1000
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2022
    detail.hit.zdb_id: 2207648-7
    detail.hit.zdb_id: 1473835-1
    SSG: 16,12
    Location Call Number Limitation Availability
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    Online Resource
  • 5
    Online Resource
    Online Resource
    Neutral Atmospheric Density Measurement Using Insight-HXMT Data by the Earth Occultation Technique
    American Astronomical Society ; 2023
    In:  The Astrophysical Journal Supplement Series Vol. 264, No. 1 ( 2023-01-01), p. 5-
    Details
    In: The Astrophysical Journal Supplement Series, American Astronomical Society, Vol. 264, No. 1 ( 2023-01-01), p. 5-
    Abstract: The Earth occultation technique has broad applications in both astronomy and atmospheric density measurements. We construct the background model during the occultation of the Crab Nebula observed by the Insight-Hard X-ray Modulation Telescope (Insight-HXMT) at energies between 6 and 100 keV. We propose a Bayesian atmospheric density retrieval method based on the Earth occultation technique, combining Poisson and Gaussian statistics. By modeling the atmospheric attenuation of X-ray photons during the occultation, we simultaneously retrieved the neutral densities of the atmosphere at different altitude ranges. Our method considers the correlation of densities between neighboring atmospheric layers and reduces the potential systematic bias to which previous work may be subject. Previous analyses based on light-curve fitting or spectral fitting also lost some spectral or temporal information of the data. In contrast to previous work, the occultation data observed by the three telescopes on board Insight-HXMT is fully used in our analysis, further reducing the statistical error in density retrieval. We apply our method to cross-check the (semi)empirical atmospheric models, using 115 sets of occultation data of the Crab Nebula observed by Insight-HXMT. We find that the retrieved neutral density is ∼10%, ∼20%, and ∼25% less than the values of the widely used atmospheric model NRLMSISE-00, in the altitude range of 55–80 km, 80–90 km, and 90–100 km, respectively. We also show that the newly released atmospheric model NRLMSIS 2.0 is generally consistent with our density measurements.
    Type of Medium: Online Resource
    ISSN: 0067-0049 , 1538-4365
    URL: Article
    DOI: 10.3847/1538-4365/ac9f16
    RVK:
    UA 1000
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2023
    detail.hit.zdb_id: 2006860-8
    detail.hit.zdb_id: 2207650-5
    SSG: 16,12
    Location Call Number Limitation Availability
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    Online Resource
  • 6
    Online Resource
    Online Resource
    The Minimum Variation Timescales of X-Ray Bursts from SGR J1935+2154
    American Astronomical Society ; 2023
    In:  The Astrophysical Journal Supplement Series Vol. 268, No. 1 ( 2023-09-01), p. 5-
    Details
    In: The Astrophysical Journal Supplement Series, American Astronomical Society, Vol. 268, No. 1 ( 2023-09-01), p. 5-
    Abstract: The minimum variation timescale (MVT) of soft gamma-ray repeaters can be an important probe to estimate the emission region in pulsar-like models, as well as the Lorentz factor and radius of the possible relativistic jet in gamma-ray burst (GRB)–like models, thus revealing their progenitors and physical mechanisms. In this work, we systematically study the MVTs of hundreds of X-ray bursts (XRBs) from SGR J1935+2154 observed by Insight-HXMT, GECAM, and Fermi/Gamma-ray Burst Monitor from 2014 July to 2022 January through the Bayesian block algorithm. We find that the MVTs peak at ∼2 ms, corresponding to a light-travel time size of about 600 km, which supports the magnetospheric origin in pulsar-like models. The shock radius and the Lorentz factor of the jet are also constrained in GRB-like models. Interestingly, the MVT of the XRB associated with FRB 200428 is ∼70 ms, which is longer than that of most bursts and implies its special radiation mechanism. In addition, the median of MVTs is 7 ms, shorter than the median MVTs of 40 ms and 480 ms for short GRBs or long GRBs, respectively. However, the MVT is independent of duration, similar to GRBs. Finally, we investigate the energy dependence of MVT and suggest that there is a marginal evidence for a power-law relationship like GRBs, but the rate of variation is at least about an order of magnitude smaller. These features may provide an approach to identify bursts with a magnetar origin.
    Type of Medium: Online Resource
    ISSN: 0067-0049 , 1538-4365
    URL: Article
    DOI: 10.3847/1538-4365/ace77c
    RVK:
    UA 1000
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2023
    detail.hit.zdb_id: 2006860-8
    detail.hit.zdb_id: 2207650-5
    SSG: 16,12
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
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