Detailed Time-resolved Spectral and Temporal Investigations of SGR J1550–5418 Bursts Detected with Fermi Gamma-Ray Burst Monitor
We have conducted a time-resolved spectral analysis of magnetar bursts originating from SGR J1550−5418. Our analysis utilizes a two-step methodology for temporal segmentation of the data. We first generated and fitted overlapping time segments. Subsequently, we obtained nonoverlapping time segments...
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IOP Publishing
2025-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/ade237 |
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| author | Mustafa Demirer Ersin Göğüş Yuki Kaneko Özge Keskin Sinem Şaşmaz Shotaro Yamasaki |
| author_facet | Mustafa Demirer Ersin Göğüş Yuki Kaneko Özge Keskin Sinem Şaşmaz Shotaro Yamasaki |
| author_sort | Mustafa Demirer |
| collection | DOAJ |
| description | We have conducted a time-resolved spectral analysis of magnetar bursts originating from SGR J1550−5418. Our analysis utilizes a two-step methodology for temporal segmentation of the data. We first generated and fitted overlapping time segments. Subsequently, we obtained nonoverlapping time segments with varying lengths based on their spectral evolution patterns, employing a machine learning algorithm called k -means clustering. For the fitting process, we employed three distinct models, namely a modified blackbody (MBB-RCS), a double blackbody (BB+BB), and a power law with an exponential cutoff (COMPT) model. We found that nearly all of the time segments fit well with the COMPT model. Both the average peak energy in the νF _ν spectra ( E _peak ) and photon index parameters follow a Gaussian distribution with means ∼30 keV and −0.5, respectively. Furthermore, there is a strong positive correlation between the cooler and hotter temperature parameters of the BB+BB model, and both parameters show a Gaussian distribution with peaks ∼4 and 12 keV, respectively. Additionally, we found that the distribution of the temperature parameter of the MBB-RCS model can be fit with a skewed Gaussian function with a peak ∼9–10 keV. Lastly, we searched for quasiperiodic spectral oscillations (QPSOs) in the hardness ratio evolution of the bursts. We identified five potential QPSO candidates at frequencies ranging from ∼15 to ∼68 Hz. We discuss and compare these results with previous studies. |
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| institution | DOAJ |
| issn | 1538-4357 |
| language | English |
| publishDate | 2025-01-01 |
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| spelling | doaj-art-a158762b31fc4979bbdcda25a1ca0db92025-08-20T03:09:36ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01988228210.3847/1538-4357/ade237Detailed Time-resolved Spectral and Temporal Investigations of SGR J1550–5418 Bursts Detected with Fermi Gamma-Ray Burst MonitorMustafa Demirer0https://orcid.org/0009-0000-9126-7824Ersin Göğüş1https://orcid.org/0000-0002-5274-6790Yuki Kaneko2https://orcid.org/0000-0002-1861-5703Özge Keskin3https://orcid.org/0000-0001-9711-4343Sinem Şaşmaz4https://orcid.org/0000-0002-9669-5825Shotaro Yamasaki5https://orcid.org/0000-0002-1688-8708Faculty of Engineering and Natural Sciences, Sabancı University , İstanbul 34956, Türkiye ; mustafa.demirer@sabanciuniv.eduFaculty of Engineering and Natural Sciences, Sabancı University , İstanbul 34956, Türkiye ; mustafa.demirer@sabanciuniv.eduFaculty of Engineering and Natural Sciences, Sabancı University , İstanbul 34956, Türkiye ; mustafa.demirer@sabanciuniv.eduFaculty of Engineering and Natural Sciences, Sabancı University , İstanbul 34956, Türkiye ; mustafa.demirer@sabanciuniv.eduDepartment of Physics Engineering, İstanbul Technical University , İstanbul 34469, TürkiyeDepartment of Physics, National Chung Hsing University , 145 Xingda Rd., South Dist., Taichung 40227, TaiwanWe have conducted a time-resolved spectral analysis of magnetar bursts originating from SGR J1550−5418. Our analysis utilizes a two-step methodology for temporal segmentation of the data. We first generated and fitted overlapping time segments. Subsequently, we obtained nonoverlapping time segments with varying lengths based on their spectral evolution patterns, employing a machine learning algorithm called k -means clustering. For the fitting process, we employed three distinct models, namely a modified blackbody (MBB-RCS), a double blackbody (BB+BB), and a power law with an exponential cutoff (COMPT) model. We found that nearly all of the time segments fit well with the COMPT model. Both the average peak energy in the νF _ν spectra ( E _peak ) and photon index parameters follow a Gaussian distribution with means ∼30 keV and −0.5, respectively. Furthermore, there is a strong positive correlation between the cooler and hotter temperature parameters of the BB+BB model, and both parameters show a Gaussian distribution with peaks ∼4 and 12 keV, respectively. Additionally, we found that the distribution of the temperature parameter of the MBB-RCS model can be fit with a skewed Gaussian function with a peak ∼9–10 keV. Lastly, we searched for quasiperiodic spectral oscillations (QPSOs) in the hardness ratio evolution of the bursts. We identified five potential QPSO candidates at frequencies ranging from ∼15 to ∼68 Hz. We discuss and compare these results with previous studies.https://doi.org/10.3847/1538-4357/ade237Neutron starsMagnetarsX-ray bursts |
| spellingShingle | Mustafa Demirer Ersin Göğüş Yuki Kaneko Özge Keskin Sinem Şaşmaz Shotaro Yamasaki Detailed Time-resolved Spectral and Temporal Investigations of SGR J1550–5418 Bursts Detected with Fermi Gamma-Ray Burst Monitor The Astrophysical Journal Neutron stars Magnetars X-ray bursts |
| title | Detailed Time-resolved Spectral and Temporal Investigations of SGR J1550–5418 Bursts Detected with Fermi Gamma-Ray Burst Monitor |
| title_full | Detailed Time-resolved Spectral and Temporal Investigations of SGR J1550–5418 Bursts Detected with Fermi Gamma-Ray Burst Monitor |
| title_fullStr | Detailed Time-resolved Spectral and Temporal Investigations of SGR J1550–5418 Bursts Detected with Fermi Gamma-Ray Burst Monitor |
| title_full_unstemmed | Detailed Time-resolved Spectral and Temporal Investigations of SGR J1550–5418 Bursts Detected with Fermi Gamma-Ray Burst Monitor |
| title_short | Detailed Time-resolved Spectral and Temporal Investigations of SGR J1550–5418 Bursts Detected with Fermi Gamma-Ray Burst Monitor |
| title_sort | detailed time resolved spectral and temporal investigations of sgr j1550 5418 bursts detected with fermi gamma ray burst monitor |
| topic | Neutron stars Magnetars X-ray bursts |
| url | https://doi.org/10.3847/1538-4357/ade237 |
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