Exploring Physically Motivated Models to Fit Gamma-Ray Burst Spectra
We explore fitting gamma-ray burst (GRB) spectra with three physically motivated models, and thus revisit the viability of synchrotron radiation as the primary source of GRB prompt emission. We pick a sample of 100 bright GRBs observed by the Fermi Gamma-ray Burst Monitor (GBM), based on their energ...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/ad0e11 |
| _version_ | 1797397069077413888 |
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| author | S. Poolakkil R. Preece P. Veres |
| author_facet | S. Poolakkil R. Preece P. Veres |
| author_sort | S. Poolakkil |
| collection | DOAJ |
| description | We explore fitting gamma-ray burst (GRB) spectra with three physically motivated models, and thus revisit the viability of synchrotron radiation as the primary source of GRB prompt emission. We pick a sample of 100 bright GRBs observed by the Fermi Gamma-ray Burst Monitor (GBM), based on their energy flux values. In addition to the standard empirical spectral models used in previous GBM spectroscopy catalogs, we also consider three physically motivated models; (a) a thermal synchrotron model, (b) a Band model with a high-energy cutoff, and (c) a smoothly broken power-law (SBPL) model with a multiplicative broken power law (MBPL). We then adopt the Bayesian information criterion to compare the fits obtained and choose the best model. We find that 42% of the GRBs from the fluence spectra and 23% of GRBs from the peak-flux spectra have one of the three physically motivated models as their preferred one. From the peak-flux spectral fits, we find that the low-energy index distributions from the empirical model fits for long GRBs peak around the synchrotron value of −2/3, while the two low-energy indices from the SBPL+MBPL fits of long GRBs peak close to the −2/3 and −3/2 values expected for a synchrotron spectrum from marginally fast-cooling electrons. |
| first_indexed | 2024-03-09T01:04:39Z |
| format | Article |
| id | doaj.art-5b03ba7e52f843209c4142bf1e01c0bc |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-09T01:04:39Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-5b03ba7e52f843209c4142bf1e01c0bc2023-12-11T11:39:06ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-0195929110.3847/1538-4357/ad0e11Exploring Physically Motivated Models to Fit Gamma-Ray Burst SpectraS. Poolakkil0https://orcid.org/0000-0002-6269-0452R. Preece1https://orcid.org/0000-0003-1626-7335P. Veres2https://orcid.org/0000-0002-2149-9846Department of Space Science, University of Alabama in Huntsville , Huntsville, AL 35899, USA; Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville , Huntsville, AL 35899, USADepartment of Space Science, University of Alabama in Huntsville , Huntsville, AL 35899, USADepartment of Space Science, University of Alabama in Huntsville , Huntsville, AL 35899, USA; Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville , Huntsville, AL 35899, USAWe explore fitting gamma-ray burst (GRB) spectra with three physically motivated models, and thus revisit the viability of synchrotron radiation as the primary source of GRB prompt emission. We pick a sample of 100 bright GRBs observed by the Fermi Gamma-ray Burst Monitor (GBM), based on their energy flux values. In addition to the standard empirical spectral models used in previous GBM spectroscopy catalogs, we also consider three physically motivated models; (a) a thermal synchrotron model, (b) a Band model with a high-energy cutoff, and (c) a smoothly broken power-law (SBPL) model with a multiplicative broken power law (MBPL). We then adopt the Bayesian information criterion to compare the fits obtained and choose the best model. We find that 42% of the GRBs from the fluence spectra and 23% of GRBs from the peak-flux spectra have one of the three physically motivated models as their preferred one. From the peak-flux spectral fits, we find that the low-energy index distributions from the empirical model fits for long GRBs peak around the synchrotron value of −2/3, while the two low-energy indices from the SBPL+MBPL fits of long GRBs peak close to the −2/3 and −3/2 values expected for a synchrotron spectrum from marginally fast-cooling electrons.https://doi.org/10.3847/1538-4357/ad0e11Gamma-ray bursts |
| spellingShingle | S. Poolakkil R. Preece P. Veres Exploring Physically Motivated Models to Fit Gamma-Ray Burst Spectra The Astrophysical Journal Gamma-ray bursts |
| title | Exploring Physically Motivated Models to Fit Gamma-Ray Burst Spectra |
| title_full | Exploring Physically Motivated Models to Fit Gamma-Ray Burst Spectra |
| title_fullStr | Exploring Physically Motivated Models to Fit Gamma-Ray Burst Spectra |
| title_full_unstemmed | Exploring Physically Motivated Models to Fit Gamma-Ray Burst Spectra |
| title_short | Exploring Physically Motivated Models to Fit Gamma-Ray Burst Spectra |
| title_sort | exploring physically motivated models to fit gamma ray burst spectra |
| topic | Gamma-ray bursts |
| url | https://doi.org/10.3847/1538-4357/ad0e11 |
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