On the Spectral Changes of OJ 287: The Lowest X-ray state Spectrum -- extended at Optical-UV and Hard at X-rays
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arXiv
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| Formato: | Preprint |
| Publicado: |
2023
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| _version_ | 1866911143207895040 |
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| author | Kushwaha, Pankaj |
| author_facet | Kushwaha, Pankaj |
| contents | Optical-UV synchrotron spectrum has been argued to be the primary driver of the majority of X-ray spectral changes in the BL Lacertae object OJ 287 during its low and intermediate X-ray flux state. Here, we focus on the lowest recorded X-ray flux state of OJ 287 by the Swift facility and report the finding of a power-law optical-UV spectrum with a photon spectrum of $\rm 2.71\pm0.03$ continuing into X-rays. Considering this at X-rays, we found a power-law X-ray spectrum of photon spectral index $\rm 1.22\pm0.20$ that improves to $\rm 1.29\pm0.06$ when considering other observations with similar X-ray spectra. This is the hardest reported X-ray spectrum (0.3-10 keV) and is consistent with the reported Swift-BAT hard X-ray spectrum. We further show that this X-ray spectrum can reproduce most of the flat X-ray spectra when combined with the corresponding optical-UV continuum during the low and intermediate flux states strengthening synchrotron as the primary driver of most of the X-ray spectral changes in the LBL state of the source. Combined with sharp-steepening/cutoff of the optical-UV spectrum during bright phases, the extended-spectrum indicates a comparatively larger emission region and could be the large-scale jet emission. The optical-UV spectrum implies a high-energy power-law particle spectrum of $\rm \sim4.4$ while X-ray implies a hard low-energy particle spectrum of $\rm 1.3-1.6$ which could be the real or can result from a higher low-energy cut-off in the particle spectrum. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2305_16144 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | On the Spectral Changes of OJ 287: The Lowest X-ray state Spectrum -- extended at Optical-UV and Hard at X-rays Kushwaha, Pankaj High Energy Astrophysical Phenomena Astrophysics of Galaxies Optical-UV synchrotron spectrum has been argued to be the primary driver of the majority of X-ray spectral changes in the BL Lacertae object OJ 287 during its low and intermediate X-ray flux state. Here, we focus on the lowest recorded X-ray flux state of OJ 287 by the Swift facility and report the finding of a power-law optical-UV spectrum with a photon spectrum of $\rm 2.71\pm0.03$ continuing into X-rays. Considering this at X-rays, we found a power-law X-ray spectrum of photon spectral index $\rm 1.22\pm0.20$ that improves to $\rm 1.29\pm0.06$ when considering other observations with similar X-ray spectra. This is the hardest reported X-ray spectrum (0.3-10 keV) and is consistent with the reported Swift-BAT hard X-ray spectrum. We further show that this X-ray spectrum can reproduce most of the flat X-ray spectra when combined with the corresponding optical-UV continuum during the low and intermediate flux states strengthening synchrotron as the primary driver of most of the X-ray spectral changes in the LBL state of the source. Combined with sharp-steepening/cutoff of the optical-UV spectrum during bright phases, the extended-spectrum indicates a comparatively larger emission region and could be the large-scale jet emission. The optical-UV spectrum implies a high-energy power-law particle spectrum of $\rm \sim4.4$ while X-ray implies a hard low-energy particle spectrum of $\rm 1.3-1.6$ which could be the real or can result from a higher low-energy cut-off in the particle spectrum. |
| title | On the Spectral Changes of OJ 287: The Lowest X-ray state Spectrum -- extended at Optical-UV and Hard at X-rays |
| topic | High Energy Astrophysical Phenomena Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2305.16144 |