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Hauptverfasser: Das, Avik Kumar, Kushwaha, Pankaj, Singh, Veeresh, Mondal, Sandeep Kumar, Ahuja, Goldy, Sarkar, Deekshya R.
Format: Preprint
Veröffentlicht: 2025
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Online-Zugang:https://arxiv.org/abs/2511.21182
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author Das, Avik Kumar
Kushwaha, Pankaj
Singh, Veeresh
Mondal, Sandeep Kumar
Ahuja, Goldy
Sarkar, Deekshya R.
author_facet Das, Avik Kumar
Kushwaha, Pankaj
Singh, Veeresh
Mondal, Sandeep Kumar
Ahuja, Goldy
Sarkar, Deekshya R.
contents We present a long-term broad-band temporal and spectral study of a TeV BL Lac source TXS 0518+211 by analyzing nearly 16 years (MJD 54682 -- 60670) of simultaneous optical, UV and X-ray light curves from \textit{Swift}-XRT/UVOT and gamma-ray light curves from \textit{Fermi}-LAT. Based on the availability of simultaneous multi-wavelength data and considering flux level as the depiction of AGN-jet activity we identified 11 epochs (named as Epoch-A to Epoch-K) and investigated temporal as well as spectral variability during these epochs to understand the emission properties in this source. The fractional variability analysis reveals that, in all epochs, X-ray light curve exhibits relatively high degree of variability in compared to the optical, UV and gamma-ray light curves. The flux-flux plots among different bands, in general, show weak to moderate correlation with Spearman correlation coefficient ranging from 0.29 to 0.58. Notably, during Epoch-I, we detect a possible orphan flare exhibiting increase in the X-ray flux level ($\sim$ 2.4 times of the total average flux) but with no corresponding counterpart seen in the optical, UV bands. In contrast, during Epoch-K, we detect a significant decrease in the X-ray flux but no corresponding decrease in optical, UV and gamma-ray bands. Overall, our study reveals several changes in the flux states and complex nature of jet dominated emission processes. We tested one-zone and two-zone leptonic scenarios and for most of the epochs, the latter one provides a better description of the broad-band emission in this TeV BL Lac source.
format Preprint
id arxiv_https___arxiv_org_abs_2511_21182
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Broad-band temporal and spectral study of TeV blazar TXS 0518+211
Das, Avik Kumar
Kushwaha, Pankaj
Singh, Veeresh
Mondal, Sandeep Kumar
Ahuja, Goldy
Sarkar, Deekshya R.
High Energy Astrophysical Phenomena
We present a long-term broad-band temporal and spectral study of a TeV BL Lac source TXS 0518+211 by analyzing nearly 16 years (MJD 54682 -- 60670) of simultaneous optical, UV and X-ray light curves from \textit{Swift}-XRT/UVOT and gamma-ray light curves from \textit{Fermi}-LAT. Based on the availability of simultaneous multi-wavelength data and considering flux level as the depiction of AGN-jet activity we identified 11 epochs (named as Epoch-A to Epoch-K) and investigated temporal as well as spectral variability during these epochs to understand the emission properties in this source. The fractional variability analysis reveals that, in all epochs, X-ray light curve exhibits relatively high degree of variability in compared to the optical, UV and gamma-ray light curves. The flux-flux plots among different bands, in general, show weak to moderate correlation with Spearman correlation coefficient ranging from 0.29 to 0.58. Notably, during Epoch-I, we detect a possible orphan flare exhibiting increase in the X-ray flux level ($\sim$ 2.4 times of the total average flux) but with no corresponding counterpart seen in the optical, UV bands. In contrast, during Epoch-K, we detect a significant decrease in the X-ray flux but no corresponding decrease in optical, UV and gamma-ray bands. Overall, our study reveals several changes in the flux states and complex nature of jet dominated emission processes. We tested one-zone and two-zone leptonic scenarios and for most of the epochs, the latter one provides a better description of the broad-band emission in this TeV BL Lac source.
title Broad-band temporal and spectral study of TeV blazar TXS 0518+211
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2511.21182