<i><b>NuSTAR</b></i> View of TeV Blazar Mrk 501
We report the results of flux and spectral variability studies of all seven <i>Nuclear Spectroscopic Telescope Array (NuSTAR)</i> observations of TeV <inline-formula><math display="inline"><semantics><mrow><mi>γ</mi><mo>-</mo><...
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| Format: | Article |
| Language: | English |
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MDPI AG
2020-07-01
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| Series: | Galaxies |
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| Online Access: | https://www.mdpi.com/2075-4434/8/3/55 |
| Summary: | We report the results of flux and spectral variability studies of all seven <i>Nuclear Spectroscopic Telescope Array (NuSTAR)</i> observations of TeV <inline-formula><math display="inline"><semantics><mrow><mi>γ</mi><mo>-</mo></mrow></semantics></math></inline-formula>ray emitting blazar Markarian (or Mrk) 501. We found strong evidence of intraday variability in 3–79 keV X-ray light curves (LCs) of Mrk 501 during four out of these seven observations. We examined spectral variability using a model-independent hardness-ratio analysis and found a general “harder-when-brighter” behaviour in two observations. We also investigated the nature of 3–79 keV X-ray spectra of TeV blazar Mrk 501 and found that five out of seven spectra are well described by the curved log-parabola models with photon indices (at 10 keV) <inline-formula><math display="inline"><semantics><mrow><mi>α</mi><mo>∼</mo></mrow></semantics></math></inline-formula> 2.12–2.32 and a curvature <inline-formula><math display="inline"><semantics><mrow><mi>β</mi><mo>∼</mo></mrow></semantics></math></inline-formula> 0.15–0.28. The two other spectra are somewhat better represented by simple power-law models with photon indices 2.70 and 2.75. We briefly discuss available physical models to explain our results. |
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| ISSN: | 2075-4434 |