Energy distribution of relativistic electrons in the kiloparsec scale jet of M 87 with Chandra
The X-ray emission from the jets in active galactic nuclei (AGN) carries important information on the distributions of relativistic electrons and magnetic fields on large scales. We reanalysed archival <i>Chandra<i/> observations on the jet of M 87 from 2000 to 2016 with a total exposure...
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| Main Authors: | , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
07 May 2018
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| In: |
Astronomy and astrophysics
Year: 2018, Volume: 612 |
| ISSN: | 1432-0746 |
| DOI: | 10.1051/0004-6361/201731716 |
| Online Access: | Verlag, Volltext: https://doi.org/10.1051/0004-6361/201731716 Verlag, Volltext: https://www.aanda.org/articles/aa/pdf/2018/04/aa31716-17.pdf 
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| Author Notes: | Xiao-Na Sun, Rui-Zhi Yang, Frank M. Rieger, Ruo-Yu Liu, Felix Aharonian |
| Summary: | The X-ray emission from the jets in active galactic nuclei (AGN) carries important information on the distributions of relativistic electrons and magnetic fields on large scales. We reanalysed archival <i>Chandra<i/> observations on the jet of M 87 from 2000 to 2016 with a total exposure of 1460 kiloseconds to explore the X-ray emission characteristics along the jet. We investigated the variability behaviours of the nucleus and the inner jet component HST-1, and confirm indications for day-scale X-ray variability in the nucleus contemporaneous to the 2010 high TeV <i>γ<i/>-ray state. HST-1 shows a general decline in X-ray flux over the last few years consistent with its synchrotron interpretation. We extracted the X-ray spectra for the nucleus and all knots in the jet, showing that they are compatible with a single power law within the X-ray band. There are indications that the resultant X-ray photon index exhibit a trend, with slight but significant index variations ranging from ≃ 2.2 (e.g. in knot D) to ≃ 2.4−2.6 (in the outer knots F, A, and B). When viewed in a multiwavelength context, a more complex situation can be seen. Fitting the radio to X-ray spectral energy distributions (SEDs) assuming a synchrotron origin, we show that a broken power-law electron spectrum with break energy <i>E<i/><sub>b<sub/> around TeV allows a satisfactory description of the multiband SEDs for most of the knots. However, in the case of knots B, C, and D we find indications that an additional high-energy component is needed to adequately reproduce the broad-band SEDs. We discuss the implications and suggest that a stratified jet model may account for the differences. |
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| Item Description: | Gesehen am 25.04.2019 |
| Physical Description: | Online Resource |
| ISSN: | 1432-0746 |
| DOI: | 10.1051/0004-6361/201731716 |