Issue |
A&A
Volume 673, May 2023
|
|
---|---|---|
Article Number | A85 | |
Number of page(s) | 12 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361/202345936 | |
Published online | 10 May 2023 |
Long-term Swift and Metsähovi monitoring of SDSS J164100.10+345452.7 reveals multi-wavelength correlated variability
1
INAF, Osservatorio Astronomico di Brera, Via Emilio Bianchi 46, 23807 Merate (LC), Italy
e-mail: patrizia.romano@inaf.it
2
Aalto University Metsähovi Radio Observatory, Metsähovintie 114, 02540 Kylmälä, Finland
3
Aalto University Department of Electronics and Nanoengineering, PO Box 15500 00076 Aalto, Finland
4
European Southern Observatory (ESO), Alonso de Córdova 3107, Casilla 19, Santiago 19001, Chile
5
INAF, Osservatorio Astrofisico di Torino, Via Osservatorio 20, 10025 Pino Torinese (TO), Italy
6
Department of Physics, Institute for Astrophysics and Computational Sciences, The Catholic University of America, Washington, DC 20064, USA
7
Dipartimento di Fisica, Università di Trento, Via Sommarive 14, Trento 38123, Italy
8
Dipartimento di Fisica e Astronomia, Università di Padova, 35122 Padova, Italy
9
European Space Agency, European Space Astronomy Centre, C/ Bajo el Castillo s/n, 28692 Villanueva de la Cañada, Madrid, Spain
10
Homer L. Dodge Department of Physics and Astronomy, The University of Oklahoma, 440 W. Brooks St., Norman, OK 73019, USA
11
Università degli Studi di Milano, Bicocca, Piazza delle Scienze 3, 20126 Milano, Italy
Received:
18
January
2023
Accepted:
8
March
2023
We report on the first multi-wavelength Swift monitoring campaign performed on SDSS J164100.10+345452.7, a nearby narrow-line Seyfert 1 galaxy that had formerly been considered to be radio-quiet. It has, however, more recently been detected both in the radio (at 37 GHz) and in the γ-ray, a behaviour that hints at the presence of a relativistic jet. During our 20-month Swift campaign, while pursuing the primary goal of assessing the baseline optical/UV and X-ray properties of SDSS J164100.10+345452.7, we observed two radio flaring episodes, namely, one each year. Our strictly simultaneous multi-wavelength data closely match the radio flare and allow us to unambiguously link the jetted radio emission of SDSS J164100.10+345452.7. Indeed, for the X-ray spectra preceding and following the radio flare, a simple absorbed power-law model does not offer an adequate description and, thus, an extra absorption component is required. The average spectrum of SDSS J164100.10+345452.7 can best be described by an absorbed power-law model with a photon index Γ = 1.93 ± 0.12, modified by a partially covering neutral absorber with a covering fraction of f = 0.91−0.03+0.02. On the contrary, the X-ray spectrum closest to the radio flare does not require any such extra absorber and it is much harder (Γflare ∼ 0.7 ± 0.4), thus implying the emergence of an additional, harder spectral component. We interpret this as the jet emission emerging from a gap in the absorber. The fractional variability we derived in the optical/UV and X-ray bands is found to be lower than the typical values reported in the literature because our observations of SDSS J164100.10+345452.7 are dominated by the source being in a low state, as opposed to the literature, where the observations were generally taken as a follow-up of bright flares in other energy bands. Based on the assumption that the origin of the 37 GHz radio flare is the emergence of a jet from an obscuring screen also observed in the X-ray, the derived total jet power is Pjettot = 3.5 × 1042 erg s−1. This result is close to the lowest values measured in the literature.
Key words: galaxies: Seyfert / galaxies: individual: SDSS J164100.10+345452.7 / galaxies: active / X-rays: individuals: SDSS J164100.10+345452.7
© The Authors 2023
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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