Long-term Swift and Mets\"ahovi monitoring of SDSS J164100.10+345452.7 reveals multi-wavelength correlated variability

We report on the first multi-wavelength Swift monitoring campaign performed on SDSS J164100.10+345452.7, a nearby narrow-line Seyfert 1 galaxy formerly known as radio quiet which was recently detected both in the radio (at 37 GHz) and in the $\gamma$-rays, which 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 J1641, we caught two radio flaring episodes, 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 J1641. Indeed, for the X-ray spectra preceding and following the radio flare a simple absorbed power-law model is not an adequate description, and an extra absorption component is required. The average spectrum of J1641 can be best described by an absorbed power law model with a photon index $\Gamma=1.93\pm0.12$, modified by a partially covering neutral absorber with a covering fraction $f=0.91_{-0.03}^{+0.02}$. On the contrary, the X-ray spectrum closest to the radio flare does not require such extra absorber and is much harder ($\Gamma_{\rm flare} \sim 0.7\pm0.4$), thus implying the emergence of a further, harder spectral component. We interpret this as the jet emission emerging from a gap in the absorber. The fractional variability we derive in the optical/UV and X-ray bands are found to be lower than the typical values reported in the literature, since our observations of J1641 are dominated by the source being in a low state. Under 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-rays, the derived total jet power is $P^{\rm tot}_{\rm jet}=3.5\times10^{42}$ erg s$^{-1}$, comparable to the lowest measured in the literature. [Abridged]Comment: Accepted for publication in Astronomy and Astrophysics (13 pages, 4 figures, 8 tables

A host galaxy study of southern narrow-line Seyfert 1 galaxies

Funding Information: IRAF is distributed by the National Optical Astronomy Observatories, which are operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with FourStar, an infrared camera, part of the Magellan 6.5 m telescopes, at the Las Campanas Observatory in Chile. This research has made use of GALFIT. This publication made use of the SIMBAD database, operated at CDS, Strasbourg, France. This research has made use of “Aladin sky atlas” developed at CDS, Strasbourg Observatory, France. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. This research made use of Astropy ( http://www.astropy.org ), a community-developed core Python package for Astronomy (Astropy Collaboration 2013, 2018). This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. I.V. would like to thank both the Magnus Ehrnrooth Foundation and the Vilho, Yrjö and Kalle Väisälä Foundation of the Finnish Academy of Science and Letters for their support. M.B. and E.C. are ESO fellows. Publisher Copyright: © 2022 EPJ Photovoltaics. All rights reserved.We studied seven nearby narrow-line Seyfert 1 (NLS1) galaxies in J and Ks bands with redshifts varying from 0.019 to 0.092. This is the first multi-source study targeting the hosts of southern NLS1 galaxies. Our data were obtained with the FourStar instrument of the 6.5 m Magellan Baade telescope at the Las Campanas Observatory (Chile). The aim of our study is to determine the host galaxy morphologies of these sources by using GALFIT. We were able to model six out of the seven sources reliably. Our conclusion is that all of the reliably modelled sources are disk-like galaxies, either spirals or lenticulars. None of these sources present an elliptical morphology. Our findings are in agreement with the hypothesis that disk-like galaxies are the main host of jetted NLS1 galaxies. Taking advantage of observations in two bands, we also produced a J-Ks colour map of each source. Five of the six colour maps show significant dust extinction near the core of the galaxy-a feature often seen in gamma-ray-detected jettedNLS1 galaxies, and interpreted to be a consequence of a past minor merger.Peer reviewe

Long-term Swift and Metsähovi monitoring of SDSS J164100.10+345452.7 reveals multi-wavelength correlated variability

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 gamma-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 Gamma = 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 (Gamma(flare) similar to 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 P-jet(tot) = 3.5 x10(42) erg s(-1). This result is close to the lowest values measured in the literature