Large-Scale Environment Properties of Narrow-Line Seyfert 1 Galaxies at z < 0.4
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© 2017 Järvelä, Lähteenmäki and Lietzen. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
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A2 Katsausartikkeli tieteellisessä aikakauslehdessä
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Date
2017-11-30
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Language
en
Pages
7
Series
Frontiers in Astronomy and Space Sciences, Volume 4
Abstract
The large-scale environment is believed to affect the evolution and intrinsic properties of galaxies. It offers a new perspective on narrow-line Seyfert 1 galaxies (NLS1) which have not been extensively studied in this context before. We study a large and diverse sample of 960 NLS1 galaxies using a luminosity-density field constructed using Sloan Digital Sky Survey. We investigate how the large-scale environment is connected to the properties of NLS1 galaxies, especially their radio loudness. Furthermore, we compare the large-scale environment properties of NLS1 galaxies with other active galactic nuclei (AGN) classes, for example, other jetted AGN and broad-line Seyfert 1 (BLS1) galaxies, to shed light on their possible relations. In general NLS1 galaxies reside in less dense large-scale environments than any of our comparison samples, thus supporting their young age. The average luminosity-density and distribution to different luminosity-density regions of NLS1 sources is significantly different compared to BLS1 galaxies. This contradicts the simple orientation-based unification of NLS1 and BLS1 galaxies, and weakens the hypothesis that BLS1 galaxies are the parent population of NLS1 galaxies. The large-scale environment density also has an impact on the intrinsic properties of NLS1 galaxies; the radio loudness increases with the increasing luminosity-density. However, our results suggest that the NLS1 population is indeed heterogeneous, and that a considerable fraction of them are misclassified. We support a suggested description that the traditional classification based on the radio loudness should be replaced with the division to jetted and non-jetted sources.Description
Keywords
active galactic nuclei, narrow-line Seyfert 1 galaxies, large-scale environment, radio loudness, relativistic jets
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Citation
Järvelä, E, Lähteenmäki, A & Lietzen, H 2017, ' Large-Scale Environment Properties of Narrow-Line Seyfert 1 Galaxies at z < 0.4 ', Frontiers in Astronomy and Space Sciences, vol. 4, 54 . https://doi.org/10.3389/fspas.2017.00054