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.
Original language | English |
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Article number | 54 |
Number of pages | 7 |
Journal | Frontiers in Astronomy and Space Sciences |
Volume | 4 |
DOIs | |
Publication status | Published - 30 Nov 2017 |
MoE publication type | A2 Review article, Literature review, Systematic review |
Event | Quasars at all cosmic epochs - Padova, Italy Duration: 3 Apr 2017 → 7 Apr 2017 |
Keywords
- active galactic nuclei
- narrow-line Seyfert 1 galaxies
- large-scale environment
- radio loudness
- relativistic jets
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Metsähovi Radio Observatory
Tammi, J. (Manager)
School of Electrical EngineeringFacility/equipment: Facility