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On the Effects of Local Environment on Active Galactic Nucleus (AGN) in the Horizon Run 5 Simulation

Singh, Ankit; Park, Changbom; Choi, Ena; Kim, Juhan; Jun, Hyunsung; Gibson, Brad K.; Kim, Yonghwi; Lee, Jaehyun; Snaith, Owain


Ankit Singh

Changbom Park

Ena Choi

Juhan Kim

Hyunsung Jun

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Professor Brad Gibson
Head of Physics; Director, E.A. Milne Centre for Astrophysics; Director of Research, Natural Sciences; Interim Associate Dean , Science & Engineering

Yonghwi Kim

Jaehyun Lee

Owain Snaith


We use the Horizon Run 5 cosmological simulation to study the effect of galaxy intrinsic properties and the local environment on active galactic nuclei (AGNs) characterized by their threshold of the accretion rate. We select galaxies in the stellar mass range 10 9.5 ≤ M * / M ⊙ ≤ 10 10.5 in the snapshot at redshift z = 0.625. Among various intrinsic properties, we find that the star formation rate of the host galaxy is most correlated to the AGN activity. To quantify the environment, we use background galaxy number density (large-scale environment) and distance and morphological type of the nearest neighbors (small-scale environment), and study their relative effects on the AGN properties. We find that, compared to the background density, the nearest neighbor environment is the dominant quantity determining the bolometric luminosity, star formation rate, and kinematic properties of AGNs and better dictates the gas mass of the host galaxy. We show that the cold gas content in the host galaxies is crucial in triggering AGN activity. However, when the nearest neighbor environment effects start to act at the neighbor distance of less than about half the virial radius of the neighbor, the neighbor environmental effects are the most dominant factor for quasar activity.


Singh, A., Park, C., Choi, E., Kim, J., Jun, H., Gibson, B. K., …Snaith, O. (2023). On the Effects of Local Environment on Active Galactic Nucleus (AGN) in the Horizon Run 5 Simulation. The Astrophysical journal, 953(1), Article 64.

Journal Article Type Article
Acceptance Date Jun 9, 2023
Online Publication Date Aug 2, 2023
Publication Date Aug 10, 2023
Deposit Date Aug 25, 2023
Publicly Available Date Aug 29, 2023
Journal Astrophysical Journal
Print ISSN 0004-637X
Electronic ISSN 1538-4357
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 953
Issue 1
Article Number 64
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Copyright Statement
&copy; 2023. The Author(s). Published by the American Astronomical Society.<br /> Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

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