May 15 – 17, 2026
College of Hakka Studies at NYCU, Zhubei, Hsinchu County 國立陽明交通大學客家學院(竹北六家校區)
Asia/Taipei timezone

Estimating the number density of ORCs in the AGN scenario

May 16, 2026, 11:00 AM
15m
HK105

HK105

Oral Galaxies

Speaker

Guan-Hong Li (National Tsing Hua University)

Description

This study investigates the origin of Odd Radio Circles (ORCs) by modeling them as remnants of active galactic nucleus (AGN) feedback using the JET semi-analytical framework. Motivated by observed host galaxy properties and recent simulations suggesting that ORCs represent relics of AGN activity following a phase of rapid supermassive black hole (SMBH) growth, we identify candidate hosts with stellar masses of 10^11-10^11.5 M_⊙ and black hole masses of 10^7.5-10^8.7 M_⊙ in a radiatively inefficient accretion state. By applying the Sheth-Tormen halo mass function, we calculate predicted numbers as a function of redshift, finding a stable distribution within 10^12-10^13 M_⊙ halos for 1 ≤ z ≤ 3. Crucially, the model yields predicted number densities at z < 1 that are of the same order of magnitude as observed counts and recent estimates (de Gasperin et al. 2026), with predicted numbers as a function of redshift providing a predictive roadmap for future deep-field radio surveys. These findings strongly support the hypothesis that ORCs are long-lived remnants of powerful AGN jets.

Participate the oral/poster presentation award competition Yes

Author

Guan-Hong Li (National Tsing Hua University)

Co-authors

Presentation materials

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