Varstrometry Selected Radio-Loud Candidates of Dual and Off-Nucleus Quasars at Sub-kpc Scales

Fuente: arXiv
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Autores principales: Wang, Hao-Chen, Wang, Jun-Xian, Gu, Min-Feng, Liao, Mai
Formato: Preprint
Publicado: 2023
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author Wang, Hao-Chen
Wang, Jun-Xian
Gu, Min-Feng
Liao, Mai
author_facet Wang, Hao-Chen
Wang, Jun-Xian
Gu, Min-Feng
Liao, Mai
contents Dual super massive black holes at sub-kpc to kpc scales, the product of galaxy mergers, are progenitors of eventually coalescing binary SMBHs. If both or one of the dual SMBHs are accreting, they may appear as dual AGNs or off-nucleus AGNs. Studying such systems is essential to learn the dynamical evolution of binary SMBHs as well as the process of galaxy merging. Recently a novel astrometry-based method named varstrometry has been put forward to search for dual SMBHs at high redshift, as the unsynchronized flux variability of dual AGNs (or off-nucleus AGNs) will cause astrometric jitters detectable by Gaia without spatially resolving them. Based on Gaia varstrometry we select a rare sample of 5 radio loud quasars with clear Gaia astrometric jitters. With e-MERLIN observations we have revealed a single compact radio source for each of them. Remarkably all but one exhibit clear Gaia-radio offsets of ~ 7 -- 40 mas. The observed Gaia jitters appear consistent with the expected values. These detected Gaia-radio offsets suggest these candidate dual SMBHs may have projected separations as small as ~ 0.01 -- 0.1'' (~ 0.1 kpc, depending on the optical flux ratio of two SMBHs). Meanwhile, this work highlights the remarkably high efficiency of Gaia varstrometry selection of jittering sources.
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institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Varstrometry Selected Radio-Loud Candidates of Dual and Off-Nucleus Quasars at Sub-kpc Scales
Wang, Hao-Chen
Wang, Jun-Xian
Gu, Min-Feng
Liao, Mai
Astrophysics of Galaxies
Dual super massive black holes at sub-kpc to kpc scales, the product of galaxy mergers, are progenitors of eventually coalescing binary SMBHs. If both or one of the dual SMBHs are accreting, they may appear as dual AGNs or off-nucleus AGNs. Studying such systems is essential to learn the dynamical evolution of binary SMBHs as well as the process of galaxy merging. Recently a novel astrometry-based method named varstrometry has been put forward to search for dual SMBHs at high redshift, as the unsynchronized flux variability of dual AGNs (or off-nucleus AGNs) will cause astrometric jitters detectable by Gaia without spatially resolving them. Based on Gaia varstrometry we select a rare sample of 5 radio loud quasars with clear Gaia astrometric jitters. With e-MERLIN observations we have revealed a single compact radio source for each of them. Remarkably all but one exhibit clear Gaia-radio offsets of ~ 7 -- 40 mas. The observed Gaia jitters appear consistent with the expected values. These detected Gaia-radio offsets suggest these candidate dual SMBHs may have projected separations as small as ~ 0.01 -- 0.1'' (~ 0.1 kpc, depending on the optical flux ratio of two SMBHs). Meanwhile, this work highlights the remarkably high efficiency of Gaia varstrometry selection of jittering sources.
title Varstrometry Selected Radio-Loud Candidates of Dual and Off-Nucleus Quasars at Sub-kpc Scales
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2306.03357