Finding binary active galactic nuclei by the centroid shift in imaging surveys
Abstract
The census of binary active galactic nuclei (AGNs) is important in order to understand the merging history of galaxies and the strength of gravitational-wave background. However, there is still no efficient method for selecting the candidates of binary AGNs. The non-synchronous variations or the color difference of the two AGNs in one binary system will induce the shift of the image centroid. Since the astrometric error is normally much smaller than the angular resolution of telescopes, it is possible to detect such shifts even in the unresolved system via multi-epoch observations. We perform some simulations and employ a known binary AGN (SDSS J233635.75-010733.7) to verify the functioning of this method. This method is suitable for the future large-scale surveys, e.g., the Large Synoptic Survey Telescope, and it would lead to a large sample of binary AGNs with a 1-2 yr survey. Please see more details in Liu, Y. 2015, A&A, 580, A133 and Liu, Y. 2016, A&A, 592, L4.
- Publication:
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43rd COSPAR Scientific Assembly. Held 28 January - 4 February
- Pub Date:
- January 2021
- Bibcode:
- 2021cosp...43E1576L