A Far-Infrared Search for Planet Nine Using AKARI All-Sky Survey

Fuente: arXiv
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Auteurs principaux: Chen, Amos Y. -A., Goto, Tomotsugu, Yamamura, Issei, Nakagawa, Takao, Wu, Cossas K. -W., Phan, Terry Long, Hashimoto, Tetsuya, Uno, Yuri, Ho, Simon C. -C., Kim, Seong Jin
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Publié: 2025
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author Chen, Amos Y. -A.
Goto, Tomotsugu
Yamamura, Issei
Nakagawa, Takao
Wu, Cossas K. -W.
Phan, Terry Long
Hashimoto, Tetsuya
Uno, Yuri
Ho, Simon C. -C.
Kim, Seong Jin
author_facet Chen, Amos Y. -A.
Goto, Tomotsugu
Yamamura, Issei
Nakagawa, Takao
Wu, Cossas K. -W.
Phan, Terry Long
Hashimoto, Tetsuya
Uno, Yuri
Ho, Simon C. -C.
Kim, Seong Jin
contents An unusual orbital element clustering of Kuiper belt objects (KBOs) has been observed. The most promising dynamic solution is the presence of a giant planet in the outer Solar system, Planet Nine. However, due to its extreme distance, intensive searches in optical have not been successful. We aim to find Planet Nine in the far-infrared, where it has the peak of the black body radiation, using the most sensitive all-sky far-infrared survey to date, AKARI. In contrast to optical searches, where the energy of reflected sunlight decreases by $d^{4}$, thermal radiation in the infrared decreases with the square of the heliocentric distance $d^{2}$. We search for moving objects in the AKARI Single Scan Detection List. We select sources from a promising region suggested by an N-body simulation from Millholland and Laughlin 2017: $30^{\circ}<$ R.A. $<50^{\circ}$ and $-20^{\circ}<$ Dec. $<20^{\circ}$. Known sources are excluded by cross-matching AKARI sources with 9 optical and infrared catalogues. Furthermore, we select sources with small background strength to avoid sources in the cirrus. Since Planet Nine is stationary in a timescale of hours but moves on a monthly scale, our primary strategy is to select slowly moving objects that are stationary in 24 hours but not in six months, using multiple single scans by AKARI. The selected slowly moving AKARI sources are scrutinised for potential contamination from cosmic rays. Our analysis reveals two possible Planet Nine candidates whose positions and flux are within the theoretical prediction ranges. These candidates warrant further investigation through follow-up observations to confirm the existence and properties of Planet Nine.
format Preprint
id arxiv_https___arxiv_org_abs_2506_12854
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A Far-Infrared Search for Planet Nine Using AKARI All-Sky Survey
Chen, Amos Y. -A.
Goto, Tomotsugu
Yamamura, Issei
Nakagawa, Takao
Wu, Cossas K. -W.
Phan, Terry Long
Hashimoto, Tetsuya
Uno, Yuri
Ho, Simon C. -C.
Kim, Seong Jin
Earth and Planetary Astrophysics
Instrumentation and Methods for Astrophysics
Solar and Stellar Astrophysics
An unusual orbital element clustering of Kuiper belt objects (KBOs) has been observed. The most promising dynamic solution is the presence of a giant planet in the outer Solar system, Planet Nine. However, due to its extreme distance, intensive searches in optical have not been successful. We aim to find Planet Nine in the far-infrared, where it has the peak of the black body radiation, using the most sensitive all-sky far-infrared survey to date, AKARI. In contrast to optical searches, where the energy of reflected sunlight decreases by $d^{4}$, thermal radiation in the infrared decreases with the square of the heliocentric distance $d^{2}$. We search for moving objects in the AKARI Single Scan Detection List. We select sources from a promising region suggested by an N-body simulation from Millholland and Laughlin 2017: $30^{\circ}<$ R.A. $<50^{\circ}$ and $-20^{\circ}<$ Dec. $<20^{\circ}$. Known sources are excluded by cross-matching AKARI sources with 9 optical and infrared catalogues. Furthermore, we select sources with small background strength to avoid sources in the cirrus. Since Planet Nine is stationary in a timescale of hours but moves on a monthly scale, our primary strategy is to select slowly moving objects that are stationary in 24 hours but not in six months, using multiple single scans by AKARI. The selected slowly moving AKARI sources are scrutinised for potential contamination from cosmic rays. Our analysis reveals two possible Planet Nine candidates whose positions and flux are within the theoretical prediction ranges. These candidates warrant further investigation through follow-up observations to confirm the existence and properties of Planet Nine.
title A Far-Infrared Search for Planet Nine Using AKARI All-Sky Survey
topic Earth and Planetary Astrophysics
Instrumentation and Methods for Astrophysics
Solar and Stellar Astrophysics
url https://arxiv.org/abs/2506.12854