Constraining the PG 1553+113 binary hypothesis: interpreting hints of a new, 22-year period

Fuente: arXiv
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Main Authors: Adhikari, Sagar, Penil, Pablo, Westernacher-Schneider, John Ryan, Dominguez, Alberto, Ajello, Marco, Buson, Sara, Rico, Alba, Zrake, Jonathan
Format: Preprint
Published: 2023
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author Adhikari, Sagar
Penil, Pablo
Westernacher-Schneider, John Ryan
Dominguez, Alberto
Ajello, Marco
Buson, Sara
Rico, Alba
Zrake, Jonathan
author_facet Adhikari, Sagar
Penil, Pablo
Westernacher-Schneider, John Ryan
Dominguez, Alberto
Ajello, Marco
Buson, Sara
Rico, Alba
Zrake, Jonathan
contents PG 1553+113 is a well-known blazar exhibiting evidence of a $\sim\! 2.2$-yr quasi-periodic oscillation (QPO) in radio, optical, X-ray, and $γ$-ray bands. Since QPO mechanisms often predict multiple QPOs, we search for a second QPO in its historical optical light curve covering a century of observations. Despite challenging data quality issues, we find hints of a $21.8 \pm 4.7$ yr oscillation. On its own, this $\sim\! 22$-yr period has a modest statistical significance of $1.6σ$ when accounting for the look-elsewhere effect. However, the joint significance of both the $2.2$- and $22$-yr periods arising from colored noise alone is $\sim 3.6σ$. The next peak of the 22-yr oscillation is predicted to occur around July 2025. We find that such a $\sim\,$10:1 relation between two periods can arise in the gas dynamics of a plausible supermassive black hole binary model of PG 1553+113. While the 22-yr QPO is preliminary, an interpretation of PG 1553+113's two QPOs in this binary model suggests that the binary engine has a mass ratio $\gtrsim 0.2$, an eccentricity $\lesssim 0.1$, and accretes from a disk with characteristic aspect ratio $\sim 0.03$. The putative binary radiates nHz gravitational waves, but the amplitude is $\sim10-100$ times too low for detection by foreseeable pulsar timing arrays.
format Preprint
id arxiv_https___arxiv_org_abs_2307_11696
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Constraining the PG 1553+113 binary hypothesis: interpreting hints of a new, 22-year period
Adhikari, Sagar
Penil, Pablo
Westernacher-Schneider, John Ryan
Dominguez, Alberto
Ajello, Marco
Buson, Sara
Rico, Alba
Zrake, Jonathan
High Energy Astrophysical Phenomena
Astrophysics of Galaxies
PG 1553+113 is a well-known blazar exhibiting evidence of a $\sim\! 2.2$-yr quasi-periodic oscillation (QPO) in radio, optical, X-ray, and $γ$-ray bands. Since QPO mechanisms often predict multiple QPOs, we search for a second QPO in its historical optical light curve covering a century of observations. Despite challenging data quality issues, we find hints of a $21.8 \pm 4.7$ yr oscillation. On its own, this $\sim\! 22$-yr period has a modest statistical significance of $1.6σ$ when accounting for the look-elsewhere effect. However, the joint significance of both the $2.2$- and $22$-yr periods arising from colored noise alone is $\sim 3.6σ$. The next peak of the 22-yr oscillation is predicted to occur around July 2025. We find that such a $\sim\,$10:1 relation between two periods can arise in the gas dynamics of a plausible supermassive black hole binary model of PG 1553+113. While the 22-yr QPO is preliminary, an interpretation of PG 1553+113's two QPOs in this binary model suggests that the binary engine has a mass ratio $\gtrsim 0.2$, an eccentricity $\lesssim 0.1$, and accretes from a disk with characteristic aspect ratio $\sim 0.03$. The putative binary radiates nHz gravitational waves, but the amplitude is $\sim10-100$ times too low for detection by foreseeable pulsar timing arrays.
title Constraining the PG 1553+113 binary hypothesis: interpreting hints of a new, 22-year period
topic High Energy Astrophysical Phenomena
Astrophysics of Galaxies
url https://arxiv.org/abs/2307.11696