A search for planetary companions around 800 pulsars from the Jodrell Bank pulsar timing programme (2203.01136v1)

Abstract: We have searched for planetary companions around 800 pulsars monitored at the Jodrell Bank Observatory, with both circular and eccentric orbits of periods between $20$ days and $17$ years and inclination-dependent planetary masses from $10^{-4}$ to $100\,\mathrm{M}{\oplus}$. Using a Bayesian framework, we simultaneously model pulsar timing parameters and a stationary noise process with a power-law power spectral density. We put limits on the projected masses of any planetary companions, which reach as low as 1/100th of the mass of the Moon ($\sim 10^{-4}\,\mathrm{M}{\oplus}$). We find that two-thirds of our pulsars are highly unlikely to host any companions above $2-8\,\mathrm{M}{\oplus}$. Our results imply that fewer than $0.5\%$ of pulsars could host terrestrial planets as large as those known to orbit PSR B1257$+$12 ($\sim4\,\mathrm{M}{\oplus}$); however, the smaller planet in this system ($\sim0.02\,\mathrm{M}_{\oplus}$) would be undetectable in $95\%$ of our sample, hidden by both instrumental and intrinsic noise processes, although it is not clear if such tiny planets could exist in isolation. We detect significant periodicities in 15 pulsars, however we find that intrinsic quasi-periodic magnetospheric effects can mimic the influence of a planet, and for the majority of these cases we believe this to be the origin of the detected periodicity. Notably, we find that the highly periodic oscillations in PSR B0144$+$59 are correlated with changes in the pulse profile and therefore can be attributed to magnetospheric effects. We believe the most plausible candidate for planetary companions in our sample is PSR J2007$+$3120.

• The paper applies a Bayesian framework to timing data from 800 pulsars, setting mass limits as low as 1/100th of the Moon's mass.
• The study finds that about two-thirds of pulsars are unlikely to host companions above 2–8 Earth masses, with fewer than 0.5% potentially hosting larger planets.
• The research indicates that observed periodicities in some pulsars likely stem from intrinsic magnetospheric effects, challenging traditional planet formation models.

Analyzing Planetary Companions Around Pulsars Using Data from the Jodrell Bank Observatory

In the field of astrophysics, the search for extrasolar planets is a dynamic and evolving field. The paper "A search for planetary companions around 800 pulsars from the Jodrell Bank pulsar timing programme" presents a meticulous investigation into the potential existence of planets orbiting pulsars. Utilizing data from the Jodrell Bank Observatory, the research provides a comprehensive analysis of 800 pulsars, investigating both circular and eccentric orbital configurations with periods ranging from 20 days to 17 years.

The research employs a Bayesian framework to simultaneously model pulsar timing parameters and a stationary noise process characterized by a power-law power spectral density. This dual-model approach effectively limits the projected masses of planetary companions to as low as 1/100th of the Moon's mass (approximately $10^{-4} \mathrm{M}_{\oplus}$). The paper's significant findings indicate that for two-thirds of the analyzed pulsars, there is a low likelihood of hosting companions above 2-8 Earth masses $\mathrm{M}_{\oplus}$.

Contradictory to the existence of terrestrial planets around pulsars, the paper suggests that fewer than 0.5% of pulsars could accommodate planets as large as those orbiting PSR B1257+12 (approximately 4 $\mathrm{M}_{\oplus}$). The smaller planets, such as those of PSR B1257+12 with masses of approximately 0.02 $\mathrm{M}_{\oplus}$, remain undetectable in 95% of the sample due to noise interference. However, it remains uncertain if such diminutive planets could exist without accompanying larger bodies.

A notable aspect of the paper involves detecting significant periodicities in 15 pulsars. The research hypothesizes that these periodicities might arise from intrinsic quasi-periodic magnetospheric effects rather than planetary bodies, as evidenced by similar pulsars with known intrinsic variability. For instance, the paper identifies PSR B0144+59 as exhibiting highly periodic oscillations correlated with changes in its pulse profile, supporting the non-planetary origin hypothesis. The most plausible candidate within the dataset for hosting a planetary companion is PSR J2007+3120, but even this is tempered by other plausible interpretations.

From a theoretical perspective, the implications of this paper suggest that pulsar planetary systems akin to PSR B1257+12 are exceedingly rare. This scarcity aligns with the hypothesis that the extreme conditions surrounding pulsar formation are not conducive to planet formation, thereby challenging certain orbital models and formation scenarios that include fallback disks or disrupted stellar companions.

The research offers a crucial foundation for understanding the dynamics of exoplanetary presence around pulsars. In practical terms, the enhanced sensitivity techniques and advanced data analysis approach, incorporating Bayesian statistics, could guide future observational strategies. The examination of pulsar timing data continues to be an invaluable tool in the search for extraterrestrial bodies, and the methodologies adopted in this analysis pave the way for future explorations with forthcoming, more sensitive instrumentation like the Square Kilometre Array.

As pulsar timing and planetary detection techniques further evolve, they are likely to provide sharper insights into pulsar systems and the potential planets that may inhabit the universe, offering fresh avenues for the continuation of these searches in more nuanced and probabilistically robust frameworks.