Searching for strange quark matter objects in exoplanets [HEAP]

The true ground state of hadronic matter may be strange quark matter (SQM). According to this hypothesis, the observed pulsars, which are generally deemed as neutron stars, may actually be strange quark stars. However, proving or disproving the SQM hypothesis still remains to be a difficult problem, due to the similarity between the macroscopical characteristics of strange quark stars and neutron stars. Here we propose a hopeful method to probe the existence of strange quark matter. In the frame work of the SQM hypothesis, strange quark dwarfs and even strange quark planets can also stably exist. Noting that SQM planets will not be tidally disrupted even when they get very close to their host stars due to their extreme compactness, we argue that we could identify SQM planets by searching for very close-in planets among extrasolar planetary systems. Although a search in the $\sim 2950$ exoplanets detected so far has failed to identify any close-in samples that meet the SQM criteria, i.e. lying in the tidal disruption region for normal matter planets, we suggest that such an effort deserves to be continued in the future since it provides a unique test for the SQM hypothesis. Especially, we should keep our eyes on possible pulsar planets with orbital radius less than $\sim 3.8 \times 10^{10}$~cm and period less than $\sim 3400$~s.

Read this paper on arXiv…

Y. Huang and Y. Yu
Tue, 28 Feb 17

Comments: 13 pages, 6 figures included, submitted