claim pulsar system of evidence for phase transition in pulsar

[notFritzArgelander]

https://phys.org/news/2021-06-astronome ... r-psr.html

the system is odd. this would be a first, a neutron star transitioning to a strange star.

https://en.wikipedia.org/wiki/Strange_star

More later after I read the paper.

[notFritzArgelander]

This is good work!

https://arxiv.org/abs/2106.05717

PSR J1946+3417 is a millisecond pulsar (MSP) with a spin period P≃3.17 ms. Harbored in a binary with an orbital period Pb≃27 days, the MSP is accompanied by a white dwarf (WD). The masses of the MSP and the WD were determined to be 1.83 M⊙ and 0.266 M⊙, respectively. Specially, its orbital eccentricity is e≃0.134, which is challenging the recycling model of MSPs. Assuming that the neutron star in a binary may collapse to a strange star when its mass reaches a critical limit, we propose a phase transition (PT) scenario to account for the origin of the system. The sudden mass loss and the kick induced by asymmetric collapse during the PT may result in the orbital eccentricity. If the PT event takes place after the mass transfer ceases, the eccentric orbit can not be re-circularized in the Hubble time. Aiming at the masses of both components, we simulate the evolution of the progenitor of PSR J1946+3417 via \texttt{MESA}. The simulations show that a NS / main sequence star binary with initial masses of 1.4+1.6 M⊙ in an initial orbit of 2.59 days will evolve into a binary consisting of a 2.0 M⊙ MSP and a 0.27 M⊙ WD in an orbit of ∼21.5 days. Assuming that the gravitational mass loss fraction during PT is 10%, we simulate the effect of PT via the kick program of \texttt{BSE} with a velocity of σPT=60 km s−1. The results show that the PT scenario can reproduce the observed orbital period and eccentricity with higher probability then other values.

Bolding is my emphasis. The eccentricity is very unlikely original. Tidal dampening would circularize an initially eccentric orbit. The energetics, a loss of 10% of gravitational mass due to the phase transition, is on the order of what a SN releases in forming a neutron star.
So this is the first credible scenario by which observation provides a clue to the existence of matter at higher than neutron star density. I particularly like that they didn't just run a bunch of computer simulations, there was a serious analytic effort too provide formulae that constrain the phenomenon.

The phase transition happens in the core. The accretion column provides an external asymmetry that provides the velocity kick into the eccentric orbit.

[turboscrew]

Quite exciting! Probably more work is needed to confirm that (beyound reasonable doubt).

[helicon]

Thanks for sharing the article notFritz. Very interesting.