Astro-quark matter: a challenge facing astroparticle physics

Quark matter both in terrestrial experiment and in astrophysics is briefly reviewed. Astrophysical quark matter could appear in the early Universe, in compact stars, and as cosmic rays. Emphasis is put on quark star as the nature of pulsars. Possible astrophysical implications of experiment-discovered sQGP are also concisely discussed.Comment: 14 pages, 4 figures and 1 table; talk presented at CosPA2007 (International Symposium on Cosmology and Particle Astrophysics, Taipei, Nov. 13-15, 2007

Trinity of Strangeon Matter

Strangeon is proposed to be the constituent of bulk strong matter, as an analogy of nucleon for an atomic nucleus. The nature of both nucleon matter (2 quark flavors, u and d) and strangeon matter (3 flavors, u, d and s) is controlled by the strong-force, but the baryon number of the former is much smaller than that of the latter, to be separated by a critical number of $A_{\rm c}\sim 10^9$. While micro nucleon matter (i.e., nuclei) is focused by nuclear physicists, astrophysical/macro strangeon matter could be manifested in the form of compact stars (strangeon star), cosmic rays (strangeon cosmic ray), and even dark matter (strangeon dark matter). This trinity of strangeon matter is explained, that may impact dramatically on today's physics.Comment: Xiamen-CUSTIPEN whorkshop on the EoS of dense matter (3-7 January 2019

PSR B1257+12: a quark star with planets?

A recent observation has shown that PSR B1257+12 could have quite small X-ray emitting area, only about 2000 m$^2$, which is more than three orders smaller than the canonical polar cap size. We suggest here that PSR B1257+12 could be a low-mass quark star with radius of $R \simeq 0.6$ km and mass of M \simeq 3\times10^{-4}\msun. Such a low-mass quark star system may form in an accretion induced collapse process or a collision process of two quark stars.Comment: 3 pages, 1figure, poster at the international conference "Astrophysics of Compact Objects" (July 1-7, 2007, Huangshan, China