Jun. 27, 2013 ＠ Baryons2013, Glasgow

1. Dark matter capture in neutron stars with exotic phases Motoi Tachibana (Saga Univ.) Jun. 27, 2013 ＠ Baryons2013, Glasgow

2. A modern physics perspective Universe Galaxy Particles Stars cosmology nuclear particle physics astro physics Sun Nuclei chemistry biology Earth Atom Mountain DNA Human “UROBOROS” = unity of matters & universe

3. Interesting connection between matters and universe Dark Matter and Neutron Stars Harmony of particle, astro-, and condensed matter physics

4. Proposed by Zwicky as missing mass (1934) What/Why dark matter (DM)? Undoubtedly exists, but properties unknown Just weakly-interacting with other particles

5. What/Why neutron star (NS)? Landau’s gigantic nucleus Good market selling ultimate environments Proposed by Baade and Zwicky as a remnant after supernova explosion (1934) arXiv:1210.0682

6. Why their connections? Possibly constraining WIMP-DM properties via NS CDMSII, 1304.4279 For a typical neutron star, Way below the CDMS limit! NS may constrain the DM properties

7. Constraining the dark matter mass and its scattering cross section through the impacts on neutron stars • Mass-radius relation with the DM EOS • Cooling in the presence of dark matter ： • (Asymmetric) dark matter capture in NS and black hole formation to collapse neutron stars cf) This is not so a new idea. People have considered the DM capture by Sun and the Earth since 80’s. [W. Press and D. Spergel (1984) etc]

8. * DM capture in NS *based on paper by McDermott-Yu-Zurek(2012)

9. Accretion of DM Thermalization of DM (energy loss) BH formation and destruction of host NS

10. (1) DM capture rate The accretion rate (A. Gould, 1987) neutron-DM elastic cross section

11. Capture efficiency factor ξ In NS, neutrons are highly degenerated (i) If momentum transfer δp is less than p , only neutrons with momentum larger than p -δp can participate in (ii) If not, all neutrons can join F F

12. (2) Thermalization of DM After the capture, DMs lose energy via scattering with neutrons and get thermalized with the star Thermalization time scale: If δpis less than p , then F

13. (3) Self–gravitation & BH formation If the DM density gets larger than the baryon density within thermal radius, DM particles be self-gravitating. This is the on-set ofthe gravitational collapse and black-hole formation (theChandrasekhar limit) To avoid destruction of NS,

14. Observational constraints For the case of the pulsar B1620-26:

15. An idea So far people have been mainly studying the issue from particle physics side. However, as I told you, hadrons in NS are in EXTREME, and exotic phases could appear. (e.g.) neutron superfluidity Bose condensation of mesons superconductivity of quarks What if those effects are incorporated?

16. Possible effects On-going project w/ M. Ruggieri ①Modification of capture efficiency via energy gap ② Modification of low-energy effective theory (e.g.) color-flavor-locked(CFL) quark matter larger suppression (e.g.) neutron superfluidity dominant d.o.f. is a superfluid phonon. Cirigliano, Reddy, Sharma (2011) We are on the way of the calculations

17. Summary Constraining dark matter properties via neutron star --dark matter capture in neutron stars— Accretion, thermalization and on-set of BH formation Models for DM, but not considering NS seriously Proposal of medium effects for hadrons in NS --modified vacuum structures and collective modes--

18. Thank you