Motoi Tachibana (Saga Univ.)

1. Dark matter capture in neutron stars with exotic phases Dark matter capture in neutron stars -stellar constraints on dark matter- Motoi Tachibana (Saga Univ.) Oct. 25, 2013 ＠ NS matter symposium, Kyoto

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

3. Impacts of dark matter on NS • NS mass-radius relation with dark matter EOS • NS heating via dark matter annihilation ： • Dark matter capture in NS and formation of black-hole to collapse host 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) cosmion

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

5. Accretion of DM Thermalization of DM (energy loss) BH formation and destruction of host NS condition of self-gravitation

6. Capturable number of DMs in NS Capture rate via DM-neutronscattering Capture rate via DM-DM self-interaction DM pair annihilation rate

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

8. 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

9. (2) Thermalization of DM After the capture, DMs lose energy via scattering with neutrons and eventually get thermalized DMmass ≦ 1GeV, DMmass ≧ 1GeV,

10. (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 (cf. theChandrasekhar limit) BH formation is the dynamical issue and not so trivial to deal with

11. Condition

12. Observational constraints For the case of the pulsar B1620-26: McDermott-Yu-Zurek (2012)

13. NS as Landau’s gigantic nucleus So far people have been mainly studying the issue from particle physics side. However, hadrons in NS are in EXTREME, and exotic matter states could appear. (e.g.) neutron superfluidity Bose condensation of mesons superconductivity of quarks What if those effects are incorporated?

14. Possible effects ①Modification of capture efficiency via energy gap ② Modification of low-energy effective theory (e.g.) color-flavor-locked(CFL) quark matter sizable effect? (e.g.) neutron superfluidity dominant d.o.f. is a superfluid phonon. Cirigliano, Reddy, Sharma (2011) We are on the way of the calculations

15. Bertoni, Nelson and Reddy, 1309.1721[hep-ph]

16. Summary Stellar constraints on dark matter properties 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-- This is OUR problem

17. Thank you