Dark matter capture in neutron stars inconstraints neutron

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

Why their connections? Possibly constraining WIMP-DM properties via NS CDMSII, 1304. 4279 Way below the CDMS limit! For a typical neutron star,

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. cosmion W. Press and D. Spergel (1984)

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

(1) Accretion of DM (1) Thermalization of DM (energy loss) (2) BH formation and destruction of host NS condition of self-gravitation

Capturable number of DMs in NS Capture rate via DM-neutron scattering Capture rate via DM-DM self-interaction DM pair annihilation rate

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

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

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

(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 of the gravitational collapse and black-hole formation (cf. the Chandrasekhar limit) BH formation is the dynamical issue and not so trivial to deal with

Condition

Observational constraints For the case of the pulsar B 1620 -26: Mc. Dermott-Yu-Zurek (2012)

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?

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

Bertoni, Nelson and Reddy, 1309. 1721[hep-ph]

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

Thank you