Dark matter capture in neutron stars with exotic

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

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

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

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

What/Why neutron star (NS)? Proposed bygigantic Baade and Zwicky Landau’s nucleus as. Good a remnant supernova (1934) marketafter selling ultimate explosion environments ar. Xiv: 1210. 0682

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

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]

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

(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 get thermalized with the star Thermalization time scale: If δp is less than p , then F

(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 (the Chandrasekhar limit) To avoid destruction of NS,

Observational constraints For the case of the pulsar B 1620 -26:

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?

Possible effects On-going project w/ M. Ruggieri ① Modification of capture efficiency via energy gap (e. g. ) color-flavor-locked(CFL) quark matter larger suppression 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

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--

Thank you