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

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

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 Just weakly-interacting with other particles Proposed by Zwicky as missing mass (1934)

arXiv: 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)

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

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 ： 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] (Asymmetric) dark matter capture in NS and black hole formation to collapse neutron stars

DM capture in NS *based on paper by McDermott-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 (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 In NS, neutrons are highly degenerated

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

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

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