Jun. 27, 2013 - PowerPoint Presentation

Slide1

Jun. 27, 2013 ＠ Baryons2013, Glasgow

Motoi Tachibana (Saga Univ.)

Dark matter

capture in neutron stars with exotic phasesSlide2

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

biologySlide3

I

nteresting

connection

between matters and universe

Dark Matter

and

Neutron Stars

Harmony of particle,

astro

-, and condensed matter physicsSlide4

What/Why dark matter (DM)?

Undoubtedly exists, but properties unknown

Just weakly-interacting with other particles

Proposed by

Zwicky

as missing mass (1934)Slide5

arXiv:1210.0682

What/Why neutron star (NS)?

Landau’s gigantic nucleus

Good market selling ultimate environments

Proposed by Baade and

Zwicky

a

s a remnant after supernova explosion (1934)Slide6

Why their connections?

Possibly constraining WIMP-DM properties via NS

For a typical neutron star,

Way below the CDMS limit!

N

S may constrain the DM properties

CDMSII, 1304.4279Slide7

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　　　 　　　　　　　：

c

f

) 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 starsSlide8

DM capture in NS

*based on paper by McDermott-Yu-

Zurek

(2012)*Slide9

Accretion of DM

Thermalization

of DM (energy loss)

BH formation and destruction of host NS Slide10

(1) DM capture rate

The accretion rate

(A. Gould, 1987)

n

eutron-DM elastic cross sectionSlide11

Capture efficiency

f

actor

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 degeneratedSlide12

(2)

Thermalization

of DM

Thermalization

time scale:

If

δp is less than p , then

After the capture, DMs lose energy via scattering

w

ith neutrons and get thermalized with the star

FSlide13

(3) Self–gravitation & BH formation

If the DM density gets larger than the baryon density

w

ithin thermal

radius, DM particles be self-gravitating.

T

his is the on-set of the gravitational collapse and black-hole formation

(the Chandrasekhar limit)

To avoid destruction of NS,Slide14

Observational constraints

For the case of the pulsar B1620-26:Slide15

So far people have been mainly studyingthe issue from particle physics side.

However, as I told you, hadrons in NS arei

n 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?Slide16

Possible effects① 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.

RuggieriSlide17

SummaryConstraining 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 seriouslyProposal of medium effects for hadrons in NS--modified vacuum structures and collective modes--Slide18

Thank you