Beata Malec University of Silesia

Beata MalecUniversity of Silesia

XXXIII International Conference of Theoretical Physics

MATTER TO THE DEEPEST: Recent Developments in Physics of Fundamental Interactions, Ustroń’09

Ustroń, Sept. 16 2009 MATTER TO THE DEEPEST 2

Outline of the talk

Introductory remarks Context - dark matter problem, Astrophysical constraints on exotic physics

White dwarfs in perspectiveG117-B15A as a tool for astroparticle physics

WD constraints on : multidimensional ADD model scalar WIMP-nucleon cross section

Conclusion and perspectives


X-ray emission from clustersGravitational lensing

by galaxies and clusters (giant arcs)

Dark Matter in the UniversePioneers: Oort 1923, Zwicky 1925

Flat rotation curves in galaxies

b = 0.042 m = 0.29 ± 0.04

MODERN COSMOLOGY

BBN

LSS

CMBR

http://antwrp.gsfc.nasa.gov/apod/image/0110/a2218c_hst_big.jpg


Dark Matter in the Universe


Motivation and ideas

Modern astrophysics is a great success of standard physical theories in understanding stellar structure and evolution

Stars serves as a source of constraints on non standard ideas Some of these constraints turn out to be more stringent than

laboratory ones

First idea: weakly interacting particles (axions, Kaluza-Klein gravitons, etc.) produced in hot and dense stellar interior are steaming freely – in effect we have additional cooling channel and modification of evolutional time-scales

Second idea: If a star is immersed in a halo of supersymmetric dark matter it can have consequences on the course of its evolution


Three main source of astrophysical constraints: (previously considered mainly in the context of additional cooling channels)

Sun (helioseismology)

additional cooling – increase of Tc

Globular clusters

main observables

Height of RGB tip above HB

Number density of stars on HB

Supernova 1987A

Duration of pulseEnergy budget

In practice


White dwarfs are degenerate stars , consist of C and O, they could also have thin outher He and H layers.

WD history is simple: the only one thing they can do is to cool down.

Luminosity is fairly well described by Mestel cooling law

Some of them are pulsating stars -

so called ZZ-Ceti variables

dtdTMc

dtdUL WDV

th

asteroseismology - gives opportunity to record many pulsational modes and to measure them with great accuracy

New tool – pulsating White Dwarfs (WD)


From the theory of stellar oscillations it is known that WD can support non radial oscillations

excited g-modes have frequencies (proportional to)

gAdrpd

drdgN

ln1ln

1

2 Brunta-Väisäla frequency

for degenerate electron gas at non-zero temperature:

A~T2 so

1/P ~T then

MTcL

TT

PP

V

inferences

from the rate of period change one can estimate cooling rate

when star is cooling its period increases

How it works?


Pulsating White Dwarf G117-B15A discovered (as variable) in 1976

(McGraw & Robinson)

Global parameters mass 0.59 M0

Teff =11 620 K (Bergeron 1995)

log(L/L0) = -2.8 tzn. L=6.18 1030 erg/s

(McCook & Sion 1999)

R = 9.6 105 cm Tc = 1.2 107 K

Chemical composition:

C:O = 20:80 (Bradley 1995)

C : O = 17 : 83 (Salaris et al. 1997)

Other names

RY LMi

WD 0921+352

Pulsational properties/features:


excited modes – g-modes– non-radial oscilations

215.2 s 271 s 304.4 sKepler et al. 1982

Rate of period change is precisely measured for the mode 215. 2 s

(Kepler et al. 2000) (Kepler et al. 2005)

Change of the period gives information about cooling rate !

2max 2

1 EPPPETCO

1151080.027.4 ssPobs

Systematic effects (secular):


Proper motion van Altena et al. 1995

• residual gravitational contraction – negligibly small

• core crystalization –DAV stars are too hot

• proper motion effect (Pajdosz 1995)

Theoretical prediction of the Salaris (1997) modelCorsico et al. 2001


Excellent agreement between theory and the observed rate of period change-> a source of constraints

It restricts possibility of new energy sources or cooling channels

In the Mestel law approximation

Energetic constraints on exotic sources in G117 – B15A

sergLLX

3010298.1126.0

theor

obsX

PP

LLL

theor

theorobsX P

PPL

MTcL

TT

PP

V

Energetic constraint


World is multidimensional: gravity acts in n+4 dimensions, all other interactions „confined” to 4-dim „brane”

One can build low-energy effective theory of K-K gravitons interacting with S.M. fields[Barger et al. 1999, Cassisi et al. 2000]

emission rate

Observed rate of change of period

Theoretical rate of change of period

3n dla 1074.9 25

491

jjs

eGB Zn

MnT

2n dla1086.5 24

375

jjs

eGB Zn

MnT

nns

Pln

n

MM

cR

2

2

WDM

KK dmL0

sergL

sergL

sergL

GCP

GB

24

212

29

1014.2

1053.4

108

ADD Model

LEP Ms > 1 TeV/c2

SUN Ms > 0,3 TeV/c2

Globular Clusters Ms > 4 TeV/c2

SN1987A Ms > 30-130TeV/c2

WD G117-B15A Ms > 8,8 TeV/c2


Comparison of bounds


Stars are immersed in the Galactic dark halo

What are the consequences ?

Accretion of dark matter


Capture rate

Barometric distribution of WIMPs sets in

Majorana particles - -> annihilate

Stady state: accretion and annihilation rates are equal

Additional luminosity

Spergel & Press 1985Gould 1987

2/1

23

dmc

cx mG

Tr kmrx 82

3ii

i p

WDsieff AX

mM


In the supersymmetric model of WIMPs (neutralino)

One can obtain the upper bound on nucleon scatering cross section

2371008.2 cmsi

Recapitulation

o Pulsating white dwarf G117 – B15A is a nice tool for astroparticle physics:

o Long sequence of observational data (fotometric and spectroscopic)

o Well calibrated astroseismologically

o Pulsational mode 215 s – one of the most stable clocks in nature (the most stable „optical clock”)



2/1

23

dmc

cx mG

Tr

kmr 82x

3ii

i p

WDsieff AX

mM


additional energy loss channel due to KK-graviton emission

relevant process - gravibremsstrahlung in static electric field of ions.

e

e

e

e

ee

e eGkk

Gkk

Gkk

Gkk


specific mass emissivity for this process calculated by Barger et al. Phys Lett B 1999

the upper 2 limit on POBS translates into a bound:

LL

PPMZn

MnTL

O

OBS

jjj

S

eKK

308.011086.5 2

2

375

the final result for the constraint on mass scale MS is:

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