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
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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
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Dark Matter in the Universe
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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
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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
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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)
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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?
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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:
Ustroń, Sept. 16 2009 MATTER TO THE DEEPEST 10
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):
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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
Ustroń, Sept. 16 2009 MATTER TO THE DEEPEST 12
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
Ustroń, Sept. 16 2009 MATTER TO THE DEEPEST 13
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
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Comparison of bounds
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Stars are immersed in the Galactic dark halo
What are the consequences ?
Accretion of dark matter
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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
Ustroń, Sept. 16 2009 MATTER TO THE DEEPEST 17
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”)
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Ustroń, Sept. 16 2009 MATTER TO THE DEEPEST 19
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2/1
23
dmc
cx mG
Tr
kmr 82x
3ii
i p
WDsieff AX
mM
Ustroń, Sept. 16 2009 MATTER TO THE DEEPEST 21
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
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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: