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Transcript
Beata Malec
University of Silesia
XXXIII International Conference of Theoretical Physics
MATTER TO THE DEEPEST: Recent Developments in Physics of
Fundamental Interactions, Ustroń’09
Outline of the talk
Introductory remarks
Context - dark matter problem,
Astrophysical constraints on exotic physics
White dwarfs in perspective
G117-B15A as a tool for astroparticle physics
WD constraints on :
multidimensional ADD model
scalar WIMP-nucleon cross section
Conclusion and perspectives
Ustroń, Sept. 16 2009
MATTER TO THE DEEPEST
2
Dark Matter in the Universe
Pioneers: Oort 1923, Zwicky 1925
X-ray emission from clusters
MODERN
COSMOLOGY
Flat rotation curves in galaxies
Gravitational lensing by
galaxies and clusters
(giant arcs)
LSS
CMBR
BBN
b = 0.042
Ustroń, Sept. 16 2009
m = 0.29 ± 0.04
MATTER TO THE DEEPEST
3
Dark Matter in the Universe
Ustroń, Sept. 16 2009
MATTER TO THE DEEPEST
4
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
Ustroń, Sept. 16 2009
MATTER TO THE DEEPEST
5
In practice
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  pulse
Energy budget
Ustroń, Sept. 16 2009
MATTER TO THE DEEPEST
6
New tool – pulsating White Dwarfs (WD)
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
dU
dT
th
L

 

c
M
V
WD
dt
dt
Some of them are pulsating stars so called ZZ-Ceti variables
 asteroseismology - gives opportunity to record many pulsational modes and
to measure them with great accuracy
Ustroń, Sept. 16 2009
MATTER TO THE DEEPEST
7
How it works?
From the theory of stellar oscillations it is known that WD can support non
radial oscillations
excited g-modes have frequencies (proportional to)
Brunta-Väisäla frequency



d
ln
1
d
ln
p


N


g



gA
dr


1dr


2
for degenerate electron gas at non-zero temperature:
A~T2
1/P ~T
so
then
P
T
L
 
P
T
cV MT
inferences
 from the rate of period change one can estimate cooling rate
 when star is cooling its period increases
Ustroń, Sept. 16 2009
MATTER TO THE DEEPEST
8
Pulsating White Dwarf G117-B15A
 discovered (as variable) in 1976
(McGraw & Robinson)
Other names
RY LMi
 Global parameters
 mass 0.59 M0
 Teff =11 620 K (Bergeron 1995)
 log(L/L0) = -2.8
tzn. L=6.18 1030 erg/s
WD 0921+352
(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)
Ustroń, Sept. 16 2009
MATTER TO THE DEEPEST
9
Pulsational properties/features:
excited modes – g-modes– non-radial oscilations
215.2 s
271 s
Kepler et al. 1982
304.4 s
Rate of period change is precisely measured
for the mode 215. 2 s
12


O

C


T


PE

P
P
E
max
(Kepler et al. 2000)
2
(Kepler et al. 2005)
Pobs  4.27  0.801015 ss 1
Change of the period gives information about cooling rate !
Ustroń, Sept. 16 2009
MATTER TO THE DEEPEST
10
Systematic effects (secular):
• residual gravitational contraction – negligibly small
• core crystalization –DAV stars are too hot
• proper motion effect (Pajdosz 1995)
Proper motion van Altena et al. 1995
Theoretical prediction of
the Salaris (1997) model
Corsico et al. 2001
Ustroń, Sept. 16 2009
MATTER TO THE DEEPEST
11
Energetic constraint
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
L  LX
L
Pobs

Ptheor
P
T
L
 
P
T
cV MT
 P

P
obs theor
L
X

P
theor
Energetic constraints on exotic sources in G117 – B15A
erg
L

0
.
126
L

1
.
298

10
X
s
30
Ustroń, Sept. 16 2009
MATTER TO THE DEEPEST
12
ADD Model
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
T
n

5
.
86

10
n
Z

dla
n

2


M
T
n

9
.
74

10

n
Z

dla
n

3


M
GB
GB
3

75
2
e
4 jj
s
4

91
2
e
5 jj
s
LKK 
M WD
  dm
0
Observed rate
of change of
period
erg
s
erg
L2  4.531021
s
erg
LGCP  2.141024
s
LGB  81029
Ustroń, Sept. 16 2009
n
2

 M
n 
Pl
R
  n2
c M
s 
n
Theoretical
rate of change
of period
MATTER TO THE DEEPEST
13
Comparison of bounds
 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
Ustroń, Sept. 16 2009
MATTER TO THE DEEPEST
14
Stars are immersed in the Galactic dark halo
What are the consequences ?
Ustroń, Sept. 16 2009
MATTER TO THE DEEPEST
15
Accretion of dark matter
Capture rate
Spergel & Press 1985
Gould 1987
 eff   si 
i
MW D
3
X i Ai
mp
Barometric distribution of WIMPs sets in
1/ 2


3Tc

rx  
2

G

m
c dm 

rx  82km
Majorana particles - -> annihilate
Stady state: accretion and annihilation rates are equal
Additional luminosity
Ustroń, Sept. 16 2009
MATTER TO THE DEEPEST
16
In the supersymmetric model of WIMPs (neutralino)
One can obtain the upper bound on nucleon scatering cross
section

2
.08

10
cm
si

37 2
Ustroń, Sept. 16 2009
MATTER TO THE DEEPEST
17
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”)
Ustroń, Sept. 16 2009
MATTER TO THE DEEPEST
18
Ustroń, Sept. 16 2009
MATTER TO THE DEEPEST
19
1/ 2


3Tc

rx  
 2G c mdm 
rx  82km
 eff
MW D
3
  si 
X i Ai
mp
i
Ustroń, Sept. 16 2009
MATTER TO THE DEEPEST
20
additional energy loss channel due to KK-graviton emission
relevant process - gravibremsstrahlung in static electric field
of ions.
Gkk
Gkk
e
e
e
e
Gkk
e
e
e
Gkk
e
Ustroń, Sept. 16 2009
MATTER TO THE DEEPEST
21
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:



T
n
P
OBS


L

5
.
86

10
n
Z

M


1
L

0
.
30

L





M 
P
O

3

75
2
e
KK
j
2j
j
S


the final result for the constraint on mass scale MS is:
Ustroń, Sept. 16 2009
MATTER TO THE DEEPEST
22