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Marek Biesiada Department of Astrophysics and Cosmology University of Silesia Katowice, Poland 2 nd Vienna Central European Seminar on Particle Physics.

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Presentation on theme: "Marek Biesiada Department of Astrophysics and Cosmology University of Silesia Katowice, Poland 2 nd Vienna Central European Seminar on Particle Physics."— Presentation transcript:


2 Marek Biesiada Department of Astrophysics and Cosmology University of Silesia Katowice, Poland 2 nd Vienna Central European Seminar on Particle Physics and Quantum Field Theory “FRONTIERS IN ASTROPARTICLE PHYSICS” 25-27 November 2005

3 Outline of the talk Astrophysics as a source of bounds on exotic physics Astroseismology of WDs - a new tool for astroparticle physics Some bounds from G117-B15A star Perspectives and Conclusions

4 modern astrophysics is a great success of standard physical theories in explaining properties of stars and stellar systems stars can be used as sources of constraints for non standard physical ideas some of these bounds turn out to be more stringent than these coming from direct physical experiments. m o t i v a t i o n

5 i d e a weakly interacting particles (axions, Kaluza-Klein gravitons, etc. ) can be produced in stellar interiors and escape freely they become an additional channel of energy loss from stellar interiors new channel of energy loss would modify stellar evolution e.g. Raffelt G., Annu.Rev.Nucl.Particle Sci.,49, 1999

6 Scheme of Evolutionary Track of a Star

7 in practice three main sources of astrophysical bounds: the Sun; supernova 1987A; red giants from globular clusters.

8 H burning main-sequence star response of radiative interior to extra cooling - shrinking and T c increase how can we measure T c of the Sun? helioseismology - possibility to estimate T c directly from the profile of c s the s u n

9 From Raffelt, 1999

10 constraints comes from: pulse duration energy budget s u p e r n o v a 1 9 8 7 A


12 red giants from globular clusters RG - stars with degenerate He core/interior on HB - stars with radiative core/interior additional cooling mechanism would actually cool down the interior of RG - there is no feedback between energy loss and pressure consequences: He-flash would be delayed star would spend less time on HB observational indicators height of RGB tip # density of stars on HB

13 the new tool now! from white dwarfs white dwarfs are degenerate stars composed of C and O with thin He and H outer layers WD history is simple: the only thing the star can do is to cool down emitting photons luminosity of the WD is given by Mestel cooling law

14 Instability strips on H-R diagram ZZ Ceti

15 relative simplicity some of them become pulsating stars - the so called ZZ-Ceti variables advances in asteroseismology - possibility to identify various modes of pulsation and to measure their periods with great accuracy an opportunity to estimate the rate of changes of the temperature and hence the fraction of luminosity attributed to hypothetical new energy loss. what makes white dwarfs useful ?

16 from the theory of stellar oscillations it turns out that white dwarfs can support non-radial oscillations the excited g-modes have frequencies (proportional to) h o w d o e s i t w o r k ? Brunt-Väisälä frequency

17 for degenerate electron gas in non-zero temperature: A~T 2 so 1/P ~T i.e. conclusions from the rate of period change one gets information about cooling rate when the star cools down - the period increases

18 First, if... the observed period increase rate P OBS is significantly greater than theoretically predicted (assuming standard physics ) P O - this anomalous effect can be explained by an additional energy loss channel L NEW (Isern, Hernanz, Garcia-Berro ApJ 1992)

19 the observed value P OBS agrees with P O in the sense that P O lies within, say 2  confidence interval - one can derive a constraint on exotic channel of energy loss second case

20 G117 - B15A

21 Main actor G117-B15A pulsating DAV white dwarf (ZZ Ceti) discovered in 1976 McGraw & Robinson global parameters mass 0.56 M 0 T eff =11 620 K Bergeron 1995 log(L/L 0 ) = -2.8 i.e. L=6.18 10 30 erg/s McCook & Sion 1999 Chemical composition: C:O = 20:80 T c = 1.2 10 7 K Bradley 1995 R = 9.6 10 8 cm O CHeH

22 Pulsating properties: excited fundamental modes 215.2 s271 s304.4 s Kepler et al. 1982 Accurate measurement of the rate of change of 215.2 s mode period Kepler et al. 2000 theory predicts dP O /dt = 3.9 10 -15 s/s ( Córsico et al. 2001)


24 What have we done with G117-B15A ? we have used this approach to constrain the compactification mass scale M s in Arkani-Hammed, Dimopoulos & Dvali (1998) model we have considered model with n=2 large extra dimensions and tested with G117-B15A Biesiada & Malec PhysRevD 65, 2002

25 additional energy loss channel due to KK-graviton emission relevant process - gravibremsstrahlung in static electric field of ions. e e e e e e e e G kk Ga kk

26 specific mass emissivity for this process calculated by Barger et al. Phys Lett B 1999 the upper 2  limit on P OBS translates into a bound: the final result for the constraint on mass scale M S is:

27 comparison with other bounds LEPM s > 1 TeV/c 2 The Sun M s > 0,3 TeV/c 2 Red Giants M s > 4 TeV/c 2 SN1987A M s > 30-130TeV/c 2 White Dwarf M s > 14,3 TeV/c 2

28 What have the others done with G117-B15A ? used G117-B15A to constrain the mass of an axion evolutionary and pulsational codes with axion emissivity added obtained bound to axion mass Corsico et al. New Astron. 6, 2001

29 Corsico et al. New Astron. 6, 2001

30 Another issue - Varying G renewed debate over the issue whether the fundamental constants of nature (G, c, h or e) can vary with time

31 Dirac’s Large Number Hypothesis Brans-Dicke Theory Theories with higher dimensions, superstring theories, M-theory etc. Claims that fine structure constant might vary Webb & Murphy 2001 Gravity constant G: historically the first considered as varying MOTIVATION

32 Paper M.Biesiada & B.Malec MNRAS 350, 644, 2004 Astroseismology of G117-B15A

33 Nature of oscillations : g-modes, Brunt - Väisälä frequency Asymptotic form Rate of period change (classically) Modification for varying G Cooling Residual contraction Here is the dependence on G

34 Idea: observed agrees with theoretical (with some accuracy) so We obtain the bound [Theoretical model according to Salaris et al. 1997 ]

35 ALTERNATIVE BOUNDS ON VARYING G 1. Paleontological: Teller 1948 assuming, that the Earth temperature is determined by energy flux through a sphere of radius = the radius of the Earth orbit T earth ~ G 2.25 M 0 1.75 if M 0 =const., then if G were 10% higher 300 mln. yrs ago T earth would have been close to water boiling point - contradicted by existence of cambrian trylobits

36 2. Celestial Mechanics Moon - Earth system (LLR) < 8 10 -12 yr -1Williams et al. 1996 Solar System (Viking) (2 ± 4 )10 -12 yr -1Hellings et al. 1983 binary pulsars PSR 1913+16 (1.10 ± 1.07 )10 -11 yr -1 Damour & Taylor 1991 PSR B1913+16 (4 ± 5 )10 -11 yr -1 Kaspi et al. 1994

37 3. Astrophysics helioseismology - p-modes spectrum: classical vs. Brans-Dicke Theory < 1.6 10 -12 yr -1Guenther et al. 1998 Globular Clusters („cluster age < age of the Universe”) (-1.4 ± 2.1) 10 -12 yr -1 Del’Innocenti et al. 1996 pulsating White Dwarfs 4. 10 -10 yr -1 Biesiada & Malec 2004 Benvenuto et al. 2004

38 4. Cosmology (Brans-Dicke Theory) CMB BBN Copi et al. Phys Rev.Lett. 92 2004 Cyburt et al. 2004 astro-ph/0408033

39 besides G117-B15A, another DAV star with dP O /dt measured is R548 (ZZ Ceti) for P 0 =213 s Mukadam et al. Baltic Astron. 2003 besides DAV, hot DBV stars can be used to test plasmon neutrinos and axions Kim, Winget, Montgomery 2005 astro-ph/0510103 pulsating White Dwarfs are becoming a new tool in astroparticle physics PERSPECTIVES AND CONCLUSIONS

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