Novel Astrophysical Constraint on Axion-Photon Coupling

Transcription

1 Novel Astrophysical Constraint on Axion-Photon Coupling Maurizio Giannotti, Barry University Based on arxiv: , accepted for publication in PRL In collaboration with: A. Friedland, Los Alamos National Laboratory M.Wise, Barry University Miami 2012 December 15, 2012

2 Summary - Axion and axion-like particles - The role of HB and intermediate mass stars - Blue loop phase and the observable evolutionary sequences of intermediate mass stars - Blue and red super giants - New constraints on axion-photon coupling from observations of blue and red super giants

3 The Axion Axions are hypothetical particles whose existence is a prediction of the Peccei-Quinn solution of the Strong CP problem. In addition, the axion is a prominent dark matter candidate. Peccei and Quinn (1977) Weinberg (1978), Wilczek (1978) Preskill, Wise and Wilczek (1983) Abbott and Sikivie (1983) Dine and Fischler (1983) Turner (1986) Axions interact with matter and radiation. In the standard axion models the axion interaction with matter and photons and the axion mass are related in terms of the phenomenological Peccei-Quinn constant f a L int i C m f i i ~ a 5 ga γa F F a 4 1 m a f a 6 ev 6 /10 GeV

4 The Axion Axions are hypothetical particles whose existence is a prediction of the Peccei-Quinn solution of the Strong CP problem. In addition, the axion is a prominent dark matter candidate. Peccei and Quinn (1977) Weinberg (1978), Wilczek (1978) Preskill, Wise and Wilczek (1983) Abbott and Sikivie (1983) Dine and Fischler (1983) Turner (1986) Axions interact with matter and radiation. In the standard axion models the axion interaction with matter and photons and the axion mass are related in terms of the phenomenological Peccei-Quinn constant f a L int m a C mi i f f a i ~ a 5 ga γa F F a 4 6 ev 6 /10 GeV 1 Axion-photon coupling g a 2 em f a

5 The Axion Axions are hypothetical particles whose existence is a prediction of the Peccei-Quinn solution of the Strong CP problem. In addition, the axion is a prominent dark matter candidate. Peccei and Quinn (1977) Weinberg (1978), Wilczek (1978) Preskill, Wise and Wilczek (1983) Abbott and Sikivie (1983) Dine and Fischler (1983) M. Turner (1986) Axions interact with matter and radiation. In the standard axion models the axion interaction with matter and photons and the axion mass are related in terms of the phenomenological Peccei-Quinn constant f a However, recently there has been an effort to study more general models where the coupling constants and the mass are independent (ALPs). Most of the current experimental searches are probing the axion-photon coupling. The current bound is g a GeV 1

6 Experimental Axion (and ALPs) Search Most of the modern axion searches are based on the microwave cavity detection proposed by P. Sikivie (1983), which relays on the axion-photon coupling. Among the major experiments that are searching for the axion is the Cern Axion Solar Telescope (CAST) Axion-photon vertex HB-bound, g 10 =1. Raffelt and Dearborn (1987) from I. G. Irastorza et al., Latest results and prospects of the CERN Axion Solar Telescope, Journal of Physics: Conference Series 309 (2011)

7 Axion v.s. neutrinos Axions can be produced in the core of a star from photons interacting with the electric field of the nuclei (Primakoff process). Axion (g 10 =1) dominates over Neutrino cooling From Friedland, M.G., Wise, arxiv: , Submitted to PRL

8 Axion and Horizontal Branch (HB) stars Axions can be produced in the core of a star from photons interacting with the electric field of the nuclei (Primakoff process). Axion (g 10 =1) dominates over Neutrino cooling HB-Stars Axions would speed up the consumption of He in the HB star core and reduce the HB lifetime. Observational constrains come from the comparison of the number of HB vs. RG stars. g a GeV 1 corresponds to a reduction of this ratio by 30%.

9 Axion and He-burning massive stars What about more massive stars? He-Burning massive Stars

10 Log(Teff[K]) [k]) Observable evolutionary Phases: Central H- and He-burning Massive stars spend 80% to 90% of their life burning hydrogen in their core (Hburning stage), and almost all the rest of their life burning helium in the core and hydrogen in a shell (He-burning stage). Consequently, these are the only stages for which there are numerous astronomical observations. Star Age [Myr] (Myr) Simulations for a 8M, solar metallicty, from main sequence to end of He-burning. MESA (Modules for Experiments in Stellar Astrophysics), Paxton et al. ApJ Suppl (2011) [arxiv: ]

11 Log(Teff[K]) [k]) H-burning H-burning Heburning Main Sequence HeB phase Star Age [Myr] (Myr) Simulations for a 8M, solar metallicty, from main sequence to end of He-burning. MESA (Modules for Experiments in Stellar Astrophysics), Paxton et al. ApJ Suppl (2011) [arxiv: ]

12 Log(Teff[K]) [k]) Observable evolutionary Phases: Central H- and He-burning Blue Loop Main Sequence Star Age [Myr] (Myr) Simulations for a 8M, solar metallicty, from main sequence to end of He-burning. MESA (Modules for Experiments in Stellar Astrophysics), Paxton et al. ApJ Suppl (2011) [arxiv: ]

13 The Axion and the Blue Loop Blue Loop: the beginning of the blue loop is set by the H-burning shell time scale whereas the end is set by the He-burning core time scale [Kippenhahn and Weigert (1994)] H-burning Heburning End M=8 M Blue Loop

14 Observable evolutionary Phases: Central H- and He-burning The blue loops are necessary to explain the existence of the Cepheids Cepheids Simulations of evolution in H-R diagram of stars with solar metallicty, from main sequence to end of He-burning. [MESA]

15 Observable evolutionary Phases: Central H- and He-burning MS BHeB RHeB Most of the star life-time is spent in one of the three sequences: the Main Sequence (central H- burning), the Red central He- Burning sequence, and the Blue central He- Burning sequence Simulations of evolution in H-R diagram of stars with solar metallicty, from main sequence to end of He-burning. [MESA]

16 Observable evolutionary Phases: Central H- and He-burning from Kristen B. W. McQuinn et. al., Astrophys.J. 740 (2011) Color-magnitude diagram for Sextans A Dohm-Palmer and E. D. Skillman, (2002)

17 Observable evolutionary Phases: Central H- and He-burning The relative number and position in the color magnitude diagram of the red and blue He-burning stars has been subject to deep investigation in the last decade. Currently there is a small discrepancy between predictions and observations: (at high luminosities) B/R is too high, and the blues stars are too blue. From Kristen B. W. McQuinn et. al., Astrophys.J. 740 (2011) Log T[k]=4 Log T[k]=3.7

18 What about the axions? Axions can be produced in stars through the Primakoff process a shell: COLD This process is very sensitive to the temperature of the plasma and so it is more efficient in the hot core than in the cold shell. core: HOT Axions would modify in different ways the time scales of the core and shell

19 The Axion and the Blue Loop Blue Loop: the beginning of the blue loop is set by the H-burning shell time scale whereas the end is set by the He-burning core time scale [Kippenhahn and Weigert (1994)] H-burning Heburning End M=8 M Blue Loop

20 The Axion and the Blue Loop

21 Red-shift The Axion and the Blue Loop Less blue stars

22 Axions effects on the Blue Loop 9.5 M star, g 10 =0 (No Axion) Age[Myr] MESA Simulation. Friedland, M.G., Wise, arxiv: , PRL (accepted)

23 Axions effects on the Blue Loop 9.5 M star, g 10 =0.6 Age[Myr] MESA Simulation. Friedland, M.G., Wise, arxiv: , PRL (accepted)

24 Axions effects on the Blue Loop 9.5 M star, g 10 =0.7 Age[Myr] MESA Simulation. Friedland, M.G., Wise, arxiv: , PRL (accepted)

25 Axions effects on the Blue Loop 9.5 M star, g 10 =0.8 Age[Myr] MESA Simulation. Friedland, M.G., Wise, arxiv: , PRL (accepted)

26 Axions effects on the Blue Loop The value g 10 =0.88 corresponds to the current CAST bound on the axion-photon coupling. A value of g10=0.8 would provide qualitative changes in the stellar evolution. In particular, it would eliminate the blue loop stage of the evolution, leaving one without an explanation for the existence of Cepheid stars in a broad range of pulsation periods.

27 Experimental Evidence for Blue Sequences High metallicity Galaxy V-I Color Figures from Kristen B. W. McQuinn et. al., Astrophys.J. 740 (2011)

28 Experimental Evidence for Blue Sequences High metallicity Galaxy uncertainty V-I Color Figures from Kristen B. W. McQuinn et. al., Astrophys.J. 740 (2011)

29 Experimental Evidence for Blue Sequences High metallicity Galaxy uncertainty V-I Color Figures from Kristen B. W. McQuinn et. al., Astrophys.J. 740 (2011)

30 Conclusions and future directions Axions affect considerably the evolution of intermediate mass stars 7-12 M. The axion cooling has the effect of red-shifting the bluest point of the blue loop and of reducing the time of the blue-loop phase. A value of g 10 =0.8, which is below the current limit, would be sufficient to eliminate completely the blue loop phase of the stellar evolution. This would contradict observational data, since the blue loops are required, e.g., to account for the existence of Cepheid stars. This is a conservative requirement. Given accurate counts, it may be possible to check whether the number of stars in the blue loop phase is reduced. For example, g 10 = 0.6 would reduce the time a 9.5 M star spends on the blue loop by a factor of two (to get the same sensitivity for g 10 from solar-mass stars requires knowing the numbers of HB stars to a 10% precision. The analysis of the blue loop phase to study particle physics is new! Besides the axion, this methodology could be applied to other hypothetical scenarios and could indicate a possible new direction of investigation of the impact of the physics beyond the standard model on astrophysics.

31 Thank You

32 Results V-I Color Result: Kristen B. W. McQuinn et. al., Astrophys.J. 740 (2011) A value of g 10 above 0.8 would be incompatible with the current observations of HeB sequences. Open questions: - Can the axion explain the small red-shift of the bluest point of the blue loop in the high luminosity region of the CMD? - Can the axion explain the discrepancy in the number of blue and red stars observed experimentally, namely the fact hat B/R is larger than expected?

33 Observable evolutionary Phases: Central H- and He-burning Color-magnitude diagram for Sextans A. MS and BHeB stars From R. C. Dohm-Palmer and E. D. Skillman, (2002) The x-axis shows the V-I color.

34 Experimental Evidence for Blue Sequences High mass (young cluster) High metallicity Galaxy Low mass (old cluster) V-I Color Figures from Kristen B. W. McQuinn et. al., Astrophys.J. 740 (2011)

35 Axion search CAST Bound from HB-stars LEGEND From Bellini et al., Borexino collaboration, PHYSICAL REVIEW D 85, (2012)

36 Experimental Axion (and ALPs) Search Bound from HB-stars Babette Dobrich, ALPS II collaboaration, arxiv: [hep-ph]

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38 Axion Models Weinberg-Wilczek Axion 2 Higgs fields; PQ scale ~ e.w. scale ~200 GeV Weinberg (1978) Wilczek (1978) excluded by several terrestrial experiments which fix fa>10 4 GeV >> e.w. scale However, The PQ mechanism does not fix the PQ scale!! If the axion emerges (at least partially) from a singlet field, the PQ constant is not related to the e.w. scale. Invisible Axion KSVZ: Kim (1979); Shifman, Vainshtein, Zakharov (1980) - Heavy quarks with non-zero PQ-charge - Standard quarks and leptons PQ-neutral - Ce ~10-3, CN ~1 DFSZ: Zhitnitskii (1980); Dine, Fischler, Srednicki (1981) - 2 Higgs fields + a singlet scalar field - Ce ~1, ~1, CN ~1

39 Summary of the astrophysical bounds HADRONIC Axion Window SN 1987A (g an ) DFSZ PQ-Scale 200 GeV 10 4 GeV 10 9 GeV GeV GeV e.w. GUT 10 6 GeV 10 8 GeV Red Giants (g ae ) Only for DFSZ axion GeV MPl HB Stars (g a ) Terrestrial Experiments Axion heavy Production damped No upper limit? Gravity?

40 Core Evolution of Massive Stars Photon cooling (not very efficient) Very slow evolution H H He Neutrino Cooling (very efficient) Very fast evolution H He C/O In collaboration with A.Heger, A.Friedland and V.Cirigliano, using the Kepler code for stellar evolution APJ:696 (2009)

41 Axion search LEGEND From Bellini et al., Borexino collaboration, PHYSICAL REVIEW D 85, (2012)

42 Axion search

43 Axion search The axion searches are mostly based on the axion photon coupling From I G Irastorza et al., CAST collaboration, 2011 J. Phys.: Conf. Ser

44 Observable evolutionary Phases: Central H- and He-burning Any new-physics process that is more efficient in the He-burning core than in the H-burning shell during the He-burning stage would change the relative position and number of RHeB and BHeBa stars. From Kristen B. W. McQuinn et. al., Astrophys.J. 740 (2011) Log T[k]=4 Log T[k]=3.7

45 Experimental Axion Search One of the major experiments searching for the axion is the Cern Axion Solar Telescope (CAST), based on the microwave cavity detection of axions proposed by P. Sikivie (1983). a HB-bound, Raffelt and Dearborn (1987) Figure from G.Raffelt, talk given at Vista in Axion Physics, INT, Seattle, April 2012

46 Observable evolutionary Phases: Central H- and He-burning MS BHeB RHeB Most of the star life-time is spent in one of the three sequences: the Main Sequence (central H- burning), the Red central He- Burning sequence, and the Blue central He- Burning sequence Simulations of evolution in H-R diagram of stars with solar metallicty, from main sequence to end of He-burning. [MESA]

47

48 Results Result: Massive stars A value of g 10 above 0.8 would be incompatible with the current observations of HeB sequences. V-I Color

49 Experimental Evidence for Blue Sequences g 10 =0 g 10 =0.88 V-I V-I High metallicity Galaxy uncertainty V-I Color Figures from Kristen B. W. McQuinn et. al., Astrophys.J. 740 (2011)