summary effects of new physics on the evolution of massive
TRANSCRIPT
Massive stars and physics beyond the standard
model: How do intermediate and massive stars
respond to new physics?
Axions and massive stars.
(MAYBE) Effects of a non-vanishing neutrino
magnetic moment on the evolution of a massive
star.
Conclusions and perspectives
Summary
Effects of new physics on the evolution of massive stars
Maurizio Giannotti, Barry University
In collaboration with: A. Friedland, V.Cirigliano, Los Alamos National LaboratoryM.Wise, Barry UniversityA. Heger, University of Minnesota
Miami 2011December 2011
Pair Production
Plasmon decay
RG
WhiteDwarf
HB
SUN
PhotoproductionBremsstrahlung
Standard Cooling: photons and neutrinos
Photon cooling is relevant in the non-degenerateregion, below T~5×108K
Neutrino Cooling in Stars
The labels refer to the star core
Neutrino Cooling
Photon
Cooling
Core Evolution of Massive Stars
From A.Heger, A.Friedland, M.G., V.Cirigliano APJ:696 (2009)
Observable evolutionary Phases:
Central H- and He-burning
Massive stars spend 80% to 90% of their life burning hydrogen in their core (H-burning 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 that can be observed astronomically.
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. 192 3 (2011) [arXiv:1009.1622]
Log(
Teff
[K])
Star Age (Myr)Age [Myr]
Log(
T eff[
k])
Observable evolutionary Phases:
Central H- and He-burning
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. 192 3 (2011) [arXiv:1009.1622]
Log(
Teff
[K])
Star Age (Myr)Age [Myr]
Log(
T eff[
k])
He-burning
H-burning
H-burning
Main SequenceHeB phase
Observable evolutionary Phases:
Central H- and He-burning
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. 192 3 (2011) [arXiv:1009.1622]
Log(
Teff
[K])
Star Age (Myr)Age [Myr]
Log(
T eff[
k])
He-burning
H-burning
Main SequenceBlue Loop
Blue Loop: the beginning is set by the H-burning shell time scale the end is set by the He-burning core time scale[e.g., Kippenhahn and Weigert(1994)]
Observable evolutionary Phases:
Central H- and He-burning
Simulations of evolution in H-R diagram of stars with solar metallicty, from main sequence to end of He-burning. [MESA]
Simulations of evolution in H-R diagram of stars with solar metallicty, from main sequence to end of He-burning. [MESA]
Observable evolutionary Phases:
Central H- and He-burning
MS
BHeB RHeBMost 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
Color-magnitude diagram for Sextans A. MS and BHeB stars
From R. C. Dohm-Palmer and E. D. Skillman, (2002)
Observable evolutionary Phases:
Central H- and He-burning
The x-axis shows the V-I color.
From Kristen B. W. McQuinn et. al.,Astrophys.J. 740 (2011)
Observable evolutionary Phases:
Central H- and He-burning
Log T[k]=3.7Log T[k]=4
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)
Observable evolutionary Phases:
Central H- and He-burning
Any new-physics process that is more efficient during the
He-burning phase than during the H-burning phase would
change the relative number of MS and HeB stars.
Log T[k]=3.7Log T[k]=4
From Kristen B. W. McQuinn et. al.,Astrophys.J. 740 (2011)
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.[see, e.g., Kippenhahn and Weigert,
Springer-Verlag Berlin Heidelberg New York. (1994)]
Log T[k]=3.7Log T[k]=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 (see P. Sikivie talk)
Axions interact with matter and radiation:
Peccei and Quinn (1977)Weinberg (1978), Wilczek (1978)
FFa gaCiL aa
~
4
1 γ5int
Preskill, Wise and Wilczek (1983)Abbott and Sikivie (1983) Dine and Fischler (1983)
Here we are interested on in the interactios with photons. The current bound on the axion-photon coupling is ga ≤10−10GeV−1
Today, the research in axion is experiencing a revival in terms of new experimental effort for its detection, and new theoretical ideas and models.
Experimental Axion Search
Among the major experiments that are searching for the axion are the Cern Axion SolarTelescope (CAST) and the Axion Dark Matter eXperiment (ADMX). They are both based onthe microwave cavity detection of axions proposed by P. Sikivie (1983). CAST searches foraxions from the sun, whereas ADMX searches for CDM axions.
Axion-photon vertex
The figure on the side is from I. G. Irastorza et al., Latest results and prospects of the CERN Axion Solar Telescope, Journal of Physics: Conference Series 309 (2011) 012001
HB-bound,Raffelt and Dearborn (1987)
a
Primakoff production of Axions in Stars
We derived an analytical fitting formula for f(x)which fits better than 3% in the region of interest for us.The relative importance of the Primakoff effect is shown above for ga = 10−10GeV−1 (g10 = 1), corresponding to the current bound
where
and
Axions can be produced in the core of a star through Primakoff photonconversion, +(Ze) → a +(Ze), in the field of a nucleus.The production rate is
A. Friedland, M.G., M. Wise, in preparation
[G. Raffelt, PRD 33, 897 (1986)]
RGHB
SUN
He-burning
H-burning
Primakoff production of Axions in Stars
Massive star: He-burning stage
A. Friedland, M.G., M. Wise, in preparation
Shell: T≈ 106 K
Core: T≈ 108 K
g10=0
g10=0.5
g10=0.6
g10=0.7
g10=0.8
g10=0.9
Simulations of evolution in H-R diagram of a 8M⊙, solar metallicty star from main sequence to end of He-burning. [MESA]. Friedland, M.G., M. Wise, in preparation
Axions effects on the Blue Loop
With g10 = ga / 10−10GeV−1
Simulations of evolution in H-R diagram of a 8M⊙, solar metallicty star from main sequence to end of He-burning. [MESA]. Friedland, M.G., M. Wise, in preparation
Axions effects on the Blue Loop
Red-shift
Less blue stars
Increasing ga causes:g10=0
g10=0.5
g10=0.6
g10=0.7
g10=0.8
g10=0.9
With g10 = ga / 10−10GeV−1
Simulations of evolution in H-R diagram of a 8M⊙, solar metallicty star from main sequence to end of He-burning. [MESA]. Friedland, M.G., M. Wise, in preparation
Axions effects on the Blue Loop
Axions effects on the Blue Loop
The figure shows the simulations of the evolution in the H-R diagram of stars (solar metallicty) from main sequence to end of He-burning. [MESA]. Friedland, M.G., M. Wise, in preparation
Axions would in general affect the expected B/R and the position of the BHeB sequence.
According to our simulations, for a value of ga below the current bound the blue loop disappears almost completely. The effect is stronger for heavier stars. For a star of initial mass about 12M⊙ (and solar metallicity), the blue loop disappears completely already for g10 = 0.5.
Figures from Kristen B. W. McQuinn et. al.,Astrophys.J. 740 (2011)
Experimental Evidence for Blue Sequences
High metallicity Galaxy
V-I Color
Figures from Kristen B. W. McQuinn et. al.,Astrophys.J. 740 (2011)
Experimental Evidence for Blue Sequences
High metallicity Galaxy
V-I ColorLow mass (old cluster)
High mass (young cluster)
Figures from Kristen B. W. McQuinn et. al.,Astrophys.J. 740 (2011)
Experimental Evidence for Blue Sequences
uncertainty
High metallicity Galaxy
V-I Color
Kristen B. W. McQuinn et. al., Astrophys.J. 740 (2011)
Experimental Evidence for Blue Sequences
uncertainty
Result:
A value of g10 above 0.8 (optimistically, 0.5) seems to be incompatible with the current observations of HeB sequences.
V-I Color
Kristen B. W. McQuinn et. al., Astrophys.J. 740 (2011)
Experimental Evidence for Blue Sequences
uncertainty
Result:
A value of g10 above 0.8 (optimistically, 0.5) seems to be incompatible with the current observations of HeB sequences.
V-I Color
I. G. Irastorza et al., Journal of Physics: Conference Series 309 (2011) 012001
HB-bound,Raffelt and Dearborn
(1987)
Kristen B. W. McQuinn et. al., Astrophys.J. 740 (2011)
Experimental Evidence for Blue Sequences
Result:
A value of g10 above 0.8 (optimistically, 0.5) seems to 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?
V-I Color
This project is part of a general plan to study the impact of new physics on massive stars.
Axions affect considerably the evolution of intermediate mass stars. The axioncooling has the effect of shifting toward the red the bluest point of the blue loop and of lowering the vale of B/R. The effect is stronger for heavier (more luminous) stars. For a star of initial mass about 12M⊙ and solar metallicity, the blue loop disappears completely for g10 = 0.5. Observations seem to exclude g10 ≥ 0.5-0.8
Finally, our analysis suggests the possibility of axions being responsible for the observed anomaly in the BHeB and RHeB stars, namely, the fact that the blue stars appear to be less blue than expected and that B/R is overestimated in the standard numerical simulations. If this picture were to be supported by further analysis, it would provide an indication of the existence of the axionwith a coupling to photons just below the current bound from CAST and testable in the near future. If not, the methodology would still indicate a new way to constrain the axion and a possible new direction of investigation of the impact of the physics beyond the standard model on astrophysics.
Conclusions