488
R. MacKenzie et al.
A1 The magnino and accompanying particles form a homogeneous relativistic
gas at a high temperature just like the visible sector in the standard model of
cosmology. It thus defines its own comoving set of coordinates. Thus it will
be necessary for this medium to be interacting with the standard sector during
an early epoch so that the two define a common comoving frame. The new
sector becomes “dark” only in the late universe. The emergent DW structure
is then a comoving constant energy contribution.
Q2 What is the equation of the state of the spin-polarised ground state? Intuitively
any medium consisting of ordinary quasi-particles should be subject to
evolution with the corresponding equation of state and will not simulate
constant energy density.
A2 The spin-polarised medium if infinite, has been estimated to satisfy p =
−0.1ρ. However we note firstly that a negative value of effective w implies
a strongly coupled medium. Further, the domain wall structure would be
immune to expansion since it exists by virtue of local stresses whose strength
is many orders of magnitudes greater than the local gravitational tidal force.
For this reason we expect the DW complex to protect both itself and the
strongly coupled quasi-particle gas from suffering tidal acceleration. Thus
the energy density should remain constant, and averaged over an enormous
number of domains, should be homogeneous.
Acknowledgments We thank NSERC, Canada for financial support and the Ministére des
relations internationales et la francophonie of the Government of Québec for financing within the
cadre of the Québec-Maharashtra exchange. RBM and MBP also thank IIT Bombay for financial
support and hospitality.
References
1. S. Weinberg, Rev. Mod. Phys. 61, 1 (1989)
2. N. Aghanim et al., (Planck) (2018), arXiv:1807.06209
3. M. Li, X.-D. Li, S. Wang, Y. Wang, Commun. Theor. Phys. 56, 525 (2011). arXiv:1103.5870
4. U.K. Dey, T.S. Ray, U. Sarkar, Nucl. Phys. B928, 258 (2018). arXiv:1705.08484
5. J.I. Kapusta, Phys. Rev. Lett. 93, 251801 (2004). arXiv:hep-th/0407164
6. R.A. Battye, M. Bucher, D. Spergel, Phys. Rev. D60, 043505 (1999). arXiv:astro-ph/9908047
7. R.A. Battye, A. Moss, Phys. Rev. D76, 023005 (2007). arXiv:astro-ph/0703744
8. L. Conversi, A. Melchiorri, L. Mersini-Houghton, J. Silk, Astropart. Phys. 21, 443 (2004).
arXiv:astro-ph/0402529
9. A. Friedland, H. Murayama, M. Perelstein, Phys. Rev. D67, 043519 (2003). arXiv:astroph/0205520
10. U.A. Yajnik, EPJ Web Conf. 70, 00046 (2014)
11. R.B. MacKenzie, M.B. Paranjape, U.A. Yajnik (2019). arXiv:1901.00995
12. S. Raby, G. West, Phys. Lett. B200, 547 (1988)
13. S. Raby G. West, Phys. Lett. B194, 557 (1987)
14. J.L. Feng, M. Kaplinghat, H. Tu, H.-B. Yu, J. Cosmol. Astropart. Phys. 0907, 004 (2009).
arXiv:0905.3039
15. K.K. Boddy, M. Kaplinghat, A. Kwa, A.H.G. Peter, Phys. Rev. D94, 123017 (2016).
R. MacKenzie et al.
A1 The magnino and accompanying particles form a homogeneous relativistic
gas at a high temperature just like the visible sector in the standard model of
cosmology. It thus defines its own comoving set of coordinates. Thus it will
be necessary for this medium to be interacting with the standard sector during
an early epoch so that the two define a common comoving frame. The new
sector becomes “dark” only in the late universe. The emergent DW structure
is then a comoving constant energy contribution.
Q2 What is the equation of the state of the spin-polarised ground state? Intuitively
any medium consisting of ordinary quasi-particles should be subject to
evolution with the corresponding equation of state and will not simulate
constant energy density.
A2 The spin-polarised medium if infinite, has been estimated to satisfy p =
−0.1ρ. However we note firstly that a negative value of effective w implies
a strongly coupled medium. Further, the domain wall structure would be
immune to expansion since it exists by virtue of local stresses whose strength
is many orders of magnitudes greater than the local gravitational tidal force.
For this reason we expect the DW complex to protect both itself and the
strongly coupled quasi-particle gas from suffering tidal acceleration. Thus
the energy density should remain constant, and averaged over an enormous
number of domains, should be homogeneous.
Acknowledgments We thank NSERC, Canada for financial support and the Ministére des
relations internationales et la francophonie of the Government of Québec for financing within the
cadre of the Québec-Maharashtra exchange. RBM and MBP also thank IIT Bombay for financial
support and hospitality.
References
1. S. Weinberg, Rev. Mod. Phys. 61, 1 (1989)
2. N. Aghanim et al., (Planck) (2018), arXiv:1807.06209
3. M. Li, X.-D. Li, S. Wang, Y. Wang, Commun. Theor. Phys. 56, 525 (2011). arXiv:1103.5870
4. U.K. Dey, T.S. Ray, U. Sarkar, Nucl. Phys. B928, 258 (2018). arXiv:1705.08484
5. J.I. Kapusta, Phys. Rev. Lett. 93, 251801 (2004). arXiv:hep-th/0407164
6. R.A. Battye, M. Bucher, D. Spergel, Phys. Rev. D60, 043505 (1999). arXiv:astro-ph/9908047
7. R.A. Battye, A. Moss, Phys. Rev. D76, 023005 (2007). arXiv:astro-ph/0703744
8. L. Conversi, A. Melchiorri, L. Mersini-Houghton, J. Silk, Astropart. Phys. 21, 443 (2004).
arXiv:astro-ph/0402529
9. A. Friedland, H. Murayama, M. Perelstein, Phys. Rev. D67, 043519 (2003). arXiv:astroph/0205520
10. U.A. Yajnik, EPJ Web Conf. 70, 00046 (2014)
11. R.B. MacKenzie, M.B. Paranjape, U.A. Yajnik (2019). arXiv:1901.00995
12. S. Raby, G. West, Phys. Lett. B200, 547 (1988)
13. S. Raby G. West, Phys. Lett. B194, 557 (1987)
14. J.L. Feng, M. Kaplinghat, H. Tu, H.-B. Yu, J. Cosmol. Astropart. Phys. 0907, 004 (2009).
arXiv:0905.3039
15. K.K. Boddy, M. Kaplinghat, A. Kwa, A.H.G. Peter, Phys. Rev. D94, 123017 (2016).