FIAS Scientific Report 2011 - Frankfurt Institute for Advanced Studies ...

A new approach to the thermal evolution of neutron stars
Collaborators: R. Negreiros 1 , S. Schramm 1 , F. Weber 2 , V. Dexheimer 3
1 Frankfurt Institute for Advanced Studies, 2 San Diego State University, USA, 3 Gettysburg College, USA
Neutron stars are the extraordinarily compact remnants of massive stars that blew apart in violent supernova
explosions. Due to their extreme properties, compact stars are superb astrophysical laboratories, that present
a wealth of physical phenomena that may provide insight in the overlapping areas of nuclear physics, particle
physics and relativistic astrophysics. Currently, the equation of state (EoS) that describes ultra-dense matter
is widely unknown because of the very complicated mathematical structure of the many-body equations that
govern matter at extreme pressures. Understanding the equation of state of matter, under extreme conditions
of pressure/density and temperature, is of key importance for correctly understanding the phase diagram of
baryon matter. One of the most prominent methods of probing the inner composition of a neutron star is
by investigating its thermal evolution, since its thermal behaviour depends intrinsically on its microscopic
composition. Following this, we have used state-of-the-art microscopic models to simulate the cooling of
compact stars. Our results were then compared with a wealth of observed data, allowing us to obtain key
information about the microscopic composition of these objects. Furthermore we have proposed a new study
that challenges the traditional neutron star cooling paradigm. With our sophisticated simulations we were able
to explain comfortably the observed thermal behaviour of the neutron star in supernova remnant Cassiopeia A.
T s (K)
2.12×10 6
2.10×10 6
2.08×10 6
2.06×10 6
2.04×10 6
2.02×10 6
2.00×10 6
M = 1.5 M sun , β = 8.91
K = 6.90 x 10 -18 , ∆M = 5.5 x 10 -11 , Ω 0 /Ω K = 0.67
K = 3.34 x 10 -16 , ∆M = 6.0 x 10 -9 , Ω 0 /Ω K = 0.42
Cas A
M = 1.97 M sun , β = 107.83
310 320 330 340 350
Age (years)
Figure: Predicted thermal evolution of spinning-down neutron stars of different masses and observed data of Cas A
Related publications in 2011:
1) R. Negreiros, S. Schramm, F. Weber, Impact of Rotation-Driven Particle Repopulation on the Thermal Evolution
of Pulsars, arXiv:1103.3870.
2) V. Dexheimer, R. Negreiros, S. Schramm, Quark Deconfinement Under the Influence of Strong Magnetic
Fields, arXiv:1108.4479.
3) M. Malheiro, R. Negreiros, F. Weber, V. Usov, The effects of charge on the structure of strange stars, J. Phys.
Conf. Ser. 312 (2011) 042018.
4) R. Negreiros, S. Schramm. F. Weber, The Crust of Spinning Down Neutron Stars, chapter contribution to
book: The Crust of Neutron Stars, edited by C.A. Bertulani and J. Piekarewicz, Nova Publishers.
5) R. Negreiros, R. Ruffini, C. Bianco, J. Rueada, Cooling of young neutron stars in GRB associated to Supernova,
accepted for publication in Astronomy and Astrophysics, arXiv:1112.3462.
6) S. Schramm, V. Dexheimer, R. Negreiros, J. Steinheimer, Dense Matter and Neutron Stars in Parity Doublet
Models, arXiv:1110.0609.
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