SÉMINAIRE DU GRECO
"Approximate No-hair Relations for Neutron Stars" |
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K. Yagi |
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Black holes enjoy the no-hair property, which states that their multipole moments can be described by just the first two, namely the mass and spin. We found that similar no-hair relations approximately hold for neutron stars. I first explain multipole moments for Newtonian polytropes can be approximately expressed in terms of the first three, namely the mass, spin and quadrupole moment, and such a three-hair relation is insensitive to the equation of state. We confirm such findings numerically for neutron stars in full General Relativity to hexadecapole order. I then explain how the neutron star relations non-trivially approach the black hole ones as the stellar compactness approaches that of a black hole by studying anisotropic stars as a toy model. Such approximate no-hair relations for neutron stars can be useful for probing nuclear physics with future X-ray observations. |
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lundi 11 mai 2015 - 11:00 Salle des séminaires Évry Schatzman, Institut d'Astrophysique de Paris |
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