Supernovae (SNe) are copious sources for Kaluza-Klein (KK) gravitons which are generic for theories with large extra dimensions. These massive particles are produced with average velocities 0.5c so that many of them are gravitationally retained by the SN core. Every neutron star thus has a halo of KK gravitons which decay into νν, e⁺e^-, and γγ on time scales 10⁹ years. The EGRET γ-flux limits ( E_γ100MeV) for nearby neutron stars constrain the compactification scale for n0ex0ex=0ex0ex2 extra dimensions to M500TeV, and M30TeV for n0ex0ex=0ex0ex3. The requirement that neutron stars are not excessively heated by KK decays implies M1700TeV for n0ex0ex=0ex0ex2, and M60TeV for n0ex0ex=0ex0ex3.
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Hannestad et al. (2002) studied this question.
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