In this talk I describe a new class of superradiant instabilities in which ultralight scalar fields extract rotational energy from neutron stars. The instability arises from the mixing of scalar and photon modes in the magnetic field of the neutron star which extract energy from the rotating magnetosphere. Unlike for black holes, where the dissipation required for superradiance is provided by an absorbative horizon, the non-hermitian dynamics in this setup come from the resistivity in the stellar magnetosphere arising from a finite bulk conductivity. This leads to a set of complex eigenfrequencies associated to the instability, which we derive using techniques analogous to quantum mechanical perturbation theory by treating scalar field bound states like a perturbed atomic state. We then compare the instability rate to the characteristic astrophysical time scales of neutron stars given by their spin-down times.
Axion superradiance in rotating neutron stars
Next Journal Club
Session to be resumed.
Black Hole Workshops
XI Black Holes Workshop, Lisbon, 2018
17-18 December 2018
Previous workshops in the series:
I Black Holes Workshop, Porto, 2008
II Black Holes Workshop, Lisbon, 2009
III Black Holes Workshop, Minho, 2010
IV Black Holes Workshop, Aveiro, 2011
V Black Holes Workshop, Lisbon, 2012
VI Black Holes Workshop, Minho 2013
VII Black Holes Workshop, Aveiro 2014
VIII Black Holes Workshop, Lisbon 2015
IX Black Holes Workshop, Minho 2016
X Black Holes Workshop, Aveiro 2017
NRHEP Network Meetings
Our group coordinated the "Numerical Relativity and High Energy Physics" IRSES network (2012-2015). Here is a list of the global network meetings organized:
9-13 July 2012, Aveiro, Portugal
11-14 March 2013, Lisbon, Portugal
6-10 January 2014, Mississippi, USA
7-10 July 2015, Rome, Italy
28 Sep-2 Oct 2015, Belém, Brazil
Ph.D. and Post-doctoral opportunities
Contact us If you are interested in pursuing graduate studies/research in our group.
A list of scientific meetings, mostly in gravitational physics, in 2016.