Speaker
Andrey Chugunov
(Ioffe Institute)
Description
Observations of hot rapidly rotating neutron stars in
low-mass X-ray binaries (LMXBs) provide important
constraints on the r-mode instability in neutron stars
(see, e.g., Ref. [1]). Here we discuss additional
constraints imposed on this instability, which follow from
observations of recycled neutron stars. Recent Ref. [2] was
devoted to the same subject and concluded that ''ungapped
interacting quark matter is consistent with both the
observed radio and x-ray data''. However, this model leads
to very high neutrino luminosity, thus high temperatures
observed for neutron stars in LMXBs can hardly be explained
(deep crustal heating is clearly not enough). We argue that
*all* the models in which r-mode instability is
suppressed by the bulk viscosity should face the same
problem. Therefore we concentrate on our recent model [1]
where r-mode instability is suppressed because of the
resonant interaction of oscillation modes at some internal
temperatures (``resonant temperatures''). Here we
demonstrate that this model agrees with observations of
millisecond pulsars and provide observational evidences
that the coupling parameter for resonant mode interaction
at low temperatures should be rather large, in agreement
with theoretical expectations [1]. Furthermore, as shown in
Ref. [3], in addition to millisecond pulsars, members of
the new class of neutron stars -- hot widows/HOFNARs -- can
be born in LMXBs. Recent observations confirm stability of
the surface temperature of the quiescent neutron stars
without power-law components [4]. This could indicate that
some of those stars can, in fact, belong to hot
widows/HOFNARs.
This study was partially supported by RFBR (grants 14-02-00868-a and 14-02-
31616-mol-a), and by RF president programme (grants MK-506.2014.2 and NSh-294.2014.2).
References
[1] M.E. Gusakov, A.I. Chugunov, and E.M. Kantor, Phys.
Rev. Lett. 112, 151101 (2014); Phys. Rev. D 90, 063001
(2014)
[2] M.G. Alford and K. Schwenzer, Phys. Rev. Lett. 113,
251102 (2014)
[3] A.I. Chugunov, E.M. Gusakov, and M.E. Kantor, MNRAS
445, 385–391 (2014)
[4] A. Bahramian et al., MNRAS 452, 3475–3488 (2015)
Primary author
Andrey Chugunov
(Ioffe Institute)
Co-authors
Dr
Elena Kantor
(Ioffe Institute)
Dr
Mikhail Gusakov
(Ioffe Institute)
