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Seminars»09.05.2019 - K. Yavuz Ekşi : How do neutron stars slow down?

09.05.2019 - K. Yavuz Ekşi : How do neutron stars slow down?

How do neutron stars slow down?

K. Yavuz Ekşi
Physics Engineering Department, Istanbul Technical University, Istanbul, Turkey
09 May 2019, Thursday, 14:40
Cavid Erginsoy Seminar Room, Physics Department, 3rd floor

Abstract: Neutron stars are compact objects of radius R ~10 km and masses of 1.5–2 solar mass. They are rapidly rotating objects with spin periods P ∼ 0.01 − 10 s; some have even shorter and some have much longer periods. Neutron stars are strongly magnetized objects with typical magnetic fields B ∼ 1012 G; some have 3 orders of magnitude smaller and larger fields. The misalignment of the rotation and magnetic axis leads to the so called “lighthouse effect” by which we observe pulsed emission as the beamed emission from the magnetic poles sweep our line of sight. We can thus measure the spin period of a pulsar precisely and even determine its change over time. Of the ∼ 2700 pulsars discovered to date most are rotationally powered pulsars (RPPs) i.e. objects radiating at the expense of their rotational kinetic energy. It is generally conceived that these objects spin-down under the magnetic dipole radiation torque, but observations suggest that other processes must also be involved. Of these processes I will review our recent works about the alignment of the rotation and magnetic axis [1,2], and the growth [3,4] and decay [2] of the magnetic field of neutron stars at different stages.

References:
[1] Eksi et al. 2016, The Astrophysical Journal, 823, 34
[2] Sasmaz-Mus et al. 2019, ArXiv: 190406769
[3] Guneydas & Eksi 2013, Monthly Notices of the Royal Astronomical Society: Letters, 430L, 59
[4] Eksi 2017, Monthly Notices of the Royal Astronomical Society, 469, 1974