Magnetic field evolution of neutron stars: linking magnetars and antimagnetars Sergei Popov (SAI MSU) (co-authors: A. Kaurov, A. Kaminker) PASA vol. 32, id.e018 (2015) arXiv: arXiv:

Pires et al. (2015)

NS birth rate [Keane, Kramer 2008, arXiv: ]

CCOs Puppis A See list in: For three sources there are strong indications for large (>~100 msec) initial spin periods and low magnetic fields: 1E in PKS /52, RX J in Pup A and PSR J in Kesteven 79

Anti-magnetars Star marks the CCO in Kes 79 (from ) Note, that there is no room for antimagnetars from the point of view of birthrate in many studies of different NS populations.

Further evolution of CCOs B PSRs+ Magnetars+ Close-by coolers CCOs B HMXBs Among young isolated NSs about 1/3 can be related to CCOs. If they are anti-magnetars, then we can expect that 1/3 of NSs in HMXBs are also low-magnetized objects. They are expected to have short spin periods <1 sec. However, there are no many sources with such properties. Possible solution: emergence of magnetic field (see Ho 2011). Chashkina, Popov 2012 Popov et al. MNRAS 2010 Halpern, Gotthelf

Where are old CCOs? Yakovlev, Pethick 2004 According to cooling studies they have to be bright till at least 10 5 years. But there are no candidates in the solar vicinity. We propose that a large set of data on HMXBs and cooling NSs is in favour of field emergence on the time scale 10 4 ≤ τ ≤ 10 5 years. Some PSRs with thermal emission for which additional heating was proposed can be descendants of CCOs with emerged field.

The final element for the GUNS? Vigano, Pons 2012Bernal, Page, Lee 2013 The field is buried by fall-back, and then re-emerges on the scale ~10 4 yrs.

Emerged pulsars in the P-Pdot diagram Emerged pulsars are expected to have P~ sec B~ G Negative braking indices or at least n<2. About of such objects are known. Parameters of emerged PSRs: similar to “injected” PSRs (Vivekanand, Narayan, Ostriker). The existence of significant fraction of “injected” pulsars formally do not contradict recent pulsar current studies (Vranesevic, Melrose 2011). Part of PSRs supposed to be born with long ( s) spin periods can be matured CCOs. Espinoza et al. arXiv:

“Hidden” magnetars Kes 79 Halpern, Gotthelf 2010 Kes 79. PSR J P~0.1 s Shabaltas & Lai (2012) show that large pulse fraction of the NS in Kes 79 can be explained if its magnetic field in the crust is very strong: few ×10 14 G. If submergence of the field happens rapidly, so the present day period represents the initial one Then, the field of PSR 1852 was not enhanced via a dynamo mechanism Detection of millisecond “hidden” magnetars will be a strong argument in favour of dynamo. arXiv:

Magnetar bursts

Growing twist (images from Mereghetti arXiv: )

Non-global twist model

What causes what? The chicken or the egg? Crust or magnetosphere? It would be nice to have magnetars without crust, and magnetars without magnetospheres. Hypothetical highly magnetized quark stars can be the first of them, and “frozen” (aka “hidden”) magnetars – can be testbeds to study crustal processes without magnetospheric phenomena.

Crust of magnetosphere? Beloborodov, Levin 2014 Lander et al Masada et al What triggers the burst? What provides energy?

How often do magnetars burst? Perna, Pons 2011

Visibility of the thermal effect Pons, Rea 2012 If a NS has low quiescent luminosity, then an additional release of thermal energy during an outburst can be well visible. If the luminosity was already high – then it is very difficult to observe an outburst.

What about Kes 79? Halpern, Gotthelf 2010 Very stable flux for years! (see also Bogdanov 2014) Why? Always in a high state? Or nearly no activity for years? AXP CXO J is known to have constant flux for a long time.

RCW 103 as a “hidden” magnetar with active crust De Luca et al. (2006) Fluxes Temperatures Variability Pulse profile changes Kes 79 looks very quiet, stable but RCW 103 – not. Only thermal radiation! No traces of any kind of magnetospheric activity.

Let us model RCW103! Kaminker et al. 2014

Cartoon of the model

Photons and neutrinos Kaminker et al Mostly released heat is carried away by νs.

How bright it can be? If we move the heating layer down (towards higher density) – then the surface emission is not strongly enhanced. It is shown, how much brighter a NS can be if we put the heating layer for 120 days.

Modeling RCW103 Calculations by A. Kaurov Heating was on for 120 days. Different curves correspond to different composition of the heat blanketing layer.

Conclusions Studies of “hidden” magnetars can be used to probe processes in the crust of strongly magnetized NSs. Kes 79 looks very stable, which is strange for a “hidden” magnetar RCW103 can be a ”hidden” magnetar, and its activity can be explained in this model. A compact object in SN1987A can be ``hidden’’ magnetar, as it was born soon after a coalescence (Morris, Podsiadlowski 2007) and strong fall-back has been proposed to explain its properties (Chevalier 1989, Bernal et al. 2010). PASA vol. 32, id.e018 (2015) arXiv: arXiv: