3 Magnetars: A Short Review and Some Sparse Considerations
127
pulsars in the up–right corner of the P – ˙
P diagram, the external dipolar magnetic
field inferred from the spin period and the slow-down rate is not necessary a good
proxy for it. For this reason, maybe it would be more appropriate to speak of
magnetar-like activity (or ‘magnetic restlessness’) in neutron stars rather than of
magnetars.
Perhaps even more importantly, magnetars are proving to be key objects in
understanding the puzzling observational diversity among the different classes of
isolated neutron stars. After all, neutron stars are relatively simply, collapsed,
objects, presumably all governed by the same equation of state: Why do they come
in so many flavours? Theoretical progresses, chiefly about the complexity and the
evolution of their magnetic field, are paving the way to a unifying view, in which
the age, the different magnetic field strength and geometry at birth, and few other
pivotal parameters, such as the mass and the chemical composition of the envelope,
can explain the neutron star diversity.
Magnetars are being increasingly invoked in a variety of astrophysical sources
and phenomena, from high-mass X-ray binaries and ULXs, to gamma-ray bursts,
superluminous supernovae, fast radio bursts, sources of gravitational waves, and
many others. While in some cases they are used in a lighthearted way as jacks-of-alltrades, because a huge magnetic field offers an easy way to solve an observational or
theoretical problem, magnetar are finally receiving the attention they deserve. This
will trigger more and more observational and theoretical efforts which, together
with new forthcoming powerful and innovative instruments, such as CTA, SKA,
Athena+, X-ray polarimeters, space interferometers, and giant optical telescopes,
are bound to deliver many important and surprising discoveries. Magnetars enthusiasts are well positioned to enjoy the next few decades.
Acknowledgments PE and NR acknowledge funding in the framework of the NWO Vidi award
A.2320.0076.
References
1. D.N. Aguilera, J.A. Pons, J.A. Miralles, 2D Cooling of magnetized neutron stars. Astron.
Astrophys. 486, 255–271 (2008). https://doi.org/10.1051/0004-6361:20078786
2. J. Aleksi´ c, L.A. Antonelli, P. Antoranz, M. Asensio, U. Barres de Almeida, J.A. Barrio,
J. Becerra González, W. Bednarek, K. Berger, E. Bernardini, A. Biland, O. Blanch, R.K.
Bock, A. Boller, G. Bonnoli, D. Borla Tridon, T. Bretz, E. Carmona, A. Carosi, P. Colin,
E. Colombo, J.L. Contreras, J. Cortina, L. Cossio, S. Covino, P. Da Vela, F. Dazzi, A. De
Angelis, G. De Caneva, E. De Cea del Pozo, B. De Lotto, C. Delgado Mendez, A. Diago
Ortega, M. Doert, D. Dominis Prester, D. Dorner, M. Doro, D. Eisenacher, D. Elsaesser,
D. Ferenc, M.V. Fonseca, L. Font, C. Fruck, R.J. García López, M. Garczarczyk, D. Garrido
Terrats, M. Gaug, G. Giavitto, N. Godinovi´ c, A. González Muñoz, S.R. Gozzini, A. Hadamek,
D. Hadasch, D. Häfner, A. Herrero, J. Hose, D. Hrupec, B. Huber, F. Jankowski, T. Jogler,
V. Kadenius, S. Klepser, M.L. Knoetig, T. Krähenbühl, J. Krause, J. Kushida, A. La
Barbera, D. Lelas, E. Leonardo, N. Lewandowska, E. Lindfors, S. Lombardi, M. López,
R. López-Coto, A. López-Oramas, E. Lorenz, M. Makariev, G. Maneva, N. Mankuzhiyil,
127
pulsars in the up–right corner of the P – ˙
P diagram, the external dipolar magnetic
field inferred from the spin period and the slow-down rate is not necessary a good
proxy for it. For this reason, maybe it would be more appropriate to speak of
magnetar-like activity (or ‘magnetic restlessness’) in neutron stars rather than of
magnetars.
Perhaps even more importantly, magnetars are proving to be key objects in
understanding the puzzling observational diversity among the different classes of
isolated neutron stars. After all, neutron stars are relatively simply, collapsed,
objects, presumably all governed by the same equation of state: Why do they come
in so many flavours? Theoretical progresses, chiefly about the complexity and the
evolution of their magnetic field, are paving the way to a unifying view, in which
the age, the different magnetic field strength and geometry at birth, and few other
pivotal parameters, such as the mass and the chemical composition of the envelope,
can explain the neutron star diversity.
Magnetars are being increasingly invoked in a variety of astrophysical sources
and phenomena, from high-mass X-ray binaries and ULXs, to gamma-ray bursts,
superluminous supernovae, fast radio bursts, sources of gravitational waves, and
many others. While in some cases they are used in a lighthearted way as jacks-of-alltrades, because a huge magnetic field offers an easy way to solve an observational or
theoretical problem, magnetar are finally receiving the attention they deserve. This
will trigger more and more observational and theoretical efforts which, together
with new forthcoming powerful and innovative instruments, such as CTA, SKA,
Athena+, X-ray polarimeters, space interferometers, and giant optical telescopes,
are bound to deliver many important and surprising discoveries. Magnetars enthusiasts are well positioned to enjoy the next few decades.
Acknowledgments PE and NR acknowledge funding in the framework of the NWO Vidi award
A.2320.0076.
References
1. D.N. Aguilera, J.A. Pons, J.A. Miralles, 2D Cooling of magnetized neutron stars. Astron.
Astrophys. 486, 255–271 (2008). https://doi.org/10.1051/0004-6361:20078786
2. J. Aleksi´ c, L.A. Antonelli, P. Antoranz, M. Asensio, U. Barres de Almeida, J.A. Barrio,
J. Becerra González, W. Bednarek, K. Berger, E. Bernardini, A. Biland, O. Blanch, R.K.
Bock, A. Boller, G. Bonnoli, D. Borla Tridon, T. Bretz, E. Carmona, A. Carosi, P. Colin,
E. Colombo, J.L. Contreras, J. Cortina, L. Cossio, S. Covino, P. Da Vela, F. Dazzi, A. De
Angelis, G. De Caneva, E. De Cea del Pozo, B. De Lotto, C. Delgado Mendez, A. Diago
Ortega, M. Doert, D. Dominis Prester, D. Dorner, M. Doro, D. Eisenacher, D. Elsaesser,
D. Ferenc, M.V. Fonseca, L. Font, C. Fruck, R.J. García López, M. Garczarczyk, D. Garrido
Terrats, M. Gaug, G. Giavitto, N. Godinovi´ c, A. González Muñoz, S.R. Gozzini, A. Hadamek,
D. Hadasch, D. Häfner, A. Herrero, J. Hose, D. Hrupec, B. Huber, F. Jankowski, T. Jogler,
V. Kadenius, S. Klepser, M.L. Knoetig, T. Krähenbühl, J. Krause, J. Kushida, A. La
Barbera, D. Lelas, E. Leonardo, N. Lewandowska, E. Lindfors, S. Lombardi, M. López,
R. López-Coto, A. López-Oramas, E. Lorenz, M. Makariev, G. Maneva, N. Mankuzhiyil,