Letters of Intent received in 2015

LoI 2017-274
Magnetars and Beyond: The Quest for a Unified Neutron Star Scenario

Topics

- Galactic neutron stars, population synthesis.
- Links among diverse neutron star classes.
- Magneto-thermal evolution of neutron stars.
- Neutron stars magnetic field.
- Multiwavelength magnetar observations.
- Magnetar formation and their progenitors.
- Magnetar magnetospheres.
- Neutron stars as sources of gravitational waves.
- Magnetar-GRB connection.
- Future perspectives, missions and observational facilities

Rationale

Neutron stars are born when a massive star ends its life in a core-collapse supernova explosion. All the physical conditions in these objects are extreme. With central densities 5-10 times larger than the nuclear density, they represent one of the densest forms of matter in the universe. Moreover, neutron stars are the strongest known magnets. Their surface magnetic field, normally in the TeraGauss range, may reach values 1000 times higher in the so-called "magnetars", largely exceeding the critical field above which effects of nonlinear quantum electrodynamics become important. Therefore, neutron stars provide excellent laboratories to probe the properties of matter under conditions that can not be reproduced in ground-based experiments, or met in other astrophysical environments.
Multi-wavelength observations have changed dramatically our vision of neutron stars, very much the same way a panchromatic view of the world compares to a black and white one. Originally discovered as pulsars, Isolated Neutron Stars (INSs) have now been observed across the entire electromagnetic spectrum, up to high-energy gamma-rays, and they exhibit a complex and much diverse phenomenology. In particular, high energy observations unveiled peculiar classes of radio silent INSs, whose existence would have passed unnoticed otherwise, e.g. the Soft Gamma Repeaters (SGRs), Anomalous X-ray Pulsars (AXPs), Central Compact Objects (CCOs) in supernova remnants and X-ray Dim Isolated Neutron Stars (XDINSs).
It is presently unknown whether the phenomenology we observe in these different sources and our classification thereof reflects differences in intrinsic properties (for example progenitors with different masses, or different spin periods and/or magnetic field strengths at birth) or is a consequence of evolution. Explaining the different INSs manifestations, the physics behind them, and the relations among different INSs types is one of the most challenging goals in compact objects astrophysics and offers the key to the ultimate understanding of the endpoints of massive star evolution.
The most extreme INS subgroup is that of AXPs and SGRs. Both these types of sources undergo periods of erratic bursting activity, and the latter even emit giant flares, hyper-energetic events which can outshine for a fraction of a second the entire Galaxy. There is strong evidence that these flares excite torsional mode oscillations in the neutron star crust that could provide unique insight into the equation of state of these highly-magnetized stars. These sources are, in fact, currently believed to be the strongest magnets in the cosmos, hosting NSs with a magnetic field as large as B~1E14- 1E15 G. More than 30 years elapsed since the first spectacular giant flare was detected on March 5th 1979 from SGR 0526-66, the first observational indication of the existence of a magnetar. Since then, the neutron star research, both observational and theoretical, has flourished. In particular, the advent of the latest generation space- and ground-based observatories has largely impacted on our knowledge of magnetars and other classes of neutron stars. All these objects are now studied in the whole electromagnetic spectrum, with ground-based radio, optical and infrared telescopes, and with the latest X-ray and Gamma ray observatories (including INTEGRAL, Chandra, XMM-Newton, Swift, Suzaku, NuSTAR, Fermi and AGILE).
For all these reasons it is our opinion that the time is ripe for gathering together both observers and theoreticians working in this field, in a meeting that will focus on breakthrough research linking astrophysics, particle physics and condensed matter physics. In this respect, we believe an IAU meeting is an ideal framework, offering a stimulating environment to review the current state of the art, to promote fruitful collaborations and discuss future perspectives in the post-XMM/Chandra/Swift era, also in view of the launch of Astro-H, NICER and Athena+ among the confirmed high energy missions, and the forthcoming multiwavelength facilities such as, among others, SKA, CTA, E-ELT, and advanced LIGO/VIRGO.

Confirmed SOC members are: GianLuca Israel (Italy), Roberto Turolla (Italy), Silvia Zane (UK), Nanda Rea (Spain/Netherlands), Metthew Baring (USA), Dong Lai (USA), Samar Safi-Harb (Canada), Jeremy Heyl (Canada), Maxim Lyutikov (USA), Dima Yakovlev (Russian Federation), Sandro Mereghetti (Italy), Rosalba Perna (USA), Chryssa Kouveliotou (USA).