Magnetars.

Diagram from 1994

Magnetars, High B field Pulsars unknown!

From Kaplan (PhD 2004)

This is a P-Pdot diagram and not B-PBut B2 proportional to P x Pdot

Reviews

There are no major reviews but try the following:• Kaspi (astroph/0402175)• Hurley (astroph/9912061)• Paczynski (1992, Acta Astronomica)• Baring (1991, A&A)

The classic set of papers in this field are • Thompson & Duncan (1995, MNRAS)• Thompson & Duncan (1996, ApJ)

Giant Burst from SGR 1900+14 (August 1998)

Giant Burst of August 1998

• Peak Luminosity of short spike, 1045 erg/s

• Energy in the hard spike, 1044 erg

• Total Energy radiated, 1045 erg

(not including neutrinos)

The luminosity exceeds LEddington

A strong B field reduces Thomson cross-section

Paczynski 1992

where the cyclotron energy

QED effects become important for BQED > 4.3x1013 G (electron rest mass)and photons with energy of 511 keV

Hurley

Anomalous X-ray Pulsars

• Periods in the range 5-20 s

• No companion (either through reflex motion or as optical/IR counterpart)

• Luminous X-ray sources (4U 0142+64)

• But Pdot not sufficient to power LX (see Table)

• Hence the name

Bursts from 1E2259+586

Kaspi

Conclusions

• Soft gamma-ray repeaters and anomalous X-ray pulsars are highly magnetized neutron stars

• The relationship between the two classes is unknown (is one descendent of the other?)

• High B field radio pulsars (1014 G) appear to be different from magnetars. Something in the interior does care about 1014 G.

Why are magnetars of some interest?

• Some have argued that the birth (hot convective core) results in a magnetar. In any case at least magnetars constitute about 10% of the birthrate.

• Magnetars have been suggested to be the central sources for GRBs

• Exotic QED Phenomena (Photon splitting & Vacuum Polarization; see Baring paper)