wolfang kundt magnetar.ppt [read-only]€¦ · : a magnetar is a strongly torqued neutron star (by...
TRANSCRIPT
![Page 1: wolfang kundt magnetar.ppt [Read-Only]€¦ · : A MAGNETAR is a strongly torqued neutron star (by a low-mass accretion disk), powered by accretion ( & spin-down), with B s ℵ 1014](https://reader033.vdocuments.mx/reader033/viewer/2022043006/5f90fea03f948a592d4f80b9/html5/thumbnails/1.jpg)
MAGNETARS
Wolfgang Kundt
Bonn University
Vulcano, 31. 5. 2007
![Page 2: wolfang kundt magnetar.ppt [Read-Only]€¦ · : A MAGNETAR is a strongly torqued neutron star (by a low-mass accretion disk), powered by accretion ( & spin-down), with B s ℵ 1014](https://reader033.vdocuments.mx/reader033/viewer/2022043006/5f90fea03f948a592d4f80b9/html5/thumbnails/2.jpg)
MAGNETARS have DIFFICULTIES
• DEF.: A Magnetar is a spinning, compact X-ray source – probably a neutronstar – powered by a strong, decaying magnetic moment µ, (Bs ℑ 1015 G);[proposed by: R.C. Duncan & C. Thompson, 1992-96].
• CANDIDATES: AXPs, SGRs, Rotating Radio Transients, Stammerers.
• CLAIM: such sources do not exist; should be replaced by `throttled PSRs´.
• DIFFICULTIES:
(1) Such strong Bs would imply Bi ℵ 1017 G in the core, at r ℵ R/2 ; they are
dynamically unstable.
(2) No plausible formation mode is known.(3) The SGRs 1900+14 & 1806-20 had glitches with Δ(dP/dt)>0. (4)Above candidates can be explained differently, in a consistent way.
![Page 3: wolfang kundt magnetar.ppt [Read-Only]€¦ · : A MAGNETAR is a strongly torqued neutron star (by a low-mass accretion disk), powered by accretion ( & spin-down), with B s ℵ 1014](https://reader033.vdocuments.mx/reader033/viewer/2022043006/5f90fea03f948a592d4f80b9/html5/thumbnails/3.jpg)
PREFERRED DEFINITION
• Def.: A MAGNETAR is a strongly torqued neutron star (bya low-mass accretion disk), powered by accretion ( & spin-down), with Bs ℵ 1014 G, a `throttled pulsar´, usually old,but occasionally very young.
• PROPERTIES:(1) Its (spin) period P is usually ∈(5, 12)s , as for the
dying pulsars, (occasionally unknown).(2) Its spindown torque T ≈ r_ <Br Bϕ > tends to be several
10_ times stronger than the (unconfined) pulsar torque. (3) Its accretion power is LX ℵ 1036 erg/s. (4) It is often found inside of a Pulsar Nebula.
![Page 4: wolfang kundt magnetar.ppt [Read-Only]€¦ · : A MAGNETAR is a strongly torqued neutron star (by a low-mass accretion disk), powered by accretion ( & spin-down), with B s ℵ 1014](https://reader033.vdocuments.mx/reader033/viewer/2022043006/5f90fea03f948a592d4f80b9/html5/thumbnails/4.jpg)
Are the Magnetars
a subset of all (ordinary)
Pulsars,
comprising the AXPs, the SGRs,the `stammerers´ (= RRATs),
the CR-boosters, and
even all the GR-bursters ?
![Page 5: wolfang kundt magnetar.ppt [Read-Only]€¦ · : A MAGNETAR is a strongly torqued neutron star (by a low-mass accretion disk), powered by accretion ( & spin-down), with B s ℵ 1014](https://reader033.vdocuments.mx/reader033/viewer/2022043006/5f90fea03f948a592d4f80b9/html5/thumbnails/5.jpg)
![Page 6: wolfang kundt magnetar.ppt [Read-Only]€¦ · : A MAGNETAR is a strongly torqued neutron star (by a low-mass accretion disk), powered by accretion ( & spin-down), with B s ℵ 1014](https://reader033.vdocuments.mx/reader033/viewer/2022043006/5f90fea03f948a592d4f80b9/html5/thumbnails/6.jpg)
![Page 7: wolfang kundt magnetar.ppt [Read-Only]€¦ · : A MAGNETAR is a strongly torqued neutron star (by a low-mass accretion disk), powered by accretion ( & spin-down), with B s ℵ 1014](https://reader033.vdocuments.mx/reader033/viewer/2022043006/5f90fea03f948a592d4f80b9/html5/thumbnails/7.jpg)
![Page 8: wolfang kundt magnetar.ppt [Read-Only]€¦ · : A MAGNETAR is a strongly torqued neutron star (by a low-mass accretion disk), powered by accretion ( & spin-down), with B s ℵ 1014](https://reader033.vdocuments.mx/reader033/viewer/2022043006/5f90fea03f948a592d4f80b9/html5/thumbnails/8.jpg)
![Page 9: wolfang kundt magnetar.ppt [Read-Only]€¦ · : A MAGNETAR is a strongly torqued neutron star (by a low-mass accretion disk), powered by accretion ( & spin-down), with B s ℵ 1014](https://reader033.vdocuments.mx/reader033/viewer/2022043006/5f90fea03f948a592d4f80b9/html5/thumbnails/9.jpg)
![Page 10: wolfang kundt magnetar.ppt [Read-Only]€¦ · : A MAGNETAR is a strongly torqued neutron star (by a low-mass accretion disk), powered by accretion ( & spin-down), with B s ℵ 1014](https://reader033.vdocuments.mx/reader033/viewer/2022043006/5f90fea03f948a592d4f80b9/html5/thumbnails/10.jpg)
CONFIRMING EVIDENCE
Indeed, the new interpretation (of the magnetars)completes our understanding of the late stages ofpulsars: Once their wind pressure pw ~ 1/P∃ fallsbelow circumstellar values, the wind-blown cavity– of radius some 1015 cm – collapses, and forms alow-mass accretion disk (M ℵ10-6 M) around thedying PSR, confining ist magnetosphere, andstrongly enhancing ist spindown ...
![Page 11: wolfang kundt magnetar.ppt [Read-Only]€¦ · : A MAGNETAR is a strongly torqued neutron star (by a low-mass accretion disk), powered by accretion ( & spin-down), with B s ℵ 1014](https://reader033.vdocuments.mx/reader033/viewer/2022043006/5f90fea03f948a592d4f80b9/html5/thumbnails/11.jpg)
• The disk´s inner edge cuts into the PSR´s corotat-ing magnetosphere, which acts like a ring ofrelativistic slingshots during their sawtooth-shaped torsional oscillations, generating cosmicrays. Occasionally, clumps from the disk´s inneredge accrete onto the n*´s surface, giving rise toGRBs. The nearest (and loudest) of them are seenas SGRs.
• Very young PSRs, like the Crab and the Vela, areseen to be likewise surrounded by circum-PSRlow-mass CSM, giving rise to strong X-radiation,and (invisible) CRs. These few, young PSRs ofhigh spin rate create (at least) the sparse, mostpowerful upper end of the CR spectrum.
![Page 12: wolfang kundt magnetar.ppt [Read-Only]€¦ · : A MAGNETAR is a strongly torqued neutron star (by a low-mass accretion disk), powered by accretion ( & spin-down), with B s ℵ 1014](https://reader033.vdocuments.mx/reader033/viewer/2022043006/5f90fea03f948a592d4f80b9/html5/thumbnails/12.jpg)
A FEW FORMULAE
• Pulsar´s Spin Period for marginally stable cavity: P = 8 s (µ31 T3 / √p-12.3)1/2 .
• Minimal Cavity Radius:
r = G M mp / 2 k T = 1014.9 cm / T3 .
• A throttled pulsar‘s Spindown Time: τ = 10(4 ±1) yr .
![Page 13: wolfang kundt magnetar.ppt [Read-Only]€¦ · : A MAGNETAR is a strongly torqued neutron star (by a low-mass accretion disk), powered by accretion ( & spin-down), with B s ℵ 1014](https://reader033.vdocuments.mx/reader033/viewer/2022043006/5f90fea03f948a592d4f80b9/html5/thumbnails/13.jpg)