The greatest flare of a Soft Gamma Repeater

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The greatest flare of a Soft Gamma Repeater

• On December 27 2004 the greatest flare from SGR
  1806-20 was detected by many satellites Swift,
  RHESSI, Konus-Wind, Coronas-F, Integral, HEND,
• 100 times brighter than ever!

Palmer et al. Astro-ph/0503030
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Magnetars in the Galaxy

• 4 SGRs, 8 AXPs, plus candidates, plus radio
  pulsars with high magnetic fields
• Young objects (about 104 yrs).
• Probably about 10 of all NSs.

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Alternative theory

• Fossil disk
• Mereghetti, Stella 1995
• Van Paradijs et al.1995
• Alpar 2001
• Marsden et al. 2001
• Problems ..
• How to generate strong bursts?

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Why magnetars?

• dE/dt gt dErot/dt
• By definition magnetically-powered NSs
• P-Pdot
• Direct field measurements (Ibrahim et al.)

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Known magnetars

• AXPs
• CXOU 010043.1-72
• 4U 014261
• 1E 1048.15937
• 1 RXS J170849-40
• XTE J1810-197
• 1E 1841-045
• AX J1844-0258
• 1E 2259586

• SGRs
• 0526-66
• 1627-41
• 1806-20
• 190014
• candidates

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Magnetic field measurements

• Direct measurement of the magnetic field of the
  SGR
• Spin-down
• Long periods

Ibrahim et al. 2002
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Are SGRs and AXPs relatives?

• SGR-like bursts from AXPs
• Spectral properties
• Quiet periods of SGRs (0525-66 since 1983)

Gavriil et al. 2002
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Historical notes

• 05 March 1979. Cone experiment. Venera-11,12
  (Mazets et al.)
• Event in LMC. SGR 0520-66.
• Fluence about 10-3 erg/cm2

Mazets et al. 1979
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Main types of activity of SGRs

• Weak burst. Llt1041 erg/s
• Intermed. bursts.L10411043 erg/s
• Giant bursts. Llt1045 erg/s
• Hyperflares. Lgt1046 erg/s

See a review in Woods, Thompson astro-ph/0406133
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Common (weak) bursts from SGRS and AXPs

• Typical burst from SGR 1806-29, SGR 190014 and
  from AXP 1E 2259586 observed by RXTE (from
  Woods, Thompson, 2004, astro-ph/0406133)

(from Woods, Thompson 2004)
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Intermediate SGR bursts

• Four intermediate bursts. However, the forth is
  sometimes considered as a giant one (from Woods,
  Thompson)

(from Woods, Thompson 2004)
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Giant flare from SGR 190014 (27 Aug 1998)

• Data from Ulysses (figure from Hurley et al.
  1999a)
• Spike 0.35 sec
• P5.16 sec
• Lgt3 1044 erg/s
• ETOTALgt1044 erg
• Influenced the Earth ionosphere

Hurley et al. 1999
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27 Dec 2004 giant outburst of SGR 1806-20

• Spike 0.2 sec
• Fluence 1 erg/cm2
• E(spike)3.5 1046 erg
• L(spike)1.8 1047 erg/s
• Long tail (400 s)
• P7.65 s
• E(tail) 1.6 1044 erg
• Distance 15 kpc

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Konus-Wind data om SGR 1806-20 27 Dec 2004 flare
Mazets et al. 2005
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SGR giant flares vs. GRBs
Woods et al.
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SGRs and starformation

• Possibility of a SGR detection outside the Local
  group of galaxies
• Starforming galaxies are the best sites for a
  search
• lt5 Mpc. M82, M83, NGC 253
• About 40 Mpc. Arp 299, NGC 3256
• Possible candidates in the BATSE catalogue of
  short GRBs

(Popov, Stern 2005)
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Theory of magnetars

• Thompson, Duncan ApJ 408, 194 (1993)
• Entropy-driven convection in young NSs generate
  strong magnetic field
• Twist of magnetic field lines

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Magnetars origin(a speculative discussion)

• Fast rotation is necessary (Thompson, Duncan)
• Spin-up of a progenitor star in a binary via
  accretion or synchronization
• Coalescence
• About 10 of NSs (Popov, Prokhorov 2005)